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1/*
2 * linux/mm/swap.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
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.
14 */
15
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/module.h>
25#include <linux/mm_inline.h>
26#include <linux/buffer_head.h> /* for try_to_release_page() */
27#include <linux/percpu_counter.h>
28#include <linux/percpu.h>
29#include <linux/cpu.h>
30#include <linux/notifier.h>
31#include <linux/backing-dev.h>
32#include <linux/memcontrol.h>
33#include <linux/gfp.h>
34
35#include "internal.h"
36
37/* How many pages do we try to swap or page in/out together? */
38int page_cluster;
39
40static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
41static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
42static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
43
44/*
45 * This path almost never happens for VM activity - pages are normally
46 * freed via pagevecs. But it gets used by networking.
47 */
48static void __page_cache_release(struct page *page)
49{
50 if (PageLRU(page)) {
51 unsigned long flags;
52 struct zone *zone = page_zone(page);
53
54 spin_lock_irqsave(&zone->lru_lock, flags);
55 VM_BUG_ON(!PageLRU(page));
56 __ClearPageLRU(page);
57 del_page_from_lru(zone, page);
58 spin_unlock_irqrestore(&zone->lru_lock, flags);
59 }
60}
61
62static void __put_single_page(struct page *page)
63{
64 __page_cache_release(page);
65 free_hot_cold_page(page, 0);
66}
67
68static void __put_compound_page(struct page *page)
69{
70 compound_page_dtor *dtor;
71
72 __page_cache_release(page);
73 dtor = get_compound_page_dtor(page);
74 (*dtor)(page);
75}
76
77static void put_compound_page(struct page *page)
78{
79 if (unlikely(PageTail(page))) {
80 /* __split_huge_page_refcount can run under us */
81 struct page *page_head = page->first_page;
82 smp_rmb();
83 /*
84 * If PageTail is still set after smp_rmb() we can be sure
85 * that the page->first_page we read wasn't a dangling pointer.
86 * See __split_huge_page_refcount() smp_wmb().
87 */
88 if (likely(PageTail(page) && get_page_unless_zero(page_head))) {
89 unsigned long flags;
90 /*
91 * Verify that our page_head wasn't converted
92 * to a a regular page before we got a
93 * reference on it.
94 */
95 if (unlikely(!PageHead(page_head))) {
96 /* PageHead is cleared after PageTail */
97 smp_rmb();
98 VM_BUG_ON(PageTail(page));
99 goto out_put_head;
100 }
101 /*
102 * Only run compound_lock on a valid PageHead,
103 * after having it pinned with
104 * get_page_unless_zero() above.
105 */
106 smp_mb();
107 /* page_head wasn't a dangling pointer */
108 flags = compound_lock_irqsave(page_head);
109 if (unlikely(!PageTail(page))) {
110 /* __split_huge_page_refcount run before us */
111 compound_unlock_irqrestore(page_head, flags);
112 VM_BUG_ON(PageHead(page_head));
113 out_put_head:
114 if (put_page_testzero(page_head))
115 __put_single_page(page_head);
116 out_put_single:
117 if (put_page_testzero(page))
118 __put_single_page(page);
119 return;
120 }
121 VM_BUG_ON(page_head != page->first_page);
122 /*
123 * We can release the refcount taken by
124 * get_page_unless_zero now that
125 * split_huge_page_refcount is blocked on the
126 * compound_lock.
127 */
128 if (put_page_testzero(page_head))
129 VM_BUG_ON(1);
130 /* __split_huge_page_refcount will wait now */
131 VM_BUG_ON(atomic_read(&page->_count) <= 0);
132 atomic_dec(&page->_count);
133 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
134 compound_unlock_irqrestore(page_head, flags);
135 if (put_page_testzero(page_head)) {
136 if (PageHead(page_head))
137 __put_compound_page(page_head);
138 else
139 __put_single_page(page_head);
140 }
141 } else {
142 /* page_head is a dangling pointer */
143 VM_BUG_ON(PageTail(page));
144 goto out_put_single;
145 }
146 } else if (put_page_testzero(page)) {
147 if (PageHead(page))
148 __put_compound_page(page);
149 else
150 __put_single_page(page);
151 }
152}
153
154void put_page(struct page *page)
155{
156 if (unlikely(PageCompound(page)))
157 put_compound_page(page);
158 else if (put_page_testzero(page))
159 __put_single_page(page);
160}
161EXPORT_SYMBOL(put_page);
162
163/**
164 * put_pages_list() - release a list of pages
165 * @pages: list of pages threaded on page->lru
166 *
167 * Release a list of pages which are strung together on page.lru. Currently
168 * used by read_cache_pages() and related error recovery code.
169 */
170void put_pages_list(struct list_head *pages)
171{
172 while (!list_empty(pages)) {
173 struct page *victim;
174
175 victim = list_entry(pages->prev, struct page, lru);
176 list_del(&victim->lru);
177 page_cache_release(victim);
178 }
179}
180EXPORT_SYMBOL(put_pages_list);
181
182static void pagevec_lru_move_fn(struct pagevec *pvec,
183 void (*move_fn)(struct page *page, void *arg),
184 void *arg)
185{
186 int i;
187 struct zone *zone = NULL;
188 unsigned long flags = 0;
189
190 for (i = 0; i < pagevec_count(pvec); i++) {
191 struct page *page = pvec->pages[i];
192 struct zone *pagezone = page_zone(page);
193
194 if (pagezone != zone) {
195 if (zone)
196 spin_unlock_irqrestore(&zone->lru_lock, flags);
197 zone = pagezone;
198 spin_lock_irqsave(&zone->lru_lock, flags);
199 }
200
201 (*move_fn)(page, arg);
202 }
203 if (zone)
204 spin_unlock_irqrestore(&zone->lru_lock, flags);
205 release_pages(pvec->pages, pvec->nr, pvec->cold);
206 pagevec_reinit(pvec);
207}
208
209static void pagevec_move_tail_fn(struct page *page, void *arg)
210{
211 int *pgmoved = arg;
212 struct zone *zone = page_zone(page);
213
214 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
215 enum lru_list lru = page_lru_base_type(page);
216 list_move_tail(&page->lru, &zone->lru[lru].list);
217 mem_cgroup_rotate_reclaimable_page(page);
218 (*pgmoved)++;
219 }
220}
221
222/*
223 * pagevec_move_tail() must be called with IRQ disabled.
