blob: 99999a9b2b0b333aeba513a1b606621928196586 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/vmscan.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
12 */
13
14#include <linux/mm.h>
15#include <linux/module.h>
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>
29#include <linux/pagevec.h>
30#include <linux/backing-dev.h>
31#include <linux/rmap.h>
32#include <linux/topology.h>
33#include <linux/cpu.h>
34#include <linux/cpuset.h>
Mel Gorman3e7d3442011-01-13 15:45:56 -080035#include <linux/compaction.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#include <linux/notifier.h>
37#include <linux/rwsem.h>
Rafael J. Wysocki248a0302006-03-22 00:09:04 -080038#include <linux/delay.h>
Yasunori Goto3218ae12006-06-27 02:53:33 -070039#include <linux/kthread.h>
Nigel Cunningham7dfb7102006-12-06 20:34:23 -080040#include <linux/freezer.h>
Balbir Singh66e17072008-02-07 00:13:56 -080041#include <linux/memcontrol.h>
Keika Kobayashi873b4772008-07-25 01:48:52 -070042#include <linux/delayacct.h>
Lee Schermerhornaf936a12008-10-18 20:26:53 -070043#include <linux/sysctl.h>
Andrea Arcangeli5a03b052011-01-13 15:47:11 -080044#include <linux/compaction.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 Weinera6dc60f82009-03-31 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
Rafael J. Wysockid6277db2006-06-23 02:03:18 -070097 int swappiness;
Nick Piggin408d8542006-09-25 23:31:27 -070098
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070099 int order;
Balbir Singh66e17072008-02-07 00:13:56 -0800100
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700101 /*
Nikanth Karthikesan415b54e2010-08-17 15:39:09 +0530102 * Intend to reclaim enough continuous memory rather than reclaim
103 * enough amount of memory. i.e, mode for high order allocation.
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700104 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800105 reclaim_mode_t reclaim_mode;
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700106
Balbir Singh66e17072008-02-07 00:13:56 -0800107 /* Which cgroup do we reclaim from */
108 struct mem_cgroup *mem_cgroup;
109
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700110 /*
111 * Nodemask of nodes allowed by the caller. If NULL, all nodes
112 * are scanned.
113 */
114 nodemask_t *nodemask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115};
116
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
118
119#ifdef ARCH_HAS_PREFETCH
120#define prefetch_prev_lru_page(_page, _base, _field) \
121 do { \
122 if ((_page)->lru.prev != _base) { \
123 struct page *prev; \
124 \
125 prev = lru_to_page(&(_page->lru)); \
126 prefetch(&prev->_field); \
127 } \
128 } while (0)
129#else
130#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
131#endif
132
133#ifdef ARCH_HAS_PREFETCHW
134#define prefetchw_prev_lru_page(_page, _base, _field) \
135 do { \
136 if ((_page)->lru.prev != _base) { \
137 struct page *prev; \
138 \
139 prev = lru_to_page(&(_page->lru)); \
140 prefetchw(&prev->_field); \
141 } \
142 } while (0)
143#else
144#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
145#endif
146
147/*
148 * From 0 .. 100. Higher means more swappy.
149 */
150int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700151long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
153static LIST_HEAD(shrinker_list);
154static DECLARE_RWSEM(shrinker_rwsem);
155
Balbir Singh00f0b822008-03-04 14:28:39 -0800156#ifdef CONFIG_CGROUP_MEM_RES_CTLR
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800157#define scanning_global_lru(sc) (!(sc)->mem_cgroup)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800158#else
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800159#define scanning_global_lru(sc) (1)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800160#endif
161
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800162static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
163 struct scan_control *sc)
164{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800165 if (!scanning_global_lru(sc))
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800166 return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone);
167
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800168 return &zone->reclaim_stat;
169}
170
Vincent Li0b217672009-09-21 17:03:09 -0700171static unsigned long zone_nr_lru_pages(struct zone *zone,
172 struct scan_control *sc, enum lru_list lru)
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800173{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800174 if (!scanning_global_lru(sc))
KOSAKI Motohiroa3d8e052009-01-07 18:08:19 -0800175 return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
176
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800177 return zone_page_state(zone, NR_LRU_BASE + lru);
178}
179
180
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181/*
182 * Add a shrinker callback to be called from the vm
183 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700184void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185{
Rusty Russell8e1f9362007-07-17 04:03:17 -0700186 shrinker->nr = 0;
187 down_write(&shrinker_rwsem);
188 list_add_tail(&shrinker->list, &shrinker_list);
189 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700191EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
193/*
194 * Remove one
195 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700196void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197{
198 down_write(&shrinker_rwsem);
199 list_del(&shrinker->list);
200 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700202EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
204#define SHRINK_BATCH 128
205/*
206 * Call the shrink functions to age shrinkable caches
207 *
208 * Here we assume it costs one seek to replace a lru page and that it also
209 * takes a seek to recreate a cache object. With this in mind we age equal
210 * percentages of the lru and ageable caches. This should balance the seeks
211 * generated by these structures.
212 *
Simon Arlott183ff222007-10-20 01:27:18 +0200213 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 * slab to avoid swapping.
215 *
216 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
217 *
218 * `lru_pages' represents the number of on-LRU pages in all the zones which
219 * are eligible for the caller's allocation attempt. It is used for balancing
220 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700221 *
222 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 */
Andrew Morton69e05942006-03-22 00:08:19 -0800224unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
225 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226{
227 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800228 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 if (scanned == 0)
231 scanned = SWAP_CLUSTER_MAX;
232
233 if (!down_read_trylock(&shrinker_rwsem))
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700234 return 1; /* Assume we'll be able to shrink next time */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
236 list_for_each_entry(shrinker, &shrinker_list, list) {
237 unsigned long long delta;
238 unsigned long total_scan;
Dave Chinner7f8275d2010-07-19 14:56:17 +1000239 unsigned long max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240
Dave Chinner7f8275d2010-07-19 14:56:17 +1000241 max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 delta = (4 * scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800243 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 do_div(delta, lru_pages + 1);
245 shrinker->nr += delta;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800246 if (shrinker->nr < 0) {
David Rientjes88c3bd72009-03-31 15:23:29 -0700247 printk(KERN_ERR "shrink_slab: %pF negative objects to "
248 "delete nr=%ld\n",
249 shrinker->shrink, shrinker->nr);
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800250 shrinker->nr = max_pass;
251 }
252
253 /*
254 * Avoid risking looping forever due to too large nr value:
255 * never try to free more than twice the estimate number of
256 * freeable entries.
257 */
258 if (shrinker->nr > max_pass * 2)
259 shrinker->nr = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260
261 total_scan = shrinker->nr;
262 shrinker->nr = 0;
263
264 while (total_scan >= SHRINK_BATCH) {
265 long this_scan = SHRINK_BATCH;
266 int shrink_ret;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700267 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268
Dave Chinner7f8275d2010-07-19 14:56:17 +1000269 nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
270 shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
271 gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 if (shrink_ret == -1)
273 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700274 if (shrink_ret < nr_before)
275 ret += nr_before - shrink_ret;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700276 count_vm_events(SLABS_SCANNED, this_scan);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 total_scan -= this_scan;
278
279 cond_resched();
280 }
281
282 shrinker->nr += total_scan;
283 }
284 up_read(&shrinker_rwsem);
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700285 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286}
287
Mel Gormanf3a310b2011-01-13 15:46:00 -0800288static void set_reclaim_mode(int priority, struct scan_control *sc,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700289 bool sync)
290{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800291 reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700292
293 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800294 * Initially assume we are entering either lumpy reclaim or
295 * reclaim/compaction.Depending on the order, we will either set the
296 * sync mode or just reclaim order-0 pages later.
