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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/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? */
44 int page_cluster;
45
46 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
47 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
48 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
49 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
50 #ifdef CONFIG_SMP
51 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
52 #endif
53
54 /*
55 * This path almost never happens for VM activity - pages are normally
56 * freed via pagevecs. But it gets used by networking.
57 */
58 static void __page_cache_release(struct page *page)
59 {
60 if (PageLRU(page)) {
61 struct zone *zone = page_zone(page);
62 struct lruvec *lruvec;
63 unsigned long flags;
64
65 spin_lock_irqsave(&zone->lru_lock, flags);
66 lruvec = mem_cgroup_page_lruvec(page, zone);
67 VM_BUG_ON_PAGE(!PageLRU(page), page);
68 __ClearPageLRU(page);
69 del_page_from_lru_list(page, lruvec, page_off_lru(page));
70 spin_unlock_irqrestore(&zone->lru_lock, flags);
71 }
72 mem_cgroup_uncharge(page);
73 }
74
75 static void __put_single_page(struct page *page)
76 {
77 __page_cache_release(page);
78 free_hot_cold_page(page, false);
79 }
80
81 static void __put_compound_page(struct page *page)
82 {
83 compound_page_dtor *dtor;
84
85 /*
86 * __page_cache_release() is supposed to be called for thp, not for
87 * hugetlb. This is because hugetlb page does never have PageLRU set
88 * (it's never listed to any LRU lists) and no memcg routines should
89 * be called for hugetlb (it has a separate hugetlb_cgroup.)
90 */
91 if (!PageHuge(page))
92 __page_cache_release(page);
93 dtor = get_compound_page_dtor(page);
94 (*dtor)(page);
95 }
96
97 void __put_page(struct page *page)
98 {
99 if (unlikely(PageCompound(page)))
100 __put_compound_page(page);
101 else
102 __put_single_page(page);
103 }
104 EXPORT_SYMBOL(__put_page);
105
106 /**
107 * put_pages_list() - release a list of pages
108 * @pages: list of pages threaded on page->lru
109 *
110 * Release a list of pages which are strung together on page.lru. Currently
111 * used by read_cache_pages() and related error recovery code.
112 */
113 void put_pages_list(struct list_head *pages)
114 {
115 while (!list_empty(pages)) {
116 struct page *victim;
117
118 victim = list_entry(pages->prev, struct page, lru);
119 list_del(&victim->lru);
120 put_page(victim);
121 }
122 }
123 EXPORT_SYMBOL(put_pages_list);
124
125 /*
126 * get_kernel_pages() - pin kernel pages in memory
127 * @kiov: An array of struct kvec structures
128 * @nr_segs: number of segments to pin
129 * @write: pinning for read/write, currently ignored
130 * @pages: array that receives pointers to the pages pinned.
131 * Should be at least nr_segs long.
132 *
133 * Returns number of pages pinned. This may be fewer than the number
134 * requested. If nr_pages is 0 or negative, returns 0. If no pages
135 * were pinned, returns -errno. Each page returned must be released
136 * with a put_page() call when it is finished with.
137 */
138 int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
139 struct page **pages)
140 {
141 int seg;
142
143 for (seg = 0; seg < nr_segs; seg++) {
144 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
145 return seg;
146
147 pages[seg] = kmap_to_page(kiov[seg].iov_base);
148 get_page(pages[seg]);
149 }
150
151 return seg;
152 }
153 EXPORT_SYMBOL_GPL(get_kernel_pages);
154
155 /*
156 * get_kernel_page() - pin a kernel page in memory
157 * @start: starting kernel address
158 * @write: pinning for read/write, currently ignored
159 * @pages: array that receives pointer to the page pinned.
160 * Must be at least nr_segs long.
161 *
162 * Returns 1 if page is pinned. If the page was not pinned, returns
163 * -errno. The page returned must be released with a put_page() call
164 * when it is finished with.
