mm/swap.c

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This source file includes following definitions.
__page_cache_release
__put_single_page
__put_compound_page
__put_page
put_pages_list
get_kernel_pages
get_kernel_page
pagevec_lru_move_fn
pagevec_move_tail_fn
pagevec_move_tail
rotate_reclaimable_page
update_page_reclaim_stat
__activate_page
activate_page_drain
need_activate_page_drain
activate_page
activate_page_drain
activate_page
__lru_cache_activate_page
mark_page_accessed
__lru_cache_add
lru_cache_add_anon
lru_cache_add_file
lru_cache_add
lru_cache_add_active_or_unevictable
lru_deactivate_file_fn
lru_deactivate_fn
lru_lazyfree_fn
lru_add_drain_cpu
deactivate_file_page
deactivate_page
mark_page_lazyfree
lru_add_drain
lru_add_drain_per_cpu
lru_add_drain_all
lru_add_drain_all
release_pages
__pagevec_release
lru_add_page_tail
__pagevec_lru_add_fn
__pagevec_lru_add
pagevec_lookup_entries
pagevec_remove_exceptionals
pagevec_lookup_range
pagevec_lookup_range_tag
pagevec_lookup_range_nr_tag
swap_setup
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/mm/swap.c
   4  *
   5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   6  */
   7 
   8 /*
   9  * This file contains the default values for the operation of the
  10  * Linux VM subsystem. Fine-tuning documentation can be found in
  11  * Documentation/admin-guide/sysctl/vm.rst.
  12  * Started 18.12.91
  13  * Swap aging added 23.2.95, Stephen Tweedie.
  14  * Buffermem limits added 12.3.98, Rik van Riel.
  15  */
  16 
  17 #include <linux/mm.h>
  18 #include <linux/sched.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/swap.h>
  21 #include <linux/mman.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/pagevec.h>
  24 #include <linux/init.h>
  25 #include <linux/export.h>
  26 #include <linux/mm_inline.h>
  27 #include <linux/percpu_counter.h>
  28 #include <linux/memremap.h>
  29 #include <linux/percpu.h>
  30 #include <linux/cpu.h>
  31 #include <linux/notifier.h>
  32 #include <linux/backing-dev.h>
  33 #include <linux/memcontrol.h>
  34 #include <linux/gfp.h>
  35 #include <linux/uio.h>
  36 #include <linux/hugetlb.h>
  37 #include <linux/page_idle.h>
  38 
  39 #include "internal.h"
  40 
  41 #define CREATE_TRACE_POINTS
  42 #include <trace/events/pagemap.h>
  43 
  44 /* How many pages do we try to swap or page in/out together? */
  45 int page_cluster;
  46 
  47 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
  48 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
  49 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
  50 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
  51 static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
  52 #ifdef CONFIG_SMP
  53 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
  54 #endif
  55 
  56 /*
  57  * This path almost never happens for VM activity - pages are normally
  58  * freed via pagevecs.  But it gets used by networking.
  59  */
  60 static void __page_cache_release(struct page *page)
  61 {
  62         if (PageLRU(page)) {
  63                 pg_data_t *pgdat = page_pgdat(page);
  64                 struct lruvec *lruvec;
  65                 unsigned long flags;
  66 
  67                 spin_lock_irqsave(&pgdat->lru_lock, flags);
  68                 lruvec = mem_cgroup_page_lruvec(page, pgdat);
  69                 VM_BUG_ON_PAGE(!PageLRU(page), page);
  70                 __ClearPageLRU(page);
  71                 del_page_from_lru_list(page, lruvec, page_off_lru(page));
  72                 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
  73         }
  74         __ClearPageWaiters(page);
  75 }
  76 
  77 static void __put_single_page(struct page *page)
  78 {
  79         __page_cache_release(page);
  80         mem_cgroup_uncharge(page);
  81         free_unref_page(page);
  82 }
  83 
  84 static void __put_compound_page(struct page *page)
  85 {
  86         compound_page_dtor *dtor;
  87 
  88         /*
  89          * __page_cache_release() is supposed to be called for thp, not for
  90          * hugetlb. This is because hugetlb page does never have PageLRU set
  91          * (it's never listed to any LRU lists) and no memcg routines should
  92          * be called for hugetlb (it has a separate hugetlb_cgroup.)
  93          */
  94         if (!PageHuge(page))
  95                 __page_cache_release(page);
  96         dtor = get_compound_page_dtor(page);
  97         (*dtor)(page);
  98 }
  99 
 100 void __put_page(struct page *page)
 101 {
 102         if (is_zone_device_page(page)) {
 103                 put_dev_pagemap(page->pgmap);
 104 
 105                 /*
 106                  * The page belongs to the device that created pgmap. Do
 107                  * not return it to page allocator.
