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>
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/pagemap.h>
41 /* How many pages do we try to swap or page in/out together? */
44 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
45 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
46 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
49 * This path almost never happens for VM activity - pages are normally
50 * freed via pagevecs. But it gets used by networking.
52 static void __page_cache_release(struct page *page)
55 struct zone *zone = page_zone(page);
56 struct lruvec *lruvec;
59 spin_lock_irqsave(&zone->lru_lock, flags);
60 lruvec = mem_cgroup_page_lruvec(page, zone);
61 VM_BUG_ON(!PageLRU(page));
63 del_page_from_lru_list(page, lruvec, page_off_lru(page));
64 spin_unlock_irqrestore(&zone->lru_lock, flags);
68 static void __put_single_page(struct page *page)
70 __page_cache_release(page);
71 free_hot_cold_page(page, 0);
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);
83 static void put_compound_page(struct page *page)
85 if (unlikely(PageTail(page))) {
86 /* __split_huge_page_refcount can run under us */
87 struct page *page_head = compound_trans_head(page);
90 * THP can not break up slab pages so avoid taking
91 * compound_lock(). Slab performs non-atomic bit ops
92 * on page->flags for better performance. In
93 * particular slab_unlock() in slub used to be a hot
94 * path. It is still hot on arches that do not support
95 * this_cpu_cmpxchg_double().
97 * If "page" is part of a slab or hugetlbfs page it
98 * cannot be splitted and the head page cannot change
99 * from under us. And if "page" is part of a THP page
100 * under splitting, if the head page pointed by the
101 * THP tail isn't a THP head anymore, we'll find
102 * PageTail clear after smp_rmb() and we'll treat it
105 if (PageSlab(page_head) || PageHeadHuge(page_head)) {
107 * If "page" is a THP tail, we must read the tail page
108 * flags after the head page flags. The
109 * split_huge_page side enforces write memory
110 * barriers between clearing PageTail and before the
111 * head page can be freed and reallocated.
114 if (likely(PageTail(page))) {
116 * __split_huge_page_refcount
119 VM_BUG_ON(!PageHead(page_head));
120 VM_BUG_ON(page_mapcount(page) <= 0);
121 atomic_dec(&page->_mapcount);
122 if (put_page_testzero(page_head))
123 __put_compound_page(page_head);
127 * __split_huge_page_refcount
128 * run before us, "page" was a
129 * THP tail. The split
130 * page_head has been freed
131 * and reallocated as slab or
132 * hugetlbfs page of smaller
133 * order (only possible if
134 * reallocated as slab on
140 if (likely(page != page_head &&
141 get_page_unless_zero(page_head))) {
145 * page_head wasn't a dangling pointer but it
146 * may not be a head page anymore by the time
147 * we obtain the lock. That is ok as long as it
148 * can't be freed from under us.
150 flags = compound_lock_irqsave(page_head);
151 if (unlikely(!PageTail(page))) {
152 /* __split_huge_page_refcount run before us */
153 compound_unlock_irqrestore(page_head, flags);
154 if (put_page_testzero(page_head)) {
156 * The head page may have been
157 * freed and reallocated as a
158 * compound page of smaller
159 * order and then freed again.
160 * All we know is that it
161 * cannot have become: a THP
162 * page, a compound page of
163 * higher order, a tail page.
