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/percpu.h>
28 #include <linux/cpu.h>
29 #include <linux/notifier.h>
30 #include <linux/backing-dev.h>
31 #include <linux/memcontrol.h>
32 #include <linux/gfp.h>
33 #include <linux/uio.h>
34 #include <linux/hugetlb.h>
35 #include <linux/page_idle.h>
39 #define CREATE_TRACE_POINTS
40 #include <trace/events/pagemap.h>
42 /* How many pages do we try to swap or page in/out together? */
45 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
46 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
47 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
50 * This path almost never happens for VM activity - pages are normally
51 * freed via pagevecs. But it gets used by networking.
53 static void __page_cache_release(struct page *page)
56 struct zone *zone = page_zone(page);
57 struct lruvec *lruvec;
60 spin_lock_irqsave(&zone->lru_lock, flags);
61 lruvec = mem_cgroup_page_lruvec(page, zone);
62 VM_BUG_ON_PAGE(!PageLRU(page), page);
64 del_page_from_lru_list(page, lruvec, page_off_lru(page));
65 spin_unlock_irqrestore(&zone->lru_lock, flags);
67 mem_cgroup_uncharge(page);
70 static void __put_single_page(struct page *page)
72 __page_cache_release(page);
73 free_hot_cold_page(page, false);
76 static void __put_compound_page(struct page *page)
78 compound_page_dtor *dtor;
81 * __page_cache_release() is supposed to be called for thp, not for
82 * hugetlb. This is because hugetlb page does never have PageLRU set
83 * (it's never listed to any LRU lists) and no memcg routines should
84 * be called for hugetlb (it has a separate hugetlb_cgroup.)
87 __page_cache_release(page);
88 dtor = get_compound_page_dtor(page);
93 * Two special cases here: we could avoid taking compound_lock_irqsave
94 * and could skip the tail refcounting(in _mapcount).
98 * PageHeadHuge will remain true until the compound page
99 * is released and enters the buddy allocator, and it could
100 * not be split by __split_huge_page_refcount().
102 * So if we see PageHeadHuge set, and we have the tail page pin,
103 * then we could safely put head page.
107 * PG_slab is cleared before the slab frees the head page, and
108 * tail pin cannot be the last reference left on the head page,
109 * because the slab code is free to reuse the compound page
110 * after a kfree/kmem_cache_free without having to check if
111 * there's any tail pin left. In turn all tail pinsmust be always
112 * released while the head is still pinned by the slab code
113 * and so we know PG_slab will be still set too.
115 * So if we see PageSlab set, and we have the tail page pin,
116 * then we could safely put head page.
118 static __always_inline
119 void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
122 * If @page is a THP tail, we must read the tail page
123 * flags after the head page flags. The
124 * __split_huge_page_refcount side enforces write memory barriers
125 * between clearing PageTail and before the head page
126 * can be freed and reallocated.
129 if (likely(PageTail(page))) {
131 * __split_huge_page_refcount cannot race
132 * here, see the comment above this function.
134 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
135 if (put_page_testzero(page_head)) {
137 * If this is the tail of a slab THP page,
138 * the tail pin must not be the last reference
139 * held on the page, because the PG_slab cannot
140 * be cleared before all tail pins (which skips
141 * the _mapcount tail refcounting) have been
144 * If this is the tail of a hugetlbfs page,
145 * the tail pin may be the last reference on
146 * the page instead, because PageHeadHuge will
147 * not go away until the compound page enters
148 * the buddy allocator.
150 VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
151 __put_compound_page(page_head);
155 * __split_huge_page_refcount run before us,
156 * @page was a THP tail. The split @page_head
157 * has been freed and reallocated as slab or
158 * hugetlbfs page of smaller order (only
159 * possible if reallocated as slab on x86).
