1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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.
13 * Swap aging added 23.2.95, Stephen Tweedie.
14 * Buffermem limits added 12.3.98, Rik van Riel.
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>
42 #define CREATE_TRACE_POINTS
43 #include <trace/events/pagemap.h>
45 /* How many pages do we try to swap or page in/out together? */
48 /* Protecting only lru_rotate.pvec which requires disabling interrupts */
53 static DEFINE_PER_CPU(struct lru_rotate
, lru_rotate
) = {
54 .lock
= INIT_LOCAL_LOCK(lock
),
58 * The following struct pagevec are grouped together because they are protected
59 * by disabling preemption (and interrupts remain enabled).
63 struct pagevec lru_add
;
64 struct pagevec lru_deactivate_file
;
65 struct pagevec lru_deactivate
;
66 struct pagevec lru_lazyfree
;
68 struct pagevec activate_page
;
71 static DEFINE_PER_CPU(struct lru_pvecs
, lru_pvecs
) = {
72 .lock
= INIT_LOCAL_LOCK(lock
),
76 * This path almost never happens for VM activity - pages are normally
77 * freed via pagevecs. But it gets used by networking.
79 static void __page_cache_release(struct page
*page
)
82 pg_data_t
*pgdat
= page_pgdat(page
);
83 struct lruvec
*lruvec
;
86 spin_lock_irqsave(&pgdat
->lru_lock
, flags
);
87 lruvec
= mem_cgroup_page_lruvec(page
, pgdat
);
88 VM_BUG_ON_PAGE(!PageLRU(page
), page
);
90 del_page_from_lru_list(page
, lruvec
, page_off_lru(page
));
91 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
93 __ClearPageWaiters(page
);
96 static void __put_single_page(struct page
*page
)
98 __page_cache_release(page
);
99 mem_cgroup_uncharge(page
);
100 free_unref_page(page
);
103 static void __put_compound_page(struct page
*page
)
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.)
112 __page_cache_release(page
);
113 destroy_compound_page(page
);
116 void __put_page(struct page
*page
)
118 if (is_zone_device_page(page
)) {
119 put_dev_pagemap(page
->pgmap
);
122 * The page belongs to the device that created pgmap. Do
123 * not return it to page allocator.
128 if (unlikely(PageCompound(page
)))
129 __put_compound_page(page
);
131 __put_single_page(page
);
133 EXPORT_SYMBOL(__put_page
);
136 * put_pages_list() - release a list of pages
137 * @pages: list of pages threaded on page->lru
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.
142 void put_pages_list(struct list_head
*pages
)
144 while (!list_empty(pages
)) {
147 victim
= lru_to_page(pages
);
148 list_del(&victim
->lru
);
152 EXPORT_SYMBOL(put_pages_list
);
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.
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.
167 int get_kernel_pages(const struct kvec
*kiov
, int nr_segs
, int write
,
172 for (seg
= 0; seg
< nr_segs
; seg
++) {
173 if (WARN_ON(kiov
[seg
].iov_len
!= PAGE_SIZE
))
176 pages
[seg
] = kmap_to_page(kiov
[seg
].iov_base
);
177 get_page(pages
[seg
]);
182 EXPORT_SYMBOL_GPL(get_kernel_pages
);
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.
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.
