Loading...
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#include <linux/local_lock.h>
39
40#include "internal.h"
41
42#define CREATE_TRACE_POINTS
43#include <trace/events/pagemap.h>
44
45/* How many pages do we try to swap or page in/out together? */
46int page_cluster;
47
48/* Protecting only lru_rotate.pvec which requires disabling interrupts */
49struct lru_rotate {
50 local_lock_t lock;
51 struct pagevec pvec;
52};
53static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
54 .lock = INIT_LOCAL_LOCK(lock),
55};
56
57/*
58 * The following struct pagevec are grouped together because they are protected
59 * by disabling preemption (and interrupts remain enabled).
60 */
61struct lru_pvecs {
62 local_lock_t lock;
63 struct pagevec lru_add;
64 struct pagevec lru_deactivate_file;
65 struct pagevec lru_deactivate;
66 struct pagevec lru_lazyfree;
67#ifdef CONFIG_SMP
68 struct pagevec activate_page;
69#endif
70};
71static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
72 .lock = INIT_LOCAL_LOCK(lock),
73};
74
75/*
76 * This path almost never happens for VM activity - pages are normally
77 * freed via pagevecs. But it gets used by networking.
78 */
79static void __page_cache_release(struct page *page)
80{
81 if (PageLRU(page)) {
82 pg_data_t *pgdat = page_pgdat(page);
83 struct lruvec *lruvec;
84 unsigned long flags;
85
86 spin_lock_irqsave(&pgdat->lru_lock, flags);
87 lruvec = mem_cgroup_page_lruvec(page, pgdat);
88 VM_BUG_ON_PAGE(!PageLRU(page), page);
89 __ClearPageLRU(page);
90 del_page_from_lru_list(page, lruvec, page_off_lru(page));
91 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
92 }
93 __ClearPageWaiters(page);
94}
95
96static void __put_single_page(struct page *page)
97{
98 __page_cache_release(page);
99 mem_cgroup_uncharge(page);
100 free_unref_page(page);
101}
102
103static void __put_compound_page(struct page *page)
104{
105 /*
106 * __page_cache_release() is supposed to be called for thp, not for
107 * hugetlb. This is because hugetlb page does never have PageLRU set
108 * (it's never listed to any LRU lists) and no memcg routines should
109 * be called for hugetlb (it has a separate hugetlb_cgroup.)
110 */
111 if (!PageHuge(page))
112 __page_cache_release(page);
113 destroy_compound_page(page);
114}
115
116void __put_page(struct page *page)
117{
118 if (is_zone_device_page(page)) {
119 put_dev_pagemap(page->pgmap);
120
121 /*
122 * The page belongs to the device that created pgmap. Do
123 * not return it to page allocator.
124 */
125 return;
126 }
127
128 if (unlikely(PageCompound(page)))
129 __put_compound_page(page);
130 else
131 __put_single_page(page);
132}
133EXPORT_SYMBOL(__put_page);
134
135/**
136 * put_pages_list() - release a list of pages
137 * @pages: list of pages threaded on page->lru
138 *
139 * Release a list of pages which are strung together on page.lru. Currently
140 * used by read_cache_pages() and related error recovery code.
141 */
142void put_pages_list(struct list_head *pages)
143{
144 while (!list_empty(pages)) {
145 struct page *victim;
146
147 victim = lru_to_page(pages);
148 list_del(&victim->lru);
149 put_page(victim);
150 }
151}
152EXPORT_SYMBOL(put_pages_list);
153
154/*
155 * get_kernel_pages() - pin kernel pages in memory
156 * @kiov: An array of struct kvec structures
157 * @nr_segs: number of segments to pin
158 * @write: pinning for read/write, currently ignored
159 * @pages: array that receives pointers to the pages pinned.
160 * Should be at least nr_segs long.
161 *
162 * Returns number of pages pinned. This may be fewer than the number
163 * requested. If nr_pages is 0 or negative, returns 0. If no pages
164 * were pinned, returns -errno. Each page returned must be released
165 * with a put_page() call when it is finished with.
166 */
167int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
168 struct page **pages)
169{
170 int seg;
171
172 for (seg = 0; seg < nr_segs; seg++) {
173 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
174 return seg;
175
176 pages[seg] = kmap_to_page(kiov[seg].iov_base);
177 get_page(pages[seg]);
178 }
179
180 return seg;
181}
182EXPORT_SYMBOL_GPL(get_kernel_pages);
183
184/*
185 * get_kernel_page() - pin a kernel page in memory
186 * @start: starting kernel address
187 * @write: pinning for read/write, currently ignored
188 * @pages: array that receives pointer to the page pinned.
189 * Must be at least nr_segs long.
190 *
191 * Returns 1 if page is pinned. If the page was not pinned, returns
192 * -errno. The page returned must be released with a put_page() call
193 * when it is finished with.
194 */
195int get_kernel_page(unsigned long start, int write, struct page **pages)
196{
197 const struct kvec kiov = {
198 .iov_base = (void *)start,
199 .iov_len = PAGE_SIZE
200 };
201
202 return get_kernel_pages(&kiov, 1, write, pages);
203}
204EXPORT_SYMBOL_GPL(get_kernel_page);
205
206static void pagevec_lru_move_fn(struct pagevec *pvec,
207 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
208 void *arg)
209{
210 int i;
211 struct pglist_data *pgdat = NULL;
212 struct lruvec *lruvec;
213 unsigned long flags = 0;
214
215 for (i = 0; i < pagevec_count(pvec); i++) {
216 struct page *page = pvec->pages[i];
217 struct pglist_data *pagepgdat = page_pgdat(page);
218
219 if (pagepgdat != pgdat) {
220 if (pgdat)
221 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
222 pgdat = pagepgdat;
223 spin_lock_irqsave(&pgdat->lru_lock, flags);
224 }
225
226 lruvec = mem_cgroup_page_lruvec(page, pgdat);
227 (*move_fn)(page, lruvec, arg);
228 }
229 if (pgdat)
230 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
231 release_pages(pvec->pages, pvec->nr);
232 pagevec_reinit(pvec);
233}
234
235static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
236 void *arg)
237{
238 int *pgmoved = arg;
239
240 if (PageLRU(page) && !PageUnevictable(page)) {
241 del_page_from_lru_list(page, lruvec, page_lru(page));
242 ClearPageActive(page);
243 add_page_to_lru_list_tail(page, lruvec, page_lru(page));
244 (*pgmoved) += thp_nr_pages(page);
245 }
246}
247
248/*
249 * pagevec_move_tail() must be called with IRQ disabled.
250 * Otherwise this may cause nasty races.
251 */
252static void pagevec_move_tail(struct pagevec *pvec)
253{
254 int pgmoved = 0;
255
256 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
257 __count_vm_events(PGROTATED, pgmoved);
258}
259
260/*
261 * Writeback is about to end against a page which has been marked for immediate
262 * reclaim. If it still appears to be reclaimable, move it to the tail of the
263 * inactive list.
264 */
265void rotate_reclaimable_page(struct page *page)
266{
267 if (!PageLocked(page) && !PageDirty(page) &&
268 !PageUnevictable(page) && PageLRU(page)) {
269 struct pagevec *pvec;
270 unsigned long flags;
271
272 get_page(page);
273 local_lock_irqsave(&lru_rotate.lock, flags);
274 pvec = this_cpu_ptr(&lru_rotate.pvec);
275 if (!pagevec_add(pvec, page) || PageCompound(page))
276 pagevec_move_tail(pvec);
277 local_unlock_irqrestore(&lru_rotate.lock, flags);
278 }
279}
280
281void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
282{
283 do {
284 unsigned long lrusize;
285
286 /* Record cost event */
287 if (file)
288 lruvec->file_cost += nr_pages;
289 else
290 lruvec->anon_cost += nr_pages;
291
292 /*
293 * Decay previous events
294 *
295 * Because workloads change over time (and to avoid
296 * overflow) we keep these statistics as a floating
297 * average, which ends up weighing recent refaults
298 * more than old ones.