164 * That is because we still
165 * hold the refcount of the
167 * page_head was the THP head
170 if (PageHead(page_head))
171 __put_compound_page(page_head);
173 __put_single_page(page_head);
176 if (put_page_testzero(page))
177 __put_single_page(page);
180 VM_BUG_ON(page_head != page->first_page);
182 * We can release the refcount taken by
183 * get_page_unless_zero() now that
184 * __split_huge_page_refcount() is blocked on
187 if (put_page_testzero(page_head))
189 /* __split_huge_page_refcount will wait now */
190 VM_BUG_ON(page_mapcount(page) <= 0);
191 atomic_dec(&page->_mapcount);
192 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
193 VM_BUG_ON(atomic_read(&page->_count) != 0);
194 compound_unlock_irqrestore(page_head, flags);
196 if (put_page_testzero(page_head)) {
197 if (PageHead(page_head))
198 __put_compound_page(page_head);
200 __put_single_page(page_head);
203 /* page_head is a dangling pointer */
204 VM_BUG_ON(PageTail(page));
207 } else if (put_page_testzero(page)) {
209 __put_compound_page(page);
211 __put_single_page(page);
215 void put_page(struct page *page)
217 if (unlikely(PageCompound(page)))
218 put_compound_page(page);
219 else if (put_page_testzero(page))
220 __put_single_page(page);
222 EXPORT_SYMBOL(put_page);
225 * This function is exported but must not be called by anything other
226 * than get_page(). It implements the slow path of get_page().
228 bool __get_page_tail(struct page *page)
231 * This takes care of get_page() if run on a tail page
232 * returned by one of the get_user_pages/follow_page variants.
233 * get_user_pages/follow_page itself doesn't need the compound
234 * lock because it runs __get_page_tail_foll() under the
235 * proper PT lock that already serializes against
240 struct page *page_head = compound_trans_head(page);
242 /* Ref to put_compound_page() comment. */
243 if (PageSlab(page_head) || PageHeadHuge(page_head)) {
245 if (likely(PageTail(page))) {
247 * This is a hugetlbfs page or a slab
248 * page. __split_huge_page_refcount
251 VM_BUG_ON(!PageHead(page_head));
252 __get_page_tail_foll(page, true);
256 * __split_huge_page_refcount run
257 * before us, "page" was a THP
258 * tail. The split page_head has been
259 * freed and reallocated as slab or
260 * hugetlbfs page of smaller order
261 * (only possible if reallocated as
269 if (likely(page != page_head && get_page_unless_zero(page_head))) {
271 * page_head wasn't a dangling pointer but it
272 * may not be a head page anymore by the time
273 * we obtain the lock. That is ok as long as it
274 * can't be freed from under us.
276 flags = compound_lock_irqsave(page_head);
277 /* here __split_huge_page_refcount won't run anymore */
278 if (likely(PageTail(page))) {
279 __get_page_tail_foll(page, false);
282 compound_unlock_irqrestore(page_head, flags);
288 EXPORT_SYMBOL(__get_page_tail);
291 * put_pages_list() - release a list of pages
292 * @pages: list of pages threaded on page->lru
294 * Release a list of pages which are strung together on page.lru. Currently
295 * used by read_cache_pages() and related error recovery code.
297 void put_pages_list(struct list_head *pages)
299 while (!list_empty(pages)) {
302 victim = list_entry(pages->prev, struct page, lru);
303 list_del(&victim->lru);
304 page_cache_release(victim);
307 EXPORT_SYMBOL(put_pages_list);
310 * get_kernel_pages() - pin kernel pages in memory
311 * @kiov: An array of struct kvec structures
312 * @nr_segs: number of segments to pin
313 * @write: pinning for read/write, currently ignored
314 * @pages: array that receives pointers to the pages pinned.
315 * Should be at least nr_segs long.
317 * Returns number of pages pinned. This may be fewer than the number
318 * requested. If nr_pages is 0 or negative, returns 0. If no pages
319 * were pinned, returns -errno. Each page returned must be released
320 * with a put_page() call when it is finished with.
322 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
327 for (seg = 0; seg < nr_segs; seg++) {
328 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
331 pages[seg] = kmap_to_page(kiov[seg].iov_base);
332 page_cache_get(pages[seg]);
337 EXPORT_SYMBOL_GPL(get_kernel_pages);
340 * get_kernel_page() - pin a kernel page in memory
341 * @start: starting kernel address
342 * @write: pinning for read/write, currently ignored
343 * @pages: array that receives pointer to the page pinned.
344 * Must be at least nr_segs long.
346 * Returns 1 if page is pinned. If the page was not pinned, returns
347 * -errno. The page returned must be released with a put_page() call
348 * when it is finished with.
