xref: /linux/mm/page_alloc.c (revision 39f75da7bcc829ddc4d40bb60d0e95520de7898b)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/mm/page_alloc.c
4  *
5  *  Manages the free list, the system allocates free pages here.
6  *  Note that kmalloc() lives in slab.c
7  *
8  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
9  *  Swap reorganised 29.12.95, Stephen Tweedie
10  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11  *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
12  *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
13  *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
14  *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
15  *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
16  */
17 
18 #include <linux/stddef.h>
19 #include <linux/mm.h>
20 #include <linux/highmem.h>
21 #include <linux/swap.h>
22 #include <linux/interrupt.h>
23 #include <linux/pagemap.h>
24 #include <linux/jiffies.h>
25 #include <linux/memblock.h>
26 #include <linux/compiler.h>
27 #include <linux/kernel.h>
28 #include <linux/kasan.h>
29 #include <linux/module.h>
30 #include <linux/suspend.h>
31 #include <linux/pagevec.h>
32 #include <linux/blkdev.h>
33 #include <linux/slab.h>
34 #include <linux/ratelimit.h>
35 #include <linux/oom.h>
36 #include <linux/topology.h>
37 #include <linux/sysctl.h>
38 #include <linux/cpu.h>
39 #include <linux/cpuset.h>
40 #include <linux/memory_hotplug.h>
41 #include <linux/nodemask.h>
42 #include <linux/vmalloc.h>
43 #include <linux/vmstat.h>
44 #include <linux/mempolicy.h>
45 #include <linux/memremap.h>
46 #include <linux/stop_machine.h>
47 #include <linux/random.h>
48 #include <linux/sort.h>
49 #include <linux/pfn.h>
50 #include <linux/backing-dev.h>
51 #include <linux/fault-inject.h>
52 #include <linux/page-isolation.h>
53 #include <linux/debugobjects.h>
54 #include <linux/kmemleak.h>
55 #include <linux/compaction.h>
56 #include <trace/events/kmem.h>
57 #include <trace/events/oom.h>
58 #include <linux/prefetch.h>
59 #include <linux/mm_inline.h>
60 #include <linux/mmu_notifier.h>
61 #include <linux/migrate.h>
62 #include <linux/hugetlb.h>
63 #include <linux/sched/rt.h>
64 #include <linux/sched/mm.h>
65 #include <linux/page_owner.h>
66 #include <linux/kthread.h>
67 #include <linux/memcontrol.h>
68 #include <linux/ftrace.h>
69 #include <linux/lockdep.h>
70 #include <linux/nmi.h>
71 #include <linux/psi.h>
72 #include <linux/padata.h>
73 #include <linux/khugepaged.h>
74 #include <linux/buffer_head.h>
75 #include <asm/sections.h>
76 #include <asm/tlbflush.h>
77 #include <asm/div64.h>
78 #include "internal.h"
79 #include "shuffle.h"
80 #include "page_reporting.h"
81 
82 /* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
83 typedef int __bitwise fpi_t;
84 
85 /* No special request */
86 #define FPI_NONE		((__force fpi_t)0)
87 
88 /*
89  * Skip free page reporting notification for the (possibly merged) page.
90  * This does not hinder free page reporting from grabbing the page,
91  * reporting it and marking it "reported" -  it only skips notifying
92  * the free page reporting infrastructure about a newly freed page. For
93  * example, used when temporarily pulling a page from a freelist and
94  * putting it back unmodified.
95  */
96 #define FPI_SKIP_REPORT_NOTIFY	((__force fpi_t)BIT(0))
97 
98 /*
99  * Place the (possibly merged) page to the tail of the freelist. Will ignore
100  * page shuffling (relevant code - e.g., memory onlining - is expected to
101  * shuffle the whole zone).
102  *
103  * Note: No code should rely on this flag for correctness - it's purely
104  *       to allow for optimizations when handing back either fresh pages
105  *       (memory onlining) or untouched pages (page isolation, free page
106  *       reporting).
107  */
108 #define FPI_TO_TAIL		((__force fpi_t)BIT(1))
109 
110 /*
111  * Don't poison memory with KASAN (only for the tag-based modes).
112  * During boot, all non-reserved memblock memory is exposed to page_alloc.
113  * Poisoning all that memory lengthens boot time, especially on systems with
114  * large amount of RAM. This flag is used to skip that poisoning.
115  * This is only done for the tag-based KASAN modes, as those are able to
116  * detect memory corruptions with the memory tags assigned by default.
117  * All memory allocated normally after boot gets poisoned as usual.
118  */
119 #define FPI_SKIP_KASAN_POISON	((__force fpi_t)BIT(2))
120 
121 /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
122 static DEFINE_MUTEX(pcp_batch_high_lock);
123 #define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8)
124 
125 struct pagesets {
126 	local_lock_t lock;
127 };
128 static DEFINE_PER_CPU(struct pagesets, pagesets) = {
129 	.lock = INIT_LOCAL_LOCK(lock),
130 };
131 
132 #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
133 DEFINE_PER_CPU(int, numa_node);
134 EXPORT_PER_CPU_SYMBOL(numa_node);
135 #endif
136 
137 DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
138 
139 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
140 /*
141  * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
142  * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
143  * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
144  * defined in <linux/topology.h>.
145  */
146 DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
147 EXPORT_PER_CPU_SYMBOL(_numa_mem_);
148 #endif
149 
150 /* work_structs for global per-cpu drains */
151 struct pcpu_drain {
152 	struct zone *zone;
153 	struct work_struct work;
154 };
155 static DEFINE_MUTEX(pcpu_drain_mutex);
156 static DEFINE_PER_CPU(struct pcpu_drain, pcpu_drain);
157 
158 #ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
159 volatile unsigned long latent_entropy __latent_entropy;
160 EXPORT_SYMBOL(latent_entropy);
161 #endif
162 
163 /*
164  * Array of node states.
165  */
166 nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
167 	[N_POSSIBLE] = NODE_MASK_ALL,
168 	[N_ONLINE] = { { [0] = 1UL } },
169 #ifndef CONFIG_NUMA
170 	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
171 #ifdef CONFIG_HIGHMEM
172 	[N_HIGH_MEMORY] = { { [0] = 1UL } },
173 #endif
174 	[N_MEMORY] = { { [0] = 1UL } },
175 	[N_CPU] = { { [0] = 1UL } },
176 #endif	/* NUMA */
177 };
178 EXPORT_SYMBOL(node_states);
179 
180 atomic_long_t _totalram_pages __read_mostly;
181 EXPORT_SYMBOL(_totalram_pages);
182 unsigned long totalreserve_pages __read_mostly;
183 unsigned long totalcma_pages __read_mostly;
184 
185 int percpu_pagelist_high_fraction;
186 gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
187 DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
188 EXPORT_SYMBOL(init_on_alloc);
189 
190 DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free);
191 EXPORT_SYMBOL(init_on_free);
192 
193 static bool _init_on_alloc_enabled_early __read_mostly
194 				= IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON);
195 static int __init early_init_on_alloc(char *buf)
196 {
197 
198 	return kstrtobool(buf, &_init_on_alloc_enabled_early);
199 }
200 early_param("init_on_alloc", early_init_on_alloc);
201 
202 static bool _init_on_free_enabled_early __read_mostly
203 				= IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON);
204 static int __init early_init_on_free(char *buf)
205 {
206 	return kstrtobool(buf, &_init_on_free_enabled_early);
207 }
208 early_param("init_on_free", early_init_on_free);
209 
210 /*
211  * A cached value of the page's pageblock's migratetype, used when the page is
212  * put on a pcplist. Used to avoid the pageblock migratetype lookup when
213  * freeing from pcplists in most cases, at the cost of possibly becoming stale.
214  * Also the migratetype set in the page does not necessarily match the pcplist
215  * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
216  * other index - this ensures that it will be put on the correct CMA freelist.
217  */
218 static inline int get_pcppage_migratetype(struct page *page)
219 {
220 	return page->index;
221 }
222 
223 static inline void set_pcppage_migratetype(struct page *page, int migratetype)
224 {
225 	page->index = migratetype;
226 }
227 
228 #ifdef CONFIG_PM_SLEEP
229 /*
230  * The following functions are used by the suspend/hibernate code to temporarily
231  * change gfp_allowed_mask in order to avoid using I/O during memory allocations
232  * while devices are suspended.  To avoid races with the suspend/hibernate code,
233  * they should always be called with system_transition_mutex held
234  * (gfp_allowed_mask also should only be modified with system_transition_mutex
235  * held, unless the suspend/hibernate code is guaranteed not to run in parallel
236  * with that modification).
237  */
238 
239 static gfp_t saved_gfp_mask;
240 
241 void pm_restore_gfp_mask(void)
242 {
243 	WARN_ON(!mutex_is_locked(&system_transition_mutex));
244 	if (saved_gfp_mask) {
245 		gfp_allowed_mask = saved_gfp_mask;
246 		saved_gfp_mask = 0;
247 	}
248 }
249 
250 void pm_restrict_gfp_mask(void)
251 {
252 	WARN_ON(!mutex_is_locked(&system_transition_mutex));
253 	WARN_ON(saved_gfp_mask);
254 	saved_gfp_mask = gfp_allowed_mask;
255 	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
256 }
257 
258 bool pm_suspended_storage(void)
259 {
260 	if ((gfp_allowed_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
261 		return false;
262 	return true;
263 }
264 #endif /* CONFIG_PM_SLEEP */
265 
266 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
267 unsigned int pageblock_order __read_mostly;
268 #endif
269 
270 static void __free_pages_ok(struct page *page, unsigned int order,
271 			    fpi_t fpi_flags);
272 
273 /*
274  * results with 256, 32 in the lowmem_reserve sysctl:
275  *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
276  *	1G machine -> (16M dma, 784M normal, 224M high)
277  *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
278  *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
279  *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
280  *
281  * TBD: should special case ZONE_DMA32 machines here - in those we normally
282  * don't need any ZONE_NORMAL reservation
283  */
284 int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
285 #ifdef CONFIG_ZONE_DMA
286 	[ZONE_DMA] = 256,
287 #endif
288 #ifdef CONFIG_ZONE_DMA32
289 	[ZONE_DMA32] = 256,
290 #endif
291 	[ZONE_NORMAL] = 32,
292 #ifdef CONFIG_HIGHMEM
293 	[ZONE_HIGHMEM] = 0,
294 #endif
295 	[ZONE_MOVABLE] = 0,
296 };
297 
298 static char * const zone_names[MAX_NR_ZONES] = {
299 #ifdef CONFIG_ZONE_DMA
300 	 "DMA",
301 #endif
302 #ifdef CONFIG_ZONE_DMA32
303 	 "DMA32",
304 #endif
305 	 "Normal",
306 #ifdef CONFIG_HIGHMEM
307 	 "HighMem",
308 #endif
309 	 "Movable",
310 #ifdef CONFIG_ZONE_DEVICE
311 	 "Device",
312 #endif
313 };
314 
315 const char * const migratetype_names[MIGRATE_TYPES] = {
316 	"Unmovable",
317 	"Movable",
318 	"Reclaimable",
319 	"HighAtomic",
320 #ifdef CONFIG_CMA
321 	"CMA",
322 #endif
323 #ifdef CONFIG_MEMORY_ISOLATION
324 	"Isolate",
325 #endif
326 };
327 
328 compound_page_dtor * const compound_page_dtors[NR_COMPOUND_DTORS] = {
329 	[NULL_COMPOUND_DTOR] = NULL,
330 	[COMPOUND_PAGE_DTOR] = free_compound_page,
331 #ifdef CONFIG_HUGETLB_PAGE
332 	[HUGETLB_PAGE_DTOR] = free_huge_page,
333 #endif
334 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
335 	[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
336 #endif
337 };
338 
339 int min_free_kbytes = 1024;
340 int user_min_free_kbytes = -1;
341 int watermark_boost_factor __read_mostly = 15000;
342 int watermark_scale_factor = 10;
343 
344 static unsigned long nr_kernel_pages __initdata;
345 static unsigned long nr_all_pages __initdata;
346 static unsigned long dma_reserve __initdata;
347 
348 static unsigned long arch_zone_lowest_possible_pfn[MAX_NR_ZONES] __initdata;
349 static unsigned long arch_zone_highest_possible_pfn[MAX_NR_ZONES] __initdata;
350 static unsigned long required_kernelcore __initdata;
351 static unsigned long required_kernelcore_percent __initdata;
352 static unsigned long required_movablecore __initdata;
353 static unsigned long required_movablecore_percent __initdata;
354 static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
355 static bool mirrored_kernelcore __meminitdata;
356 
357 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
358 int movable_zone;
359 EXPORT_SYMBOL(movable_zone);
360 
361 #if MAX_NUMNODES > 1
362 unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
363 unsigned int nr_online_nodes __read_mostly = 1;
364 EXPORT_SYMBOL(nr_node_ids);
365 EXPORT_SYMBOL(nr_online_nodes);
366 #endif
367 
368 int page_group_by_mobility_disabled __read_mostly;
369 
370 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
371 /*
372  * During boot we initialize deferred pages on-demand, as needed, but once
373  * page_alloc_init_late() has finished, the deferred pages are all initialized,
374  * and we can permanently disable that path.
375  */
376 static DEFINE_STATIC_KEY_TRUE(deferred_pages);
377 
378 /*
379  * Calling kasan_poison_pages() only after deferred memory initialization
380  * has completed. Poisoning pages during deferred memory init will greatly
381  * lengthen the process and cause problem in large memory systems as the
382  * deferred pages initialization is done with interrupt disabled.
383  *
384  * Assuming that there will be no reference to those newly initialized
385  * pages before they are ever allocated, this should have no effect on
386  * KASAN memory tracking as the poison will be properly inserted at page
387  * allocation time. The only corner case is when pages are allocated by
388  * on-demand allocation and then freed again before the deferred pages
389  * initialization is done, but this is not likely to happen.
390  */
391 static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
392 {
393 	return static_branch_unlikely(&deferred_pages) ||
394 	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
395 		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
396 	       PageSkipKASanPoison(page);
397 }
398 
399 /* Returns true if the struct page for the pfn is uninitialised */
400 static inline bool __meminit early_page_uninitialised(unsigned long pfn)
401 {
402 	int nid = early_pfn_to_nid(pfn);
403 
404 	if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
405 		return true;
406 
407 	return false;
408 }
409 
410 /*
411  * Returns true when the remaining initialisation should be deferred until
412  * later in the boot cycle when it can be parallelised.
413  */
414 static bool __meminit
415 defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
416 {
417 	static unsigned long prev_end_pfn, nr_initialised;
418 
419 	/*
420 	 * prev_end_pfn static that contains the end of previous zone
421 	 * No need to protect because called very early in boot before smp_init.
422 	 */
423 	if (prev_end_pfn != end_pfn) {
424 		prev_end_pfn = end_pfn;
425 		nr_initialised = 0;
426 	}
427 
428 	/* Always populate low zones for address-constrained allocations */
429 	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
430 		return false;
431 
432 	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
433 		return true;
434 	/*
435 	 * We start only with one section of pages, more pages are added as
436 	 * needed until the rest of deferred pages are initialized.
437 	 */
438 	nr_initialised++;
439 	if ((nr_initialised > PAGES_PER_SECTION) &&
440 	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
441 		NODE_DATA(nid)->first_deferred_pfn = pfn;
442 		return true;
443 	}
444 	return false;
445 }
446 #else
447 static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
448 {
449 	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
450 		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
451 	       PageSkipKASanPoison(page);
452 }
453 
454 static inline bool early_page_uninitialised(unsigned long pfn)
455 {
456 	return false;
457 }
458 
459 static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
460 {
461 	return false;
462 }
463 #endif
464 
465 /* Return a pointer to the bitmap storing bits affecting a block of pages */
466 static inline unsigned long *get_pageblock_bitmap(const struct page *page,
467 							unsigned long pfn)
468 {
469 #ifdef CONFIG_SPARSEMEM
470 	return section_to_usemap(__pfn_to_section(pfn));
471 #else
472 	return page_zone(page)->pageblock_flags;
473 #endif /* CONFIG_SPARSEMEM */
474 }
475 
476 static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
477 {
478 #ifdef CONFIG_SPARSEMEM
479 	pfn &= (PAGES_PER_SECTION-1);
480 #else
481 	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
482 #endif /* CONFIG_SPARSEMEM */
483 	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
484 }
485 
486 static __always_inline
487 unsigned long __get_pfnblock_flags_mask(const struct page *page,
488 					unsigned long pfn,
489 					unsigned long mask)
490 {
491 	unsigned long *bitmap;
492 	unsigned long bitidx, word_bitidx;
493 	unsigned long word;
494 
495 	bitmap = get_pageblock_bitmap(page, pfn);
496 	bitidx = pfn_to_bitidx(page, pfn);
497 	word_bitidx = bitidx / BITS_PER_LONG;
498 	bitidx &= (BITS_PER_LONG-1);
499 
500 	word = bitmap[word_bitidx];
501 	return (word >> bitidx) & mask;
502 }
503 
504 /**
505  * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
506  * @page: The page within the block of interest
507  * @pfn: The target page frame number
508  * @mask: mask of bits that the caller is interested in
509  *
510  * Return: pageblock_bits flags
511  */
512 unsigned long get_pfnblock_flags_mask(const struct page *page,
513 					unsigned long pfn, unsigned long mask)
514 {
515 	return __get_pfnblock_flags_mask(page, pfn, mask);
516 }
517 
518 static __always_inline int get_pfnblock_migratetype(const struct page *page,
519 					unsigned long pfn)
520 {
521 	return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
522 }
523 
524 /**
525  * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
526  * @page: The page within the block of interest
527  * @flags: The flags to set
528  * @pfn: The target page frame number
529  * @mask: mask of bits that the caller is interested in
530  */
531 void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
532 					unsigned long pfn,
533 					unsigned long mask)
534 {
535 	unsigned long *bitmap;
536 	unsigned long bitidx, word_bitidx;
537 	unsigned long old_word, word;
538 
539 	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
540 	BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
541 
542 	bitmap = get_pageblock_bitmap(page, pfn);
543 	bitidx = pfn_to_bitidx(page, pfn);
544 	word_bitidx = bitidx / BITS_PER_LONG;
545 	bitidx &= (BITS_PER_LONG-1);
546 
547 	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
548 
549 	mask <<= bitidx;
550 	flags <<= bitidx;
551 
552 	word = READ_ONCE(bitmap[word_bitidx]);
553 	for (;;) {
554 		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
555 		if (word == old_word)
556 			break;
557 		word = old_word;
558 	}
559 }
560 
561 void set_pageblock_migratetype(struct page *page, int migratetype)
562 {
563 	if (unlikely(page_group_by_mobility_disabled &&
564 		     migratetype < MIGRATE_PCPTYPES))
565 		migratetype = MIGRATE_UNMOVABLE;
566 
567 	set_pfnblock_flags_mask(page, (unsigned long)migratetype,
568 				page_to_pfn(page), MIGRATETYPE_MASK);
569 }
570 
571 #ifdef CONFIG_DEBUG_VM
572 static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
573 {
574 	int ret = 0;
575 	unsigned seq;
576 	unsigned long pfn = page_to_pfn(page);
577 	unsigned long sp, start_pfn;
578 
579 	do {
580 		seq = zone_span_seqbegin(zone);
581 		start_pfn = zone->zone_start_pfn;
582 		sp = zone->spanned_pages;
583 		if (!zone_spans_pfn(zone, pfn))
584 			ret = 1;
585 	} while (zone_span_seqretry(zone, seq));
586 
587 	if (ret)
588 		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
589 			pfn, zone_to_nid(zone), zone->name,
590 			start_pfn, start_pfn + sp);
591 
592 	return ret;
593 }
594 
595 static int page_is_consistent(struct zone *zone, struct page *page)
596 {
597 	if (!pfn_valid_within(page_to_pfn(page)))
598 		return 0;
599 	if (zone != page_zone(page))
600 		return 0;
601 
602 	return 1;
603 }
604 /*
605  * Temporary debugging check for pages not lying within a given zone.
606  */
607 static int __maybe_unused bad_range(struct zone *zone, struct page *page)
608 {
609 	if (page_outside_zone_boundaries(zone, page))
610 		return 1;
611 	if (!page_is_consistent(zone, page))
612 		return 1;
613 
614 	return 0;
615 }
616 #else
617 static inline int __maybe_unused bad_range(struct zone *zone, struct page *page)
618 {
619 	return 0;
620 }
621 #endif
622 
623 static void bad_page(struct page *page, const char *reason)
624 {
625 	static unsigned long resume;
626 	static unsigned long nr_shown;
627 	static unsigned long nr_unshown;
628 
629 	/*
630 	 * Allow a burst of 60 reports, then keep quiet for that minute;
631 	 * or allow a steady drip of one report per second.
632 	 */
633 	if (nr_shown == 60) {
634 		if (time_before(jiffies, resume)) {
635 			nr_unshown++;
636 			goto out;
637 		}
638 		if (nr_unshown) {
639 			pr_alert(
640 			      "BUG: Bad page state: %lu messages suppressed\n",
641 				nr_unshown);
642 			nr_unshown = 0;
643 		}
644 		nr_shown = 0;
645 	}
646 	if (nr_shown++ == 0)
647 		resume = jiffies + 60 * HZ;
648 
649 	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
650 		current->comm, page_to_pfn(page));
651 	dump_page(page, reason);
652 
653 	print_modules();
654 	dump_stack();
655 out:
656 	/* Leave bad fields for debug, except PageBuddy could make trouble */
657 	page_mapcount_reset(page); /* remove PageBuddy */
658 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
659 }
660 
661 static inline unsigned int order_to_pindex(int migratetype, int order)
662 {
663 	int base = order;
664 
665 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
666 	if (order > PAGE_ALLOC_COSTLY_ORDER) {
667 		VM_BUG_ON(order != pageblock_order);
668 		base = PAGE_ALLOC_COSTLY_ORDER + 1;
669 	}
670 #else
671 	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
672 #endif
673 
674 	return (MIGRATE_PCPTYPES * base) + migratetype;
675 }
676 
677 static inline int pindex_to_order(unsigned int pindex)
678 {
679 	int order = pindex / MIGRATE_PCPTYPES;
680 
681 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
682 	if (order > PAGE_ALLOC_COSTLY_ORDER) {
683 		order = pageblock_order;
684 		VM_BUG_ON(order != pageblock_order);
685 	}
686 #else
687 	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
688 #endif
689 
690 	return order;
691 }
692 
693 static inline bool pcp_allowed_order(unsigned int order)
694 {
695 	if (order <= PAGE_ALLOC_COSTLY_ORDER)
696 		return true;
697 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
698 	if (order == pageblock_order)
699 		return true;
700 #endif
701 	return false;
702 }
703 
704 static inline void free_the_page(struct page *page, unsigned int order)
705 {
706 	if (pcp_allowed_order(order))		/* Via pcp? */
707 		free_unref_page(page, order);
708 	else
709 		__free_pages_ok(page, order, FPI_NONE);
710 }
711 
712 /*
713  * Higher-order pages are called "compound pages".  They are structured thusly:
714  *
715  * The first PAGE_SIZE page is called the "head page" and have PG_head set.
716  *
717  * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
718  * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
719  *
720  * The first tail page's ->compound_dtor holds the offset in array of compound
721  * page destructors. See compound_page_dtors.
722  *
723  * The first tail page's ->compound_order holds the order of allocation.
724  * This usage means that zero-order pages may not be compound.
725  */
726 
727 void free_compound_page(struct page *page)
728 {
729 	mem_cgroup_uncharge(page);
730 	free_the_page(page, compound_order(page));
731 }
732 
733 void prep_compound_page(struct page *page, unsigned int order)
734 {
735 	int i;
736 	int nr_pages = 1 << order;
737 
738 	__SetPageHead(page);
739 	for (i = 1; i < nr_pages; i++) {
740 		struct page *p = page + i;
741 		p->mapping = TAIL_MAPPING;
742 		set_compound_head(p, page);
743 	}
744 
745 	set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
746 	set_compound_order(page, order);
747 	atomic_set(compound_mapcount_ptr(page), -1);
748 	if (hpage_pincount_available(page))
749 		atomic_set(compound_pincount_ptr(page), 0);
750 }
751 
752 #ifdef CONFIG_DEBUG_PAGEALLOC
753 unsigned int _debug_guardpage_minorder;
754 
755 bool _debug_pagealloc_enabled_early __read_mostly
756 			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
757 EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
758 DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
759 EXPORT_SYMBOL(_debug_pagealloc_enabled);
760 
761 DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);
762 
763 static int __init early_debug_pagealloc(char *buf)
764 {
765 	return kstrtobool(buf, &_debug_pagealloc_enabled_early);
766 }
767 early_param("debug_pagealloc", early_debug_pagealloc);
768 
769 static int __init debug_guardpage_minorder_setup(char *buf)
770 {
771 	unsigned long res;
772 
773 	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
774 		pr_err("Bad debug_guardpage_minorder value\n");
775 		return 0;
776 	}
777 	_debug_guardpage_minorder = res;
778 	pr_info("Setting debug_guardpage_minorder to %lu\n", res);
779 	return 0;
780 }
781 early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
782 
783 static inline bool set_page_guard(struct zone *zone, struct page *page,
784 				unsigned int order, int migratetype)
785 {
786 	if (!debug_guardpage_enabled())
787 		return false;
788 
789 	if (order >= debug_guardpage_minorder())
790 		return false;
791 
792 	__SetPageGuard(page);
793 	INIT_LIST_HEAD(&page->lru);
794 	set_page_private(page, order);
795 	/* Guard pages are not available for any usage */
796 	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
797 
798 	return true;
799 }
800 
801 static inline void clear_page_guard(struct zone *zone, struct page *page,
802 				unsigned int order, int migratetype)
803 {
804 	if (!debug_guardpage_enabled())
805 		return;
806 
807 	__ClearPageGuard(page);
808 
809 	set_page_private(page, 0);
810 	if (!is_migrate_isolate(migratetype))
811 		__mod_zone_freepage_state(zone, (1 << order), migratetype);
812 }
813 #else
814 static inline bool set_page_guard(struct zone *zone, struct page *page,
815 			unsigned int order, int migratetype) { return false; }
816 static inline void clear_page_guard(struct zone *zone, struct page *page,
817 				unsigned int order, int migratetype) {}
818 #endif
819 
820 /*
821  * Enable static keys related to various memory debugging and hardening options.
822  * Some override others, and depend on early params that are evaluated in the
823  * order of appearance. So we need to first gather the full picture of what was
824  * enabled, and then make decisions.
825  */
826 void init_mem_debugging_and_hardening(void)
827 {
828 	bool page_poisoning_requested = false;
829 
830 #ifdef CONFIG_PAGE_POISONING
831 	/*
832 	 * Page poisoning is debug page alloc for some arches. If
833 	 * either of those options are enabled, enable poisoning.
834 	 */
835 	if (page_poisoning_enabled() ||
836 	     (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
837 	      debug_pagealloc_enabled())) {
838 		static_branch_enable(&_page_poisoning_enabled);
839 		page_poisoning_requested = true;
840 	}
841 #endif
842 
843 	if ((_init_on_alloc_enabled_early || _init_on_free_enabled_early) &&
844 	    page_poisoning_requested) {
845 		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
846 			"will take precedence over init_on_alloc and init_on_free\n");
847 		_init_on_alloc_enabled_early = false;
848 		_init_on_free_enabled_early = false;
849 	}
850 
851 	if (_init_on_alloc_enabled_early)
852 		static_branch_enable(&init_on_alloc);
853 	else
854 		static_branch_disable(&init_on_alloc);
855 
856 	if (_init_on_free_enabled_early)
857 		static_branch_enable(&init_on_free);
858 	else
859 		static_branch_disable(&init_on_free);
860 
861 #ifdef CONFIG_DEBUG_PAGEALLOC
862 	if (!debug_pagealloc_enabled())
863 		return;
864 
865 	static_branch_enable(&_debug_pagealloc_enabled);
866 
867 	if (!debug_guardpage_minorder())
868 		return;
869 
870 	static_branch_enable(&_debug_guardpage_enabled);
871 #endif
872 }
873 
874 static inline void set_buddy_order(struct page *page, unsigned int order)
875 {
876 	set_page_private(page, order);
877 	__SetPageBuddy(page);
878 }
879 
880 /*
881  * This function checks whether a page is free && is the buddy
882  * we can coalesce a page and its buddy if
883  * (a) the buddy is not in a hole (check before calling!) &&
884  * (b) the buddy is in the buddy system &&
885  * (c) a page and its buddy have the same order &&
886  * (d) a page and its buddy are in the same zone.
887  *
888  * For recording whether a page is in the buddy system, we set PageBuddy.
889  * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
890  *
891  * For recording page's order, we use page_private(page).
892  */
893 static inline bool page_is_buddy(struct page *page, struct page *buddy,
894 							unsigned int order)
895 {
896 	if (!page_is_guard(buddy) && !PageBuddy(buddy))
897 		return false;
898 
899 	if (buddy_order(buddy) != order)
900 		return false;
901 
902 	/*
903 	 * zone check is done late to avoid uselessly calculating
904 	 * zone/node ids for pages that could never merge.
905 	 */
906 	if (page_zone_id(page) != page_zone_id(buddy))
907 		return false;
908 
909 	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
910 
911 	return true;
912 }
913 
914 #ifdef CONFIG_COMPACTION
915 static inline struct capture_control *task_capc(struct zone *zone)
916 {
917 	struct capture_control *capc = current->capture_control;
918 
919 	return unlikely(capc) &&
920 		!(current->flags & PF_KTHREAD) &&
921 		!capc->page &&
922 		capc->cc->zone == zone ? capc : NULL;
923 }
924 
925 static inline bool
926 compaction_capture(struct capture_control *capc, struct page *page,
927 		   int order, int migratetype)
928 {
929 	if (!capc || order != capc->cc->order)
930 		return false;
931 
932 	/* Do not accidentally pollute CMA or isolated regions*/
933 	if (is_migrate_cma(migratetype) ||
934 	    is_migrate_isolate(migratetype))
935 		return false;
936 
937 	/*
938 	 * Do not let lower order allocations pollute a movable pageblock.
939 	 * This might let an unmovable request use a reclaimable pageblock
940 	 * and vice-versa but no more than normal fallback logic which can
941 	 * have trouble finding a high-order free page.
942 	 */
943 	if (order < pageblock_order && migratetype == MIGRATE_MOVABLE)
944 		return false;
945 
946 	capc->page = page;
947 	return true;
948 }
949 
950 #else
951 static inline struct capture_control *task_capc(struct zone *zone)
952 {
953 	return NULL;
954 }
955 
956 static inline bool
957 compaction_capture(struct capture_control *capc, struct page *page,
958 		   int order, int migratetype)
959 {
960 	return false;
961 }
962 #endif /* CONFIG_COMPACTION */
963 
964 /* Used for pages not on another list */
965 static inline void add_to_free_list(struct page *page, struct zone *zone,
966 				    unsigned int order, int migratetype)
967 {
968 	struct free_area *area = &zone->free_area[order];
969 
970 	list_add(&page->lru, &area->free_list[migratetype]);
971 	area->nr_free++;
972 }
973 
974 /* Used for pages not on another list */
975 static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
976 					 unsigned int order, int migratetype)
977 {
978 	struct free_area *area = &zone->free_area[order];
979 
980 	list_add_tail(&page->lru, &area->free_list[migratetype]);
981 	area->nr_free++;
982 }
983 
984 /*
985  * Used for pages which are on another list. Move the pages to the tail
986  * of the list - so the moved pages won't immediately be considered for
987  * allocation again (e.g., optimization for memory onlining).
988  */
989 static inline void move_to_free_list(struct page *page, struct zone *zone,
990 				     unsigned int order, int migratetype)
991 {
992 	struct free_area *area = &zone->free_area[order];
993 
994 	list_move_tail(&page->lru, &area->free_list[migratetype]);
995 }
996 
997 static inline void del_page_from_free_list(struct page *page, struct zone *zone,
998 					   unsigned int order)
999 {
1000 	/* clear reported state and update reported page count */
1001 	if (page_reported(page))
1002 		__ClearPageReported(page);
1003 
1004 	list_del(&page->lru);
1005 	__ClearPageBuddy(page);
1006 	set_page_private(page, 0);
1007 	zone->free_area[order].nr_free--;
1008 }
1009 
1010 /*
1011  * If this is not the largest possible page, check if the buddy
1012  * of the next-highest order is free. If it is, it's possible
1013  * that pages are being freed that will coalesce soon. In case,
1014  * that is happening, add the free page to the tail of the list
1015  * so it's less likely to be used soon and more likely to be merged
1016  * as a higher order page
1017  */
1018 static inline bool
1019 buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
1020 		   struct page *page, unsigned int order)
1021 {
1022 	struct page *higher_page, *higher_buddy;
1023 	unsigned long combined_pfn;
1024 
1025 	if (order >= MAX_ORDER - 2)
1026 		return false;
1027 
1028 	if (!pfn_valid_within(buddy_pfn))
1029 		return false;
1030 
1031 	combined_pfn = buddy_pfn & pfn;
1032 	higher_page = page + (combined_pfn - pfn);
1033 	buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1);
1034 	higher_buddy = higher_page + (buddy_pfn - combined_pfn);
1035 
1036 	return pfn_valid_within(buddy_pfn) &&
1037 	       page_is_buddy(higher_page, higher_buddy, order + 1);
1038 }
1039 
1040 /*
1041  * Freeing function for a buddy system allocator.
1042  *
1043  * The concept of a buddy system is to maintain direct-mapped table
1044  * (containing bit values) for memory blocks of various "orders".
1045  * The bottom level table contains the map for the smallest allocatable
1046  * units of memory (here, pages), and each level above it describes
1047  * pairs of units from the levels below, hence, "buddies".
1048  * At a high level, all that happens here is marking the table entry
1049  * at the bottom level available, and propagating the changes upward
1050  * as necessary, plus some accounting needed to play nicely with other
1051  * parts of the VM system.
1052  * At each level, we keep a list of pages, which are heads of continuous
1053  * free pages of length of (1 << order) and marked with PageBuddy.
1054  * Page's order is recorded in page_private(page) field.
1055  * So when we are allocating or freeing one, we can derive the state of the
1056  * other.  That is, if we allocate a small block, and both were
1057  * free, the remainder of the region must be split into blocks.
1058  * If a block is freed, and its buddy is also free, then this
1059  * triggers coalescing into a block of larger size.
1060  *
1061  * -- nyc
1062  */
1063 
1064 static inline void __free_one_page(struct page *page,
1065 		unsigned long pfn,
1066 		struct zone *zone, unsigned int order,
1067 		int migratetype, fpi_t fpi_flags)
1068 {
1069 	struct capture_control *capc = task_capc(zone);
1070 	unsigned long buddy_pfn;
1071 	unsigned long combined_pfn;
1072 	unsigned int max_order;
1073 	struct page *buddy;
1074 	bool to_tail;
1075 
1076 	max_order = min_t(unsigned int, MAX_ORDER - 1, pageblock_order);
1077 
1078 	VM_BUG_ON(!zone_is_initialized(zone));
1079 	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
1080 
1081 	VM_BUG_ON(migratetype == -1);
1082 	if (likely(!is_migrate_isolate(migratetype)))
1083 		__mod_zone_freepage_state(zone, 1 << order, migratetype);
1084 
1085 	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
1086 	VM_BUG_ON_PAGE(bad_range(zone, page), page);
1087 
1088 continue_merging:
1089 	while (order < max_order) {
1090 		if (compaction_capture(capc, page, order, migratetype)) {
1091 			__mod_zone_freepage_state(zone, -(1 << order),
1092 								migratetype);
1093 			return;
1094 		}
1095 		buddy_pfn = __find_buddy_pfn(pfn, order);
1096 		buddy = page + (buddy_pfn - pfn);
1097 
1098 		if (!pfn_valid_within(buddy_pfn))
1099 			goto done_merging;
1100 		if (!page_is_buddy(page, buddy, order))
1101 			goto done_merging;
1102 		/*
1103 		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
1104 		 * merge with it and move up one order.
1105 		 */
1106 		if (page_is_guard(buddy))
1107 			clear_page_guard(zone, buddy, order, migratetype);
1108 		else
1109 			del_page_from_free_list(buddy, zone, order);
1110 		combined_pfn = buddy_pfn & pfn;
1111 		page = page + (combined_pfn - pfn);
1112 		pfn = combined_pfn;
1113 		order++;
1114 	}
1115 	if (order < MAX_ORDER - 1) {
1116 		/* If we are here, it means order is >= pageblock_order.
1117 		 * We want to prevent merge between freepages on isolate
1118 		 * pageblock and normal pageblock. Without this, pageblock
1119 		 * isolation could cause incorrect freepage or CMA accounting.
1120 		 *
1121 		 * We don't want to hit this code for the more frequent
1122 		 * low-order merging.
1123 		 */
1124 		if (unlikely(has_isolate_pageblock(zone))) {
1125 			int buddy_mt;
1126 
1127 			buddy_pfn = __find_buddy_pfn(pfn, order);
1128 			buddy = page + (buddy_pfn - pfn);
1129 			buddy_mt = get_pageblock_migratetype(buddy);
1130 
1131 			if (migratetype != buddy_mt
1132 					&& (is_migrate_isolate(migratetype) ||
1133 						is_migrate_isolate(buddy_mt)))
1134 				goto done_merging;
1135 		}
1136 		max_order = order + 1;
1137 		goto continue_merging;
1138 	}
1139 
1140 done_merging:
1141 	set_buddy_order(page, order);
1142 
1143 	if (fpi_flags & FPI_TO_TAIL)
1144 		to_tail = true;
1145 	else if (is_shuffle_order(order))
1146 		to_tail = shuffle_pick_tail();
1147 	else
1148 		to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
1149 
1150 	if (to_tail)
1151 		add_to_free_list_tail(page, zone, order, migratetype);
1152 	else
1153 		add_to_free_list(page, zone, order, migratetype);
1154 
1155 	/* Notify page reporting subsystem of freed page */
1156 	if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
1157 		page_reporting_notify_free(order);
1158 }
1159 
1160 /*
1161  * A bad page could be due to a number of fields. Instead of multiple branches,
1162  * try and check multiple fields with one check. The caller must do a detailed
1163  * check if necessary.
1164  */
1165 static inline bool page_expected_state(struct page *page,
1166 					unsigned long check_flags)
1167 {
1168 	if (unlikely(atomic_read(&page->_mapcount) != -1))
1169 		return false;
1170 
1171 	if (unlikely((unsigned long)page->mapping |
1172 			page_ref_count(page) |
1173 #ifdef CONFIG_MEMCG
1174 			page->memcg_data |
1175 #endif
1176 			(page->flags & check_flags)))
1177 		return false;
1178 
1179 	return true;
1180 }
1181 
1182 static const char *page_bad_reason(struct page *page, unsigned long flags)
1183 {
1184 	const char *bad_reason = NULL;
1185 
1186 	if (unlikely(atomic_read(&page->_mapcount) != -1))
1187 		bad_reason = "nonzero mapcount";
1188 	if (unlikely(page->mapping != NULL))
1189 		bad_reason = "non-NULL mapping";
1190 	if (unlikely(page_ref_count(page) != 0))
1191 		bad_reason = "nonzero _refcount";
1192 	if (unlikely(page->flags & flags)) {
1193 		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
1194 			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
1195 		else
1196 			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
1197 	}
1198 #ifdef CONFIG_MEMCG
1199 	if (unlikely(page->memcg_data))
1200 		bad_reason = "page still charged to cgroup";
1201 #endif
1202 	return bad_reason;
1203 }
1204 
1205 static void check_free_page_bad(struct page *page)
1206 {
1207 	bad_page(page,
1208 		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
1209 }
1210 
1211 static inline int check_free_page(struct page *page)
1212 {
1213 	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
1214 		return 0;
1215 
1216 	/* Something has gone sideways, find it */
1217 	check_free_page_bad(page);
1218 	return 1;
1219 }
1220 
1221 static int free_tail_pages_check(struct page *head_page, struct page *page)
1222 {
1223 	int ret = 1;
1224 
1225 	/*
1226 	 * We rely page->lru.next never has bit 0 set, unless the page
1227 	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
1228 	 */
1229 	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
1230 
1231 	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
1232 		ret = 0;
1233 		goto out;
1234 	}
1235 	switch (page - head_page) {
1236 	case 1:
1237 		/* the first tail page: ->mapping may be compound_mapcount() */
1238 		if (unlikely(compound_mapcount(page))) {
1239 			bad_page(page, "nonzero compound_mapcount");
1240 			goto out;
1241 		}
1242 		break;
1243 	case 2:
1244 		/*
1245 		 * the second tail page: ->mapping is
1246 		 * deferred_list.next -- ignore value.
