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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090016#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/backing-dev.h>
30#include <linux/rmap.h>
31#include <linux/topology.h>
32#include <linux/cpu.h>
33#include <linux/cpuset.h>
Mel Gorman3e7d3442011-01-13 15:45:56 -080034#include <linux/compaction.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#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>
KOSAKI Motohiro929bea72011-04-14 15:22:12 -070043#include <linux/oom.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070044#include <linux/prefetch.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46#include <asm/tlbflush.h>
47#include <asm/div64.h>
48
49#include <linux/swapops.h>
50
Nick Piggin0f8053a2006-03-22 00:08:33 -080051#include "internal.h"
52
Mel Gorman33906bc2010-08-09 17:19:16 -070053#define CREATE_TRACE_POINTS
54#include <trace/events/vmscan.h>
55
Mel Gormanee64fc92011-01-13 15:45:55 -080056/*
Mel Gormanf3a310b2011-01-13 15:46:00 -080057 * reclaim_mode determines how the inactive list is shrunk
58 * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages
59 * RECLAIM_MODE_ASYNC: Do not block
60 * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
61 * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference
Mel Gormanee64fc92011-01-13 15:45:55 -080062 * page from the LRU and reclaim all pages within a
63 * naturally aligned range
Mel Gormanf3a310b2011-01-13 15:46:00 -080064 * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of
Mel Gorman3e7d3442011-01-13 15:45:56 -080065 * order-0 pages and then compact the zone
Mel Gormanee64fc92011-01-13 15:45:55 -080066 */
Mel Gormanf3a310b2011-01-13 15:46:00 -080067typedef unsigned __bitwise__ reclaim_mode_t;
68#define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u)
69#define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u)
70#define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u)
71#define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u)
72#define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u)
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -070073
Linus Torvalds1da177e2005-04-16 15:20:36 -070074struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 /* Incremented by the number of inactive pages that were scanned */
76 unsigned long nr_scanned;
77
Rik van Riela79311c2009-01-06 14:40:01 -080078 /* Number of pages freed so far during a call to shrink_zones() */
79 unsigned long nr_reclaimed;
80
KOSAKI Motohiro22fba332009-12-14 17:59:10 -080081 /* How many pages shrink_list() should reclaim */
82 unsigned long nr_to_reclaim;
83
KOSAKI Motohiro7b517552009-12-14 17:59:12 -080084 unsigned long hibernation_mode;
85
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040087 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89 int may_writepage;
90
Johannes Weinera6dc60f2009-03-31 15:19:30 -070091 /* Can mapped pages be reclaimed? */
92 int may_unmap;
Christoph Lameterf1fd1062006-01-18 17:42:30 -080093
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -070094 /* Can pages be swapped as part of reclaim? */
95 int may_swap;
96
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070097 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080098
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -070099 /*
Nikanth Karthikesan415b54e2010-08-17 15:39:09 +0530100 * Intend to reclaim enough continuous memory rather than reclaim
101 * enough amount of memory. i.e, mode for high order allocation.
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700102 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800103 reclaim_mode_t reclaim_mode;
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700104
Johannes Weinerf16015f2012-01-12 17:17:52 -0800105 /*
106 * The memory cgroup that hit its limit and as a result is the
107 * primary target of this reclaim invocation.
108 */
109 struct mem_cgroup *target_mem_cgroup;
Balbir Singh66e17072008-02-07 00:13:56 -0800110
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700111 /*
112 * Nodemask of nodes allowed by the caller. If NULL, all nodes
113 * are scanned.
114 */
115 nodemask_t *nodemask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116};
117
Johannes Weinerf16015f2012-01-12 17:17:52 -0800118struct mem_cgroup_zone {
119 struct mem_cgroup *mem_cgroup;
120 struct zone *zone;
121};
122
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
124
125#ifdef ARCH_HAS_PREFETCH
126#define prefetch_prev_lru_page(_page, _base, _field) \
127 do { \
128 if ((_page)->lru.prev != _base) { \
129 struct page *prev; \
130 \
131 prev = lru_to_page(&(_page->lru)); \
132 prefetch(&prev->_field); \
133 } \
134 } while (0)
135#else
136#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
137#endif
138
139#ifdef ARCH_HAS_PREFETCHW
140#define prefetchw_prev_lru_page(_page, _base, _field) \
141 do { \
142 if ((_page)->lru.prev != _base) { \
143 struct page *prev; \
144 \
145 prev = lru_to_page(&(_page->lru)); \
146 prefetchw(&prev->_field); \
147 } \
148 } while (0)
149#else
150#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
151#endif
152
153/*
154 * From 0 .. 100. Higher means more swappy.
155 */
156int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700157long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
159static LIST_HEAD(shrinker_list);
160static DECLARE_RWSEM(shrinker_rwsem);
161
Balbir Singh00f0b822008-03-04 14:28:39 -0800162#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800163static bool global_reclaim(struct scan_control *sc)
164{
Johannes Weinerf16015f2012-01-12 17:17:52 -0800165 return !sc->target_mem_cgroup;
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800166}
167
Johannes Weinerf16015f2012-01-12 17:17:52 -0800168static bool scanning_global_lru(struct mem_cgroup_zone *mz)
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800169{
Johannes Weinerf16015f2012-01-12 17:17:52 -0800170 return !mz->mem_cgroup;
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800171}
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800172#else
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800173static bool global_reclaim(struct scan_control *sc)
174{
175 return true;
176}
177
Johannes Weinerf16015f2012-01-12 17:17:52 -0800178static bool scanning_global_lru(struct mem_cgroup_zone *mz)
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800179{
180 return true;
181}
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800182#endif
183
Johannes Weinerf16015f2012-01-12 17:17:52 -0800184static struct zone_reclaim_stat *get_reclaim_stat(struct mem_cgroup_zone *mz)
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800185{
Johannes Weinerf16015f2012-01-12 17:17:52 -0800186 if (!scanning_global_lru(mz))
187 return mem_cgroup_get_reclaim_stat(mz->mem_cgroup, mz->zone);
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800188
Johannes Weinerf16015f2012-01-12 17:17:52 -0800189 return &mz->zone->reclaim_stat;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800190}
191
Johannes Weinerf16015f2012-01-12 17:17:52 -0800192static unsigned long zone_nr_lru_pages(struct mem_cgroup_zone *mz,
193 enum lru_list lru)
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800194{
Johannes Weinerf16015f2012-01-12 17:17:52 -0800195 if (!scanning_global_lru(mz))
196 return mem_cgroup_zone_nr_lru_pages(mz->mem_cgroup,
197 zone_to_nid(mz->zone),
198 zone_idx(mz->zone),
199 BIT(lru));
KOSAKI Motohiroa3d8e052009-01-07 18:08:19 -0800200
Johannes Weinerf16015f2012-01-12 17:17:52 -0800201 return zone_page_state(mz->zone, NR_LRU_BASE + lru);
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800202}
203
204
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205/*
206 * Add a shrinker callback to be called from the vm
207 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700208void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209{
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800210 atomic_long_set(&shrinker->nr_in_batch, 0);
Rusty Russell8e1f9362007-07-17 04:03:17 -0700211 down_write(&shrinker_rwsem);
212 list_add_tail(&shrinker->list, &shrinker_list);
213 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700215EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
217/*
218 * Remove one
219 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700220void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221{
222 down_write(&shrinker_rwsem);
223 list_del(&shrinker->list);
224 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700226EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
Ying Han1495f232011-05-24 17:12:27 -0700228static inline int do_shrinker_shrink(struct shrinker *shrinker,
229 struct shrink_control *sc,
230 unsigned long nr_to_scan)
231{
232 sc->nr_to_scan = nr_to_scan;
233 return (*shrinker->shrink)(shrinker, sc);
234}
235
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236#define SHRINK_BATCH 128
237/*
238 * Call the shrink functions to age shrinkable caches
239 *
240 * Here we assume it costs one seek to replace a lru page and that it also
241 * takes a seek to recreate a cache object. With this in mind we age equal
242 * percentages of the lru and ageable caches. This should balance the seeks
243 * generated by these structures.
244 *
Simon Arlott183ff222007-10-20 01:27:18 +0200245 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 * slab to avoid swapping.
247 *
248 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
249 *
250 * `lru_pages' represents the number of on-LRU pages in all the zones which
251 * are eligible for the caller's allocation attempt. It is used for balancing
252 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700253 *
254 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 */
Ying Hana09ed5e2011-05-24 17:12:26 -0700256unsigned long shrink_slab(struct shrink_control *shrink,
Ying Han1495f232011-05-24 17:12:27 -0700257 unsigned long nr_pages_scanned,
Ying Hana09ed5e2011-05-24 17:12:26 -0700258 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259{
260 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800261 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262
Ying Han1495f232011-05-24 17:12:27 -0700263 if (nr_pages_scanned == 0)
264 nr_pages_scanned = SWAP_CLUSTER_MAX;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
Minchan Kimf06590b2011-05-24 17:11:11 -0700266 if (!down_read_trylock(&shrinker_rwsem)) {
267 /* Assume we'll be able to shrink next time */
268 ret = 1;
269 goto out;
270 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
272 list_for_each_entry(shrinker, &shrinker_list, list) {
273 unsigned long long delta;
Konstantin Khlebnikov635697c2011-12-08 14:33:51 -0800274 long total_scan;
275 long max_pass;
Dave Chinner09576072011-07-08 14:14:34 +1000276 int shrink_ret = 0;
Dave Chinneracf92b42011-07-08 14:14:35 +1000277 long nr;
278 long new_nr;
Dave Chinnere9299f52011-07-08 14:14:37 +1000279 long batch_size = shrinker->batch ? shrinker->batch
280 : SHRINK_BATCH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
Konstantin Khlebnikov635697c2011-12-08 14:33:51 -0800282 max_pass = do_shrinker_shrink(shrinker, shrink, 0);
283 if (max_pass <= 0)
284 continue;
285
Dave Chinneracf92b42011-07-08 14:14:35 +1000286 /*
287 * copy the current shrinker scan count into a local variable
288 * and zero it so that other concurrent shrinker invocations
289 * don't also do this scanning work.
290 */
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800291 nr = atomic_long_xchg(&shrinker->nr_in_batch, 0);
Dave Chinneracf92b42011-07-08 14:14:35 +1000292
293 total_scan = nr;
Ying Han1495f232011-05-24 17:12:27 -0700294 delta = (4 * nr_pages_scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800295 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 do_div(delta, lru_pages + 1);
Dave Chinneracf92b42011-07-08 14:14:35 +1000297 total_scan += delta;
298 if (total_scan < 0) {
David Rientjes88c3bd72009-03-31 15:23:29 -0700299 printk(KERN_ERR "shrink_slab: %pF negative objects to "
300 "delete nr=%ld\n",
Dave Chinneracf92b42011-07-08 14:14:35 +1000301 shrinker->shrink, total_scan);
302 total_scan = max_pass;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800303 }
304
305 /*
Dave Chinner3567b592011-07-08 14:14:36 +1000306 * We need to avoid excessive windup on filesystem shrinkers
307 * due to large numbers of GFP_NOFS allocations causing the
308 * shrinkers to return -1 all the time. This results in a large
309 * nr being built up so when a shrink that can do some work
310 * comes along it empties the entire cache due to nr >>>
311 * max_pass. This is bad for sustaining a working set in
312 * memory.
313 *
314 * Hence only allow the shrinker to scan the entire cache when
315 * a large delta change is calculated directly.
316 */
317 if (delta < max_pass / 4)
318 total_scan = min(total_scan, max_pass / 2);
319
320 /*
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800321 * Avoid risking looping forever due to too large nr value:
322 * never try to free more than twice the estimate number of
323 * freeable entries.
324 */
Dave Chinneracf92b42011-07-08 14:14:35 +1000325 if (total_scan > max_pass * 2)
326 total_scan = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327
Dave Chinneracf92b42011-07-08 14:14:35 +1000328 trace_mm_shrink_slab_start(shrinker, shrink, nr,
Dave Chinner09576072011-07-08 14:14:34 +1000329 nr_pages_scanned, lru_pages,
330 max_pass, delta, total_scan);
331
Dave Chinnere9299f52011-07-08 14:14:37 +1000332 while (total_scan >= batch_size) {
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700333 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
Ying Han1495f232011-05-24 17:12:27 -0700335 nr_before = do_shrinker_shrink(shrinker, shrink, 0);
336 shrink_ret = do_shrinker_shrink(shrinker, shrink,
Dave Chinnere9299f52011-07-08 14:14:37 +1000337 batch_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 if (shrink_ret == -1)
339 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700340 if (shrink_ret < nr_before)
341 ret += nr_before - shrink_ret;
Dave Chinnere9299f52011-07-08 14:14:37 +1000342 count_vm_events(SLABS_SCANNED, batch_size);
343 total_scan -= batch_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345 cond_resched();
346 }
347
Dave Chinneracf92b42011-07-08 14:14:35 +1000348 /*
349 * move the unused scan count back into the shrinker in a
350 * manner that handles concurrent updates. If we exhausted the
351 * scan, there is no need to do an update.
352 */
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800353 if (total_scan > 0)
354 new_nr = atomic_long_add_return(total_scan,
355 &shrinker->nr_in_batch);
356 else
357 new_nr = atomic_long_read(&shrinker->nr_in_batch);
Dave Chinneracf92b42011-07-08 14:14:35 +1000358
359 trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 }
361 up_read(&shrinker_rwsem);
Minchan Kimf06590b2011-05-24 17:11:11 -0700362out:
363 cond_resched();
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700364 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365}
366
Mel Gormanf3a310b2011-01-13 15:46:00 -0800367static void set_reclaim_mode(int priority, struct scan_control *sc,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700368 bool sync)
369{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800370 reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700371
372 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800373 * Initially assume we are entering either lumpy reclaim or
374 * reclaim/compaction.Depending on the order, we will either set the
375 * sync mode or just reclaim order-0 pages later.
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700376 */
Mel Gorman3e7d3442011-01-13 15:45:56 -0800377 if (COMPACTION_BUILD)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800378 sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
Mel Gorman3e7d3442011-01-13 15:45:56 -0800379 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800380 sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700381
382 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800383 * Avoid using lumpy reclaim or reclaim/compaction if possible by
384 * restricting when its set to either costly allocations or when
385 * under memory pressure
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700386 */
387 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800388 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700389 else if (sc->order && priority < DEF_PRIORITY - 2)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800390 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700391 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800392 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700393}
394
Mel Gormanf3a310b2011-01-13 15:46:00 -0800395static void reset_reclaim_mode(struct scan_control *sc)
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700396{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800397 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700398}
399
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400static inline int is_page_cache_freeable(struct page *page)
401{
Johannes Weinerceddc3a2009-09-21 17:03:00 -0700402 /*
403 * A freeable page cache page is referenced only by the caller
404 * that isolated the page, the page cache radix tree and
405 * optional buffer heads at page->private.
406 */
Johannes Weineredcf4742009-09-21 17:02:59 -0700407 return page_count(page) - page_has_private(page) == 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408}
409
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700410static int may_write_to_queue(struct backing_dev_info *bdi,
411 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412{
Christoph Lameter930d9152006-01-08 01:00:47 -0800413 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 return 1;
415 if (!bdi_write_congested(bdi))
416 return 1;
417 if (bdi == current->backing_dev_info)
418 return 1;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700419
420 /* lumpy reclaim for hugepage often need a lot of write */
421 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
422 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 return 0;
424}
425
426/*
427 * We detected a synchronous write error writing a page out. Probably
428 * -ENOSPC. We need to propagate that into the address_space for a subsequent
429 * fsync(), msync() or close().
430 *
431 * The tricky part is that after writepage we cannot touch the mapping: nothing
432 * prevents it from being freed up. But we have a ref on the page and once
433 * that page is locked, the mapping is pinned.
434 *
435 * We're allowed to run sleeping lock_page() here because we know the caller has
436 * __GFP_FS.
437 */
438static void handle_write_error(struct address_space *mapping,
439 struct page *page, int error)
440{
Jens Axboe7eaceac2011-03-10 08:52:07 +0100441 lock_page(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700442 if (page_mapping(page) == mapping)
443 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 unlock_page(page);
445}
446
Christoph Lameter04e62a22006-06-23 02:03:38 -0700447/* possible outcome of pageout() */
448typedef enum {
449 /* failed to write page out, page is locked */
450 PAGE_KEEP,
451 /* move page to the active list, page is locked */
452 PAGE_ACTIVATE,
453 /* page has been sent to the disk successfully, page is unlocked */
454 PAGE_SUCCESS,
455 /* page is clean and locked */
456 PAGE_CLEAN,
457} pageout_t;
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459/*
Andrew Morton1742f192006-03-22 00:08:21 -0800460 * pageout is called by shrink_page_list() for each dirty page.
461 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700463static pageout_t pageout(struct page *page, struct address_space *mapping,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700464 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465{
466 /*
467 * If the page is dirty, only perform writeback if that write
468 * will be non-blocking. To prevent this allocation from being
469 * stalled by pagecache activity. But note that there may be
470 * stalls if we need to run get_block(). We could test
471 * PagePrivate for that.
472 *
Vincent Li6aceb532009-12-14 17:58:49 -0800473 * If this process is currently in __generic_file_aio_write() against
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 * this page's queue, we can perform writeback even if that
475 * will block.
476 *
477 * If the page is swapcache, write it back even if that would
478 * block, for some throttling. This happens by accident, because
479 * swap_backing_dev_info is bust: it doesn't reflect the
480 * congestion state of the swapdevs. Easy to fix, if needed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 */
482 if (!is_page_cache_freeable(page))
483 return PAGE_KEEP;
484 if (!mapping) {
485 /*
486 * Some data journaling orphaned pages can have
487 * page->mapping == NULL while being dirty with clean buffers.
488 */
David Howells266cf652009-04-03 16:42:36 +0100489 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 if (try_to_free_buffers(page)) {
491 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700492 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 return PAGE_CLEAN;
494 }
495 }
496 return PAGE_KEEP;
497 }
498 if (mapping->a_ops->writepage == NULL)
499 return PAGE_ACTIVATE;
Mel Gorman0e093d992010-10-26 14:21:45 -0700500 if (!may_write_to_queue(mapping->backing_dev_info, sc))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 return PAGE_KEEP;
502
503 if (clear_page_dirty_for_io(page)) {
504 int res;
505 struct writeback_control wbc = {
506 .sync_mode = WB_SYNC_NONE,
507 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700508 .range_start = 0,
509 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 .for_reclaim = 1,
511 };
512
513 SetPageReclaim(page);
514 res = mapping->a_ops->writepage(page, &wbc);
515 if (res < 0)
516 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800517 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 ClearPageReclaim(page);
519 return PAGE_ACTIVATE;
520 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700521
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 if (!PageWriteback(page)) {
523 /* synchronous write or broken a_ops? */
524 ClearPageReclaim(page);
525 }
Mel Gorman755f0222010-08-09 17:19:18 -0700526 trace_mm_vmscan_writepage(page,
Mel Gormanf3a310b2011-01-13 15:46:00 -0800527 trace_reclaim_flags(page, sc->reclaim_mode));
Andrew Mortone129b5c2006-09-27 01:50:00 -0700528 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 return PAGE_SUCCESS;
530 }
531
532 return PAGE_CLEAN;
533}
534
Andrew Mortona649fd92006-10-17 00:09:36 -0700535/*
Nick Piggine2867812008-07-25 19:45:30 -0700536 * Same as remove_mapping, but if the page is removed from the mapping, it
537 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700538 */
Nick Piggine2867812008-07-25 19:45:30 -0700539static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800540{
Nick Piggin28e4d962006-09-25 23:31:23 -0700541 BUG_ON(!PageLocked(page));
542 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800543
Nick Piggin19fd6232008-07-25 19:45:32 -0700544 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800545 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700546 * The non racy check for a busy page.
