4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
8 * This file contains the default values for the operation of the
9 * Linux VM subsystem. Fine-tuning documentation can be found in
10 * Documentation/sysctl/vm.txt.
12 * Swap aging added 23.2.95, Stephen Tweedie.
13 * Buffermem limits added 12.3.98, Rik van Riel.
17 #include <linux/sched.h>
18 #include <linux/kernel_stat.h>
19 #include <linux/swap.h>
20 #include <linux/mman.h>
21 #include <linux/pagemap.h>
22 #include <linux/pagevec.h>
23 #include <linux/init.h>
24 #include <linux/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>
37 /* How many pages do we try to swap or page in/out together? */
40 static DEFINE_PER_CPU(struct pagevec
[NR_LRU_LISTS
], lru_add_pvecs
);
41 static DEFINE_PER_CPU(struct pagevec
, lru_rotate_pvecs
);
44 * This path almost never happens for VM activity - pages are normally
45 * freed via pagevecs. But it gets used by networking.
47 static void __page_cache_release(struct page
*page
)
51 struct zone
*zone
= page_zone(page
);
53 spin_lock_irqsave(&zone
->lru_lock
, flags
);
54 VM_BUG_ON(!PageLRU(page
));
56 del_page_from_lru(zone
, page
);
57 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
59 free_hot_cold_page(page
, 0);
62 static void put_compound_page(struct page
*page
)
64 page
= compound_head(page
);
65 if (put_page_testzero(page
)) {
66 compound_page_dtor
*dtor
;
68 dtor
= get_compound_page_dtor(page
);
73 void put_page(struct page
*page
)
75 if (unlikely(PageCompound(page
)))
76 put_compound_page(page
);
77 else if (put_page_testzero(page
))
78 __page_cache_release(page
);
80 EXPORT_SYMBOL(put_page
);
83 * put_pages_list() - release a list of pages
84 * @pages: list of pages threaded on page->lru
86 * Release a list of pages which are strung together on page.lru. Currently
87 * used by read_cache_pages() and related error recovery code.
89 void put_pages_list(struct list_head
*pages
)
91 while (!list_empty(pages
)) {
94 victim
= list_entry(pages
->prev
, struct page
, lru
);
95 list_del(&victim
->lru
);
96 page_cache_release(victim
);
99 EXPORT_SYMBOL(put_pages_list
);
102 * pagevec_move_tail() must be called with IRQ disabled.
103 * Otherwise this may cause nasty races.
105 static void pagevec_move_tail(struct pagevec
*pvec
)
109 struct zone
*zone
= NULL
;
111 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
112 struct page
*page
= pvec
->pages
[i
];
113 struct zone
*pagezone
= page_zone(page
);
115 if (pagezone
!= zone
) {
117 spin_unlock(&zone
->lru_lock
);
119 spin_lock(&zone
->lru_lock
);
121 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
122 int lru
= page_lru_base_type(page
);
123 list_move_tail(&page
->lru
, &zone
->lru
[lru
].list
);
128 spin_unlock(&zone
->lru_lock
);
129 __count_vm_events(PGROTATED
, pgmoved
);
130 release_pages(pvec
->pages
, pvec
->nr
, pvec
->cold
);
131 pagevec_reinit(pvec
);
135 * Writeback is about to end against a page which has been marked for immediate
136 * reclaim. If it still appears to be reclaimable, move it to the tail of the
139 void rotate_reclaimable_page(struct page
*page
)
141 if (!PageLocked(page
) && !PageDirty(page
) && !PageActive(page
) &&
142 !PageUnevictable(page
) && PageLRU(page
)) {
143 struct pagevec
*pvec
;
146 page_cache_get(page
);
147 local_irq_save(flags
);
148 pvec
= &__get_cpu_var(lru_rotate_pvecs
);
149 if (!pagevec_add(pvec
, page
))
150 pagevec_move_tail(pvec
);
151 local_irq_restore(flags
);
155 static void update_page_reclaim_stat(struct zone
*zone
, struct page
*page
,
156 int file
, int rotated
)
158 struct zone_reclaim_stat
*reclaim_stat
= &zone
->reclaim_stat
;
159 struct zone_reclaim_stat
*memcg_reclaim_stat
;
161 memcg_reclaim_stat
= mem_cgroup_get_reclaim_stat_from_page(page
);
163 reclaim_stat
->recent_scanned
[file
]++;
165 reclaim_stat
->recent_rotated
[file
]++;
167 if (!memcg_reclaim_stat
)
170 memcg_reclaim_stat
->recent_scanned
[file
]++;
172 memcg_reclaim_stat
->recent_rotated
[file
]++;
176 * FIXME: speed this up?