299 */
300 lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) +
301 lruvec_page_state(lruvec, NR_ACTIVE_ANON) +
302 lruvec_page_state(lruvec, NR_INACTIVE_FILE) +
303 lruvec_page_state(lruvec, NR_ACTIVE_FILE);
304
305 if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) {
306 lruvec->file_cost /= 2;
307 lruvec->anon_cost /= 2;
308 }
309 } while ((lruvec = parent_lruvec(lruvec)));
310}
311
312void lru_note_cost_page(struct page *page)
313{
314 lru_note_cost(mem_cgroup_page_lruvec(page, page_pgdat(page)),
315 page_is_file_lru(page), thp_nr_pages(page));
316}
317
318static void __activate_page(struct page *page, struct lruvec *lruvec,
319 void *arg)
320{
321 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
322 int lru = page_lru_base_type(page);
323 int nr_pages = thp_nr_pages(page);
324
325 del_page_from_lru_list(page, lruvec, lru);
326 SetPageActive(page);
327 lru += LRU_ACTIVE;
328 add_page_to_lru_list(page, lruvec, lru);
329 trace_mm_lru_activate(page);
330
331 __count_vm_events(PGACTIVATE, nr_pages);
332 __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
333 nr_pages);
334 }
335}
336
337#ifdef CONFIG_SMP
338static void activate_page_drain(int cpu)
339{
340 struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, cpu);
341
342 if (pagevec_count(pvec))
343 pagevec_lru_move_fn(pvec, __activate_page, NULL);
344}
345
346static bool need_activate_page_drain(int cpu)
347{
348 return pagevec_count(&per_cpu(lru_pvecs.activate_page, cpu)) != 0;
349}
350
351void activate_page(struct page *page)
352{
353 page = compound_head(page);
354 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
355 struct pagevec *pvec;
356
357 local_lock(&lru_pvecs.lock);
358 pvec = this_cpu_ptr(&lru_pvecs.activate_page);
359 get_page(page);
360 if (!pagevec_add(pvec, page) || PageCompound(page))
361 pagevec_lru_move_fn(pvec, __activate_page, NULL);
362 local_unlock(&lru_pvecs.lock);
363 }
364}
365
366#else
367static inline void activate_page_drain(int cpu)
368{
369}
370
371void activate_page(struct page *page)
372{
373 pg_data_t *pgdat = page_pgdat(page);
374
375 page = compound_head(page);
376 spin_lock_irq(&pgdat->lru_lock);
377 __activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
378 spin_unlock_irq(&pgdat->lru_lock);
379}
380#endif
381
382static void __lru_cache_activate_page(struct page *page)
383{
384 struct pagevec *pvec;
385 int i;
386
387 local_lock(&lru_pvecs.lock);
388 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
389
390 /*
391 * Search backwards on the optimistic assumption that the page being
392 * activated has just been added to this pagevec. Note that only
393 * the local pagevec is examined as a !PageLRU page could be in the
394 * process of being released, reclaimed, migrated or on a remote
395 * pagevec that is currently being drained. Furthermore, marking
396 * a remote pagevec's page PageActive potentially hits a race where
397 * a page is marked PageActive just after it is added to the inactive
398 * list causing accounting errors and BUG_ON checks to trigger.
399 */
400 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
401 struct page *pagevec_page = pvec->pages[i];
402
403 if (pagevec_page == page) {
404 SetPageActive(page);
405 break;
406 }
407 }
408
409 local_unlock(&lru_pvecs.lock);
410}
411
412/*
413 * Mark a page as having seen activity.
414 *
415 * inactive,unreferenced -> inactive,referenced
416 * inactive,referenced -> active,unreferenced
417 * active,unreferenced -> active,referenced
418 *
419 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
420 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
421 */
422void mark_page_accessed(struct page *page)
423{
424 page = compound_head(page);
425
426 if (!PageReferenced(page)) {
427 SetPageReferenced(page);
428 } else if (PageUnevictable(page)) {
429 /*
430 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
431 * this list is never rotated or maintained, so marking an
432 * evictable page accessed has no effect.
433 */
434 } else if (!PageActive(page)) {
435 /*
436 * If the page is on the LRU, queue it for activation via
437 * lru_pvecs.activate_page. Otherwise, assume the page is on a
438 * pagevec, mark it active and it'll be moved to the active
439 * LRU on the next drain.
440 */
441 if (PageLRU(page))
442 activate_page(page);
443 else
444 __lru_cache_activate_page(page);
445 ClearPageReferenced(page);
446 workingset_activation(page);
447 }
448 if (page_is_idle(page))
449 clear_page_idle(page);
450}
451EXPORT_SYMBOL(mark_page_accessed);
452
453/**
454 * lru_cache_add - add a page to a page list
455 * @page: the page to be added to the LRU.
456 *
457 * Queue the page for addition to the LRU via pagevec. The decision on whether
458 * to add the page to the [in]active [file|anon] list is deferred until the
459 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
460 * have the page added to the active list using mark_page_accessed().
461 */
462void lru_cache_add(struct page *page)
463{
464 struct pagevec *pvec;
465
466 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
467 VM_BUG_ON_PAGE(PageLRU(page), page);
468
469 get_page(page);
470 local_lock(&lru_pvecs.lock);
471 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
472 if (!pagevec_add(pvec, page) || PageCompound(page))
473 __pagevec_lru_add(pvec);
474 local_unlock(&lru_pvecs.lock);
475}
476EXPORT_SYMBOL(lru_cache_add);
477
478/**
479 * lru_cache_add_inactive_or_unevictable
480 * @page: the page to be added to LRU
481 * @vma: vma in which page is mapped for determining reclaimability
482 *
483 * Place @page on the inactive or unevictable LRU list, depending on its
484 * evictability. Note that if the page is not evictable, it goes
485 * directly back onto it's zone's unevictable list, it does NOT use a
486 * per cpu pagevec.
487 */
488void lru_cache_add_inactive_or_unevictable(struct page *page,
489 struct vm_area_struct *vma)
490{
491 bool unevictable;
492
493 VM_BUG_ON_PAGE(PageLRU(page), page);
494
495 unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;
496 if (unlikely(unevictable) && !TestSetPageMlocked(page)) {
497 int nr_pages = thp_nr_pages(page);
498 /*
499 * We use the irq-unsafe __mod_zone_page_stat because this
500 * counter is not modified from interrupt context, and the pte
501 * lock is held(spinlock), which implies preemption disabled.
502 */
503 __mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
504 count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
505 }
506 lru_cache_add(page);
507}
508
509/*
510 * If the page can not be invalidated, it is moved to the
511 * inactive list to speed up its reclaim. It is moved to the
512 * head of the list, rather than the tail, to give the flusher
513 * threads some time to write it out, as this is much more
514 * effective than the single-page writeout from reclaim.
515 *
516 * If the page isn't page_mapped and dirty/writeback, the page
517 * could reclaim asap using PG_reclaim.
518 *
519 * 1. active, mapped page -> none
520 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
521 * 3. inactive, mapped page -> none
522 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
523 * 5. inactive, clean -> inactive, tail
524 * 6. Others -> none
525 *
526 * In 4, why it moves inactive's head, the VM expects the page would
527 * be write it out by flusher threads as this is much more effective
528 * than the single-page writeout from reclaim.
529 */
530static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
531 void *arg)
532{
533 int lru;
534 bool active;
535 int nr_pages = thp_nr_pages(page);
536
537 if (!PageLRU(page))
538 return;
539
540 if (PageUnevictable(page))
541 return;
542
543 /* Some processes are using the page */
544 if (page_mapped(page))
545 return;
546
547 active = PageActive(page);
548 lru = page_lru_base_type(page);
549
550 del_page_from_lru_list(page, lruvec, lru + active);
551 ClearPageActive(page);
552 ClearPageReferenced(page);
553
554 if (PageWriteback(page) || PageDirty(page)) {
555 /*
556 * PG_reclaim could be raced with end_page_writeback
557 * It can make readahead confusing. But race window
558 * is _really_ small and it's non-critical problem.
559 */
560 add_page_to_lru_list(page, lruvec, lru);
561 SetPageReclaim(page);
562 } else {
563 /*
564 * The page's writeback ends up during pagevec
565 * We moves tha page into tail of inactive.
