blob: eac9577941f935a0d8f281a6e851b68995e50314 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/vmscan.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
12 */
13
14#include <linux/mm.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/kernel_stat.h>
18#include <linux/swap.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/highmem.h>
Andrew Mortone129b5c2006-09-27 01:50:00 -070022#include <linux/vmstat.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/file.h>
24#include <linux/writeback.h>
25#include <linux/blkdev.h>
26#include <linux/buffer_head.h> /* for try_to_release_page(),
27 buffer_heads_over_limit */
28#include <linux/mm_inline.h>
29#include <linux/pagevec.h>
30#include <linux/backing-dev.h>
31#include <linux/rmap.h>
32#include <linux/topology.h>
33#include <linux/cpu.h>
34#include <linux/cpuset.h>
35#include <linux/notifier.h>
36#include <linux/rwsem.h>
Rafael J. Wysocki248a0302006-03-22 00:09:04 -080037#include <linux/delay.h>
Yasunori Goto3218ae12006-06-27 02:53:33 -070038#include <linux/kthread.h>
Nigel Cunningham7dfb7102006-12-06 20:34:23 -080039#include <linux/freezer.h>
Balbir Singh66e17072008-02-07 00:13:56 -080040#include <linux/memcontrol.h>
Keika Kobayashi873b4772008-07-25 01:48:52 -070041#include <linux/delayacct.h>
Lee Schermerhornaf936a12008-10-18 20:26:53 -070042#include <linux/sysctl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44#include <asm/tlbflush.h>
45#include <asm/div64.h>
46
47#include <linux/swapops.h>
48
Nick Piggin0f8053a2006-03-22 00:08:33 -080049#include "internal.h"
50
Linus Torvalds1da177e2005-04-16 15:20:36 -070051struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 /* Incremented by the number of inactive pages that were scanned */
53 unsigned long nr_scanned;
54
Rik van Riela79311c2009-01-06 14:40:01 -080055 /* Number of pages freed so far during a call to shrink_zones() */
56 unsigned long nr_reclaimed;
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040059 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61 int may_writepage;
62
Johannes Weinera6dc60f2009-03-31 15:19:30 -070063 /* Can mapped pages be reclaimed? */
64 int may_unmap;
Christoph Lameterf1fd1062006-01-18 17:42:30 -080065
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -070066 /* Can pages be swapped as part of reclaim? */
67 int may_swap;
68
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 /* This context's SWAP_CLUSTER_MAX. If freeing memory for
70 * suspend, we effectively ignore SWAP_CLUSTER_MAX.
71 * In this context, it doesn't matter that we scan the
72 * whole list at once. */
73 int swap_cluster_max;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -070074
75 int swappiness;
Nick Piggin408d8542006-09-25 23:31:27 -070076
77 int all_unreclaimable;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070078
79 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080080
81 /* Which cgroup do we reclaim from */
82 struct mem_cgroup *mem_cgroup;
83
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -070084 /*
85 * Nodemask of nodes allowed by the caller. If NULL, all nodes
86 * are scanned.
87 */
88 nodemask_t *nodemask;
89
Balbir Singh66e17072008-02-07 00:13:56 -080090 /* Pluggable isolate pages callback */
91 unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
92 unsigned long *scanned, int order, int mode,
93 struct zone *z, struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -070094 int active, int file);
Linus Torvalds1da177e2005-04-16 15:20:36 -070095};
96
Linus Torvalds1da177e2005-04-16 15:20:36 -070097#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
98
99#ifdef ARCH_HAS_PREFETCH
100#define prefetch_prev_lru_page(_page, _base, _field) \
101 do { \
102 if ((_page)->lru.prev != _base) { \
103 struct page *prev; \
104 \
105 prev = lru_to_page(&(_page->lru)); \
106 prefetch(&prev->_field); \
107 } \
108 } while (0)
109#else
110#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
111#endif
112
113#ifdef ARCH_HAS_PREFETCHW
114#define prefetchw_prev_lru_page(_page, _base, _field) \
115 do { \
116 if ((_page)->lru.prev != _base) { \
117 struct page *prev; \
118 \
119 prev = lru_to_page(&(_page->lru)); \
120 prefetchw(&prev->_field); \
121 } \
122 } while (0)
123#else
124#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
125#endif
126
127/*
128 * From 0 .. 100. Higher means more swappy.
129 */
130int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700131long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
133static LIST_HEAD(shrinker_list);
134static DECLARE_RWSEM(shrinker_rwsem);
135
Balbir Singh00f0b822008-03-04 14:28:39 -0800136#ifdef CONFIG_CGROUP_MEM_RES_CTLR
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800137#define scanning_global_lru(sc) (!(sc)->mem_cgroup)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800138#else
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800139#define scanning_global_lru(sc) (1)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800140#endif
141
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800142static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
143 struct scan_control *sc)
144{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800145 if (!scanning_global_lru(sc))
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800146 return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone);
147
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800148 return &zone->reclaim_stat;
149}
150
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800151static unsigned long zone_nr_pages(struct zone *zone, struct scan_control *sc,
152 enum lru_list lru)
153{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800154 if (!scanning_global_lru(sc))
KOSAKI Motohiroa3d8e052009-01-07 18:08:19 -0800155 return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
156
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800157 return zone_page_state(zone, NR_LRU_BASE + lru);
158}
159
160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161/*
162 * Add a shrinker callback to be called from the vm
163 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700164void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165{
Rusty Russell8e1f9362007-07-17 04:03:17 -0700166 shrinker->nr = 0;
167 down_write(&shrinker_rwsem);
168 list_add_tail(&shrinker->list, &shrinker_list);
169 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700171EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
173/*
174 * Remove one
175 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700176void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177{
178 down_write(&shrinker_rwsem);
179 list_del(&shrinker->list);
180 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700182EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
184#define SHRINK_BATCH 128
185/*
186 * Call the shrink functions to age shrinkable caches
187 *
188 * Here we assume it costs one seek to replace a lru page and that it also
189 * takes a seek to recreate a cache object. With this in mind we age equal
190 * percentages of the lru and ageable caches. This should balance the seeks
191 * generated by these structures.
192 *
Simon Arlott183ff222007-10-20 01:27:18 +0200193 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 * slab to avoid swapping.
195 *
196 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
197 *
198 * `lru_pages' represents the number of on-LRU pages in all the zones which
199 * are eligible for the caller's allocation attempt. It is used for balancing
200 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700201 *
202 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 */
Andrew Morton69e05942006-03-22 00:08:19 -0800204unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
205 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206{
207 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800208 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
210 if (scanned == 0)
211 scanned = SWAP_CLUSTER_MAX;
212
213 if (!down_read_trylock(&shrinker_rwsem))
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700214 return 1; /* Assume we'll be able to shrink next time */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
216 list_for_each_entry(shrinker, &shrinker_list, list) {
217 unsigned long long delta;
218 unsigned long total_scan;
Rusty Russell8e1f9362007-07-17 04:03:17 -0700219 unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221 delta = (4 * scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800222 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 do_div(delta, lru_pages + 1);
224 shrinker->nr += delta;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800225 if (shrinker->nr < 0) {
David Rientjes88c3bd72009-03-31 15:23:29 -0700226 printk(KERN_ERR "shrink_slab: %pF negative objects to "
227 "delete nr=%ld\n",
228 shrinker->shrink, shrinker->nr);
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800229 shrinker->nr = max_pass;
230 }
231
232 /*
233 * Avoid risking looping forever due to too large nr value:
234 * never try to free more than twice the estimate number of
235 * freeable entries.
236 */
237 if (shrinker->nr > max_pass * 2)
238 shrinker->nr = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
240 total_scan = shrinker->nr;
241 shrinker->nr = 0;
242
243 while (total_scan >= SHRINK_BATCH) {
244 long this_scan = SHRINK_BATCH;
245 int shrink_ret;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700246 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
Rusty Russell8e1f9362007-07-17 04:03:17 -0700248 nr_before = (*shrinker->shrink)(0, gfp_mask);
249 shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 if (shrink_ret == -1)
251 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700252 if (shrink_ret < nr_before)
253 ret += nr_before - shrink_ret;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700254 count_vm_events(SLABS_SCANNED, this_scan);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 total_scan -= this_scan;
256
257 cond_resched();
258 }
259
260 shrinker->nr += total_scan;
261 }
262 up_read(&shrinker_rwsem);
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700263 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264}
265
266/* Called without lock on whether page is mapped, so answer is unstable */
267static inline int page_mapping_inuse(struct page *page)
268{
269 struct address_space *mapping;
270
271 /* Page is in somebody's page tables. */
272 if (page_mapped(page))
273 return 1;
274
275 /* Be more reluctant to reclaim swapcache than pagecache */
276 if (PageSwapCache(page))
277 return 1;
278
279 mapping = page_mapping(page);
280 if (!mapping)
281 return 0;
282
283 /* File is mmap'd by somebody? */
284 return mapping_mapped(mapping);
285}
286
287static inline int is_page_cache_freeable(struct page *page)
288{
David Howells266cf652009-04-03 16:42:36 +0100289 return page_count(page) - !!page_has_private(page) == 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290}
291
292static int may_write_to_queue(struct backing_dev_info *bdi)
293{
Christoph Lameter930d9152006-01-08 01:00:47 -0800294 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 return 1;
296 if (!bdi_write_congested(bdi))
297 return 1;
298 if (bdi == current->backing_dev_info)
299 return 1;
300 return 0;
301}
302
303/*
304 * We detected a synchronous write error writing a page out. Probably
305 * -ENOSPC. We need to propagate that into the address_space for a subsequent
306 * fsync(), msync() or close().
307 *
308 * The tricky part is that after writepage we cannot touch the mapping: nothing
309 * prevents it from being freed up. But we have a ref on the page and once
310 * that page is locked, the mapping is pinned.
311 *
312 * We're allowed to run sleeping lock_page() here because we know the caller has
313 * __GFP_FS.
314 */
315static void handle_write_error(struct address_space *mapping,
316 struct page *page, int error)
317{
318 lock_page(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700319 if (page_mapping(page) == mapping)
320 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 unlock_page(page);
322}
323
Andy Whitcroftc661b072007-08-22 14:01:26 -0700324/* Request for sync pageout. */
325enum pageout_io {
326 PAGEOUT_IO_ASYNC,
327 PAGEOUT_IO_SYNC,
328};
329
Christoph Lameter04e62a22006-06-23 02:03:38 -0700330/* possible outcome of pageout() */
331typedef enum {
332 /* failed to write page out, page is locked */
333 PAGE_KEEP,
334 /* move page to the active list, page is locked */
335 PAGE_ACTIVATE,
336 /* page has been sent to the disk successfully, page is unlocked */
337 PAGE_SUCCESS,
338 /* page is clean and locked */
339 PAGE_CLEAN,
340} pageout_t;
341
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342/*
Andrew Morton1742f192006-03-22 00:08:21 -0800343 * pageout is called by shrink_page_list() for each dirty page.
344 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700346static pageout_t pageout(struct page *page, struct address_space *mapping,
347 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348{
349 /*
350 * If the page is dirty, only perform writeback if that write
351 * will be non-blocking. To prevent this allocation from being
352 * stalled by pagecache activity. But note that there may be
353 * stalls if we need to run get_block(). We could test
354 * PagePrivate for that.
355 *
356 * If this process is currently in generic_file_write() against
357 * this page's queue, we can perform writeback even if that
358 * will block.
359 *
360 * If the page is swapcache, write it back even if that would
361 * block, for some throttling. This happens by accident, because
362 * swap_backing_dev_info is bust: it doesn't reflect the
363 * congestion state of the swapdevs. Easy to fix, if needed.
364 * See swapfile.c:page_queue_congested().
365 */
366 if (!is_page_cache_freeable(page))
367 return PAGE_KEEP;
368 if (!mapping) {
369 /*
370 * Some data journaling orphaned pages can have
371 * page->mapping == NULL while being dirty with clean buffers.
