Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_SWAP_H
3 : #define _LINUX_SWAP_H
4 :
5 : #include <linux/spinlock.h>
6 : #include <linux/linkage.h>
7 : #include <linux/mmzone.h>
8 : #include <linux/list.h>
9 : #include <linux/memcontrol.h>
10 : #include <linux/sched.h>
11 : #include <linux/node.h>
12 : #include <linux/fs.h>
13 : #include <linux/pagemap.h>
14 : #include <linux/atomic.h>
15 : #include <linux/page-flags.h>
16 : #include <uapi/linux/mempolicy.h>
17 : #include <asm/page.h>
18 :
19 : struct notifier_block;
20 :
21 : struct bio;
22 :
23 : struct pagevec;
24 :
25 : #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
26 : #define SWAP_FLAG_PRIO_MASK 0x7fff
27 : #define SWAP_FLAG_PRIO_SHIFT 0
28 : #define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
29 : #define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
30 : #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
31 :
32 : #define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
33 : SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
34 : SWAP_FLAG_DISCARD_PAGES)
35 : #define SWAP_BATCH 64
36 :
37 : static inline int current_is_kswapd(void)
38 : {
39 0 : return current->flags & PF_KSWAPD;
40 : }
41 :
42 : /*
43 : * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
44 : * be swapped to. The swap type and the offset into that swap type are
45 : * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
46 : * for the type means that the maximum number of swapcache pages is 27 bits
47 : * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
48 : * the type/offset into the pte as 5/27 as well.
49 : */
50 : #define MAX_SWAPFILES_SHIFT 5
51 :
52 : /*
53 : * Use some of the swap files numbers for other purposes. This
54 : * is a convenient way to hook into the VM to trigger special
55 : * actions on faults.
56 : */
57 :
58 : /*
59 : * Unaddressable device memory support. See include/linux/hmm.h and
60 : * Documentation/vm/hmm.rst. Short description is we need struct pages for
61 : * device memory that is unaddressable (inaccessible) by CPU, so that we can
62 : * migrate part of a process memory to device memory.
63 : *
64 : * When a page is migrated from CPU to device, we set the CPU page table entry
65 : * to a special SWP_DEVICE_{READ|WRITE} entry.
66 : *
67 : * When a page is mapped by the device for exclusive access we set the CPU page
68 : * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
69 : */
70 : #ifdef CONFIG_DEVICE_PRIVATE
71 : #define SWP_DEVICE_NUM 4
72 : #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
73 : #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
74 : #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
75 : #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
76 : #else
77 : #define SWP_DEVICE_NUM 0
78 : #endif
79 :
80 : /*
81 : * NUMA node memory migration support
82 : */
83 : #ifdef CONFIG_MIGRATION
84 : #define SWP_MIGRATION_NUM 2
85 : #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
86 : #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
87 : #else
88 : #define SWP_MIGRATION_NUM 0
89 : #endif
90 :
91 : /*
92 : * Handling of hardware poisoned pages with memory corruption.
93 : */
94 : #ifdef CONFIG_MEMORY_FAILURE
95 : #define SWP_HWPOISON_NUM 1
96 : #define SWP_HWPOISON MAX_SWAPFILES
97 : #else
98 : #define SWP_HWPOISON_NUM 0
99 : #endif
100 :
101 : #define MAX_SWAPFILES \
102 : ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
103 : SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
104 :
105 : /*
106 : * Magic header for a swap area. The first part of the union is
107 : * what the swap magic looks like for the old (limited to 128MB)
108 : * swap area format, the second part of the union adds - in the
109 : * old reserved area - some extra information. Note that the first
110 : * kilobyte is reserved for boot loader or disk label stuff...
111 : *
112 : * Having the magic at the end of the PAGE_SIZE makes detecting swap
113 : * areas somewhat tricky on machines that support multiple page sizes.
114 : * For 2.5 we'll probably want to move the magic to just beyond the
115 : * bootbits...