 108                  */
 109                 return;
 110         }
 111 
 112         if (unlikely(PageCompound(page)))
 113                 __put_compound_page(page);
 114         else
 115                 __put_single_page(page);
 116 }
 117 EXPORT_SYMBOL(__put_page);
 118 
 119 /**
 120  * put_pages_list() - release a list of pages
 121  * @pages: list of pages threaded on page->lru
 122  *
 123  * Release a list of pages which are strung together on page.lru.  Currently
 124  * used by read_cache_pages() and related error recovery code.
 125  */
 126 void put_pages_list(struct list_head *pages)
 127 {
 128         while (!list_empty(pages)) {
 129                 struct page *victim;
 130 
 131                 victim = lru_to_page(pages);
 132                 list_del(&victim->lru);
 133                 put_page(victim);
 134         }
 135 }
 136 EXPORT_SYMBOL(put_pages_list);
 137 
 138 /*
 139  * get_kernel_pages() - pin kernel pages in memory
 140  * @kiov:       An array of struct kvec structures
 141  * @nr_segs:    number of segments to pin
 142  * @write:      pinning for read/write, currently ignored
 143  * @pages:      array that receives pointers to the pages pinned.
 144  *              Should be at least nr_segs long.
 145  *
 146  * Returns number of pages pinned. This may be fewer than the number
 147  * requested. If nr_pages is 0 or negative, returns 0. If no pages
 148  * were pinned, returns -errno. Each page returned must be released
 149  * with a put_page() call when it is finished with.
 150  */
 151 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
 152                 struct page **pages)
 153 {
 154         int seg;
 155 
 156         for (seg = 0; seg < nr_segs; seg++) {
 157                 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
 158                         return seg;
 159 
 160                 pages[seg] = kmap_to_page(kiov[seg].iov_base);
 161                 get_page(pages[seg]);
 162         }
 163 
 164         return seg;
 165 }
 166 EXPORT_SYMBOL_GPL(get_kernel_pages);
 167 
 168 /*
 169  * get_kernel_page() - pin a kernel page in memory
 170  * @start:      starting kernel address
 171  * @write:      pinning for read/write, currently ignored
 172  * @pages:      array that receives pointer to the page pinned.
 173  *              Must be at least nr_segs long.
 174  *
 175  * Returns 1 if page is pinned. If the page was not pinned, returns
 176  * -errno. The page returned must be released with a put_page() call
 177  * when it is finished with.
 178  */
 179 int get_kernel_page(unsigned long start, int write, struct page **pages)
 180 {
 181         const struct kvec kiov = {
 182                 .iov_base = (void *)start,
 183                 .iov_len = PAGE_SIZE
 184         };
 185 
 186         return get_kernel_pages(&kiov, 1, write, pages);
 187 }
 188 EXPORT_SYMBOL_GPL(get_kernel_page);
 189 
 190 static void pagevec_lru_move_fn(struct pagevec *pvec,
 191         void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
 192         void *arg)
 193 {
 194         int i;
 195         struct pglist_data *pgdat = NULL;
 196         struct lruvec *lruvec;
 197         unsigned long flags = 0;
 198 
 199         for (i = 0; i < pagevec_count(pvec); i++) {
 200                 struct page *page = pvec->pages[i];
 201                 struct pglist_data *pagepgdat = page_pgdat(page);
 202 
 203                 if (pagepgdat != pgdat) {
 204                         if (pgdat)
 205                                 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
 206                         pgdat = pagepgdat;
 207                         spin_lock_irqsave(&pgdat->lru_lock, flags);
 208                 }
 209 
 210                 lruvec = mem_cgroup_page_lruvec(page, pgdat);
 211                 (*move_fn)(page, lruvec, arg);
 212         }
 213         if (pgdat)
 214                 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
 215         release_pages(pvec->pages, pvec->nr);
 216         pagevec_reinit(pvec);
 217 }
 218 
 219 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
 220                                  void *arg)
 221 {
 222         int *pgmoved = arg;
 223 
 224         if (PageLRU(page) && !PageUnevictable(page)) {
 225                 del_page_from_lru_list(page, lruvec, page_lru(page));
 226                 ClearPageActive(page);
 227                 add_page_to_lru_list_tail(page, lruvec, page_lru(page));
 228                 (*pgmoved)++;
 229         }
 230 }
 231 
 232 /*
 233  * pagevec_move_tail() must be called with IRQ disabled.
 234  * Otherwise this may cause nasty races.
 235  */
 236 static void pagevec_move_tail(struct pagevec *pvec)
 237 {
 238         int pgmoved = 0;
 239 
 240         pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
 241         __count_vm_events(PGROTATED, pgmoved);
 242 }
 243 
 244 /*
 245  * Writeback is about to end against a page which has been marked for immediate
 246  * reclaim.  If it still appears to be reclaimable, move it to the tail of the
 247  * inactive list.
