4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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.
12 * Swap aging added 23.2.95, Stephen Tweedie.
13 * Buffermem limits added 12.3.98, Rik van Riel.
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>
40 #define CREATE_TRACE_POINTS
41 #include <trace/events/pagemap.h>
43 /* How many pages do we try to swap or page in/out together? */
46 static DEFINE_PER_CPU(struct pagevec
, lru_add_pvec
);
47 static DEFINE_PER_CPU(struct pagevec
, lru_rotate_pvecs
);
48 static DEFINE_PER_CPU(struct pagevec
, lru_deactivate_file_pvecs
);
49 static DEFINE_PER_CPU(struct pagevec
, lru_lazyfree_pvecs
);
51 static DEFINE_PER_CPU(struct pagevec
, activate_page_pvecs
);
55 * This path almost never happens for VM activity - pages are normally
56 * freed via pagevecs. But it gets used by networking.
58 static void __page_cache_release(struct page
*page
)
61 pg_data_t
*pgdat
= page_pgdat(page
);
62 struct lruvec
*lruvec
;
65 spin_lock_irqsave(&pgdat
->lru_lock
, flags
);
66 lruvec
= mem_cgroup_page_lruvec(page
, pgdat
);
67 VM_BUG_ON_PAGE(!PageLRU(page
), page
);
69 del_page_from_lru_list(page
, lruvec
, page_off_lru(page
));
70 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
72 __ClearPageWaiters(page
);
73 mem_cgroup_uncharge(page
);
76 static void __put_single_page(struct page
*page
)
78 __page_cache_release(page
);
79 free_unref_page(page
);
82 static void __put_compound_page(struct page
*page
)
84 compound_page_dtor
*dtor
;
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.)
93 __page_cache_release(page
);
94 dtor
= get_compound_page_dtor(page
);
98 void __put_page(struct page
*page
)
100 if (is_zone_device_page(page
)) {
101 put_dev_pagemap(page
->pgmap
);
104 * The page belongs to the device that created pgmap. Do
105 * not return it to page allocator.
110 if (unlikely(PageCompound(page
)))
111 __put_compound_page(page
);
113 __put_single_page(page
);
115 EXPORT_SYMBOL(__put_page
);
118 * put_pages_list() - release a list of pages
119 * @pages: list of pages threaded on page->lru
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.
124 void put_pages_list(struct list_head
*pages
)
126 while (!list_empty(pages
)) {
129 victim
= lru_to_page(pages
);
130 list_del(&victim
->lru
);
134 EXPORT_SYMBOL(put_pages_list
);
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.
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.
149 int get_kernel_pages(const struct kvec
*kiov
, int nr_segs
, int write
,
154 for (seg
= 0; seg
< nr_segs
; seg
++) {
155 if (WARN_ON(kiov
[seg
].iov_len
!= PAGE_SIZE
))
158 pages
[seg
] = kmap_to_page(kiov
[seg
].iov_base
);
159 get_page(pages
[seg
]);
164 EXPORT_SYMBOL_GPL(get_kernel_pages
);
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.
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.
177 int get_kernel_page(unsigned long start
, int write
, struct page
**pages
)
179 const struct kvec kiov
= {
180 .iov_base
= (void *)start
,
184 return get_kernel_pages(&kiov
, 1, write
, pages
);
186 EXPORT_SYMBOL_GPL(get_kernel_page
);
188 static void pagevec_lru_move_fn(struct pagevec
*pvec
,
189 void (*move_fn
)(struct page
*page
, struct lruvec
*lruvec
, void *arg
),
193 struct pglist_data
*pgdat
= NULL
;
194 struct lruvec
*lruvec
;
195 unsigned long flags
= 0;
197 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
198 struct page
*page
= pvec
->pages
[i
];
199 struct pglist_data
*pagepgdat
= page_pgdat(page
);
201 if (pagepgdat
!= pgdat
) {
203 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
205 spin_lock_irqsave(&pgdat
->lru_lock
, flags
);
208 lruvec
= mem_cgroup_page_lruvec(page
, pgdat
);
209 (*move_fn
)(page
, lruvec
, arg
);
212 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
213 release_pages(pvec
->pages
, pvec
->nr
);
214 pagevec_reinit(pvec
);
217 static void pagevec_move_tail_fn(struct page
*page
, struct lruvec
*lruvec
,
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
));
231 * pagevec_move_tail() must be called with IRQ disabled.