178 void activate_page(struct page
*page
)
180 struct zone
*zone
= page_zone(page
);
182 spin_lock_irq(&zone
->lru_lock
);
183 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
184 int file
= page_is_file_cache(page
);
185 int lru
= page_lru_base_type(page
);
186 del_page_from_lru_list(zone
, page
, lru
);
190 add_page_to_lru_list(zone
, page
, lru
);
191 __count_vm_event(PGACTIVATE
);
193 update_page_reclaim_stat(zone
, page
, file
, 1);
195 spin_unlock_irq(&zone
->lru_lock
);
199 * Mark a page as having seen activity.
201 * inactive,unreferenced -> inactive,referenced
202 * inactive,referenced -> active,unreferenced
203 * active,unreferenced -> active,referenced
205 void mark_page_accessed(struct page
*page
)
207 if (!PageActive(page
) && !PageUnevictable(page
) &&
208 PageReferenced(page
) && PageLRU(page
)) {
210 ClearPageReferenced(page
);
211 } else if (!PageReferenced(page
)) {
212 SetPageReferenced(page
);
216 EXPORT_SYMBOL(mark_page_accessed
);
218 void __lru_cache_add(struct page
*page
, enum lru_list lru
)
220 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvecs
)[lru
];
222 page_cache_get(page
);
223 if (!pagevec_add(pvec
, page
))
224 ____pagevec_lru_add(pvec
, lru
);
225 put_cpu_var(lru_add_pvecs
);
227 EXPORT_SYMBOL(__lru_cache_add
);
230 * lru_cache_add_lru - add a page to a page list
231 * @page: the page to be added to the LRU.
232 * @lru: the LRU list to which the page is added.
234 void lru_cache_add_lru(struct page
*page
, enum lru_list lru
)
236 if (PageActive(page
)) {
237 VM_BUG_ON(PageUnevictable(page
));
238 ClearPageActive(page
);
239 } else if (PageUnevictable(page
)) {
240 VM_BUG_ON(PageActive(page
));
241 ClearPageUnevictable(page
);
244 VM_BUG_ON(PageLRU(page
) || PageActive(page
) || PageUnevictable(page
));
245 __lru_cache_add(page
, lru
);
249 * add_page_to_unevictable_list - add a page to the unevictable list
250 * @page: the page to be added to the unevictable list
252 * Add page directly to its zone's unevictable list. To avoid races with
253 * tasks that might be making the page evictable, through eg. munlock,
254 * munmap or exit, while it's not on the lru, we want to add the page
255 * while it's locked or otherwise "invisible" to other tasks. This is
256 * difficult to do when using the pagevec cache, so bypass that.
258 void add_page_to_unevictable_list(struct page
*page
)
260 struct zone
*zone
= page_zone(page
);
262 spin_lock_irq(&zone
->lru_lock
);
263 SetPageUnevictable(page
);
265 add_page_to_lru_list(zone
, page
, LRU_UNEVICTABLE
);
266 spin_unlock_irq(&zone
->lru_lock
);
270 * Drain pages out of the cpu's pagevecs.
271 * Either "cpu" is the current CPU, and preemption has already been
272 * disabled; or "cpu" is being hot-unplugged, and is already dead.
274 static void drain_cpu_pagevecs(int cpu
)
276 struct pagevec
*pvecs
= per_cpu(lru_add_pvecs
, cpu
);
277 struct pagevec
*pvec
;
281 pvec
= &pvecs
[lru
- LRU_BASE
];
282 if (pagevec_count(pvec
))
283 ____pagevec_lru_add(pvec
, lru
);
286 pvec
= &per_cpu(lru_rotate_pvecs
, cpu
);
287 if (pagevec_count(pvec
)) {
290 /* No harm done if a racing interrupt already did this */
291 local_irq_save(flags
);
292 pagevec_move_tail(pvec
);
293 local_irq_restore(flags
);
297 void lru_add_drain(void)
299 drain_cpu_pagevecs(get_cpu());
303 static void lru_add_drain_per_cpu(struct work_struct
*dummy
)
309 * Returns 0 for success
311 int lru_add_drain_all(void)
313 return schedule_on_each_cpu(lru_add_drain_per_cpu
);
317 * Batched page_cache_release(). Decrement the reference count on all the
318 * passed pages. If it fell to zero then remove the page from the LRU and
321 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
322 * for the remainder of the operation.