350 int get_kernel_page(unsigned long start, int write, struct page **pages)
352 const struct kvec kiov = {
353 .iov_base = (void *)start,
357 return get_kernel_pages(&kiov, 1, write, pages);
359 EXPORT_SYMBOL_GPL(get_kernel_page);
361 static void pagevec_lru_move_fn(struct pagevec *pvec,
362 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
366 struct zone *zone = NULL;
367 struct lruvec *lruvec;
368 unsigned long flags = 0;
370 for (i = 0; i < pagevec_count(pvec); i++) {
371 struct page *page = pvec->pages[i];
372 struct zone *pagezone = page_zone(page);
374 if (pagezone != zone) {
376 spin_unlock_irqrestore(&zone->lru_lock, flags);
378 spin_lock_irqsave(&zone->lru_lock, flags);
381 lruvec = mem_cgroup_page_lruvec(page, zone);
382 (*move_fn)(page, lruvec, arg);
385 spin_unlock_irqrestore(&zone->lru_lock, flags);
386 release_pages(pvec->pages, pvec->nr, pvec->cold);
387 pagevec_reinit(pvec);
390 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
395 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
396 enum lru_list lru = page_lru_base_type(page);
397 list_move_tail(&page->lru, &lruvec->lists[lru]);
403 * pagevec_move_tail() must be called with IRQ disabled.
404 * Otherwise this may cause nasty races.
406 static void pagevec_move_tail(struct pagevec *pvec)
410 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
411 __count_vm_events(PGROTATED, pgmoved);
415 * Writeback is about to end against a page which has been marked for immediate
416 * reclaim. If it still appears to be reclaimable, move it to the tail of the
419 void rotate_reclaimable_page(struct page *page)
421 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
422 !PageUnevictable(page) && PageLRU(page)) {
423 struct pagevec *pvec;
426 page_cache_get(page);
427 local_irq_save(flags);
428 pvec = &__get_cpu_var(lru_rotate_pvecs);
429 if (!pagevec_add(pvec, page))
430 pagevec_move_tail(pvec);
431 local_irq_restore(flags);
435 static void update_page_reclaim_stat(struct lruvec *lruvec,
436 int file, int rotated)
438 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
440 reclaim_stat->recent_scanned[file]++;
442 reclaim_stat->recent_rotated[file]++;
445 static void __activate_page(struct page *page, struct lruvec *lruvec,
448 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
449 int file = page_is_file_cache(page);
450 int lru = page_lru_base_type(page);
452 del_page_from_lru_list(page, lruvec, lru);
455 add_page_to_lru_list(page, lruvec, lru);
456 trace_mm_lru_activate(page, page_to_pfn(page));
458 __count_vm_event(PGACTIVATE);
459 update_page_reclaim_stat(lruvec, file, 1);
464 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
466 static void activate_page_drain(int cpu)
468 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
470 if (pagevec_count(pvec))
471 pagevec_lru_move_fn(pvec, __activate_page, NULL);
474 static bool need_activate_page_drain(int cpu)
476 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
479 void activate_page(struct page *page)
481 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
482 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
484 page_cache_get(page);
485 if (!pagevec_add(pvec, page))
486 pagevec_lru_move_fn(pvec, __activate_page, NULL);
487 put_cpu_var(activate_page_pvecs);
492 static inline void activate_page_drain(int cpu)
496 static bool need_activate_page_drain(int cpu)
501 void activate_page(struct page *page)
503 struct zone *zone = page_zone(page);
505 spin_lock_irq(&zone->lru_lock);
506 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
507 spin_unlock_irq(&zone->lru_lock);
511 static void __lru_cache_activate_page(struct page *page)
513 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
517 * Search backwards on the optimistic assumption that the page being
518 * activated has just been added to this pagevec. Note that only
519 * the local pagevec is examined as a !PageLRU page could be in the
520 * process of being released, reclaimed, migrated or on a remote
521 * pagevec that is currently being drained. Furthermore, marking
522 * a remote pagevec's page PageActive potentially hits a race where
523 * a page is marked PageActive just after it is added to the inactive
524 * list causing accounting errors and BUG_ON checks to trigger.