224 * Otherwise this may cause nasty races.
225 */
226static void pagevec_move_tail(struct pagevec *pvec)
227{
228 int pgmoved = 0;
229
230 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
231 __count_vm_events(PGROTATED, pgmoved);
232}
233
234/*
235 * Writeback is about to end against a page which has been marked for immediate
236 * reclaim. If it still appears to be reclaimable, move it to the tail of the
237 * inactive list.
238 */
239void rotate_reclaimable_page(struct page *page)
240{
241 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
242 !PageUnevictable(page) && PageLRU(page)) {
243 struct pagevec *pvec;
244 unsigned long flags;
245
246 page_cache_get(page);
247 local_irq_save(flags);
248 pvec = &__get_cpu_var(lru_rotate_pvecs);
249 if (!pagevec_add(pvec, page))
250 pagevec_move_tail(pvec);
251 local_irq_restore(flags);
252 }
253}
254
255static void update_page_reclaim_stat(struct zone *zone, struct page *page,
256 int file, int rotated)
257{
258 struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
259 struct zone_reclaim_stat *memcg_reclaim_stat;
260
261 memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
262
263 reclaim_stat->recent_scanned[file]++;
264 if (rotated)
265 reclaim_stat->recent_rotated[file]++;
266
267 if (!memcg_reclaim_stat)
268 return;
269
270 memcg_reclaim_stat->recent_scanned[file]++;
271 if (rotated)
272 memcg_reclaim_stat->recent_rotated[file]++;
273}
274
275static void __activate_page(struct page *page, void *arg)
276{
277 struct zone *zone = page_zone(page);
278
279 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
280 int file = page_is_file_cache(page);
281 int lru = page_lru_base_type(page);
282 del_page_from_lru_list(zone, page, lru);
283
284 SetPageActive(page);
285 lru += LRU_ACTIVE;
286 add_page_to_lru_list(zone, page, lru);
287 __count_vm_event(PGACTIVATE);
288
289 update_page_reclaim_stat(zone, page, file, 1);
290 }
291}
292
293#ifdef CONFIG_SMP
294static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
295
296static void activate_page_drain(int cpu)
297{
298 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
299
300 if (pagevec_count(pvec))
301 pagevec_lru_move_fn(pvec, __activate_page, NULL);
302}
303
304void activate_page(struct page *page)
305{
306 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
307 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
308
309 page_cache_get(page);
310 if (!pagevec_add(pvec, page))
311 pagevec_lru_move_fn(pvec, __activate_page, NULL);
312 put_cpu_var(activate_page_pvecs);
313 }
314}
315
316#else
317static inline void activate_page_drain(int cpu)
318{
319}
320
321void activate_page(struct page *page)
322{
323 struct zone *zone = page_zone(page);
324
325 spin_lock_irq(&zone->lru_lock);
326 __activate_page(page, NULL);
327 spin_unlock_irq(&zone->lru_lock);
328}
329#endif
330
331/*
332 * Mark a page as having seen activity.
333 *
334 * inactive,unreferenced -> inactive,referenced
335 * inactive,referenced -> active,unreferenced
336 * active,unreferenced -> active,referenced
337 */
338void mark_page_accessed(struct page *page)
339{
340 if (!PageActive(page) && !PageUnevictable(page) &&
341 PageReferenced(page) && PageLRU(page)) {
342 activate_page(page);
343 ClearPageReferenced(page);
344 } else if (!PageReferenced(page)) {
345 SetPageReferenced(page);
346 }
347}
348
349EXPORT_SYMBOL(mark_page_accessed);
350
351void __lru_cache_add(struct page *page, enum lru_list lru)
352{
353 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
354
355 page_cache_get(page);
356 if (!pagevec_add(pvec, page))
357 ____pagevec_lru_add(pvec, lru);
358 put_cpu_var(lru_add_pvecs);
359}
360EXPORT_SYMBOL(__lru_cache_add);
361
362/**
363 * lru_cache_add_lru - add a page to a page list
364 * @page: the page to be added to the LRU.
365 * @lru: the LRU list to which the page is added.
366 */
367void lru_cache_add_lru(struct page *page, enum lru_list lru)
368{
369 if (PageActive(page)) {
370 VM_BUG_ON(PageUnevictable(page));
371 ClearPageActive(page);
372 } else if (PageUnevictable(page)) {
373 VM_BUG_ON(PageActive(page));
374 ClearPageUnevictable(page);
375 }
376
377 VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
378 __lru_cache_add(page, lru);
379}
380
381/**
382 * add_page_to_unevictable_list - add a page to the unevictable list
383 * @page: the page to be added to the unevictable list
384 *
385 * Add page directly to its zone's unevictable list. To avoid races with
386 * tasks that might be making the page evictable, through eg. munlock,
387 * munmap or exit, while it's not on the lru, we want to add the page
388 * while it's locked or otherwise "invisible" to other tasks. This is
389 * difficult to do when using the pagevec cache, so bypass that.