547 *
548 * Must be careful with the order of the tests. When someone has
549 * a ref to the page, it may be possible that they dirty it then
550 * drop the reference. So if PageDirty is tested before page_count
551 * here, then the following race may occur:
552 *
553 * get_user_pages(&page);
554 * [user mapping goes away]
555 * write_to(page);
556 * !PageDirty(page) [good]
557 * SetPageDirty(page);
558 * put_page(page);
559 * !page_count(page) [good, discard it]
560 *
561 * [oops, our write_to data is lost]
562 *
563 * Reversing the order of the tests ensures such a situation cannot
564 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
565 * load is not satisfied before that of page->_count.
566 *
567 * Note that if SetPageDirty is always performed via set_page_dirty,
568 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800569 */
Nick Piggine2867812008-07-25 19:45:30 -0700570 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800571 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700572 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
573 if (unlikely(PageDirty(page))) {
574 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800575 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700576 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800577
578 if (PageSwapCache(page)) {
579 swp_entry_t swap = { .val = page_private(page) };
580 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700581 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -0700582 swapcache_free(swap, page);
Nick Piggine2867812008-07-25 19:45:30 -0700583 } else {
Linus Torvalds6072d132010-12-01 13:35:19 -0500584 void (*freepage)(struct page *);
585
586 freepage = mapping->a_ops->freepage;
587
Minchan Kime64a7822011-03-22 16:32:44 -0700588 __delete_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700589 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700590 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500591
592 if (freepage != NULL)
593 freepage(page);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800594 }
595
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800596 return 1;
597
598cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700599 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800600 return 0;
601}
602
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603/*
Nick Piggine2867812008-07-25 19:45:30 -0700604 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
605 * someone else has a ref on the page, abort and return 0. If it was
606 * successfully detached, return 1. Assumes the caller has a single ref on
607 * this page.
608 */
609int remove_mapping(struct address_space *mapping, struct page *page)
610{
611 if (__remove_mapping(mapping, page)) {
612 /*
613 * Unfreezing the refcount with 1 rather than 2 effectively
614 * drops the pagecache ref for us without requiring another
615 * atomic operation.
616 */
617 page_unfreeze_refs(page, 1);
618 return 1;
619 }
620 return 0;
621}
622
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700623/**
624 * putback_lru_page - put previously isolated page onto appropriate LRU list
625 * @page: page to be put back to appropriate lru list
626 *
627 * Add previously isolated @page to appropriate LRU list.
628 * Page may still be unevictable for other reasons.
629 *
630 * lru_lock must not be held, interrupts must be enabled.
631 */
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700632void putback_lru_page(struct page *page)
633{
634 int lru;
635 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700636 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700637
638 VM_BUG_ON(PageLRU(page));
639
640redo:
641 ClearPageUnevictable(page);
642
643 if (page_evictable(page, NULL)) {
644 /*
645 * For evictable pages, we can use the cache.
646 * In event of a race, worst case is we end up with an
647 * unevictable page on [in]active list.
648 * We know how to handle that.
649 */
Johannes Weiner401a8e12009-09-21 17:02:58 -0700650 lru = active + page_lru_base_type(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700651 lru_cache_add_lru(page, lru);
652 } else {
653 /*
654 * Put unevictable pages directly on zone's unevictable
655 * list.
656 */
657 lru = LRU_UNEVICTABLE;
658 add_page_to_unevictable_list(page);
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700659 /*
Minchan Kim21ee9f32011-10-31 17:09:28 -0700660 * When racing with an mlock or AS_UNEVICTABLE clearing
661 * (page is unlocked) make sure that if the other thread
662 * does not observe our setting of PG_lru and fails
Hugh Dickins24513262012-01-20 14:34:21 -0800663 * isolation/check_move_unevictable_pages,
Minchan Kim21ee9f32011-10-31 17:09:28 -0700664 * we see PG_mlocked/AS_UNEVICTABLE cleared below and move
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700665 * the page back to the evictable list.
666 *
Minchan Kim21ee9f32011-10-31 17:09:28 -0700667 * The other side is TestClearPageMlocked() or shmem_lock().
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700668 */
669 smp_mb();
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700670 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700671
672 /*
673 * page's status can change while we move it among lru. If an evictable
674 * page is on unevictable list, it never be freed. To avoid that,
675 * check after we added it to the list, again.
676 */
677 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
678 if (!isolate_lru_page(page)) {
679 put_page(page);
680 goto redo;
681 }
682 /* This means someone else dropped this page from LRU
683 * So, it will be freed or putback to LRU again. There is
684 * nothing to do here.
685 */
686 }
687
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700688 if (was_unevictable && lru != LRU_UNEVICTABLE)
689 count_vm_event(UNEVICTABLE_PGRESCUED);
690 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
691 count_vm_event(UNEVICTABLE_PGCULLED);
692
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700693 put_page(page); /* drop ref from isolate */
694}
695
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800696enum page_references {
697 PAGEREF_RECLAIM,
698 PAGEREF_RECLAIM_CLEAN,
Johannes Weiner64574742010-03-05 13:42:22 -0800699 PAGEREF_KEEP,
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800700 PAGEREF_ACTIVATE,
701};
702
703static enum page_references page_check_references(struct page *page,
Johannes Weinerf16015f2012-01-12 17:17:52 -0800704 struct mem_cgroup_zone *mz,
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800705 struct scan_control *sc)
706{
Johannes Weiner64574742010-03-05 13:42:22 -0800707 int referenced_ptes, referenced_page;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800708 unsigned long vm_flags;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800709
Johannes Weinerf16015f2012-01-12 17:17:52 -0800710 referenced_ptes = page_referenced(page, 1, mz->mem_cgroup, &vm_flags);
Johannes Weiner64574742010-03-05 13:42:22 -0800711 referenced_page = TestClearPageReferenced(page);
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800712
713 /* Lumpy reclaim - ignore references */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800714 if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800715 return PAGEREF_RECLAIM;
716
717 /*
718 * Mlock lost the isolation race with us. Let try_to_unmap()
719 * move the page to the unevictable list.
720 */
721 if (vm_flags & VM_LOCKED)
722 return PAGEREF_RECLAIM;
723
Johannes Weiner64574742010-03-05 13:42:22 -0800724 if (referenced_ptes) {
725 if (PageAnon(page))
726 return PAGEREF_ACTIVATE;
727 /*
728 * All mapped pages start out with page table
729 * references from the instantiating fault, so we need
730 * to look twice if a mapped file page is used more
731 * than once.
732 *
733 * Mark it and spare it for another trip around the
734 * inactive list. Another page table reference will
735 * lead to its activation.
736 *
737 * Note: the mark is set for activated pages as well
738 * so that recently deactivated but used pages are
739 * quickly recovered.
740 */
741 SetPageReferenced(page);
742
Konstantin Khlebnikov34dbc672012-01-10 15:06:59 -0800743 if (referenced_page || referenced_ptes > 1)
Johannes Weiner64574742010-03-05 13:42:22 -0800744 return PAGEREF_ACTIVATE;
745
Konstantin Khlebnikovc909e992012-01-10 15:07:03 -0800746 /*
747 * Activate file-backed executable pages after first usage.
748 */
749 if (vm_flags & VM_EXEC)
750 return PAGEREF_ACTIVATE;
751
Johannes Weiner64574742010-03-05 13:42:22 -0800752 return PAGEREF_KEEP;
753 }
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800754
755 /* Reclaim if clean, defer dirty pages to writeback */
KOSAKI Motohiro2e302442010-10-26 14:21:46 -0700756 if (referenced_page && !PageSwapBacked(page))
Johannes Weiner64574742010-03-05 13:42:22 -0800757 return PAGEREF_RECLAIM_CLEAN;
758
759 return PAGEREF_RECLAIM;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800760}
761
Nick Piggine2867812008-07-25 19:45:30 -0700762/*
Andrew Morton1742f192006-03-22 00:08:21 -0800763 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 */
Andrew Morton1742f192006-03-22 00:08:21 -0800765static unsigned long shrink_page_list(struct list_head *page_list,
Johannes Weinerf16015f2012-01-12 17:17:52 -0800766 struct mem_cgroup_zone *mz,
Mel Gormanf84f6e22011-10-31 17:07:51 -0700767 struct scan_control *sc,
Mel Gorman92df3a72011-10-31 17:07:56 -0700768 int priority,
769 unsigned long *ret_nr_dirty,
770 unsigned long *ret_nr_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771{
772 LIST_HEAD(ret_pages);
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700773 LIST_HEAD(free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 int pgactivate = 0;
Mel Gorman0e093d992010-10-26 14:21:45 -0700775 unsigned long nr_dirty = 0;
776 unsigned long nr_congested = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800777 unsigned long nr_reclaimed = 0;
Mel Gorman92df3a72011-10-31 17:07:56 -0700778 unsigned long nr_writeback = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
780 cond_resched();
781
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 while (!list_empty(page_list)) {
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800783 enum page_references references;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 struct address_space *mapping;
785 struct page *page;
786 int may_enter_fs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787
788 cond_resched();
789
790 page = lru_to_page(page_list);
791 list_del(&page->lru);
792
Nick Piggin529ae9a2008-08-02 12:01:03 +0200793 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 goto keep;
795
Nick Piggin725d7042006-09-25 23:30:55 -0700796 VM_BUG_ON(PageActive(page));
Johannes Weinerf16015f2012-01-12 17:17:52 -0800797 VM_BUG_ON(page_zone(page) != mz->zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
799 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800800
Nick Pigginb291f002008-10-18 20:26:44 -0700801 if (unlikely(!page_evictable(page, NULL)))
802 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700803
Johannes Weinera6dc60f2009-03-31 15:19:30 -0700804 if (!sc->may_unmap && page_mapped(page))
Christoph Lameter80e43422006-02-11 17:55:53 -0800805 goto keep_locked;
806
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 /* Double the slab pressure for mapped and swapcache pages */
808 if (page_mapped(page) || PageSwapCache(page))
809 sc->nr_scanned++;
810
Andy Whitcroftc661b072007-08-22 14:01:26 -0700811 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
812 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
813
814 if (PageWriteback(page)) {
Mel Gorman92df3a72011-10-31 17:07:56 -0700815 nr_writeback++;
Andy Whitcroftc661b072007-08-22 14:01:26 -0700816 /*
Mel Gormana18bba02011-10-31 17:07:42 -0700817 * Synchronous reclaim cannot queue pages for
818 * writeback due to the possibility of stack overflow
819 * but if it encounters a page under writeback, wait
820 * for the IO to complete.
Andy Whitcroftc661b072007-08-22 14:01:26 -0700821 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800822 if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700823 may_enter_fs)
Andy Whitcroftc661b072007-08-22 14:01:26 -0700824 wait_on_page_writeback(page);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700825 else {
826 unlock_page(page);
827 goto keep_lumpy;
828 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700829 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830
Johannes Weinerf16015f2012-01-12 17:17:52 -0800831 references = page_check_references(page, mz, sc);
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800832 switch (references) {
833 case PAGEREF_ACTIVATE:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 goto activate_locked;
Johannes Weiner64574742010-03-05 13:42:22 -0800835 case PAGEREF_KEEP:
836 goto keep_locked;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800837 case PAGEREF_RECLAIM:
838 case PAGEREF_RECLAIM_CLEAN:
839 ; /* try to reclaim the page below */
840 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 /*
843 * Anonymous process memory has backing store?
844 * Try to allocate it some swap space here.
845 */
Nick Pigginb291f002008-10-18 20:26:44 -0700846 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800847 if (!(sc->gfp_mask & __GFP_IO))
848 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800849 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800851 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700852 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853
854 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
856 /*
857 * The page is mapped into the page tables of one or more
858 * processes. Try to unmap it here.
859 */
860 if (page_mapped(page) && mapping) {
Andi Kleen14fa31b2009-09-16 11:50:10 +0200861 switch (try_to_unmap(page, TTU_UNMAP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 case SWAP_FAIL:
863 goto activate_locked;
864 case SWAP_AGAIN:
865 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700866 case SWAP_MLOCK:
867 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 case SWAP_SUCCESS:
869 ; /* try to free the page below */
870 }
871 }
872
873 if (PageDirty(page)) {
Mel Gorman0e093d992010-10-26 14:21:45 -0700874 nr_dirty++;
875
Mel Gormanee728862011-10-31 17:07:38 -0700876 /*
877 * Only kswapd can writeback filesystem pages to
Mel Gormanf84f6e22011-10-31 17:07:51 -0700878 * avoid risk of stack overflow but do not writeback
879 * unless under significant pressure.
Mel Gormanee728862011-10-31 17:07:38 -0700880 */
Mel Gormanf84f6e22011-10-31 17:07:51 -0700881 if (page_is_file_cache(page) &&
882 (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
Mel Gorman49ea7eb2011-10-31 17:07:59 -0700883 /*
884 * Immediately reclaim when written back.
885 * Similar in principal to deactivate_page()
886 * except we already have the page isolated
887 * and know it's dirty
888 */
889 inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE);
890 SetPageReclaim(page);
891
Mel Gormanee728862011-10-31 17:07:38 -0700892 goto keep_locked;
893 }
894
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800895 if (references == PAGEREF_RECLAIM_CLEAN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700897 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800899 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 goto keep_locked;
901
902 /* Page is dirty, try to write it out here */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700903 switch (pageout(page, mapping, sc)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 case PAGE_KEEP:
Mel Gorman0e093d992010-10-26 14:21:45 -0700905 nr_congested++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 goto keep_locked;
907 case PAGE_ACTIVATE:
908 goto activate_locked;
909 case PAGE_SUCCESS:
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700910 if (PageWriteback(page))
911 goto keep_lumpy;
912 if (PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 goto keep;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700914
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 /*
916 * A synchronous write - probably a ramdisk. Go
917 * ahead and try to reclaim the page.
918 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200919 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 goto keep;
921 if (PageDirty(page) || PageWriteback(page))
922 goto keep_locked;
923 mapping = page_mapping(page);
924 case PAGE_CLEAN:
925 ; /* try to free the page below */
926 }
927 }
928
929 /*
930 * If the page has buffers, try to free the buffer mappings
931 * associated with this page. If we succeed we try to free
932 * the page as well.
933 *
934 * We do this even if the page is PageDirty().
935 * try_to_release_page() does not perform I/O, but it is
936 * possible for a page to have PageDirty set, but it is actually
937 * clean (all its buffers are clean). This happens if the
938 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700939 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 * try_to_release_page() will discover that cleanness and will
941 * drop the buffers and mark the page clean - it can be freed.
942 *
943 * Rarely, pages can have buffers and no ->mapping. These are
944 * the pages which were not successfully invalidated in
945 * truncate_complete_page(). We try to drop those buffers here
946 * and if that worked, and the page is no longer mapped into
947 * process address space (page_count == 1) it can be freed.
948 * Otherwise, leave the page on the LRU so it is swappable.
949 */
David Howells266cf652009-04-03 16:42:36 +0100950 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 if (!try_to_release_page(page, sc->gfp_mask))
952 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700953 if (!mapping && page_count(page) == 1) {
954 unlock_page(page);
955 if (put_page_testzero(page))
956 goto free_it;
957 else {
958 /*
959 * rare race with speculative reference.
960 * the speculative reference will free
961 * this page shortly, so we may
962 * increment nr_reclaimed here (and
963 * leave it off the LRU).
964 */
965 nr_reclaimed++;
966 continue;
967 }
968 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 }
970
Nick Piggine2867812008-07-25 19:45:30 -0700971 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800972 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973
Nick Piggina978d6f2008-10-18 20:26:58 -0700974 /*
975 * At this point, we have no other references and there is
976 * no way to pick any more up (removed from LRU, removed
977 * from pagecache). Can use non-atomic bitops now (and
978 * we obviously don't have to worry about waking up a process
979 * waiting on the page lock, because there are no references.
980 */
981 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700982free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800983 nr_reclaimed++;
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700984
985 /*
986 * Is there need to periodically free_page_list? It would
987 * appear not as the counts should be low
988 */
989 list_add(&page->lru, &free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 continue;
991
Nick Pigginb291f002008-10-18 20:26:44 -0700992cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800993 if (PageSwapCache(page))
994 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700995 unlock_page(page);
996 putback_lru_page(page);
Mel Gormanf3a310b2011-01-13 15:46:00 -0800997 reset_reclaim_mode(sc);
Nick Pigginb291f002008-10-18 20:26:44 -0700998 continue;
999
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -07001001 /* Not a candidate for swapping, so reclaim swap space. */
1002 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -08001003 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001004 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 SetPageActive(page);
1006 pgactivate++;
1007keep_locked:
1008 unlock_page(page);
1009keep:
Mel Gormanf3a310b2011-01-13 15:46:00 -08001010 reset_reclaim_mode(sc);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -07001011keep_lumpy:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -07001013 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 }
Mel Gormanabe4c3b2010-08-09 17:19:31 -07001015
Mel Gorman0e093d992010-10-26 14:21:45 -07001016 /*
1017 * Tag a zone as congested if all the dirty pages encountered were
1018 * backed by a congested BDI. In this case, reclaimers should just
1019 * back off and wait for congestion to clear because further reclaim
1020 * will encounter the same problem
1021 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001022 if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))
Johannes Weinerf16015f2012-01-12 17:17:52 -08001023 zone_set_flag(mz->zone, ZONE_CONGESTED);
Mel Gorman0e093d992010-10-26 14:21:45 -07001024
Konstantin Khlebnikovcc598502012-01-10 15:07:04 -08001025 free_hot_cold_page_list(&free_pages, 1);
Mel Gormanabe4c3b2010-08-09 17:19:31 -07001026
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 list_splice(&ret_pages, page_list);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001028 count_vm_events(PGACTIVATE, pgactivate);
Mel Gorman92df3a72011-10-31 17:07:56 -07001029 *ret_nr_dirty += nr_dirty;
1030 *ret_nr_writeback += nr_writeback;
Andrew Morton05ff5132006-03-22 00:08:20 -08001031 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032}
1033
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001034/*
1035 * Attempt to remove the specified page from its LRU. Only take this page
1036 * if it is of the appropriate PageActive status. Pages which are being
1037 * freed elsewhere are also ignored.
