| 1 | /* |
| 2 | * linux/mm/swap.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * This file contains the default values for the operation of the |
| 9 | * Linux VM subsystem. Fine-tuning documentation can be found in |
| 10 | * Documentation/sysctl/vm.txt. |
| 11 | * Started 18.12.91 |
| 12 | * Swap aging added 23.2.95, Stephen Tweedie. |
| 13 | * Buffermem limits added 12.3.98, Rik van Riel. |
| 14 | */ |
| 15 | |
| 16 | #include <linux/mm.h> |
| 17 | #include <linux/sched.h> |
| 18 | #include <linux/kernel_stat.h> |
| 19 | #include <linux/swap.h> |
| 20 | #include <linux/mman.h> |
| 21 | #include <linux/pagemap.h> |
| 22 | #include <linux/pagevec.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/export.h> |
| 25 | #include <linux/mm_inline.h> |
| 26 | #include <linux/percpu_counter.h> |
| 27 | #include <linux/percpu.h> |
| 28 | #include <linux/cpu.h> |
| 29 | #include <linux/notifier.h> |
| 30 | #include <linux/backing-dev.h> |
| 31 | #include <linux/memcontrol.h> |
| 32 | #include <linux/gfp.h> |
| 33 | #include <linux/uio.h> |
| 34 | #include <linux/hugetlb.h> |
| 35 | |
| 36 | #include "internal.h" |
| 37 | |
| 38 | #define CREATE_TRACE_POINTS |
| 39 | #include <trace/events/pagemap.h> |
| 40 | |
| 41 | /* How many pages do we try to swap or page in/out together? */ |
| 42 | int page_cluster; |
| 43 | |
| 44 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); |
| 45 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
| 46 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); |
| 47 | |
| 48 | /* |
| 49 | * This path almost never happens for VM activity - pages are normally |
| 50 | * freed via pagevecs. But it gets used by networking. |
| 51 | */ |
| 52 | static void __page_cache_release(struct page *page) |
| 53 | { |
| 54 | if (PageLRU(page)) { |
| 55 | struct zone *zone = page_zone(page); |
| 56 | struct lruvec *lruvec; |
| 57 | unsigned long flags; |
| 58 | |
| 59 | spin_lock_irqsave(&zone->lru_lock, flags); |
| 60 | lruvec = mem_cgroup_page_lruvec(page, zone); |
| 61 | VM_BUG_ON(!PageLRU(page)); |
| 62 | __ClearPageLRU(page); |
| 63 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); |
| 64 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | static void __put_single_page(struct page *page) |
| 69 | { |
| 70 | __page_cache_release(page); |
| 71 | free_hot_cold_page(page, 0); |
| 72 | } |
| 73 | |
| 74 | static void __put_compound_page(struct page *page) |
| 75 | { |
| 76 | compound_page_dtor *dtor; |
| 77 | |
| 78 | __page_cache_release(page); |
| 79 | dtor = get_compound_page_dtor(page); |
| 80 | (*dtor)(page); |
| 81 | } |
| 82 | |
| 83 | static void put_compound_page(struct page *page) |
| 84 | { |
| 85 | /* |
| 86 | * hugetlbfs pages cannot be split from under us. If this is a |
| 87 | * hugetlbfs page, check refcount on head page and release the page if |
| 88 | * the refcount becomes zero. |
| 89 | */ |
| 90 | if (PageHuge(page)) { |
| 91 | page = compound_head(page); |
| 92 | if (put_page_testzero(page)) |
| 93 | __put_compound_page(page); |
| 94 | |
| 95 | return; |
| 96 | } |
| 97 | |
| 98 | if (unlikely(PageTail(page))) { |
| 99 | /* __split_huge_page_refcount can run under us */ |
| 100 | struct page *page_head = compound_trans_head(page); |
| 101 | |
| 102 | if (likely(page != page_head && |
| 103 | get_page_unless_zero(page_head))) { |
| 104 | unsigned long flags; |
| 105 | |
| 106 | /* |
| 107 | * THP can not break up slab pages so avoid taking |
| 108 | * compound_lock(). Slab performs non-atomic bit ops |
| 109 | * on page->flags for better performance. In particular |
| 110 | * slab_unlock() in slub used to be a hot path. It is |
| 111 | * still hot on arches that do not support |
| 112 | * this_cpu_cmpxchg_double(). |
| 113 | */ |
| 114 | if (PageSlab(page_head)) { |
| 115 | if (PageTail(page)) { |
| 116 | if (put_page_testzero(page_head)) |
| 117 | VM_BUG_ON(1); |
| 118 | |
| 119 | atomic_dec(&page->_mapcount); |
| 120 | goto skip_lock_tail; |
| 121 | } else |
| 122 | goto skip_lock; |
| 123 | } |
| 124 | /* |
| 125 | * page_head wasn't a dangling pointer but it |
| 126 | * may not be a head page anymore by the time |
| 127 | * we obtain the lock. That is ok as long as it |
