Loading...
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/memremap.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#include <linux/uio.h>
35#include <linux/hugetlb.h>
36#include <linux/page_idle.h>
37
38#include "internal.h"
39
40#define CREATE_TRACE_POINTS
41#include <trace/events/pagemap.h>
42
43/* How many pages do we try to swap or page in/out together? */
44int page_cluster;
45
46static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
47static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
48static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
49static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
50
51/*
52 * This path almost never happens for VM activity - pages are normally
53 * freed via pagevecs. But it gets used by networking.
54 */
55static void __page_cache_release(struct page *page)
56{
57 if (PageLRU(page)) {
58 struct zone *zone = page_zone(page);
59 struct lruvec *lruvec;
60 unsigned long flags;
61
62 spin_lock_irqsave(&zone->lru_lock, flags);
63 lruvec = mem_cgroup_page_lruvec(page, zone);
64 VM_BUG_ON_PAGE(!PageLRU(page), page);
65 __ClearPageLRU(page);
66 del_page_from_lru_list(page, lruvec, page_off_lru(page));
67 spin_unlock_irqrestore(&zone->lru_lock, flags);
68 }
69 mem_cgroup_uncharge(page);
70}
71
72static void __put_single_page(struct page *page)
73{
74 __page_cache_release(page);
75 free_hot_cold_page(page, false);
76}
77
78static void __put_compound_page(struct page *page)
79{
80 compound_page_dtor *dtor;
81
82 /*
83 * __page_cache_release() is supposed to be called for thp, not for
84 * hugetlb. This is because hugetlb page does never have PageLRU set
85 * (it's never listed to any LRU lists) and no memcg routines should
86 * be called for hugetlb (it has a separate hugetlb_cgroup.)
87 */
88 if (!PageHuge(page))
89 __page_cache_release(page);
90 dtor = get_compound_page_dtor(page);
91 (*dtor)(page);
92}
93
94void __put_page(struct page *page)
95{
96 if (unlikely(PageCompound(page)))
97 __put_compound_page(page);
98 else
99 __put_single_page(page);
100}
101EXPORT_SYMBOL(__put_page);
102
103/**
104 * put_pages_list() - release a list of pages
105 * @pages: list of pages threaded on page->lru
106 *
107 * Release a list of pages which are strung together on page.lru. Currently
108 * used by read_cache_pages() and related error recovery code.
109 */
110void put_pages_list(struct list_head *pages)
111{
112 while (!list_empty(pages)) {
113 struct page *victim;
114
115 victim = list_entry(pages->prev, struct page, lru);
116 list_del(&victim->lru);
117 put_page(victim);
118 }
119}
120EXPORT_SYMBOL(put_pages_list);
121
122/*
123 * get_kernel_pages() - pin kernel pages in memory
124 * @kiov: An array of struct kvec structures
125 * @nr_segs: number of segments to pin
126 * @write: pinning for read/write, currently ignored
127 * @pages: array that receives pointers to the pages pinned.
128 * Should be at least nr_segs long.
129 *
130 * Returns number of pages pinned. This may be fewer than the number
131 * requested. If nr_pages is 0 or negative, returns 0. If no pages
132 * were pinned, returns -errno. Each page returned must be released
133 * with a put_page() call when it is finished with.
134 */
135int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
136 struct page **pages)
137{
138 int seg;
139
140 for (seg = 0; seg < nr_segs; seg++) {
141 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
142 return seg;
143
144 pages[seg] = kmap_to_page(kiov[seg].iov_base);
145 get_page(pages[seg]);
146 }
147
148 return seg;
149}
150EXPORT_SYMBOL_GPL(get_kernel_pages);
151
152/*
153 * get_kernel_page() - pin a kernel page in memory
154 * @start: starting kernel address
155 * @write: pinning for read/write, currently ignored
156 * @pages: array that receives pointer to the page pinned.
157 * Must be at least nr_segs long.
158 *
159 * Returns 1 if page is pinned. If the page was not pinned, returns
160 * -errno. The page returned must be released with a put_page() call
161 * when it is finished with.