1038 *
1039 * page: page to consider
1040 * mode: one of the LRU isolation modes defined above
1041 *
1042 * returns 0 on success, -ve errno on failure.
1043 */
Minchan Kim4356f212011-10-31 17:06:47 -07001044int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001045{
Minchan Kim4356f212011-10-31 17:06:47 -07001046 bool all_lru_mode;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001047 int ret = -EINVAL;
1048
1049 /* Only take pages on the LRU. */
1050 if (!PageLRU(page))
1051 return ret;
1052
Minchan Kim4356f212011-10-31 17:06:47 -07001053 all_lru_mode = (mode & (ISOLATE_ACTIVE|ISOLATE_INACTIVE)) ==
1054 (ISOLATE_ACTIVE|ISOLATE_INACTIVE);
1055
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001056 /*
1057 * When checking the active state, we need to be sure we are
1058 * dealing with comparible boolean values. Take the logical not
1059 * of each.
1060 */
Minchan Kim4356f212011-10-31 17:06:47 -07001061 if (!all_lru_mode && !PageActive(page) != !(mode & ISOLATE_ACTIVE))
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001062 return ret;
1063
Minchan Kim4356f212011-10-31 17:06:47 -07001064 if (!all_lru_mode && !!page_is_file_cache(page) != file)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001065 return ret;
1066
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001067 /*
1068 * When this function is being called for lumpy reclaim, we
1069 * initially look into all LRU pages, active, inactive and
1070 * unevictable; only give shrink_page_list evictable pages.
1071 */
1072 if (PageUnevictable(page))
1073 return ret;
1074
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001075 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08001076
Mel Gormanc8244932012-01-12 17:19:38 -08001077 /*
1078 * To minimise LRU disruption, the caller can indicate that it only
1079 * wants to isolate pages it will be able to operate on without
1080 * blocking - clean pages for the most part.
1081 *
1082 * ISOLATE_CLEAN means that only clean pages should be isolated. This
1083 * is used by reclaim when it is cannot write to backing storage
1084 *
1085 * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages
1086 * that it is possible to migrate without blocking
1087 */
1088 if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {
1089 /* All the caller can do on PageWriteback is block */
1090 if (PageWriteback(page))
1091 return ret;
1092
1093 if (PageDirty(page)) {
1094 struct address_space *mapping;
1095
1096 /* ISOLATE_CLEAN means only clean pages */
1097 if (mode & ISOLATE_CLEAN)
1098 return ret;
1099
1100 /*
1101 * Only pages without mappings or that have a
1102 * ->migratepage callback are possible to migrate
1103 * without blocking
1104 */
1105 mapping = page_mapping(page);
1106 if (mapping && !mapping->a_ops->migratepage)
1107 return ret;
1108 }
1109 }
Minchan Kim39deaf82011-10-31 17:06:51 -07001110
Minchan Kimf80c0672011-10-31 17:06:55 -07001111 if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
1112 return ret;
1113
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001114 if (likely(get_page_unless_zero(page))) {
1115 /*
1116 * Be careful not to clear PageLRU until after we're
1117 * sure the page is not being freed elsewhere -- the
1118 * page release code relies on it.
1119 */
1120 ClearPageLRU(page);
1121 ret = 0;
1122 }
1123
1124 return ret;
1125}
1126
Christoph Lameter49d2e9c2006-01-08 01:00:48 -08001127/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 * zone->lru_lock is heavily contended. Some of the functions that
1129 * shrink the lists perform better by taking out a batch of pages
1130 * and working on them outside the LRU lock.
1131 *
1132 * For pagecache intensive workloads, this function is the hottest
1133 * spot in the kernel (apart from copy_*_user functions).
1134 *
1135 * Appropriate locks must be held before calling this function.
1136 *
1137 * @nr_to_scan: The number of pages to look through on the list.
Hugh Dickinsf6260122012-01-12 17:20:06 -08001138 * @mz: The mem_cgroup_zone to pull pages from.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 * @dst: The temp list to put pages on to.
Hugh Dickinsf6260122012-01-12 17:20:06 -08001140 * @nr_scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001141 * @order: The caller's attempted allocation order
1142 * @mode: One of the LRU isolation modes
Hugh Dickinsf6260122012-01-12 17:20:06 -08001143 * @active: True [1] if isolating active pages
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001144 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 *
1146 * returns how many pages were moved onto *@dst.
1147 */
Andrew Morton69e05942006-03-22 00:08:19 -08001148static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
Hugh Dickinsf6260122012-01-12 17:20:06 -08001149 struct mem_cgroup_zone *mz, struct list_head *dst,
1150 unsigned long *nr_scanned, int order, isolate_mode_t mode,
1151 int active, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152{
Hugh Dickinsf6260122012-01-12 17:20:06 -08001153 struct lruvec *lruvec;
1154 struct list_head *src;
Andrew Morton69e05942006-03-22 00:08:19 -08001155 unsigned long nr_taken = 0;
Mel Gormana8a94d12010-08-09 17:19:17 -07001156 unsigned long nr_lumpy_taken = 0;
1157 unsigned long nr_lumpy_dirty = 0;
1158 unsigned long nr_lumpy_failed = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001159 unsigned long scan;
Hugh Dickinsf6260122012-01-12 17:20:06 -08001160 int lru = LRU_BASE;
1161
1162 lruvec = mem_cgroup_zone_lruvec(mz->zone, mz->mem_cgroup);
1163 if (active)
1164 lru += LRU_ACTIVE;
1165 if (file)
1166 lru += LRU_FILE;
1167 src = &lruvec->lists[lru];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001169 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001170 struct page *page;
1171 unsigned long pfn;
1172 unsigned long end_pfn;
1173 unsigned long page_pfn;
1174 int zone_id;
1175
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 page = lru_to_page(src);
1177 prefetchw_prev_lru_page(page, src, flags);
1178
Nick Piggin725d7042006-09-25 23:30:55 -07001179 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001180
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001181 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001182 case 0:
Johannes Weiner925b7672012-01-12 17:18:15 -08001183 mem_cgroup_lru_del(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001184 list_move(&page->lru, dst);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001185 nr_taken += hpage_nr_pages(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001186 break;
Nick Piggin46453a62006-03-22 00:07:58 -08001187
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001188 case -EBUSY:
1189 /* else it is being freed elsewhere */
1190 list_move(&page->lru, src);
1191 continue;
1192
1193 default:
1194 BUG();
1195 }
1196
1197 if (!order)
1198 continue;
1199
1200 /*
1201 * Attempt to take all pages in the order aligned region
1202 * surrounding the tag page. Only take those pages of
1203 * the same active state as that tag page. We may safely
1204 * round the target page pfn down to the requested order
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001205 * as the mem_map is guaranteed valid out to MAX_ORDER,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001206 * where that page is in a different zone we will detect
1207 * it from its zone id and abort this block scan.
1208 */
1209 zone_id = page_zone_id(page);
1210 page_pfn = page_to_pfn(page);
1211 pfn = page_pfn & ~((1 << order) - 1);
1212 end_pfn = pfn + (1 << order);
1213 for (; pfn < end_pfn; pfn++) {
1214 struct page *cursor_page;
1215
1216 /* The target page is in the block, ignore it. */
1217 if (unlikely(pfn == page_pfn))
1218 continue;
1219
1220 /* Avoid holes within the zone. */
1221 if (unlikely(!pfn_valid_within(pfn)))
1222 break;
1223
1224 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001225
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001226 /* Check that we have not crossed a zone boundary. */
1227 if (unlikely(page_zone_id(cursor_page) != zone_id))
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001228 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001229
1230 /*
1231 * If we don't have enough swap space, reclaiming of
1232 * anon page which don't already have a swap slot is
1233 * pointless.
1234 */
Hugh Dickins043bcbe2012-01-10 15:08:33 -08001235 if (nr_swap_pages <= 0 && PageSwapBacked(cursor_page) &&
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001236 !PageSwapCache(cursor_page))
1237 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001238
KAMEZAWA Hiroyukiee993b12009-06-16 15:33:24 -07001239 if (__isolate_lru_page(cursor_page, mode, file) == 0) {
Andrea Arcangeli50134732012-01-12 17:19:29 -08001240 unsigned int isolated_pages;
1241
Johannes Weiner925b7672012-01-12 17:18:15 -08001242 mem_cgroup_lru_del(cursor_page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001243 list_move(&cursor_page->lru, dst);
Andrea Arcangeli50134732012-01-12 17:19:29 -08001244 isolated_pages = hpage_nr_pages(cursor_page);
1245 nr_taken += isolated_pages;
1246 nr_lumpy_taken += isolated_pages;
Mel Gormana8a94d12010-08-09 17:19:17 -07001247 if (PageDirty(cursor_page))
Andrea Arcangeli50134732012-01-12 17:19:29 -08001248 nr_lumpy_dirty += isolated_pages;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001249 scan++;
Andrea Arcangeli50134732012-01-12 17:19:29 -08001250 pfn += isolated_pages - 1;
Mel Gormana8a94d12010-08-09 17:19:17 -07001251 } else {
Andrea Arcangelid179e842011-06-15 15:08:51 -07001252 /*
1253 * Check if the page is freed already.
1254 *
1255 * We can't use page_count() as that
1256 * requires compound_head and we don't
1257 * have a pin on the page here. If a
1258 * page is tail, we may or may not
1259 * have isolated the head, so assume
1260 * it's not free, it'd be tricky to
1261 * track the head status without a
1262 * page pin.
1263 */
1264 if (!PageTail(cursor_page) &&
1265 !atomic_read(&cursor_page->_count))
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001266 continue;
1267 break;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001268 }
1269 }
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001270
1271 /* If we break out of the loop above, lumpy reclaim failed */
1272 if (pfn < end_pfn)
1273 nr_lumpy_failed++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274 }
1275
Hugh Dickinsf6260122012-01-12 17:20:06 -08001276 *nr_scanned = scan;
Mel Gormana8a94d12010-08-09 17:19:17 -07001277
1278 trace_mm_vmscan_lru_isolate(order,
1279 nr_to_scan, scan,
1280 nr_taken,
1281 nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed,
Tao Maea4d3492012-01-12 17:19:20 -08001282 mode, file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 return nr_taken;
1284}
1285
Nick Piggin62695a82008-10-18 20:26:09 -07001286/**
1287 * isolate_lru_page - tries to isolate a page from its LRU list
1288 * @page: page to isolate from its LRU list
1289 *
1290 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1291 * vmstat statistic corresponding to whatever LRU list the page was on.
1292 *
1293 * Returns 0 if the page was removed from an LRU list.
1294 * Returns -EBUSY if the page was not on an LRU list.
1295 *
1296 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001297 * the active list, it will have PageActive set. If it was found on
1298 * the unevictable list, it will have the PageUnevictable bit set. That flag
1299 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001300 *
1301 * The vmstat statistic corresponding to the list on which the page was
1302 * found will be decremented.
1303 *
1304 * Restrictions:
1305 * (1) Must be called with an elevated refcount on the page. This is a
1306 * fundamentnal difference from isolate_lru_pages (which is called
1307 * without a stable reference).
1308 * (2) the lru_lock must not be held.
1309 * (3) interrupts must be enabled.
1310 */
1311int isolate_lru_page(struct page *page)
1312{
1313 int ret = -EBUSY;
1314
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001315 VM_BUG_ON(!page_count(page));
1316
Nick Piggin62695a82008-10-18 20:26:09 -07001317 if (PageLRU(page)) {
1318 struct zone *zone = page_zone(page);
1319
1320 spin_lock_irq(&zone->lru_lock);
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001321 if (PageLRU(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001322 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001323 ret = 0;
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001324 get_page(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001325 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001326
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001327 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001328 }
1329 spin_unlock_irq(&zone->lru_lock);
1330 }
1331 return ret;
1332}
1333
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001334/*
Rik van Riel35cd7812009-09-21 17:01:38 -07001335 * Are there way too many processes in the direct reclaim path already?
1336 */
1337static int too_many_isolated(struct zone *zone, int file,
1338 struct scan_control *sc)
1339{
1340 unsigned long inactive, isolated;
1341
1342 if (current_is_kswapd())
1343 return 0;
1344
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001345 if (!global_reclaim(sc))
Rik van Riel35cd7812009-09-21 17:01:38 -07001346 return 0;
1347
1348 if (file) {
1349 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1350 isolated = zone_page_state(zone, NR_ISOLATED_FILE);
1351 } else {
1352 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1353 isolated = zone_page_state(zone, NR_ISOLATED_ANON);
1354 }
1355
1356 return isolated > inactive;
1357}
1358
Mel Gorman66635622010-08-09 17:19:30 -07001359static noinline_for_stack void
Hugh Dickins3f797682012-01-12 17:20:07 -08001360putback_inactive_pages(struct mem_cgroup_zone *mz,
1361 struct list_head *page_list)
Mel Gorman66635622010-08-09 17:19:30 -07001362{
Johannes Weinerf16015f2012-01-12 17:17:52 -08001363 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
Hugh Dickins3f797682012-01-12 17:20:07 -08001364 struct zone *zone = mz->zone;
1365 LIST_HEAD(pages_to_free);
Mel Gorman66635622010-08-09 17:19:30 -07001366
Mel Gorman66635622010-08-09 17:19:30 -07001367 /*
1368 * Put back any unfreeable pages.
1369 */
Mel Gorman66635622010-08-09 17:19:30 -07001370 while (!list_empty(page_list)) {
Hugh Dickins3f797682012-01-12 17:20:07 -08001371 struct page *page = lru_to_page(page_list);
Mel Gorman66635622010-08-09 17:19:30 -07001372 int lru;
Hugh Dickins3f797682012-01-12 17:20:07 -08001373
Mel Gorman66635622010-08-09 17:19:30 -07001374 VM_BUG_ON(PageLRU(page));
1375 list_del(&page->lru);
1376 if (unlikely(!page_evictable(page, NULL))) {
1377 spin_unlock_irq(&zone->lru_lock);
1378 putback_lru_page(page);
1379 spin_lock_irq(&zone->lru_lock);
1380 continue;
1381 }
Linus Torvalds7a608572011-01-17 14:42:19 -08001382 SetPageLRU(page);
Mel Gorman66635622010-08-09 17:19:30 -07001383 lru = page_lru(page);
Linus Torvalds7a608572011-01-17 14:42:19 -08001384 add_page_to_lru_list(zone, page, lru);
Mel Gorman66635622010-08-09 17:19:30 -07001385 if (is_active_lru(lru)) {
1386 int file = is_file_lru(lru);
Rik van Riel9992af12011-01-13 15:47:13 -08001387 int numpages = hpage_nr_pages(page);
1388 reclaim_stat->recent_rotated[file] += numpages;
Mel Gorman66635622010-08-09 17:19:30 -07001389 }
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001390 if (put_page_testzero(page)) {
1391 __ClearPageLRU(page);
1392 __ClearPageActive(page);
1393 del_page_from_lru_list(zone, page, lru);
1394
1395 if (unlikely(PageCompound(page))) {
1396 spin_unlock_irq(&zone->lru_lock);
1397 (*get_compound_page_dtor(page))(page);
1398 spin_lock_irq(&zone->lru_lock);
1399 } else
1400 list_add(&page->lru, &pages_to_free);
Mel Gorman66635622010-08-09 17:19:30 -07001401 }
1402 }
Mel Gorman66635622010-08-09 17:19:30 -07001403
Hugh Dickins3f797682012-01-12 17:20:07 -08001404 /*
1405 * To save our caller's stack, now use input list for pages to free.
1406 */
1407 list_splice(&pages_to_free, page_list);
Mel Gorman66635622010-08-09 17:19:30 -07001408}
1409
Johannes Weinerf16015f2012-01-12 17:17:52 -08001410static noinline_for_stack void
1411update_isolated_counts(struct mem_cgroup_zone *mz,
Hugh Dickins3f797682012-01-12 17:20:07 -08001412 struct list_head *page_list,
Johannes Weinerf16015f2012-01-12 17:17:52 -08001413 unsigned long *nr_anon,
Hugh Dickins3f797682012-01-12 17:20:07 -08001414 unsigned long *nr_file)
Mel Gorman1489fa12010-08-09 17:19:33 -07001415{
Hugh Dickins3f797682012-01-12 17:20:07 -08001416 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
Johannes Weinerf16015f2012-01-12 17:17:52 -08001417 struct zone *zone = mz->zone;
Mel Gorman1489fa12010-08-09 17:19:33 -07001418 unsigned int count[NR_LRU_LISTS] = { 0, };
Hugh Dickins3f797682012-01-12 17:20:07 -08001419 unsigned long nr_active = 0;
1420 struct page *page;
1421 int lru;
Mel Gorman1489fa12010-08-09 17:19:33 -07001422
Hugh Dickins3f797682012-01-12 17:20:07 -08001423 /*
1424 * Count pages and clear active flags
1425 */
1426 list_for_each_entry(page, page_list, lru) {
1427 int numpages = hpage_nr_pages(page);
1428 lru = page_lru_base_type(page);
1429 if (PageActive(page)) {
1430 lru += LRU_ACTIVE;
1431 ClearPageActive(page);
1432 nr_active += numpages;
1433 }
1434 count[lru] += numpages;
1435 }
1436
Mel Gorman1489fa12010-08-09 17:19:33 -07001437 __count_vm_events(PGDEACTIVATE, nr_active);
1438
1439 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1440 -count[LRU_ACTIVE_FILE]);
1441 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1442 -count[LRU_INACTIVE_FILE]);
1443 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1444 -count[LRU_ACTIVE_ANON]);
1445 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1446 -count[LRU_INACTIVE_ANON]);
1447
1448 *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
1449 *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
Mel Gorman1489fa12010-08-09 17:19:33 -07001450
1451 reclaim_stat->recent_scanned[0] += *nr_anon;
1452 reclaim_stat->recent_scanned[1] += *nr_file;
1453}
1454
Mel Gorman66635622010-08-09 17:19:30 -07001455/*
Mel Gormana18bba02011-10-31 17:07:42 -07001456 * Returns true if a direct reclaim should wait on pages under writeback.
Wu Fengguange31f36982010-08-09 17:20:01 -07001457 *
1458 * If we are direct reclaiming for contiguous pages and we do not reclaim
1459 * everything in the list, try again and wait for writeback IO to complete.
1460 * This will stall high-order allocations noticeably. Only do that when really
1461 * need to free the pages under high memory pressure.
1462 */
1463static inline bool should_reclaim_stall(unsigned long nr_taken,
1464 unsigned long nr_freed,
1465 int priority,
1466 struct scan_control *sc)
1467{
1468 int lumpy_stall_priority;
1469
1470 /* kswapd should not stall on sync IO */
1471 if (current_is_kswapd())
1472 return false;
1473
1474 /* Only stall on lumpy reclaim */
Mel Gormanf3a310b2011-01-13 15:46:00 -08001475 if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
Wu Fengguange31f36982010-08-09 17:20:01 -07001476 return false;
1477
Justin P. Mattock81d66c72011-08-23 09:28:02 -07001478 /* If we have reclaimed everything on the isolated list, no stall */
Wu Fengguange31f36982010-08-09 17:20:01 -07001479 if (nr_freed == nr_taken)
1480 return false;
1481
1482 /*
1483 * For high-order allocations, there are two stall thresholds.
