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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - mm/swap.c
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
);
67 static void __put_single_page(struct page
*page
)
69 __page_cache_release(page
);
70 free_hot_cold_page(page
, 0);
73 static void __put_compound_page(struct page
*page
)
75 compound_page_dtor
*dtor
;
77 __page_cache_release(page
);
78 dtor
= get_compound_page_dtor(page
);
82 static void put_compound_page(struct page
*page
)
84 struct page
*page_head
;
86 if (likely(!PageTail(page
))) {
87 if (put_page_testzero(page
)) {
89 * By the time all refcounts have been released
90 * split_huge_page cannot run anymore from under us.
93 __put_compound_page(page
);
95 __put_single_page(page
);
100 /* __split_huge_page_refcount can run under us */
101 page_head
= compound_head(page
);
104 * THP can not break up slab pages so avoid taking
105 * compound_lock() and skip the tail page refcounting (in
106 * _mapcount) too. Slab performs non-atomic bit ops on
107 * page->flags for better performance. In particular
108 * slab_unlock() in slub used to be a hot path. It is still
109 * hot on arches that do not support
110 * this_cpu_cmpxchg_double().
112 * If "page" is part of a slab or hugetlbfs page it cannot be
113 * splitted and the head page cannot change from under us. And
114 * if "page" is part of a THP page under splitting, if the
115 * head page pointed by the THP tail isn't a THP head anymore,
116 * we'll find PageTail clear after smp_rmb() and we'll treat
117 * it as a single page.
119 if (!__compound_tail_refcounted(page_head
)) {
121 * If "page" is a THP tail, we must read the tail page
122 * flags after the head page flags. The
123 * split_huge_page side enforces write memory barriers
124 * between clearing PageTail and before the head page
125 * can be freed and reallocated.
128 if (likely(PageTail(page
))) {
130 * __split_huge_page_refcount cannot race
133 VM_BUG_ON_PAGE(!PageHead(page_head
), page_head
);
134 VM_BUG_ON_PAGE(page_mapcount(page
) != 0, page
);
135 if (put_page_testzero(page_head
)) {
137 * If this is the tail of a slab
138 * compound page, the tail pin must
139 * not be the last reference held on
140 * the page, because the PG_slab
141 * cannot be cleared before all tail
142 * pins (which skips the _mapcount
143 * tail refcounting) have been
144 * released. For hugetlbfs the tail
145 * pin may be the last reference on
146 * the page instead, because
147 * PageHeadHuge will not go away until
148 * the compound page enters the buddy
151 VM_BUG_ON_PAGE(PageSlab(page_head
), page_head
);
152 __put_compound_page(page_head
);
157 * __split_huge_page_refcount run before us,
158 * "page" was a THP tail. The split page_head
159 * has been freed and reallocated as slab or
160 * hugetlbfs page of smaller order (only
161 * possible if reallocated as slab on x86).
166 if (likely(page
!= page_head
&& get_page_unless_zero(page_head
))) {
170 * page_head wasn't a dangling pointer but it may not
171 * be a head page anymore by the time we obtain the
172 * lock. That is ok as long as it can't be freed from
175 flags
= compound_lock_irqsave(page_head
);
176 if (unlikely(!PageTail(page
))) {
177 /* __split_huge_page_refcount run before us */
178 compound_unlock_irqrestore(page_head
, flags
);
179 if (put_page_testzero(page_head
)) {
181 * The head page may have been freed
182 * and reallocated as a compound page
183 * of smaller order and then freed
184 * again. All we know is that it
185 * cannot have become: a THP page, a
186 * compound page of higher order, a
187 * tail page. That is because we
188 * still hold the refcount of the
189 * split THP tail and page_head was
190 * the THP head before the split.