162 */
163int get_kernel_page(unsigned long start, int write, struct page **pages)
164{
165 const struct kvec kiov = {
166 .iov_base = (void *)start,
167 .iov_len = PAGE_SIZE
168 };
169
170 return get_kernel_pages(&kiov, 1, write, pages);
171}
172EXPORT_SYMBOL_GPL(get_kernel_page);
173
174static void pagevec_lru_move_fn(struct pagevec *pvec,
175 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
176 void *arg)
177{
178 int i;
179 struct zone *zone = NULL;
180 struct lruvec *lruvec;
181 unsigned long flags = 0;
182
183 for (i = 0; i < pagevec_count(pvec); i++) {
184 struct page *page = pvec->pages[i];
185 struct zone *pagezone = page_zone(page);
186
187 if (pagezone != zone) {
188 if (zone)
189 spin_unlock_irqrestore(&zone->lru_lock, flags);
190 zone = pagezone;
191 spin_lock_irqsave(&zone->lru_lock, flags);
192 }
193
194 lruvec = mem_cgroup_page_lruvec(page, zone);
195 (*move_fn)(page, lruvec, arg);
196 }
197 if (zone)
198 spin_unlock_irqrestore(&zone->lru_lock, flags);
199 release_pages(pvec->pages, pvec->nr, pvec->cold);
200 pagevec_reinit(pvec);
201}
202
203static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
204 void *arg)
205{
206 int *pgmoved = arg;
207
208 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
209 enum lru_list lru = page_lru_base_type(page);
210 list_move_tail(&page->lru, &lruvec->lists[lru]);
211 (*pgmoved)++;
212 }
213}
214
215/*
216 * pagevec_move_tail() must be called with IRQ disabled.
217 * Otherwise this may cause nasty races.
218 */
219static void pagevec_move_tail(struct pagevec *pvec)
220{
221 int pgmoved = 0;
222
223 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
224 __count_vm_events(PGROTATED, pgmoved);
225}
226
227/*
228 * Writeback is about to end against a page which has been marked for immediate
229 * reclaim. If it still appears to be reclaimable, move it to the tail of the
230 * inactive list.
231 */
232void rotate_reclaimable_page(struct page *page)
233{
234 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
235 !PageUnevictable(page) && PageLRU(page)) {
236 struct pagevec *pvec;
237 unsigned long flags;
238
239 get_page(page);
240 local_irq_save(flags);
241 pvec = this_cpu_ptr(&lru_rotate_pvecs);
242 if (!pagevec_add(pvec, page))
243 pagevec_move_tail(pvec);
244 local_irq_restore(flags);
245 }
246}
247
248static void update_page_reclaim_stat(struct lruvec *lruvec,
249 int file, int rotated)
250{
251 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
252
253 reclaim_stat->recent_scanned[file]++;
254 if (rotated)
255 reclaim_stat->recent_rotated[file]++;
256}
257
258static void __activate_page(struct page *page, struct lruvec *lruvec,
259 void *arg)
260{
261 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
262 int file = page_is_file_cache(page);
263 int lru = page_lru_base_type(page);
264
265 del_page_from_lru_list(page, lruvec, lru);
266 SetPageActive(page);
267 lru += LRU_ACTIVE;
268 add_page_to_lru_list(page, lruvec, lru);
269 trace_mm_lru_activate(page);
270
271 __count_vm_event(PGACTIVATE);
272 update_page_reclaim_stat(lruvec, file, 1);
273 }
274}
275
276#ifdef CONFIG_SMP
277static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
278
279static void activate_page_drain(int cpu)
280{
281 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
282
283 if (pagevec_count(pvec))
284 pagevec_lru_move_fn(pvec, __activate_page, NULL);
285}
286
287static bool need_activate_page_drain(int cpu)
288{
289 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
290}
291
292void activate_page(struct page *page)
293{
294 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
295 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
296
297 get_page(page);
298 if (!pagevec_add(pvec, page))
299 pagevec_lru_move_fn(pvec, __activate_page, NULL);
300 put_cpu_var(activate_page_pvecs);
301 }
302}
303
304#else
305static inline void activate_page_drain(int cpu)
306{
307}
308
309static bool need_activate_page_drain(int cpu)
310{
311 return false;
312}
313
314void activate_page(struct page *page)
315{
316 struct zone *zone = page_zone(page);
317
318 spin_lock_irq(&zone->lru_lock);
319 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
320 spin_unlock_irq(&zone->lru_lock);
321}
322#endif
323
324static void __lru_cache_activate_page(struct page *page)
325{
326 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
327 int i;
328
329 /*
330 * Search backwards on the optimistic assumption that the page being
331 * activated has just been added to this pagevec. Note that only
332 * the local pagevec is examined as a !PageLRU page could be in the
333 * process of being released, reclaimed, migrated or on a remote
334 * pagevec that is currently being drained. Furthermore, marking
335 * a remote pagevec's page PageActive potentially hits a race where
336 * a page is marked PageActive just after it is added to the inactive
337 * list causing accounting errors and BUG_ON checks to trigger.
