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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
21struct pagevec;
22
23#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
24#define SWAP_FLAG_PRIO_MASK 0x7fff
25#define SWAP_FLAG_PRIO_SHIFT 0
26#define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
27#define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
28#define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
29
30#define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
31 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
32 SWAP_FLAG_DISCARD_PAGES)
33#define SWAP_BATCH 64
34
35static inline int current_is_kswapd(void)
36{
37 return current->flags & PF_KSWAPD;
38}
39
40/*
41 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
42 * be swapped to. The swap type and the offset into that swap type are
43 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
44 * for the type means that the maximum number of swapcache pages is 27 bits
45 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
46 * the type/offset into the pte as 5/27 as well.
47 */
48#define MAX_SWAPFILES_SHIFT 5
49
50/*
51 * Use some of the swap files numbers for other purposes. This
52 * is a convenient way to hook into the VM to trigger special
53 * actions on faults.
54 */
55
56/*
57 * Unaddressable device memory support. See include/linux/hmm.h and
58 * Documentation/vm/hmm.rst. Short description is we need struct pages for
59 * device memory that is unaddressable (inaccessible) by CPU, so that we can
60 * migrate part of a process memory to device memory.
61 *
62 * When a page is migrated from CPU to device, we set the CPU page table entry
63 * to a special SWP_DEVICE_* entry.
64 */
65#ifdef CONFIG_DEVICE_PRIVATE
66#define SWP_DEVICE_NUM 2
67#define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
68#define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
69#else
70#define SWP_DEVICE_NUM 0
71#endif
72
73/*
74 * NUMA node memory migration support
75 */
76#ifdef CONFIG_MIGRATION
77#define SWP_MIGRATION_NUM 2
78#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
79#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
80#else
81#define SWP_MIGRATION_NUM 0
82#endif
83
84/*
85 * Handling of hardware poisoned pages with memory corruption.
86 */
87#ifdef CONFIG_MEMORY_FAILURE
88#define SWP_HWPOISON_NUM 1
89#define SWP_HWPOISON MAX_SWAPFILES
90#else
91#define SWP_HWPOISON_NUM 0
92#endif
93
94#define MAX_SWAPFILES \
95 ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
96 SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
97
98/*
99 * Magic header for a swap area. The first part of the union is
100 * what the swap magic looks like for the old (limited to 128MB)
101 * swap area format, the second part of the union adds - in the
102 * old reserved area - some extra information. Note that the first
103 * kilobyte is reserved for boot loader or disk label stuff...
104 *
105 * Having the magic at the end of the PAGE_SIZE makes detecting swap
106 * areas somewhat tricky on machines that support multiple page sizes.
107 * For 2.5 we'll probably want to move the magic to just beyond the
108 * bootbits...
109 */
110union swap_header {
111 struct {
112 char reserved[PAGE_SIZE - 10];
113 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
114 } magic;
115 struct {
116 char bootbits[1024]; /* Space for disklabel etc. */
117 __u32 version;
118 __u32 last_page;
119 __u32 nr_badpages;
120 unsigned char sws_uuid[16];
121 unsigned char sws_volume[16];
122 __u32 padding[117];
123 __u32 badpages[1];
124 } info;
125};
126
127/*
128 * current->reclaim_state points to one of these when a task is running
129 * memory reclaim
130 */
131struct reclaim_state {
132 unsigned long reclaimed_slab;
133};
134
135#ifdef __KERNEL__
136
137struct address_space;
138struct sysinfo;
139struct writeback_control;
140struct zone;
141
142/*
143 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
144 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
145 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
146 * from setup, they're handled identically.
147 *
148 * We always assume that blocks are of size PAGE_SIZE.
149 */
150struct swap_extent {
151 struct rb_node rb_node;
152 pgoff_t start_page;
153 pgoff_t nr_pages;
154 sector_t start_block;
155};
156
157/*
158 * Max bad pages in the new format..
