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>
37 #define CREATE_TRACE_POINTS
38 #include <trace/events/pagemap.h>
40 /* How many pages do we try to swap or page in/out together? */
43 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
44 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
45 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
48 * This path almost never happens for VM activity - pages are normally
49 * freed via pagevecs. But it gets used by networking.
51 static void __page_cache_release(struct page *page)
54 struct zone *zone = page_zone(page);
55 struct lruvec *lruvec;
58 spin_lock_irqsave(&zone->lru_lock, flags);
59 lruvec = mem_cgroup_page_lruvec(page, zone);
60 VM_BUG_ON_PAGE(!PageLRU(page), page);
62 del_page_from_lru_list(page, lruvec, page_off_lru(page));
63 spin_unlock_irqrestore(&zone->lru_lock, flags);
65 mem_cgroup_uncharge(page);
68 static void __put_single_page(struct page *page)
70 __page_cache_release(page);
71 free_hot_cold_page(page, false);
74 static void __put_compound_page(struct page *page)
76 compound_page_dtor *dtor;
78 __page_cache_release(page);
79 dtor = get_compound_page_dtor(page);
84 * Two special cases here: we could avoid taking compound_lock_irqsave
85 * and could skip the tail refcounting(in _mapcount).
89 * PageHeadHuge will remain true until the compound page
90 * is released and enters the buddy allocator, and it could
91 * not be split by __split_huge_page_refcount().
93 * So if we see PageHeadHuge set, and we have the tail page pin,
94 * then we could safely put head page.
98 * PG_slab is cleared before the slab frees the head page, and
99 * tail pin cannot be the last reference left on the head page,
100 * because the slab code is free to reuse the compound page
101 * after a kfree/kmem_cache_free without having to check if
102 * there's any tail pin left. In turn all tail pinsmust be always
103 * released while the head is still pinned by the slab code
104 * and so we know PG_slab will be still set too.
106 * So if we see PageSlab set, and we have the tail page pin,
107 * then we could safely put head page.
109 static __always_inline
110 void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
113 * If @page is a THP tail, we must read the tail page
114 * flags after the head page flags. The
115 * __split_huge_page_refcount side enforces write memory barriers
116 * between clearing PageTail and before the head page
117 * can be freed and reallocated.
120 if (likely(PageTail(page))) {
122 * __split_huge_page_refcount cannot race
123 * here, see the comment above this function.
125 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
126 VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
127 if (put_page_testzero(page_head)) {
129 * If this is the tail of a slab THP page,
130 * the tail pin must not be the last reference
131 * held on the page, because the PG_slab cannot
132 * be cleared before all tail pins (which skips
133 * the _mapcount tail refcounting) have been
136 * If this is the tail of a hugetlbfs page,
137 * the tail pin may be the last reference on
138 * the page instead, because PageHeadHuge will
139 * not go away until the compound page enters
140 * the buddy allocator.
142 VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
143 __put_compound_page(page_head);
147 * __split_huge_page_refcount run before us,
148 * @page was a THP tail. The split @page_head
149 * has been freed and reallocated as slab or
150 * hugetlbfs page of smaller order (only
151 * possible if reallocated as slab on x86).
153 if (put_page_testzero(page))
154 __put_single_page(page);
157 static __always_inline
158 void put_refcounted_compound_page(struct page *page_head, struct page *page)
160 if (likely(page != page_head && get_page_unless_zero(page_head))) {
164 * @page_head wasn't a dangling pointer but it may not
165 * be a head page anymore by the time we obtain the
166 * lock. That is ok as long as it can't be freed from
169 flags = compound_lock_irqsave(page_head);
170 if (unlikely(!PageTail(page))) {
171 /* __split_huge_page_refcount run before us */
172 compound_unlock_irqrestore(page_head, flags);
173 if (put_page_testzero(page_head)) {
175 * The @page_head may have been freed
176 * and reallocated as a compound page
177 * of smaller order and then freed
178 * again. All we know is that it
179 * cannot have become: a THP page, a
180 * compound page of higher order, a
181 * tail page. That is because we
182 * still hold the refcount of the
183 * split THP tail and page_head was
184 * the THP head before the split.