195 int get_kernel_page(unsigned long start
, int write
, struct page
**pages
)
197 const struct kvec kiov
= {
198 .iov_base
= (void *)start
,
202 return get_kernel_pages(&kiov
, 1, write
, pages
);
204 EXPORT_SYMBOL_GPL(get_kernel_page
);
206 static void pagevec_lru_move_fn(struct pagevec
*pvec
,
207 void (*move_fn
)(struct page
*page
, struct lruvec
*lruvec
, void *arg
),
211 struct pglist_data
*pgdat
= NULL
;
212 struct lruvec
*lruvec
;
213 unsigned long flags
= 0;
215 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
216 struct page
*page
= pvec
->pages
[i
];
217 struct pglist_data
*pagepgdat
= page_pgdat(page
);
219 if (pagepgdat
!= pgdat
) {
221 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
223 spin_lock_irqsave(&pgdat
->lru_lock
, flags
);
226 lruvec
= mem_cgroup_page_lruvec(page
, pgdat
);
227 (*move_fn
)(page
, lruvec
, arg
);
230 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
231 release_pages(pvec
->pages
, pvec
->nr
);
232 pagevec_reinit(pvec
);
235 static void pagevec_move_tail_fn(struct page
*page
, struct lruvec
*lruvec
,
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
) += hpage_nr_pages(page
);
249 * pagevec_move_tail() must be called with IRQ disabled.
250 * Otherwise this may cause nasty races.
252 static void pagevec_move_tail(struct pagevec
*pvec
)
256 pagevec_lru_move_fn(pvec
, pagevec_move_tail_fn
, &pgmoved
);
257 __count_vm_events(PGROTATED
, pgmoved
);
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
265 void rotate_reclaimable_page(struct page
*page
)
267 if (!PageLocked(page
) && !PageDirty(page
) &&
268 !PageUnevictable(page
) && PageLRU(page
)) {
269 struct pagevec
*pvec
;
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
);
281 void lru_note_cost(struct lruvec
*lruvec
, bool file
, unsigned int nr_pages
)
284 unsigned long lrusize
;
286 /* Record cost event */
288 lruvec
->file_cost
+= nr_pages
;
290 lruvec
->anon_cost
+= nr_pages
;
293 * Decay previous events
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.
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
);
305 if (lruvec
->file_cost
+ lruvec
->anon_cost
> lrusize
/ 4) {
306 lruvec
->file_cost
/= 2;
307 lruvec
->anon_cost
/= 2;
309 } while ((lruvec
= parent_lruvec(lruvec
)));
312 void lru_note_cost_page(struct page
*page
)
314 lru_note_cost(mem_cgroup_page_lruvec(page
, page_pgdat(page
)),
315 page_is_file_lru(page
), hpage_nr_pages(page
));
318 static void __activate_page(struct page
*page
, struct lruvec
*lruvec
,
321 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
322 int lru
= page_lru_base_type(page
);
323 int nr_pages
= hpage_nr_pages(page
);
325 del_page_from_lru_list(page
, lruvec
, lru
);
328 add_page_to_lru_list(page
, lruvec
, lru
);
329 trace_mm_lru_activate(page
);
331 __count_vm_events(PGACTIVATE
, nr_pages
);
332 __count_memcg_events(lruvec_memcg(lruvec
), PGACTIVATE
,
338 static void activate_page_drain(int cpu
)
340 struct pagevec
*pvec
= &per_cpu(lru_pvecs
.activate_page
, cpu
);
342 if (pagevec_count(pvec
))
343 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
346 static bool need_activate_page_drain(int cpu
)
348 return pagevec_count(&per_cpu(lru_pvecs
.activate_page
, cpu
)) != 0;
351 void activate_page(struct page
*page
)
353 page
= compound_head(page
);
354 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
355 struct pagevec
*pvec
;
357 local_lock(&lru_pvecs
.lock
);
358 pvec
= this_cpu_ptr(&lru_pvecs
.activate_page
);
360 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
361 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
362 local_unlock(&lru_pvecs
.lock
);
367 static inline void activate_page_drain(int cpu
)
371 void activate_page(struct page
*page
)
373 pg_data_t
*pgdat
= page_pgdat(page
);
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
);
382 static void __lru_cache_activate_page(struct page
*page
)
384 struct pagevec
*pvec
;
387 local_lock(&lru_pvecs
.lock
);
388 pvec
= this_cpu_ptr(&lru_pvecs
.lru_add
);
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.
