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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/atomic.h>
14#include <linux/page-flags.h>
15#include <asm/page.h>
16
17struct notifier_block;
18
19struct bio;
20
21#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
22#define SWAP_FLAG_PRIO_MASK 0x7fff
23#define SWAP_FLAG_PRIO_SHIFT 0
24#define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
25#define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
26#define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
27
28#define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
29 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
30 SWAP_FLAG_DISCARD_PAGES)
31#define SWAP_BATCH 64
32
33static inline int current_is_kswapd(void)
34{
35 return current->flags & PF_KSWAPD;
36}
37
38/*
39 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
40 * be swapped to. The swap type and the offset into that swap type are
41 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
42 * for the type means that the maximum number of swapcache pages is 27 bits
43 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
44 * the type/offset into the pte as 5/27 as well.
45 */
46#define MAX_SWAPFILES_SHIFT 5
47
48/*
49 * Use some of the swap files numbers for other purposes. This
50 * is a convenient way to hook into the VM to trigger special
51 * actions on faults.
52 */
53
54/*
55 * Unaddressable device memory support. See include/linux/hmm.h and
56 * Documentation/vm/hmm.rst. Short description is we need struct pages for
57 * device memory that is unaddressable (inaccessible) by CPU, so that we can
58 * migrate part of a process memory to device memory.
59 *
60 * When a page is migrated from CPU to device, we set the CPU page table entry
61 * to a special SWP_DEVICE_* entry.
62 */
63#ifdef CONFIG_DEVICE_PRIVATE
64#define SWP_DEVICE_NUM 2
65#define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
66#define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
67#else
68#define SWP_DEVICE_NUM 0
69#endif
70
71/*
72 * NUMA node memory migration support
73 */
74#ifdef CONFIG_MIGRATION
75#define SWP_MIGRATION_NUM 2
76#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
77#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
78#else
79#define SWP_MIGRATION_NUM 0
80#endif
81
82/*
83 * Handling of hardware poisoned pages with memory corruption.
84 */
85#ifdef CONFIG_MEMORY_FAILURE
86#define SWP_HWPOISON_NUM 1
87#define SWP_HWPOISON MAX_SWAPFILES
88#else
89#define SWP_HWPOISON_NUM 0
90#endif
91
92#define MAX_SWAPFILES \
93 ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
94 SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
95
96/*
97 * Magic header for a swap area. The first part of the union is
98 * what the swap magic looks like for the old (limited to 128MB)
99 * swap area format, the second part of the union adds - in the
100 * old reserved area - some extra information. Note that the first
101 * kilobyte is reserved for boot loader or disk label stuff...
102 *
103 * Having the magic at the end of the PAGE_SIZE makes detecting swap
104 * areas somewhat tricky on machines that support multiple page sizes.
105 * For 2.5 we'll probably want to move the magic to just beyond the
106 * bootbits...
107 */
108union swap_header {
109 struct {
110 char reserved[PAGE_SIZE - 10];
111 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
112 } magic;
113 struct {
114 char bootbits[1024]; /* Space for disklabel etc. */
115 __u32 version;
116 __u32 last_page;
117 __u32 nr_badpages;
118 unsigned char sws_uuid[16];
119 unsigned char sws_volume[16];
120 __u32 padding[117];
121 __u32 badpages[1];
122 } info;
123};
124
125/*
126 * current->reclaim_state points to one of these when a task is running
127 * memory reclaim
128 */
129struct reclaim_state {
130 unsigned long reclaimed_slab;
131};
132
133#ifdef __KERNEL__
134
135struct address_space;
136struct sysinfo;
137struct writeback_control;
138struct zone;
139
140/*
141 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
142 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
143 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
144 * from setup, they're handled identically.
145 *
146 * We always assume that blocks are of size PAGE_SIZE.
147 */
148struct swap_extent {
149 struct list_head list;
150 pgoff_t start_page;
151 pgoff_t nr_pages;
152 sector_t start_block;
153};
154
155/*
156 * Max bad pages in the new format..