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700297 */
Mel Gorman3e7d3442011-01-13 15:45:56 -0800298 if (COMPACTION_BUILD)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800299 sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
Mel Gorman3e7d3442011-01-13 15:45:56 -0800300 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800301 sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700302
303 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800304 * Avoid using lumpy reclaim or reclaim/compaction if possible by
305 * restricting when its set to either costly allocations or when
306 * under memory pressure
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700307 */
308 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800309 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700310 else if (sc->order && priority < DEF_PRIORITY - 2)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800311 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700312 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800313 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700314}
315
Mel Gormanf3a310b2011-01-13 15:46:00 -0800316static void reset_reclaim_mode(struct scan_control *sc)
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700317{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800318 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700319}
320
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321static inline int is_page_cache_freeable(struct page *page)
322{
Johannes Weinerceddc3a2009-09-21 17:03:00 -0700323 /*
324 * A freeable page cache page is referenced only by the caller
325 * that isolated the page, the page cache radix tree and
326 * optional buffer heads at page->private.
327 */
Johannes Weineredcf4742009-09-21 17:02:59 -0700328 return page_count(page) - page_has_private(page) == 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329}
330
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700331static int may_write_to_queue(struct backing_dev_info *bdi,
332 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
Christoph Lameter930d9152006-01-08 01:00:47 -0800334 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 return 1;
336 if (!bdi_write_congested(bdi))
337 return 1;
338 if (bdi == current->backing_dev_info)
339 return 1;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700340
341 /* lumpy reclaim for hugepage often need a lot of write */
342 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
343 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 return 0;
345}
346
347/*
348 * We detected a synchronous write error writing a page out. Probably
349 * -ENOSPC. We need to propagate that into the address_space for a subsequent
350 * fsync(), msync() or close().
351 *
352 * The tricky part is that after writepage we cannot touch the mapping: nothing
353 * prevents it from being freed up. But we have a ref on the page and once
354 * that page is locked, the mapping is pinned.
355 *
356 * We're allowed to run sleeping lock_page() here because we know the caller has
357 * __GFP_FS.
358 */
359static void handle_write_error(struct address_space *mapping,
360 struct page *page, int error)
361{
Nick Piggina6aa62a2010-07-20 13:24:25 -0700362 lock_page_nosync(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700363 if (page_mapping(page) == mapping)
364 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 unlock_page(page);
366}
367
Christoph Lameter04e62a22006-06-23 02:03:38 -0700368/* possible outcome of pageout() */
369typedef enum {
370 /* failed to write page out, page is locked */
371 PAGE_KEEP,
372 /* move page to the active list, page is locked */
373 PAGE_ACTIVATE,
374 /* page has been sent to the disk successfully, page is unlocked */
375 PAGE_SUCCESS,
376 /* page is clean and locked */
377 PAGE_CLEAN,
378} pageout_t;
379
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380/*
Andrew Morton1742f192006-03-22 00:08:21 -0800381 * pageout is called by shrink_page_list() for each dirty page.
382 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700384static pageout_t pageout(struct page *page, struct address_space *mapping,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700385 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386{
387 /*
388 * If the page is dirty, only perform writeback if that write
389 * will be non-blocking. To prevent this allocation from being
390 * stalled by pagecache activity. But note that there may be
391 * stalls if we need to run get_block(). We could test
392 * PagePrivate for that.
393 *
Vincent Li6aceb532009-12-14 17:58:49 -0800394 * If this process is currently in __generic_file_aio_write() against
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 * this page's queue, we can perform writeback even if that
396 * will block.
397 *
398 * If the page is swapcache, write it back even if that would
399 * block, for some throttling. This happens by accident, because
400 * swap_backing_dev_info is bust: it doesn't reflect the
401 * congestion state of the swapdevs. Easy to fix, if needed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 */
403 if (!is_page_cache_freeable(page))
404 return PAGE_KEEP;
405 if (!mapping) {
406 /*
407 * Some data journaling orphaned pages can have
408 * page->mapping == NULL while being dirty with clean buffers.
409 */
David Howells266cf652009-04-03 16:42:36 +0100410 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 if (try_to_free_buffers(page)) {
412 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700413 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 return PAGE_CLEAN;
415 }
416 }
417 return PAGE_KEEP;
418 }
419 if (mapping->a_ops->writepage == NULL)
420 return PAGE_ACTIVATE;
Mel Gorman0e093d992010-10-26 14:21:45 -0700421 if (!may_write_to_queue(mapping->backing_dev_info, sc))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 return PAGE_KEEP;
423
424 if (clear_page_dirty_for_io(page)) {
425 int res;
426 struct writeback_control wbc = {
427 .sync_mode = WB_SYNC_NONE,
428 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700429 .range_start = 0,
430 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 .for_reclaim = 1,
432 };
433
434 SetPageReclaim(page);
435 res = mapping->a_ops->writepage(page, &wbc);
436 if (res < 0)
437 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800438 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 ClearPageReclaim(page);
440 return PAGE_ACTIVATE;
441 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700442
443 /*
444 * Wait on writeback if requested to. This happens when
445 * direct reclaiming a large contiguous area and the
446 * first attempt to free a range of pages fails.
447 */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700448 if (PageWriteback(page) &&
Mel Gormanf3a310b2011-01-13 15:46:00 -0800449 (sc->reclaim_mode & RECLAIM_MODE_SYNC))
Andy Whitcroftc661b072007-08-22 14:01:26 -0700450 wait_on_page_writeback(page);
451
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 if (!PageWriteback(page)) {
453 /* synchronous write or broken a_ops? */
454 ClearPageReclaim(page);
455 }
Mel Gorman755f0222010-08-09 17:19:18 -0700456 trace_mm_vmscan_writepage(page,
Mel Gormanf3a310b2011-01-13 15:46:00 -0800457 trace_reclaim_flags(page, sc->reclaim_mode));
Andrew Mortone129b5c2006-09-27 01:50:00 -0700458 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 return PAGE_SUCCESS;
460 }
461
462 return PAGE_CLEAN;
463}
464
Andrew Mortona649fd92006-10-17 00:09:36 -0700465/*
Nick Piggine2867812008-07-25 19:45:30 -0700466 * Same as remove_mapping, but if the page is removed from the mapping, it
467 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700468 */
Nick Piggine2867812008-07-25 19:45:30 -0700469static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800470{
Nick Piggin28e4d962006-09-25 23:31:23 -0700471 BUG_ON(!PageLocked(page));
472 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800473
Nick Piggin19fd6232008-07-25 19:45:32 -0700474 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800475 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700476 * The non racy check for a busy page.
477 *
478 * Must be careful with the order of the tests. When someone has
479 * a ref to the page, it may be possible that they dirty it then
480 * drop the reference. So if PageDirty is tested before page_count
481 * here, then the following race may occur:
482 *
483 * get_user_pages(&page);
484 * [user mapping goes away]
485 * write_to(page);
486 * !PageDirty(page) [good]
487 * SetPageDirty(page);
488 * put_page(page);
489 * !page_count(page) [good, discard it]
490 *
491 * [oops, our write_to data is lost]
492 *
493 * Reversing the order of the tests ensures such a situation cannot
494 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
495 * load is not satisfied before that of page->_count.
496 *
497 * Note that if SetPageDirty is always performed via set_page_dirty,
498 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800499 */
Nick Piggine2867812008-07-25 19:45:30 -0700500 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800501 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700502 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
503 if (unlikely(PageDirty(page))) {
504 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800505 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700506 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800507
508 if (PageSwapCache(page)) {
509 swp_entry_t swap = { .val = page_private(page) };
510 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700511 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -0700512 swapcache_free(swap, page);
Nick Piggine2867812008-07-25 19:45:30 -0700513 } else {
Linus Torvalds6072d132010-12-01 13:35:19 -0500514 void (*freepage)(struct page *);
515
516 freepage = mapping->a_ops->freepage;
517
Nick Piggine2867812008-07-25 19:45:30 -0700518 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700519 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700520 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500521
522 if (freepage != NULL)
523 freepage(page);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800524 }
525
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800526 return 1;
527
528cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700529 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800530 return 0;
531}
532
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533/*
Nick Piggine2867812008-07-25 19:45:30 -0700534 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
535 * someone else has a ref on the page, abort and return 0. If it was
536 * successfully detached, return 1. Assumes the caller has a single ref on
537 * this page.
538 */
539int remove_mapping(struct address_space *mapping, struct page *page)
540{
541 if (__remove_mapping(mapping, page)) {
542 /*
543 * Unfreezing the refcount with 1 rather than 2 effectively
544 * drops the pagecache ref for us without requiring another
545 * atomic operation.