566 */
567 add_page_to_lru_list_tail(page, lruvec, lru);
568 __count_vm_events(PGROTATED, nr_pages);
569 }
570
571 if (active) {
572 __count_vm_events(PGDEACTIVATE, nr_pages);
573 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
574 nr_pages);
575 }
576}
577
578static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
579 void *arg)
580{
581 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
582 int lru = page_lru_base_type(page);
583 int nr_pages = thp_nr_pages(page);
584
585 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
586 ClearPageActive(page);
587 ClearPageReferenced(page);
588 add_page_to_lru_list(page, lruvec, lru);
589
590 __count_vm_events(PGDEACTIVATE, nr_pages);
591 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
592 nr_pages);
593 }
594}
595
596static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
597 void *arg)
598{
599 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
600 !PageSwapCache(page) && !PageUnevictable(page)) {
601 bool active = PageActive(page);
602 int nr_pages = thp_nr_pages(page);
603
604 del_page_from_lru_list(page, lruvec,
605 LRU_INACTIVE_ANON + active);
606 ClearPageActive(page);
607 ClearPageReferenced(page);
608 /*
609 * Lazyfree pages are clean anonymous pages. They have
610 * PG_swapbacked flag cleared, to distinguish them from normal
611 * anonymous pages
612 */
613 ClearPageSwapBacked(page);
614 add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
615
616 __count_vm_events(PGLAZYFREE, nr_pages);
617 __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
618 nr_pages);
619 }
620}
621
622/*
623 * Drain pages out of the cpu's pagevecs.
624 * Either "cpu" is the current CPU, and preemption has already been
625 * disabled; or "cpu" is being hot-unplugged, and is already dead.
626 */
627void lru_add_drain_cpu(int cpu)
628{
629 struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);
630
631 if (pagevec_count(pvec))
632 __pagevec_lru_add(pvec);
633
634 pvec = &per_cpu(lru_rotate.pvec, cpu);
635 /* Disabling interrupts below acts as a compiler barrier. */
636 if (data_race(pagevec_count(pvec))) {
637 unsigned long flags;
638
639 /* No harm done if a racing interrupt already did this */
640 local_lock_irqsave(&lru_rotate.lock, flags);
641 pagevec_move_tail(pvec);
642 local_unlock_irqrestore(&lru_rotate.lock, flags);
643 }
644
645 pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu);
646 if (pagevec_count(pvec))
647 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
648
649 pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu);
650 if (pagevec_count(pvec))
651 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
652
653 pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu);
654 if (pagevec_count(pvec))
655 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
656
657 activate_page_drain(cpu);
658}
659
660/**
661 * deactivate_file_page - forcefully deactivate a file page
662 * @page: page to deactivate
663 *
664 * This function hints the VM that @page is a good reclaim candidate,
665 * for example if its invalidation fails due to the page being dirty
666 * or under writeback.
667 */
668void deactivate_file_page(struct page *page)
669{
670 /*
671 * In a workload with many unevictable page such as mprotect,
672 * unevictable page deactivation for accelerating reclaim is pointless.
673 */
674 if (PageUnevictable(page))
675 return;
676
677 if (likely(get_page_unless_zero(page))) {
678 struct pagevec *pvec;
679
680 local_lock(&lru_pvecs.lock);
681 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file);
682
683 if (!pagevec_add(pvec, page) || PageCompound(page))
684 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
685 local_unlock(&lru_pvecs.lock);
686 }
687}
688
689/*
690 * deactivate_page - deactivate a page
691 * @page: page to deactivate
692 *
693 * deactivate_page() moves @page to the inactive list if @page was on the active
694 * list and was not an unevictable page. This is done to accelerate the reclaim
695 * of @page.
696 */
697void deactivate_page(struct page *page)
698{
699 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
700 struct pagevec *pvec;
701
702 local_lock(&lru_pvecs.lock);
703 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate);
704 get_page(page);
705 if (!pagevec_add(pvec, page) || PageCompound(page))
706 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
707 local_unlock(&lru_pvecs.lock);
708 }
709}
710
711/**
712 * mark_page_lazyfree - make an anon page lazyfree
713 * @page: page to deactivate
714 *
715 * mark_page_lazyfree() moves @page to the inactive file list.
716 * This is done to accelerate the reclaim of @page.
717 */
718void mark_page_lazyfree(struct page *page)
719{
720 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
721 !PageSwapCache(page) && !PageUnevictable(page)) {
722 struct pagevec *pvec;
723
724 local_lock(&lru_pvecs.lock);
725 pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree);
726 get_page(page);
727 if (!pagevec_add(pvec, page) || PageCompound(page))
728 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
729 local_unlock(&lru_pvecs.lock);
730 }
731}
732
733void lru_add_drain(void)
734{
735 local_lock(&lru_pvecs.lock);
736 lru_add_drain_cpu(smp_processor_id());
737 local_unlock(&lru_pvecs.lock);
738}
739
740void lru_add_drain_cpu_zone(struct zone *zone)
741{
742 local_lock(&lru_pvecs.lock);
743 lru_add_drain_cpu(smp_processor_id());
744 drain_local_pages(zone);
745 local_unlock(&lru_pvecs.lock);
746}
747
748#ifdef CONFIG_SMP
749
750static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
751
752static void lru_add_drain_per_cpu(struct work_struct *dummy)
753{
754 lru_add_drain();
755}
756
757/*
758 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
759 * kworkers being shut down before our page_alloc_cpu_dead callback is
760 * executed on the offlined cpu.
761 * Calling this function with cpu hotplug locks held can actually lead
762 * to obscure indirect dependencies via WQ context.
763 */
764void lru_add_drain_all(void)
765{
766 static seqcount_t seqcount = SEQCNT_ZERO(seqcount);
767 static DEFINE_MUTEX(lock);
768 static struct cpumask has_work;
769 int cpu, seq;
770
771 /*
772 * Make sure nobody triggers this path before mm_percpu_wq is fully
773 * initialized.
774 */
775 if (WARN_ON(!mm_percpu_wq))
776 return;
777
778 seq = raw_read_seqcount_latch(&seqcount);
779
780 mutex_lock(&lock);
781
782 /*
783 * Piggyback on drain started and finished while we waited for lock:
784 * all pages pended at the time of our enter were drained from vectors.
785 */
786 if (__read_seqcount_retry(&seqcount, seq))
787 goto done;
788
789 raw_write_seqcount_latch(&seqcount);
790
791 cpumask_clear(&has_work);
792
793 for_each_online_cpu(cpu) {
794 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
795
796 if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
797 data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
798 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
799 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
800 pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
801 need_activate_page_drain(cpu)) {
802 INIT_WORK(work, lru_add_drain_per_cpu);
803 queue_work_on(cpu, mm_percpu_wq, work);
804 cpumask_set_cpu(cpu, &has_work);
805 }
806 }
807
808 for_each_cpu(cpu, &has_work)
809 flush_work(&per_cpu(lru_add_drain_work, cpu));
810
811done:
812 mutex_unlock(&lock);
813}
814#else
815void lru_add_drain_all(void)
816{
817 lru_add_drain();
818}
819#endif
820
821/**
822 * release_pages - batched put_page()
823 * @pages: array of pages to release
824 * @nr: number of pages
825 *
826 * Decrement the reference count on all the pages in @pages. If it
827 * fell to zero, remove the page from the LRU and free it.
828 */
829void release_pages(struct page **pages, int nr)
830{
831 int i;
832 LIST_HEAD(pages_to_free);
833 struct pglist_data *locked_pgdat = NULL;
834 struct lruvec *lruvec;
835 unsigned long flags;
836 unsigned int lock_batch;
837
838 for (i = 0; i < nr; i++) {
839 struct page *page = pages[i];
840
841 /*
842 * Make sure the IRQ-safe lock-holding time does not get
843 * excessive with a continuous string of pages from the
844 * same pgdat. The lock is held only if pgdat != NULL.
845 */
846 if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
847 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
848 locked_pgdat = NULL;
849 }
850
851 if (is_huge_zero_page(page))
852 continue;
853
854 if (is_zone_device_page(page)) {
855 if (locked_pgdat) {
856 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
857 flags);
858 locked_pgdat = NULL;
859 }
860 /*
861 * ZONE_DEVICE pages that return 'false' from
862 * put_devmap_managed_page() do not require special
863 * processing, and instead, expect a call to
864 * put_page_testzero().