372 */
David Howells266cf652009-04-03 16:42:36 +0100373 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 if (try_to_free_buffers(page)) {
375 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700376 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 return PAGE_CLEAN;
378 }
379 }
380 return PAGE_KEEP;
381 }
382 if (mapping->a_ops->writepage == NULL)
383 return PAGE_ACTIVATE;
384 if (!may_write_to_queue(mapping->backing_dev_info))
385 return PAGE_KEEP;
386
387 if (clear_page_dirty_for_io(page)) {
388 int res;
389 struct writeback_control wbc = {
390 .sync_mode = WB_SYNC_NONE,
391 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700392 .range_start = 0,
393 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 .nonblocking = 1,
395 .for_reclaim = 1,
396 };
397
398 SetPageReclaim(page);
399 res = mapping->a_ops->writepage(page, &wbc);
400 if (res < 0)
401 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800402 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 ClearPageReclaim(page);
404 return PAGE_ACTIVATE;
405 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700406
407 /*
408 * Wait on writeback if requested to. This happens when
409 * direct reclaiming a large contiguous area and the
410 * first attempt to free a range of pages fails.
411 */
412 if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
413 wait_on_page_writeback(page);
414
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 if (!PageWriteback(page)) {
416 /* synchronous write or broken a_ops? */
417 ClearPageReclaim(page);
418 }
Andrew Mortone129b5c2006-09-27 01:50:00 -0700419 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 return PAGE_SUCCESS;
421 }
422
423 return PAGE_CLEAN;
424}
425
Andrew Mortona649fd92006-10-17 00:09:36 -0700426/*
Nick Piggine2867812008-07-25 19:45:30 -0700427 * Same as remove_mapping, but if the page is removed from the mapping, it
428 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700429 */
Nick Piggine2867812008-07-25 19:45:30 -0700430static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800431{
Nick Piggin28e4d962006-09-25 23:31:23 -0700432 BUG_ON(!PageLocked(page));
433 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800434
Nick Piggin19fd6232008-07-25 19:45:32 -0700435 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800436 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700437 * The non racy check for a busy page.
438 *
439 * Must be careful with the order of the tests. When someone has
440 * a ref to the page, it may be possible that they dirty it then
441 * drop the reference. So if PageDirty is tested before page_count
442 * here, then the following race may occur:
443 *
444 * get_user_pages(&page);
445 * [user mapping goes away]
446 * write_to(page);
447 * !PageDirty(page) [good]
448 * SetPageDirty(page);
449 * put_page(page);
450 * !page_count(page) [good, discard it]
451 *
452 * [oops, our write_to data is lost]
453 *
454 * Reversing the order of the tests ensures such a situation cannot
455 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
456 * load is not satisfied before that of page->_count.
457 *
458 * Note that if SetPageDirty is always performed via set_page_dirty,
459 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800460 */
Nick Piggine2867812008-07-25 19:45:30 -0700461 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800462 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700463 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
464 if (unlikely(PageDirty(page))) {
465 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800466 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700467 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800468
469 if (PageSwapCache(page)) {
470 swp_entry_t swap = { .val = page_private(page) };
471 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700472 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800473 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -0700474 } else {
475 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700476 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800477 }
478
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800479 return 1;
480
481cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700482 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800483 return 0;
484}
485
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486/*
Nick Piggine2867812008-07-25 19:45:30 -0700487 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
488 * someone else has a ref on the page, abort and return 0. If it was
489 * successfully detached, return 1. Assumes the caller has a single ref on
490 * this page.
491 */
492int remove_mapping(struct address_space *mapping, struct page *page)
493{
494 if (__remove_mapping(mapping, page)) {
495 /*
496 * Unfreezing the refcount with 1 rather than 2 effectively
497 * drops the pagecache ref for us without requiring another
498 * atomic operation.
499 */
500 page_unfreeze_refs(page, 1);
501 return 1;
502 }
503 return 0;
504}
505
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700506/**
507 * putback_lru_page - put previously isolated page onto appropriate LRU list
508 * @page: page to be put back to appropriate lru list
509 *
510 * Add previously isolated @page to appropriate LRU list.
511 * Page may still be unevictable for other reasons.
512 *
513 * lru_lock must not be held, interrupts must be enabled.
514 */
515#ifdef CONFIG_UNEVICTABLE_LRU
516void putback_lru_page(struct page *page)
517{
518 int lru;
519 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700520 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700521
522 VM_BUG_ON(PageLRU(page));
523
524redo:
525 ClearPageUnevictable(page);
526
527 if (page_evictable(page, NULL)) {
528 /*
529 * For evictable pages, we can use the cache.
530 * In event of a race, worst case is we end up with an
531 * unevictable page on [in]active list.
532 * We know how to handle that.
533 */
534 lru = active + page_is_file_cache(page);
535 lru_cache_add_lru(page, lru);
536 } else {
537 /*
538 * Put unevictable pages directly on zone's unevictable
539 * list.
540 */
541 lru = LRU_UNEVICTABLE;
542 add_page_to_unevictable_list(page);
543 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700544
545 /*
546 * page's status can change while we move it among lru. If an evictable
547 * page is on unevictable list, it never be freed. To avoid that,
548 * check after we added it to the list, again.
549 */
550 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
551 if (!isolate_lru_page(page)) {
552 put_page(page);
553 goto redo;
554 }
555 /* This means someone else dropped this page from LRU
556 * So, it will be freed or putback to LRU again. There is
557 * nothing to do here.
558 */
559 }
560
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700561 if (was_unevictable && lru != LRU_UNEVICTABLE)
562 count_vm_event(UNEVICTABLE_PGRESCUED);
563 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
564 count_vm_event(UNEVICTABLE_PGCULLED);
565
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700566 put_page(page); /* drop ref from isolate */
567}
568
569#else /* CONFIG_UNEVICTABLE_LRU */
570
571void putback_lru_page(struct page *page)
572{
573 int lru;
574 VM_BUG_ON(PageLRU(page));
575
576 lru = !!TestClearPageActive(page) + page_is_file_cache(page);
577 lru_cache_add_lru(page, lru);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700578 put_page(page);
579}
580#endif /* CONFIG_UNEVICTABLE_LRU */
581
582
Nick Piggine2867812008-07-25 19:45:30 -0700583/*
Andrew Morton1742f192006-03-22 00:08:21 -0800584 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 */
Andrew Morton1742f192006-03-22 00:08:21 -0800586static unsigned long shrink_page_list(struct list_head *page_list,
Andy Whitcroftc661b072007-08-22 14:01:26 -0700587 struct scan_control *sc,
588 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589{
590 LIST_HEAD(ret_pages);
591 struct pagevec freed_pvec;
592 int pgactivate = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800593 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594
595 cond_resched();
596
597 pagevec_init(&freed_pvec, 1);
598 while (!list_empty(page_list)) {
599 struct address_space *mapping;
600 struct page *page;
601 int may_enter_fs;
602 int referenced;
603
604 cond_resched();
605
606 page = lru_to_page(page_list);
607 list_del(&page->lru);
608
Nick Piggin529ae9a2008-08-02 12:01:03 +0200609 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 goto keep;
611
Nick Piggin725d7042006-09-25 23:30:55 -0700612 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613
614 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800615
Nick Pigginb291f002008-10-18 20:26:44 -0700616 if (unlikely(!page_evictable(page, NULL)))
617 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700618
Johannes Weinera6dc60f2009-03-31 15:19:30 -0700619 if (!sc->may_unmap && page_mapped(page))
Christoph Lameter80e43422006-02-11 17:55:53 -0800620 goto keep_locked;
621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 /* Double the slab pressure for mapped and swapcache pages */
623 if (page_mapped(page) || PageSwapCache(page))
624 sc->nr_scanned++;
625
Andy Whitcroftc661b072007-08-22 14:01:26 -0700626 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
627 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
628
629 if (PageWriteback(page)) {
630 /*
631 * Synchronous reclaim is performed in two passes,
632 * first an asynchronous pass over the list to
633 * start parallel writeback, and a second synchronous
634 * pass to wait for the IO to complete. Wait here
635 * for any page for which writeback has already
636 * started.
637 */
638 if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
639 wait_on_page_writeback(page);
Andrew Morton4dd4b922008-03-24 12:29:52 -0700640 else
Andy Whitcroftc661b072007-08-22 14:01:26 -0700641 goto keep_locked;
642 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643
Balbir Singhbed71612008-02-07 00:14:01 -0800644 referenced = page_referenced(page, 1, sc->mem_cgroup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 /* In active use or really unfreeable? Activate it. */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700646 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
647 referenced && page_mapping_inuse(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 goto activate_locked;
649
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 /*
651 * Anonymous process memory has backing store?
652 * Try to allocate it some swap space here.
653 */
Nick Pigginb291f002008-10-18 20:26:44 -0700654 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800655 if (!(sc->gfp_mask & __GFP_IO))
656 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800657 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800659 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700660 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661
662 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663
664 /*
665 * The page is mapped into the page tables of one or more
666 * processes. Try to unmap it here.
667 */
668 if (page_mapped(page) && mapping) {
Christoph Lametera48d07a2006-02-01 03:05:38 -0800669 switch (try_to_unmap(page, 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 case SWAP_FAIL:
671 goto activate_locked;
672 case SWAP_AGAIN:
673 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700674 case SWAP_MLOCK:
675 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 case SWAP_SUCCESS:
677 ; /* try to free the page below */
678 }
679 }
680
681 if (PageDirty(page)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700682 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700684 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800686 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 goto keep_locked;
688
689 /* Page is dirty, try to write it out here */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700690 switch (pageout(page, mapping, sync_writeback)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 case PAGE_KEEP:
692 goto keep_locked;
693 case PAGE_ACTIVATE:
694 goto activate_locked;
695 case PAGE_SUCCESS:
Andrew Morton4dd4b922008-03-24 12:29:52 -0700696 if (PageWriteback(page) || PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 goto keep;
698 /*
699 * A synchronous write - probably a ramdisk. Go
700 * ahead and try to reclaim the page.
701 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200702 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 goto keep;
704 if (PageDirty(page) || PageWriteback(page))
705 goto keep_locked;
706 mapping = page_mapping(page);
707 case PAGE_CLEAN:
708 ; /* try to free the page below */
709 }
710 }
711
712 /*
713 * If the page has buffers, try to free the buffer mappings
714 * associated with this page. If we succeed we try to free
715 * the page as well.
716 *
717 * We do this even if the page is PageDirty().
718 * try_to_release_page() does not perform I/O, but it is
719 * possible for a page to have PageDirty set, but it is actually
720 * clean (all its buffers are clean). This happens if the
721 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700722 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 * try_to_release_page() will discover that cleanness and will
724 * drop the buffers and mark the page clean - it can be freed.
725 *
726 * Rarely, pages can have buffers and no ->mapping. These are
727 * the pages which were not successfully invalidated in
728 * truncate_complete_page(). We try to drop those buffers here
729 * and if that worked, and the page is no longer mapped into
730 * process address space (page_count == 1) it can be freed.
731 * Otherwise, leave the page on the LRU so it is swappable.
732 */
David Howells266cf652009-04-03 16:42:36 +0100733 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 if (!try_to_release_page(page, sc->gfp_mask))
735 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700736 if (!mapping && page_count(page) == 1) {
737 unlock_page(page);
738 if (put_page_testzero(page))
739 goto free_it;
740 else {
741 /*
742 * rare race with speculative reference.
743 * the speculative reference will free
744 * this page shortly, so we may
745 * increment nr_reclaimed here (and
746 * leave it off the LRU).
747 */
748 nr_reclaimed++;
749 continue;
750 }
751 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 }
753
Nick Piggine2867812008-07-25 19:45:30 -0700754 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800755 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756
Nick Piggina978d6f2008-10-18 20:26:58 -0700757 /*
758 * At this point, we have no other references and there is
759 * no way to pick any more up (removed from LRU, removed
760 * from pagecache). Can use non-atomic bitops now (and
761 * we obviously don't have to worry about waking up a process
762 * waiting on the page lock, because there are no references.