 248  */
 249 void rotate_reclaimable_page(struct page *page)
 250 {
 251         if (!PageLocked(page) && !PageDirty(page) &&
 252             !PageUnevictable(page) && PageLRU(page)) {
 253                 struct pagevec *pvec;
 254                 unsigned long flags;
 255 
 256                 get_page(page);
 257                 local_irq_save(flags);
 258                 pvec = this_cpu_ptr(&lru_rotate_pvecs);
 259                 if (!pagevec_add(pvec, page) || PageCompound(page))
 260                         pagevec_move_tail(pvec);
 261                 local_irq_restore(flags);
 262         }
 263 }
 264 
 265 static void update_page_reclaim_stat(struct lruvec *lruvec,
 266                                      int file, int rotated)
 267 {
 268         struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 269 
 270         reclaim_stat->recent_scanned[file]++;
 271         if (rotated)
 272                 reclaim_stat->recent_rotated[file]++;
 273 }
 274 
 275 static void __activate_page(struct page *page, struct lruvec *lruvec,
 276                             void *arg)
 277 {
 278         if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
 279                 int file = page_is_file_cache(page);
 280                 int lru = page_lru_base_type(page);
 281 
 282                 del_page_from_lru_list(page, lruvec, lru);
 283                 SetPageActive(page);
 284                 lru += LRU_ACTIVE;
 285                 add_page_to_lru_list(page, lruvec, lru);
 286                 trace_mm_lru_activate(page);
 287 
 288                 __count_vm_event(PGACTIVATE);
 289                 update_page_reclaim_stat(lruvec, file, 1);
 290         }
 291 }
 292 
 293 #ifdef CONFIG_SMP
 294 static void activate_page_drain(int cpu)
 295 {
 296         struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
 297 
 298         if (pagevec_count(pvec))
 299                 pagevec_lru_move_fn(pvec, __activate_page, NULL);
 300 }
 301 
 302 static bool need_activate_page_drain(int cpu)
 303 {
 304         return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
 305 }
 306 
 307 void activate_page(struct page *page)
 308 {
 309         page = compound_head(page);
 310         if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
 311                 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
 312 
 313                 get_page(page);
 314                 if (!pagevec_add(pvec, page) || PageCompound(page))
 315                         pagevec_lru_move_fn(pvec, __activate_page, NULL);
 316                 put_cpu_var(activate_page_pvecs);
 317         }
 318 }
 319 
 320 #else
 321 static inline void activate_page_drain(int cpu)
 322 {
 323 }
 324 
 325 void activate_page(struct page *page)
 326 {
 327         pg_data_t *pgdat = page_pgdat(page);
 328 
 329         page = compound_head(page);
 330         spin_lock_irq(&pgdat->lru_lock);
 331         __activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
 332         spin_unlock_irq(&pgdat->lru_lock);
 333 }
 334 #endif
 335 
 336 static void __lru_cache_activate_page(struct page *page)
 337 {
 338         struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
 339         int i;
 340 
 341         /*
 342          * Search backwards on the optimistic assumption that the page being
 343          * activated has just been added to this pagevec. Note that only
 344          * the local pagevec is examined as a !PageLRU page could be in the
 345          * process of being released, reclaimed, migrated or on a remote
 346          * pagevec that is currently being drained. Furthermore, marking
 347          * a remote pagevec's page PageActive potentially hits a race where
 348          * a page is marked PageActive just after it is added to the inactive
 349          * list causing accounting errors and BUG_ON checks to trigger.
 350          */
 351         for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
 352                 struct page *pagevec_page = pvec->pages[i];
 353 
 354                 if (pagevec_page == page) {
 355                         SetPageActive(page);
 356                         break;
 357                 }
 358         }
 359 
 360         put_cpu_var(lru_add_pvec);
 361 }
 362 
 363 /*
 364  * Mark a page as having seen activity.
 365  *
 366  * inactive,unreferenced        ->      inactive,referenced
 367  * inactive,referenced          ->      active,unreferenced
 368  * active,unreferenced          ->      active,referenced
 369  *
 370  * When a newly allocated page is not yet visible, so safe for non-atomic ops,
 371  * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
 372  */
 373 void mark_page_accessed(struct page *page)
 374 {
 375         page = compound_head(page);
 376         if (!PageActive(page) && !PageUnevictable(page) &&
 377                         PageReferenced(page)) {
 378 
 379                 /*
 380                  * If the page is on the LRU, queue it for activation via
 381                  * activate_page_pvecs. Otherwise, assume the page is on a
 382                  * pagevec, mark it active and it'll be moved to the active
 383                  * LRU on the next drain.