| 128 | * can't be freed from under us. |
| 129 | */ |
| 130 | flags = compound_lock_irqsave(page_head); |
| 131 | if (unlikely(!PageTail(page))) { |
| 132 | /* __split_huge_page_refcount run before us */ |
| 133 | compound_unlock_irqrestore(page_head, flags); |
| 134 | skip_lock: |
| 135 | if (put_page_testzero(page_head)) |
| 136 | __put_single_page(page_head); |
| 137 | out_put_single: |
| 138 | if (put_page_testzero(page)) |
| 139 | __put_single_page(page); |
| 140 | return; |
| 141 | } |
| 142 | VM_BUG_ON(page_head != page->first_page); |
| 143 | /* |
| 144 | * We can release the refcount taken by |
| 145 | * get_page_unless_zero() now that |
| 146 | * __split_huge_page_refcount() is blocked on |
| 147 | * the compound_lock. |
| 148 | */ |
| 149 | if (put_page_testzero(page_head)) |
| 150 | VM_BUG_ON(1); |
| 151 | /* __split_huge_page_refcount will wait now */ |
| 152 | VM_BUG_ON(page_mapcount(page) <= 0); |
| 153 | atomic_dec(&page->_mapcount); |
| 154 | VM_BUG_ON(atomic_read(&page_head->_count) <= 0); |
| 155 | VM_BUG_ON(atomic_read(&page->_count) != 0); |
| 156 | compound_unlock_irqrestore(page_head, flags); |
| 157 | |
| 158 | skip_lock_tail: |
| 159 | if (put_page_testzero(page_head)) { |
| 160 | if (PageHead(page_head)) |
| 161 | __put_compound_page(page_head); |
| 162 | else |
| 163 | __put_single_page(page_head); |
| 164 | } |
| 165 | } else { |
| 166 | /* page_head is a dangling pointer */ |
| 167 | VM_BUG_ON(PageTail(page)); |
| 168 | goto out_put_single; |
| 169 | } |
| 170 | } else if (put_page_testzero(page)) { |
| 171 | if (PageHead(page)) |
| 172 | __put_compound_page(page); |
| 173 | else |
| 174 | __put_single_page(page); |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | void put_page(struct page *page) |
| 179 | { |
| 180 | if (unlikely(PageCompound(page))) |
| 181 | put_compound_page(page); |
| 182 | else if (put_page_testzero(page)) |
| 183 | __put_single_page(page); |
| 184 | } |
| 185 | EXPORT_SYMBOL(put_page); |
| 186 | |
| 187 | /* |
| 188 | * This function is exported but must not be called by anything other |
| 189 | * than get_page(). It implements the slow path of get_page(). |
| 190 | */ |
| 191 | bool __get_page_tail(struct page *page) |
| 192 | { |
| 193 | /* |
| 194 | * This takes care of get_page() if run on a tail page |
| 195 | * returned by one of the get_user_pages/follow_page variants. |
| 196 | * get_user_pages/follow_page itself doesn't need the compound |
| 197 | * lock because it runs __get_page_tail_foll() under the |
| 198 | * proper PT lock that already serializes against |
| 199 | * split_huge_page(). |
| 200 | */ |
| 201 | bool got = false; |
| 202 | struct page *page_head; |
| 203 | |
| 204 | /* |
| 205 | * If this is a hugetlbfs page it cannot be split under us. Simply |
| 206 | * increment refcount for the head page. |
| 207 | */ |
| 208 | if (PageHuge(page)) { |
| 209 | page_head = compound_head(page); |
| 210 | atomic_inc(&page_head->_count); |
| 211 | got = true; |
| 212 | } else { |
| 213 | unsigned long flags; |
| 214 | |
| 215 | page_head = compound_trans_head(page); |
| 216 | if (likely(page != page_head && |
| 217 | get_page_unless_zero(page_head))) { |
| 218 | |
| 219 | /* Ref to put_compound_page() comment. */ |
| 220 | if (PageSlab(page_head)) { |
| 221 | if (likely(PageTail(page))) { |
| 222 | __get_page_tail_foll(page, false); |
| 223 | return true; |
| 224 | } else { |
| 225 | put_page(page_head); |
| 226 | return false; |
| 227 | } |
| 228 | } |
| 229 | |
| 230 | /* |
| 231 | * page_head wasn't a dangling pointer but it |
| 232 | * may not be a head page anymore by the time |
| 233 | * we obtain the lock. That is ok as long as it |
| 234 | * can't be freed from under us. |
| 235 | */ |
| 236 | flags = compound_lock_irqsave(page_head); |
| 237 | /* here __split_huge_page_refcount won't run anymore */ |
| 238 | if (likely(PageTail(page))) { |
| 239 | __get_page_tail_foll(page, false); |
| 240 | got = true; |
| 241 | } |
| 242 | compound_unlock_irqrestore(page_head, flags); |
| 243 | if (unlikely(!got)) |
| 244 | put_page(page_head); |
| 245 | } |
| 246 | } |
| 247 | return got; |
| 248 | } |
| 249 | EXPORT_SYMBOL(__get_page_tail); |
| 250 | |