400 for (i
= pagevec_count(pvec
) - 1; i
>= 0; i
--) {
401 struct page
*pagevec_page
= pvec
->pages
[i
];
403 if (pagevec_page
== page
) {
409 local_unlock(&lru_pvecs
.lock
);
413 * Mark a page as having seen activity.
415 * inactive,unreferenced -> inactive,referenced
416 * inactive,referenced -> active,unreferenced
417 * active,unreferenced -> active,referenced
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).
422 void mark_page_accessed(struct page
*page
)
424 page
= compound_head(page
);
426 if (!PageReferenced(page
)) {
427 SetPageReferenced(page
);
428 } else if (PageUnevictable(page
)) {
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.
434 } else if (!PageActive(page
)) {
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.
444 __lru_cache_activate_page(page
);
445 ClearPageReferenced(page
);
446 if (page_is_file_lru(page
))
447 workingset_activation(page
);
449 if (page_is_idle(page
))
450 clear_page_idle(page
);
452 EXPORT_SYMBOL(mark_page_accessed
);
455 * lru_cache_add - add a page to a page list
456 * @page: the page to be added to the LRU.
458 * Queue the page for addition to the LRU via pagevec. The decision on whether
459 * to add the page to the [in]active [file|anon] list is deferred until the
460 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
461 * have the page added to the active list using mark_page_accessed().
463 void lru_cache_add(struct page
*page
)
465 struct pagevec
*pvec
;
467 VM_BUG_ON_PAGE(PageActive(page
) && PageUnevictable(page
), page
);
468 VM_BUG_ON_PAGE(PageLRU(page
), page
);
471 local_lock(&lru_pvecs
.lock
);
472 pvec
= this_cpu_ptr(&lru_pvecs
.lru_add
);
473 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
474 __pagevec_lru_add(pvec
);
475 local_unlock(&lru_pvecs
.lock
);
477 EXPORT_SYMBOL(lru_cache_add
);
480 * lru_cache_add_active_or_unevictable
481 * @page: the page to be added to LRU
482 * @vma: vma in which page is mapped for determining reclaimability
484 * Place @page on the active or unevictable LRU list, depending on its
485 * evictability. Note that if the page is not evictable, it goes
486 * directly back onto it's zone's unevictable list, it does NOT use a
489 void lru_cache_add_active_or_unevictable(struct page
*page
,
490 struct vm_area_struct
*vma
)
492 VM_BUG_ON_PAGE(PageLRU(page
), page
);
494 if (likely((vma
->vm_flags
& (VM_LOCKED
| VM_SPECIAL
)) != VM_LOCKED
))
496 else if (!TestSetPageMlocked(page
)) {
498 * We use the irq-unsafe __mod_zone_page_stat because this
499 * counter is not modified from interrupt context, and the pte
500 * lock is held(spinlock), which implies preemption disabled.
502 __mod_zone_page_state(page_zone(page
), NR_MLOCK
,
503 hpage_nr_pages(page
));
504 count_vm_event(UNEVICTABLE_PGMLOCKED
);
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.
516 * If the page isn't page_mapped and dirty/writeback, the page
517 * could reclaim asap using PG_reclaim.
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
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.
530 static void lru_deactivate_file_fn(struct page
*page
, struct lruvec
*lruvec
,
535 int nr_pages
= hpage_nr_pages(page
);
540 if (PageUnevictable(page
))
543 /* Some processes are using the page */
544 if (page_mapped(page
))
547 active
= PageActive(page
);
548 lru
= page_lru_base_type(page
);
550 del_page_from_lru_list(page
, lruvec
, lru
+ active
);
551 ClearPageActive(page
);
552 ClearPageReferenced(page
);
554 if (PageWriteback(page
) || PageDirty(page
)) {
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.
560 add_page_to_lru_list(page
, lruvec
, lru
);
561 SetPageReclaim(page
);
564 * The page's writeback ends up during pagevec
565 * We moves tha page into tail of inactive.
