xref: /linux/mm/madvise.c (revision ea518afc992032f7570c0a89ac9240b387dc0faf)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *	linux/mm/madvise.c
4  *
5  * Copyright (C) 1999  Linus Torvalds
6  * Copyright (C) 2002  Christoph Hellwig
7  */
8 
9 #include <linux/mman.h>
10 #include <linux/pagemap.h>
11 #include <linux/syscalls.h>
12 #include <linux/mempolicy.h>
13 #include <linux/page-isolation.h>
14 #include <linux/page_idle.h>
15 #include <linux/userfaultfd_k.h>
16 #include <linux/hugetlb.h>
17 #include <linux/falloc.h>
18 #include <linux/fadvise.h>
19 #include <linux/sched.h>
20 #include <linux/sched/mm.h>
21 #include <linux/mm_inline.h>
22 #include <linux/string.h>
23 #include <linux/uio.h>
24 #include <linux/ksm.h>
25 #include <linux/fs.h>
26 #include <linux/file.h>
27 #include <linux/blkdev.h>
28 #include <linux/backing-dev.h>
29 #include <linux/pagewalk.h>
30 #include <linux/swap.h>
31 #include <linux/swapops.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/mmu_notifier.h>
34 
35 #include <asm/tlb.h>
36 
37 #include "internal.h"
38 #include "swap.h"
39 
40 struct madvise_walk_private {
41 	struct mmu_gather *tlb;
42 	bool pageout;
43 };
44 
45 /*
46  * Any behaviour which results in changes to the vma->vm_flags needs to
47  * take mmap_lock for writing. Others, which simply traverse vmas, need
48  * to only take it for reading.
49  */
50 static int madvise_need_mmap_write(int behavior)
51 {
52 	switch (behavior) {
53 	case MADV_REMOVE:
54 	case MADV_WILLNEED:
55 	case MADV_DONTNEED:
56 	case MADV_DONTNEED_LOCKED:
57 	case MADV_COLD:
58 	case MADV_PAGEOUT:
59 	case MADV_FREE:
60 	case MADV_POPULATE_READ:
61 	case MADV_POPULATE_WRITE:
62 	case MADV_COLLAPSE:
63 		return 0;
64 	default:
65 		/* be safe, default to 1. list exceptions explicitly */
66 		return 1;
67 	}
68 }
69 
70 #ifdef CONFIG_ANON_VMA_NAME
71 struct anon_vma_name *anon_vma_name_alloc(const char *name)
72 {
73 	struct anon_vma_name *anon_name;
74 	size_t count;
75 
76 	/* Add 1 for NUL terminator at the end of the anon_name->name */
77 	count = strlen(name) + 1;
78 	anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 	if (anon_name) {
80 		kref_init(&anon_name->kref);
81 		memcpy(anon_name->name, name, count);
82 	}
83 
84 	return anon_name;
85 }
86 
87 void anon_vma_name_free(struct kref *kref)
88 {
89 	struct anon_vma_name *anon_name =
90 			container_of(kref, struct anon_vma_name, kref);
91 	kfree(anon_name);
92 }
93 
94 struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95 {
96 	mmap_assert_locked(vma->vm_mm);
97 
98 	return vma->anon_name;
99 }
100 
101 /* mmap_lock should be write-locked */
102 static int replace_anon_vma_name(struct vm_area_struct *vma,
103 				 struct anon_vma_name *anon_name)
104 {
105 	struct anon_vma_name *orig_name = anon_vma_name(vma);
106 
107 	if (!anon_name) {
108 		vma->anon_name = NULL;
109 		anon_vma_name_put(orig_name);
110 		return 0;
111 	}
112 
113 	if (anon_vma_name_eq(orig_name, anon_name))
114 		return 0;
115 
116 	vma->anon_name = anon_vma_name_reuse(anon_name);
117 	anon_vma_name_put(orig_name);
118 
119 	return 0;
120 }
121 #else /* CONFIG_ANON_VMA_NAME */
122 static int replace_anon_vma_name(struct vm_area_struct *vma,
123 				 struct anon_vma_name *anon_name)
124 {
125 	if (anon_name)
126 		return -EINVAL;
127 
128 	return 0;
129 }
130 #endif /* CONFIG_ANON_VMA_NAME */
131 /*
132  * Update the vm_flags on region of a vma, splitting it or merging it as
133  * necessary.  Must be called with mmap_lock held for writing;
134  * Caller should ensure anon_name stability by raising its refcount even when
135  * anon_name belongs to a valid vma because this function might free that vma.
136  */
137 static int madvise_update_vma(struct vm_area_struct *vma,
138 			      struct vm_area_struct **prev, unsigned long start,
139 			      unsigned long end, unsigned long new_flags,
140 			      struct anon_vma_name *anon_name)
141 {
142 	struct mm_struct *mm = vma->vm_mm;
143 	int error;
144 	VMA_ITERATOR(vmi, mm, start);
145 
146 	if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
147 		*prev = vma;
148 		return 0;
149 	}
150 
151 	vma = vma_modify_flags_name(&vmi, *prev, vma, start, end, new_flags,
152 				    anon_name);
153 	if (IS_ERR(vma))
154 		return PTR_ERR(vma);
155 
156 	*prev = vma;
157 
158 	/* vm_flags is protected by the mmap_lock held in write mode. */
159 	vma_start_write(vma);
160 	vm_flags_reset(vma, new_flags);
161 	if (!vma->vm_file || vma_is_anon_shmem(vma)) {
162 		error = replace_anon_vma_name(vma, anon_name);
163 		if (error)
164 			return error;
165 	}
166 
167 	return 0;
168 }
169 
170 #ifdef CONFIG_SWAP
171 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
172 		unsigned long end, struct mm_walk *walk)
173 {
174 	struct vm_area_struct *vma = walk->private;
175 	struct swap_iocb *splug = NULL;
176 	pte_t *ptep = NULL;
177 	spinlock_t *ptl;
178 	unsigned long addr;
179 
180 	for (addr = start; addr < end; addr += PAGE_SIZE) {
181 		pte_t pte;
182 		swp_entry_t entry;
183 		struct folio *folio;
184 
185 		if (!ptep++) {
186 			ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
187 			if (!ptep)
188 				break;
189 		}
190 
191 		pte = ptep_get(ptep);
192 		if (!is_swap_pte(pte))
193 			continue;
194 		entry = pte_to_swp_entry(pte);
195 		if (unlikely(non_swap_entry(entry)))
196 			continue;
197 
198 		pte_unmap_unlock(ptep, ptl);
199 		ptep = NULL;
200 
201 		folio = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
202 					     vma, addr, &splug);
203 		if (folio)
204 			folio_put(folio);
205 	}
206 
207 	if (ptep)
208 		pte_unmap_unlock(ptep, ptl);
209 	swap_read_unplug(splug);
210 	cond_resched();
211 
212 	return 0;
213 }
214 
215 static const struct mm_walk_ops swapin_walk_ops = {
216 	.pmd_entry		= swapin_walk_pmd_entry,
217 	.walk_lock		= PGWALK_RDLOCK,
218 };
219 
220 static void shmem_swapin_range(struct vm_area_struct *vma,
221 		unsigned long start, unsigned long end,
222 		struct address_space *mapping)
223 {
224 	XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
225 	pgoff_t end_index = linear_page_index(vma, end) - 1;
226 	struct folio *folio;
227 	struct swap_iocb *splug = NULL;
228 
229 	rcu_read_lock();
230 	xas_for_each(&xas, folio, end_index) {
231 		unsigned long addr;
232 		swp_entry_t entry;
233 
234 		if (!xa_is_value(folio))
235 			continue;
236 		entry = radix_to_swp_entry(folio);
237 		/* There might be swapin error entries in shmem mapping. */
238 		if (non_swap_entry(entry))
239 			continue;
240 
241 		addr = vma->vm_start +
242 			((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
243 		xas_pause(&xas);
244 		rcu_read_unlock();
245 
246 		folio = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
247 					     vma, addr, &splug);
248 		if (folio)
249 			folio_put(folio);
250 
251 		rcu_read_lock();
252 	}
253 	rcu_read_unlock();
254 	swap_read_unplug(splug);
255 }
256 #endif		/* CONFIG_SWAP */
257 
258 /*
259  * Schedule all required I/O operations.  Do not wait for completion.