763 */
764 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700765free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800766 nr_reclaimed++;
Nick Piggine2867812008-07-25 19:45:30 -0700767 if (!pagevec_add(&freed_pvec, page)) {
768 __pagevec_free(&freed_pvec);
769 pagevec_reinit(&freed_pvec);
770 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 continue;
772
Nick Pigginb291f002008-10-18 20:26:44 -0700773cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800774 if (PageSwapCache(page))
775 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700776 unlock_page(page);
777 putback_lru_page(page);
778 continue;
779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700781 /* Not a candidate for swapping, so reclaim swap space. */
782 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800783 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700784 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 SetPageActive(page);
786 pgactivate++;
787keep_locked:
788 unlock_page(page);
789keep:
790 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700791 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 }
793 list_splice(&ret_pages, page_list);
794 if (pagevec_count(&freed_pvec))
Nick Piggine2867812008-07-25 19:45:30 -0700795 __pagevec_free(&freed_pvec);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700796 count_vm_events(PGACTIVATE, pgactivate);
Andrew Morton05ff5132006-03-22 00:08:20 -0800797 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798}
799
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700800/* LRU Isolation modes. */
801#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
802#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
803#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
804
805/*
806 * Attempt to remove the specified page from its LRU. Only take this page
807 * if it is of the appropriate PageActive status. Pages which are being
808 * freed elsewhere are also ignored.
809 *
810 * page: page to consider
811 * mode: one of the LRU isolation modes defined above
812 *
813 * returns 0 on success, -ve errno on failure.
814 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700815int __isolate_lru_page(struct page *page, int mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700816{
817 int ret = -EINVAL;
818
819 /* Only take pages on the LRU. */
820 if (!PageLRU(page))
821 return ret;
822
823 /*
824 * When checking the active state, we need to be sure we are
825 * dealing with comparible boolean values. Take the logical not
826 * of each.
827 */
828 if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
829 return ret;
830
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700831 if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file))
832 return ret;
833
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700834 /*
835 * When this function is being called for lumpy reclaim, we
836 * initially look into all LRU pages, active, inactive and
837 * unevictable; only give shrink_page_list evictable pages.
838 */
839 if (PageUnevictable(page))
840 return ret;
841
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700842 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800843
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700844 if (likely(get_page_unless_zero(page))) {
845 /*
846 * Be careful not to clear PageLRU until after we're
847 * sure the page is not being freed elsewhere -- the
848 * page release code relies on it.
849 */
850 ClearPageLRU(page);
851 ret = 0;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800852 mem_cgroup_del_lru(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700853 }
854
855 return ret;
856}
857
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800858/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 * zone->lru_lock is heavily contended. Some of the functions that
860 * shrink the lists perform better by taking out a batch of pages
861 * and working on them outside the LRU lock.
862 *
863 * For pagecache intensive workloads, this function is the hottest
864 * spot in the kernel (apart from copy_*_user functions).
865 *
866 * Appropriate locks must be held before calling this function.
867 *
868 * @nr_to_scan: The number of pages to look through on the list.
869 * @src: The LRU list to pull pages off.
870 * @dst: The temp list to put pages on to.
871 * @scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700872 * @order: The caller's attempted allocation order
873 * @mode: One of the LRU isolation modes
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700874 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 *
876 * returns how many pages were moved onto *@dst.
877 */
Andrew Morton69e05942006-03-22 00:08:19 -0800878static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
879 struct list_head *src, struct list_head *dst,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700880 unsigned long *scanned, int order, int mode, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881{
Andrew Morton69e05942006-03-22 00:08:19 -0800882 unsigned long nr_taken = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800883 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800885 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700886 struct page *page;
887 unsigned long pfn;
888 unsigned long end_pfn;
889 unsigned long page_pfn;
890 int zone_id;
891
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 page = lru_to_page(src);
893 prefetchw_prev_lru_page(page, src, flags);
894
Nick Piggin725d7042006-09-25 23:30:55 -0700895 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800896
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700897 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700898 case 0:
899 list_move(&page->lru, dst);
Nick Piggin7c8ee9a2006-03-22 00:08:03 -0800900 nr_taken++;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700901 break;
Nick Piggin46453a62006-03-22 00:07:58 -0800902
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700903 case -EBUSY:
904 /* else it is being freed elsewhere */
905 list_move(&page->lru, src);
906 continue;
907
908 default:
909 BUG();
910 }
911
912 if (!order)
913 continue;
914
915 /*
916 * Attempt to take all pages in the order aligned region
917 * surrounding the tag page. Only take those pages of
918 * the same active state as that tag page. We may safely
919 * round the target page pfn down to the requested order
920 * as the mem_map is guarenteed valid out to MAX_ORDER,
921 * where that page is in a different zone we will detect
922 * it from its zone id and abort this block scan.
923 */
924 zone_id = page_zone_id(page);
925 page_pfn = page_to_pfn(page);
926 pfn = page_pfn & ~((1 << order) - 1);
927 end_pfn = pfn + (1 << order);
928 for (; pfn < end_pfn; pfn++) {
929 struct page *cursor_page;
930
931 /* The target page is in the block, ignore it. */
932 if (unlikely(pfn == page_pfn))
933 continue;
934
935 /* Avoid holes within the zone. */
936 if (unlikely(!pfn_valid_within(pfn)))
937 break;
938
939 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700940
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700941 /* Check that we have not crossed a zone boundary. */
942 if (unlikely(page_zone_id(cursor_page) != zone_id))
943 continue;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700944 switch (__isolate_lru_page(cursor_page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700945 case 0:
946 list_move(&cursor_page->lru, dst);
947 nr_taken++;
948 scan++;
949 break;
950
951 case -EBUSY:
952 /* else it is being freed elsewhere */
953 list_move(&cursor_page->lru, src);
954 default:
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700955 break; /* ! on LRU or wrong list */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700956 }
957 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 }
959
960 *scanned = scan;
961 return nr_taken;
962}
963
Balbir Singh66e17072008-02-07 00:13:56 -0800964static unsigned long isolate_pages_global(unsigned long nr,
965 struct list_head *dst,
966 unsigned long *scanned, int order,
967 int mode, struct zone *z,
968 struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700969 int active, int file)
Balbir Singh66e17072008-02-07 00:13:56 -0800970{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700971 int lru = LRU_BASE;
Balbir Singh66e17072008-02-07 00:13:56 -0800972 if (active)
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700973 lru += LRU_ACTIVE;
974 if (file)
975 lru += LRU_FILE;
976 return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
977 mode, !!file);
Balbir Singh66e17072008-02-07 00:13:56 -0800978}
979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980/*
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700981 * clear_active_flags() is a helper for shrink_active_list(), clearing
982 * any active bits from the pages in the list.
983 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700984static unsigned long clear_active_flags(struct list_head *page_list,
985 unsigned int *count)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700986{
987 int nr_active = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700988 int lru;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700989 struct page *page;
990
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700991 list_for_each_entry(page, page_list, lru) {
992 lru = page_is_file_cache(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700993 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700994 lru += LRU_ACTIVE;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700995 ClearPageActive(page);
996 nr_active++;
997 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700998 count[lru]++;
999 }
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001000
1001 return nr_active;
1002}
1003
Nick Piggin62695a82008-10-18 20:26:09 -07001004/**
1005 * isolate_lru_page - tries to isolate a page from its LRU list
1006 * @page: page to isolate from its LRU list
1007 *
1008 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1009 * vmstat statistic corresponding to whatever LRU list the page was on.
1010 *
1011 * Returns 0 if the page was removed from an LRU list.
1012 * Returns -EBUSY if the page was not on an LRU list.
1013 *
1014 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001015 * the active list, it will have PageActive set. If it was found on
1016 * the unevictable list, it will have the PageUnevictable bit set. That flag
1017 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001018 *
1019 * The vmstat statistic corresponding to the list on which the page was
1020 * found will be decremented.
1021 *
1022 * Restrictions:
1023 * (1) Must be called with an elevated refcount on the page. This is a
1024 * fundamentnal difference from isolate_lru_pages (which is called
1025 * without a stable reference).
1026 * (2) the lru_lock must not be held.
1027 * (3) interrupts must be enabled.
1028 */
1029int isolate_lru_page(struct page *page)
1030{
1031 int ret = -EBUSY;
1032
1033 if (PageLRU(page)) {
1034 struct zone *zone = page_zone(page);
1035
1036 spin_lock_irq(&zone->lru_lock);
1037 if (PageLRU(page) && get_page_unless_zero(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001038 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001039 ret = 0;
1040 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001041
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001042 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001043 }
1044 spin_unlock_irq(&zone->lru_lock);
1045 }
1046 return ret;
1047}
1048
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001049/*
Andrew Morton1742f192006-03-22 00:08:21 -08001050 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1051 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 */
Andrew Morton1742f192006-03-22 00:08:21 -08001053static unsigned long shrink_inactive_list(unsigned long max_scan,
Rik van Riel33c120e2008-10-18 20:26:36 -07001054 struct zone *zone, struct scan_control *sc,
1055 int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056{
1057 LIST_HEAD(page_list);
1058 struct pagevec pvec;
Andrew Morton69e05942006-03-22 00:08:19 -08001059 unsigned long nr_scanned = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -08001060 unsigned long nr_reclaimed = 0;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001061 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
1063 pagevec_init(&pvec, 1);
1064
1065 lru_add_drain();
1066 spin_lock_irq(&zone->lru_lock);
Andrew Morton69e05942006-03-22 00:08:19 -08001067 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 struct page *page;
Andrew Morton69e05942006-03-22 00:08:19 -08001069 unsigned long nr_taken;
1070 unsigned long nr_scan;
1071 unsigned long nr_freed;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001072 unsigned long nr_active;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001073 unsigned int count[NR_LRU_LISTS] = { 0, };
Rik van Riel33c120e2008-10-18 20:26:36 -07001074 int mode = ISOLATE_INACTIVE;
1075
1076 /*
1077 * If we need a large contiguous chunk of memory, or have
1078 * trouble getting a small set of contiguous pages, we
1079 * will reclaim both active and inactive pages.
1080 *
1081 * We use the same threshold as pageout congestion_wait below.
1082 */
1083 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1084 mode = ISOLATE_BOTH;
1085 else if (sc->order && priority < DEF_PRIORITY - 2)
1086 mode = ISOLATE_BOTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087
Balbir Singh66e17072008-02-07 00:13:56 -08001088 nr_taken = sc->isolate_pages(sc->swap_cluster_max,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001089 &page_list, &nr_scan, sc->order, mode,
1090 zone, sc->mem_cgroup, 0, file);
1091 nr_active = clear_active_flags(&page_list, count);
Andy Whitcrofte9187bd2007-08-22 14:01:25 -07001092 __count_vm_events(PGDEACTIVATE, nr_active);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001093
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001094 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1095 -count[LRU_ACTIVE_FILE]);
1096 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1097 -count[LRU_INACTIVE_FILE]);
1098 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1099 -count[LRU_ACTIVE_ANON]);
1100 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1101 -count[LRU_INACTIVE_ANON]);
1102
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001103 if (scanning_global_lru(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001104 zone->pages_scanned += nr_scan;
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -08001105
1106 reclaim_stat->recent_scanned[0] += count[LRU_INACTIVE_ANON];
1107 reclaim_stat->recent_scanned[0] += count[LRU_ACTIVE_ANON];
1108 reclaim_stat->recent_scanned[1] += count[LRU_INACTIVE_FILE];
1109 reclaim_stat->recent_scanned[1] += count[LRU_ACTIVE_FILE];
1110
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 spin_unlock_irq(&zone->lru_lock);
1112
Andrew Morton69e05942006-03-22 00:08:19 -08001113 nr_scanned += nr_scan;
Andy Whitcroftc661b072007-08-22 14:01:26 -07001114 nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
1115
1116 /*
1117 * If we are direct reclaiming for contiguous pages and we do
1118 * not reclaim everything in the list, try again and wait
1119 * for IO to complete. This will stall high-order allocations
1120 * but that should be acceptable to the caller
1121 */
1122 if (nr_freed < nr_taken && !current_is_kswapd() &&
1123 sc->order > PAGE_ALLOC_COSTLY_ORDER) {
1124 congestion_wait(WRITE, HZ/10);
1125
1126 /*
1127 * The attempt at page out may have made some
1128 * of the pages active, mark them inactive again.