157 */
158#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
159#define MAX_SWAP_BADPAGES \
160 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
161
162enum {
163 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
164 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
165 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
166 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
167 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
168 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
169 SWP_BLKDEV = (1 << 6), /* its a block device */
170 SWP_FILE = (1 << 7), /* set after swap_activate success */
171 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
172 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
173 SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */
174 SWP_SYNCHRONOUS_IO = (1 << 11), /* synchronous IO is efficient */
175 /* add others here before... */
176 SWP_SCANNING = (1 << 12), /* refcount in scan_swap_map */
177};
178
179#define SWAP_CLUSTER_MAX 32UL
180#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
181
182#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
183#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
184#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
185#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
186#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
187#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
188
189/*
190 * We use this to track usage of a cluster. A cluster is a block of swap disk
191 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
192 * free clusters are organized into a list. We fetch an entry from the list to
193 * get a free cluster.
194 *
195 * The data field stores next cluster if the cluster is free or cluster usage
196 * counter otherwise. The flags field determines if a cluster is free. This is
197 * protected by swap_info_struct.lock.
198 */
199struct swap_cluster_info {
200 spinlock_t lock; /*
201 * Protect swap_cluster_info fields
202 * and swap_info_struct->swap_map
203 * elements correspond to the swap
204 * cluster
205 */
206 unsigned int data:24;
207 unsigned int flags:8;
208};
209#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
210#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
211#define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
212
213/*
214 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
215 * its own cluster and swapout sequentially. The purpose is to optimize swapout
216 * throughput.
217 */
218struct percpu_cluster {
219 struct swap_cluster_info index; /* Current cluster index */
220 unsigned int next; /* Likely next allocation offset */
221};
222
223struct swap_cluster_list {
224 struct swap_cluster_info head;
225 struct swap_cluster_info tail;
226};
227
228/*
229 * The in-memory structure used to track swap areas.
230 */
231struct swap_info_struct {
232 unsigned long flags; /* SWP_USED etc: see above */
233 signed short prio; /* swap priority of this type */
234 struct plist_node list; /* entry in swap_active_head */
235 struct plist_node avail_lists[MAX_NUMNODES];/* entry in swap_avail_heads */
236 signed char type; /* strange name for an index */
237 unsigned int max; /* extent of the swap_map */
238 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
239 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
240 struct swap_cluster_list free_clusters; /* free clusters list */
241 unsigned int lowest_bit; /* index of first free in swap_map */
242 unsigned int highest_bit; /* index of last free in swap_map */
243 unsigned int pages; /* total of usable pages of swap */
244 unsigned int inuse_pages; /* number of those currently in use */
245 unsigned int cluster_next; /* likely index for next allocation */
246 unsigned int cluster_nr; /* countdown to next cluster search */
247 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
248 struct swap_extent *curr_swap_extent;
249 struct swap_extent first_swap_extent;
250 struct block_device *bdev; /* swap device or bdev of swap file */
251 struct file *swap_file; /* seldom referenced */
252 unsigned int old_block_size; /* seldom referenced */
253#ifdef CONFIG_FRONTSWAP
254 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
255 atomic_t frontswap_pages; /* frontswap pages in-use counter */
256#endif
257 spinlock_t lock; /*
258 * protect map scan related fields like
259 * swap_map, lowest_bit, highest_bit,
260 * inuse_pages, cluster_next,
261 * cluster_nr, lowest_alloc,
262 * highest_alloc, free/discard cluster
263 * list. other fields are only changed
264 * at swapon/swapoff, so are protected
265 * by swap_lock. changing flags need
266 * hold this lock and swap_lock. If
267 * both locks need hold, hold swap_lock
268 * first.
269 */
270 spinlock_t cont_lock; /*
271 * protect swap count continuation page
272 * list.