232 * Otherwise this may cause nasty races.
234 static void pagevec_move_tail(struct pagevec
*pvec
)
238 pagevec_lru_move_fn(pvec
, pagevec_move_tail_fn
, &pgmoved
);
239 __count_vm_events(PGROTATED
, pgmoved
);
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
247 void rotate_reclaimable_page(struct page
*page
)
249 if (!PageLocked(page
) && !PageDirty(page
) &&
250 !PageUnevictable(page
) && PageLRU(page
)) {
251 struct pagevec
*pvec
;
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
);
263 static void update_page_reclaim_stat(struct lruvec
*lruvec
,
264 int file
, int rotated
)
266 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
268 reclaim_stat
->recent_scanned
[file
]++;
270 reclaim_stat
->recent_rotated
[file
]++;
273 static void __activate_page(struct page
*page
, struct lruvec
*lruvec
,
276 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
277 int file
= page_is_file_cache(page
);
278 int lru
= page_lru_base_type(page
);
280 del_page_from_lru_list(page
, lruvec
, lru
);
283 add_page_to_lru_list(page
, lruvec
, lru
);
284 trace_mm_lru_activate(page
);
286 __count_vm_event(PGACTIVATE
);
287 update_page_reclaim_stat(lruvec
, file
, 1);
292 static void activate_page_drain(int cpu
)
294 struct pagevec
*pvec
= &per_cpu(activate_page_pvecs
, cpu
);
296 if (pagevec_count(pvec
))
297 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
300 static bool need_activate_page_drain(int cpu
)
302 return pagevec_count(&per_cpu(activate_page_pvecs
, cpu
)) != 0;
305 void activate_page(struct page
*page
)
307 page
= compound_head(page
);
308 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
309 struct pagevec
*pvec
= &get_cpu_var(activate_page_pvecs
);
312 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
313 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
314 put_cpu_var(activate_page_pvecs
);
319 static inline void activate_page_drain(int cpu
)
323 void activate_page(struct page
*page
)
325 pg_data_t
*pgdat
= page_pgdat(page
);
327 page
= compound_head(page
);
328 spin_lock_irq(&pgdat
->lru_lock
);
329 __activate_page(page
, mem_cgroup_page_lruvec(page
, pgdat
), NULL
);
330 spin_unlock_irq(&pgdat
->lru_lock
);
334 static void __lru_cache_activate_page(struct page
*page
)
336 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvec
);
340 * Search backwards on the optimistic assumption that the page being
341 * activated has just been added to this pagevec. Note that only
342 * the local pagevec is examined as a !PageLRU page could be in the
343 * process of being released, reclaimed, migrated or on a remote
344 * pagevec that is currently being drained. Furthermore, marking
345 * a remote pagevec's page PageActive potentially hits a race where
346 * a page is marked PageActive just after it is added to the inactive
347 * list causing accounting errors and BUG_ON checks to trigger.
349 for (i
= pagevec_count(pvec
) - 1; i
>= 0; i
--) {
350 struct page
*pagevec_page
= pvec
->pages
[i
];
352 if (pagevec_page
== page
) {
358 put_cpu_var(lru_add_pvec
);
362 * Mark a page as having seen activity.
364 * inactive,unreferenced -> inactive,referenced
365 * inactive,referenced -> active,unreferenced
366 * active,unreferenced -> active,referenced
368 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
369 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
371 void mark_page_accessed(struct page
*page
)
373 page
= compound_head(page
);
374 if (!PageActive(page
) && !PageUnevictable(page
) &&
375 PageReferenced(page
)) {
378 * If the page is on the LRU, queue it for activation via
379 * activate_page_pvecs. Otherwise, assume the page is on a
380 * pagevec, mark it active and it'll be moved to the active
381 * LRU on the next drain.