 384                  */
 385                 if (PageLRU(page))
 386                         activate_page(page);
 387                 else
 388                         __lru_cache_activate_page(page);
 389                 ClearPageReferenced(page);
 390                 if (page_is_file_cache(page))
 391                         workingset_activation(page);
 392         } else if (!PageReferenced(page)) {
 393                 SetPageReferenced(page);
 394         }
 395         if (page_is_idle(page))
 396                 clear_page_idle(page);
 397 }
 398 EXPORT_SYMBOL(mark_page_accessed);
 399 
 400 static void __lru_cache_add(struct page *page)
 401 {
 402         struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
 403 
 404         get_page(page);
 405         if (!pagevec_add(pvec, page) || PageCompound(page))
 406                 __pagevec_lru_add(pvec);
 407         put_cpu_var(lru_add_pvec);
 408 }
 409 
 410 /**
 411  * lru_cache_add_anon - add a page to the page lists
 412  * @page: the page to add
 413  */
 414 void lru_cache_add_anon(struct page *page)
 415 {
 416         if (PageActive(page))
 417                 ClearPageActive(page);
 418         __lru_cache_add(page);
 419 }
 420 
 421 void lru_cache_add_file(struct page *page)
 422 {
 423         if (PageActive(page))
 424                 ClearPageActive(page);
 425         __lru_cache_add(page);
 426 }
 427 EXPORT_SYMBOL(lru_cache_add_file);
 428 
 429 /**
 430  * lru_cache_add - add a page to a page list
 431  * @page: the page to be added to the LRU.
 432  *
 433  * Queue the page for addition to the LRU via pagevec. The decision on whether
 434  * to add the page to the [in]active [file|anon] list is deferred until the
 435  * pagevec is drained. This gives a chance for the caller of lru_cache_add()
 436  * have the page added to the active list using mark_page_accessed().
 437  */
 438 void lru_cache_add(struct page *page)
 439 {
 440         VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
 441         VM_BUG_ON_PAGE(PageLRU(page), page);
 442         __lru_cache_add(page);
 443 }
 444 
 445 /**
 446  * lru_cache_add_active_or_unevictable
 447  * @page:  the page to be added to LRU
 448  * @vma:   vma in which page is mapped for determining reclaimability
 449  *
 450  * Place @page on the active or unevictable LRU list, depending on its
 451  * evictability.  Note that if the page is not evictable, it goes
 452  * directly back onto it's zone's unevictable list, it does NOT use a
 453  * per cpu pagevec.
 454  */
 455 void lru_cache_add_active_or_unevictable(struct page *page,
 456                                          struct vm_area_struct *vma)
 457 {
 458         VM_BUG_ON_PAGE(PageLRU(page), page);
 459 
 460         if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
 461                 SetPageActive(page);
 462         else if (!TestSetPageMlocked(page)) {
 463                 /*
 464                  * We use the irq-unsafe __mod_zone_page_stat because this
 465                  * counter is not modified from interrupt context, and the pte
 466                  * lock is held(spinlock), which implies preemption disabled.
 467                  */
 468                 __mod_zone_page_state(page_zone(page), NR_MLOCK,
 469                                     hpage_nr_pages(page));
 470                 count_vm_event(UNEVICTABLE_PGMLOCKED);
 471         }
 472         lru_cache_add(page);
 473 }
 474 
 475 /*
 476  * If the page can not be invalidated, it is moved to the
 477  * inactive list to speed up its reclaim.  It is moved to the
 478  * head of the list, rather than the tail, to give the flusher
 479  * threads some time to write it out, as this is much more
 480  * effective than the single-page writeout from reclaim.
 481  *
 482  * If the page isn't page_mapped and dirty/writeback, the page
 483  * could reclaim asap using PG_reclaim.
 484  *
 485  * 1. active, mapped page -> none
 486  * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
 487  * 3. inactive, mapped page -> none
 488  * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
 489  * 5. inactive, clean -> inactive, tail
 490  * 6. Others -> none
 491  *
 492  * In 4, why it moves inactive's head, the VM expects the page would
 493  * be write it out by flusher threads as this is much more effective
 494  * than the single-page writeout from reclaim.
 495  */
 496 static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
 497                               void *arg)
 498 {
 499         int lru, file;
 500         bool active;
 501 
 502         if (!PageLRU(page))
 503                 return;
 504 
 505         if (PageUnevictable(page))
 506                 return;
 507 
 508         /* Some processes are using the page */
 509         if (page_mapped(page))
 510                 return;
 511 
 512         active = PageActive(page);
 513         file = page_is_file_cache(page);
 514         lru = page_lru_base_type(page);
 515 
 516         del_page_from_lru_list(page, lruvec, lru + active);
 517         ClearPageActive(page);
 518         ClearPageReferenced(page);
 519 
 520         if (PageWriteback(page) || PageDirty(page)) {
 521                 /*
 522                  * PG_reclaim could be raced with end_page_writeback
 523                  * It can make readahead confusing.  But race window
 524                  * is _really_ small and  it's non-critical problem.
 525                  */
 526                 add_page_to_lru_list(page, lruvec, lru);
 527                 SetPageReclaim(page);
 528         } else {
 529                 /*
 530                  * The page's writeback ends up during pagevec
 531                  * We moves tha page into tail of inactive.