1247 		 */
1248 		break;
1249 	default:
1250 		if (page->mapping != TAIL_MAPPING) {
1251 			bad_page(page, "corrupted mapping in tail page");
1252 			goto out;
1253 		}
1254 		break;
1255 	}
1256 	if (unlikely(!PageTail(page))) {
1257 		bad_page(page, "PageTail not set");
1258 		goto out;
1259 	}
1260 	if (unlikely(compound_head(page) != head_page)) {
1261 		bad_page(page, "compound_head not consistent");
1262 		goto out;
1263 	}
1264 	ret = 0;
1265 out:
1266 	page->mapping = NULL;
1267 	clear_compound_head(page);
1268 	return ret;
1269 }
1270 
1271 static void kernel_init_free_pages(struct page *page, int numpages, bool zero_tags)
1272 {
1273 	int i;
1274 
1275 	if (zero_tags) {
1276 		for (i = 0; i < numpages; i++)
1277 			tag_clear_highpage(page + i);
1278 		return;
1279 	}
1280 
1281 	/* s390's use of memset() could override KASAN redzones. */
1282 	kasan_disable_current();
1283 	for (i = 0; i < numpages; i++) {
1284 		u8 tag = page_kasan_tag(page + i);
1285 		page_kasan_tag_reset(page + i);
1286 		clear_highpage(page + i);
1287 		page_kasan_tag_set(page + i, tag);
1288 	}
1289 	kasan_enable_current();
1290 }
1291 
1292 static __always_inline bool free_pages_prepare(struct page *page,
1293 			unsigned int order, bool check_free, fpi_t fpi_flags)
1294 {
1295 	int bad = 0;
1296 	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
1297 
1298 	VM_BUG_ON_PAGE(PageTail(page), page);
1299 
1300 	trace_mm_page_free(page, order);
1301 
1302 	if (unlikely(PageHWPoison(page)) && !order) {
1303 		/*
1304 		 * Do not let hwpoison pages hit pcplists/buddy
1305 		 * Untie memcg state and reset page's owner
1306 		 */
1307 		if (memcg_kmem_enabled() && PageMemcgKmem(page))
1308 			__memcg_kmem_uncharge_page(page, order);
1309 		reset_page_owner(page, order);
1310 		return false;
1311 	}
1312 
1313 	/*
1314 	 * Check tail pages before head page information is cleared to
1315 	 * avoid checking PageCompound for order-0 pages.
1316 	 */
1317 	if (unlikely(order)) {
1318 		bool compound = PageCompound(page);
1319 		int i;
1320 
1321 		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
1322 
1323 		if (compound)
1324 			ClearPageDoubleMap(page);
1325 		for (i = 1; i < (1 << order); i++) {
1326 			if (compound)
1327 				bad += free_tail_pages_check(page, page + i);
1328 			if (unlikely(check_free_page(page + i))) {
1329 				bad++;
1330 				continue;
1331 			}
1332 			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1333 		}
1334 	}
1335 	if (PageMappingFlags(page))
1336 		page->mapping = NULL;
1337 	if (memcg_kmem_enabled() && PageMemcgKmem(page))
1338 		__memcg_kmem_uncharge_page(page, order);
1339 	if (check_free)
1340 		bad += check_free_page(page);
1341 	if (bad)
1342 		return false;
1343 
1344 	page_cpupid_reset_last(page);
1345 	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1346 	reset_page_owner(page, order);
1347 
1348 	if (!PageHighMem(page)) {
1349 		debug_check_no_locks_freed(page_address(page),
1350 					   PAGE_SIZE << order);
1351 		debug_check_no_obj_freed(page_address(page),
1352 					   PAGE_SIZE << order);
1353 	}
1354 
1355 	kernel_poison_pages(page, 1 << order);
1356 
1357 	/*
1358 	 * As memory initialization might be integrated into KASAN,
1359 	 * kasan_free_pages and kernel_init_free_pages must be
1360 	 * kept together to avoid discrepancies in behavior.
1361 	 *
1362 	 * With hardware tag-based KASAN, memory tags must be set before the
1363 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
1364 	 */
1365 	if (kasan_has_integrated_init()) {
1366 		if (!skip_kasan_poison)
1367 			kasan_free_pages(page, order);
1368 	} else {
1369 		bool init = want_init_on_free();
1370 
1371 		if (init)
1372 			kernel_init_free_pages(page, 1 << order, false);
1373 		if (!skip_kasan_poison)
1374 			kasan_poison_pages(page, order, init);
1375 	}
1376 
1377 	/*
1378 	 * arch_free_page() can make the page's contents inaccessible.  s390
1379 	 * does this.  So nothing which can access the page's contents should
1380 	 * happen after this.
1381 	 */
1382 	arch_free_page(page, order);
1383 
1384 	debug_pagealloc_unmap_pages(page, 1 << order);
1385 
1386 	return true;
1387 }
1388 
1389 #ifdef CONFIG_DEBUG_VM
1390 /*
1391  * With DEBUG_VM enabled, order-0 pages are checked immediately when being freed
1392  * to pcp lists. With debug_pagealloc also enabled, they are also rechecked when
1393  * moved from pcp lists to free lists.
1394  */
1395 static bool free_pcp_prepare(struct page *page, unsigned int order)
1396 {
1397 	return free_pages_prepare(page, order, true, FPI_NONE);
1398 }
1399 
1400 static bool bulkfree_pcp_prepare(struct page *page)
1401 {
1402 	if (debug_pagealloc_enabled_static())
1403 		return check_free_page(page);
1404 	else
1405 		return false;
1406 }
1407 #else
1408 /*
1409  * With DEBUG_VM disabled, order-0 pages being freed are checked only when
1410  * moving from pcp lists to free list in order to reduce overhead. With
1411  * debug_pagealloc enabled, they are checked also immediately when being freed
1412  * to the pcp lists.
1413  */
1414 static bool free_pcp_prepare(struct page *page, unsigned int order)
1415 {
1416 	if (debug_pagealloc_enabled_static())
1417 		return free_pages_prepare(page, order, true, FPI_NONE);
1418 	else
1419 		return free_pages_prepare(page, order, false, FPI_NONE);
1420 }
1421 
1422 static bool bulkfree_pcp_prepare(struct page *page)
1423 {
1424 	return check_free_page(page);
1425 }
1426 #endif /* CONFIG_DEBUG_VM */
1427 
1428 static inline void prefetch_buddy(struct page *page)
1429 {
1430 	unsigned long pfn = page_to_pfn(page);
1431 	unsigned long buddy_pfn = __find_buddy_pfn(pfn, 0);
1432 	struct page *buddy = page + (buddy_pfn - pfn);
1433 
1434 	prefetch(buddy);
1435 }
1436 
1437 /*
1438  * Frees a number of pages from the PCP lists
1439  * Assumes all pages on list are in same zone, and of same order.
1440  * count is the number of pages to free.
1441  *
1442  * If the zone was previously in an "all pages pinned" state then look to
1443  * see if this freeing clears that state.
1444  *
1445  * And clear the zone's pages_scanned counter, to hold off the "all pages are
1446  * pinned" detection logic.
1447  */
1448 static void free_pcppages_bulk(struct zone *zone, int count,
1449 					struct per_cpu_pages *pcp)
1450 {
1451 	int pindex = 0;
1452 	int batch_free = 0;
1453 	int nr_freed = 0;
1454 	unsigned int order;
1455 	int prefetch_nr = READ_ONCE(pcp->batch);
1456 	bool isolated_pageblocks;
1457 	struct page *page, *tmp;
1458 	LIST_HEAD(head);
1459 
1460 	/*
1461 	 * Ensure proper count is passed which otherwise would stuck in the
1462 	 * below while (list_empty(list)) loop.
1463 	 */
1464 	count = min(pcp->count, count);
1465 	while (count > 0) {
1466 		struct list_head *list;
1467 
1468 		/*
1469 		 * Remove pages from lists in a round-robin fashion. A
1470 		 * batch_free count is maintained that is incremented when an
1471 		 * empty list is encountered.  This is so more pages are freed
1472 		 * off fuller lists instead of spinning excessively around empty
1473 		 * lists
1474 		 */
1475 		do {
1476 			batch_free++;
1477 			if (++pindex == NR_PCP_LISTS)
1478 				pindex = 0;
1479 			list = &pcp->lists[pindex];
1480 		} while (list_empty(list));
1481 
1482 		/* This is the only non-empty list. Free them all. */
1483 		if (batch_free == NR_PCP_LISTS)
1484 			batch_free = count;
1485 
1486 		order = pindex_to_order(pindex);
1487 		BUILD_BUG_ON(MAX_ORDER >= (1<<NR_PCP_ORDER_WIDTH));
1488 		do {
1489 			page = list_last_entry(list, struct page, lru);
1490 			/* must delete to avoid corrupting pcp list */
1491 			list_del(&page->lru);
1492 			nr_freed += 1 << order;
1493 			count -= 1 << order;
1494 
1495 			if (bulkfree_pcp_prepare(page))
1496 				continue;
1497 
1498 			/* Encode order with the migratetype */
1499 			page->index <<= NR_PCP_ORDER_WIDTH;
1500 			page->index |= order;
1501 
1502 			list_add_tail(&page->lru, &head);
1503 
1504 			/*
1505 			 * We are going to put the page back to the global
1506 			 * pool, prefetch its buddy to speed up later access
1507 			 * under zone->lock. It is believed the overhead of
1508 			 * an additional test and calculating buddy_pfn here
1509 			 * can be offset by reduced memory latency later. To
1510 			 * avoid excessive prefetching due to large count, only
1511 			 * prefetch buddy for the first pcp->batch nr of pages.
1512 			 */
1513 			if (prefetch_nr) {
1514 				prefetch_buddy(page);
1515 				prefetch_nr--;
1516 			}
1517 		} while (count > 0 && --batch_free && !list_empty(list));
1518 	}
1519 	pcp->count -= nr_freed;
1520 
1521 	/*
1522 	 * local_lock_irq held so equivalent to spin_lock_irqsave for
1523 	 * both PREEMPT_RT and non-PREEMPT_RT configurations.
1524 	 */
1525 	spin_lock(&zone->lock);
1526 	isolated_pageblocks = has_isolate_pageblock(zone);
1527 
1528 	/*
1529 	 * Use safe version since after __free_one_page(),
1530 	 * page->lru.next will not point to original list.
1531 	 */
1532 	list_for_each_entry_safe(page, tmp, &head, lru) {
1533 		int mt = get_pcppage_migratetype(page);
1534 
1535 		/* mt has been encoded with the order (see above) */
1536 		order = mt & NR_PCP_ORDER_MASK;
1537 		mt >>= NR_PCP_ORDER_WIDTH;
1538 
1539 		/* MIGRATE_ISOLATE page should not go to pcplists */
1540 		VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
1541 		/* Pageblock could have been isolated meanwhile */
1542 		if (unlikely(isolated_pageblocks))
1543 			mt = get_pageblock_migratetype(page);
1544 
1545 		__free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE);
1546 		trace_mm_page_pcpu_drain(page, order, mt);
1547 	}
1548 	spin_unlock(&zone->lock);
1549 }
1550 
1551 static void free_one_page(struct zone *zone,
1552 				struct page *page, unsigned long pfn,
1553 				unsigned int order,
1554 				int migratetype, fpi_t fpi_flags)
1555 {
1556 	unsigned long flags;
1557 
1558 	spin_lock_irqsave(&zone->lock, flags);
1559 	if (unlikely(has_isolate_pageblock(zone) ||
1560 		is_migrate_isolate(migratetype))) {
1561 		migratetype = get_pfnblock_migratetype(page, pfn);
1562 	}
1563 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
1564 	spin_unlock_irqrestore(&zone->lock, flags);
1565 }
1566 
1567 static void __meminit __init_single_page(struct page *page, unsigned long pfn,
1568 				unsigned long zone, int nid)
1569 {
1570 	mm_zero_struct_page(page);
1571 	set_page_links(page, zone, nid, pfn);
1572 	init_page_count(page);
1573 	page_mapcount_reset(page);
1574 	page_cpupid_reset_last(page);
1575 	page_kasan_tag_reset(page);
1576 
1577 	INIT_LIST_HEAD(&page->lru);
1578 #ifdef WANT_PAGE_VIRTUAL
1579 	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
1580 	if (!is_highmem_idx(zone))
1581 		set_page_address(page, __va(pfn << PAGE_SHIFT));
1582 #endif
1583 }
1584 
1585 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
1586 static void __meminit init_reserved_page(unsigned long pfn)
1587 {
1588 	pg_data_t *pgdat;
1589 	int nid, zid;
1590 
1591 	if (!early_page_uninitialised(pfn))
1592 		return;
1593 
1594 	nid = early_pfn_to_nid(pfn);
1595 	pgdat = NODE_DATA(nid);
1596 
1597 	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1598 		struct zone *zone = &pgdat->node_zones[zid];
1599 
1600 		if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
1601 			break;
1602 	}
1603 	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
1604 }
1605 #else
1606 static inline void init_reserved_page(unsigned long pfn)
1607 {
1608 }
1609 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
1610 
1611 /*
1612  * Initialised pages do not have PageReserved set. This function is
1613  * called for each range allocated by the bootmem allocator and
1614  * marks the pages PageReserved. The remaining valid pages are later
1615  * sent to the buddy page allocator.
1616  */
1617 void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
1618 {
1619 	unsigned long start_pfn = PFN_DOWN(start);
1620 	unsigned long end_pfn = PFN_UP(end);
1621 
1622 	for (; start_pfn < end_pfn; start_pfn++) {
1623 		if (pfn_valid(start_pfn)) {
1624 			struct page *page = pfn_to_page(start_pfn);
1625 
1626 			init_reserved_page(start_pfn);
1627 
1628 			/* Avoid false-positive PageTail() */
1629 			INIT_LIST_HEAD(&page->lru);
1630 
1631 			/*
1632 			 * no need for atomic set_bit because the struct
1633 			 * page is not visible yet so nobody should
1634 			 * access it yet.
1635 			 */
1636 			__SetPageReserved(page);
1637 		}
1638 	}
1639 }
1640 
1641 static void __free_pages_ok(struct page *page, unsigned int order,
1642 			    fpi_t fpi_flags)
1643 {
1644 	unsigned long flags;
1645 	int migratetype;
1646 	unsigned long pfn = page_to_pfn(page);
1647 	struct zone *zone = page_zone(page);
1648 
1649 	if (!free_pages_prepare(page, order, true, fpi_flags))
1650 		return;
1651 
1652 	migratetype = get_pfnblock_migratetype(page, pfn);
1653 
1654 	spin_lock_irqsave(&zone->lock, flags);
1655 	if (unlikely(has_isolate_pageblock(zone) ||
1656 		is_migrate_isolate(migratetype))) {
1657 		migratetype = get_pfnblock_migratetype(page, pfn);
1658 	}
1659 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
1660 	spin_unlock_irqrestore(&zone->lock, flags);
1661 
1662 	__count_vm_events(PGFREE, 1 << order);
1663 }
1664 
1665 void __free_pages_core(struct page *page, unsigned int order)
1666 {
1667 	unsigned int nr_pages = 1 << order;
1668 	struct page *p = page;
1669 	unsigned int loop;
1670 
1671 	/*
1672 	 * When initializing the memmap, __init_single_page() sets the refcount
1673 	 * of all pages to 1 ("allocated"/"not free"). We have to set the
1674 	 * refcount of all involved pages to 0.
1675 	 */
1676 	prefetchw(p);
1677 	for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
1678 		prefetchw(p + 1);
1679 		__ClearPageReserved(p);
1680 		set_page_count(p, 0);
1681 	}
1682 	__ClearPageReserved(p);
1683 	set_page_count(p, 0);
1684 
1685 	atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
1686 
1687 	/*
1688 	 * Bypass PCP and place fresh pages right to the tail, primarily
1689 	 * relevant for memory onlining.
1690 	 */
1691 	__free_pages_ok(page, order, FPI_TO_TAIL | FPI_SKIP_KASAN_POISON);
1692 }
1693 
1694 #ifdef CONFIG_NUMA
1695 
1696 /*
1697  * During memory init memblocks map pfns to nids. The search is expensive and
1698  * this caches recent lookups. The implementation of __early_pfn_to_nid
1699  * treats start/end as pfns.
1700  */
1701 struct mminit_pfnnid_cache {
1702 	unsigned long last_start;
1703 	unsigned long last_end;
1704 	int last_nid;
1705 };
1706 
1707 static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;
1708 
1709 /*
1710  * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
1711  */
1712 static int __meminit __early_pfn_to_nid(unsigned long pfn,
1713 					struct mminit_pfnnid_cache *state)
1714 {
1715 	unsigned long start_pfn, end_pfn;
1716 	int nid;
1717 
1718 	if (state->last_start <= pfn && pfn < state->last_end)
1719 		return state->last_nid;
1720 
1721 	nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
1722 	if (nid != NUMA_NO_NODE) {
1723 		state->last_start = start_pfn;
1724 		state->last_end = end_pfn;
1725 		state->last_nid = nid;
1726 	}
1727 
1728 	return nid;
1729 }
1730 
1731 int __meminit early_pfn_to_nid(unsigned long pfn)
1732 {
1733 	static DEFINE_SPINLOCK(early_pfn_lock);
1734 	int nid;
1735 
1736 	spin_lock(&early_pfn_lock);
1737 	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
1738 	if (nid < 0)
1739 		nid = first_online_node;
1740 	spin_unlock(&early_pfn_lock);
1741 
1742 	return nid;
1743 }
1744 #endif /* CONFIG_NUMA */
1745 
1746 void __init memblock_free_pages(struct page *page, unsigned long pfn,
1747 							unsigned int order)
1748 {
1749 	if (early_page_uninitialised(pfn))
1750 		return;
1751 	__free_pages_core(page, order);
1752 }
1753 
1754 /*
1755  * Check that the whole (or subset of) a pageblock given by the interval of
1756  * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
1757  * with the migration of free compaction scanner. The scanners then need to
1758  * use only pfn_valid_within() check for arches that allow holes within
1759  * pageblocks.
1760  *
1761  * Return struct page pointer of start_pfn, or NULL if checks were not passed.
1762  *
1763  * It's possible on some configurations to have a setup like node0 node1 node0
1764  * i.e. it's possible that all pages within a zones range of pages do not
1765  * belong to a single zone. We assume that a border between node0 and node1
1766  * can occur within a single pageblock, but not a node0 node1 node0
1767  * interleaving within a single pageblock. It is therefore sufficient to check
1768  * the first and last page of a pageblock and avoid checking each individual
1769  * page in a pageblock.
1770  */
1771 struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
1772 				     unsigned long end_pfn, struct zone *zone)
1773 {
1774 	struct page *start_page;
1775 	struct page *end_page;
1776 
1777 	/* end_pfn is one past the range we are checking */
1778 	end_pfn--;
1779 
1780 	if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
1781 		return NULL;
1782 
1783 	start_page = pfn_to_online_page(start_pfn);
1784 	if (!start_page)
1785 		return NULL;
1786 
1787 	if (page_zone(start_page) != zone)
1788 		return NULL;
1789 
1790 	end_page = pfn_to_page(end_pfn);
1791 
1792 	/* This gives a shorter code than deriving page_zone(end_page) */
1793 	if (page_zone_id(start_page) != page_zone_id(end_page))
1794 		return NULL;
1795 
1796 	return start_page;
1797 }
1798 
1799 void set_zone_contiguous(struct zone *zone)
1800 {
1801 	unsigned long block_start_pfn = zone->zone_start_pfn;
1802 	unsigned long block_end_pfn;
1803 
1804 	block_end_pfn = ALIGN(block_start_pfn + 1, pageblock_nr_pages);
1805 	for (; block_start_pfn < zone_end_pfn(zone);
1806 			block_start_pfn = block_end_pfn,
1807 			 block_end_pfn += pageblock_nr_pages) {
1808 
1809 		block_end_pfn = min(block_end_pfn, zone_end_pfn(zone));
1810 
1811 		if (!__pageblock_pfn_to_page(block_start_pfn,
1812 					     block_end_pfn, zone))
1813 			return;
1814 		cond_resched();
1815 	}
1816 
1817 	/* We confirm that there is no hole */
1818 	zone->contiguous = true;
1819 }
1820 
1821 void clear_zone_contiguous(struct zone *zone)
1822 {
1823 	zone->contiguous = false;
1824 }
1825 
1826 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
1827 static void __init deferred_free_range(unsigned long pfn,
1828 				       unsigned long nr_pages)
1829 {
1830 	struct page *page;
1831 	unsigned long i;
1832 
1833 	if (!nr_pages)
1834 		return;
1835 
1836 	page = pfn_to_page(pfn);
1837 
1838 	/* Free a large naturally-aligned chunk if possible */
1839 	if (nr_pages == pageblock_nr_pages &&
1840 	    (pfn & (pageblock_nr_pages - 1)) == 0) {
1841 		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
1842 		__free_pages_core(page, pageblock_order);
1843 		return;
1844 	}
1845 
1846 	for (i = 0; i < nr_pages; i++, page++, pfn++) {
1847 		if ((pfn & (pageblock_nr_pages - 1)) == 0)
1848 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
1849 		__free_pages_core(page, 0);
1850 	}
1851 }
1852 
1853 /* Completion tracking for deferred_init_memmap() threads */
1854 static atomic_t pgdat_init_n_undone __initdata;
1855 static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
1856 
1857 static inline void __init pgdat_init_report_one_done(void)
1858 {
1859 	if (atomic_dec_and_test(&pgdat_init_n_undone))
1860 		complete(&pgdat_init_all_done_comp);
1861 }
1862 
1863 /*
1864  * Returns true if page needs to be initialized or freed to buddy allocator.
1865  *
1866  * First we check if pfn is valid on architectures where it is possible to have
1867  * holes within pageblock_nr_pages. On systems where it is not possible, this
1868  * function is optimized out.
1869  *
1870  * Then, we check if a current large page is valid by only checking the validity
1871  * of the head pfn.
1872  */
1873 static inline bool __init deferred_pfn_valid(unsigned long pfn)
1874 {
1875 	if (!pfn_valid_within(pfn))
1876 		return false;
1877 	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
1878 		return false;
1879 	return true;
1880 }
1881 
1882 /*
1883  * Free pages to buddy allocator. Try to free aligned pages in
1884  * pageblock_nr_pages sizes.
1885  */
1886 static void __init deferred_free_pages(unsigned long pfn,
1887 				       unsigned long end_pfn)
1888 {
1889 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
1890 	unsigned long nr_free = 0;
1891 
1892 	for (; pfn < end_pfn; pfn++) {
1893 		if (!deferred_pfn_valid(pfn)) {
1894 			deferred_free_range(pfn - nr_free, nr_free);
1895 			nr_free = 0;
1896 		} else if (!(pfn & nr_pgmask)) {
1897 			deferred_free_range(pfn - nr_free, nr_free);
1898 			nr_free = 1;
1899 		} else {
1900 			nr_free++;
1901 		}
1902 	}
1903 	/* Free the last block of pages to allocator */
1904 	deferred_free_range(pfn - nr_free, nr_free);
1905 }
1906 
1907 /*
1908  * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
1909  * by performing it only once every pageblock_nr_pages.
1910  * Return number of pages initialized.
1911  */
1912 static unsigned long  __init deferred_init_pages(struct zone *zone,
1913 						 unsigned long pfn,
1914 						 unsigned long end_pfn)
1915 {
1916 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
1917 	int nid = zone_to_nid(zone);
1918 	unsigned long nr_pages = 0;
1919 	int zid = zone_idx(zone);
1920 	struct page *page = NULL;
1921 
1922 	for (; pfn < end_pfn; pfn++) {
1923 		if (!deferred_pfn_valid(pfn)) {
1924 			page = NULL;
1925 			continue;
1926 		} else if (!page || !(pfn & nr_pgmask)) {
1927 			page = pfn_to_page(pfn);
1928 		} else {
1929 			page++;
1930 		}
1931 		__init_single_page(page, pfn, zid, nid);
1932 		nr_pages++;
1933 	}
1934 	return (nr_pages);
1935 }
1936 
1937 /*
1938  * This function is meant to pre-load the iterator for the zone init.
1939  * Specifically it walks through the ranges until we are caught up to the
1940  * first_init_pfn value and exits there. If we never encounter the value we
1941  * return false indicating there are no valid ranges left.
1942  */
1943 static bool __init
1944 deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
1945 				    unsigned long *spfn, unsigned long *epfn,
1946 				    unsigned long first_init_pfn)
1947 {
1948 	u64 j;
1949 
1950 	/*
1951 	 * Start out by walking through the ranges in this zone that have
1952 	 * already been initialized. We don't need to do anything with them
1953 	 * so we just need to flush them out of the system.
1954 	 */
1955 	for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
1956 		if (*epfn <= first_init_pfn)
1957 			continue;
1958 		if (*spfn < first_init_pfn)
1959 			*spfn = first_init_pfn;
1960 		*i = j;
1961 		return true;
1962 	}
1963 
1964 	return false;
1965 }
1966 
1967 /*
1968  * Initialize and free pages. We do it in two loops: first we initialize
1969  * struct page, then free to buddy allocator, because while we are
1970  * freeing pages we can access pages that are ahead (computing buddy
1971  * page in __free_one_page()).
1972  *
1973  * In order to try and keep some memory in the cache we have the loop
1974  * broken along max page order boundaries. This way we will not cause
1975  * any issues with the buddy page computation.
1976  */
1977 static unsigned long __init
1978 deferred_init_maxorder(u64 *i, struct zone *zone, unsigned long *start_pfn,
1979 		       unsigned long *end_pfn)
1980 {
1981 	unsigned long mo_pfn = ALIGN(*start_pfn + 1, MAX_ORDER_NR_PAGES);
1982 	unsigned long spfn = *start_pfn, epfn = *end_pfn;
1983 	unsigned long nr_pages = 0;
1984 	u64 j = *i;
1985 
1986 	/* First we loop through and initialize the page values */
1987 	for_each_free_mem_pfn_range_in_zone_from(j, zone, start_pfn, end_pfn) {
1988 		unsigned long t;
1989 
1990 		if (mo_pfn <= *start_pfn)
1991 			break;
1992 
1993 		t = min(mo_pfn, *end_pfn);
1994 		nr_pages += deferred_init_pages(zone, *start_pfn, t);
1995 
1996 		if (mo_pfn < *end_pfn) {
1997 			*start_pfn = mo_pfn;
1998 			break;
1999 		}
2000 	}
2001 
2002 	/* Reset values and now loop through freeing pages as needed */
2003 	swap(j, *i);
2004 
2005 	for_each_free_mem_pfn_range_in_zone_from(j, zone, &spfn, &epfn) {
2006 		unsigned long t;
2007 
2008 		if (mo_pfn <= spfn)
2009 			break;
2010 
2011 		t = min(mo_pfn, epfn);
2012 		deferred_free_pages(spfn, t);
2013 
2014 		if (mo_pfn <= epfn)
2015 			break;
2016 	}
2017 
2018 	return nr_pages;
2019 }
2020 
2021 static void __init
2022 deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
2023 			   void *arg)
2024 {
2025 	unsigned long spfn, epfn;
2026 	struct zone *zone = arg;
2027 	u64 i;
2028 
2029 	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);
2030 
2031 	/*
2032 	 * Initialize and free pages in MAX_ORDER sized increments so that we
2033 	 * can avoid introducing any issues with the buddy allocator.
2034 	 */
2035 	while (spfn < end_pfn) {
2036 		deferred_init_maxorder(&i, zone, &spfn, &epfn);
2037 		cond_resched();
2038 	}
2039 }
2040 
2041 /* An arch may override for more concurrency. */
2042 __weak int __init
2043 deferred_page_init_max_threads(const struct cpumask *node_cpumask)
2044 {
2045 	return 1;
2046 }
2047 
2048 /* Initialise remaining memory on a node */
2049 static int __init deferred_init_memmap(void *data)
2050 {
2051 	pg_data_t *pgdat = data;
2052 	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
2053 	unsigned long spfn = 0, epfn = 0;
2054 	unsigned long first_init_pfn, flags;
2055 	unsigned long start = jiffies;
2056 	struct zone *zone;
2057 	int zid, max_threads;
2058 	u64 i;
2059 
2060 	/* Bind memory initialisation thread to a local node if possible */
2061 	if (!cpumask_empty(cpumask))
2062 		set_cpus_allowed_ptr(current, cpumask);
2063 
2064 	pgdat_resize_lock(pgdat, &flags);
2065 	first_init_pfn = pgdat->first_deferred_pfn;
2066 	if (first_init_pfn == ULONG_MAX) {
2067 		pgdat_resize_unlock(pgdat, &flags);
2068 		pgdat_init_report_one_done();
2069 		return 0;
2070 	}
2071 
2072 	/* Sanity check boundaries */
2073 	BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
2074 	BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
2075 	pgdat->first_deferred_pfn = ULONG_MAX;
2076 
2077 	/*
2078 	 * Once we unlock here, the zone cannot be grown anymore, thus if an
2079 	 * interrupt thread must allocate this early in boot, zone must be
2080 	 * pre-grown prior to start of deferred page initialization.
2081 	 */
2082 	pgdat_resize_unlock(pgdat, &flags);
2083 
2084 	/* Only the highest zone is deferred so find it */
2085 	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
2086 		zone = pgdat->node_zones + zid;
2087 		if (first_init_pfn < zone_end_pfn(zone))
2088 			break;
2089 	}
2090 
2091 	/* If the zone is empty somebody else may have cleared out the zone */
2092 	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2093 						 first_init_pfn))
2094 		goto zone_empty;
2095 
2096 	max_threads = deferred_page_init_max_threads(cpumask);
2097 
2098 	while (spfn < epfn) {
2099 		unsigned long epfn_align = ALIGN(epfn, PAGES_PER_SECTION);
2100 		struct padata_mt_job job = {
2101 			.thread_fn   = deferred_init_memmap_chunk,
2102 			.fn_arg      = zone,
2103 			.start       = spfn,
2104 			.size        = epfn_align - spfn,
2105 			.align       = PAGES_PER_SECTION,
2106 			.min_chunk   = PAGES_PER_SECTION,
2107 			.max_threads = max_threads,
2108 		};
2109 
2110 		padata_do_multithreaded(&job);
2111 		deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2112 						    epfn_align);
2113 	}
2114 zone_empty:
2115 	/* Sanity check that the next zone really is unpopulated */
2116 	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
2117 
2118 	pr_info("node %d deferred pages initialised in %ums\n",
2119 		pgdat->node_id, jiffies_to_msecs(jiffies - start));
2120 
2121 	pgdat_init_report_one_done();
2122 	return 0;
2123 }
2124 
2125 /*
2126  * If this zone has deferred pages, try to grow it by initializing enough
2127  * deferred pages to satisfy the allocation specified by order, rounded up to
2128  * the nearest PAGES_PER_SECTION boundary.  So we're adding memory in increments
2129  * of SECTION_SIZE bytes by initializing struct pages in increments of
2130  * PAGES_PER_SECTION * sizeof(struct page) bytes.
2131  *
2132  * Return true when zone was grown, otherwise return false. We return true even
2133  * when we grow less than requested, to let the caller decide if there are
2134  * enough pages to satisfy the allocation.
2135  *
2136  * Note: We use noinline because this function is needed only during boot, and
2137  * it is called from a __ref function _deferred_grow_zone. This way we are
2138  * making sure that it is not inlined into permanent text section.
2139  */
2140 static noinline bool __init
2141 deferred_grow_zone(struct zone *zone, unsigned int order)
2142 {
2143 	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
2144 	pg_data_t *pgdat = zone->zone_pgdat;
2145 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
2146 	unsigned long spfn, epfn, flags;
2147 	unsigned long nr_pages = 0;
2148 	u64 i;
2149 
2150 	/* Only the last zone may have deferred pages */
2151 	if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
2152 		return false;
2153 
2154 	pgdat_resize_lock(pgdat, &flags);
2155 
2156 	/*
2157 	 * If someone grew this zone while we were waiting for spinlock, return
2158 	 * true, as there might be enough pages already.
2159 	 */
2160 	if (first_deferred_pfn != pgdat->first_deferred_pfn) {
2161 		pgdat_resize_unlock(pgdat, &flags);
2162 		return true;
2163 	}
2164 
2165 	/* If the zone is empty somebody else may have cleared out the zone */
2166 	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
2167 						 first_deferred_pfn)) {
2168 		pgdat->first_deferred_pfn = ULONG_MAX;
2169 		pgdat_resize_unlock(pgdat, &flags);
2170 		/* Retry only once. */
2171 		return first_deferred_pfn != ULONG_MAX;
2172 	}
2173 
2174 	/*
2175 	 * Initialize and free pages in MAX_ORDER sized increments so
2176 	 * that we can avoid introducing any issues with the buddy
2177 	 * allocator.
2178 	 */
2179 	while (spfn < epfn) {
2180 		/* update our first deferred PFN for this section */
2181 		first_deferred_pfn = spfn;
2182 
2183 		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
2184 		touch_nmi_watchdog();
2185 
2186 		/* We should only stop along section boundaries */
2187 		if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION)
2188 			continue;
2189 
2190 		/* If our quota has been met we can stop here */
2191 		if (nr_pages >= nr_pages_needed)
2192 			break;
2193 	}
2194 
2195 	pgdat->first_deferred_pfn = spfn;
2196 	pgdat_resize_unlock(pgdat, &flags);
2197 
2198 	return nr_pages > 0;
2199 }
2200 
2201 /*
2202  * deferred_grow_zone() is __init, but it is called from
2203  * get_page_from_freelist() during early boot until deferred_pages permanently
2204  * disables this call. This is why we have refdata wrapper to avoid warning,
2205  * and to ensure that the function body gets unloaded.
2206  */
2207 static bool __ref
2208 _deferred_grow_zone(struct zone *zone, unsigned int order)
2209 {
2210 	return deferred_grow_zone(zone, order);
2211 }
2212 
2213 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
2214 
2215 void __init page_alloc_init_late(void)
2216 {
2217 	struct zone *zone;
2218 	int nid;
2219 
2220 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
2221 
2222 	/* There will be num_node_state(N_MEMORY) threads */
2223 	atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
2224 	for_each_node_state(nid, N_MEMORY) {
2225 		kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
2226 	}
2227 
2228 	/* Block until all are initialised */
2229 	wait_for_completion(&pgdat_init_all_done_comp);
2230 
2231 	/*
2232 	 * We initialized the rest of the deferred pages.  Permanently disable
2233 	 * on-demand struct page initialization.
2234 	 */
2235 	static_branch_disable(&deferred_pages);
2236 
2237 	/* Reinit limits that are based on free pages after the kernel is up */
2238 	files_maxfiles_init();
2239 #endif
2240 
2241 	buffer_init();
2242 
2243 	/* Discard memblock private memory */
2244 	memblock_discard();
2245 
2246 	for_each_node_state(nid, N_MEMORY)
2247 		shuffle_free_memory(NODE_DATA(nid));
2248 
2249 	for_each_populated_zone(zone)
2250 		set_zone_contiguous(zone);
2251 }
2252 
2253 #ifdef CONFIG_CMA
2254 /* Free whole pageblock and set its migration type to MIGRATE_CMA. */
2255 void __init init_cma_reserved_pageblock(struct page *page)
2256 {
2257 	unsigned i = pageblock_nr_pages;
2258 	struct page *p = page;
2259 
2260 	do {
2261 		__ClearPageReserved(p);
2262 		set_page_count(p, 0);
2263 	} while (++p, --i);
2264 
2265 	set_pageblock_migratetype(page, MIGRATE_CMA);
2266 
2267 	if (pageblock_order >= MAX_ORDER) {
2268 		i = pageblock_nr_pages;
2269 		p = page;
2270 		do {
2271 			set_page_refcounted(p);
2272 			__free_pages(p, MAX_ORDER - 1);
2273 			p += MAX_ORDER_NR_PAGES;
2274 		} while (i -= MAX_ORDER_NR_PAGES);
2275 	} else {
2276 		set_page_refcounted(page);
2277 		__free_pages(page, pageblock_order);
2278 	}
2279 
2280 	adjust_managed_page_count(page, pageblock_nr_pages);
2281 	page_zone(page)->cma_pages += pageblock_nr_pages;
2282 }
2283 #endif
2284 
2285 /*
2286  * The order of subdivision here is critical for the IO subsystem.
2287  * Please do not alter this order without good reasons and regression
2288  * testing. Specifically, as large blocks of memory are subdivided,
2289  * the order in which smaller blocks are delivered depends on the order
2290  * they're subdivided in this function. This is the primary factor
2291  * influencing the order in which pages are delivered to the IO
2292  * subsystem according to empirical testing, and this is also justified
2293  * by considering the behavior of a buddy system containing a single
2294  * large block of memory acted on by a series of small allocations.
2295  * This behavior is a critical factor in sglist merging's success.
2296  *
2297  * -- nyc
2298  */
2299 static inline void expand(struct zone *zone, struct page *page,
2300 	int low, int high, int migratetype)
2301 {
2302 	unsigned long size = 1 << high;
2303 
2304 	while (high > low) {
2305 		high--;
2306 		size >>= 1;
2307 		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
2308 
2309 		/*
2310 		 * Mark as guard pages (or page), that will allow to
2311 		 * merge back to allocator when buddy will be freed.
2312 		 * Corresponding page table entries will not be touched,
2313 		 * pages will stay not present in virtual address space
2314 		 */
2315 		if (set_page_guard(zone, &page[size], high, migratetype))
2316 			continue;
2317 
2318 		add_to_free_list(&page[size], zone, high, migratetype);
2319 		set_buddy_order(&page[size], high);
2320 	}
2321 }
2322 
2323 static void check_new_page_bad(struct page *page)
2324 {
2325 	if (unlikely(page->flags & __PG_HWPOISON)) {
2326 		/* Don't complain about hwpoisoned pages */
2327 		page_mapcount_reset(page); /* remove PageBuddy */
2328 		return;
2329 	}
2330 
2331 	bad_page(page,
2332 		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
2333 }
2334 
2335 /*
2336  * This page is about to be returned from the page allocator
2337  */
2338 static inline int check_new_page(struct page *page)
2339 {
2340 	if (likely(page_expected_state(page,
2341 				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
2342 		return 0;
2343 
2344 	check_new_page_bad(page);
2345 	return 1;
2346 }
2347 
2348 #ifdef CONFIG_DEBUG_VM
2349 /*
2350  * With DEBUG_VM enabled, order-0 pages are checked for expected state when
2351  * being allocated from pcp lists. With debug_pagealloc also enabled, they are
2352  * also checked when pcp lists are refilled from the free lists.
2353  */
2354 static inline bool check_pcp_refill(struct page *page)
2355 {
2356 	if (debug_pagealloc_enabled_static())
2357 		return check_new_page(page);
2358 	else
2359 		return false;
2360 }
2361 
2362 static inline bool check_new_pcp(struct page *page)
2363 {
2364 	return check_new_page(page);
2365 }
2366 #else
2367 /*
2368  * With DEBUG_VM disabled, free order-0 pages are checked for expected state
2369  * when pcp lists are being refilled from the free lists. With debug_pagealloc
2370  * enabled, they are also checked when being allocated from the pcp lists.
2371  */
2372 static inline bool check_pcp_refill(struct page *page)
2373 {
2374 	return check_new_page(page);
2375 }
2376 static inline bool check_new_pcp(struct page *page)
2377 {
2378 	if (debug_pagealloc_enabled_static())
2379 		return check_new_page(page);
2380 	else
2381 		return false;
2382 }
2383 #endif /* CONFIG_DEBUG_VM */
2384 
2385 static bool check_new_pages(struct page *page, unsigned int order)
2386 {
2387 	int i;
2388 	for (i = 0; i < (1 << order); i++) {
2389 		struct page *p = page + i;
2390 
2391 		if (unlikely(check_new_page(p)))
2392 			return true;
2393 	}
2394 
2395 	return false;
2396 }
2397 
2398 inline void post_alloc_hook(struct page *page, unsigned int order,
2399 				gfp_t gfp_flags)
2400 {
2401 	set_page_private(page, 0);
2402 	set_page_refcounted(page);
2403 
2404 	arch_alloc_page(page, order);
2405 	debug_pagealloc_map_pages(page, 1 << order);
2406 
2407 	/*
2408 	 * Page unpoisoning must happen before memory initialization.
2409 	 * Otherwise, the poison pattern will be overwritten for __GFP_ZERO
2410 	 * allocations and the page unpoisoning code will complain.
2411 	 */
2412 	kernel_unpoison_pages(page, 1 << order);
2413 
2414 	/*
2415 	 * As memory initialization might be integrated into KASAN,
2416 	 * kasan_alloc_pages and kernel_init_free_pages must be
2417 	 * kept together to avoid discrepancies in behavior.
2418 	 */
2419 	if (kasan_has_integrated_init()) {
2420 		kasan_alloc_pages(page, order, gfp_flags);
2421 	} else {
2422 		bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
2423 
2424 		kasan_unpoison_pages(page, order, init);
2425 		if (init)
2426 			kernel_init_free_pages(page, 1 << order,
2427 					       gfp_flags & __GFP_ZEROTAGS);
2428 	}
2429 
2430 	set_page_owner(page, order, gfp_flags);
2431 }
2432 
2433 static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
2434 							unsigned int alloc_flags)
2435 {
2436 	post_alloc_hook(page, order, gfp_flags);
2437 
2438 	if (order && (gfp_flags & __GFP_COMP))
2439 		prep_compound_page(page, order);
2440 
2441 	/*
2442 	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
2443 	 * allocate the page. The expectation is that the caller is taking
2444 	 * steps that will free more memory. The caller should avoid the page
2445 	 * being used for !PFMEMALLOC purposes.