386 __lru_cache_activate_page(page
);
387 ClearPageReferenced(page
);
388 if (page_is_file_cache(page
))
389 workingset_activation(page
);
390 } else if (!PageReferenced(page
)) {
391 SetPageReferenced(page
);
393 if (page_is_idle(page
))
394 clear_page_idle(page
);
396 EXPORT_SYMBOL(mark_page_accessed
);
398 static void __lru_cache_add(struct page
*page
)
400 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvec
);
403 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
404 __pagevec_lru_add(pvec
);
405 put_cpu_var(lru_add_pvec
);
409 * lru_cache_add_anon - add a page to the page lists
410 * @page: the page to add
412 void lru_cache_add_anon(struct page
*page
)
414 if (PageActive(page
))
415 ClearPageActive(page
);
416 __lru_cache_add(page
);
419 void lru_cache_add_file(struct page
*page
)
421 if (PageActive(page
))
422 ClearPageActive(page
);
423 __lru_cache_add(page
);
425 EXPORT_SYMBOL(lru_cache_add_file
);
428 * lru_cache_add - add a page to a page list
429 * @page: the page to be added to the LRU.
431 * Queue the page for addition to the LRU via pagevec. The decision on whether
432 * to add the page to the [in]active [file|anon] list is deferred until the
433 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
434 * have the page added to the active list using mark_page_accessed().
436 void lru_cache_add(struct page
*page
)
438 VM_BUG_ON_PAGE(PageActive(page
) && PageUnevictable(page
), page
);
439 VM_BUG_ON_PAGE(PageLRU(page
), page
);
440 __lru_cache_add(page
);
444 * lru_cache_add_active_or_unevictable
445 * @page: the page to be added to LRU
446 * @vma: vma in which page is mapped for determining reclaimability
448 * Place @page on the active or unevictable LRU list, depending on its
449 * evictability. Note that if the page is not evictable, it goes
450 * directly back onto it's zone's unevictable list, it does NOT use a
453 void lru_cache_add_active_or_unevictable(struct page
*page
,
454 struct vm_area_struct
*vma
)
456 VM_BUG_ON_PAGE(PageLRU(page
), page
);
458 if (likely((vma
->vm_flags
& (VM_LOCKED
| VM_SPECIAL
)) != VM_LOCKED
))
460 else if (!TestSetPageMlocked(page
)) {
462 * We use the irq-unsafe __mod_zone_page_stat because this
463 * counter is not modified from interrupt context, and the pte
464 * lock is held(spinlock), which implies preemption disabled.
466 __mod_zone_page_state(page_zone(page
), NR_MLOCK
,
467 hpage_nr_pages(page
));
468 count_vm_event(UNEVICTABLE_PGMLOCKED
);
474 * If the page can not be invalidated, it is moved to the
475 * inactive list to speed up its reclaim. It is moved to the
476 * head of the list, rather than the tail, to give the flusher
477 * threads some time to write it out, as this is much more
478 * effective than the single-page writeout from reclaim.
480 * If the page isn't page_mapped and dirty/writeback, the page
481 * could reclaim asap using PG_reclaim.
483 * 1. active, mapped page -> none
484 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
485 * 3. inactive, mapped page -> none
486 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
487 * 5. inactive, clean -> inactive, tail
490 * In 4, why it moves inactive's head, the VM expects the page would
491 * be write it out by flusher threads as this is much more effective
492 * than the single-page writeout from reclaim.
494 static void lru_deactivate_file_fn(struct page
*page
, struct lruvec
*lruvec
,
503 if (PageUnevictable(page
))
506 /* Some processes are using the page */
507 if (page_mapped(page
))
510 active
= PageActive(page
);
511 file
= page_is_file_cache(page
);
512 lru
= page_lru_base_type(page
);
514 del_page_from_lru_list(page
, lruvec
, lru
+ active
);
515 ClearPageActive(page
);
516 ClearPageReferenced(page
);
517 add_page_to_lru_list(page
, lruvec
, lru
);
519 if (PageWriteback(page
) || PageDirty(page
)) {
521 * PG_reclaim could be raced with end_page_writeback
522 * It can make readahead confusing. But race window
523 * is _really_ small and it's non-critical problem.
