include/linux/swap.h

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