865 */
866 if (page_is_devmap_managed(page)) {
867 put_devmap_managed_page(page);
868 continue;
869 }
870 }
871
872 page = compound_head(page);
873 if (!put_page_testzero(page))
874 continue;
875
876 if (PageCompound(page)) {
877 if (locked_pgdat) {
878 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
879 locked_pgdat = NULL;
880 }
881 __put_compound_page(page);
882 continue;
883 }
884
885 if (PageLRU(page)) {
886 struct pglist_data *pgdat = page_pgdat(page);
887
888 if (pgdat != locked_pgdat) {
889 if (locked_pgdat)
890 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
891 flags);
892 lock_batch = 0;
893 locked_pgdat = pgdat;
894 spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
895 }
896
897 lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
898 VM_BUG_ON_PAGE(!PageLRU(page), page);
899 __ClearPageLRU(page);
900 del_page_from_lru_list(page, lruvec, page_off_lru(page));
901 }
902
903 /* Clear Active bit in case of parallel mark_page_accessed */
904 __ClearPageActive(page);
905 __ClearPageWaiters(page);
906
907 list_add(&page->lru, &pages_to_free);
908 }
909 if (locked_pgdat)
910 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
911
912 mem_cgroup_uncharge_list(&pages_to_free);
913 free_unref_page_list(&pages_to_free);
914}
915EXPORT_SYMBOL(release_pages);
916
917/*
918 * The pages which we're about to release may be in the deferred lru-addition
919 * queues. That would prevent them from really being freed right now. That's
920 * OK from a correctness point of view but is inefficient - those pages may be
921 * cache-warm and we want to give them back to the page allocator ASAP.
922 *
923 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
924 * and __pagevec_lru_add_active() call release_pages() directly to avoid
925 * mutual recursion.
926 */
927void __pagevec_release(struct pagevec *pvec)
928{
929 if (!pvec->percpu_pvec_drained) {
930 lru_add_drain();
931 pvec->percpu_pvec_drained = true;
932 }
933 release_pages(pvec->pages, pagevec_count(pvec));
934 pagevec_reinit(pvec);
935}
936EXPORT_SYMBOL(__pagevec_release);
937
938#ifdef CONFIG_TRANSPARENT_HUGEPAGE
939/* used by __split_huge_page_refcount() */
940void lru_add_page_tail(struct page *page, struct page *page_tail,
941 struct lruvec *lruvec, struct list_head *list)
942{
943 VM_BUG_ON_PAGE(!PageHead(page), page);
944 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
945 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
946 lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
947
948 if (!list)
949 SetPageLRU(page_tail);
950
951 if (likely(PageLRU(page)))
952 list_add_tail(&page_tail->lru, &page->lru);
953 else if (list) {
954 /* page reclaim is reclaiming a huge page */
955 get_page(page_tail);
956 list_add_tail(&page_tail->lru, list);
957 } else {
958 /*
959 * Head page has not yet been counted, as an hpage,
960 * so we must account for each subpage individually.
961 *
962 * Put page_tail on the list at the correct position
963 * so they all end up in order.
964 */
965 add_page_to_lru_list_tail(page_tail, lruvec,
966 page_lru(page_tail));
967 }
968}
969#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
970
971static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
972 void *arg)
973{
974 enum lru_list lru;
975 int was_unevictable = TestClearPageUnevictable(page);
976 int nr_pages = thp_nr_pages(page);
977
978 VM_BUG_ON_PAGE(PageLRU(page), page);
979
980 /*
981 * Page becomes evictable in two ways:
982 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
983 * 2) Before acquiring LRU lock to put the page to correct LRU and then
984 * a) do PageLRU check with lock [check_move_unevictable_pages]
985 * b) do PageLRU check before lock [clear_page_mlock]
986 *
987 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
988 * following strict ordering:
989 *
990 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
991 *
992 * SetPageLRU() TestClearPageMlocked()
993 * smp_mb() // explicit ordering // above provides strict
994 * // ordering
995 * PageMlocked() PageLRU()
996 *
997 *
998 * if '#1' does not observe setting of PG_lru by '#0' and fails
999 * isolation, the explicit barrier will make sure that page_evictable
1000 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
1001 * can be reordered after PageMlocked check and can make '#1' to fail
1002 * the isolation of the page whose Mlocked bit is cleared (#0 is also
1003 * looking at the same page) and the evictable page will be stranded
1004 * in an unevictable LRU.
1005 */
1006 SetPageLRU(page);
1007 smp_mb__after_atomic();
1008
1009 if (page_evictable(page)) {
1010 lru = page_lru(page);
1011 if (was_unevictable)
1012 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
1013 } else {
1014 lru = LRU_UNEVICTABLE;
1015 ClearPageActive(page);
1016 SetPageUnevictable(page);
1017 if (!was_unevictable)
1018 __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
1019 }
1020
1021 add_page_to_lru_list(page, lruvec, lru);
1022 trace_mm_lru_insertion(page, lru);
1023}
1024
1025/*
1026 * Add the passed pages to the LRU, then drop the caller's refcount
1027 * on them. Reinitialises the caller's pagevec.
1028 */
1029void __pagevec_lru_add(struct pagevec *pvec)
1030{
1031 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
1032}
1033
1034/**
1035 * pagevec_lookup_entries - gang pagecache lookup
1036 * @pvec: Where the resulting entries are placed
1037 * @mapping: The address_space to search
1038 * @start: The starting entry index
1039 * @nr_entries: The maximum number of pages
1040 * @indices: The cache indices corresponding to the entries in @pvec
1041 *
1042 * pagevec_lookup_entries() will search for and return a group of up
1043 * to @nr_pages pages and shadow entries in the mapping. All
1044 * entries are placed in @pvec. pagevec_lookup_entries() takes a
1045 * reference against actual pages in @pvec.
1046 *
1047 * The search returns a group of mapping-contiguous entries with
1048 * ascending indexes. There may be holes in the indices due to
1049 * not-present entries.
1050 *
1051 * Only one subpage of a Transparent Huge Page is returned in one call:
1052 * allowing truncate_inode_pages_range() to evict the whole THP without
1053 * cycling through a pagevec of extra references.
1054 *
1055 * pagevec_lookup_entries() returns the number of entries which were
1056 * found.
1057 */
1058unsigned pagevec_lookup_entries(struct pagevec *pvec,
1059 struct address_space *mapping,
1060 pgoff_t start, unsigned nr_entries,
1061 pgoff_t *indices)
1062{
1063 pvec->nr = find_get_entries(mapping, start, nr_entries,
1064 pvec->pages, indices);
1065 return pagevec_count(pvec);
1066}
1067
1068/**
1069 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1070 * @pvec: The pagevec to prune
1071 *
1072 * pagevec_lookup_entries() fills both pages and exceptional radix
1073 * tree entries into the pagevec. This function prunes all
1074 * exceptionals from @pvec without leaving holes, so that it can be
1075 * passed on to page-only pagevec operations.
1076 */
1077void pagevec_remove_exceptionals(struct pagevec *pvec)
1078{
1079 int i, j;
1080
1081 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1082 struct page *page = pvec->pages[i];
1083 if (!xa_is_value(page))
1084 pvec->pages[j++] = page;
1085 }
1086 pvec->nr = j;
1087}
1088
1089/**
1090 * pagevec_lookup_range - gang pagecache lookup
1091 * @pvec: Where the resulting pages are placed
1092 * @mapping: The address_space to search
1093 * @start: The starting page index
1094 * @end: The final page index
1095 *
1096 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1097 * pages in the mapping starting from index @start and upto index @end
1098 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
1099 * reference against the pages in @pvec.
1100 *
1101 * The search returns a group of mapping-contiguous pages with ascending
1102 * indexes. There may be holes in the indices due to not-present pages. We
1103 * also update @start to index the next page for the traversal.
1104 *
1105 * pagevec_lookup_range() returns the number of pages which were found. If this
1106 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1107 * reached.