161 if (put_page_testzero(page))
162 __put_single_page(page);
165 static __always_inline
166 void put_refcounted_compound_page(struct page *page_head, struct page *page)
168 if (likely(page != page_head && get_page_unless_zero(page_head))) {
172 * @page_head wasn't a dangling pointer but it may not
173 * be a head page anymore by the time we obtain the
174 * lock. That is ok as long as it can't be freed from
177 flags = compound_lock_irqsave(page_head);
178 if (unlikely(!PageTail(page))) {
179 /* __split_huge_page_refcount run before us */
180 compound_unlock_irqrestore(page_head, flags);
181 if (put_page_testzero(page_head)) {
183 * The @page_head may have been freed
184 * and reallocated as a compound page
185 * of smaller order and then freed
186 * again. All we know is that it
187 * cannot have become: a THP page, a
188 * compound page of higher order, a
189 * tail page. That is because we
190 * still hold the refcount of the
191 * split THP tail and page_head was
192 * the THP head before the split.
194 if (PageHead(page_head))
195 __put_compound_page(page_head);
197 __put_single_page(page_head);
200 if (put_page_testzero(page))
201 __put_single_page(page);
204 VM_BUG_ON_PAGE(page_head != page->first_page, page);
206 * We can release the refcount taken by
207 * get_page_unless_zero() now that
208 * __split_huge_page_refcount() is blocked on the
211 if (put_page_testzero(page_head))
212 VM_BUG_ON_PAGE(1, page_head);
213 /* __split_huge_page_refcount will wait now */
214 VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
215 atomic_dec(&page->_mapcount);
216 VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
217 VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
218 compound_unlock_irqrestore(page_head, flags);
220 if (put_page_testzero(page_head)) {
221 if (PageHead(page_head))
222 __put_compound_page(page_head);
224 __put_single_page(page_head);
227 /* @page_head is a dangling pointer */
228 VM_BUG_ON_PAGE(PageTail(page), page);
233 static void put_compound_page(struct page *page)
235 struct page *page_head;
238 * We see the PageCompound set and PageTail not set, so @page maybe:
239 * 1. hugetlbfs head page, or
242 if (likely(!PageTail(page))) {
243 if (put_page_testzero(page)) {
245 * By the time all refcounts have been released
246 * split_huge_page cannot run anymore from under us.
249 __put_compound_page(page);
251 __put_single_page(page);
257 * We see the PageCompound set and PageTail set, so @page maybe:
258 * 1. a tail hugetlbfs page, or
259 * 2. a tail THP page, or
260 * 3. a split THP page.
262 * Case 3 is possible, as we may race with
263 * __split_huge_page_refcount tearing down a THP page.
265 page_head = compound_head_by_tail(page);
266 if (!__compound_tail_refcounted(page_head))
267 put_unrefcounted_compound_page(page_head, page);
269 put_refcounted_compound_page(page_head, page);
272 void put_page(struct page *page)
274 if (unlikely(PageCompound(page)))
275 put_compound_page(page);
276 else if (put_page_testzero(page))
277 __put_single_page(page);
279 EXPORT_SYMBOL(put_page);
282 * This function is exported but must not be called by anything other
283 * than get_page(). It implements the slow path of get_page().
285 bool __get_page_tail(struct page *page)
288 * This takes care of get_page() if run on a tail page
289 * returned by one of the get_user_pages/follow_page variants.
290 * get_user_pages/follow_page itself doesn't need the compound
291 * lock because it runs __get_page_tail_foll() under the
292 * proper PT lock that already serializes against
297 struct page *page_head = compound_head(page);
299 /* Ref to put_compound_page() comment. */
300 if (!__compound_tail_refcounted(page_head)) {
302 if (likely(PageTail(page))) {
304 * This is a hugetlbfs page or a slab
305 * page. __split_huge_page_refcount
308 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
309 __get_page_tail_foll(page, true);
313 * __split_huge_page_refcount run
314 * before us, "page" was a THP
315 * tail. The split page_head has been
316 * freed and reallocated as slab or
317 * hugetlbfs page of smaller order
318 * (only possible if reallocated as
326 if (likely(page != page_head && get_page_unless_zero(page_head))) {
328 * page_head wasn't a dangling pointer but it
329 * may not be a head page anymore by the time
330 * we obtain the lock. That is ok as long as it
331 * can't be freed from under us.
333 flags = compound_lock_irqsave(page_head);
334 /* here __split_huge_page_refcount won't run anymore */
335 if (likely(PageTail(page))) {
336 __get_page_tail_foll(page, false);
339 compound_unlock_irqrestore(page_head, flags);
345 EXPORT_SYMBOL(__get_page_tail);
348 * put_pages_list() - release a list of pages
349 * @pages: list of pages threaded on page->lru
351 * Release a list of pages which are strung together on page.lru. Currently
352 * used by read_cache_pages() and related error recovery code.