525 SetPageReclaim(page
);
528 * The page's writeback ends up during pagevec
529 * We moves tha page into tail of inactive.
531 list_move_tail(&page
->lru
, &lruvec
->lists
[lru
]);
532 __count_vm_event(PGROTATED
);
536 __count_vm_event(PGDEACTIVATE
);
537 update_page_reclaim_stat(lruvec
, file
, 0);
541 static void lru_lazyfree_fn(struct page
*page
, struct lruvec
*lruvec
,
544 if (PageLRU(page
) && PageAnon(page
) && PageSwapBacked(page
) &&
545 !PageSwapCache(page
) && !PageUnevictable(page
)) {
546 bool active
= PageActive(page
);
548 del_page_from_lru_list(page
, lruvec
,
549 LRU_INACTIVE_ANON
+ active
);
550 ClearPageActive(page
);
551 ClearPageReferenced(page
);
553 * lazyfree pages are clean anonymous pages. They have
554 * SwapBacked flag cleared to distinguish normal anonymous
557 ClearPageSwapBacked(page
);
558 add_page_to_lru_list(page
, lruvec
, LRU_INACTIVE_FILE
);
560 __count_vm_events(PGLAZYFREE
, hpage_nr_pages(page
));
561 count_memcg_page_event(page
, PGLAZYFREE
);
562 update_page_reclaim_stat(lruvec
, 1, 0);
567 * Drain pages out of the cpu's pagevecs.
568 * Either "cpu" is the current CPU, and preemption has already been
569 * disabled; or "cpu" is being hot-unplugged, and is already dead.
571 void lru_add_drain_cpu(int cpu
)
573 struct pagevec
*pvec
= &per_cpu(lru_add_pvec
, cpu
);
575 if (pagevec_count(pvec
))
576 __pagevec_lru_add(pvec
);
578 pvec
= &per_cpu(lru_rotate_pvecs
, cpu
);
579 if (pagevec_count(pvec
)) {
582 /* No harm done if a racing interrupt already did this */
583 local_irq_save(flags
);
584 pagevec_move_tail(pvec
);
585 local_irq_restore(flags
);
588 pvec
= &per_cpu(lru_deactivate_file_pvecs
, cpu
);
589 if (pagevec_count(pvec
))
590 pagevec_lru_move_fn(pvec
, lru_deactivate_file_fn
, NULL
);
592 pvec
= &per_cpu(lru_lazyfree_pvecs
, cpu
);
593 if (pagevec_count(pvec
))
594 pagevec_lru_move_fn(pvec
, lru_lazyfree_fn
, NULL
);
596 activate_page_drain(cpu
);
600 * deactivate_file_page - forcefully deactivate a file page
601 * @page: page to deactivate
603 * This function hints the VM that @page is a good reclaim candidate,
604 * for example if its invalidation fails due to the page being dirty
605 * or under writeback.
607 void deactivate_file_page(struct page
*page
)
610 * In a workload with many unevictable page such as mprotect,
611 * unevictable page deactivation for accelerating reclaim is pointless.
613 if (PageUnevictable(page
))
616 if (likely(get_page_unless_zero(page
))) {
617 struct pagevec
*pvec
= &get_cpu_var(lru_deactivate_file_pvecs
);
619 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
620 pagevec_lru_move_fn(pvec
, lru_deactivate_file_fn
, NULL
);
621 put_cpu_var(lru_deactivate_file_pvecs
);
626 * mark_page_lazyfree - make an anon page lazyfree
627 * @page: page to deactivate
629 * mark_page_lazyfree() moves @page to the inactive file list.
630 * This is done to accelerate the reclaim of @page.
632 void mark_page_lazyfree(struct page
*page
)
634 if (PageLRU(page
) && PageAnon(page
) && PageSwapBacked(page
) &&
635 !PageSwapCache(page
) && !PageUnevictable(page
)) {
636 struct pagevec
*pvec
= &get_cpu_var(lru_lazyfree_pvecs
);
639 if (!pagevec_add(pvec
, page
) || PageCompound(page
))
640 pagevec_lru_move_fn(pvec
, lru_lazyfree_fn
, NULL
);
641 put_cpu_var(lru_lazyfree_pvecs
);
645 void lru_add_drain(void)
647 lru_add_drain_cpu(get_cpu());
653 static DEFINE_PER_CPU(struct work_struct
, lru_add_drain_work
);
655 static void lru_add_drain_per_cpu(struct work_struct
*dummy
)
661 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
662 * kworkers being shut down before our page_alloc_cpu_dead callback is
663 * executed on the offlined cpu.