1129 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001130 nr_active = clear_active_flags(&page_list, count);
Andy Whitcroftc661b072007-08-22 14:01:26 -07001131 count_vm_events(PGDEACTIVATE, nr_active);
1132
1133 nr_freed += shrink_page_list(&page_list, sc,
1134 PAGEOUT_IO_SYNC);
1135 }
1136
Andrew Morton05ff5132006-03-22 00:08:20 -08001137 nr_reclaimed += nr_freed;
Nick Piggina74609f2006-01-06 00:11:20 -08001138 local_irq_disable();
1139 if (current_is_kswapd()) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001140 __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);
1141 __count_vm_events(KSWAPD_STEAL, nr_freed);
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001142 } else if (scanning_global_lru(sc))
Christoph Lameterf8891e52006-06-30 01:55:45 -07001143 __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001144
Shantanu Goel918d3f92006-12-29 16:48:59 -08001145 __count_zone_vm_events(PGSTEAL, zone, nr_freed);
Nick Piggina74609f2006-01-06 00:11:20 -08001146
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001147 if (nr_taken == 0)
1148 goto done;
1149
Nick Piggina74609f2006-01-06 00:11:20 -08001150 spin_lock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 /*
1152 * Put back any unfreeable pages.
1153 */
1154 while (!list_empty(&page_list)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001155 int lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 page = lru_to_page(&page_list);
Nick Piggin725d7042006-09-25 23:30:55 -07001157 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 list_del(&page->lru);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001159 if (unlikely(!page_evictable(page, NULL))) {
1160 spin_unlock_irq(&zone->lru_lock);
1161 putback_lru_page(page);
1162 spin_lock_irq(&zone->lru_lock);
1163 continue;
1164 }
1165 SetPageLRU(page);
1166 lru = page_lru(page);
1167 add_page_to_lru_list(zone, page, lru);
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -08001168 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001169 int file = !!page_is_file_cache(page);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001170 reclaim_stat->recent_rotated[file]++;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001171 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 if (!pagevec_add(&pvec, page)) {
1173 spin_unlock_irq(&zone->lru_lock);
1174 __pagevec_release(&pvec);
1175 spin_lock_irq(&zone->lru_lock);
1176 }
1177 }
Andrew Morton69e05942006-03-22 00:08:19 -08001178 } while (nr_scanned < max_scan);
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001179 spin_unlock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180done:
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001181 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182 pagevec_release(&pvec);
Andrew Morton05ff5132006-03-22 00:08:20 -08001183 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184}
1185
Martin Bligh3bb1a852006-10-28 10:38:24 -07001186/*
1187 * We are about to scan this zone at a certain priority level. If that priority
1188 * level is smaller (ie: more urgent) than the previous priority, then note
1189 * that priority level within the zone. This is done so that when the next
1190 * process comes in to scan this zone, it will immediately start out at this
1191 * priority level rather than having to build up its own scanning priority.
1192 * Here, this priority affects only the reclaim-mapped threshold.
1193 */
1194static inline void note_zone_scanning_priority(struct zone *zone, int priority)
1195{
1196 if (priority < zone->prev_priority)
1197 zone->prev_priority = priority;
1198}
1199
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001200/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 * This moves pages from the active list to the inactive list.
1202 *
1203 * We move them the other way if the page is referenced by one or more
1204 * processes, from rmap.
1205 *
1206 * If the pages are mostly unmapped, the processing is fast and it is
1207 * appropriate to hold zone->lru_lock across the whole operation. But if
1208 * the pages are mapped, the processing is slow (page_referenced()) so we
1209 * should drop zone->lru_lock around each page. It's impossible to balance
1210 * this, so instead we remove the pages from the LRU while processing them.
1211 * It is safe to rely on PG_active against the non-LRU pages in here because
1212 * nobody will play with that bit on a non-LRU page.
1213 *
1214 * The downside is that we have to touch page->_count against each page.
1215 * But we had to alter page->flags anyway.
1216 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001217
1218
Andrew Morton1742f192006-03-22 00:08:21 -08001219static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001220 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221{
Andrew Morton69e05942006-03-22 00:08:19 -08001222 unsigned long pgmoved;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223 int pgdeactivate = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001224 unsigned long pgscanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 LIST_HEAD(l_hold); /* The pages which were snipped off */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001226 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 struct page *page;
1228 struct pagevec pvec;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001229 enum lru_list lru;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001230 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231
1232 lru_add_drain();
1233 spin_lock_irq(&zone->lru_lock);
Balbir Singh66e17072008-02-07 00:13:56 -08001234 pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
1235 ISOLATE_ACTIVE, zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001236 sc->mem_cgroup, 1, file);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001237 /*
1238 * zone->pages_scanned is used for detect zone's oom
1239 * mem_cgroup remembers nr_scan by itself.
1240 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001241 if (scanning_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001242 zone->pages_scanned += pgscanned;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001243 }
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -08001244 reclaim_stat->recent_scanned[!!file] += pgmoved;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001245
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001246 if (file)
1247 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
1248 else
1249 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 spin_unlock_irq(&zone->lru_lock);
1251
Rik van Riel556adec2008-10-18 20:26:34 -07001252 pgmoved = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 while (!list_empty(&l_hold)) {
1254 cond_resched();
1255 page = lru_to_page(&l_hold);
1256 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001257
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001258 if (unlikely(!page_evictable(page, NULL))) {
1259 putback_lru_page(page);
1260 continue;
1261 }
1262
Rik van Riel7e9cd482008-10-18 20:26:35 -07001263 /* page_referenced clears PageReferenced */
1264 if (page_mapping_inuse(page) &&
1265 page_referenced(page, 0, sc->mem_cgroup))
1266 pgmoved++;
1267
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268 list_add(&page->lru, &l_inactive);
1269 }
1270
Andrew Mortonb5557492009-01-06 14:40:13 -08001271 /*
1272 * Move the pages to the [file or anon] inactive list.
1273 */
1274 pagevec_init(&pvec, 1);
Andrew Mortonb5557492009-01-06 14:40:13 -08001275 lru = LRU_BASE + file * LRU_FILE;
1276
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001277 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001278 /*
Rik van Riel7e9cd482008-10-18 20:26:35 -07001279 * Count referenced pages from currently used mappings as
1280 * rotated, even though they are moved to the inactive list.
1281 * This helps balance scan pressure between file and anonymous
1282 * pages in get_scan_ratio.
1283 */
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -08001284 reclaim_stat->recent_rotated[!!file] += pgmoved;
Rik van Riel556adec2008-10-18 20:26:34 -07001285
Daisuke Nishimura1d885522009-03-13 13:52:00 -07001286 pgmoved = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 while (!list_empty(&l_inactive)) {
1288 page = lru_to_page(&l_inactive);
1289 prefetchw_prev_lru_page(page, &l_inactive, flags);
Nick Piggin725d7042006-09-25 23:30:55 -07001290 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001291 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -07001292 VM_BUG_ON(!PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -08001293 ClearPageActive(page);
1294
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001295 list_move(&page->lru, &zone->lru[lru].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08001296 mem_cgroup_add_lru_list(page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 pgmoved++;
1298 if (!pagevec_add(&pvec, page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001299 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 spin_unlock_irq(&zone->lru_lock);
1301 pgdeactivate += pgmoved;
1302 pgmoved = 0;
1303 if (buffer_heads_over_limit)
1304 pagevec_strip(&pvec);
1305 __pagevec_release(&pvec);
1306 spin_lock_irq(&zone->lru_lock);
1307 }
1308 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001309 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 pgdeactivate += pgmoved;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001311 __count_zone_vm_events(PGREFILL, zone, pgscanned);
1312 __count_vm_events(PGDEACTIVATE, pgdeactivate);
1313 spin_unlock_irq(&zone->lru_lock);
Johannes Weiner24434622009-03-31 15:23:12 -07001314 if (buffer_heads_over_limit)
1315 pagevec_strip(&pvec);
Nick Piggina74609f2006-01-06 00:11:20 -08001316 pagevec_release(&pvec);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317}
1318
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001319static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001320{
1321 unsigned long active, inactive;
1322
1323 active = zone_page_state(zone, NR_ACTIVE_ANON);
1324 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1325
1326 if (inactive * zone->inactive_ratio < active)
1327 return 1;
1328
1329 return 0;
1330}
1331
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001332/**
1333 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1334 * @zone: zone to check
1335 * @sc: scan control of this context
1336 *
1337 * Returns true if the zone does not have enough inactive anon pages,
1338 * meaning some active anon pages need to be deactivated.
1339 */
1340static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc)
1341{
1342 int low;
1343
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001344 if (scanning_global_lru(sc))
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001345 low = inactive_anon_is_low_global(zone);
1346 else
KOSAKI Motohiroc772be92009-01-07 18:08:25 -08001347 low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001348 return low;
1349}
1350
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001351static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Christoph Lameterb69408e2008-10-18 20:26:14 -07001352 struct zone *zone, struct scan_control *sc, int priority)
1353{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001354 int file = is_file_lru(lru);
1355
Rik van Riel556adec2008-10-18 20:26:34 -07001356 if (lru == LRU_ACTIVE_FILE) {
1357 shrink_active_list(nr_to_scan, zone, sc, priority, file);
1358 return 0;
1359 }
1360
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001361 if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001362 shrink_active_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001363 return 0;
1364 }
Rik van Riel33c120e2008-10-18 20:26:36 -07001365 return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001366}
1367
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001369 * Determine how aggressively the anon and file LRU lists should be
1370 * scanned. The relative value of each set of LRU lists is determined
1371 * by looking at the fraction of the pages scanned we did rotate back
1372 * onto the active list instead of evict.
1373 *
1374 * percent[0] specifies how much pressure to put on ram/swap backed
1375 * memory, while percent[1] determines pressure on the file LRUs.
1376 */
1377static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
1378 unsigned long *percent)
1379{
1380 unsigned long anon, file, free;
1381 unsigned long anon_prio, file_prio;
1382 unsigned long ap, fp;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001383 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001384
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001385 /* If we have no swap space, do not bother scanning anon pages. */
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07001386 if (!sc->may_swap || (nr_swap_pages <= 0)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001387 percent[0] = 0;
1388 percent[1] = 100;
1389 return;
1390 }
1391
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -08001392 anon = zone_nr_pages(zone, sc, LRU_ACTIVE_ANON) +
1393 zone_nr_pages(zone, sc, LRU_INACTIVE_ANON);
1394 file = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) +
1395 zone_nr_pages(zone, sc, LRU_INACTIVE_FILE);
Hugh Dickinsb9627162009-01-06 14:39:41 -08001396
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001397 if (scanning_global_lru(sc)) {
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001398 free = zone_page_state(zone, NR_FREE_PAGES);
1399 /* If we have very few page cache pages,
1400 force-scan anon pages. */
1401 if (unlikely(file + free <= zone->pages_high)) {
1402 percent[0] = 100;
1403 percent[1] = 0;
1404 return;
1405 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001406 }
1407
1408 /*
1409 * OK, so we have swap space and a fair amount of page cache
1410 * pages. We use the recently rotated / recently scanned
1411 * ratios to determine how valuable each cache is.