192 if (PageHead(page_head
))
193 __put_compound_page(page_head
);
195 __put_single_page(page_head
);
198 if (put_page_testzero(page
))
199 __put_single_page(page
);
202 VM_BUG_ON_PAGE(page_head
!= page
->first_page
, page
);
204 * We can release the refcount taken by
205 * get_page_unless_zero() now that
206 * __split_huge_page_refcount() is blocked on the
209 if (put_page_testzero(page_head
))
210 VM_BUG_ON_PAGE(1, page_head
);
211 /* __split_huge_page_refcount will wait now */
212 VM_BUG_ON_PAGE(page_mapcount(page
) <= 0, page
);
213 atomic_dec(&page
->_mapcount
);
214 VM_BUG_ON_PAGE(atomic_read(&page_head
->_count
) <= 0, page_head
);
215 VM_BUG_ON_PAGE(atomic_read(&page
->_count
) != 0, page
);
216 compound_unlock_irqrestore(page_head
, flags
);
218 if (put_page_testzero(page_head
)) {
219 if (PageHead(page_head
))
220 __put_compound_page(page_head
);
222 __put_single_page(page_head
);
225 /* page_head is a dangling pointer */
226 VM_BUG_ON_PAGE(PageTail(page
), page
);
231 void put_page(struct page
*page
)
233 if (unlikely(PageCompound(page
)))
234 put_compound_page(page
);
235 else if (put_page_testzero(page
))
236 __put_single_page(page
);
238 EXPORT_SYMBOL(put_page
);
241 * This function is exported but must not be called by anything other
242 * than get_page(). It implements the slow path of get_page().
244 bool __get_page_tail(struct page
*page
)
247 * This takes care of get_page() if run on a tail page
248 * returned by one of the get_user_pages/follow_page variants.
249 * get_user_pages/follow_page itself doesn't need the compound
250 * lock because it runs __get_page_tail_foll() under the
251 * proper PT lock that already serializes against
256 struct page
*page_head
= compound_head(page
);
258 /* Ref to put_compound_page() comment. */
259 if (!__compound_tail_refcounted(page_head
)) {
261 if (likely(PageTail(page
))) {
263 * This is a hugetlbfs page or a slab
264 * page. __split_huge_page_refcount
267 VM_BUG_ON_PAGE(!PageHead(page_head
), page_head
);
268 __get_page_tail_foll(page
, true);
272 * __split_huge_page_refcount run
273 * before us, "page" was a THP
274 * tail. The split page_head has been
275 * freed and reallocated as slab or
276 * hugetlbfs page of smaller order
277 * (only possible if reallocated as
285 if (likely(page
!= page_head
&& get_page_unless_zero(page_head
))) {
287 * page_head wasn't a dangling pointer but it
288 * may not be a head page anymore by the time
289 * we obtain the lock. That is ok as long as it
290 * can't be freed from under us.
292 flags
= compound_lock_irqsave(page_head
);
293 /* here __split_huge_page_refcount won't run anymore */
294 if (likely(PageTail(page
))) {
295 __get_page_tail_foll(page
, false);
298 compound_unlock_irqrestore(page_head
, flags
);
304 EXPORT_SYMBOL(__get_page_tail
);
307 * put_pages_list() - release a list of pages
308 * @pages: list of pages threaded on page->lru
310 * Release a list of pages which are strung together on page.lru. Currently
311 * used by read_cache_pages() and related error recovery code.
313 void put_pages_list(struct list_head
*pages
)
315 while (!list_empty(pages
)) {
318 victim
= list_entry(pages
->prev
, struct page
, lru
);
319 list_del(&victim
->lru
);
320 page_cache_release(victim
);
323 EXPORT_SYMBOL(put_pages_list
);
326 * get_kernel_pages() - pin kernel pages in memory
327 * @kiov: An array of struct kvec structures
328 * @nr_segs: number of segments to pin
329 * @write: pinning for read/write, currently ignored
330 * @pages: array that receives pointers to the pages pinned.
331 * Should be at least nr_segs long.
333 * Returns number of pages pinned. This may be fewer than the number
334 * requested. If nr_pages is 0 or negative, returns 0. If no pages
335 * were pinned, returns -errno. Each page returned must be released
336 * with a put_page() call when it is finished with.
