xref: /linux/include/linux/swap.h (revision 592329e5e94e26080f4815c6cc6cd0f487a91064)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SWAP_H
3 #define _LINUX_SWAP_H
4 
5 #include <linux/spinlock.h>
6 #include <linux/linkage.h>
7 #include <linux/mmzone.h>
8 #include <linux/list.h>
9 #include <linux/memcontrol.h>
10 #include <linux/sched.h>
11 #include <linux/node.h>
12 #include <linux/fs.h>
13 #include <linux/pagemap.h>
14 #include <linux/atomic.h>
15 #include <linux/page-flags.h>
16 #include <uapi/linux/mempolicy.h>
17 #include <asm/page.h>
18 
19 struct notifier_block;
20 
21 struct bio;
22 
23 struct pagevec;
24 
25 #define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
26 #define SWAP_FLAG_PRIO_MASK	0x7fff
27 #define SWAP_FLAG_PRIO_SHIFT	0
28 #define SWAP_FLAG_DISCARD	0x10000 /* enable discard for swap */
29 #define SWAP_FLAG_DISCARD_ONCE	0x20000 /* discard swap area at swapon-time */
30 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
31 
32 #define SWAP_FLAGS_VALID	(SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
33 				 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
34 				 SWAP_FLAG_DISCARD_PAGES)
35 #define SWAP_BATCH 64
36 
current_is_kswapd(void)37 static inline int current_is_kswapd(void)
38 {
39 	return current->flags & PF_KSWAPD;
40 }
41 
42 /*
43  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
44  * be swapped to.  The swap type and the offset into that swap type are
45  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
46  * for the type means that the maximum number of swapcache pages is 27 bits
47  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
48  * the type/offset into the pte as 5/27 as well.
49  */
50 #define MAX_SWAPFILES_SHIFT	5
51 
52 /*
53  * Use some of the swap files numbers for other purposes. This
54  * is a convenient way to hook into the VM to trigger special
55  * actions on faults.
56  */
57 
58 /*
59  * PTE markers are used to persist information onto PTEs that otherwise
60  * should be a none pte.  As its name "PTE" hints, it should only be
61  * applied to the leaves of pgtables.
62  */
63 #define SWP_PTE_MARKER_NUM 1
64 #define SWP_PTE_MARKER     (MAX_SWAPFILES + SWP_HWPOISON_NUM + \
65 			    SWP_MIGRATION_NUM + SWP_DEVICE_NUM)
66 
67 /*
68  * Unaddressable device memory support. See include/linux/hmm.h and
69  * Documentation/mm/hmm.rst. Short description is we need struct pages for
70  * device memory that is unaddressable (inaccessible) by CPU, so that we can
71  * migrate part of a process memory to device memory.
72  *
73  * When a page is migrated from CPU to device, we set the CPU page table entry
74  * to a special SWP_DEVICE_{READ|WRITE} entry.
75  *
76  * When a page is mapped by the device for exclusive access we set the CPU page
77  * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
78  */
79 #ifdef CONFIG_DEVICE_PRIVATE
80 #define SWP_DEVICE_NUM 4
81 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
82 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
83 #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
84 #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
85 #else
86 #define SWP_DEVICE_NUM 0
87 #endif
88 
89 /*
90  * Page migration support.
91  *
92  * SWP_MIGRATION_READ_EXCLUSIVE is only applicable to anonymous pages and
93  * indicates that the referenced (part of) an anonymous page is exclusive to
94  * a single process. For SWP_MIGRATION_WRITE, that information is implicit:
95  * (part of) an anonymous page that are mapped writable are exclusive to a
96  * single process.
97  */
98 #ifdef CONFIG_MIGRATION
99 #define SWP_MIGRATION_NUM 3
100 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
101 #define SWP_MIGRATION_READ_EXCLUSIVE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
102 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 2)
103 #else
104 #define SWP_MIGRATION_NUM 0
105 #endif
106 
107 /*
108  * Handling of hardware poisoned pages with memory corruption.
