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>
36 /* How many pages do we try to swap or page in/out together? */
39 static DEFINE_PER_CPU(struct pagevec
[NR_LRU_LISTS
], lru_add_pvecs
);
40 static DEFINE_PER_CPU(struct pagevec
, lru_rotate_pvecs
);
43 * This path almost never happens for VM activity - pages are normally
44 * freed via pagevecs. But it gets used by networking.
46 static void __page_cache_release(struct page
*page
)
50 struct zone
*zone
= page_zone(page
);
52 spin_lock_irqsave(&zone
->lru_lock
, flags
);
53 VM_BUG_ON(!PageLRU(page
));
55 del_page_from_lru(zone
, page
);
56 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
61 static void put_compound_page(struct page
*page
)
63 page
= compound_head(page
);
64 if (put_page_testzero(page
)) {
65 compound_page_dtor
*dtor
;
67 dtor
= get_compound_page_dtor(page
);
72 void put_page(struct page
*page
)
74 if (unlikely(PageCompound(page
)))
75 put_compound_page(page
);
76 else if (put_page_testzero(page
))
77 __page_cache_release(page
);
79 EXPORT_SYMBOL(put_page
);
82 * put_pages_list() - release a list of pages
83 * @pages: list of pages threaded on page->lru
85 * Release a list of pages which are strung together on page.lru. Currently
86 * used by read_cache_pages() and related error recovery code.
88 void put_pages_list(struct list_head
*pages
)
90 while (!list_empty(pages
)) {
93 victim
= list_entry(pages
->prev
, struct page
, lru
);
94 list_del(&victim
->lru
);
95 page_cache_release(victim
);
98 EXPORT_SYMBOL(put_pages_list
);
101 * pagevec_move_tail() must be called with IRQ disabled.
102 * Otherwise this may cause nasty races.
104 static void pagevec_move_tail(struct pagevec
*pvec
)
108 struct zone
*zone
= NULL
;
110 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
111 struct page
*page
= pvec
->pages
[i
];
112 struct zone
*pagezone
= page_zone(page
);
114 if (pagezone
!= zone
) {
116 spin_unlock(&zone
->lru_lock
);
118 spin_lock(&zone
->lru_lock
);
120 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
121 int lru
= page_is_file_cache(page
);
122 list_move_tail(&page
->lru
, &zone
->lru
[lru
].list
);
127 spin_unlock(&zone
->lru_lock
);
128 __count_vm_events(PGROTATED
, pgmoved
);
129 release_pages(pvec
->pages
, pvec
->nr
, pvec
->cold
);
130 pagevec_reinit(pvec
);
134 * Writeback is about to end against a page which has been marked for immediate
135 * reclaim. If it still appears to be reclaimable, move it to the tail of the
138 void rotate_reclaimable_page(struct page
*page
)
140 if (!PageLocked(page
) && !PageDirty(page
) && !PageActive(page
) &&
141 !PageUnevictable(page
) && PageLRU(page
)) {
142 struct pagevec
*pvec
;
145 page_cache_get(page
);
146 local_irq_save(flags
);
147 pvec
= &__get_cpu_var(lru_rotate_pvecs
);
148 if (!pagevec_add(pvec
, page
))
149 pagevec_move_tail(pvec
);
150 local_irq_restore(flags
);
154 static void update_page_reclaim_stat(struct zone
*zone
, struct page
*page
,
155 int file
, int rotated
)
157 struct zone_reclaim_stat
*reclaim_stat
= &zone
->reclaim_stat
;
158 struct zone_reclaim_stat
*memcg_reclaim_stat
;
160 memcg_reclaim_stat
= mem_cgroup_get_reclaim_stat_from_page(page
);
162 reclaim_stat
->recent_scanned
[file
]++;
164 reclaim_stat
->recent_rotated
[file
]++;
166 if (!memcg_reclaim_stat
)
169 memcg_reclaim_stat
->recent_scanned
[file
]++;
171 memcg_reclaim_stat
->recent_rotated
[file
]++;
175 * FIXME: speed this up?
177 void activate_page(struct page
*page
)
179 struct zone
*zone
= page_zone(page
);
181 spin_lock_irq(&zone
->lru_lock
);
182 if (PageLRU(page
) && !PageActive(page
) && !PageUnevictable(page
)) {
183 int file
= page_is_file_cache(page
);
184 int lru
= LRU_BASE
+ file
;
185 del_page_from_lru_list(zone
, page
, lru
);
189 add_page_to_lru_list(zone
, page
, lru
);
190 __count_vm_event(PGACTIVATE
);
192 update_page_reclaim_stat(zone
, page
, !!file
, 1);
194 spin_unlock_irq(&zone
->lru_lock
);
198 * Mark a page as having seen activity.