354 void put_pages_list(struct list_head *pages)
356 while (!list_empty(pages)) {
359 victim = list_entry(pages->prev, struct page, lru);
360 list_del(&victim->lru);
361 page_cache_release(victim);
364 EXPORT_SYMBOL(put_pages_list);
367 * get_kernel_pages() - pin kernel pages in memory
368 * @kiov: An array of struct kvec structures
369 * @nr_segs: number of segments to pin
370 * @write: pinning for read/write, currently ignored
371 * @pages: array that receives pointers to the pages pinned.
372 * Should be at least nr_segs long.
374 * Returns number of pages pinned. This may be fewer than the number
375 * requested. If nr_pages is 0 or negative, returns 0. If no pages
376 * were pinned, returns -errno. Each page returned must be released
377 * with a put_page() call when it is finished with.
379 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
384 for (seg = 0; seg < nr_segs; seg++) {
385 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
388 pages[seg] = kmap_to_page(kiov[seg].iov_base);
389 page_cache_get(pages[seg]);
394 EXPORT_SYMBOL_GPL(get_kernel_pages);
397 * get_kernel_page() - pin a kernel page in memory
398 * @start: starting kernel address
399 * @write: pinning for read/write, currently ignored
400 * @pages: array that receives pointer to the page pinned.
401 * Must be at least nr_segs long.
403 * Returns 1 if page is pinned. If the page was not pinned, returns
404 * -errno. The page returned must be released with a put_page() call
405 * when it is finished with.
407 int get_kernel_page(unsigned long start, int write, struct page **pages)
409 const struct kvec kiov = {
410 .iov_base = (void *)start,
414 return get_kernel_pages(&kiov, 1, write, pages);
416 EXPORT_SYMBOL_GPL(get_kernel_page);
418 static void pagevec_lru_move_fn(struct pagevec *pvec,
419 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
423 struct zone *zone = NULL;
424 struct lruvec *lruvec;
425 unsigned long flags = 0;
427 for (i = 0; i < pagevec_count(pvec); i++) {
428 struct page *page = pvec->pages[i];
429 struct zone *pagezone = page_zone(page);
431 if (pagezone != zone) {
433 spin_unlock_irqrestore(&zone->lru_lock, flags);
435 spin_lock_irqsave(&zone->lru_lock, flags);
438 lruvec = mem_cgroup_page_lruvec(page, zone);
439 (*move_fn)(page, lruvec, arg);
442 spin_unlock_irqrestore(&zone->lru_lock, flags);
443 release_pages(pvec->pages, pvec->nr, pvec->cold);
444 pagevec_reinit(pvec);
447 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
452 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
453 enum lru_list lru = page_lru_base_type(page);
454 list_move_tail(&page->lru, &lruvec->lists[lru]);
460 * pagevec_move_tail() must be called with IRQ disabled.
461 * Otherwise this may cause nasty races.
