Merge tag 'gpio-for-v3.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw...
[linux-2.6.git] / mm / swap.c
blob62b78a6e224f2f10682e9fa11f28b8d01da1c324
1 /*
2 * linux/mm/swap.c
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
7 /*
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.
11 * Started 18.12.91
12 * Swap aging added 23.2.95, Stephen Tweedie.
13 * Buffermem limits added 12.3.98, Rik van Riel.
16 #include <linux/mm.h>
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>
35 #include "internal.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? */
41 int page_cluster;
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)
53 if (PageLRU(page)) {
54 struct zone *zone = page_zone(page);
55 struct lruvec *lruvec;
56 unsigned long flags;
58 spin_lock_irqsave(&zone->lru_lock, flags);
59 lruvec = mem_cgroup_page_lruvec(page, zone);
60 VM_BUG_ON(!PageLRU(page));
61 __ClearPageLRU(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);
79 (*dtor)(page);
82 static void put_compound_page(struct page *page)
84 if (unlikely(PageTail(page))) {
85 /* __split_huge_page_refcount can run under us */
86 struct page *page_head = compound_trans_head(page);
88 if (likely(page != page_head &&
89 get_page_unless_zero(page_head))) {
90 unsigned long flags;
93 * THP can not break up slab pages so avoid taking
94 * compound_lock(). Slab performs non-atomic bit ops
95 * on page->flags for better performance. In particular
96 * slab_unlock() in slub used to be a hot path. It is
97 * still hot on arches that do not support
98 * this_cpu_cmpxchg_double().
100 if (PageSlab(page_head)) {
101 if (PageTail(page)) {
102 if (put_page_testzero(page_head))
103 VM_BUG_ON(1);
105 atomic_dec(&page->_mapcount);
106 goto skip_lock_tail;
107 } else
108 goto skip_lock;
111 * page_head wasn't a dangling pointer but it
112 * may not be a head page anymore by the time
113 * we obtain the lock. That is ok as long as it
114 * can't be freed from under us.
116 flags = compound_lock_irqsave(page_head);
117 if (unlikely(!PageTail(page))) {
118 /* __split_huge_page_refcount run before us */
119 compound_unlock_irqrestore(page_head, flags);
120 skip_lock:
121 if (put_page_testzero(page_head))
122 __put_single_page(page_head);
123 out_put_single:
124 if (put_page_testzero(page))
125 __put_single_page(page);
126 return;
128 VM_BUG_ON(page_head != page->first_page);
130 * We can release the refcount taken by
131 * get_page_unless_zero() now that
132 * __split_huge_page_refcount() is blocked on
133 * the compound_lock.
135 if (put_page_testzero(page_head))
136 VM_BUG_ON(1);
137 /* __split_huge_page_refcount will wait now */
138 VM_BUG_ON(page_mapcount(page) <= 0);
139 atomic_dec(&page->_mapcount);
140 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
141 VM_BUG_ON(atomic_read(&page->_count) != 0);
142 compound_unlock_irqrestore(page_head, flags);
144 skip_lock_tail:
145 if (put_page_testzero(page_head)) {
146 if (PageHead(page_head))
147 __put_compound_page(page_head);
148 else
149 __put_single_page(page_head);
151 } else {
152 /* page_head is a dangling pointer */
153 VM_BUG_ON(PageTail(page));
154 goto out_put_single;
156 } else if (put_page_testzero(page)) {
157 if (PageHead(page))
158 __put_compound_page(page);
159 else
160 __put_single_page(page);
164 void put_page(struct page *page)
166 if (unlikely(PageCompound(page)))
167 put_compound_page(page);
168 else if (put_page_testzero(page))
169 __put_single_page(page);
171 EXPORT_SYMBOL(put_page);
174 * This function is exported but must not be called by anything other
175 * than get_page(). It implements the slow path of get_page().
177 bool __get_page_tail(struct page *page)
180 * This takes care of get_page() if run on a tail page
181 * returned by one of the get_user_pages/follow_page variants.