338 int get_kernel_pages(const struct kvec
*kiov
, int nr_segs
, int write
,
343 for (seg
= 0; seg
< nr_segs
; seg
++) {
344 if (WARN_ON(kiov
[seg
].iov_len
!= PAGE_SIZE
))
347 pages
[seg
] = kmap_to_page(kiov
[seg
].iov_base
);
348 page_cache_get(pages
[seg
]);
353 EXPORT_SYMBOL_GPL(get_kernel_pages
);
356 * get_kernel_page() - pin a kernel page in memory
357 * @start: starting kernel address
358 * @write: pinning for read/write, currently ignored
359 * @pages: array that receives pointer to the page pinned.
360 * Must be at least nr_segs long.
362 * Returns 1 if page is pinned. If the page was not pinned, returns
363 * -errno. The page returned must be released with a put_page() call
364 * when it is finished with.
366 int get_kernel_page(unsigned long start
, int write
, struct page
**pages
)
368 const struct kvec kiov
= {
369 .iov_base
= (void *)start
,
373 return get_kernel_pages(&kiov
, 1, write
, pages
);
375 EXPORT_SYMBOL_GPL(get_kernel_page
);
377 static void pagevec_lru_move_fn(struct pagevec
*pvec
,
378 void (*move_fn
)(struct page
*page
, struct lruvec
*lruvec
, void *arg
),
382 struct zone
*zone
= NULL
;
383 struct lruvec
*lruvec
;
384 unsigned long flags
= 0;
386 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
387 struct page
*page
= pvec
->pages
[i
];
388 struct zone
*pagezone
= page_zone(page
);
390 if (pagezone
!= zone
) {
392 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
394 spin_lock_irqsave(&zone
->lru_lock
, flags
);
397 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
398 (*move_fn
)(page
, lruvec
, arg
);
401 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
402 release_pages(pvec
->pages
, pvec
->nr
, pvec
->cold
);
403 pagevec_reinit(pvec
);
406 static void pagevec_move_tail_fn(struct page
*page
, struct lruvec
*lruvec
,
411 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
412 enum lru_list lru
= page_lru_base_type(page
);
413 list_move_tail(&page
->lru
, &lruvec
->lists
[lru
]);
419 * pagevec_move_tail() must be called with IRQ disabled.
420 * Otherwise this may cause nasty races.
422 static void pagevec_move_tail(struct pagevec
*pvec
)
426 pagevec_lru_move_fn(pvec
, pagevec_move_tail_fn
, &pgmoved
);
427 __count_vm_events(PGROTATED
, pgmoved
);
431 * Writeback is about to end against a page which has been marked for immediate
432 * reclaim. If it still appears to be reclaimable, move it to the tail of the
435 void rotate_reclaimable_page(struct page
*page
)
437 if (!PageLocked(page
) && !PageDirty(page
) && !PageActive(page
) &&
438 !PageUnevictable(page
) && PageLRU(page
)) {
439 struct pagevec
*pvec
;
442 page_cache_get(page
);
443 local_irq_save(flags
);
444 pvec
= &__get_cpu_var(lru_rotate_pvecs
);
445 if (!pagevec_add(pvec
, page
))
446 pagevec_move_tail(pvec
);
447 local_irq_restore(flags
);
451 static void update_page_reclaim_stat(struct lruvec
*lruvec
,
452 int file
, int rotated
)
454 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
456 reclaim_stat
->recent_scanned
[file
]++;
458 reclaim_stat
->recent_rotated
[file
]++;
461 static void __activate_page(struct page
*page
, struct lruvec
*lruvec
,
464 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
465 int file
= page_is_file_cache(page
);
466 int lru
= page_lru_base_type(page
);
468 del_page_from_lru_list(page
, lruvec
, lru
);
471 add_page_to_lru_list(page
, lruvec
, lru
);
472 trace_mm_lru_activate(page
, page_to_pfn(page
));
474 __count_vm_event(PGACTIVATE
);
475 update_page_reclaim_stat(lruvec
, file
, 1);
480 static DEFINE_PER_CPU(struct pagevec
, activate_page_pvecs
);
482 static void activate_page_drain(int cpu
)
484 struct pagevec
*pvec
= &per_cpu(activate_page_pvecs
, cpu
);
486 if (pagevec_count(pvec
))
487 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