116 : */
117 : union swap_header {
118 : struct {
119 : char reserved[PAGE_SIZE - 10];
120 : char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
121 : } magic;
122 : struct {
123 : char bootbits[1024]; /* Space for disklabel etc. */
124 : __u32 version;
125 : __u32 last_page;
126 : __u32 nr_badpages;
127 : unsigned char sws_uuid[16];
128 : unsigned char sws_volume[16];
129 : __u32 padding[117];
130 : __u32 badpages[1];
131 : } info;
132 : };
133 :
134 : /*
135 : * current->reclaim_state points to one of these when a task is running
136 : * memory reclaim
137 : */
138 : struct reclaim_state {
139 : unsigned long reclaimed_slab;
140 : };
141 :
142 : #ifdef __KERNEL__
143 :
144 : struct address_space;
145 : struct sysinfo;
146 : struct writeback_control;
147 : struct zone;
148 :
149 : /*
150 : * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
151 : * disk blocks. A list of swap extents maps the entire swapfile. (Where the
152 : * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
153 : * from setup, they're handled identically.
154 : *
155 : * We always assume that blocks are of size PAGE_SIZE.
156 : */
157 : struct swap_extent {
158 : struct rb_node rb_node;
159 : pgoff_t start_page;
160 : pgoff_t nr_pages;
161 : sector_t start_block;
162 : };
163 :
164 : /*
165 : * Max bad pages in the new format..
166 : */
167 : #define MAX_SWAP_BADPAGES \
168 : ((offsetof(union swap_header, magic.magic) - \
169 : offsetof(union swap_header, info.badpages)) / sizeof(int))
170 :
171 : enum {
172 : SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
173 : SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
174 : SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
175 : SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
176 : SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
177 : SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
178 : SWP_BLKDEV = (1 << 6), /* its a block device */
179 : SWP_ACTIVATED = (1 << 7), /* set after swap_activate success */
180 : SWP_FS_OPS = (1 << 8), /* swapfile operations go through fs */
181 : SWP_AREA_DISCARD = (1 << 9), /* single-time swap area discards */
182 : SWP_PAGE_DISCARD = (1 << 10), /* freed swap page-cluster discards */
183 : SWP_STABLE_WRITES = (1 << 11), /* no overwrite PG_writeback pages */
184 : SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */
185 : /* add others here before... */
186 : SWP_SCANNING = (1 << 14), /* refcount in scan_swap_map */
187 : };
188 :
189 : #define SWAP_CLUSTER_MAX 32UL
190 : #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
191 :
192 : /* Bit flag in swap_map */
193 : #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
194 : #define COUNT_CONTINUED 0x80 /* Flag swap_map continuation for full count */
195 :
196 : /* Special value in first swap_map */
197 : #define SWAP_MAP_MAX 0x3e /* Max count */
198 : #define SWAP_MAP_BAD 0x3f /* Note page is bad */
199 : #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs */
200 :
201 : /* Special value in each swap_map continuation */
202 : #define SWAP_CONT_MAX 0x7f /* Max count */
203 :
204 : /*
205 : * We use this to track usage of a cluster. A cluster is a block of swap disk
206 : * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
207 : * free clusters are organized into a list. We fetch an entry from the list to
208 : * get a free cluster.
209 : *
210 : * The data field stores next cluster if the cluster is free or cluster usage
211 : * counter otherwise. The flags field determines if a cluster is free. This is
212 : * protected by swap_info_struct.lock.
213 : */
214 : struct swap_cluster_info {
215 : spinlock_t lock; /*
216 : * Protect swap_cluster_info fields
217 : * and swap_info_struct->swap_map
218 : * elements correspond to the swap
219 : * cluster
220 : */
221 : unsigned int data:24;
222 : unsigned int flags:8;
223 : };
224 : #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
225 : #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
226 : #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
227 :
228 : /*
229 : * We assign a cluster to each CPU, so each CPU can allocate swap entry from
230 : * its own cluster and swapout sequentially. The purpose is to optimize swapout
231 : * throughput.
232 : */
233 : struct percpu_cluster {
234 : struct swap_cluster_info index; /* Current cluster index */
235 : unsigned int next; /* Likely next allocation offset */
236 : };
237 :
238 : struct swap_cluster_list {
239 : struct swap_cluster_info head;
240 : struct swap_cluster_info tail;
241 : };
242 :
243 : /*
244 : * The in-memory structure used to track swap areas.