186 if (PageHead(page_head))
187 __put_compound_page(page_head);
189 __put_single_page(page_head);
192 if (put_page_testzero(page))
193 __put_single_page(page);
196 VM_BUG_ON_PAGE(page_head != page->first_page, page);
198 * We can release the refcount taken by
199 * get_page_unless_zero() now that
200 * __split_huge_page_refcount() is blocked on the
203 if (put_page_testzero(page_head))
204 VM_BUG_ON_PAGE(1, page_head);
205 /* __split_huge_page_refcount will wait now */
206 VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
207 atomic_dec(&page->_mapcount);
208 VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
209 VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
210 compound_unlock_irqrestore(page_head, flags);
212 if (put_page_testzero(page_head)) {
213 if (PageHead(page_head))
214 __put_compound_page(page_head);
216 __put_single_page(page_head);
219 /* @page_head is a dangling pointer */
220 VM_BUG_ON_PAGE(PageTail(page), page);
225 static void put_compound_page(struct page *page)
227 struct page *page_head;
230 * We see the PageCompound set and PageTail not set, so @page maybe:
231 * 1. hugetlbfs head page, or
234 if (likely(!PageTail(page))) {
235 if (put_page_testzero(page)) {
237 * By the time all refcounts have been released
238 * split_huge_page cannot run anymore from under us.
241 __put_compound_page(page);
243 __put_single_page(page);
249 * We see the PageCompound set and PageTail set, so @page maybe:
250 * 1. a tail hugetlbfs page, or
251 * 2. a tail THP page, or
252 * 3. a split THP page.
254 * Case 3 is possible, as we may race with
255 * __split_huge_page_refcount tearing down a THP page.
257 page_head = compound_head_by_tail(page);
258 if (!__compound_tail_refcounted(page_head))
259 put_unrefcounted_compound_page(page_head, page);
261 put_refcounted_compound_page(page_head, page);
264 void put_page(struct page *page)
266 if (unlikely(PageCompound(page)))
267 put_compound_page(page);
268 else if (put_page_testzero(page))
269 __put_single_page(page);
271 EXPORT_SYMBOL(put_page);
274 * This function is exported but must not be called by anything other
275 * than get_page(). It implements the slow path of get_page().
277 bool __get_page_tail(struct page *page)
280 * This takes care of get_page() if run on a tail page
281 * returned by one of the get_user_pages/follow_page variants.
282 * get_user_pages/follow_page itself doesn't need the compound
283 * lock because it runs __get_page_tail_foll() under the
284 * proper PT lock that already serializes against
289 struct page *page_head = compound_head(page);
291 /* Ref to put_compound_page() comment. */
292 if (!__compound_tail_refcounted(page_head)) {
294 if (likely(PageTail(page))) {
296 * This is a hugetlbfs page or a slab
297 * page. __split_huge_page_refcount
300 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
301 __get_page_tail_foll(page, true);
305 * __split_huge_page_refcount run
306 * before us, "page" was a THP
307 * tail. The split page_head has been
308 * freed and reallocated as slab or
309 * hugetlbfs page of smaller order
310 * (only possible if reallocated as
318 if (likely(page != page_head && get_page_unless_zero(page_head))) {
320 * page_head wasn't a dangling pointer but it
321 * may not be a head page anymore by the time
322 * we obtain the lock. That is ok as long as it
323 * can't be freed from under us.
325 flags = compound_lock_irqsave(page_head);
326 /* here __split_huge_page_refcount won't run anymore */
327 if (likely(PageTail(page))) {
328 __get_page_tail_foll(page, false);
331 compound_unlock_irqrestore(page_head, flags);
337 EXPORT_SYMBOL(__get_page_tail);
340 * put_pages_list() - release a list of pages
341 * @pages: list of pages threaded on page->lru
343 * Release a list of pages which are strung together on page.lru. Currently
344 * used by read_cache_pages() and related error recovery code.