182 * get_user_pages/follow_page itself doesn't need the compound
183 * lock because it runs __get_page_tail_foll() under the
184 * proper PT lock that already serializes against
185 * split_huge_page().
187 unsigned long flags;
188 bool got = false;
189 struct page *page_head = compound_trans_head(page);
191 if (likely(page != page_head && get_page_unless_zero(page_head))) {
193 /* Ref to put_compound_page() comment. */
194 if (PageSlab(page_head)) {
195 if (likely(PageTail(page))) {
196 __get_page_tail_foll(page, false);
197 return true;
198 } else {
199 put_page(page_head);
200 return false;
205 * page_head wasn't a dangling pointer but it
206 * may not be a head page anymore by the time
207 * we obtain the lock. That is ok as long as it
208 * can't be freed from under us.
210 flags = compound_lock_irqsave(page_head);
211 /* here __split_huge_page_refcount won't run anymore */
212 if (likely(PageTail(page))) {
213 __get_page_tail_foll(page, false);
214 got = true;
216 compound_unlock_irqrestore(page_head, flags);
217 if (unlikely(!got))
218 put_page(page_head);
220 return got;
222 EXPORT_SYMBOL(__get_page_tail);
225 * put_pages_list() - release a list of pages
226 * @pages: list of pages threaded on page->lru
228 * Release a list of pages which are strung together on page.lru. Currently
229 * used by read_cache_pages() and related error recovery code.
231 void put_pages_list(struct list_head *pages)
233 while (!list_empty(pages)) {
234 struct page *victim;
236 victim = list_entry(pages->prev, struct page, lru);
237 list_del(&victim->lru);
238 page_cache_release(victim);
241 EXPORT_SYMBOL(put_pages_list);
244 * get_kernel_pages() - pin kernel pages in memory
245 * @kiov: An array of struct kvec structures
246 * @nr_segs: number of segments to pin
247 * @write: pinning for read/write, currently ignored
248 * @pages: array that receives pointers to the pages pinned.
249 * Should be at least nr_segs long.
251 * Returns number of pages pinned. This may be fewer than the number
252 * requested. If nr_pages is 0 or negative, returns 0. If no pages
253 * were pinned, returns -errno. Each page returned must be released
254 * with a put_page() call when it is finished with.
256 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
257 struct page **pages)
259 int seg;
261 for (seg = 0; seg < nr_segs; seg++) {
262 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
263 return seg;
265 pages[seg] = kmap_to_page(kiov[seg].iov_base);
266 page_cache_get(pages[seg]);
269 return seg;
271 EXPORT_SYMBOL_GPL(get_kernel_pages);
274 * get_kernel_page() - pin a kernel page in memory
275 * @start: starting kernel address
276 * @write: pinning for read/write, currently ignored
277 * @pages: array that receives pointer to the page pinned.
278 * Must be at least nr_segs long.
280 * Returns 1 if page is pinned. If the page was not pinned, returns
281 * -errno. The page returned must be released with a put_page() call
282 * when it is finished with.
284 int get_kernel_page(unsigned long start, int write, struct page **pages)
286 const struct kvec kiov = {
287 .iov_base = (void *)start,
288 .iov_len = PAGE_SIZE
291 return get_kernel_pages(&kiov, 1, write, pages);
293 EXPORT_SYMBOL_GPL(get_kernel_page);
295 static void pagevec_lru_move_fn(struct pagevec *pvec,
296 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
297 void *arg)
299 int i;
300 struct zone *zone = NULL;
301 struct lruvec *lruvec;
302 unsigned long flags = 0;
304 for (i = 0; i < pagevec_count(pvec); i++) {
305 struct page *page = pvec->pages[i];
306 struct zone *pagezone = page_zone(page);
308 if (pagezone != zone) {
309 if (zone)
310 spin_unlock_irqrestore(&zone->lru_lock, flags);
311 zone = pagezone;
312 spin_lock_irqsave(&zone->lru_lock, flags);
315 lruvec = mem_cgroup_page_lruvec(page, zone);
316 (*move_fn)(page, lruvec, arg);
318 if (zone)
319 spin_unlock_irqrestore(&zone->lru_lock, flags);
320 release_pages(pvec->pages, pvec->nr, pvec->cold);
321 pagevec_reinit(pvec);
324 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
325 void *arg)
327 int *pgmoved = arg;
329 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
330 enum lru_list lru = page_lru_base_type(page);
331 list_move_tail(&page->lru, &lruvec->lists[lru]);
332 (*pgmoved)++;
337 * pagevec_move_tail() must be called with IRQ disabled.