273 */
274 struct work_struct discard_work; /* discard worker */
275 struct swap_cluster_list discard_clusters; /* discard clusters list */
276};
277
278#ifdef CONFIG_64BIT
279#define SWAP_RA_ORDER_CEILING 5
280#else
281/* Avoid stack overflow, because we need to save part of page table */
282#define SWAP_RA_ORDER_CEILING 3
283#define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
284#endif
285
286struct vma_swap_readahead {
287 unsigned short win;
288 unsigned short offset;
289 unsigned short nr_pte;
290#ifdef CONFIG_64BIT
291 pte_t *ptes;
292#else
293 pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
294#endif
295};
296
297/* linux/mm/workingset.c */
298void *workingset_eviction(struct address_space *mapping, struct page *page);
299bool workingset_refault(void *shadow);
300void workingset_activation(struct page *page);
301
302/* Do not use directly, use workingset_lookup_update */
303void workingset_update_node(struct radix_tree_node *node);
304
305/* Returns workingset_update_node() if the mapping has shadow entries. */
306#define workingset_lookup_update(mapping) \
307({ \
308 radix_tree_update_node_t __helper = workingset_update_node; \
309 if (dax_mapping(mapping) || shmem_mapping(mapping)) \
310 __helper = NULL; \
311 __helper; \
312})
313
314/* linux/mm/page_alloc.c */
315extern unsigned long totalram_pages;
316extern unsigned long totalreserve_pages;
317extern unsigned long nr_free_buffer_pages(void);
318extern unsigned long nr_free_pagecache_pages(void);
319
320/* Definition of global_zone_page_state not available yet */
321#define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
322
323
324/* linux/mm/swap.c */
325extern void lru_cache_add(struct page *);
326extern void lru_cache_add_anon(struct page *page);
327extern void lru_cache_add_file(struct page *page);
328extern void lru_add_page_tail(struct page *page, struct page *page_tail,
329 struct lruvec *lruvec, struct list_head *head);
330extern void activate_page(struct page *);
331extern void mark_page_accessed(struct page *);
332extern void lru_add_drain(void);
333extern void lru_add_drain_cpu(int cpu);
334extern void lru_add_drain_all(void);
335extern void rotate_reclaimable_page(struct page *page);
336extern void deactivate_file_page(struct page *page);
337extern void mark_page_lazyfree(struct page *page);
338extern void swap_setup(void);
339
340extern void lru_cache_add_active_or_unevictable(struct page *page,
341 struct vm_area_struct *vma);
342
343/* linux/mm/vmscan.c */
344extern unsigned long zone_reclaimable_pages(struct zone *zone);
345extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
346 gfp_t gfp_mask, nodemask_t *mask);
347extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
348extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
349 unsigned long nr_pages,
350 gfp_t gfp_mask,
351 bool may_swap);
352extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
353 gfp_t gfp_mask, bool noswap,
354 pg_data_t *pgdat,
355 unsigned long *nr_scanned);
356extern unsigned long shrink_all_memory(unsigned long nr_pages);
357extern int vm_swappiness;
358extern int remove_mapping(struct address_space *mapping, struct page *page);
359extern unsigned long vm_total_pages;
360
361#ifdef CONFIG_NUMA
362extern int node_reclaim_mode;
363extern int sysctl_min_unmapped_ratio;
364extern int sysctl_min_slab_ratio;
365extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
366#else
367#define node_reclaim_mode 0
368static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
369 unsigned int order)
370{
371 return 0;
372}
373#endif
374
375extern int page_evictable(struct page *page);
376extern void check_move_unevictable_pages(struct page **, int nr_pages);
377
378extern int kswapd_run(int nid);
379extern void kswapd_stop(int nid);
380
381#ifdef CONFIG_SWAP
382
383#include <linux/blk_types.h> /* for bio_end_io_t */
384
385/* linux/mm/page_io.c */
386extern int swap_readpage(struct page *page, bool do_poll);
387extern int swap_writepage(struct page *page, struct writeback_control *wbc);
388extern void end_swap_bio_write(struct bio *bio);
389extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
390 bio_end_io_t end_write_func);
391extern int swap_set_page_dirty(struct page *page);
392
393int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
394 unsigned long nr_pages, sector_t start_block);
395int generic_swapfile_activate(struct swap_info_struct *, struct file *,
396 sector_t *);
397
398/* linux/mm/swap_state.c */
399/* One swap address space for each 64M swap space */
400#define SWAP_ADDRESS_SPACE_SHIFT 14
401#define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
402extern struct address_space *swapper_spaces[];
403#define swap_address_space(entry) \
404 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
405 >> SWAP_ADDRESS_SPACE_SHIFT])
406extern unsigned long total_swapcache_pages(void);
407extern void show_swap_cache_info(void);
408extern int add_to_swap(struct page *page);
409extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
410extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
411extern void __delete_from_swap_cache(struct page *);
412extern void delete_from_swap_cache(struct page *);
413extern void free_page_and_swap_cache(struct page *);
414extern void free_pages_and_swap_cache(struct page **, int);
415extern struct page *lookup_swap_cache(swp_entry_t entry,
416 struct vm_area_struct *vma,
417 unsigned long addr);
418extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
419 struct vm_area_struct *vma, unsigned long addr,
420 bool do_poll);
421extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
422 struct vm_area_struct *vma, unsigned long addr,
423 bool *new_page_allocated);
424extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
425 struct vm_fault *vmf);
426extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
427 struct vm_fault *vmf);
428
429/* linux/mm/swapfile.c */
430extern atomic_long_t nr_swap_pages;
431extern long total_swap_pages;
432extern atomic_t nr_rotate_swap;
433extern bool has_usable_swap(void);
434
435/* Swap 50% full? Release swapcache more aggressively.. */
436static inline bool vm_swap_full(void)
437{
438 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
439}
440
441static inline long get_nr_swap_pages(void)
442{
443 return atomic_long_read(&nr_swap_pages);
444}
445
446extern void si_swapinfo(struct sysinfo *);
447extern swp_entry_t get_swap_page(struct page *page);
448extern void put_swap_page(struct page *page, swp_entry_t entry);
449extern swp_entry_t get_swap_page_of_type(int);
450extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
451extern int add_swap_count_continuation(swp_entry_t, gfp_t);
452extern void swap_shmem_alloc(swp_entry_t);
453extern int swap_duplicate(swp_entry_t);
454extern int swapcache_prepare(swp_entry_t);
455extern void swap_free(swp_entry_t);
456extern void swapcache_free_entries(swp_entry_t *entries, int n);
457extern int free_swap_and_cache(swp_entry_t);
458extern int swap_type_of(dev_t, sector_t, struct block_device **);
459extern unsigned int count_swap_pages(int, int);
460extern sector_t map_swap_page(struct page *, struct block_device **);
461extern sector_t swapdev_block(int, pgoff_t);
462extern int page_swapcount(struct page *);
463extern int __swap_count(struct swap_info_struct *si, swp_entry_t entry);
464extern int __swp_swapcount(swp_entry_t entry);
465extern int swp_swapcount(swp_entry_t entry);
466extern struct swap_info_struct *page_swap_info(struct page *);
467extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
468extern bool reuse_swap_page(struct page *, int *);
469extern int try_to_free_swap(struct page *);
470struct backing_dev_info;
471extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
472extern void exit_swap_address_space(unsigned int type);
473
474#else /* CONFIG_SWAP */
475
476static inline int swap_readpage(struct page *page, bool do_poll)
477{
478 return 0;
479}
480
481static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
482{
483 return NULL;
484}
485
486#define swap_address_space(entry) (NULL)
487#define get_nr_swap_pages() 0L
488#define total_swap_pages 0L
489#define total_swapcache_pages() 0UL
490#define vm_swap_full() 0
491