1484 * High-cost allocations stall immediately where as lower
1485 * order allocations such as stacks require the scanning
1486 * priority to be much higher before stalling.
1487 */
1488 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1489 lumpy_stall_priority = DEF_PRIORITY;
1490 else
1491 lumpy_stall_priority = DEF_PRIORITY / 3;
1492
1493 return priority <= lumpy_stall_priority;
1494}
1495
1496/*
Andrew Morton1742f192006-03-22 00:08:21 -08001497 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1498 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 */
Mel Gorman66635622010-08-09 17:19:30 -07001500static noinline_for_stack unsigned long
Johannes Weinerf16015f2012-01-12 17:17:52 -08001501shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
1502 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503{
1504 LIST_HEAD(page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001505 unsigned long nr_scanned;
Andrew Morton05ff5132006-03-22 00:08:20 -08001506 unsigned long nr_reclaimed = 0;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001507 unsigned long nr_taken;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001508 unsigned long nr_anon;
1509 unsigned long nr_file;
Mel Gorman92df3a72011-10-31 17:07:56 -07001510 unsigned long nr_dirty = 0;
1511 unsigned long nr_writeback = 0;
Minchan Kim4356f212011-10-31 17:06:47 -07001512 isolate_mode_t reclaim_mode = ISOLATE_INACTIVE;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001513 struct zone *zone = mz->zone;
KOSAKI Motohiro78dc5832009-06-16 15:31:40 -07001514
Rik van Riel35cd7812009-09-21 17:01:38 -07001515 while (unlikely(too_many_isolated(zone, file, sc))) {
KOSAKI Motohiro58355c72009-10-26 16:49:35 -07001516 congestion_wait(BLK_RW_ASYNC, HZ/10);
Rik van Riel35cd7812009-09-21 17:01:38 -07001517
1518 /* We are about to die and free our memory. Return now. */
1519 if (fatal_signal_pending(current))
1520 return SWAP_CLUSTER_MAX;
1521 }
1522
Mel Gormanf3a310b2011-01-13 15:46:00 -08001523 set_reclaim_mode(priority, sc, false);
Minchan Kim4356f212011-10-31 17:06:47 -07001524 if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
1525 reclaim_mode |= ISOLATE_ACTIVE;
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 lru_add_drain();
Minchan Kimf80c0672011-10-31 17:06:55 -07001528
1529 if (!sc->may_unmap)
1530 reclaim_mode |= ISOLATE_UNMAPPED;
1531 if (!sc->may_writepage)
1532 reclaim_mode |= ISOLATE_CLEAN;
1533
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 spin_lock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535
Hugh Dickinsf6260122012-01-12 17:20:06 -08001536 nr_taken = isolate_lru_pages(nr_to_scan, mz, &page_list,
1537 &nr_scanned, sc->order,
1538 reclaim_mode, 0, file);
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001539 if (global_reclaim(sc)) {
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001540 zone->pages_scanned += nr_scanned;
KOSAKI Motohirob35ea172009-09-21 17:01:36 -07001541 if (current_is_kswapd())
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001542 __count_zone_vm_events(PGSCAN_KSWAPD, zone,
1543 nr_scanned);
1544 else
1545 __count_zone_vm_events(PGSCAN_DIRECT, zone,
1546 nr_scanned);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001547 }
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001548
Mel Gorman66635622010-08-09 17:19:30 -07001549 if (nr_taken == 0) {
1550 spin_unlock_irq(&zone->lru_lock);
1551 return 0;
1552 }
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001553
Hugh Dickins3f797682012-01-12 17:20:07 -08001554 update_isolated_counts(mz, &page_list, &nr_anon, &nr_file);
1555
1556 __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
1557 __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001558
1559 spin_unlock_irq(&zone->lru_lock);
1560
Johannes Weinerf16015f2012-01-12 17:17:52 -08001561 nr_reclaimed = shrink_page_list(&page_list, mz, sc, priority,
Mel Gorman92df3a72011-10-31 17:07:56 -07001562 &nr_dirty, &nr_writeback);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001563
Wu Fengguange31f36982010-08-09 17:20:01 -07001564 /* Check if we should syncronously wait for writeback */
1565 if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
Mel Gormanf3a310b2011-01-13 15:46:00 -08001566 set_reclaim_mode(priority, sc, true);
Johannes Weinerf16015f2012-01-12 17:17:52 -08001567 nr_reclaimed += shrink_page_list(&page_list, mz, sc,
Mel Gorman92df3a72011-10-31 17:07:56 -07001568 priority, &nr_dirty, &nr_writeback);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001569 }
1570
Hugh Dickins3f797682012-01-12 17:20:07 -08001571 spin_lock_irq(&zone->lru_lock);
1572
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001573 if (current_is_kswapd())
1574 __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
1575 __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
1576
Hugh Dickins3f797682012-01-12 17:20:07 -08001577 putback_inactive_pages(mz, &page_list);
1578
1579 __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
1580 __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
1581
1582 spin_unlock_irq(&zone->lru_lock);
1583
1584 free_hot_cold_page_list(&page_list, 1);
Mel Gormane11da5b2010-10-26 14:21:40 -07001585
Mel Gorman92df3a72011-10-31 17:07:56 -07001586 /*
1587 * If reclaim is isolating dirty pages under writeback, it implies
1588 * that the long-lived page allocation rate is exceeding the page
1589 * laundering rate. Either the global limits are not being effective
1590 * at throttling processes due to the page distribution throughout
1591 * zones or there is heavy usage of a slow backing device. The
1592 * only option is to throttle from reclaim context which is not ideal
1593 * as there is no guarantee the dirtying process is throttled in the
1594 * same way balance_dirty_pages() manages.
1595 *
1596 * This scales the number of dirty pages that must be under writeback
1597 * before throttling depending on priority. It is a simple backoff
1598 * function that has the most effect in the range DEF_PRIORITY to
1599 * DEF_PRIORITY-2 which is the priority reclaim is considered to be
1600 * in trouble and reclaim is considered to be in trouble.
1601 *
1602 * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
1603 * DEF_PRIORITY-1 50% must be PageWriteback
1604 * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
1605 * ...
1606 * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
1607 * isolated page is PageWriteback
1608 */
1609 if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority)))
1610 wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
1611
Mel Gormane11da5b2010-10-26 14:21:40 -07001612 trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
1613 zone_idx(zone),
1614 nr_scanned, nr_reclaimed,
1615 priority,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001616 trace_shrink_flags(file, sc->reclaim_mode));
Andrew Morton05ff5132006-03-22 00:08:20 -08001617 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618}
1619
Martin Bligh3bb1a852006-10-28 10:38:24 -07001620/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621 * This moves pages from the active list to the inactive list.
1622 *
1623 * We move them the other way if the page is referenced by one or more
1624 * processes, from rmap.
1625 *
1626 * If the pages are mostly unmapped, the processing is fast and it is
1627 * appropriate to hold zone->lru_lock across the whole operation. But if
1628 * the pages are mapped, the processing is slow (page_referenced()) so we
1629 * should drop zone->lru_lock around each page. It's impossible to balance
1630 * this, so instead we remove the pages from the LRU while processing them.
1631 * It is safe to rely on PG_active against the non-LRU pages in here because
1632 * nobody will play with that bit on a non-LRU page.
1633 *
1634 * The downside is that we have to touch page->_count against each page.
1635 * But we had to alter page->flags anyway.
1636 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001637
Wu Fengguang3eb41402009-06-16 15:33:13 -07001638static void move_active_pages_to_lru(struct zone *zone,
1639 struct list_head *list,
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001640 struct list_head *pages_to_free,
Wu Fengguang3eb41402009-06-16 15:33:13 -07001641 enum lru_list lru)
1642{
1643 unsigned long pgmoved = 0;
Wu Fengguang3eb41402009-06-16 15:33:13 -07001644 struct page *page;
1645
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001646 if (buffer_heads_over_limit) {
1647 spin_unlock_irq(&zone->lru_lock);
1648 list_for_each_entry(page, list, lru) {
1649 if (page_has_private(page) && trylock_page(page)) {
1650 if (page_has_private(page))
1651 try_to_release_page(page, 0);
1652 unlock_page(page);
1653 }
1654 }
1655 spin_lock_irq(&zone->lru_lock);
1656 }
Wu Fengguang3eb41402009-06-16 15:33:13 -07001657
1658 while (!list_empty(list)) {
Johannes Weiner925b7672012-01-12 17:18:15 -08001659 struct lruvec *lruvec;
1660
Wu Fengguang3eb41402009-06-16 15:33:13 -07001661 page = lru_to_page(list);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001662
1663 VM_BUG_ON(PageLRU(page));
1664 SetPageLRU(page);
1665
Johannes Weiner925b7672012-01-12 17:18:15 -08001666 lruvec = mem_cgroup_lru_add_list(zone, page, lru);
1667 list_move(&page->lru, &lruvec->lists[lru]);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001668 pgmoved += hpage_nr_pages(page);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001669
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001670 if (put_page_testzero(page)) {
1671 __ClearPageLRU(page);
1672 __ClearPageActive(page);
1673 del_page_from_lru_list(zone, page, lru);
1674
1675 if (unlikely(PageCompound(page))) {
1676 spin_unlock_irq(&zone->lru_lock);
1677 (*get_compound_page_dtor(page))(page);
1678 spin_lock_irq(&zone->lru_lock);
1679 } else
1680 list_add(&page->lru, pages_to_free);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001681 }
1682 }
1683 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
1684 if (!is_active_lru(lru))
1685 __count_vm_events(PGDEACTIVATE, pgmoved);
1686}
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001687
Hugh Dickinsf6260122012-01-12 17:20:06 -08001688static void shrink_active_list(unsigned long nr_to_scan,
Johannes Weinerf16015f2012-01-12 17:17:52 -08001689 struct mem_cgroup_zone *mz,
1690 struct scan_control *sc,
1691 int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692{
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001693 unsigned long nr_taken;
Hugh Dickinsf6260122012-01-12 17:20:06 -08001694 unsigned long nr_scanned;
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -07001695 unsigned long vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 LIST_HEAD(l_hold); /* The pages which were snipped off */
Wu Fengguang8cab4752009-06-16 15:33:12 -07001697 LIST_HEAD(l_active);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001698 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 struct page *page;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001700 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001701 unsigned long nr_rotated = 0;
Minchan Kimf80c0672011-10-31 17:06:55 -07001702 isolate_mode_t reclaim_mode = ISOLATE_ACTIVE;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001703 struct zone *zone = mz->zone;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704
1705 lru_add_drain();
Minchan Kimf80c0672011-10-31 17:06:55 -07001706
1707 if (!sc->may_unmap)
1708 reclaim_mode |= ISOLATE_UNMAPPED;
1709 if (!sc->may_writepage)
1710 reclaim_mode |= ISOLATE_CLEAN;
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 spin_lock_irq(&zone->lru_lock);
Johannes Weiner925b7672012-01-12 17:18:15 -08001713
Hugh Dickinsf6260122012-01-12 17:20:06 -08001714 nr_taken = isolate_lru_pages(nr_to_scan, mz, &l_hold,
1715 &nr_scanned, sc->order,
1716 reclaim_mode, 1, file);
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001717 if (global_reclaim(sc))
Hugh Dickinsf6260122012-01-12 17:20:06 -08001718 zone->pages_scanned += nr_scanned;
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001719
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001720 reclaim_stat->recent_scanned[file] += nr_taken;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001721
Hugh Dickinsf6260122012-01-12 17:20:06 -08001722 __count_zone_vm_events(PGREFILL, zone, nr_scanned);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001723 if (file)
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001724 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001725 else
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001726 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001727 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 spin_unlock_irq(&zone->lru_lock);
1729
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 while (!list_empty(&l_hold)) {
1731 cond_resched();
1732 page = lru_to_page(&l_hold);
1733 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001734
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001735 if (unlikely(!page_evictable(page, NULL))) {
1736 putback_lru_page(page);
1737 continue;
1738 }
1739
Johannes Weinerf16015f2012-01-12 17:17:52 -08001740 if (page_referenced(page, 0, mz->mem_cgroup, &vm_flags)) {
Rik van Riel9992af12011-01-13 15:47:13 -08001741 nr_rotated += hpage_nr_pages(page);
Wu Fengguang8cab4752009-06-16 15:33:12 -07001742 /*
1743 * Identify referenced, file-backed active pages and
1744 * give them one more trip around the active list. So
1745 * that executable code get better chances to stay in
1746 * memory under moderate memory pressure. Anon pages
1747 * are not likely to be evicted by use-once streaming
1748 * IO, plus JVM can create lots of anon VM_EXEC pages,
1749 * so we ignore them here.
1750 */
Wu Fengguang41e20982009-10-26 16:49:53 -07001751 if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
Wu Fengguang8cab4752009-06-16 15:33:12 -07001752 list_add(&page->lru, &l_active);
1753 continue;
1754 }
1755 }
Rik van Riel7e9cd482008-10-18 20:26:35 -07001756
KOSAKI Motohiro5205e562009-09-21 17:01:44 -07001757 ClearPageActive(page); /* we are de-activating */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 list_add(&page->lru, &l_inactive);
1759 }
1760
Andrew Mortonb5557492009-01-06 14:40:13 -08001761 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001762 * Move pages back to the lru list.
Andrew Mortonb5557492009-01-06 14:40:13 -08001763 */
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001764 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001765 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001766 * Count referenced pages from currently used mappings as rotated,
1767 * even though only some of them are actually re-activated. This
1768 * helps balance scan pressure between file and anonymous pages in
1769 * get_scan_ratio.
Rik van Riel7e9cd482008-10-18 20:26:35 -07001770 */
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001771 reclaim_stat->recent_rotated[file] += nr_rotated;
Rik van Riel556adec2008-10-18 20:26:34 -07001772
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001773 move_active_pages_to_lru(zone, &l_active, &l_hold,
Wu Fengguang3eb41402009-06-16 15:33:13 -07001774 LRU_ACTIVE + file * LRU_FILE);
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001775 move_active_pages_to_lru(zone, &l_inactive, &l_hold,
Wu Fengguang3eb41402009-06-16 15:33:13 -07001776 LRU_BASE + file * LRU_FILE);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001777 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001778 spin_unlock_irq(&zone->lru_lock);
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001779
1780 free_hot_cold_page_list(&l_hold, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781}
1782
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001783#ifdef CONFIG_SWAP
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001784static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001785{
1786 unsigned long active, inactive;
1787
1788 active = zone_page_state(zone, NR_ACTIVE_ANON);
1789 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1790
1791 if (inactive * zone->inactive_ratio < active)
1792 return 1;
1793
1794 return 0;
1795}
1796
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001797/**
1798 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1799 * @zone: zone to check
1800 * @sc: scan control of this context
1801 *
1802 * Returns true if the zone does not have enough inactive anon pages,
1803 * meaning some active anon pages need to be deactivated.
1804 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001805static int inactive_anon_is_low(struct mem_cgroup_zone *mz)
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001806{
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001807 /*
1808 * If we don't have swap space, anonymous page deactivation
1809 * is pointless.
1810 */
1811 if (!total_swap_pages)
1812 return 0;
1813
Johannes Weinerf16015f2012-01-12 17:17:52 -08001814 if (!scanning_global_lru(mz))
1815 return mem_cgroup_inactive_anon_is_low(mz->mem_cgroup,
1816 mz->zone);
1817
1818 return inactive_anon_is_low_global(mz->zone);
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001819}
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001820#else
Johannes Weinerf16015f2012-01-12 17:17:52 -08001821static inline int inactive_anon_is_low(struct mem_cgroup_zone *mz)
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001822{
1823 return 0;
1824}
1825#endif
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001826
Rik van Riel56e49d22009-06-16 15:32:28 -07001827static int inactive_file_is_low_global(struct zone *zone)
1828{
1829 unsigned long active, inactive;
1830
1831 active = zone_page_state(zone, NR_ACTIVE_FILE);
1832 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1833
1834 return (active > inactive);
1835}
1836
1837/**
1838 * inactive_file_is_low - check if file pages need to be deactivated
Johannes Weinerf16015f2012-01-12 17:17:52 -08001839 * @mz: memory cgroup and zone to check
Rik van Riel56e49d22009-06-16 15:32:28 -07001840 *
1841 * When the system is doing streaming IO, memory pressure here
1842 * ensures that active file pages get deactivated, until more
1843 * than half of the file pages are on the inactive list.
1844 *
1845 * Once we get to that situation, protect the system's working
1846 * set from being evicted by disabling active file page aging.
1847 *
1848 * This uses a different ratio than the anonymous pages, because
1849 * the page cache uses a use-once replacement algorithm.
1850 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001851static int inactive_file_is_low(struct mem_cgroup_zone *mz)
Rik van Riel56e49d22009-06-16 15:32:28 -07001852{
Johannes Weinerf16015f2012-01-12 17:17:52 -08001853 if (!scanning_global_lru(mz))
1854 return mem_cgroup_inactive_file_is_low(mz->mem_cgroup,
1855 mz->zone);
Rik van Riel56e49d22009-06-16 15:32:28 -07001856
Johannes Weinerf16015f2012-01-12 17:17:52 -08001857 return inactive_file_is_low_global(mz->zone);
Rik van Riel56e49d22009-06-16 15:32:28 -07001858}
1859
Johannes Weinerf16015f2012-01-12 17:17:52 -08001860static int inactive_list_is_low(struct mem_cgroup_zone *mz, int file)
Rik van Rielb39415b2009-12-14 17:59:48 -08001861{
1862 if (file)
Johannes Weinerf16015f2012-01-12 17:17:52 -08001863 return inactive_file_is_low(mz);
Rik van Rielb39415b2009-12-14 17:59:48 -08001864 else
Johannes Weinerf16015f2012-01-12 17:17:52 -08001865 return inactive_anon_is_low(mz);
Rik van Rielb39415b2009-12-14 17:59:48 -08001866}
1867
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001868static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Johannes Weinerf16015f2012-01-12 17:17:52 -08001869 struct mem_cgroup_zone *mz,
1870 struct scan_control *sc, int priority)
Christoph Lameterb69408e2008-10-18 20:26:14 -07001871{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001872 int file = is_file_lru(lru);
1873
Rik van Rielb39415b2009-12-14 17:59:48 -08001874 if (is_active_lru(lru)) {
Johannes Weinerf16015f2012-01-12 17:17:52 -08001875 if (inactive_list_is_low(mz, file))
1876 shrink_active_list(nr_to_scan, mz, sc, priority, file);
Rik van Riel556adec2008-10-18 20:26:34 -07001877 return 0;
1878 }
1879
Johannes Weinerf16015f2012-01-12 17:17:52 -08001880 return shrink_inactive_list(nr_to_scan, mz, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001881}
1882
Johannes Weinerf16015f2012-01-12 17:17:52 -08001883static int vmscan_swappiness(struct mem_cgroup_zone *mz,
1884 struct scan_control *sc)
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001885{
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001886 if (global_reclaim(sc))
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001887 return vm_swappiness;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001888 return mem_cgroup_swappiness(mz->mem_cgroup);
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001889}
1890
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001892 * Determine how aggressively the anon and file LRU lists should be
1893 * scanned. The relative value of each set of LRU lists is determined
1894 * by looking at the fraction of the pages scanned we did rotate back
1895 * onto the active list instead of evict.