390 */
391void add_page_to_unevictable_list(struct page *page)
392{
393 struct zone *zone = page_zone(page);
394
395 spin_lock_irq(&zone->lru_lock);
396 SetPageUnevictable(page);
397 SetPageLRU(page);
398 add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
399 spin_unlock_irq(&zone->lru_lock);
400}
401
402/*
403 * If the page can not be invalidated, it is moved to the
404 * inactive list to speed up its reclaim. It is moved to the
405 * head of the list, rather than the tail, to give the flusher
406 * threads some time to write it out, as this is much more
407 * effective than the single-page writeout from reclaim.
408 *
409 * If the page isn't page_mapped and dirty/writeback, the page
410 * could reclaim asap using PG_reclaim.
411 *
412 * 1. active, mapped page -> none
413 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
414 * 3. inactive, mapped page -> none
415 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
416 * 5. inactive, clean -> inactive, tail
417 * 6. Others -> none
418 *
419 * In 4, why it moves inactive's head, the VM expects the page would
420 * be write it out by flusher threads as this is much more effective
421 * than the single-page writeout from reclaim.
422 */
423static void lru_deactivate_fn(struct page *page, void *arg)
424{
425 int lru, file;
426 bool active;
427 struct zone *zone = page_zone(page);
428
429 if (!PageLRU(page))
430 return;
431
432 if (PageUnevictable(page))
433 return;
434
435 /* Some processes are using the page */
436 if (page_mapped(page))
437 return;
438
439 active = PageActive(page);
440
441 file = page_is_file_cache(page);
442 lru = page_lru_base_type(page);
443 del_page_from_lru_list(zone, page, lru + active);
444 ClearPageActive(page);
445 ClearPageReferenced(page);
446 add_page_to_lru_list(zone, page, lru);
447
448 if (PageWriteback(page) || PageDirty(page)) {
449 /*
450 * PG_reclaim could be raced with end_page_writeback
451 * It can make readahead confusing. But race window
452 * is _really_ small and it's non-critical problem.
453 */
454 SetPageReclaim(page);
455 } else {
456 /*
457 * The page's writeback ends up during pagevec
458 * We moves tha page into tail of inactive.
459 */
460 list_move_tail(&page->lru, &zone->lru[lru].list);
461 mem_cgroup_rotate_reclaimable_page(page);
462 __count_vm_event(PGROTATED);
463 }
464
465 if (active)
466 __count_vm_event(PGDEACTIVATE);
467 update_page_reclaim_stat(zone, page, file, 0);
468}
469
470/*
471 * Drain pages out of the cpu's pagevecs.
472 * Either "cpu" is the current CPU, and preemption has already been
473 * disabled; or "cpu" is being hot-unplugged, and is already dead.
474 */
475static void drain_cpu_pagevecs(int cpu)
476{
477 struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
478 struct pagevec *pvec;
479 int lru;
480
481 for_each_lru(lru) {
482 pvec = &pvecs[lru - LRU_BASE];
483 if (pagevec_count(pvec))
484 ____pagevec_lru_add(pvec, lru);
485 }
486
487 pvec = &per_cpu(lru_rotate_pvecs, cpu);
488 if (pagevec_count(pvec)) {
489 unsigned long flags;
490
491 /* No harm done if a racing interrupt already did this */
492 local_irq_save(flags);
493 pagevec_move_tail(pvec);
494 local_irq_restore(flags);
495 }
496
497 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
498 if (pagevec_count(pvec))
499 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
500
501 activate_page_drain(cpu);
502}
503
504/**
505 * deactivate_page - forcefully deactivate a page
506 * @page: page to deactivate
507 *
508 * This function hints the VM that @page is a good reclaim candidate,
509 * for example if its invalidation fails due to the page being dirty
510 * or under writeback.
511 */
512void deactivate_page(struct page *page)
513{
514 /*
515 * In a workload with many unevictable page such as mprotect, unevictable
516 * page deactivation for accelerating reclaim is pointless.
517 */
518 if (PageUnevictable(page))
519 return;
520
521 if (likely(get_page_unless_zero(page))) {
522 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
523
524 if (!pagevec_add(pvec, page))
525 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
526 put_cpu_var(lru_deactivate_pvecs);
527 }
528}
529
530void lru_add_drain(void)
531{
532 drain_cpu_pagevecs(get_cpu());
533 put_cpu();
534}
535
536static void lru_add_drain_per_cpu(struct work_struct *dummy)
537{
538 lru_add_drain();
539}
540
541/*
542 * Returns 0 for success
543 */
544int lru_add_drain_all(void)
545{
546 return schedule_on_each_cpu(lru_add_drain_per_cpu);
547}
548
549/*
550 * Batched page_cache_release(). Decrement the reference count on all the
551 * passed pages. If it fell to zero then remove the page from the LRU and
552 * free it.
553 *
554 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
555 * for the remainder of the operation.
556 *
557 * The locking in this function is against shrink_inactive_list(): we recheck
558 * the page count inside the lock to see whether shrink_inactive_list()
559 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
560 * will free it.
561 */
562void release_pages(struct page **pages, int nr, int cold)
563{
564 int i;
565 struct pagevec pages_to_free;
566 struct zone *zone = NULL;
567 unsigned long uninitialized_var(flags);
568
569 pagevec_init(&pages_to_free, cold);
570 for (i = 0; i < nr; i++) {
571 struct page *page = pages[i];
572
573 if (unlikely(PageCompound(page))) {
574 if (zone) {
575 spin_unlock_irqrestore(&zone->lru_lock, flags);
576 zone = NULL;
577 }
578 put_compound_page(page);
579 continue;
580 }
581
582 if (!put_page_testzero(page))
583 continue;
584
585 if (PageLRU(page)) {
586 struct zone *pagezone = page_zone(page);
587
588 if (pagezone != zone) {
589 if (zone)
590 spin_unlock_irqrestore(&zone->lru_lock,
591 flags);
592 zone = pagezone;
593 spin_lock_irqsave(&zone->lru_lock, flags);
594 }
595 VM_BUG_ON(!PageLRU(page));
596 __ClearPageLRU(page);
597 del_page_from_lru(zone, page);
598 }
599
600 if (!pagevec_add(&pages_to_free, page)) {
601 if (zone) {
602 spin_unlock_irqrestore(&zone->lru_lock, flags);
603 zone = NULL;
604 }
605 __pagevec_free(&pages_to_free);
606 pagevec_reinit(&pages_to_free);
607 }
608 }
609 if (zone)
610 spin_unlock_irqrestore(&zone->lru_lock, flags);
611
612 pagevec_free(&pages_to_free);
613}
614EXPORT_SYMBOL(release_pages);
615
616/*
617 * The pages which we're about to release may be in the deferred lru-addition
618 * queues. That would prevent them from really being freed right now. That's
619 * OK from a correctness point of view but is inefficient - those pages may be
620 * cache-warm and we want to give them back to the page allocator ASAP.