463 static void pagevec_move_tail(struct pagevec *pvec)
467 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
468 __count_vm_events(PGROTATED, pgmoved);
472 * Writeback is about to end against a page which has been marked for immediate
473 * reclaim. If it still appears to be reclaimable, move it to the tail of the
476 void rotate_reclaimable_page(struct page *page)
478 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
479 !PageUnevictable(page) && PageLRU(page)) {
480 struct pagevec *pvec;
483 page_cache_get(page);
484 local_irq_save(flags);
485 pvec = this_cpu_ptr(&lru_rotate_pvecs);
486 if (!pagevec_add(pvec, page))
487 pagevec_move_tail(pvec);
488 local_irq_restore(flags);
492 static void update_page_reclaim_stat(struct lruvec *lruvec,
493 int file, int rotated)
495 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
497 reclaim_stat->recent_scanned[file]++;
499 reclaim_stat->recent_rotated[file]++;
502 static void __activate_page(struct page *page, struct lruvec *lruvec,
505 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
506 int file = page_is_file_cache(page);
507 int lru = page_lru_base_type(page);
509 del_page_from_lru_list(page, lruvec, lru);
512 add_page_to_lru_list(page, lruvec, lru);
513 trace_mm_lru_activate(page);
515 __count_vm_event(PGACTIVATE);
516 update_page_reclaim_stat(lruvec, file, 1);
521 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
523 static void activate_page_drain(int cpu)
525 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
527 if (pagevec_count(pvec))
528 pagevec_lru_move_fn(pvec, __activate_page, NULL);
531 static bool need_activate_page_drain(int cpu)
533 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
536 void activate_page(struct page *page)
538 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
539 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
541 page_cache_get(page);
542 if (!pagevec_add(pvec, page))
543 pagevec_lru_move_fn(pvec, __activate_page, NULL);
544 put_cpu_var(activate_page_pvecs);
549 static inline void activate_page_drain(int cpu)
553 static bool need_activate_page_drain(int cpu)
558 void activate_page(struct page *page)
560 struct zone *zone = page_zone(page);
562 spin_lock_irq(&zone->lru_lock);
563 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
564 spin_unlock_irq(&zone->lru_lock);
568 static void __lru_cache_activate_page(struct page *page)
570 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
574 * Search backwards on the optimistic assumption that the page being
575 * activated has just been added to this pagevec. Note that only
576 * the local pagevec is examined as a !PageLRU page could be in the
577 * process of being released, reclaimed, migrated or on a remote
578 * pagevec that is currently being drained. Furthermore, marking
579 * a remote pagevec's page PageActive potentially hits a race where
580 * a page is marked PageActive just after it is added to the inactive
581 * list causing accounting errors and BUG_ON checks to trigger.
583 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
584 struct page *pagevec_page = pvec->pages[i];
586 if (pagevec_page == page) {
592 put_cpu_var(lru_add_pvec);
596 * Mark a page as having seen activity.
598 * inactive,unreferenced -> inactive,referenced
599 * inactive,referenced -> active,unreferenced
600 * active,unreferenced -> active,referenced
602 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
603 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
605 void mark_page_accessed(struct page *page)
607 if (!PageActive(page) && !PageUnevictable(page) &&
608 PageReferenced(page)) {
611 * If the page is on the LRU, queue it for activation via
612 * activate_page_pvecs. Otherwise, assume the page is on a
613 * pagevec, mark it active and it'll be moved to the active
614 * LRU on the next drain.
619 __lru_cache_activate_page(page);
620 ClearPageReferenced(page);
621 if (page_is_file_cache(page))
622 workingset_activation(page);
623 } else if (!PageReferenced(page)) {
624 SetPageReferenced(page);
626 if (page_is_idle(page))
627 clear_page_idle(page);
629 EXPORT_SYMBOL(mark_page_accessed);
631 static void __lru_cache_add(struct page *page)
633 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
635 page_cache_get(page);
636 if (!pagevec_space(pvec))
637 __pagevec_lru_add(pvec);
638 pagevec_add(pvec, page);
639 put_cpu_var(lru_add_pvec);
643 * lru_cache_add: add a page to the page lists
644 * @page: the page to add
646 void lru_cache_add_anon(struct page *page)
648 if (PageActive(page))
649 ClearPageActive(page);
650 __lru_cache_add(page);
653 void lru_cache_add_file(struct page *page)
655 if (PageActive(page))
656 ClearPageActive(page);
657 __lru_cache_add(page);
659 EXPORT_SYMBOL(lru_cache_add_file);
662 * lru_cache_add - add a page to a page list
663 * @page: the page to be added to the LRU.
665 * Queue the page for addition to the LRU via pagevec. The decision on whether
666 * to add the page to the [in]active [file|anon] list is deferred until the
667 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
668 * have the page added to the active list using mark_page_accessed().
670 void lru_cache_add(struct page *page)
672 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
673 VM_BUG_ON_PAGE(PageLRU(page), page);
674 __lru_cache_add(page);
678 * add_page_to_unevictable_list - add a page to the unevictable list
679 * @page: the page to be added to the unevictable list
681 * Add page directly to its zone's unevictable list. To avoid races with
682 * tasks that might be making the page evictable, through eg. munlock,
683 * munmap or exit, while it's not on the lru, we want to add the page
684 * while it's locked or otherwise "invisible" to other tasks. This is
685 * difficult to do when using the pagevec cache, so bypass that.