1896 *
Shaohua Li76a33fc2010-05-24 14:32:36 -07001897 * nr[0] = anon pages to scan; nr[1] = file pages to scan
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001898 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001899static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
1900 unsigned long *nr, int priority)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001901{
1902 unsigned long anon, file, free;
1903 unsigned long anon_prio, file_prio;
1904 unsigned long ap, fp;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001905 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
Shaohua Li76a33fc2010-05-24 14:32:36 -07001906 u64 fraction[2], denominator;
Hugh Dickins41113042012-01-12 17:20:01 -08001907 enum lru_list lru;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001908 int noswap = 0;
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001909 bool force_scan = false;
KAMEZAWA Hiroyuki246e87a2011-05-26 16:25:34 -07001910
Johannes Weinerf11c0ca2011-10-31 17:07:27 -07001911 /*
1912 * If the zone or memcg is small, nr[l] can be 0. This
1913 * results in no scanning on this priority and a potential
1914 * priority drop. Global direct reclaim can go to the next
1915 * zone and tends to have no problems. Global kswapd is for
1916 * zone balancing and it needs to scan a minimum amount. When
1917 * reclaiming for a memcg, a priority drop can cause high
1918 * latencies, so it's better to scan a minimum amount there as
1919 * well.
1920 */
Johannes Weinerb95a2f22012-01-12 17:18:06 -08001921 if (current_is_kswapd() && mz->zone->all_unreclaimable)
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001922 force_scan = true;
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001923 if (!global_reclaim(sc))
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001924 force_scan = true;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001925
1926 /* If we have no swap space, do not bother scanning anon pages. */
1927 if (!sc->may_swap || (nr_swap_pages <= 0)) {
1928 noswap = 1;
1929 fraction[0] = 0;
1930 fraction[1] = 1;
1931 denominator = 1;
1932 goto out;
1933 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001934
Johannes Weinerf16015f2012-01-12 17:17:52 -08001935 anon = zone_nr_lru_pages(mz, LRU_ACTIVE_ANON) +
1936 zone_nr_lru_pages(mz, LRU_INACTIVE_ANON);
1937 file = zone_nr_lru_pages(mz, LRU_ACTIVE_FILE) +
1938 zone_nr_lru_pages(mz, LRU_INACTIVE_FILE);
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001939
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001940 if (global_reclaim(sc)) {
Johannes Weinerf16015f2012-01-12 17:17:52 -08001941 free = zone_page_state(mz->zone, NR_FREE_PAGES);
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001942 /* If we have very few page cache pages,
1943 force-scan anon pages. */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001944 if (unlikely(file + free <= high_wmark_pages(mz->zone))) {
Shaohua Li76a33fc2010-05-24 14:32:36 -07001945 fraction[0] = 1;
1946 fraction[1] = 0;
1947 denominator = 1;
1948 goto out;
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001949 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001950 }
1951
1952 /*
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001953 * With swappiness at 100, anonymous and file have the same priority.
1954 * This scanning priority is essentially the inverse of IO cost.
1955 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001956 anon_prio = vmscan_swappiness(mz, sc);
1957 file_prio = 200 - vmscan_swappiness(mz, sc);
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001958
1959 /*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001960 * OK, so we have swap space and a fair amount of page cache
1961 * pages. We use the recently rotated / recently scanned
1962 * ratios to determine how valuable each cache is.
1963 *
1964 * Because workloads change over time (and to avoid overflow)
1965 * we keep these statistics as a floating average, which ends
1966 * up weighing recent references more than old ones.
1967 *
1968 * anon in [0], file in [1]
1969 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08001970 spin_lock_irq(&mz->zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001971 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001972 reclaim_stat->recent_scanned[0] /= 2;
1973 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001974 }
1975
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001976 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001977 reclaim_stat->recent_scanned[1] /= 2;
1978 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001979 }
1980
1981 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001982 * The amount of pressure on anon vs file pages is inversely
1983 * proportional to the fraction of recently scanned pages on
1984 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001985 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001986 ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
1987 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001988
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001989 fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
1990 fp /= reclaim_stat->recent_rotated[1] + 1;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001991 spin_unlock_irq(&mz->zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001992
Shaohua Li76a33fc2010-05-24 14:32:36 -07001993 fraction[0] = ap;
1994 fraction[1] = fp;
1995 denominator = ap + fp + 1;
1996out:
Hugh Dickins41113042012-01-12 17:20:01 -08001997 for_each_evictable_lru(lru) {
1998 int file = is_file_lru(lru);
Shaohua Li76a33fc2010-05-24 14:32:36 -07001999 unsigned long scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002000
Hugh Dickins41113042012-01-12 17:20:01 -08002001 scan = zone_nr_lru_pages(mz, lru);
Shaohua Li76a33fc2010-05-24 14:32:36 -07002002 if (priority || noswap) {
2003 scan >>= priority;
Johannes Weinerf11c0ca2011-10-31 17:07:27 -07002004 if (!scan && force_scan)
2005 scan = SWAP_CLUSTER_MAX;
Shaohua Li76a33fc2010-05-24 14:32:36 -07002006 scan = div64_u64(scan * fraction[file], denominator);
2007 }
Hugh Dickins41113042012-01-12 17:20:01 -08002008 nr[lru] = scan;
Shaohua Li76a33fc2010-05-24 14:32:36 -07002009 }
Wu Fengguang6e08a362009-06-16 15:32:29 -07002010}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002011
2012/*
Mel Gorman3e7d3442011-01-13 15:45:56 -08002013 * Reclaim/compaction depends on a number of pages being freed. To avoid
2014 * disruption to the system, a small number of order-0 pages continue to be
2015 * rotated and reclaimed in the normal fashion. However, by the time we get
2016 * back to the allocator and call try_to_compact_zone(), we ensure that
2017 * there are enough free pages for it to be likely successful
2018 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002019static inline bool should_continue_reclaim(struct mem_cgroup_zone *mz,
Mel Gorman3e7d3442011-01-13 15:45:56 -08002020 unsigned long nr_reclaimed,
2021 unsigned long nr_scanned,
2022 struct scan_control *sc)
2023{
2024 unsigned long pages_for_compaction;
2025 unsigned long inactive_lru_pages;
2026
2027 /* If not in reclaim/compaction mode, stop */
Mel Gormanf3a310b2011-01-13 15:46:00 -08002028 if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
Mel Gorman3e7d3442011-01-13 15:45:56 -08002029 return false;
2030
Mel Gorman28765922011-02-25 14:44:20 -08002031 /* Consider stopping depending on scan and reclaim activity */
2032 if (sc->gfp_mask & __GFP_REPEAT) {
2033 /*
2034 * For __GFP_REPEAT allocations, stop reclaiming if the
2035 * full LRU list has been scanned and we are still failing
2036 * to reclaim pages. This full LRU scan is potentially
2037 * expensive but a __GFP_REPEAT caller really wants to succeed
2038 */
2039 if (!nr_reclaimed && !nr_scanned)
2040 return false;
2041 } else {
2042 /*
2043 * For non-__GFP_REPEAT allocations which can presumably
2044 * fail without consequence, stop if we failed to reclaim
2045 * any pages from the last SWAP_CLUSTER_MAX number of
2046 * pages that were scanned. This will return to the
2047 * caller faster at the risk reclaim/compaction and
2048 * the resulting allocation attempt fails
2049 */
2050 if (!nr_reclaimed)
2051 return false;
2052 }
Mel Gorman3e7d3442011-01-13 15:45:56 -08002053
2054 /*
2055 * If we have not reclaimed enough pages for compaction and the
2056 * inactive lists are large enough, continue reclaiming
2057 */
2058 pages_for_compaction = (2UL << sc->order);
Johannes Weinerf16015f2012-01-12 17:17:52 -08002059 inactive_lru_pages = zone_nr_lru_pages(mz, LRU_INACTIVE_FILE);
Minchan Kim86cfd3a2012-01-10 15:08:18 -08002060 if (nr_swap_pages > 0)
Johannes Weinerf16015f2012-01-12 17:17:52 -08002061 inactive_lru_pages += zone_nr_lru_pages(mz, LRU_INACTIVE_ANON);
Mel Gorman3e7d3442011-01-13 15:45:56 -08002062 if (sc->nr_reclaimed < pages_for_compaction &&
2063 inactive_lru_pages > pages_for_compaction)
2064 return true;
2065
2066 /* If compaction would go ahead or the allocation would succeed, stop */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002067 switch (compaction_suitable(mz->zone, sc->order)) {
Mel Gorman3e7d3442011-01-13 15:45:56 -08002068 case COMPACT_PARTIAL:
2069 case COMPACT_CONTINUE:
2070 return false;
2071 default:
2072 return true;
2073 }
2074}
2075
2076/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
2078 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002079static void shrink_mem_cgroup_zone(int priority, struct mem_cgroup_zone *mz,
2080 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081{
Christoph Lameterb69408e2008-10-18 20:26:14 -07002082 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08002083 unsigned long nr_to_scan;
Hugh Dickins41113042012-01-12 17:20:01 -08002084 enum lru_list lru;
Johannes Weinerf0fdc5e2011-02-10 15:01:34 -08002085 unsigned long nr_reclaimed, nr_scanned;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002086 unsigned long nr_to_reclaim = sc->nr_to_reclaim;
Shaohua Li3da367c2011-10-31 17:07:03 -07002087 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088
Mel Gorman3e7d3442011-01-13 15:45:56 -08002089restart:
2090 nr_reclaimed = 0;
Johannes Weinerf0fdc5e2011-02-10 15:01:34 -08002091 nr_scanned = sc->nr_scanned;
Johannes Weinerf16015f2012-01-12 17:17:52 -08002092 get_scan_count(mz, sc, nr, priority);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002093
Shaohua Li3da367c2011-10-31 17:07:03 -07002094 blk_start_plug(&plug);
Rik van Riel556adec2008-10-18 20:26:34 -07002095 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
2096 nr[LRU_INACTIVE_FILE]) {
Hugh Dickins41113042012-01-12 17:20:01 -08002097 for_each_evictable_lru(lru) {
2098 if (nr[lru]) {
KOSAKI Motohiroece74b22009-12-14 17:59:14 -08002099 nr_to_scan = min_t(unsigned long,
Hugh Dickins41113042012-01-12 17:20:01 -08002100 nr[lru], SWAP_CLUSTER_MAX);
2101 nr[lru] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102
Hugh Dickins41113042012-01-12 17:20:01 -08002103 nr_reclaimed += shrink_list(lru, nr_to_scan,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002104 mz, sc, priority);
Christoph Lameterb69408e2008-10-18 20:26:14 -07002105 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 }
Rik van Riela79311c2009-01-06 14:40:01 -08002107 /*
2108 * On large memory systems, scan >> priority can become
2109 * really large. This is fine for the starting priority;
2110 * we want to put equal scanning pressure on each zone.
2111 * However, if the VM has a harder time of freeing pages,
2112 * with multiple processes reclaiming pages, the total
2113 * freeing target can get unreasonably large.
2114 */
KOSAKI Motohiro338fde92009-12-14 17:59:15 -08002115 if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
Rik van Riela79311c2009-01-06 14:40:01 -08002116 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 }
Shaohua Li3da367c2011-10-31 17:07:03 -07002118 blk_finish_plug(&plug);
Mel Gorman3e7d3442011-01-13 15:45:56 -08002119 sc->nr_reclaimed += nr_reclaimed;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08002120
Rik van Riel556adec2008-10-18 20:26:34 -07002121 /*
2122 * Even if we did not try to evict anon pages at all, we want to
2123 * rebalance the anon lru active/inactive ratio.
2124 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002125 if (inactive_anon_is_low(mz))
2126 shrink_active_list(SWAP_CLUSTER_MAX, mz, sc, priority, 0);
Rik van Riel556adec2008-10-18 20:26:34 -07002127
Mel Gorman3e7d3442011-01-13 15:45:56 -08002128 /* reclaim/compaction might need reclaim to continue */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002129 if (should_continue_reclaim(mz, nr_reclaimed,
Mel Gorman3e7d3442011-01-13 15:45:56 -08002130 sc->nr_scanned - nr_scanned, sc))
2131 goto restart;
2132
Andrew Morton232ea4d2007-02-28 20:13:21 -08002133 throttle_vm_writeout(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134}
2135
Johannes Weinerf16015f2012-01-12 17:17:52 -08002136static void shrink_zone(int priority, struct zone *zone,
2137 struct scan_control *sc)
2138{
Johannes Weiner56600482012-01-12 17:17:59 -08002139 struct mem_cgroup *root = sc->target_mem_cgroup;
2140 struct mem_cgroup_reclaim_cookie reclaim = {
Johannes Weinerf16015f2012-01-12 17:17:52 -08002141 .zone = zone,
Johannes Weiner56600482012-01-12 17:17:59 -08002142 .priority = priority,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002143 };
Johannes Weiner56600482012-01-12 17:17:59 -08002144 struct mem_cgroup *memcg;
Johannes Weinerf16015f2012-01-12 17:17:52 -08002145
Johannes Weiner56600482012-01-12 17:17:59 -08002146 memcg = mem_cgroup_iter(root, NULL, &reclaim);
2147 do {
2148 struct mem_cgroup_zone mz = {
2149 .mem_cgroup = memcg,
2150 .zone = zone,
2151 };
2152
2153 shrink_mem_cgroup_zone(priority, &mz, sc);
2154 /*
2155 * Limit reclaim has historically picked one memcg and
2156 * scanned it with decreasing priority levels until
2157 * nr_to_reclaim had been reclaimed. This priority
2158 * cycle is thus over after a single memcg.
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002159 *
2160 * Direct reclaim and kswapd, on the other hand, have
2161 * to scan all memory cgroups to fulfill the overall
2162 * scan target for the zone.
Johannes Weiner56600482012-01-12 17:17:59 -08002163 */
2164 if (!global_reclaim(sc)) {
2165 mem_cgroup_iter_break(root, memcg);
2166 break;
2167 }
2168 memcg = mem_cgroup_iter(root, memcg, &reclaim);
2169 } while (memcg);
Johannes Weinerf16015f2012-01-12 17:17:52 -08002170}
2171
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002172/* Returns true if compaction should go ahead for a high-order request */
2173static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
2174{
2175 unsigned long balance_gap, watermark;
2176 bool watermark_ok;
2177
2178 /* Do not consider compaction for orders reclaim is meant to satisfy */
2179 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER)
2180 return false;
2181
2182 /*
2183 * Compaction takes time to run and there are potentially other
2184 * callers using the pages just freed. Continue reclaiming until
2185 * there is a buffer of free pages available to give compaction
2186 * a reasonable chance of completing and allocating the page
2187 */
2188 balance_gap = min(low_wmark_pages(zone),
2189 (zone->present_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
2190 KSWAPD_ZONE_BALANCE_GAP_RATIO);
2191 watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order);
2192 watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0);
2193
2194 /*
2195 * If compaction is deferred, reclaim up to a point where
2196 * compaction will have a chance of success when re-enabled
2197 */
2198 if (compaction_deferred(zone))
2199 return watermark_ok;
2200
2201 /* If compaction is not ready to start, keep reclaiming */
2202 if (!compaction_suitable(zone, sc->order))
2203 return false;
2204
2205 return watermark_ok;
2206}
2207
Linus Torvalds1da177e2005-04-16 15:20:36 -07002208/*
2209 * This is the direct reclaim path, for page-allocating processes. We only
2210 * try to reclaim pages from zones which will satisfy the caller's allocation
2211 * request.
2212 *
Mel Gorman41858962009-06-16 15:32:12 -07002213 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
2214 * Because:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
2216 * allocation or
Mel Gorman41858962009-06-16 15:32:12 -07002217 * b) The target zone may be at high_wmark_pages(zone) but the lower zones
2218 * must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
2219 * zone defense algorithm.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 * If a zone is deemed to be full of pinned pages then just give it a light
2222 * scan then give up on it.
Mel Gormane0c23272011-10-31 17:09:33 -07002223 *
2224 * This function returns true if a zone is being reclaimed for a costly
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002225 * high-order allocation and compaction is ready to begin. This indicates to
Mel Gorman0cee34f2012-01-12 17:19:49 -08002226 * the caller that it should consider retrying the allocation instead of
2227 * further reclaim.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228 */
Mel Gormane0c23272011-10-31 17:09:33 -07002229static bool shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08002230 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231{
Mel Gormandd1a2392008-04-28 02:12:17 -07002232 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002233 struct zone *zone;
Ying Hand149e3b2011-05-26 16:25:27 -07002234 unsigned long nr_soft_reclaimed;
2235 unsigned long nr_soft_scanned;
Mel Gorman0cee34f2012-01-12 17:19:49 -08002236 bool aborted_reclaim = false;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002237
Mel Gormand4debc62010-08-09 17:19:29 -07002238 for_each_zone_zonelist_nodemask(zone, z, zonelist,
2239 gfp_zone(sc->gfp_mask), sc->nodemask) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08002240 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002242 /*
2243 * Take care memory controller reclaiming has small influence
2244 * to global LRU.
2245 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002246 if (global_reclaim(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002247 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2248 continue;
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002249 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002250 continue; /* Let kswapd poll it */
Rik van Riele0887c12011-10-31 17:09:31 -07002251 if (COMPACTION_BUILD) {
2252 /*
Mel Gormane0c23272011-10-31 17:09:33 -07002253 * If we already have plenty of memory free for
2254 * compaction in this zone, don't free any more.
2255 * Even though compaction is invoked for any
2256 * non-zero order, only frequent costly order
2257 * reclamation is disruptive enough to become a
2258 * noticable problem, like transparent huge page
2259 * allocations.
Rik van Riele0887c12011-10-31 17:09:31 -07002260 */
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002261 if (compaction_ready(zone, sc)) {
Mel Gorman0cee34f2012-01-12 17:19:49 -08002262 aborted_reclaim = true;
Rik van Riele0887c12011-10-31 17:09:31 -07002263 continue;
Mel Gormane0c23272011-10-31 17:09:33 -07002264 }
Rik van Riele0887c12011-10-31 17:09:31 -07002265 }
KAMEZAWA Hiroyukiac34a1a2011-06-27 16:18:12 -07002266 /*
2267 * This steals pages from memory cgroups over softlimit
2268 * and returns the number of reclaimed pages and
2269 * scanned pages. This works for global memory pressure
2270 * and balancing, not for a memcg's limit.