621 *
622 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
623 * and __pagevec_lru_add_active() call release_pages() directly to avoid
624 * mutual recursion.
625 */
626void __pagevec_release(struct pagevec *pvec)
627{
628 lru_add_drain();
629 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
630 pagevec_reinit(pvec);
631}
632
633EXPORT_SYMBOL(__pagevec_release);
634
635/* used by __split_huge_page_refcount() */
636void lru_add_page_tail(struct zone* zone,
637 struct page *page, struct page *page_tail)
638{
639 int active;
640 enum lru_list lru;
641 const int file = 0;
642 struct list_head *head;
643
644 VM_BUG_ON(!PageHead(page));
645 VM_BUG_ON(PageCompound(page_tail));
646 VM_BUG_ON(PageLRU(page_tail));
647 VM_BUG_ON(!spin_is_locked(&zone->lru_lock));
648
649 SetPageLRU(page_tail);
650
651 if (page_evictable(page_tail, NULL)) {
652 if (PageActive(page)) {
653 SetPageActive(page_tail);
654 active = 1;
655 lru = LRU_ACTIVE_ANON;
656 } else {
657 active = 0;
658 lru = LRU_INACTIVE_ANON;
659 }
660 update_page_reclaim_stat(zone, page_tail, file, active);
661 if (likely(PageLRU(page)))
662 head = page->lru.prev;
663 else
664 head = &zone->lru[lru].list;
665 __add_page_to_lru_list(zone, page_tail, lru, head);
666 } else {
667 SetPageUnevictable(page_tail);
668 add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
669 }
670}
671
672static void ____pagevec_lru_add_fn(struct page *page, void *arg)
673{
674 enum lru_list lru = (enum lru_list)arg;
675 struct zone *zone = page_zone(page);
676 int file = is_file_lru(lru);
677 int active = is_active_lru(lru);
678
679 VM_BUG_ON(PageActive(page));
680 VM_BUG_ON(PageUnevictable(page));
681 VM_BUG_ON(PageLRU(page));
682
683 SetPageLRU(page);
684 if (active)
685 SetPageActive(page);
686 update_page_reclaim_stat(zone, page, file, active);
687 add_page_to_lru_list(zone, page, lru);
688}
689
690/*
691 * Add the passed pages to the LRU, then drop the caller's refcount
692 * on them. Reinitialises the caller's pagevec.
693 */
694void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
695{
696 VM_BUG_ON(is_unevictable_lru(lru));
697
698 pagevec_lru_move_fn(pvec, ____pagevec_lru_add_fn, (void *)lru);
699}
700
701EXPORT_SYMBOL(____pagevec_lru_add);
702
703/*
704 * Try to drop buffers from the pages in a pagevec
705 */
706void pagevec_strip(struct pagevec *pvec)
707{
708 int i;
709
710 for (i = 0; i < pagevec_count(pvec); i++) {
711 struct page *page = pvec->pages[i];
712
713 if (page_has_private(page) && trylock_page(page)) {
714 if (page_has_private(page))
715 try_to_release_page(page, 0);
716 unlock_page(page);
717 }
718 }
719}
720
721/**
722 * pagevec_lookup - gang pagecache lookup
723 * @pvec: Where the resulting pages are placed
724 * @mapping: The address_space to search
725 * @start: The starting page index
726 * @nr_pages: The maximum number of pages
727 *
728 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
729 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
730 * reference against the pages in @pvec.
731 *
732 * The search returns a group of mapping-contiguous pages with ascending
733 * indexes. There may be holes in the indices due to not-present pages.
734 *
735 * pagevec_lookup() returns the number of pages which were found.
736 */
737unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
738 pgoff_t start, unsigned nr_pages)
739{
740 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
741 return pagevec_count(pvec);
742}
743
744EXPORT_SYMBOL(pagevec_lookup);
745
746unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
747 pgoff_t *index, int tag, unsigned nr_pages)
748{
749 pvec->nr = find_get_pages_tag(mapping, index, tag,
750 nr_pages, pvec->pages);
751 return pagevec_count(pvec);
752}
753
754EXPORT_SYMBOL(pagevec_lookup_tag);
755
756/*
757 * Perform any setup for the swap system
758 */
759void __init swap_setup(void)
760{
761 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
762
763#ifdef CONFIG_SWAP
764 bdi_init(swapper_space.backing_dev_info);
765#endif
766
767 /* Use a smaller cluster for small-memory machines */
768 if (megs < 16)
769 page_cluster = 2;
770 else
771 page_cluster = 3;
772 /*
773 * Right now other parts of the system means that we
774 * _really_ don't want to cluster much more
775 */
776}
1/*
2 * linux/mm/swap.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
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.
14 */
15
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
34#include "internal.h"
35
36/* How many pages do we try to swap or page in/out together? */
37int page_cluster;
38
39static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
40static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
41static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
42
43/*
44 * This path almost never happens for VM activity - pages are normally
45 * freed via pagevecs. But it gets used by networking.