346 void put_pages_list(struct list_head *pages)
348 while (!list_empty(pages)) {
351 victim = list_entry(pages->prev, struct page, lru);
352 list_del(&victim->lru);
353 page_cache_release(victim);
356 EXPORT_SYMBOL(put_pages_list);
359 * get_kernel_pages() - pin kernel pages in memory
360 * @kiov: An array of struct kvec structures
361 * @nr_segs: number of segments to pin
362 * @write: pinning for read/write, currently ignored
363 * @pages: array that receives pointers to the pages pinned.
364 * Should be at least nr_segs long.
366 * Returns number of pages pinned. This may be fewer than the number
367 * requested. If nr_pages is 0 or negative, returns 0. If no pages
368 * were pinned, returns -errno. Each page returned must be released
369 * with a put_page() call when it is finished with.
371 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
376 for (seg = 0; seg < nr_segs; seg++) {
377 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
380 pages[seg] = kmap_to_page(kiov[seg].iov_base);
381 page_cache_get(pages[seg]);
386 EXPORT_SYMBOL_GPL(get_kernel_pages);
389 * get_kernel_page() - pin a kernel page in memory
390 * @start: starting kernel address
391 * @write: pinning for read/write, currently ignored
392 * @pages: array that receives pointer to the page pinned.
393 * Must be at least nr_segs long.
395 * Returns 1 if page is pinned. If the page was not pinned, returns
396 * -errno. The page returned must be released with a put_page() call
397 * when it is finished with.
399 int get_kernel_page(unsigned long start, int write, struct page **pages)
401 const struct kvec kiov = {
402 .iov_base = (void *)start,
406 return get_kernel_pages(&kiov, 1, write, pages);
408 EXPORT_SYMBOL_GPL(get_kernel_page);
410 static void pagevec_lru_move_fn(struct pagevec *pvec,
411 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
415 struct zone *zone = NULL;
416 struct lruvec *lruvec;
417 unsigned long flags = 0;
419 for (i = 0; i < pagevec_count(pvec); i++) {
420 struct page *page = pvec->pages[i];
421 struct zone *pagezone = page_zone(page);
423 if (pagezone != zone) {
425 spin_unlock_irqrestore(&zone->lru_lock, flags);
427 spin_lock_irqsave(&zone->lru_lock, flags);
430 lruvec = mem_cgroup_page_lruvec(page, zone);
431 (*move_fn)(page, lruvec, arg);
434 spin_unlock_irqrestore(&zone->lru_lock, flags);
435 release_pages(pvec->pages, pvec->nr, pvec->cold);
436 pagevec_reinit(pvec);
439 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
444 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
445 enum lru_list lru = page_lru_base_type(page);
446 list_move_tail(&page->lru, &lruvec->lists[lru]);
452 * pagevec_move_tail() must be called with IRQ disabled.
453 * Otherwise this may cause nasty races.
455 static void pagevec_move_tail(struct pagevec *pvec)
459 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
460 __count_vm_events(PGROTATED, pgmoved);
464 * Writeback is about to end against a page which has been marked for immediate
465 * reclaim. If it still appears to be reclaimable, move it to the tail of the
468 void rotate_reclaimable_page(struct page *page)
470 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
471 !PageUnevictable(page) && PageLRU(page)) {
472 struct pagevec *pvec;
475 page_cache_get(page);
476 local_irq_save(flags);
477 pvec = this_cpu_ptr(&lru_rotate_pvecs);
478 if (!pagevec_add(pvec, page))
479 pagevec_move_tail(pvec);
480 local_irq_restore(flags);
484 static void update_page_reclaim_stat(struct lruvec *lruvec,
485 int file, int rotated)
487 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
489 reclaim_stat->recent_scanned[file]++;
491 reclaim_stat->recent_rotated[file]++;
494 static void __activate_page(struct page *page, struct lruvec *lruvec,
497 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
498 int file = page_is_file_cache(page);
499 int lru = page_lru_base_type(page);
501 del_page_from_lru_list(page, lruvec, lru);
504 add_page_to_lru_list(page, lruvec, lru);
505 trace_mm_lru_activate(page);
507 __count_vm_event(PGACTIVATE);
508 update_page_reclaim_stat(lruvec, file, 1);
513 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
515 static void activate_page_drain(int cpu)
517 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