1108 */
1109unsigned pagevec_lookup_range(struct pagevec *pvec,
1110 struct address_space *mapping, pgoff_t *start, pgoff_t end)
1111{
1112 pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
1113 pvec->pages);
1114 return pagevec_count(pvec);
1115}
1116EXPORT_SYMBOL(pagevec_lookup_range);
1117
1118unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1119 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1120 xa_mark_t tag)
1121{
1122 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1123 PAGEVEC_SIZE, pvec->pages);
1124 return pagevec_count(pvec);
1125}
1126EXPORT_SYMBOL(pagevec_lookup_range_tag);
1127
1128unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
1129 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1130 xa_mark_t tag, unsigned max_pages)
1131{
1132 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1133 min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
1134 return pagevec_count(pvec);
1135}
1136EXPORT_SYMBOL(pagevec_lookup_range_nr_tag);
1137/*
1138 * Perform any setup for the swap system
1139 */
1140void __init swap_setup(void)
1141{
1142 unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1143
1144 /* Use a smaller cluster for small-memory machines */
1145 if (megs < 16)
1146 page_cluster = 2;
1147 else
1148 page_cluster = 3;
1149 /*
1150 * Right now other parts of the system means that we
1151 * _really_ don't want to cluster much more
1152 */
1153}
1154
1155#ifdef CONFIG_DEV_PAGEMAP_OPS
1156void put_devmap_managed_page(struct page *page)
1157{
1158 int count;
1159
1160 if (WARN_ON_ONCE(!page_is_devmap_managed(page)))
1161 return;
1162
1163 count = page_ref_dec_return(page);
1164
1165 /*
1166 * devmap page refcounts are 1-based, rather than 0-based: if
1167 * refcount is 1, then the page is free and the refcount is
1168 * stable because nobody holds a reference on the page.
1169 */
1170 if (count == 1)
1171 free_devmap_managed_page(page);
1172 else if (!count)
1173 __put_page(page);
1174}
1175EXPORT_SYMBOL(put_devmap_managed_page);
1176#endif
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/memremap.h>
28#include <linux/percpu.h>
29#include <linux/cpu.h>
30#include <linux/notifier.h>
31#include <linux/backing-dev.h>
32#include <linux/memcontrol.h>
33#include <linux/gfp.h>
34#include <linux/uio.h>
35#include <linux/hugetlb.h>
36#include <linux/page_idle.h>
37
38#include "internal.h"
39
40#define CREATE_TRACE_POINTS
41#include <trace/events/pagemap.h>
42
43/* How many pages do we try to swap or page in/out together? */
44int page_cluster;
45
46static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
47static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
48static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
49static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
50#ifdef CONFIG_SMP
51static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
52#endif
53
54/*
55 * This path almost never happens for VM activity - pages are normally
56 * freed via pagevecs. But it gets used by networking.
57 */
58static void __page_cache_release(struct page *page)
59{
60 if (PageLRU(page)) {
61 struct zone *zone = page_zone(page);
62 struct lruvec *lruvec;
63 unsigned long flags;
64
65 spin_lock_irqsave(zone_lru_lock(zone), flags);
66 lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
67 VM_BUG_ON_PAGE(!PageLRU(page), page);
68 __ClearPageLRU(page);
69 del_page_from_lru_list(page, lruvec, page_off_lru(page));
70 spin_unlock_irqrestore(zone_lru_lock(zone), flags);
71 }
72 __ClearPageWaiters(page);
73 mem_cgroup_uncharge(page);
74}
75
76static void __put_single_page(struct page *page)
77{
78 __page_cache_release(page);
79 free_unref_page(page);
80}
81
82static void __put_compound_page(struct page *page)
83{
84 compound_page_dtor *dtor;
85
86 /*
87 * __page_cache_release() is supposed to be called for thp, not for
88 * hugetlb. This is because hugetlb page does never have PageLRU set
89 * (it's never listed to any LRU lists) and no memcg routines should
90 * be called for hugetlb (it has a separate hugetlb_cgroup.)
91 */
92 if (!PageHuge(page))
93 __page_cache_release(page);
94 dtor = get_compound_page_dtor(page);
95 (*dtor)(page);
96}
97
98void __put_page(struct page *page)
99{
100 if (is_zone_device_page(page)) {
101 put_dev_pagemap(page->pgmap);
102
103 /*
104 * The page belongs to the device that created pgmap. Do
105 * not return it to page allocator.
106 */
107 return;
108 }
109
110 if (unlikely(PageCompound(page)))
111 __put_compound_page(page);
112 else
113 __put_single_page(page);
114}
115EXPORT_SYMBOL(__put_page);
116
117/**
118 * put_pages_list() - release a list of pages
119 * @pages: list of pages threaded on page->lru
120 *
121 * Release a list of pages which are strung together on page.lru. Currently
122 * used by read_cache_pages() and related error recovery code.
123 */
124void put_pages_list(struct list_head *pages)
125{
126 while (!list_empty(pages)) {
127 struct page *victim;
128
129 victim = list_entry(pages->prev, struct page, lru);
130 list_del(&victim->lru);
131 put_page(victim);
132 }
133}
134EXPORT_SYMBOL(put_pages_list);
135
136/*
137 * get_kernel_pages() - pin kernel pages in memory
138 * @kiov: An array of struct kvec structures
139 * @nr_segs: number of segments to pin
140 * @write: pinning for read/write, currently ignored
141 * @pages: array that receives pointers to the pages pinned.
142 * Should be at least nr_segs long.
143 *
144 * Returns number of pages pinned. This may be fewer than the number
145 * requested. If nr_pages is 0 or negative, returns 0. If no pages
146 * were pinned, returns -errno. Each page returned must be released
147 * with a put_page() call when it is finished with.
148 */
149int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
150 struct page **pages)
151{
152 int seg;
153
154 for (seg = 0; seg < nr_segs; seg++) {
155 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
156 return seg;
157
158 pages[seg] = kmap_to_page(kiov[seg].iov_base);
159 get_page(pages[seg]);
160 }
161
162 return seg;
163}
164EXPORT_SYMBOL_GPL(get_kernel_pages);
165
166/*
167 * get_kernel_page() - pin a kernel page in memory
168 * @start: starting kernel address
169 * @write: pinning for read/write, currently ignored
170 * @pages: array that receives pointer to the page pinned.
171 * Must be at least nr_segs long.
172 *
173 * Returns 1 if page is pinned. If the page was not pinned, returns
174 * -errno. The page returned must be released with a put_page() call
175 * when it is finished with.
176 */
177int get_kernel_page(unsigned long start, int write, struct page **pages)
178{
179 const struct kvec kiov = {
180 .iov_base = (void *)start,
181 .iov_len = PAGE_SIZE
182 };
183
184 return get_kernel_pages(&kiov, 1, write, pages);
185}
186EXPORT_SYMBOL_GPL(get_kernel_page);
187
188static void pagevec_lru_move_fn(struct pagevec *pvec,
189 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
190 void *arg)
191{
192 int i;
193 struct pglist_data *pgdat = NULL;
194 struct lruvec *lruvec;
195 unsigned long flags = 0;
196
197 for (i = 0; i < pagevec_count(pvec); i++) {
198 struct page *page = pvec->pages[i];
199 struct pglist_data *pagepgdat = page_pgdat(page);
200
201 if (pagepgdat != pgdat) {
202 if (pgdat)
203 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
204 pgdat = pagepgdat;
205 spin_lock_irqsave(&pgdat->lru_lock, flags);
206 }
207
208 lruvec = mem_cgroup_page_lruvec(page, pgdat);
209 (*move_fn)(page, lruvec, arg);
210 }
211 if (pgdat)
212 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
213 release_pages(pvec->pages, pvec->nr);
214 pagevec_reinit(pvec);
215}
216
217static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
218 void *arg)
219{
220 int *pgmoved = arg;
221
222 if (PageLRU(page) && !PageUnevictable(page)) {
223 del_page_from_lru_list(page, lruvec, page_lru(page));
224 ClearPageActive(page);
225 add_page_to_lru_list_tail(page, lruvec, page_lru(page));
226 (*pgmoved)++;
227 }
228}
229
230/*
231 * pagevec_move_tail() must be called with IRQ disabled.
