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