245 : */
246 : struct swap_info_struct {
247 : struct percpu_ref users; /* indicate and keep swap device valid. */
248 : unsigned long flags; /* SWP_USED etc: see above */
249 : signed short prio; /* swap priority of this type */
250 : struct plist_node list; /* entry in swap_active_head */
251 : signed char type; /* strange name for an index */
252 : unsigned int max; /* extent of the swap_map */
253 : unsigned char *swap_map; /* vmalloc'ed array of usage counts */
254 : struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
255 : struct swap_cluster_list free_clusters; /* free clusters list */
256 : unsigned int lowest_bit; /* index of first free in swap_map */
257 : unsigned int highest_bit; /* index of last free in swap_map */
258 : unsigned int pages; /* total of usable pages of swap */
259 : unsigned int inuse_pages; /* number of those currently in use */
260 : unsigned int cluster_next; /* likely index for next allocation */
261 : unsigned int cluster_nr; /* countdown to next cluster search */
262 : unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
263 : struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
264 : struct rb_root swap_extent_root;/* root of the swap extent rbtree */
265 : struct block_device *bdev; /* swap device or bdev of swap file */
266 : struct file *swap_file; /* seldom referenced */
267 : unsigned int old_block_size; /* seldom referenced */
268 : struct completion comp; /* seldom referenced */
269 : #ifdef CONFIG_FRONTSWAP
270 : unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
271 : atomic_t frontswap_pages; /* frontswap pages in-use counter */
272 : #endif
273 : spinlock_t lock; /*
274 : * protect map scan related fields like
275 : * swap_map, lowest_bit, highest_bit,
276 : * inuse_pages, cluster_next,
277 : * cluster_nr, lowest_alloc,
278 : * highest_alloc, free/discard cluster
279 : * list. other fields are only changed
280 : * at swapon/swapoff, so are protected
281 : * by swap_lock. changing flags need
282 : * hold this lock and swap_lock. If
283 : * both locks need hold, hold swap_lock
284 : * first.
285 : */
286 : spinlock_t cont_lock; /*
287 : * protect swap count continuation page
288 : * list.
289 : */
290 : struct work_struct discard_work; /* discard worker */
291 : struct swap_cluster_list discard_clusters; /* discard clusters list */
292 : struct plist_node avail_lists[]; /*
293 : * entries in swap_avail_heads, one
294 : * entry per node.
295 : * Must be last as the number of the
296 : * array is nr_node_ids, which is not
297 : * a fixed value so have to allocate
298 : * dynamically.
299 : * And it has to be an array so that
300 : * plist_for_each_* can work.
301 : */
302 : };
303 :
304 : #ifdef CONFIG_64BIT
305 : #define SWAP_RA_ORDER_CEILING 5
306 : #else
307 : /* Avoid stack overflow, because we need to save part of page table */
308 : #define SWAP_RA_ORDER_CEILING 3
309 : #define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
310 : #endif
311 :
312 : struct vma_swap_readahead {
313 : unsigned short win;
314 : unsigned short offset;
315 : unsigned short nr_pte;
316 : #ifdef CONFIG_64BIT
317 : pte_t *ptes;
318 : #else
319 : pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
320 : #endif
321 : };
322 :
323 : static inline swp_entry_t folio_swap_entry(struct folio *folio)
324 : {
325 0 : swp_entry_t entry = { .val = page_private(&folio->page) };
326 : return entry;
327 : }
328 :
329 : /* linux/mm/workingset.c */
330 : void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
331 : void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
332 : void workingset_refault(struct folio *folio, void *shadow);
333 : void workingset_activation(struct folio *folio);
334 :
335 : /* Only track the nodes of mappings with shadow entries */
336 : void workingset_update_node(struct xa_node *node);
337 : extern struct list_lru shadow_nodes;
338 : #define mapping_set_update(xas, mapping) do { \
339 : if (!dax_mapping(mapping) && !shmem_mapping(mapping)) { \
340 : xas_set_update(xas, workingset_update_node); \
341 : xas_set_lru(xas, &shadow_nodes); \
342 : } \
343 : } while (0)
344 :
345 : /* linux/mm/page_alloc.c */
346 : extern unsigned long totalreserve_pages;
347 :
348 : /* Definition of global_zone_page_state not available yet */
349 : #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
350 :
351 :
352 : /* linux/mm/swap.c */
353 : extern void lru_note_cost(struct lruvec *lruvec, bool file,
354 : unsigned int nr_pages);
355 : extern void lru_note_cost_folio(struct folio *);
