1 #ifndef _LINUX_SWAP_H 2 #define _LINUX_SWAP_H 3 4 #include <linux/spinlock.h> 5 #include <linux/linkage.h> 6 #include <linux/mmzone.h> 7 #include <linux/list.h> 8 #include <linux/memcontrol.h> 9 #include <linux/sched.h> 10 #include <linux/node.h> 11 #include <linux/fs.h> 12 #include <linux/atomic.h> 13 #include <linux/page-flags.h> 14 #include <asm/page.h> 15 16 struct notifier_block; 17 18 struct bio; 19 20 #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */ 21 #define SWAP_FLAG_PRIO_MASK 0x7fff 22 #define SWAP_FLAG_PRIO_SHIFT 0 23 #define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */ 24 #define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */ 25 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */ 26 27 #define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \ 28 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \ 29 SWAP_FLAG_DISCARD_PAGES) 30 31 static inline int current_is_kswapd(void) 32 { 33 return current->flags & PF_KSWAPD; 34 } 35 36 /* 37 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can 38 * be swapped to. The swap type and the offset into that swap type are 39 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits 40 * for the type means that the maximum number of swapcache pages is 27 bits 41 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs 42 * the type/offset into the pte as 5/27 as well. 43 */ 44 #define MAX_SWAPFILES_SHIFT 5 45 46 /* 47 * Use some of the swap files numbers for other purposes. This 48 * is a convenient way to hook into the VM to trigger special 49 * actions on faults. 50 */ 51 52 /* 53 * NUMA node memory migration support 54 */ 55 #ifdef CONFIG_MIGRATION 56 #define SWP_MIGRATION_NUM 2 57 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM) 58 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1) 59 #else 60 #define SWP_MIGRATION_NUM 0 61 #endif 62 63 /* 64 * Handling of hardware poisoned pages with memory corruption. 65 */ 66 #ifdef CONFIG_MEMORY_FAILURE 67 #define SWP_HWPOISON_NUM 1 68 #define SWP_HWPOISON MAX_SWAPFILES 69 #else 70 #define SWP_HWPOISON_NUM 0 71 #endif 72 73 #define MAX_SWAPFILES \ 74 ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM) 75 76 /* 77 * Magic header for a swap area. The first part of the union is 78 * what the swap magic looks like for the old (limited to 128MB) 79 * swap area format, the second part of the union adds - in the 80 * old reserved area - some extra information. Note that the first 81 * kilobyte is reserved for boot loader or disk label stuff... 82 * 83 * Having the magic at the end of the PAGE_SIZE makes detecting swap 84 * areas somewhat tricky on machines that support multiple page sizes. 85 * For 2.5 we'll probably want to move the magic to just beyond the 86 * bootbits... 87 */ 88 union swap_header { 89 struct { 90 char reserved[PAGE_SIZE - 10]; 91 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */ 92 } magic; 93 struct { 94 char bootbits[1024]; /* Space for disklabel etc. */ 95 __u32 version; 96 __u32 last_page; 97 __u32 nr_badpages; 98 unsigned char sws_uuid[16]; 99 unsigned char sws_volume[16]; 100 __u32 padding[117]; 101 __u32 badpages[1]; 102 } info; 103 }; 104 105 /* 106 * current->reclaim_state points to one of these when a task is running 107 * memory reclaim 108 */ 109 struct reclaim_state { 110 unsigned long reclaimed_slab; 111 }; 112 113 #ifdef __KERNEL__ 114 115 struct address_space; 116 struct sysinfo; 117 struct writeback_control; 118 struct zone; 119 120 /* 121 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of 122 * disk blocks. A list of swap extents maps the entire swapfile. (Where the 123 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart 124 * from setup, they're handled identically. 125 * 126 * We always assume that blocks are of size PAGE_SIZE. 127 */ 128 struct swap_extent { 129 struct list_head list; 130 pgoff_t start_page; 131 pgoff_t nr_pages; 132 sector_t start_block; 133 }; 134 135 /* 136 * Max bad pages in the new format.. 137 */ 138 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x) 139 #define MAX_SWAP_BADPAGES \ 140 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int)) 141 142 enum { 143 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */ 144 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */ 145 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */ 146 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */ 147 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */ 148 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */ 149 SWP_BLKDEV = (1 << 6), /* its a block device */ 150 SWP_FILE = (1 << 7), /* set after swap_activate success */ 151 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */ 152 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */ 153 /* add others here before... */ 154 SWP_SCANNING = (1 << 10), /* refcount in scan_swap_map */ 155 }; 156 157 #define