1 /* SPDX-License-Identifier: GPL-2.0 */
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>
13 #include <linux/atomic.h>
14 #include <linux/page-flags.h>
17 struct notifier_block;
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 */
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)
33 static inline int current_is_kswapd(void)
35 return current->flags & PF_KSWAPD;
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.
46 #define MAX_SWAPFILES_SHIFT 5
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
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.
60 * When a page is migrated from CPU to device, we set the CPU page table entry
61 * to a special SWP_DEVICE_* entry.
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)
68 #define SWP_DEVICE_NUM 0
72 * NUMA node memory migration support
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)
79 #define SWP_MIGRATION_NUM 0
83 * Handling of hardware poisoned pages with memory corruption.
85 #ifdef CONFIG_MEMORY_FAILURE
86 #define SWP_HWPOISON_NUM 1
87 #define SWP_HWPOISON MAX_SWAPFILES
89 #define SWP_HWPOISON_NUM 0
92 #define MAX_SWAPFILES \
93 ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
94 SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
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...
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
110 char reserved[PAGE_SIZE - 10];
111 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
114 char bootbits[1024]; /* Space for disklabel etc. */
118 unsigned char sws_uuid[16];
119 unsigned char sws_volume[16];
126 * current->reclaim_state points to one of these when a task is running
129 struct reclaim_state {
130 unsigned long reclaimed_slab;
135 struct address_space;
137 struct writeback_control;
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.
146 * We always assume that blocks are of size PAGE_SIZE.
149 struct list_head list;
152 sector_t start_block;
156 * Max bad pages in the new format..
158 #define MAX_SWAP_BADPAGES \
159 ((offsetof(union swap_header, magic.magic) - \
160 offsetof(union swap_header, info.badpages)) / sizeof(int))
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 /* add others here before... */
175 SWP_SCANNING = (1 << 11), /* refcount in scan_swap_map */
178 #define SWAP_CLUSTER_MAX 32UL
179 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
181 #define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
182 #define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
183 #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
184 #define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
185 #define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
186 #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
189 * We use this to track usage of a cluster. A cluster is a block of swap disk
190 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
191 * free clusters are organized into a list. We fetch an entry from the list to
192 * get a free cluster.
194 * The data field stores next cluster if the cluster is free or cluster usage
195 * counter otherwise. The flags field determines if a cluster is free. This is
196 * protected by swap_info_struct.lock.
198 struct swap_cluster_info {
200 * Protect swap_cluster_info fields
201 * and swap_info_struct->swap_map
202 * elements correspond to the swap
205 unsigned int data:24;
206 unsigned int flags:8;
208 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
209 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
210 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
213 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
214 * its own cluster and swapout sequentially. The purpose is to optimize swapout
217 struct percpu_cluster {
218 struct swap_cluster_info index; /* Current cluster index */
219 unsigned int next; /* Likely next allocation offset */
222 struct swap_cluster_list {
223 struct swap_cluster_info head;
224 struct swap_cluster_info tail;
228 * The in-memory structure used to track swap areas.
230 struct swap_info_struct {
231 unsigned long flags; /* SWP_USED etc: see above */
232 signed short prio; /* swap priority of this type */
233 struct plist_node list; /* entry in swap_active_head */
234 signed char type; /* strange name for an index */
235 unsigned int max; /* extent of the swap_map */
236 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
237 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
238 struct swap_cluster_list free_clusters; /* free clusters list */
239 unsigned int lowest_bit; /* index of first free in swap_map */
240 unsigned int highest_bit; /* index of last free in swap_map */
241 unsigned int pages; /* total of usable pages of swap */
242 unsigned int inuse_pages; /* number of those currently in use */
243 unsigned int cluster_next; /* likely index for next allocation */
244 unsigned int cluster_nr; /* countdown to next cluster search */
245 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
246 struct swap_extent *curr_swap_extent;
247 struct swap_extent first_swap_extent;
248 struct block_device *bdev; /* swap device or bdev of swap file */
249 struct file *swap_file; /* seldom referenced */
250 unsigned int old_block_size; /* seldom referenced */
251 #ifdef CONFIG_FRONTSWAP
252 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
253 atomic_t frontswap_pages; /* frontswap pages in-use counter */
256 * protect map scan related fields like
257 * swap_map, lowest_bit, highest_bit,
258 * inuse_pages, cluster_next,
259 * cluster_nr, lowest_alloc,
260 * highest_alloc, free/discard cluster
261 * list. other fields are only changed
262 * at swapon/swapoff, so are protected
263 * by swap_lock. changing flags need
264 * hold this lock and swap_lock. If
265 * both locks need hold, hold swap_lock
268 spinlock_t cont_lock; /*
269 * protect swap count continuation page
272 struct work_struct discard_work; /* discard worker */
273 struct swap_cluster_list discard_clusters; /* discard clusters list */
274 struct plist_node avail_lists[0]; /*
275 * entries in swap_avail_heads, one
277 * Must be last as the number of the
278 * array is nr_node_ids, which is not
279 * a fixed value so have to allocate
281 * And it has to be an array so that
282 * plist_for_each_* can work.