356 : extern void folio_add_lru(struct folio *);
357 : extern void lru_cache_add(struct page *);
358 : void mark_page_accessed(struct page *);
359 : void folio_mark_accessed(struct folio *);
360 :
361 : extern atomic_t lru_disable_count;
362 :
363 : static inline bool lru_cache_disabled(void)
364 : {
365 0 : return atomic_read(&lru_disable_count);
366 : }
367 :
368 : static inline void lru_cache_enable(void)
369 : {
370 : atomic_dec(&lru_disable_count);
371 : }
372 :
373 : extern void lru_cache_disable(void);
374 : extern void lru_add_drain(void);
375 : extern void lru_add_drain_cpu(int cpu);
376 : extern void lru_add_drain_cpu_zone(struct zone *zone);
377 : extern void lru_add_drain_all(void);
378 : extern void deactivate_page(struct page *page);
379 : extern void mark_page_lazyfree(struct page *page);
380 : extern void swap_setup(void);
381 :
382 : extern void lru_cache_add_inactive_or_unevictable(struct page *page,
383 : struct vm_area_struct *vma);
384 :
385 : /* linux/mm/vmscan.c */
386 : extern unsigned long zone_reclaimable_pages(struct zone *zone);
387 : extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
388 : gfp_t gfp_mask, nodemask_t *mask);
389 : extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
390 : unsigned long nr_pages,
391 : gfp_t gfp_mask,
392 : bool may_swap);
393 : extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
394 : gfp_t gfp_mask, bool noswap,
395 : pg_data_t *pgdat,
396 : unsigned long *nr_scanned);
397 : extern unsigned long shrink_all_memory(unsigned long nr_pages);
398 : extern int vm_swappiness;
399 : long remove_mapping(struct address_space *mapping, struct folio *folio);
400 :
401 : extern unsigned long reclaim_pages(struct list_head *page_list);
402 : #ifdef CONFIG_NUMA
403 : extern int node_reclaim_mode;
404 : extern int sysctl_min_unmapped_ratio;
405 : extern int sysctl_min_slab_ratio;
406 : #else
407 : #define node_reclaim_mode 0
408 : #endif
409 :
410 : static inline bool node_reclaim_enabled(void)
411 : {
412 : /* Is any node_reclaim_mode bit set? */
413 : return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
414 : }
415 :
416 : extern void check_move_unevictable_pages(struct pagevec *pvec);
417 :
418 : extern void kswapd_run(int nid);
419 : extern void kswapd_stop(int nid);
420 :
421 : #ifdef CONFIG_SWAP
422 :
423 : #include <linux/blk_types.h> /* for bio_end_io_t */
424 :
425 : /* linux/mm/page_io.c */
426 : extern int swap_readpage(struct page *page, bool do_poll);
427 : extern int swap_writepage(struct page *page, struct writeback_control *wbc);
428 : extern void end_swap_bio_write(struct bio *bio);
429 : extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
430 : bio_end_io_t end_write_func);
431 : bool swap_dirty_folio(struct address_space *mapping, struct folio *folio);
432 :
433 : int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
434 : unsigned long nr_pages, sector_t start_block);
435 : int generic_swapfile_activate(struct swap_info_struct *, struct file *,
436 : sector_t *);
437 :
438 : /* linux/mm/swap_state.c */
439 : /* One swap address space for each 64M swap space */
440 : #define SWAP_ADDRESS_SPACE_SHIFT 14
441 : #define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
442 : extern struct address_space *swapper_spaces[];
443 : #define swap_address_space(entry) \
444 : (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
445 : >> SWAP_ADDRESS_SPACE_SHIFT])
446 : static inline unsigned long total_swapcache_pages(void)
447 : {
448 0 : return global_node_page_state(NR_SWAPCACHE);
449 : }
450 :
451 : extern void show_swap_cache_info(void);
452 : extern int add_to_swap(struct page *page);
453 : extern void *get_shadow_from_swap_cache(swp_entry_t entry);
454 : extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
455 : gfp_t gfp, void **shadowp);
456 : extern void __delete_from_swap_cache(struct page *page,
457 : swp_entry_t entry, void *shadow);
458 : extern void delete_from_swap_cache(struct page *);
459 : extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
460 : unsigned long end);
461 : extern void free_swap_cache(struct page *);
462 : extern void free_page_and_swap_cache(struct page *);
463 : extern void free_pages_and_swap_cache(struct page **, int);
464 : extern struct page *lookup_swap_cache(swp_entry_t entry,
465 : struct vm_area_struct *vma,
466 : unsigned long addr);
467 : struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
468 : extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
469 : struct vm_area_struct *vma, unsigned long addr,