490 static bool need_activate_page_drain(int cpu
)
492 return pagevec_count(&per_cpu(activate_page_pvecs
, cpu
)) != 0;
495 void activate_page(struct page
*page
)
497 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
498 struct pagevec
*pvec
= &get_cpu_var(activate_page_pvecs
);
500 page_cache_get(page
);
501 if (!pagevec_add(pvec
, page
))
502 pagevec_lru_move_fn(pvec
, __activate_page
, NULL
);
503 put_cpu_var(activate_page_pvecs
);
508 static inline void activate_page_drain(int cpu
)
512 static bool need_activate_page_drain(int cpu
)
517 void activate_page(struct page
*page
)
519 struct zone
*zone
= page_zone(page
);
521 spin_lock_irq(&zone
->lru_lock
);
522 __activate_page(page
, mem_cgroup_page_lruvec(page
, zone
), NULL
);
523 spin_unlock_irq(&zone
->lru_lock
);
527 static void __lru_cache_activate_page(struct page
*page
)
529 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvec
);
533 * Search backwards on the optimistic assumption that the page being
534 * activated has just been added to this pagevec. Note that only
535 * the local pagevec is examined as a !PageLRU page could be in the
536 * process of being released, reclaimed, migrated or on a remote
537 * pagevec that is currently being drained. Furthermore, marking
538 * a remote pagevec's page PageActive potentially hits a race where
539 * a page is marked PageActive just after it is added to the inactive
540 * list causing accounting errors and BUG_ON checks to trigger.
542 for (i
= pagevec_count(pvec
) - 1; i
>= 0; i
--) {
543 struct page
*pagevec_page
= pvec
->pages
[i
];
545 if (pagevec_page
== page
) {
551 put_cpu_var(lru_add_pvec
);
555 * Mark a page as having seen activity.
557 * inactive,unreferenced -> inactive,referenced
558 * inactive,referenced -> active,unreferenced
559 * active,unreferenced -> active,referenced
561 void mark_page_accessed(struct page
*page
)
563 if (!PageActive(page
) && !PageUnevictable(page
) &&
564 PageReferenced(page
)) {
567 * If the page is on the LRU, queue it for activation via
568 * activate_page_pvecs. Otherwise, assume the page is on a
569 * pagevec, mark it active and it'll be moved to the active
570 * LRU on the next drain.
575 __lru_cache_activate_page(page
);
576 ClearPageReferenced(page
);
577 } else if (!PageReferenced(page
)) {
578 SetPageReferenced(page
);
581 EXPORT_SYMBOL(mark_page_accessed
);
584 * Queue the page for addition to the LRU via pagevec. The decision on whether
585 * to add the page to the [in]active [file|anon] list is deferred until the
586 * pagevec is drained. This gives a chance for the caller of __lru_cache_add()
587 * have the page added to the active list using mark_page_accessed().
589 void __lru_cache_add(struct page
*page
)
591 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvec
);
593 page_cache_get(page
);
594 if (!pagevec_space(pvec
))
595 __pagevec_lru_add(pvec
);
596 pagevec_add(pvec
, page
);
597 put_cpu_var(lru_add_pvec
);
599 EXPORT_SYMBOL(__lru_cache_add
);
602 * lru_cache_add - add a page to a page list
603 * @page: the page to be added to the LRU.
605 void lru_cache_add(struct page
*page
)
607 VM_BUG_ON_PAGE(PageActive(page
) && PageUnevictable(page
), page
);
608 VM_BUG_ON_PAGE(PageLRU(page
), page
);
609 __lru_cache_add(page
);
613 * add_page_to_unevictable_list - add a page to the unevictable list
614 * @page: the page to be added to the unevictable list
616 * Add page directly to its zone's unevictable list. To avoid races with
617 * tasks that might be making the page evictable, through eg. munlock,
618 * munmap or exit, while it's not on the lru, we want to add the page
619 * while it's locked or otherwise "invisible" to other tasks. This is
620 * difficult to do when using the pagevec cache, so bypass that.