2271 */
2272 nr_soft_scanned = 0;
2273 nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
2274 sc->order, sc->gfp_mask,
2275 &nr_soft_scanned);
2276 sc->nr_reclaimed += nr_soft_reclaimed;
2277 sc->nr_scanned += nr_soft_scanned;
2278 /* need some check for avoid more shrink_zone() */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002279 }
Nick Piggin408d8542006-09-25 23:31:27 -07002280
Rik van Riela79311c2009-01-06 14:40:01 -08002281 shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282 }
Mel Gormane0c23272011-10-31 17:09:33 -07002283
Mel Gorman0cee34f2012-01-12 17:19:49 -08002284 return aborted_reclaim;
Minchan Kimd1908362010-09-22 13:05:01 -07002285}
2286
2287static bool zone_reclaimable(struct zone *zone)
2288{
2289 return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
2290}
2291
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002292/* All zones in zonelist are unreclaimable? */
Minchan Kimd1908362010-09-22 13:05:01 -07002293static bool all_unreclaimable(struct zonelist *zonelist,
2294 struct scan_control *sc)
2295{
2296 struct zoneref *z;
2297 struct zone *zone;
Minchan Kimd1908362010-09-22 13:05:01 -07002298
2299 for_each_zone_zonelist_nodemask(zone, z, zonelist,
2300 gfp_zone(sc->gfp_mask), sc->nodemask) {
2301 if (!populated_zone(zone))
2302 continue;
2303 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2304 continue;
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002305 if (!zone->all_unreclaimable)
2306 return false;
Minchan Kimd1908362010-09-22 13:05:01 -07002307 }
2308
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002309 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002310}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002311
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312/*
2313 * This is the main entry point to direct page reclaim.
2314 *
2315 * If a full scan of the inactive list fails to free enough memory then we
2316 * are "out of memory" and something needs to be killed.
2317 *
2318 * If the caller is !__GFP_FS then the probability of a failure is reasonably
2319 * high - the zone may be full of dirty or under-writeback pages, which this
Jens Axboe5b0830c2009-09-23 19:37:09 +02002320 * caller can't do much about. We kick the writeback threads and take explicit
2321 * naps in the hope that some of these pages can be written. But if the
2322 * allocating task holds filesystem locks which prevent writeout this might not
2323 * work, and the allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07002324 *
2325 * returns: 0, if no pages reclaimed
2326 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 */
Mel Gormandac1d272008-04-28 02:12:12 -07002328static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Ying Hana09ed5e2011-05-24 17:12:26 -07002329 struct scan_control *sc,
2330 struct shrink_control *shrink)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331{
2332 int priority;
Andrew Morton69e05942006-03-22 00:08:19 -08002333 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334 struct reclaim_state *reclaim_state = current->reclaim_state;
Mel Gormandd1a2392008-04-28 02:12:17 -07002335 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002336 struct zone *zone;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002337 unsigned long writeback_threshold;
Mel Gorman0cee34f2012-01-12 17:19:49 -08002338 bool aborted_reclaim;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339
Miao Xiec0ff7452010-05-24 14:32:08 -07002340 get_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002341 delayacct_freepages_start();
2342
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002343 if (global_reclaim(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002344 count_vm_event(ALLOCSTALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345
2346 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08002347 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002348 if (!priority)
Johannes Weinerf16015f2012-01-12 17:17:52 -08002349 disable_swap_token(sc->target_mem_cgroup);
Mel Gorman0cee34f2012-01-12 17:19:49 -08002350 aborted_reclaim = shrink_zones(priority, zonelist, sc);
Mel Gormane0c23272011-10-31 17:09:33 -07002351
Balbir Singh66e17072008-02-07 00:13:56 -08002352 /*
2353 * Don't shrink slabs when reclaiming memory from
2354 * over limit cgroups
2355 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002356 if (global_reclaim(sc)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002357 unsigned long lru_pages = 0;
Mel Gormand4debc62010-08-09 17:19:29 -07002358 for_each_zone_zonelist(zone, z, zonelist,
2359 gfp_zone(sc->gfp_mask)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002360 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2361 continue;
2362
2363 lru_pages += zone_reclaimable_pages(zone);
2364 }
2365
Ying Han1495f232011-05-24 17:12:27 -07002366 shrink_slab(shrink, sc->nr_scanned, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002367 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08002368 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002369 reclaim_state->reclaimed_slab = 0;
2370 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371 }
Balbir Singh66e17072008-02-07 00:13:56 -08002372 total_scanned += sc->nr_scanned;
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002373 if (sc->nr_reclaimed >= sc->nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002375
2376 /*
2377 * Try to write back as many pages as we just scanned. This
2378 * tends to cause slow streaming writers to write data to the
2379 * disk smoothly, at the dirtying rate, which is nice. But
2380 * that's undesirable in laptop mode, where we *want* lumpy
2381 * writeout. So in laptop mode, write out the whole world.
2382 */
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002383 writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
2384 if (total_scanned > writeback_threshold) {
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002385 wakeup_flusher_threads(laptop_mode ? 0 : total_scanned,
2386 WB_REASON_TRY_TO_FREE_PAGES);
Balbir Singh66e17072008-02-07 00:13:56 -08002387 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388 }
2389
2390 /* Take a nap, wait for some writeback to complete */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002391 if (!sc->hibernation_mode && sc->nr_scanned &&
Mel Gorman0e093d992010-10-26 14:21:45 -07002392 priority < DEF_PRIORITY - 2) {
2393 struct zone *preferred_zone;
2394
2395 first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
David Rientjesf33261d2011-01-25 15:07:20 -08002396 &cpuset_current_mems_allowed,
2397 &preferred_zone);
Mel Gorman0e093d992010-10-26 14:21:45 -07002398 wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
2399 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002400 }
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002401
Linus Torvalds1da177e2005-04-16 15:20:36 -07002402out:
Keika Kobayashi873b4772008-07-25 01:48:52 -07002403 delayacct_freepages_end();
Miao Xiec0ff7452010-05-24 14:32:08 -07002404 put_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002405
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002406 if (sc->nr_reclaimed)
2407 return sc->nr_reclaimed;
2408
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002409 /*
2410 * As hibernation is going on, kswapd is freezed so that it can't mark
2411 * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
2412 * check.
2413 */
2414 if (oom_killer_disabled)
2415 return 0;
2416
Mel Gorman0cee34f2012-01-12 17:19:49 -08002417 /* Aborted reclaim to try compaction? don't OOM, then */
2418 if (aborted_reclaim)
Mel Gorman73350842012-01-12 17:19:33 -08002419 return 1;
2420
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002421 /* top priority shrink_zones still had more to do? don't OOM, then */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002422 if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002423 return 1;
2424
2425 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426}
2427
Mel Gormandac1d272008-04-28 02:12:12 -07002428unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002429 gfp_t gfp_mask, nodemask_t *nodemask)
Balbir Singh66e17072008-02-07 00:13:56 -08002430{
Mel Gorman33906bc2010-08-09 17:19:16 -07002431 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002432 struct scan_control sc = {
2433 .gfp_mask = gfp_mask,
2434 .may_writepage = !laptop_mode,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002435 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002436 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002437 .may_swap = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08002438 .order = order,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002439 .target_mem_cgroup = NULL,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002440 .nodemask = nodemask,
Balbir Singh66e17072008-02-07 00:13:56 -08002441 };
Ying Hana09ed5e2011-05-24 17:12:26 -07002442 struct shrink_control shrink = {
2443 .gfp_mask = sc.gfp_mask,
2444 };
Balbir Singh66e17072008-02-07 00:13:56 -08002445
Mel Gorman33906bc2010-08-09 17:19:16 -07002446 trace_mm_vmscan_direct_reclaim_begin(order,
2447 sc.may_writepage,
2448 gfp_mask);
2449
Ying Hana09ed5e2011-05-24 17:12:26 -07002450 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
Mel Gorman33906bc2010-08-09 17:19:16 -07002451
2452 trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
2453
2454 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002455}
2456
Balbir Singh00f0b822008-03-04 14:28:39 -08002457#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08002458
Johannes Weiner72835c82012-01-12 17:18:32 -08002459unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
Balbir Singh4e416952009-09-23 15:56:39 -07002460 gfp_t gfp_mask, bool noswap,
Ying Han0ae5e892011-05-26 16:25:25 -07002461 struct zone *zone,
2462 unsigned long *nr_scanned)
Balbir Singh4e416952009-09-23 15:56:39 -07002463{
2464 struct scan_control sc = {
Ying Han0ae5e892011-05-26 16:25:25 -07002465 .nr_scanned = 0,
KOSAKI Motohirob8f5c562010-08-10 18:03:02 -07002466 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh4e416952009-09-23 15:56:39 -07002467 .may_writepage = !laptop_mode,
2468 .may_unmap = 1,
2469 .may_swap = !noswap,
Balbir Singh4e416952009-09-23 15:56:39 -07002470 .order = 0,
Johannes Weiner72835c82012-01-12 17:18:32 -08002471 .target_mem_cgroup = memcg,
Balbir Singh4e416952009-09-23 15:56:39 -07002472 };
Johannes Weiner56600482012-01-12 17:17:59 -08002473 struct mem_cgroup_zone mz = {
Johannes Weiner72835c82012-01-12 17:18:32 -08002474 .mem_cgroup = memcg,
Johannes Weiner56600482012-01-12 17:17:59 -08002475 .zone = zone,
2476 };
Ying Han0ae5e892011-05-26 16:25:25 -07002477
Balbir Singh4e416952009-09-23 15:56:39 -07002478 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2479 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002480
2481 trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
2482 sc.may_writepage,
2483 sc.gfp_mask);
2484
Balbir Singh4e416952009-09-23 15:56:39 -07002485 /*
2486 * NOTE: Although we can get the priority field, using it
2487 * here is not a good idea, since it limits the pages we can scan.
2488 * if we don't reclaim here, the shrink_zone from balance_pgdat
2489 * will pick up pages from other mem cgroup's as well. We hack
2490 * the priority and make it zero.
2491 */
Johannes Weiner56600482012-01-12 17:17:59 -08002492 shrink_mem_cgroup_zone(0, &mz, &sc);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002493
2494 trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
2495
Ying Han0ae5e892011-05-26 16:25:25 -07002496 *nr_scanned = sc.nr_scanned;
Balbir Singh4e416952009-09-23 15:56:39 -07002497 return sc.nr_reclaimed;
2498}
2499
Johannes Weiner72835c82012-01-12 17:18:32 -08002500unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002501 gfp_t gfp_mask,
Johannes Weiner185efc02011-09-14 16:21:58 -07002502 bool noswap)
Balbir Singh66e17072008-02-07 00:13:56 -08002503{
Balbir Singh4e416952009-09-23 15:56:39 -07002504 struct zonelist *zonelist;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002505 unsigned long nr_reclaimed;
Ying Han889976d2011-05-26 16:25:33 -07002506 int nid;
Balbir Singh66e17072008-02-07 00:13:56 -08002507 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08002508 .may_writepage = !laptop_mode,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002509 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002510 .may_swap = !noswap,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002511 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh66e17072008-02-07 00:13:56 -08002512 .order = 0,
Johannes Weiner72835c82012-01-12 17:18:32 -08002513 .target_mem_cgroup = memcg,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002514 .nodemask = NULL, /* we don't care the placement */
Ying Hana09ed5e2011-05-24 17:12:26 -07002515 .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2516 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
2517 };
2518 struct shrink_control shrink = {
2519 .gfp_mask = sc.gfp_mask,
Balbir Singh66e17072008-02-07 00:13:56 -08002520 };
Balbir Singh66e17072008-02-07 00:13:56 -08002521
Ying Han889976d2011-05-26 16:25:33 -07002522 /*
2523 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
2524 * take care of from where we get pages. So the node where we start the
2525 * scan does not need to be the current node.
2526 */
Johannes Weiner72835c82012-01-12 17:18:32 -08002527 nid = mem_cgroup_select_victim_node(memcg);
Ying Han889976d2011-05-26 16:25:33 -07002528
2529 zonelist = NODE_DATA(nid)->node_zonelists;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002530
2531 trace_mm_vmscan_memcg_reclaim_begin(0,
2532 sc.may_writepage,
2533 sc.gfp_mask);
2534
Ying Hana09ed5e2011-05-24 17:12:26 -07002535 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002536
2537 trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
2538
2539 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002540}
2541#endif
2542
Johannes Weinerf16015f2012-01-12 17:17:52 -08002543static void age_active_anon(struct zone *zone, struct scan_control *sc,
2544 int priority)
2545{
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002546 struct mem_cgroup *memcg;
Johannes Weinerf16015f2012-01-12 17:17:52 -08002547
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002548 if (!total_swap_pages)
2549 return;
2550
2551 memcg = mem_cgroup_iter(NULL, NULL, NULL);
2552 do {
2553 struct mem_cgroup_zone mz = {
2554 .mem_cgroup = memcg,
2555 .zone = zone,
2556 };
2557
2558 if (inactive_anon_is_low(&mz))
2559 shrink_active_list(SWAP_CLUSTER_MAX, &mz,
2560 sc, priority, 0);
2561
2562 memcg = mem_cgroup_iter(NULL, memcg, NULL);
2563 } while (memcg);
Johannes Weinerf16015f2012-01-12 17:17:52 -08002564}
2565
Mel Gorman1741c872011-01-13 15:46:21 -08002566/*
2567 * pgdat_balanced is used when checking if a node is balanced for high-order
2568 * allocations. Only zones that meet watermarks and are in a zone allowed
2569 * by the callers classzone_idx are added to balanced_pages. The total of
2570 * balanced pages must be at least 25% of the zones allowed by classzone_idx
2571 * for the node to be considered balanced. Forcing all zones to be balanced
2572 * for high orders can cause excessive reclaim when there are imbalanced zones.
2573 * The choice of 25% is due to
2574 * o a 16M DMA zone that is balanced will not balance a zone on any
2575 * reasonable sized machine
2576 * o On all other machines, the top zone must be at least a reasonable
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002577 * percentage of the middle zones. For example, on 32-bit x86, highmem
Mel Gorman1741c872011-01-13 15:46:21 -08002578 * would need to be at least 256M for it to be balance a whole node.
2579 * Similarly, on x86-64 the Normal zone would need to be at least 1G
2580 * to balance a node on its own. These seemed like reasonable ratios.
2581 */
2582static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
2583 int classzone_idx)
2584{
2585 unsigned long present_pages = 0;
2586 int i;
2587
2588 for (i = 0; i <= classzone_idx; i++)
2589 present_pages += pgdat->node_zones[i].present_pages;
2590
Shaohua Li4746efd2011-07-19 08:49:26 -07002591 /* A special case here: if zone has no page, we think it's balanced */
2592 return balanced_pages >= (present_pages >> 2);
Mel Gorman1741c872011-01-13 15:46:21 -08002593}
2594
Mel Gormanf50de2d2009-12-14 17:58:53 -08002595/* is kswapd sleeping prematurely? */
Mel Gormandc83edd2011-01-13 15:46:26 -08002596static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
2597 int classzone_idx)
Mel Gormanf50de2d2009-12-14 17:58:53 -08002598{
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002599 int i;
Mel Gorman1741c872011-01-13 15:46:21 -08002600 unsigned long balanced = 0;
2601 bool all_zones_ok = true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002602
2603 /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
2604 if (remaining)
Mel Gormandc83edd2011-01-13 15:46:26 -08002605 return true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002606
Mel Gorman0abdee22011-01-13 15:46:22 -08002607 /* Check the watermark levels */
Mel Gorman08951e52011-07-08 15:39:36 -07002608 for (i = 0; i <= classzone_idx; i++) {
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002609 struct zone *zone = pgdat->node_zones + i;
2610
2611 if (!populated_zone(zone))
2612 continue;
2613
Mel Gorman355b09c2011-01-13 15:46:24 -08002614 /*
2615 * balance_pgdat() skips over all_unreclaimable after
2616 * DEF_PRIORITY. Effectively, it considers them balanced so
2617 * they must be considered balanced here as well if kswapd
2618 * is to sleep
2619 */
2620 if (zone->all_unreclaimable) {
2621 balanced += zone->present_pages;
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002622 continue;
Mel Gorman355b09c2011-01-13 15:46:24 -08002623 }
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002624
Mel Gorman88f5acf2011-01-13 15:45:41 -08002625 if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
Mel Gormanda175d02011-07-08 15:39:39 -07002626 i, 0))
Mel Gorman1741c872011-01-13 15:46:21 -08002627 all_zones_ok = false;
2628 else
2629 balanced += zone->present_pages;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002630 }
Mel Gormanf50de2d2009-12-14 17:58:53 -08002631
Mel Gorman1741c872011-01-13 15:46:21 -08002632 /*
2633 * For high-order requests, the balanced zones must contain at least
2634 * 25% of the nodes pages for kswapd to sleep. For order-0, all zones
2635 * must be balanced
2636 */
2637 if (order)
Johannes Weinerafc7e322011-05-24 17:11:09 -07002638 return !pgdat_balanced(pgdat, balanced, classzone_idx);
Mel Gorman1741c872011-01-13 15:46:21 -08002639 else
2640 return !all_zones_ok;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002641}
2642
Linus Torvalds1da177e2005-04-16 15:20:36 -07002643/*
2644 * For kswapd, balance_pgdat() will work across all this node's zones until
Mel Gorman41858962009-06-16 15:32:12 -07002645 * they are all at high_wmark_pages(zone).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002646 *
Mel Gorman0abdee22011-01-13 15:46:22 -08002647 * Returns the final order kswapd was reclaiming at
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648 *
2649 * There is special handling here for zones which are full of pinned pages.
2650 * This can happen if the pages are all mlocked, or if they are all used by
2651 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
2652 * What we do is to detect the case where all pages in the zone have been
2653 * scanned twice and there has been zero successful reclaim. Mark the zone as
2654 * dead and from now on, only perform a short scan. Basically we're polling
2655 * the zone for when the problem goes away.
2656 *
2657 * kswapd scans the zones in the highmem->normal->dma direction. It skips
Mel Gorman41858962009-06-16 15:32:12 -07002658 * zones which have free_pages > high_wmark_pages(zone), but once a zone is
2659 * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
2660 * lower zones regardless of the number of free pages in the lower zones. This
2661 * interoperates with the page allocator fallback scheme to ensure that aging
2662 * of pages is balanced across the zones.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663 */
Mel Gorman99504742011-01-13 15:46:20 -08002664static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
Mel Gormandc83edd2011-01-13 15:46:26 -08002665 int *classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002667 int all_zones_ok;
Mel Gorman1741c872011-01-13 15:46:21 -08002668 unsigned long balanced;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002669 int priority;
2670 int i;
Mel Gorman99504742011-01-13 15:46:20 -08002671 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
Andrew Morton69e05942006-03-22 00:08:19 -08002672 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673 struct reclaim_state *reclaim_state = current->reclaim_state;
Ying Han0ae5e892011-05-26 16:25:25 -07002674 unsigned long nr_soft_reclaimed;
2675 unsigned long nr_soft_scanned;
Andrew Morton179e9632006-03-22 00:08:18 -08002676 struct scan_control sc = {
2677 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f2009-03-31 15:19:30 -07002678 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002679 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002680 /*
2681 * kswapd doesn't want to be bailed out while reclaim. because
2682 * we want to put equal scanning pressure on each zone.