526 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
527 struct page *pagevec_page = pvec->pages[i];
529 if (pagevec_page == page) {
535 put_cpu_var(lru_add_pvec);
539 * Mark a page as having seen activity.
541 * inactive,unreferenced -> inactive,referenced
542 * inactive,referenced -> active,unreferenced
543 * active,unreferenced -> active,referenced
545 void mark_page_accessed(struct page *page)
547 if (!PageActive(page) && !PageUnevictable(page) &&
548 PageReferenced(page)) {
551 * If the page is on the LRU, queue it for activation via
552 * activate_page_pvecs. Otherwise, assume the page is on a
553 * pagevec, mark it active and it'll be moved to the active
554 * LRU on the next drain.
559 __lru_cache_activate_page(page);
560 ClearPageReferenced(page);
561 } else if (!PageReferenced(page)) {
562 SetPageReferenced(page);
565 EXPORT_SYMBOL(mark_page_accessed);
568 * Queue the page for addition to the LRU via pagevec. The decision on whether
569 * to add the page to the [in]active [file|anon] list is deferred until the
570 * pagevec is drained. This gives a chance for the caller of __lru_cache_add()
571 * have the page added to the active list using mark_page_accessed().
573 void __lru_cache_add(struct page *page)
575 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
577 page_cache_get(page);
578 if (!pagevec_space(pvec))
579 __pagevec_lru_add(pvec);
580 pagevec_add(pvec, page);
581 put_cpu_var(lru_add_pvec);
583 EXPORT_SYMBOL(__lru_cache_add);
586 * lru_cache_add - add a page to a page list
587 * @page: the page to be added to the LRU.
589 void lru_cache_add(struct page *page)
591 VM_BUG_ON(PageActive(page) && PageUnevictable(page));
592 VM_BUG_ON(PageLRU(page));
593 __lru_cache_add(page);
597 * add_page_to_unevictable_list - add a page to the unevictable list
598 * @page: the page to be added to the unevictable list
600 * Add page directly to its zone's unevictable list. To avoid races with
601 * tasks that might be making the page evictable, through eg. munlock,
602 * munmap or exit, while it's not on the lru, we want to add the page
603 * while it's locked or otherwise "invisible" to other tasks. This is
604 * difficult to do when using the pagevec cache, so bypass that.
606 void add_page_to_unevictable_list(struct page *page)
608 struct zone *zone = page_zone(page);
609 struct lruvec *lruvec;
611 spin_lock_irq(&zone->lru_lock);
612 lruvec = mem_cgroup_page_lruvec(page, zone);
613 ClearPageActive(page);
614 SetPageUnevictable(page);
616 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
617 spin_unlock_irq(&zone->lru_lock);
621 * If the page can not be invalidated, it is moved to the
622 * inactive list to speed up its reclaim. It is moved to the
623 * head of the list, rather than the tail, to give the flusher
624 * threads some time to write it out, as this is much more
625 * effective than the single-page writeout from reclaim.
627 * If the page isn't page_mapped and dirty/writeback, the page
628 * could reclaim asap using PG_reclaim.
630 * 1. active, mapped page -> none
631 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
632 * 3. inactive, mapped page -> none
633 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
634 * 5. inactive, clean -> inactive, tail
637 * In 4, why it moves inactive's head, the VM expects the page would
638 * be write it out by flusher threads as this is much more effective
639 * than the single-page writeout from reclaim.
641 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
650 if (PageUnevictable(page))
653 /* Some processes are using the page */
654 if (page_mapped(page))
657 active = PageActive(page);
658 file = page_is_file_cache(page);
659 lru = page_lru_base_type(page);
661 del_page_from_lru_list(page, lruvec, lru + active);
662 ClearPageActive(page);
663 ClearPageReferenced(page);
664 add_page_to_lru_list(page, lruvec, lru);
666 if (PageWriteback(page) || PageDirty(page)) {
668 * PG_reclaim could be raced with end_page_writeback
669 * It can make readahead confusing. But race window
670 * is _really_ small and it's non-critical problem.