622 void add_page_to_unevictable_list(struct page
*page
)
624 struct zone
*zone
= page_zone(page
);
625 struct lruvec
*lruvec
;
627 spin_lock_irq(&zone
->lru_lock
);
628 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
629 ClearPageActive(page
);
630 SetPageUnevictable(page
);
632 add_page_to_lru_list(page
, lruvec
, LRU_UNEVICTABLE
);
633 spin_unlock_irq(&zone
->lru_lock
);
637 * If the page can not be invalidated, it is moved to the
638 * inactive list to speed up its reclaim. It is moved to the
639 * head of the list, rather than the tail, to give the flusher
640 * threads some time to write it out, as this is much more
641 * effective than the single-page writeout from reclaim.
643 * If the page isn't page_mapped and dirty/writeback, the page
644 * could reclaim asap using PG_reclaim.
646 * 1. active, mapped page -> none
647 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
648 * 3. inactive, mapped page -> none
649 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
650 * 5. inactive, clean -> inactive, tail
653 * In 4, why it moves inactive's head, the VM expects the page would
654 * be write it out by flusher threads as this is much more effective
655 * than the single-page writeout from reclaim.
657 static void lru_deactivate_fn(struct page
*page
, struct lruvec
*lruvec
,
666 if (PageUnevictable(page
))
669 /* Some processes are using the page */
670 if (page_mapped(page
))
673 active
= PageActive(page
);
674 file
= page_is_file_cache(page
);
675 lru
= page_lru_base_type(page
);
677 del_page_from_lru_list(page
, lruvec
, lru
+ active
);
678 ClearPageActive(page
);
679 ClearPageReferenced(page
);
680 add_page_to_lru_list(page
, lruvec
, lru
);
682 if (PageWriteback(page
) || PageDirty(page
)) {
684 * PG_reclaim could be raced with end_page_writeback
685 * It can make readahead confusing. But race window
686 * is _really_ small and it's non-critical problem.
688 SetPageReclaim(page
);
691 * The page's writeback ends up during pagevec
692 * We moves tha page into tail of inactive.
694 list_move_tail(&page
->lru
, &lruvec
->lists
[lru
]);
695 __count_vm_event(PGROTATED
);
699 __count_vm_event(PGDEACTIVATE
);
700 update_page_reclaim_stat(lruvec
, file
, 0);
704 * Drain pages out of the cpu's pagevecs.
705 * Either "cpu" is the current CPU, and preemption has already been
706 * disabled; or "cpu" is being hot-unplugged, and is already dead.
708 void lru_add_drain_cpu(int cpu
)
710 struct pagevec
*pvec
= &per_cpu(lru_add_pvec
, cpu
);
712 if (pagevec_count(pvec
))
713 __pagevec_lru_add(pvec
);
715 pvec
= &per_cpu(lru_rotate_pvecs
, cpu
);
716 if (pagevec_count(pvec
)) {
719 /* No harm done if a racing interrupt already did this */
720 local_irq_save(flags
);
721 pagevec_move_tail(pvec
);
722 local_irq_restore(flags
);
725 pvec
= &per_cpu(lru_deactivate_pvecs
, cpu
);
726 if (pagevec_count(pvec
))
727 pagevec_lru_move_fn(pvec
, lru_deactivate_fn
, NULL
);
729 activate_page_drain(cpu
);
733 * deactivate_page - forcefully deactivate a page
734 * @page: page to deactivate
736 * This function hints the VM that @page is a good reclaim candidate,
737 * for example if its invalidation fails due to the page being dirty
738 * or under writeback.
740 void deactivate_page(struct page
*page
)
743 * In a workload with many unevictable page such as mprotect, unevictable
744 * page deactivation for accelerating reclaim is pointless.