567 add_page_to_lru_list_tail(page
, lruvec
, lru
);
568 __count_vm_events(PGROTATED
, nr_pages
);
572 __count_vm_events(PGDEACTIVATE
, nr_pages
);
573 __count_memcg_events(lruvec_memcg(lruvec
), PGDEACTIVATE
,
578 static void lru_deactivate_fn(struct page
*page
, struct lruvec
*lruvec
,
581 if (PageLRU(page
) && PageActive(page
) && !PageUnevictable(page
)) {
582 int lru
= page_lru_base_type(page
);
583 int nr_pages
= hpage_nr_pages(page
);
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
);
590 __count_vm_events(PGDEACTIVATE
, nr_pages
);
591 __count_memcg_events(lruvec_memcg(lruvec
), PGDEACTIVATE
,
596 static void lru_lazyfree_fn(struct page
*page
, struct lruvec
*lruvec
,
599 if (PageLRU(page
) && PageAnon(page
) && PageSwapBacked(page
) &&
600 !PageSwapCache(page
) && !PageUnevictable(page
)) {
601 bool active
= PageActive(page
);
602 int nr_pages
= hpage_nr_pages(page
);
604 del_page_from_lru_list(page
, lruvec
,
605 LRU_INACTIVE_ANON
+ active
);
606 ClearPageActive(page
);
607 ClearPageReferenced(page
);
609 * Lazyfree pages are clean anonymous pages. They have
610 * PG_swapbacked flag cleared, to distinguish them from normal
613 ClearPageSwapBacked(page
);
614 add_page_to_lru_list(page
, lruvec
, LRU_INACTIVE_FILE
);
616 __count_vm_events(PGLAZYFREE
, nr_pages
);
617 __count_memcg_events(lruvec_memcg(lruvec
), PGLAZYFREE
,
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.
627 void lru_add_drain_cpu(int cpu
)
629 struct pagevec
*pvec
= &per_cpu(lru_pvecs
.lru_add
, cpu
);
631 if (pagevec_count(pvec
))
632 __pagevec_lru_add(pvec
);
634 pvec
= &per_cpu(lru_rotate
.pvec
, cpu
);
635 if (pagevec_count(pvec
)) {
638 /* No harm done if a racing interrupt already did this */
639 local_lock_irqsave(&lru_rotate
.lock
, flags
);
640 pagevec_move_tail(pvec
);
641 local_unlock_irqrestore(&lru_rotate
.lock
, flags
);
644 pvec
= &per_cpu(lru_pvecs
.lru_deactivate_file
, cpu
);
645 if (pagevec_count(pvec
))
646 pagevec_lru_move_fn(pvec
, lru_deactivate_file_fn
, NULL
);
648 pvec
= &per_cpu(lru_pvecs
.lru_deactivate
, cpu
);
649 if (pagevec_count(pvec
))
650 pagevec_lru_move_fn(pvec
, lru_deactivate_fn
, NULL
);
652 pvec
= &per_cpu(lru_pvecs
.lru_lazyfree
, cpu
);
653 if (pagevec_count(pvec
))
654 pagevec_lru_move_fn(pvec
, lru_lazyfree_fn
, NULL
);
656 activate_page_drain(cpu
);
660 * deactivate_file_page - forcefully deactivate a file page
661 * @page: page to deactivate
663 * This function hints the VM that @page is a good reclaim candidate,
664 * for example if its invalidation fails due to the page being dirty
665 * or under writeback.
667 void deactivate_file_page(struct page
*page
)
670 * In a workload with many unevictable page such as mprotect,
671 * unevictable page deactivation for accelerating reclaim is pointless.