470 : bool do_poll);
471 : extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
472 : struct vm_area_struct *vma, unsigned long addr,
473 : bool *new_page_allocated);
474 : extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
475 : struct vm_fault *vmf);
476 : extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
477 : struct vm_fault *vmf);
478 :
479 : /* linux/mm/swapfile.c */
480 : extern atomic_long_t nr_swap_pages;
481 : extern long total_swap_pages;
482 : extern atomic_t nr_rotate_swap;
483 : extern bool has_usable_swap(void);
484 :
485 : /* Swap 50% full? Release swapcache more aggressively.. */
486 : static inline bool vm_swap_full(void)
487 : {
488 0 : return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
489 : }
490 :
491 : static inline long get_nr_swap_pages(void)
492 : {
493 0 : return atomic_long_read(&nr_swap_pages);
494 : }
495 :
496 : extern void si_swapinfo(struct sysinfo *);
497 : extern swp_entry_t get_swap_page(struct page *page);
498 : extern void put_swap_page(struct page *page, swp_entry_t entry);
499 : extern swp_entry_t get_swap_page_of_type(int);
500 : extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
501 : extern int add_swap_count_continuation(swp_entry_t, gfp_t);
502 : extern void swap_shmem_alloc(swp_entry_t);
503 : extern int swap_duplicate(swp_entry_t);
504 : extern int swapcache_prepare(swp_entry_t);
505 : extern void swap_free(swp_entry_t);
506 : extern void swapcache_free_entries(swp_entry_t *entries, int n);
507 : extern int free_swap_and_cache(swp_entry_t);
508 : int swap_type_of(dev_t device, sector_t offset);
509 : int find_first_swap(dev_t *device);
510 : extern unsigned int count_swap_pages(int, int);
511 : extern sector_t swapdev_block(int, pgoff_t);
512 : extern int page_swapcount(struct page *);
513 : extern int __swap_count(swp_entry_t entry);
514 : extern int __swp_swapcount(swp_entry_t entry);
515 : extern int swp_swapcount(swp_entry_t entry);
516 : extern struct swap_info_struct *page_swap_info(struct page *);
517 : extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
518 : extern int try_to_free_swap(struct page *);
519 : struct backing_dev_info;
520 : extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
521 : extern void exit_swap_address_space(unsigned int type);
522 : extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
523 : sector_t swap_page_sector(struct page *page);
524 :
525 : static inline void put_swap_device(struct swap_info_struct *si)
526 : {
527 0 : percpu_ref_put(&si->users);
528 : }
529 :
530 : #else /* CONFIG_SWAP */
531 :
532 : static inline int swap_readpage(struct page *page, bool do_poll)
533 : {
534 : return 0;
535 : }
536 :
537 : static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
538 : {
539 : return NULL;
540 : }
541 :
542 : static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
543 : {
544 : return NULL;
545 : }
546 :
547 : static inline void put_swap_device(struct swap_info_struct *si)
548 : {
549 : }
550 :
551 : static inline struct address_space *swap_address_space(swp_entry_t entry)
552 : {
553 : return NULL;
554 : }
555 :
556 : #define get_nr_swap_pages() 0L
557 : #define total_swap_pages 0L
558 : #define total_swapcache_pages() 0UL
559 : #define vm_swap_full() 0
560 :
561 : #define si_swapinfo(val) \
562 : do { (val)->freeswap = (val)->totalswap = 0; } while (0)
563 : /* only sparc can not include linux/pagemap.h in this file
564 : * so leave put_page and release_pages undeclared... */
565 : #define free_page_and_swap_cache(page) \
566 : put_page(page)
567 : #define free_pages_and_swap_cache(pages, nr) \
568 : release_pages((pages), (nr));
569 :
570 : static inline void free_swap_cache(struct page *page)
571 : {
572 : }
573 :
574 : static inline void show_swap_cache_info(void)
575 : {
576 : }
577 :
578 : /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
579 : #define free_swap_and_cache(e) is_pfn_swap_entry(e)
580 :
581 : static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
582 : {
583 : return 0;
584 : }
585 :
586 : static inline void swap_shmem_alloc(swp_entry_t swp)
587 : {
588 : }
589 :
590 : static inline int swap_duplicate(swp_entry_t swp)
591 : {
592 : return 0;
593 : }
594 :
595 : static inline void swap_free(swp_entry_t swp)
596 : {
597 : }
598 :
599 : static inline void put_swap_page(struct page *page, swp_entry_t swp)
600 : {
601 : }
602 :
603 : static inline struct page *swap_cluster_readahead(swp_entry_t entry,
604 : gfp_t gfp_mask, struct vm_fault *vmf)
605 : {
606 : return NULL;
607 : }