519 if (pagevec_count(pvec))
520 pagevec_lru_move_fn(pvec, __activate_page, NULL);
523 static bool need_activate_page_drain(int cpu)
525 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
528 void activate_page(struct page *page)
530 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
531 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
533 page_cache_get(page);
534 if (!pagevec_add(pvec, page))
535 pagevec_lru_move_fn(pvec, __activate_page, NULL);
536 put_cpu_var(activate_page_pvecs);
541 static inline void activate_page_drain(int cpu)
545 static bool need_activate_page_drain(int cpu)
550 void activate_page(struct page *page)
552 struct zone *zone = page_zone(page);
554 spin_lock_irq(&zone->lru_lock);
555 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
556 spin_unlock_irq(&zone->lru_lock);
560 static void __lru_cache_activate_page(struct page *page)
562 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
566 * Search backwards on the optimistic assumption that the page being
567 * activated has just been added to this pagevec. Note that only
568 * the local pagevec is examined as a !PageLRU page could be in the
569 * process of being released, reclaimed, migrated or on a remote
570 * pagevec that is currently being drained. Furthermore, marking
571 * a remote pagevec's page PageActive potentially hits a race where
572 * a page is marked PageActive just after it is added to the inactive
573 * list causing accounting errors and BUG_ON checks to trigger.
575 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
576 struct page *pagevec_page = pvec->pages[i];
578 if (pagevec_page == page) {
584 put_cpu_var(lru_add_pvec);
588 * Mark a page as having seen activity.
590 * inactive,unreferenced -> inactive,referenced
591 * inactive,referenced -> active,unreferenced
592 * active,unreferenced -> active,referenced
594 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
595 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
597 void mark_page_accessed(struct page *page)
599 if (!PageActive(page) && !PageUnevictable(page) &&
600 PageReferenced(page)) {
603 * If the page is on the LRU, queue it for activation via
604 * activate_page_pvecs. Otherwise, assume the page is on a
605 * pagevec, mark it active and it'll be moved to the active
606 * LRU on the next drain.
611 __lru_cache_activate_page(page);
612 ClearPageReferenced(page);
613 if (page_is_file_cache(page))
614 workingset_activation(page);
615 } else if (!PageReferenced(page)) {
616 SetPageReferenced(page);
619 EXPORT_SYMBOL(mark_page_accessed);
621 static void __lru_cache_add(struct page *page)
623 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
625 page_cache_get(page);
626 if (!pagevec_space(pvec))
627 __pagevec_lru_add(pvec);
628 pagevec_add(pvec, page);
629 put_cpu_var(lru_add_pvec);
633 * lru_cache_add: add a page to the page lists
634 * @page: the page to add
636 void lru_cache_add_anon(struct page *page)
638 if (PageActive(page))
639 ClearPageActive(page);
640 __lru_cache_add(page);
643 void lru_cache_add_file(struct page *page)
645 if (PageActive(page))
646 ClearPageActive(page);
647 __lru_cache_add(page);
649 EXPORT_SYMBOL(lru_cache_add_file);
652 * lru_cache_add - add a page to a page list
653 * @page: the page to be added to the LRU.
655 * Queue the page for addition to the LRU via pagevec. The decision on whether
656 * to add the page to the [in]active [file|anon] list is deferred until the
657 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
658 * have the page added to the active list using mark_page_accessed().
660 void lru_cache_add(struct page *page)
662 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
663 VM_BUG_ON_PAGE(PageLRU(page), page);
664 __lru_cache_add(page);
668 * add_page_to_unevictable_list - add a page to the unevictable list
669 * @page: the page to be added to the unevictable list
671 * Add page directly to its zone's unevictable list. To avoid races with
672 * tasks that might be making the page evictable, through eg. munlock,
673 * munmap or exit, while it's not on the lru, we want to add the page
674 * while it's locked or otherwise "invisible" to other tasks. This is
675 * difficult to do when using the pagevec cache, so bypass that.