673 if (PageUnevictable(page
))
676 if (likely(get_page_unless_zero(page
))) {
677 struct pagevec
*pvec
;
679 local_lock(&lru_pvecs
.lock
);
680 pvec
= this_cpu_ptr(&lru_pvecs
.lru_deactivate_file
);
682 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
683 pagevec_lru_move_fn(pvec
, lru_deactivate_file_fn
, NULL
);
684 local_unlock(&lru_pvecs
.lock
);
689 * deactivate_page - deactivate a page
690 * @page: page to deactivate
692 * deactivate_page() moves @page to the inactive list if @page was on the active
693 * list and was not an unevictable page. This is done to accelerate the reclaim
696 void deactivate_page(struct page
*page
)
698 if (PageLRU(page
) && PageActive(page
) && !PageUnevictable(page
)) {
699 struct pagevec
*pvec
;
701 local_lock(&lru_pvecs
.lock
);
702 pvec
= this_cpu_ptr(&lru_pvecs
.lru_deactivate
);
704 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
705 pagevec_lru_move_fn(pvec
, lru_deactivate_fn
, NULL
);
706 local_unlock(&lru_pvecs
.lock
);
711 * mark_page_lazyfree - make an anon page lazyfree
712 * @page: page to deactivate
714 * mark_page_lazyfree() moves @page to the inactive file list.
715 * This is done to accelerate the reclaim of @page.
717 void mark_page_lazyfree(struct page
*page
)
719 if (PageLRU(page
) && PageAnon(page
) && PageSwapBacked(page
) &&
720 !PageSwapCache(page
) && !PageUnevictable(page
)) {
721 struct pagevec
*pvec
;
723 local_lock(&lru_pvecs
.lock
);
724 pvec
= this_cpu_ptr(&lru_pvecs
.lru_lazyfree
);
726 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
727 pagevec_lru_move_fn(pvec
, lru_lazyfree_fn
, NULL
);
728 local_unlock(&lru_pvecs
.lock
);
732 void lru_add_drain(void)
734 local_lock(&lru_pvecs
.lock
);
735 lru_add_drain_cpu(smp_processor_id());
736 local_unlock(&lru_pvecs
.lock
);
739 void lru_add_drain_cpu_zone(struct zone
*zone
)
741 local_lock(&lru_pvecs
.lock
);
742 lru_add_drain_cpu(smp_processor_id());
743 drain_local_pages(zone
);
744 local_unlock(&lru_pvecs
.lock
);
749 static DEFINE_PER_CPU(struct work_struct
, lru_add_drain_work
);
751 static void lru_add_drain_per_cpu(struct work_struct
*dummy
)
757 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
758 * kworkers being shut down before our page_alloc_cpu_dead callback is
759 * executed on the offlined cpu.
760 * Calling this function with cpu hotplug locks held can actually lead
761 * to obscure indirect dependencies via WQ context.
763 void lru_add_drain_all(void)
765 static seqcount_t seqcount
= SEQCNT_ZERO(seqcount
);
766 static DEFINE_MUTEX(lock
);
767 static struct cpumask has_work
;
771 * Make sure nobody triggers this path before mm_percpu_wq is fully
774 if (WARN_ON(!mm_percpu_wq
))
777 seq
= raw_read_seqcount_latch(&seqcount
);
782 * Piggyback on drain started and finished while we waited for lock:
783 * all pages pended at the time of our enter were drained from vectors.
785 if (__read_seqcount_retry(&seqcount
, seq
))
788 raw_write_seqcount_latch(&seqcount
);
790 cpumask_clear(&has_work
);
792 for_each_online_cpu(cpu
) {
793 struct work_struct
*work
= &per_cpu(lru_add_drain_work
, cpu
);
795 if (pagevec_count(&per_cpu(lru_pvecs
.lru_add
, cpu
)) ||
796 pagevec_count(&per_cpu(lru_rotate
.pvec
, cpu
)) ||
797 pagevec_count(&per_cpu(lru_pvecs
.lru_deactivate_file
, cpu
)) ||
798 pagevec_count(&per_cpu(lru_pvecs
.lru_deactivate
, cpu
)) ||
799 pagevec_count(&per_cpu(lru_pvecs
.lru_lazyfree
, cpu
)) ||
800 need_activate_page_drain(cpu
)) {
801 INIT_WORK(work
, lru_add_drain_per_cpu
);
802 queue_work_on(cpu
, mm_percpu_wq
, work
);
803 cpumask_set_cpu(cpu
, &has_work
);
807 for_each_cpu(cpu
, &has_work
)
808 flush_work(&per_cpu(lru_add_drain_work
, cpu
));
814 void lru_add_drain_all(void)
821 * release_pages - batched put_page()
822 * @pages: array of pages to release
823 * @nr: number of pages
825 * Decrement the reference count on all the pages in @pages. If it
826 * fell to zero, remove the page from the LRU and free it.