2446 	 */
2447 	if (alloc_flags & ALLOC_NO_WATERMARKS)
2448 		set_page_pfmemalloc(page);
2449 	else
2450 		clear_page_pfmemalloc(page);
2451 }
2452 
2453 /*
2454  * Go through the free lists for the given migratetype and remove
2455  * the smallest available page from the freelists
2456  */
2457 static __always_inline
2458 struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
2459 						int migratetype)
2460 {
2461 	unsigned int current_order;
2462 	struct free_area *area;
2463 	struct page *page;
2464 
2465 	/* Find a page of the appropriate size in the preferred list */
2466 	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
2467 		area = &(zone->free_area[current_order]);
2468 		page = get_page_from_free_area(area, migratetype);
2469 		if (!page)
2470 			continue;
2471 		del_page_from_free_list(page, zone, current_order);
2472 		expand(zone, page, order, current_order, migratetype);
2473 		set_pcppage_migratetype(page, migratetype);
2474 		return page;
2475 	}
2476 
2477 	return NULL;
2478 }
2479 
2480 
2481 /*
2482  * This array describes the order lists are fallen back to when
2483  * the free lists for the desirable migrate type are depleted
2484  */
2485 static int fallbacks[MIGRATE_TYPES][3] = {
2486 	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_TYPES },
2487 	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
2488 	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_TYPES },
2489 #ifdef CONFIG_CMA
2490 	[MIGRATE_CMA]         = { MIGRATE_TYPES }, /* Never used */
2491 #endif
2492 #ifdef CONFIG_MEMORY_ISOLATION
2493 	[MIGRATE_ISOLATE]     = { MIGRATE_TYPES }, /* Never used */
2494 #endif
2495 };
2496 
2497 #ifdef CONFIG_CMA
2498 static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone,
2499 					unsigned int order)
2500 {
2501 	return __rmqueue_smallest(zone, order, MIGRATE_CMA);
2502 }
2503 #else
2504 static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
2505 					unsigned int order) { return NULL; }
2506 #endif
2507 
2508 /*
2509  * Move the free pages in a range to the freelist tail of the requested type.
2510  * Note that start_page and end_pages are not aligned on a pageblock
2511  * boundary. If alignment is required, use move_freepages_block()
2512  */
2513 static int move_freepages(struct zone *zone,
2514 			  unsigned long start_pfn, unsigned long end_pfn,
2515 			  int migratetype, int *num_movable)
2516 {
2517 	struct page *page;
2518 	unsigned long pfn;
2519 	unsigned int order;
2520 	int pages_moved = 0;
2521 
2522 	for (pfn = start_pfn; pfn <= end_pfn;) {
2523 		if (!pfn_valid_within(pfn)) {
2524 			pfn++;
2525 			continue;
2526 		}
2527 
2528 		page = pfn_to_page(pfn);
2529 		if (!PageBuddy(page)) {
2530 			/*
2531 			 * We assume that pages that could be isolated for
2532 			 * migration are movable. But we don't actually try
2533 			 * isolating, as that would be expensive.
2534 			 */
2535 			if (num_movable &&
2536 					(PageLRU(page) || __PageMovable(page)))
2537 				(*num_movable)++;
2538 			pfn++;
2539 			continue;
2540 		}
2541 
2542 		/* Make sure we are not inadvertently changing nodes */
2543 		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
2544 		VM_BUG_ON_PAGE(page_zone(page) != zone, page);
2545 
2546 		order = buddy_order(page);
2547 		move_to_free_list(page, zone, order, migratetype);
2548 		pfn += 1 << order;
2549 		pages_moved += 1 << order;
2550 	}
2551 
2552 	return pages_moved;
2553 }
2554 
2555 int move_freepages_block(struct zone *zone, struct page *page,
2556 				int migratetype, int *num_movable)
2557 {
2558 	unsigned long start_pfn, end_pfn, pfn;
2559 
2560 	if (num_movable)
2561 		*num_movable = 0;
2562 
2563 	pfn = page_to_pfn(page);
2564 	start_pfn = pfn & ~(pageblock_nr_pages - 1);
2565 	end_pfn = start_pfn + pageblock_nr_pages - 1;
2566 
2567 	/* Do not cross zone boundaries */
2568 	if (!zone_spans_pfn(zone, start_pfn))
2569 		start_pfn = pfn;
2570 	if (!zone_spans_pfn(zone, end_pfn))
2571 		return 0;
2572 
2573 	return move_freepages(zone, start_pfn, end_pfn, migratetype,
2574 								num_movable);
2575 }
2576 
2577 static void change_pageblock_range(struct page *pageblock_page,
2578 					int start_order, int migratetype)
2579 {
2580 	int nr_pageblocks = 1 << (start_order - pageblock_order);
2581 
2582 	while (nr_pageblocks--) {
2583 		set_pageblock_migratetype(pageblock_page, migratetype);
2584 		pageblock_page += pageblock_nr_pages;
2585 	}
2586 }
2587 
2588 /*
2589  * When we are falling back to another migratetype during allocation, try to
2590  * steal extra free pages from the same pageblocks to satisfy further
2591  * allocations, instead of polluting multiple pageblocks.
2592  *
2593  * If we are stealing a relatively large buddy page, it is likely there will
2594  * be more free pages in the pageblock, so try to steal them all. For
2595  * reclaimable and unmovable allocations, we steal regardless of page size,
2596  * as fragmentation caused by those allocations polluting movable pageblocks
2597  * is worse than movable allocations stealing from unmovable and reclaimable
2598  * pageblocks.
2599  */
2600 static bool can_steal_fallback(unsigned int order, int start_mt)
2601 {
2602 	/*
2603 	 * Leaving this order check is intended, although there is
2604 	 * relaxed order check in next check. The reason is that
2605 	 * we can actually steal whole pageblock if this condition met,
2606 	 * but, below check doesn't guarantee it and that is just heuristic
2607 	 * so could be changed anytime.
2608 	 */
2609 	if (order >= pageblock_order)
2610 		return true;
2611 
2612 	if (order >= pageblock_order / 2 ||
2613 		start_mt == MIGRATE_RECLAIMABLE ||
2614 		start_mt == MIGRATE_UNMOVABLE ||
2615 		page_group_by_mobility_disabled)
2616 		return true;
2617 
2618 	return false;
2619 }
2620 
2621 static inline bool boost_watermark(struct zone *zone)
2622 {
2623 	unsigned long max_boost;
2624 
2625 	if (!watermark_boost_factor)
2626 		return false;
2627 	/*
2628 	 * Don't bother in zones that are unlikely to produce results.
2629 	 * On small machines, including kdump capture kernels running
2630 	 * in a small area, boosting the watermark can cause an out of
2631 	 * memory situation immediately.
2632 	 */
2633 	if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
2634 		return false;
2635 
2636 	max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
2637 			watermark_boost_factor, 10000);
2638 
2639 	/*
2640 	 * high watermark may be uninitialised if fragmentation occurs
2641 	 * very early in boot so do not boost. We do not fall
2642 	 * through and boost by pageblock_nr_pages as failing
2643 	 * allocations that early means that reclaim is not going
2644 	 * to help and it may even be impossible to reclaim the
2645 	 * boosted watermark resulting in a hang.
2646 	 */
2647 	if (!max_boost)
2648 		return false;
2649 
2650 	max_boost = max(pageblock_nr_pages, max_boost);
2651 
2652 	zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
2653 		max_boost);
2654 
2655 	return true;
2656 }
2657 
2658 /*
2659  * This function implements actual steal behaviour. If order is large enough,
2660  * we can steal whole pageblock. If not, we first move freepages in this
2661  * pageblock to our migratetype and determine how many already-allocated pages
2662  * are there in the pageblock with a compatible migratetype. If at least half
2663  * of pages are free or compatible, we can change migratetype of the pageblock
2664  * itself, so pages freed in the future will be put on the correct free list.
2665  */
2666 static void steal_suitable_fallback(struct zone *zone, struct page *page,
2667 		unsigned int alloc_flags, int start_type, bool whole_block)
2668 {
2669 	unsigned int current_order = buddy_order(page);
2670 	int free_pages, movable_pages, alike_pages;
2671 	int old_block_type;
2672 
2673 	old_block_type = get_pageblock_migratetype(page);
2674 
2675 	/*
2676 	 * This can happen due to races and we want to prevent broken
2677 	 * highatomic accounting.
2678 	 */
2679 	if (is_migrate_highatomic(old_block_type))
2680 		goto single_page;
2681 
2682 	/* Take ownership for orders >= pageblock_order */
2683 	if (current_order >= pageblock_order) {
2684 		change_pageblock_range(page, current_order, start_type);
2685 		goto single_page;
2686 	}
2687 
2688 	/*
2689 	 * Boost watermarks to increase reclaim pressure to reduce the
2690 	 * likelihood of future fallbacks. Wake kswapd now as the node
2691 	 * may be balanced overall and kswapd will not wake naturally.
2692 	 */
2693 	if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
2694 		set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
2695 
2696 	/* We are not allowed to try stealing from the whole block */
2697 	if (!whole_block)
2698 		goto single_page;
2699 
2700 	free_pages = move_freepages_block(zone, page, start_type,
2701 						&movable_pages);
2702 	/*
2703 	 * Determine how many pages are compatible with our allocation.
2704 	 * For movable allocation, it's the number of movable pages which
2705 	 * we just obtained. For other types it's a bit more tricky.
2706 	 */
2707 	if (start_type == MIGRATE_MOVABLE) {
2708 		alike_pages = movable_pages;
2709 	} else {
2710 		/*
2711 		 * If we are falling back a RECLAIMABLE or UNMOVABLE allocation
2712 		 * to MOVABLE pageblock, consider all non-movable pages as
2713 		 * compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
2714 		 * vice versa, be conservative since we can't distinguish the
2715 		 * exact migratetype of non-movable pages.
2716 		 */
2717 		if (old_block_type == MIGRATE_MOVABLE)
2718 			alike_pages = pageblock_nr_pages
2719 						- (free_pages + movable_pages);
2720 		else
2721 			alike_pages = 0;
2722 	}
2723 
2724 	/* moving whole block can fail due to zone boundary conditions */
2725 	if (!free_pages)
2726 		goto single_page;
2727 
2728 	/*
2729 	 * If a sufficient number of pages in the block are either free or of
2730 	 * comparable migratability as our allocation, claim the whole block.
2731 	 */
2732 	if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
2733 			page_group_by_mobility_disabled)
2734 		set_pageblock_migratetype(page, start_type);
2735 
2736 	return;
2737 
2738 single_page:
2739 	move_to_free_list(page, zone, current_order, start_type);
2740 }
2741 
2742 /*
2743  * Check whether there is a suitable fallback freepage with requested order.
2744  * If only_stealable is true, this function returns fallback_mt only if
2745  * we can steal other freepages all together. This would help to reduce
2746  * fragmentation due to mixed migratetype pages in one pageblock.
2747  */
2748 int find_suitable_fallback(struct free_area *area, unsigned int order,
2749 			int migratetype, bool only_stealable, bool *can_steal)
2750 {
2751 	int i;
2752 	int fallback_mt;
2753 
2754 	if (area->nr_free == 0)
2755 		return -1;
2756 
2757 	*can_steal = false;
2758 	for (i = 0;; i++) {
2759 		fallback_mt = fallbacks[migratetype][i];
2760 		if (fallback_mt == MIGRATE_TYPES)
2761 			break;
2762 
2763 		if (free_area_empty(area, fallback_mt))
2764 			continue;
2765 
2766 		if (can_steal_fallback(order, migratetype))
2767 			*can_steal = true;
2768 
2769 		if (!only_stealable)
2770 			return fallback_mt;
2771 
2772 		if (*can_steal)
2773 			return fallback_mt;
2774 	}
2775 
2776 	return -1;
2777 }
2778 
2779 /*
2780  * Reserve a pageblock for exclusive use of high-order atomic allocations if
2781  * there are no empty page blocks that contain a page with a suitable order
2782  */
2783 static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
2784 				unsigned int alloc_order)
2785 {
2786 	int mt;
2787 	unsigned long max_managed, flags;
2788 
2789 	/*
2790 	 * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
2791 	 * Check is race-prone but harmless.
2792 	 */
2793 	max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
2794 	if (zone->nr_reserved_highatomic >= max_managed)
2795 		return;
2796 
2797 	spin_lock_irqsave(&zone->lock, flags);
2798 
2799 	/* Recheck the nr_reserved_highatomic limit under the lock */
2800 	if (zone->nr_reserved_highatomic >= max_managed)
2801 		goto out_unlock;
2802 
2803 	/* Yoink! */
2804 	mt = get_pageblock_migratetype(page);
2805 	if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt)
2806 	    && !is_migrate_cma(mt)) {
2807 		zone->nr_reserved_highatomic += pageblock_nr_pages;
2808 		set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
2809 		move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
2810 	}
2811 
2812 out_unlock:
2813 	spin_unlock_irqrestore(&zone->lock, flags);
2814 }
2815 
2816 /*
2817  * Used when an allocation is about to fail under memory pressure. This
2818  * potentially hurts the reliability of high-order allocations when under
2819  * intense memory pressure but failed atomic allocations should be easier
2820  * to recover from than an OOM.
2821  *
2822  * If @force is true, try to unreserve a pageblock even though highatomic
2823  * pageblock is exhausted.
2824  */
2825 static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
2826 						bool force)
2827 {
2828 	struct zonelist *zonelist = ac->zonelist;
2829 	unsigned long flags;
2830 	struct zoneref *z;
2831 	struct zone *zone;
2832 	struct page *page;
2833 	int order;
2834 	bool ret;
2835 
2836 	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
2837 								ac->nodemask) {
2838 		/*
2839 		 * Preserve at least one pageblock unless memory pressure
2840 		 * is really high.
2841 		 */
2842 		if (!force && zone->nr_reserved_highatomic <=
2843 					pageblock_nr_pages)
2844 			continue;
2845 
2846 		spin_lock_irqsave(&zone->lock, flags);
2847 		for (order = 0; order < MAX_ORDER; order++) {
2848 			struct free_area *area = &(zone->free_area[order]);
2849 
2850 			page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
2851 			if (!page)
2852 				continue;
2853 
2854 			/*
2855 			 * In page freeing path, migratetype change is racy so
2856 			 * we can counter several free pages in a pageblock
2857 			 * in this loop although we changed the pageblock type
2858 			 * from highatomic to ac->migratetype. So we should
2859 			 * adjust the count once.
2860 			 */
2861 			if (is_migrate_highatomic_page(page)) {
2862 				/*
2863 				 * It should never happen but changes to
2864 				 * locking could inadvertently allow a per-cpu
2865 				 * drain to add pages to MIGRATE_HIGHATOMIC
2866 				 * while unreserving so be safe and watch for
2867 				 * underflows.
2868 				 */
2869 				zone->nr_reserved_highatomic -= min(
2870 						pageblock_nr_pages,
2871 						zone->nr_reserved_highatomic);
2872 			}
2873 
2874 			/*
2875 			 * Convert to ac->migratetype and avoid the normal
2876 			 * pageblock stealing heuristics. Minimally, the caller
2877 			 * is doing the work and needs the pages. More
2878 			 * importantly, if the block was always converted to
2879 			 * MIGRATE_UNMOVABLE or another type then the number
2880 			 * of pageblocks that cannot be completely freed
2881 			 * may increase.
2882 			 */
2883 			set_pageblock_migratetype(page, ac->migratetype);
2884 			ret = move_freepages_block(zone, page, ac->migratetype,
2885 									NULL);
2886 			if (ret) {
2887 				spin_unlock_irqrestore(&zone->lock, flags);
2888 				return ret;
2889 			}
2890 		}
2891 		spin_unlock_irqrestore(&zone->lock, flags);
2892 	}
2893 
2894 	return false;
2895 }
2896 
2897 /*
2898  * Try finding a free buddy page on the fallback list and put it on the free
2899  * list of requested migratetype, possibly along with other pages from the same
2900  * block, depending on fragmentation avoidance heuristics. Returns true if
2901  * fallback was found so that __rmqueue_smallest() can grab it.
2902  *
2903  * The use of signed ints for order and current_order is a deliberate
2904  * deviation from the rest of this file, to make the for loop
2905  * condition simpler.
2906  */
2907 static __always_inline bool
2908 __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
2909 						unsigned int alloc_flags)
2910 {
2911 	struct free_area *area;
2912 	int current_order;
2913 	int min_order = order;
2914 	struct page *page;
2915 	int fallback_mt;
2916 	bool can_steal;
2917 
2918 	/*
2919 	 * Do not steal pages from freelists belonging to other pageblocks
2920 	 * i.e. orders < pageblock_order. If there are no local zones free,
2921 	 * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
2922 	 */
2923 	if (alloc_flags & ALLOC_NOFRAGMENT)
2924 		min_order = pageblock_order;
2925 
2926 	/*
2927 	 * Find the largest available free page in the other list. This roughly
2928 	 * approximates finding the pageblock with the most free pages, which
2929 	 * would be too costly to do exactly.
2930 	 */
2931 	for (current_order = MAX_ORDER - 1; current_order >= min_order;
2932 				--current_order) {
2933 		area = &(zone->free_area[current_order]);
2934 		fallback_mt = find_suitable_fallback(area, current_order,
2935 				start_migratetype, false, &can_steal);
2936 		if (fallback_mt == -1)
2937 			continue;
2938 
2939 		/*
2940 		 * We cannot steal all free pages from the pageblock and the
2941 		 * requested migratetype is movable. In that case it's better to
2942 		 * steal and split the smallest available page instead of the
2943 		 * largest available page, because even if the next movable
2944 		 * allocation falls back into a different pageblock than this
2945 		 * one, it won't cause permanent fragmentation.
2946 		 */
2947 		if (!can_steal && start_migratetype == MIGRATE_MOVABLE
2948 					&& current_order > order)
2949 			goto find_smallest;
2950 
2951 		goto do_steal;
2952 	}
2953 
2954 	return false;
2955 
2956 find_smallest:
2957 	for (current_order = order; current_order < MAX_ORDER;
2958 							current_order++) {
2959 		area = &(zone->free_area[current_order]);
2960 		fallback_mt = find_suitable_fallback(area, current_order,
2961 				start_migratetype, false, &can_steal);
2962 		if (fallback_mt != -1)
2963 			break;
2964 	}
2965 
2966 	/*
2967 	 * This should not happen - we already found a suitable fallback
2968 	 * when looking for the largest page.
2969 	 */
2970 	VM_BUG_ON(current_order == MAX_ORDER);
2971 
2972 do_steal:
2973 	page = get_page_from_free_area(area, fallback_mt);
2974 
2975 	steal_suitable_fallback(zone, page, alloc_flags, start_migratetype,
2976 								can_steal);
2977 
2978 	trace_mm_page_alloc_extfrag(page, order, current_order,
2979 		start_migratetype, fallback_mt);
2980 
2981 	return true;
2982 
2983 }
2984 
2985 /*
2986  * Do the hard work of removing an element from the buddy allocator.
2987  * Call me with the zone->lock already held.
2988  */
2989 static __always_inline struct page *
2990 __rmqueue(struct zone *zone, unsigned int order, int migratetype,
2991 						unsigned int alloc_flags)
2992 {
2993 	struct page *page;
2994 
2995 	if (IS_ENABLED(CONFIG_CMA)) {
2996 		/*
2997 		 * Balance movable allocations between regular and CMA areas by
2998 		 * allocating from CMA when over half of the zone's free memory
2999 		 * is in the CMA area.
3000 		 */
3001 		if (alloc_flags & ALLOC_CMA &&
3002 		    zone_page_state(zone, NR_FREE_CMA_PAGES) >
3003 		    zone_page_state(zone, NR_FREE_PAGES) / 2) {
3004 			page = __rmqueue_cma_fallback(zone, order);
3005 			if (page)
3006 				goto out;
3007 		}
3008 	}
3009 retry:
3010 	page = __rmqueue_smallest(zone, order, migratetype);
3011 	if (unlikely(!page)) {
3012 		if (alloc_flags & ALLOC_CMA)
3013 			page = __rmqueue_cma_fallback(zone, order);
3014 
3015 		if (!page && __rmqueue_fallback(zone, order, migratetype,
3016 								alloc_flags))
3017 			goto retry;
3018 	}
3019 out:
3020 	if (page)
3021 		trace_mm_page_alloc_zone_locked(page, order, migratetype);
3022 	return page;
3023 }
3024 
3025 /*
3026  * Obtain a specified number of elements from the buddy allocator, all under
3027  * a single hold of the lock, for efficiency.  Add them to the supplied list.
3028  * Returns the number of new pages which were placed at *list.
3029  */
3030 static int rmqueue_bulk(struct zone *zone, unsigned int order,
3031 			unsigned long count, struct list_head *list,
3032 			int migratetype, unsigned int alloc_flags)
3033 {
3034 	int i, allocated = 0;
3035 
3036 	/*
3037 	 * local_lock_irq held so equivalent to spin_lock_irqsave for
3038 	 * both PREEMPT_RT and non-PREEMPT_RT configurations.
3039 	 */
3040 	spin_lock(&zone->lock);
3041 	for (i = 0; i < count; ++i) {
3042 		struct page *page = __rmqueue(zone, order, migratetype,
3043 								alloc_flags);
3044 		if (unlikely(page == NULL))
3045 			break;
3046 
3047 		if (unlikely(check_pcp_refill(page)))
3048 			continue;
3049 
3050 		/*
3051 		 * Split buddy pages returned by expand() are received here in
3052 		 * physical page order. The page is added to the tail of
3053 		 * caller's list. From the callers perspective, the linked list
3054 		 * is ordered by page number under some conditions. This is
3055 		 * useful for IO devices that can forward direction from the
3056 		 * head, thus also in the physical page order. This is useful
3057 		 * for IO devices that can merge IO requests if the physical
3058 		 * pages are ordered properly.
3059 		 */
3060 		list_add_tail(&page->lru, list);
3061 		allocated++;
3062 		if (is_migrate_cma(get_pcppage_migratetype(page)))
3063 			__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
3064 					      -(1 << order));
3065 	}
3066 
3067 	/*
3068 	 * i pages were removed from the buddy list even if some leak due
3069 	 * to check_pcp_refill failing so adjust NR_FREE_PAGES based
3070 	 * on i. Do not confuse with 'allocated' which is the number of
3071 	 * pages added to the pcp list.
3072 	 */
3073 	__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
3074 	spin_unlock(&zone->lock);
3075 	return allocated;
3076 }
3077 
3078 #ifdef CONFIG_NUMA
3079 /*
3080  * Called from the vmstat counter updater to drain pagesets of this
3081  * currently executing processor on remote nodes after they have
3082  * expired.
3083  *
3084  * Note that this function must be called with the thread pinned to
3085  * a single processor.
3086  */
3087 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
3088 {
3089 	unsigned long flags;
3090 	int to_drain, batch;
3091 
3092 	local_lock_irqsave(&pagesets.lock, flags);
3093 	batch = READ_ONCE(pcp->batch);
3094 	to_drain = min(pcp->count, batch);
3095 	if (to_drain > 0)
3096 		free_pcppages_bulk(zone, to_drain, pcp);
3097 	local_unlock_irqrestore(&pagesets.lock, flags);
3098 }
3099 #endif
3100 
3101 /*
3102  * Drain pcplists of the indicated processor and zone.
3103  *
3104  * The processor must either be the current processor and the
3105  * thread pinned to the current processor or a processor that
3106  * is not online.
3107  */
3108 static void drain_pages_zone(unsigned int cpu, struct zone *zone)
3109 {
3110 	unsigned long flags;
3111 	struct per_cpu_pages *pcp;
3112 
3113 	local_lock_irqsave(&pagesets.lock, flags);
3114 
3115 	pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
3116 	if (pcp->count)
3117 		free_pcppages_bulk(zone, pcp->count, pcp);
3118 
3119 	local_unlock_irqrestore(&pagesets.lock, flags);
3120 }
3121 
3122 /*
3123  * Drain pcplists of all zones on the indicated processor.
3124  *
3125  * The processor must either be the current processor and the
3126  * thread pinned to the current processor or a processor that
3127  * is not online.
3128  */
3129 static void drain_pages(unsigned int cpu)
3130 {
3131 	struct zone *zone;
3132 
3133 	for_each_populated_zone(zone) {
3134 		drain_pages_zone(cpu, zone);
3135 	}
3136 }
3137 
3138 /*
3139  * Spill all of this CPU's per-cpu pages back into the buddy allocator.
3140  *
3141  * The CPU has to be pinned. When zone parameter is non-NULL, spill just
3142  * the single zone's pages.
3143  */
3144 void drain_local_pages(struct zone *zone)
3145 {
3146 	int cpu = smp_processor_id();
3147 
3148 	if (zone)
3149 		drain_pages_zone(cpu, zone);
3150 	else
3151 		drain_pages(cpu);
3152 }
3153 
3154 static void drain_local_pages_wq(struct work_struct *work)
3155 {
3156 	struct pcpu_drain *drain;
3157 
3158 	drain = container_of(work, struct pcpu_drain, work);
3159 
3160 	/*
3161 	 * drain_all_pages doesn't use proper cpu hotplug protection so
3162 	 * we can race with cpu offline when the WQ can move this from
3163 	 * a cpu pinned worker to an unbound one. We can operate on a different
3164 	 * cpu which is alright but we also have to make sure to not move to
3165 	 * a different one.
3166 	 */
3167 	preempt_disable();
3168 	drain_local_pages(drain->zone);
3169 	preempt_enable();
3170 }
3171 
3172 /*
3173  * The implementation of drain_all_pages(), exposing an extra parameter to
3174  * drain on all cpus.
3175  *
3176  * drain_all_pages() is optimized to only execute on cpus where pcplists are
3177  * not empty. The check for non-emptiness can however race with a free to
3178  * pcplist that has not yet increased the pcp->count from 0 to 1. Callers
3179  * that need the guarantee that every CPU has drained can disable the
3180  * optimizing racy check.
3181  */
3182 static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
3183 {
3184 	int cpu;
3185 
3186 	/*
3187 	 * Allocate in the BSS so we won't require allocation in
3188 	 * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
3189 	 */
3190 	static cpumask_t cpus_with_pcps;
3191 
3192 	/*
3193 	 * Make sure nobody triggers this path before mm_percpu_wq is fully
3194 	 * initialized.
3195 	 */
3196 	if (WARN_ON_ONCE(!mm_percpu_wq))
3197 		return;
3198 
3199 	/*
3200 	 * Do not drain if one is already in progress unless it's specific to
3201 	 * a zone. Such callers are primarily CMA and memory hotplug and need
3202 	 * the drain to be complete when the call returns.
3203 	 */
3204 	if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
3205 		if (!zone)
3206 			return;
3207 		mutex_lock(&pcpu_drain_mutex);
3208 	}
3209 
3210 	/*
3211 	 * We don't care about racing with CPU hotplug event
3212 	 * as offline notification will cause the notified
3213 	 * cpu to drain that CPU pcps and on_each_cpu_mask
3214 	 * disables preemption as part of its processing
3215 	 */
3216 	for_each_online_cpu(cpu) {
3217 		struct per_cpu_pages *pcp;
3218 		struct zone *z;
3219 		bool has_pcps = false;
3220 
3221 		if (force_all_cpus) {
3222 			/*
3223 			 * The pcp.count check is racy, some callers need a
3224 			 * guarantee that no cpu is missed.
3225 			 */
3226 			has_pcps = true;
3227 		} else if (zone) {
3228 			pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
3229 			if (pcp->count)
3230 				has_pcps = true;
3231 		} else {
3232 			for_each_populated_zone(z) {
3233 				pcp = per_cpu_ptr(z->per_cpu_pageset, cpu);
3234 				if (pcp->count) {
3235 					has_pcps = true;
3236 					break;
3237 				}
3238 			}
3239 		}
3240 
3241 		if (has_pcps)
3242 			cpumask_set_cpu(cpu, &cpus_with_pcps);
3243 		else
3244 			cpumask_clear_cpu(cpu, &cpus_with_pcps);
3245 	}
3246 
3247 	for_each_cpu(cpu, &cpus_with_pcps) {
3248 		struct pcpu_drain *drain = per_cpu_ptr(&pcpu_drain, cpu);
3249 
3250 		drain->zone = zone;
3251 		INIT_WORK(&drain->work, drain_local_pages_wq);
3252 		queue_work_on(cpu, mm_percpu_wq, &drain->work);
3253 	}
3254 	for_each_cpu(cpu, &cpus_with_pcps)
3255 		flush_work(&per_cpu_ptr(&pcpu_drain, cpu)->work);
3256 
3257 	mutex_unlock(&pcpu_drain_mutex);
3258 }
3259 
3260 /*
3261  * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
3262  *
3263  * When zone parameter is non-NULL, spill just the single zone's pages.
3264  *
3265  * Note that this can be extremely slow as the draining happens in a workqueue.
3266  */
3267 void drain_all_pages(struct zone *zone)
3268 {
3269 	__drain_all_pages(zone, false);
3270 }
3271 
3272 #ifdef CONFIG_HIBERNATION
3273 
3274 /*
3275  * Touch the watchdog for every WD_PAGE_COUNT pages.
3276  */
3277 #define WD_PAGE_COUNT	(128*1024)
3278 
3279 void mark_free_pages(struct zone *zone)
3280 {
3281 	unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT;
3282 	unsigned long flags;
3283 	unsigned int order, t;
3284 	struct page *page;
3285 
3286 	if (zone_is_empty(zone))
3287 		return;
3288 
3289 	spin_lock_irqsave(&zone->lock, flags);
3290 
3291 	max_zone_pfn = zone_end_pfn(zone);
3292 	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
3293 		if (pfn_valid(pfn)) {
3294 			page = pfn_to_page(pfn);
3295 
3296 			if (!--page_count) {
3297 				touch_nmi_watchdog();
3298 				page_count = WD_PAGE_COUNT;
3299 			}
3300 
3301 			if (page_zone(page) != zone)
3302 				continue;
3303 
3304 			if (!swsusp_page_is_forbidden(page))
3305 				swsusp_unset_page_free(page);
3306 		}
3307 
3308 	for_each_migratetype_order(order, t) {
3309 		list_for_each_entry(page,
3310 				&zone->free_area[order].free_list[t], lru) {
3311 			unsigned long i;
3312 
3313 			pfn = page_to_pfn(page);
3314 			for (i = 0; i < (1UL << order); i++) {
3315 				if (!--page_count) {
3316 					touch_nmi_watchdog();
3317 					page_count = WD_PAGE_COUNT;
3318 				}
3319 				swsusp_set_page_free(pfn_to_page(pfn + i));
3320 			}
3321 		}
3322 	}
3323 	spin_unlock_irqrestore(&zone->lock, flags);
3324 }
3325 #endif /* CONFIG_PM */
3326 
3327 static bool free_unref_page_prepare(struct page *page, unsigned long pfn,
3328 							unsigned int order)
3329 {
3330 	int migratetype;
3331 
3332 	if (!free_pcp_prepare(page, order))
3333 		return false;
3334 
3335 	migratetype = get_pfnblock_migratetype(page, pfn);
3336 	set_pcppage_migratetype(page, migratetype);
3337 	return true;
3338 }
3339 
3340 static int nr_pcp_free(struct per_cpu_pages *pcp, int high, int batch)
3341 {
3342 	int min_nr_free, max_nr_free;
3343 
3344 	/* Check for PCP disabled or boot pageset */
3345 	if (unlikely(high < batch))
3346 		return 1;
3347 
3348 	/* Leave at least pcp->batch pages on the list */
3349 	min_nr_free = batch;
3350 	max_nr_free = high - batch;
3351 
3352 	/*
3353 	 * Double the number of pages freed each time there is subsequent
3354 	 * freeing of pages without any allocation.
3355 	 */
3356 	batch <<= pcp->free_factor;
3357 	if (batch < max_nr_free)
3358 		pcp->free_factor++;
3359 	batch = clamp(batch, min_nr_free, max_nr_free);
3360 
3361 	return batch;
3362 }
3363 
3364 static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone)
3365 {
3366 	int high = READ_ONCE(pcp->high);
3367 
3368 	if (unlikely(!high))
3369 		return 0;
3370 
3371 	if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
3372 		return high;
3373 
3374 	/*
3375 	 * If reclaim is active, limit the number of pages that can be
3376 	 * stored on pcp lists
3377 	 */
3378 	return min(READ_ONCE(pcp->batch) << 2, high);
3379 }
3380 
3381 static void free_unref_page_commit(struct page *page, unsigned long pfn,
3382 				   int migratetype, unsigned int order)
3383 {
3384 	struct zone *zone = page_zone(page);
3385 	struct per_cpu_pages *pcp;
3386 	int high;
3387 	int pindex;
3388 
3389 	__count_vm_event(PGFREE);
3390 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
3391 	pindex = order_to_pindex(migratetype, order);
3392 	list_add(&page->lru, &pcp->lists[pindex]);
3393 	pcp->count += 1 << order;
3394 	high = nr_pcp_high(pcp, zone);
3395 	if (pcp->count >= high) {
3396 		int batch = READ_ONCE(pcp->batch);
3397 
3398 		free_pcppages_bulk(zone, nr_pcp_free(pcp, high, batch), pcp);
3399 	}
3400 }
3401 
3402 /*
3403  * Free a pcp page
3404  */
3405 void free_unref_page(struct page *page, unsigned int order)
3406 {
3407 	unsigned long flags;
3408 	unsigned long pfn = page_to_pfn(page);
3409 	int migratetype;
3410 
3411 	if (!free_unref_page_prepare(page, pfn, order))
3412 		return;
3413 
3414 	/*
3415 	 * We only track unmovable, reclaimable and movable on pcp lists.
3416 	 * Place ISOLATE pages on the isolated list because they are being
3417 	 * offlined but treat HIGHATOMIC as movable pages so we can get those
3418 	 * areas back if necessary. Otherwise, we may have to free
3419 	 * excessively into the page allocator
3420 	 */
3421 	migratetype = get_pcppage_migratetype(page);
3422 	if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
3423 		if (unlikely(is_migrate_isolate(migratetype))) {
3424 			free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE);
3425 			return;
3426 		}
3427 		migratetype = MIGRATE_MOVABLE;
3428 	}
3429 
3430 	local_lock_irqsave(&pagesets.lock, flags);
3431 	free_unref_page_commit(page, pfn, migratetype, order);
3432 	local_unlock_irqrestore(&pagesets.lock, flags);
3433 }
3434 
3435 /*
3436  * Free a list of 0-order pages
3437  */
3438 void free_unref_page_list(struct list_head *list)
3439 {
3440 	struct page *page, *next;
3441 	unsigned long flags, pfn;
3442 	int batch_count = 0;
3443 	int migratetype;
3444 
3445 	/* Prepare pages for freeing */
3446 	list_for_each_entry_safe(page, next, list, lru) {
3447 		pfn = page_to_pfn(page);
3448 		if (!free_unref_page_prepare(page, pfn, 0))
3449 			list_del(&page->lru);
3450 
3451 		/*
3452 		 * Free isolated pages directly to the allocator, see
3453 		 * comment in free_unref_page.
3454 		 */
3455 		migratetype = get_pcppage_migratetype(page);
3456 		if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
3457 			if (unlikely(is_migrate_isolate(migratetype))) {
3458 				list_del(&page->lru);
3459 				free_one_page(page_zone(page), page, pfn, 0,
3460 							migratetype, FPI_NONE);
3461 				continue;
3462 			}
3463 
3464 			/*
3465 			 * Non-isolated types over MIGRATE_PCPTYPES get added
3466 			 * to the MIGRATE_MOVABLE pcp list.
3467 			 */
3468 			set_pcppage_migratetype(page, MIGRATE_MOVABLE);
3469 		}
3470 
3471 		set_page_private(page, pfn);
3472 	}
3473 
3474 	local_lock_irqsave(&pagesets.lock, flags);
3475 	list_for_each_entry_safe(page, next, list, lru) {
3476 		pfn = page_private(page);
3477 		set_page_private(page, 0);
3478 		migratetype = get_pcppage_migratetype(page);
3479 		trace_mm_page_free_batched(page);
3480 		free_unref_page_commit(page, pfn, migratetype, 0);
3481 
3482 		/*
3483 		 * Guard against excessive IRQ disabled times when we get
3484 		 * a large list of pages to free.
3485 		 */
3486 		if (++batch_count == SWAP_CLUSTER_MAX) {
3487 			local_unlock_irqrestore(&pagesets.lock, flags);
3488 			batch_count = 0;
3489 			local_lock_irqsave(&pagesets.lock, flags);
3490 		}
3491 	}
3492 	local_unlock_irqrestore(&pagesets.lock, flags);
3493 }
3494 
3495 /*
3496  * split_page takes a non-compound higher-order page, and splits it into
3497  * n (1<<order) sub-pages: page[0..n]
3498  * Each sub-page must be freed individually.
3499  *
3500  * Note: this is probably too low level an operation for use in drivers.
3501  * Please consult with lkml before using this in your driver.
3502  */
3503 void split_page(struct page *page, unsigned int order)
3504 {
3505 	int i;
3506 
3507 	VM_BUG_ON_PAGE(PageCompound(page), page);
3508 	VM_BUG_ON_PAGE(!page_count(page), page);
3509 
3510 	for (i = 1; i < (1 << order); i++)
3511 		set_page_refcounted(page + i);
3512 	split_page_owner(page, 1 << order);
3513 	split_page_memcg(page, 1 << order);
3514 }
3515 EXPORT_SYMBOL_GPL(split_page);
3516 
3517 int __isolate_free_page(struct page *page, unsigned int order)
3518 {
3519 	unsigned long watermark;
3520 	struct zone *zone;
3521 	int mt;
3522 
3523 	BUG_ON(!PageBuddy(page));
3524 
3525 	zone = page_zone(page);
3526 	mt = get_pageblock_migratetype(page);
3527 
3528 	if (!is_migrate_isolate(mt)) {
3529 		/*
3530 		 * Obey watermarks as if the page was being allocated. We can
3531 		 * emulate a high-order watermark check with a raised order-0
3532 		 * watermark, because we already know our high-order page
3533 		 * exists.
3534 		 */
3535 		watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
3536 		if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
3537 			return 0;
3538 
3539 		__mod_zone_freepage_state(zone, -(1UL << order), mt);
3540 	}
3541 
3542 	/* Remove page from free list */
3543 
3544 	del_page_from_free_list(page, zone, order);
3545 
3546 	/*
3547 	 * Set the pageblock if the isolated page is at least half of a
3548 	 * pageblock
3549 	 */
3550 	if (order >= pageblock_order - 1) {
3551 		struct page *endpage = page + (1 << order) - 1;
3552 		for (; page < endpage; page += pageblock_nr_pages) {
3553 			int mt = get_pageblock_migratetype(page);
3554 			if (!is_migrate_isolate(mt) && !is_migrate_cma(mt)
3555 			    && !is_migrate_highatomic(mt))
3556 				set_pageblock_migratetype(page,
3557 							  MIGRATE_MOVABLE);
3558 		}
3559 	}
3560 
3561 
3562 	return 1UL << order;
3563 }
3564 
3565 /**
3566  * __putback_isolated_page - Return a now-isolated page back where we got it
3567  * @page: Page that was isolated
3568  * @order: Order of the isolated page
3569  * @mt: The page's pageblock's migratetype
3570  *
3571  * This function is meant to return a page pulled from the free lists via
3572  * __isolate_free_page back to the free lists they were pulled from.
3573  */
3574 void __putback_isolated_page(struct page *page, unsigned int order, int mt)
3575 {
3576 	struct zone *zone = page_zone(page);
3577 
3578 	/* zone lock should be held when this function is called */
3579 	lockdep_assert_held(&zone->lock);
3580 
3581 	/* Return isolated page to tail of freelist. */
3582 	__free_one_page(page, page_to_pfn(page), zone, order, mt,
3583 			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
3584 }
3585 
3586 /*
3587  * Update NUMA hit/miss statistics
3588  *
3589  * Must be called with interrupts disabled.
3590  */
3591 static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
3592 				   long nr_account)
3593 {
3594 #ifdef CONFIG_NUMA
3595 	enum numa_stat_item local_stat = NUMA_LOCAL;
3596 
3597 	/* skip numa counters update if numa stats is disabled */
3598 	if (!static_branch_likely(&vm_numa_stat_key))
3599 		return;
3600 
3601 	if (zone_to_nid(z) != numa_node_id())
3602 		local_stat = NUMA_OTHER;
3603 
3604 	if (zone_to_nid(z) == zone_to_nid(preferred_zone))
3605 		__count_numa_events(z, NUMA_HIT, nr_account);
3606 	else {
3607 		__count_numa_events(z, NUMA_MISS, nr_account);
3608 		__count_numa_events(preferred_zone, NUMA_FOREIGN, nr_account);
3609 	}
3610 	__count_numa_events(z, local_stat, nr_account);
3611 #endif
3612 }
3613 
3614 /* Remove page from the per-cpu list, caller must protect the list */
3615 static inline
3616 struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
3617 			int migratetype,
3618 			unsigned int alloc_flags,
3619 			struct per_cpu_pages *pcp,
3620 			struct list_head *list)
3621 {
3622 	struct page *page;
3623 
3624 	do {
3625 		if (list_empty(list)) {
3626 			int batch = READ_ONCE(pcp->batch);
3627 			int alloced;
3628 
3629 			/*
3630 			 * Scale batch relative to order if batch implies
3631 			 * free pages can be stored on the PCP. Batch can
3632 			 * be 1 for small zones or for boot pagesets which
3633 			 * should never store free pages as the pages may
3634 			 * belong to arbitrary zones.