| 251 | /** |
| 252 | * put_pages_list() - release a list of pages |
| 253 | * @pages: list of pages threaded on page->lru |
| 254 | * |
| 255 | * Release a list of pages which are strung together on page.lru. Currently |
| 256 | * used by read_cache_pages() and related error recovery code. |
| 257 | */ |
| 258 | void put_pages_list(struct list_head *pages) |
| 259 | { |
| 260 | while (!list_empty(pages)) { |
| 261 | struct page *victim; |
| 262 | |
| 263 | victim = list_entry(pages->prev, struct page, lru); |
| 264 | list_del(&victim->lru); |
| 265 | page_cache_release(victim); |
| 266 | } |
| 267 | } |
| 268 | EXPORT_SYMBOL(put_pages_list); |
| 269 | |
| 270 | /* |
| 271 | * get_kernel_pages() - pin kernel pages in memory |
| 272 | * @kiov: An array of struct kvec structures |
| 273 | * @nr_segs: number of segments to pin |
| 274 | * @write: pinning for read/write, currently ignored |
| 275 | * @pages: array that receives pointers to the pages pinned. |
| 276 | * Should be at least nr_segs long. |
| 277 | * |
| 278 | * Returns number of pages pinned. This may be fewer than the number |
| 279 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
| 280 | * were pinned, returns -errno. Each page returned must be released |
| 281 | * with a put_page() call when it is finished with. |
| 282 | */ |
| 283 | int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, |
| 284 | struct page **pages) |
| 285 | { |
| 286 | int seg; |
| 287 | |
| 288 | for (seg = 0; seg < nr_segs; seg++) { |
| 289 | if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) |
| 290 | return seg; |
| 291 | |
| 292 | pages[seg] = kmap_to_page(kiov[seg].iov_base); |
| 293 | page_cache_get(pages[seg]); |
| 294 | } |
| 295 | |
| 296 | return seg; |
| 297 | } |
| 298 | EXPORT_SYMBOL_GPL(get_kernel_pages); |
| 299 | |
| 300 | /* |
| 301 | * get_kernel_page() - pin a kernel page in memory |
| 302 | * @start: starting kernel address |
| 303 | * @write: pinning for read/write, currently ignored |
| 304 | * @pages: array that receives pointer to the page pinned. |
| 305 | * Must be at least nr_segs long. |
| 306 | * |
| 307 | * Returns 1 if page is pinned. If the page was not pinned, returns |
| 308 | * -errno. The page returned must be released with a put_page() call |
| 309 | * when it is finished with. |
| 310 | */ |
| 311 | int get_kernel_page(unsigned long start, int write, struct page **pages) |
| 312 | { |
| 313 | const struct kvec kiov = { |
| 314 | .iov_base = (void *)start, |
| 315 | .iov_len = PAGE_SIZE |
| 316 | }; |
| 317 | |
| 318 | return get_kernel_pages(&kiov, 1, write, pages); |
| 319 | } |
| 320 | EXPORT_SYMBOL_GPL(get_kernel_page); |
| 321 | |
| 322 | static void pagevec_lru_move_fn(struct pagevec *pvec, |
| 323 | void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg), |
| 324 | void *arg) |
| 325 | { |
| 326 | int i; |
| 327 | struct zone *zone = NULL; |
| 328 | struct lruvec *lruvec; |
| 329 | unsigned long flags = 0; |
| 330 | |
| 331 | for (i = 0; i < pagevec_count(pvec); i++) { |
| 332 | struct page *page = pvec->pages[i]; |
| 333 | struct zone *pagezone = page_zone(page); |
| 334 | |
| 335 | if (pagezone != zone) { |
| 336 | if (zone) |
| 337 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
| 338 | zone = pagezone; |
| 339 | spin_lock_irqsave(&zone->lru_lock, flags); |
| 340 | } |
| 341 | |
| 342 | lruvec = mem_cgroup_page_lruvec(page, zone); |
| 343 | (*move_fn)(page, lruvec, arg); |
| 344 | } |
| 345 | if (zone) |
| 346 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
| 347 | release_pages(pvec->pages, pvec->nr, pvec->cold); |
| 348 | pagevec_reinit(pvec); |
| 349 | } |
| 350 | |
| 351 | static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec, |
| 352 | void *arg) |
| 353 | { |
| 354 | int *pgmoved = arg; |
| 355 | |
| 356 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| 357 | enum lru_list lru = page_lru_base_type(page); |
| 358 | list_move_tail(&page->lru, &lruvec->lists[lru]); |
| 359 | (*pgmoved)++; |
| 360 | } |
| 361 | } |
| 362 | |
| 363 | /* |
| 364 | * pagevec_move_tail() must be called with IRQ disabled. |
| 365 | * Otherwise this may cause nasty races. |
| 366 | */ |
| 367 | static void pagevec_move_tail(struct pagevec *pvec) |