159 */
160#define MAX_SWAP_BADPAGES \
161 ((offsetof(union swap_header, magic.magic) - \
162 offsetof(union swap_header, info.badpages)) / sizeof(int))
163
164enum {
165 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
166 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
167 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
168 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
169 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
170 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
171 SWP_BLKDEV = (1 << 6), /* its a block device */
172 SWP_ACTIVATED = (1 << 7), /* set after swap_activate success */
173 SWP_FS_OPS = (1 << 8), /* swapfile operations go through fs */
174 SWP_AREA_DISCARD = (1 << 9), /* single-time swap area discards */
175 SWP_PAGE_DISCARD = (1 << 10), /* freed swap page-cluster discards */
176 SWP_STABLE_WRITES = (1 << 11), /* no overwrite PG_writeback pages */
177 SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */
178 SWP_VALID = (1 << 13), /* swap is valid to be operated on? */
179 /* add others here before... */
180 SWP_SCANNING = (1 << 14), /* refcount in scan_swap_map */
181};
182
183#define SWAP_CLUSTER_MAX 32UL
184#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
185
186/* Bit flag in swap_map */
187#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
188#define COUNT_CONTINUED 0x80 /* Flag swap_map continuation for full count */
189
190/* Special value in first swap_map */
191#define SWAP_MAP_MAX 0x3e /* Max count */
192#define SWAP_MAP_BAD 0x3f /* Note page is bad */
193#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs */
194
195/* Special value in each swap_map continuation */
196#define SWAP_CONT_MAX 0x7f /* Max count */
197
198/*
199 * We use this to track usage of a cluster. A cluster is a block of swap disk
200 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
201 * free clusters are organized into a list. We fetch an entry from the list to
202 * get a free cluster.
203 *
204 * The data field stores next cluster if the cluster is free or cluster usage
205 * counter otherwise. The flags field determines if a cluster is free. This is
206 * protected by swap_info_struct.lock.
207 */
208struct swap_cluster_info {
209 spinlock_t lock; /*
210 * Protect swap_cluster_info fields
211 * and swap_info_struct->swap_map
212 * elements correspond to the swap
213 * cluster
214 */
215 unsigned int data:24;
216 unsigned int flags:8;
217};
218#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
219#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
220#define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
221
222/*
223 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
224 * its own cluster and swapout sequentially. The purpose is to optimize swapout
225 * throughput.
226 */
227struct percpu_cluster {
228 struct swap_cluster_info index; /* Current cluster index */
229 unsigned int next; /* Likely next allocation offset */
230};
231
232struct swap_cluster_list {
233 struct swap_cluster_info head;
234 struct swap_cluster_info tail;
235};
236
237/*
238 * The in-memory structure used to track swap areas.
239 */
240struct swap_info_struct {
241 unsigned long flags; /* SWP_USED etc: see above */
242 signed short prio; /* swap priority of this type */
243 struct plist_node list; /* entry in swap_active_head */
244 signed char type; /* strange name for an index */
245 unsigned int max; /* extent of the swap_map */
246 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
247 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
248 struct swap_cluster_list free_clusters; /* free clusters list */
249 unsigned int lowest_bit; /* index of first free in swap_map */
250 unsigned int highest_bit; /* index of last free in swap_map */
251 unsigned int pages; /* total of usable pages of swap */
252 unsigned int inuse_pages; /* number of those currently in use */
253 unsigned int cluster_next; /* likely index for next allocation */
254 unsigned int cluster_nr; /* countdown to next cluster search */
255 unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
256 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
257 struct rb_root swap_extent_root;/* root of the swap extent rbtree */
258 struct block_device *bdev; /* swap device or bdev of swap file */
259 struct file *swap_file; /* seldom referenced */
260 unsigned int old_block_size; /* seldom referenced */
261#ifdef CONFIG_FRONTSWAP
262 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
263 atomic_t frontswap_pages; /* frontswap pages in-use counter */
264#endif
265 spinlock_t lock; /*
266 * protect map scan related fields like
267 * swap_map, lowest_bit, highest_bit,
268 * inuse_pages, cluster_next,
269 * cluster_nr, lowest_alloc,
270 * highest_alloc, free/discard cluster
271 * list. other fields are only changed
272 * at swapon/swapoff, so are protected
273 * by swap_lock. changing flags need
274 * hold this lock and swap_lock. If
275 * both locks need hold, hold swap_lock
276 * first.