200 * inactive,unreferenced -> inactive,referenced
201 * inactive,referenced -> active,unreferenced
202 * active,unreferenced -> active,referenced
204 void mark_page_accessed(struct page
*page
)
206 if (!PageActive(page
) && !PageUnevictable(page
) &&
207 PageReferenced(page
) && PageLRU(page
)) {
209 ClearPageReferenced(page
);
210 } else if (!PageReferenced(page
)) {
211 SetPageReferenced(page
);
215 EXPORT_SYMBOL(mark_page_accessed
);
217 void __lru_cache_add(struct page
*page
, enum lru_list lru
)
219 struct pagevec
*pvec
= &get_cpu_var(lru_add_pvecs
)[lru
];
221 page_cache_get(page
);
222 if (!pagevec_add(pvec
, page
))
223 ____pagevec_lru_add(pvec
, lru
);
224 put_cpu_var(lru_add_pvecs
);
228 * lru_cache_add_lru - add a page to a page list
229 * @page: the page to be added to the LRU.
230 * @lru: the LRU list to which the page is added.
232 void lru_cache_add_lru(struct page
*page
, enum lru_list lru
)
234 if (PageActive(page
)) {
235 VM_BUG_ON(PageUnevictable(page
));
236 ClearPageActive(page
);
237 } else if (PageUnevictable(page
)) {
238 VM_BUG_ON(PageActive(page
));
239 ClearPageUnevictable(page
);
242 VM_BUG_ON(PageLRU(page
) || PageActive(page
) || PageUnevictable(page
));
243 __lru_cache_add(page
, lru
);
247 * add_page_to_unevictable_list - add a page to the unevictable list
248 * @page: the page to be added to the unevictable list
250 * Add page directly to its zone's unevictable list. To avoid races with
251 * tasks that might be making the page evictable, through eg. munlock,
252 * munmap or exit, while it's not on the lru, we want to add the page
253 * while it's locked or otherwise "invisible" to other tasks. This is
254 * difficult to do when using the pagevec cache, so bypass that.
256 void add_page_to_unevictable_list(struct page
*page
)
258 struct zone
*zone
= page_zone(page
);
260 spin_lock_irq(&zone
->lru_lock
);
261 SetPageUnevictable(page
);
263 add_page_to_lru_list(zone
, page
, LRU_UNEVICTABLE
);
264 spin_unlock_irq(&zone
->lru_lock
);
268 * Drain pages out of the cpu's pagevecs.
269 * Either "cpu" is the current CPU, and preemption has already been
270 * disabled; or "cpu" is being hot-unplugged, and is already dead.
272 static void drain_cpu_pagevecs(int cpu
)
274 struct pagevec
*pvecs
= per_cpu(lru_add_pvecs
, cpu
);
275 struct pagevec
*pvec
;
279 pvec
= &pvecs
[lru
- LRU_BASE
];
280 if (pagevec_count(pvec
))
281 ____pagevec_lru_add(pvec
, lru
);
284 pvec
= &per_cpu(lru_rotate_pvecs
, cpu
);
285 if (pagevec_count(pvec
)) {
288 /* No harm done if a racing interrupt already did this */
289 local_irq_save(flags
);
290 pagevec_move_tail(pvec
);
291 local_irq_restore(flags
);
295 void lru_add_drain(void)
297 drain_cpu_pagevecs(get_cpu());
301 static void lru_add_drain_per_cpu(struct work_struct
*dummy
)
307 * Returns 0 for success
309 int lru_add_drain_all(void)
311 return schedule_on_each_cpu(lru_add_drain_per_cpu
);
315 * Batched page_cache_release(). Decrement the reference count on all the
316 * passed pages. If it fell to zero then remove the page from the LRU and
319 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
320 * for the remainder of the operation.