677 void add_page_to_unevictable_list(struct page *page)
679 struct zone *zone = page_zone(page);
680 struct lruvec *lruvec;
682 spin_lock_irq(&zone->lru_lock);
683 lruvec = mem_cgroup_page_lruvec(page, zone);
684 ClearPageActive(page);
685 SetPageUnevictable(page);
687 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
688 spin_unlock_irq(&zone->lru_lock);
692 * lru_cache_add_active_or_unevictable
693 * @page: the page to be added to LRU
694 * @vma: vma in which page is mapped for determining reclaimability
696 * Place @page on the active or unevictable LRU list, depending on its
697 * evictability. Note that if the page is not evictable, it goes
698 * directly back onto it's zone's unevictable list, it does NOT use a
701 void lru_cache_add_active_or_unevictable(struct page *page,
702 struct vm_area_struct *vma)
704 VM_BUG_ON_PAGE(PageLRU(page), page);
706 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
712 if (!TestSetPageMlocked(page)) {
714 * We use the irq-unsafe __mod_zone_page_stat because this
715 * counter is not modified from interrupt context, and the pte
716 * lock is held(spinlock), which implies preemption disabled.
718 __mod_zone_page_state(page_zone(page), NR_MLOCK,
719 hpage_nr_pages(page));
720 count_vm_event(UNEVICTABLE_PGMLOCKED);
722 add_page_to_unevictable_list(page);
726 * If the page can not be invalidated, it is moved to the
727 * inactive list to speed up its reclaim. It is moved to the
728 * head of the list, rather than the tail, to give the flusher
729 * threads some time to write it out, as this is much more
730 * effective than the single-page writeout from reclaim.
732 * If the page isn't page_mapped and dirty/writeback, the page
733 * could reclaim asap using PG_reclaim.
735 * 1. active, mapped page -> none
736 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
737 * 3. inactive, mapped page -> none
738 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
739 * 5. inactive, clean -> inactive, tail
742 * In 4, why it moves inactive's head, the VM expects the page would
743 * be write it out by flusher threads as this is much more effective
744 * than the single-page writeout from reclaim.
746 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
755 if (PageUnevictable(page))
758 /* Some processes are using the page */
759 if (page_mapped(page))
762 active = PageActive(page);
763 file = page_is_file_cache(page);
764 lru = page_lru_base_type(page);
766 del_page_from_lru_list(page, lruvec, lru + active);
767 ClearPageActive(page);
768 ClearPageReferenced(page);
769 add_page_to_lru_list(page, lruvec, lru);
771 if (PageWriteback(page) || PageDirty(page)) {
773 * PG_reclaim could be raced with end_page_writeback
774 * It can make readahead confusing. But race window
775 * is _really_ small and it's non-critical problem.
777 SetPageReclaim(page);
780 * The page's writeback ends up during pagevec
781 * We moves tha page into tail of inactive.
783 list_move_tail(&page->lru, &lruvec->lists[lru]);
784 __count_vm_event(PGROTATED);
788 __count_vm_event(PGDEACTIVATE);
789 update_page_reclaim_stat(lruvec, file, 0);
793 * Drain pages out of the cpu's pagevecs.
794 * Either "cpu" is the current CPU, and preemption has already been
795 * disabled; or "cpu" is being hot-unplugged, and is already dead.
797 void lru_add_drain_cpu(int cpu)
799 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
801 if (pagevec_count(pvec))
802 __pagevec_lru_add(pvec);
804 pvec = &per_cpu(lru_rotate_pvecs, cpu);
805 if (pagevec_count(pvec)) {
808 /* No harm done if a racing interrupt already did this */
809 local_irq_save(flags);
810 pagevec_move_tail(pvec);
811 local_irq_restore(flags);
814 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
815 if (pagevec_count(pvec))
816 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
818 activate_page_drain(cpu);
822 * deactivate_page - forcefully deactivate a page
823 * @page: page to deactivate
825 * This function hints the VM that @page is a good reclaim candidate,
826 * for example if its invalidation fails due to the page being dirty
827 * or under writeback.
829 void deactivate_page(struct page *page)
832 * In a workload with many unevictable page such as mprotect, unevictable
833 * page deactivation for accelerating reclaim is pointless.