277 */
278 spinlock_t cont_lock; /*
279 * protect swap count continuation page
280 * list.
281 */
282 struct work_struct discard_work; /* discard worker */
283 struct swap_cluster_list discard_clusters; /* discard clusters list */
284 struct plist_node avail_lists[]; /*
285 * entries in swap_avail_heads, one
286 * entry per node.
287 * Must be last as the number of the
288 * array is nr_node_ids, which is not
289 * a fixed value so have to allocate
290 * dynamically.
291 * And it has to be an array so that
292 * plist_for_each_* can work.
293 */
294};
295
296#ifdef CONFIG_64BIT
297#define SWAP_RA_ORDER_CEILING 5
298#else
299/* Avoid stack overflow, because we need to save part of page table */
300#define SWAP_RA_ORDER_CEILING 3
301#define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
302#endif
303
304struct vma_swap_readahead {
305 unsigned short win;
306 unsigned short offset;
307 unsigned short nr_pte;
308#ifdef CONFIG_64BIT
309 pte_t *ptes;
310#else
311 pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
312#endif
313};
314
315/* linux/mm/workingset.c */
316void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
317void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
318void workingset_refault(struct page *page, void *shadow);
319void workingset_activation(struct page *page);
320
321/* Only track the nodes of mappings with shadow entries */
322void workingset_update_node(struct xa_node *node);
323#define mapping_set_update(xas, mapping) do { \
324 if (!dax_mapping(mapping) && !shmem_mapping(mapping)) \
325 xas_set_update(xas, workingset_update_node); \
326} while (0)
327
328/* linux/mm/page_alloc.c */
329extern unsigned long totalreserve_pages;
330extern unsigned long nr_free_buffer_pages(void);
331
332/* Definition of global_zone_page_state not available yet */
333#define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
334
335
336/* linux/mm/swap.c */
337extern void lru_note_cost(struct lruvec *lruvec, bool file,
338 unsigned int nr_pages);
339extern void lru_note_cost_page(struct page *);
340extern void lru_cache_add(struct page *);
341extern void mark_page_accessed(struct page *);
342extern void lru_add_drain(void);
343extern void lru_add_drain_cpu(int cpu);
344extern void lru_add_drain_cpu_zone(struct zone *zone);
345extern void lru_add_drain_all(void);
346extern void rotate_reclaimable_page(struct page *page);
347extern void deactivate_file_page(struct page *page);
348extern void deactivate_page(struct page *page);
349extern void mark_page_lazyfree(struct page *page);
350extern void swap_setup(void);
351
352extern void lru_cache_add_inactive_or_unevictable(struct page *page,
353 struct vm_area_struct *vma);
354
355/* linux/mm/vmscan.c */
356extern unsigned long zone_reclaimable_pages(struct zone *zone);
357extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
358 gfp_t gfp_mask, nodemask_t *mask);
359extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);
360extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
361 unsigned long nr_pages,
362 gfp_t gfp_mask,
363 bool may_swap);
364extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
365 gfp_t gfp_mask, bool noswap,
366 pg_data_t *pgdat,
367 unsigned long *nr_scanned);
368extern unsigned long shrink_all_memory(unsigned long nr_pages);
369extern int vm_swappiness;
370extern int remove_mapping(struct address_space *mapping, struct page *page);
371
372extern unsigned long reclaim_pages(struct list_head *page_list);
373#ifdef CONFIG_NUMA
374extern int node_reclaim_mode;
375extern int sysctl_min_unmapped_ratio;
376extern int sysctl_min_slab_ratio;
377#else
378#define node_reclaim_mode 0
379#endif
380
381extern void check_move_unevictable_pages(struct pagevec *pvec);
382
383extern int kswapd_run(int nid);
384extern void kswapd_stop(int nid);
385
386#ifdef CONFIG_SWAP
387
388#include <linux/blk_types.h> /* for bio_end_io_t */
389
390/* linux/mm/page_io.c */
391extern int swap_readpage(struct page *page, bool do_poll);
392extern int swap_writepage(struct page *page, struct writeback_control *wbc);
393extern void end_swap_bio_write(struct bio *bio);
394extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
395 bio_end_io_t end_write_func);
396extern int swap_set_page_dirty(struct page *page);
397
398int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
399 unsigned long nr_pages, sector_t start_block);
400int generic_swapfile_activate(struct swap_info_struct *, struct file *,