687 void add_page_to_unevictable_list(struct page *page)
689 struct zone *zone = page_zone(page);
690 struct lruvec *lruvec;
692 spin_lock_irq(&zone->lru_lock);
693 lruvec = mem_cgroup_page_lruvec(page, zone);
694 ClearPageActive(page);
695 SetPageUnevictable(page);
697 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
698 spin_unlock_irq(&zone->lru_lock);
702 * lru_cache_add_active_or_unevictable
703 * @page: the page to be added to LRU
704 * @vma: vma in which page is mapped for determining reclaimability
706 * Place @page on the active or unevictable LRU list, depending on its
707 * evictability. Note that if the page is not evictable, it goes
708 * directly back onto it's zone's unevictable list, it does NOT use a
711 void lru_cache_add_active_or_unevictable(struct page *page,
712 struct vm_area_struct *vma)
714 VM_BUG_ON_PAGE(PageLRU(page), page);
716 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
722 if (!TestSetPageMlocked(page)) {
724 * We use the irq-unsafe __mod_zone_page_stat because this
725 * counter is not modified from interrupt context, and the pte
726 * lock is held(spinlock), which implies preemption disabled.
728 __mod_zone_page_state(page_zone(page), NR_MLOCK,
729 hpage_nr_pages(page));
730 count_vm_event(UNEVICTABLE_PGMLOCKED);
732 add_page_to_unevictable_list(page);
736 * If the page can not be invalidated, it is moved to the
737 * inactive list to speed up its reclaim. It is moved to the
738 * head of the list, rather than the tail, to give the flusher
739 * threads some time to write it out, as this is much more
740 * effective than the single-page writeout from reclaim.
742 * If the page isn't page_mapped and dirty/writeback, the page
743 * could reclaim asap using PG_reclaim.
745 * 1. active, mapped page -> none
746 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
747 * 3. inactive, mapped page -> none
748 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
749 * 5. inactive, clean -> inactive, tail
752 * In 4, why it moves inactive's head, the VM expects the page would
753 * be write it out by flusher threads as this is much more effective
754 * than the single-page writeout from reclaim.
756 static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
765 if (PageUnevictable(page))
768 /* Some processes are using the page */
769 if (page_mapped(page))
772 active = PageActive(page);
773 file = page_is_file_cache(page);
774 lru = page_lru_base_type(page);
776 del_page_from_lru_list(page, lruvec, lru + active);
777 ClearPageActive(page);
778 ClearPageReferenced(page);
779 add_page_to_lru_list(page, lruvec, lru);
781 if (PageWriteback(page) || PageDirty(page)) {
783 * PG_reclaim could be raced with end_page_writeback
784 * It can make readahead confusing. But race window
785 * is _really_ small and it's non-critical problem.
787 SetPageReclaim(page);
790 * The page's writeback ends up during pagevec
791 * We moves tha page into tail of inactive.
793 list_move_tail(&page->lru, &lruvec->lists[lru]);
794 __count_vm_event(PGROTATED);
798 __count_vm_event(PGDEACTIVATE);
799 update_page_reclaim_stat(lruvec, file, 0);
803 * Drain pages out of the cpu's pagevecs.
804 * Either "cpu" is the current CPU, and preemption has already been
805 * disabled; or "cpu" is being hot-unplugged, and is already dead.
807 void lru_add_drain_cpu(int cpu)
809 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
811 if (pagevec_count(pvec))
812 __pagevec_lru_add(pvec);
814 pvec = &per_cpu(lru_rotate_pvecs, cpu);
815 if (pagevec_count(pvec)) {
818 /* No harm done if a racing interrupt already did this */
819 local_irq_save(flags);
820 pagevec_move_tail(pvec);
821 local_irq_restore(flags);
824 pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
825 if (pagevec_count(pvec))
826 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
828 activate_page_drain(cpu);
832 * deactivate_file_page - forcefully deactivate a file page
833 * @page: page to deactivate
835 * This function hints the VM that @page is a good reclaim candidate,
836 * for example if its invalidation fails due to the page being dirty
837 * or under writeback.