746 if (PageUnevictable(page
))
749 if (likely(get_page_unless_zero(page
))) {
750 struct pagevec
*pvec
= &get_cpu_var(lru_deactivate_pvecs
);
752 if (!pagevec_add(pvec
, page
))
753 pagevec_lru_move_fn(pvec
, lru_deactivate_fn
, NULL
);
754 put_cpu_var(lru_deactivate_pvecs
);
758 void lru_add_drain(void)
760 lru_add_drain_cpu(get_cpu());
764 static void lru_add_drain_per_cpu(struct work_struct
*dummy
)
769 static DEFINE_PER_CPU(struct work_struct
, lru_add_drain_work
);
771 void lru_add_drain_all(void)
773 static DEFINE_MUTEX(lock
);
774 static struct cpumask has_work
;
779 cpumask_clear(&has_work
);
781 for_each_online_cpu(cpu
) {
782 struct work_struct
*work
= &per_cpu(lru_add_drain_work
, cpu
);
784 if (pagevec_count(&per_cpu(lru_add_pvec
, cpu
)) ||
785 pagevec_count(&per_cpu(lru_rotate_pvecs
, cpu
)) ||
786 pagevec_count(&per_cpu(lru_deactivate_pvecs
, cpu
)) ||
787 need_activate_page_drain(cpu
)) {
788 INIT_WORK(work
, lru_add_drain_per_cpu
);
789 schedule_work_on(cpu
, work
);
790 cpumask_set_cpu(cpu
, &has_work
);
794 for_each_cpu(cpu
, &has_work
)
795 flush_work(&per_cpu(lru_add_drain_work
, cpu
));
802 * Batched page_cache_release(). Decrement the reference count on all the
803 * passed pages. If it fell to zero then remove the page from the LRU and
806 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
807 * for the remainder of the operation.
809 * The locking in this function is against shrink_inactive_list(): we recheck
810 * the page count inside the lock to see whether shrink_inactive_list()
811 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
814 void release_pages(struct page
**pages
, int nr
, int cold
)
817 LIST_HEAD(pages_to_free
);
818 struct zone
*zone
= NULL
;
819 struct lruvec
*lruvec
;
820 unsigned long uninitialized_var(flags
);
822 for (i
= 0; i
< nr
; i
++) {
823 struct page
*page
= pages
[i
];
825 if (unlikely(PageCompound(page
))) {
827 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
830 put_compound_page(page
);
834 if (!put_page_testzero(page
))
838 struct zone
*pagezone
= page_zone(page
);
840 if (pagezone
!= zone
) {
842 spin_unlock_irqrestore(&zone
->lru_lock
,
845 spin_lock_irqsave(&zone
->lru_lock
, flags
);
848 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
849 VM_BUG_ON_PAGE(!PageLRU(page
), page
);
850 __ClearPageLRU(page
);
851 del_page_from_lru_list(page
, lruvec
, page_off_lru(page
));
854 /* Clear Active bit in case of parallel mark_page_accessed */
855 ClearPageActive(page
);
857 list_add(&page
->lru
, &pages_to_free
);
860 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
862 free_hot_cold_page_list(&pages_to_free
, cold
);
864 EXPORT_SYMBOL(release_pages
);
867 * The pages which we're about to release may be in the deferred lru-addition
868 * queues. That would prevent them from really being freed right now. That's
869 * OK from a correctness point of view but is inefficient - those pages may be
870 * cache-warm and we want to give them back to the page allocator ASAP.
872 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
873 * and __pagevec_lru_add_active() call release_pages() directly to avoid
876 void __pagevec_release(struct pagevec
*pvec
)
879 release_pages(pvec
->pages
, pagevec_count(pvec
), pvec
->cold
);
880 pagevec_reinit(pvec
);
882 EXPORT_SYMBOL(__pagevec_release
);
884 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
885 /* used by __split_huge_page_refcount() */
886 void lru_add_page_tail(struct page
*page
, struct page
*page_tail
,
887 struct lruvec
*lruvec
, struct list_head
*list
)
891 VM_BUG_ON_PAGE(!PageHead(page
), page
);
892 VM_BUG_ON_PAGE(PageCompound(page_tail
), page
);
893 VM_BUG_ON_PAGE(PageLRU(page_tail
), page
);
894 VM_BUG_ON(NR_CPUS
!= 1 &&
895 !spin_is_locked(&lruvec_zone(lruvec
)->lru_lock
));
898 SetPageLRU(page_tail
);
900 if (likely(PageLRU(page
)))
901 list_add_tail(&page_tail
->lru
, &page
->lru
);
903 /* page reclaim is reclaiming a huge page */
905 list_add_tail(&page_tail
->lru
, list
);
907 struct list_head
*list_head
;
909 * Head page has not yet been counted, as an hpage,
910 * so we must account for each subpage individually.