2683 */
2684 .nr_to_reclaim = ULONG_MAX,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07002685 .order = order,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002686 .target_mem_cgroup = NULL,
Andrew Morton179e9632006-03-22 00:08:18 -08002687 };
Ying Hana09ed5e2011-05-24 17:12:26 -07002688 struct shrink_control shrink = {
2689 .gfp_mask = sc.gfp_mask,
2690 };
Linus Torvalds1da177e2005-04-16 15:20:36 -07002691loop_again:
2692 total_scanned = 0;
Rik van Riela79311c2009-01-06 14:40:01 -08002693 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07002694 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07002695 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002696
Linus Torvalds1da177e2005-04-16 15:20:36 -07002697 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002698 unsigned long lru_pages = 0;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002699 int has_under_min_watermark_zone = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002700
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002701 /* The swap token gets in the way of swapout... */
2702 if (!priority)
KOSAKI Motohiroa4336582011-06-15 15:08:13 -07002703 disable_swap_token(NULL);
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002704
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705 all_zones_ok = 1;
Mel Gorman1741c872011-01-13 15:46:21 -08002706 balanced = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002707
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002708 /*
2709 * Scan in the highmem->dma direction for the highest
2710 * zone which needs scanning
2711 */
2712 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
2713 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002714
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002715 if (!populated_zone(zone))
2716 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002718 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002719 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002720
Rik van Riel556adec2008-10-18 20:26:34 -07002721 /*
2722 * Do some background aging of the anon list, to give
2723 * pages a chance to be referenced before reclaiming.
2724 */
Johannes Weinerf16015f2012-01-12 17:17:52 -08002725 age_active_anon(zone, &sc, priority);
Rik van Riel556adec2008-10-18 20:26:34 -07002726
Mel Gorman88f5acf2011-01-13 15:45:41 -08002727 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman41858962009-06-16 15:32:12 -07002728 high_wmark_pages(zone), 0, 0)) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002729 end_zone = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002730 break;
Shaohua Li439423f2011-08-25 15:59:12 -07002731 } else {
2732 /* If balanced, clear the congested flag */
2733 zone_clear_flag(zone, ZONE_CONGESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002736 if (i < 0)
2737 goto out;
2738
Linus Torvalds1da177e2005-04-16 15:20:36 -07002739 for (i = 0; i <= end_zone; i++) {
2740 struct zone *zone = pgdat->node_zones + i;
2741
Wu Fengguangadea02a2009-09-21 17:01:42 -07002742 lru_pages += zone_reclaimable_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002743 }
2744
2745 /*
2746 * Now scan the zone in the dma->highmem direction, stopping
2747 * at the last zone which needs scanning.
2748 *
2749 * We do this because the page allocator works in the opposite
2750 * direction. This prevents the page allocator from allocating
2751 * pages behind kswapd's direction of progress, which would
2752 * cause too much scanning of the lower zones.
2753 */
2754 for (i = 0; i <= end_zone; i++) {
2755 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07002756 int nr_slab;
Mel Gorman8afdcec2011-03-22 16:33:04 -07002757 unsigned long balance_gap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002758
Con Kolivasf3fe6512006-01-06 00:11:15 -08002759 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760 continue;
2761
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002762 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763 continue;
2764
Linus Torvalds1da177e2005-04-16 15:20:36 -07002765 sc.nr_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002766
Ying Han0ae5e892011-05-26 16:25:25 -07002767 nr_soft_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002768 /*
2769 * Call soft limit reclaim before calling shrink_zone.
Balbir Singh4e416952009-09-23 15:56:39 -07002770 */
Ying Han0ae5e892011-05-26 16:25:25 -07002771 nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
2772 order, sc.gfp_mask,
2773 &nr_soft_scanned);
2774 sc.nr_reclaimed += nr_soft_reclaimed;
2775 total_scanned += nr_soft_scanned;
KOSAKI Motohiro00918b62010-08-10 18:03:05 -07002776
Rik van Riel32a43302007-10-16 01:24:50 -07002777 /*
Mel Gorman8afdcec2011-03-22 16:33:04 -07002778 * We put equal pressure on every zone, unless
2779 * one zone has way too many pages free
2780 * already. The "too many pages" is defined
2781 * as the high wmark plus a "gap" where the
2782 * gap is either the low watermark or 1%
2783 * of the zone, whichever is smaller.
Rik van Riel32a43302007-10-16 01:24:50 -07002784 */
Mel Gorman8afdcec2011-03-22 16:33:04 -07002785 balance_gap = min(low_wmark_pages(zone),
2786 (zone->present_pages +
2787 KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
2788 KSWAPD_ZONE_BALANCE_GAP_RATIO);
Mel Gorman88f5acf2011-01-13 15:45:41 -08002789 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman8afdcec2011-03-22 16:33:04 -07002790 high_wmark_pages(zone) + balance_gap,
Mel Gormand7868da2011-07-08 15:39:38 -07002791 end_zone, 0)) {
Rik van Riela79311c2009-01-06 14:40:01 -08002792 shrink_zone(priority, zone, &sc);
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002793
Mel Gormand7868da2011-07-08 15:39:38 -07002794 reclaim_state->reclaimed_slab = 0;
2795 nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
2796 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
2797 total_scanned += sc.nr_scanned;
2798
2799 if (nr_slab == 0 && !zone_reclaimable(zone))
2800 zone->all_unreclaimable = 1;
2801 }
2802
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803 /*
2804 * If we've done a decent amount of scanning and
2805 * the reclaim ratio is low, start doing writepage
2806 * even in laptop mode
2807 */
2808 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08002809 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002810 sc.may_writepage = 1;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002811
Mel Gorman215ddd62011-07-08 15:39:40 -07002812 if (zone->all_unreclaimable) {
2813 if (end_zone && end_zone == i)
2814 end_zone--;
Mel Gormand7868da2011-07-08 15:39:38 -07002815 continue;
Mel Gorman215ddd62011-07-08 15:39:40 -07002816 }
Mel Gormand7868da2011-07-08 15:39:38 -07002817
Mel Gorman88f5acf2011-01-13 15:45:41 -08002818 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002819 high_wmark_pages(zone), end_zone, 0)) {
2820 all_zones_ok = 0;
2821 /*
2822 * We are still under min water mark. This
2823 * means that we have a GFP_ATOMIC allocation
2824 * failure risk. Hurry up!
2825 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002826 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002827 min_wmark_pages(zone), end_zone, 0))
2828 has_under_min_watermark_zone = 1;
Mel Gorman0e093d992010-10-26 14:21:45 -07002829 } else {
2830 /*
2831 * If a zone reaches its high watermark,
2832 * consider it to be no longer congested. It's
2833 * possible there are dirty pages backed by
2834 * congested BDIs but as pressure is relieved,
2835 * spectulatively avoid congestion waits
2836 */
2837 zone_clear_flag(zone, ZONE_CONGESTED);
Mel Gormandc83edd2011-01-13 15:46:26 -08002838 if (i <= *classzone_idx)
Mel Gorman1741c872011-01-13 15:46:21 -08002839 balanced += zone->present_pages;
Minchan Kim45973d72010-03-05 13:41:45 -08002840 }
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002841
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842 }
Mel Gormandc83edd2011-01-13 15:46:26 -08002843 if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002844 break; /* kswapd: all done */
2845 /*
2846 * OK, kswapd is getting into trouble. Take a nap, then take
2847 * another pass across the zones.
2848 */
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002849 if (total_scanned && (priority < DEF_PRIORITY - 2)) {
2850 if (has_under_min_watermark_zone)
2851 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
2852 else
2853 congestion_wait(BLK_RW_ASYNC, HZ/10);
2854 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855
2856 /*
2857 * We do this so kswapd doesn't build up large priorities for
2858 * example when it is freeing in parallel with allocators. It
2859 * matches the direct reclaim path behaviour in terms of impact
2860 * on zone->*_priority.
2861 */
Rik van Riela79311c2009-01-06 14:40:01 -08002862 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863 break;
2864 }
2865out:
Mel Gorman99504742011-01-13 15:46:20 -08002866
2867 /*
2868 * order-0: All zones must meet high watermark for a balanced node
Mel Gorman1741c872011-01-13 15:46:21 -08002869 * high-order: Balanced zones must make up at least 25% of the node
2870 * for the node to be balanced
Mel Gorman99504742011-01-13 15:46:20 -08002871 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002872 if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002873 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08002874
2875 try_to_freeze();
2876
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08002877 /*
2878 * Fragmentation may mean that the system cannot be
2879 * rebalanced for high-order allocations in all zones.
2880 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
2881 * it means the zones have been fully scanned and are still
2882 * not balanced. For high-order allocations, there is
2883 * little point trying all over again as kswapd may
2884 * infinite loop.
2885 *
2886 * Instead, recheck all watermarks at order-0 as they
2887 * are the most important. If watermarks are ok, kswapd will go
2888 * back to sleep. High-order users can still perform direct
2889 * reclaim if they wish.
2890 */
2891 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
2892 order = sc.order = 0;
2893
Linus Torvalds1da177e2005-04-16 15:20:36 -07002894 goto loop_again;
2895 }
2896
Mel Gorman99504742011-01-13 15:46:20 -08002897 /*
2898 * If kswapd was reclaiming at a higher order, it has the option of
2899 * sleeping without all zones being balanced. Before it does, it must
2900 * ensure that the watermarks for order-0 on *all* zones are met and
2901 * that the congestion flags are cleared. The congestion flag must
2902 * be cleared as kswapd is the only mechanism that clears the flag
2903 * and it is potentially going to sleep here.
2904 */
2905 if (order) {
2906 for (i = 0; i <= end_zone; i++) {
2907 struct zone *zone = pgdat->node_zones + i;
2908
2909 if (!populated_zone(zone))
2910 continue;
2911
2912 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
2913 continue;
2914
2915 /* Confirm the zone is balanced for order-0 */
2916 if (!zone_watermark_ok(zone, 0,
2917 high_wmark_pages(zone), 0, 0)) {
2918 order = sc.order = 0;
2919 goto loop_again;
2920 }
2921
2922 /* If balanced, clear the congested flag */
2923 zone_clear_flag(zone, ZONE_CONGESTED);
Shaohua Li16fb9512011-10-31 17:08:02 -07002924 if (i <= *classzone_idx)
2925 balanced += zone->present_pages;
Mel Gorman99504742011-01-13 15:46:20 -08002926 }
2927 }
2928
Mel Gorman0abdee22011-01-13 15:46:22 -08002929 /*
2930 * Return the order we were reclaiming at so sleeping_prematurely()
2931 * makes a decision on the order we were last reclaiming at. However,
2932 * if another caller entered the allocator slow path while kswapd
2933 * was awake, order will remain at the higher level
2934 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002935 *classzone_idx = end_zone;
Mel Gorman0abdee22011-01-13 15:46:22 -08002936 return order;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002937}
2938
Mel Gormandc83edd2011-01-13 15:46:26 -08002939static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002940{
2941 long remaining = 0;
2942 DEFINE_WAIT(wait);
2943
2944 if (freezing(current) || kthread_should_stop())
2945 return;
2946
2947 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2948
2949 /* Try to sleep for a short interval */
Mel Gormandc83edd2011-01-13 15:46:26 -08002950 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002951 remaining = schedule_timeout(HZ/10);
2952 finish_wait(&pgdat->kswapd_wait, &wait);
2953 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2954 }
2955
2956 /*
2957 * After a short sleep, check if it was a premature sleep. If not, then
2958 * go fully to sleep until explicitly woken up.
2959 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002960 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002961 trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
2962
2963 /*
2964 * vmstat counters are not perfectly accurate and the estimated
2965 * value for counters such as NR_FREE_PAGES can deviate from the
2966 * true value by nr_online_cpus * threshold. To avoid the zone
2967 * watermarks being breached while under pressure, we reduce the
2968 * per-cpu vmstat threshold while kswapd is awake and restore
2969 * them before going back to sleep.
2970 */
2971 set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
2972 schedule();
2973 set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
2974 } else {
2975 if (remaining)
2976 count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
2977 else
2978 count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
2979 }
2980 finish_wait(&pgdat->kswapd_wait, &wait);
2981}
2982
Linus Torvalds1da177e2005-04-16 15:20:36 -07002983/*
2984 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002985 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002986 *
2987 * This basically trickles out pages so that we have _some_
2988 * free memory available even if there is no other activity
2989 * that frees anything up. This is needed for things like routing
2990 * etc, where we otherwise might have all activity going on in
2991 * asynchronous contexts that cannot page things out.
2992 *
2993 * If there are applications that are active memory-allocators
2994 * (most normal use), this basically shouldn't matter.
2995 */
2996static int kswapd(void *p)
2997{
Mel Gorman215ddd62011-07-08 15:39:40 -07002998 unsigned long order, new_order;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07002999 unsigned balanced_order;
Mel Gorman215ddd62011-07-08 15:39:40 -07003000 int classzone_idx, new_classzone_idx;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003001 int balanced_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003002 pg_data_t *pgdat = (pg_data_t*)p;
3003 struct task_struct *tsk = current;
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08003004
Linus Torvalds1da177e2005-04-16 15:20:36 -07003005 struct reclaim_state reclaim_state = {
3006 .reclaimed_slab = 0,
3007 };
Rusty Russella70f7302009-03-13 14:49:46 +10303008 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003009
Nick Piggincf40bd12009-01-21 08:12:39 +01003010 lockdep_set_current_reclaim_state(GFP_KERNEL);
3011
Rusty Russell174596a2009-01-01 10:12:29 +10303012 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07003013 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003014 current->reclaim_state = &reclaim_state;
3015
3016 /*
3017 * Tell the memory management that we're a "memory allocator",
3018 * and that if we need more memory we should get access to it
3019 * regardless (see "__alloc_pages()"). "kswapd" should
3020 * never get caught in the normal page freeing logic.
3021 *
3022 * (Kswapd normally doesn't need memory anyway, but sometimes
3023 * you need a small amount of memory in order to be able to
3024 * page out something else, and this flag essentially protects
3025 * us from recursively trying to free more memory as we're
3026 * trying to free the first piece of memory in the first place).
3027 */
Christoph Lameter930d9152006-01-08 01:00:47 -08003028 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07003029 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003030
Mel Gorman215ddd62011-07-08 15:39:40 -07003031 order = new_order = 0;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003032 balanced_order = 0;
Mel Gorman215ddd62011-07-08 15:39:40 -07003033 classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003034 balanced_classzone_idx = classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003035 for ( ; ; ) {
David Rientjes8fe23e02009-12-14 17:58:33 -08003036 int ret;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07003037
Mel Gorman215ddd62011-07-08 15:39:40 -07003038 /*
3039 * If the last balance_pgdat was unsuccessful it's unlikely a
3040 * new request of a similar or harder type will succeed soon
3041 * so consider going to sleep on the basis we reclaimed at
3042 */
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003043 if (balanced_classzone_idx >= new_classzone_idx &&
3044 balanced_order == new_order) {
Mel Gorman215ddd62011-07-08 15:39:40 -07003045 new_order = pgdat->kswapd_max_order;
3046 new_classzone_idx = pgdat->classzone_idx;
3047 pgdat->kswapd_max_order = 0;
3048 pgdat->classzone_idx = pgdat->nr_zones - 1;
3049 }
3050
Mel Gorman99504742011-01-13 15:46:20 -08003051 if (order < new_order || classzone_idx > new_classzone_idx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003052 /*
3053 * Don't sleep if someone wants a larger 'order'
Mel Gorman99504742011-01-13 15:46:20 -08003054 * allocation or has tigher zone constraints
Linus Torvalds1da177e2005-04-16 15:20:36 -07003055 */
3056 order = new_order;
Mel Gorman99504742011-01-13 15:46:20 -08003057 classzone_idx = new_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003058 } else {
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003059 kswapd_try_to_sleep(pgdat, balanced_order,
3060 balanced_classzone_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003061 order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08003062 classzone_idx = pgdat->classzone_idx;
Alex,Shif0dfcde2011-10-31 17:08:45 -07003063 new_order = order;
3064 new_classzone_idx = classzone_idx;
Mel Gorman4d405022011-01-13 15:46:23 -08003065 pgdat->kswapd_max_order = 0;
Mel Gorman215ddd62011-07-08 15:39:40 -07003066 pgdat->classzone_idx = pgdat->nr_zones - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003067 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003068
David Rientjes8fe23e02009-12-14 17:58:33 -08003069 ret = try_to_freeze();
3070 if (kthread_should_stop())
3071 break;
3072
3073 /*
3074 * We can speed up thawing tasks if we don't call balance_pgdat
3075 * after returning from the refrigerator
3076 */
Mel Gorman33906bc2010-08-09 17:19:16 -07003077 if (!ret) {
3078 trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003079 balanced_classzone_idx = classzone_idx;
3080 balanced_order = balance_pgdat(pgdat, order,
3081 &balanced_classzone_idx);
Mel Gorman33906bc2010-08-09 17:19:16 -07003082 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003083 }
3084 return 0;
3085}
3086
3087/*
3088 * A zone is low on free memory, so wake its kswapd task to service it.
3089 */
Mel Gorman99504742011-01-13 15:46:20 -08003090void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003091{
3092 pg_data_t *pgdat;
3093
Con Kolivasf3fe6512006-01-06 00:11:15 -08003094 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003095 return;
3096
Paul Jackson02a0e532006-12-13 00:34:25 -08003097 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003098 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08003099 pgdat = zone->zone_pgdat;
Mel Gorman99504742011-01-13 15:46:20 -08003100 if (pgdat->kswapd_max_order < order) {
Mel Gorman88f5acf2011-01-13 15:45:41 -08003101 pgdat->kswapd_max_order = order;
Mel Gorman99504742011-01-13 15:46:20 -08003102 pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
3103 }
Con Kolivas8d0986e2005-09-13 01:25:07 -07003104 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003105 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08003106 if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
3107 return;
3108
3109 trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
Con Kolivas8d0986e2005-09-13 01:25:07 -07003110 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003111}
3112
Wu Fengguangadea02a2009-09-21 17:01:42 -07003113/*
3114 * The reclaimable count would be mostly accurate.