| 368 | { |
| 369 | int pgmoved = 0; |
| 370 | |
| 371 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); |
| 372 | __count_vm_events(PGROTATED, pgmoved); |
| 373 | } |
| 374 | |
| 375 | /* |
| 376 | * Writeback is about to end against a page which has been marked for immediate |
| 377 | * reclaim. If it still appears to be reclaimable, move it to the tail of the |
| 378 | * inactive list. |
| 379 | */ |
| 380 | void rotate_reclaimable_page(struct page *page) |
| 381 | { |
| 382 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
| 383 | !PageUnevictable(page) && PageLRU(page)) { |
| 384 | struct pagevec *pvec; |
| 385 | unsigned long flags; |
| 386 | |
| 387 | page_cache_get(page); |
| 388 | local_irq_save(flags); |
| 389 | pvec = &__get_cpu_var(lru_rotate_pvecs); |
| 390 | if (!pagevec_add(pvec, page)) |
| 391 | pagevec_move_tail(pvec); |
| 392 | local_irq_restore(flags); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | static void update_page_reclaim_stat(struct lruvec *lruvec, |
| 397 | int file, int rotated) |
| 398 | { |
| 399 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
| 400 | |
| 401 | reclaim_stat->recent_scanned[file]++; |
| 402 | if (rotated) |
| 403 | reclaim_stat->recent_rotated[file]++; |
| 404 | } |
| 405 | |
| 406 | static void __activate_page(struct page *page, struct lruvec *lruvec, |
| 407 | void *arg) |
| 408 | { |
| 409 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| 410 | int file = page_is_file_cache(page); |
| 411 | int lru = page_lru_base_type(page); |
| 412 | |
| 413 | del_page_from_lru_list(page, lruvec, lru); |
| 414 | SetPageActive(page); |
| 415 | lru += LRU_ACTIVE; |
| 416 | add_page_to_lru_list(page, lruvec, lru); |
| 417 | trace_mm_lru_activate(page, page_to_pfn(page)); |
| 418 | |
| 419 | __count_vm_event(PGACTIVATE); |
| 420 | update_page_reclaim_stat(lruvec, file, 1); |
| 421 | } |
| 422 | } |
| 423 | |
| 424 | #ifdef CONFIG_SMP |
| 425 | static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); |
| 426 | |
| 427 | static void activate_page_drain(int cpu) |
| 428 | { |
| 429 | struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); |
| 430 | |
| 431 | if (pagevec_count(pvec)) |
| 432 | pagevec_lru_move_fn(pvec, __activate_page, NULL); |
| 433 | } |
| 434 | |
| 435 | static bool need_activate_page_drain(int cpu) |
| 436 | { |
| 437 | return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0; |
| 438 | } |
| 439 | |
| 440 | void activate_page(struct page *page) |
| 441 | { |
| 442 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| 443 | struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); |
| 444 | |
| 445 | page_cache_get(page); |
| 446 | if (!pagevec_add(pvec, page)) |
| 447 | pagevec_lru_move_fn(pvec, __activate_page, NULL); |
| 448 | put_cpu_var(activate_page_pvecs); |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | #else |
| 453 | static inline void activate_page_drain(int cpu) |
| 454 | { |
| 455 | } |
| 456 | |
| 457 | static bool need_activate_page_drain(int cpu) |
| 458 | { |
| 459 | return false; |
| 460 | } |
| 461 | |
| 462 | void activate_page(struct page *page) |
| 463 | { |
| 464 | struct zone *zone = page_zone(page); |
| 465 | |
| 466 | spin_lock_irq(&zone->lru_lock); |
| 467 | __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL); |
| 468 | spin_unlock_irq(&zone->lru_lock); |
| 469 | } |
| 470 | #endif |
| 471 | |
| 472 | static void __lru_cache_activate_page(struct page *page) |
| 473 | { |
| 474 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); |
| 475 | int i; |
| 476 | |
| 477 | /* |
| 478 | * Search backwards on the optimistic assumption that the page being |
| 479 | * activated has just been added to this pagevec. Note that only |
| 480 | * the local pagevec is examined as a !PageLRU page could be in the |
| 481 | * process of being released, reclaimed, migrated or on a remote |
| 482 | * pagevec that is currently being drained. Furthermore, marking |
| 483 | * a remote pagevec's page PageActive potentially hits a race where |
| 484 | * a page is marked PageActive just after it is added to the inactive |
| 485 | * list causing accounting errors and BUG_ON checks to trigger. |