 532                  */
 533                 add_page_to_lru_list_tail(page, lruvec, lru);
 534                 __count_vm_event(PGROTATED);
 535         }
 536 
 537         if (active)
 538                 __count_vm_event(PGDEACTIVATE);
 539         update_page_reclaim_stat(lruvec, file, 0);
 540 }
 541 
 542 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
 543                             void *arg)
 544 {
 545         if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
 546                 int file = page_is_file_cache(page);
 547                 int lru = page_lru_base_type(page);
 548 
 549                 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
 550                 ClearPageActive(page);
 551                 ClearPageReferenced(page);
 552                 add_page_to_lru_list(page, lruvec, lru);
 553 
 554                 __count_vm_events(PGDEACTIVATE, hpage_nr_pages(page));
 555                 update_page_reclaim_stat(lruvec, file, 0);
 556         }
 557 }
 558 
 559 static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
 560                             void *arg)
 561 {
 562         if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
 563             !PageSwapCache(page) && !PageUnevictable(page)) {
 564                 bool active = PageActive(page);
 565 
 566                 del_page_from_lru_list(page, lruvec,
 567                                        LRU_INACTIVE_ANON + active);
 568                 ClearPageActive(page);
 569                 ClearPageReferenced(page);
 570                 /*
 571                  * lazyfree pages are clean anonymous pages. They have
 572                  * SwapBacked flag cleared to distinguish normal anonymous
 573                  * pages
 574                  */
 575                 ClearPageSwapBacked(page);
 576                 add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
 577 
 578                 __count_vm_events(PGLAZYFREE, hpage_nr_pages(page));
 579                 count_memcg_page_event(page, PGLAZYFREE);
 580                 update_page_reclaim_stat(lruvec, 1, 0);
 581         }
 582 }
 583 
 584 /*
 585  * Drain pages out of the cpu's pagevecs.
 586  * Either "cpu" is the current CPU, and preemption has already been
 587  * disabled; or "cpu" is being hot-unplugged, and is already dead.
 588  */
 589 void lru_add_drain_cpu(int cpu)
 590 {
 591         struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
 592 
 593         if (pagevec_count(pvec))
 594                 __pagevec_lru_add(pvec);
 595 
 596         pvec = &per_cpu(lru_rotate_pvecs, cpu);
 597         if (pagevec_count(pvec)) {
 598                 unsigned long flags;
 599 
 600                 /* No harm done if a racing interrupt already did this */
 601                 local_irq_save(flags);
 602                 pagevec_move_tail(pvec);
 603                 local_irq_restore(flags);
 604         }
 605 
 606         pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
 607         if (pagevec_count(pvec))
 608                 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
 609 
 610         pvec = &per_cpu(lru_deactivate_pvecs, cpu);
 611         if (pagevec_count(pvec))
 612                 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
 613 
 614         pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
 615         if (pagevec_count(pvec))
 616                 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
 617 
 618         activate_page_drain(cpu);
 619 }
 620 
 621 /**
 622  * deactivate_file_page - forcefully deactivate a file page
 623  * @page: page to deactivate
 624  *
 625  * This function hints the VM that @page is a good reclaim candidate,
 626  * for example if its invalidation fails due to the page being dirty
 627  * or under writeback.
 628  */
 629 void deactivate_file_page(struct page *page)
 630 {
 631         /*
 632          * In a workload with many unevictable page such as mprotect,
 633          * unevictable page deactivation for accelerating reclaim is pointless.
 634          */
 635         if (PageUnevictable(page))
 636                 return;
 637 
 638         if (likely(get_page_unless_zero(page))) {
 639                 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
 640 
 641                 if (!pagevec_add(pvec, page) || PageCompound(page))
 642                         pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
 643                 put_cpu_var(lru_deactivate_file_pvecs);
 644         }
 645 }
 646 
 647 /*
 648  * deactivate_page - deactivate a page
 649  * @page: page to deactivate
 650  *
 651  * deactivate_page() moves @page to the inactive list if @page was on the active
 652  * list and was not an unevictable page.  This is done to accelerate the reclaim
 653  * of @page.
 654  */
 655 void deactivate_page(struct page *page)
 656 {
 657         if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
 658                 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
 659 
 660                 get_page(page);
 661                 if (!pagevec_add(pvec, page) || PageCompound(page))
 662                         pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
 663                 put_cpu_var(lru_deactivate_pvecs);
 664         }
 665 }
 666 
 667 /**
 668  * mark_page_lazyfree - make an anon page lazyfree
 669  * @page: page to deactivate
 670  *
 671  * mark_page_lazyfree() moves @page to the inactive file list.
 672  * This is done to accelerate the reclaim of @page.