3635 			 */
3636 			if (batch > 1)
3637 				batch = max(batch >> order, 2);
3638 			alloced = rmqueue_bulk(zone, order,
3639 					batch, list,
3640 					migratetype, alloc_flags);
3641 
3642 			pcp->count += alloced << order;
3643 			if (unlikely(list_empty(list)))
3644 				return NULL;
3645 		}
3646 
3647 		page = list_first_entry(list, struct page, lru);
3648 		list_del(&page->lru);
3649 		pcp->count -= 1 << order;
3650 	} while (check_new_pcp(page));
3651 
3652 	return page;
3653 }
3654 
3655 /* Lock and remove page from the per-cpu list */
3656 static struct page *rmqueue_pcplist(struct zone *preferred_zone,
3657 			struct zone *zone, unsigned int order,
3658 			gfp_t gfp_flags, int migratetype,
3659 			unsigned int alloc_flags)
3660 {
3661 	struct per_cpu_pages *pcp;
3662 	struct list_head *list;
3663 	struct page *page;
3664 	unsigned long flags;
3665 
3666 	local_lock_irqsave(&pagesets.lock, flags);
3667 
3668 	/*
3669 	 * On allocation, reduce the number of pages that are batch freed.
3670 	 * See nr_pcp_free() where free_factor is increased for subsequent
3671 	 * frees.
3672 	 */
3673 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
3674 	pcp->free_factor >>= 1;
3675 	list = &pcp->lists[order_to_pindex(migratetype, order)];
3676 	page = __rmqueue_pcplist(zone, order, migratetype, alloc_flags, pcp, list);
3677 	local_unlock_irqrestore(&pagesets.lock, flags);
3678 	if (page) {
3679 		__count_zid_vm_events(PGALLOC, page_zonenum(page), 1);
3680 		zone_statistics(preferred_zone, zone, 1);
3681 	}
3682 	return page;
3683 }
3684 
3685 /*
3686  * Allocate a page from the given zone. Use pcplists for order-0 allocations.
3687  */
3688 static inline
3689 struct page *rmqueue(struct zone *preferred_zone,
3690 			struct zone *zone, unsigned int order,
3691 			gfp_t gfp_flags, unsigned int alloc_flags,
3692 			int migratetype)
3693 {
3694 	unsigned long flags;
3695 	struct page *page;
3696 
3697 	if (likely(pcp_allowed_order(order))) {
3698 		/*
3699 		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
3700 		 * we need to skip it when CMA area isn't allowed.
3701 		 */
3702 		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
3703 				migratetype != MIGRATE_MOVABLE) {
3704 			page = rmqueue_pcplist(preferred_zone, zone, order,
3705 					gfp_flags, migratetype, alloc_flags);
3706 			goto out;
3707 		}
3708 	}
3709 
3710 	/*
3711 	 * We most definitely don't want callers attempting to
3712 	 * allocate greater than order-1 page units with __GFP_NOFAIL.
3713 	 */
3714 	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
3715 	spin_lock_irqsave(&zone->lock, flags);
3716 
3717 	do {
3718 		page = NULL;
3719 		/*
3720 		 * order-0 request can reach here when the pcplist is skipped
3721 		 * due to non-CMA allocation context. HIGHATOMIC area is
3722 		 * reserved for high-order atomic allocation, so order-0
3723 		 * request should skip it.
3724 		 */
3725 		if (order > 0 && alloc_flags & ALLOC_HARDER) {
3726 			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
3727 			if (page)
3728 				trace_mm_page_alloc_zone_locked(page, order, migratetype);
3729 		}
3730 		if (!page)
3731 			page = __rmqueue(zone, order, migratetype, alloc_flags);
3732 	} while (page && check_new_pages(page, order));
3733 	if (!page)
3734 		goto failed;
3735 
3736 	__mod_zone_freepage_state(zone, -(1 << order),
3737 				  get_pcppage_migratetype(page));
3738 	spin_unlock_irqrestore(&zone->lock, flags);
3739 
3740 	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
3741 	zone_statistics(preferred_zone, zone, 1);
3742 
3743 out:
3744 	/* Separate test+clear to avoid unnecessary atomics */
3745 	if (test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags)) {
3746 		clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
3747 		wakeup_kswapd(zone, 0, 0, zone_idx(zone));
3748 	}
3749 
3750 	VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
3751 	return page;
3752 
3753 failed:
3754 	spin_unlock_irqrestore(&zone->lock, flags);
3755 	return NULL;
3756 }
3757 
3758 #ifdef CONFIG_FAIL_PAGE_ALLOC
3759 
3760 static struct {
3761 	struct fault_attr attr;
3762 
3763 	bool ignore_gfp_highmem;
3764 	bool ignore_gfp_reclaim;
3765 	u32 min_order;
3766 } fail_page_alloc = {
3767 	.attr = FAULT_ATTR_INITIALIZER,
3768 	.ignore_gfp_reclaim = true,
3769 	.ignore_gfp_highmem = true,
3770 	.min_order = 1,
3771 };
3772 
3773 static int __init setup_fail_page_alloc(char *str)
3774 {
3775 	return setup_fault_attr(&fail_page_alloc.attr, str);
3776 }
3777 __setup("fail_page_alloc=", setup_fail_page_alloc);
3778 
3779 static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3780 {
3781 	if (order < fail_page_alloc.min_order)
3782 		return false;
3783 	if (gfp_mask & __GFP_NOFAIL)
3784 		return false;
3785 	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
3786 		return false;
3787 	if (fail_page_alloc.ignore_gfp_reclaim &&
3788 			(gfp_mask & __GFP_DIRECT_RECLAIM))
3789 		return false;
3790 
3791 	return should_fail(&fail_page_alloc.attr, 1 << order);
3792 }
3793 
3794 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
3795 
3796 static int __init fail_page_alloc_debugfs(void)
3797 {
3798 	umode_t mode = S_IFREG | 0600;
3799 	struct dentry *dir;
3800 
3801 	dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
3802 					&fail_page_alloc.attr);
3803 
3804 	debugfs_create_bool("ignore-gfp-wait", mode, dir,
3805 			    &fail_page_alloc.ignore_gfp_reclaim);
3806 	debugfs_create_bool("ignore-gfp-highmem", mode, dir,
3807 			    &fail_page_alloc.ignore_gfp_highmem);
3808 	debugfs_create_u32("min-order", mode, dir, &fail_page_alloc.min_order);
3809 
3810 	return 0;
3811 }
3812 
3813 late_initcall(fail_page_alloc_debugfs);
3814 
3815 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
3816 
3817 #else /* CONFIG_FAIL_PAGE_ALLOC */
3818 
3819 static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3820 {
3821 	return false;
3822 }
3823 
3824 #endif /* CONFIG_FAIL_PAGE_ALLOC */
3825 
3826 noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3827 {
3828 	return __should_fail_alloc_page(gfp_mask, order);
3829 }
3830 ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);
3831 
3832 static inline long __zone_watermark_unusable_free(struct zone *z,
3833 				unsigned int order, unsigned int alloc_flags)
3834 {
3835 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
3836 	long unusable_free = (1 << order) - 1;
3837 
3838 	/*
3839 	 * If the caller does not have rights to ALLOC_HARDER then subtract
3840 	 * the high-atomic reserves. This will over-estimate the size of the
3841 	 * atomic reserve but it avoids a search.
3842 	 */
3843 	if (likely(!alloc_harder))
3844 		unusable_free += z->nr_reserved_highatomic;
3845 
3846 #ifdef CONFIG_CMA
3847 	/* If allocation can't use CMA areas don't use free CMA pages */
3848 	if (!(alloc_flags & ALLOC_CMA))
3849 		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
3850 #endif
3851 
3852 	return unusable_free;
3853 }
3854 
3855 /*
3856  * Return true if free base pages are above 'mark'. For high-order checks it
3857  * will return true of the order-0 watermark is reached and there is at least
3858  * one free page of a suitable size. Checking now avoids taking the zone lock
3859  * to check in the allocation paths if no pages are free.
3860  */
3861 bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3862 			 int highest_zoneidx, unsigned int alloc_flags,
3863 			 long free_pages)
3864 {
3865 	long min = mark;
3866 	int o;
3867 	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
3868 
3869 	/* free_pages may go negative - that's OK */
3870 	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);
3871 
3872 	if (alloc_flags & ALLOC_HIGH)
3873 		min -= min / 2;
3874 
3875 	if (unlikely(alloc_harder)) {
3876 		/*
3877 		 * OOM victims can try even harder than normal ALLOC_HARDER
3878 		 * users on the grounds that it's definitely going to be in
3879 		 * the exit path shortly and free memory. Any allocation it
3880 		 * makes during the free path will be small and short-lived.
3881 		 */
3882 		if (alloc_flags & ALLOC_OOM)
3883 			min -= min / 2;
3884 		else
3885 			min -= min / 4;
3886 	}
3887 
3888 	/*
3889 	 * Check watermarks for an order-0 allocation request. If these
3890 	 * are not met, then a high-order request also cannot go ahead
3891 	 * even if a suitable page happened to be free.
3892 	 */
3893 	if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
3894 		return false;
3895 
3896 	/* If this is an order-0 request then the watermark is fine */
3897 	if (!order)
3898 		return true;
3899 
3900 	/* For a high-order request, check at least one suitable page is free */
3901 	for (o = order; o < MAX_ORDER; o++) {
3902 		struct free_area *area = &z->free_area[o];
3903 		int mt;
3904 
3905 		if (!area->nr_free)
3906 			continue;
3907 
3908 		for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
3909 			if (!free_area_empty(area, mt))
3910 				return true;
3911 		}
3912 
3913 #ifdef CONFIG_CMA
3914 		if ((alloc_flags & ALLOC_CMA) &&
3915 		    !free_area_empty(area, MIGRATE_CMA)) {
3916 			return true;
3917 		}
3918 #endif
3919 		if (alloc_harder && !free_area_empty(area, MIGRATE_HIGHATOMIC))
3920 			return true;
3921 	}
3922 	return false;
3923 }
3924 
3925 bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
3926 		      int highest_zoneidx, unsigned int alloc_flags)
3927 {
3928 	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3929 					zone_page_state(z, NR_FREE_PAGES));
3930 }
3931 
3932 static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
3933 				unsigned long mark, int highest_zoneidx,
3934 				unsigned int alloc_flags, gfp_t gfp_mask)
3935 {
3936 	long free_pages;
3937 
3938 	free_pages = zone_page_state(z, NR_FREE_PAGES);
3939 
3940 	/*
3941 	 * Fast check for order-0 only. If this fails then the reserves
3942 	 * need to be calculated.
3943 	 */
3944 	if (!order) {
3945 		long fast_free;
3946 
3947 		fast_free = free_pages;
3948 		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
3949 		if (fast_free > mark + z->lowmem_reserve[highest_zoneidx])
3950 			return true;
3951 	}
3952 
3953 	if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
3954 					free_pages))
3955 		return true;
3956 	/*
3957 	 * Ignore watermark boosting for GFP_ATOMIC order-0 allocations
3958 	 * when checking the min watermark. The min watermark is the
3959 	 * point where boosting is ignored so that kswapd is woken up
3960 	 * when below the low watermark.
3961 	 */
3962 	if (unlikely(!order && (gfp_mask & __GFP_ATOMIC) && z->watermark_boost
3963 		&& ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
3964 		mark = z->_watermark[WMARK_MIN];
3965 		return __zone_watermark_ok(z, order, mark, highest_zoneidx,
3966 					alloc_flags, free_pages);
3967 	}
3968 
3969 	return false;
3970 }
3971 
3972 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
3973 			unsigned long mark, int highest_zoneidx)
3974 {
3975 	long free_pages = zone_page_state(z, NR_FREE_PAGES);
3976 
3977 	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
3978 		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
3979 
3980 	return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
3981 								free_pages);
3982 }
3983 
3984 #ifdef CONFIG_NUMA
3985 static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3986 {
3987 	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
3988 				node_reclaim_distance;
3989 }
3990 #else	/* CONFIG_NUMA */
3991 static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
3992 {
3993 	return true;
3994 }
3995 #endif	/* CONFIG_NUMA */
3996 
3997 /*
3998  * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
3999  * fragmentation is subtle. If the preferred zone was HIGHMEM then
4000  * premature use of a lower zone may cause lowmem pressure problems that
4001  * are worse than fragmentation. If the next zone is ZONE_DMA then it is
4002  * probably too small. It only makes sense to spread allocations to avoid
4003  * fragmentation between the Normal and DMA32 zones.
4004  */
4005 static inline unsigned int
4006 alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
4007 {
4008 	unsigned int alloc_flags;
4009 
4010 	/*
4011 	 * __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
4012 	 * to save a branch.
4013 	 */
4014 	alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);
4015 
4016 #ifdef CONFIG_ZONE_DMA32
4017 	if (!zone)
4018 		return alloc_flags;
4019 
4020 	if (zone_idx(zone) != ZONE_NORMAL)
4021 		return alloc_flags;
4022 
4023 	/*
4024 	 * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
4025 	 * the pointer is within zone->zone_pgdat->node_zones[]. Also assume
4026 	 * on UMA that if Normal is populated then so is DMA32.
4027 	 */
4028 	BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
4029 	if (nr_online_nodes > 1 && !populated_zone(--zone))
4030 		return alloc_flags;
4031 
4032 	alloc_flags |= ALLOC_NOFRAGMENT;
4033 #endif /* CONFIG_ZONE_DMA32 */
4034 	return alloc_flags;
4035 }
4036 
4037 /* Must be called after current_gfp_context() which can change gfp_mask */
4038 static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
4039 						  unsigned int alloc_flags)
4040 {
4041 #ifdef CONFIG_CMA
4042 	if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
4043 		alloc_flags |= ALLOC_CMA;
4044 #endif
4045 	return alloc_flags;
4046 }
4047 
4048 /*
4049  * get_page_from_freelist goes through the zonelist trying to allocate
4050  * a page.
4051  */
4052 static struct page *
4053 get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
4054 						const struct alloc_context *ac)
4055 {
4056 	struct zoneref *z;
4057 	struct zone *zone;
4058 	struct pglist_data *last_pgdat_dirty_limit = NULL;
4059 	bool no_fallback;
4060 
4061 retry:
4062 	/*
4063 	 * Scan zonelist, looking for a zone with enough free.
4064 	 * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
4065 	 */
4066 	no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
4067 	z = ac->preferred_zoneref;
4068 	for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
4069 					ac->nodemask) {
4070 		struct page *page;
4071 		unsigned long mark;
4072 
4073 		if (cpusets_enabled() &&
4074 			(alloc_flags & ALLOC_CPUSET) &&
4075 			!__cpuset_zone_allowed(zone, gfp_mask))
4076 				continue;
4077 		/*
4078 		 * When allocating a page cache page for writing, we
4079 		 * want to get it from a node that is within its dirty
4080 		 * limit, such that no single node holds more than its
4081 		 * proportional share of globally allowed dirty pages.
4082 		 * The dirty limits take into account the node's
4083 		 * lowmem reserves and high watermark so that kswapd
4084 		 * should be able to balance it without having to
4085 		 * write pages from its LRU list.
4086 		 *
4087 		 * XXX: For now, allow allocations to potentially
4088 		 * exceed the per-node dirty limit in the slowpath
4089 		 * (spread_dirty_pages unset) before going into reclaim,
4090 		 * which is important when on a NUMA setup the allowed
4091 		 * nodes are together not big enough to reach the
4092 		 * global limit.  The proper fix for these situations
4093 		 * will require awareness of nodes in the
4094 		 * dirty-throttling and the flusher threads.
4095 		 */
4096 		if (ac->spread_dirty_pages) {
4097 			if (last_pgdat_dirty_limit == zone->zone_pgdat)
4098 				continue;
4099 
4100 			if (!node_dirty_ok(zone->zone_pgdat)) {
4101 				last_pgdat_dirty_limit = zone->zone_pgdat;
4102 				continue;
4103 			}
4104 		}
4105 
4106 		if (no_fallback && nr_online_nodes > 1 &&
4107 		    zone != ac->preferred_zoneref->zone) {
4108 			int local_nid;
4109 
4110 			/*
4111 			 * If moving to a remote node, retry but allow
4112 			 * fragmenting fallbacks. Locality is more important
4113 			 * than fragmentation avoidance.
4114 			 */
4115 			local_nid = zone_to_nid(ac->preferred_zoneref->zone);
4116 			if (zone_to_nid(zone) != local_nid) {
4117 				alloc_flags &= ~ALLOC_NOFRAGMENT;
4118 				goto retry;
4119 			}
4120 		}
4121 
4122 		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
4123 		if (!zone_watermark_fast(zone, order, mark,
4124 				       ac->highest_zoneidx, alloc_flags,
4125 				       gfp_mask)) {
4126 			int ret;
4127 
4128 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
4129 			/*
4130 			 * Watermark failed for this zone, but see if we can
4131 			 * grow this zone if it contains deferred pages.
4132 			 */
4133 			if (static_branch_unlikely(&deferred_pages)) {
4134 				if (_deferred_grow_zone(zone, order))
4135 					goto try_this_zone;
4136 			}
4137 #endif
4138 			/* Checked here to keep the fast path fast */
4139 			BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
4140 			if (alloc_flags & ALLOC_NO_WATERMARKS)
4141 				goto try_this_zone;
4142 
4143 			if (!node_reclaim_enabled() ||
4144 			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
4145 				continue;
4146 
4147 			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
4148 			switch (ret) {
4149 			case NODE_RECLAIM_NOSCAN:
4150 				/* did not scan */
4151 				continue;
4152 			case NODE_RECLAIM_FULL:
4153 				/* scanned but unreclaimable */
4154 				continue;
4155 			default:
4156 				/* did we reclaim enough */
4157 				if (zone_watermark_ok(zone, order, mark,
4158 					ac->highest_zoneidx, alloc_flags))
4159 					goto try_this_zone;
4160 
4161 				continue;
4162 			}
4163 		}
4164 
4165 try_this_zone:
4166 		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
4167 				gfp_mask, alloc_flags, ac->migratetype);
4168 		if (page) {
4169 			prep_new_page(page, order, gfp_mask, alloc_flags);
4170 
4171 			/*
4172 			 * If this is a high-order atomic allocation then check
4173 			 * if the pageblock should be reserved for the future
4174 			 */
4175 			if (unlikely(order && (alloc_flags & ALLOC_HARDER)))
4176 				reserve_highatomic_pageblock(page, zone, order);
4177 
4178 			return page;
4179 		} else {
4180 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
4181 			/* Try again if zone has deferred pages */
4182 			if (static_branch_unlikely(&deferred_pages)) {
4183 				if (_deferred_grow_zone(zone, order))
4184 					goto try_this_zone;
4185 			}
4186 #endif
4187 		}
4188 	}
4189 
4190 	/*
4191 	 * It's possible on a UMA machine to get through all zones that are
4192 	 * fragmented. If avoiding fragmentation, reset and try again.
4193 	 */
4194 	if (no_fallback) {
4195 		alloc_flags &= ~ALLOC_NOFRAGMENT;
4196 		goto retry;
4197 	}
4198 
4199 	return NULL;
4200 }
4201 
4202 static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
4203 {
4204 	unsigned int filter = SHOW_MEM_FILTER_NODES;
4205 
4206 	/*
4207 	 * This documents exceptions given to allocations in certain
4208 	 * contexts that are allowed to allocate outside current's set
4209 	 * of allowed nodes.
4210 	 */
4211 	if (!(gfp_mask & __GFP_NOMEMALLOC))
4212 		if (tsk_is_oom_victim(current) ||
4213 		    (current->flags & (PF_MEMALLOC | PF_EXITING)))
4214 			filter &= ~SHOW_MEM_FILTER_NODES;
4215 	if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
4216 		filter &= ~SHOW_MEM_FILTER_NODES;
4217 
4218 	show_mem(filter, nodemask);
4219 }
4220 
4221 void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
4222 {
4223 	struct va_format vaf;
4224 	va_list args;
4225 	static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);
4226 
4227 	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
4228 		return;
4229 
4230 	va_start(args, fmt);
4231 	vaf.fmt = fmt;
4232 	vaf.va = &args;
4233 	pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
4234 			current->comm, &vaf, gfp_mask, &gfp_mask,
4235 			nodemask_pr_args(nodemask));
4236 	va_end(args);
4237 
4238 	cpuset_print_current_mems_allowed();
4239 	pr_cont("\n");
4240 	dump_stack();
4241 	warn_alloc_show_mem(gfp_mask, nodemask);
4242 }
4243 
4244 static inline struct page *
4245 __alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
4246 			      unsigned int alloc_flags,
4247 			      const struct alloc_context *ac)
4248 {
4249 	struct page *page;
4250 
4251 	page = get_page_from_freelist(gfp_mask, order,
4252 			alloc_flags|ALLOC_CPUSET, ac);
4253 	/*
4254 	 * fallback to ignore cpuset restriction if our nodes
4255 	 * are depleted
4256 	 */
4257 	if (!page)
4258 		page = get_page_from_freelist(gfp_mask, order,
4259 				alloc_flags, ac);
4260 
4261 	return page;
4262 }
4263 
4264 static inline struct page *
4265 __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
4266 	const struct alloc_context *ac, unsigned long *did_some_progress)
4267 {
4268 	struct oom_control oc = {
4269 		.zonelist = ac->zonelist,
4270 		.nodemask = ac->nodemask,
4271 		.memcg = NULL,
4272 		.gfp_mask = gfp_mask,
4273 		.order = order,
4274 	};
4275 	struct page *page;
4276 
4277 	*did_some_progress = 0;
4278 
4279 	/*
4280 	 * Acquire the oom lock.  If that fails, somebody else is
4281 	 * making progress for us.
4282 	 */
4283 	if (!mutex_trylock(&oom_lock)) {
4284 		*did_some_progress = 1;
4285 		schedule_timeout_uninterruptible(1);
4286 		return NULL;
4287 	}
4288 
4289 	/*
4290 	 * Go through the zonelist yet one more time, keep very high watermark
4291 	 * here, this is only to catch a parallel oom killing, we must fail if
4292 	 * we're still under heavy pressure. But make sure that this reclaim
4293 	 * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
4294 	 * allocation which will never fail due to oom_lock already held.
4295 	 */
4296 	page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
4297 				      ~__GFP_DIRECT_RECLAIM, order,
4298 				      ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
4299 	if (page)
4300 		goto out;
4301 
4302 	/* Coredumps can quickly deplete all memory reserves */
4303 	if (current->flags & PF_DUMPCORE)
4304 		goto out;
4305 	/* The OOM killer will not help higher order allocs */
4306 	if (order > PAGE_ALLOC_COSTLY_ORDER)
4307 		goto out;
4308 	/*
4309 	 * We have already exhausted all our reclaim opportunities without any
4310 	 * success so it is time to admit defeat. We will skip the OOM killer
4311 	 * because it is very likely that the caller has a more reasonable
4312 	 * fallback than shooting a random task.
4313 	 *
4314 	 * The OOM killer may not free memory on a specific node.
4315 	 */
4316 	if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
4317 		goto out;
4318 	/* The OOM killer does not needlessly kill tasks for lowmem */
4319 	if (ac->highest_zoneidx < ZONE_NORMAL)
4320 		goto out;
4321 	if (pm_suspended_storage())
4322 		goto out;
4323 	/*
4324 	 * XXX: GFP_NOFS allocations should rather fail than rely on
4325 	 * other request to make a forward progress.
4326 	 * We are in an unfortunate situation where out_of_memory cannot
4327 	 * do much for this context but let's try it to at least get
4328 	 * access to memory reserved if the current task is killed (see
4329 	 * out_of_memory). Once filesystems are ready to handle allocation
4330 	 * failures more gracefully we should just bail out here.
4331 	 */
4332 
4333 	/* Exhausted what can be done so it's blame time */
4334 	if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
4335 		*did_some_progress = 1;
4336 
4337 		/*
4338 		 * Help non-failing allocations by giving them access to memory
4339 		 * reserves
4340 		 */
4341 		if (gfp_mask & __GFP_NOFAIL)
4342 			page = __alloc_pages_cpuset_fallback(gfp_mask, order,
4343 					ALLOC_NO_WATERMARKS, ac);
4344 	}
4345 out:
4346 	mutex_unlock(&oom_lock);
4347 	return page;
4348 }
4349 
4350 /*
4351  * Maximum number of compaction retries with a progress before OOM
4352  * killer is consider as the only way to move forward.
4353  */
4354 #define MAX_COMPACT_RETRIES 16
4355 
4356 #ifdef CONFIG_COMPACTION
4357 /* Try memory compaction for high-order allocations before reclaim */
4358 static struct page *
4359 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
4360 		unsigned int alloc_flags, const struct alloc_context *ac,
4361 		enum compact_priority prio, enum compact_result *compact_result)
4362 {
4363 	struct page *page = NULL;
4364 	unsigned long pflags;
4365 	unsigned int noreclaim_flag;
4366 
4367 	if (!order)
4368 		return NULL;
4369 
4370 	psi_memstall_enter(&pflags);
4371 	noreclaim_flag = memalloc_noreclaim_save();
4372 
4373 	*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
4374 								prio, &page);
4375 
4376 	memalloc_noreclaim_restore(noreclaim_flag);
4377 	psi_memstall_leave(&pflags);
4378 
4379 	if (*compact_result == COMPACT_SKIPPED)
4380 		return NULL;
4381 	/*
4382 	 * At least in one zone compaction wasn't deferred or skipped, so let's
4383 	 * count a compaction stall
4384 	 */
4385 	count_vm_event(COMPACTSTALL);
4386 
4387 	/* Prep a captured page if available */
4388 	if (page)
4389 		prep_new_page(page, order, gfp_mask, alloc_flags);
4390 
4391 	/* Try get a page from the freelist if available */
4392 	if (!page)
4393 		page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4394 
4395 	if (page) {
4396 		struct zone *zone = page_zone(page);
4397 
4398 		zone->compact_blockskip_flush = false;
4399 		compaction_defer_reset(zone, order, true);
4400 		count_vm_event(COMPACTSUCCESS);
4401 		return page;
4402 	}
4403 
4404 	/*
4405 	 * It's bad if compaction run occurs and fails. The most likely reason
4406 	 * is that pages exist, but not enough to satisfy watermarks.
4407 	 */
4408 	count_vm_event(COMPACTFAIL);
4409 
4410 	cond_resched();
4411 
4412 	return NULL;
4413 }
4414 
4415 static inline bool
4416 should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
4417 		     enum compact_result compact_result,
4418 		     enum compact_priority *compact_priority,
4419 		     int *compaction_retries)
4420 {
4421 	int max_retries = MAX_COMPACT_RETRIES;
4422 	int min_priority;
4423 	bool ret = false;
4424 	int retries = *compaction_retries;
4425 	enum compact_priority priority = *compact_priority;
4426 
4427 	if (!order)
4428 		return false;
4429 
4430 	if (fatal_signal_pending(current))
4431 		return false;
4432 
4433 	if (compaction_made_progress(compact_result))
4434 		(*compaction_retries)++;
4435 
4436 	/*
4437 	 * compaction considers all the zone as desperately out of memory
4438 	 * so it doesn't really make much sense to retry except when the
4439 	 * failure could be caused by insufficient priority
4440 	 */
4441 	if (compaction_failed(compact_result))
4442 		goto check_priority;
4443 
4444 	/*
4445 	 * compaction was skipped because there are not enough order-0 pages
4446 	 * to work with, so we retry only if it looks like reclaim can help.
4447 	 */
4448 	if (compaction_needs_reclaim(compact_result)) {
4449 		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
4450 		goto out;
4451 	}
4452 
4453 	/*
4454 	 * make sure the compaction wasn't deferred or didn't bail out early
4455 	 * due to locks contention before we declare that we should give up.
4456 	 * But the next retry should use a higher priority if allowed, so
4457 	 * we don't just keep bailing out endlessly.
4458 	 */
4459 	if (compaction_withdrawn(compact_result)) {
4460 		goto check_priority;
4461 	}
4462 
4463 	/*
4464 	 * !costly requests are much more important than __GFP_RETRY_MAYFAIL
4465 	 * costly ones because they are de facto nofail and invoke OOM
4466 	 * killer to move on while costly can fail and users are ready
4467 	 * to cope with that. 1/4 retries is rather arbitrary but we
4468 	 * would need much more detailed feedback from compaction to
4469 	 * make a better decision.
4470 	 */
4471 	if (order > PAGE_ALLOC_COSTLY_ORDER)
4472 		max_retries /= 4;
4473 	if (*compaction_retries <= max_retries) {
4474 		ret = true;
4475 		goto out;
4476 	}
4477 
4478 	/*
4479 	 * Make sure there are attempts at the highest priority if we exhausted
4480 	 * all retries or failed at the lower priorities.
4481 	 */
4482 check_priority:
4483 	min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
4484 			MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;
4485 
4486 	if (*compact_priority > min_priority) {
4487 		(*compact_priority)--;
4488 		*compaction_retries = 0;
4489 		ret = true;
4490 	}
4491 out:
4492 	trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
4493 	return ret;
4494 }
4495 #else
4496 static inline struct page *
4497 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
4498 		unsigned int alloc_flags, const struct alloc_context *ac,
4499 		enum compact_priority prio, enum compact_result *compact_result)
4500 {
4501 	*compact_result = COMPACT_SKIPPED;
4502 	return NULL;
4503 }
4504 
4505 static inline bool
4506 should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
4507 		     enum compact_result compact_result,
4508 		     enum compact_priority *compact_priority,
4509 		     int *compaction_retries)
4510 {
4511 	struct zone *zone;
4512 	struct zoneref *z;
4513 
4514 	if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
4515 		return false;
4516 
4517 	/*
4518 	 * There are setups with compaction disabled which would prefer to loop
4519 	 * inside the allocator rather than hit the oom killer prematurely.
4520 	 * Let's give them a good hope and keep retrying while the order-0
4521 	 * watermarks are OK.
4522 	 */
4523 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
4524 				ac->highest_zoneidx, ac->nodemask) {
4525 		if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
4526 					ac->highest_zoneidx, alloc_flags))
4527 			return true;
4528 	}
4529 	return false;
4530 }
4531 #endif /* CONFIG_COMPACTION */
4532 
4533 #ifdef CONFIG_LOCKDEP
4534 static struct lockdep_map __fs_reclaim_map =
4535 	STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
4536 
4537 static bool __need_reclaim(gfp_t gfp_mask)
4538 {
4539 	/* no reclaim without waiting on it */
4540 	if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
4541 		return false;
4542 
4543 	/* this guy won't enter reclaim */
4544 	if (current->flags & PF_MEMALLOC)
4545 		return false;
4546 
4547 	if (gfp_mask & __GFP_NOLOCKDEP)
4548 		return false;
4549 
4550 	return true;
4551 }
4552 
4553 void __fs_reclaim_acquire(void)
4554 {
4555 	lock_map_acquire(&__fs_reclaim_map);
4556 }
4557 
4558 void __fs_reclaim_release(void)
4559 {
4560 	lock_map_release(&__fs_reclaim_map);
4561 }
4562 
4563 void fs_reclaim_acquire(gfp_t gfp_mask)
4564 {
4565 	gfp_mask = current_gfp_context(gfp_mask);
4566 
4567 	if (__need_reclaim(gfp_mask)) {
4568 		if (gfp_mask & __GFP_FS)
4569 			__fs_reclaim_acquire();
4570 
4571 #ifdef CONFIG_MMU_NOTIFIER
4572 		lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
4573 		lock_map_release(&__mmu_notifier_invalidate_range_start_map);
4574 #endif
4575 
4576 	}
4577 }
4578 EXPORT_SYMBOL_GPL(fs_reclaim_acquire);
4579 
4580 void fs_reclaim_release(gfp_t gfp_mask)
4581 {
4582 	gfp_mask = current_gfp_context(gfp_mask);
4583 
4584 	if (__need_reclaim(gfp_mask)) {
4585 		if (gfp_mask & __GFP_FS)
4586 			__fs_reclaim_release();
4587 	}
4588 }
4589 EXPORT_SYMBOL_GPL(fs_reclaim_release);
4590 #endif
4591 
4592 /* Perform direct synchronous page reclaim */
4593 static unsigned long
4594 __perform_reclaim(gfp_t gfp_mask, unsigned int order,
4595 					const struct alloc_context *ac)
4596 {
4597 	unsigned int noreclaim_flag;
4598 	unsigned long pflags, progress;
4599 
4600 	cond_resched();
4601 
4602 	/* We now go into synchronous reclaim */
4603 	cpuset_memory_pressure_bump();
4604 	psi_memstall_enter(&pflags);
4605 	fs_reclaim_acquire(gfp_mask);
4606 	noreclaim_flag = memalloc_noreclaim_save();
4607 
4608 	progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
4609 								ac->nodemask);
4610 
4611 	memalloc_noreclaim_restore(noreclaim_flag);
4612 	fs_reclaim_release(gfp_mask);
4613 	psi_memstall_leave(&pflags);
4614 
4615 	cond_resched();
4616 
4617 	return progress;
4618 }
4619 
4620 /* The really slow allocator path where we enter direct reclaim */
4621 static inline struct page *
4622 __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
4623 		unsigned int alloc_flags, const struct alloc_context *ac,
4624 		unsigned long *did_some_progress)
4625 {
4626 	struct page *page = NULL;
4627 	bool drained = false;
4628 
4629 	*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
4630 	if (unlikely(!(*did_some_progress)))
4631 		return NULL;
4632 
4633 retry:
4634 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4635 
4636 	/*
4637 	 * If an allocation failed after direct reclaim, it could be because
4638 	 * pages are pinned on the per-cpu lists or in high alloc reserves.
4639 	 * Shrink them and try again
4640 	 */
4641 	if (!page && !drained) {
4642 		unreserve_highatomic_pageblock(ac, false);
4643 		drain_all_pages(NULL);
4644 		drained = true;
4645 		goto retry;
4646 	}
4647 
4648 	return page;
4649 }
4650 
4651 static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
4652 			     const struct alloc_context *ac)
4653 {
4654 	struct zoneref *z;
4655 	struct zone *zone;
4656 	pg_data_t *last_pgdat = NULL;
4657 	enum zone_type highest_zoneidx = ac->highest_zoneidx;
4658 
4659 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
4660 					ac->nodemask) {
4661 		if (last_pgdat != zone->zone_pgdat)
4662 			wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
4663 		last_pgdat = zone->zone_pgdat;
4664 	}
4665 }
4666 
4667 static inline unsigned int
4668 gfp_to_alloc_flags(gfp_t gfp_mask)
4669 {
4670 	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
4671 
4672 	/*
4673 	 * __GFP_HIGH is assumed to be the same as ALLOC_HIGH
4674 	 * and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
4675 	 * to save two branches.
4676 	 */
4677 	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
4678 	BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
4679 
4680 	/*
4681 	 * The caller may dip into page reserves a bit more if the caller
4682 	 * cannot run direct reclaim, or if the caller has realtime scheduling
4683 	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
4684 	 * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_HIGH (__GFP_HIGH).
4685 	 */
4686 	alloc_flags |= (__force int)
4687 		(gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));
4688 
4689 	if (gfp_mask & __GFP_ATOMIC) {
4690 		/*
4691 		 * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
4692 		 * if it can't schedule.
4693 		 */
4694 		if (!(gfp_mask & __GFP_NOMEMALLOC))
4695 			alloc_flags |= ALLOC_HARDER;
4696 		/*
4697 		 * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
4698 		 * comment for __cpuset_node_allowed().
4699 		 */
4700 		alloc_flags &= ~ALLOC_CPUSET;
4701 	} else if (unlikely(rt_task(current)) && !in_interrupt())
4702 		alloc_flags |= ALLOC_HARDER;
4703 
4704 	alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags);
4705 
4706 	return alloc_flags;
4707 }
4708 
4709 static bool oom_reserves_allowed(struct task_struct *tsk)
4710 {
4711 	if (!tsk_is_oom_victim(tsk))
4712 		return false;
4713 
4714 	/*
4715 	 * !MMU doesn't have oom reaper so give access to memory reserves
4716 	 * only to the thread with TIF_MEMDIE set
4717 	 */
4718 	if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
4719 		return false;
4720 
4721 	return true;
4722 }
4723 
4724 /*
4725  * Distinguish requests which really need access to full memory
4726  * reserves from oom victims which can live with a portion of it
4727  */
4728 static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
4729 {
4730 	if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
4731 		return 0;
4732 	if (gfp_mask & __GFP_MEMALLOC)
4733 		return ALLOC_NO_WATERMARKS;
4734 	if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
4735 		return ALLOC_NO_WATERMARKS;
4736 	if (!in_interrupt()) {
4737 		if (current->flags & PF_MEMALLOC)
4738 			return ALLOC_NO_WATERMARKS;
4739 		else if (oom_reserves_allowed(current))
4740 			return ALLOC_OOM;
4741 	}
4742 
4743 	return 0;
4744 }
4745 
4746 bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
4747 {
4748 	return !!__gfp_pfmemalloc_flags(gfp_mask);
4749 }
4750 
4751 /*
4752  * Checks whether it makes sense to retry the reclaim to make a forward progress
4753  * for the given allocation request.
4754  *
4755  * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
4756  * without success, or when we couldn't even meet the watermark if we
4757  * reclaimed all remaining pages on the LRU lists.
4758  *
4759  * Returns true if a retry is viable or false to enter the oom path.
4760  */
4761 static inline bool
4762 should_reclaim_retry(gfp_t gfp_mask, unsigned order,
4763 		     struct alloc_context *ac, int alloc_flags,
4764 		     bool did_some_progress, int *no_progress_loops)
4765 {
4766 	struct zone *zone;
4767 	struct zoneref *z;
4768 	bool ret = false;
4769 
4770 	/*
4771 	 * Costly allocations might have made a progress but this doesn't mean
4772 	 * their order will become available due to high fragmentation so
4773 	 * always increment the no progress counter for them
4774 	 */
4775 	if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
4776 		*no_progress_loops = 0;
4777 	else
4778 		(*no_progress_loops)++;
4779 
4780 	/*
4781 	 * Make sure we converge to OOM if we cannot make any progress
4782 	 * several times in the row.
4783 	 */
4784 	if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
4785 		/* Before OOM, exhaust highatomic_reserve */
4786 		return unreserve_highatomic_pageblock(ac, true);
4787 	}
4788 
4789 	/*
4790 	 * Keep reclaiming pages while there is a chance this will lead
4791 	 * somewhere.  If none of the target zones can satisfy our allocation
4792 	 * request even if all reclaimable pages are considered then we are
4793 	 * screwed and have to go OOM.
4794 	 */
4795 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
4796 				ac->highest_zoneidx, ac->nodemask) {
4797 		unsigned long available;
4798 		unsigned long reclaimable;
4799 		unsigned long min_wmark = min_wmark_pages(zone);
4800 		bool wmark;
4801 
4802 		available = reclaimable = zone_reclaimable_pages(zone);
4803 		available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
4804 
4805 		/*
4806 		 * Would the allocation succeed if we reclaimed all
4807 		 * reclaimable pages?
4808 		 */
4809 		wmark = __zone_watermark_ok(zone, order, min_wmark,
4810 				ac->highest_zoneidx, alloc_flags, available);
4811 		trace_reclaim_retry_zone(z, order, reclaimable,
4812 				available, min_wmark, *no_progress_loops, wmark);
4813 		if (wmark) {
4814 			/*
4815 			 * If we didn't make any progress and have a lot of
4816 			 * dirty + writeback pages then we should wait for
4817 			 * an IO to complete to slow down the reclaim and
4818 			 * prevent from pre mature OOM
4819 			 */
4820 			if (!did_some_progress) {
4821 				unsigned long write_pending;
4822 
4823 				write_pending = zone_page_state_snapshot(zone,
4824 							NR_ZONE_WRITE_PENDING);
4825 
4826 				if (2 * write_pending > reclaimable) {
4827 					congestion_wait(BLK_RW_ASYNC, HZ/10);
4828 					return true;
4829 				}
4830 			}
4831 
4832 			ret = true;
4833 			goto out;
4834 		}
4835 	}
4836 
4837 out:
4838 	/*
4839 	 * Memory allocation/reclaim might be called from a WQ context and the
4840 	 * current implementation of the WQ concurrency control doesn't
4841 	 * recognize that a particular WQ is congested if the worker thread is
4842 	 * looping without ever sleeping. Therefore we have to do a short sleep
4843 	 * here rather than calling cond_resched().
4844 	 */
4845 	if (current->flags & PF_WQ_WORKER)
4846 		schedule_timeout_uninterruptible(1);
4847 	else
4848 		cond_resched();
4849 	return ret;
4850 }
4851 
4852 static inline bool
4853 check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
4854 {
4855 	/*
4856 	 * It's possible that cpuset's mems_allowed and the nodemask from
4857 	 * mempolicy don't intersect. This should be normally dealt with by
4858 	 * policy_nodemask(), but it's possible to race with cpuset update in
4859 	 * such a way the check therein was true, and then it became false
4860 	 * before we got our cpuset_mems_cookie here.
4861 	 * This assumes that for all allocations, ac->nodemask can come only
4862 	 * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
4863 	 * when it does not intersect with the cpuset restrictions) or the
4864 	 * caller can deal with a violated nodemask.
4865 	 */
4866 	if (cpusets_enabled() && ac->nodemask &&
4867 			!cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
4868 		ac->nodemask = NULL;
4869 		return true;
4870 	}
4871 
4872 	/*
4873 	 * When updating a task's mems_allowed or mempolicy nodemask, it is
4874 	 * possible to race with parallel threads in such a way that our
4875 	 * allocation can fail while the mask is being updated. If we are about
4876 	 * to fail, check if the cpuset changed during allocation and if so,
4877 	 * retry.