1412 *
1413 * Because workloads change over time (and to avoid overflow)
1414 * we keep these statistics as a floating average, which ends
1415 * up weighing recent references more than old ones.
1416 *
1417 * anon in [0], file in [1]
1418 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001419 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001420 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001421 reclaim_stat->recent_scanned[0] /= 2;
1422 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001423 spin_unlock_irq(&zone->lru_lock);
1424 }
1425
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001426 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001427 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001428 reclaim_stat->recent_scanned[1] /= 2;
1429 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001430 spin_unlock_irq(&zone->lru_lock);
1431 }
1432
1433 /*
1434 * With swappiness at 100, anonymous and file have the same priority.
1435 * This scanning priority is essentially the inverse of IO cost.
1436 */
1437 anon_prio = sc->swappiness;
1438 file_prio = 200 - sc->swappiness;
1439
1440 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001441 * The amount of pressure on anon vs file pages is inversely
1442 * proportional to the fraction of recently scanned pages on
1443 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001444 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001445 ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
1446 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001447
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001448 fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
1449 fp /= reclaim_stat->recent_rotated[1] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001450
1451 /* Normalize to percentages */
1452 percent[0] = 100 * ap / (ap + fp + 1);
1453 percent[1] = 100 - percent[0];
1454}
1455
1456
1457/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1459 */
Rik van Riela79311c2009-01-06 14:40:01 -08001460static void shrink_zone(int priority, struct zone *zone,
Andrew Morton05ff5132006-03-22 00:08:20 -08001461 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462{
Christoph Lameterb69408e2008-10-18 20:26:14 -07001463 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08001464 unsigned long nr_to_scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001465 unsigned long percent[2]; /* anon @ 0; file @ 1 */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001466 enum lru_list l;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001467 unsigned long nr_reclaimed = sc->nr_reclaimed;
1468 unsigned long swap_cluster_max = sc->swap_cluster_max;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001470 get_scan_ratio(zone, sc, percent);
1471
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001472 for_each_evictable_lru(l) {
KOSAKI Motohiro9439c1c2009-01-07 18:08:21 -08001473 int file = is_file_lru(l);
1474 int scan;
Johannes Weinere0f79b82008-10-18 20:26:55 -07001475
KOSAKI Motohirof272b7b2009-03-12 14:31:36 -07001476 scan = zone_nr_pages(zone, sc, l);
KOSAKI Motohiro9439c1c2009-01-07 18:08:21 -08001477 if (priority) {
1478 scan >>= priority;
1479 scan = (scan * percent[file]) / 100;
1480 }
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001481 if (scanning_global_lru(sc)) {
Johannes Weinere0f79b82008-10-18 20:26:55 -07001482 zone->lru[l].nr_scan += scan;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001483 nr[l] = zone->lru[l].nr_scan;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001484 if (nr[l] >= swap_cluster_max)
Christoph Lameterb69408e2008-10-18 20:26:14 -07001485 zone->lru[l].nr_scan = 0;
1486 else
1487 nr[l] = 0;
KOSAKI Motohiro9439c1c2009-01-07 18:08:21 -08001488 } else
1489 nr[l] = scan;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001490 }
1491
Rik van Riel556adec2008-10-18 20:26:34 -07001492 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1493 nr[LRU_INACTIVE_FILE]) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001494 for_each_evictable_lru(l) {
Christoph Lameterb69408e2008-10-18 20:26:14 -07001495 if (nr[l]) {
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001496 nr_to_scan = min(nr[l], swap_cluster_max);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001497 nr[l] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001499 nr_reclaimed += shrink_list(l, nr_to_scan,
1500 zone, sc, priority);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001501 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 }
Rik van Riela79311c2009-01-06 14:40:01 -08001503 /*
1504 * On large memory systems, scan >> priority can become
1505 * really large. This is fine for the starting priority;
1506 * we want to put equal scanning pressure on each zone.
1507 * However, if the VM has a harder time of freeing pages,
1508 * with multiple processes reclaiming pages, the total
1509 * freeing target can get unreasonably large.
1510 */
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001511 if (nr_reclaimed > swap_cluster_max &&
Rik van Riela79311c2009-01-06 14:40:01 -08001512 priority < DEF_PRIORITY && !current_is_kswapd())
1513 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 }
1515
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001516 sc->nr_reclaimed = nr_reclaimed;
1517
Rik van Riel556adec2008-10-18 20:26:34 -07001518 /*
1519 * Even if we did not try to evict anon pages at all, we want to
1520 * rebalance the anon lru active/inactive ratio.
1521 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001522 if (inactive_anon_is_low(zone, sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001523 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1524
Andrew Morton232ea4d2007-02-28 20:13:21 -08001525 throttle_vm_writeout(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526}
1527
1528/*
1529 * This is the direct reclaim path, for page-allocating processes. We only
1530 * try to reclaim pages from zones which will satisfy the caller's allocation
1531 * request.
1532 *
1533 * We reclaim from a zone even if that zone is over pages_high. Because:
1534 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
1535 * allocation or
1536 * b) The zones may be over pages_high but they must go *over* pages_high to
1537 * satisfy the `incremental min' zone defense algorithm.
1538 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 * If a zone is deemed to be full of pinned pages then just give it a light
1540 * scan then give up on it.
1541 */
Rik van Riela79311c2009-01-06 14:40:01 -08001542static void shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08001543 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544{
Mel Gorman54a6eb52008-04-28 02:12:16 -07001545 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Mel Gormandd1a2392008-04-28 02:12:17 -07001546 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001547 struct zone *zone;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001548
Nick Piggin408d8542006-09-25 23:31:27 -07001549 sc->all_unreclaimable = 1;
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07001550 for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
1551 sc->nodemask) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08001552 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001554 /*
1555 * Take care memory controller reclaiming has small influence
1556 * to global LRU.
1557 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001558 if (scanning_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001559 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1560 continue;
1561 note_zone_scanning_priority(zone, priority);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001563 if (zone_is_all_unreclaimable(zone) &&
1564 priority != DEF_PRIORITY)
1565 continue; /* Let kswapd poll it */
1566 sc->all_unreclaimable = 0;
1567 } else {
1568 /*
1569 * Ignore cpuset limitation here. We just want to reduce
1570 * # of used pages by us regardless of memory shortage.
1571 */
1572 sc->all_unreclaimable = 0;
1573 mem_cgroup_note_reclaim_priority(sc->mem_cgroup,
1574 priority);
1575 }
Nick Piggin408d8542006-09-25 23:31:27 -07001576
Rik van Riela79311c2009-01-06 14:40:01 -08001577 shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 }
1579}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001580
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581/*
1582 * This is the main entry point to direct page reclaim.
1583 *
1584 * If a full scan of the inactive list fails to free enough memory then we
1585 * are "out of memory" and something needs to be killed.
1586 *
1587 * If the caller is !__GFP_FS then the probability of a failure is reasonably
1588 * high - the zone may be full of dirty or under-writeback pages, which this
1589 * caller can't do much about. We kick pdflush and take explicit naps in the
1590 * hope that some of these pages can be written. But if the allocating task
1591 * holds filesystem locks which prevent writeout this might not work, and the
1592 * allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07001593 *
1594 * returns: 0, if no pages reclaimed
1595 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 */
Mel Gormandac1d272008-04-28 02:12:12 -07001597static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Mel Gormandd1a2392008-04-28 02:12:17 -07001598 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599{
1600 int priority;
kosaki.motohiro@jp.fujitsu.comc700be32008-06-12 15:21:27 -07001601 unsigned long ret = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001602 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 struct reclaim_state *reclaim_state = current->reclaim_state;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 unsigned long lru_pages = 0;
Mel Gormandd1a2392008-04-28 02:12:17 -07001605 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001606 struct zone *zone;
Mel Gormandd1a2392008-04-28 02:12:17 -07001607 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
Keika Kobayashi873b4772008-07-25 01:48:52 -07001609 delayacct_freepages_start();
1610
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001611 if (scanning_global_lru(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001612 count_vm_event(ALLOCSTALL);
1613 /*
1614 * mem_cgroup will not do shrink_slab.
1615 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001616 if (scanning_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001617 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001619 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1620 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001622 lru_pages += zone_lru_pages(zone);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001623 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 }
1625
1626 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08001627 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001628 if (!priority)
1629 disable_swap_token();
Rik van Riela79311c2009-01-06 14:40:01 -08001630 shrink_zones(priority, zonelist, sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001631 /*
1632 * Don't shrink slabs when reclaiming memory from
1633 * over limit cgroups
1634 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001635 if (scanning_global_lru(sc)) {
Mel Gormandd1a2392008-04-28 02:12:17 -07001636 shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001637 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08001638 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001639 reclaim_state->reclaimed_slab = 0;
1640 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 }
Balbir Singh66e17072008-02-07 00:13:56 -08001642 total_scanned += sc->nr_scanned;
Rik van Riela79311c2009-01-06 14:40:01 -08001643 if (sc->nr_reclaimed >= sc->swap_cluster_max) {
1644 ret = sc->nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 goto out;
1646 }
1647
1648 /*
1649 * Try to write back as many pages as we just scanned. This
1650 * tends to cause slow streaming writers to write data to the
1651 * disk smoothly, at the dirtying rate, which is nice. But
1652 * that's undesirable in laptop mode, where we *want* lumpy
1653 * writeout. So in laptop mode, write out the whole world.
1654 */
Balbir Singh66e17072008-02-07 00:13:56 -08001655 if (total_scanned > sc->swap_cluster_max +
1656 sc->swap_cluster_max / 2) {
Pekka J Enberg687a21c2005-06-28 20:44:55 -07001657 wakeup_pdflush(laptop_mode ? 0 : total_scanned);
Balbir Singh66e17072008-02-07 00:13:56 -08001658 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 }
1660
1661 /* Take a nap, wait for some writeback to complete */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001662 if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001663 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 }
Fernando Luis Vazquez Cao87547ee2008-07-29 22:33:42 -07001665 /* top priority shrink_zones still had more to do? don't OOM, then */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001666 if (!sc->all_unreclaimable && scanning_global_lru(sc))
Rik van Riela79311c2009-01-06 14:40:01 -08001667 ret = sc->nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668out:
Martin Bligh3bb1a852006-10-28 10:38:24 -07001669 /*
1670 * Now that we've scanned all the zones at this priority level, note
1671 * that level within the zone so that the next thread which performs
1672 * scanning of this zone will immediately start out at this priority
1673 * level. This affects only the decision whether or not to bring
1674 * mapped pages onto the inactive list.
1675 */
1676 if (priority < 0)
1677 priority = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001679 if (scanning_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001680 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001682 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1683 continue;
1684
1685 zone->prev_priority = priority;
1686 }
1687 } else
1688 mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority);
1689
Keika Kobayashi873b4772008-07-25 01:48:52 -07001690 delayacct_freepages_end();
1691
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 return ret;
1693}
1694
Mel Gormandac1d272008-04-28 02:12:12 -07001695unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07001696 gfp_t gfp_mask, nodemask_t *nodemask)
Balbir Singh66e17072008-02-07 00:13:56 -08001697{
1698 struct scan_control sc = {
1699 .gfp_mask = gfp_mask,
1700 .may_writepage = !laptop_mode,
1701 .swap_cluster_max = SWAP_CLUSTER_MAX,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07001702 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07001703 .may_swap = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08001704 .swappiness = vm_swappiness,
1705 .order = order,
1706 .mem_cgroup = NULL,
1707 .isolate_pages = isolate_pages_global,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07001708 .nodemask = nodemask,
Balbir Singh66e17072008-02-07 00:13:56 -08001709 };
1710
Mel Gormandd1a2392008-04-28 02:12:17 -07001711 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001712}
1713
Balbir Singh00f0b822008-03-04 14:28:39 -08001714#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08001715
Balbir Singhe1a1cd52008-02-07 00:14:02 -08001716unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08001717 gfp_t gfp_mask,
1718 bool noswap,
1719 unsigned int swappiness)
Balbir Singh66e17072008-02-07 00:13:56 -08001720{
1721 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08001722 .may_writepage = !laptop_mode,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07001723 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07001724 .may_swap = !noswap,
Balbir Singh66e17072008-02-07 00:13:56 -08001725 .swap_cluster_max = SWAP_CLUSTER_MAX,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08001726 .swappiness = swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08001727 .order = 0,
1728 .mem_cgroup = mem_cont,
1729 .isolate_pages = mem_cgroup_isolate_pages,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07001730 .nodemask = NULL, /* we don't care the placement */
Balbir Singh66e17072008-02-07 00:13:56 -08001731 };
Mel Gormandac1d272008-04-28 02:12:12 -07001732 struct zonelist *zonelist;
Balbir Singh66e17072008-02-07 00:13:56 -08001733
Mel Gormandd1a2392008-04-28 02:12:17 -07001734 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
1735 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
1736 zonelist = NODE_DATA(numa_node_id())->node_zonelists;
1737 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001738}
1739#endif
1740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741/*
1742 * For kswapd, balance_pgdat() will work across all this node's zones until
1743 * they are all at pages_high.