46 */
47static void __page_cache_release(struct page *page)
48{
49 if (PageLRU(page)) {
50 struct zone *zone = page_zone(page);
51 struct lruvec *lruvec;
52 unsigned long flags;
53
54 spin_lock_irqsave(&zone->lru_lock, flags);
55 lruvec = mem_cgroup_page_lruvec(page, zone);
56 VM_BUG_ON(!PageLRU(page));
57 __ClearPageLRU(page);
58 del_page_from_lru_list(page, lruvec, page_off_lru(page));
59 spin_unlock_irqrestore(&zone->lru_lock, flags);
60 }
61}
62
63static void __put_single_page(struct page *page)
64{
65 __page_cache_release(page);
66 free_hot_cold_page(page, 0);
67}
68
69static void __put_compound_page(struct page *page)
70{
71 compound_page_dtor *dtor;
72
73 __page_cache_release(page);
74 dtor = get_compound_page_dtor(page);
75 (*dtor)(page);
76}
77
78static void put_compound_page(struct page *page)
79{
80 if (unlikely(PageTail(page))) {
81 /* __split_huge_page_refcount can run under us */
82 struct page *page_head = compound_trans_head(page);
83
84 if (likely(page != page_head &&
85 get_page_unless_zero(page_head))) {
86 unsigned long flags;
87
88 /*
89 * THP can not break up slab pages so avoid taking
90 * compound_lock(). Slab performs non-atomic bit ops
91 * on page->flags for better performance. In particular
92 * slab_unlock() in slub used to be a hot path. It is
93 * still hot on arches that do not support
94 * this_cpu_cmpxchg_double().
95 */
96 if (PageSlab(page_head)) {
97 if (PageTail(page)) {
98 if (put_page_testzero(page_head))
99 VM_BUG_ON(1);
100
101 atomic_dec(&page->_mapcount);
102 goto skip_lock_tail;
103 } else
104 goto skip_lock;
105 }
106 /*
107 * page_head wasn't a dangling pointer but it
108 * may not be a head page anymore by the time
109 * we obtain the lock. That is ok as long as it
110 * can't be freed from under us.
111 */
112 flags = compound_lock_irqsave(page_head);
113 if (unlikely(!PageTail(page))) {
114 /* __split_huge_page_refcount run before us */
115 compound_unlock_irqrestore(page_head, flags);
116skip_lock:
117 if (put_page_testzero(page_head))
118 __put_single_page(page_head);
119out_put_single:
120 if (put_page_testzero(page))
121 __put_single_page(page);
122 return;
123 }
124 VM_BUG_ON(page_head != page->first_page);
125 /*
126 * We can release the refcount taken by
127 * get_page_unless_zero() now that
128 * __split_huge_page_refcount() is blocked on
129 * the compound_lock.
130 */
131 if (put_page_testzero(page_head))
132 VM_BUG_ON(1);
133 /* __split_huge_page_refcount will wait now */
134 VM_BUG_ON(page_mapcount(page) <= 0);
135 atomic_dec(&page->_mapcount);
136 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
137 VM_BUG_ON(atomic_read(&page->_count) != 0);
138 compound_unlock_irqrestore(page_head, flags);
139
140skip_lock_tail:
141 if (put_page_testzero(page_head)) {
142 if (PageHead(page_head))
143 __put_compound_page(page_head);
144 else
145 __put_single_page(page_head);
146 }
147 } else {
148 /* page_head is a dangling pointer */
149 VM_BUG_ON(PageTail(page));
150 goto out_put_single;
151 }
152 } else if (put_page_testzero(page)) {
153 if (PageHead(page))
154 __put_compound_page(page);
155 else
156 __put_single_page(page);
157 }
158}
159
160void put_page(struct page *page)
161{
162 if (unlikely(PageCompound(page)))
163 put_compound_page(page);
164 else if (put_page_testzero(page))
165 __put_single_page(page);
166}
167EXPORT_SYMBOL(put_page);
168
169/*
170 * This function is exported but must not be called by anything other
171 * than get_page(). It implements the slow path of get_page().
172 */
173bool __get_page_tail(struct page *page)
174{
175 /*
176 * This takes care of get_page() if run on a tail page
177 * returned by one of the get_user_pages/follow_page variants.
178 * get_user_pages/follow_page itself doesn't need the compound
179 * lock because it runs __get_page_tail_foll() under the
180 * proper PT lock that already serializes against
181 * split_huge_page().
182 */
183 unsigned long flags;
184 bool got = false;
185 struct page *page_head = compound_trans_head(page);
186
187 if (likely(page != page_head && get_page_unless_zero(page_head))) {
188
189 /* Ref to put_compound_page() comment. */
190 if (PageSlab(page_head)) {
191 if (likely(PageTail(page))) {
192 __get_page_tail_foll(page, false);
193 return true;
194 } else {
195 put_page(page_head);
196 return false;
197 }
198 }
199
200 /*
201 * page_head wasn't a dangling pointer but it
202 * may not be a head page anymore by the time
203 * we obtain the lock. That is ok as long as it
204 * can't be freed from under us.
205 */
206 flags = compound_lock_irqsave(page_head);
207 /* here __split_huge_page_refcount won't run anymore */
208 if (likely(PageTail(page))) {
209 __get_page_tail_foll(page, false);
210 got = true;
211 }
212 compound_unlock_irqrestore(page_head, flags);
213 if (unlikely(!got))
214 put_page(page_head);
215 }
216 return got;
217}
218EXPORT_SYMBOL(__get_page_tail);
219
220/**
221 * put_pages_list() - release a list of pages
222 * @pages: list of pages threaded on page->lru
223 *
224 * Release a list of pages which are strung together on page.lru. Currently
225 * used by read_cache_pages() and related error recovery code.