338 * Otherwise this may cause nasty races.
340 static void pagevec_move_tail(struct pagevec *pvec)
342 int pgmoved = 0;
344 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
345 __count_vm_events(PGROTATED, pgmoved);
349 * Writeback is about to end against a page which has been marked for immediate
350 * reclaim. If it still appears to be reclaimable, move it to the tail of the
351 * inactive list.
353 void rotate_reclaimable_page(struct page *page)
355 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
356 !PageUnevictable(page) && PageLRU(page)) {
357 struct pagevec *pvec;
358 unsigned long flags;
360 page_cache_get(page);
361 local_irq_save(flags);
362 pvec = &__get_cpu_var(lru_rotate_pvecs);
363 if (!pagevec_add(pvec, page))
364 pagevec_move_tail(pvec);
365 local_irq_restore(flags);
369 static void update_page_reclaim_stat(struct lruvec *lruvec,
370 int file, int rotated)
372 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
374 reclaim_stat->recent_scanned[file]++;
375 if (rotated)
376 reclaim_stat->recent_rotated[file]++;
379 static void __activate_page(struct page *page, struct lruvec *lruvec,
380 void *arg)
382 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
383 int file = page_is_file_cache(page);
384 int lru = page_lru_base_type(page);
386 del_page_from_lru_list(page, lruvec, lru);
387 SetPageActive(page);
388 lru += LRU_ACTIVE;
389 add_page_to_lru_list(page, lruvec, lru);
390 trace_mm_lru_activate(page, page_to_pfn(page));
392 __count_vm_event(PGACTIVATE);
393 update_page_reclaim_stat(lruvec, file, 1);
397 #ifdef CONFIG_SMP
398 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
400 static void activate_page_drain(int cpu)
402 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
404 if (pagevec_count(pvec))
405 pagevec_lru_move_fn(pvec, __activate_page, NULL);
408 void activate_page(struct page *page)
410 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
411 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
413 page_cache_get(page);
414 if (!pagevec_add(pvec, page))
415 pagevec_lru_move_fn(pvec, __activate_page, NULL);
416 put_cpu_var(activate_page_pvecs);
420 #else
421 static inline void activate_page_drain(int cpu)
425 void activate_page(struct page *page)
427 struct zone *zone = page_zone(page);
429 spin_lock_irq(&zone->lru_lock);
430 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
431 spin_unlock_irq(&zone->lru_lock);
433 #endif
435 static void __lru_cache_activate_page(struct page *page)
437 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
438 int i;
441 * Search backwards on the optimistic assumption that the page being
442 * activated has just been added to this pagevec. Note that only
443 * the local pagevec is examined as a !PageLRU page could be in the
444 * process of being released, reclaimed, migrated or on a remote
445 * pagevec that is currently being drained. Furthermore, marking
446 * a remote pagevec's page PageActive potentially hits a race where
447 * a page is marked PageActive just after it is added to the inactive
448 * list causing accounting errors and BUG_ON checks to trigger.
450 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
451 struct page *pagevec_page = pvec->pages[i];
453 if (pagevec_page == page) {
454 SetPageActive(page);
455 break;
459 put_cpu_var(lru_add_pvec);
463 * Mark a page as having seen activity.