1744 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 * Returns the number of pages which were actually freed.
1746 *
1747 * There is special handling here for zones which are full of pinned pages.
1748 * This can happen if the pages are all mlocked, or if they are all used by
1749 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
1750 * What we do is to detect the case where all pages in the zone have been
1751 * scanned twice and there has been zero successful reclaim. Mark the zone as
1752 * dead and from now on, only perform a short scan. Basically we're polling
1753 * the zone for when the problem goes away.
1754 *
1755 * kswapd scans the zones in the highmem->normal->dma direction. It skips
1756 * zones which have free_pages > pages_high, but once a zone is found to have
1757 * free_pages <= pages_high, we scan that zone and the lower zones regardless
1758 * of the number of free pages in the lower zones. This interoperates with
1759 * the page allocator fallback scheme to ensure that aging of pages is balanced
1760 * across the zones.
1761 */
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001762static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 int all_zones_ok;
1765 int priority;
1766 int i;
Andrew Morton69e05942006-03-22 00:08:19 -08001767 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 struct reclaim_state *reclaim_state = current->reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08001769 struct scan_control sc = {
1770 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07001771 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07001772 .may_swap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001773 .swap_cluster_max = SWAP_CLUSTER_MAX,
1774 .swappiness = vm_swappiness,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001775 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08001776 .mem_cgroup = NULL,
1777 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08001778 };
Martin Bligh3bb1a852006-10-28 10:38:24 -07001779 /*
1780 * temp_priority is used to remember the scanning priority at which
1781 * this zone was successfully refilled to free_pages == pages_high.
1782 */
1783 int temp_priority[MAX_NR_ZONES];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784
1785loop_again:
1786 total_scanned = 0;
Rik van Riela79311c2009-01-06 14:40:01 -08001787 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07001788 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001789 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790
Martin Bligh3bb1a852006-10-28 10:38:24 -07001791 for (i = 0; i < pgdat->nr_zones; i++)
1792 temp_priority[i] = DEF_PRIORITY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793
1794 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
1795 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
1796 unsigned long lru_pages = 0;
1797
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001798 /* The swap token gets in the way of swapout... */
1799 if (!priority)
1800 disable_swap_token();
1801
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802 all_zones_ok = 1;
1803
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001804 /*
1805 * Scan in the highmem->dma direction for the highest
1806 * zone which needs scanning
1807 */
1808 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
1809 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001811 if (!populated_zone(zone))
1812 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
David Rientjese815af92007-10-16 23:25:54 -07001814 if (zone_is_all_unreclaimable(zone) &&
1815 priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001816 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817
Rik van Riel556adec2008-10-18 20:26:34 -07001818 /*
1819 * Do some background aging of the anon list, to give
1820 * pages a chance to be referenced before reclaiming.
1821 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001822 if (inactive_anon_is_low(zone, &sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001823 shrink_active_list(SWAP_CLUSTER_MAX, zone,
1824 &sc, priority, 0);
1825
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001826 if (!zone_watermark_ok(zone, order, zone->pages_high,
1827 0, 0)) {
1828 end_zone = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001829 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001832 if (i < 0)
1833 goto out;
1834
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835 for (i = 0; i <= end_zone; i++) {
1836 struct zone *zone = pgdat->node_zones + i;
1837
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001838 lru_pages += zone_lru_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 }
1840
1841 /*
1842 * Now scan the zone in the dma->highmem direction, stopping
1843 * at the last zone which needs scanning.
1844 *
1845 * We do this because the page allocator works in the opposite
1846 * direction. This prevents the page allocator from allocating
1847 * pages behind kswapd's direction of progress, which would
1848 * cause too much scanning of the lower zones.
1849 */
1850 for (i = 0; i <= end_zone; i++) {
1851 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001852 int nr_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853
Con Kolivasf3fe6512006-01-06 00:11:15 -08001854 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855 continue;
1856
David Rientjese815af92007-10-16 23:25:54 -07001857 if (zone_is_all_unreclaimable(zone) &&
1858 priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 continue;
1860
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001861 if (!zone_watermark_ok(zone, order, zone->pages_high,
1862 end_zone, 0))
1863 all_zones_ok = 0;
Martin Bligh3bb1a852006-10-28 10:38:24 -07001864 temp_priority[i] = priority;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 sc.nr_scanned = 0;
Martin Bligh3bb1a852006-10-28 10:38:24 -07001866 note_zone_scanning_priority(zone, priority);
Rik van Riel32a43302007-10-16 01:24:50 -07001867 /*
1868 * We put equal pressure on every zone, unless one
1869 * zone has way too many pages free already.
1870 */
1871 if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
1872 end_zone, 0))
Rik van Riela79311c2009-01-06 14:40:01 -08001873 shrink_zone(priority, zone, &sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 reclaim_state->reclaimed_slab = 0;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001875 nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
1876 lru_pages);
Rik van Riela79311c2009-01-06 14:40:01 -08001877 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 total_scanned += sc.nr_scanned;
David Rientjese815af92007-10-16 23:25:54 -07001879 if (zone_is_all_unreclaimable(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 continue;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001881 if (nr_slab == 0 && zone->pages_scanned >=
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001882 (zone_lru_pages(zone) * 6))
David Rientjese815af92007-10-16 23:25:54 -07001883 zone_set_flag(zone,
1884 ZONE_ALL_UNRECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885 /*
1886 * If we've done a decent amount of scanning and
1887 * the reclaim ratio is low, start doing writepage
1888 * even in laptop mode
1889 */
1890 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08001891 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 sc.may_writepage = 1;
1893 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894 if (all_zones_ok)
1895 break; /* kswapd: all done */
1896 /*
1897 * OK, kswapd is getting into trouble. Take a nap, then take
1898 * another pass across the zones.
1899 */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001900 if (total_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001901 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902
1903 /*
1904 * We do this so kswapd doesn't build up large priorities for
1905 * example when it is freeing in parallel with allocators. It
1906 * matches the direct reclaim path behaviour in terms of impact
1907 * on zone->*_priority.
1908 */
Rik van Riela79311c2009-01-06 14:40:01 -08001909 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 break;
1911 }
1912out:
Martin Bligh3bb1a852006-10-28 10:38:24 -07001913 /*
1914 * Note within each zone the priority level at which this zone was
1915 * brought into a happy state. So that the next thread which scans this
1916 * zone will start out at that priority level.
1917 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 for (i = 0; i < pgdat->nr_zones; i++) {
1919 struct zone *zone = pgdat->node_zones + i;
1920
Martin Bligh3bb1a852006-10-28 10:38:24 -07001921 zone->prev_priority = temp_priority[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 }
1923 if (!all_zones_ok) {
1924 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08001925
1926 try_to_freeze();
1927
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08001928 /*
1929 * Fragmentation may mean that the system cannot be
1930 * rebalanced for high-order allocations in all zones.
1931 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
1932 * it means the zones have been fully scanned and are still
1933 * not balanced. For high-order allocations, there is
1934 * little point trying all over again as kswapd may
1935 * infinite loop.
1936 *
1937 * Instead, recheck all watermarks at order-0 as they
1938 * are the most important. If watermarks are ok, kswapd will go
1939 * back to sleep. High-order users can still perform direct
1940 * reclaim if they wish.
1941 */
1942 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
1943 order = sc.order = 0;
1944
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 goto loop_again;
1946 }
1947
Rik van Riela79311c2009-01-06 14:40:01 -08001948 return sc.nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949}
1950
1951/*
1952 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001953 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 *
1955 * This basically trickles out pages so that we have _some_
1956 * free memory available even if there is no other activity
1957 * that frees anything up. This is needed for things like routing
1958 * etc, where we otherwise might have all activity going on in
1959 * asynchronous contexts that cannot page things out.
1960 *
1961 * If there are applications that are active memory-allocators
1962 * (most normal use), this basically shouldn't matter.
1963 */
1964static int kswapd(void *p)
1965{
1966 unsigned long order;
1967 pg_data_t *pgdat = (pg_data_t*)p;
1968 struct task_struct *tsk = current;
1969 DEFINE_WAIT(wait);
1970 struct reclaim_state reclaim_state = {
1971 .reclaimed_slab = 0,
1972 };
Rusty Russella70f7302009-03-13 14:49:46 +10301973 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974
Nick Piggincf40bd12009-01-21 08:12:39 +01001975 lockdep_set_current_reclaim_state(GFP_KERNEL);
1976
Rusty Russell174596a2009-01-01 10:12:29 +10301977 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07001978 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 current->reclaim_state = &reclaim_state;
1980
1981 /*
1982 * Tell the memory management that we're a "memory allocator",
1983 * and that if we need more memory we should get access to it
1984 * regardless (see "__alloc_pages()"). "kswapd" should
1985 * never get caught in the normal page freeing logic.
1986 *
1987 * (Kswapd normally doesn't need memory anyway, but sometimes
1988 * you need a small amount of memory in order to be able to
1989 * page out something else, and this flag essentially protects
1990 * us from recursively trying to free more memory as we're
1991 * trying to free the first piece of memory in the first place).
1992 */
Christoph Lameter930d9152006-01-08 01:00:47 -08001993 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07001994 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995
1996 order = 0;
1997 for ( ; ; ) {
1998 unsigned long new_order;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07001999
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2001 new_order = pgdat->kswapd_max_order;
2002 pgdat->kswapd_max_order = 0;
2003 if (order < new_order) {
2004 /*
2005 * Don't sleep if someone wants a larger 'order'
2006 * allocation
2007 */
2008 order = new_order;
2009 } else {
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07002010 if (!freezing(current))
2011 schedule();
2012
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013 order = pgdat->kswapd_max_order;
2014 }
2015 finish_wait(&pgdat->kswapd_wait, &wait);
2016
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07002017 if (!try_to_freeze()) {
2018 /* We can speed up thawing tasks if we don't call
2019 * balance_pgdat after returning from the refrigerator
2020 */
2021 balance_pgdat(pgdat, order);
2022 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 }
2024 return 0;
2025}
2026
2027/*
2028 * A zone is low on free memory, so wake its kswapd task to service it.
2029 */
2030void wakeup_kswapd(struct zone *zone, int order)
2031{
2032 pg_data_t *pgdat;
2033
Con Kolivasf3fe6512006-01-06 00:11:15 -08002034 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 return;
2036
2037 pgdat = zone->zone_pgdat;
Rohit Seth7fb1d9f2005-11-13 16:06:43 -08002038 if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 return;
2040 if (pgdat->kswapd_max_order < order)
2041 pgdat->kswapd_max_order = order;
Paul Jackson02a0e532006-12-13 00:34:25 -08002042 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07002044 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07002046 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047}
2048
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002049unsigned long global_lru_pages(void)
2050{
2051 return global_page_state(NR_ACTIVE_ANON)
2052 + global_page_state(NR_ACTIVE_FILE)
2053 + global_page_state(NR_INACTIVE_ANON)
2054 + global_page_state(NR_INACTIVE_FILE);
2055}
2056
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057#ifdef CONFIG_PM
2058/*
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002059 * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages
MinChan Kimd9796772009-03-31 15:19:34 -07002060 * from LRU lists system-wide, for given pass and priority.
