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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.txt. 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 lru_add_drain_all_cpuslocked(void);
336extern void rotate_reclaimable_page(struct page *page);
337extern void deactivate_file_page(struct page *page);
338extern void mark_page_lazyfree(struct page *page);
339extern void swap_setup(void);
340
341extern void add_page_to_unevictable_list(struct page *page);
342
343extern void lru_cache_add_active_or_unevictable(struct page *page,
344 struct vm_area_struct *vma);
345
346/* linux/mm/vmscan.c */
347extern unsigned long zone_reclaimable_pages(struct zone *zone);
348extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
349extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
350 gfp_t gfp_mask, nodemask_t *mask);
351extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
352extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
353 unsigned long nr_pages,
354 gfp_t gfp_mask,
355 bool may_swap);
356extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
357 gfp_t gfp_mask, bool noswap,
358 pg_data_t *pgdat,
359 unsigned long *nr_scanned);
360extern unsigned long shrink_all_memory(unsigned long nr_pages);
361extern int vm_swappiness;
362extern int remove_mapping(struct address_space *mapping, struct page *page);
363extern unsigned long vm_total_pages;
364
365#ifdef CONFIG_NUMA
366extern int node_reclaim_mode;
367extern int sysctl_min_unmapped_ratio;
368extern int sysctl_min_slab_ratio;
369extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
370#else
371#define node_reclaim_mode 0
372static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
373 unsigned int order)
374{
375 return 0;
376}
377#endif
378
379extern int page_evictable(struct page *page);
380extern void check_move_unevictable_pages(struct page **, int nr_pages);
381
382extern int kswapd_run(int nid);
383extern void kswapd_stop(int nid);
384
385#ifdef CONFIG_SWAP
386
387#include <linux/blk_types.h> /* for bio_end_io_t */
388
389/* linux/mm/page_io.c */
390extern int swap_readpage(struct page *page, bool do_poll);
391extern int swap_writepage(struct page *page, struct writeback_control *wbc);
392extern void end_swap_bio_write(struct bio *bio);
393extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
394 bio_end_io_t end_write_func);
395extern int swap_set_page_dirty(struct page *page);
396
397int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
398 unsigned long nr_pages, sector_t start_block);
399int generic_swapfile_activate(struct swap_info_struct *, struct file *,
400 sector_t *);
401
402/* linux/mm/swap_state.c */
403/* One swap address space for each 64M swap space */
404#define SWAP_ADDRESS_SPACE_SHIFT 14
405#define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
406extern struct address_space *swapper_spaces[];
407extern bool swap_vma_readahead;
408#define swap_address_space(entry) \
409 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
410 >> SWAP_ADDRESS_SPACE_SHIFT])
411extern unsigned long total_swapcache_pages(void);
412extern void show_swap_cache_info(void);
413extern int add_to_swap(struct page *page);
414extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
415extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
416extern void __delete_from_swap_cache(struct page *);
417extern void delete_from_swap_cache(struct page *);
418extern void free_page_and_swap_cache(struct page *);
419extern void free_pages_and_swap_cache(struct page **, int);
420extern struct page *lookup_swap_cache(swp_entry_t entry,
421 struct vm_area_struct *vma,
422 unsigned long addr);
423extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
424 struct vm_area_struct *vma, unsigned long addr,
425 bool do_poll);
426extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
427 struct vm_area_struct *vma, unsigned long addr,
428 bool *new_page_allocated);
429extern struct page *swapin_readahead(swp_entry_t, gfp_t,
430 struct vm_area_struct *vma, unsigned long addr);
431
432extern struct page *swap_readahead_detect(struct vm_fault *vmf,
433 struct vma_swap_readahead *swap_ra);
434extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
435 struct vm_fault *vmf,
436 struct vma_swap_readahead *swap_ra);
437
438/* linux/mm/swapfile.c */
439extern atomic_long_t nr_swap_pages;
440extern long total_swap_pages;
441extern atomic_t nr_rotate_swap;
442extern bool has_usable_swap(void);
443
444static inline bool swap_use_vma_readahead(void)
445{
446 return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
447}
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, bool cluster, swp_entry_t swp_entries[]);
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);
472extern int swap_type_of(dev_t, sector_t, struct block_device **);
473extern unsigned int count_swap_pages(int, int);
474extern sector_t map_swap_page(struct page *, struct block_device **);
475extern sector_t swapdev_block(int, pgoff_t);