672 SetPageReclaim(page);
675 * The page's writeback ends up during pagevec
676 * We moves tha page into tail of inactive.
678 list_move_tail(&page->lru, &lruvec->lists[lru]);
679 __count_vm_event(PGROTATED);
683 __count_vm_event(PGDEACTIVATE);
684 update_page_reclaim_stat(lruvec, file, 0);
688 * Drain pages out of the cpu's pagevecs.
689 * Either "cpu" is the current CPU, and preemption has already been
690 * disabled; or "cpu" is being hot-unplugged, and is already dead.
692 void lru_add_drain_cpu(int cpu)
694 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
696 if (pagevec_count(pvec))
697 __pagevec_lru_add(pvec);
699 pvec = &per_cpu(lru_rotate_pvecs, cpu);
700 if (pagevec_count(pvec)) {
703 /* No harm done if a racing interrupt already did this */
704 local_irq_save(flags);
705 pagevec_move_tail(pvec);
706 local_irq_restore(flags);
709 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
710 if (pagevec_count(pvec))
711 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
713 activate_page_drain(cpu);
717 * deactivate_page - forcefully deactivate a page
718 * @page: page to deactivate
720 * This function hints the VM that @page is a good reclaim candidate,
721 * for example if its invalidation fails due to the page being dirty
722 * or under writeback.
724 void deactivate_page(struct page *page)
727 * In a workload with many unevictable page such as mprotect, unevictable
728 * page deactivation for accelerating reclaim is pointless.
730 if (PageUnevictable(page))
733 if (likely(get_page_unless_zero(page))) {
734 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
736 if (!pagevec_add(pvec, page))
737 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
738 put_cpu_var(lru_deactivate_pvecs);
742 void lru_add_drain(void)
744 lru_add_drain_cpu(get_cpu());
748 static void lru_add_drain_per_cpu(struct work_struct *dummy)
753 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
755 void lru_add_drain_all(void)
757 static DEFINE_MUTEX(lock);
758 static struct cpumask has_work;
763 cpumask_clear(&has_work);
765 for_each_online_cpu(cpu) {
766 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
768 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
769 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
770 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
771 need_activate_page_drain(cpu)) {
772 INIT_WORK(work, lru_add_drain_per_cpu);
773 schedule_work_on(cpu, work);
774 cpumask_set_cpu(cpu, &has_work);
778 for_each_cpu(cpu, &has_work)
779 flush_work(&per_cpu(lru_add_drain_work, cpu));
786 * Batched page_cache_release(). Decrement the reference count on all the
787 * passed pages. If it fell to zero then remove the page from the LRU and
790 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
791 * for the remainder of the operation.
793 * The locking in this function is against shrink_inactive_list(): we recheck
794 * the page count inside the lock to see whether shrink_inactive_list()
795 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
798 void release_pages(struct page **pages, int nr, int cold)
801 LIST_HEAD(pages_to_free);
802 struct zone *zone = NULL;
803 struct lruvec *lruvec;
804 unsigned long uninitialized_var(flags);
806 for (i = 0; i < nr; i++) {
807 struct page *page = pages[i];
809 if (unlikely(PageCompound(page))) {
811 spin_unlock_irqrestore(&zone->lru_lock, flags);
814 put_compound_page(page);
818 if (!put_page_testzero(page))
822 struct zone *pagezone = page_zone(page);
824 if (pagezone != zone) {
826 spin_unlock_irqrestore(&zone->lru_lock,
829 spin_lock_irqsave(&zone->lru_lock, flags);
832 lruvec = mem_cgroup_page_lruvec(page, zone);
833 VM_BUG_ON(!PageLRU(page));
834 __ClearPageLRU(page);
835 del_page_from_lru_list(page, lruvec, page_off_lru(page));
838 /* Clear Active bit in case of parallel mark_page_accessed */
839 ClearPageActive(page);
841 list_add(&page->lru, &pages_to_free);
844 spin_unlock_irqrestore(&zone->lru_lock, flags);
846 free_hot_cold_page_list(&pages_to_free, cold);
848 EXPORT_SYMBOL(release_pages);
851 * The pages which we're about to release may be in the deferred lru-addition
852 * queues. That would prevent them from really being freed right now. That's
853 * OK from a correctness point of view but is inefficient - those pages may be
854 * cache-warm and we want to give them back to the page allocator ASAP.