260  */
261 static long madvise_willneed(struct vm_area_struct *vma,
262 			     struct vm_area_struct **prev,
263 			     unsigned long start, unsigned long end)
264 {
265 	struct mm_struct *mm = vma->vm_mm;
266 	struct file *file = vma->vm_file;
267 	loff_t offset;
268 
269 	*prev = vma;
270 #ifdef CONFIG_SWAP
271 	if (!file) {
272 		walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
273 		lru_add_drain(); /* Push any new pages onto the LRU now */
274 		return 0;
275 	}
276 
277 	if (shmem_mapping(file->f_mapping)) {
278 		shmem_swapin_range(vma, start, end, file->f_mapping);
279 		lru_add_drain(); /* Push any new pages onto the LRU now */
280 		return 0;
281 	}
282 #else
283 	if (!file)
284 		return -EBADF;
285 #endif
286 
287 	if (IS_DAX(file_inode(file))) {
288 		/* no bad return value, but ignore advice */
289 		return 0;
290 	}
291 
292 	/*
293 	 * Filesystem's fadvise may need to take various locks.  We need to
294 	 * explicitly grab a reference because the vma (and hence the
295 	 * vma's reference to the file) can go away as soon as we drop
296 	 * mmap_lock.
297 	 */
298 	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
299 	get_file(file);
300 	offset = (loff_t)(start - vma->vm_start)
301 			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
302 	mmap_read_unlock(mm);
303 	vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
304 	fput(file);
305 	mmap_read_lock(mm);
306 	return 0;
307 }
308 
309 static inline bool can_do_file_pageout(struct vm_area_struct *vma)
310 {
311 	if (!vma->vm_file)
312 		return false;
313 	/*
314 	 * paging out pagecache only for non-anonymous mappings that correspond
315 	 * to the files the calling process could (if tried) open for writing;
316 	 * otherwise we'd be including shared non-exclusive mappings, which
317 	 * opens a side channel.
318 	 */
319 	return inode_owner_or_capable(&nop_mnt_idmap,
320 				      file_inode(vma->vm_file)) ||
321 	       file_permission(vma->vm_file, MAY_WRITE) == 0;
322 }
323 
324 static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
325 				unsigned long addr, unsigned long end,
326 				struct mm_walk *walk)
327 {
328 	struct madvise_walk_private *private = walk->private;
329 	struct mmu_gather *tlb = private->tlb;
330 	bool pageout = private->pageout;
331 	struct mm_struct *mm = tlb->mm;
332 	struct vm_area_struct *vma = walk->vma;
333 	pte_t *start_pte, *pte, ptent;
334 	spinlock_t *ptl;
335 	struct folio *folio = NULL;
336 	LIST_HEAD(folio_list);
337 	bool pageout_anon_only_filter;
338 	unsigned int batch_count = 0;
339 
340 	if (fatal_signal_pending(current))
341 		return -EINTR;
342 
343 	pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
344 					!can_do_file_pageout(vma);
345 
346 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
347 	if (pmd_trans_huge(*pmd)) {
348 		pmd_t orig_pmd;
349 		unsigned long next = pmd_addr_end(addr, end);
350 
351 		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
352 		ptl = pmd_trans_huge_lock(pmd, vma);
353 		if (!ptl)
354 			return 0;
355 
356 		orig_pmd = *pmd;
357 		if (is_huge_zero_pmd(orig_pmd))
358 			goto huge_unlock;
359 
360 		if (unlikely(!pmd_present(orig_pmd))) {
361 			VM_BUG_ON(thp_migration_supported() &&
362 					!is_pmd_migration_entry(orig_pmd));
363 			goto huge_unlock;
364 		}
365 
366 		folio = pfn_folio(pmd_pfn(orig_pmd));
367 
368 		/* Do not interfere with other mappings of this folio */
369 		if (folio_estimated_sharers(folio) != 1)
370 			goto huge_unlock;
371 
372 		if (pageout_anon_only_filter && !folio_test_anon(folio))
373 			goto huge_unlock;
374 
375 		if (next - addr != HPAGE_PMD_SIZE) {
376 			int err;
377 
378 			folio_get(folio);
379 			spin_unlock(ptl);
380 			folio_lock(folio);
381 			err = split_folio(folio);
382 			folio_unlock(folio);
383 			folio_put(folio);
384 			if (!err)
385 				goto regular_folio;
386 			return 0;
387 		}
388 
389 		if (pmd_young(orig_pmd)) {
390 			pmdp_invalidate(vma, addr, pmd);
391 			orig_pmd = pmd_mkold(orig_pmd);
392 
393 			set_pmd_at(mm, addr, pmd, orig_pmd);
394 			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
395 		}
396 
397 		folio_clear_referenced(folio);
398 		folio_test_clear_young(folio);
399 		if (folio_test_active(folio))
400 			folio_set_workingset(folio);
401 		if (pageout) {
402 			if (folio_isolate_lru(folio)) {
403 				if (folio_test_unevictable(folio))
404 					folio_putback_lru(folio);
405 				else
406 					list_add(&folio->lru, &folio_list);
407 			}
408 		} else
409 			folio_deactivate(folio);
410 huge_unlock:
411 		spin_unlock(ptl);
412 		if (pageout)
413 			reclaim_pages(&folio_list);
414 		return 0;
415 	}
416 
417 regular_folio:
418 #endif
419 	tlb_change_page_size(tlb, PAGE_SIZE);
420 restart:
421 	start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
422 	if (!start_pte)
423 		return 0;
424 	flush_tlb_batched_pending(mm);
425 	arch_enter_lazy_mmu_mode();
426 	for (; addr < end; pte++, addr += PAGE_SIZE) {
427 		ptent = ptep_get(pte);
428 
429 		if (++batch_count == SWAP_CLUSTER_MAX) {
430 			batch_count = 0;
431 			if (need_resched()) {
432 				pte_unmap_unlock(start_pte, ptl);
433 				cond_resched();
434 				goto restart;
435 			}
436 		}
437 
438 		if (pte_none(ptent))
439 			continue;
440 
441 		if (!pte_present(ptent))
442 			continue;
443 
444 		folio = vm_normal_folio(vma, addr, ptent);
445 		if (!folio || folio_is_zone_device(folio))
446 			continue;
447 
448 		/*
449 		 * Creating a THP page is expensive so split it only if we
450 		 * are sure it's worth. Split it if we are only owner.