546 */
547 page_unfreeze_refs(page, 1);
548 return 1;
549 }
550 return 0;
551}
552
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700553/**
554 * putback_lru_page - put previously isolated page onto appropriate LRU list
555 * @page: page to be put back to appropriate lru list
556 *
557 * Add previously isolated @page to appropriate LRU list.
558 * Page may still be unevictable for other reasons.
559 *
560 * lru_lock must not be held, interrupts must be enabled.
561 */
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700562void putback_lru_page(struct page *page)
563{
564 int lru;
565 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700566 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700567
568 VM_BUG_ON(PageLRU(page));
569
570redo:
571 ClearPageUnevictable(page);
572
573 if (page_evictable(page, NULL)) {
574 /*
575 * For evictable pages, we can use the cache.
576 * In event of a race, worst case is we end up with an
577 * unevictable page on [in]active list.
578 * We know how to handle that.
579 */
Johannes Weiner401a8e12009-09-21 17:02:58 -0700580 lru = active + page_lru_base_type(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700581 lru_cache_add_lru(page, lru);
582 } else {
583 /*
584 * Put unevictable pages directly on zone's unevictable
585 * list.
586 */
587 lru = LRU_UNEVICTABLE;
588 add_page_to_unevictable_list(page);
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700589 /*
590 * When racing with an mlock clearing (page is
591 * unlocked), make sure that if the other thread does
592 * not observe our setting of PG_lru and fails
593 * isolation, we see PG_mlocked cleared below and move
594 * the page back to the evictable list.
595 *
596 * The other side is TestClearPageMlocked().
597 */
598 smp_mb();
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700599 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700600
601 /*
602 * page's status can change while we move it among lru. If an evictable
603 * page is on unevictable list, it never be freed. To avoid that,
604 * check after we added it to the list, again.
605 */
606 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
607 if (!isolate_lru_page(page)) {
608 put_page(page);
609 goto redo;
610 }
611 /* This means someone else dropped this page from LRU
612 * So, it will be freed or putback to LRU again. There is
613 * nothing to do here.
614 */
615 }
616
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700617 if (was_unevictable && lru != LRU_UNEVICTABLE)
618 count_vm_event(UNEVICTABLE_PGRESCUED);
619 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
620 count_vm_event(UNEVICTABLE_PGCULLED);
621
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700622 put_page(page); /* drop ref from isolate */
623}
624
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800625enum page_references {
626 PAGEREF_RECLAIM,
627 PAGEREF_RECLAIM_CLEAN,
Johannes Weiner645747462010-03-05 13:42:22 -0800628 PAGEREF_KEEP,
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800629 PAGEREF_ACTIVATE,
630};
631
632static enum page_references page_check_references(struct page *page,
633 struct scan_control *sc)
634{
Johannes Weiner645747462010-03-05 13:42:22 -0800635 int referenced_ptes, referenced_page;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800636 unsigned long vm_flags;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800637
Johannes Weiner645747462010-03-05 13:42:22 -0800638 referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags);
639 referenced_page = TestClearPageReferenced(page);
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800640
641 /* Lumpy reclaim - ignore references */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800642 if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800643 return PAGEREF_RECLAIM;
644
645 /*
646 * Mlock lost the isolation race with us. Let try_to_unmap()
647 * move the page to the unevictable list.
648 */
649 if (vm_flags & VM_LOCKED)
650 return PAGEREF_RECLAIM;
651
Johannes Weiner645747462010-03-05 13:42:22 -0800652 if (referenced_ptes) {
653 if (PageAnon(page))
654 return PAGEREF_ACTIVATE;
655 /*
656 * All mapped pages start out with page table
657 * references from the instantiating fault, so we need
658 * to look twice if a mapped file page is used more
659 * than once.
660 *
661 * Mark it and spare it for another trip around the
662 * inactive list. Another page table reference will
663 * lead to its activation.
664 *
665 * Note: the mark is set for activated pages as well
666 * so that recently deactivated but used pages are
667 * quickly recovered.
668 */
669 SetPageReferenced(page);
670
671 if (referenced_page)
672 return PAGEREF_ACTIVATE;
673
674 return PAGEREF_KEEP;
675 }
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800676
677 /* Reclaim if clean, defer dirty pages to writeback */
KOSAKI Motohiro2e302442010-10-26 14:21:46 -0700678 if (referenced_page && !PageSwapBacked(page))
Johannes Weiner645747462010-03-05 13:42:22 -0800679 return PAGEREF_RECLAIM_CLEAN;
680
681 return PAGEREF_RECLAIM;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800682}
683
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700684static noinline_for_stack void free_page_list(struct list_head *free_pages)
685{
686 struct pagevec freed_pvec;
687 struct page *page, *tmp;
688
689 pagevec_init(&freed_pvec, 1);
690
691 list_for_each_entry_safe(page, tmp, free_pages, lru) {
692 list_del(&page->lru);
693 if (!pagevec_add(&freed_pvec, page)) {
694 __pagevec_free(&freed_pvec);
695 pagevec_reinit(&freed_pvec);
696 }
697 }
698
699 pagevec_free(&freed_pvec);
700}
701
Nick Piggine2867812008-07-25 19:45:30 -0700702/*
Andrew Morton1742f192006-03-22 00:08:21 -0800703 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 */
Andrew Morton1742f192006-03-22 00:08:21 -0800705static unsigned long shrink_page_list(struct list_head *page_list,
Mel Gorman0e093d992010-10-26 14:21:45 -0700706 struct zone *zone,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700707 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708{
709 LIST_HEAD(ret_pages);
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700710 LIST_HEAD(free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 int pgactivate = 0;
Mel Gorman0e093d992010-10-26 14:21:45 -0700712 unsigned long nr_dirty = 0;
713 unsigned long nr_congested = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800714 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715
716 cond_resched();
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 while (!list_empty(page_list)) {
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800719 enum page_references references;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 struct address_space *mapping;
721 struct page *page;
722 int may_enter_fs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723
724 cond_resched();
725
726 page = lru_to_page(page_list);
727 list_del(&page->lru);
728
Nick Piggin529ae9a2008-08-02 12:01:03 +0200729 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 goto keep;
731
Nick Piggin725d7042006-09-25 23:30:55 -0700732 VM_BUG_ON(PageActive(page));
Mel Gorman0e093d992010-10-26 14:21:45 -0700733 VM_BUG_ON(page_zone(page) != zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734
735 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800736
Nick Pigginb291f002008-10-18 20:26:44 -0700737 if (unlikely(!page_evictable(page, NULL)))
738 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700739
Johannes Weinera6dc60f82009-03-31 15:19:30 -0700740 if (!sc->may_unmap && page_mapped(page))
Christoph Lameter80e43422006-02-11 17:55:53 -0800741 goto keep_locked;
742
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 /* Double the slab pressure for mapped and swapcache pages */
744 if (page_mapped(page) || PageSwapCache(page))
745 sc->nr_scanned++;
746
Andy Whitcroftc661b072007-08-22 14:01:26 -0700747 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
748 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
749
750 if (PageWriteback(page)) {
751 /*
752 * Synchronous reclaim is performed in two passes,
753 * first an asynchronous pass over the list to
754 * start parallel writeback, and a second synchronous
755 * pass to wait for the IO to complete. Wait here
756 * for any page for which writeback has already
757 * started.
758 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800759 if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700760 may_enter_fs)
Andy Whitcroftc661b072007-08-22 14:01:26 -0700761 wait_on_page_writeback(page);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700762 else {
763 unlock_page(page);
764 goto keep_lumpy;
765 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700766 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800768 references = page_check_references(page, sc);
769 switch (references) {
770 case PAGEREF_ACTIVATE:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 goto activate_locked;
Johannes Weiner645747462010-03-05 13:42:22 -0800772 case PAGEREF_KEEP:
773 goto keep_locked;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800774 case PAGEREF_RECLAIM:
775 case PAGEREF_RECLAIM_CLEAN:
776 ; /* try to reclaim the page below */
777 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 /*
780 * Anonymous process memory has backing store?
781 * Try to allocate it some swap space here.
782 */
Nick Pigginb291f002008-10-18 20:26:44 -0700783 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800784 if (!(sc->gfp_mask & __GFP_IO))
785 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800786 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800788 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700789 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
791 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792
793 /*
794 * The page is mapped into the page tables of one or more
795 * processes. Try to unmap it here.