165 */
166 int get_kernel_page(unsigned long start, int write, struct page **pages)
167 {
168 const struct kvec kiov = {
169 .iov_base = (void *)start,
170 .iov_len = PAGE_SIZE
171 };
172
173 return get_kernel_pages(&kiov, 1, write, pages);
174 }
175 EXPORT_SYMBOL_GPL(get_kernel_page);
176
177 static void pagevec_lru_move_fn(struct pagevec *pvec,
178 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
179 void *arg)
180 {
181 int i;
182 struct zone *zone = NULL;
183 struct lruvec *lruvec;
184 unsigned long flags = 0;
185
186 for (i = 0; i < pagevec_count(pvec); i++) {
187 struct page *page = pvec->pages[i];
188 struct zone *pagezone = page_zone(page);
189
190 if (pagezone != zone) {
191 if (zone)
192 spin_unlock_irqrestore(&zone->lru_lock, flags);
193 zone = pagezone;
194 spin_lock_irqsave(&zone->lru_lock, flags);
195 }
196
197 lruvec = mem_cgroup_page_lruvec(page, zone);
198 (*move_fn)(page, lruvec, arg);
199 }
200 if (zone)
201 spin_unlock_irqrestore(&zone->lru_lock, flags);
202 release_pages(pvec->pages, pvec->nr, pvec->cold);
203 pagevec_reinit(pvec);
204 }
205
206 static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
207 void *arg)
208 {
209 int *pgmoved = arg;
210
211 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
212 enum lru_list lru = page_lru_base_type(page);
213 list_move_tail(&page->lru, &lruvec->lists[lru]);
214 (*pgmoved)++;
215 }
216 }
217
218 /*
219 * pagevec_move_tail() must be called with IRQ disabled.
220 * Otherwise this may cause nasty races.
221 */
222 static void pagevec_move_tail(struct pagevec *pvec)
223 {
224 int pgmoved = 0;
225
226 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
227 __count_vm_events(PGROTATED, pgmoved);
228 }
229
230 /*
231 * Writeback is about to end against a page which has been marked for immediate
232 * reclaim. If it still appears to be reclaimable, move it to the tail of the
233 * inactive list.
234 */
235 void rotate_reclaimable_page(struct page *page)
236 {
237 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
238 !PageUnevictable(page) && PageLRU(page)) {
239 struct pagevec *pvec;
240 unsigned long flags;
241
242 get_page(page);
243 local_irq_save(flags);
244 pvec = this_cpu_ptr(&lru_rotate_pvecs);
245 if (!pagevec_add(pvec, page))
246 pagevec_move_tail(pvec);
247 local_irq_restore(flags);
248 }
249 }
250
251 static void update_page_reclaim_stat(struct lruvec *lruvec,
252 int file, int rotated)
253 {
254 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
255
256 reclaim_stat->recent_scanned[file]++;
257 if (rotated)
258 reclaim_stat->recent_rotated[file]++;
259 }
260
261 static void __activate_page(struct page *page, struct lruvec *lruvec,
262 void *arg)
263 {
264 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
265 int file = page_is_file_cache(page);
266 int lru = page_lru_base_type(page);
267
268 del_page_from_lru_list(page, lruvec, lru);
269 SetPageActive(page);
270 lru += LRU_ACTIVE;
271 add_page_to_lru_list(page, lruvec, lru);
272 trace_mm_lru_activate(page);
273
274 __count_vm_event(PGACTIVATE);
275 update_page_reclaim_stat(lruvec, file, 1);
276 }
277 }
278
279 #ifdef CONFIG_SMP
280 static void activate_page_drain(int cpu)
281 {
282 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
283
284 if (pagevec_count(pvec))
285 pagevec_lru_move_fn(pvec, __activate_page, NULL);
286 }
287
288 static bool need_activate_page_drain(int cpu)
289 {
290 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
291 }
292
293 void activate_page(struct page *page)
294 {
295 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
296 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
297
298 get_page(page);
299 if (!pagevec_add(pvec, page))
300 pagevec_lru_move_fn(pvec, __activate_page, NULL);
301 put_cpu_var(activate_page_pvecs);
302 }
303 }
304
305 #else
306 static inline void activate_page_drain(int cpu)
307 {
308 }
309
310 static bool need_activate_page_drain(int cpu)
311 {
312 return false;
313 }
314
315 void activate_page(struct page *page)
316 {
317 struct zone *zone = page_zone(page);
318
319 spin_lock_irq(&zone->lru_lock);
320 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
321 spin_unlock_irq(&zone->lru_lock);
322 }
323 #endif
324
325 static void __lru_cache_activate_page(struct page *page)
326 {
327 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
328 int i;
329
330 /*
331 * Search backwards on the optimistic assumption that the page being
332 * activated has just been added to this pagevec. Note that only
333 * the local pagevec is examined as a !PageLRU page could be in the
334 * process of being released, reclaimed, migrated or on a remote
335 * pagevec that is currently being drained. Furthermore, marking
336 * a remote pagevec's page PageActive potentially hits a race where
337 * a page is marked PageActive just after it is added to the inactive
338 * list causing accounting errors and BUG_ON checks to trigger.