338 */
339 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
340 struct page *pagevec_page = pvec->pages[i];
341
342 if (pagevec_page == page) {
343 SetPageActive(page);
344 break;
345 }
346 }
347
348 put_cpu_var(lru_add_pvec);
349}
350
351/*
352 * Mark a page as having seen activity.
353 *
354 * inactive,unreferenced -> inactive,referenced
355 * inactive,referenced -> active,unreferenced
356 * active,unreferenced -> active,referenced
357 *
358 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
359 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
360 */
361void mark_page_accessed(struct page *page)
362{
363 page = compound_head(page);
364 if (!PageActive(page) && !PageUnevictable(page) &&
365 PageReferenced(page)) {
366
367 /*
368 * If the page is on the LRU, queue it for activation via
369 * activate_page_pvecs. Otherwise, assume the page is on a
370 * pagevec, mark it active and it'll be moved to the active
371 * LRU on the next drain.
372 */
373 if (PageLRU(page))
374 activate_page(page);
375 else
376 __lru_cache_activate_page(page);
377 ClearPageReferenced(page);
378 if (page_is_file_cache(page))
379 workingset_activation(page);
380 } else if (!PageReferenced(page)) {
381 SetPageReferenced(page);
382 }
383 if (page_is_idle(page))
384 clear_page_idle(page);
385}
386EXPORT_SYMBOL(mark_page_accessed);
387
388static void __lru_cache_add(struct page *page)
389{
390 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
391
392 get_page(page);
393 if (!pagevec_space(pvec))
394 __pagevec_lru_add(pvec);
395 pagevec_add(pvec, page);
396 put_cpu_var(lru_add_pvec);
397}
398
399/**
400 * lru_cache_add: add a page to the page lists
401 * @page: the page to add
402 */
403void lru_cache_add_anon(struct page *page)
404{
405 if (PageActive(page))
406 ClearPageActive(page);
407 __lru_cache_add(page);
408}
409
410void lru_cache_add_file(struct page *page)
411{
412 if (PageActive(page))
413 ClearPageActive(page);
414 __lru_cache_add(page);
415}
416EXPORT_SYMBOL(lru_cache_add_file);
417
418/**
419 * lru_cache_add - add a page to a page list
420 * @page: the page to be added to the LRU.
421 *
422 * Queue the page for addition to the LRU via pagevec. The decision on whether
423 * to add the page to the [in]active [file|anon] list is deferred until the
424 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
425 * have the page added to the active list using mark_page_accessed().
426 */
427void lru_cache_add(struct page *page)
428{
429 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
430 VM_BUG_ON_PAGE(PageLRU(page), page);
431 __lru_cache_add(page);
432}
433
434/**
435 * add_page_to_unevictable_list - add a page to the unevictable list
436 * @page: the page to be added to the unevictable list
437 *
438 * Add page directly to its zone's unevictable list. To avoid races with
439 * tasks that might be making the page evictable, through eg. munlock,
440 * munmap or exit, while it's not on the lru, we want to add the page
441 * while it's locked or otherwise "invisible" to other tasks. This is
442 * difficult to do when using the pagevec cache, so bypass that.