4878 	 */
4879 	if (read_mems_allowed_retry(cpuset_mems_cookie))
4880 		return true;
4881 
4882 	return false;
4883 }
4884 
4885 static inline struct page *
4886 __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
4887 						struct alloc_context *ac)
4888 {
4889 	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
4890 	const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
4891 	struct page *page = NULL;
4892 	unsigned int alloc_flags;
4893 	unsigned long did_some_progress;
4894 	enum compact_priority compact_priority;
4895 	enum compact_result compact_result;
4896 	int compaction_retries;
4897 	int no_progress_loops;
4898 	unsigned int cpuset_mems_cookie;
4899 	int reserve_flags;
4900 
4901 	/*
4902 	 * We also sanity check to catch abuse of atomic reserves being used by
4903 	 * callers that are not in atomic context.
4904 	 */
4905 	if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
4906 				(__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
4907 		gfp_mask &= ~__GFP_ATOMIC;
4908 
4909 retry_cpuset:
4910 	compaction_retries = 0;
4911 	no_progress_loops = 0;
4912 	compact_priority = DEF_COMPACT_PRIORITY;
4913 	cpuset_mems_cookie = read_mems_allowed_begin();
4914 
4915 	/*
4916 	 * The fast path uses conservative alloc_flags to succeed only until
4917 	 * kswapd needs to be woken up, and to avoid the cost of setting up
4918 	 * alloc_flags precisely. So we do that now.
4919 	 */
4920 	alloc_flags = gfp_to_alloc_flags(gfp_mask);
4921 
4922 	/*
4923 	 * We need to recalculate the starting point for the zonelist iterator
4924 	 * because we might have used different nodemask in the fast path, or
4925 	 * there was a cpuset modification and we are retrying - otherwise we
4926 	 * could end up iterating over non-eligible zones endlessly.
4927 	 */
4928 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
4929 					ac->highest_zoneidx, ac->nodemask);
4930 	if (!ac->preferred_zoneref->zone)
4931 		goto nopage;
4932 
4933 	if (alloc_flags & ALLOC_KSWAPD)
4934 		wake_all_kswapds(order, gfp_mask, ac);
4935 
4936 	/*
4937 	 * The adjusted alloc_flags might result in immediate success, so try
4938 	 * that first
4939 	 */
4940 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
4941 	if (page)
4942 		goto got_pg;
4943 
4944 	/*
4945 	 * For costly allocations, try direct compaction first, as it's likely
4946 	 * that we have enough base pages and don't need to reclaim. For non-
4947 	 * movable high-order allocations, do that as well, as compaction will
4948 	 * try prevent permanent fragmentation by migrating from blocks of the
4949 	 * same migratetype.
4950 	 * Don't try this for allocations that are allowed to ignore
4951 	 * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
4952 	 */
4953 	if (can_direct_reclaim &&
4954 			(costly_order ||
4955 			   (order > 0 && ac->migratetype != MIGRATE_MOVABLE))
4956 			&& !gfp_pfmemalloc_allowed(gfp_mask)) {
4957 		page = __alloc_pages_direct_compact(gfp_mask, order,
4958 						alloc_flags, ac,
4959 						INIT_COMPACT_PRIORITY,
4960 						&compact_result);
4961 		if (page)
4962 			goto got_pg;
4963 
4964 		/*
4965 		 * Checks for costly allocations with __GFP_NORETRY, which
4966 		 * includes some THP page fault allocations
4967 		 */
4968 		if (costly_order && (gfp_mask & __GFP_NORETRY)) {
4969 			/*
4970 			 * If allocating entire pageblock(s) and compaction
4971 			 * failed because all zones are below low watermarks
4972 			 * or is prohibited because it recently failed at this
4973 			 * order, fail immediately unless the allocator has
4974 			 * requested compaction and reclaim retry.
4975 			 *
4976 			 * Reclaim is
4977 			 *  - potentially very expensive because zones are far
4978 			 *    below their low watermarks or this is part of very
4979 			 *    bursty high order allocations,
4980 			 *  - not guaranteed to help because isolate_freepages()
4981 			 *    may not iterate over freed pages as part of its
4982 			 *    linear scan, and
4983 			 *  - unlikely to make entire pageblocks free on its
4984 			 *    own.
4985 			 */
4986 			if (compact_result == COMPACT_SKIPPED ||
4987 			    compact_result == COMPACT_DEFERRED)
4988 				goto nopage;
4989 
4990 			/*
4991 			 * Looks like reclaim/compaction is worth trying, but
4992 			 * sync compaction could be very expensive, so keep
4993 			 * using async compaction.
4994 			 */
4995 			compact_priority = INIT_COMPACT_PRIORITY;
4996 		}
4997 	}
4998 
4999 retry:
5000 	/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
5001 	if (alloc_flags & ALLOC_KSWAPD)
5002 		wake_all_kswapds(order, gfp_mask, ac);
5003 
5004 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
5005 	if (reserve_flags)
5006 		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags);
5007 
5008 	/*
5009 	 * Reset the nodemask and zonelist iterators if memory policies can be
5010 	 * ignored. These allocations are high priority and system rather than
5011 	 * user oriented.
5012 	 */
5013 	if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
5014 		ac->nodemask = NULL;
5015 		ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
5016 					ac->highest_zoneidx, ac->nodemask);
5017 	}
5018 
5019 	/* Attempt with potentially adjusted zonelist and alloc_flags */
5020 	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
5021 	if (page)
5022 		goto got_pg;
5023 
5024 	/* Caller is not willing to reclaim, we can't balance anything */
5025 	if (!can_direct_reclaim)
5026 		goto nopage;
5027 
5028 	/* Avoid recursion of direct reclaim */
5029 	if (current->flags & PF_MEMALLOC)
5030 		goto nopage;
5031 
5032 	/* Try direct reclaim and then allocating */
5033 	page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
5034 							&did_some_progress);
5035 	if (page)
5036 		goto got_pg;
5037 
5038 	/* Try direct compaction and then allocating */
5039 	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
5040 					compact_priority, &compact_result);
5041 	if (page)
5042 		goto got_pg;
5043 
5044 	/* Do not loop if specifically requested */
5045 	if (gfp_mask & __GFP_NORETRY)
5046 		goto nopage;
5047 
5048 	/*
5049 	 * Do not retry costly high order allocations unless they are
5050 	 * __GFP_RETRY_MAYFAIL
5051 	 */
5052 	if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
5053 		goto nopage;
5054 
5055 	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
5056 				 did_some_progress > 0, &no_progress_loops))
5057 		goto retry;
5058 
5059 	/*
5060 	 * It doesn't make any sense to retry for the compaction if the order-0
5061 	 * reclaim is not able to make any progress because the current
5062 	 * implementation of the compaction depends on the sufficient amount
5063 	 * of free memory (see __compaction_suitable)
5064 	 */
5065 	if (did_some_progress > 0 &&
5066 			should_compact_retry(ac, order, alloc_flags,
5067 				compact_result, &compact_priority,
5068 				&compaction_retries))
5069 		goto retry;
5070 
5071 
5072 	/* Deal with possible cpuset update races before we start OOM killing */
5073 	if (check_retry_cpuset(cpuset_mems_cookie, ac))
5074 		goto retry_cpuset;
5075 
5076 	/* Reclaim has failed us, start killing things */
5077 	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
5078 	if (page)
5079 		goto got_pg;
5080 
5081 	/* Avoid allocations with no watermarks from looping endlessly */
5082 	if (tsk_is_oom_victim(current) &&
5083 	    (alloc_flags & ALLOC_OOM ||
5084 	     (gfp_mask & __GFP_NOMEMALLOC)))
5085 		goto nopage;
5086 
5087 	/* Retry as long as the OOM killer is making progress */
5088 	if (did_some_progress) {
5089 		no_progress_loops = 0;
5090 		goto retry;
5091 	}
5092 
5093 nopage:
5094 	/* Deal with possible cpuset update races before we fail */
5095 	if (check_retry_cpuset(cpuset_mems_cookie, ac))
5096 		goto retry_cpuset;
5097 
5098 	/*
5099 	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
5100 	 * we always retry
5101 	 */
5102 	if (gfp_mask & __GFP_NOFAIL) {
5103 		/*
5104 		 * All existing users of the __GFP_NOFAIL are blockable, so warn
5105 		 * of any new users that actually require GFP_NOWAIT
5106 		 */
5107 		if (WARN_ON_ONCE(!can_direct_reclaim))
5108 			goto fail;
5109 
5110 		/*
5111 		 * PF_MEMALLOC request from this context is rather bizarre
5112 		 * because we cannot reclaim anything and only can loop waiting
5113 		 * for somebody to do a work for us
5114 		 */
5115 		WARN_ON_ONCE(current->flags & PF_MEMALLOC);
5116 
5117 		/*
5118 		 * non failing costly orders are a hard requirement which we
5119 		 * are not prepared for much so let's warn about these users
5120 		 * so that we can identify them and convert them to something
5121 		 * else.
5122 		 */
5123 		WARN_ON_ONCE(order > PAGE_ALLOC_COSTLY_ORDER);
5124 
5125 		/*
5126 		 * Help non-failing allocations by giving them access to memory
5127 		 * reserves but do not use ALLOC_NO_WATERMARKS because this
5128 		 * could deplete whole memory reserves which would just make
5129 		 * the situation worse
5130 		 */
5131 		page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac);
5132 		if (page)
5133 			goto got_pg;
5134 
5135 		cond_resched();
5136 		goto retry;
5137 	}
5138 fail:
5139 	warn_alloc(gfp_mask, ac->nodemask,
5140 			"page allocation failure: order:%u", order);
5141 got_pg:
5142 	return page;
5143 }
5144 
5145 static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
5146 		int preferred_nid, nodemask_t *nodemask,
5147 		struct alloc_context *ac, gfp_t *alloc_gfp,
5148 		unsigned int *alloc_flags)
5149 {
5150 	ac->highest_zoneidx = gfp_zone(gfp_mask);
5151 	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
5152 	ac->nodemask = nodemask;
5153 	ac->migratetype = gfp_migratetype(gfp_mask);
5154 
5155 	if (cpusets_enabled()) {
5156 		*alloc_gfp |= __GFP_HARDWALL;
5157 		/*
5158 		 * When we are in the interrupt context, it is irrelevant
5159 		 * to the current task context. It means that any node ok.
5160 		 */
5161 		if (!in_interrupt() && !ac->nodemask)
5162 			ac->nodemask = &cpuset_current_mems_allowed;
5163 		else
5164 			*alloc_flags |= ALLOC_CPUSET;
5165 	}
5166 
5167 	fs_reclaim_acquire(gfp_mask);
5168 	fs_reclaim_release(gfp_mask);
5169 
5170 	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
5171 
5172 	if (should_fail_alloc_page(gfp_mask, order))
5173 		return false;
5174 
5175 	*alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags);
5176 
5177 	/* Dirty zone balancing only done in the fast path */
5178 	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
5179 
5180 	/*
5181 	 * The preferred zone is used for statistics but crucially it is
5182 	 * also used as the starting point for the zonelist iterator. It
5183 	 * may get reset for allocations that ignore memory policies.
5184 	 */
5185 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
5186 					ac->highest_zoneidx, ac->nodemask);
5187 
5188 	return true;
5189 }
5190 
5191 /*
5192  * __alloc_pages_bulk - Allocate a number of order-0 pages to a list or array
5193  * @gfp: GFP flags for the allocation
5194  * @preferred_nid: The preferred NUMA node ID to allocate from
5195  * @nodemask: Set of nodes to allocate from, may be NULL
5196  * @nr_pages: The number of pages desired on the list or array
5197  * @page_list: Optional list to store the allocated pages
5198  * @page_array: Optional array to store the pages
5199  *
5200  * This is a batched version of the page allocator that attempts to
5201  * allocate nr_pages quickly. Pages are added to page_list if page_list
5202  * is not NULL, otherwise it is assumed that the page_array is valid.
5203  *
5204  * For lists, nr_pages is the number of pages that should be allocated.
5205  *
5206  * For arrays, only NULL elements are populated with pages and nr_pages
5207  * is the maximum number of pages that will be stored in the array.
5208  *
5209  * Returns the number of pages on the list or array.
5210  */
5211 unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
5212 			nodemask_t *nodemask, int nr_pages,
5213 			struct list_head *page_list,
5214 			struct page **page_array)
5215 {
5216 	struct page *page;
5217 	unsigned long flags;
5218 	struct zone *zone;
5219 	struct zoneref *z;
5220 	struct per_cpu_pages *pcp;
5221 	struct list_head *pcp_list;
5222 	struct alloc_context ac;
5223 	gfp_t alloc_gfp;
5224 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
5225 	int nr_populated = 0, nr_account = 0;
5226 
5227 	/*
5228 	 * Skip populated array elements to determine if any pages need
5229 	 * to be allocated before disabling IRQs.
5230 	 */
5231 	while (page_array && nr_populated < nr_pages && page_array[nr_populated])
5232 		nr_populated++;
5233 
5234 	/* No pages requested? */
5235 	if (unlikely(nr_pages <= 0))
5236 		goto out;
5237 
5238 	/* Already populated array? */
5239 	if (unlikely(page_array && nr_pages - nr_populated == 0))
5240 		goto out;
5241 
5242 	/* Use the single page allocator for one page. */
5243 	if (nr_pages - nr_populated == 1)
5244 		goto failed;
5245 
5246 #ifdef CONFIG_PAGE_OWNER
5247 	/*
5248 	 * PAGE_OWNER may recurse into the allocator to allocate space to
5249 	 * save the stack with pagesets.lock held. Releasing/reacquiring
5250 	 * removes much of the performance benefit of bulk allocation so
5251 	 * force the caller to allocate one page at a time as it'll have
5252 	 * similar performance to added complexity to the bulk allocator.
5253 	 */
5254 	if (static_branch_unlikely(&page_owner_inited))
5255 		goto failed;
5256 #endif
5257 
5258 	/* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */
5259 	gfp &= gfp_allowed_mask;
5260 	alloc_gfp = gfp;
5261 	if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
5262 		goto out;
5263 	gfp = alloc_gfp;
5264 
5265 	/* Find an allowed local zone that meets the low watermark. */
5266 	for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
5267 		unsigned long mark;
5268 
5269 		if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
5270 		    !__cpuset_zone_allowed(zone, gfp)) {
5271 			continue;
5272 		}
5273 
5274 		if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
5275 		    zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
5276 			goto failed;
5277 		}
5278 
5279 		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
5280 		if (zone_watermark_fast(zone, 0,  mark,
5281 				zonelist_zone_idx(ac.preferred_zoneref),
5282 				alloc_flags, gfp)) {
5283 			break;
5284 		}
5285 	}
5286 
5287 	/*
5288 	 * If there are no allowed local zones that meets the watermarks then
5289 	 * try to allocate a single page and reclaim if necessary.
5290 	 */
5291 	if (unlikely(!zone))
5292 		goto failed;
5293 
5294 	/* Attempt the batch allocation */
5295 	local_lock_irqsave(&pagesets.lock, flags);
5296 	pcp = this_cpu_ptr(zone->per_cpu_pageset);
5297 	pcp_list = &pcp->lists[order_to_pindex(ac.migratetype, 0)];
5298 
5299 	while (nr_populated < nr_pages) {
5300 
5301 		/* Skip existing pages */
5302 		if (page_array && page_array[nr_populated]) {
5303 			nr_populated++;
5304 			continue;
5305 		}
5306 
5307 		page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
5308 								pcp, pcp_list);
5309 		if (unlikely(!page)) {
5310 			/* Try and get at least one page */
5311 			if (!nr_populated)
5312 				goto failed_irq;
5313 			break;
5314 		}
5315 		nr_account++;
5316 
5317 		prep_new_page(page, 0, gfp, 0);
5318 		if (page_list)
5319 			list_add(&page->lru, page_list);
5320 		else
5321 			page_array[nr_populated] = page;
5322 		nr_populated++;
5323 	}
5324 
5325 	local_unlock_irqrestore(&pagesets.lock, flags);
5326 
5327 	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
5328 	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
5329 
5330 out:
5331 	return nr_populated;
5332 
5333 failed_irq:
5334 	local_unlock_irqrestore(&pagesets.lock, flags);
5335 
5336 failed:
5337 	page = __alloc_pages(gfp, 0, preferred_nid, nodemask);
5338 	if (page) {
5339 		if (page_list)
5340 			list_add(&page->lru, page_list);
5341 		else
5342 			page_array[nr_populated] = page;
5343 		nr_populated++;
5344 	}
5345 
5346 	goto out;
5347 }
5348 EXPORT_SYMBOL_GPL(__alloc_pages_bulk);
5349 
5350 /*
5351  * This is the 'heart' of the zoned buddy allocator.
5352  */
5353 struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
5354 							nodemask_t *nodemask)
5355 {
5356 	struct page *page;
5357 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
5358 	gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */
5359 	struct alloc_context ac = { };
5360 
5361 	/*
5362 	 * There are several places where we assume that the order value is sane
5363 	 * so bail out early if the request is out of bound.
5364 	 */
5365 	if (unlikely(order >= MAX_ORDER)) {
5366 		WARN_ON_ONCE(!(gfp & __GFP_NOWARN));
5367 		return NULL;
5368 	}
5369 
5370 	gfp &= gfp_allowed_mask;
5371 	/*
5372 	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
5373 	 * resp. GFP_NOIO which has to be inherited for all allocation requests
5374 	 * from a particular context which has been marked by
5375 	 * memalloc_no{fs,io}_{save,restore}. And PF_MEMALLOC_PIN which ensures
5376 	 * movable zones are not used during allocation.
5377 	 */
5378 	gfp = current_gfp_context(gfp);
5379 	alloc_gfp = gfp;
5380 	if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
5381 			&alloc_gfp, &alloc_flags))
5382 		return NULL;
5383 
5384 	/*
5385 	 * Forbid the first pass from falling back to types that fragment
5386 	 * memory until all local zones are considered.
5387 	 */
5388 	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
5389 
5390 	/* First allocation attempt */
5391 	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
5392 	if (likely(page))
5393 		goto out;
5394 
5395 	alloc_gfp = gfp;
5396 	ac.spread_dirty_pages = false;
5397 
5398 	/*
5399 	 * Restore the original nodemask if it was potentially replaced with
5400 	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
5401 	 */
5402 	ac.nodemask = nodemask;
5403 
5404 	page = __alloc_pages_slowpath(alloc_gfp, order, &ac);
5405 
5406 out:
5407 	if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page &&
5408 	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
5409 		__free_pages(page, order);
5410 		page = NULL;
5411 	}
5412 
5413 	trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
5414 
5415 	return page;
5416 }
5417 EXPORT_SYMBOL(__alloc_pages);
5418 
5419 /*
5420  * Common helper functions. Never use with __GFP_HIGHMEM because the returned
5421  * address cannot represent highmem pages. Use alloc_pages and then kmap if
5422  * you need to access high mem.
5423  */
5424 unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
5425 {
5426 	struct page *page;
5427 
5428 	page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
5429 	if (!page)
5430 		return 0;
5431 	return (unsigned long) page_address(page);
5432 }
5433 EXPORT_SYMBOL(__get_free_pages);
5434 
5435 unsigned long get_zeroed_page(gfp_t gfp_mask)
5436 {
5437 	return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
5438 }
5439 EXPORT_SYMBOL(get_zeroed_page);
5440 
5441 /**
5442  * __free_pages - Free pages allocated with alloc_pages().
5443  * @page: The page pointer returned from alloc_pages().
5444  * @order: The order of the allocation.
5445  *
5446  * This function can free multi-page allocations that are not compound
5447  * pages.  It does not check that the @order passed in matches that of
5448  * the allocation, so it is easy to leak memory.  Freeing more memory
5449  * than was allocated will probably emit a warning.
5450  *
5451  * If the last reference to this page is speculative, it will be released
5452  * by put_page() which only frees the first page of a non-compound
5453  * allocation.  To prevent the remaining pages from being leaked, we free
5454  * the subsequent pages here.  If you want to use the page's reference
5455  * count to decide when to free the allocation, you should allocate a
5456  * compound page, and use put_page() instead of __free_pages().
5457  *
5458  * Context: May be called in interrupt context or while holding a normal
5459  * spinlock, but not in NMI context or while holding a raw spinlock.
5460  */
5461 void __free_pages(struct page *page, unsigned int order)
5462 {
5463 	if (put_page_testzero(page))
5464 		free_the_page(page, order);
5465 	else if (!PageHead(page))
5466 		while (order-- > 0)
5467 			free_the_page(page + (1 << order), order);
5468 }
5469 EXPORT_SYMBOL(__free_pages);
5470 
5471 void free_pages(unsigned long addr, unsigned int order)
5472 {
5473 	if (addr != 0) {
5474 		VM_BUG_ON(!virt_addr_valid((void *)addr));
5475 		__free_pages(virt_to_page((void *)addr), order);
5476 	}
5477 }
5478 
5479 EXPORT_SYMBOL(free_pages);
5480 
5481 /*
5482  * Page Fragment:
5483  *  An arbitrary-length arbitrary-offset area of memory which resides
5484  *  within a 0 or higher order page.  Multiple fragments within that page
5485  *  are individually refcounted, in the page's reference counter.
5486  *
5487  * The page_frag functions below provide a simple allocation framework for
5488  * page fragments.  This is used by the network stack and network device
5489  * drivers to provide a backing region of memory for use as either an
5490  * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
5491  */
5492 static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
5493 					     gfp_t gfp_mask)
5494 {
5495 	struct page *page = NULL;
5496 	gfp_t gfp = gfp_mask;
5497 
5498 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5499 	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
5500 		    __GFP_NOMEMALLOC;
5501 	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
5502 				PAGE_FRAG_CACHE_MAX_ORDER);
5503 	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
5504 #endif
5505 	if (unlikely(!page))
5506 		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
5507 
5508 	nc->va = page ? page_address(page) : NULL;
5509 
5510 	return page;
5511 }
5512 
5513 void __page_frag_cache_drain(struct page *page, unsigned int count)
5514 {
5515 	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
5516 
5517 	if (page_ref_sub_and_test(page, count))
5518 		free_the_page(page, compound_order(page));
5519 }
5520 EXPORT_SYMBOL(__page_frag_cache_drain);
5521 
5522 void *page_frag_alloc_align(struct page_frag_cache *nc,
5523 		      unsigned int fragsz, gfp_t gfp_mask,
5524 		      unsigned int align_mask)
5525 {
5526 	unsigned int size = PAGE_SIZE;
5527 	struct page *page;
5528 	int offset;
5529 
5530 	if (unlikely(!nc->va)) {
5531 refill:
5532 		page = __page_frag_cache_refill(nc, gfp_mask);
5533 		if (!page)
5534 			return NULL;
5535 
5536 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5537 		/* if size can vary use size else just use PAGE_SIZE */
5538 		size = nc->size;
5539 #endif
5540 		/* Even if we own the page, we do not use atomic_set().
5541 		 * This would break get_page_unless_zero() users.
5542 		 */
5543 		page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
5544 
5545 		/* reset page count bias and offset to start of new frag */
5546 		nc->pfmemalloc = page_is_pfmemalloc(page);
5547 		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
5548 		nc->offset = size;
5549 	}
5550 
5551 	offset = nc->offset - fragsz;
5552 	if (unlikely(offset < 0)) {
5553 		page = virt_to_page(nc->va);
5554 
5555 		if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
5556 			goto refill;
5557 
5558 		if (unlikely(nc->pfmemalloc)) {
5559 			free_the_page(page, compound_order(page));
5560 			goto refill;
5561 		}
5562 
5563 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
5564 		/* if size can vary use size else just use PAGE_SIZE */
5565 		size = nc->size;
5566 #endif
5567 		/* OK, page count is 0, we can safely set it */
5568 		set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
5569 
5570 		/* reset page count bias and offset to start of new frag */
5571 		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
5572 		offset = size - fragsz;
5573 	}
5574 
5575 	nc->pagecnt_bias--;
5576 	offset &= align_mask;
5577 	nc->offset = offset;
5578 
5579 	return nc->va + offset;
5580 }
5581 EXPORT_SYMBOL(page_frag_alloc_align);
5582 
5583 /*
5584  * Frees a page fragment allocated out of either a compound or order 0 page.
5585  */
5586 void page_frag_free(void *addr)
5587 {
5588 	struct page *page = virt_to_head_page(addr);
5589 
5590 	if (unlikely(put_page_testzero(page)))
5591 		free_the_page(page, compound_order(page));
5592 }
5593 EXPORT_SYMBOL(page_frag_free);
5594 
5595 static void *make_alloc_exact(unsigned long addr, unsigned int order,
5596 		size_t size)
5597 {
5598 	if (addr) {
5599 		unsigned long alloc_end = addr + (PAGE_SIZE << order);
5600 		unsigned long used = addr + PAGE_ALIGN(size);
5601 
5602 		split_page(virt_to_page((void *)addr), order);
5603 		while (used < alloc_end) {
5604 			free_page(used);
5605 			used += PAGE_SIZE;
5606 		}
5607 	}
5608 	return (void *)addr;
5609 }
5610 
5611 /**
5612  * alloc_pages_exact - allocate an exact number physically-contiguous pages.
5613  * @size: the number of bytes to allocate
5614  * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5615  *
5616  * This function is similar to alloc_pages(), except that it allocates the
5617  * minimum number of pages to satisfy the request.  alloc_pages() can only
5618  * allocate memory in power-of-two pages.
5619  *
5620  * This function is also limited by MAX_ORDER.
5621  *
5622  * Memory allocated by this function must be released by free_pages_exact().
5623  *
5624  * Return: pointer to the allocated area or %NULL in case of error.
5625  */
5626 void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
5627 {
5628 	unsigned int order = get_order(size);
5629 	unsigned long addr;
5630 
5631 	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
5632 		gfp_mask &= ~__GFP_COMP;
5633 
5634 	addr = __get_free_pages(gfp_mask, order);
5635 	return make_alloc_exact(addr, order, size);
5636 }
5637 EXPORT_SYMBOL(alloc_pages_exact);
5638 
5639 /**
5640  * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
5641  *			   pages on a node.
5642  * @nid: the preferred node ID where memory should be allocated
5643  * @size: the number of bytes to allocate
5644  * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
5645  *
5646  * Like alloc_pages_exact(), but try to allocate on node nid first before falling
5647  * back.
5648  *
5649  * Return: pointer to the allocated area or %NULL in case of error.
5650  */
5651 void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
5652 {
5653 	unsigned int order = get_order(size);
5654 	struct page *p;
5655 
5656 	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
5657 		gfp_mask &= ~__GFP_COMP;
5658 
5659 	p = alloc_pages_node(nid, gfp_mask, order);
5660 	if (!p)
5661 		return NULL;
5662 	return make_alloc_exact((unsigned long)page_address(p), order, size);
5663 }
5664 
5665 /**
5666  * free_pages_exact - release memory allocated via alloc_pages_exact()
5667  * @virt: the value returned by alloc_pages_exact.
5668  * @size: size of allocation, same value as passed to alloc_pages_exact().
5669  *
5670  * Release the memory allocated by a previous call to alloc_pages_exact.
5671  */
5672 void free_pages_exact(void *virt, size_t size)
5673 {
5674 	unsigned long addr = (unsigned long)virt;
5675 	unsigned long end = addr + PAGE_ALIGN(size);
5676 
5677 	while (addr < end) {
5678 		free_page(addr);
5679 		addr += PAGE_SIZE;
5680 	}
5681 }
5682 EXPORT_SYMBOL(free_pages_exact);
5683 
5684 /**
5685  * nr_free_zone_pages - count number of pages beyond high watermark
5686  * @offset: The zone index of the highest zone
5687  *
5688  * nr_free_zone_pages() counts the number of pages which are beyond the
5689  * high watermark within all zones at or below a given zone index.  For each
5690  * zone, the number of pages is calculated as:
5691  *
5692  *     nr_free_zone_pages = managed_pages - high_pages
5693  *
5694  * Return: number of pages beyond high watermark.
5695  */
5696 static unsigned long nr_free_zone_pages(int offset)
5697 {
5698 	struct zoneref *z;
5699 	struct zone *zone;
5700 
5701 	/* Just pick one node, since fallback list is circular */
5702 	unsigned long sum = 0;
5703 
5704 	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
5705 
5706 	for_each_zone_zonelist(zone, z, zonelist, offset) {
5707 		unsigned long size = zone_managed_pages(zone);
5708 		unsigned long high = high_wmark_pages(zone);
5709 		if (size > high)
5710 			sum += size - high;
5711 	}
5712 
5713 	return sum;
5714 }
5715 
5716 /**
5717  * nr_free_buffer_pages - count number of pages beyond high watermark
5718  *
5719  * nr_free_buffer_pages() counts the number of pages which are beyond the high
5720  * watermark within ZONE_DMA and ZONE_NORMAL.
5721  *
5722  * Return: number of pages beyond high watermark within ZONE_DMA and
5723  * ZONE_NORMAL.
5724  */
5725 unsigned long nr_free_buffer_pages(void)
5726 {
5727 	return nr_free_zone_pages(gfp_zone(GFP_USER));
5728 }
5729 EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
5730 
5731 static inline void show_node(struct zone *zone)
5732 {
5733 	if (IS_ENABLED(CONFIG_NUMA))
5734 		printk("Node %d ", zone_to_nid(zone));
5735 }
5736 
5737 long si_mem_available(void)
5738 {
5739 	long available;
5740 	unsigned long pagecache;
5741 	unsigned long wmark_low = 0;
5742 	unsigned long pages[NR_LRU_LISTS];
5743 	unsigned long reclaimable;
5744 	struct zone *zone;
5745 	int lru;
5746 
5747 	for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
5748 		pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
5749 
5750 	for_each_zone(zone)
5751 		wmark_low += low_wmark_pages(zone);
5752 
5753 	/*
5754 	 * Estimate the amount of memory available for userspace allocations,
5755 	 * without causing swapping.
5756 	 */
5757 	available = global_zone_page_state(NR_FREE_PAGES) - totalreserve_pages;
5758 
5759 	/*
5760 	 * Not all the page cache can be freed, otherwise the system will
5761 	 * start swapping. Assume at least half of the page cache, or the
5762 	 * low watermark worth of cache, needs to stay.
5763 	 */
5764 	pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
5765 	pagecache -= min(pagecache / 2, wmark_low);
5766 	available += pagecache;
5767 
5768 	/*
5769 	 * Part of the reclaimable slab and other kernel memory consists of
5770 	 * items that are in use, and cannot be freed. Cap this estimate at the
5771 	 * low watermark.
5772 	 */
5773 	reclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B) +
5774 		global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE);
5775 	available += reclaimable - min(reclaimable / 2, wmark_low);
5776 
5777 	if (available < 0)
5778 		available = 0;
5779 	return available;
5780 }
5781 EXPORT_SYMBOL_GPL(si_mem_available);
5782 
5783 void si_meminfo(struct sysinfo *val)
5784 {
5785 	val->totalram = totalram_pages();
5786 	val->sharedram = global_node_page_state(NR_SHMEM);
5787 	val->freeram = global_zone_page_state(NR_FREE_PAGES);
5788 	val->bufferram = nr_blockdev_pages();
5789 	val->totalhigh = totalhigh_pages();
5790 	val->freehigh = nr_free_highpages();
5791 	val->mem_unit = PAGE_SIZE;
5792 }
5793 
5794 EXPORT_SYMBOL(si_meminfo);
5795 
5796 #ifdef CONFIG_NUMA
5797 void si_meminfo_node(struct sysinfo *val, int nid)
5798 {
5799 	int zone_type;		/* needs to be signed */
5800 	unsigned long managed_pages = 0;
5801 	unsigned long managed_highpages = 0;
5802 	unsigned long free_highpages = 0;
5803 	pg_data_t *pgdat = NODE_DATA(nid);
5804 
5805 	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
5806 		managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
5807 	val->totalram = managed_pages;
5808 	val->sharedram = node_page_state(pgdat, NR_SHMEM);
5809 	val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
5810 #ifdef CONFIG_HIGHMEM
5811 	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
5812 		struct zone *zone = &pgdat->node_zones[zone_type];
5813 
5814 		if (is_highmem(zone)) {
5815 			managed_highpages += zone_managed_pages(zone);
5816 			free_highpages += zone_page_state(zone, NR_FREE_PAGES);
5817 		}
5818 	}
5819 	val->totalhigh = managed_highpages;
5820 	val->freehigh = free_highpages;
5821 #else
5822 	val->totalhigh = managed_highpages;
5823 	val->freehigh = free_highpages;
5824 #endif
5825 	val->mem_unit = PAGE_SIZE;
5826 }
5827 #endif
5828 
5829 /*
5830  * Determine whether the node should be displayed or not, depending on whether
5831  * SHOW_MEM_FILTER_NODES was passed to show_free_areas().
5832  */
5833 static bool show_mem_node_skip(unsigned int flags, int nid, nodemask_t *nodemask)
5834 {
5835 	if (!(flags & SHOW_MEM_FILTER_NODES))
5836 		return false;
5837 
5838 	/*
5839 	 * no node mask - aka implicit memory numa policy. Do not bother with
5840 	 * the synchronization - read_mems_allowed_begin - because we do not
5841 	 * have to be precise here.
5842 	 */
5843 	if (!nodemask)
5844 		nodemask = &cpuset_current_mems_allowed;
5845 
5846 	return !node_isset(nid, *nodemask);
5847 }
5848 
5849 #define K(x) ((x) << (PAGE_SHIFT-10))
5850 
5851 static void show_migration_types(unsigned char type)
5852 {
5853 	static const char types[MIGRATE_TYPES] = {
5854 		[MIGRATE_UNMOVABLE]	= 'U',
5855 		[MIGRATE_MOVABLE]	= 'M',
5856 		[MIGRATE_RECLAIMABLE]	= 'E',
5857 		[MIGRATE_HIGHATOMIC]	= 'H',
5858 #ifdef CONFIG_CMA
5859 		[MIGRATE_CMA]		= 'C',
5860 #endif
5861 #ifdef CONFIG_MEMORY_ISOLATION
5862 		[MIGRATE_ISOLATE]	= 'I',
5863 #endif
5864 	};
5865 	char tmp[MIGRATE_TYPES + 1];
5866 	char *p = tmp;
5867 	int i;
5868 
5869 	for (i = 0; i < MIGRATE_TYPES; i++) {
5870 		if (type & (1 << i))
5871 			*p++ = types[i];
5872 	}
5873 
5874 	*p = '\0';
5875 	printk(KERN_CONT "(%s) ", tmp);
5876 }
5877 
5878 /*
5879  * Show free area list (used inside shift_scroll-lock stuff)
5880  * We also calculate the percentage fragmentation. We do this by counting the
5881  * memory on each free list with the exception of the first item on the list.
5882  *
5883  * Bits in @filter:
5884  * SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
5885  *   cpuset.
5886  */
5887 void show_free_areas(unsigned int filter, nodemask_t *nodemask)
5888 {
5889 	unsigned long free_pcp = 0;
5890 	int cpu;
5891 	struct zone *zone;
5892 	pg_data_t *pgdat;
5893 
5894 	for_each_populated_zone(zone) {
5895 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
5896 			continue;
5897 
5898 		for_each_online_cpu(cpu)
5899 			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
5900 	}
5901 
5902 	printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
5903 		" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
5904 		" unevictable:%lu dirty:%lu writeback:%lu\n"
5905 		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
5906 		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
5907 		" free:%lu free_pcp:%lu free_cma:%lu\n",
5908 		global_node_page_state(NR_ACTIVE_ANON),
5909 		global_node_page_state(NR_INACTIVE_ANON),
5910 		global_node_page_state(NR_ISOLATED_ANON),
5911 		global_node_page_state(NR_ACTIVE_FILE),
5912 		global_node_page_state(NR_INACTIVE_FILE),
5913 		global_node_page_state(NR_ISOLATED_FILE),
5914 		global_node_page_state(NR_UNEVICTABLE),
5915 		global_node_page_state(NR_FILE_DIRTY),
5916 		global_node_page_state(NR_WRITEBACK),
5917 		global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B),
5918 		global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B),
5919 		global_node_page_state(NR_FILE_MAPPED),
5920 		global_node_page_state(NR_SHMEM),
5921 		global_node_page_state(NR_PAGETABLE),
5922 		global_zone_page_state(NR_BOUNCE),
5923 		global_zone_page_state(NR_FREE_PAGES),
5924 		free_pcp,
5925 		global_zone_page_state(NR_FREE_CMA_PAGES));
5926 
5927 	for_each_online_pgdat(pgdat) {
5928 		if (show_mem_node_skip(filter, pgdat->node_id, nodemask))
5929 			continue;
5930 
5931 		printk("Node %d"
5932 			" active_anon:%lukB"
5933 			" inactive_anon:%lukB"
5934 			" active_file:%lukB"
5935 			" inactive_file:%lukB"
5936 			" unevictable:%lukB"
5937 			" isolated(anon):%lukB"
5938 			" isolated(file):%lukB"
5939 			" mapped:%lukB"
5940 			" dirty:%lukB"
5941 			" writeback:%lukB"
5942 			" shmem:%lukB"
5943 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5944 			" shmem_thp: %lukB"
5945 			" shmem_pmdmapped: %lukB"
5946 			" anon_thp: %lukB"
5947 #endif
5948 			" writeback_tmp:%lukB"
5949 			" kernel_stack:%lukB"
5950 #ifdef CONFIG_SHADOW_CALL_STACK
5951 			" shadow_call_stack:%lukB"
5952 #endif
5953 			" pagetables:%lukB"
5954 			" all_unreclaimable? %s"
5955 			"\n",
5956 			pgdat->node_id,
5957 			K(node_page_state(pgdat, NR_ACTIVE_ANON)),
5958 			K(node_page_state(pgdat, NR_INACTIVE_ANON)),
5959 			K(node_page_state(pgdat, NR_ACTIVE_FILE)),
5960 			K(node_page_state(pgdat, NR_INACTIVE_FILE)),
5961 			K(node_page_state(pgdat, NR_UNEVICTABLE)),
5962 			K(node_page_state(pgdat, NR_ISOLATED_ANON)),
5963 			K(node_page_state(pgdat, NR_ISOLATED_FILE)),
5964 			K(node_page_state(pgdat, NR_FILE_MAPPED)),
5965 			K(node_page_state(pgdat, NR_FILE_DIRTY)),
5966 			K(node_page_state(pgdat, NR_WRITEBACK)),
5967 			K(node_page_state(pgdat, NR_SHMEM)),
5968 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5969 			K(node_page_state(pgdat, NR_SHMEM_THPS)),
5970 			K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)),
5971 			K(node_page_state(pgdat, NR_ANON_THPS)),
5972 #endif
5973 			K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
5974 			node_page_state(pgdat, NR_KERNEL_STACK_KB),
5975 #ifdef CONFIG_SHADOW_CALL_STACK
5976 			node_page_state(pgdat, NR_KERNEL_SCS_KB),
5977 #endif
5978 			K(node_page_state(pgdat, NR_PAGETABLE)),
5979 			pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ?
5980 				"yes" : "no");
5981 	}
5982 
5983 	for_each_populated_zone(zone) {
5984 		int i;
5985 
5986 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
5987 			continue;
5988 
5989 		free_pcp = 0;
5990 		for_each_online_cpu(cpu)
5991 			free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
5992 
5993 		show_node(zone);
5994 		printk(KERN_CONT
5995 			"%s"
5996 			" free:%lukB"
5997 			" min:%lukB"
5998 			" low:%lukB"
5999 			" high:%lukB"
6000 			" reserved_highatomic:%luKB"
6001 			" active_anon:%lukB"
6002 			" inactive_anon:%lukB"
6003 			" active_file:%lukB"
6004 			" inactive_file:%lukB"
6005 			" unevictable:%lukB"
6006 			" writepending:%lukB"
6007 			" present:%lukB"
6008 			" managed:%lukB"
6009 			" mlocked:%lukB"
6010 			" bounce:%lukB"
6011 			" free_pcp:%lukB"
6012 			" local_pcp:%ukB"
6013 			" free_cma:%lukB"
6014 			"\n",
6015 			zone->name,
6016 			K(zone_page_state(zone, NR_FREE_PAGES)),
6017 			K(min_wmark_pages(zone)),
6018 			K(low_wmark_pages(zone)),
6019 			K(high_wmark_pages(zone)),
6020 			K(zone->nr_reserved_highatomic),
6021 			K(zone_page_state(zone, NR_ZONE_ACTIVE_ANON)),
6022 			K(zone_page_state(zone, NR_ZONE_INACTIVE_ANON)),
6023 			K(zone_page_state(zone, NR_ZONE_ACTIVE_FILE)),
6024 			K(zone_page_state(zone, NR_ZONE_INACTIVE_FILE)),
6025 			K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
6026 			K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
6027 			K(zone->present_pages),
6028 			K(zone_managed_pages(zone)),
6029 			K(zone_page_state(zone, NR_MLOCK)),
6030 			K(zone_page_state(zone, NR_BOUNCE)),
6031 			K(free_pcp),
6032 			K(this_cpu_read(zone->per_cpu_pageset->count)),
6033 			K(zone_page_state(zone, NR_FREE_CMA_PAGES)));
6034 		printk("lowmem_reserve[]:");
6035 		for (i = 0; i < MAX_NR_ZONES; i++)
6036 			printk(KERN_CONT " %ld", zone->lowmem_reserve[i]);
6037 		printk(KERN_CONT "\n");
6038 	}
6039 
6040 	for_each_populated_zone(zone) {
6041 		unsigned int order;
6042 		unsigned long nr[MAX_ORDER], flags, total = 0;
6043 		unsigned char types[MAX_ORDER];
6044 
6045 		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
6046 			continue;
6047 		show_node(zone);
6048 		printk(KERN_CONT "%s: ", zone->name);
6049 
6050 		spin_lock_irqsave(&zone->lock, flags);
6051 		for (order = 0; order < MAX_ORDER; order++) {
6052 			struct free_area *area = &zone->free_area[order];
6053 			int type;
6054 
6055 			nr[order] = area->nr_free;
6056 			total += nr[order] << order;
6057 
6058 			types[order] = 0;
6059 			for (type = 0; type < MIGRATE_TYPES; type++) {
6060 				if (!free_area_empty(area, type))
6061 					types[order] |= 1 << type;
6062 			}
6063 		}
6064 		spin_unlock_irqrestore(&zone->lock, flags);
6065 		for (order = 0; order < MAX_ORDER; order++) {
6066 			printk(KERN_CONT "%lu*%lukB ",
6067 			       nr[order], K(1UL) << order);
6068 			if (nr[order])
6069 				show_migration_types(types[order]);
6070 		}
6071 		printk(KERN_CONT "= %lukB\n", K(total));
6072 	}
6073 
6074 	hugetlb_show_meminfo();
6075 
6076 	printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));
6077 
6078 	show_swap_cache_info();
6079 }
6080 
6081 static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
6082 {
6083 	zoneref->zone = zone;
6084 	zoneref->zone_idx = zone_idx(zone);
6085 }
6086 
6087 /*
6088  * Builds allocation fallback zone lists.