339 */
340 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
341 struct page *pagevec_page = pvec->pages[i];
342
343 if (pagevec_page == page) {
344 SetPageActive(page);
345 break;
346 }
347 }
348
349 put_cpu_var(lru_add_pvec);
350 }
351
352 /*
353 * Mark a page as having seen activity.
354 *
355 * inactive,unreferenced -> inactive,referenced
356 * inactive,referenced -> active,unreferenced
357 * active,unreferenced -> active,referenced
358 *
359 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
360 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
361 */
362 void mark_page_accessed(struct page *page)
363 {
364 page = compound_head(page);
365 if (!PageActive(page) && !PageUnevictable(page) &&
366 PageReferenced(page)) {
367
368 /*
369 * If the page is on the LRU, queue it for activation via
370 * activate_page_pvecs. Otherwise, assume the page is on a
371 * pagevec, mark it active and it'll be moved to the active
372 * LRU on the next drain.
373 */
374 if (PageLRU(page))
375 activate_page(page);
376 else
377 __lru_cache_activate_page(page);
378 ClearPageReferenced(page);
379 if (page_is_file_cache(page))
380 workingset_activation(page);
381 } else if (!PageReferenced(page)) {
382 SetPageReferenced(page);
383 }
384 if (page_is_idle(page))
385 clear_page_idle(page);
386 }
387 EXPORT_SYMBOL(mark_page_accessed);
388
389 static void __lru_cache_add(struct page *page)
390 {
391 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
392
393 get_page(page);
394 if (!pagevec_space(pvec))
395 __pagevec_lru_add(pvec);
396 pagevec_add(pvec, page);
397 put_cpu_var(lru_add_pvec);
398 }
399
400 /**
401 * lru_cache_add: add a page to the page lists
402 * @page: the page to add
403 */
404 void lru_cache_add_anon(struct page *page)
405 {
406 if (PageActive(page))
407 ClearPageActive(page);
408 __lru_cache_add(page);
409 }
410
411 void lru_cache_add_file(struct page *page)
412 {
413 if (PageActive(page))
414 ClearPageActive(page);
415 __lru_cache_add(page);
416 }
417 EXPORT_SYMBOL(lru_cache_add_file);
418
419 /**
420 * lru_cache_add - add a page to a page list
421 * @page: the page to be added to the LRU.
422 *
423 * Queue the page for addition to the LRU via pagevec. The decision on whether
424 * to add the page to the [in]active [file|anon] list is deferred until the
425 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
426 * have the page added to the active list using mark_page_accessed().
427 */
428 void lru_cache_add(struct page *page)
429 {
430 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
431 VM_BUG_ON_PAGE(PageLRU(page), page);
432 __lru_cache_add(page);
433 }
434
435 /**
436 * add_page_to_unevictable_list - add a page to the unevictable list
437 * @page: the page to be added to the unevictable list
438 *
439 * Add page directly to its zone's unevictable list. To avoid races with
440 * tasks that might be making the page evictable, through eg. munlock,
441 * munmap or exit, while it's not on the lru, we want to add the page
442 * while it's locked or otherwise "invisible" to other tasks. This is
443 * difficult to do when using the pagevec cache, so bypass that.