664 * Calling this function with cpu hotplug locks held can actually lead
665 * to obscure indirect dependencies via WQ context.
667 void lru_add_drain_all(void)
669 static DEFINE_MUTEX(lock
);
670 static struct cpumask has_work
;
674 * Make sure nobody triggers this path before mm_percpu_wq is fully
677 if (WARN_ON(!mm_percpu_wq
))
681 cpumask_clear(&has_work
);
683 for_each_online_cpu(cpu
) {
684 struct work_struct
*work
= &per_cpu(lru_add_drain_work
, cpu
);
686 if (pagevec_count(&per_cpu(lru_add_pvec
, cpu
)) ||
687 pagevec_count(&per_cpu(lru_rotate_pvecs
, cpu
)) ||
688 pagevec_count(&per_cpu(lru_deactivate_file_pvecs
, cpu
)) ||
689 pagevec_count(&per_cpu(lru_lazyfree_pvecs
, cpu
)) ||
690 need_activate_page_drain(cpu
)) {
691 INIT_WORK(work
, lru_add_drain_per_cpu
);
692 queue_work_on(cpu
, mm_percpu_wq
, work
);
693 cpumask_set_cpu(cpu
, &has_work
);
697 for_each_cpu(cpu
, &has_work
)
698 flush_work(&per_cpu(lru_add_drain_work
, cpu
));
703 void lru_add_drain_all(void)
710 * release_pages - batched put_page()
711 * @pages: array of pages to release
712 * @nr: number of pages
714 * Decrement the reference count on all the pages in @pages. If it
715 * fell to zero, remove the page from the LRU and free it.
717 void release_pages(struct page
**pages
, int nr
)
720 LIST_HEAD(pages_to_free
);
721 struct pglist_data
*locked_pgdat
= NULL
;
722 struct lruvec
*lruvec
;
723 unsigned long uninitialized_var(flags
);
724 unsigned int uninitialized_var(lock_batch
);
726 for (i
= 0; i
< nr
; i
++) {
727 struct page
*page
= pages
[i
];
730 * Make sure the IRQ-safe lock-holding time does not get
731 * excessive with a continuous string of pages from the
732 * same pgdat. The lock is held only if pgdat != NULL.
734 if (locked_pgdat
&& ++lock_batch
== SWAP_CLUSTER_MAX
) {
735 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
739 if (is_huge_zero_page(page
))
742 /* Device public page can not be huge page */
743 if (is_device_public_page(page
)) {
745 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
,
749 put_devmap_managed_page(page
);
753 page
= compound_head(page
);
754 if (!put_page_testzero(page
))
757 if (PageCompound(page
)) {
759 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
762 __put_compound_page(page
);
767 struct pglist_data
*pgdat
= page_pgdat(page
);
769 if (pgdat
!= locked_pgdat
) {
771 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
,
774 locked_pgdat
= pgdat
;
775 spin_lock_irqsave(&locked_pgdat
->lru_lock
, flags
);
778 lruvec
= mem_cgroup_page_lruvec(page
, locked_pgdat
);
779 VM_BUG_ON_PAGE(!PageLRU(page
), page
);
780 __ClearPageLRU(page
);
781 del_page_from_lru_list(page
, lruvec
, page_off_lru(page
));
784 /* Clear Active bit in case of parallel mark_page_accessed */
785 __ClearPageActive(page
);
786 __ClearPageWaiters(page
);
788 list_add(&page
->lru
, &pages_to_free
);
791 spin_unlock_irqrestore(&locked_pgdat
->lru_lock
, flags
);
793 mem_cgroup_uncharge_list(&pages_to_free
);
794 free_unref_page_list(&pages_to_free
);
796 EXPORT_SYMBOL(release_pages
);
799 * The pages which we're about to release may be in the deferred lru-addition
800 * queues. That would prevent them from really being freed right now. That's
801 * OK from a correctness point of view but is inefficient - those pages may be
802 * cache-warm and we want to give them back to the page allocator ASAP.