828 void release_pages(struct page
**pages
, int nr
)
831 LIST_HEAD(pages_to_free
);
832 struct pglist_data
*locked_pgdat
= NULL
;
833 struct lruvec
*lruvec
;
834 unsigned long uninitialized_var(flags
);
835 unsigned int uninitialized_var(lock_batch
);
837 for (i
= 0; i
< nr
; i
++) {
838 struct page
*page
= pages
[i
];
841 * Make sure the IRQ-safe lock-holding time does not get
842 * excessive with a continuous string of pages from the
843 * same pgdat. The lock is held only if pgdat != NULL.
845 if (locked_pgdat
&& ++lock_batch
== SWAP_CLUSTER_MAX
) {
846 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
850 if (is_huge_zero_page(page
))
853 if (is_zone_device_page(page
)) {
855 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
,
860 * ZONE_DEVICE pages that return 'false' from
861 * put_devmap_managed_page() do not require special
862 * processing, and instead, expect a call to
863 * put_page_testzero().
865 if (page_is_devmap_managed(page
)) {
866 put_devmap_managed_page(page
);
871 page
= compound_head(page
);
872 if (!put_page_testzero(page
))
875 if (PageCompound(page
)) {
877 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
880 __put_compound_page(page
);
885 struct pglist_data
*pgdat
= page_pgdat(page
);
887 if (pgdat
!= locked_pgdat
) {
889 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
,
892 locked_pgdat
= pgdat
;
893 spin_lock_irqsave(&locked_pgdat
->lru_lock
, flags
);
896 lruvec
= mem_cgroup_page_lruvec(page
, locked_pgdat
);
897 VM_BUG_ON_PAGE(!PageLRU(page
), page
);
898 __ClearPageLRU(page
);
899 del_page_from_lru_list(page
, lruvec
, page_off_lru(page
));
902 /* Clear Active bit in case of parallel mark_page_accessed */
903 __ClearPageActive(page
);
904 __ClearPageWaiters(page
);
906 list_add(&page
->lru
, &pages_to_free
);
909 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
911 mem_cgroup_uncharge_list(&pages_to_free
);
912 free_unref_page_list(&pages_to_free
);
914 EXPORT_SYMBOL(release_pages
);
917 * The pages which we're about to release may be in the deferred lru-addition
918 * queues. That would prevent them from really being freed right now. That's
919 * OK from a correctness point of view but is inefficient - those pages may be
920 * cache-warm and we want to give them back to the page allocator ASAP.
922 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
923 * and __pagevec_lru_add_active() call release_pages() directly to avoid
926 void __pagevec_release(struct pagevec
*pvec
)
928 if (!pvec
->percpu_pvec_drained
) {
930 pvec
->percpu_pvec_drained
= true;
932 release_pages(pvec
->pages
, pagevec_count(pvec
));
933 pagevec_reinit(pvec
);
935 EXPORT_SYMBOL(__pagevec_release
);
937 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
938 /* used by __split_huge_page_refcount() */
939 void lru_add_page_tail(struct page
*page
, struct page
*page_tail
,
940 struct lruvec
*lruvec
, struct list_head
*list
)
942 VM_BUG_ON_PAGE(!PageHead(page
), page
);
943 VM_BUG_ON_PAGE(PageCompound(page_tail
), page
);
944 VM_BUG_ON_PAGE(PageLRU(page_tail
), page
);
945 lockdep_assert_held(&lruvec_pgdat(lruvec
)->lru_lock
);
948 SetPageLRU(page_tail
);
950 if (likely(PageLRU(page
)))
951 list_add_tail(&page_tail
->lru
, &page
->lru
);
953 /* page reclaim is reclaiming a huge page */
955 list_add_tail(&page_tail
->lru
, list
);
958 * Head page has not yet been counted, as an hpage,
959 * so we must account for each subpage individually.