SWAP_CLUSTER_MAX 32UL 158 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX 159 160 #define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */ 161 #define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */ 162 #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */ 163 #define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */ 164 #define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */ 165 #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */ 166 167 /* 168 * We use this to track usage of a cluster. A cluster is a block of swap disk 169 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All 170 * free clusters are organized into a list. We fetch an entry from the list to 171 * get a free cluster. 172 * 173 * The data field stores next cluster if the cluster is free or cluster usage 174 * counter otherwise. The flags field determines if a cluster is free. This is 175 * protected by swap_info_struct.lock. 176 */ 177 struct swap_cluster_info { 178 unsigned int data:24; 179 unsigned int flags:8; 180 }; 181 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */ 182 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */ 183 184 /* 185 * We assign a cluster to each CPU, so each CPU can allocate swap entry from 186 * its own cluster and swapout sequentially. The purpose is to optimize swapout 187 * throughput. 188 */ 189 struct percpu_cluster { 190 struct swap_cluster_info index; /* Current cluster index */ 191 unsigned int next; /* Likely next allocation offset */ 192 }; 193 194 /* 195 * The in-memory structure used to track swap areas. 196 */ 197 struct swap_info_struct { 198 unsigned long flags; /* SWP_USED etc: see above */ 199 signed short prio; /* swap priority of this type */ 200 struct plist_node list; /* entry in swap_active_head */ 201 struct plist_node avail_list; /* entry in swap_avail_head */ 202 signed char type; /* strange name for an index */ 203 unsigned int max; /* extent of the swap_map */ 204 unsigned char *swap_map; /* vmalloc'ed array of usage counts */ 205 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ 206 struct swap_cluster_info free_cluster_head; /* free cluster list head */ 207 struct swap_cluster_info free_cluster_tail; /* free cluster list tail */ 208 unsigned int lowest_bit; /* index of first free in swap_map */ 209 unsigned int highest_bit; /* index of last free in swap_map */ 210 unsigned int pages; /* total of usable pages of swap */ 211 unsigned int inuse_pages; /* number of those currently in use */ 212 unsigned int cluster_next; /* likely index for next allocation */ 213 unsigned int cluster_nr; /* countdown to next cluster search */ 214 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */ 215 struct swap_extent *curr_swap_extent; 216 struct swap_extent first_swap_extent; 217 struct block_device *bdev; /* swap device or bdev of swap file */ 218 struct file *swap_file; /* seldom referenced */ 219 unsigned int old_block_size; /* seldom referenced */ 220 #ifdef CONFIG_FRONTSWAP 221 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ 222 atomic_t frontswap_pages; /* frontswap pages in-use counter */ 223 #endif 224 spinlock_t lock; /* 225 * protect map scan related fields like 226 * swap_map, lowest_bit, highest_bit, 227 * inuse_pages, cluster_next, 228 * cluster_nr, lowest_alloc, 229 * highest_alloc, free/discard cluster 230 * list. other fields are only changed 231 * at swapon/swapoff, so are protected 232 * by swap_lock. changing flags need 233 * hold this lock and swap_lock. If 234 * both locks need hold, hold swap_lock 235 * first. 236 */ 237 struct work_struct discard_work; /* discard worker */ 238 struct swap_cluster_info discard_cluster_head; /* list head of discard clusters */ 239 struct swap_cluster_info discard_cluster_tail; /* list tail of discard clusters */ 240 }; 241 242 /* linux/mm/workingset.c */ 243 void *workingset_eviction(struct address_space *mapping, struct page *page); 244 bool workingset_refault(void *shadow); 245 void workingset_activation(struct page *page); 246 extern struct list_lru workingset_shadow_nodes; 247 248 static inline unsigned int workingset_node_pages(struct radix_tree_node *node) 249 { 250 return node->count & RADIX_TREE_COUNT_MASK; 251 } 252 253 static inline void workingset_node_pages_inc(struct radix_tree_node *node) 254 { 255 node->count++; 256 } 257 258 static inline void workingset_node_pages_dec(struct radix_tree_node *node) 259 { 260 VM_BUG_ON(!workingset_node_pages(node)); 261 node->count--; 262 } 263 264 static inline unsigned int workingset_node_shadows(struct radix_tree_node *node) 265 { 266 return node->count >> RADIX_TREE_COUNT_SHIFT; 267 } 268 269 static inline void workingset_node_shadows_inc(struct radix_tree_node *node) 270 { 271 node->count += 1U << RADIX_TREE_COUNT_SHIFT; 272 } 273 274 static inline void workingset_node_shadows_dec(struct radix_tree_node *node) 275 { 276 VM_BUG_ON(!workingset_node_shadows(node)); 277 node->count -= 1U << RADIX_TREE_COUNT_SHIFT; 278 } 279 280 /* linux/mm/page_alloc.c */ 281 extern unsigned long totalram_pages; 282 extern unsigned long totalreserve_pages; 283 extern unsigned long nr_free_buffer_pages(void); 284 extern unsigned long nr_free_pagecache_pages(void); 285 286 /* Definition of global_page_state not available yet */ 287 #define nr_free_pages() global_page_state(NR_FREE_PAGES) 288 289 290 /* linux/mm/swap.c */ 291 extern void lru_cache_add(struct page *); 292 extern void lru_cache_add_anon(struct page *page); 293 extern void lru_cache_add_file(struct page *page); 294 extern void lru_add_page_tail(struct page *page, struct page *page_tail, 295 struct lruvec *lruvec, struct list_head *head); 296 extern void activate_page(struct page *); 297 extern void mark_page_accessed(struct page *); 298 extern void lru_add_drain(void); 299 extern void lru_add_drain_cpu(int cpu); 300 extern void lru_add_drain_all(void); 301 extern void rotate_reclaimable_page(struct page *page); 302 extern void deactivate_file_page(struct page *page); 303 extern void deactivate_page(struct page *page); 304 extern void swap_setup(void); 305 306 extern void add_page_to_unevictable_list(struct page *page); 307 308 extern void lru_cache_add_active_or_unevictable(struct page *page, 309 struct vm_area_struct *vma); 310 311 /* linux/mm/vmscan.c */ 312 extern unsigned long zone_reclaimable_pages(struct zone *zone); 313 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat); 314 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, 315 gfp_t gfp_mask, nodemask_t *mask); 316 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode); 317 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, 318 unsigned long nr_pages, 319 gfp_t gfp_mask, 320 bool may_swap); 321 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, 322 gfp_t gfp_mask, bool noswap, 323 pg_data_t *pgdat, 324 unsigned long *nr_scanned); 325 extern unsigned long shrink_all_memory(unsigned long nr_pages); 326 extern int vm_swappiness; 327 extern int remove_mapping(struct address_space *mapping, struct page *page); 328 extern unsigned long vm_total_pages; 329 330 #ifdef CONFIG_NUMA 331 extern int node_reclaim_mode; 332 extern int sysctl_min_unmapped_ratio; 333 extern int sysctl_min_slab_ratio; 334 extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int); 335 #else 336 #define node_reclaim_mode 0 337 static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask, 338 unsigned int order) 339 { 340 return 0; 341 } 342 #endif 343 344 extern int page_evictable(struct page *page); 345 extern void check_move_unevictable_pages(struct page **, int nr_pages); 346 347 extern int kswapd_run(int nid); 348 extern void kswapd_stop(int nid); 349 350 #ifdef CONFIG_SWAP 351 /* linux/mm/page_io.c */ 352 extern int swap_readpage(struct page *); 353 extern int swap_writepage(struct page *page, struct writeback_control *wbc); 354 extern void end_swap_bio_write(struct bio *bio); 355 extern int __swap_writepage(struct page *page, struct writeback_control *wbc, 356 bio_end_io_t end_write_func); 357 extern int swap_set_page_dirty(struct page *page); 358 359 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 360 unsigned long nr_pages, sector_t start_block); 361 int generic_swapfile_activate(struct swap_info_struct *, struct file *, 362 sector_t *); 363 364 /* linux/mm/swap_state.c */ 365 extern struct address_space swapper_spaces[]; 366 #define swap_address_space(entry) (&swapper_spaces[swp_type(entry)]) 367 extern unsigned long total_swapcache_pages(void); 368 extern void show_swap_cache_info(void); 369 extern int add_to_swap(struct page *, struct list_head *list); 370 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); 371 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); 372 extern void __delete_from_swap_cache(struct page *); 373 extern void delete_from_swap_cache(struct page *); 374 extern void free_page_and_swap_cache(struct page *); 375 extern void free_pages_and_swap_cache(struct page **, int); 376 extern struct page *lookup_swap_cache(swp_entry_t); 377 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t, 378 struct vm_area_struct *vma, unsigned long addr); 379 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t, 380 struct vm_area_struct *vma, unsigned long addr, 381 bool *new_page_allocated); 382 extern struct page *swapin_readahead(swp_entry_t, gfp_t, 383 struct vm_area_struct *vma, unsigned long addr); 384 385 /* linux/mm/swapfile.c */ 386 extern atomic_long_t nr_swap_pages; 387 extern long total_swap_pages; 388 389 /* Swap 50% full? Release swapcache more aggressively.. */ 390 static inline bool vm_swap_full(void) 391 { 392 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages; 393 } 394 395 static inline long get_nr_swap_pages(void) 396 { 397 return