451 		 */
452 		if (folio_test_large(folio)) {
453 			int err;
454 
455 			if (folio_estimated_sharers(folio) != 1)
456 				break;
457 			if (pageout_anon_only_filter && !folio_test_anon(folio))
458 				break;
459 			if (!folio_trylock(folio))
460 				break;
461 			folio_get(folio);
462 			arch_leave_lazy_mmu_mode();
463 			pte_unmap_unlock(start_pte, ptl);
464 			start_pte = NULL;
465 			err = split_folio(folio);
466 			folio_unlock(folio);
467 			folio_put(folio);
468 			if (err)
469 				break;
470 			start_pte = pte =
471 				pte_offset_map_lock(mm, pmd, addr, &ptl);
472 			if (!start_pte)
473 				break;
474 			arch_enter_lazy_mmu_mode();
475 			pte--;
476 			addr -= PAGE_SIZE;
477 			continue;
478 		}
479 
480 		/*
481 		 * Do not interfere with other mappings of this folio and
482 		 * non-LRU folio.
483 		 */
484 		if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
485 			continue;
486 
487 		if (pageout_anon_only_filter && !folio_test_anon(folio))
488 			continue;
489 
490 		VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
491 
492 		if (pte_young(ptent)) {
493 			ptent = ptep_get_and_clear_full(mm, addr, pte,
494 							tlb->fullmm);
495 			ptent = pte_mkold(ptent);
496 			set_pte_at(mm, addr, pte, ptent);
497 			tlb_remove_tlb_entry(tlb, pte, addr);
498 		}
499 
500 		/*
501 		 * We are deactivating a folio for accelerating reclaiming.
502 		 * VM couldn't reclaim the folio unless we clear PG_young.
503 		 * As a side effect, it makes confuse idle-page tracking
504 		 * because they will miss recent referenced history.
505 		 */
506 		folio_clear_referenced(folio);
507 		folio_test_clear_young(folio);
508 		if (folio_test_active(folio))
509 			folio_set_workingset(folio);
510 		if (pageout) {
511 			if (folio_isolate_lru(folio)) {
512 				if (folio_test_unevictable(folio))
513 					folio_putback_lru(folio);
514 				else
515 					list_add(&folio->lru, &folio_list);
516 			}
517 		} else
518 			folio_deactivate(folio);
519 	}
520 
521 	if (start_pte) {
522 		arch_leave_lazy_mmu_mode();
523 		pte_unmap_unlock(start_pte, ptl);
524 	}
525 	if (pageout)
526 		reclaim_pages(&folio_list);
527 	cond_resched();
528 
529 	return 0;
530 }
531 
532 static const struct mm_walk_ops cold_walk_ops = {
533 	.pmd_entry = madvise_cold_or_pageout_pte_range,
534 	.walk_lock = PGWALK_RDLOCK,
535 };
536 
537 static void madvise_cold_page_range(struct mmu_gather *tlb,
538 			     struct vm_area_struct *vma,
539 			     unsigned long addr, unsigned long end)
540 {
541 	struct madvise_walk_private walk_private = {
542 		.pageout = false,
543 		.tlb = tlb,
544 	};
545 
546 	tlb_start_vma(tlb, vma);
547 	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
548 	tlb_end_vma(tlb, vma);
549 }
550 
551 static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
552 {
553 	return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
554 }
555 
556 static long madvise_cold(struct vm_area_struct *vma,
557 			struct vm_area_struct **prev,
558 			unsigned long start_addr, unsigned long end_addr)
559 {
560 	struct mm_struct *mm = vma->vm_mm;
561 	struct mmu_gather tlb;
562 
563 	*prev = vma;
564 	if (!can_madv_lru_vma(vma))
565 		return -EINVAL;
566 
567 	lru_add_drain();
568 	tlb_gather_mmu(&tlb, mm);
569 	madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
570 	tlb_finish_mmu(&tlb);
571 
572 	return 0;
573 }
574 
575 static void madvise_pageout_page_range(struct mmu_gather *tlb,
576 			     struct vm_area_struct *vma,
577 			     unsigned long addr, unsigned long end)
578 {
579 	struct madvise_walk_private walk_private = {
580 		.pageout = true,
581 		.tlb = tlb,
582 	};
583 
584 	tlb_start_vma(tlb, vma);
585 	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
586 	tlb_end_vma(tlb, vma);
587 }
588 
589 static long madvise_pageout(struct vm_area_struct *vma,
590 			struct vm_area_struct **prev,
591 			unsigned long start_addr, unsigned long end_addr)
592 {
593 	struct mm_struct *mm = vma->vm_mm;
594 	struct mmu_gather tlb;
595 
596 	*prev = vma;
597 	if (!can_madv_lru_vma(vma))
598 		return -EINVAL;
599 
600 	/*
601 	 * If the VMA belongs to a private file mapping, there can be private
602 	 * dirty pages which can be paged out if even this process is neither
603 	 * owner nor write capable of the file. We allow private file mappings
604 	 * further to pageout dirty anon pages.