401 sector_t *);
402
403/* linux/mm/swap_state.c */
404/* One swap address space for each 64M swap space */
405#define SWAP_ADDRESS_SPACE_SHIFT 14
406#define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
407extern struct address_space *swapper_spaces[];
408#define swap_address_space(entry) \
409 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
410 >> SWAP_ADDRESS_SPACE_SHIFT])
411static inline unsigned long total_swapcache_pages(void)
412{
413 return global_node_page_state(NR_SWAPCACHE);
414}
415
416extern void show_swap_cache_info(void);
417extern int add_to_swap(struct page *page);
418extern void *get_shadow_from_swap_cache(swp_entry_t entry);
419extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
420 gfp_t gfp, void **shadowp);
421extern void __delete_from_swap_cache(struct page *page,
422 swp_entry_t entry, void *shadow);
423extern void delete_from_swap_cache(struct page *);
424extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
425 unsigned long end);
426extern void free_page_and_swap_cache(struct page *);
427extern void free_pages_and_swap_cache(struct page **, int);
428extern struct page *lookup_swap_cache(swp_entry_t entry,
429 struct vm_area_struct *vma,
430 unsigned long addr);
431struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
432extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
433 struct vm_area_struct *vma, unsigned long addr,
434 bool do_poll);
435extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
436 struct vm_area_struct *vma, unsigned long addr,
437 bool *new_page_allocated);
438extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
439 struct vm_fault *vmf);
440extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
441 struct vm_fault *vmf);
442
443/* linux/mm/swapfile.c */
444extern atomic_long_t nr_swap_pages;
445extern long total_swap_pages;
446extern atomic_t nr_rotate_swap;
447extern bool has_usable_swap(void);
448
449/* Swap 50% full? Release swapcache more aggressively.. */
450static inline bool vm_swap_full(void)
451{
452 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
453}
454
455static inline long get_nr_swap_pages(void)
456{
457 return atomic_long_read(&nr_swap_pages);
458}
459
460extern void si_swapinfo(struct sysinfo *);
461extern swp_entry_t get_swap_page(struct page *page);
462extern void put_swap_page(struct page *page, swp_entry_t entry);
463extern swp_entry_t get_swap_page_of_type(int);
464extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
465extern int add_swap_count_continuation(swp_entry_t, gfp_t);
466extern void swap_shmem_alloc(swp_entry_t);
467extern int swap_duplicate(swp_entry_t);
468extern int swapcache_prepare(swp_entry_t);
469extern void swap_free(swp_entry_t);
470extern void swapcache_free_entries(swp_entry_t *entries, int n);
471extern int free_swap_and_cache(swp_entry_t);
472int swap_type_of(dev_t device, sector_t offset);
473int find_first_swap(dev_t *device);
474extern unsigned int count_swap_pages(int, int);
475extern sector_t swapdev_block(int, pgoff_t);
476extern int page_swapcount(struct page *);
477extern int __swap_count(swp_entry_t entry);
478extern int __swp_swapcount(swp_entry_t entry);
479extern int swp_swapcount(swp_entry_t entry);
480extern struct swap_info_struct *page_swap_info(struct page *);
481extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
482extern bool reuse_swap_page(struct page *, int *);
483extern int try_to_free_swap(struct page *);
484struct backing_dev_info;
485extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
486extern void exit_swap_address_space(unsigned int type);
487extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
488sector_t swap_page_sector(struct page *page);
489
490static inline void put_swap_device(struct swap_info_struct *si)
491{
492 rcu_read_unlock();
493}
494
495#else /* CONFIG_SWAP */
496
497static inline int swap_readpage(struct page *page, bool do_poll)
498{
499 return 0;
500}
501
502static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
503{
504 return NULL;
505}
506
507#define swap_address_space(entry) (NULL)
508#define get_nr_swap_pages() 0L
509#define total_swap_pages 0L
510#define total_swapcache_pages() 0UL
511#define vm_swap_full() 0
512
513#define si_swapinfo(val) \
514 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
515/* only sparc can not include linux/pagemap.h in this file
516 * so leave put_page and release_pages undeclared... */
517#define free_page_and_swap_cache(page) \