287 #define SWAP_RA_ORDER_CEILING 5
289 /* Avoid stack overflow, because we need to save part of page table */
290 #define SWAP_RA_ORDER_CEILING 3
291 #define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
294 struct vma_swap_readahead {
296 unsigned short offset;
297 unsigned short nr_pte;
301 pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
305 /* linux/mm/workingset.c */
306 void *workingset_eviction(struct address_space *mapping, struct page *page);
307 bool workingset_refault(void *shadow);
308 void workingset_activation(struct page *page);
309 void workingset_update_node(struct radix_tree_node *node, void *private);
311 /* linux/mm/page_alloc.c */
312 extern unsigned long totalram_pages;
313 extern unsigned long totalreserve_pages;
314 extern unsigned long nr_free_buffer_pages(void);
315 extern unsigned long nr_free_pagecache_pages(void);
317 /* Definition of global_zone_page_state not available yet */
318 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
321 /* linux/mm/swap.c */
322 extern void lru_cache_add(struct page *);
323 extern void lru_cache_add_anon(struct page *page);
324 extern void lru_cache_add_file(struct page *page);
325 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
326 struct lruvec *lruvec, struct list_head *head);
327 extern void activate_page(struct page *);
328 extern void mark_page_accessed(struct page *);
329 extern void lru_add_drain(void);
330 extern void lru_add_drain_cpu(int cpu);
331 extern void lru_add_drain_all(void);
332 extern void lru_add_drain_all_cpuslocked(void);
333 extern void rotate_reclaimable_page(struct page *page);
334 extern void deactivate_file_page(struct page *page);
335 extern void mark_page_lazyfree(struct page *page);
336 extern void swap_setup(void);
338 extern void add_page_to_unevictable_list(struct page *page);
340 extern void lru_cache_add_active_or_unevictable(struct page *page,
341 struct vm_area_struct *vma);
343 /* linux/mm/vmscan.c */
344 extern unsigned long zone_reclaimable_pages(struct zone *zone);
345 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
346 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
347 gfp_t gfp_mask, nodemask_t *mask);
348 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
349 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
350 unsigned long nr_pages,
353 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
354 gfp_t gfp_mask, bool noswap,
356 unsigned long *nr_scanned);
357 extern unsigned long shrink_all_memory(unsigned long nr_pages);
358 extern int vm_swappiness;
359 extern int remove_mapping(struct address_space *mapping, struct page *page);
360 extern unsigned long vm_total_pages;
363 extern int node_reclaim_mode;
364 extern int sysctl_min_unmapped_ratio;
365 extern int sysctl_min_slab_ratio;
367 #define node_reclaim_mode 0
370 extern int page_evictable(struct page *page);
371 extern void check_move_unevictable_pages(struct page **, int nr_pages);
373 extern int kswapd_run(int nid);
374 extern void kswapd_stop(int nid);
378 #include <linux/blk_types.h> /* for bio_end_io_t */
380 /* linux/mm/page_io.c */
381 extern int swap_readpage(struct page *page, bool do_poll);
382 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
383 extern void end_swap_bio_write(struct bio *bio);
384 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
385 bio_end_io_t end_write_func);
386 extern int swap_set_page_dirty(struct page *page);
388 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
389 unsigned long nr_pages, sector_t start_block);
390 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
393 /* linux/mm/swap_state.c */
394 /* One swap address space for each 64M swap space */
395 #define SWAP_ADDRESS_SPACE_SHIFT 14
396 #define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
397 extern struct address_space *swapper_spaces[];
398 extern bool swap_vma_readahead;
399 #define swap_address_space(entry) \
400 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
401 >> SWAP_ADDRESS_SPACE_SHIFT])
402 extern unsigned long total_swapcache_pages(void);
403 extern void show_swap_cache_info(void);
404 extern int add_to_swap(struct page *page);
405 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
406 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
407 extern void __delete_from_swap_cache(struct page *);
408 extern void delete_from_swap_cache(struct page *);
409 extern void free_page_and_swap_cache(struct page *);
410 extern void free_pages_and_swap_cache(struct page **, int);
411 extern struct page *lookup_swap_cache(swp_entry_t entry,
412 struct vm_area_struct *vma,
414 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
415 struct vm_area_struct *vma, unsigned long addr,
417 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
418 struct vm_area_struct *vma, unsigned long addr,
419 bool *new_page_allocated);
420 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
421 struct vm_area_struct *vma, unsigned long addr);
423 extern struct page *swap_readahead_detect(struct vm_fault *vmf,
424 struct vma_swap_readahead *swap_ra);
425 extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
426 struct vm_fault *vmf,
427 struct vma_swap_readahead *swap_ra);
429 /* linux/mm/swapfile.c */
430 extern atomic_long_t nr_swap_pages;
431 extern long total_swap_pages;
432 extern atomic_t nr_rotate_swap;