961 * Put page_tail on the list at the correct position
962 * so they all end up in order.
964 add_page_to_lru_list_tail(page_tail
, lruvec
,
965 page_lru(page_tail
));
968 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
970 static void __pagevec_lru_add_fn(struct page
*page
, struct lruvec
*lruvec
,
974 int was_unevictable
= TestClearPageUnevictable(page
);
975 int nr_pages
= hpage_nr_pages(page
);
977 VM_BUG_ON_PAGE(PageLRU(page
), page
);
980 * Page becomes evictable in two ways:
981 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
982 * 2) Before acquiring LRU lock to put the page to correct LRU and then
983 * a) do PageLRU check with lock [check_move_unevictable_pages]
984 * b) do PageLRU check before lock [clear_page_mlock]
986 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
987 * following strict ordering:
989 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
991 * SetPageLRU() TestClearPageMlocked()
992 * smp_mb() // explicit ordering // above provides strict
994 * PageMlocked() PageLRU()
997 * if '#1' does not observe setting of PG_lru by '#0' and fails
998 * isolation, the explicit barrier will make sure that page_evictable
999 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
1000 * can be reordered after PageMlocked check and can make '#1' to fail
1001 * the isolation of the page whose Mlocked bit is cleared (#0 is also
1002 * looking at the same page) and the evictable page will be stranded
1003 * in an unevictable LRU.
1006 smp_mb__after_atomic();
1008 if (page_evictable(page
)) {
1009 lru
= page_lru(page
);
1010 if (was_unevictable
)
1011 __count_vm_events(UNEVICTABLE_PGRESCUED
, nr_pages
);
1013 lru
= LRU_UNEVICTABLE
;
1014 ClearPageActive(page
);
1015 SetPageUnevictable(page
);
1016 if (!was_unevictable
)
1017 __count_vm_events(UNEVICTABLE_PGCULLED
, nr_pages
);
1020 add_page_to_lru_list(page
, lruvec
, lru
);
1021 trace_mm_lru_insertion(page
, lru
);
1025 * Add the passed pages to the LRU, then drop the caller's refcount
1026 * on them. Reinitialises the caller's pagevec.
1028 void __pagevec_lru_add(struct pagevec
*pvec
)
1030 pagevec_lru_move_fn(pvec
, __pagevec_lru_add_fn
, NULL
);
1034 * pagevec_lookup_entries - gang pagecache lookup
1035 * @pvec: Where the resulting entries are placed
1036 * @mapping: The address_space to search
1037 * @start: The starting entry index
1038 * @nr_entries: The maximum number of pages
1039 * @indices: The cache indices corresponding to the entries in @pvec
1041 * pagevec_lookup_entries() will search for and return a group of up
1042 * to @nr_pages pages and shadow entries in the mapping. All
1043 * entries are placed in @pvec. pagevec_lookup_entries() takes a
1044 * reference against actual pages in @pvec.
1046 * The search returns a group of mapping-contiguous entries with
1047 * ascending indexes. There may be holes in the indices due to
1048 * not-present entries.
1050 * Only one subpage of a Transparent Huge Page is returned in one call:
1051 * allowing truncate_inode_pages_range() to evict the whole THP without
1052 * cycling through a pagevec of extra references.