608 :
609 : static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
610 : struct vm_fault *vmf)
611 : {
612 : return NULL;
613 : }
614 :
615 : static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
616 : {
617 : return 0;
618 : }
619 :
620 : static inline struct page *lookup_swap_cache(swp_entry_t swp,
621 : struct vm_area_struct *vma,
622 : unsigned long addr)
623 : {
624 : return NULL;
625 : }
626 :
627 : static inline
628 : struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
629 : {
630 : return find_get_page(mapping, index);
631 : }
632 :
633 : static inline int add_to_swap(struct page *page)
634 : {
635 : return 0;
636 : }
637 :
638 : static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
639 : {
640 : return NULL;
641 : }
642 :
643 : static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
644 : gfp_t gfp_mask, void **shadowp)
645 : {
646 : return -1;
647 : }
648 :
649 : static inline void __delete_from_swap_cache(struct page *page,
650 : swp_entry_t entry, void *shadow)
651 : {
652 : }
653 :
654 : static inline void delete_from_swap_cache(struct page *page)
655 : {
656 : }
657 :
658 : static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
659 : unsigned long end)
660 : {
661 : }
662 :
663 : static inline int page_swapcount(struct page *page)
664 : {
665 : return 0;
666 : }
667 :
668 : static inline int __swap_count(swp_entry_t entry)
669 : {
670 : return 0;
671 : }
672 :
673 : static inline int __swp_swapcount(swp_entry_t entry)
674 : {
675 : return 0;
676 : }
677 :
678 : static inline int swp_swapcount(swp_entry_t entry)
679 : {
680 : return 0;
681 : }
682 :
683 : static inline int try_to_free_swap(struct page *page)
684 : {
685 : return 0;
686 : }
687 :
688 : static inline swp_entry_t get_swap_page(struct page *page)
689 : {
690 : swp_entry_t entry;
691 : entry.val = 0;
692 : return entry;
693 : }
694 :
695 : #endif /* CONFIG_SWAP */
696 :
697 : #ifdef CONFIG_THP_SWAP
698 : extern int split_swap_cluster(swp_entry_t entry);
699 : #else
700 : static inline int split_swap_cluster(swp_entry_t entry)
701 : {
702 : return 0;
703 : }
704 : #endif
705 :
706 : #ifdef CONFIG_MEMCG
707 : static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
708 : {
709 : /* Cgroup2 doesn't have per-cgroup swappiness */
710 : if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
711 : return vm_swappiness;
712 :
713 : /* root ? */
714 : if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
715 : return vm_swappiness;
716 :
717 : return memcg->swappiness;
718 : }
719 : #else
720 : static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
721 : {
722 0 : return vm_swappiness;
723 : }
724 : #endif
725 :
726 : #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
727 : extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
728 : static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
729 : {
730 : if (mem_cgroup_disabled())
731 : return;
732 : __cgroup_throttle_swaprate(page, gfp_mask);
733 : }
734 : #else
735 : static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
736 : {
737 : }
738 : #endif
739 :
740 : #ifdef CONFIG_MEMCG_SWAP
741 : void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
742 : extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
743 : static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
744 : {
745 : if (mem_cgroup_disabled())
746 : return 0;
747 : return __mem_cgroup_try_charge_swap(page, entry);
748 : }
749 :
750 : extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
751 : static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
752 : {
753 : if (mem_cgroup_disabled())
754 : return;
755 : __mem_cgroup_uncharge_swap(entry, nr_pages);
756 : }
757 :
758 : extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
759 : extern bool mem_cgroup_swap_full(struct page *page);
760 : #else
761 : static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
762 : {
763 : }
764 :
765 : static inline int mem_cgroup_try_charge_swap(struct page *page,
766 : swp_entry_t entry)
767 : {
768 : return 0;
769 : }
770 :
771 : static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
772 : unsigned int nr_pages)
773 : {
774 : }
775 :
776 : static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
777 : {
778 : return get_nr_swap_pages();
779 : }
780 :
781 : static inline bool mem_cgroup_swap_full(struct page *page)
782 : {
783 : return vm_swap_full();
784 : }
785 : #endif
786 :
787 : #endif /* __KERNEL__*/
788 : #endif /* _LINUX_SWAP_H */
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