796 */
797 if (page_mapped(page) && mapping) {
Andi Kleen14fa31b2009-09-16 11:50:10 +0200798 switch (try_to_unmap(page, TTU_UNMAP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 case SWAP_FAIL:
800 goto activate_locked;
801 case SWAP_AGAIN:
802 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700803 case SWAP_MLOCK:
804 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 case SWAP_SUCCESS:
806 ; /* try to free the page below */
807 }
808 }
809
810 if (PageDirty(page)) {
Mel Gorman0e093d992010-10-26 14:21:45 -0700811 nr_dirty++;
812
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800813 if (references == PAGEREF_RECLAIM_CLEAN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700815 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800817 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 goto keep_locked;
819
820 /* Page is dirty, try to write it out here */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700821 switch (pageout(page, mapping, sc)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 case PAGE_KEEP:
Mel Gorman0e093d992010-10-26 14:21:45 -0700823 nr_congested++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 goto keep_locked;
825 case PAGE_ACTIVATE:
826 goto activate_locked;
827 case PAGE_SUCCESS:
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700828 if (PageWriteback(page))
829 goto keep_lumpy;
830 if (PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 goto keep;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700832
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 /*
834 * A synchronous write - probably a ramdisk. Go
835 * ahead and try to reclaim the page.
836 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200837 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 goto keep;
839 if (PageDirty(page) || PageWriteback(page))
840 goto keep_locked;
841 mapping = page_mapping(page);
842 case PAGE_CLEAN:
843 ; /* try to free the page below */
844 }
845 }
846
847 /*
848 * If the page has buffers, try to free the buffer mappings
849 * associated with this page. If we succeed we try to free
850 * the page as well.
851 *
852 * We do this even if the page is PageDirty().
853 * try_to_release_page() does not perform I/O, but it is
854 * possible for a page to have PageDirty set, but it is actually
855 * clean (all its buffers are clean). This happens if the
856 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700857 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 * try_to_release_page() will discover that cleanness and will
859 * drop the buffers and mark the page clean - it can be freed.
860 *
861 * Rarely, pages can have buffers and no ->mapping. These are
862 * the pages which were not successfully invalidated in
863 * truncate_complete_page(). We try to drop those buffers here
864 * and if that worked, and the page is no longer mapped into
865 * process address space (page_count == 1) it can be freed.
866 * Otherwise, leave the page on the LRU so it is swappable.
867 */
David Howells266cf652009-04-03 16:42:36 +0100868 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 if (!try_to_release_page(page, sc->gfp_mask))
870 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700871 if (!mapping && page_count(page) == 1) {
872 unlock_page(page);
873 if (put_page_testzero(page))
874 goto free_it;
875 else {
876 /*
877 * rare race with speculative reference.
878 * the speculative reference will free
879 * this page shortly, so we may
880 * increment nr_reclaimed here (and
881 * leave it off the LRU).
882 */
883 nr_reclaimed++;
884 continue;
885 }
886 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 }
888
Nick Piggine2867812008-07-25 19:45:30 -0700889 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800890 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891
Nick Piggina978d6f2008-10-18 20:26:58 -0700892 /*
893 * At this point, we have no other references and there is
894 * no way to pick any more up (removed from LRU, removed
895 * from pagecache). Can use non-atomic bitops now (and
896 * we obviously don't have to worry about waking up a process
897 * waiting on the page lock, because there are no references.
898 */
899 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700900free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800901 nr_reclaimed++;
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700902
903 /*
904 * Is there need to periodically free_page_list? It would
905 * appear not as the counts should be low
906 */
907 list_add(&page->lru, &free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 continue;
909
Nick Pigginb291f002008-10-18 20:26:44 -0700910cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800911 if (PageSwapCache(page))
912 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700913 unlock_page(page);
914 putback_lru_page(page);
Mel Gormanf3a310b2011-01-13 15:46:00 -0800915 reset_reclaim_mode(sc);
Nick Pigginb291f002008-10-18 20:26:44 -0700916 continue;
917
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700919 /* Not a candidate for swapping, so reclaim swap space. */
920 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800921 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700922 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 SetPageActive(page);
924 pgactivate++;
925keep_locked:
926 unlock_page(page);
927keep:
Mel Gormanf3a310b2011-01-13 15:46:00 -0800928 reset_reclaim_mode(sc);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700929keep_lumpy:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700931 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 }
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700933
Mel Gorman0e093d992010-10-26 14:21:45 -0700934 /*
935 * Tag a zone as congested if all the dirty pages encountered were
936 * backed by a congested BDI. In this case, reclaimers should just
937 * back off and wait for congestion to clear because further reclaim
938 * will encounter the same problem
939 */
Shaohua Li1dce071e2010-11-11 14:05:17 -0800940 if (nr_dirty == nr_congested && nr_dirty != 0)
Mel Gorman0e093d992010-10-26 14:21:45 -0700941 zone_set_flag(zone, ZONE_CONGESTED);
942
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700943 free_page_list(&free_pages);
944
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 list_splice(&ret_pages, page_list);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700946 count_vm_events(PGACTIVATE, pgactivate);
Andrew Morton05ff5132006-03-22 00:08:20 -0800947 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948}
949
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700950/*
951 * Attempt to remove the specified page from its LRU. Only take this page
952 * if it is of the appropriate PageActive status. Pages which are being
953 * freed elsewhere are also ignored.
954 *
955 * page: page to consider
956 * mode: one of the LRU isolation modes defined above
957 *
958 * returns 0 on success, -ve errno on failure.
959 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700960int __isolate_lru_page(struct page *page, int mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700961{
962 int ret = -EINVAL;
963
964 /* Only take pages on the LRU. */
965 if (!PageLRU(page))
966 return ret;
967
968 /*
969 * When checking the active state, we need to be sure we are
970 * dealing with comparible boolean values. Take the logical not
971 * of each.
972 */
973 if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
974 return ret;
975
Johannes Weiner6c0b1352009-09-21 17:02:59 -0700976 if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700977 return ret;
978
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700979 /*
980 * When this function is being called for lumpy reclaim, we
981 * initially look into all LRU pages, active, inactive and
982 * unevictable; only give shrink_page_list evictable pages.
983 */
984 if (PageUnevictable(page))
985 return ret;
986
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700987 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800988
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700989 if (likely(get_page_unless_zero(page))) {
990 /*
991 * Be careful not to clear PageLRU until after we're
992 * sure the page is not being freed elsewhere -- the
993 * page release code relies on it.
994 */
995 ClearPageLRU(page);
996 ret = 0;
997 }
998
999 return ret;
1000}
1001
Christoph Lameter49d2e9c2006-01-08 01:00:48 -08001002/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 * zone->lru_lock is heavily contended. Some of the functions that
1004 * shrink the lists perform better by taking out a batch of pages
1005 * and working on them outside the LRU lock.
1006 *
1007 * For pagecache intensive workloads, this function is the hottest
1008 * spot in the kernel (apart from copy_*_user functions).
1009 *
1010 * Appropriate locks must be held before calling this function.
1011 *
1012 * @nr_to_scan: The number of pages to look through on the list.
1013 * @src: The LRU list to pull pages off.
1014 * @dst: The temp list to put pages on to.
1015 * @scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001016 * @order: The caller's attempted allocation order
1017 * @mode: One of the LRU isolation modes
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001018 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 *
1020 * returns how many pages were moved onto *@dst.