443 */
444void add_page_to_unevictable_list(struct page *page)
445{
446 struct zone *zone = page_zone(page);
447 struct lruvec *lruvec;
448
449 spin_lock_irq(&zone->lru_lock);
450 lruvec = mem_cgroup_page_lruvec(page, zone);
451 ClearPageActive(page);
452 SetPageUnevictable(page);
453 SetPageLRU(page);
454 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
455 spin_unlock_irq(&zone->lru_lock);
456}
457
458/**
459 * lru_cache_add_active_or_unevictable
460 * @page: the page to be added to LRU
461 * @vma: vma in which page is mapped for determining reclaimability
462 *
463 * Place @page on the active or unevictable LRU list, depending on its
464 * evictability. Note that if the page is not evictable, it goes
465 * directly back onto it's zone's unevictable list, it does NOT use a
466 * per cpu pagevec.
467 */
468void lru_cache_add_active_or_unevictable(struct page *page,
469 struct vm_area_struct *vma)
470{
471 VM_BUG_ON_PAGE(PageLRU(page), page);
472
473 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
474 SetPageActive(page);
475 lru_cache_add(page);
476 return;
477 }
478
479 if (!TestSetPageMlocked(page)) {
480 /*
481 * We use the irq-unsafe __mod_zone_page_stat because this
482 * counter is not modified from interrupt context, and the pte
483 * lock is held(spinlock), which implies preemption disabled.
484 */
485 __mod_zone_page_state(page_zone(page), NR_MLOCK,
486 hpage_nr_pages(page));
487 count_vm_event(UNEVICTABLE_PGMLOCKED);
488 }
489 add_page_to_unevictable_list(page);
490}
491
492/*
493 * If the page can not be invalidated, it is moved to the
494 * inactive list to speed up its reclaim. It is moved to the
495 * head of the list, rather than the tail, to give the flusher
496 * threads some time to write it out, as this is much more
497 * effective than the single-page writeout from reclaim.
498 *
499 * If the page isn't page_mapped and dirty/writeback, the page
500 * could reclaim asap using PG_reclaim.
501 *
502 * 1. active, mapped page -> none
503 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
504 * 3. inactive, mapped page -> none
505 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
506 * 5. inactive, clean -> inactive, tail
507 * 6. Others -> none
508 *
509 * In 4, why it moves inactive's head, the VM expects the page would
510 * be write it out by flusher threads as this is much more effective
511 * than the single-page writeout from reclaim.
512 */
513static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
514 void *arg)
515{
516 int lru, file;
517 bool active;
518
519 if (!PageLRU(page))
520 return;
521
522 if (PageUnevictable(page))
523 return;
524
525 /* Some processes are using the page */
526 if (page_mapped(page))
527 return;
528
529 active = PageActive(page);
530 file = page_is_file_cache(page);
531 lru = page_lru_base_type(page);
532
533 del_page_from_lru_list(page, lruvec, lru + active);
534 ClearPageActive(page);
535 ClearPageReferenced(page);
536 add_page_to_lru_list(page, lruvec, lru);
537
538 if (PageWriteback(page) || PageDirty(page)) {
539 /*
540 * PG_reclaim could be raced with end_page_writeback
541 * It can make readahead confusing. But race window
542 * is _really_ small and it's non-critical problem.
543 */
544 SetPageReclaim(page);
545 } else {
546 /*
547 * The page's writeback ends up during pagevec
548 * We moves tha page into tail of inactive.
549 */
550 list_move_tail(&page->lru, &lruvec->lists[lru]);
551 __count_vm_event(PGROTATED);
552 }
553
554 if (active)
555 __count_vm_event(PGDEACTIVATE);
556 update_page_reclaim_stat(lruvec, file, 0);
557}
558
559
560static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
561 void *arg)
562{
563 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
564 int file = page_is_file_cache(page);
565 int lru = page_lru_base_type(page);
566
567 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
568 ClearPageActive(page);
569 ClearPageReferenced(page);
570 add_page_to_lru_list(page, lruvec, lru);
571
572 __count_vm_event(PGDEACTIVATE);
573 update_page_reclaim_stat(lruvec, file, 0);
574 }
575}
576
577/*
578 * Drain pages out of the cpu's pagevecs.