465 * inactive,unreferenced -> inactive,referenced
466 * inactive,referenced -> active,unreferenced
467 * active,unreferenced -> active,referenced
469 void mark_page_accessed(struct page *page)
471 if (!PageActive(page) && !PageUnevictable(page) &&
472 PageReferenced(page)) {
475 * If the page is on the LRU, queue it for activation via
476 * activate_page_pvecs. Otherwise, assume the page is on a
477 * pagevec, mark it active and it'll be moved to the active
478 * LRU on the next drain.
480 if (PageLRU(page))
481 activate_page(page);
482 else
483 __lru_cache_activate_page(page);
484 ClearPageReferenced(page);
485 } else if (!PageReferenced(page)) {
486 SetPageReferenced(page);
489 EXPORT_SYMBOL(mark_page_accessed);
492 * Queue the page for addition to the LRU via pagevec. The decision on whether
493 * to add the page to the [in]active [file|anon] list is deferred until the
494 * pagevec is drained. This gives a chance for the caller of __lru_cache_add()
495 * have the page added to the active list using mark_page_accessed().
497 void __lru_cache_add(struct page *page)
499 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
501 page_cache_get(page);
502 if (!pagevec_space(pvec))
503 __pagevec_lru_add(pvec);
504 pagevec_add(pvec, page);
505 put_cpu_var(lru_add_pvec);
507 EXPORT_SYMBOL(__lru_cache_add);
510 * lru_cache_add - add a page to a page list
511 * @page: the page to be added to the LRU.
513 void lru_cache_add(struct page *page)
515 VM_BUG_ON(PageActive(page) && PageUnevictable(page));
516 VM_BUG_ON(PageLRU(page));
517 __lru_cache_add(page);
521 * add_page_to_unevictable_list - add a page to the unevictable list
522 * @page: the page to be added to the unevictable list
524 * Add page directly to its zone's unevictable list. To avoid races with
525 * tasks that might be making the page evictable, through eg. munlock,
526 * munmap or exit, while it's not on the lru, we want to add the page
527 * while it's locked or otherwise "invisible" to other tasks. This is
528 * difficult to do when using the pagevec cache, so bypass that.
530 void add_page_to_unevictable_list(struct page *page)
532 struct zone *zone = page_zone(page);
533 struct lruvec *lruvec;
535 spin_lock_irq(&zone->lru_lock);
536 lruvec = mem_cgroup_page_lruvec(page, zone);
537 ClearPageActive(page);
538 SetPageUnevictable(page);
539 SetPageLRU(page);
540 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
541 spin_unlock_irq(&zone->lru_lock);
545 * If the page can not be invalidated, it is moved to the
546 * inactive list to speed up its reclaim. It is moved to the
547 * head of the list, rather than the tail, to give the flusher
548 * threads some time to write it out, as this is much more
549 * effective than the single-page writeout from reclaim.
551 * If the page isn't page_mapped and dirty/writeback, the page
552 * could reclaim asap using PG_reclaim.
554 * 1. active, mapped page -> none
555 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
556 * 3. inactive, mapped page -> none
557 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
558 * 5. inactive, clean -> inactive, tail
559 * 6. Others -> none
561 * In 4, why it moves inactive's head, the VM expects the page would
562 * be write it out by flusher threads as this is much more effective
563 * than the single-page writeout from reclaim.
565 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
566 void *arg)
568 int lru, file;
569 bool active;
571 if (!PageLRU(page))
572 return;
574 if (PageUnevictable(page))
575 return;
577 /* Some processes are using the page */
578 if (page_mapped(page))
579 return;
581 active = PageActive(page);
582 file = page_is_file_cache(page);
583 lru = page_lru_base_type(page);
585 del_page_from_lru_list(page, lruvec, lru + active);
586 ClearPageActive(page);
587 ClearPageReferenced(page);
588 add_page_to_lru_list(page, lruvec, lru);
590 if (PageWriteback(page) || PageDirty(page)) {
592 * PG_reclaim could be raced with end_page_writeback
593 * It can make readahead confusing. But race window
594 * is _really_ small and it's non-critical problem.