109  */
110 #ifdef CONFIG_MEMORY_FAILURE
111 #define SWP_HWPOISON_NUM 1
112 #define SWP_HWPOISON		MAX_SWAPFILES
113 #else
114 #define SWP_HWPOISON_NUM 0
115 #endif
116 
117 #define MAX_SWAPFILES \
118 	((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
119 	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \
120 	SWP_PTE_MARKER_NUM)
121 
122 /*
123  * Magic header for a swap area. The first part of the union is
124  * what the swap magic looks like for the old (limited to 128MB)
125  * swap area format, the second part of the union adds - in the
126  * old reserved area - some extra information. Note that the first
127  * kilobyte is reserved for boot loader or disk label stuff...
128  *
129  * Having the magic at the end of the PAGE_SIZE makes detecting swap
130  * areas somewhat tricky on machines that support multiple page sizes.
131  * For 2.5 we'll probably want to move the magic to just beyond the
132  * bootbits...
133  */
134 union swap_header {
135 	struct {
136 		char reserved[PAGE_SIZE - 10];
137 		char magic[10];			/* SWAP-SPACE or SWAPSPACE2 */
138 	} magic;
139 	struct {
140 		char		bootbits[1024];	/* Space for disklabel etc. */
141 		__u32		version;
142 		__u32		last_page;
143 		__u32		nr_badpages;
144 		unsigned char	sws_uuid[16];
145 		unsigned char	sws_volume[16];
146 		__u32		padding[117];
147 		__u32		badpages[1];
148 	} info;
149 };
150 
151 /*
152  * current->reclaim_state points to one of these when a task is running
153  * memory reclaim
154  */
155 struct reclaim_state {
156 	/* pages reclaimed outside of LRU-based reclaim */
157 	unsigned long reclaimed;
158 #ifdef CONFIG_LRU_GEN
159 	/* per-thread mm walk data */
160 	struct lru_gen_mm_walk *mm_walk;
161 #endif
162 };
163 
164 /*
165  * mm_account_reclaimed_pages(): account reclaimed pages outside of LRU-based
166  * reclaim
167  * @pages: number of pages reclaimed
168  *
169  * If the current process is undergoing a reclaim operation, increment the
170  * number of reclaimed pages by @pages.
171  */
mm_account_reclaimed_pages(unsigned long pages)172 static inline void mm_account_reclaimed_pages(unsigned long pages)
173 {
174 	if (current->reclaim_state)
175 		current->reclaim_state->reclaimed += pages;
176 }
177 
178 #ifdef __KERNEL__
179 
180 struct address_space;
181 struct sysinfo;
182 struct writeback_control;
183 struct zone;
184 
185 /*
186  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
187  * disk blocks.  A rbtree of swap extents maps the entire swapfile (Where the
188  * term `swapfile' refers to either a blockdevice or an IS_REG file). Apart
189  * from setup, they're handled identically.
190  *
191  * We always assume that blocks are of size PAGE_SIZE.
192  */
193 struct swap_extent {
194 	struct rb_node rb_node;
195 	pgoff_t start_page;
196 	pgoff_t nr_pages;
197 	sector_t start_block;
198 };
199 
200 /*
201  * Max bad pages in the new format..
202  */
203 #define MAX_SWAP_BADPAGES \
204 	((offsetof(union swap_header, magic.magic) - \
205 	  offsetof(union swap_header, info.badpages)) / sizeof(int))
206 
207 enum {
208 	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
209 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
210 	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
211 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
212 	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
213 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
214 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
215 	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
216 	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
217 	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
218 	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
219 	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
220 	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
221 					/* add others here before... */
222 };
223 
224 #define SWAP_CLUSTER_MAX 32UL
225 #define SWAP_CLUSTER_MAX_SKIPPED (SWAP_CLUSTER_MAX << 10)
226 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
227 
228 /* Bit flag in swap_map */
229 #define SWAP_HAS_CACHE	0x40	/* Flag page is cached, in first swap_map */
230 #define COUNT_CONTINUED	0x80	/* Flag swap_map continuation for full count */
231 
232 /* Special value in first swap_map */
233 #define SWAP_MAP_MAX	0x3e	/* Max count */
234 #define SWAP_MAP_BAD	0x3f	/* Note page is bad */
235 #define SWAP_MAP_SHMEM	0xbf	/* Owned by shmem/tmpfs */
236 
237 /* Special value in each swap_map continuation */
238 #define SWAP_CONT_MAX	0x7f	/* Max count */
239 
240 /*
241  * We use this to track usage of a cluster. A cluster is a block of swap disk
242  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
243  * free clusters are organized into a list. We fetch an entry from the list to
244  * get a free cluster.