6089  *
6090  * Add all populated zones of a node to the zonelist.
6091  */
6092 static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
6093 {
6094 	struct zone *zone;
6095 	enum zone_type zone_type = MAX_NR_ZONES;
6096 	int nr_zones = 0;
6097 
6098 	do {
6099 		zone_type--;
6100 		zone = pgdat->node_zones + zone_type;
6101 		if (managed_zone(zone)) {
6102 			zoneref_set_zone(zone, &zonerefs[nr_zones++]);
6103 			check_highest_zone(zone_type);
6104 		}
6105 	} while (zone_type);
6106 
6107 	return nr_zones;
6108 }
6109 
6110 #ifdef CONFIG_NUMA
6111 
6112 static int __parse_numa_zonelist_order(char *s)
6113 {
6114 	/*
6115 	 * We used to support different zonelists modes but they turned
6116 	 * out to be just not useful. Let's keep the warning in place
6117 	 * if somebody still use the cmd line parameter so that we do
6118 	 * not fail it silently
6119 	 */
6120 	if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
6121 		pr_warn("Ignoring unsupported numa_zonelist_order value:  %s\n", s);
6122 		return -EINVAL;
6123 	}
6124 	return 0;
6125 }
6126 
6127 char numa_zonelist_order[] = "Node";
6128 
6129 /*
6130  * sysctl handler for numa_zonelist_order
6131  */
6132 int numa_zonelist_order_handler(struct ctl_table *table, int write,
6133 		void *buffer, size_t *length, loff_t *ppos)
6134 {
6135 	if (write)
6136 		return __parse_numa_zonelist_order(buffer);
6137 	return proc_dostring(table, write, buffer, length, ppos);
6138 }
6139 
6140 
6141 #define MAX_NODE_LOAD (nr_online_nodes)
6142 static int node_load[MAX_NUMNODES];
6143 
6144 /**
6145  * find_next_best_node - find the next node that should appear in a given node's fallback list
6146  * @node: node whose fallback list we're appending
6147  * @used_node_mask: nodemask_t of already used nodes
6148  *
6149  * We use a number of factors to determine which is the next node that should
6150  * appear on a given node's fallback list.  The node should not have appeared
6151  * already in @node's fallback list, and it should be the next closest node
6152  * according to the distance array (which contains arbitrary distance values
6153  * from each node to each node in the system), and should also prefer nodes
6154  * with no CPUs, since presumably they'll have very little allocation pressure
6155  * on them otherwise.
6156  *
6157  * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
6158  */
6159 static int find_next_best_node(int node, nodemask_t *used_node_mask)
6160 {
6161 	int n, val;
6162 	int min_val = INT_MAX;
6163 	int best_node = NUMA_NO_NODE;
6164 
6165 	/* Use the local node if we haven't already */
6166 	if (!node_isset(node, *used_node_mask)) {
6167 		node_set(node, *used_node_mask);
6168 		return node;
6169 	}
6170 
6171 	for_each_node_state(n, N_MEMORY) {
6172 
6173 		/* Don't want a node to appear more than once */
6174 		if (node_isset(n, *used_node_mask))
6175 			continue;
6176 
6177 		/* Use the distance array to find the distance */
6178 		val = node_distance(node, n);
6179 
6180 		/* Penalize nodes under us ("prefer the next node") */
6181 		val += (n < node);
6182 
6183 		/* Give preference to headless and unused nodes */
6184 		if (!cpumask_empty(cpumask_of_node(n)))
6185 			val += PENALTY_FOR_NODE_WITH_CPUS;
6186 
6187 		/* Slight preference for less loaded node */
6188 		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
6189 		val += node_load[n];
6190 
6191 		if (val < min_val) {
6192 			min_val = val;
6193 			best_node = n;
6194 		}
6195 	}
6196 
6197 	if (best_node >= 0)
6198 		node_set(best_node, *used_node_mask);
6199 
6200 	return best_node;
6201 }
6202 
6203 
6204 /*
6205  * Build zonelists ordered by node and zones within node.
6206  * This results in maximum locality--normal zone overflows into local
6207  * DMA zone, if any--but risks exhausting DMA zone.
6208  */
6209 static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
6210 		unsigned nr_nodes)
6211 {
6212 	struct zoneref *zonerefs;
6213 	int i;
6214 
6215 	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
6216 
6217 	for (i = 0; i < nr_nodes; i++) {
6218 		int nr_zones;
6219 
6220 		pg_data_t *node = NODE_DATA(node_order[i]);
6221 
6222 		nr_zones = build_zonerefs_node(node, zonerefs);
6223 		zonerefs += nr_zones;
6224 	}
6225 	zonerefs->zone = NULL;
6226 	zonerefs->zone_idx = 0;
6227 }
6228 
6229 /*
6230  * Build gfp_thisnode zonelists
6231  */
6232 static void build_thisnode_zonelists(pg_data_t *pgdat)
6233 {
6234 	struct zoneref *zonerefs;
6235 	int nr_zones;
6236 
6237 	zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
6238 	nr_zones = build_zonerefs_node(pgdat, zonerefs);
6239 	zonerefs += nr_zones;
6240 	zonerefs->zone = NULL;
6241 	zonerefs->zone_idx = 0;
6242 }
6243 
6244 /*
6245  * Build zonelists ordered by zone and nodes within zones.
6246  * This results in conserving DMA zone[s] until all Normal memory is
6247  * exhausted, but results in overflowing to remote node while memory
6248  * may still exist in local DMA zone.
6249  */
6250 
6251 static void build_zonelists(pg_data_t *pgdat)
6252 {
6253 	static int node_order[MAX_NUMNODES];
6254 	int node, load, nr_nodes = 0;
6255 	nodemask_t used_mask = NODE_MASK_NONE;
6256 	int local_node, prev_node;
6257 
6258 	/* NUMA-aware ordering of nodes */
6259 	local_node = pgdat->node_id;
6260 	load = nr_online_nodes;
6261 	prev_node = local_node;
6262 
6263 	memset(node_order, 0, sizeof(node_order));
6264 	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
6265 		/*
6266 		 * We don't want to pressure a particular node.
6267 		 * So adding penalty to the first node in same
6268 		 * distance group to make it round-robin.
6269 		 */
6270 		if (node_distance(local_node, node) !=
6271 		    node_distance(local_node, prev_node))
6272 			node_load[node] = load;
6273 
6274 		node_order[nr_nodes++] = node;
6275 		prev_node = node;
6276 		load--;
6277 	}
6278 
6279 	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
6280 	build_thisnode_zonelists(pgdat);
6281 }
6282 
6283 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
6284 /*
6285  * Return node id of node used for "local" allocations.
6286  * I.e., first node id of first zone in arg node's generic zonelist.
6287  * Used for initializing percpu 'numa_mem', which is used primarily
6288  * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
6289  */
6290 int local_memory_node(int node)
6291 {
6292 	struct zoneref *z;
6293 
6294 	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
6295 				   gfp_zone(GFP_KERNEL),
6296 				   NULL);
6297 	return zone_to_nid(z->zone);
6298 }
6299 #endif
6300 
6301 static void setup_min_unmapped_ratio(void);
6302 static void setup_min_slab_ratio(void);
6303 #else	/* CONFIG_NUMA */
6304 
6305 static void build_zonelists(pg_data_t *pgdat)
6306 {
6307 	int node, local_node;
6308 	struct zoneref *zonerefs;
6309 	int nr_zones;
6310 
6311 	local_node = pgdat->node_id;
6312 
6313 	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
6314 	nr_zones = build_zonerefs_node(pgdat, zonerefs);
6315 	zonerefs += nr_zones;
6316 
6317 	/*
6318 	 * Now we build the zonelist so that it contains the zones
6319 	 * of all the other nodes.
6320 	 * We don't want to pressure a particular node, so when
6321 	 * building the zones for node N, we make sure that the
6322 	 * zones coming right after the local ones are those from
6323 	 * node N+1 (modulo N)
6324 	 */
6325 	for (node = local_node + 1; node < MAX_NUMNODES; node++) {
6326 		if (!node_online(node))
6327 			continue;
6328 		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
6329 		zonerefs += nr_zones;
6330 	}
6331 	for (node = 0; node < local_node; node++) {
6332 		if (!node_online(node))
6333 			continue;
6334 		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
6335 		zonerefs += nr_zones;
6336 	}
6337 
6338 	zonerefs->zone = NULL;
6339 	zonerefs->zone_idx = 0;
6340 }
6341 
6342 #endif	/* CONFIG_NUMA */
6343 
6344 /*
6345  * Boot pageset table. One per cpu which is going to be used for all
6346  * zones and all nodes. The parameters will be set in such a way
6347  * that an item put on a list will immediately be handed over to
6348  * the buddy list. This is safe since pageset manipulation is done
6349  * with interrupts disabled.
6350  *
6351  * The boot_pagesets must be kept even after bootup is complete for
6352  * unused processors and/or zones. They do play a role for bootstrapping
6353  * hotplugged processors.
6354  *
6355  * zoneinfo_show() and maybe other functions do
6356  * not check if the processor is online before following the pageset pointer.
6357  * Other parts of the kernel may not check if the zone is available.
6358  */
6359 static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats);
6360 /* These effectively disable the pcplists in the boot pageset completely */
6361 #define BOOT_PAGESET_HIGH	0
6362 #define BOOT_PAGESET_BATCH	1
6363 static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
6364 static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
6365 static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
6366 
6367 static void __build_all_zonelists(void *data)
6368 {
6369 	int nid;
6370 	int __maybe_unused cpu;
6371 	pg_data_t *self = data;
6372 	static DEFINE_SPINLOCK(lock);
6373 
6374 	spin_lock(&lock);
6375 
6376 #ifdef CONFIG_NUMA
6377 	memset(node_load, 0, sizeof(node_load));
6378 #endif
6379 
6380 	/*
6381 	 * This node is hotadded and no memory is yet present.   So just
6382 	 * building zonelists is fine - no need to touch other nodes.
6383 	 */
6384 	if (self && !node_online(self->node_id)) {
6385 		build_zonelists(self);
6386 	} else {
6387 		for_each_online_node(nid) {
6388 			pg_data_t *pgdat = NODE_DATA(nid);
6389 
6390 			build_zonelists(pgdat);
6391 		}
6392 
6393 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
6394 		/*
6395 		 * We now know the "local memory node" for each node--
6396 		 * i.e., the node of the first zone in the generic zonelist.
6397 		 * Set up numa_mem percpu variable for on-line cpus.  During
6398 		 * boot, only the boot cpu should be on-line;  we'll init the
6399 		 * secondary cpus' numa_mem as they come on-line.  During
6400 		 * node/memory hotplug, we'll fixup all on-line cpus.
6401 		 */
6402 		for_each_online_cpu(cpu)
6403 			set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
6404 #endif
6405 	}
6406 
6407 	spin_unlock(&lock);
6408 }
6409 
6410 static noinline void __init
6411 build_all_zonelists_init(void)
6412 {
6413 	int cpu;
6414 
6415 	__build_all_zonelists(NULL);
6416 
6417 	/*
6418 	 * Initialize the boot_pagesets that are going to be used
6419 	 * for bootstrapping processors. The real pagesets for
6420 	 * each zone will be allocated later when the per cpu
6421 	 * allocator is available.
6422 	 *
6423 	 * boot_pagesets are used also for bootstrapping offline
6424 	 * cpus if the system is already booted because the pagesets
6425 	 * are needed to initialize allocators on a specific cpu too.
6426 	 * F.e. the percpu allocator needs the page allocator which
6427 	 * needs the percpu allocator in order to allocate its pagesets
6428 	 * (a chicken-egg dilemma).
6429 	 */
6430 	for_each_possible_cpu(cpu)
6431 		per_cpu_pages_init(&per_cpu(boot_pageset, cpu), &per_cpu(boot_zonestats, cpu));
6432 
6433 	mminit_verify_zonelist();
6434 	cpuset_init_current_mems_allowed();
6435 }
6436 
6437 /*
6438  * unless system_state == SYSTEM_BOOTING.
6439  *
6440  * __ref due to call of __init annotated helper build_all_zonelists_init
6441  * [protected by SYSTEM_BOOTING].
6442  */
6443 void __ref build_all_zonelists(pg_data_t *pgdat)
6444 {
6445 	unsigned long vm_total_pages;
6446 
6447 	if (system_state == SYSTEM_BOOTING) {
6448 		build_all_zonelists_init();
6449 	} else {
6450 		__build_all_zonelists(pgdat);
6451 		/* cpuset refresh routine should be here */
6452 	}
6453 	/* Get the number of free pages beyond high watermark in all zones. */
6454 	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
6455 	/*
6456 	 * Disable grouping by mobility if the number of pages in the
6457 	 * system is too low to allow the mechanism to work. It would be
6458 	 * more accurate, but expensive to check per-zone. This check is
6459 	 * made on memory-hotadd so a system can start with mobility
6460 	 * disabled and enable it later
6461 	 */
6462 	if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
6463 		page_group_by_mobility_disabled = 1;
6464 	else
6465 		page_group_by_mobility_disabled = 0;
6466 
6467 	pr_info("Built %u zonelists, mobility grouping %s.  Total pages: %ld\n",
6468 		nr_online_nodes,
6469 		page_group_by_mobility_disabled ? "off" : "on",
6470 		vm_total_pages);
6471 #ifdef CONFIG_NUMA
6472 	pr_info("Policy zone: %s\n", zone_names[policy_zone]);
6473 #endif
6474 }
6475 
6476 /* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
6477 static bool __meminit
6478 overlap_memmap_init(unsigned long zone, unsigned long *pfn)
6479 {
6480 	static struct memblock_region *r;
6481 
6482 	if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
6483 		if (!r || *pfn >= memblock_region_memory_end_pfn(r)) {
6484 			for_each_mem_region(r) {
6485 				if (*pfn < memblock_region_memory_end_pfn(r))
6486 					break;
6487 			}
6488 		}
6489 		if (*pfn >= memblock_region_memory_base_pfn(r) &&
6490 		    memblock_is_mirror(r)) {
6491 			*pfn = memblock_region_memory_end_pfn(r);
6492 			return true;
6493 		}
6494 	}
6495 	return false;
6496 }
6497 
6498 /*
6499  * Initially all pages are reserved - free ones are freed
6500  * up by memblock_free_all() once the early boot process is
6501  * done. Non-atomic initialization, single-pass.
6502  *
6503  * All aligned pageblocks are initialized to the specified migratetype
6504  * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
6505  * zone stats (e.g., nr_isolate_pageblock) are touched.
6506  */
6507 void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone,
6508 		unsigned long start_pfn, unsigned long zone_end_pfn,
6509 		enum meminit_context context,
6510 		struct vmem_altmap *altmap, int migratetype)
6511 {
6512 	unsigned long pfn, end_pfn = start_pfn + size;
6513 	struct page *page;
6514 
6515 	if (highest_memmap_pfn < end_pfn - 1)
6516 		highest_memmap_pfn = end_pfn - 1;
6517 
6518 #ifdef CONFIG_ZONE_DEVICE
6519 	/*
6520 	 * Honor reservation requested by the driver for this ZONE_DEVICE
6521 	 * memory. We limit the total number of pages to initialize to just
6522 	 * those that might contain the memory mapping. We will defer the
6523 	 * ZONE_DEVICE page initialization until after we have released
6524 	 * the hotplug lock.
6525 	 */
6526 	if (zone == ZONE_DEVICE) {
6527 		if (!altmap)
6528 			return;
6529 
6530 		if (start_pfn == altmap->base_pfn)
6531 			start_pfn += altmap->reserve;
6532 		end_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
6533 	}
6534 #endif
6535 
6536 	for (pfn = start_pfn; pfn < end_pfn; ) {
6537 		/*
6538 		 * There can be holes in boot-time mem_map[]s handed to this
6539 		 * function.  They do not exist on hotplugged memory.
6540 		 */
6541 		if (context == MEMINIT_EARLY) {
6542 			if (overlap_memmap_init(zone, &pfn))
6543 				continue;
6544 			if (defer_init(nid, pfn, zone_end_pfn))
6545 				break;
6546 		}
6547 
6548 		page = pfn_to_page(pfn);
6549 		__init_single_page(page, pfn, zone, nid);
6550 		if (context == MEMINIT_HOTPLUG)
6551 			__SetPageReserved(page);
6552 
6553 		/*
6554 		 * Usually, we want to mark the pageblock MIGRATE_MOVABLE,
6555 		 * such that unmovable allocations won't be scattered all
6556 		 * over the place during system boot.
6557 		 */
6558 		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
6559 			set_pageblock_migratetype(page, migratetype);
6560 			cond_resched();
6561 		}
6562 		pfn++;
6563 	}
6564 }
6565 
6566 #ifdef CONFIG_ZONE_DEVICE
6567 void __ref memmap_init_zone_device(struct zone *zone,
6568 				   unsigned long start_pfn,
6569 				   unsigned long nr_pages,
6570 				   struct dev_pagemap *pgmap)
6571 {
6572 	unsigned long pfn, end_pfn = start_pfn + nr_pages;
6573 	struct pglist_data *pgdat = zone->zone_pgdat;
6574 	struct vmem_altmap *altmap = pgmap_altmap(pgmap);
6575 	unsigned long zone_idx = zone_idx(zone);
6576 	unsigned long start = jiffies;
6577 	int nid = pgdat->node_id;
6578 
6579 	if (WARN_ON_ONCE(!pgmap || zone_idx(zone) != ZONE_DEVICE))
6580 		return;
6581 
6582 	/*
6583 	 * The call to memmap_init should have already taken care
6584 	 * of the pages reserved for the memmap, so we can just jump to
6585 	 * the end of that region and start processing the device pages.
6586 	 */
6587 	if (altmap) {
6588 		start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
6589 		nr_pages = end_pfn - start_pfn;
6590 	}
6591 
6592 	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
6593 		struct page *page = pfn_to_page(pfn);
6594 
6595 		__init_single_page(page, pfn, zone_idx, nid);
6596 
6597 		/*
6598 		 * Mark page reserved as it will need to wait for onlining
6599 		 * phase for it to be fully associated with a zone.
6600 		 *
6601 		 * We can use the non-atomic __set_bit operation for setting
6602 		 * the flag as we are still initializing the pages.
6603 		 */
6604 		__SetPageReserved(page);
6605 
6606 		/*
6607 		 * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
6608 		 * and zone_device_data.  It is a bug if a ZONE_DEVICE page is
6609 		 * ever freed or placed on a driver-private list.
6610 		 */
6611 		page->pgmap = pgmap;
6612 		page->zone_device_data = NULL;
6613 
6614 		/*
6615 		 * Mark the block movable so that blocks are reserved for
6616 		 * movable at startup. This will force kernel allocations
6617 		 * to reserve their blocks rather than leaking throughout
6618 		 * the address space during boot when many long-lived
6619 		 * kernel allocations are made.
6620 		 *
6621 		 * Please note that MEMINIT_HOTPLUG path doesn't clear memmap
6622 		 * because this is done early in section_activate()
6623 		 */
6624 		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
6625 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
6626 			cond_resched();
6627 		}
6628 	}
6629 
6630 	pr_info("%s initialised %lu pages in %ums\n", __func__,
6631 		nr_pages, jiffies_to_msecs(jiffies - start));
6632 }
6633 
6634 #endif
6635 static void __meminit zone_init_free_lists(struct zone *zone)
6636 {
6637 	unsigned int order, t;
6638 	for_each_migratetype_order(order, t) {
6639 		INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
6640 		zone->free_area[order].nr_free = 0;
6641 	}
6642 }
6643 
6644 #if !defined(CONFIG_FLATMEM)
6645 /*
6646  * Only struct pages that correspond to ranges defined by memblock.memory
6647  * are zeroed and initialized by going through __init_single_page() during
6648  * memmap_init_zone_range().
6649  *
6650  * But, there could be struct pages that correspond to holes in
6651  * memblock.memory. This can happen because of the following reasons:
6652  * - physical memory bank size is not necessarily the exact multiple of the
6653  *   arbitrary section size
6654  * - early reserved memory may not be listed in memblock.memory
6655  * - memory layouts defined with memmap= kernel parameter may not align
6656  *   nicely with memmap sections
6657  *
6658  * Explicitly initialize those struct pages so that:
6659  * - PG_Reserved is set
6660  * - zone and node links point to zone and node that span the page if the
6661  *   hole is in the middle of a zone
6662  * - zone and node links point to adjacent zone/node if the hole falls on
6663  *   the zone boundary; the pages in such holes will be prepended to the
6664  *   zone/node above the hole except for the trailing pages in the last
6665  *   section that will be appended to the zone/node below.
6666  */
6667 static void __init init_unavailable_range(unsigned long spfn,
6668 					  unsigned long epfn,
6669 					  int zone, int node)
6670 {
6671 	unsigned long pfn;
6672 	u64 pgcnt = 0;
6673 
6674 	for (pfn = spfn; pfn < epfn; pfn++) {
6675 		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
6676 			pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
6677 				+ pageblock_nr_pages - 1;
6678 			continue;
6679 		}
6680 		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
6681 		__SetPageReserved(pfn_to_page(pfn));
6682 		pgcnt++;
6683 	}
6684 
6685 	if (pgcnt)
6686 		pr_info("On node %d, zone %s: %lld pages in unavailable ranges",
6687 			node, zone_names[zone], pgcnt);
6688 }
6689 #else
6690 static inline void init_unavailable_range(unsigned long spfn,
6691 					  unsigned long epfn,
6692 					  int zone, int node)
6693 {
6694 }
6695 #endif
6696 
6697 static void __init memmap_init_zone_range(struct zone *zone,
6698 					  unsigned long start_pfn,
6699 					  unsigned long end_pfn,
6700 					  unsigned long *hole_pfn)
6701 {
6702 	unsigned long zone_start_pfn = zone->zone_start_pfn;
6703 	unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages;
6704 	int nid = zone_to_nid(zone), zone_id = zone_idx(zone);
6705 
6706 	start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn);
6707 	end_pfn = clamp(end_pfn, zone_start_pfn, zone_end_pfn);
6708 
6709 	if (start_pfn >= end_pfn)
6710 		return;
6711 
6712 	memmap_init_range(end_pfn - start_pfn, nid, zone_id, start_pfn,
6713 			  zone_end_pfn, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE);
6714 
6715 	if (*hole_pfn < start_pfn)
6716 		init_unavailable_range(*hole_pfn, start_pfn, zone_id, nid);
6717 
6718 	*hole_pfn = end_pfn;
6719 }
6720 
6721 static void __init memmap_init(void)
6722 {
6723 	unsigned long start_pfn, end_pfn;
6724 	unsigned long hole_pfn = 0;
6725 	int i, j, zone_id, nid;
6726 
6727 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
6728 		struct pglist_data *node = NODE_DATA(nid);
6729 
6730 		for (j = 0; j < MAX_NR_ZONES; j++) {
6731 			struct zone *zone = node->node_zones + j;
6732 
6733 			if (!populated_zone(zone))
6734 				continue;
6735 
6736 			memmap_init_zone_range(zone, start_pfn, end_pfn,
6737 					       &hole_pfn);
6738 			zone_id = j;
6739 		}
6740 	}
6741 
6742 #ifdef CONFIG_SPARSEMEM
6743 	/*
6744 	 * Initialize the memory map for hole in the range [memory_end,
6745 	 * section_end].
6746 	 * Append the pages in this hole to the highest zone in the last
6747 	 * node.
6748 	 * The call to init_unavailable_range() is outside the ifdef to
6749 	 * silence the compiler warining about zone_id set but not used;
6750 	 * for FLATMEM it is a nop anyway
6751 	 */
6752 	end_pfn = round_up(end_pfn, PAGES_PER_SECTION);
6753 	if (hole_pfn < end_pfn)
6754 #endif
6755 		init_unavailable_range(hole_pfn, end_pfn, zone_id, nid);
6756 }
6757 
6758 static int zone_batchsize(struct zone *zone)
6759 {
6760 #ifdef CONFIG_MMU
6761 	int batch;
6762 
6763 	/*
6764 	 * The number of pages to batch allocate is either ~0.1%
6765 	 * of the zone or 1MB, whichever is smaller. The batch
6766 	 * size is striking a balance between allocation latency
6767 	 * and zone lock contention.
6768 	 */
6769 	batch = min(zone_managed_pages(zone) >> 10, (1024 * 1024) / PAGE_SIZE);
6770 	batch /= 4;		/* We effectively *= 4 below */
6771 	if (batch < 1)
6772 		batch = 1;
6773 
6774 	/*
6775 	 * Clamp the batch to a 2^n - 1 value. Having a power
6776 	 * of 2 value was found to be more likely to have
6777 	 * suboptimal cache aliasing properties in some cases.
6778 	 *
6779 	 * For example if 2 tasks are alternately allocating
6780 	 * batches of pages, one task can end up with a lot
6781 	 * of pages of one half of the possible page colors
6782 	 * and the other with pages of the other colors.
6783 	 */
6784 	batch = rounddown_pow_of_two(batch + batch/2) - 1;
6785 
6786 	return batch;
6787 
6788 #else
6789 	/* The deferral and batching of frees should be suppressed under NOMMU
6790 	 * conditions.
6791 	 *
6792 	 * The problem is that NOMMU needs to be able to allocate large chunks
6793 	 * of contiguous memory as there's no hardware page translation to
6794 	 * assemble apparent contiguous memory from discontiguous pages.
6795 	 *
6796 	 * Queueing large contiguous runs of pages for batching, however,
6797 	 * causes the pages to actually be freed in smaller chunks.  As there
6798 	 * can be a significant delay between the individual batches being
6799 	 * recycled, this leads to the once large chunks of space being
6800 	 * fragmented and becoming unavailable for high-order allocations.
6801 	 */
6802 	return 0;
6803 #endif
6804 }
6805 
6806 static int zone_highsize(struct zone *zone, int batch, int cpu_online)
6807 {
6808 #ifdef CONFIG_MMU
6809 	int high;
6810 	int nr_split_cpus;
6811 	unsigned long total_pages;
6812 
6813 	if (!percpu_pagelist_high_fraction) {
6814 		/*
6815 		 * By default, the high value of the pcp is based on the zone
6816 		 * low watermark so that if they are full then background
6817 		 * reclaim will not be started prematurely.
6818 		 */
6819 		total_pages = low_wmark_pages(zone);
6820 	} else {
6821 		/*
6822 		 * If percpu_pagelist_high_fraction is configured, the high
6823 		 * value is based on a fraction of the managed pages in the
6824 		 * zone.
6825 		 */
6826 		total_pages = zone_managed_pages(zone) / percpu_pagelist_high_fraction;
6827 	}
6828 
6829 	/*
6830 	 * Split the high value across all online CPUs local to the zone. Note
6831 	 * that early in boot that CPUs may not be online yet and that during
6832 	 * CPU hotplug that the cpumask is not yet updated when a CPU is being
6833 	 * onlined. For memory nodes that have no CPUs, split pcp->high across
6834 	 * all online CPUs to mitigate the risk that reclaim is triggered
6835 	 * prematurely due to pages stored on pcp lists.
6836 	 */
6837 	nr_split_cpus = cpumask_weight(cpumask_of_node(zone_to_nid(zone))) + cpu_online;
6838 	if (!nr_split_cpus)
6839 		nr_split_cpus = num_online_cpus();
6840 	high = total_pages / nr_split_cpus;
6841 
6842 	/*
6843 	 * Ensure high is at least batch*4. The multiple is based on the
6844 	 * historical relationship between high and batch.
6845 	 */
6846 	high = max(high, batch << 2);
6847 
6848 	return high;
6849 #else
6850 	return 0;
6851 #endif
6852 }
6853 
6854 /*
6855  * pcp->high and pcp->batch values are related and generally batch is lower
6856  * than high. They are also related to pcp->count such that count is lower
6857  * than high, and as soon as it reaches high, the pcplist is flushed.
6858  *
6859  * However, guaranteeing these relations at all times would require e.g. write
6860  * barriers here but also careful usage of read barriers at the read side, and
6861  * thus be prone to error and bad for performance. Thus the update only prevents
6862  * store tearing. Any new users of pcp->batch and pcp->high should ensure they
6863  * can cope with those fields changing asynchronously, and fully trust only the
6864  * pcp->count field on the local CPU with interrupts disabled.
6865  *
6866  * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
6867  * outside of boot time (or some other assurance that no concurrent updaters
6868  * exist).
6869  */
6870 static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
6871 		unsigned long batch)
6872 {
6873 	WRITE_ONCE(pcp->batch, batch);
6874 	WRITE_ONCE(pcp->high, high);
6875 }
6876 
6877 static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonestat *pzstats)
6878 {
6879 	int pindex;
6880 
6881 	memset(pcp, 0, sizeof(*pcp));
6882 	memset(pzstats, 0, sizeof(*pzstats));
6883 
6884 	for (pindex = 0; pindex < NR_PCP_LISTS; pindex++)
6885 		INIT_LIST_HEAD(&pcp->lists[pindex]);
6886 
6887 	/*
6888 	 * Set batch and high values safe for a boot pageset. A true percpu
6889 	 * pageset's initialization will update them subsequently. Here we don't
6890 	 * need to be as careful as pageset_update() as nobody can access the
6891 	 * pageset yet.
6892 	 */
6893 	pcp->high = BOOT_PAGESET_HIGH;
6894 	pcp->batch = BOOT_PAGESET_BATCH;
6895 	pcp->free_factor = 0;
6896 }
6897 
6898 static void __zone_set_pageset_high_and_batch(struct zone *zone, unsigned long high,
6899 		unsigned long batch)
6900 {
6901 	struct per_cpu_pages *pcp;
6902 	int cpu;
6903 
6904 	for_each_possible_cpu(cpu) {
6905 		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
6906 		pageset_update(pcp, high, batch);
6907 	}
6908 }
6909 
6910 /*
6911  * Calculate and set new high and batch values for all per-cpu pagesets of a
6912  * zone based on the zone's size.
6913  */
6914 static void zone_set_pageset_high_and_batch(struct zone *zone, int cpu_online)
6915 {
6916 	int new_high, new_batch;
6917 
6918 	new_batch = max(1, zone_batchsize(zone));
6919 	new_high = zone_highsize(zone, new_batch, cpu_online);
6920 
6921 	if (zone->pageset_high == new_high &&
6922 	    zone->pageset_batch == new_batch)
6923 		return;
6924 
6925 	zone->pageset_high = new_high;
6926 	zone->pageset_batch = new_batch;
6927 
6928 	__zone_set_pageset_high_and_batch(zone, new_high, new_batch);
6929 }
6930 
6931 void __meminit setup_zone_pageset(struct zone *zone)
6932 {
6933 	int cpu;
6934 
6935 	/* Size may be 0 on !SMP && !NUMA */
6936 	if (sizeof(struct per_cpu_zonestat) > 0)
6937 		zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat);
6938 
6939 	zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages);
6940 	for_each_possible_cpu(cpu) {
6941 		struct per_cpu_pages *pcp;
6942 		struct per_cpu_zonestat *pzstats;
6943 
6944 		pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
6945 		pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
6946 		per_cpu_pages_init(pcp, pzstats);
6947 	}
6948 
6949 	zone_set_pageset_high_and_batch(zone, 0);
6950 }
6951 
6952 /*
6953  * Allocate per cpu pagesets and initialize them.
6954  * Before this call only boot pagesets were available.
6955  */
6956 void __init setup_per_cpu_pageset(void)
6957 {
6958 	struct pglist_data *pgdat;
6959 	struct zone *zone;
6960 	int __maybe_unused cpu;
6961 
6962 	for_each_populated_zone(zone)
6963 		setup_zone_pageset(zone);
6964 
6965 #ifdef CONFIG_NUMA
6966 	/*
6967 	 * Unpopulated zones continue using the boot pagesets.
6968 	 * The numa stats for these pagesets need to be reset.
6969 	 * Otherwise, they will end up skewing the stats of
6970 	 * the nodes these zones are associated with.
6971 	 */
6972 	for_each_possible_cpu(cpu) {
6973 		struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
6974 		memset(pzstats->vm_numa_event, 0,
6975 		       sizeof(pzstats->vm_numa_event));
6976 	}
6977 #endif
6978 
6979 	for_each_online_pgdat(pgdat)
6980 		pgdat->per_cpu_nodestats =
6981 			alloc_percpu(struct per_cpu_nodestat);
6982 }
6983 
6984 static __meminit void zone_pcp_init(struct zone *zone)
6985 {
6986 	/*
6987 	 * per cpu subsystem is not up at this point. The following code
6988 	 * relies on the ability of the linker to provide the
6989 	 * offset of a (static) per cpu variable into the per cpu area.
6990 	 */
6991 	zone->per_cpu_pageset = &boot_pageset;
6992 	zone->per_cpu_zonestats = &boot_zonestats;
6993 	zone->pageset_high = BOOT_PAGESET_HIGH;
6994 	zone->pageset_batch = BOOT_PAGESET_BATCH;
6995 
6996 	if (populated_zone(zone))
6997 		pr_debug("  %s zone: %lu pages, LIFO batch:%u\n", zone->name,
6998 			 zone->present_pages, zone_batchsize(zone));
6999 }
7000 
7001 void __meminit init_currently_empty_zone(struct zone *zone,
7002 					unsigned long zone_start_pfn,
7003 					unsigned long size)
7004 {
7005 	struct pglist_data *pgdat = zone->zone_pgdat;
7006 	int zone_idx = zone_idx(zone) + 1;
7007 
7008 	if (zone_idx > pgdat->nr_zones)
7009 		pgdat->nr_zones = zone_idx;
7010 
7011 	zone->zone_start_pfn = zone_start_pfn;
7012 
7013 	mminit_dprintk(MMINIT_TRACE, "memmap_init",
7014 			"Initialising map node %d zone %lu pfns %lu -> %lu\n",
7015 			pgdat->node_id,
7016 			(unsigned long)zone_idx(zone),
7017 			zone_start_pfn, (zone_start_pfn + size));
7018 
7019 	zone_init_free_lists(zone);
7020 	zone->initialized = 1;
7021 }
7022 
7023 /**
7024  * get_pfn_range_for_nid - Return the start and end page frames for a node
7025  * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
7026  * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
7027  * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
7028  *
7029  * It returns the start and end page frame of a node based on information
7030  * provided by memblock_set_node(). If called for a node
7031  * with no available memory, a warning is printed and the start and end
7032  * PFNs will be 0.
7033  */
7034 void __init get_pfn_range_for_nid(unsigned int nid,
7035 			unsigned long *start_pfn, unsigned long *end_pfn)
7036 {
7037 	unsigned long this_start_pfn, this_end_pfn;
7038 	int i;
7039 
7040 	*start_pfn = -1UL;
7041 	*end_pfn = 0;
7042 
7043 	for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
7044 		*start_pfn = min(*start_pfn, this_start_pfn);
7045 		*end_pfn = max(*end_pfn, this_end_pfn);
7046 	}
7047 
7048 	if (*start_pfn == -1UL)
7049 		*start_pfn = 0;
7050 }
7051 
7052 /*
7053  * This finds a zone that can be used for ZONE_MOVABLE pages. The
7054  * assumption is made that zones within a node are ordered in monotonic
7055  * increasing memory addresses so that the "highest" populated zone is used
7056  */
7057 static void __init find_usable_zone_for_movable(void)
7058 {
7059 	int zone_index;
7060 	for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
7061 		if (zone_index == ZONE_MOVABLE)
7062 			continue;
7063 
7064 		if (arch_zone_highest_possible_pfn[zone_index] >
7065 				arch_zone_lowest_possible_pfn[zone_index])
7066 			break;
7067 	}
7068 
7069 	VM_BUG_ON(zone_index == -1);
7070 	movable_zone = zone_index;
7071 }
7072 
7073 /*
7074  * The zone ranges provided by the architecture do not include ZONE_MOVABLE
7075  * because it is sized independent of architecture. Unlike the other zones,
7076  * the starting point for ZONE_MOVABLE is not fixed. It may be different
7077  * in each node depending on the size of each node and how evenly kernelcore
7078  * is distributed. This helper function adjusts the zone ranges
7079  * provided by the architecture for a given node by using the end of the
7080  * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
7081  * zones within a node are in order of monotonic increases memory addresses
7082  */
7083 static void __init adjust_zone_range_for_zone_movable(int nid,
7084 					unsigned long zone_type,
7085 					unsigned long node_start_pfn,
7086 					unsigned long node_end_pfn,
7087 					unsigned long *zone_start_pfn,
7088 					unsigned long *zone_end_pfn)
7089 {
7090 	/* Only adjust if ZONE_MOVABLE is on this node */
7091 	if (zone_movable_pfn[nid]) {
7092 		/* Size ZONE_MOVABLE */
7093 		if (zone_type == ZONE_MOVABLE) {
7094 			*zone_start_pfn = zone_movable_pfn[nid];
7095 			*zone_end_pfn = min(node_end_pfn,
7096 				arch_zone_highest_possible_pfn[movable_zone]);
7097 
7098 		/* Adjust for ZONE_MOVABLE starting within this range */
7099 		} else if (!mirrored_kernelcore &&
7100 			*zone_start_pfn < zone_movable_pfn[nid] &&
7101 			*zone_end_pfn > zone_movable_pfn[nid]) {
7102 			*zone_end_pfn = zone_movable_pfn[nid];
7103 
7104 		/* Check if this whole range is within ZONE_MOVABLE */
7105 		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
7106 			*zone_start_pfn = *zone_end_pfn;
7107 	}
7108 }
7109 
7110 /*
7111  * Return the number of pages a zone spans in a node, including holes
7112  * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
7113  */
7114 static unsigned long __init zone_spanned_pages_in_node(int nid,
7115 					unsigned long zone_type,
7116 					unsigned long node_start_pfn,
7117 					unsigned long node_end_pfn,
7118 					unsigned long *zone_start_pfn,
7119 					unsigned long *zone_end_pfn)
7120 {
7121 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
7122 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
7123 	/* When hotadd a new node from cpu_up(), the node should be empty */
7124 	if (!node_start_pfn && !node_end_pfn)
7125 		return 0;
7126 
7127 	/* Get the start and end of the zone */
7128 	*zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
7129 	*zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
7130 	adjust_zone_range_for_zone_movable(nid, zone_type,
7131 				node_start_pfn, node_end_pfn,
7132 				zone_start_pfn, zone_end_pfn);
7133 
7134 	/* Check that this node has pages within the zone's required range */
7135 	if (*zone_end_pfn < node_start_pfn || *zone_start_pfn > node_end_pfn)
7136 		return 0;
7137 
7138 	/* Move the zone boundaries inside the node if necessary */
7139 	*zone_end_pfn = min(*zone_end_pfn, node_end_pfn);
7140 	*zone_start_pfn = max(*zone_start_pfn, node_start_pfn);
7141 
7142 	/* Return the spanned pages */
7143 	return *zone_end_pfn - *zone_start_pfn;
7144 }
7145 
7146 /*
7147  * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
7148  * then all holes in the requested range will be accounted for.
7149  */
7150 unsigned long __init __absent_pages_in_range(int nid,
7151 				unsigned long range_start_pfn,
7152 				unsigned long range_end_pfn)
7153 {
7154 	unsigned long nr_absent = range_end_pfn - range_start_pfn;
7155 	unsigned long start_pfn, end_pfn;
7156 	int i;
7157 
7158 	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
7159 		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
7160 		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
7161 		nr_absent -= end_pfn - start_pfn;
7162 	}
7163 	return nr_absent;
7164 }
7165 
7166 /**
7167  * absent_pages_in_range - Return number of page frames in holes within a range
7168  * @start_pfn: The start PFN to start searching for holes
7169  * @end_pfn: The end PFN to stop searching for holes
7170  *
7171  * Return: the number of pages frames in memory holes within a range.