232 * Otherwise this may cause nasty races.
233 */
234static void pagevec_move_tail(struct pagevec *pvec)
235{
236 int pgmoved = 0;
237
238 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
239 __count_vm_events(PGROTATED, pgmoved);
240}
241
242/*
243 * Writeback is about to end against a page which has been marked for immediate
244 * reclaim. If it still appears to be reclaimable, move it to the tail of the
245 * inactive list.
246 */
247void rotate_reclaimable_page(struct page *page)
248{
249 if (!PageLocked(page) && !PageDirty(page) &&
250 !PageUnevictable(page) && PageLRU(page)) {
251 struct pagevec *pvec;
252 unsigned long flags;
253
254 get_page(page);
255 local_irq_save(flags);
256 pvec = this_cpu_ptr(&lru_rotate_pvecs);
257 if (!pagevec_add(pvec, page) || PageCompound(page))
258 pagevec_move_tail(pvec);
259 local_irq_restore(flags);
260 }
261}
262
263static void update_page_reclaim_stat(struct lruvec *lruvec,
264 int file, int rotated)
265{
266 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
267
268 reclaim_stat->recent_scanned[file]++;
269 if (rotated)
270 reclaim_stat->recent_rotated[file]++;
271}
272
273static void __activate_page(struct page *page, struct lruvec *lruvec,
274 void *arg)
275{
276 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
277 int file = page_is_file_cache(page);
278 int lru = page_lru_base_type(page);
279
280 del_page_from_lru_list(page, lruvec, lru);
281 SetPageActive(page);
282 lru += LRU_ACTIVE;
283 add_page_to_lru_list(page, lruvec, lru);
284 trace_mm_lru_activate(page);
285
286 __count_vm_event(PGACTIVATE);
287 update_page_reclaim_stat(lruvec, file, 1);
288 }
289}
290
291#ifdef CONFIG_SMP
292static void activate_page_drain(int cpu)
293{
294 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
295
296 if (pagevec_count(pvec))
297 pagevec_lru_move_fn(pvec, __activate_page, NULL);
298}
299
300static bool need_activate_page_drain(int cpu)
301{
302 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
303}
304
305void activate_page(struct page *page)
306{
307 page = compound_head(page);
308 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
309 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
310
311 get_page(page);
312 if (!pagevec_add(pvec, page) || PageCompound(page))
313 pagevec_lru_move_fn(pvec, __activate_page, NULL);
314 put_cpu_var(activate_page_pvecs);
315 }
316}
317
318#else
319static inline void activate_page_drain(int cpu)
320{
321}
322
323static bool need_activate_page_drain(int cpu)
324{
325 return false;
326}
327
328void activate_page(struct page *page)
329{
330 struct zone *zone = page_zone(page);
331
332 page = compound_head(page);
333 spin_lock_irq(zone_lru_lock(zone));
334 __activate_page(page, mem_cgroup_page_lruvec(page, zone->zone_pgdat), NULL);
335 spin_unlock_irq(zone_lru_lock(zone));
336}
337#endif
338
339static void __lru_cache_activate_page(struct page *page)
340{
341 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
342 int i;
343
344 /*
345 * Search backwards on the optimistic assumption that the page being
346 * activated has just been added to this pagevec. Note that only
347 * the local pagevec is examined as a !PageLRU page could be in the
348 * process of being released, reclaimed, migrated or on a remote
349 * pagevec that is currently being drained. Furthermore, marking
350 * a remote pagevec's page PageActive potentially hits a race where
351 * a page is marked PageActive just after it is added to the inactive
352 * list causing accounting errors and BUG_ON checks to trigger.
353 */
354 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
355 struct page *pagevec_page = pvec->pages[i];
356
357 if (pagevec_page == page) {
358 SetPageActive(page);
359 break;
360 }
361 }
362
363 put_cpu_var(lru_add_pvec);
364}
365
366/*
367 * Mark a page as having seen activity.
368 *
369 * inactive,unreferenced -> inactive,referenced
370 * inactive,referenced -> active,unreferenced
371 * active,unreferenced -> active,referenced
372 *
373 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
374 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
375 */
376void mark_page_accessed(struct page *page)
377{
378 page = compound_head(page);
379 if (!PageActive(page) && !PageUnevictable(page) &&
380 PageReferenced(page)) {
381
382 /*
383 * If the page is on the LRU, queue it for activation via
384 * activate_page_pvecs. Otherwise, assume the page is on a
385 * pagevec, mark it active and it'll be moved to the active
386 * LRU on the next drain.
387 */
388 if (PageLRU(page))
389 activate_page(page);
390 else
391 __lru_cache_activate_page(page);
392 ClearPageReferenced(page);
393 if (page_is_file_cache(page))
394 workingset_activation(page);
395 } else if (!PageReferenced(page)) {
396 SetPageReferenced(page);
397 }
398 if (page_is_idle(page))
399 clear_page_idle(page);
400}
401EXPORT_SYMBOL(mark_page_accessed);
402
403static void __lru_cache_add(struct page *page)
404{
405 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
406
407 get_page(page);
408 if (!pagevec_add(pvec, page) || PageCompound(page))
409 __pagevec_lru_add(pvec);
410 put_cpu_var(lru_add_pvec);
411}
412
413/**
414 * lru_cache_add_anon - add a page to the page lists
415 * @page: the page to add
416 */
417void lru_cache_add_anon(struct page *page)
418{
419 if (PageActive(page))
420 ClearPageActive(page);
421 __lru_cache_add(page);
422}
423
424void lru_cache_add_file(struct page *page)
425{
426 if (PageActive(page))
427 ClearPageActive(page);
428 __lru_cache_add(page);
429}
430EXPORT_SYMBOL(lru_cache_add_file);
431
432/**
433 * lru_cache_add - add a page to a page list
434 * @page: the page to be added to the LRU.
435 *
436 * Queue the page for addition to the LRU via pagevec. The decision on whether
437 * to add the page to the [in]active [file|anon] list is deferred until the
438 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
439 * have the page added to the active list using mark_page_accessed().
440 */
441void lru_cache_add(struct page *page)
442{
443 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
444 VM_BUG_ON_PAGE(PageLRU(page), page);
445 __lru_cache_add(page);
446}
447
448/**
449 * lru_cache_add_active_or_unevictable
450 * @page: the page to be added to LRU
451 * @vma: vma in which page is mapped for determining reclaimability
452 *
453 * Place @page on the active or unevictable LRU list, depending on its
454 * evictability. Note that if the page is not evictable, it goes
455 * directly back onto it's zone's unevictable list, it does NOT use a
456 * per cpu pagevec.
457 */
458void lru_cache_add_active_or_unevictable(struct page *page,
459 struct vm_area_struct *vma)
460{
461 VM_BUG_ON_PAGE(PageLRU(page), page);
462
463 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
464 SetPageActive(page);
465 else if (!TestSetPageMlocked(page)) {
466 /*
467 * We use the irq-unsafe __mod_zone_page_stat because this
468 * counter is not modified from interrupt context, and the pte
469 * lock is held(spinlock), which implies preemption disabled.
470 */
471 __mod_zone_page_state(page_zone(page), NR_MLOCK,
472 hpage_nr_pages(page));
473 count_vm_event(UNEVICTABLE_PGMLOCKED);
474 }
475 lru_cache_add(page);
476}
477
478/*
479 * If the page can not be invalidated, it is moved to the
480 * inactive list to speed up its reclaim. It is moved to the
481 * head of the list, rather than the tail, to give the flusher
482 * threads some time to write it out, as this is much more
483 * effective than the single-page writeout from reclaim.
484 *
485 * If the page isn't page_mapped and dirty/writeback, the page
486 * could reclaim asap using PG_reclaim.
487 *
488 * 1. active, mapped page -> none
489 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
490 * 3. inactive, mapped page -> none
491 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
492 * 5. inactive, clean -> inactive, tail
493 * 6. Others -> none
494 *
495 * In 4, why it moves inactive's head, the VM expects the page would
496 * be write it out by flusher threads as this is much more effective
497 * than the single-page writeout from reclaim.