605 	 */
606 	if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
607 				(vma->vm_flags & VM_MAYSHARE)))
608 		return 0;
609 
610 	lru_add_drain();
611 	tlb_gather_mmu(&tlb, mm);
612 	madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
613 	tlb_finish_mmu(&tlb);
614 
615 	return 0;
616 }
617 
618 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
619 				unsigned long end, struct mm_walk *walk)
620 
621 {
622 	struct mmu_gather *tlb = walk->private;
623 	struct mm_struct *mm = tlb->mm;
624 	struct vm_area_struct *vma = walk->vma;
625 	spinlock_t *ptl;
626 	pte_t *start_pte, *pte, ptent;
627 	struct folio *folio;
628 	int nr_swap = 0;
629 	unsigned long next;
630 
631 	next = pmd_addr_end(addr, end);
632 	if (pmd_trans_huge(*pmd))
633 		if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
634 			return 0;
635 
636 	tlb_change_page_size(tlb, PAGE_SIZE);
637 	start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
638 	if (!start_pte)
639 		return 0;
640 	flush_tlb_batched_pending(mm);
641 	arch_enter_lazy_mmu_mode();
642 	for (; addr != end; pte++, addr += PAGE_SIZE) {
643 		ptent = ptep_get(pte);
644 
645 		if (pte_none(ptent))
646 			continue;
647 		/*
648 		 * If the pte has swp_entry, just clear page table to
649 		 * prevent swap-in which is more expensive rather than
650 		 * (page allocation + zeroing).
651 		 */
652 		if (!pte_present(ptent)) {
653 			swp_entry_t entry;
654 
655 			entry = pte_to_swp_entry(ptent);
656 			if (!non_swap_entry(entry)) {
657 				nr_swap--;
658 				free_swap_and_cache(entry);
659 				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
660 			} else if (is_hwpoison_entry(entry) ||
661 				   is_poisoned_swp_entry(entry)) {
662 				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
663 			}
664 			continue;
665 		}
666 
667 		folio = vm_normal_folio(vma, addr, ptent);
668 		if (!folio || folio_is_zone_device(folio))
669 			continue;
670 
671 		/*
672 		 * If pmd isn't transhuge but the folio is large and
673 		 * is owned by only this process, split it and
674 		 * deactivate all pages.
675 		 */
676 		if (folio_test_large(folio)) {
677 			int err;
678 
679 			if (folio_estimated_sharers(folio) != 1)
680 				break;
681 			if (!folio_trylock(folio))
682 				break;
683 			folio_get(folio);
684 			arch_leave_lazy_mmu_mode();
685 			pte_unmap_unlock(start_pte, ptl);
686 			start_pte = NULL;
687 			err = split_folio(folio);
688 			folio_unlock(folio);
689 			folio_put(folio);
690 			if (err)
691 				break;
692 			start_pte = pte =
693 				pte_offset_map_lock(mm, pmd, addr, &ptl);
694 			if (!start_pte)
695 				break;
696 			arch_enter_lazy_mmu_mode();
697 			pte--;
698 			addr -= PAGE_SIZE;
699 			continue;
700 		}
701 
702 		if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
703 			if (!folio_trylock(folio))
704 				continue;
705 			/*
706 			 * If folio is shared with others, we mustn't clear
707 			 * the folio's dirty flag.
708 			 */
709 			if (folio_mapcount(folio) != 1) {
710 				folio_unlock(folio);
711 				continue;
712 			}
713 
714 			if (folio_test_swapcache(folio) &&
715 			    !folio_free_swap(folio)) {
716 				folio_unlock(folio);
717 				continue;
718 			}
719 
720 			folio_clear_dirty(folio);
721 			folio_unlock(folio);
722 		}
723 
724 		if (pte_young(ptent) || pte_dirty(ptent)) {
725 			/*
726 			 * Some of architecture(ex, PPC) don't update TLB
727 			 * with set_pte_at and tlb_remove_tlb_entry so for
728 			 * the portability, remap the pte with old|clean
729 			 * after pte clearing.
730 			 */
731 			ptent = ptep_get_and_clear_full(mm, addr, pte,
732 							tlb->fullmm);
733 
734 			ptent = pte_mkold(ptent);
735 			ptent = pte_mkclean(ptent);
736 			set_pte_at(mm, addr, pte, ptent);
737 			tlb_remove_tlb_entry(tlb, pte, addr);
738 		}
739 		folio_mark_lazyfree(folio);
740 	}
741 
742 	if (nr_swap)
743 		add_mm_counter(mm, MM_SWAPENTS, nr_swap);
744 	if (start_pte) {
745 		arch_leave_lazy_mmu_mode();
746 		pte_unmap_unlock(start_pte, ptl);
747 	}
748 	cond_resched();
749 
750 	return 0;
751 }
752 
753 static const struct mm_walk_ops madvise_free_walk_ops = {
754 	.pmd_entry		= madvise_free_pte_range,
755 	.walk_lock		= PGWALK_RDLOCK,
756 };
757 
758 static int madvise_free_single_vma(struct vm_area_struct *vma,
759 			unsigned long start_addr, unsigned long end_addr)
760 {
761 	struct mm_struct *mm = vma->vm_mm;
762 	struct mmu_notifier_range range;
763 	struct mmu_gather tlb;
764 
765 	/* MADV_FREE works for only anon vma at the moment */
766 	if (!vma_is_anonymous(vma))
767 		return -EINVAL;
768 
769 	range.start = max(vma->vm_start, start_addr);
770 	if (range.start >= vma->vm_end)
771 		return -EINVAL;
772 	range.end = min(vma->vm_end, end_addr);
773 	if (range.end <= vma->vm_start)
774 		return -EINVAL;
775 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
776 				range.start, range.end);
777 
778 	lru_add_drain();
779 	tlb_gather_mmu(&tlb, mm);
780 	update_hiwater_rss(mm);
781 
782 	mmu_notifier_invalidate_range_start(&range);
783 	tlb_start_vma(&tlb, vma);
784 	walk_page_range(vma->vm_mm, range.start, range.end,
785 			&madvise_free_walk_ops, &tlb);
786 	tlb_end_vma(&tlb, vma);
787 	mmu_notifier_invalidate_range_end(&range);
788 	tlb_finish_mmu(&tlb);
789 
790 	return 0;
791 }
792 
793 /*
794  * Application no longer needs these pages.  If the pages are dirty,
795  * it's OK to just throw them away.  The app will be more careful about
796  * data it wants to keep.  Be sure to free swap resources too.  The
797  * zap_page_range_single call sets things up for shrink_active_list to actually
798  * free these pages later if no one else has touched them in the meantime,
799  * although we could add these pages to a global reuse list for
800  * shrink_active_list to pick up before reclaiming other pages.