579 * Either "cpu" is the current CPU, and preemption has already been
580 * disabled; or "cpu" is being hot-unplugged, and is already dead.
581 */
582void lru_add_drain_cpu(int cpu)
583{
584 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
585
586 if (pagevec_count(pvec))
587 __pagevec_lru_add(pvec);
588
589 pvec = &per_cpu(lru_rotate_pvecs, cpu);
590 if (pagevec_count(pvec)) {
591 unsigned long flags;
592
593 /* No harm done if a racing interrupt already did this */
594 local_irq_save(flags);
595 pagevec_move_tail(pvec);
596 local_irq_restore(flags);
597 }
598
599 pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
600 if (pagevec_count(pvec))
601 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
602
603 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
604 if (pagevec_count(pvec))
605 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
606
607 activate_page_drain(cpu);
608}
609
610/**
611 * deactivate_file_page - forcefully deactivate a file page
612 * @page: page to deactivate
613 *
614 * This function hints the VM that @page is a good reclaim candidate,
615 * for example if its invalidation fails due to the page being dirty
616 * or under writeback.
617 */
618void deactivate_file_page(struct page *page)
619{
620 /*
621 * In a workload with many unevictable page such as mprotect,
622 * unevictable page deactivation for accelerating reclaim is pointless.
623 */
624 if (PageUnevictable(page))
625 return;
626
627 if (likely(get_page_unless_zero(page))) {
628 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
629
630 if (!pagevec_add(pvec, page))
631 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
632 put_cpu_var(lru_deactivate_file_pvecs);
633 }
634}
635
636/**
637 * deactivate_page - deactivate a page
638 * @page: page to deactivate
639 *
640 * deactivate_page() moves @page to the inactive list if @page was on the active
641 * list and was not an unevictable page. This is done to accelerate the reclaim
642 * of @page.
643 */
644void deactivate_page(struct page *page)
645{
646 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
647 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
648
649 get_page(page);
650 if (!pagevec_add(pvec, page))
651 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
652 put_cpu_var(lru_deactivate_pvecs);
653 }
654}
655
656void lru_add_drain(void)
657{
658 lru_add_drain_cpu(get_cpu());
659 put_cpu();
660}
661
662static void lru_add_drain_per_cpu(struct work_struct *dummy)
663{
664 lru_add_drain();
665}
666
667static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
668
669void lru_add_drain_all(void)
670{
671 static DEFINE_MUTEX(lock);
672 static struct cpumask has_work;
673 int cpu;
674
675 mutex_lock(&lock);
676 get_online_cpus();
677 cpumask_clear(&has_work);
678
679 for_each_online_cpu(cpu) {
680 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
681
682 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
683 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
684 pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
685 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
686 need_activate_page_drain(cpu)) {
687 INIT_WORK(work, lru_add_drain_per_cpu);
688 schedule_work_on(cpu, work);
689 cpumask_set_cpu(cpu, &has_work);
690 }
691 }
692
693 for_each_cpu(cpu, &has_work)
694 flush_work(&per_cpu(lru_add_drain_work, cpu));
695
696 put_online_cpus();
697 mutex_unlock(&lock);
698}
699
700/**
701 * release_pages - batched put_page()
702 * @pages: array of pages to release
703 * @nr: number of pages
704 * @cold: whether the pages are cache cold
705 *
706 * Decrement the reference count on all the pages in @pages. If it
707 * fell to zero, remove the page from the LRU and free it.