226 */
227void put_pages_list(struct list_head *pages)
228{
229 while (!list_empty(pages)) {
230 struct page *victim;
231
232 victim = list_entry(pages->prev, struct page, lru);
233 list_del(&victim->lru);
234 page_cache_release(victim);
235 }
236}
237EXPORT_SYMBOL(put_pages_list);
238
239static void pagevec_lru_move_fn(struct pagevec *pvec,
240 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
241 void *arg)
242{
243 int i;
244 struct zone *zone = NULL;
245 struct lruvec *lruvec;
246 unsigned long flags = 0;
247
248 for (i = 0; i < pagevec_count(pvec); i++) {
249 struct page *page = pvec->pages[i];
250 struct zone *pagezone = page_zone(page);
251
252 if (pagezone != zone) {
253 if (zone)
254 spin_unlock_irqrestore(&zone->lru_lock, flags);
255 zone = pagezone;
256 spin_lock_irqsave(&zone->lru_lock, flags);
257 }
258
259 lruvec = mem_cgroup_page_lruvec(page, zone);
260 (*move_fn)(page, lruvec, arg);
261 }
262 if (zone)
263 spin_unlock_irqrestore(&zone->lru_lock, flags);
264 release_pages(pvec->pages, pvec->nr, pvec->cold);
265 pagevec_reinit(pvec);
266}
267
268static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
269 void *arg)
270{
271 int *pgmoved = arg;
272
273 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
274 enum lru_list lru = page_lru_base_type(page);
275 list_move_tail(&page->lru, &lruvec->lists[lru]);
276 (*pgmoved)++;
277 }
278}
279
280/*
281 * pagevec_move_tail() must be called with IRQ disabled.
282 * Otherwise this may cause nasty races.
283 */
284static void pagevec_move_tail(struct pagevec *pvec)
285{
286 int pgmoved = 0;
287
288 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
289 __count_vm_events(PGROTATED, pgmoved);
290}
291
292/*
293 * Writeback is about to end against a page which has been marked for immediate
294 * reclaim. If it still appears to be reclaimable, move it to the tail of the
295 * inactive list.
296 */
297void rotate_reclaimable_page(struct page *page)
298{
299 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
300 !PageUnevictable(page) && PageLRU(page)) {
301 struct pagevec *pvec;
302 unsigned long flags;
303
304 page_cache_get(page);
305 local_irq_save(flags);
306 pvec = &__get_cpu_var(lru_rotate_pvecs);
307 if (!pagevec_add(pvec, page))
308 pagevec_move_tail(pvec);
309 local_irq_restore(flags);
310 }
311}
312
313static void update_page_reclaim_stat(struct lruvec *lruvec,
314 int file, int rotated)
315{
316 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
317
318 reclaim_stat->recent_scanned[file]++;
319 if (rotated)
320 reclaim_stat->recent_rotated[file]++;
321}
322
323static void __activate_page(struct page *page, struct lruvec *lruvec,
324 void *arg)
325{
326 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
327 int file = page_is_file_cache(page);
328 int lru = page_lru_base_type(page);
329
330 del_page_from_lru_list(page, lruvec, lru);
331 SetPageActive(page);
332 lru += LRU_ACTIVE;
333 add_page_to_lru_list(page, lruvec, lru);
334
335 __count_vm_event(PGACTIVATE);
336 update_page_reclaim_stat(lruvec, file, 1);
337 }
338}
339
340#ifdef CONFIG_SMP
341static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
342
343static void activate_page_drain(int cpu)
344{
345 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
346
347 if (pagevec_count(pvec))
348 pagevec_lru_move_fn(pvec, __activate_page, NULL);
349}
350
351void activate_page(struct page *page)
352{
353 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
354 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
355
356 page_cache_get(page);
357 if (!pagevec_add(pvec, page))
358 pagevec_lru_move_fn(pvec, __activate_page, NULL);
359 put_cpu_var(activate_page_pvecs);
360 }
361}
362
363#else
364static inline void activate_page_drain(int cpu)
365{
366}
367
368void activate_page(struct page *page)
369{
370 struct zone *zone = page_zone(page);
371
372 spin_lock_irq(&zone->lru_lock);
373 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
374 spin_unlock_irq(&zone->lru_lock);
375}
376#endif
377
378/*
379 * Mark a page as having seen activity.
380 *
381 * inactive,unreferenced -> inactive,referenced
382 * inactive,referenced -> active,unreferenced
383 * active,unreferenced -> active,referenced
384 */
385void mark_page_accessed(struct page *page)
386{
387 if (!PageActive(page) && !PageUnevictable(page) &&
388 PageReferenced(page) && PageLRU(page)) {
389 activate_page(page);
390 ClearPageReferenced(page);
391 } else if (!PageReferenced(page)) {
392 SetPageReferenced(page);
393 }
394}
395EXPORT_SYMBOL(mark_page_accessed);
396
397void __lru_cache_add(struct page *page, enum lru_list lru)
398{
399 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
400
401 page_cache_get(page);
402 if (!pagevec_add(pvec, page))
403 __pagevec_lru_add(pvec, lru);
404 put_cpu_var(lru_add_pvecs);
405}
406EXPORT_SYMBOL(__lru_cache_add);
407
408/**
409 * lru_cache_add_lru - add a page to a page list
410 * @page: the page to be added to the LRU.
411 * @lru: the LRU list to which the page is added.
412 */
413void lru_cache_add_lru(struct page *page, enum lru_list lru)
414{
415 if (PageActive(page)) {
416 VM_BUG_ON(PageUnevictable(page));
417 ClearPageActive(page);
418 } else if (PageUnevictable(page)) {
419 VM_BUG_ON(PageActive(page));
420 ClearPageUnevictable(page);
421 }
422
423 VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
424 __lru_cache_add(page, lru);
425}
426
427/**
428 * add_page_to_unevictable_list - add a page to the unevictable list
429 * @page: the page to be added to the unevictable list
430 *
431 * Add page directly to its zone's unevictable list. To avoid races with
432 * tasks that might be making the page evictable, through eg. munlock,
433 * munmap or exit, while it's not on the lru, we want to add the page
434 * while it's locked or otherwise "invisible" to other tasks. This is
435 * difficult to do when using the pagevec cache, so bypass that.