444 */
445 void add_page_to_unevictable_list(struct page *page)
446 {
447 struct zone *zone = page_zone(page);
448 struct lruvec *lruvec;
449
450 spin_lock_irq(&zone->lru_lock);
451 lruvec = mem_cgroup_page_lruvec(page, zone);
452 ClearPageActive(page);
453 SetPageUnevictable(page);
454 SetPageLRU(page);
455 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
456 spin_unlock_irq(&zone->lru_lock);
457 }
458
459 /**
460 * lru_cache_add_active_or_unevictable
461 * @page: the page to be added to LRU
462 * @vma: vma in which page is mapped for determining reclaimability
463 *
464 * Place @page on the active or unevictable LRU list, depending on its
465 * evictability. Note that if the page is not evictable, it goes
466 * directly back onto it's zone's unevictable list, it does NOT use a
467 * per cpu pagevec.
468 */
469 void lru_cache_add_active_or_unevictable(struct page *page,
470 struct vm_area_struct *vma)
471 {
472 VM_BUG_ON_PAGE(PageLRU(page), page);
473
474 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
475 SetPageActive(page);
476 lru_cache_add(page);
477 return;
478 }
479
480 if (!TestSetPageMlocked(page)) {
481 /*
482 * We use the irq-unsafe __mod_zone_page_stat because this
483 * counter is not modified from interrupt context, and the pte
484 * lock is held(spinlock), which implies preemption disabled.
485 */
486 __mod_zone_page_state(page_zone(page), NR_MLOCK,
487 hpage_nr_pages(page));
488 count_vm_event(UNEVICTABLE_PGMLOCKED);
489 }
490 add_page_to_unevictable_list(page);
491 }
492
493 /*
494 * If the page can not be invalidated, it is moved to the
495 * inactive list to speed up its reclaim. It is moved to the
496 * head of the list, rather than the tail, to give the flusher
497 * threads some time to write it out, as this is much more
498 * effective than the single-page writeout from reclaim.
499 *
500 * If the page isn't page_mapped and dirty/writeback, the page
501 * could reclaim asap using PG_reclaim.
502 *
503 * 1. active, mapped page -> none
504 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
505 * 3. inactive, mapped page -> none
506 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
507 * 5. inactive, clean -> inactive, tail
508 * 6. Others -> none
509 *
510 * In 4, why it moves inactive's head, the VM expects the page would
511 * be write it out by flusher threads as this is much more effective
512 * than the single-page writeout from reclaim.
513 */
514 static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
515 void *arg)
516 {
517 int lru, file;
518 bool active;
519
520 if (!PageLRU(page))
521 return;
522
523 if (PageUnevictable(page))
524 return;
525
526 /* Some processes are using the page */
527 if (page_mapped(page))
528 return;
529
530 active = PageActive(page);
531 file = page_is_file_cache(page);
532 lru = page_lru_base_type(page);
533
534 del_page_from_lru_list(page, lruvec, lru + active);
535 ClearPageActive(page);
536 ClearPageReferenced(page);
537 add_page_to_lru_list(page, lruvec, lru);
538
539 if (PageWriteback(page) || PageDirty(page)) {
540 /*
541 * PG_reclaim could be raced with end_page_writeback
542 * It can make readahead confusing. But race window
543 * is _really_ small and it's non-critical problem.
544 */
545 SetPageReclaim(page);
546 } else {
547 /*
548 * The page's writeback ends up during pagevec
549 * We moves tha page into tail of inactive.
550 */
551 list_move_tail(&page->lru, &lruvec->lists[lru]);
552 __count_vm_event(PGROTATED);
553 }
554
555 if (active)
556 __count_vm_event(PGDEACTIVATE);
557 update_page_reclaim_stat(lruvec, file, 0);
558 }
559
560
561 static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
562 void *arg)
563 {
564 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
565 int file = page_is_file_cache(page);
566 int lru = page_lru_base_type(page);
567
568 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
569 ClearPageActive(page);
570 ClearPageReferenced(page);
571 add_page_to_lru_list(page, lruvec, lru);
572
573 __count_vm_event(PGDEACTIVATE);
574 update_page_reclaim_stat(lruvec, file, 0);
575 }
576 }
577
578 /*
579 * Drain pages out of the cpu's pagevecs.