| 486 | */ |
| 487 | for (i = pagevec_count(pvec) - 1; i >= 0; i--) { |
| 488 | struct page *pagevec_page = pvec->pages[i]; |
| 489 | |
| 490 | if (pagevec_page == page) { |
| 491 | SetPageActive(page); |
| 492 | break; |
| 493 | } |
| 494 | } |
| 495 | |
| 496 | put_cpu_var(lru_add_pvec); |
| 497 | } |
| 498 | |
| 499 | /* |
| 500 | * Mark a page as having seen activity. |
| 501 | * |
| 502 | * inactive,unreferenced -> inactive,referenced |
| 503 | * inactive,referenced -> active,unreferenced |
| 504 | * active,unreferenced -> active,referenced |
| 505 | */ |
| 506 | void mark_page_accessed(struct page *page) |
| 507 | { |
| 508 | if (!PageActive(page) && !PageUnevictable(page) && |
| 509 | PageReferenced(page)) { |
| 510 | |
| 511 | /* |
| 512 | * If the page is on the LRU, queue it for activation via |
| 513 | * activate_page_pvecs. Otherwise, assume the page is on a |
| 514 | * pagevec, mark it active and it'll be moved to the active |
| 515 | * LRU on the next drain. |
| 516 | */ |
| 517 | if (PageLRU(page)) |
| 518 | activate_page(page); |
| 519 | else |
| 520 | __lru_cache_activate_page(page); |
| 521 | ClearPageReferenced(page); |
| 522 | } else if (!PageReferenced(page)) { |
| 523 | SetPageReferenced(page); |
| 524 | } |
| 525 | } |
| 526 | EXPORT_SYMBOL(mark_page_accessed); |
| 527 | |
| 528 | /* |
| 529 | * Queue the page for addition to the LRU via pagevec. The decision on whether |
| 530 | * to add the page to the [in]active [file|anon] list is deferred until the |
| 531 | * pagevec is drained. This gives a chance for the caller of __lru_cache_add() |
| 532 | * have the page added to the active list using mark_page_accessed(). |
| 533 | */ |
| 534 | void __lru_cache_add(struct page *page) |
| 535 | { |
| 536 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); |
| 537 | |
| 538 | page_cache_get(page); |
| 539 | if (!pagevec_space(pvec)) |
| 540 | __pagevec_lru_add(pvec); |
| 541 | pagevec_add(pvec, page); |
| 542 | put_cpu_var(lru_add_pvec); |
| 543 | } |
| 544 | EXPORT_SYMBOL(__lru_cache_add); |
| 545 | |
| 546 | /** |
| 547 | * lru_cache_add - add a page to a page list |
| 548 | * @page: the page to be added to the LRU. |
| 549 | */ |
| 550 | void lru_cache_add(struct page *page) |
| 551 | { |
| 552 | VM_BUG_ON(PageActive(page) && PageUnevictable(page)); |
| 553 | VM_BUG_ON(PageLRU(page)); |
| 554 | __lru_cache_add(page); |
| 555 | } |
| 556 | |
| 557 | /** |
| 558 | * add_page_to_unevictable_list - add a page to the unevictable list |
| 559 | * @page: the page to be added to the unevictable list |
| 560 | * |
| 561 | * Add page directly to its zone's unevictable list. To avoid races with |
| 562 | * tasks that might be making the page evictable, through eg. munlock, |
| 563 | * munmap or exit, while it's not on the lru, we want to add the page |
| 564 | * while it's locked or otherwise "invisible" to other tasks. This is |
| 565 | * difficult to do when using the pagevec cache, so bypass that. |
| 566 | */ |
| 567 | void add_page_to_unevictable_list(struct page *page) |
| 568 | { |
| 569 | struct zone *zone = page_zone(page); |
| 570 | struct lruvec *lruvec; |
| 571 | |
| 572 | spin_lock_irq(&zone->lru_lock); |
| 573 | lruvec = mem_cgroup_page_lruvec(page, zone); |
| 574 | ClearPageActive(page); |
| 575 | SetPageUnevictable(page); |
| 576 | SetPageLRU(page); |
| 577 | add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE); |
| 578 | spin_unlock_irq(&zone->lru_lock); |
| 579 | } |
| 580 | |
| 581 | /* |
| 582 | * If the page can not be invalidated, it is moved to the |
| 583 | * inactive list to speed up its reclaim. It is moved to the |
| 584 | * head of the list, rather than the tail, to give the flusher |
| 585 | * threads some time to write it out, as this is much more |
| 586 | * effective than the single-page writeout from reclaim. |
| 587 | * |
| 588 | * If the page isn't page_mapped and dirty/writeback, the page |
| 589 | * could reclaim asap using PG_reclaim. |
| 590 | * |
| 591 | * 1. active, mapped page -> none |
| 592 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim |
| 593 | * 3. inactive, mapped page -> none |
| 594 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim |
| 595 | * 5. inactive, clean -> inactive, tail |
| 596 | * 6. Others -> none |
| 597 | * |
| 598 | * In 4, why it moves inactive's head, the VM expects the page would |
| 599 | * be write it out by flusher threads as this is much more effective |
| 600 | * than the single-page writeout from reclaim. |
| 601 | */ |
| 602 | static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, |
| 603 | void *arg) |
| 604 | { |
| 605 | int lru, file; |
| 606 | bool active; |
| 607 | |
| 608 | if (!PageLRU(page)) |
| 609 | return; |
| 610 | |
| 611 | if (PageUnevictable(page)) |
| 612 | return; |
| 613 | |
| 614 | /* Some processes are using the page */ |
| 615 | if (page_mapped(page)) |
| 616 | return; |
| 617 | |
| 618 | active = PageActive(page); |
| 619 | file = page_is_file_cache(page); |
| 620 | lru = page_lru_base_type(page); |
| 621 | |
| 622 | del_page_from_lru_list(page, lruvec, lru + active); |
| 623 | ClearPageActive(page); |
| 624 | ClearPageReferenced(page); |
| 625 | add_page_to_lru_list(page, lruvec, lru); |
| 626 | |
| 627 | if (PageWriteback(page) || PageDirty(page)) { |
| 628 | /* |
| 629 | * PG_reclaim could be raced with end_page_writeback |
| 630 | * It can make readahead confusing. But race window |
| 631 | * is _really_ small and it's non-critical problem. |
| 632 | */ |
| 633 | SetPageReclaim(page); |
| 634 | } else { |
| 635 | /* |
| 636 | * The page's writeback ends up during pagevec |
| 637 | * We moves tha page into tail of inactive. |
| 638 | */ |
| 639 | list_move_tail(&page->lru, &lruvec->lists[lru]); |
| 640 | __count_vm_event(PGROTATED); |
| 641 | } |
| 642 | |
| 643 | if (active) |
| 644 | __count_vm_event(PGDEACTIVATE); |
| 645 | update_page_reclaim_stat(lruvec, file, 0); |
| 646 | } |
| 647 | |
| 648 | /* |
| 649 | * Drain pages out of the cpu's pagevecs. |
| 650 | * Either "cpu" is the current CPU, and preemption has already been |
| 651 | * disabled; or "cpu" is being hot-unplugged, and is already dead. |
| 652 | */ |
| 653 | void lru_add_drain_cpu(int cpu) |
| 654 | { |
| 655 | struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu); |
| 656 | |
| 657 | if (pagevec_count(pvec)) |
| 658 | __pagevec_lru_add(pvec); |
| 659 | |
| 660 | pvec = &per_cpu(lru_rotate_pvecs, cpu); |
| 661 | if (pagevec_count(pvec)) { |
| 662 | unsigned long flags; |
| 663 | |
| 664 | /* No harm done if a racing interrupt already did this */ |
| 665 | local_irq_save(flags); |
| 666 | pagevec_move_tail(pvec); |
| 667 | local_irq_restore(flags); |
| 668 | } |
| 669 | |
| 670 | pvec = &per_cpu(lru_deactivate_pvecs, cpu); |
| 671 | if (pagevec_count(pvec)) |
| 672 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
| 673 | |
| 674 | activate_page_drain(cpu); |
| 675 | } |
| 676 | |
| 677 | /** |
| 678 | * deactivate_page - forcefully deactivate a page |
| 679 | * @page: page to deactivate |
| 680 | * |
| 681 | * This function hints the VM that @page is a good reclaim candidate, |
| 682 | * for example if its invalidation fails due to the page being dirty |
| 683 | * or under writeback. |
| 684 | */ |
| 685 | void deactivate_page(struct page *page) |
| 686 | { |
| 687 | /* |
| 688 | * In a workload with many unevictable page such as mprotect, unevictable |
| 689 | * page deactivation for accelerating reclaim is pointless. |
| 690 | */ |
| 691 | if (PageUnevictable(page)) |
| 692 | return; |
| 693 | |
| 694 | if (likely(get_page_unless_zero(page))) { |
| 695 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); |
| 696 | |
| 697 | if (!pagevec_add(pvec, page)) |
| 698 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
| 699 | put_cpu_var(lru_deactivate_pvecs); |
| 700 | } |
| 701 | } |
| 702 | |
| 703 | void lru_add_drain(void) |
| 704 | { |
| 705 | lru_add_drain_cpu(get_cpu()); |
| 706 | put_cpu(); |
| 707 | } |
| 708 | |
| 709 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
| 710 | { |
| 711 | lru_add_drain(); |
| 712 | } |
| 713 | |
| 714 | static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); |
| 715 | |
| 716 | void lru_add_drain_all(void) |
| 717 | { |
| 718 | static DEFINE_MUTEX(lock); |
| 719 | static struct cpumask has_work; |
| 720 | int cpu; |
| 721 | |
| 722 | mutex_lock(&lock); |
| 723 | get_online_cpus(); |