492#define si_swapinfo(val) \
493 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
494/* only sparc can not include linux/pagemap.h in this file
495 * so leave put_page and release_pages undeclared... */
496#define free_page_and_swap_cache(page) \
497 put_page(page)
498#define free_pages_and_swap_cache(pages, nr) \
499 release_pages((pages), (nr));
500
501static inline void show_swap_cache_info(void)
502{
503}
504
505#define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
506#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
507
508static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
509{
510 return 0;
511}
512
513static inline void swap_shmem_alloc(swp_entry_t swp)
514{
515}
516
517static inline int swap_duplicate(swp_entry_t swp)
518{
519 return 0;
520}
521
522static inline void swap_free(swp_entry_t swp)
523{
524}
525
526static inline void put_swap_page(struct page *page, swp_entry_t swp)
527{
528}
529
530static inline struct page *swap_cluster_readahead(swp_entry_t entry,
531 gfp_t gfp_mask, struct vm_fault *vmf)
532{
533 return NULL;
534}
535
536static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
537 struct vm_fault *vmf)
538{
539 return NULL;
540}
541
542static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
543{
544 return 0;
545}
546
547static inline struct page *lookup_swap_cache(swp_entry_t swp,
548 struct vm_area_struct *vma,
549 unsigned long addr)
550{
551 return NULL;
552}
553
554static inline int add_to_swap(struct page *page)
555{
556 return 0;
557}
558
559static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
560 gfp_t gfp_mask)
561{
562 return -1;
563}
564
565static inline void __delete_from_swap_cache(struct page *page)
566{
567}
568
569static inline void delete_from_swap_cache(struct page *page)
570{
571}
572
573static inline int page_swapcount(struct page *page)
574{
575 return 0;
576}
577
578static inline int __swap_count(struct swap_info_struct *si, swp_entry_t entry)
579{
580 return 0;
581}
582
583static inline int __swp_swapcount(swp_entry_t entry)
584{
585 return 0;
586}
587
588static inline int swp_swapcount(swp_entry_t entry)
589{
590 return 0;
591}
592
593#define reuse_swap_page(page, total_map_swapcount) \
594 (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
595
596static inline int try_to_free_swap(struct page *page)
597{
598 return 0;
599}
600
601static inline swp_entry_t get_swap_page(struct page *page)
602{
603 swp_entry_t entry;
604 entry.val = 0;
605 return entry;
606}
607
608#endif /* CONFIG_SWAP */
609
610#ifdef CONFIG_THP_SWAP
611extern int split_swap_cluster(swp_entry_t entry);
612#else
613static inline int split_swap_cluster(swp_entry_t entry)
614{
615 return 0;
616}
617#endif
618
619#ifdef CONFIG_MEMCG
620static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
621{
622 /* Cgroup2 doesn't have per-cgroup swappiness */
623 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
624 return vm_swappiness;
625
626 /* root ? */
627 if (mem_cgroup_disabled() || !memcg->css.parent)
628 return vm_swappiness;
629
630 return memcg->swappiness;
631}
632
633#else
634static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
635{
636 return vm_swappiness;
637}
638#endif
639
640#ifdef CONFIG_MEMCG_SWAP
641extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
642extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
643extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
644extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
645extern bool mem_cgroup_swap_full(struct page *page);
646#else
647static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
648{
649}
650
651static inline int mem_cgroup_try_charge_swap(struct page *page,
652 swp_entry_t entry)
653{
654 return 0;
655}
656
657static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
658 unsigned int nr_pages)
659{
660}
661
662static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
663{
664 return get_nr_swap_pages();
665}
666
667static inline bool mem_cgroup_swap_full(struct page *page)
668{
669 return vm_swap_full();
670}
671#endif
672
673#endif /* __KERNEL__*/
674#endif /* _LINUX_SWAP_H */