580 * Either "cpu" is the current CPU, and preemption has already been
581 * disabled; or "cpu" is being hot-unplugged, and is already dead.
582 */
583 void lru_add_drain_cpu(int cpu)
584 {
585 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
586
587 if (pagevec_count(pvec))
588 __pagevec_lru_add(pvec);
589
590 pvec = &per_cpu(lru_rotate_pvecs, cpu);
591 if (pagevec_count(pvec)) {
592 unsigned long flags;
593
594 /* No harm done if a racing interrupt already did this */
595 local_irq_save(flags);
596 pagevec_move_tail(pvec);
597 local_irq_restore(flags);
598 }
599
600 pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
601 if (pagevec_count(pvec))
602 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
603
604 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
605 if (pagevec_count(pvec))
606 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
607
608 activate_page_drain(cpu);
609 }
610
611 /**
612 * deactivate_file_page - forcefully deactivate a file page
613 * @page: page to deactivate
614 *
615 * This function hints the VM that @page is a good reclaim candidate,
616 * for example if its invalidation fails due to the page being dirty
617 * or under writeback.
618 */
619 void deactivate_file_page(struct page *page)
620 {
621 /*
622 * In a workload with many unevictable page such as mprotect,
623 * unevictable page deactivation for accelerating reclaim is pointless.
624 */
625 if (PageUnevictable(page))
626 return;
627
628 if (likely(get_page_unless_zero(page))) {
629 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
630
631 if (!pagevec_add(pvec, page))
632 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
633 put_cpu_var(lru_deactivate_file_pvecs);
634 }
635 }
636
637 /**
638 * deactivate_page - deactivate a page
639 * @page: page to deactivate
640 *
641 * deactivate_page() moves @page to the inactive list if @page was on the active
642 * list and was not an unevictable page. This is done to accelerate the reclaim
643 * of @page.
644 */
645 void deactivate_page(struct page *page)
646 {
647 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
648 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
649
650 get_page(page);
651 if (!pagevec_add(pvec, page))
652 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
653 put_cpu_var(lru_deactivate_pvecs);
654 }
655 }
656
657 void lru_add_drain(void)
658 {
659 lru_add_drain_cpu(get_cpu());
660 put_cpu();
661 }
662
663 static void lru_add_drain_per_cpu(struct work_struct *dummy)
664 {
665 lru_add_drain();
666 }
667
668 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
669
670 void lru_add_drain_all(void)
671 {
672 static DEFINE_MUTEX(lock);
673 static struct cpumask has_work;
674 int cpu;
675
676 mutex_lock(&lock);
677 get_online_cpus();
678 cpumask_clear(&has_work);
679
680 for_each_online_cpu(cpu) {
681 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
682
683 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
684 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
685 pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
686 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
687 need_activate_page_drain(cpu)) {
688 INIT_WORK(work, lru_add_drain_per_cpu);
689 schedule_work_on(cpu, work);
690 cpumask_set_cpu(cpu, &has_work);
691 }
692 }
693
694 for_each_cpu(cpu, &has_work)
695 flush_work(&per_cpu(lru_add_drain_work, cpu));
696
697 put_online_cpus();
698 mutex_unlock(&lock);
699 }
700
701 /**
702 * release_pages - batched put_page()
703 * @pages: array of pages to release
704 * @nr: number of pages
705 * @cold: whether the pages are cache cold
706 *
707 * Decrement the reference count on all the pages in @pages. If it
708 * fell to zero, remove the page from the LRU and free it.