498 */
499static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
500 void *arg)
501{
502 int lru, file;
503 bool active;
504
505 if (!PageLRU(page))
506 return;
507
508 if (PageUnevictable(page))
509 return;
510
511 /* Some processes are using the page */
512 if (page_mapped(page))
513 return;
514
515 active = PageActive(page);
516 file = page_is_file_cache(page);
517 lru = page_lru_base_type(page);
518
519 del_page_from_lru_list(page, lruvec, lru + active);
520 ClearPageActive(page);
521 ClearPageReferenced(page);
522 add_page_to_lru_list(page, lruvec, lru);
523
524 if (PageWriteback(page) || PageDirty(page)) {
525 /*
526 * PG_reclaim could be raced with end_page_writeback
527 * It can make readahead confusing. But race window
528 * is _really_ small and it's non-critical problem.
529 */
530 SetPageReclaim(page);
531 } else {
532 /*
533 * The page's writeback ends up during pagevec
534 * We moves tha page into tail of inactive.
535 */
536 list_move_tail(&page->lru, &lruvec->lists[lru]);
537 __count_vm_event(PGROTATED);
538 }
539
540 if (active)
541 __count_vm_event(PGDEACTIVATE);
542 update_page_reclaim_stat(lruvec, file, 0);
543}
544
545
546static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
547 void *arg)
548{
549 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
550 !PageSwapCache(page) && !PageUnevictable(page)) {
551 bool active = PageActive(page);
552
553 del_page_from_lru_list(page, lruvec,
554 LRU_INACTIVE_ANON + active);
555 ClearPageActive(page);
556 ClearPageReferenced(page);
557 /*
558 * lazyfree pages are clean anonymous pages. They have
559 * SwapBacked flag cleared to distinguish normal anonymous
560 * pages
561 */
562 ClearPageSwapBacked(page);
563 add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
564
565 __count_vm_events(PGLAZYFREE, hpage_nr_pages(page));
566 count_memcg_page_event(page, PGLAZYFREE);
567 update_page_reclaim_stat(lruvec, 1, 0);
568 }
569}
570
571/*
572 * Drain pages out of the cpu's pagevecs.
573 * Either "cpu" is the current CPU, and preemption has already been
574 * disabled; or "cpu" is being hot-unplugged, and is already dead.
575 */
576void lru_add_drain_cpu(int cpu)
577{
578 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
579
580 if (pagevec_count(pvec))
581 __pagevec_lru_add(pvec);
582
583 pvec = &per_cpu(lru_rotate_pvecs, cpu);
584 if (pagevec_count(pvec)) {
585 unsigned long flags;
586
587 /* No harm done if a racing interrupt already did this */
588 local_irq_save(flags);
589 pagevec_move_tail(pvec);
590 local_irq_restore(flags);
591 }
592
593 pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
594 if (pagevec_count(pvec))
595 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
596
597 pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
598 if (pagevec_count(pvec))
599 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
600
601 activate_page_drain(cpu);
602}
603
604/**
605 * deactivate_file_page - forcefully deactivate a file page
606 * @page: page to deactivate
607 *
608 * This function hints the VM that @page is a good reclaim candidate,
609 * for example if its invalidation fails due to the page being dirty
610 * or under writeback.
611 */
612void deactivate_file_page(struct page *page)
613{
614 /*
615 * In a workload with many unevictable page such as mprotect,
616 * unevictable page deactivation for accelerating reclaim is pointless.
617 */
618 if (PageUnevictable(page))
619 return;
620
621 if (likely(get_page_unless_zero(page))) {
622 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
623
624 if (!pagevec_add(pvec, page) || PageCompound(page))
625 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
626 put_cpu_var(lru_deactivate_file_pvecs);
627 }
628}
629
630/**
631 * mark_page_lazyfree - make an anon page lazyfree
632 * @page: page to deactivate
633 *
634 * mark_page_lazyfree() moves @page to the inactive file list.
635 * This is done to accelerate the reclaim of @page.
636 */
637void mark_page_lazyfree(struct page *page)
638{
639 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
640 !PageSwapCache(page) && !PageUnevictable(page)) {
641 struct pagevec *pvec = &get_cpu_var(lru_lazyfree_pvecs);
642
643 get_page(page);
644 if (!pagevec_add(pvec, page) || PageCompound(page))
645 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
646 put_cpu_var(lru_lazyfree_pvecs);
647 }
648}
649
650void lru_add_drain(void)
651{
652 lru_add_drain_cpu(get_cpu());
653 put_cpu();
654}
655
656static void lru_add_drain_per_cpu(struct work_struct *dummy)
657{
658 lru_add_drain();
659}
660
661static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
662
663/*
664 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
665 * kworkers being shut down before our page_alloc_cpu_dead callback is
666 * executed on the offlined cpu.
667 * Calling this function with cpu hotplug locks held can actually lead
668 * to obscure indirect dependencies via WQ context.
669 */
670void lru_add_drain_all(void)
671{
672 static DEFINE_MUTEX(lock);
673 static struct cpumask has_work;
674 int cpu;
675
676 /*
677 * Make sure nobody triggers this path before mm_percpu_wq is fully
678 * initialized.
679 */
680 if (WARN_ON(!mm_percpu_wq))
681 return;
682
683 mutex_lock(&lock);
684 cpumask_clear(&has_work);
685
686 for_each_online_cpu(cpu) {
687 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
688
689 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
690 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
691 pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
692 pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
693 need_activate_page_drain(cpu)) {
694 INIT_WORK(work, lru_add_drain_per_cpu);
695 queue_work_on(cpu, mm_percpu_wq, work);
696 cpumask_set_cpu(cpu, &has_work);
697 }
698 }
699
700 for_each_cpu(cpu, &has_work)
701 flush_work(&per_cpu(lru_add_drain_work, cpu));
702
703 mutex_unlock(&lock);
704}
705
706/**
707 * release_pages - batched put_page()
708 * @pages: array of pages to release
709 * @nr: number of pages
710 *
711 * Decrement the reference count on all the pages in @pages. If it
712 * fell to zero, remove the page from the LRU and free it.
713 */
714void release_pages(struct page **pages, int nr)
715{
716 int i;
717 LIST_HEAD(pages_to_free);
718 struct pglist_data *locked_pgdat = NULL;
719 struct lruvec *lruvec;
720 unsigned long uninitialized_var(flags);
721 unsigned int uninitialized_var(lock_batch);
722
723 for (i = 0; i < nr; i++) {
724 struct page *page = pages[i];
725
726 /*
727 * Make sure the IRQ-safe lock-holding time does not get
728 * excessive with a continuous string of pages from the
729 * same pgdat. The lock is held only if pgdat != NULL.
730 */
731 if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
732 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
733 locked_pgdat = NULL;
734 }
735
736 if (is_huge_zero_page(page))
737 continue;
738
739 /* Device public page can not be huge page */
740 if (is_device_public_page(page)) {
741 if (locked_pgdat) {
742 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
743 flags);
744 locked_pgdat = NULL;
745 }
746 put_zone_device_private_or_public_page(page);
747 continue;
748 }
749
750 page = compound_head(page);
751 if (!put_page_testzero(page))
752 continue;
753
754 if (PageCompound(page)) {
755 if (locked_pgdat) {
756 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
757 locked_pgdat = NULL;
758 }
759 __put_compound_page(page);
760 continue;
761 }
762
763 if (PageLRU(page)) {
764 struct pglist_data *pgdat = page_pgdat(page);
765
766 if (pgdat != locked_pgdat) {
767 if (locked_pgdat)
768 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
769 flags);
770 lock_batch = 0;
771 locked_pgdat = pgdat;
772 spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
773 }
774
775 lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
776 VM_BUG_ON_PAGE(!PageLRU(page), page);
777 __ClearPageLRU(page);
778 del_page_from_lru_list(page, lruvec, page_off_lru(page));
779 }
780
781 /* Clear Active bit in case of parallel mark_page_accessed */
782 __ClearPageActive(page);
783 __ClearPageWaiters(page);
784
785 list_add(&page->lru, &pages_to_free);
786 }
787 if (locked_pgdat)
788 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
789
790 mem_cgroup_uncharge_list(&pages_to_free);
791 free_unref_page_list(&pages_to_free);
792}
793EXPORT_SYMBOL(release_pages);
794
795/*
796 * The pages which we're about to release may be in the deferred lru-addition
797 * queues. That would prevent them from really being freed right now. That's
798 * OK from a correctness point of view but is inefficient - those pages may be
799 * cache-warm and we want to give them back to the page allocator ASAP.