839 void deactivate_file_page(struct page *page)
842 * In a workload with many unevictable page such as mprotect,
843 * unevictable page deactivation for accelerating reclaim is pointless.
845 if (PageUnevictable(page))
848 if (likely(get_page_unless_zero(page))) {
849 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
851 if (!pagevec_add(pvec, page))
852 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
853 put_cpu_var(lru_deactivate_file_pvecs);
857 void lru_add_drain(void)
859 lru_add_drain_cpu(get_cpu());
863 static void lru_add_drain_per_cpu(struct work_struct *dummy)
868 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
870 void lru_add_drain_all(void)
872 static DEFINE_MUTEX(lock);
873 static struct cpumask has_work;
878 cpumask_clear(&has_work);
880 for_each_online_cpu(cpu) {
881 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
883 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
884 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
885 pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
886 need_activate_page_drain(cpu)) {
887 INIT_WORK(work, lru_add_drain_per_cpu);
888 schedule_work_on(cpu, work);
889 cpumask_set_cpu(cpu, &has_work);
893 for_each_cpu(cpu, &has_work)
894 flush_work(&per_cpu(lru_add_drain_work, cpu));
901 * release_pages - batched page_cache_release()
902 * @pages: array of pages to release
903 * @nr: number of pages
904 * @cold: whether the pages are cache cold
906 * Decrement the reference count on all the pages in @pages. If it
907 * fell to zero, remove the page from the LRU and free it.
909 void release_pages(struct page **pages, int nr, bool cold)
912 LIST_HEAD(pages_to_free);
913 struct zone *zone = NULL;
914 struct lruvec *lruvec;
915 unsigned long uninitialized_var(flags);
916 unsigned int uninitialized_var(lock_batch);
918 for (i = 0; i < nr; i++) {
919 struct page *page = pages[i];
921 if (unlikely(PageCompound(page))) {
923 spin_unlock_irqrestore(&zone->lru_lock, flags);
926 put_compound_page(page);
931 * Make sure the IRQ-safe lock-holding time does not get
932 * excessive with a continuous string of pages from the
933 * same zone. The lock is held only if zone != NULL.
935 if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
936 spin_unlock_irqrestore(&zone->lru_lock, flags);
940 if (!put_page_testzero(page))
944 struct zone *pagezone = page_zone(page);
946 if (pagezone != zone) {
948 spin_unlock_irqrestore(&zone->lru_lock,
952 spin_lock_irqsave(&zone->lru_lock, flags);
955 lruvec = mem_cgroup_page_lruvec(page, zone);
956 VM_BUG_ON_PAGE(!PageLRU(page), page);
957 __ClearPageLRU(page);
958 del_page_from_lru_list(page, lruvec, page_off_lru(page));
961 /* Clear Active bit in case of parallel mark_page_accessed */
962 __ClearPageActive(page);
964 list_add(&page->lru, &pages_to_free);
967 spin_unlock_irqrestore(&zone->lru_lock, flags);
969 mem_cgroup_uncharge_list(&pages_to_free);
970 free_hot_cold_page_list(&pages_to_free, cold);
972 EXPORT_SYMBOL(release_pages);
975 * The pages which we're about to release may be in the deferred lru-addition
976 * queues. That would prevent them from really being freed right now. That's
977 * OK from a correctness point of view but is inefficient - those pages may be
978 * cache-warm and we want to give them back to the page allocator ASAP.
980 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
981 * and __pagevec_lru_add_active() call release_pages() directly to avoid
984 void __pagevec_release(struct pagevec *pvec)
987 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
988 pagevec_reinit(pvec);
990 EXPORT_SYMBOL(__pagevec_release);
992 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
993 /* used by __split_huge_page_refcount() */
994 void lru_add_page_tail(struct page *page, struct page *page_tail,
995 struct lruvec *lruvec, struct list_head *list)
999 VM_BUG_ON_PAGE(!PageHead(page), page);
1000 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
1001 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
1002 VM_BUG_ON(NR_CPUS != 1 &&
1003 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
1006 SetPageLRU(page_tail);
1008 if (likely(PageLRU(page)))
1009 list_add_tail(&page_tail->lru, &page->lru);
1011 /* page reclaim is reclaiming a huge page */
1012 get_page(page_tail);
1013 list_add_tail(&page_tail->lru, list);
1015 struct list_head *list_head;
1017 * Head page has not yet been counted, as an hpage,
1018 * so we must account for each subpage individually.