476extern int page_swapcount(struct page *);
477extern int __swap_count(struct swap_info_struct *si, 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);
487
488#else /* CONFIG_SWAP */
489
490static inline int swap_readpage(struct page *page, bool do_poll)
491{
492 return 0;
493}
494
495static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
496{
497 return NULL;
498}
499
500#define swap_address_space(entry) (NULL)
501#define get_nr_swap_pages() 0L
502#define total_swap_pages 0L
503#define total_swapcache_pages() 0UL
504#define vm_swap_full() 0
505
506#define si_swapinfo(val) \
507 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
508/* only sparc can not include linux/pagemap.h in this file
509 * so leave put_page and release_pages undeclared... */
510#define free_page_and_swap_cache(page) \
511 put_page(page)
512#define free_pages_and_swap_cache(pages, nr) \
513 release_pages((pages), (nr));
514
515static inline void show_swap_cache_info(void)
516{
517}
518
519#define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
520#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
521
522static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
523{
524 return 0;
525}
526
527static inline void swap_shmem_alloc(swp_entry_t swp)
528{
529}
530
531static inline int swap_duplicate(swp_entry_t swp)
532{
533 return 0;
534}
535
536static inline void swap_free(swp_entry_t swp)
537{
538}
539
540static inline void put_swap_page(struct page *page, swp_entry_t swp)
541{
542}
543
544static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
545 struct vm_area_struct *vma, unsigned long addr)
546{
547 return NULL;
548}
549
550static inline bool swap_use_vma_readahead(void)
551{
552 return false;
553}
554
555static inline struct page *swap_readahead_detect(
556 struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
557{
558 return NULL;
559}
560
561static inline struct page *do_swap_page_readahead(
562 swp_entry_t fentry, gfp_t gfp_mask,
563 struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
564{
565 return NULL;
566}
567
568static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
569{
570 return 0;
571}
572
573static inline struct page *lookup_swap_cache(swp_entry_t swp,
574 struct vm_area_struct *vma,
575 unsigned long addr)
576{
577 return NULL;
578}
579
580static inline int add_to_swap(struct page *page)
581{
582 return 0;
583}
584
585static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
586 gfp_t gfp_mask)
587{
588 return -1;
589}
590
591static inline void __delete_from_swap_cache(struct page *page)
592{
593}
594
595static inline void delete_from_swap_cache(struct page *page)
596{
597}
598
599static inline int page_swapcount(struct page *page)
600{
601 return 0;
602}
603
604static inline int __swap_count(struct swap_info_struct *si, swp_entry_t entry)
605{
606 return 0;
607}
608
609static inline int __swp_swapcount(swp_entry_t entry)
610{
611 return 0;
612}
613
614static inline int swp_swapcount(swp_entry_t entry)
615{
616 return 0;
617}
618
619#define reuse_swap_page(page, total_map_swapcount) \
620 (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
621
622static inline int try_to_free_swap(struct page *page)
623{
624 return 0;
625}
626
627static inline swp_entry_t get_swap_page(struct page *page)
628{
629 swp_entry_t entry;
630 entry.val = 0;
631 return entry;
632}
633
634#endif /* CONFIG_SWAP */
635
636#ifdef CONFIG_THP_SWAP
637extern int split_swap_cluster(swp_entry_t entry);
638#else
639static inline int split_swap_cluster(swp_entry_t entry)
640{
641 return 0;
642}
643#endif
644
645#ifdef CONFIG_MEMCG
646static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
647{
648 /* Cgroup2 doesn't have per-cgroup swappiness */
649 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
650 return vm_swappiness;
651
652 /* root ? */
653 if (mem_cgroup_disabled() || !memcg->css.parent)
654 return vm_swappiness;
655
656 return memcg->swappiness;
657}
658
659#else
660static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
661{
662 return vm_swappiness;
663}
664#endif
665
666#ifdef CONFIG_MEMCG_SWAP
667extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
668extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
669extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
670extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
671extern bool mem_cgroup_swap_full(struct page *page);
672#else
673static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
674{
675}
676
677static inline int mem_cgroup_try_charge_swap(struct page *page,
678 swp_entry_t entry)
679{
680 return 0;
681}
682
683static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
684 unsigned int nr_pages)
685{
686}
687
688static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
689{
690 return get_nr_swap_pages();
691}
692
693static inline bool mem_cgroup_swap_full(struct page *page)
694{
695 return vm_swap_full();
696}
697#endif
698
699#endif /* __KERNEL__*/
700#endif /* _LINUX_SWAP_H */