596 SetPageReclaim(page);
597 } else {
599 * The page's writeback ends up during pagevec
600 * We moves tha page into tail of inactive.
602 list_move_tail(&page->lru, &lruvec->lists[lru]);
603 __count_vm_event(PGROTATED);
606 if (active)
607 __count_vm_event(PGDEACTIVATE);
608 update_page_reclaim_stat(lruvec, file, 0);
612 * Drain pages out of the cpu's pagevecs.
613 * Either "cpu" is the current CPU, and preemption has already been
614 * disabled; or "cpu" is being hot-unplugged, and is already dead.
616 void lru_add_drain_cpu(int cpu)
618 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
620 if (pagevec_count(pvec))
621 __pagevec_lru_add(pvec);
623 pvec = &per_cpu(lru_rotate_pvecs, cpu);
624 if (pagevec_count(pvec)) {
625 unsigned long flags;
627 /* No harm done if a racing interrupt already did this */
628 local_irq_save(flags);
629 pagevec_move_tail(pvec);
630 local_irq_restore(flags);
633 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
634 if (pagevec_count(pvec))
635 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
637 activate_page_drain(cpu);
641 * deactivate_page - forcefully deactivate a page
642 * @page: page to deactivate
644 * This function hints the VM that @page is a good reclaim candidate,
645 * for example if its invalidation fails due to the page being dirty
646 * or under writeback.
648 void deactivate_page(struct page *page)
651 * In a workload with many unevictable page such as mprotect, unevictable
652 * page deactivation for accelerating reclaim is pointless.
654 if (PageUnevictable(page))
655 return;
657 if (likely(get_page_unless_zero(page))) {
658 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
660 if (!pagevec_add(pvec, page))
661 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
662 put_cpu_var(lru_deactivate_pvecs);
666 void lru_add_drain(void)
668 lru_add_drain_cpu(get_cpu());
669 put_cpu();
672 static void lru_add_drain_per_cpu(struct work_struct *dummy)
674 lru_add_drain();
678 * Returns 0 for success
680 int lru_add_drain_all(void)
682 return schedule_on_each_cpu(lru_add_drain_per_cpu);
686 * Batched page_cache_release(). Decrement the reference count on all the
687 * passed pages. If it fell to zero then remove the page from the LRU and
688 * free it.
690 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
691 * for the remainder of the operation.
693 * The locking in this function is against shrink_inactive_list(): we recheck
694 * the page count inside the lock to see whether shrink_inactive_list()
695 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
696 * will free it.
698 void release_pages(struct page **pages, int nr, int cold)
700 int i;
701 LIST_HEAD(pages_to_free);
702 struct zone *zone = NULL;
703 struct lruvec *lruvec;
704 unsigned long uninitialized_var(flags);
706 for (i = 0; i < nr; i++) {
707 struct page *page = pages[i];
709 if (unlikely(PageCompound(page))) {
710 if (zone) {
711 spin_unlock_irqrestore(&zone->lru_lock, flags);
712 zone = NULL;
714 put_compound_page(page);
715 continue;
718 if (!put_page_testzero(page))
719 continue;
721 if (PageLRU(page)) {
722 struct zone *pagezone = page_zone(page);
724 if (pagezone != zone) {
725 if (zone)
726 spin_unlock_irqrestore(&zone->lru_lock,
727 flags);
728 zone = pagezone;
729 spin_lock_irqsave(&zone->lru_lock, flags);
732 lruvec = mem_cgroup_page_lruvec(page, zone);
733 VM_BUG_ON(!PageLRU(page));
734 __ClearPageLRU(page);
735 del_page_from_lru_list(page, lruvec, page_off_lru(page));
738 /* Clear Active bit in case of parallel mark_page_accessed */
739 ClearPageActive(page);
741 list_add(&page->lru, &pages_to_free);
743 if (zone)
744 spin_unlock_irqrestore(&zone->lru_lock, flags);
746 free_hot_cold_page_list(&pages_to_free, cold);
748 EXPORT_SYMBOL(release_pages);
751 * The pages which we're about to release may be in the deferred lru-addition
752 * queues. That would prevent them from really being freed right now. That's
753 * OK from a correctness point of view but is inefficient - those pages may be
754 * cache-warm and we want to give them back to the page allocator ASAP.