 673  */
 674 void mark_page_lazyfree(struct page *page)
 675 {
 676         if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
 677             !PageSwapCache(page) && !PageUnevictable(page)) {
 678                 struct pagevec *pvec = &get_cpu_var(lru_lazyfree_pvecs);
 679 
 680                 get_page(page);
 681                 if (!pagevec_add(pvec, page) || PageCompound(page))
 682                         pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
 683                 put_cpu_var(lru_lazyfree_pvecs);
 684         }
 685 }
 686 
 687 void lru_add_drain(void)
 688 {
 689         lru_add_drain_cpu(get_cpu());
 690         put_cpu();
 691 }
 692 
 693 #ifdef CONFIG_SMP
 694 
 695 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
 696 
 697 static void lru_add_drain_per_cpu(struct work_struct *dummy)
 698 {
 699         lru_add_drain();
 700 }
 701 
 702 /*
 703  * Doesn't need any cpu hotplug locking because we do rely on per-cpu
 704  * kworkers being shut down before our page_alloc_cpu_dead callback is
 705  * executed on the offlined cpu.
 706  * Calling this function with cpu hotplug locks held can actually lead
 707  * to obscure indirect dependencies via WQ context.
 708  */
 709 void lru_add_drain_all(void)
 710 {
 711         static DEFINE_MUTEX(lock);
 712         static struct cpumask has_work;
 713         int cpu;
 714 
 715         /*
 716          * Make sure nobody triggers this path before mm_percpu_wq is fully
 717          * initialized.
 718          */
 719         if (WARN_ON(!mm_percpu_wq))
 720                 return;
 721 
 722         mutex_lock(&lock);
 723         cpumask_clear(&has_work);
 724 
 725         for_each_online_cpu(cpu) {
 726                 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
 727 
 728                 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
 729                     pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
 730                     pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
 731                     pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
 732                     pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
 733                     need_activate_page_drain(cpu)) {
 734                         INIT_WORK(work, lru_add_drain_per_cpu);
 735                         queue_work_on(cpu, mm_percpu_wq, work);
 736                         cpumask_set_cpu(cpu, &has_work);
 737                 }
 738         }
 739 
 740         for_each_cpu(cpu, &has_work)
 741                 flush_work(&per_cpu(lru_add_drain_work, cpu));
 742 
 743         mutex_unlock(&lock);
 744 }
 745 #else
 746 void lru_add_drain_all(void)
 747 {
 748         lru_add_drain();
 749 }
 750 #endif
 751 
 752 /**
 753  * release_pages - batched put_page()
 754  * @pages: array of pages to release
 755  * @nr: number of pages
 756  *
 757  * Decrement the reference count on all the pages in @pages.  If it
 758  * fell to zero, remove the page from the LRU and free it.
 759  */
 760 void release_pages(struct page **pages, int nr)
 761 {
 762         int i;
 763         LIST_HEAD(pages_to_free);
 764         struct pglist_data *locked_pgdat = NULL;
 765         struct lruvec *lruvec;
 766         unsigned long uninitialized_var(flags);
 767         unsigned int uninitialized_var(lock_batch);
 768 
 769         for (i = 0; i < nr; i++) {
 770                 struct page *page = pages[i];
 771 
 772                 /*
 773                  * Make sure the IRQ-safe lock-holding time does not get
 774                  * excessive with a continuous string of pages from the
 775                  * same pgdat. The lock is held only if pgdat != NULL.
 776                  */
 777                 if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
 778                         spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
 779                         locked_pgdat = NULL;
 780                 }
 781 
 782                 if (is_huge_zero_page(page))
 783                         continue;
 784 
 785                 if (is_zone_device_page(page)) {
 786                         if (locked_pgdat) {
 787                                 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
 788                                                        flags);
 789                                 locked_pgdat = NULL;
 790                         }
 791                         /*
 792                          * ZONE_DEVICE pages that return 'false' from
 793                          * put_devmap_managed_page() do not require special
 794                          * processing, and instead, expect a call to
 795                          * put_page_testzero().