708 */
709void release_pages(struct page **pages, int nr, bool cold)
710{
711 int i;
712 LIST_HEAD(pages_to_free);
713 struct zone *zone = NULL;
714 struct lruvec *lruvec;
715 unsigned long uninitialized_var(flags);
716 unsigned int uninitialized_var(lock_batch);
717
718 for (i = 0; i < nr; i++) {
719 struct page *page = pages[i];
720
721 /*
722 * Make sure the IRQ-safe lock-holding time does not get
723 * excessive with a continuous string of pages from the
724 * same zone. The lock is held only if zone != NULL.
725 */
726 if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
727 spin_unlock_irqrestore(&zone->lru_lock, flags);
728 zone = NULL;
729 }
730
731 if (is_huge_zero_page(page)) {
732 put_huge_zero_page();
733 continue;
734 }
735
736 page = compound_head(page);
737 if (!put_page_testzero(page))
738 continue;
739
740 if (PageCompound(page)) {
741 if (zone) {
742 spin_unlock_irqrestore(&zone->lru_lock, flags);
743 zone = NULL;
744 }
745 __put_compound_page(page);
746 continue;
747 }
748
749 if (PageLRU(page)) {
750 struct zone *pagezone = page_zone(page);
751
752 if (pagezone != zone) {
753 if (zone)
754 spin_unlock_irqrestore(&zone->lru_lock,
755 flags);
756 lock_batch = 0;
757 zone = pagezone;
758 spin_lock_irqsave(&zone->lru_lock, flags);
759 }
760
761 lruvec = mem_cgroup_page_lruvec(page, zone);
762 VM_BUG_ON_PAGE(!PageLRU(page), page);
763 __ClearPageLRU(page);
764 del_page_from_lru_list(page, lruvec, page_off_lru(page));
765 }
766
767 /* Clear Active bit in case of parallel mark_page_accessed */
768 __ClearPageActive(page);
769
770 list_add(&page->lru, &pages_to_free);
771 }
772 if (zone)
773 spin_unlock_irqrestore(&zone->lru_lock, flags);
774
775 mem_cgroup_uncharge_list(&pages_to_free);
776 free_hot_cold_page_list(&pages_to_free, cold);
777}
778EXPORT_SYMBOL(release_pages);
779
780/*
781 * The pages which we're about to release may be in the deferred lru-addition
782 * queues. That would prevent them from really being freed right now. That's
783 * OK from a correctness point of view but is inefficient - those pages may be
784 * cache-warm and we want to give them back to the page allocator ASAP.
785 *
786 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
787 * and __pagevec_lru_add_active() call release_pages() directly to avoid
788 * mutual recursion.
789 */
790void __pagevec_release(struct pagevec *pvec)
791{
792 lru_add_drain();
793 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
794 pagevec_reinit(pvec);
795}
796EXPORT_SYMBOL(__pagevec_release);
797
798#ifdef CONFIG_TRANSPARENT_HUGEPAGE
799/* used by __split_huge_page_refcount() */
800void lru_add_page_tail(struct page *page, struct page *page_tail,
801 struct lruvec *lruvec, struct list_head *list)
802{
803 const int file = 0;
804
805 VM_BUG_ON_PAGE(!PageHead(page), page);
806 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
807 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
808 VM_BUG_ON(NR_CPUS != 1 &&
809 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
810
811 if (!list)
812 SetPageLRU(page_tail);
813
814 if (likely(PageLRU(page)))
815 list_add_tail(&page_tail->lru, &page->lru);
816 else if (list) {
817 /* page reclaim is reclaiming a huge page */
818 get_page(page_tail);
819 list_add_tail(&page_tail->lru, list);
820 } else {
821 struct list_head *list_head;
822 /*
823 * Head page has not yet been counted, as an hpage,
824 * so we must account for each subpage individually.
825 *
826 * Use the standard add function to put page_tail on the list,
827 * but then correct its position so they all end up in order.
828 */
829 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
830 list_head = page_tail->lru.prev;
831 list_move_tail(&page_tail->lru, list_head);
832 }
833
834 if (!PageUnevictable(page))
835 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
836}
837#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
838
839static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
840 void *arg)
841{
842 int file = page_is_file_cache(page);
843 int active = PageActive(page);
844 enum lru_list lru = page_lru(page);
845
846 VM_BUG_ON_PAGE(PageLRU(page), page);
847
848 SetPageLRU(page);
849 add_page_to_lru_list(page, lruvec, lru);
850 update_page_reclaim_stat(lruvec, file, active);
851 trace_mm_lru_insertion(page, lru);
852}
853
854/*
855 * Add the passed pages to the LRU, then drop the caller's refcount
856 * on them. Reinitialises the caller's pagevec.