835 if (PageUnevictable(page))
838 if (likely(get_page_unless_zero(page))) {
839 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
841 if (!pagevec_add(pvec, page))
842 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
843 put_cpu_var(lru_deactivate_pvecs);
847 void lru_add_drain(void)
849 lru_add_drain_cpu(get_cpu());
853 static void lru_add_drain_per_cpu(struct work_struct *dummy)
858 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
860 void lru_add_drain_all(void)
862 static DEFINE_MUTEX(lock);
863 static struct cpumask has_work;
868 cpumask_clear(&has_work);
870 for_each_online_cpu(cpu) {
871 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
873 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
874 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
875 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
876 need_activate_page_drain(cpu)) {
877 INIT_WORK(work, lru_add_drain_per_cpu);
878 schedule_work_on(cpu, work);
879 cpumask_set_cpu(cpu, &has_work);
883 for_each_cpu(cpu, &has_work)
884 flush_work(&per_cpu(lru_add_drain_work, cpu));
891 * release_pages - batched page_cache_release()
892 * @pages: array of pages to release
893 * @nr: number of pages
894 * @cold: whether the pages are cache cold
896 * Decrement the reference count on all the pages in @pages. If it
897 * fell to zero, remove the page from the LRU and free it.
899 void release_pages(struct page **pages, int nr, bool cold)
902 LIST_HEAD(pages_to_free);
903 struct zone *zone = NULL;
904 struct lruvec *lruvec;
905 unsigned long uninitialized_var(flags);
906 unsigned int uninitialized_var(lock_batch);
908 for (i = 0; i < nr; i++) {
909 struct page *page = pages[i];
911 if (unlikely(PageCompound(page))) {
913 spin_unlock_irqrestore(&zone->lru_lock, flags);
916 put_compound_page(page);
921 * Make sure the IRQ-safe lock-holding time does not get
922 * excessive with a continuous string of pages from the
923 * same zone. The lock is held only if zone != NULL.
925 if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
926 spin_unlock_irqrestore(&zone->lru_lock, flags);
930 if (!put_page_testzero(page))
934 struct zone *pagezone = page_zone(page);
936 if (pagezone != zone) {
938 spin_unlock_irqrestore(&zone->lru_lock,
942 spin_lock_irqsave(&zone->lru_lock, flags);
945 lruvec = mem_cgroup_page_lruvec(page, zone);
946 VM_BUG_ON_PAGE(!PageLRU(page), page);
947 __ClearPageLRU(page);
948 del_page_from_lru_list(page, lruvec, page_off_lru(page));
951 /* Clear Active bit in case of parallel mark_page_accessed */
952 __ClearPageActive(page);
954 list_add(&page->lru, &pages_to_free);
957 spin_unlock_irqrestore(&zone->lru_lock, flags);
959 mem_cgroup_uncharge_list(&pages_to_free);
960 free_hot_cold_page_list(&pages_to_free, cold);
962 EXPORT_SYMBOL(release_pages);
965 * The pages which we're about to release may be in the deferred lru-addition
966 * queues. That would prevent them from really being freed right now. That's
967 * OK from a correctness point of view but is inefficient - those pages may be
968 * cache-warm and we want to give them back to the page allocator ASAP.
970 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
971 * and __pagevec_lru_add_active() call release_pages() directly to avoid
974 void __pagevec_release(struct pagevec *pvec)
977 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
978 pagevec_reinit(pvec);
980 EXPORT_SYMBOL(__pagevec_release);
982 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
983 /* used by __split_huge_page_refcount() */
984 void lru_add_page_tail(struct page *page, struct page *page_tail,
985 struct lruvec *lruvec, struct list_head *list)
989 VM_BUG_ON_PAGE(!PageHead(page), page);
990 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
991 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
992 VM_BUG_ON(NR_CPUS != 1 &&
993 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
996 SetPageLRU(page_tail);
998 if (likely(PageLRU(page)))
999 list_add_tail(&page_tail->lru, &page->lru);
1001 /* page reclaim is reclaiming a huge page */
1002 get_page(page_tail);
1003 list_add_tail(&page_tail->lru, list);
1005 struct list_head *list_head;
1007 * Head page has not yet been counted, as an hpage,
1008 * so we must account for each subpage individually.