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002061 *
2062 * For pass > 3 we also try to shrink the LRU lists that contain a few pages
2063 */
MinChan Kimd9796772009-03-31 15:19:34 -07002064static void shrink_all_zones(unsigned long nr_pages, int prio,
Nigel Cunninghame07aa052006-12-22 01:07:21 -08002065 int pass, struct scan_control *sc)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002066{
2067 struct zone *zone;
MinChan Kimd9796772009-03-31 15:19:34 -07002068 unsigned long nr_reclaimed = 0;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002069
KOSAKI Motohiroee99c712009-03-31 15:19:31 -07002070 for_each_populated_zone(zone) {
Johannes Weiner0cb57252009-02-14 02:04:10 +01002071 enum lru_list l;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002072
David Rientjese815af92007-10-16 23:25:54 -07002073 if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002074 continue;
2075
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002076 for_each_evictable_lru(l) {
Johannes Weiner0cb57252009-02-14 02:04:10 +01002077 enum zone_stat_item ls = NR_LRU_BASE + l;
2078 unsigned long lru_pages = zone_page_state(zone, ls);
2079
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002080 /* For pass = 0, we don't shrink the active list */
Johannes Weiner0cb57252009-02-14 02:04:10 +01002081 if (pass == 0 && (l == LRU_ACTIVE_ANON ||
2082 l == LRU_ACTIVE_FILE))
Christoph Lameterb69408e2008-10-18 20:26:14 -07002083 continue;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002084
Johannes Weiner0cb57252009-02-14 02:04:10 +01002085 zone->lru[l].nr_scan += (lru_pages >> prio) + 1;
Christoph Lameterb69408e2008-10-18 20:26:14 -07002086 if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
Johannes Weiner0cb57252009-02-14 02:04:10 +01002087 unsigned long nr_to_scan;
2088
Christoph Lameterb69408e2008-10-18 20:26:14 -07002089 zone->lru[l].nr_scan = 0;
Johannes Weiner0cb57252009-02-14 02:04:10 +01002090 nr_to_scan = min(nr_pages, lru_pages);
MinChan Kimd9796772009-03-31 15:19:34 -07002091 nr_reclaimed += shrink_list(l, nr_to_scan, zone,
Christoph Lameterb69408e2008-10-18 20:26:14 -07002092 sc, prio);
MinChan Kimd9796772009-03-31 15:19:34 -07002093 if (nr_reclaimed >= nr_pages) {
Rafael J. Wysockia21e2552009-04-18 17:23:41 +02002094 sc->nr_reclaimed += nr_reclaimed;
MinChan Kimd9796772009-03-31 15:19:34 -07002095 return;
2096 }
Christoph Lameterb69408e2008-10-18 20:26:14 -07002097 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002098 }
2099 }
Rafael J. Wysockia21e2552009-04-18 17:23:41 +02002100 sc->nr_reclaimed += nr_reclaimed;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002101}
2102
2103/*
2104 * Try to free `nr_pages' of memory, system-wide, and return the number of
2105 * freed pages.
2106 *
2107 * Rather than trying to age LRUs the aim is to preserve the overall
2108 * LRU order by reclaiming preferentially
2109 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110 */
Andrew Morton69e05942006-03-22 00:08:19 -08002111unsigned long shrink_all_memory(unsigned long nr_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002113 unsigned long lru_pages, nr_slab;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002114 int pass;
2115 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002116 struct scan_control sc = {
2117 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002118 .may_unmap = 0,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002119 .may_writepage = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08002120 .isolate_pages = isolate_pages_global,
Rafael J. Wysockia21e2552009-04-18 17:23:41 +02002121 .nr_reclaimed = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122 };
2123
2124 current->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08002125
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002126 lru_pages = global_lru_pages();
Christoph Lameter972d1a72006-09-25 23:31:51 -07002127 nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002128 /* If slab caches are huge, it's better to hit them first */
2129 while (nr_slab >= lru_pages) {
2130 reclaim_state.reclaimed_slab = 0;
2131 shrink_slab(nr_pages, sc.gfp_mask, lru_pages);
2132 if (!reclaim_state.reclaimed_slab)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 break;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002134
MinChan Kimd9796772009-03-31 15:19:34 -07002135 sc.nr_reclaimed += reclaim_state.reclaimed_slab;
2136 if (sc.nr_reclaimed >= nr_pages)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002137 goto out;
2138
2139 nr_slab -= reclaim_state.reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002141
2142 /*
2143 * We try to shrink LRUs in 5 passes:
2144 * 0 = Reclaim from inactive_list only
2145 * 1 = Reclaim from active list but don't reclaim mapped
2146 * 2 = 2nd pass of type 1
2147 * 3 = Reclaim mapped (normal reclaim)
2148 * 4 = 2nd pass of type 3
2149 */
2150 for (pass = 0; pass < 5; pass++) {
2151 int prio;
2152
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002153 /* Force reclaiming mapped pages in the passes #3 and #4 */
Johannes Weiner30491032009-02-14 02:03:08 +01002154 if (pass > 2)
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002155 sc.may_unmap = 1;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002156
2157 for (prio = DEF_PRIORITY; prio >= 0; prio--) {
MinChan Kimd9796772009-03-31 15:19:34 -07002158 unsigned long nr_to_scan = nr_pages - sc.nr_reclaimed;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002159
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002160 sc.nr_scanned = 0;
Johannes Weiner9786bf82009-03-31 15:19:35 -07002161 sc.swap_cluster_max = nr_to_scan;
MinChan Kimd9796772009-03-31 15:19:34 -07002162 shrink_all_zones(nr_to_scan, prio, pass, &sc);
2163 if (sc.nr_reclaimed >= nr_pages)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002164 goto out;
2165
2166 reclaim_state.reclaimed_slab = 0;
Andrew Morton76395d32007-01-05 16:37:05 -08002167 shrink_slab(sc.nr_scanned, sc.gfp_mask,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002168 global_lru_pages());
MinChan Kimd9796772009-03-31 15:19:34 -07002169 sc.nr_reclaimed += reclaim_state.reclaimed_slab;
2170 if (sc.nr_reclaimed >= nr_pages)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002171 goto out;
2172
2173 if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07002174 congestion_wait(WRITE, HZ / 10);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002175 }
Rafael J. Wysocki248a0302006-03-22 00:09:04 -08002176 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002177
2178 /*
MinChan Kimd9796772009-03-31 15:19:34 -07002179 * If sc.nr_reclaimed = 0, we could not shrink LRUs, but there may be
2180 * something in slab caches
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002181 */
MinChan Kimd9796772009-03-31 15:19:34 -07002182 if (!sc.nr_reclaimed) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002183 do {
2184 reclaim_state.reclaimed_slab = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002185 shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
MinChan Kimd9796772009-03-31 15:19:34 -07002186 sc.nr_reclaimed += reclaim_state.reclaimed_slab;
2187 } while (sc.nr_reclaimed < nr_pages &&
2188 reclaim_state.reclaimed_slab > 0);
Andrew Morton76395d32007-01-05 16:37:05 -08002189 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002190
MinChan Kimd9796772009-03-31 15:19:34 -07002191
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002192out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 current->reclaim_state = NULL;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002194
MinChan Kimd9796772009-03-31 15:19:34 -07002195 return sc.nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196}
2197#endif
2198
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199/* It's optimal to keep kswapds on the same CPUs as their memory, but
2200 not required for correctness. So if the last cpu in a node goes
2201 away, we get changed to run anywhere: as the first one comes back,
2202 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07002203static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08002204 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002206 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002208 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002209 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07002210 pg_data_t *pgdat = NODE_DATA(nid);
Rusty Russella70f7302009-03-13 14:49:46 +10302211 const struct cpumask *mask;
2212
2213 mask = cpumask_of_node(pgdat->node_id);
Mike Travisc5f59f02008-04-04 18:11:10 -07002214
Rusty Russell3e597942009-01-01 10:12:24 +10302215 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07002217 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 }
2219 }
2220 return NOTIFY_OK;
2221}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222
Yasunori Goto3218ae12006-06-27 02:53:33 -07002223/*
2224 * This kswapd start function will be called by init and node-hot-add.
2225 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
2226 */
2227int kswapd_run(int nid)
2228{
2229 pg_data_t *pgdat = NODE_DATA(nid);
2230 int ret = 0;
2231
2232 if (pgdat->kswapd)
2233 return 0;
2234
2235 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
2236 if (IS_ERR(pgdat->kswapd)) {
2237 /* failure at boot is fatal */
2238 BUG_ON(system_state == SYSTEM_BOOTING);
2239 printk("Failed to start kswapd on node %d\n",nid);
2240 ret = -1;
2241 }
2242 return ret;
2243}
2244
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245static int __init kswapd_init(void)
2246{
Yasunori Goto3218ae12006-06-27 02:53:33 -07002247 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08002248
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07002250 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07002251 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 hotcpu_notifier(cpu_callback, 0);
2253 return 0;
2254}
2255
2256module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002257
2258#ifdef CONFIG_NUMA
2259/*
2260 * Zone reclaim mode
2261 *
2262 * If non-zero call zone_reclaim when the number of free pages falls below
2263 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08002264 */
2265int zone_reclaim_mode __read_mostly;
2266
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002267#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07002268#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002269#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
2270#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
2271
Christoph Lameter9eeff232006-01-18 17:42:31 -08002272/*
Christoph Lametera92f7122006-02-01 03:05:32 -08002273 * Priority for ZONE_RECLAIM. This determines the fraction of pages
2274 * of a node considered for each zone_reclaim. 4 scans 1/16th of
2275 * a zone.
2276 */
2277#define ZONE_RECLAIM_PRIORITY 4
2278
Christoph Lameter9eeff232006-01-18 17:42:31 -08002279/*
Christoph Lameter96146342006-07-03 00:24:13 -07002280 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
2281 * occur.
2282 */
2283int sysctl_min_unmapped_ratio = 1;
2284
2285/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002286 * If the number of slab pages in a zone grows beyond this percentage then
2287 * slab reclaim needs to occur.
2288 */
2289int sysctl_min_slab_ratio = 5;
2290
2291/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08002292 * Try to free up some pages from this zone through reclaim.
2293 */
Andrew Morton179e9632006-03-22 00:08:18 -08002294static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002295{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002296 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08002297 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002298 struct task_struct *p = current;
2299 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08002300 int priority;
Andrew Morton179e9632006-03-22 00:08:18 -08002301 struct scan_control sc = {
2302 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002303 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002304 .may_swap = 1,
Andrew Morton69e05942006-03-22 00:08:19 -08002305 .swap_cluster_max = max_t(unsigned long, nr_pages,
2306 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08002307 .gfp_mask = gfp_mask,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002308 .swappiness = vm_swappiness,
Johannes Weinerbd2f6192009-03-31 15:19:38 -07002309 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08002310 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08002311 };
Christoph Lameter83e33a42006-09-25 23:31:53 -07002312 unsigned long slab_reclaimable;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002313
2314 disable_swap_token();
Christoph Lameter9eeff232006-01-18 17:42:31 -08002315 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08002316 /*
2317 * We need to be able to allocate from the reserves for RECLAIM_SWAP
2318 * and we also need to be able to write out pages for RECLAIM_WRITE
2319 * and RECLAIM_SWAP.