804 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
805 * and __pagevec_lru_add_active() call release_pages() directly to avoid
808 void __pagevec_release(struct pagevec
*pvec
)
810 if (!pvec
->percpu_pvec_drained
) {
812 pvec
->percpu_pvec_drained
= true;
814 release_pages(pvec
->pages
, pagevec_count(pvec
));
815 pagevec_reinit(pvec
);
817 EXPORT_SYMBOL(__pagevec_release
);
819 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
820 /* used by __split_huge_page_refcount() */
821 void lru_add_page_tail(struct page
*page
, struct page
*page_tail
,
822 struct lruvec
*lruvec
, struct list_head
*list
)
826 VM_BUG_ON_PAGE(!PageHead(page
), page
);
827 VM_BUG_ON_PAGE(PageCompound(page_tail
), page
);
828 VM_BUG_ON_PAGE(PageLRU(page_tail
), page
);
829 lockdep_assert_held(&lruvec_pgdat(lruvec
)->lru_lock
);
832 SetPageLRU(page_tail
);
834 if (likely(PageLRU(page
)))
835 list_add_tail(&page_tail
->lru
, &page
->lru
);
837 /* page reclaim is reclaiming a huge page */
839 list_add_tail(&page_tail
->lru
, list
);
841 struct list_head
*list_head
;
843 * Head page has not yet been counted, as an hpage,
844 * so we must account for each subpage individually.
846 * Use the standard add function to put page_tail on the list,
847 * but then correct its position so they all end up in order.
849 add_page_to_lru_list(page_tail
, lruvec
, page_lru(page_tail
));
850 list_head
= page_tail
->lru
.prev
;
851 list_move_tail(&page_tail
->lru
, list_head
);
854 if (!PageUnevictable(page
))
855 update_page_reclaim_stat(lruvec
, file
, PageActive(page_tail
));
857 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
859 static void __pagevec_lru_add_fn(struct page
*page
, struct lruvec
*lruvec
,
863 int was_unevictable
= TestClearPageUnevictable(page
);
865 VM_BUG_ON_PAGE(PageLRU(page
), page
);
869 * Page becomes evictable in two ways:
870 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
871 * 2) Before acquiring LRU lock to put the page to correct LRU and then
872 * a) do PageLRU check with lock [check_move_unevictable_pages]
873 * b) do PageLRU check before lock [clear_page_mlock]
875 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
876 * following strict ordering:
878 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
880 * SetPageLRU() TestClearPageMlocked()
881 * smp_mb() // explicit ordering // above provides strict
883 * PageMlocked() PageLRU()
886 * if '#1' does not observe setting of PG_lru by '#0' and fails
887 * isolation, the explicit barrier will make sure that page_evictable
888 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
889 * can be reordered after PageMlocked check and can make '#1' to fail
890 * the isolation of the page whose Mlocked bit is cleared (#0 is also
891 * looking at the same page) and the evictable page will be stranded
892 * in an unevictable LRU.
896 if (page_evictable(page
)) {
897 lru
= page_lru(page
);
898 update_page_reclaim_stat(lruvec
, page_is_file_cache(page
),
901 count_vm_event(UNEVICTABLE_PGRESCUED
);
903 lru
= LRU_UNEVICTABLE
;
904 ClearPageActive(page
);
905 SetPageUnevictable(page
);
906 if (!was_unevictable
)
907 count_vm_event(UNEVICTABLE_PGCULLED
);
910 add_page_to_lru_list(page
, lruvec
, lru
);
911 trace_mm_lru_insertion(page
, lru
);
915 * Add the passed pages to the LRU, then drop the caller's refcount
916 * on them. Reinitialises the caller's pagevec.