245  *
246  * The flags field determines if a cluster is free. This is
247  * protected by cluster lock.
248  */
249 struct swap_cluster_info {
250 	spinlock_t lock;	/*
251 				 * Protect swap_cluster_info fields
252 				 * other than list, and swap_info_struct->swap_map
253 				 * elements corresponding to the swap cluster.
254 				 */
255 	u16 count;
256 	u8 flags;
257 	u8 order;
258 	struct list_head list;
259 };
260 
261 /* All on-list cluster must have a non-zero flag. */
262 enum swap_cluster_flags {
263 	CLUSTER_FLAG_NONE = 0, /* For temporary off-list cluster */
264 	CLUSTER_FLAG_FREE,
265 	CLUSTER_FLAG_NONFULL,
266 	CLUSTER_FLAG_FRAG,
267 	/* Clusters with flags above are allocatable */
268 	CLUSTER_FLAG_USABLE = CLUSTER_FLAG_FRAG,
269 	CLUSTER_FLAG_FULL,
270 	CLUSTER_FLAG_DISCARD,
271 	CLUSTER_FLAG_MAX,
272 };
273 
274 /*
275  * The first page in the swap file is the swap header, which is always marked
276  * bad to prevent it from being allocated as an entry. This also prevents the
277  * cluster to which it belongs being marked free. Therefore 0 is safe to use as
278  * a sentinel to indicate an entry is not valid.
279  */
280 #define SWAP_ENTRY_INVALID	0
281 
282 #ifdef CONFIG_THP_SWAP
283 #define SWAP_NR_ORDERS		(PMD_ORDER + 1)
284 #else
285 #define SWAP_NR_ORDERS		1
286 #endif
287 
288 /*
289  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
290  * its own cluster and swapout sequentially. The purpose is to optimize swapout
291  * throughput.
292  */
293 struct percpu_cluster {
294 	local_lock_t lock; /* Protect the percpu_cluster above */
295 	unsigned int next[SWAP_NR_ORDERS]; /* Likely next allocation offset */
296 };
297 
298 /*
299  * The in-memory structure used to track swap areas.
300  */
301 struct swap_info_struct {
302 	struct percpu_ref users;	/* indicate and keep swap device valid. */
303 	unsigned long	flags;		/* SWP_USED etc: see above */
304 	signed short	prio;		/* swap priority of this type */
305 	struct plist_node list;		/* entry in swap_active_head */
306 	signed char	type;		/* strange name for an index */
307 	unsigned int	max;		/* extent of the swap_map */
308 	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
309 	unsigned long *zeromap;		/* kvmalloc'ed bitmap to track zero pages */
310 	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
311 	struct list_head free_clusters; /* free clusters list */
312 	struct list_head full_clusters; /* full clusters list */
313 	struct list_head nonfull_clusters[SWAP_NR_ORDERS];
314 					/* list of cluster that contains at least one free slot */
315 	struct list_head frag_clusters[SWAP_NR_ORDERS];
316 					/* list of cluster that are fragmented or contented */
317 	atomic_long_t frag_cluster_nr[SWAP_NR_ORDERS];
318 	unsigned int pages;		/* total of usable pages of swap */
319 	atomic_long_t inuse_pages;	/* number of those currently in use */
320 	struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
321 	struct percpu_cluster *global_cluster; /* Use one global cluster for rotating device */
322 	spinlock_t global_cluster_lock;	/* Serialize usage of global cluster */
323 	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
324 	struct block_device *bdev;	/* swap device or bdev of swap file */
325 	struct file *swap_file;		/* seldom referenced */
326 	struct completion comp;		/* seldom referenced */
327 	spinlock_t lock;		/*
328 					 * protect map scan related fields like
329 					 * swap_map, lowest_bit, highest_bit,
330 					 * inuse_pages, cluster_next,
331 					 * cluster_nr, lowest_alloc,
332 					 * highest_alloc, free/discard cluster
333 					 * list. other fields are only changed
334 					 * at swapon/swapoff, so are protected
335 					 * by swap_lock. changing flags need
336 					 * hold this lock and swap_lock. If
337 					 * both locks need hold, hold swap_lock
338 					 * first.