1021 */
Andrew Morton69e05942006-03-22 00:08:19 -08001022static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
1023 struct list_head *src, struct list_head *dst,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001024 unsigned long *scanned, int order, int mode, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025{
Andrew Morton69e05942006-03-22 00:08:19 -08001026 unsigned long nr_taken = 0;
Mel Gormana8a94d12010-08-09 17:19:17 -07001027 unsigned long nr_lumpy_taken = 0;
1028 unsigned long nr_lumpy_dirty = 0;
1029 unsigned long nr_lumpy_failed = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001030 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001032 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001033 struct page *page;
1034 unsigned long pfn;
1035 unsigned long end_pfn;
1036 unsigned long page_pfn;
1037 int zone_id;
1038
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 page = lru_to_page(src);
1040 prefetchw_prev_lru_page(page, src, flags);
1041
Nick Piggin725d7042006-09-25 23:30:55 -07001042 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001043
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001044 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001045 case 0:
1046 list_move(&page->lru, dst);
KAMEZAWA Hiroyuki2ffebca2009-06-17 16:27:21 -07001047 mem_cgroup_del_lru(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001048 nr_taken += hpage_nr_pages(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001049 break;
Nick Piggin46453a62006-03-22 00:07:58 -08001050
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001051 case -EBUSY:
1052 /* else it is being freed elsewhere */
1053 list_move(&page->lru, src);
KAMEZAWA Hiroyuki2ffebca2009-06-17 16:27:21 -07001054 mem_cgroup_rotate_lru_list(page, page_lru(page));
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001055 continue;
1056
1057 default:
1058 BUG();
1059 }
1060
1061 if (!order)
1062 continue;
1063
1064 /*
1065 * Attempt to take all pages in the order aligned region
1066 * surrounding the tag page. Only take those pages of
1067 * the same active state as that tag page. We may safely
1068 * round the target page pfn down to the requested order
1069 * as the mem_map is guarenteed valid out to MAX_ORDER,
1070 * where that page is in a different zone we will detect
1071 * it from its zone id and abort this block scan.
1072 */
1073 zone_id = page_zone_id(page);
1074 page_pfn = page_to_pfn(page);
1075 pfn = page_pfn & ~((1 << order) - 1);
1076 end_pfn = pfn + (1 << order);
1077 for (; pfn < end_pfn; pfn++) {
1078 struct page *cursor_page;
1079
1080 /* The target page is in the block, ignore it. */
1081 if (unlikely(pfn == page_pfn))
1082 continue;
1083
1084 /* Avoid holes within the zone. */
1085 if (unlikely(!pfn_valid_within(pfn)))
1086 break;
1087
1088 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001089
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001090 /* Check that we have not crossed a zone boundary. */
1091 if (unlikely(page_zone_id(cursor_page) != zone_id))
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001092 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001093
1094 /*
1095 * If we don't have enough swap space, reclaiming of
1096 * anon page which don't already have a swap slot is
1097 * pointless.
1098 */
1099 if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001100 !PageSwapCache(cursor_page))
1101 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001102
KAMEZAWA Hiroyukiee993b12009-06-16 15:33:24 -07001103 if (__isolate_lru_page(cursor_page, mode, file) == 0) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001104 list_move(&cursor_page->lru, dst);
KAMEZAWA Hiroyukicb4cbcf2009-06-23 08:57:55 +09001105 mem_cgroup_del_lru(cursor_page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001106 nr_taken += hpage_nr_pages(page);
Mel Gormana8a94d12010-08-09 17:19:17 -07001107 nr_lumpy_taken++;
1108 if (PageDirty(cursor_page))
1109 nr_lumpy_dirty++;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001110 scan++;
Mel Gormana8a94d12010-08-09 17:19:17 -07001111 } else {
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001112 /* the page is freed already. */
1113 if (!page_count(cursor_page))
1114 continue;
1115 break;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001116 }
1117 }
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001118
1119 /* If we break out of the loop above, lumpy reclaim failed */
1120 if (pfn < end_pfn)
1121 nr_lumpy_failed++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 }
1123
1124 *scanned = scan;
Mel Gormana8a94d12010-08-09 17:19:17 -07001125
1126 trace_mm_vmscan_lru_isolate(order,
1127 nr_to_scan, scan,
1128 nr_taken,
1129 nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed,
1130 mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 return nr_taken;
1132}
1133
Balbir Singh66e17072008-02-07 00:13:56 -08001134static unsigned long isolate_pages_global(unsigned long nr,
1135 struct list_head *dst,
1136 unsigned long *scanned, int order,
1137 int mode, struct zone *z,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001138 int active, int file)
Balbir Singh66e17072008-02-07 00:13:56 -08001139{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001140 int lru = LRU_BASE;
Balbir Singh66e17072008-02-07 00:13:56 -08001141 if (active)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001142 lru += LRU_ACTIVE;
1143 if (file)
1144 lru += LRU_FILE;
1145 return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001146 mode, file);
Balbir Singh66e17072008-02-07 00:13:56 -08001147}
1148
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149/*
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001150 * clear_active_flags() is a helper for shrink_active_list(), clearing
1151 * any active bits from the pages in the list.
1152 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001153static unsigned long clear_active_flags(struct list_head *page_list,
1154 unsigned int *count)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001155{
1156 int nr_active = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001157 int lru;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001158 struct page *page;
1159
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001160 list_for_each_entry(page, page_list, lru) {
Rik van Riel2c888cf2011-01-13 15:47:13 -08001161 int numpages = hpage_nr_pages(page);
Johannes Weiner401a8e12009-09-21 17:02:58 -07001162 lru = page_lru_base_type(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001163 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001164 lru += LRU_ACTIVE;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001165 ClearPageActive(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001166 nr_active += numpages;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001167 }
Mel Gorman1489fa12010-08-09 17:19:33 -07001168 if (count)
Rik van Riel2c888cf2011-01-13 15:47:13 -08001169 count[lru] += numpages;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001170 }
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001171
1172 return nr_active;
1173}
1174
Nick Piggin62695a82008-10-18 20:26:09 -07001175/**
1176 * isolate_lru_page - tries to isolate a page from its LRU list
1177 * @page: page to isolate from its LRU list
1178 *
1179 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1180 * vmstat statistic corresponding to whatever LRU list the page was on.
1181 *
1182 * Returns 0 if the page was removed from an LRU list.
1183 * Returns -EBUSY if the page was not on an LRU list.
1184 *
1185 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001186 * the active list, it will have PageActive set. If it was found on
1187 * the unevictable list, it will have the PageUnevictable bit set. That flag
1188 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001189 *
1190 * The vmstat statistic corresponding to the list on which the page was
1191 * found will be decremented.
1192 *
1193 * Restrictions:
1194 * (1) Must be called with an elevated refcount on the page. This is a
1195 * fundamentnal difference from isolate_lru_pages (which is called
1196 * without a stable reference).
1197 * (2) the lru_lock must not be held.
1198 * (3) interrupts must be enabled.
1199 */
1200int isolate_lru_page(struct page *page)
1201{
1202 int ret = -EBUSY;
1203
1204 if (PageLRU(page)) {
1205 struct zone *zone = page_zone(page);
1206
1207 spin_lock_irq(&zone->lru_lock);
1208 if (PageLRU(page) && get_page_unless_zero(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001209 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001210 ret = 0;
1211 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001212
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001213 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001214 }
1215 spin_unlock_irq(&zone->lru_lock);
1216 }
1217 return ret;
1218}
1219
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001220/*
Rik van Riel35cd7812009-09-21 17:01:38 -07001221 * Are there way too many processes in the direct reclaim path already?
1222 */
1223static int too_many_isolated(struct zone *zone, int file,
1224 struct scan_control *sc)
1225{
1226 unsigned long inactive, isolated;
1227
1228 if (current_is_kswapd())
1229 return 0;
1230
1231 if (!scanning_global_lru(sc))
1232 return 0;
1233
1234 if (file) {
1235 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1236 isolated = zone_page_state(zone, NR_ISOLATED_FILE);
1237 } else {
1238 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1239 isolated = zone_page_state(zone, NR_ISOLATED_ANON);
1240 }
1241
1242 return isolated > inactive;
1243}
1244
1245/*
Mel Gorman66635622010-08-09 17:19:30 -07001246 * TODO: Try merging with migrations version of putback_lru_pages
1247 */
1248static noinline_for_stack void
Mel Gorman1489fa12010-08-09 17:19:33 -07001249putback_lru_pages(struct zone *zone, struct scan_control *sc,
Mel Gorman66635622010-08-09 17:19:30 -07001250 unsigned long nr_anon, unsigned long nr_file,
1251 struct list_head *page_list)
1252{
1253 struct page *page;
1254 struct pagevec pvec;
Mel Gorman1489fa12010-08-09 17:19:33 -07001255 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Mel Gorman66635622010-08-09 17:19:30 -07001256
1257 pagevec_init(&pvec, 1);
1258
1259 /*
1260 * Put back any unfreeable pages.