801  *
802  * NB: This interface discards data rather than pushes it out to swap,
803  * as some implementations do.  This has performance implications for
804  * applications like large transactional databases which want to discard
805  * pages in anonymous maps after committing to backing store the data
806  * that was kept in them.  There is no reason to write this data out to
807  * the swap area if the application is discarding it.
808  *
809  * An interface that causes the system to free clean pages and flush
810  * dirty pages is already available as msync(MS_INVALIDATE).
811  */
812 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
813 					unsigned long start, unsigned long end)
814 {
815 	zap_page_range_single(vma, start, end - start, NULL);
816 	return 0;
817 }
818 
819 static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
820 					    unsigned long start,
821 					    unsigned long *end,
822 					    int behavior)
823 {
824 	if (!is_vm_hugetlb_page(vma)) {
825 		unsigned int forbidden = VM_PFNMAP;
826 
827 		if (behavior != MADV_DONTNEED_LOCKED)
828 			forbidden |= VM_LOCKED;
829 
830 		return !(vma->vm_flags & forbidden);
831 	}
832 
833 	if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
834 		return false;
835 	if (start & ~huge_page_mask(hstate_vma(vma)))
836 		return false;
837 
838 	/*
839 	 * Madvise callers expect the length to be rounded up to PAGE_SIZE
840 	 * boundaries, and may be unaware that this VMA uses huge pages.
841 	 * Avoid unexpected data loss by rounding down the number of
842 	 * huge pages freed.
843 	 */
844 	*end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
845 
846 	return true;
847 }
848 
849 static long madvise_dontneed_free(struct vm_area_struct *vma,
850 				  struct vm_area_struct **prev,
851 				  unsigned long start, unsigned long end,
852 				  int behavior)
853 {
854 	struct mm_struct *mm = vma->vm_mm;
855 
856 	*prev = vma;
857 	if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
858 		return -EINVAL;
859 
860 	if (start == end)
861 		return 0;
862 
863 	if (!userfaultfd_remove(vma, start, end)) {
864 		*prev = NULL; /* mmap_lock has been dropped, prev is stale */
865 
866 		mmap_read_lock(mm);
867 		vma = vma_lookup(mm, start);
868 		if (!vma)
869 			return -ENOMEM;
870 		/*
871 		 * Potential end adjustment for hugetlb vma is OK as
872 		 * the check below keeps end within vma.
873 		 */
874 		if (!madvise_dontneed_free_valid_vma(vma, start, &end,
875 						     behavior))
876 			return -EINVAL;
877 		if (end > vma->vm_end) {
878 			/*
879 			 * Don't fail if end > vma->vm_end. If the old
880 			 * vma was split while the mmap_lock was
881 			 * released the effect of the concurrent
882 			 * operation may not cause madvise() to
883 			 * have an undefined result. There may be an
884 			 * adjacent next vma that we'll walk
885 			 * next. userfaultfd_remove() will generate an
886 			 * UFFD_EVENT_REMOVE repetition on the
887 			 * end-vma->vm_end range, but the manager can
888 			 * handle a repetition fine.
889 			 */
890 			end = vma->vm_end;
891 		}
892 		VM_WARN_ON(start >= end);
893 	}
894 
895 	if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
896 		return madvise_dontneed_single_vma(vma, start, end);
897 	else if (behavior == MADV_FREE)
898 		return madvise_free_single_vma(vma, start, end);
899 	else
900 		return -EINVAL;
901 }
902 
903 static long madvise_populate(struct vm_area_struct *vma,
904 			     struct vm_area_struct **prev,
905 			     unsigned long start, unsigned long end,
906 			     int behavior)
907 {
908 	const bool write = behavior == MADV_POPULATE_WRITE;
909 	struct mm_struct *mm = vma->vm_mm;
910 	unsigned long tmp_end;
911 	int locked = 1;
912 	long pages;
913 
914 	*prev = vma;
915 
916 	while (start < end) {
917 		/*
918 		 * We might have temporarily dropped the lock. For example,
919 		 * our VMA might have been split.
920 		 */
921 		if (!vma || start >= vma->vm_end) {
922 			vma = vma_lookup(mm, start);
923 			if (!vma)
924 				return -ENOMEM;
925 		}
926 
927 		tmp_end = min_t(unsigned long, end, vma->vm_end);
928 		/* Populate (prefault) page tables readable/writable. */
929 		pages = faultin_vma_page_range(vma, start, tmp_end, write,
930 					       &locked);
931 		if (!locked) {
932 			mmap_read_lock(mm);
933 			locked = 1;
934 			*prev = NULL;
935 			vma = NULL;
936 		}
937 		if (pages < 0) {
938 			switch (pages) {
939 			case -EINTR:
940 				return -EINTR;
941 			case -EINVAL: /* Incompatible mappings / permissions. */
942 				return -EINVAL;
943 			case -EHWPOISON:
944 				return -EHWPOISON;
945 			case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
946 				return -EFAULT;
947 			default:
948 				pr_warn_once("%s: unhandled return value: %ld\n",
949 					     __func__, pages);
950 				fallthrough;
951 			case -ENOMEM:
952 				return -ENOMEM;
953 			}
954 		}
955 		start += pages * PAGE_SIZE;
956 	}
957 	return 0;
958 }
959 
960 /*
961  * Application wants to free up the pages and associated backing store.
962  * This is effectively punching a hole into the middle of a file.