339 					 */
340 	spinlock_t cont_lock;		/*
341 					 * protect swap count continuation page
342 					 * list.
343 					 */
344 	struct work_struct discard_work; /* discard worker */
345 	struct work_struct reclaim_work; /* reclaim worker */
346 	struct list_head discard_clusters; /* discard clusters list */
347 	struct plist_node avail_lists[]; /*
348 					   * entries in swap_avail_heads, one
349 					   * entry per node.
350 					   * Must be last as the number of the
351 					   * array is nr_node_ids, which is not
352 					   * a fixed value so have to allocate
353 					   * dynamically.
354 					   * And it has to be an array so that
355 					   * plist_for_each_* can work.
356 					   */
357 };
358 
page_swap_entry(struct page * page)359 static inline swp_entry_t page_swap_entry(struct page *page)
360 {
361 	struct folio *folio = page_folio(page);
362 	swp_entry_t entry = folio->swap;
363 
364 	entry.val += folio_page_idx(folio, page);
365 	return entry;
366 }
367 
368 /* linux/mm/workingset.c */
369 bool workingset_test_recent(void *shadow, bool file, bool *workingset,
370 				bool flush);
371 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
372 void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
373 void workingset_refault(struct folio *folio, void *shadow);
374 void workingset_activation(struct folio *folio);
375 
376 /* linux/mm/page_alloc.c */
377 extern unsigned long totalreserve_pages;
378 
379 /* Definition of global_zone_page_state not available yet */
380 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
381 
382 
383 /* linux/mm/swap.c */
384 void lru_note_cost(struct lruvec *lruvec, bool file,
385 		   unsigned int nr_io, unsigned int nr_rotated);
386 void lru_note_cost_refault(struct folio *);
387 void folio_add_lru(struct folio *);
388 void folio_add_lru_vma(struct folio *, struct vm_area_struct *);
389 void mark_page_accessed(struct page *);
390 void folio_mark_accessed(struct folio *);
391 
392 extern atomic_t lru_disable_count;
393 
lru_cache_disabled(void)394 static inline bool lru_cache_disabled(void)
395 {
396 	return atomic_read(&lru_disable_count);
397 }
398 
lru_cache_enable(void)399 static inline void lru_cache_enable(void)
400 {
401 	atomic_dec(&lru_disable_count);
402 }
403 
404 extern void lru_cache_disable(void);
405 extern void lru_add_drain(void);
406 extern void lru_add_drain_cpu(int cpu);
407 extern void lru_add_drain_cpu_zone(struct zone *zone);
408 extern void lru_add_drain_all(void);
409 void folio_deactivate(struct folio *folio);
410 void folio_mark_lazyfree(struct folio *folio);
411 extern void swap_setup(void);
412 
413 /* linux/mm/vmscan.c */
414 extern unsigned long zone_reclaimable_pages(struct zone *zone);
415 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
416 					gfp_t gfp_mask, nodemask_t *mask);
417 
418 #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
419 #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
420 #define MIN_SWAPPINESS 0
421 #define MAX_SWAPPINESS 200
422 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
423 						  unsigned long nr_pages,
424 						  gfp_t gfp_mask,
425 						  unsigned int reclaim_options,
426 						  int *swappiness);
427 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
428 						gfp_t gfp_mask, bool noswap,
429 						pg_data_t *pgdat,
430 						unsigned long *nr_scanned);
431 extern unsigned long shrink_all_memory(unsigned long nr_pages);
432 extern int vm_swappiness;
433 long remove_mapping(struct address_space *mapping, struct folio *folio);
434 
435 #ifdef CONFIG_NUMA
436 extern int sysctl_min_unmapped_ratio;
437 extern int sysctl_min_slab_ratio;
438 #endif
439 
440 void check_move_unevictable_folios(struct folio_batch *fbatch);
441 
442 extern void __meminit kswapd_run(int nid);
443 extern void __meminit kswapd_stop(int nid);
444 
445 #ifdef CONFIG_SWAP
446 
447 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
448 		unsigned long nr_pages, sector_t start_block);
449 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
450 		sector_t *);
451 
total_swapcache_pages(void)452 static inline unsigned long total_swapcache_pages(void)
453 {
454 	return global_node_page_state(NR_SWAPCACHE);
455 }