436 */
437void add_page_to_unevictable_list(struct page *page)
438{
439 struct zone *zone = page_zone(page);
440 struct lruvec *lruvec;
441
442 spin_lock_irq(&zone->lru_lock);
443 lruvec = mem_cgroup_page_lruvec(page, zone);
444 SetPageUnevictable(page);
445 SetPageLRU(page);
446 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
447 spin_unlock_irq(&zone->lru_lock);
448}
449
450/*
451 * If the page can not be invalidated, it is moved to the
452 * inactive list to speed up its reclaim. It is moved to the
453 * head of the list, rather than the tail, to give the flusher
454 * threads some time to write it out, as this is much more
455 * effective than the single-page writeout from reclaim.
456 *
457 * If the page isn't page_mapped and dirty/writeback, the page
458 * could reclaim asap using PG_reclaim.
459 *
460 * 1. active, mapped page -> none
461 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
462 * 3. inactive, mapped page -> none
463 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
464 * 5. inactive, clean -> inactive, tail
465 * 6. Others -> none
466 *
467 * In 4, why it moves inactive's head, the VM expects the page would
468 * be write it out by flusher threads as this is much more effective
469 * than the single-page writeout from reclaim.
470 */
471static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
472 void *arg)
473{
474 int lru, file;
475 bool active;
476
477 if (!PageLRU(page))
478 return;
479
480 if (PageUnevictable(page))
481 return;
482
483 /* Some processes are using the page */
484 if (page_mapped(page))
485 return;
486
487 active = PageActive(page);
488 file = page_is_file_cache(page);
489 lru = page_lru_base_type(page);
490
491 del_page_from_lru_list(page, lruvec, lru + active);
492 ClearPageActive(page);
493 ClearPageReferenced(page);
494 add_page_to_lru_list(page, lruvec, lru);
495
496 if (PageWriteback(page) || PageDirty(page)) {
497 /*
498 * PG_reclaim could be raced with end_page_writeback
499 * It can make readahead confusing. But race window
500 * is _really_ small and it's non-critical problem.
501 */
502 SetPageReclaim(page);
503 } else {
504 /*
505 * The page's writeback ends up during pagevec
506 * We moves tha page into tail of inactive.
507 */
508 list_move_tail(&page->lru, &lruvec->lists[lru]);
509 __count_vm_event(PGROTATED);
510 }
511
512 if (active)
513 __count_vm_event(PGDEACTIVATE);
514 update_page_reclaim_stat(lruvec, file, 0);
515}
516
517/*
518 * Drain pages out of the cpu's pagevecs.
519 * Either "cpu" is the current CPU, and preemption has already been
520 * disabled; or "cpu" is being hot-unplugged, and is already dead.
521 */
522void lru_add_drain_cpu(int cpu)
523{
524 struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
525 struct pagevec *pvec;
526 int lru;
527
528 for_each_lru(lru) {
529 pvec = &pvecs[lru - LRU_BASE];
530 if (pagevec_count(pvec))
531 __pagevec_lru_add(pvec, lru);
532 }
533
534 pvec = &per_cpu(lru_rotate_pvecs, cpu);
535 if (pagevec_count(pvec)) {
536 unsigned long flags;
537
538 /* No harm done if a racing interrupt already did this */
539 local_irq_save(flags);
540 pagevec_move_tail(pvec);
541 local_irq_restore(flags);
542 }
543
544 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
545 if (pagevec_count(pvec))
546 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
547
548 activate_page_drain(cpu);
549}
550
551/**
552 * deactivate_page - forcefully deactivate a page
553 * @page: page to deactivate
554 *
555 * This function hints the VM that @page is a good reclaim candidate,
556 * for example if its invalidation fails due to the page being dirty
557 * or under writeback.
558 */
559void deactivate_page(struct page *page)
560{
561 /*
562 * In a workload with many unevictable page such as mprotect, unevictable
563 * page deactivation for accelerating reclaim is pointless.
564 */
565 if (PageUnevictable(page))
566 return;
567
568 if (likely(get_page_unless_zero(page))) {
569 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
570
571 if (!pagevec_add(pvec, page))
572 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
573 put_cpu_var(lru_deactivate_pvecs);
574 }
575}
576
577void lru_add_drain(void)
578{
579 lru_add_drain_cpu(get_cpu());
580 put_cpu();
581}
582
583static void lru_add_drain_per_cpu(struct work_struct *dummy)
584{
585 lru_add_drain();
586}
587
588/*
589 * Returns 0 for success
590 */
591int lru_add_drain_all(void)
592{
593 return schedule_on_each_cpu(lru_add_drain_per_cpu);
594}
595
596/*
597 * Batched page_cache_release(). Decrement the reference count on all the
598 * passed pages. If it fell to zero then remove the page from the LRU and
599 * free it.
600 *
601 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
602 * for the remainder of the operation.
603 *
604 * The locking in this function is against shrink_inactive_list(): we recheck
605 * the page count inside the lock to see whether shrink_inactive_list()
606 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
607 * will free it.