709 */
710 void release_pages(struct page **pages, int nr, bool cold)
711 {
712 int i;
713 LIST_HEAD(pages_to_free);
714 struct zone *zone = NULL;
715 struct lruvec *lruvec;
716 unsigned long uninitialized_var(flags);
717 unsigned int uninitialized_var(lock_batch);
718
719 for (i = 0; i < nr; i++) {
720 struct page *page = pages[i];
721
722 /*
723 * Make sure the IRQ-safe lock-holding time does not get
724 * excessive with a continuous string of pages from the
725 * same zone. The lock is held only if zone != NULL.
726 */
727 if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
728 spin_unlock_irqrestore(&zone->lru_lock, flags);
729 zone = NULL;
730 }
731
732 if (is_huge_zero_page(page)) {
733 put_huge_zero_page();
734 continue;
735 }
736
737 page = compound_head(page);
738 if (!put_page_testzero(page))
739 continue;
740
741 if (PageCompound(page)) {
742 if (zone) {
743 spin_unlock_irqrestore(&zone->lru_lock, flags);
744 zone = NULL;
745 }
746 __put_compound_page(page);
747 continue;
748 }
749
750 if (PageLRU(page)) {
751 struct zone *pagezone = page_zone(page);
752
753 if (pagezone != zone) {
754 if (zone)
755 spin_unlock_irqrestore(&zone->lru_lock,
756 flags);
757 lock_batch = 0;
758 zone = pagezone;
759 spin_lock_irqsave(&zone->lru_lock, flags);
760 }
761
762 lruvec = mem_cgroup_page_lruvec(page, zone);
763 VM_BUG_ON_PAGE(!PageLRU(page), page);
764 __ClearPageLRU(page);
765 del_page_from_lru_list(page, lruvec, page_off_lru(page));
766 }
767
768 /* Clear Active bit in case of parallel mark_page_accessed */
769 __ClearPageActive(page);
770
771 list_add(&page->lru, &pages_to_free);
772 }
773 if (zone)
774 spin_unlock_irqrestore(&zone->lru_lock, flags);
775
776 mem_cgroup_uncharge_list(&pages_to_free);
777 free_hot_cold_page_list(&pages_to_free, cold);
778 }
779 EXPORT_SYMBOL(release_pages);
780
781 /*
782 * The pages which we're about to release may be in the deferred lru-addition
783 * queues. That would prevent them from really being freed right now. That's
784 * OK from a correctness point of view but is inefficient - those pages may be
785 * cache-warm and we want to give them back to the page allocator ASAP.
786 *
787 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
788 * and __pagevec_lru_add_active() call release_pages() directly to avoid
789 * mutual recursion.
790 */
791 void __pagevec_release(struct pagevec *pvec)
792 {
793 lru_add_drain();
794 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
795 pagevec_reinit(pvec);
796 }
797 EXPORT_SYMBOL(__pagevec_release);
798
799 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
800 /* used by __split_huge_page_refcount() */
801 void lru_add_page_tail(struct page *page, struct page *page_tail,
802 struct lruvec *lruvec, struct list_head *list)
803 {
804 const int file = 0;
805
806 VM_BUG_ON_PAGE(!PageHead(page), page);
807 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
808 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
809 VM_BUG_ON(NR_CPUS != 1 &&
810 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
811
812 if (!list)
813 SetPageLRU(page_tail);
814
815 if (likely(PageLRU(page)))
816 list_add_tail(&page_tail->lru, &page->lru);
817 else if (list) {
818 /* page reclaim is reclaiming a huge page */
819 get_page(page_tail);
820 list_add_tail(&page_tail->lru, list);
821 } else {
822 struct list_head *list_head;
823 /*
824 * Head page has not yet been counted, as an hpage,
825 * so we must account for each subpage individually.
826 *
827 * Use the standard add function to put page_tail on the list,
828 * but then correct its position so they all end up in order.
829 */
830 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
831 list_head = page_tail->lru.prev;
832 list_move_tail(&page_tail->lru, list_head);
833 }
834
835 if (!PageUnevictable(page))
836 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
837 }
838 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
839
840 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
841 void *arg)
842 {
843 int file = page_is_file_cache(page);
844 int active = PageActive(page);
845 enum lru_list lru = page_lru(page);
846
847 VM_BUG_ON_PAGE(PageLRU(page), page);
848
849 SetPageLRU(page);
850 add_page_to_lru_list(page, lruvec, lru);
851 update_page_reclaim_stat(lruvec, file, active);
852 trace_mm_lru_insertion(page, lru);
853 }
854
855 /*
856 * Add the passed pages to the LRU, then drop the caller's refcount
857 * on them. Reinitialises the caller's pagevec.