456 
457 void free_swap_cache(struct folio *folio);
458 void free_page_and_swap_cache(struct page *);
459 void free_pages_and_swap_cache(struct encoded_page **, int);
460 /* linux/mm/swapfile.c */
461 extern atomic_long_t nr_swap_pages;
462 extern long total_swap_pages;
463 extern atomic_t nr_rotate_swap;
464 extern bool has_usable_swap(void);
465 
466 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)467 static inline bool vm_swap_full(void)
468 {
469 	return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
470 }
471 
get_nr_swap_pages(void)472 static inline long get_nr_swap_pages(void)
473 {
474 	return atomic_long_read(&nr_swap_pages);
475 }
476 
477 extern void si_swapinfo(struct sysinfo *);
478 swp_entry_t folio_alloc_swap(struct folio *folio);
479 bool folio_free_swap(struct folio *folio);
480 void put_swap_folio(struct folio *folio, swp_entry_t entry);
481 extern swp_entry_t get_swap_page_of_type(int);
482 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order);
483 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
484 extern void swap_shmem_alloc(swp_entry_t, int);
485 extern int swap_duplicate(swp_entry_t);
486 extern int swapcache_prepare(swp_entry_t entry, int nr);
487 extern void swap_free_nr(swp_entry_t entry, int nr_pages);
488 extern void swapcache_free_entries(swp_entry_t *entries, int n);
489 extern void free_swap_and_cache_nr(swp_entry_t entry, int nr);
490 int swap_type_of(dev_t device, sector_t offset);
491 int find_first_swap(dev_t *device);
492 extern unsigned int count_swap_pages(int, int);
493 extern sector_t swapdev_block(int, pgoff_t);
494 extern int __swap_count(swp_entry_t entry);
495 extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
496 extern int swp_swapcount(swp_entry_t entry);
497 struct swap_info_struct *swp_swap_info(swp_entry_t entry);
498 struct backing_dev_info;
499 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
500 extern void exit_swap_address_space(unsigned int type);
501 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
502 sector_t swap_folio_sector(struct folio *folio);
503 
put_swap_device(struct swap_info_struct * si)504 static inline void put_swap_device(struct swap_info_struct *si)
505 {
506 	percpu_ref_put(&si->users);
507 }
508 
509 #else /* CONFIG_SWAP */
swp_swap_info(swp_entry_t entry)510 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
511 {
512 	return NULL;
513 }
514 
get_swap_device(swp_entry_t entry)515 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
516 {
517 	return NULL;
518 }
519 
put_swap_device(struct swap_info_struct * si)520 static inline void put_swap_device(struct swap_info_struct *si)
521 {
522 }
523 
524 #define get_nr_swap_pages()			0L
525 #define total_swap_pages			0L
526 #define total_swapcache_pages()			0UL
527 #define vm_swap_full()				0
528 
529 #define si_swapinfo(val) \
530 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
531 /* only sparc can not include linux/pagemap.h in this file
532  * so leave put_page and release_pages undeclared... */
533 #define free_page_and_swap_cache(page) \
534 	put_page(page)
535 #define free_pages_and_swap_cache(pages, nr) \
536 	release_pages((pages), (nr));
537 
free_swap_and_cache_nr(swp_entry_t entry,int nr)538 static inline void free_swap_and_cache_nr(swp_entry_t entry, int nr)
539 {
540 }
541 
free_swap_cache(struct folio * folio)542 static inline void free_swap_cache(struct folio *folio)
543 {
544 }
545 
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)546 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
547 {
548 	return 0;
549 }
550 
swap_shmem_alloc(swp_entry_t swp,int nr)551 static inline void swap_shmem_alloc(swp_entry_t swp, int nr)
552 {
553 }
554 
swap_duplicate(swp_entry_t swp)555 static inline int swap_duplicate(swp_entry_t swp)
556 {
557 	return 0;
558 }
559 
swapcache_prepare(swp_entry_t swp,int nr)560 static inline int swapcache_prepare(swp_entry_t swp, int nr)
561 {
562 	return 0;
563 }
564 
swap_free_nr(swp_entry_t entry,int nr_pages)565 static inline void swap_free_nr(swp_entry_t entry, int nr_pages)
566 {
567 }
568 
put_swap_folio(struct folio * folio,swp_entry_t swp)569 static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
570 {