433 extern bool has_usable_swap(void);
435 static inline bool swap_use_vma_readahead(void)
437 return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
440 /* Swap 50% full? Release swapcache more aggressively.. */
441 static inline bool vm_swap_full(void)
443 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
446 static inline long get_nr_swap_pages(void)
448 return atomic_long_read(&nr_swap_pages);
451 extern void si_swapinfo(struct sysinfo *);
452 extern swp_entry_t get_swap_page(struct page *page);
453 extern void put_swap_page(struct page *page, swp_entry_t entry);
454 extern swp_entry_t get_swap_page_of_type(int);
455 extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
456 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
457 extern void swap_shmem_alloc(swp_entry_t);
458 extern int swap_duplicate(swp_entry_t);
459 extern int swapcache_prepare(swp_entry_t);
460 extern void swap_free(swp_entry_t);
461 extern void swapcache_free_entries(swp_entry_t *entries, int n);
462 extern int free_swap_and_cache(swp_entry_t);
463 extern int swap_type_of(dev_t, sector_t, struct block_device **);
464 extern unsigned int count_swap_pages(int, int);
465 extern sector_t map_swap_page(struct page *, struct block_device **);
466 extern sector_t swapdev_block(int, pgoff_t);
467 extern int page_swapcount(struct page *);
468 extern int __swp_swapcount(swp_entry_t entry);
469 extern int swp_swapcount(swp_entry_t entry);
470 extern struct swap_info_struct *page_swap_info(struct page *);
471 extern bool reuse_swap_page(struct page *, int *);
472 extern int try_to_free_swap(struct page *);
473 struct backing_dev_info;
474 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
475 extern void exit_swap_address_space(unsigned int type);
477 #else /* CONFIG_SWAP */
479 #define swap_address_space(entry) (NULL)
480 #define get_nr_swap_pages() 0L
481 #define total_swap_pages 0L
482 #define total_swapcache_pages() 0UL
483 #define vm_swap_full() 0
485 #define si_swapinfo(val) \
486 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
487 /* only sparc can not include linux/pagemap.h in this file
488 * so leave put_page and release_pages undeclared... */
489 #define free_page_and_swap_cache(page) \
491 #define free_pages_and_swap_cache(pages, nr) \
492 release_pages((pages), (nr), false);
494 static inline void show_swap_cache_info(void)
498 #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
499 #define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
501 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
506 static inline void swap_shmem_alloc(swp_entry_t swp)
510 static inline int swap_duplicate(swp_entry_t swp)
515 static inline void swap_free(swp_entry_t swp)
519 static inline void put_swap_page(struct page *page, swp_entry_t swp)
523 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
524 struct vm_area_struct *vma, unsigned long addr)
529 static inline bool swap_use_vma_readahead(void)
534 static inline struct page *swap_readahead_detect(
535 struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
540 static inline struct page *do_swap_page_readahead(
541 swp_entry_t fentry, gfp_t gfp_mask,
542 struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
547 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
552 static inline struct page *lookup_swap_cache(swp_entry_t swp,
553 struct vm_area_struct *vma,
559 static inline int add_to_swap(struct page *page)
564 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
570 static inline void __delete_from_swap_cache(struct page *page)
574 static inline void delete_from_swap_cache(struct page *page)
578 static inline int page_swapcount(struct page *page)
583 static inline int __swp_swapcount(swp_entry_t entry)
588 static inline int swp_swapcount(swp_entry_t entry)
593 #define reuse_swap_page(page, total_map_swapcount) \
594 (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
596 static inline int try_to_free_swap(struct page *page)
601 static inline swp_entry_t get_swap_page(struct page *page)
608 #endif /* CONFIG_SWAP */
610 #ifdef CONFIG_THP_SWAP
611 extern int split_swap_cluster(swp_entry_t entry);
613 static inline int split_swap_cluster(swp_entry_t entry)
620 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
622 /* Cgroup2 doesn't have per-cgroup swappiness */
623 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
624 return vm_swappiness;
627 if (mem_cgroup_disabled() || !memcg->css.parent)
628 return vm_swappiness;
630 return memcg->swappiness;
634 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
636 return vm_swappiness;
640 #ifdef CONFIG_MEMCG_SWAP
641 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
642 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
643 extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
644 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
645 extern bool mem_cgroup_swap_full(struct page *page);
647 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
651 static inline int mem_cgroup_try_charge_swap(struct page *page,
657 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
658 unsigned int nr_pages)
662 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
664 return get_nr_swap_pages();
667 static inline bool mem_cgroup_swap_full(struct page *page)
669 return vm_swap_full();
673 #endif /* __KERNEL__*/
674 #endif /* _LINUX_SWAP_H */