963  */
964 static long madvise_remove(struct vm_area_struct *vma,
965 				struct vm_area_struct **prev,
966 				unsigned long start, unsigned long end)
967 {
968 	loff_t offset;
969 	int error;
970 	struct file *f;
971 	struct mm_struct *mm = vma->vm_mm;
972 
973 	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
974 
975 	if (vma->vm_flags & VM_LOCKED)
976 		return -EINVAL;
977 
978 	f = vma->vm_file;
979 
980 	if (!f || !f->f_mapping || !f->f_mapping->host) {
981 			return -EINVAL;
982 	}
983 
984 	if (!vma_is_shared_maywrite(vma))
985 		return -EACCES;
986 
987 	offset = (loff_t)(start - vma->vm_start)
988 			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
989 
990 	/*
991 	 * Filesystem's fallocate may need to take i_rwsem.  We need to
992 	 * explicitly grab a reference because the vma (and hence the
993 	 * vma's reference to the file) can go away as soon as we drop
994 	 * mmap_lock.
995 	 */
996 	get_file(f);
997 	if (userfaultfd_remove(vma, start, end)) {
998 		/* mmap_lock was not released by userfaultfd_remove() */
999 		mmap_read_unlock(mm);
1000 	}
1001 	error = vfs_fallocate(f,
1002 				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1003 				offset, end - start);
1004 	fput(f);
1005 	mmap_read_lock(mm);
1006 	return error;
1007 }
1008 
1009 /*
1010  * Apply an madvise behavior to a region of a vma.  madvise_update_vma
1011  * will handle splitting a vm area into separate areas, each area with its own
1012  * behavior.
1013  */
1014 static int madvise_vma_behavior(struct vm_area_struct *vma,
1015 				struct vm_area_struct **prev,
1016 				unsigned long start, unsigned long end,
1017 				unsigned long behavior)
1018 {
1019 	int error;
1020 	struct anon_vma_name *anon_name;
1021 	unsigned long new_flags = vma->vm_flags;
1022 
1023 	switch (behavior) {
1024 	case MADV_REMOVE:
1025 		return madvise_remove(vma, prev, start, end);
1026 	case MADV_WILLNEED:
1027 		return madvise_willneed(vma, prev, start, end);
1028 	case MADV_COLD:
1029 		return madvise_cold(vma, prev, start, end);
1030 	case MADV_PAGEOUT:
1031 		return madvise_pageout(vma, prev, start, end);
1032 	case MADV_FREE:
1033 	case MADV_DONTNEED:
1034 	case MADV_DONTNEED_LOCKED:
1035 		return madvise_dontneed_free(vma, prev, start, end, behavior);
1036 	case MADV_POPULATE_READ:
1037 	case MADV_POPULATE_WRITE:
1038 		return madvise_populate(vma, prev, start, end, behavior);
1039 	case MADV_NORMAL:
1040 		new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1041 		break;
1042 	case MADV_SEQUENTIAL:
1043 		new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1044 		break;
1045 	case MADV_RANDOM:
1046 		new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1047 		break;
1048 	case MADV_DONTFORK:
1049 		new_flags |= VM_DONTCOPY;
1050 		break;
1051 	case MADV_DOFORK:
1052 		if (vma->vm_flags & VM_IO)
1053 			return -EINVAL;
1054 		new_flags &= ~VM_DONTCOPY;
1055 		break;
1056 	case MADV_WIPEONFORK:
1057 		/* MADV_WIPEONFORK is only supported on anonymous memory. */
1058 		if (vma->vm_file || vma->vm_flags & VM_SHARED)
1059 			return -EINVAL;
1060 		new_flags |= VM_WIPEONFORK;
1061 		break;
1062 	case MADV_KEEPONFORK:
1063 		new_flags &= ~VM_WIPEONFORK;
1064 		break;
1065 	case MADV_DONTDUMP:
1066 		new_flags |= VM_DONTDUMP;
1067 		break;
1068 	case MADV_DODUMP:
1069 		if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1070 			return -EINVAL;
1071 		new_flags &= ~VM_DONTDUMP;
1072 		break;
1073 	case MADV_MERGEABLE:
1074 	case MADV_UNMERGEABLE:
1075 		error = ksm_madvise(vma, start, end, behavior, &new_flags);
1076 		if (error)
1077 			goto out;
1078 		break;
1079 	case MADV_HUGEPAGE:
1080 	case MADV_NOHUGEPAGE:
1081 		error = hugepage_madvise(vma, &new_flags, behavior);
1082 		if (error)
1083 			goto out;
1084 		break;
1085 	case MADV_COLLAPSE:
1086 		return madvise_collapse(vma, prev, start, end);
1087 	}
1088 
1089 	anon_name = anon_vma_name(vma);
1090 	anon_vma_name_get(anon_name);
1091 	error = madvise_update_vma(vma, prev, start, end, new_flags,
1092 				   anon_name);
1093 	anon_vma_name_put(anon_name);
1094 
1095 out:
1096 	/*
1097 	 * madvise() returns EAGAIN if kernel resources, such as
1098 	 * slab, are temporarily unavailable.
1099 	 */
1100 	if (error == -ENOMEM)
1101 		error = -EAGAIN;
1102 	return error;
1103 }
1104 
1105 #ifdef CONFIG_MEMORY_FAILURE
1106 /*
1107  * Error injection support for memory error handling.
1108  */
1109 static int madvise_inject_error(int behavior,
1110 		unsigned long start, unsigned long end)
1111 {
1112 	unsigned long size;
1113 
1114 	if (!capable(CAP_SYS_ADMIN))
1115 		return -EPERM;
1116 
1117 
1118 	for (; start < end; start += size) {
1119 		unsigned long pfn;
1120 		struct page *page;
1121 		int ret;
1122 
1123 		ret = get_user_pages_fast(start, 1, 0, &page);
1124 		if (ret != 1)
1125 			return ret;
1126 		pfn = page_to_pfn(page);
1127 
1128 		/*
1129 		 * When soft offlining hugepages, after migrating the page
1130 		 * we dissolve it, therefore in the second loop "page" will
1131 		 * no longer be a compound page.