571 }
572 
__swap_count(swp_entry_t entry)573 static inline int __swap_count(swp_entry_t entry)
574 {
575 	return 0;
576 }
577 
swap_swapcount(struct swap_info_struct * si,swp_entry_t entry)578 static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
579 {
580 	return 0;
581 }
582 
swp_swapcount(swp_entry_t entry)583 static inline int swp_swapcount(swp_entry_t entry)
584 {
585 	return 0;
586 }
587 
folio_alloc_swap(struct folio * folio)588 static inline swp_entry_t folio_alloc_swap(struct folio *folio)
589 {
590 	swp_entry_t entry;
591 	entry.val = 0;
592 	return entry;
593 }
594 
folio_free_swap(struct folio * folio)595 static inline bool folio_free_swap(struct folio *folio)
596 {
597 	return false;
598 }
599 
add_swap_extent(struct swap_info_struct * sis,unsigned long start_page,unsigned long nr_pages,sector_t start_block)600 static inline int add_swap_extent(struct swap_info_struct *sis,
601 				  unsigned long start_page,
602 				  unsigned long nr_pages, sector_t start_block)
603 {
604 	return -EINVAL;
605 }
606 #endif /* CONFIG_SWAP */
607 
free_swap_and_cache(swp_entry_t entry)608 static inline void free_swap_and_cache(swp_entry_t entry)
609 {
610 	free_swap_and_cache_nr(entry, 1);
611 }
612 
swap_free(swp_entry_t entry)613 static inline void swap_free(swp_entry_t entry)
614 {
615 	swap_free_nr(entry, 1);
616 }
617 
618 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)619 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
620 {
621 	/* Cgroup2 doesn't have per-cgroup swappiness */
622 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
623 		return READ_ONCE(vm_swappiness);
624 
625 	/* root ? */
626 	if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
627 		return READ_ONCE(vm_swappiness);
628 
629 	return READ_ONCE(memcg->swappiness);
630 }
631 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)632 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
633 {
634 	return READ_ONCE(vm_swappiness);
635 }
636 #endif
637 
638 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
639 void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp);
folio_throttle_swaprate(struct folio * folio,gfp_t gfp)640 static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
641 {
642 	if (mem_cgroup_disabled())
643 		return;
644 	__folio_throttle_swaprate(folio, gfp);
645 }
646 #else
folio_throttle_swaprate(struct folio * folio,gfp_t gfp)647 static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
648 {
649 }
650 #endif
651 
652 #if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
653 void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
654 int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry);
mem_cgroup_try_charge_swap(struct folio * folio,swp_entry_t entry)655 static inline int mem_cgroup_try_charge_swap(struct folio *folio,
656 		swp_entry_t entry)
657 {
658 	if (mem_cgroup_disabled())
659 		return 0;
660 	return __mem_cgroup_try_charge_swap(folio, entry);
661 }
662 
663 extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)664 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
665 {
666 	if (mem_cgroup_disabled())
667 		return;
668 	__mem_cgroup_uncharge_swap(entry, nr_pages);
669 }
670 
671 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
672 extern bool mem_cgroup_swap_full(struct folio *folio);
673 #else
mem_cgroup_swapout(struct folio * folio,swp_entry_t entry)674 static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
675 {
676 }
677 
mem_cgroup_try_charge_swap(struct folio * folio,swp_entry_t entry)678 static inline int mem_cgroup_try_charge_swap(struct folio *folio,
679 					     swp_entry_t entry)
680 {
681 	return 0;
682 }
683 
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)684 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
685 					    unsigned int nr_pages)
686 {
687 }
688 
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)689 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
690 {
691 	return get_nr_swap_pages();
692 }
693 
mem_cgroup_swap_full(struct folio * folio)694 static inline bool mem_cgroup_swap_full(struct folio *folio)
695 {
696 	return vm_swap_full();
697 }
698 #endif
699 
700 #endif /* __KERNEL__*/
701 #endif /* _LINUX_SWAP_H */
702