atomic_long_read(&nr_swap_pages); 398 } 399 400 extern void si_swapinfo(struct sysinfo *); 401 extern swp_entry_t get_swap_page(void); 402 extern swp_entry_t get_swap_page_of_type(int); 403 extern int add_swap_count_continuation(swp_entry_t, gfp_t); 404 extern void swap_shmem_alloc(swp_entry_t); 405 extern int swap_duplicate(swp_entry_t); 406 extern int swapcache_prepare(swp_entry_t); 407 extern void swap_free(swp_entry_t); 408 extern void swapcache_free(swp_entry_t); 409 extern int free_swap_and_cache(swp_entry_t); 410 extern int swap_type_of(dev_t, sector_t, struct block_device **); 411 extern unsigned int count_swap_pages(int, int); 412 extern sector_t map_swap_page(struct page *, struct block_device **); 413 extern sector_t swapdev_block(int, pgoff_t); 414 extern int page_swapcount(struct page *); 415 extern int swp_swapcount(swp_entry_t entry); 416 extern struct swap_info_struct *page_swap_info(struct page *); 417 extern bool reuse_swap_page(struct page *, int *); 418 extern int try_to_free_swap(struct page *); 419 struct backing_dev_info; 420 421 #else /* CONFIG_SWAP */ 422 423 #define swap_address_space(entry) (NULL) 424 #define get_nr_swap_pages() 0L 425 #define total_swap_pages 0L 426 #define total_swapcache_pages() 0UL 427 #define vm_swap_full() 0 428 429 #define si_swapinfo(val) \ 430 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 431 /* only sparc can not include linux/pagemap.h in this file 432 * so leave put_page and release_pages undeclared... */ 433 #define free_page_and_swap_cache(page) \ 434 put_page(page) 435 #define free_pages_and_swap_cache(pages, nr) \ 436 release_pages((pages), (nr), false); 437 438 static inline void show_swap_cache_info(void) 439 { 440 } 441 442 #define free_swap_and_cache(swp) is_migration_entry(swp) 443 #define swapcache_prepare(swp) is_migration_entry(swp) 444 445 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) 446 { 447 return 0; 448 } 449 450 static inline void swap_shmem_alloc(swp_entry_t swp) 451 { 452 } 453 454 static inline int swap_duplicate(swp_entry_t swp) 455 { 456 return 0; 457 } 458 459 static inline void swap_free(swp_entry_t swp) 460 { 461 } 462 463 static inline void swapcache_free(swp_entry_t swp) 464 { 465 } 466 467 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, 468 struct vm_area_struct *vma, unsigned long addr) 469 { 470 return NULL; 471 } 472 473 static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 474 { 475 return 0; 476 } 477 478 static inline struct page *lookup_swap_cache(swp_entry_t swp) 479 { 480 return NULL; 481 } 482 483 static inline int add_to_swap(struct page *page, struct list_head *list) 484 { 485 return 0; 486 } 487 488 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, 489 gfp_t gfp_mask) 490 { 491 return -1; 492 } 493 494 static inline void __delete_from_swap_cache(struct page *page) 495 { 496 } 497 498 static inline void delete_from_swap_cache(struct page *page) 499 { 500 } 501 502 static inline int page_swapcount(struct page *page) 503 { 504 return 0; 505 } 506 507 static inline int swp_swapcount(swp_entry_t entry) 508 { 509 return 0; 510 } 511 512 #define reuse_swap_page(page, total_mapcount) \ 513 (page_trans_huge_mapcount(page, total_mapcount) == 1) 514 515 static inline int try_to_free_swap(struct page *page) 516 { 517 return 0; 518 } 519 520 static inline swp_entry_t get_swap_page(void) 521 { 522 swp_entry_t entry; 523 entry.val = 0; 524 return entry; 525 } 526 527 #endif /* CONFIG_SWAP */ 528 529 #ifdef CONFIG_MEMCG 530 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) 531 { 532 /* Cgroup2 doesn't have per-cgroup swappiness */ 533 if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) 534 return vm_swappiness; 535 536 /* root ? */ 537 if (mem_cgroup_disabled() || !memcg->css.parent) 538 return vm_swappiness; 539 540 return memcg->swappiness; 541 } 542 543 #else 544 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) 545 { 546 return vm_swappiness; 547 } 548 #endif 549 550 #ifdef CONFIG_MEMCG_SWAP 551 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); 552 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); 553 extern void mem_cgroup_uncharge_swap(swp_entry_t entry); 554 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); 555 extern bool mem_cgroup_swap_full(struct page *page); 556 #else 557 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry) 558 { 559 } 560 561 static inline int mem_cgroup_try_charge_swap(struct page *page, 562 swp_entry_t entry) 563 { 564 return 0; 565 } 566 567 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry) 568 { 569 } 570 571 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) 572 { 573 return get_nr_swap_pages(); 574 } 575 576 static inline bool mem_cgroup_swap_full(struct page *page) 577 { 578 return vm_swap_full(); 579 } 580 #endif 581 582 #endif /* __KERNEL__*/ 583 #endif /* _LINUX_SWAP_H */ 584