1261 */
1262 spin_lock(&zone->lru_lock);
1263 while (!list_empty(page_list)) {
1264 int lru;
1265 page = lru_to_page(page_list);
1266 VM_BUG_ON(PageLRU(page));
1267 list_del(&page->lru);
1268 if (unlikely(!page_evictable(page, NULL))) {
1269 spin_unlock_irq(&zone->lru_lock);
1270 putback_lru_page(page);
1271 spin_lock_irq(&zone->lru_lock);
1272 continue;
1273 }
Mel Gorman66635622010-08-09 17:19:30 -07001274 lru = page_lru(page);
Mel Gorman66635622010-08-09 17:19:30 -07001275 if (is_active_lru(lru)) {
1276 int file = is_file_lru(lru);
Rik van Riel9992af12011-01-13 15:47:13 -08001277 int numpages = hpage_nr_pages(page);
1278 reclaim_stat->recent_rotated[file] += numpages;
Shaohua Li744ed1442011-01-13 15:47:34 -08001279 if (putback_active_lru_page(zone, page))
1280 continue;
Mel Gorman66635622010-08-09 17:19:30 -07001281 }
Shaohua Li744ed1442011-01-13 15:47:34 -08001282 SetPageLRU(page);
1283 add_page_to_lru_list(zone, page, lru);
Mel Gorman66635622010-08-09 17:19:30 -07001284 if (!pagevec_add(&pvec, page)) {
1285 spin_unlock_irq(&zone->lru_lock);
1286 __pagevec_release(&pvec);
1287 spin_lock_irq(&zone->lru_lock);
1288 }
1289 }
1290 __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
1291 __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
1292
1293 spin_unlock_irq(&zone->lru_lock);
1294 pagevec_release(&pvec);
1295}
1296
Mel Gorman1489fa12010-08-09 17:19:33 -07001297static noinline_for_stack void update_isolated_counts(struct zone *zone,
1298 struct scan_control *sc,
1299 unsigned long *nr_anon,
1300 unsigned long *nr_file,
1301 struct list_head *isolated_list)
1302{
1303 unsigned long nr_active;
1304 unsigned int count[NR_LRU_LISTS] = { 0, };
1305 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
1306
1307 nr_active = clear_active_flags(isolated_list, count);
1308 __count_vm_events(PGDEACTIVATE, nr_active);
1309
1310 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1311 -count[LRU_ACTIVE_FILE]);
1312 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1313 -count[LRU_INACTIVE_FILE]);
1314 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1315 -count[LRU_ACTIVE_ANON]);
1316 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1317 -count[LRU_INACTIVE_ANON]);
1318
1319 *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
1320 *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
1321 __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon);
1322 __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file);
1323
1324 reclaim_stat->recent_scanned[0] += *nr_anon;
1325 reclaim_stat->recent_scanned[1] += *nr_file;
1326}
1327
Mel Gorman66635622010-08-09 17:19:30 -07001328/*
Wu Fengguange31f36982010-08-09 17:20:01 -07001329 * Returns true if the caller should wait to clean dirty/writeback pages.
1330 *
1331 * If we are direct reclaiming for contiguous pages and we do not reclaim
1332 * everything in the list, try again and wait for writeback IO to complete.
1333 * This will stall high-order allocations noticeably. Only do that when really
1334 * need to free the pages under high memory pressure.
1335 */
1336static inline bool should_reclaim_stall(unsigned long nr_taken,
1337 unsigned long nr_freed,
1338 int priority,
1339 struct scan_control *sc)
1340{
1341 int lumpy_stall_priority;
1342
1343 /* kswapd should not stall on sync IO */
1344 if (current_is_kswapd())
1345 return false;
1346
1347 /* Only stall on lumpy reclaim */
Mel Gormanf3a310b2011-01-13 15:46:00 -08001348 if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
Wu Fengguange31f36982010-08-09 17:20:01 -07001349 return false;
1350
1351 /* If we have relaimed everything on the isolated list, no stall */
1352 if (nr_freed == nr_taken)
1353 return false;
1354
1355 /*
1356 * For high-order allocations, there are two stall thresholds.
1357 * High-cost allocations stall immediately where as lower
1358 * order allocations such as stacks require the scanning
1359 * priority to be much higher before stalling.
1360 */
1361 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1362 lumpy_stall_priority = DEF_PRIORITY;
1363 else
1364 lumpy_stall_priority = DEF_PRIORITY / 3;
1365
1366 return priority <= lumpy_stall_priority;
1367}
1368
1369/*
Andrew Morton1742f192006-03-22 00:08:21 -08001370 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1371 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 */
Mel Gorman66635622010-08-09 17:19:30 -07001373static noinline_for_stack unsigned long
1374shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
1375 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376{
1377 LIST_HEAD(page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001378 unsigned long nr_scanned;
Andrew Morton05ff5132006-03-22 00:08:20 -08001379 unsigned long nr_reclaimed = 0;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001380 unsigned long nr_taken;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001381 unsigned long nr_anon;
1382 unsigned long nr_file;
KOSAKI Motohiro78dc5832009-06-16 15:31:40 -07001383
Rik van Riel35cd7812009-09-21 17:01:38 -07001384 while (unlikely(too_many_isolated(zone, file, sc))) {
KOSAKI Motohiro58355c72009-10-26 16:49:35 -07001385 congestion_wait(BLK_RW_ASYNC, HZ/10);
Rik van Riel35cd7812009-09-21 17:01:38 -07001386
1387 /* We are about to die and free our memory. Return now. */
1388 if (fatal_signal_pending(current))
1389 return SWAP_CLUSTER_MAX;
1390 }
1391
Mel Gormanf3a310b2011-01-13 15:46:00 -08001392 set_reclaim_mode(priority, sc, false);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 lru_add_drain();
1394 spin_lock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001396 if (scanning_global_lru(sc)) {
1397 nr_taken = isolate_pages_global(nr_to_scan,
1398 &page_list, &nr_scanned, sc->order,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001399 sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
Mel Gorman3e7d3442011-01-13 15:45:56 -08001400 ISOLATE_BOTH : ISOLATE_INACTIVE,
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001401 zone, 0, file);
1402 zone->pages_scanned += nr_scanned;
KOSAKI Motohirob35ea172009-09-21 17:01:36 -07001403 if (current_is_kswapd())
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001404 __count_zone_vm_events(PGSCAN_KSWAPD, zone,
1405 nr_scanned);
1406 else
1407 __count_zone_vm_events(PGSCAN_DIRECT, zone,
1408 nr_scanned);
1409 } else {
1410 nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
1411 &page_list, &nr_scanned, sc->order,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001412 sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
Mel Gorman3e7d3442011-01-13 15:45:56 -08001413 ISOLATE_BOTH : ISOLATE_INACTIVE,
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001414 zone, sc->mem_cgroup,
1415 0, file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 /*
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001417 * mem_cgroup_isolate_pages() keeps track of
1418 * scanned pages on its own.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 */
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001420 }
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001421
Mel Gorman66635622010-08-09 17:19:30 -07001422 if (nr_taken == 0) {
1423 spin_unlock_irq(&zone->lru_lock);
1424 return 0;
1425 }
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001426
Mel Gorman1489fa12010-08-09 17:19:33 -07001427 update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001428
1429 spin_unlock_irq(&zone->lru_lock);
1430
Mel Gorman0e093d992010-10-26 14:21:45 -07001431 nr_reclaimed = shrink_page_list(&page_list, zone, sc);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001432
Wu Fengguange31f36982010-08-09 17:20:01 -07001433 /* Check if we should syncronously wait for writeback */
1434 if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
Mel Gormanf3a310b2011-01-13 15:46:00 -08001435 set_reclaim_mode(priority, sc, true);
Mel Gorman0e093d992010-10-26 14:21:45 -07001436 nr_reclaimed += shrink_page_list(&page_list, zone, sc);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001437 }
1438
1439 local_irq_disable();
1440 if (current_is_kswapd())
1441 __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
1442 __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
1443
Mel Gorman1489fa12010-08-09 17:19:33 -07001444 putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
Mel Gormane11da5b2010-10-26 14:21:40 -07001445
1446 trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
1447 zone_idx(zone),
1448 nr_scanned, nr_reclaimed,
1449 priority,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001450 trace_shrink_flags(file, sc->reclaim_mode));
Andrew Morton05ff5132006-03-22 00:08:20 -08001451 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452}
1453
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001454/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 * This moves pages from the active list to the inactive list.