856 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
857 * and __pagevec_lru_add_active() call release_pages() directly to avoid
860 void __pagevec_release(struct pagevec *pvec)
863 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
864 pagevec_reinit(pvec);
866 EXPORT_SYMBOL(__pagevec_release);
868 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
869 /* used by __split_huge_page_refcount() */
870 void lru_add_page_tail(struct page *page, struct page *page_tail,
871 struct lruvec *lruvec, struct list_head *list)
875 VM_BUG_ON(!PageHead(page));
876 VM_BUG_ON(PageCompound(page_tail));
877 VM_BUG_ON(PageLRU(page_tail));
878 VM_BUG_ON(NR_CPUS != 1 &&
879 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
882 SetPageLRU(page_tail);
884 if (likely(PageLRU(page)))
885 list_add_tail(&page_tail->lru, &page->lru);
887 /* page reclaim is reclaiming a huge page */
889 list_add_tail(&page_tail->lru, list);
891 struct list_head *list_head;
893 * Head page has not yet been counted, as an hpage,
894 * so we must account for each subpage individually.
896 * Use the standard add function to put page_tail on the list,
897 * but then correct its position so they all end up in order.
899 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
900 list_head = page_tail->lru.prev;
901 list_move_tail(&page_tail->lru, list_head);
904 if (!PageUnevictable(page))
905 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
907 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
909 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
912 int file = page_is_file_cache(page);
913 int active = PageActive(page);
914 enum lru_list lru = page_lru(page);
916 VM_BUG_ON(PageLRU(page));
919 add_page_to_lru_list(page, lruvec, lru);
920 update_page_reclaim_stat(lruvec, file, active);
921 trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page));
925 * Add the passed pages to the LRU, then drop the caller's refcount
926 * on them. Reinitialises the caller's pagevec.
928 void __pagevec_lru_add(struct pagevec *pvec)
930 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
932 EXPORT_SYMBOL(__pagevec_lru_add);
935 * pagevec_lookup - gang pagecache lookup
936 * @pvec: Where the resulting pages are placed
937 * @mapping: The address_space to search
938 * @start: The starting page index
939 * @nr_pages: The maximum number of pages
941 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
942 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
943 * reference against the pages in @pvec.
945 * The search returns a group of mapping-contiguous pages with ascending
946 * indexes. There may be holes in the indices due to not-present pages.
948 * pagevec_lookup() returns the number of pages which were found.
950 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
951 pgoff_t start, unsigned nr_pages)
953 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
954 return pagevec_count(pvec);
956 EXPORT_SYMBOL(pagevec_lookup);
958 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
959 pgoff_t *index, int tag, unsigned nr_pages)
961 pvec->nr = find_get_pages_tag(mapping, index, tag,
962 nr_pages, pvec->pages);
963 return pagevec_count(pvec);
965 EXPORT_SYMBOL(pagevec_lookup_tag);
968 * Perform any setup for the swap system
970 void __init swap_setup(void)
972 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
976 if (bdi_init(swapper_spaces[0].backing_dev_info))
977 panic("Failed to init swap bdi");
978 for (i = 0; i < MAX_SWAPFILES; i++) {
979 spin_lock_init(&swapper_spaces[i].tree_lock);
980 INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
984 /* Use a smaller cluster for small-memory machines */
990 * Right now other parts of the system means that we
991 * _really_ don't want to cluster much more