324 * The locking in this function is against shrink_inactive_list(): we recheck
325 * the page count inside the lock to see whether shrink_inactive_list()
326 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
329 void release_pages(struct page
**pages
, int nr
, int cold
)
332 struct pagevec pages_to_free
;
333 struct zone
*zone
= NULL
;
334 unsigned long uninitialized_var(flags
);
336 pagevec_init(&pages_to_free
, cold
);
337 for (i
= 0; i
< nr
; i
++) {
338 struct page
*page
= pages
[i
];
340 if (unlikely(PageCompound(page
))) {
342 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
345 put_compound_page(page
);
349 if (!put_page_testzero(page
))
353 struct zone
*pagezone
= page_zone(page
);
355 if (pagezone
!= zone
) {
357 spin_unlock_irqrestore(&zone
->lru_lock
,
360 spin_lock_irqsave(&zone
->lru_lock
, flags
);
362 VM_BUG_ON(!PageLRU(page
));
363 __ClearPageLRU(page
);
364 del_page_from_lru(zone
, page
);
367 if (!pagevec_add(&pages_to_free
, page
)) {
369 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
372 __pagevec_free(&pages_to_free
);
373 pagevec_reinit(&pages_to_free
);
377 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
379 pagevec_free(&pages_to_free
);
381 EXPORT_SYMBOL(release_pages
);
384 * The pages which we're about to release may be in the deferred lru-addition
385 * queues. That would prevent them from really being freed right now. That's
386 * OK from a correctness point of view but is inefficient - those pages may be
387 * cache-warm and we want to give them back to the page allocator ASAP.
389 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
390 * and __pagevec_lru_add_active() call release_pages() directly to avoid
393 void __pagevec_release(struct pagevec
*pvec
)
396 release_pages(pvec
->pages
, pagevec_count(pvec
), pvec
->cold
);
397 pagevec_reinit(pvec
);
400 EXPORT_SYMBOL(__pagevec_release
);
403 * Add the passed pages to the LRU, then drop the caller's refcount
404 * on them. Reinitialises the caller's pagevec.
406 void ____pagevec_lru_add(struct pagevec
*pvec
, enum lru_list lru
)
409 struct zone
*zone
= NULL
;
411 VM_BUG_ON(is_unevictable_lru(lru
));
413 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
414 struct page
*page
= pvec
->pages
[i
];
415 struct zone
*pagezone
= page_zone(page
);
419 if (pagezone
!= zone
) {
421 spin_unlock_irq(&zone
->lru_lock
);
423 spin_lock_irq(&zone
->lru_lock
);
425 VM_BUG_ON(PageActive(page
));
426 VM_BUG_ON(PageUnevictable(page
));
427 VM_BUG_ON(PageLRU(page
));
429 active
= is_active_lru(lru
);
430 file
= is_file_lru(lru
);
433 update_page_reclaim_stat(zone
, page
, file
, active
);
434 add_page_to_lru_list(zone
, page
, lru
);
437 spin_unlock_irq(&zone
->lru_lock
);
438 release_pages(pvec
->pages
, pvec
->nr
, pvec
->cold
);
439 pagevec_reinit(pvec
);
442 EXPORT_SYMBOL(____pagevec_lru_add
);
445 * Try to drop buffers from the pages in a pagevec
447 void pagevec_strip(struct pagevec
*pvec
)
451 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
452 struct page
*page
= pvec
->pages
[i
];
454 if (page_has_private(page
) && trylock_page(page
)) {
455 if (page_has_private(page
))
456 try_to_release_page(page
, 0);
463 * pagevec_lookup - gang pagecache lookup
464 * @pvec: Where the resulting pages are placed
465 * @mapping: The address_space to search
466 * @start: The starting page index
467 * @nr_pages: The maximum number of pages
469 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
470 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
471 * reference against the pages in @pvec.
473 * The search returns a group of mapping-contiguous pages with ascending
474 * indexes. There may be holes in the indices due to not-present pages.
476 * pagevec_lookup() returns the number of pages which were found.
478 unsigned pagevec_lookup(struct pagevec
*pvec
, struct address_space
*mapping
,
479 pgoff_t start
, unsigned nr_pages
)
481 pvec
->nr
= find_get_pages(mapping
, start
, nr_pages
, pvec
->pages
);
482 return pagevec_count(pvec
);
485 EXPORT_SYMBOL(pagevec_lookup
);
487 unsigned pagevec_lookup_tag(struct pagevec
*pvec
, struct address_space
*mapping
,
488 pgoff_t
*index
, int tag
, unsigned nr_pages
)
490 pvec
->nr
= find_get_pages_tag(mapping
, index
, tag
,
491 nr_pages
, pvec
->pages
);
492 return pagevec_count(pvec
);
495 EXPORT_SYMBOL(pagevec_lookup_tag
);
498 * Perform any setup for the swap system
500 void __init
swap_setup(void)
502 unsigned long megs
= totalram_pages
>> (20 - PAGE_SHIFT
);
505 bdi_init(swapper_space
.backing_dev_info
);
508 /* Use a smaller cluster for small-memory machines */
514 * Right now other parts of the system means that we
515 * _really_ don't want to cluster much more
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