7172  */
7173 unsigned long __init absent_pages_in_range(unsigned long start_pfn,
7174 							unsigned long end_pfn)
7175 {
7176 	return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
7177 }
7178 
7179 /* Return the number of page frames in holes in a zone on a node */
7180 static unsigned long __init zone_absent_pages_in_node(int nid,
7181 					unsigned long zone_type,
7182 					unsigned long node_start_pfn,
7183 					unsigned long node_end_pfn)
7184 {
7185 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
7186 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
7187 	unsigned long zone_start_pfn, zone_end_pfn;
7188 	unsigned long nr_absent;
7189 
7190 	/* When hotadd a new node from cpu_up(), the node should be empty */
7191 	if (!node_start_pfn && !node_end_pfn)
7192 		return 0;
7193 
7194 	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
7195 	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
7196 
7197 	adjust_zone_range_for_zone_movable(nid, zone_type,
7198 			node_start_pfn, node_end_pfn,
7199 			&zone_start_pfn, &zone_end_pfn);
7200 	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
7201 
7202 	/*
7203 	 * ZONE_MOVABLE handling.
7204 	 * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
7205 	 * and vice versa.
7206 	 */
7207 	if (mirrored_kernelcore && zone_movable_pfn[nid]) {
7208 		unsigned long start_pfn, end_pfn;
7209 		struct memblock_region *r;
7210 
7211 		for_each_mem_region(r) {
7212 			start_pfn = clamp(memblock_region_memory_base_pfn(r),
7213 					  zone_start_pfn, zone_end_pfn);
7214 			end_pfn = clamp(memblock_region_memory_end_pfn(r),
7215 					zone_start_pfn, zone_end_pfn);
7216 
7217 			if (zone_type == ZONE_MOVABLE &&
7218 			    memblock_is_mirror(r))
7219 				nr_absent += end_pfn - start_pfn;
7220 
7221 			if (zone_type == ZONE_NORMAL &&
7222 			    !memblock_is_mirror(r))
7223 				nr_absent += end_pfn - start_pfn;
7224 		}
7225 	}
7226 
7227 	return nr_absent;
7228 }
7229 
7230 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
7231 						unsigned long node_start_pfn,
7232 						unsigned long node_end_pfn)
7233 {
7234 	unsigned long realtotalpages = 0, totalpages = 0;
7235 	enum zone_type i;
7236 
7237 	for (i = 0; i < MAX_NR_ZONES; i++) {
7238 		struct zone *zone = pgdat->node_zones + i;
7239 		unsigned long zone_start_pfn, zone_end_pfn;
7240 		unsigned long spanned, absent;
7241 		unsigned long size, real_size;
7242 
7243 		spanned = zone_spanned_pages_in_node(pgdat->node_id, i,
7244 						     node_start_pfn,
7245 						     node_end_pfn,
7246 						     &zone_start_pfn,
7247 						     &zone_end_pfn);
7248 		absent = zone_absent_pages_in_node(pgdat->node_id, i,
7249 						   node_start_pfn,
7250 						   node_end_pfn);
7251 
7252 		size = spanned;
7253 		real_size = size - absent;
7254 
7255 		if (size)
7256 			zone->zone_start_pfn = zone_start_pfn;
7257 		else
7258 			zone->zone_start_pfn = 0;
7259 		zone->spanned_pages = size;
7260 		zone->present_pages = real_size;
7261 
7262 		totalpages += size;
7263 		realtotalpages += real_size;
7264 	}
7265 
7266 	pgdat->node_spanned_pages = totalpages;
7267 	pgdat->node_present_pages = realtotalpages;
7268 	pr_debug("On node %d totalpages: %lu\n", pgdat->node_id, realtotalpages);
7269 }
7270 
7271 #ifndef CONFIG_SPARSEMEM
7272 /*
7273  * Calculate the size of the zone->blockflags rounded to an unsigned long
7274  * Start by making sure zonesize is a multiple of pageblock_order by rounding
7275  * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
7276  * round what is now in bits to nearest long in bits, then return it in
7277  * bytes.
7278  */
7279 static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned long zonesize)
7280 {
7281 	unsigned long usemapsize;
7282 
7283 	zonesize += zone_start_pfn & (pageblock_nr_pages-1);
7284 	usemapsize = roundup(zonesize, pageblock_nr_pages);
7285 	usemapsize = usemapsize >> pageblock_order;
7286 	usemapsize *= NR_PAGEBLOCK_BITS;
7287 	usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
7288 
7289 	return usemapsize / 8;
7290 }
7291 
7292 static void __ref setup_usemap(struct zone *zone)
7293 {
7294 	unsigned long usemapsize = usemap_size(zone->zone_start_pfn,
7295 					       zone->spanned_pages);
7296 	zone->pageblock_flags = NULL;
7297 	if (usemapsize) {
7298 		zone->pageblock_flags =
7299 			memblock_alloc_node(usemapsize, SMP_CACHE_BYTES,
7300 					    zone_to_nid(zone));
7301 		if (!zone->pageblock_flags)
7302 			panic("Failed to allocate %ld bytes for zone %s pageblock flags on node %d\n",
7303 			      usemapsize, zone->name, zone_to_nid(zone));
7304 	}
7305 }
7306 #else
7307 static inline void setup_usemap(struct zone *zone) {}
7308 #endif /* CONFIG_SPARSEMEM */
7309 
7310 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
7311 
7312 /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
7313 void __init set_pageblock_order(void)
7314 {
7315 	unsigned int order;
7316 
7317 	/* Check that pageblock_nr_pages has not already been setup */
7318 	if (pageblock_order)
7319 		return;
7320 
7321 	if (HPAGE_SHIFT > PAGE_SHIFT)
7322 		order = HUGETLB_PAGE_ORDER;
7323 	else
7324 		order = MAX_ORDER - 1;
7325 
7326 	/*
7327 	 * Assume the largest contiguous order of interest is a huge page.
7328 	 * This value may be variable depending on boot parameters on IA64 and
7329 	 * powerpc.
7330 	 */
7331 	pageblock_order = order;
7332 }
7333 #else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
7334 
7335 /*
7336  * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
7337  * is unused as pageblock_order is set at compile-time. See
7338  * include/linux/pageblock-flags.h for the values of pageblock_order based on
7339  * the kernel config
7340  */
7341 void __init set_pageblock_order(void)
7342 {
7343 }
7344 
7345 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
7346 
7347 static unsigned long __init calc_memmap_size(unsigned long spanned_pages,
7348 						unsigned long present_pages)
7349 {
7350 	unsigned long pages = spanned_pages;
7351 
7352 	/*
7353 	 * Provide a more accurate estimation if there are holes within
7354 	 * the zone and SPARSEMEM is in use. If there are holes within the
7355 	 * zone, each populated memory region may cost us one or two extra
7356 	 * memmap pages due to alignment because memmap pages for each
7357 	 * populated regions may not be naturally aligned on page boundary.
7358 	 * So the (present_pages >> 4) heuristic is a tradeoff for that.
7359 	 */
7360 	if (spanned_pages > present_pages + (present_pages >> 4) &&
7361 	    IS_ENABLED(CONFIG_SPARSEMEM))
7362 		pages = present_pages;
7363 
7364 	return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
7365 }
7366 
7367 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
7368 static void pgdat_init_split_queue(struct pglist_data *pgdat)
7369 {
7370 	struct deferred_split *ds_queue = &pgdat->deferred_split_queue;
7371 
7372 	spin_lock_init(&ds_queue->split_queue_lock);
7373 	INIT_LIST_HEAD(&ds_queue->split_queue);
7374 	ds_queue->split_queue_len = 0;
7375 }
7376 #else
7377 static void pgdat_init_split_queue(struct pglist_data *pgdat) {}
7378 #endif
7379 
7380 #ifdef CONFIG_COMPACTION
7381 static void pgdat_init_kcompactd(struct pglist_data *pgdat)
7382 {
7383 	init_waitqueue_head(&pgdat->kcompactd_wait);
7384 }
7385 #else
7386 static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
7387 #endif
7388 
7389 static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
7390 {
7391 	pgdat_resize_init(pgdat);
7392 
7393 	pgdat_init_split_queue(pgdat);
7394 	pgdat_init_kcompactd(pgdat);
7395 
7396 	init_waitqueue_head(&pgdat->kswapd_wait);
7397 	init_waitqueue_head(&pgdat->pfmemalloc_wait);
7398 
7399 	pgdat_page_ext_init(pgdat);
7400 	lruvec_init(&pgdat->__lruvec);
7401 }
7402 
7403 static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
7404 							unsigned long remaining_pages)
7405 {
7406 	atomic_long_set(&zone->managed_pages, remaining_pages);
7407 	zone_set_nid(zone, nid);
7408 	zone->name = zone_names[idx];
7409 	zone->zone_pgdat = NODE_DATA(nid);
7410 	spin_lock_init(&zone->lock);
7411 	zone_seqlock_init(zone);
7412 	zone_pcp_init(zone);
7413 }
7414 
7415 /*
7416  * Set up the zone data structures
7417  * - init pgdat internals
7418  * - init all zones belonging to this node
7419  *
7420  * NOTE: this function is only called during memory hotplug
7421  */
7422 #ifdef CONFIG_MEMORY_HOTPLUG
7423 void __ref free_area_init_core_hotplug(int nid)
7424 {
7425 	enum zone_type z;
7426 	pg_data_t *pgdat = NODE_DATA(nid);
7427 
7428 	pgdat_init_internals(pgdat);
7429 	for (z = 0; z < MAX_NR_ZONES; z++)
7430 		zone_init_internals(&pgdat->node_zones[z], z, nid, 0);
7431 }
7432 #endif
7433 
7434 /*
7435  * Set up the zone data structures:
7436  *   - mark all pages reserved
7437  *   - mark all memory queues empty
7438  *   - clear the memory bitmaps
7439  *
7440  * NOTE: pgdat should get zeroed by caller.
7441  * NOTE: this function is only called during early init.
7442  */
7443 static void __init free_area_init_core(struct pglist_data *pgdat)
7444 {
7445 	enum zone_type j;
7446 	int nid = pgdat->node_id;
7447 
7448 	pgdat_init_internals(pgdat);
7449 	pgdat->per_cpu_nodestats = &boot_nodestats;
7450 
7451 	for (j = 0; j < MAX_NR_ZONES; j++) {
7452 		struct zone *zone = pgdat->node_zones + j;
7453 		unsigned long size, freesize, memmap_pages;
7454 
7455 		size = zone->spanned_pages;
7456 		freesize = zone->present_pages;
7457 
7458 		/*
7459 		 * Adjust freesize so that it accounts for how much memory
7460 		 * is used by this zone for memmap. This affects the watermark
7461 		 * and per-cpu initialisations
7462 		 */
7463 		memmap_pages = calc_memmap_size(size, freesize);
7464 		if (!is_highmem_idx(j)) {
7465 			if (freesize >= memmap_pages) {
7466 				freesize -= memmap_pages;
7467 				if (memmap_pages)
7468 					pr_debug("  %s zone: %lu pages used for memmap\n",
7469 						 zone_names[j], memmap_pages);
7470 			} else
7471 				pr_warn("  %s zone: %lu memmap pages exceeds freesize %lu\n",
7472 					zone_names[j], memmap_pages, freesize);
7473 		}
7474 
7475 		/* Account for reserved pages */
7476 		if (j == 0 && freesize > dma_reserve) {
7477 			freesize -= dma_reserve;
7478 			pr_debug("  %s zone: %lu pages reserved\n", zone_names[0], dma_reserve);
7479 		}
7480 
7481 		if (!is_highmem_idx(j))
7482 			nr_kernel_pages += freesize;
7483 		/* Charge for highmem memmap if there are enough kernel pages */
7484 		else if (nr_kernel_pages > memmap_pages * 2)
7485 			nr_kernel_pages -= memmap_pages;
7486 		nr_all_pages += freesize;
7487 
7488 		/*
7489 		 * Set an approximate value for lowmem here, it will be adjusted
7490 		 * when the bootmem allocator frees pages into the buddy system.
7491 		 * And all highmem pages will be managed by the buddy system.
7492 		 */
7493 		zone_init_internals(zone, j, nid, freesize);
7494 
7495 		if (!size)
7496 			continue;
7497 
7498 		set_pageblock_order();
7499 		setup_usemap(zone);
7500 		init_currently_empty_zone(zone, zone->zone_start_pfn, size);
7501 	}
7502 }
7503 
7504 #ifdef CONFIG_FLATMEM
7505 static void __ref alloc_node_mem_map(struct pglist_data *pgdat)
7506 {
7507 	unsigned long __maybe_unused start = 0;
7508 	unsigned long __maybe_unused offset = 0;
7509 
7510 	/* Skip empty nodes */
7511 	if (!pgdat->node_spanned_pages)
7512 		return;
7513 
7514 	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
7515 	offset = pgdat->node_start_pfn - start;
7516 	/* ia64 gets its own node_mem_map, before this, without bootmem */
7517 	if (!pgdat->node_mem_map) {
7518 		unsigned long size, end;
7519 		struct page *map;
7520 
7521 		/*
7522 		 * The zone's endpoints aren't required to be MAX_ORDER
7523 		 * aligned but the node_mem_map endpoints must be in order
7524 		 * for the buddy allocator to function correctly.
7525 		 */
7526 		end = pgdat_end_pfn(pgdat);
7527 		end = ALIGN(end, MAX_ORDER_NR_PAGES);
7528 		size =  (end - start) * sizeof(struct page);
7529 		map = memblock_alloc_node(size, SMP_CACHE_BYTES,
7530 					  pgdat->node_id);
7531 		if (!map)
7532 			panic("Failed to allocate %ld bytes for node %d memory map\n",
7533 			      size, pgdat->node_id);
7534 		pgdat->node_mem_map = map + offset;
7535 	}
7536 	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
7537 				__func__, pgdat->node_id, (unsigned long)pgdat,
7538 				(unsigned long)pgdat->node_mem_map);
7539 #ifndef CONFIG_NUMA
7540 	/*
7541 	 * With no DISCONTIG, the global mem_map is just set as node 0's
7542 	 */
7543 	if (pgdat == NODE_DATA(0)) {
7544 		mem_map = NODE_DATA(0)->node_mem_map;
7545 		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
7546 			mem_map -= offset;
7547 	}
7548 #endif
7549 }
7550 #else
7551 static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
7552 #endif /* CONFIG_FLATMEM */
7553 
7554 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
7555 static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
7556 {
7557 	pgdat->first_deferred_pfn = ULONG_MAX;
7558 }
7559 #else
7560 static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
7561 #endif
7562 
7563 static void __init free_area_init_node(int nid)
7564 {
7565 	pg_data_t *pgdat = NODE_DATA(nid);
7566 	unsigned long start_pfn = 0;
7567 	unsigned long end_pfn = 0;
7568 
7569 	/* pg_data_t should be reset to zero when it's allocated */
7570 	WARN_ON(pgdat->nr_zones || pgdat->kswapd_highest_zoneidx);
7571 
7572 	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
7573 
7574 	pgdat->node_id = nid;
7575 	pgdat->node_start_pfn = start_pfn;
7576 	pgdat->per_cpu_nodestats = NULL;
7577 
7578 	pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
7579 		(u64)start_pfn << PAGE_SHIFT,
7580 		end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
7581 	calculate_node_totalpages(pgdat, start_pfn, end_pfn);
7582 
7583 	alloc_node_mem_map(pgdat);
7584 	pgdat_set_deferred_range(pgdat);
7585 
7586 	free_area_init_core(pgdat);
7587 }
7588 
7589 void __init free_area_init_memoryless_node(int nid)
7590 {
7591 	free_area_init_node(nid);
7592 }
7593 
7594 #if MAX_NUMNODES > 1
7595 /*
7596  * Figure out the number of possible node ids.
7597  */
7598 void __init setup_nr_node_ids(void)
7599 {
7600 	unsigned int highest;
7601 
7602 	highest = find_last_bit(node_possible_map.bits, MAX_NUMNODES);
7603 	nr_node_ids = highest + 1;
7604 }
7605 #endif
7606 
7607 /**
7608  * node_map_pfn_alignment - determine the maximum internode alignment
7609  *
7610  * This function should be called after node map is populated and sorted.
7611  * It calculates the maximum power of two alignment which can distinguish
7612  * all the nodes.
7613  *
7614  * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
7615  * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
7616  * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
7617  * shifted, 1GiB is enough and this function will indicate so.
7618  *
7619  * This is used to test whether pfn -> nid mapping of the chosen memory
7620  * model has fine enough granularity to avoid incorrect mapping for the
7621  * populated node map.
7622  *
7623  * Return: the determined alignment in pfn's.  0 if there is no alignment
7624  * requirement (single node).
7625  */
7626 unsigned long __init node_map_pfn_alignment(void)
7627 {
7628 	unsigned long accl_mask = 0, last_end = 0;
7629 	unsigned long start, end, mask;
7630 	int last_nid = NUMA_NO_NODE;
7631 	int i, nid;
7632 
7633 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
7634 		if (!start || last_nid < 0 || last_nid == nid) {
7635 			last_nid = nid;
7636 			last_end = end;
7637 			continue;
7638 		}
7639 
7640 		/*
7641 		 * Start with a mask granular enough to pin-point to the
7642 		 * start pfn and tick off bits one-by-one until it becomes
7643 		 * too coarse to separate the current node from the last.
7644 		 */
7645 		mask = ~((1 << __ffs(start)) - 1);
7646 		while (mask && last_end <= (start & (mask << 1)))
7647 			mask <<= 1;
7648 
7649 		/* accumulate all internode masks */
7650 		accl_mask |= mask;
7651 	}
7652 
7653 	/* convert mask to number of pages */
7654 	return ~accl_mask + 1;
7655 }
7656 
7657 /**
7658  * find_min_pfn_with_active_regions - Find the minimum PFN registered
7659  *
7660  * Return: the minimum PFN based on information provided via
7661  * memblock_set_node().
7662  */
7663 unsigned long __init find_min_pfn_with_active_regions(void)
7664 {
7665 	return PHYS_PFN(memblock_start_of_DRAM());
7666 }
7667 
7668 /*
7669  * early_calculate_totalpages()
7670  * Sum pages in active regions for movable zone.
7671  * Populate N_MEMORY for calculating usable_nodes.
7672  */
7673 static unsigned long __init early_calculate_totalpages(void)
7674 {
7675 	unsigned long totalpages = 0;
7676 	unsigned long start_pfn, end_pfn;
7677 	int i, nid;
7678 
7679 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
7680 		unsigned long pages = end_pfn - start_pfn;
7681 
7682 		totalpages += pages;
7683 		if (pages)
7684 			node_set_state(nid, N_MEMORY);
7685 	}
7686 	return totalpages;
7687 }
7688 
7689 /*
7690  * Find the PFN the Movable zone begins in each node. Kernel memory
7691  * is spread evenly between nodes as long as the nodes have enough
7692  * memory. When they don't, some nodes will have more kernelcore than
7693  * others
7694  */
7695 static void __init find_zone_movable_pfns_for_nodes(void)
7696 {
7697 	int i, nid;
7698 	unsigned long usable_startpfn;
7699 	unsigned long kernelcore_node, kernelcore_remaining;
7700 	/* save the state before borrow the nodemask */
7701 	nodemask_t saved_node_state = node_states[N_MEMORY];
7702 	unsigned long totalpages = early_calculate_totalpages();
7703 	int usable_nodes = nodes_weight(node_states[N_MEMORY]);
7704 	struct memblock_region *r;
7705 
7706 	/* Need to find movable_zone earlier when movable_node is specified. */
7707 	find_usable_zone_for_movable();
7708 
7709 	/*
7710 	 * If movable_node is specified, ignore kernelcore and movablecore
7711 	 * options.
7712 	 */
7713 	if (movable_node_is_enabled()) {
7714 		for_each_mem_region(r) {
7715 			if (!memblock_is_hotpluggable(r))
7716 				continue;
7717 
7718 			nid = memblock_get_region_node(r);
7719 
7720 			usable_startpfn = PFN_DOWN(r->base);
7721 			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
7722 				min(usable_startpfn, zone_movable_pfn[nid]) :
7723 				usable_startpfn;
7724 		}
7725 
7726 		goto out2;
7727 	}
7728 
7729 	/*
7730 	 * If kernelcore=mirror is specified, ignore movablecore option
7731 	 */
7732 	if (mirrored_kernelcore) {
7733 		bool mem_below_4gb_not_mirrored = false;
7734 
7735 		for_each_mem_region(r) {
7736 			if (memblock_is_mirror(r))
7737 				continue;
7738 
7739 			nid = memblock_get_region_node(r);
7740 
7741 			usable_startpfn = memblock_region_memory_base_pfn(r);
7742 
7743 			if (usable_startpfn < 0x100000) {
7744 				mem_below_4gb_not_mirrored = true;
7745 				continue;
7746 			}
7747 
7748 			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
7749 				min(usable_startpfn, zone_movable_pfn[nid]) :
7750 				usable_startpfn;
7751 		}
7752 
7753 		if (mem_below_4gb_not_mirrored)
7754 			pr_warn("This configuration results in unmirrored kernel memory.\n");
7755 
7756 		goto out2;
7757 	}
7758 
7759 	/*
7760 	 * If kernelcore=nn% or movablecore=nn% was specified, calculate the
7761 	 * amount of necessary memory.
7762 	 */
7763 	if (required_kernelcore_percent)
7764 		required_kernelcore = (totalpages * 100 * required_kernelcore_percent) /
7765 				       10000UL;
7766 	if (required_movablecore_percent)
7767 		required_movablecore = (totalpages * 100 * required_movablecore_percent) /
7768 					10000UL;
7769 
7770 	/*
7771 	 * If movablecore= was specified, calculate what size of
7772 	 * kernelcore that corresponds so that memory usable for
7773 	 * any allocation type is evenly spread. If both kernelcore
7774 	 * and movablecore are specified, then the value of kernelcore
7775 	 * will be used for required_kernelcore if it's greater than
7776 	 * what movablecore would have allowed.
7777 	 */
7778 	if (required_movablecore) {
7779 		unsigned long corepages;
7780 
7781 		/*
7782 		 * Round-up so that ZONE_MOVABLE is at least as large as what
7783 		 * was requested by the user
7784 		 */
7785 		required_movablecore =
7786 			roundup(required_movablecore, MAX_ORDER_NR_PAGES);
7787 		required_movablecore = min(totalpages, required_movablecore);
7788 		corepages = totalpages - required_movablecore;
7789 
7790 		required_kernelcore = max(required_kernelcore, corepages);
7791 	}
7792 
7793 	/*
7794 	 * If kernelcore was not specified or kernelcore size is larger
7795 	 * than totalpages, there is no ZONE_MOVABLE.
7796 	 */
7797 	if (!required_kernelcore || required_kernelcore >= totalpages)
7798 		goto out;
7799 
7800 	/* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
7801 	usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
7802 
7803 restart:
7804 	/* Spread kernelcore memory as evenly as possible throughout nodes */
7805 	kernelcore_node = required_kernelcore / usable_nodes;
7806 	for_each_node_state(nid, N_MEMORY) {
7807 		unsigned long start_pfn, end_pfn;
7808 
7809 		/*
7810 		 * Recalculate kernelcore_node if the division per node
7811 		 * now exceeds what is necessary to satisfy the requested
7812 		 * amount of memory for the kernel
7813 		 */
7814 		if (required_kernelcore < kernelcore_node)
7815 			kernelcore_node = required_kernelcore / usable_nodes;
7816 
7817 		/*
7818 		 * As the map is walked, we track how much memory is usable
7819 		 * by the kernel using kernelcore_remaining. When it is
7820 		 * 0, the rest of the node is usable by ZONE_MOVABLE
7821 		 */
7822 		kernelcore_remaining = kernelcore_node;
7823 
7824 		/* Go through each range of PFNs within this node */
7825 		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
7826 			unsigned long size_pages;
7827 
7828 			start_pfn = max(start_pfn, zone_movable_pfn[nid]);
7829 			if (start_pfn >= end_pfn)
7830 				continue;
7831 
7832 			/* Account for what is only usable for kernelcore */
7833 			if (start_pfn < usable_startpfn) {
7834 				unsigned long kernel_pages;
7835 				kernel_pages = min(end_pfn, usable_startpfn)
7836 								- start_pfn;
7837 
7838 				kernelcore_remaining -= min(kernel_pages,
7839 							kernelcore_remaining);
7840 				required_kernelcore -= min(kernel_pages,
7841 							required_kernelcore);
7842 
7843 				/* Continue if range is now fully accounted */
7844 				if (end_pfn <= usable_startpfn) {
7845 
7846 					/*
7847 					 * Push zone_movable_pfn to the end so
7848 					 * that if we have to rebalance
7849 					 * kernelcore across nodes, we will
7850 					 * not double account here
7851 					 */
7852 					zone_movable_pfn[nid] = end_pfn;
7853 					continue;
7854 				}
7855 				start_pfn = usable_startpfn;
7856 			}
7857 
7858 			/*
7859 			 * The usable PFN range for ZONE_MOVABLE is from
7860 			 * start_pfn->end_pfn. Calculate size_pages as the
7861 			 * number of pages used as kernelcore
7862 			 */
7863 			size_pages = end_pfn - start_pfn;
7864 			if (size_pages > kernelcore_remaining)
7865 				size_pages = kernelcore_remaining;
7866 			zone_movable_pfn[nid] = start_pfn + size_pages;
7867 
7868 			/*
7869 			 * Some kernelcore has been met, update counts and
7870 			 * break if the kernelcore for this node has been
7871 			 * satisfied
7872 			 */
7873 			required_kernelcore -= min(required_kernelcore,
7874 								size_pages);
7875 			kernelcore_remaining -= size_pages;
7876 			if (!kernelcore_remaining)
7877 				break;
7878 		}
7879 	}
7880 
7881 	/*
7882 	 * If there is still required_kernelcore, we do another pass with one
7883 	 * less node in the count. This will push zone_movable_pfn[nid] further
7884 	 * along on the nodes that still have memory until kernelcore is
7885 	 * satisfied
7886 	 */
7887 	usable_nodes--;
7888 	if (usable_nodes && required_kernelcore > usable_nodes)
7889 		goto restart;
7890 
7891 out2:
7892 	/* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
7893 	for (nid = 0; nid < MAX_NUMNODES; nid++)
7894 		zone_movable_pfn[nid] =
7895 			roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
7896 
7897 out:
7898 	/* restore the node_state */
7899 	node_states[N_MEMORY] = saved_node_state;
7900 }
7901 
7902 /* Any regular or high memory on that node ? */
7903 static void check_for_memory(pg_data_t *pgdat, int nid)
7904 {
7905 	enum zone_type zone_type;
7906 
7907 	for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
7908 		struct zone *zone = &pgdat->node_zones[zone_type];
7909 		if (populated_zone(zone)) {
7910 			if (IS_ENABLED(CONFIG_HIGHMEM))
7911 				node_set_state(nid, N_HIGH_MEMORY);
7912 			if (zone_type <= ZONE_NORMAL)
7913 				node_set_state(nid, N_NORMAL_MEMORY);
7914 			break;
7915 		}
7916 	}
7917 }
7918 
7919 /*
7920  * Some architectures, e.g. ARC may have ZONE_HIGHMEM below ZONE_NORMAL. For
7921  * such cases we allow max_zone_pfn sorted in the descending order
7922  */
7923 bool __weak arch_has_descending_max_zone_pfns(void)
7924 {
7925 	return false;
7926 }
7927 
7928 /**
7929  * free_area_init - Initialise all pg_data_t and zone data
7930  * @max_zone_pfn: an array of max PFNs for each zone
7931  *
7932  * This will call free_area_init_node() for each active node in the system.
7933  * Using the page ranges provided by memblock_set_node(), the size of each
7934  * zone in each node and their holes is calculated. If the maximum PFN
7935  * between two adjacent zones match, it is assumed that the zone is empty.
7936  * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
7937  * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
7938  * starts where the previous one ended. For example, ZONE_DMA32 starts
7939  * at arch_max_dma_pfn.
7940  */
7941 void __init free_area_init(unsigned long *max_zone_pfn)
7942 {
7943 	unsigned long start_pfn, end_pfn;
7944 	int i, nid, zone;
7945 	bool descending;
7946 
7947 	/* Record where the zone boundaries are */
7948 	memset(arch_zone_lowest_possible_pfn, 0,
7949 				sizeof(arch_zone_lowest_possible_pfn));
7950 	memset(arch_zone_highest_possible_pfn, 0,
7951 				sizeof(arch_zone_highest_possible_pfn));
7952 
7953 	start_pfn = find_min_pfn_with_active_regions();
7954 	descending = arch_has_descending_max_zone_pfns();
7955 
7956 	for (i = 0; i < MAX_NR_ZONES; i++) {
7957 		if (descending)
7958 			zone = MAX_NR_ZONES - i - 1;
7959 		else
7960 			zone = i;
7961 
7962 		if (zone == ZONE_MOVABLE)
7963 			continue;
7964 
7965 		end_pfn = max(max_zone_pfn[zone], start_pfn);
7966 		arch_zone_lowest_possible_pfn[zone] = start_pfn;
7967 		arch_zone_highest_possible_pfn[zone] = end_pfn;
7968 
7969 		start_pfn = end_pfn;
7970 	}
7971 
7972 	/* Find the PFNs that ZONE_MOVABLE begins at in each node */
7973 	memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
7974 	find_zone_movable_pfns_for_nodes();
7975 
7976 	/* Print out the zone ranges */
7977 	pr_info("Zone ranges:\n");
7978 	for (i = 0; i < MAX_NR_ZONES; i++) {
7979 		if (i == ZONE_MOVABLE)
7980 			continue;
7981 		pr_info("  %-8s ", zone_names[i]);
7982 		if (arch_zone_lowest_possible_pfn[i] ==
7983 				arch_zone_highest_possible_pfn[i])
7984 			pr_cont("empty\n");
7985 		else
7986 			pr_cont("[mem %#018Lx-%#018Lx]\n",
7987 				(u64)arch_zone_lowest_possible_pfn[i]
7988 					<< PAGE_SHIFT,
7989 				((u64)arch_zone_highest_possible_pfn[i]
7990 					<< PAGE_SHIFT) - 1);
7991 	}
7992 
7993 	/* Print out the PFNs ZONE_MOVABLE begins at in each node */
7994 	pr_info("Movable zone start for each node\n");
7995 	for (i = 0; i < MAX_NUMNODES; i++) {
7996 		if (zone_movable_pfn[i])
7997 			pr_info("  Node %d: %#018Lx\n", i,
7998 			       (u64)zone_movable_pfn[i] << PAGE_SHIFT);
7999 	}
8000 
8001 	/*
8002 	 * Print out the early node map, and initialize the
8003 	 * subsection-map relative to active online memory ranges to
8004 	 * enable future "sub-section" extensions of the memory map.
8005 	 */
8006 	pr_info("Early memory node ranges\n");
8007 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
8008 		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
8009 			(u64)start_pfn << PAGE_SHIFT,
8010 			((u64)end_pfn << PAGE_SHIFT) - 1);
8011 		subsection_map_init(start_pfn, end_pfn - start_pfn);
8012 	}
8013 
8014 	/* Initialise every node */
8015 	mminit_verify_pageflags_layout();
8016 	setup_nr_node_ids();
8017 	for_each_online_node(nid) {
8018 		pg_data_t *pgdat = NODE_DATA(nid);
8019 		free_area_init_node(nid);
8020 
8021 		/* Any memory on that node */
8022 		if (pgdat->node_present_pages)
8023 			node_set_state(nid, N_MEMORY);
8024 		check_for_memory(pgdat, nid);
8025 	}
8026 
8027 	memmap_init();
8028 }
8029 
8030 static int __init cmdline_parse_core(char *p, unsigned long *core,
8031 				     unsigned long *percent)
8032 {
8033 	unsigned long long coremem;
8034 	char *endptr;
8035 
8036 	if (!p)
8037 		return -EINVAL;
8038 
8039 	/* Value may be a percentage of total memory, otherwise bytes */
8040 	coremem = simple_strtoull(p, &endptr, 0);
8041 	if (*endptr == '%') {
8042 		/* Paranoid check for percent values greater than 100 */
8043 		WARN_ON(coremem > 100);
8044 
8045 		*percent = coremem;
8046 	} else {
8047 		coremem = memparse(p, &p);
8048 		/* Paranoid check that UL is enough for the coremem value */
8049 		WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);
8050 
8051 		*core = coremem >> PAGE_SHIFT;
8052 		*percent = 0UL;
8053 	}
8054 	return 0;
8055 }
8056 
8057 /*
8058  * kernelcore=size sets the amount of memory for use for allocations that
8059  * cannot be reclaimed or migrated.
8060  */
8061 static int __init cmdline_parse_kernelcore(char *p)
8062 {
8063 	/* parse kernelcore=mirror */
8064 	if (parse_option_str(p, "mirror")) {
8065 		mirrored_kernelcore = true;
8066 		return 0;
8067 	}
8068 
8069 	return cmdline_parse_core(p, &required_kernelcore,
8070 				  &required_kernelcore_percent);
8071 }
8072 
8073 /*
8074  * movablecore=size sets the amount of memory for use for allocations that
8075  * can be reclaimed or migrated.
8076  */
8077 static int __init cmdline_parse_movablecore(char *p)
8078 {
8079 	return cmdline_parse_core(p, &required_movablecore,
8080 				  &required_movablecore_percent);
8081 }
8082 
8083 early_param("kernelcore", cmdline_parse_kernelcore);
8084 early_param("movablecore", cmdline_parse_movablecore);
8085 
8086 void adjust_managed_page_count(struct page *page, long count)
8087 {
8088 	atomic_long_add(count, &page_zone(page)->managed_pages);
8089 	totalram_pages_add(count);
8090 #ifdef CONFIG_HIGHMEM
8091 	if (PageHighMem(page))
8092 		totalhigh_pages_add(count);
8093 #endif
8094 }
8095 EXPORT_SYMBOL(adjust_managed_page_count);
8096 
8097 unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
8098 {
8099 	void *pos;
8100 	unsigned long pages = 0;
8101 
8102 	start = (void *)PAGE_ALIGN((unsigned long)start);
8103 	end = (void *)((unsigned long)end & PAGE_MASK);
8104 	for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
8105 		struct page *page = virt_to_page(pos);
8106 		void *direct_map_addr;
8107 
8108 		/*
8109 		 * 'direct_map_addr' might be different from 'pos'
8110 		 * because some architectures' virt_to_page()
8111 		 * work with aliases.  Getting the direct map
8112 		 * address ensures that we get a _writeable_
8113 		 * alias for the memset().
8114 		 */
8115 		direct_map_addr = page_address(page);
8116 		/*
8117 		 * Perform a kasan-unchecked memset() since this memory
8118 		 * has not been initialized.
8119 		 */
8120 		direct_map_addr = kasan_reset_tag(direct_map_addr);
8121 		if ((unsigned int)poison <= 0xFF)
8122 			memset(direct_map_addr, poison, PAGE_SIZE);
8123 
8124 		free_reserved_page(page);
8125 	}
8126 
8127 	if (pages && s)
8128 		pr_info("Freeing %s memory: %ldK\n",
8129 			s, pages << (PAGE_SHIFT - 10));
8130 
8131 	return pages;
8132 }
8133 
8134 void __init mem_init_print_info(void)
8135 {
8136 	unsigned long physpages, codesize, datasize, rosize, bss_size;
8137 	unsigned long init_code_size, init_data_size;
8138 
8139 	physpages = get_num_physpages();
8140 	codesize = _etext - _stext;
8141 	datasize = _edata - _sdata;
8142 	rosize = __end_rodata - __start_rodata;
8143 	bss_size = __bss_stop - __bss_start;
8144 	init_data_size = __init_end - __init_begin;
8145 	init_code_size = _einittext - _sinittext;
8146 
8147 	/*
8148 	 * Detect special cases and adjust section sizes accordingly:
8149 	 * 1) .init.* may be embedded into .data sections
8150 	 * 2) .init.text.* may be out of [__init_begin, __init_end],
8151 	 *    please refer to arch/tile/kernel/vmlinux.lds.S.
8152 	 * 3) .rodata.* may be embedded into .text or .data sections.
8153 	 */
8154 #define adj_init_size(start, end, size, pos, adj) \
8155 	do { \
8156 		if (start <= pos && pos < end && size > adj) \
8157 			size -= adj; \
8158 	} while (0)
8159 
8160 	adj_init_size(__init_begin, __init_end, init_data_size,
8161 		     _sinittext, init_code_size);
8162 	adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
8163 	adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
8164 	adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
8165 	adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);
8166 
8167 #undef	adj_init_size
8168 
8169 	pr_info("Memory: %luK/%luK available (%luK kernel code, %luK rwdata, %luK rodata, %luK init, %luK bss, %luK reserved, %luK cma-reserved"
8170 #ifdef	CONFIG_HIGHMEM
8171 		", %luK highmem"
8172 #endif
8173 		")\n",
8174 		nr_free_pages() << (PAGE_SHIFT - 10),
8175 		physpages << (PAGE_SHIFT - 10),
8176 		codesize >> 10, datasize >> 10, rosize >> 10,
8177 		(init_data_size + init_code_size) >> 10, bss_size >> 10,
8178 		(physpages - totalram_pages() - totalcma_pages) << (PAGE_SHIFT - 10),
8179 		totalcma_pages << (PAGE_SHIFT - 10)
8180 #ifdef	CONFIG_HIGHMEM
8181 		, totalhigh_pages() << (PAGE_SHIFT - 10)
8182 #endif
8183 		);
8184 }
8185 
8186 /**
8187  * set_dma_reserve - set the specified number of pages reserved in the first zone
8188  * @new_dma_reserve: The number of pages to mark reserved
8189  *
8190  * The per-cpu batchsize and zone watermarks are determined by managed_pages.
8191  * In the DMA zone, a significant percentage may be consumed by kernel image
8192  * and other unfreeable allocations which can skew the watermarks badly. This
8193  * function may optionally be used to account for unfreeable pages in the
8194  * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
8195  * smaller per-cpu batchsize.
8196  */
8197 void __init set_dma_reserve(unsigned long new_dma_reserve)
8198 {
8199 	dma_reserve = new_dma_reserve;
8200 }
8201 
8202 static int page_alloc_cpu_dead(unsigned int cpu)
8203 {
8204 	struct zone *zone;
8205 
8206 	lru_add_drain_cpu(cpu);
8207 	drain_pages(cpu);
8208 
8209 	/*
8210 	 * Spill the event counters of the dead processor
8211 	 * into the current processors event counters.
8212 	 * This artificially elevates the count of the current
8213 	 * processor.
8214 	 */
8215 	vm_events_fold_cpu(cpu);
8216 
8217 	/*
8218 	 * Zero the differential counters of the dead processor
8219 	 * so that the vm statistics are consistent.
8220 	 *
8221 	 * This is only okay since the processor is dead and cannot
8222 	 * race with what we are doing.
8223 	 */
8224 	cpu_vm_stats_fold(cpu);
8225 
8226 	for_each_populated_zone(zone)
8227 		zone_pcp_update(zone, 0);
8228 
8229 	return 0;
8230 }
8231 
8232 static int page_alloc_cpu_online(unsigned int cpu)
8233 {
8234 	struct zone *zone;
8235 
8236 	for_each_populated_zone(zone)
8237 		zone_pcp_update(zone, 1);
8238 	return 0;
8239 }
8240 
8241 #ifdef CONFIG_NUMA
8242 int hashdist = HASHDIST_DEFAULT;
8243 
8244 static int __init set_hashdist(char *str)
8245 {
8246 	if (!str)
8247 		return 0;
8248 	hashdist = simple_strtoul(str, &str, 0);
8249 	return 1;
8250 }
8251 __setup("hashdist=", set_hashdist);
8252 #endif
8253 
8254 void __init page_alloc_init(void)
8255 {
8256 	int ret;
8257 
8258 #ifdef CONFIG_NUMA
8259 	if (num_node_state(N_MEMORY) == 1)
8260 		hashdist = 0;
8261 #endif
8262 
8263 	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC,
8264 					"mm/page_alloc:pcp",
8265 					page_alloc_cpu_online,
8266 					page_alloc_cpu_dead);
8267 	WARN_ON(ret < 0);
8268 }
8269 
8270 /*
8271  * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
8272  *	or min_free_kbytes changes.
8273  */
8274 static void calculate_totalreserve_pages(void)
8275 {
8276 	struct pglist_data *pgdat;
8277 	unsigned long reserve_pages = 0;
8278 	enum zone_type i, j;
8279 
8280 	for_each_online_pgdat(pgdat) {
8281 
8282 		pgdat->totalreserve_pages = 0;
8283 
8284 		for (i = 0; i < MAX_NR_ZONES; i++) {
8285 			struct zone *zone = pgdat->node_zones + i;
8286 			long max = 0;
8287 			unsigned long managed_pages = zone_managed_pages(zone);
8288 
8289 			/* Find valid and maximum lowmem_reserve in the zone */
8290 			for (j = i; j < MAX_NR_ZONES; j++) {
8291 				if (zone->lowmem_reserve[j] > max)
8292 					max = zone->lowmem_reserve[j];
8293 			}
8294 
8295 			/* we treat the high watermark as reserved pages. */
8296 			max += high_wmark_pages(zone);
8297 
8298 			if (max > managed_pages)
8299 				max = managed_pages;
8300 
8301 			pgdat->totalreserve_pages += max;
8302 
8303 			reserve_pages += max;
8304 		}
8305 	}
8306 	totalreserve_pages = reserve_pages;
8307 }
8308 
8309 /*
8310  * setup_per_zone_lowmem_reserve - called whenever
8311  *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
8312  *	has a correct pages reserved value, so an adequate number of
8313  *	pages are left in the zone after a successful __alloc_pages().