918 void __pagevec_lru_add(struct pagevec
*pvec
)
920 pagevec_lru_move_fn(pvec
, __pagevec_lru_add_fn
, NULL
);
922 EXPORT_SYMBOL(__pagevec_lru_add
);
925 * pagevec_lookup_entries - gang pagecache lookup
926 * @pvec: Where the resulting entries are placed
927 * @mapping: The address_space to search
928 * @start: The starting entry index
929 * @nr_entries: The maximum number of pages
930 * @indices: The cache indices corresponding to the entries in @pvec
932 * pagevec_lookup_entries() will search for and return a group of up
933 * to @nr_pages pages and shadow entries in the mapping. All
934 * entries are placed in @pvec. pagevec_lookup_entries() takes a
935 * reference against actual pages in @pvec.
937 * The search returns a group of mapping-contiguous entries with
938 * ascending indexes. There may be holes in the indices due to
939 * not-present entries.
941 * pagevec_lookup_entries() returns the number of entries which were
944 unsigned pagevec_lookup_entries(struct pagevec
*pvec
,
945 struct address_space
*mapping
,
946 pgoff_t start
, unsigned nr_entries
,
949 pvec
->nr
= find_get_entries(mapping
, start
, nr_entries
,
950 pvec
->pages
, indices
);
951 return pagevec_count(pvec
);
955 * pagevec_remove_exceptionals - pagevec exceptionals pruning
956 * @pvec: The pagevec to prune
958 * pagevec_lookup_entries() fills both pages and exceptional radix
959 * tree entries into the pagevec. This function prunes all
960 * exceptionals from @pvec without leaving holes, so that it can be
961 * passed on to page-only pagevec operations.
963 void pagevec_remove_exceptionals(struct pagevec
*pvec
)
967 for (i
= 0, j
= 0; i
< pagevec_count(pvec
); i
++) {
968 struct page
*page
= pvec
->pages
[i
];
969 if (!xa_is_value(page
))
970 pvec
->pages
[j
++] = page
;
976 * pagevec_lookup_range - gang pagecache lookup
977 * @pvec: Where the resulting pages are placed
978 * @mapping: The address_space to search
979 * @start: The starting page index
980 * @end: The final page index
982 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
983 * pages in the mapping starting from index @start and upto index @end
984 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
985 * reference against the pages in @pvec.
987 * The search returns a group of mapping-contiguous pages with ascending
988 * indexes. There may be holes in the indices due to not-present pages. We
989 * also update @start to index the next page for the traversal.
991 * pagevec_lookup_range() returns the number of pages which were found. If this
992 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
995 unsigned pagevec_lookup_range(struct pagevec
*pvec
,
996 struct address_space
*mapping
, pgoff_t
*start
, pgoff_t end
)
998 pvec
->nr
= find_get_pages_range(mapping
, start
, end
, PAGEVEC_SIZE
,
1000 return pagevec_count(pvec
);
1002 EXPORT_SYMBOL(pagevec_lookup_range
);
1004 unsigned pagevec_lookup_range_tag(struct pagevec
*pvec
,
1005 struct address_space
*mapping
, pgoff_t
*index
, pgoff_t end
,
1008 pvec
->nr
= find_get_pages_range_tag(mapping
, index
, end
, tag
,
1009 PAGEVEC_SIZE
, pvec
->pages
);
1010 return pagevec_count(pvec
);
1012 EXPORT_SYMBOL(pagevec_lookup_range_tag
);
1014 unsigned pagevec_lookup_range_nr_tag(struct pagevec
*pvec
,
1015 struct address_space
*mapping
, pgoff_t
*index
, pgoff_t end
,
1016 xa_mark_t tag
, unsigned max_pages
)
1018 pvec
->nr
= find_get_pages_range_tag(mapping
, index
, end
, tag
,
1019 min_t(unsigned int, max_pages
, PAGEVEC_SIZE
), pvec
->pages
);
1020 return pagevec_count(pvec
);
1022 EXPORT_SYMBOL(pagevec_lookup_range_nr_tag
);
1024 * Perform any setup for the swap system
1026 void __init
swap_setup(void)
1028 unsigned long megs
= totalram_pages() >> (20 - PAGE_SHIFT
);
1030 /* Use a smaller cluster for small-memory machines */
1036 * Right now other parts of the system means that we
1037 * _really_ don't want to cluster much more