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