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

source code of linux/include/linux/swap.h