857 */
858void __pagevec_lru_add(struct pagevec *pvec)
859{
860 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
861}
862EXPORT_SYMBOL(__pagevec_lru_add);
863
864/**
865 * pagevec_lookup_entries - gang pagecache lookup
866 * @pvec: Where the resulting entries are placed
867 * @mapping: The address_space to search
868 * @start: The starting entry index
869 * @nr_entries: The maximum number of entries
870 * @indices: The cache indices corresponding to the entries in @pvec
871 *
872 * pagevec_lookup_entries() will search for and return a group of up
873 * to @nr_entries pages and shadow entries in the mapping. All
874 * entries are placed in @pvec. pagevec_lookup_entries() takes a
875 * reference against actual pages in @pvec.
876 *
877 * The search returns a group of mapping-contiguous entries with
878 * ascending indexes. There may be holes in the indices due to
879 * not-present entries.
880 *
881 * pagevec_lookup_entries() returns the number of entries which were
882 * found.
883 */
884unsigned pagevec_lookup_entries(struct pagevec *pvec,
885 struct address_space *mapping,
886 pgoff_t start, unsigned nr_pages,
887 pgoff_t *indices)
888{
889 pvec->nr = find_get_entries(mapping, start, nr_pages,
890 pvec->pages, indices);
891 return pagevec_count(pvec);
892}
893
894/**
895 * pagevec_remove_exceptionals - pagevec exceptionals pruning
896 * @pvec: The pagevec to prune
897 *
898 * pagevec_lookup_entries() fills both pages and exceptional radix
899 * tree entries into the pagevec. This function prunes all
900 * exceptionals from @pvec without leaving holes, so that it can be
901 * passed on to page-only pagevec operations.
902 */
903void pagevec_remove_exceptionals(struct pagevec *pvec)
904{
905 int i, j;
906
907 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
908 struct page *page = pvec->pages[i];
909 if (!radix_tree_exceptional_entry(page))
910 pvec->pages[j++] = page;
911 }
912 pvec->nr = j;
913}
914
915/**
916 * pagevec_lookup - gang pagecache lookup
917 * @pvec: Where the resulting pages are placed
918 * @mapping: The address_space to search
919 * @start: The starting page index
920 * @nr_pages: The maximum number of pages
921 *
922 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
923 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
924 * reference against the pages in @pvec.
925 *
926 * The search returns a group of mapping-contiguous pages with ascending
927 * indexes. There may be holes in the indices due to not-present pages.
928 *
929 * pagevec_lookup() returns the number of pages which were found.
930 */
931unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
932 pgoff_t start, unsigned nr_pages)
933{
934 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
935 return pagevec_count(pvec);
936}
937EXPORT_SYMBOL(pagevec_lookup);
938
939unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
940 pgoff_t *index, int tag, unsigned nr_pages)
941{
942 pvec->nr = find_get_pages_tag(mapping, index, tag,
943 nr_pages, pvec->pages);
944 return pagevec_count(pvec);
945}
946EXPORT_SYMBOL(pagevec_lookup_tag);
947
948/*
949 * Perform any setup for the swap system
950 */
951void __init swap_setup(void)
952{
953 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
954#ifdef CONFIG_SWAP
955 int i;
956
957 for (i = 0; i < MAX_SWAPFILES; i++)
958 spin_lock_init(&swapper_spaces[i].tree_lock);
959#endif
960
961 /* Use a smaller cluster for small-memory machines */
962 if (megs < 16)
963 page_cluster = 2;
964 else
965 page_cluster = 3;
966 /*
967 * Right now other parts of the system means that we
968 * _really_ don't want to cluster much more
969 */
970}
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}