800 *
801 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
802 * and __pagevec_lru_add_active() call release_pages() directly to avoid
803 * mutual recursion.
804 */
805void __pagevec_release(struct pagevec *pvec)
806{
807 if (!pvec->percpu_pvec_drained) {
808 lru_add_drain();
809 pvec->percpu_pvec_drained = true;
810 }
811 release_pages(pvec->pages, pagevec_count(pvec));
812 pagevec_reinit(pvec);
813}
814EXPORT_SYMBOL(__pagevec_release);
815
816#ifdef CONFIG_TRANSPARENT_HUGEPAGE
817/* used by __split_huge_page_refcount() */
818void lru_add_page_tail(struct page *page, struct page *page_tail,
819 struct lruvec *lruvec, struct list_head *list)
820{
821 const int file = 0;
822
823 VM_BUG_ON_PAGE(!PageHead(page), page);
824 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
825 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
826 VM_BUG_ON(NR_CPUS != 1 &&
827 !spin_is_locked(&lruvec_pgdat(lruvec)->lru_lock));
828
829 if (!list)
830 SetPageLRU(page_tail);
831
832 if (likely(PageLRU(page)))
833 list_add_tail(&page_tail->lru, &page->lru);
834 else if (list) {
835 /* page reclaim is reclaiming a huge page */
836 get_page(page_tail);
837 list_add_tail(&page_tail->lru, list);
838 } else {
839 struct list_head *list_head;
840 /*
841 * Head page has not yet been counted, as an hpage,
842 * so we must account for each subpage individually.
843 *
844 * Use the standard add function to put page_tail on the list,
845 * but then correct its position so they all end up in order.
846 */
847 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
848 list_head = page_tail->lru.prev;
849 list_move_tail(&page_tail->lru, list_head);
850 }
851
852 if (!PageUnevictable(page))
853 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
854}
855#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
856
857static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
858 void *arg)
859{
860 enum lru_list lru;
861 int was_unevictable = TestClearPageUnevictable(page);
862
863 VM_BUG_ON_PAGE(PageLRU(page), page);
864
865 SetPageLRU(page);
866 /*
867 * Page becomes evictable in two ways:
868 * 1) Within LRU lock [munlock_vma_pages() and __munlock_pagevec()].
869 * 2) Before acquiring LRU lock to put the page to correct LRU and then
870 * a) do PageLRU check with lock [check_move_unevictable_pages]
871 * b) do PageLRU check before lock [clear_page_mlock]
872 *
873 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
874 * following strict ordering:
875 *
876 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
877 *
878 * SetPageLRU() TestClearPageMlocked()
879 * smp_mb() // explicit ordering // above provides strict
880 * // ordering
881 * PageMlocked() PageLRU()
882 *
883 *
884 * if '#1' does not observe setting of PG_lru by '#0' and fails
885 * isolation, the explicit barrier will make sure that page_evictable
886 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
887 * can be reordered after PageMlocked check and can make '#1' to fail
888 * the isolation of the page whose Mlocked bit is cleared (#0 is also
889 * looking at the same page) and the evictable page will be stranded
890 * in an unevictable LRU.
891 */
892 smp_mb();
893
894 if (page_evictable(page)) {
895 lru = page_lru(page);
896 update_page_reclaim_stat(lruvec, page_is_file_cache(page),
897 PageActive(page));
898 if (was_unevictable)
899 count_vm_event(UNEVICTABLE_PGRESCUED);
900 } else {
901 lru = LRU_UNEVICTABLE;
902 ClearPageActive(page);
903 SetPageUnevictable(page);
904 if (!was_unevictable)
905 count_vm_event(UNEVICTABLE_PGCULLED);
906 }
907
908 add_page_to_lru_list(page, lruvec, lru);
909 trace_mm_lru_insertion(page, lru);
910}
911
912/*
913 * Add the passed pages to the LRU, then drop the caller's refcount
914 * on them. Reinitialises the caller's pagevec.
915 */
916void __pagevec_lru_add(struct pagevec *pvec)
917{
918 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
919}
920EXPORT_SYMBOL(__pagevec_lru_add);
921
922/**
923 * pagevec_lookup_entries - gang pagecache lookup
924 * @pvec: Where the resulting entries are placed
925 * @mapping: The address_space to search
926 * @start: The starting entry index
927 * @nr_entries: The maximum number of pages
928 * @indices: The cache indices corresponding to the entries in @pvec
929 *
930 * pagevec_lookup_entries() will search for and return a group of up
931 * to @nr_pages pages and shadow entries in the mapping. All
932 * entries are placed in @pvec. pagevec_lookup_entries() takes a
933 * reference against actual pages in @pvec.
934 *
935 * The search returns a group of mapping-contiguous entries with
936 * ascending indexes. There may be holes in the indices due to
937 * not-present entries.
938 *
939 * pagevec_lookup_entries() returns the number of entries which were
940 * found.
941 */
942unsigned pagevec_lookup_entries(struct pagevec *pvec,
943 struct address_space *mapping,
944 pgoff_t start, unsigned nr_entries,
945 pgoff_t *indices)
946{
947 pvec->nr = find_get_entries(mapping, start, nr_entries,
948 pvec->pages, indices);
949 return pagevec_count(pvec);
950}
951
952/**
953 * pagevec_remove_exceptionals - pagevec exceptionals pruning
954 * @pvec: The pagevec to prune
955 *
956 * pagevec_lookup_entries() fills both pages and exceptional radix
957 * tree entries into the pagevec. This function prunes all
958 * exceptionals from @pvec without leaving holes, so that it can be
959 * passed on to page-only pagevec operations.
960 */
961void pagevec_remove_exceptionals(struct pagevec *pvec)
962{
963 int i, j;
964
965 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
966 struct page *page = pvec->pages[i];
967 if (!radix_tree_exceptional_entry(page))
968 pvec->pages[j++] = page;
969 }
970 pvec->nr = j;
971}
972
973/**
974 * pagevec_lookup_range - gang pagecache lookup
975 * @pvec: Where the resulting pages are placed
976 * @mapping: The address_space to search
977 * @start: The starting page index
978 * @end: The final page index
979 *
980 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
981 * pages in the mapping starting from index @start and upto index @end
982 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
983 * reference against the pages in @pvec.
984 *
985 * The search returns a group of mapping-contiguous pages with ascending
986 * indexes. There may be holes in the indices due to not-present pages. We
987 * also update @start to index the next page for the traversal.
988 *
989 * pagevec_lookup_range() returns the number of pages which were found. If this
990 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
991 * reached.
992 */
993unsigned pagevec_lookup_range(struct pagevec *pvec,
994 struct address_space *mapping, pgoff_t *start, pgoff_t end)
995{
996 pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
997 pvec->pages);
998 return pagevec_count(pvec);
999}
1000EXPORT_SYMBOL(pagevec_lookup_range);
1001
1002unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1003 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1004 int tag)
1005{
1006 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1007 PAGEVEC_SIZE, pvec->pages);
1008 return pagevec_count(pvec);
1009}
1010EXPORT_SYMBOL(pagevec_lookup_range_tag);
1011
1012unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
1013 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1014 int tag, unsigned max_pages)
1015{
1016 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1017 min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
1018 return pagevec_count(pvec);
1019}
1020EXPORT_SYMBOL(pagevec_lookup_range_nr_tag);
1021/*
1022 * Perform any setup for the swap system
1023 */
1024void __init swap_setup(void)
1025{
1026 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
1027
1028 /* Use a smaller cluster for small-memory machines */
1029 if (megs < 16)
1030 page_cluster = 2;
1031 else
1032 page_cluster = 3;
1033 /*
1034 * Right now other parts of the system means that we
1035 * _really_ don't want to cluster much more
1036 */
1037}