1456 *
1457 * We move them the other way if the page is referenced by one or more
1458 * processes, from rmap.
1459 *
1460 * If the pages are mostly unmapped, the processing is fast and it is
1461 * appropriate to hold zone->lru_lock across the whole operation. But if
1462 * the pages are mapped, the processing is slow (page_referenced()) so we
1463 * should drop zone->lru_lock around each page. It's impossible to balance
1464 * this, so instead we remove the pages from the LRU while processing them.
1465 * It is safe to rely on PG_active against the non-LRU pages in here because
1466 * nobody will play with that bit on a non-LRU page.
1467 *
1468 * The downside is that we have to touch page->_count against each page.
1469 * But we had to alter page->flags anyway.
1470 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001471
Wu Fengguang3eb41402009-06-16 15:33:13 -07001472static void move_active_pages_to_lru(struct zone *zone,
1473 struct list_head *list,
1474 enum lru_list lru)
1475{
1476 unsigned long pgmoved = 0;
1477 struct pagevec pvec;
1478 struct page *page;
1479
1480 pagevec_init(&pvec, 1);
1481
1482 while (!list_empty(list)) {
1483 page = lru_to_page(list);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001484
1485 VM_BUG_ON(PageLRU(page));
1486 SetPageLRU(page);
1487
Wu Fengguang3eb41402009-06-16 15:33:13 -07001488 list_move(&page->lru, &zone->lru[lru].list);
1489 mem_cgroup_add_lru_list(page, lru);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001490 pgmoved += hpage_nr_pages(page);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001491
1492 if (!pagevec_add(&pvec, page) || list_empty(list)) {
1493 spin_unlock_irq(&zone->lru_lock);
1494 if (buffer_heads_over_limit)
1495 pagevec_strip(&pvec);
1496 __pagevec_release(&pvec);
1497 spin_lock_irq(&zone->lru_lock);
1498 }
1499 }
1500 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
1501 if (!is_active_lru(lru))
1502 __count_vm_events(PGDEACTIVATE, pgmoved);
1503}
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001504
Andrew Morton1742f192006-03-22 00:08:21 -08001505static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001506 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507{
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001508 unsigned long nr_taken;
Andrew Morton69e05942006-03-22 00:08:19 -08001509 unsigned long pgscanned;
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -07001510 unsigned long vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 LIST_HEAD(l_hold); /* The pages which were snipped off */
Wu Fengguang8cab4752009-06-16 15:33:12 -07001512 LIST_HEAD(l_active);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001513 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 struct page *page;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001515 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001516 unsigned long nr_rotated = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517
1518 lru_add_drain();
1519 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001520 if (scanning_global_lru(sc)) {
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001521 nr_taken = isolate_pages_global(nr_pages, &l_hold,
1522 &pgscanned, sc->order,
1523 ISOLATE_ACTIVE, zone,
1524 1, file);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001525 zone->pages_scanned += pgscanned;
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001526 } else {
1527 nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
1528 &pgscanned, sc->order,
1529 ISOLATE_ACTIVE, zone,
1530 sc->mem_cgroup, 1, file);
1531 /*
1532 * mem_cgroup_isolate_pages() keeps track of
1533 * scanned pages on its own.
1534 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001535 }
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001536
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001537 reclaim_stat->recent_scanned[file] += nr_taken;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001538
Wu Fengguang3eb41402009-06-16 15:33:13 -07001539 __count_zone_vm_events(PGREFILL, zone, pgscanned);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001540 if (file)
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001541 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001542 else
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001543 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001544 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 spin_unlock_irq(&zone->lru_lock);
1546
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 while (!list_empty(&l_hold)) {
1548 cond_resched();
1549 page = lru_to_page(&l_hold);
1550 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001551
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001552 if (unlikely(!page_evictable(page, NULL))) {
1553 putback_lru_page(page);
1554 continue;
1555 }
1556
Johannes Weiner645747462010-03-05 13:42:22 -08001557 if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
Rik van Riel9992af12011-01-13 15:47:13 -08001558 nr_rotated += hpage_nr_pages(page);
Wu Fengguang8cab4752009-06-16 15:33:12 -07001559 /*
1560 * Identify referenced, file-backed active pages and
1561 * give them one more trip around the active list. So
1562 * that executable code get better chances to stay in
1563 * memory under moderate memory pressure. Anon pages
1564 * are not likely to be evicted by use-once streaming
1565 * IO, plus JVM can create lots of anon VM_EXEC pages,
1566 * so we ignore them here.
1567 */
Wu Fengguang41e20982009-10-26 16:49:53 -07001568 if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
Wu Fengguang8cab4752009-06-16 15:33:12 -07001569 list_add(&page->lru, &l_active);
1570 continue;
1571 }
1572 }
Rik van Riel7e9cd482008-10-18 20:26:35 -07001573
KOSAKI Motohiro5205e562009-09-21 17:01:44 -07001574 ClearPageActive(page); /* we are de-activating */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575 list_add(&page->lru, &l_inactive);
1576 }
1577
Andrew Mortonb5557492009-01-06 14:40:13 -08001578 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001579 * Move pages back to the lru list.
Andrew Mortonb5557492009-01-06 14:40:13 -08001580 */
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001581 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001582 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001583 * Count referenced pages from currently used mappings as rotated,
1584 * even though only some of them are actually re-activated. This
1585 * helps balance scan pressure between file and anonymous pages in
1586 * get_scan_ratio.
Rik van Riel7e9cd482008-10-18 20:26:35 -07001587 */
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001588 reclaim_stat->recent_rotated[file] += nr_rotated;
Rik van Riel556adec2008-10-18 20:26:34 -07001589
Wu Fengguang3eb41402009-06-16 15:33:13 -07001590 move_active_pages_to_lru(zone, &l_active,
1591 LRU_ACTIVE + file * LRU_FILE);
1592 move_active_pages_to_lru(zone, &l_inactive,
1593 LRU_BASE + file * LRU_FILE);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001594 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001595 spin_unlock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596}
1597
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001598#ifdef CONFIG_SWAP
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001599static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001600{
1601 unsigned long active, inactive;
1602
1603 active = zone_page_state(zone, NR_ACTIVE_ANON);
1604 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1605
1606 if (inactive * zone->inactive_ratio < active)
1607 return 1;
1608
1609 return 0;
1610}
1611
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001612/**
1613 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1614 * @zone: zone to check
1615 * @sc: scan control of this context
1616 *
1617 * Returns true if the zone does not have enough inactive anon pages,
1618 * meaning some active anon pages need to be deactivated.
1619 */
1620static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc)
1621{
1622 int low;
1623
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001624 /*
1625 * If we don't have swap space, anonymous page deactivation
1626 * is pointless.
1627 */
1628 if (!total_swap_pages)
1629 return 0;
1630
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001631 if (scanning_global_lru(sc))
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001632 low = inactive_anon_is_low_global(zone);
1633 else
KOSAKI Motohiroc772be92009-01-07 18:08:25 -08001634 low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001635 return low;
1636}
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001637#else
1638static inline int inactive_anon_is_low(struct zone *zone,
1639 struct scan_control *sc)
1640{
1641 return 0;
1642}
1643#endif
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001644
Rik van Riel56e49d22009-06-16 15:32:28 -07001645static int inactive_file_is_low_global(struct zone *zone)
1646{
1647 unsigned long active, inactive;
1648
1649 active = zone_page_state(zone, NR_ACTIVE_FILE);
1650 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1651
1652 return (active > inactive);
1653}
1654
1655/**
1656 * inactive_file_is_low - check if file pages need to be deactivated
1657 * @zone: zone to check
1658 * @sc: scan control of this context
1659 *
1660 * When the system is doing streaming IO, memory pressure here
1661 * ensures that active file pages get deactivated, until more
1662 * than half of the file pages are on the inactive list.