608 */
609void release_pages(struct page **pages, int nr, int cold)
610{
611 int i;
612 LIST_HEAD(pages_to_free);
613 struct zone *zone = NULL;
614 struct lruvec *lruvec;
615 unsigned long uninitialized_var(flags);
616
617 for (i = 0; i < nr; i++) {
618 struct page *page = pages[i];
619
620 if (unlikely(PageCompound(page))) {
621 if (zone) {
622 spin_unlock_irqrestore(&zone->lru_lock, flags);
623 zone = NULL;
624 }
625 put_compound_page(page);
626 continue;
627 }
628
629 if (!put_page_testzero(page))
630 continue;
631
632 if (PageLRU(page)) {
633 struct zone *pagezone = page_zone(page);
634
635 if (pagezone != zone) {
636 if (zone)
637 spin_unlock_irqrestore(&zone->lru_lock,
638 flags);
639 zone = pagezone;
640 spin_lock_irqsave(&zone->lru_lock, flags);
641 }
642
643 lruvec = mem_cgroup_page_lruvec(page, zone);
644 VM_BUG_ON(!PageLRU(page));
645 __ClearPageLRU(page);
646 del_page_from_lru_list(page, lruvec, page_off_lru(page));
647 }
648
649 list_add(&page->lru, &pages_to_free);
650 }
651 if (zone)
652 spin_unlock_irqrestore(&zone->lru_lock, flags);
653
654 free_hot_cold_page_list(&pages_to_free, cold);
655}
656EXPORT_SYMBOL(release_pages);
657
658/*
659 * The pages which we're about to release may be in the deferred lru-addition
660 * queues. That would prevent them from really being freed right now. That's
661 * OK from a correctness point of view but is inefficient - those pages may be
662 * cache-warm and we want to give them back to the page allocator ASAP.
663 *
664 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
665 * and __pagevec_lru_add_active() call release_pages() directly to avoid
666 * mutual recursion.
667 */
668void __pagevec_release(struct pagevec *pvec)
669{
670 lru_add_drain();
671 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
672 pagevec_reinit(pvec);
673}
674EXPORT_SYMBOL(__pagevec_release);
675
676#ifdef CONFIG_TRANSPARENT_HUGEPAGE
677/* used by __split_huge_page_refcount() */
678void lru_add_page_tail(struct page *page, struct page *page_tail,
679 struct lruvec *lruvec)
680{
681 int uninitialized_var(active);
682 enum lru_list lru;
683 const int file = 0;
684
685 VM_BUG_ON(!PageHead(page));
686 VM_BUG_ON(PageCompound(page_tail));
687 VM_BUG_ON(PageLRU(page_tail));
688 VM_BUG_ON(NR_CPUS != 1 &&
689 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
690
691 SetPageLRU(page_tail);
692
693 if (page_evictable(page_tail, NULL)) {
694 if (PageActive(page)) {
695 SetPageActive(page_tail);
696 active = 1;
697 lru = LRU_ACTIVE_ANON;
698 } else {
699 active = 0;
700 lru = LRU_INACTIVE_ANON;
701 }
702 } else {
703 SetPageUnevictable(page_tail);
704 lru = LRU_UNEVICTABLE;
705 }
706
707 if (likely(PageLRU(page)))
708 list_add_tail(&page_tail->lru, &page->lru);
709 else {
710 struct list_head *list_head;
711 /*
712 * Head page has not yet been counted, as an hpage,
713 * so we must account for each subpage individually.
714 *
715 * Use the standard add function to put page_tail on the list,
716 * but then correct its position so they all end up in order.
717 */
718 add_page_to_lru_list(page_tail, lruvec, lru);
719 list_head = page_tail->lru.prev;
720 list_move_tail(&page_tail->lru, list_head);
721 }
722
723 if (!PageUnevictable(page))
724 update_page_reclaim_stat(lruvec, file, active);
725}
726#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
727
728static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
729 void *arg)
730{
731 enum lru_list lru = (enum lru_list)arg;
732 int file = is_file_lru(lru);
733 int active = is_active_lru(lru);
734
735 VM_BUG_ON(PageActive(page));
736 VM_BUG_ON(PageUnevictable(page));
737 VM_BUG_ON(PageLRU(page));
738
739 SetPageLRU(page);
740 if (active)
741 SetPageActive(page);
742 add_page_to_lru_list(page, lruvec, lru);
743 update_page_reclaim_stat(lruvec, file, active);
744}
745
746/*
747 * Add the passed pages to the LRU, then drop the caller's refcount
748 * on them. Reinitialises the caller's pagevec.
749 */
750void __pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
751{
752 VM_BUG_ON(is_unevictable_lru(lru));
753
754 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, (void *)lru);
755}
756EXPORT_SYMBOL(__pagevec_lru_add);
757
758/**
759 * pagevec_lookup - gang pagecache lookup
760 * @pvec: Where the resulting pages are placed
761 * @mapping: The address_space to search
762 * @start: The starting page index
763 * @nr_pages: The maximum number of pages
764 *
765 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
766 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
767 * reference against the pages in @pvec.
768 *
769 * The search returns a group of mapping-contiguous pages with ascending
770 * indexes. There may be holes in the indices due to not-present pages.
771 *
772 * pagevec_lookup() returns the number of pages which were found.
773 */
774unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
775 pgoff_t start, unsigned nr_pages)
776{
777 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
778 return pagevec_count(pvec);
779}
780EXPORT_SYMBOL(pagevec_lookup);
781
782unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
783 pgoff_t *index, int tag, unsigned nr_pages)
784{
785 pvec->nr = find_get_pages_tag(mapping, index, tag,
786 nr_pages, pvec->pages);
787 return pagevec_count(pvec);
788}
789EXPORT_SYMBOL(pagevec_lookup_tag);
790
791/*
792 * Perform any setup for the swap system
793 */
794void __init swap_setup(void)
795{
796 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
797
798#ifdef CONFIG_SWAP
799 bdi_init(swapper_space.backing_dev_info);
800#endif
801
802 /* Use a smaller cluster for small-memory machines */
803 if (megs < 16)
804 page_cluster = 2;
805 else
806 page_cluster = 3;
807 /*
808 * Right now other parts of the system means that we
809 * _really_ don't want to cluster much more
810 */
811}