1020 * Use the standard add function to put page_tail on the list,
1021 * but then correct its position so they all end up in order.
1023 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
1024 list_head = page_tail->lru.prev;
1025 list_move_tail(&page_tail->lru, list_head);
1028 if (!PageUnevictable(page))
1029 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
1031 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1033 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
1036 int file = page_is_file_cache(page);
1037 int active = PageActive(page);
1038 enum lru_list lru = page_lru(page);
1040 VM_BUG_ON_PAGE(PageLRU(page), page);
1043 add_page_to_lru_list(page, lruvec, lru);
1044 update_page_reclaim_stat(lruvec, file, active);
1045 trace_mm_lru_insertion(page, lru);
1049 * Add the passed pages to the LRU, then drop the caller's refcount
1050 * on them. Reinitialises the caller's pagevec.
1052 void __pagevec_lru_add(struct pagevec *pvec)
1054 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
1056 EXPORT_SYMBOL(__pagevec_lru_add);
1059 * pagevec_lookup_entries - gang pagecache lookup
1060 * @pvec: Where the resulting entries are placed
1061 * @mapping: The address_space to search
1062 * @start: The starting entry index
1063 * @nr_entries: The maximum number of entries
1064 * @indices: The cache indices corresponding to the entries in @pvec
1066 * pagevec_lookup_entries() will search for and return a group of up
1067 * to @nr_entries pages and shadow entries in the mapping. All
1068 * entries are placed in @pvec. pagevec_lookup_entries() takes a
1069 * reference against actual pages in @pvec.
1071 * The search returns a group of mapping-contiguous entries with
1072 * ascending indexes. There may be holes in the indices due to
1073 * not-present entries.
1075 * pagevec_lookup_entries() returns the number of entries which were
1078 unsigned pagevec_lookup_entries(struct pagevec *pvec,
1079 struct address_space *mapping,
1080 pgoff_t start, unsigned nr_pages,
1083 pvec->nr = find_get_entries(mapping, start, nr_pages,
1084 pvec->pages, indices);
1085 return pagevec_count(pvec);
1089 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1090 * @pvec: The pagevec to prune
1092 * pagevec_lookup_entries() fills both pages and exceptional radix
1093 * tree entries into the pagevec. This function prunes all
1094 * exceptionals from @pvec without leaving holes, so that it can be
1095 * passed on to page-only pagevec operations.
1097 void pagevec_remove_exceptionals(struct pagevec *pvec)
1101 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1102 struct page *page = pvec->pages[i];
1103 if (!radix_tree_exceptional_entry(page))
1104 pvec->pages[j++] = page;
1110 * pagevec_lookup - gang pagecache lookup
1111 * @pvec: Where the resulting pages are placed
1112 * @mapping: The address_space to search
1113 * @start: The starting page index
1114 * @nr_pages: The maximum number of pages
1116 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
1117 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
1118 * reference against the pages in @pvec.
1120 * The search returns a group of mapping-contiguous pages with ascending
1121 * indexes. There may be holes in the indices due to not-present pages.
1123 * pagevec_lookup() returns the number of pages which were found.
1125 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
1126 pgoff_t start, unsigned nr_pages)
1128 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
1129 return pagevec_count(pvec);
1131 EXPORT_SYMBOL(pagevec_lookup);
1133 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
1134 pgoff_t *index, int tag, unsigned nr_pages)
1136 pvec->nr = find_get_pages_tag(mapping, index, tag,
1137 nr_pages, pvec->pages);
1138 return pagevec_count(pvec);
1140 EXPORT_SYMBOL(pagevec_lookup_tag);
1143 * Perform any setup for the swap system
1145 void __init swap_setup(void)
1147 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
1151 for (i = 0; i < MAX_SWAPFILES; i++)
1152 spin_lock_init(&swapper_spaces[i].tree_lock);
1155 /* Use a smaller cluster for small-memory machines */
1161 * Right now other parts of the system means that we
1162 * _really_ don't want to cluster much more