| 724 | cpumask_clear(&has_work); |
| 725 | |
| 726 | for_each_online_cpu(cpu) { |
| 727 | struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); |
| 728 | |
| 729 | if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || |
| 730 | pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || |
| 731 | pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || |
| 732 | need_activate_page_drain(cpu)) { |
| 733 | INIT_WORK(work, lru_add_drain_per_cpu); |
| 734 | schedule_work_on(cpu, work); |
| 735 | cpumask_set_cpu(cpu, &has_work); |
| 736 | } |
| 737 | } |
| 738 | |
| 739 | for_each_cpu(cpu, &has_work) |
| 740 | flush_work(&per_cpu(lru_add_drain_work, cpu)); |
| 741 | |
| 742 | put_online_cpus(); |
| 743 | mutex_unlock(&lock); |
| 744 | } |
| 745 | |
| 746 | /* |
| 747 | * Batched page_cache_release(). Decrement the reference count on all the |
| 748 | * passed pages. If it fell to zero then remove the page from the LRU and |
| 749 | * free it. |
| 750 | * |
| 751 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it |
| 752 | * for the remainder of the operation. |
| 753 | * |
| 754 | * The locking in this function is against shrink_inactive_list(): we recheck |
| 755 | * the page count inside the lock to see whether shrink_inactive_list() |
| 756 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() |
| 757 | * will free it. |
| 758 | */ |
| 759 | void release_pages(struct page **pages, int nr, int cold) |
| 760 | { |
| 761 | int i; |
| 762 | LIST_HEAD(pages_to_free); |
| 763 | struct zone *zone = NULL; |
| 764 | struct lruvec *lruvec; |
| 765 | unsigned long uninitialized_var(flags); |
| 766 | |
| 767 | for (i = 0; i < nr; i++) { |
| 768 | struct page *page = pages[i]; |
| 769 | |
| 770 | if (unlikely(PageCompound(page))) { |
| 771 | if (zone) { |
| 772 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
| 773 | zone = NULL; |
| 774 | } |
| 775 | put_compound_page(page); |
| 776 | continue; |
| 777 | } |
| 778 | |
| 779 | if (!put_page_testzero(page)) |
| 780 | continue; |
| 781 | |
| 782 | if (PageLRU(page)) { |
| 783 | struct zone *pagezone = page_zone(page); |
| 784 | |
| 785 | if (pagezone != zone) { |
| 786 | if (zone) |
| 787 | spin_unlock_irqrestore(&zone->lru_lock, |
| 788 | flags); |
| 789 | zone = pagezone; |
| 790 | spin_lock_irqsave(&zone->lru_lock, flags); |
| 791 | } |
| 792 | |
| 793 | lruvec = mem_cgroup_page_lruvec(page, zone); |
| 794 | VM_BUG_ON(!PageLRU(page)); |
| 795 | __ClearPageLRU(page); |
| 796 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); |
| 797 | } |
| 798 | |
| 799 | /* Clear Active bit in case of parallel mark_page_accessed */ |
| 800 | ClearPageActive(page); |
| 801 | |
| 802 | list_add(&page->lru, &pages_to_free); |
| 803 | } |
| 804 | if (zone) |
| 805 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
| 806 | |
| 807 | free_hot_cold_page_list(&pages_to_free, cold); |
| 808 | } |
| 809 | EXPORT_SYMBOL(release_pages); |
| 810 | |
| 811 | /* |
| 812 | * The pages which we're about to release may be in the deferred lru-addition |
| 813 | * queues. That would prevent them from really being freed right now. That's |
| 814 | * OK from a correctness point of view but is inefficient - those pages may be |
| 815 | * cache-warm and we want to give them back to the page allocator ASAP. |
| 816 | * |
| 817 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() |
| 818 | * and __pagevec_lru_add_active() call release_pages() directly to avoid |
| 819 | * mutual recursion. |
| 820 | */ |
| 821 | void __pagevec_release(struct pagevec *pvec) |
| 822 | { |
| 823 | lru_add_drain(); |
| 824 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); |
| 825 | pagevec_reinit(pvec); |
| 826 | } |
| 827 | EXPORT_SYMBOL(__pagevec_release); |
| 828 | |
| 829 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| 830 | /* used by __split_huge_page_refcount() */ |
| 831 | void lru_add_page_tail(struct page *page, struct page *page_tail, |
| 832 | struct lruvec *lruvec, struct list_head *list) |
| 833 | { |
| 834 | const int file = 0; |
| 835 | |
| 836 | VM_BUG_ON(!PageHead(page)); |
| 837 | VM_BUG_ON(PageCompound(page_tail)); |
| 838 | VM_BUG_ON(PageLRU(page_tail)); |
| 839 | VM_BUG_ON(NR_CPUS != 1 && |