1010 * Use the standard add function to put page_tail on the list,
1011 * but then correct its position so they all end up in order.
1013 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
1014 list_head = page_tail->lru.prev;
1015 list_move_tail(&page_tail->lru, list_head);
1018 if (!PageUnevictable(page))
1019 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
1021 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1023 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
1026 int file = page_is_file_cache(page);
1027 int active = PageActive(page);
1028 enum lru_list lru = page_lru(page);
1030 VM_BUG_ON_PAGE(PageLRU(page), page);
1033 add_page_to_lru_list(page, lruvec, lru);
1034 update_page_reclaim_stat(lruvec, file, active);
1035 trace_mm_lru_insertion(page, lru);
1039 * Add the passed pages to the LRU, then drop the caller's refcount
1040 * on them. Reinitialises the caller's pagevec.
1042 void __pagevec_lru_add(struct pagevec *pvec)
1044 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
1046 EXPORT_SYMBOL(__pagevec_lru_add);
1049 * pagevec_lookup_entries - gang pagecache lookup
1050 * @pvec: Where the resulting entries are placed
1051 * @mapping: The address_space to search
1052 * @start: The starting entry index
1053 * @nr_entries: The maximum number of entries
1054 * @indices: The cache indices corresponding to the entries in @pvec
1056 * pagevec_lookup_entries() will search for and return a group of up
1057 * to @nr_entries pages and shadow entries in the mapping. All
1058 * entries are placed in @pvec. pagevec_lookup_entries() takes a
1059 * reference against actual pages in @pvec.
1061 * The search returns a group of mapping-contiguous entries with
1062 * ascending indexes. There may be holes in the indices due to
1063 * not-present entries.
1065 * pagevec_lookup_entries() returns the number of entries which were
1068 unsigned pagevec_lookup_entries(struct pagevec *pvec,
1069 struct address_space *mapping,
1070 pgoff_t start, unsigned nr_pages,
1073 pvec->nr = find_get_entries(mapping, start, nr_pages,
1074 pvec->pages, indices);
1075 return pagevec_count(pvec);
1079 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1080 * @pvec: The pagevec to prune
1082 * pagevec_lookup_entries() fills both pages and exceptional radix
1083 * tree entries into the pagevec. This function prunes all
1084 * exceptionals from @pvec without leaving holes, so that it can be
1085 * passed on to page-only pagevec operations.
1087 void pagevec_remove_exceptionals(struct pagevec *pvec)
1091 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1092 struct page *page = pvec->pages[i];
1093 if (!radix_tree_exceptional_entry(page))
1094 pvec->pages[j++] = page;
1100 * pagevec_lookup - gang pagecache lookup
1101 * @pvec: Where the resulting pages are placed
1102 * @mapping: The address_space to search
1103 * @start: The starting page index
1104 * @nr_pages: The maximum number of pages
1106 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
1107 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
1108 * reference against the pages in @pvec.
1110 * The search returns a group of mapping-contiguous pages with ascending
1111 * indexes. There may be holes in the indices due to not-present pages.
1113 * pagevec_lookup() returns the number of pages which were found.
1115 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
1116 pgoff_t start, unsigned nr_pages)
1118 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
1119 return pagevec_count(pvec);
1121 EXPORT_SYMBOL(pagevec_lookup);
1123 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
1124 pgoff_t *index, int tag, unsigned nr_pages)
1126 pvec->nr = find_get_pages_tag(mapping, index, tag,
1127 nr_pages, pvec->pages);
1128 return pagevec_count(pvec);
1130 EXPORT_SYMBOL(pagevec_lookup_tag);
1133 * Perform any setup for the swap system
1135 void __init swap_setup(void)
1137 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
1141 if (bdi_init(swapper_spaces[0].backing_dev_info))
1142 panic("Failed to init swap bdi");
1143 for (i = 0; i < MAX_SWAPFILES; i++) {
1144 spin_lock_init(&swapper_spaces[i].tree_lock);
1145 INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
1149 /* Use a smaller cluster for small-memory machines */
1155 * Right now other parts of the system means that we
1156 * _really_ don't want to cluster much more