2320 */
2321 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002322 reclaim_state.reclaimed_slab = 0;
2323 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08002324
Christoph Lameter0ff38492006-09-25 23:31:52 -07002325 if (zone_page_state(zone, NR_FILE_PAGES) -
2326 zone_page_state(zone, NR_FILE_MAPPED) >
2327 zone->min_unmapped_pages) {
2328 /*
2329 * Free memory by calling shrink zone with increasing
2330 * priorities until we have enough memory freed.
2331 */
2332 priority = ZONE_RECLAIM_PRIORITY;
2333 do {
Martin Bligh3bb1a852006-10-28 10:38:24 -07002334 note_zone_scanning_priority(zone, priority);
Rik van Riela79311c2009-01-06 14:40:01 -08002335 shrink_zone(priority, zone, &sc);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002336 priority--;
Rik van Riela79311c2009-01-06 14:40:01 -08002337 } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002338 }
Christoph Lameterc84db232006-02-01 03:05:29 -08002339
Christoph Lameter83e33a42006-09-25 23:31:53 -07002340 slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
2341 if (slab_reclaimable > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002342 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002343 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07002344 * many pages were freed in this zone. So we take the current
2345 * number of slab pages and shake the slab until it is reduced
2346 * by the same nr_pages that we used for reclaiming unmapped
2347 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002348 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07002349 * Note that shrink_slab will free memory on all zones and may
2350 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002351 */
Christoph Lameter0ff38492006-09-25 23:31:52 -07002352 while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
Christoph Lameter83e33a42006-09-25 23:31:53 -07002353 zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
2354 slab_reclaimable - nr_pages)
Christoph Lameter0ff38492006-09-25 23:31:52 -07002355 ;
Christoph Lameter83e33a42006-09-25 23:31:53 -07002356
2357 /*
2358 * Update nr_reclaimed by the number of slab pages we
2359 * reclaimed from this zone.
2360 */
Rik van Riela79311c2009-01-06 14:40:01 -08002361 sc.nr_reclaimed += slab_reclaimable -
Christoph Lameter83e33a42006-09-25 23:31:53 -07002362 zone_page_state(zone, NR_SLAB_RECLAIMABLE);
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002363 }
2364
Christoph Lameter9eeff232006-01-18 17:42:31 -08002365 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08002366 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
Rik van Riela79311c2009-01-06 14:40:01 -08002367 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002368}
Andrew Morton179e9632006-03-22 00:08:18 -08002369
2370int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
2371{
Andrew Morton179e9632006-03-22 00:08:18 -08002372 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07002373 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002374
2375 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002376 * Zone reclaim reclaims unmapped file backed pages and
2377 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07002378 *
Christoph Lameter96146342006-07-03 00:24:13 -07002379 * A small portion of unmapped file backed pages is needed for
2380 * file I/O otherwise pages read by file I/O will be immediately
2381 * thrown out if the zone is overallocated. So we do not reclaim
2382 * if less than a specified percentage of the zone is used by
2383 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08002384 */
Christoph Lameter34aa1332006-06-30 01:55:37 -07002385 if (zone_page_state(zone, NR_FILE_PAGES) -
Christoph Lameter0ff38492006-09-25 23:31:52 -07002386 zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages
2387 && zone_page_state(zone, NR_SLAB_RECLAIMABLE)
2388 <= zone->min_slab_pages)
Christoph Lameter96146342006-07-03 00:24:13 -07002389 return 0;
Andrew Morton179e9632006-03-22 00:08:18 -08002390
David Rientjesd773ed62007-10-16 23:26:01 -07002391 if (zone_is_all_unreclaimable(zone))
2392 return 0;
2393
Andrew Morton179e9632006-03-22 00:08:18 -08002394 /*
David Rientjesd773ed62007-10-16 23:26:01 -07002395 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08002396 */
David Rientjesd773ed62007-10-16 23:26:01 -07002397 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Andrew Morton179e9632006-03-22 00:08:18 -08002398 return 0;
2399
2400 /*
2401 * Only run zone reclaim on the local zone or on zones that do not
2402 * have associated processors. This will favor the local processor
2403 * over remote processors and spread off node memory allocations
2404 * as wide as possible.
2405 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07002406 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07002407 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Andrew Morton179e9632006-03-22 00:08:18 -08002408 return 0;
David Rientjesd773ed62007-10-16 23:26:01 -07002409
2410 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
2411 return 0;
2412 ret = __zone_reclaim(zone, gfp_mask, order);
2413 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
2414
2415 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002416}
Christoph Lameter9eeff232006-01-18 17:42:31 -08002417#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002418
2419#ifdef CONFIG_UNEVICTABLE_LRU
2420/*
2421 * page_evictable - test whether a page is evictable
2422 * @page: the page to test
2423 * @vma: the VMA in which the page is or will be mapped, may be NULL
2424 *
2425 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07002426 * lists vs unevictable list. The vma argument is !NULL when called from the
2427 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002428 *
2429 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002430 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07002431 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002432 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002433 */
2434int page_evictable(struct page *page, struct vm_area_struct *vma)
2435{
2436
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002437 if (mapping_unevictable(page_mapping(page)))
2438 return 0;
2439
Nick Pigginb291f002008-10-18 20:26:44 -07002440 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
2441 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002442
2443 return 1;
2444}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002445
2446/**
2447 * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
2448 * @page: page to check evictability and move to appropriate lru list
2449 * @zone: zone page is in
2450 *
2451 * Checks a page for evictability and moves the page to the appropriate
2452 * zone lru list.
2453 *
2454 * Restrictions: zone->lru_lock must be held, page must be on LRU and must
2455 * have PageUnevictable set.
2456 */
2457static void check_move_unevictable_page(struct page *page, struct zone *zone)
2458{
2459 VM_BUG_ON(PageActive(page));
2460
2461retry:
2462 ClearPageUnevictable(page);
2463 if (page_evictable(page, NULL)) {
2464 enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002465
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002466 __dec_zone_state(zone, NR_UNEVICTABLE);
2467 list_move(&page->lru, &zone->lru[l].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08002468 mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002469 __inc_zone_state(zone, NR_INACTIVE_ANON + l);
2470 __count_vm_event(UNEVICTABLE_PGRESCUED);
2471 } else {
2472 /*
2473 * rotate unevictable list
2474 */
2475 SetPageUnevictable(page);
2476 list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08002477 mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002478 if (page_evictable(page, NULL))
2479 goto retry;
2480 }
2481}
2482
2483/**
2484 * scan_mapping_unevictable_pages - scan an address space for evictable pages
2485 * @mapping: struct address_space to scan for evictable pages
2486 *
2487 * Scan all pages in mapping. Check unevictable pages for
2488 * evictability and move them to the appropriate zone lru list.
2489 */
2490void scan_mapping_unevictable_pages(struct address_space *mapping)
2491{
2492 pgoff_t next = 0;
2493 pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
2494 PAGE_CACHE_SHIFT;
2495 struct zone *zone;
2496 struct pagevec pvec;
2497
2498 if (mapping->nrpages == 0)
2499 return;
2500
2501 pagevec_init(&pvec, 0);
2502 while (next < end &&
2503 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
2504 int i;
2505 int pg_scanned = 0;
2506
2507 zone = NULL;
2508
2509 for (i = 0; i < pagevec_count(&pvec); i++) {
2510 struct page *page = pvec.pages[i];
2511 pgoff_t page_index = page->index;
2512 struct zone *pagezone = page_zone(page);
2513
2514 pg_scanned++;
2515 if (page_index > next)
2516 next = page_index;
2517 next++;
2518
2519 if (pagezone != zone) {
2520 if (zone)
2521 spin_unlock_irq(&zone->lru_lock);
2522 zone = pagezone;
2523 spin_lock_irq(&zone->lru_lock);
2524 }
2525
2526 if (PageLRU(page) && PageUnevictable(page))
2527 check_move_unevictable_page(page, zone);
2528 }
2529 if (zone)
2530 spin_unlock_irq(&zone->lru_lock);
2531 pagevec_release(&pvec);
2532
2533 count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
2534 }
2535
2536}
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002537
2538/**
2539 * scan_zone_unevictable_pages - check unevictable list for evictable pages
2540 * @zone - zone of which to scan the unevictable list
2541 *
2542 * Scan @zone's unevictable LRU lists to check for pages that have become
2543 * evictable. Move those that have to @zone's inactive list where they
2544 * become candidates for reclaim, unless shrink_inactive_zone() decides
2545 * to reactivate them. Pages that are still unevictable are rotated
2546 * back onto @zone's unevictable list.
2547 */
2548#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
KOSAKI Motohiro14b90b22009-01-06 14:39:45 -08002549static void scan_zone_unevictable_pages(struct zone *zone)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002550{
2551 struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
2552 unsigned long scan;
2553 unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
2554
2555 while (nr_to_scan > 0) {
2556 unsigned long batch_size = min(nr_to_scan,
2557 SCAN_UNEVICTABLE_BATCH_SIZE);
2558
2559 spin_lock_irq(&zone->lru_lock);
2560 for (scan = 0; scan < batch_size; scan++) {
2561 struct page *page = lru_to_page(l_unevictable);
2562
2563 if (!trylock_page(page))
2564 continue;
2565
2566 prefetchw_prev_lru_page(page, l_unevictable, flags);
2567
2568 if (likely(PageLRU(page) && PageUnevictable(page)))
2569 check_move_unevictable_page(page, zone);
2570
2571 unlock_page(page);
2572 }
2573 spin_unlock_irq(&zone->lru_lock);
2574
2575 nr_to_scan -= batch_size;
2576 }
2577}
2578
2579
2580/**
2581 * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
2582 *
2583 * A really big hammer: scan all zones' unevictable LRU lists to check for
2584 * pages that have become evictable. Move those back to the zones'
2585 * inactive list where they become candidates for reclaim.
2586 * This occurs when, e.g., we have unswappable pages on the unevictable lists,
2587 * and we add swap to the system. As such, it runs in the context of a task
2588 * that has possibly/probably made some previously unevictable pages
2589 * evictable.
2590 */
KOSAKI Motohiroff301532009-01-06 14:39:44 -08002591static void scan_all_zones_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002592{
2593 struct zone *zone;
2594
2595 for_each_zone(zone) {
2596 scan_zone_unevictable_pages(zone);
2597 }
2598}
2599
2600/*
2601 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
2602 * all nodes' unevictable lists for evictable pages
2603 */
2604unsigned long scan_unevictable_pages;
2605
2606int scan_unevictable_handler(struct ctl_table *table, int write,
2607 struct file *file, void __user *buffer,
2608 size_t *length, loff_t *ppos)
2609{
2610 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
2611
2612 if (write && *(unsigned long *)table->data)
2613 scan_all_zones_unevictable_pages();
2614
2615 scan_unevictable_pages = 0;
2616 return 0;
2617}
2618
2619/*
2620 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
2621 * a specified node's per zone unevictable lists for evictable pages.
2622 */
2623
2624static ssize_t read_scan_unevictable_node(struct sys_device *dev,
2625 struct sysdev_attribute *attr,
2626 char *buf)
2627{
2628 return sprintf(buf, "0\n"); /* always zero; should fit... */
2629}
2630
2631static ssize_t write_scan_unevictable_node(struct sys_device *dev,
2632 struct sysdev_attribute *attr,
2633 const char *buf, size_t count)
2634{
2635 struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
2636 struct zone *zone;
2637 unsigned long res;
2638 unsigned long req = strict_strtoul(buf, 10, &res);
2639
2640 if (!req)
2641 return 1; /* zero is no-op */
2642
2643 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
2644 if (!populated_zone(zone))
2645 continue;
2646 scan_zone_unevictable_pages(zone);
2647 }
2648 return 1;
2649}
2650
2651
2652static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
2653 read_scan_unevictable_node,
2654 write_scan_unevictable_node);
2655
2656int scan_unevictable_register_node(struct node *node)
2657{
2658 return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
2659}
2660
2661void scan_unevictable_unregister_node(struct node *node)
2662{
2663 sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
2664}
2665
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002666#endif