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