912 * Use the standard add function to put page_tail on the list,
913 * but then correct its position so they all end up in order.
915 add_page_to_lru_list(page_tail
, lruvec
, page_lru(page_tail
));
916 list_head
= page_tail
->lru
.prev
;
917 list_move_tail(&page_tail
->lru
, list_head
);
920 if (!PageUnevictable(page
))
921 update_page_reclaim_stat(lruvec
, file
, PageActive(page_tail
));
923 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
925 static void __pagevec_lru_add_fn(struct page
*page
, struct lruvec
*lruvec
,
928 int file
= page_is_file_cache(page
);
929 int active
= PageActive(page
);
930 enum lru_list lru
= page_lru(page
);
932 VM_BUG_ON_PAGE(PageLRU(page
), page
);
935 add_page_to_lru_list(page
, lruvec
, lru
);
936 update_page_reclaim_stat(lruvec
, file
, active
);
937 trace_mm_lru_insertion(page
, page_to_pfn(page
), lru
, trace_pagemap_flags(page
));
941 * Add the passed pages to the LRU, then drop the caller's refcount
942 * on them. Reinitialises the caller's pagevec.
944 void __pagevec_lru_add(struct pagevec
*pvec
)
946 pagevec_lru_move_fn(pvec
, __pagevec_lru_add_fn
, NULL
);
948 EXPORT_SYMBOL(__pagevec_lru_add
);
951 * pagevec_lookup - gang pagecache lookup
952 * @pvec: Where the resulting pages are placed
953 * @mapping: The address_space to search
954 * @start: The starting page index
955 * @nr_pages: The maximum number of pages
957 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
958 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
959 * reference against the pages in @pvec.
961 * The search returns a group of mapping-contiguous pages with ascending
962 * indexes. There may be holes in the indices due to not-present pages.
964 * pagevec_lookup() returns the number of pages which were found.
966 unsigned pagevec_lookup(struct pagevec
*pvec
, struct address_space
*mapping
,
967 pgoff_t start
, unsigned nr_pages
)
969 pvec
->nr
= find_get_pages(mapping
, start
, nr_pages
, pvec
->pages
);
970 return pagevec_count(pvec
);
972 EXPORT_SYMBOL(pagevec_lookup
);
974 unsigned pagevec_lookup_tag(struct pagevec
*pvec
, struct address_space
*mapping
,
975 pgoff_t
*index
, int tag
, unsigned nr_pages
)
977 pvec
->nr
= find_get_pages_tag(mapping
, index
, tag
,
978 nr_pages
, pvec
->pages
);
979 return pagevec_count(pvec
);
981 EXPORT_SYMBOL(pagevec_lookup_tag
);
984 * Perform any setup for the swap system
986 void __init
swap_setup(void)
988 unsigned long megs
= totalram_pages
>> (20 - PAGE_SHIFT
);
992 if (bdi_init(swapper_spaces
[0].backing_dev_info
))
993 panic("Failed to init swap bdi");
994 for (i
= 0; i
< MAX_SWAPFILES
; i
++) {
995 spin_lock_init(&swapper_spaces
[i
].tree_lock
);
996 INIT_LIST_HEAD(&swapper_spaces
[i
].i_mmap_nonlinear
);
1000 /* Use a smaller cluster for small-memory machines */
1006 * Right now other parts of the system means that we
1007 * _really_ don't want to cluster much more