| 840 | !spin_is_locked(&lruvec_zone(lruvec)->lru_lock)); |
| 841 | |
| 842 | if (!list) |
| 843 | SetPageLRU(page_tail); |
| 844 | |
| 845 | if (likely(PageLRU(page))) |
| 846 | list_add_tail(&page_tail->lru, &page->lru); |
| 847 | else if (list) { |
| 848 | /* page reclaim is reclaiming a huge page */ |
| 849 | get_page(page_tail); |
| 850 | list_add_tail(&page_tail->lru, list); |
| 851 | } else { |
| 852 | struct list_head *list_head; |
| 853 | /* |
| 854 | * Head page has not yet been counted, as an hpage, |
| 855 | * so we must account for each subpage individually. |
| 856 | * |
| 857 | * Use the standard add function to put page_tail on the list, |
| 858 | * but then correct its position so they all end up in order. |
| 859 | */ |
| 860 | add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail)); |
| 861 | list_head = page_tail->lru.prev; |
| 862 | list_move_tail(&page_tail->lru, list_head); |
| 863 | } |
| 864 | |
| 865 | if (!PageUnevictable(page)) |
| 866 | update_page_reclaim_stat(lruvec, file, PageActive(page_tail)); |
| 867 | } |
| 868 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
| 869 | |
| 870 | static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, |
| 871 | void *arg) |
| 872 | { |
| 873 | int file = page_is_file_cache(page); |
| 874 | int active = PageActive(page); |
| 875 | enum lru_list lru = page_lru(page); |
| 876 | |
| 877 | VM_BUG_ON(PageLRU(page)); |
| 878 | |
| 879 | SetPageLRU(page); |
| 880 | add_page_to_lru_list(page, lruvec, lru); |
| 881 | update_page_reclaim_stat(lruvec, file, active); |
| 882 | trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page)); |
| 883 | } |
| 884 | |
| 885 | /* |
| 886 | * Add the passed pages to the LRU, then drop the caller's refcount |
| 887 | * on them. Reinitialises the caller's pagevec. |
| 888 | */ |
| 889 | void __pagevec_lru_add(struct pagevec *pvec) |
| 890 | { |
| 891 | pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL); |
| 892 | } |
| 893 | EXPORT_SYMBOL(__pagevec_lru_add); |
| 894 | |
| 895 | /** |
| 896 | * pagevec_lookup - gang pagecache lookup |
| 897 | * @pvec: Where the resulting pages are placed |
| 898 | * @mapping: The address_space to search |
| 899 | * @start: The starting page index |
| 900 | * @nr_pages: The maximum number of pages |
| 901 | * |
| 902 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages |
| 903 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a |
| 904 | * reference against the pages in @pvec. |
| 905 | * |
| 906 | * The search returns a group of mapping-contiguous pages with ascending |
| 907 | * indexes. There may be holes in the indices due to not-present pages. |
| 908 | * |
| 909 | * pagevec_lookup() returns the number of pages which were found. |
| 910 | */ |
| 911 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, |
| 912 | pgoff_t start, unsigned nr_pages) |
| 913 | { |
| 914 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); |
| 915 | return pagevec_count(pvec); |
| 916 | } |
| 917 | EXPORT_SYMBOL(pagevec_lookup); |
| 918 | |
| 919 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
| 920 | pgoff_t *index, int tag, unsigned nr_pages) |
| 921 | { |
| 922 | pvec->nr = find_get_pages_tag(mapping, index, tag, |
| 923 | nr_pages, pvec->pages); |
| 924 | return pagevec_count(pvec); |
| 925 | } |
| 926 | EXPORT_SYMBOL(pagevec_lookup_tag); |
| 927 | |
| 928 | /* |
| 929 | * Perform any setup for the swap system |
| 930 | */ |
| 931 | void __init swap_setup(void) |
| 932 | { |
| 933 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); |
| 934 | #ifdef CONFIG_SWAP |
| 935 | int i; |
| 936 | |
| 937 | bdi_init(swapper_spaces[0].backing_dev_info); |
| 938 | for (i = 0; i < MAX_SWAPFILES; i++) { |
| 939 | spin_lock_init(&swapper_spaces[i].tree_lock); |
| 940 | INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear); |
| 941 | } |
| 942 | #endif |
| 943 | |
| 944 | /* Use a smaller cluster for small-memory machines */ |
| 945 | if (megs < 16) |
| 946 | page_cluster = 2; |
| 947 | else |
| 948 | page_cluster = 3; |
| 949 | /* |
| 950 | * Right now other parts of the system means that we |
| 951 | * _really_ don't want to cluster much more |
| 952 | */ |
| 953 | } |