1132 		 */
1133 		size = page_size(compound_head(page));
1134 
1135 		if (behavior == MADV_SOFT_OFFLINE) {
1136 			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1137 				 pfn, start);
1138 			ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
1139 		} else {
1140 			pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1141 				 pfn, start);
1142 			ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
1143 			if (ret == -EOPNOTSUPP)
1144 				ret = 0;
1145 		}
1146 
1147 		if (ret)
1148 			return ret;
1149 	}
1150 
1151 	return 0;
1152 }
1153 #endif
1154 
1155 static bool
1156 madvise_behavior_valid(int behavior)
1157 {
1158 	switch (behavior) {
1159 	case MADV_DOFORK:
1160 	case MADV_DONTFORK:
1161 	case MADV_NORMAL:
1162 	case MADV_SEQUENTIAL:
1163 	case MADV_RANDOM:
1164 	case MADV_REMOVE:
1165 	case MADV_WILLNEED:
1166 	case MADV_DONTNEED:
1167 	case MADV_DONTNEED_LOCKED:
1168 	case MADV_FREE:
1169 	case MADV_COLD:
1170 	case MADV_PAGEOUT:
1171 	case MADV_POPULATE_READ:
1172 	case MADV_POPULATE_WRITE:
1173 #ifdef CONFIG_KSM
1174 	case MADV_MERGEABLE:
1175 	case MADV_UNMERGEABLE:
1176 #endif
1177 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1178 	case MADV_HUGEPAGE:
1179 	case MADV_NOHUGEPAGE:
1180 	case MADV_COLLAPSE:
1181 #endif
1182 	case MADV_DONTDUMP:
1183 	case MADV_DODUMP:
1184 	case MADV_WIPEONFORK:
1185 	case MADV_KEEPONFORK:
1186 #ifdef CONFIG_MEMORY_FAILURE
1187 	case MADV_SOFT_OFFLINE:
1188 	case MADV_HWPOISON:
1189 #endif
1190 		return true;
1191 
1192 	default:
1193 		return false;
1194 	}
1195 }
1196 
1197 static bool process_madvise_behavior_valid(int behavior)
1198 {
1199 	switch (behavior) {
1200 	case MADV_COLD:
1201 	case MADV_PAGEOUT:
1202 	case MADV_WILLNEED:
1203 	case MADV_COLLAPSE:
1204 		return true;
1205 	default:
1206 		return false;
1207 	}
1208 }
1209 
1210 /*
1211  * Walk the vmas in range [start,end), and call the visit function on each one.
1212  * The visit function will get start and end parameters that cover the overlap
1213  * between the current vma and the original range.  Any unmapped regions in the
1214  * original range will result in this function returning -ENOMEM while still
1215  * calling the visit function on all of the existing vmas in the range.
1216  * Must be called with the mmap_lock held for reading or writing.
1217  */
1218 static
1219 int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1220 		      unsigned long end, unsigned long arg,
1221 		      int (*visit)(struct vm_area_struct *vma,
1222 				   struct vm_area_struct **prev, unsigned long start,
1223 				   unsigned long end, unsigned long arg))
1224 {
1225 	struct vm_area_struct *vma;
1226 	struct vm_area_struct *prev;
1227 	unsigned long tmp;
1228 	int unmapped_error = 0;
1229 
1230 	/*
1231 	 * If the interval [start,end) covers some unmapped address
1232 	 * ranges, just ignore them, but return -ENOMEM at the end.
1233 	 * - different from the way of handling in mlock etc.
1234 	 */
1235 	vma = find_vma_prev(mm, start, &prev);
1236 	if (vma && start > vma->vm_start)
1237 		prev = vma;
1238 
1239 	for (;;) {
1240 		int error;
1241 
1242 		/* Still start < end. */
1243 		if (!vma)
1244 			return -ENOMEM;
1245 
1246 		/* Here start < (end|vma->vm_end). */
1247 		if (start < vma->vm_start) {
1248 			unmapped_error = -ENOMEM;
1249 			start = vma->vm_start;
1250 			if (start >= end)
1251 				break;
1252 		}
1253 
1254 		/* Here vma->vm_start <= start < (end|vma->vm_end) */
1255 		tmp = vma->vm_end;
1256 		if (end < tmp)
1257 			tmp = end;
1258 
1259 		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1260 		error = visit(vma, &prev, start, tmp, arg);
1261 		if (error)
1262 			return error;
1263 		start = tmp;
1264 		if (prev && start < prev->vm_end)
1265 			start = prev->vm_end;
1266 		if (start >= end)
1267 			break;
1268 		if (prev)
1269 			vma = find_vma(mm, prev->vm_end);
1270 		else	/* madvise_remove dropped mmap_lock */
1271 			vma = find_vma(mm, start);
1272 	}
1273 
1274 	return unmapped_error;
1275 }
1276 
1277 #ifdef CONFIG_ANON_VMA_NAME
1278 static int madvise_vma_anon_name(struct vm_area_struct *vma,
1279 				 struct vm_area_struct **prev,
1280 				 unsigned long start, unsigned long end,
1281 				 unsigned long anon_name)
1282 {
1283 	int error;
1284 
1285 	/* Only anonymous mappings can be named */
1286 	if (vma->vm_file && !vma_is_anon_shmem(vma))
1287 		return -EBADF;
1288 
1289 	error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
1290 				   (struct anon_vma_name *)anon_name);
1291 
1292 	/*
1293 	 * madvise() returns EAGAIN if kernel resources, such as
1294 	 * slab, are temporarily unavailable.
1295 	 */
1296 	if (error == -ENOMEM)
1297 		error = -EAGAIN;
1298 	return error;
1299 }
1300 
1301 int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1302 			  unsigned long len_in, struct anon_vma_name *anon_name)
1303 {
1304 	unsigned long end;
1305 	unsigned long len;
1306 
1307 	if (start & ~PAGE_MASK)
1308 		return -EINVAL;
1309 	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1310 
1311 	/* Check to see whether len was rounded up from small -ve to zero */
1312 	if (len_in && !len)
1313 		return -EINVAL;
1314 
1315 	end = start + len;
1316 	if (end < start)
1317 		return -EINVAL;
1318 
1319 	if (end == start)
1320 		return 0;
1321 
1322 	return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
1323 				 madvise_vma_anon_name);
1324 }
1325 #endif /* CONFIG_ANON_VMA_NAME */
1326 /*
1327  * The madvise(2) system call.
1328  *
1329  * Applications can use madvise() to advise the kernel how it should
1330  * handle paging I/O in this VM area.  The idea is to help the kernel
1331  * use appropriate read-ahead and caching techniques.  The information
1332  * provided is advisory only, and can be safely disregarded by the
1333  * kernel without affecting the correct operation of the application.
1334  *
1335  * behavior values:
1336  *  MADV_NORMAL - the default behavior is to read clusters.  This
1337  *		results in some read-ahead and read-behind.
1338  *  MADV_RANDOM - the system should read the minimum amount of data
1339  *		on any access, since it is unlikely that the appli-
1340  *		cation will need more than what it asks for.
1341  *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
1342  *		once, so they can be aggressively read ahead, and
1343  *		can be freed soon after they are accessed.