858 */
859 void __pagevec_lru_add(struct pagevec *pvec)
860 {
861 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
862 }
863 EXPORT_SYMBOL(__pagevec_lru_add);
864
865 /**
866 * pagevec_lookup_entries - gang pagecache lookup
867 * @pvec: Where the resulting entries are placed
868 * @mapping: The address_space to search
869 * @start: The starting entry index
870 * @nr_entries: The maximum number of entries
871 * @indices: The cache indices corresponding to the entries in @pvec
872 *
873 * pagevec_lookup_entries() will search for and return a group of up
874 * to @nr_entries pages and shadow entries in the mapping. All
875 * entries are placed in @pvec. pagevec_lookup_entries() takes a
876 * reference against actual pages in @pvec.
877 *
878 * The search returns a group of mapping-contiguous entries with
879 * ascending indexes. There may be holes in the indices due to
880 * not-present entries.
881 *
882 * pagevec_lookup_entries() returns the number of entries which were
883 * found.
884 */
885 unsigned pagevec_lookup_entries(struct pagevec *pvec,
886 struct address_space *mapping,
887 pgoff_t start, unsigned nr_pages,
888 pgoff_t *indices)
889 {
890 pvec->nr = find_get_entries(mapping, start, nr_pages,
891 pvec->pages, indices);
892 return pagevec_count(pvec);
893 }
894
895 /**
896 * pagevec_remove_exceptionals - pagevec exceptionals pruning
897 * @pvec: The pagevec to prune
898 *
899 * pagevec_lookup_entries() fills both pages and exceptional radix
900 * tree entries into the pagevec. This function prunes all
901 * exceptionals from @pvec without leaving holes, so that it can be
902 * passed on to page-only pagevec operations.
903 */
904 void pagevec_remove_exceptionals(struct pagevec *pvec)
905 {
906 int i, j;
907
908 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
909 struct page *page = pvec->pages[i];
910 if (!radix_tree_exceptional_entry(page))
911 pvec->pages[j++] = page;
912 }
913 pvec->nr = j;
914 }
915
916 /**
917 * pagevec_lookup - gang pagecache lookup
918 * @pvec: Where the resulting pages are placed
919 * @mapping: The address_space to search
920 * @start: The starting page index
921 * @nr_pages: The maximum number of pages
922 *
923 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
924 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
925 * reference against the pages in @pvec.
926 *
927 * The search returns a group of mapping-contiguous pages with ascending
928 * indexes. There may be holes in the indices due to not-present pages.
929 *
930 * pagevec_lookup() returns the number of pages which were found.
931 */
932 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
933 pgoff_t start, unsigned nr_pages)
934 {
935 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
936 return pagevec_count(pvec);
937 }
938 EXPORT_SYMBOL(pagevec_lookup);
939
940 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
941 pgoff_t *index, int tag, unsigned nr_pages)
942 {
943 pvec->nr = find_get_pages_tag(mapping, index, tag,
944 nr_pages, pvec->pages);
945 return pagevec_count(pvec);
946 }
947 EXPORT_SYMBOL(pagevec_lookup_tag);
948
949 /*
950 * Perform any setup for the swap system
951 */
952 void __init swap_setup(void)
953 {
954 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
955 #ifdef CONFIG_SWAP
956 int i;
957
958 for (i = 0; i < MAX_SWAPFILES; i++)
959 spin_lock_init(&swapper_spaces[i].tree_lock);
960 #endif
961
962 /* Use a smaller cluster for small-memory machines */
963 if (megs < 16)
964 page_cluster = 2;
965 else
966 page_cluster = 3;
967 /*
968 * Right now other parts of the system means that we
969 * _really_ don't want to cluster much more
970 */
971 }