756 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
757 * and __pagevec_lru_add_active() call release_pages() directly to avoid
758 * mutual recursion.
760 void __pagevec_release(struct pagevec *pvec)
762 lru_add_drain();
763 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
764 pagevec_reinit(pvec);
766 EXPORT_SYMBOL(__pagevec_release);
768 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
769 /* used by __split_huge_page_refcount() */
770 void lru_add_page_tail(struct page *page, struct page *page_tail,
771 struct lruvec *lruvec, struct list_head *list)
773 const int file = 0;
775 VM_BUG_ON(!PageHead(page));
776 VM_BUG_ON(PageCompound(page_tail));
777 VM_BUG_ON(PageLRU(page_tail));
778 VM_BUG_ON(NR_CPUS != 1 &&
779 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
781 if (!list)
782 SetPageLRU(page_tail);
784 if (likely(PageLRU(page)))
785 list_add_tail(&page_tail->lru, &page->lru);
786 else if (list) {
787 /* page reclaim is reclaiming a huge page */
788 get_page(page_tail);
789 list_add_tail(&page_tail->lru, list);
790 } else {
791 struct list_head *list_head;
793 * Head page has not yet been counted, as an hpage,
794 * so we must account for each subpage individually.
796 * Use the standard add function to put page_tail on the list,
797 * but then correct its position so they all end up in order.
799 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
800 list_head = page_tail->lru.prev;
801 list_move_tail(&page_tail->lru, list_head);
804 if (!PageUnevictable(page))
805 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
807 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
809 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
810 void *arg)
812 int file = page_is_file_cache(page);
813 int active = PageActive(page);
814 enum lru_list lru = page_lru(page);
816 VM_BUG_ON(PageLRU(page));
818 SetPageLRU(page);
819 add_page_to_lru_list(page, lruvec, lru);
820 update_page_reclaim_stat(lruvec, file, active);
821 trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page));
825 * Add the passed pages to the LRU, then drop the caller's refcount
826 * on them. Reinitialises the caller's pagevec.
828 void __pagevec_lru_add(struct pagevec *pvec)
830 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
832 EXPORT_SYMBOL(__pagevec_lru_add);
835 * pagevec_lookup - gang pagecache lookup
836 * @pvec: Where the resulting pages are placed
837 * @mapping: The address_space to search
838 * @start: The starting page index
839 * @nr_pages: The maximum number of pages
841 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
842 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
843 * reference against the pages in @pvec.
845 * The search returns a group of mapping-contiguous pages with ascending
846 * indexes. There may be holes in the indices due to not-present pages.
848 * pagevec_lookup() returns the number of pages which were found.
850 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
851 pgoff_t start, unsigned nr_pages)
853 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
854 return pagevec_count(pvec);
856 EXPORT_SYMBOL(pagevec_lookup);
858 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
859 pgoff_t *index, int tag, unsigned nr_pages)
861 pvec->nr = find_get_pages_tag(mapping, index, tag,
862 nr_pages, pvec->pages);
863 return pagevec_count(pvec);
865 EXPORT_SYMBOL(pagevec_lookup_tag);
868 * Perform any setup for the swap system
870 void __init swap_setup(void)
872 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
873 #ifdef CONFIG_SWAP
874 int i;
876 bdi_init(swapper_spaces[0].backing_dev_info);
877 for (i = 0; i < MAX_SWAPFILES; i++) {
878 spin_lock_init(&swapper_spaces[i].tree_lock);
879 INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
881 #endif
883 /* Use a smaller cluster for small-memory machines */
884 if (megs < 16)
885 page_cluster = 2;
886 else
887 page_cluster = 3;
889 * Right now other parts of the system means that we
890 * _really_ don't want to cluster much more