322 * The locking in this function is against shrink_inactive_list(): we recheck
323 * the page count inside the lock to see whether shrink_inactive_list()
324 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
327 void release_pages(struct page
**pages
, int nr
, int cold
)
330 struct pagevec pages_to_free
;
331 struct zone
*zone
= NULL
;
332 unsigned long uninitialized_var(flags
);
334 pagevec_init(&pages_to_free
, cold
);
335 for (i
= 0; i
< nr
; i
++) {
336 struct page
*page
= pages
[i
];
338 if (unlikely(PageCompound(page
))) {
340 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
343 put_compound_page(page
);
347 if (!put_page_testzero(page
))
351 struct zone
*pagezone
= page_zone(page
);
353 if (pagezone
!= zone
) {
355 spin_unlock_irqrestore(&zone
->lru_lock
,
358 spin_lock_irqsave(&zone
->lru_lock
, flags
);
360 VM_BUG_ON(!PageLRU(page
));
361 __ClearPageLRU(page
);
362 del_page_from_lru(zone
, page
);
365 if (!pagevec_add(&pages_to_free
, page
)) {
367 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
370 __pagevec_free(&pages_to_free
);
371 pagevec_reinit(&pages_to_free
);
375 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
377 pagevec_free(&pages_to_free
);
381 * The pages which we're about to release may be in the deferred lru-addition
382 * queues. That would prevent them from really being freed right now. That's
383 * OK from a correctness point of view but is inefficient - those pages may be
384 * cache-warm and we want to give them back to the page allocator ASAP.
386 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
387 * and __pagevec_lru_add_active() call release_pages() directly to avoid
390 void __pagevec_release(struct pagevec
*pvec
)
393 release_pages(pvec
->pages
, pagevec_count(pvec
), pvec
->cold
);
394 pagevec_reinit(pvec
);
397 EXPORT_SYMBOL(__pagevec_release
);
400 * Add the passed pages to the LRU, then drop the caller's refcount
401 * on them. Reinitialises the caller's pagevec.
403 void ____pagevec_lru_add(struct pagevec
*pvec
, enum lru_list lru
)
406 struct zone
*zone
= NULL
;
408 VM_BUG_ON(is_unevictable_lru(lru
));
410 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
411 struct page
*page
= pvec
->pages
[i
];
412 struct zone
*pagezone
= page_zone(page
);
416 if (pagezone
!= zone
) {
418 spin_unlock_irq(&zone
->lru_lock
);
420 spin_lock_irq(&zone
->lru_lock
);
422 VM_BUG_ON(PageActive(page
));
423 VM_BUG_ON(PageUnevictable(page
));
424 VM_BUG_ON(PageLRU(page
));
426 active
= is_active_lru(lru
);
427 file
= is_file_lru(lru
);
430 update_page_reclaim_stat(zone
, page
, file
, active
);
431 add_page_to_lru_list(zone
, page
, lru
);
434 spin_unlock_irq(&zone
->lru_lock
);
435 release_pages(pvec
->pages
, pvec
->nr
, pvec
->cold
);
436 pagevec_reinit(pvec
);
439 EXPORT_SYMBOL(____pagevec_lru_add
);
442 * Try to drop buffers from the pages in a pagevec
444 void pagevec_strip(struct pagevec
*pvec
)
448 for (i
= 0; i
< pagevec_count(pvec
); i
++) {
449 struct page
*page
= pvec
->pages
[i
];
451 if (page_has_private(page
) && trylock_page(page
)) {
452 if (page_has_private(page
))
453 try_to_release_page(page
, 0);
460 * pagevec_lookup - gang pagecache lookup
461 * @pvec: Where the resulting pages are placed
462 * @mapping: The address_space to search
463 * @start: The starting page index
464 * @nr_pages: The maximum number of pages
466 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
467 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
468 * reference against the pages in @pvec.
470 * The search returns a group of mapping-contiguous pages with ascending
471 * indexes. There may be holes in the indices due to not-present pages.
473 * pagevec_lookup() returns the number of pages which were found.
475 unsigned pagevec_lookup(struct pagevec
*pvec
, struct address_space
*mapping
,
476 pgoff_t start
, unsigned nr_pages
)
478 pvec
->nr
= find_get_pages(mapping
, start
, nr_pages
, pvec
->pages
);
479 return pagevec_count(pvec
);
482 EXPORT_SYMBOL(pagevec_lookup
);
484 unsigned pagevec_lookup_tag(struct pagevec
*pvec
, struct address_space
*mapping
,
485 pgoff_t
*index
, int tag
, unsigned nr_pages
)
487 pvec
->nr
= find_get_pages_tag(mapping
, index
, tag
,
488 nr_pages
, pvec
->pages
);
489 return pagevec_count(pvec
);
492 EXPORT_SYMBOL(pagevec_lookup_tag
);
495 * Perform any setup for the swap system
497 void __init
swap_setup(void)
499 unsigned long megs
= num_physpages
>> (20 - PAGE_SHIFT
);
502 bdi_init(swapper_space
.backing_dev_info
);
505 /* Use a smaller cluster for small-memory machines */
511 * Right now other parts of the system means that we
512 * _really_ don't want to cluster much more
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