518 put_page(page)
519#define free_pages_and_swap_cache(pages, nr) \
520 release_pages((pages), (nr));
521
522static inline void show_swap_cache_info(void)
523{
524}
525
526#define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
527#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
528
529static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
530{
531 return 0;
532}
533
534static inline void swap_shmem_alloc(swp_entry_t swp)
535{
536}
537
538static inline int swap_duplicate(swp_entry_t swp)
539{
540 return 0;
541}
542
543static inline void swap_free(swp_entry_t swp)
544{
545}
546
547static inline void put_swap_page(struct page *page, swp_entry_t swp)
548{
549}
550
551static inline struct page *swap_cluster_readahead(swp_entry_t entry,
552 gfp_t gfp_mask, struct vm_fault *vmf)
553{
554 return NULL;
555}
556
557static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
558 struct vm_fault *vmf)
559{
560 return NULL;
561}
562
563static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
564{
565 return 0;
566}
567
568static inline struct page *lookup_swap_cache(swp_entry_t swp,
569 struct vm_area_struct *vma,
570 unsigned long addr)
571{
572 return NULL;
573}
574
575static inline
576struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
577{
578 return find_get_page(mapping, index);
579}
580
581static inline int add_to_swap(struct page *page)
582{
583 return 0;
584}
585
586static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
587{
588 return NULL;
589}
590
591static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
592 gfp_t gfp_mask, void **shadowp)
593{
594 return -1;
595}
596
597static inline void __delete_from_swap_cache(struct page *page,
598 swp_entry_t entry, void *shadow)
599{
600}
601
602static inline void delete_from_swap_cache(struct page *page)
603{
604}
605
606static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
607 unsigned long end)
608{
609}
610
611static inline int page_swapcount(struct page *page)
612{
613 return 0;
614}
615
616static inline int __swap_count(swp_entry_t entry)
617{
618 return 0;
619}
620
621static inline int __swp_swapcount(swp_entry_t entry)
622{
623 return 0;
624}
625
626static inline int swp_swapcount(swp_entry_t entry)
627{
628 return 0;
629}
630
631#define reuse_swap_page(page, total_map_swapcount) \
632 (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
633
634static inline int try_to_free_swap(struct page *page)
635{
636 return 0;
637}
638
639static inline swp_entry_t get_swap_page(struct page *page)
640{
641 swp_entry_t entry;
642 entry.val = 0;
643 return entry;
644}
645
646#endif /* CONFIG_SWAP */
647
648#ifdef CONFIG_THP_SWAP
649extern int split_swap_cluster(swp_entry_t entry);
650#else
651static inline int split_swap_cluster(swp_entry_t entry)
652{
653 return 0;
654}
655#endif
656
657#ifdef CONFIG_MEMCG
658static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
659{
660 /* Cgroup2 doesn't have per-cgroup swappiness */
661 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
662 return vm_swappiness;
663
664 /* root ? */
665 if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
666 return vm_swappiness;
667
668 return memcg->swappiness;
669}
670#else
671static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
672{
673 return vm_swappiness;
674}
675#endif
676
677#if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
678extern void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
679#else
680static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
681{
682}
683#endif
684
685#ifdef CONFIG_MEMCG_SWAP
686extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
687extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
688extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
689extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
690extern bool mem_cgroup_swap_full(struct page *page);
691#else
692static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
693{
694}
695
696static inline int mem_cgroup_try_charge_swap(struct page *page,
697 swp_entry_t entry)
698{
699 return 0;
700}
701
702static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
703 unsigned int nr_pages)
704{
705}
706
707static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
708{
709 return get_nr_swap_pages();
710}
711
712static inline bool mem_cgroup_swap_full(struct page *page)
713{
714 return vm_swap_full();
715}
716#endif
717
718#endif /* __KERNEL__*/
719#endif /* _LINUX_SWAP_H */