3115 * The less reclaimable pages may be
3116 * - mlocked pages, which will be moved to unevictable list when encountered
3117 * - mapped pages, which may require several travels to be reclaimed
3118 * - dirty pages, which is not "instantly" reclaimable
3119 */
3120unsigned long global_reclaimable_pages(void)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07003121{
Wu Fengguangadea02a2009-09-21 17:01:42 -07003122 int nr;
3123
3124 nr = global_page_state(NR_ACTIVE_FILE) +
3125 global_page_state(NR_INACTIVE_FILE);
3126
3127 if (nr_swap_pages > 0)
3128 nr += global_page_state(NR_ACTIVE_ANON) +
3129 global_page_state(NR_INACTIVE_ANON);
3130
3131 return nr;
3132}
3133
3134unsigned long zone_reclaimable_pages(struct zone *zone)
3135{
3136 int nr;
3137
3138 nr = zone_page_state(zone, NR_ACTIVE_FILE) +
3139 zone_page_state(zone, NR_INACTIVE_FILE);
3140
3141 if (nr_swap_pages > 0)
3142 nr += zone_page_state(zone, NR_ACTIVE_ANON) +
3143 zone_page_state(zone, NR_INACTIVE_ANON);
3144
3145 return nr;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07003146}
3147
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02003148#ifdef CONFIG_HIBERNATION
Linus Torvalds1da177e2005-04-16 15:20:36 -07003149/*
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003150 * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003151 * freed pages.
3152 *
3153 * Rather than trying to age LRUs the aim is to preserve the overall
3154 * LRU order by reclaiming preferentially
3155 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07003156 */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003157unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003158{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003159 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003160 struct scan_control sc = {
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003161 .gfp_mask = GFP_HIGHUSER_MOVABLE,
3162 .may_swap = 1,
3163 .may_unmap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003164 .may_writepage = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003165 .nr_to_reclaim = nr_to_reclaim,
3166 .hibernation_mode = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003167 .order = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003168 };
Ying Hana09ed5e2011-05-24 17:12:26 -07003169 struct shrink_control shrink = {
3170 .gfp_mask = sc.gfp_mask,
3171 };
3172 struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003173 struct task_struct *p = current;
3174 unsigned long nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003175
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003176 p->flags |= PF_MEMALLOC;
3177 lockdep_set_current_reclaim_state(sc.gfp_mask);
3178 reclaim_state.reclaimed_slab = 0;
3179 p->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08003180
Ying Hana09ed5e2011-05-24 17:12:26 -07003181 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003182
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003183 p->reclaim_state = NULL;
3184 lockdep_clear_current_reclaim_state();
3185 p->flags &= ~PF_MEMALLOC;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003186
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003187 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003188}
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02003189#endif /* CONFIG_HIBERNATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003190
Linus Torvalds1da177e2005-04-16 15:20:36 -07003191/* It's optimal to keep kswapds on the same CPUs as their memory, but
3192 not required for correctness. So if the last cpu in a node goes
3193 away, we get changed to run anywhere: as the first one comes back,
3194 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07003195static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08003196 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003197{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07003198 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003199
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003200 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07003201 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07003202 pg_data_t *pgdat = NODE_DATA(nid);
Rusty Russella70f7302009-03-13 14:49:46 +10303203 const struct cpumask *mask;
3204
3205 mask = cpumask_of_node(pgdat->node_id);
Mike Travisc5f59f02008-04-04 18:11:10 -07003206
Rusty Russell3e597942009-01-01 10:12:24 +10303207 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003208 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07003209 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003210 }
3211 }
3212 return NOTIFY_OK;
3213}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003214
Yasunori Goto3218ae12006-06-27 02:53:33 -07003215/*
3216 * This kswapd start function will be called by init and node-hot-add.
3217 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
3218 */
3219int kswapd_run(int nid)
3220{
3221 pg_data_t *pgdat = NODE_DATA(nid);
3222 int ret = 0;
3223
3224 if (pgdat->kswapd)
3225 return 0;
3226
3227 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
3228 if (IS_ERR(pgdat->kswapd)) {
3229 /* failure at boot is fatal */
3230 BUG_ON(system_state == SYSTEM_BOOTING);
3231 printk("Failed to start kswapd on node %d\n",nid);
3232 ret = -1;
3233 }
3234 return ret;
3235}
3236
David Rientjes8fe23e02009-12-14 17:58:33 -08003237/*
3238 * Called by memory hotplug when all memory in a node is offlined.
3239 */
3240void kswapd_stop(int nid)
3241{
3242 struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
3243
3244 if (kswapd)
3245 kthread_stop(kswapd);
3246}
3247
Linus Torvalds1da177e2005-04-16 15:20:36 -07003248static int __init kswapd_init(void)
3249{
Yasunori Goto3218ae12006-06-27 02:53:33 -07003250 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08003251
Linus Torvalds1da177e2005-04-16 15:20:36 -07003252 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07003253 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07003254 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003255 hotcpu_notifier(cpu_callback, 0);
3256 return 0;
3257}
3258
3259module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08003260
3261#ifdef CONFIG_NUMA
3262/*
3263 * Zone reclaim mode
3264 *
3265 * If non-zero call zone_reclaim when the number of free pages falls below
3266 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08003267 */
3268int zone_reclaim_mode __read_mostly;
3269
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08003270#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07003271#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08003272#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
3273#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
3274
Christoph Lameter9eeff232006-01-18 17:42:31 -08003275/*
Christoph Lametera92f7122006-02-01 03:05:32 -08003276 * Priority for ZONE_RECLAIM. This determines the fraction of pages
3277 * of a node considered for each zone_reclaim. 4 scans 1/16th of
3278 * a zone.
3279 */
3280#define ZONE_RECLAIM_PRIORITY 4
3281
Christoph Lameter9eeff232006-01-18 17:42:31 -08003282/*
Christoph Lameter96146342006-07-03 00:24:13 -07003283 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
3284 * occur.
3285 */
3286int sysctl_min_unmapped_ratio = 1;
3287
3288/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003289 * If the number of slab pages in a zone grows beyond this percentage then
3290 * slab reclaim needs to occur.
3291 */
3292int sysctl_min_slab_ratio = 5;
3293
Mel Gorman90afa5d2009-06-16 15:33:20 -07003294static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
3295{
3296 unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
3297 unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
3298 zone_page_state(zone, NR_ACTIVE_FILE);
3299
3300 /*
3301 * It's possible for there to be more file mapped pages than
3302 * accounted for by the pages on the file LRU lists because
3303 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
3304 */
3305 return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
3306}
3307
3308/* Work out how many page cache pages we can reclaim in this reclaim_mode */
3309static long zone_pagecache_reclaimable(struct zone *zone)
3310{
3311 long nr_pagecache_reclaimable;
3312 long delta = 0;
3313
3314 /*
3315 * If RECLAIM_SWAP is set, then all file pages are considered
3316 * potentially reclaimable. Otherwise, we have to worry about
3317 * pages like swapcache and zone_unmapped_file_pages() provides
3318 * a better estimate
3319 */
3320 if (zone_reclaim_mode & RECLAIM_SWAP)
3321 nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
3322 else
3323 nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
3324
3325 /* If we can't clean pages, remove dirty pages from consideration */
3326 if (!(zone_reclaim_mode & RECLAIM_WRITE))
3327 delta += zone_page_state(zone, NR_FILE_DIRTY);
3328
3329 /* Watch for any possible underflows due to delta */
3330 if (unlikely(delta > nr_pagecache_reclaimable))
3331 delta = nr_pagecache_reclaimable;
3332
3333 return nr_pagecache_reclaimable - delta;
3334}
3335
Christoph Lameter0ff38492006-09-25 23:31:52 -07003336/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08003337 * Try to free up some pages from this zone through reclaim.
3338 */
Andrew Morton179e9632006-03-22 00:08:18 -08003339static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08003340{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08003341 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08003342 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003343 struct task_struct *p = current;
3344 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08003345 int priority;
Andrew Morton179e9632006-03-22 00:08:18 -08003346 struct scan_control sc = {
3347 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
Johannes Weinera6dc60f2009-03-31 15:19:30 -07003348 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07003349 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08003350 .nr_to_reclaim = max_t(unsigned long, nr_pages,
3351 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08003352 .gfp_mask = gfp_mask,
Johannes Weinerbd2f6192009-03-31 15:19:38 -07003353 .order = order,
Andrew Morton179e9632006-03-22 00:08:18 -08003354 };
Ying Hana09ed5e2011-05-24 17:12:26 -07003355 struct shrink_control shrink = {
3356 .gfp_mask = sc.gfp_mask,
3357 };
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003358 unsigned long nr_slab_pages0, nr_slab_pages1;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003359
Christoph Lameter9eeff232006-01-18 17:42:31 -08003360 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08003361 /*
3362 * We need to be able to allocate from the reserves for RECLAIM_SWAP
3363 * and we also need to be able to write out pages for RECLAIM_WRITE
3364 * and RECLAIM_SWAP.
3365 */
3366 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003367 lockdep_set_current_reclaim_state(gfp_mask);
Christoph Lameter9eeff232006-01-18 17:42:31 -08003368 reclaim_state.reclaimed_slab = 0;
3369 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08003370
Mel Gorman90afa5d2009-06-16 15:33:20 -07003371 if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
Christoph Lameter0ff38492006-09-25 23:31:52 -07003372 /*
3373 * Free memory by calling shrink zone with increasing
3374 * priorities until we have enough memory freed.
3375 */
3376 priority = ZONE_RECLAIM_PRIORITY;
3377 do {
Rik van Riela79311c2009-01-06 14:40:01 -08003378 shrink_zone(priority, zone, &sc);
Christoph Lameter0ff38492006-09-25 23:31:52 -07003379 priority--;
Rik van Riela79311c2009-01-06 14:40:01 -08003380 } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
Christoph Lameter0ff38492006-09-25 23:31:52 -07003381 }
Christoph Lameterc84db232006-02-01 03:05:29 -08003382
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003383 nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3384 if (nr_slab_pages0 > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003385 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08003386 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07003387 * many pages were freed in this zone. So we take the current
3388 * number of slab pages and shake the slab until it is reduced
3389 * by the same nr_pages that we used for reclaiming unmapped
3390 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003391 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07003392 * Note that shrink_slab will free memory on all zones and may
3393 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003394 */
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003395 for (;;) {
3396 unsigned long lru_pages = zone_reclaimable_pages(zone);
3397
3398 /* No reclaimable slab or very low memory pressure */
Ying Han1495f232011-05-24 17:12:27 -07003399 if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages))
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003400 break;
3401
3402 /* Freed enough memory */
3403 nr_slab_pages1 = zone_page_state(zone,
3404 NR_SLAB_RECLAIMABLE);
3405 if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
3406 break;
3407 }
Christoph Lameter83e33a42006-09-25 23:31:53 -07003408
3409 /*
3410 * Update nr_reclaimed by the number of slab pages we
3411 * reclaimed from this zone.
3412 */
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003413 nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3414 if (nr_slab_pages1 < nr_slab_pages0)
3415 sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003416 }
3417
Christoph Lameter9eeff232006-01-18 17:42:31 -08003418 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08003419 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003420 lockdep_clear_current_reclaim_state();
Rik van Riela79311c2009-01-06 14:40:01 -08003421 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003422}
Andrew Morton179e9632006-03-22 00:08:18 -08003423
3424int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
3425{
Andrew Morton179e9632006-03-22 00:08:18 -08003426 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07003427 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003428
3429 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003430 * Zone reclaim reclaims unmapped file backed pages and
3431 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07003432 *
Christoph Lameter96146342006-07-03 00:24:13 -07003433 * A small portion of unmapped file backed pages is needed for
3434 * file I/O otherwise pages read by file I/O will be immediately
3435 * thrown out if the zone is overallocated. So we do not reclaim
3436 * if less than a specified percentage of the zone is used by
3437 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08003438 */
Mel Gorman90afa5d2009-06-16 15:33:20 -07003439 if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
3440 zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003441 return ZONE_RECLAIM_FULL;
Andrew Morton179e9632006-03-22 00:08:18 -08003442
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08003443 if (zone->all_unreclaimable)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003444 return ZONE_RECLAIM_FULL;
David Rientjesd773ed62007-10-16 23:26:01 -07003445
Andrew Morton179e9632006-03-22 00:08:18 -08003446 /*
David Rientjesd773ed62007-10-16 23:26:01 -07003447 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08003448 */
David Rientjesd773ed62007-10-16 23:26:01 -07003449 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003450 return ZONE_RECLAIM_NOSCAN;
Andrew Morton179e9632006-03-22 00:08:18 -08003451
3452 /*
3453 * Only run zone reclaim on the local zone or on zones that do not
3454 * have associated processors. This will favor the local processor
3455 * over remote processors and spread off node memory allocations
3456 * as wide as possible.
3457 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07003458 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07003459 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Mel Gormanfa5e0842009-06-16 15:33:22 -07003460 return ZONE_RECLAIM_NOSCAN;
David Rientjesd773ed62007-10-16 23:26:01 -07003461
3462 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003463 return ZONE_RECLAIM_NOSCAN;
3464
David Rientjesd773ed62007-10-16 23:26:01 -07003465 ret = __zone_reclaim(zone, gfp_mask, order);
3466 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
3467
Mel Gorman24cf725182009-06-16 15:33:23 -07003468 if (!ret)
3469 count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
3470
David Rientjesd773ed62007-10-16 23:26:01 -07003471 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003472}
Christoph Lameter9eeff232006-01-18 17:42:31 -08003473#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003474
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003475/*
3476 * page_evictable - test whether a page is evictable
3477 * @page: the page to test
3478 * @vma: the VMA in which the page is or will be mapped, may be NULL
3479 *
3480 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07003481 * lists vs unevictable list. The vma argument is !NULL when called from the
3482 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003483 *
3484 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003485 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07003486 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003487 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003488 */
3489int page_evictable(struct page *page, struct vm_area_struct *vma)
3490{
3491
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003492 if (mapping_unevictable(page_mapping(page)))
3493 return 0;
3494
Nick Pigginb291f002008-10-18 20:26:44 -07003495 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
3496 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003497
3498 return 1;
3499}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003500
Hugh Dickins850465792012-01-20 14:34:19 -08003501#ifdef CONFIG_SHMEM
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003502/**
Hugh Dickins24513262012-01-20 14:34:21 -08003503 * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list
3504 * @pages: array of pages to check
3505 * @nr_pages: number of pages to check
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003506 *
Hugh Dickins24513262012-01-20 14:34:21 -08003507 * Checks pages for evictability and moves them to the appropriate lru list.
Hugh Dickins850465792012-01-20 14:34:19 -08003508 *
3509 * This function is only used for SysV IPC SHM_UNLOCK.
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003510 */
Hugh Dickins24513262012-01-20 14:34:21 -08003511void check_move_unevictable_pages(struct page **pages, int nr_pages)
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003512{
Johannes Weiner925b7672012-01-12 17:18:15 -08003513 struct lruvec *lruvec;
Hugh Dickins24513262012-01-20 14:34:21 -08003514 struct zone *zone = NULL;
3515 int pgscanned = 0;
3516 int pgrescued = 0;
3517 int i;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003518
Hugh Dickins24513262012-01-20 14:34:21 -08003519 for (i = 0; i < nr_pages; i++) {
3520 struct page *page = pages[i];
3521 struct zone *pagezone;
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003522
Hugh Dickins24513262012-01-20 14:34:21 -08003523 pgscanned++;
3524 pagezone = page_zone(page);
3525 if (pagezone != zone) {
3526 if (zone)
3527 spin_unlock_irq(&zone->lru_lock);
3528 zone = pagezone;
3529 spin_lock_irq(&zone->lru_lock);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003530 }
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003531
Hugh Dickins24513262012-01-20 14:34:21 -08003532 if (!PageLRU(page) || !PageUnevictable(page))
3533 continue;
3534
3535 if (page_evictable(page, NULL)) {
3536 enum lru_list lru = page_lru_base_type(page);
3537
3538 VM_BUG_ON(PageActive(page));
3539 ClearPageUnevictable(page);
3540 __dec_zone_state(zone, NR_UNEVICTABLE);
3541 lruvec = mem_cgroup_lru_move_lists(zone, page,
3542 LRU_UNEVICTABLE, lru);
3543 list_move(&page->lru, &lruvec->lists[lru]);
3544 __inc_zone_state(zone, NR_INACTIVE_ANON + lru);
3545 pgrescued++;
3546 }
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003547 }
Hugh Dickins24513262012-01-20 14:34:21 -08003548
3549 if (zone) {
3550 __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
3551 __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
3552 spin_unlock_irq(&zone->lru_lock);
3553 }
Hugh Dickins850465792012-01-20 14:34:19 -08003554}
3555#endif /* CONFIG_SHMEM */
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003556
Johannes Weiner264e56d2011-10-31 17:09:13 -07003557static void warn_scan_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003558{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003559 printk_once(KERN_WARNING
KOSAKI Motohiro25bd91b2012-01-10 15:07:40 -08003560 "%s: The scan_unevictable_pages sysctl/node-interface has been "
Johannes Weiner264e56d2011-10-31 17:09:13 -07003561 "disabled for lack of a legitimate use case. If you have "
KOSAKI Motohiro25bd91b2012-01-10 15:07:40 -08003562 "one, please send an email to linux-mm@kvack.org.\n",
3563 current->comm);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003564}
3565
3566/*
3567 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
3568 * all nodes' unevictable lists for evictable pages
3569 */
3570unsigned long scan_unevictable_pages;
3571
3572int scan_unevictable_handler(struct ctl_table *table, int write,
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003573 void __user *buffer,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003574 size_t *length, loff_t *ppos)
3575{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003576 warn_scan_unevictable_pages();
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003577 proc_doulongvec_minmax(table, write, buffer, length, ppos);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003578 scan_unevictable_pages = 0;
3579 return 0;
3580}
3581
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003582#ifdef CONFIG_NUMA
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003583/*
3584 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
3585 * a specified node's per zone unevictable lists for evictable pages.
3586 */
3587
Kay Sievers10fbcf42011-12-21 14:48:43 -08003588static ssize_t read_scan_unevictable_node(struct device *dev,
3589 struct device_attribute *attr,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003590 char *buf)
3591{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003592 warn_scan_unevictable_pages();
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003593 return sprintf(buf, "0\n"); /* always zero; should fit... */
3594}
3595
Kay Sievers10fbcf42011-12-21 14:48:43 -08003596static ssize_t write_scan_unevictable_node(struct device *dev,
3597 struct device_attribute *attr,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003598 const char *buf, size_t count)
3599{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003600 warn_scan_unevictable_pages();
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003601 return 1;
3602}
3603
3604
Kay Sievers10fbcf42011-12-21 14:48:43 -08003605static DEVICE_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003606 read_scan_unevictable_node,
3607 write_scan_unevictable_node);
3608
3609int scan_unevictable_register_node(struct node *node)
3610{
Kay Sievers10fbcf42011-12-21 14:48:43 -08003611 return device_create_file(&node->dev, &dev_attr_scan_unevictable_pages);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003612}
3613
3614void scan_unevictable_unregister_node(struct node *node)
3615{
Kay Sievers10fbcf42011-12-21 14:48:43 -08003616 device_remove_file(&node->dev, &dev_attr_scan_unevictable_pages);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003617}
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003618#endif