1054 * pagevec_lookup_entries() returns the number of entries which were
1057 unsigned pagevec_lookup_entries(struct pagevec
*pvec
,
1058 struct address_space
*mapping
,
1059 pgoff_t start
, unsigned nr_entries
,
1062 pvec
->nr
= find_get_entries(mapping
, start
, nr_entries
,
1063 pvec
->pages
, indices
);
1064 return pagevec_count(pvec
);
1068 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1069 * @pvec: The pagevec to prune
1071 * pagevec_lookup_entries() fills both pages and exceptional radix
1072 * tree entries into the pagevec. This function prunes all
1073 * exceptionals from @pvec without leaving holes, so that it can be
1074 * passed on to page-only pagevec operations.
1076 void pagevec_remove_exceptionals(struct pagevec
*pvec
)
1080 for (i
= 0, j
= 0; i
< pagevec_count(pvec
); i
++) {
1081 struct page
*page
= pvec
->pages
[i
];
1082 if (!xa_is_value(page
))
1083 pvec
->pages
[j
++] = page
;
1089 * pagevec_lookup_range - gang pagecache lookup
1090 * @pvec: Where the resulting pages are placed
1091 * @mapping: The address_space to search
1092 * @start: The starting page index
1093 * @end: The final page index
1095 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1096 * pages in the mapping starting from index @start and upto index @end
1097 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
1098 * reference against the pages in @pvec.
1100 * The search returns a group of mapping-contiguous pages with ascending
1101 * indexes. There may be holes in the indices due to not-present pages. We
1102 * also update @start to index the next page for the traversal.
1104 * pagevec_lookup_range() returns the number of pages which were found. If this
1105 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1108 unsigned pagevec_lookup_range(struct pagevec
*pvec
,
1109 struct address_space
*mapping
, pgoff_t
*start
, pgoff_t end
)
1111 pvec
->nr
= find_get_pages_range(mapping
, start
, end
, PAGEVEC_SIZE
,
1113 return pagevec_count(pvec
);
1115 EXPORT_SYMBOL(pagevec_lookup_range
);
1117 unsigned pagevec_lookup_range_tag(struct pagevec
*pvec
,
1118 struct address_space
*mapping
, pgoff_t
*index
, pgoff_t end
,
1121 pvec
->nr
= find_get_pages_range_tag(mapping
, index
, end
, tag
,
1122 PAGEVEC_SIZE
, pvec
->pages
);
1123 return pagevec_count(pvec
);
1125 EXPORT_SYMBOL(pagevec_lookup_range_tag
);
1127 unsigned pagevec_lookup_range_nr_tag(struct pagevec
*pvec
,
1128 struct address_space
*mapping
, pgoff_t
*index
, pgoff_t end
,
1129 xa_mark_t tag
, unsigned max_pages
)
1131 pvec
->nr
= find_get_pages_range_tag(mapping
, index
, end
, tag
,
1132 min_t(unsigned int, max_pages
, PAGEVEC_SIZE
), pvec
->pages
);
1133 return pagevec_count(pvec
);
1135 EXPORT_SYMBOL(pagevec_lookup_range_nr_tag
);
1137 * Perform any setup for the swap system
1139 void __init
swap_setup(void)
1141 unsigned long megs
= totalram_pages() >> (20 - PAGE_SHIFT
);
1143 /* Use a smaller cluster for small-memory machines */
1149 * Right now other parts of the system means that we
1150 * _really_ don't want to cluster much more
1154 #ifdef CONFIG_DEV_PAGEMAP_OPS
1155 void put_devmap_managed_page(struct page
*page
)
1159 if (WARN_ON_ONCE(!page_is_devmap_managed(page
)))
1162 count
= page_ref_dec_return(page
);
1165 * devmap page refcounts are 1-based, rather than 0-based: if
1166 * refcount is 1, then the page is free and the refcount is
1167 * stable because nobody holds a reference on the page.
1170 free_devmap_managed_page(page
);
1174 EXPORT_SYMBOL(put_devmap_managed_page
);