 796                          */
 797                         if (put_devmap_managed_page(page))
 798                                 continue;
 799                 }
 800 
 801                 page = compound_head(page);
 802                 if (!put_page_testzero(page))
 803                         continue;
 804 
 805                 if (PageCompound(page)) {
 806                         if (locked_pgdat) {
 807                                 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
 808                                 locked_pgdat = NULL;
 809                         }
 810                         __put_compound_page(page);
 811                         continue;
 812                 }
 813 
 814                 if (PageLRU(page)) {
 815                         struct pglist_data *pgdat = page_pgdat(page);
 816 
 817                         if (pgdat != locked_pgdat) {
 818                                 if (locked_pgdat)
 819                                         spin_unlock_irqrestore(&locked_pgdat->lru_lock,
 820                                                                         flags);
 821                                 lock_batch = 0;
 822                                 locked_pgdat = pgdat;
 823                                 spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
 824                         }
 825 
 826                         lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
 827                         VM_BUG_ON_PAGE(!PageLRU(page), page);
 828                         __ClearPageLRU(page);
 829                         del_page_from_lru_list(page, lruvec, page_off_lru(page));
 830                 }
 831 
 832                 /* Clear Active bit in case of parallel mark_page_accessed */
 833                 __ClearPageActive(page);
 834                 __ClearPageWaiters(page);
 835 
 836                 list_add(&page->lru, &pages_to_free);
 837         }
 838         if (locked_pgdat)
 839                 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
 840 
 841         mem_cgroup_uncharge_list(&pages_to_free);
 842         free_unref_page_list(&pages_to_free);
 843 }
 844 EXPORT_SYMBOL(release_pages);
 845 
 846 /*
 847  * The pages which we're about to release may be in the deferred lru-addition
 848  * queues.  That would prevent them from really being freed right now.  That's
 849  * OK from a correctness point of view but is inefficient - those pages may be
 850  * cache-warm and we want to give them back to the page allocator ASAP.
 851  *
 852  * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()
 853  * and __pagevec_lru_add_active() call release_pages() directly to avoid
 854  * mutual recursion.
 855  */
 856 void __pagevec_release(struct pagevec *pvec)
 857 {
 858         if (!pvec->percpu_pvec_drained) {
 859                 lru_add_drain();
 860                 pvec->percpu_pvec_drained = true;
 861         }
 862         release_pages(pvec->pages, pagevec_count(pvec));
 863         pagevec_reinit(pvec);
 864 }
 865 EXPORT_SYMBOL(__pagevec_release);
 866 
 867 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 868 /* used by __split_huge_page_refcount() */
 869 void lru_add_page_tail(struct page *page, struct page *page_tail,
 870                        struct lruvec *lruvec, struct list_head *list)
 871 {
 872         const int file = 0;
 873 
 874         VM_BUG_ON_PAGE(!PageHead(page), page);
 875         VM_BUG_ON_PAGE(PageCompound(page_tail), page);
 876         VM_BUG_ON_PAGE(PageLRU(page_tail), page);
 877         lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
 878 
 879         if (!list)
 880                 SetPageLRU(page_tail);
 881 
 882         if (likely(PageLRU(page)))
 883                 list_add_tail(&page_tail->lru, &page->lru);
 884         else if (list) {
 885                 /* page reclaim is reclaiming a huge page */
 886                 get_page(page_tail);
 887                 list_add_tail(&page_tail->lru, list);
 888         } else {
 889                 /*
 890                  * Head page has not yet been counted, as an hpage,
 891                  * so we must account for each subpage individually.
 892                  *
 893                  * Put page_tail on the list at the correct position
 894                  * so they all end up in order.
 895                  */
 896                 add_page_to_lru_list_tail(page_tail, lruvec,
 897                                           page_lru(page_tail));
 898         }
 899 
 900         if (!PageUnevictable(page))
 901                 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
 902 }
 903 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 904 
 905 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
 906                                  void *arg)
 907 {
 908         enum lru_list lru;
 909         int was_unevictable = TestClearPageUnevictable(page);
 910 
 911         VM_BUG_ON_PAGE(PageLRU(page), page);
 912 
 913         SetPageLRU(page);
 914         /*
 915          * Page becomes evictable in two ways:
 916          * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
 917          * 2) Before acquiring LRU lock to put the page to correct LRU and then
 918          *   a) do PageLRU check with lock [check_move_unevictable_pages]
 919          *   b) do PageLRU check before lock [clear_page_mlock]
 920          *
 921          * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
 922          * following strict ordering:
 923          *
 924          * #0: __pagevec_lru_add_fn             #1: clear_page_mlock
 925          *
 926          * SetPageLRU()                         TestClearPageMlocked()
 927          * smp_mb() // explicit ordering        // above provides strict
 928          *                                      // ordering
 929          * PageMlocked()                        PageLRU()
 930          *
 931          *
 932          * if '#1' does not observe setting of PG_lru by '#0' and fails
 933          * isolation, the explicit barrier will make sure that page_evictable
 934          * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
 935          * can be reordered after PageMlocked check and can make '#1' to fail
 936          * the isolation of the page whose Mlocked bit is cleared (#0 is also
 937          * looking at the same page) and the evictable page will be stranded
 938          * in an unevictable LRU.
 939          */
 940         smp_mb();
 941 
 942         if (page_evictable(page)) {
 943                 lru = page_lru(page);
 944                 update_page_reclaim_stat(lruvec, page_is_file_cache(page),
 945                                          PageActive(page));
 946                 if (was_unevictable)
 947                         count_vm_event(UNEVICTABLE_PGRESCUED);
 948         } else {
 949                 lru = LRU_UNEVICTABLE;
 950                 ClearPageActive(page);
 951                 SetPageUnevictable(page);
 952                 if (!was_unevictable)
 953                         count_vm_event(UNEVICTABLE_PGCULLED);
 954         }
 955 
 956         add_page_to_lru_list(page, lruvec, lru);
 957         trace_mm_lru_insertion(page, lru);
 958 }
 959 
 960 /*
 961  * Add the passed pages to the LRU, then drop the caller's refcount
 962  * on them.  Reinitialises the caller's pagevec.