8314  */
8315 static void setup_per_zone_lowmem_reserve(void)
8316 {
8317 	struct pglist_data *pgdat;
8318 	enum zone_type i, j;
8319 
8320 	for_each_online_pgdat(pgdat) {
8321 		for (i = 0; i < MAX_NR_ZONES - 1; i++) {
8322 			struct zone *zone = &pgdat->node_zones[i];
8323 			int ratio = sysctl_lowmem_reserve_ratio[i];
8324 			bool clear = !ratio || !zone_managed_pages(zone);
8325 			unsigned long managed_pages = 0;
8326 
8327 			for (j = i + 1; j < MAX_NR_ZONES; j++) {
8328 				struct zone *upper_zone = &pgdat->node_zones[j];
8329 
8330 				managed_pages += zone_managed_pages(upper_zone);
8331 
8332 				if (clear)
8333 					zone->lowmem_reserve[j] = 0;
8334 				else
8335 					zone->lowmem_reserve[j] = managed_pages / ratio;
8336 			}
8337 		}
8338 	}
8339 
8340 	/* update totalreserve_pages */
8341 	calculate_totalreserve_pages();
8342 }
8343 
8344 static void __setup_per_zone_wmarks(void)
8345 {
8346 	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
8347 	unsigned long lowmem_pages = 0;
8348 	struct zone *zone;
8349 	unsigned long flags;
8350 
8351 	/* Calculate total number of !ZONE_HIGHMEM pages */
8352 	for_each_zone(zone) {
8353 		if (!is_highmem(zone))
8354 			lowmem_pages += zone_managed_pages(zone);
8355 	}
8356 
8357 	for_each_zone(zone) {
8358 		u64 tmp;
8359 
8360 		spin_lock_irqsave(&zone->lock, flags);
8361 		tmp = (u64)pages_min * zone_managed_pages(zone);
8362 		do_div(tmp, lowmem_pages);
8363 		if (is_highmem(zone)) {
8364 			/*
8365 			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
8366 			 * need highmem pages, so cap pages_min to a small
8367 			 * value here.
8368 			 *
8369 			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
8370 			 * deltas control async page reclaim, and so should
8371 			 * not be capped for highmem.
8372 			 */
8373 			unsigned long min_pages;
8374 
8375 			min_pages = zone_managed_pages(zone) / 1024;
8376 			min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
8377 			zone->_watermark[WMARK_MIN] = min_pages;
8378 		} else {
8379 			/*
8380 			 * If it's a lowmem zone, reserve a number of pages
8381 			 * proportionate to the zone's size.
8382 			 */
8383 			zone->_watermark[WMARK_MIN] = tmp;
8384 		}
8385 
8386 		/*
8387 		 * Set the kswapd watermarks distance according to the
8388 		 * scale factor in proportion to available memory, but
8389 		 * ensure a minimum size on small systems.
8390 		 */
8391 		tmp = max_t(u64, tmp >> 2,
8392 			    mult_frac(zone_managed_pages(zone),
8393 				      watermark_scale_factor, 10000));
8394 
8395 		zone->watermark_boost = 0;
8396 		zone->_watermark[WMARK_LOW]  = min_wmark_pages(zone) + tmp;
8397 		zone->_watermark[WMARK_HIGH] = min_wmark_pages(zone) + tmp * 2;
8398 
8399 		spin_unlock_irqrestore(&zone->lock, flags);
8400 	}
8401 
8402 	/* update totalreserve_pages */
8403 	calculate_totalreserve_pages();
8404 }
8405 
8406 /**
8407  * setup_per_zone_wmarks - called when min_free_kbytes changes
8408  * or when memory is hot-{added|removed}
8409  *
8410  * Ensures that the watermark[min,low,high] values for each zone are set
8411  * correctly with respect to min_free_kbytes.
8412  */
8413 void setup_per_zone_wmarks(void)
8414 {
8415 	struct zone *zone;
8416 	static DEFINE_SPINLOCK(lock);
8417 
8418 	spin_lock(&lock);
8419 	__setup_per_zone_wmarks();
8420 	spin_unlock(&lock);
8421 
8422 	/*
8423 	 * The watermark size have changed so update the pcpu batch
8424 	 * and high limits or the limits may be inappropriate.
8425 	 */
8426 	for_each_zone(zone)
8427 		zone_pcp_update(zone, 0);
8428 }
8429 
8430 /*
8431  * Initialise min_free_kbytes.
8432  *
8433  * For small machines we want it small (128k min).  For large machines
8434  * we want it large (256MB max).  But it is not linear, because network
8435  * bandwidth does not increase linearly with machine size.  We use
8436  *
8437  *	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
8438  *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
8439  *
8440  * which yields
8441  *
8442  * 16MB:	512k
8443  * 32MB:	724k
8444  * 64MB:	1024k
8445  * 128MB:	1448k
8446  * 256MB:	2048k
8447  * 512MB:	2896k
8448  * 1024MB:	4096k
8449  * 2048MB:	5792k
8450  * 4096MB:	8192k
8451  * 8192MB:	11584k
8452  * 16384MB:	16384k
8453  */
8454 int __meminit init_per_zone_wmark_min(void)
8455 {
8456 	unsigned long lowmem_kbytes;
8457 	int new_min_free_kbytes;
8458 
8459 	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
8460 	new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
8461 
8462 	if (new_min_free_kbytes > user_min_free_kbytes) {
8463 		min_free_kbytes = new_min_free_kbytes;
8464 		if (min_free_kbytes < 128)
8465 			min_free_kbytes = 128;
8466 		if (min_free_kbytes > 262144)
8467 			min_free_kbytes = 262144;
8468 	} else {
8469 		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
8470 				new_min_free_kbytes, user_min_free_kbytes);
8471 	}
8472 	setup_per_zone_wmarks();
8473 	refresh_zone_stat_thresholds();
8474 	setup_per_zone_lowmem_reserve();
8475 
8476 #ifdef CONFIG_NUMA
8477 	setup_min_unmapped_ratio();
8478 	setup_min_slab_ratio();
8479 #endif
8480 
8481 	khugepaged_min_free_kbytes_update();
8482 
8483 	return 0;
8484 }
8485 postcore_initcall(init_per_zone_wmark_min)
8486 
8487 /*
8488  * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
8489  *	that we can call two helper functions whenever min_free_kbytes
8490  *	changes.
8491  */
8492 int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
8493 		void *buffer, size_t *length, loff_t *ppos)
8494 {
8495 	int rc;
8496 
8497 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8498 	if (rc)
8499 		return rc;
8500 
8501 	if (write) {
8502 		user_min_free_kbytes = min_free_kbytes;
8503 		setup_per_zone_wmarks();
8504 	}
8505 	return 0;
8506 }
8507 
8508 int watermark_scale_factor_sysctl_handler(struct ctl_table *table, int write,
8509 		void *buffer, size_t *length, loff_t *ppos)
8510 {
8511 	int rc;
8512 
8513 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8514 	if (rc)
8515 		return rc;
8516 
8517 	if (write)
8518 		setup_per_zone_wmarks();
8519 
8520 	return 0;
8521 }
8522 
8523 #ifdef CONFIG_NUMA
8524 static void setup_min_unmapped_ratio(void)
8525 {
8526 	pg_data_t *pgdat;
8527 	struct zone *zone;
8528 
8529 	for_each_online_pgdat(pgdat)
8530 		pgdat->min_unmapped_pages = 0;
8531 
8532 	for_each_zone(zone)
8533 		zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
8534 						         sysctl_min_unmapped_ratio) / 100;
8535 }
8536 
8537 
8538 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
8539 		void *buffer, size_t *length, loff_t *ppos)
8540 {
8541 	int rc;
8542 
8543 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8544 	if (rc)
8545 		return rc;
8546 
8547 	setup_min_unmapped_ratio();
8548 
8549 	return 0;
8550 }
8551 
8552 static void setup_min_slab_ratio(void)
8553 {
8554 	pg_data_t *pgdat;
8555 	struct zone *zone;
8556 
8557 	for_each_online_pgdat(pgdat)
8558 		pgdat->min_slab_pages = 0;
8559 
8560 	for_each_zone(zone)
8561 		zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
8562 						     sysctl_min_slab_ratio) / 100;
8563 }
8564 
8565 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
8566 		void *buffer, size_t *length, loff_t *ppos)
8567 {
8568 	int rc;
8569 
8570 	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
8571 	if (rc)
8572 		return rc;
8573 
8574 	setup_min_slab_ratio();
8575 
8576 	return 0;
8577 }
8578 #endif
8579 
8580 /*
8581  * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
8582  *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
8583  *	whenever sysctl_lowmem_reserve_ratio changes.
8584  *
8585  * The reserve ratio obviously has absolutely no relation with the
8586  * minimum watermarks. The lowmem reserve ratio can only make sense
8587  * if in function of the boot time zone sizes.
8588  */
8589 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
8590 		void *buffer, size_t *length, loff_t *ppos)
8591 {
8592 	int i;
8593 
8594 	proc_dointvec_minmax(table, write, buffer, length, ppos);
8595 
8596 	for (i = 0; i < MAX_NR_ZONES; i++) {
8597 		if (sysctl_lowmem_reserve_ratio[i] < 1)
8598 			sysctl_lowmem_reserve_ratio[i] = 0;
8599 	}
8600 
8601 	setup_per_zone_lowmem_reserve();
8602 	return 0;
8603 }
8604 
8605 /*
8606  * percpu_pagelist_high_fraction - changes the pcp->high for each zone on each
8607  * cpu. It is the fraction of total pages in each zone that a hot per cpu
8608  * pagelist can have before it gets flushed back to buddy allocator.
8609  */
8610 int percpu_pagelist_high_fraction_sysctl_handler(struct ctl_table *table,
8611 		int write, void *buffer, size_t *length, loff_t *ppos)
8612 {
8613 	struct zone *zone;
8614 	int old_percpu_pagelist_high_fraction;
8615 	int ret;
8616 
8617 	mutex_lock(&pcp_batch_high_lock);
8618 	old_percpu_pagelist_high_fraction = percpu_pagelist_high_fraction;
8619 
8620 	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
8621 	if (!write || ret < 0)
8622 		goto out;
8623 
8624 	/* Sanity checking to avoid pcp imbalance */
8625 	if (percpu_pagelist_high_fraction &&
8626 	    percpu_pagelist_high_fraction < MIN_PERCPU_PAGELIST_HIGH_FRACTION) {
8627 		percpu_pagelist_high_fraction = old_percpu_pagelist_high_fraction;
8628 		ret = -EINVAL;
8629 		goto out;
8630 	}
8631 
8632 	/* No change? */
8633 	if (percpu_pagelist_high_fraction == old_percpu_pagelist_high_fraction)
8634 		goto out;
8635 
8636 	for_each_populated_zone(zone)
8637 		zone_set_pageset_high_and_batch(zone, 0);
8638 out:
8639 	mutex_unlock(&pcp_batch_high_lock);
8640 	return ret;
8641 }
8642 
8643 #ifndef __HAVE_ARCH_RESERVED_KERNEL_PAGES
8644 /*
8645  * Returns the number of pages that arch has reserved but
8646  * is not known to alloc_large_system_hash().
8647  */
8648 static unsigned long __init arch_reserved_kernel_pages(void)
8649 {
8650 	return 0;
8651 }
8652 #endif
8653 
8654 /*
8655  * Adaptive scale is meant to reduce sizes of hash tables on large memory
8656  * machines. As memory size is increased the scale is also increased but at
8657  * slower pace.  Starting from ADAPT_SCALE_BASE (64G), every time memory
8658  * quadruples the scale is increased by one, which means the size of hash table
8659  * only doubles, instead of quadrupling as well.
8660  * Because 32-bit systems cannot have large physical memory, where this scaling
8661  * makes sense, it is disabled on such platforms.
8662  */
8663 #if __BITS_PER_LONG > 32
8664 #define ADAPT_SCALE_BASE	(64ul << 30)
8665 #define ADAPT_SCALE_SHIFT	2
8666 #define ADAPT_SCALE_NPAGES	(ADAPT_SCALE_BASE >> PAGE_SHIFT)
8667 #endif
8668 
8669 /*
8670  * allocate a large system hash table from bootmem
8671  * - it is assumed that the hash table must contain an exact power-of-2
8672  *   quantity of entries
8673  * - limit is the number of hash buckets, not the total allocation size
8674  */
8675 void *__init alloc_large_system_hash(const char *tablename,
8676 				     unsigned long bucketsize,
8677 				     unsigned long numentries,
8678 				     int scale,
8679 				     int flags,
8680 				     unsigned int *_hash_shift,
8681 				     unsigned int *_hash_mask,
8682 				     unsigned long low_limit,
8683 				     unsigned long high_limit)
8684 {
8685 	unsigned long long max = high_limit;
8686 	unsigned long log2qty, size;
8687 	void *table = NULL;
8688 	gfp_t gfp_flags;
8689 	bool virt;
8690 	bool huge;
8691 
8692 	/* allow the kernel cmdline to have a say */
8693 	if (!numentries) {
8694 		/* round applicable memory size up to nearest megabyte */
8695 		numentries = nr_kernel_pages;
8696 		numentries -= arch_reserved_kernel_pages();
8697 
8698 		/* It isn't necessary when PAGE_SIZE >= 1MB */
8699 		if (PAGE_SHIFT < 20)
8700 			numentries = round_up(numentries, (1<<20)/PAGE_SIZE);
8701 
8702 #if __BITS_PER_LONG > 32
8703 		if (!high_limit) {
8704 			unsigned long adapt;
8705 
8706 			for (adapt = ADAPT_SCALE_NPAGES; adapt < numentries;
8707 			     adapt <<= ADAPT_SCALE_SHIFT)
8708 				scale++;
8709 		}
8710 #endif
8711 
8712 		/* limit to 1 bucket per 2^scale bytes of low memory */
8713 		if (scale > PAGE_SHIFT)
8714 			numentries >>= (scale - PAGE_SHIFT);
8715 		else
8716 			numentries <<= (PAGE_SHIFT - scale);
8717 
8718 		/* Make sure we've got at least a 0-order allocation.. */
8719 		if (unlikely(flags & HASH_SMALL)) {
8720 			/* Makes no sense without HASH_EARLY */
8721 			WARN_ON(!(flags & HASH_EARLY));
8722 			if (!(numentries >> *_hash_shift)) {
8723 				numentries = 1UL << *_hash_shift;
8724 				BUG_ON(!numentries);
8725 			}
8726 		} else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
8727 			numentries = PAGE_SIZE / bucketsize;
8728 	}
8729 	numentries = roundup_pow_of_two(numentries);
8730 
8731 	/* limit allocation size to 1/16 total memory by default */
8732 	if (max == 0) {
8733 		max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
8734 		do_div(max, bucketsize);
8735 	}
8736 	max = min(max, 0x80000000ULL);
8737 
8738 	if (numentries < low_limit)
8739 		numentries = low_limit;
8740 	if (numentries > max)
8741 		numentries = max;
8742 
8743 	log2qty = ilog2(numentries);
8744 
8745 	gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;
8746 	do {
8747 		virt = false;
8748 		size = bucketsize << log2qty;
8749 		if (flags & HASH_EARLY) {
8750 			if (flags & HASH_ZERO)
8751 				table = memblock_alloc(size, SMP_CACHE_BYTES);
8752 			else
8753 				table = memblock_alloc_raw(size,
8754 							   SMP_CACHE_BYTES);
8755 		} else if (get_order(size) >= MAX_ORDER || hashdist) {
8756 			table = __vmalloc(size, gfp_flags);
8757 			virt = true;
8758 			huge = is_vm_area_hugepages(table);
8759 		} else {
8760 			/*
8761 			 * If bucketsize is not a power-of-two, we may free
8762 			 * some pages at the end of hash table which
8763 			 * alloc_pages_exact() automatically does
8764 			 */
8765 			table = alloc_pages_exact(size, gfp_flags);
8766 			kmemleak_alloc(table, size, 1, gfp_flags);
8767 		}
8768 	} while (!table && size > PAGE_SIZE && --log2qty);
8769 
8770 	if (!table)
8771 		panic("Failed to allocate %s hash table\n", tablename);
8772 
8773 	pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n",
8774 		tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size,
8775 		virt ? (huge ? "vmalloc hugepage" : "vmalloc") : "linear");
8776 
8777 	if (_hash_shift)
8778 		*_hash_shift = log2qty;
8779 	if (_hash_mask)
8780 		*_hash_mask = (1 << log2qty) - 1;
8781 
8782 	return table;
8783 }
8784 
8785 /*
8786  * This function checks whether pageblock includes unmovable pages or not.
8787  *
8788  * PageLRU check without isolation or lru_lock could race so that
8789  * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
8790  * check without lock_page also may miss some movable non-lru pages at
8791  * race condition. So you can't expect this function should be exact.
8792  *
8793  * Returns a page without holding a reference. If the caller wants to
8794  * dereference that page (e.g., dumping), it has to make sure that it
8795  * cannot get removed (e.g., via memory unplug) concurrently.
8796  *
8797  */
8798 struct page *has_unmovable_pages(struct zone *zone, struct page *page,
8799 				 int migratetype, int flags)
8800 {
8801 	unsigned long iter = 0;
8802 	unsigned long pfn = page_to_pfn(page);
8803 	unsigned long offset = pfn % pageblock_nr_pages;
8804 
8805 	if (is_migrate_cma_page(page)) {
8806 		/*
8807 		 * CMA allocations (alloc_contig_range) really need to mark
8808 		 * isolate CMA pageblocks even when they are not movable in fact
8809 		 * so consider them movable here.
8810 		 */
8811 		if (is_migrate_cma(migratetype))
8812 			return NULL;
8813 
8814 		return page;
8815 	}
8816 
8817 	for (; iter < pageblock_nr_pages - offset; iter++) {
8818 		if (!pfn_valid_within(pfn + iter))
8819 			continue;
8820 
8821 		page = pfn_to_page(pfn + iter);
8822 
8823 		/*
8824 		 * Both, bootmem allocations and memory holes are marked
8825 		 * PG_reserved and are unmovable. We can even have unmovable
8826 		 * allocations inside ZONE_MOVABLE, for example when
8827 		 * specifying "movablecore".
8828 		 */
8829 		if (PageReserved(page))
8830 			return page;
8831 
8832 		/*
8833 		 * If the zone is movable and we have ruled out all reserved
8834 		 * pages then it should be reasonably safe to assume the rest
8835 		 * is movable.
8836 		 */
8837 		if (zone_idx(zone) == ZONE_MOVABLE)
8838 			continue;
8839 
8840 		/*
8841 		 * Hugepages are not in LRU lists, but they're movable.
8842 		 * THPs are on the LRU, but need to be counted as #small pages.
8843 		 * We need not scan over tail pages because we don't
8844 		 * handle each tail page individually in migration.
8845 		 */
8846 		if (PageHuge(page) || PageTransCompound(page)) {
8847 			struct page *head = compound_head(page);
8848 			unsigned int skip_pages;
8849 
8850 			if (PageHuge(page)) {
8851 				if (!hugepage_migration_supported(page_hstate(head)))
8852 					return page;
8853 			} else if (!PageLRU(head) && !__PageMovable(head)) {
8854 				return page;
8855 			}
8856 
8857 			skip_pages = compound_nr(head) - (page - head);
8858 			iter += skip_pages - 1;
8859 			continue;
8860 		}
8861 
8862 		/*
8863 		 * We can't use page_count without pin a page
8864 		 * because another CPU can free compound page.
8865 		 * This check already skips compound tails of THP
8866 		 * because their page->_refcount is zero at all time.
8867 		 */
8868 		if (!page_ref_count(page)) {
8869 			if (PageBuddy(page))
8870 				iter += (1 << buddy_order(page)) - 1;
8871 			continue;
8872 		}
8873 
8874 		/*
8875 		 * The HWPoisoned page may be not in buddy system, and
8876 		 * page_count() is not 0.
8877 		 */
8878 		if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
8879 			continue;
8880 
8881 		/*
8882 		 * We treat all PageOffline() pages as movable when offlining
8883 		 * to give drivers a chance to decrement their reference count
8884 		 * in MEM_GOING_OFFLINE in order to indicate that these pages
8885 		 * can be offlined as there are no direct references anymore.
8886 		 * For actually unmovable PageOffline() where the driver does
8887 		 * not support this, we will fail later when trying to actually
8888 		 * move these pages that still have a reference count > 0.
8889 		 * (false negatives in this function only)
8890 		 */
8891 		if ((flags & MEMORY_OFFLINE) && PageOffline(page))
8892 			continue;
8893 
8894 		if (__PageMovable(page) || PageLRU(page))
8895 			continue;
8896 
8897 		/*
8898 		 * If there are RECLAIMABLE pages, we need to check
8899 		 * it.  But now, memory offline itself doesn't call
8900 		 * shrink_node_slabs() and it still to be fixed.
8901 		 */
8902 		return page;
8903 	}
8904 	return NULL;
8905 }
8906 
8907 #ifdef CONFIG_CONTIG_ALLOC
8908 static unsigned long pfn_max_align_down(unsigned long pfn)
8909 {
8910 	return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
8911 			     pageblock_nr_pages) - 1);
8912 }
8913 
8914 static unsigned long pfn_max_align_up(unsigned long pfn)
8915 {
8916 	return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES,
8917 				pageblock_nr_pages));
8918 }
8919 
8920 #if defined(CONFIG_DYNAMIC_DEBUG) || \
8921 	(defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
8922 /* Usage: See admin-guide/dynamic-debug-howto.rst */
8923 static void alloc_contig_dump_pages(struct list_head *page_list)
8924 {
8925 	DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, "migrate failure");
8926 
8927 	if (DYNAMIC_DEBUG_BRANCH(descriptor)) {
8928 		struct page *page;
8929 
8930 		dump_stack();
8931 		list_for_each_entry(page, page_list, lru)
8932 			dump_page(page, "migration failure");
8933 	}
8934 }
8935 #else
8936 static inline void alloc_contig_dump_pages(struct list_head *page_list)
8937 {
8938 }
8939 #endif
8940 
8941 /* [start, end) must belong to a single zone. */
8942 static int __alloc_contig_migrate_range(struct compact_control *cc,
8943 					unsigned long start, unsigned long end)
8944 {
8945 	/* This function is based on compact_zone() from compaction.c. */
8946 	unsigned int nr_reclaimed;
8947 	unsigned long pfn = start;
8948 	unsigned int tries = 0;
8949 	int ret = 0;
8950 	struct migration_target_control mtc = {
8951 		.nid = zone_to_nid(cc->zone),
8952 		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
8953 	};
8954 
8955 	lru_cache_disable();
8956 
8957 	while (pfn < end || !list_empty(&cc->migratepages)) {
8958 		if (fatal_signal_pending(current)) {
8959 			ret = -EINTR;
8960 			break;
8961 		}
8962 
8963 		if (list_empty(&cc->migratepages)) {
8964 			cc->nr_migratepages = 0;
8965 			ret = isolate_migratepages_range(cc, pfn, end);
8966 			if (ret && ret != -EAGAIN)
8967 				break;
8968 			pfn = cc->migrate_pfn;
8969 			tries = 0;
8970 		} else if (++tries == 5) {
8971 			ret = -EBUSY;
8972 			break;
8973 		}
8974 
8975 		nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
8976 							&cc->migratepages);
8977 		cc->nr_migratepages -= nr_reclaimed;
8978 
8979 		ret = migrate_pages(&cc->migratepages, alloc_migration_target,
8980 				NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
8981 
8982 		/*
8983 		 * On -ENOMEM, migrate_pages() bails out right away. It is pointless
8984 		 * to retry again over this error, so do the same here.
8985 		 */
8986 		if (ret == -ENOMEM)
8987 			break;
8988 	}
8989 
8990 	lru_cache_enable();
8991 	if (ret < 0) {
8992 		if (ret == -EBUSY)
8993 			alloc_contig_dump_pages(&cc->migratepages);
8994 		putback_movable_pages(&cc->migratepages);
8995 		return ret;
8996 	}
8997 	return 0;
8998 }
8999 
9000 /**
9001  * alloc_contig_range() -- tries to allocate given range of pages
9002  * @start:	start PFN to allocate
9003  * @end:	one-past-the-last PFN to allocate
9004  * @migratetype:	migratetype of the underlying pageblocks (either
9005  *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
9006  *			in range must have the same migratetype and it must
9007  *			be either of the two.
9008  * @gfp_mask:	GFP mask to use during compaction
9009  *
9010  * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
9011  * aligned.  The PFN range must belong to a single zone.
9012  *
9013  * The first thing this routine does is attempt to MIGRATE_ISOLATE all
9014  * pageblocks in the range.  Once isolated, the pageblocks should not
9015  * be modified by others.
9016  *
9017  * Return: zero on success or negative error code.  On success all
9018  * pages which PFN is in [start, end) are allocated for the caller and
9019  * need to be freed with free_contig_range().
9020  */
9021 int alloc_contig_range(unsigned long start, unsigned long end,
9022 		       unsigned migratetype, gfp_t gfp_mask)
9023 {
9024 	unsigned long outer_start, outer_end;
9025 	unsigned int order;
9026 	int ret = 0;
9027 
9028 	struct compact_control cc = {
9029 		.nr_migratepages = 0,
9030 		.order = -1,
9031 		.zone = page_zone(pfn_to_page(start)),
9032 		.mode = MIGRATE_SYNC,
9033 		.ignore_skip_hint = true,
9034 		.no_set_skip_hint = true,
9035 		.gfp_mask = current_gfp_context(gfp_mask),
9036 		.alloc_contig = true,
9037 	};
9038 	INIT_LIST_HEAD(&cc.migratepages);
9039 
9040 	/*
9041 	 * What we do here is we mark all pageblocks in range as
9042 	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
9043 	 * have different sizes, and due to the way page allocator
9044 	 * work, we align the range to biggest of the two pages so
9045 	 * that page allocator won't try to merge buddies from
9046 	 * different pageblocks and change MIGRATE_ISOLATE to some
9047 	 * other migration type.
9048 	 *
9049 	 * Once the pageblocks are marked as MIGRATE_ISOLATE, we
9050 	 * migrate the pages from an unaligned range (ie. pages that
9051 	 * we are interested in).  This will put all the pages in
9052 	 * range back to page allocator as MIGRATE_ISOLATE.
9053 	 *
9054 	 * When this is done, we take the pages in range from page
9055 	 * allocator removing them from the buddy system.  This way
9056 	 * page allocator will never consider using them.
9057 	 *
9058 	 * This lets us mark the pageblocks back as
9059 	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
9060 	 * aligned range but not in the unaligned, original range are
9061 	 * put back to page allocator so that buddy can use them.
9062 	 */
9063 
9064 	ret = start_isolate_page_range(pfn_max_align_down(start),
9065 				       pfn_max_align_up(end), migratetype, 0);
9066 	if (ret)
9067 		return ret;
9068 
9069 	drain_all_pages(cc.zone);
9070 
9071 	/*
9072 	 * In case of -EBUSY, we'd like to know which page causes problem.
9073 	 * So, just fall through. test_pages_isolated() has a tracepoint
9074 	 * which will report the busy page.
9075 	 *
9076 	 * It is possible that busy pages could become available before
9077 	 * the call to test_pages_isolated, and the range will actually be
9078 	 * allocated.  So, if we fall through be sure to clear ret so that
9079 	 * -EBUSY is not accidentally used or returned to caller.
9080 	 */
9081 	ret = __alloc_contig_migrate_range(&cc, start, end);
9082 	if (ret && ret != -EBUSY)
9083 		goto done;
9084 	ret = 0;
9085 
9086 	/*
9087 	 * Pages from [start, end) are within a MAX_ORDER_NR_PAGES
9088 	 * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
9089 	 * more, all pages in [start, end) are free in page allocator.
9090 	 * What we are going to do is to allocate all pages from
9091 	 * [start, end) (that is remove them from page allocator).
9092 	 *
9093 	 * The only problem is that pages at the beginning and at the
9094 	 * end of interesting range may be not aligned with pages that
9095 	 * page allocator holds, ie. they can be part of higher order
9096 	 * pages.  Because of this, we reserve the bigger range and
9097 	 * once this is done free the pages we are not interested in.
9098 	 *
9099 	 * We don't have to hold zone->lock here because the pages are
9100 	 * isolated thus they won't get removed from buddy.
9101 	 */
9102 
9103 	order = 0;
9104 	outer_start = start;
9105 	while (!PageBuddy(pfn_to_page(outer_start))) {
9106 		if (++order >= MAX_ORDER) {
9107 			outer_start = start;
9108 			break;
9109 		}
9110 		outer_start &= ~0UL << order;
9111 	}
9112 
9113 	if (outer_start != start) {
9114 		order = buddy_order(pfn_to_page(outer_start));
9115 
9116 		/*
9117 		 * outer_start page could be small order buddy page and
9118 		 * it doesn't include start page. Adjust outer_start
9119 		 * in this case to report failed page properly
9120 		 * on tracepoint in test_pages_isolated()
9121 		 */
9122 		if (outer_start + (1UL << order) <= start)
9123 			outer_start = start;
9124 	}
9125 
9126 	/* Make sure the range is really isolated. */
9127 	if (test_pages_isolated(outer_start, end, 0)) {
9128 		ret = -EBUSY;
9129 		goto done;
9130 	}
9131 
9132 	/* Grab isolated pages from freelists. */
9133 	outer_end = isolate_freepages_range(&cc, outer_start, end);
9134 	if (!outer_end) {
9135 		ret = -EBUSY;
9136 		goto done;
9137 	}
9138 
9139 	/* Free head and tail (if any) */
9140 	if (start != outer_start)
9141 		free_contig_range(outer_start, start - outer_start);
9142 	if (end != outer_end)
9143 		free_contig_range(end, outer_end - end);
9144 
9145 done:
9146 	undo_isolate_page_range(pfn_max_align_down(start),
9147 				pfn_max_align_up(end), migratetype);
9148 	return ret;
9149 }
9150 EXPORT_SYMBOL(alloc_contig_range);
9151 
9152 static int __alloc_contig_pages(unsigned long start_pfn,
9153 				unsigned long nr_pages, gfp_t gfp_mask)
9154 {
9155 	unsigned long end_pfn = start_pfn + nr_pages;
9156 
9157 	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
9158 				  gfp_mask);
9159 }
9160 
9161 static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
9162 				   unsigned long nr_pages)
9163 {
9164 	unsigned long i, end_pfn = start_pfn + nr_pages;
9165 	struct page *page;
9166 
9167 	for (i = start_pfn; i < end_pfn; i++) {
9168 		page = pfn_to_online_page(i);
9169 		if (!page)
9170 			return false;
9171 
9172 		if (page_zone(page) != z)
9173 			return false;
9174 
9175 		if (PageReserved(page))
9176 			return false;
9177 	}
9178 	return true;
9179 }
9180 
9181 static bool zone_spans_last_pfn(const struct zone *zone,
9182 				unsigned long start_pfn, unsigned long nr_pages)
9183 {
9184 	unsigned long last_pfn = start_pfn + nr_pages - 1;
9185 
9186 	return zone_spans_pfn(zone, last_pfn);
9187 }
9188 
9189 /**
9190  * alloc_contig_pages() -- tries to find and allocate contiguous range of pages
9191  * @nr_pages:	Number of contiguous pages to allocate
9192  * @gfp_mask:	GFP mask to limit search and used during compaction
9193  * @nid:	Target node
9194  * @nodemask:	Mask for other possible nodes
9195  *
9196  * This routine is a wrapper around alloc_contig_range(). It scans over zones
9197  * on an applicable zonelist to find a contiguous pfn range which can then be
9198  * tried for allocation with alloc_contig_range(). This routine is intended
9199  * for allocation requests which can not be fulfilled with the buddy allocator.
9200  *
9201  * The allocated memory is always aligned to a page boundary. If nr_pages is a
9202  * power of two then the alignment is guaranteed to be to the given nr_pages
9203  * (e.g. 1GB request would be aligned to 1GB).
9204  *
9205  * Allocated pages can be freed with free_contig_range() or by manually calling
9206  * __free_page() on each allocated page.
9207  *
9208  * Return: pointer to contiguous pages on success, or NULL if not successful.
9209  */
9210 struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
9211 				int nid, nodemask_t *nodemask)
9212 {
9213 	unsigned long ret, pfn, flags;
9214 	struct zonelist *zonelist;
9215 	struct zone *zone;
9216 	struct zoneref *z;
9217 
9218 	zonelist = node_zonelist(nid, gfp_mask);
9219 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
9220 					gfp_zone(gfp_mask), nodemask) {
9221 		spin_lock_irqsave(&zone->lock, flags);
9222 
9223 		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
9224 		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
9225 			if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
9226 				/*
9227 				 * We release the zone lock here because
9228 				 * alloc_contig_range() will also lock the zone
9229 				 * at some point. If there's an allocation
9230 				 * spinning on this lock, it may win the race
9231 				 * and cause alloc_contig_range() to fail...
9232 				 */
9233 				spin_unlock_irqrestore(&zone->lock, flags);
9234 				ret = __alloc_contig_pages(pfn, nr_pages,
9235 							gfp_mask);
9236 				if (!ret)
9237 					return pfn_to_page(pfn);
9238 				spin_lock_irqsave(&zone->lock, flags);
9239 			}
9240 			pfn += nr_pages;
9241 		}
9242 		spin_unlock_irqrestore(&zone->lock, flags);
9243 	}
9244 	return NULL;
9245 }
9246 #endif /* CONFIG_CONTIG_ALLOC */
9247 
9248 void free_contig_range(unsigned long pfn, unsigned long nr_pages)
9249 {
9250 	unsigned long count = 0;
9251 
9252 	for (; nr_pages--; pfn++) {
9253 		struct page *page = pfn_to_page(pfn);
9254 
9255 		count += page_count(page) != 1;
9256 		__free_page(page);
9257 	}
9258 	WARN(count != 0, "%lu pages are still in use!\n", count);
9259 }
9260 EXPORT_SYMBOL(free_contig_range);
9261 
9262 /*
9263  * The zone indicated has a new number of managed_pages; batch sizes and percpu
9264  * page high values need to be recalculated.
9265  */
9266 void zone_pcp_update(struct zone *zone, int cpu_online)
9267 {
9268 	mutex_lock(&pcp_batch_high_lock);
9269 	zone_set_pageset_high_and_batch(zone, cpu_online);
9270 	mutex_unlock(&pcp_batch_high_lock);
9271 }
9272 
9273 /*
9274  * Effectively disable pcplists for the zone by setting the high limit to 0
9275  * and draining all cpus. A concurrent page freeing on another CPU that's about
9276  * to put the page on pcplist will either finish before the drain and the page
9277  * will be drained, or observe the new high limit and skip the pcplist.
9278  *
9279  * Must be paired with a call to zone_pcp_enable().
9280  */
9281 void zone_pcp_disable(struct zone *zone)
9282 {
9283 	mutex_lock(&pcp_batch_high_lock);
9284 	__zone_set_pageset_high_and_batch(zone, 0, 1);
9285 	__drain_all_pages(zone, true);
9286 }
9287 
9288 void zone_pcp_enable(struct zone *zone)
9289 {
9290 	__zone_set_pageset_high_and_batch(zone, zone->pageset_high, zone->pageset_batch);
9291 	mutex_unlock(&pcp_batch_high_lock);
9292 }
9293 
9294 void zone_pcp_reset(struct zone *zone)
9295 {
9296 	int cpu;
9297 	struct per_cpu_zonestat *pzstats;
9298 
9299 	if (zone->per_cpu_pageset != &boot_pageset) {
9300 		for_each_online_cpu(cpu) {
9301 			pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
9302 			drain_zonestat(zone, pzstats);
9303 		}
9304 		free_percpu(zone->per_cpu_pageset);
9305 		free_percpu(zone->per_cpu_zonestats);
9306 		zone->per_cpu_pageset = &boot_pageset;
9307 		zone->per_cpu_zonestats = &boot_zonestats;
9308 	}
9309 }
9310 
9311 #ifdef CONFIG_MEMORY_HOTREMOVE
9312 /*
9313  * All pages in the range must be in a single zone, must not contain holes,
9314  * must span full sections, and must be isolated before calling this function.
9315  */
9316 void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
9317 {
9318 	unsigned long pfn = start_pfn;
9319 	struct page *page;
9320 	struct zone *zone;
9321 	unsigned int order;
9322 	unsigned long flags;
9323 
9324 	offline_mem_sections(pfn, end_pfn);
9325 	zone = page_zone(pfn_to_page(pfn));
9326 	spin_lock_irqsave(&zone->lock, flags);
9327 	while (pfn < end_pfn) {
9328 		page = pfn_to_page(pfn);
9329 		/*
9330 		 * The HWPoisoned page may be not in buddy system, and
9331 		 * page_count() is not 0.
9332 		 */
9333 		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
9334 			pfn++;
9335 			continue;
9336 		}
9337 		/*
9338 		 * At this point all remaining PageOffline() pages have a
9339 		 * reference count of 0 and can simply be skipped.
9340 		 */
9341 		if (PageOffline(page)) {
9342 			BUG_ON(page_count(page));
9343 			BUG_ON(PageBuddy(page));
9344 			pfn++;
9345 			continue;
9346 		}
9347 
9348 		BUG_ON(page_count(page));
9349 		BUG_ON(!PageBuddy(page));
9350 		order = buddy_order(page);
9351 		del_page_from_free_list(page, zone, order);
9352 		pfn += (1 << order);
9353 	}
9354 	spin_unlock_irqrestore(&zone->lock, flags);
9355 }
9356 #endif
9357 
9358 bool is_free_buddy_page(struct page *page)
9359 {
9360 	struct zone *zone = page_zone(page);
9361 	unsigned long pfn = page_to_pfn(page);
9362 	unsigned long flags;
9363 	unsigned int order;
9364 
9365 	spin_lock_irqsave(&zone->lock, flags);
9366 	for (order = 0; order < MAX_ORDER; order++) {
9367 		struct page *page_head = page - (pfn & ((1 << order) - 1));
9368 
9369 		if (PageBuddy(page_head) && buddy_order(page_head) >= order)
9370 			break;
9371 	}
9372 	spin_unlock_irqrestore(&zone->lock, flags);
9373 
9374 	return order < MAX_ORDER;
9375 }
9376 
9377 #ifdef CONFIG_MEMORY_FAILURE
9378 /*
9379  * Break down a higher-order page in sub-pages, and keep our target out of
9380  * buddy allocator.
9381  */
9382 static void break_down_buddy_pages(struct zone *zone, struct page *page,
9383 				   struct page *target, int low, int high,
9384 				   int migratetype)
9385 {
9386 	unsigned long size = 1 << high;
9387 	struct page *current_buddy, *next_page;
9388 
9389 	while (high > low) {
9390 		high--;
9391 		size >>= 1;
9392 
9393 		if (target >= &page[size]) {
9394 			next_page = page + size;
9395 			current_buddy = page;
9396 		} else {
9397 			next_page = page;
9398 			current_buddy = page + size;
9399 		}
9400 
9401 		if (set_page_guard(zone, current_buddy, high, migratetype))
9402 			continue;
9403 
9404 		if (current_buddy != target) {
9405 			add_to_free_list(current_buddy, zone, high, migratetype);
9406 			set_buddy_order(current_buddy, high);
9407 			page = next_page;
9408 		}
9409 	}
9410 }
9411 
9412 /*
9413  * Take a page that will be marked as poisoned off the buddy allocator.
9414  */
9415 bool take_page_off_buddy(struct page *page)
9416 {
9417 	struct zone *zone = page_zone(page);
9418 	unsigned long pfn = page_to_pfn(page);
9419 	unsigned long flags;
9420 	unsigned int order;
9421 	bool ret = false;
9422 
9423 	spin_lock_irqsave(&zone->lock, flags);
9424 	for (order = 0; order < MAX_ORDER; order++) {
9425 		struct page *page_head = page - (pfn & ((1 << order) - 1));
9426 		int page_order = buddy_order(page_head);
9427 
9428 		if (PageBuddy(page_head) && page_order >= order) {
9429 			unsigned long pfn_head = page_to_pfn(page_head);
9430 			int migratetype = get_pfnblock_migratetype(page_head,
9431 								   pfn_head);
9432 
9433 			del_page_from_free_list(page_head, zone, page_order);
9434 			break_down_buddy_pages(zone, page_head, page, 0,
9435 						page_order, migratetype);
9436 			if (!is_migrate_isolate(migratetype))
9437 				__mod_zone_freepage_state(zone, -1, migratetype);
9438 			ret = true;
9439 			break;
9440 		}
9441 		if (page_count(page_head) > 0)
9442 			break;
9443 	}
9444 	spin_unlock_irqrestore(&zone->lock, flags);
9445 	return ret;
9446 }
9447 #endif
9448