1344  *  MADV_WILLNEED - the application is notifying the system to read
1345  *		some pages ahead.
1346  *  MADV_DONTNEED - the application is finished with the given range,
1347  *		so the kernel can free resources associated with it.
1348  *  MADV_FREE - the application marks pages in the given range as lazy free,
1349  *		where actual purges are postponed until memory pressure happens.
1350  *  MADV_REMOVE - the application wants to free up the given range of
1351  *		pages and associated backing store.
1352  *  MADV_DONTFORK - omit this area from child's address space when forking:
1353  *		typically, to avoid COWing pages pinned by get_user_pages().
1354  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1355  *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
1356  *              range after a fork.
1357  *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1358  *  MADV_HWPOISON - trigger memory error handler as if the given memory range
1359  *		were corrupted by unrecoverable hardware memory failure.
1360  *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1361  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1362  *		this area with pages of identical content from other such areas.
1363  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1364  *  MADV_HUGEPAGE - the application wants to back the given range by transparent
1365  *		huge pages in the future. Existing pages might be coalesced and
1366  *		new pages might be allocated as THP.
1367  *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1368  *		transparent huge pages so the existing pages will not be
1369  *		coalesced into THP and new pages will not be allocated as THP.
1370  *  MADV_COLLAPSE - synchronously coalesce pages into new THP.
1371  *  MADV_DONTDUMP - the application wants to prevent pages in the given range
1372  *		from being included in its core dump.
1373  *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1374  *  MADV_COLD - the application is not expected to use this memory soon,
1375  *		deactivate pages in this range so that they can be reclaimed
1376  *		easily if memory pressure happens.
1377  *  MADV_PAGEOUT - the application is not expected to use this memory soon,
1378  *		page out the pages in this range immediately.
1379  *  MADV_POPULATE_READ - populate (prefault) page tables readable by
1380  *		triggering read faults if required
1381  *  MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1382  *		triggering write faults if required
1383  *
1384  * return values:
1385  *  zero    - success
1386  *  -EINVAL - start + len < 0, start is not page-aligned,
1387  *		"behavior" is not a valid value, or application
1388  *		is attempting to release locked or shared pages,
1389  *		or the specified address range includes file, Huge TLB,
1390  *		MAP_SHARED or VMPFNMAP range.
1391  *  -ENOMEM - addresses in the specified range are not currently
1392  *		mapped, or are outside the AS of the process.
1393  *  -EIO    - an I/O error occurred while paging in data.
1394  *  -EBADF  - map exists, but area maps something that isn't a file.
1395  *  -EAGAIN - a kernel resource was temporarily unavailable.
1396  */
1397 int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1398 {
1399 	unsigned long end;
1400 	int error;
1401 	int write;
1402 	size_t len;
1403 	struct blk_plug plug;
1404 
1405 	if (!madvise_behavior_valid(behavior))
1406 		return -EINVAL;
1407 
1408 	if (!PAGE_ALIGNED(start))
1409 		return -EINVAL;
1410 	len = PAGE_ALIGN(len_in);
1411 
1412 	/* Check to see whether len was rounded up from small -ve to zero */
1413 	if (len_in && !len)
1414 		return -EINVAL;
1415 
1416 	end = start + len;
1417 	if (end < start)
1418 		return -EINVAL;
1419 
1420 	if (end == start)
1421 		return 0;
1422 
1423 #ifdef CONFIG_MEMORY_FAILURE
1424 	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1425 		return madvise_inject_error(behavior, start, start + len_in);
1426 #endif
1427 
1428 	write = madvise_need_mmap_write(behavior);
1429 	if (write) {
1430 		if (mmap_write_lock_killable(mm))
1431 			return -EINTR;
1432 	} else {
1433 		mmap_read_lock(mm);
1434 	}
1435 
1436 	start = untagged_addr_remote(mm, start);
1437 	end = start + len;
1438 
1439 	blk_start_plug(&plug);
1440 	error = madvise_walk_vmas(mm, start, end, behavior,
1441 			madvise_vma_behavior);
1442 	blk_finish_plug(&plug);
1443 	if (write)
1444 		mmap_write_unlock(mm);
1445 	else
1446 		mmap_read_unlock(mm);
1447 
1448 	return error;
1449 }
1450 
1451 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1452 {
1453 	return do_madvise(current->mm, start, len_in, behavior);
1454 }
1455 
1456 SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1457 		size_t, vlen, int, behavior, unsigned int, flags)
1458 {
1459 	ssize_t ret;
1460 	struct iovec iovstack[UIO_FASTIOV];
1461 	struct iovec *iov = iovstack;
1462 	struct iov_iter iter;
1463 	struct task_struct *task;
1464 	struct mm_struct *mm;
1465 	size_t total_len;
1466 	unsigned int f_flags;
1467 
1468 	if (flags != 0) {
1469 		ret = -EINVAL;
1470 		goto out;
1471 	}
1472 
1473 	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1474 	if (ret < 0)
1475 		goto out;
1476 
1477 	task = pidfd_get_task(pidfd, &f_flags);
1478 	if (IS_ERR(task)) {
1479 		ret = PTR_ERR(task);
1480 		goto free_iov;
1481 	}
1482 
1483 	if (!process_madvise_behavior_valid(behavior)) {
1484 		ret = -EINVAL;
1485 		goto release_task;
1486 	}
1487 
1488 	/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1489 	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1490 	if (IS_ERR_OR_NULL(mm)) {
1491 		ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1492 		goto release_task;
1493 	}
1494 
1495 	/*
1496 	 * Require CAP_SYS_NICE for influencing process performance. Note that
1497 	 * only non-destructive hints are currently supported.
1498 	 */
1499 	if (!capable(CAP_SYS_NICE)) {
1500 		ret = -EPERM;
1501 		goto release_mm;
1502 	}
1503 
1504 	total_len = iov_iter_count(&iter);
1505 
1506 	while (iov_iter_count(&iter)) {
1507 		ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
1508 					iter_iov_len(&iter), behavior);
1509 		if (ret < 0)
1510 			break;
1511 		iov_iter_advance(&iter, iter_iov_len(&iter));
1512 	}
1513 
1514 	ret = (total_len - iov_iter_count(&iter)) ? : ret;
1515 
1516 release_mm:
1517 	mmput(mm);
1518 release_task:
1519 	put_task_struct(task);
1520 free_iov:
1521 	kfree(iov);
1522 out:
1523 	return ret;
1524 }
1525