 963  */
 964 void __pagevec_lru_add(struct pagevec *pvec)
 965 {
 966         pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
 967 }
 968 EXPORT_SYMBOL(__pagevec_lru_add);
 969 
 970 /**
 971  * pagevec_lookup_entries - gang pagecache lookup
 972  * @pvec:       Where the resulting entries are placed
 973  * @mapping:    The address_space to search
 974  * @start:      The starting entry index
 975  * @nr_entries: The maximum number of pages
 976  * @indices:    The cache indices corresponding to the entries in @pvec
 977  *
 978  * pagevec_lookup_entries() will search for and return a group of up
 979  * to @nr_pages pages and shadow entries in the mapping.  All
 980  * entries are placed in @pvec.  pagevec_lookup_entries() takes a
 981  * reference against actual pages in @pvec.
 982  *
 983  * The search returns a group of mapping-contiguous entries with
 984  * ascending indexes.  There may be holes in the indices due to
 985  * not-present entries.
 986  *
 987  * pagevec_lookup_entries() returns the number of entries which were
 988  * found.
 989  */
 990 unsigned pagevec_lookup_entries(struct pagevec *pvec,
 991                                 struct address_space *mapping,
 992                                 pgoff_t start, unsigned nr_entries,
 993                                 pgoff_t *indices)
 994 {
 995         pvec->nr = find_get_entries(mapping, start, nr_entries,
 996                                     pvec->pages, indices);
 997         return pagevec_count(pvec);
 998 }
 999 
1000 /**
1001  * pagevec_remove_exceptionals - pagevec exceptionals pruning
1002  * @pvec:       The pagevec to prune
1003  *
1004  * pagevec_lookup_entries() fills both pages and exceptional radix
1005  * tree entries into the pagevec.  This function prunes all
1006  * exceptionals from @pvec without leaving holes, so that it can be
1007  * passed on to page-only pagevec operations.
1008  */
1009 void pagevec_remove_exceptionals(struct pagevec *pvec)
1010 {
1011         int i, j;
1012 
1013         for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1014                 struct page *page = pvec->pages[i];
1015                 if (!xa_is_value(page))
1016                         pvec->pages[j++] = page;
1017         }
1018         pvec->nr = j;
1019 }
1020 
1021 /**
1022  * pagevec_lookup_range - gang pagecache lookup
1023  * @pvec:       Where the resulting pages are placed
1024  * @mapping:    The address_space to search
1025  * @start:      The starting page index
1026  * @end:        The final page index
1027  *
1028  * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1029  * pages in the mapping starting from index @start and upto index @end
1030  * (inclusive).  The pages are placed in @pvec.  pagevec_lookup() takes a
1031  * reference against the pages in @pvec.
1032  *
1033  * The search returns a group of mapping-contiguous pages with ascending
1034  * indexes.  There may be holes in the indices due to not-present pages. We
1035  * also update @start to index the next page for the traversal.
1036  *
1037  * pagevec_lookup_range() returns the number of pages which were found. If this
1038  * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1039  * reached.
1040  */
1041 unsigned pagevec_lookup_range(struct pagevec *pvec,
1042                 struct address_space *mapping, pgoff_t *start, pgoff_t end)
1043 {
1044         pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
1045                                         pvec->pages);
1046         return pagevec_count(pvec);
1047 }
1048 EXPORT_SYMBOL(pagevec_lookup_range);
1049 
1050 unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1051                 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1052                 xa_mark_t tag)
1053 {
1054         pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1055                                         PAGEVEC_SIZE, pvec->pages);
1056         return pagevec_count(pvec);
1057 }
1058 EXPORT_SYMBOL(pagevec_lookup_range_tag);
1059 
1060 unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
1061                 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1062                 xa_mark_t tag, unsigned max_pages)
1063 {
1064         pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1065                 min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
1066         return pagevec_count(pvec);
1067 }
1068 EXPORT_SYMBOL(pagevec_lookup_range_nr_tag);
1069 /*
1070  * Perform any setup for the swap system
1071  */
1072 void __init swap_setup(void)
1073 {
1074         unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1075 
1076         /* Use a smaller cluster for small-memory machines */
1077         if (megs < 16)
1078                 page_cluster = 2;
1079         else
1080                 page_cluster = 3;
1081         /*
1082          * Right now other parts of the system means that we
1083          * _really_ don't want to cluster much more
1084          */
1085 }
/* [<][>][^][v][top][bottom][index][help] */
root/mm/swap.c

DEFINITIONS
