include/linux/swap.h

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