1663 *
1664 * Once we get to that situation, protect the system's working
1665 * set from being evicted by disabling active file page aging.
1666 *
1667 * This uses a different ratio than the anonymous pages, because
1668 * the page cache uses a use-once replacement algorithm.
1669 */
1670static int inactive_file_is_low(struct zone *zone, struct scan_control *sc)
1671{
1672 int low;
1673
1674 if (scanning_global_lru(sc))
1675 low = inactive_file_is_low_global(zone);
1676 else
1677 low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup);
1678 return low;
1679}
1680
Rik van Rielb39415b2009-12-14 17:59:48 -08001681static int inactive_list_is_low(struct zone *zone, struct scan_control *sc,
1682 int file)
1683{
1684 if (file)
1685 return inactive_file_is_low(zone, sc);
1686 else
1687 return inactive_anon_is_low(zone, sc);
1688}
1689
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001690static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Christoph Lameterb69408e2008-10-18 20:26:14 -07001691 struct zone *zone, struct scan_control *sc, int priority)
1692{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001693 int file = is_file_lru(lru);
1694
Rik van Rielb39415b2009-12-14 17:59:48 -08001695 if (is_active_lru(lru)) {
1696 if (inactive_list_is_low(zone, sc, file))
1697 shrink_active_list(nr_to_scan, zone, sc, priority, file);
Rik van Riel556adec2008-10-18 20:26:34 -07001698 return 0;
1699 }
1700
Rik van Riel33c120e2008-10-18 20:26:36 -07001701 return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001702}
1703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704/*
Shaohua Li76a33fc2010-05-24 14:32:36 -07001705 * Smallish @nr_to_scan's are deposited in @nr_saved_scan,
1706 * until we collected @swap_cluster_max pages to scan.
1707 */
1708static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
1709 unsigned long *nr_saved_scan)
1710{
1711 unsigned long nr;
1712
1713 *nr_saved_scan += nr_to_scan;
1714 nr = *nr_saved_scan;
1715
1716 if (nr >= SWAP_CLUSTER_MAX)
1717 *nr_saved_scan = 0;
1718 else
1719 nr = 0;
1720
1721 return nr;
1722}
1723
1724/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001725 * Determine how aggressively the anon and file LRU lists should be
1726 * scanned. The relative value of each set of LRU lists is determined
1727 * by looking at the fraction of the pages scanned we did rotate back
1728 * onto the active list instead of evict.
1729 *
Shaohua Li76a33fc2010-05-24 14:32:36 -07001730 * nr[0] = anon pages to scan; nr[1] = file pages to scan
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001731 */
Shaohua Li76a33fc2010-05-24 14:32:36 -07001732static void get_scan_count(struct zone *zone, struct scan_control *sc,
1733 unsigned long *nr, int priority)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001734{
1735 unsigned long anon, file, free;
1736 unsigned long anon_prio, file_prio;
1737 unsigned long ap, fp;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001738 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Shaohua Li76a33fc2010-05-24 14:32:36 -07001739 u64 fraction[2], denominator;
1740 enum lru_list l;
1741 int noswap = 0;
1742
1743 /* If we have no swap space, do not bother scanning anon pages. */
1744 if (!sc->may_swap || (nr_swap_pages <= 0)) {
1745 noswap = 1;
1746 fraction[0] = 0;
1747 fraction[1] = 1;
1748 denominator = 1;
1749 goto out;
1750 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001751
Vincent Li0b217672009-09-21 17:03:09 -07001752 anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +
1753 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON);
1754 file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +
1755 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
Hugh Dickinsb9627162009-01-06 14:39:41 -08001756
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001757 if (scanning_global_lru(sc)) {
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001758 free = zone_page_state(zone, NR_FREE_PAGES);
1759 /* If we have very few page cache pages,
1760 force-scan anon pages. */
Mel Gorman41858962009-06-16 15:32:12 -07001761 if (unlikely(file + free <= high_wmark_pages(zone))) {
Shaohua Li76a33fc2010-05-24 14:32:36 -07001762 fraction[0] = 1;
1763 fraction[1] = 0;
1764 denominator = 1;
1765 goto out;
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001766 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001767 }
1768
1769 /*
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001770 * With swappiness at 100, anonymous and file have the same priority.
1771 * This scanning priority is essentially the inverse of IO cost.
1772 */
1773 anon_prio = sc->swappiness;
1774 file_prio = 200 - sc->swappiness;
1775
1776 /*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001777 * OK, so we have swap space and a fair amount of page cache
1778 * pages. We use the recently rotated / recently scanned
1779 * ratios to determine how valuable each cache is.
1780 *
1781 * Because workloads change over time (and to avoid overflow)
1782 * we keep these statistics as a floating average, which ends
1783 * up weighing recent references more than old ones.
1784 *
1785 * anon in [0], file in [1]
1786 */
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001787 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001788 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001789 reclaim_stat->recent_scanned[0] /= 2;
1790 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001791 }
1792
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001793 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001794 reclaim_stat->recent_scanned[1] /= 2;
1795 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001796 }
1797
1798 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001799 * The amount of pressure on anon vs file pages is inversely
1800 * proportional to the fraction of recently scanned pages on
1801 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001802 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001803 ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
1804 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001805
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001806 fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
1807 fp /= reclaim_stat->recent_rotated[1] + 1;
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001808 spin_unlock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001809
Shaohua Li76a33fc2010-05-24 14:32:36 -07001810 fraction[0] = ap;
1811 fraction[1] = fp;
1812 denominator = ap + fp + 1;
1813out:
1814 for_each_evictable_lru(l) {
1815 int file = is_file_lru(l);
1816 unsigned long scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001817
Shaohua Li76a33fc2010-05-24 14:32:36 -07001818 scan = zone_nr_lru_pages(zone, sc, l);
1819 if (priority || noswap) {
1820 scan >>= priority;
1821 scan = div64_u64(scan * fraction[file], denominator);
1822 }
1823 nr[l] = nr_scan_try_batch(scan,
1824 &reclaim_stat->nr_saved_scan[l]);
1825 }
Wu Fengguang6e08a362009-06-16 15:32:29 -07001826}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001827
1828/*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001829 * Reclaim/compaction depends on a number of pages being freed. To avoid
1830 * disruption to the system, a small number of order-0 pages continue to be
1831 * rotated and reclaimed in the normal fashion. However, by the time we get
1832 * back to the allocator and call try_to_compact_zone(), we ensure that
1833 * there are enough free pages for it to be likely successful
1834 */
1835static inline bool should_continue_reclaim(struct zone *zone,
1836 unsigned long nr_reclaimed,
1837 unsigned long nr_scanned,
1838 struct scan_control *sc)
1839{
1840 unsigned long pages_for_compaction;
1841 unsigned long inactive_lru_pages;
1842
1843 /* If not in reclaim/compaction mode, stop */
Mel Gormanf3a310b2011-01-13 15:46:00 -08001844 if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001845 return false;
1846
1847 /*
1848 * If we failed to reclaim and have scanned the full list, stop.
1849 * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far
1850 * faster but obviously would be less likely to succeed
1851 * allocation. If this is desirable, use GFP_REPEAT to decide
1852 * if both reclaimed and scanned should be checked or just
1853 * reclaimed
1854 */
1855 if (!nr_reclaimed && !nr_scanned)
1856 return false;
1857
1858 /*
1859 * If we have not reclaimed enough pages for compaction and the
1860 * inactive lists are large enough, continue reclaiming
1861 */
1862 pages_for_compaction = (2UL << sc->order);
1863 inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) +
1864 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
1865 if (sc->nr_reclaimed < pages_for_compaction &&
1866 inactive_lru_pages > pages_for_compaction)
1867 return true;
1868
1869 /* If compaction would go ahead or the allocation would succeed, stop */
1870 switch (compaction_suitable(zone, sc->order)) {
1871 case COMPACT_PARTIAL:
1872 case COMPACT_CONTINUE:
1873 return false;
1874 default:
1875 return true;
1876 }
1877}
1878
1879/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1881 */
Rik van Riela79311c2009-01-06 14:40:01 -08001882static void shrink_zone(int priority, struct zone *zone,
Andrew Morton05ff5132006-03-22 00:08:20 -08001883 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884{
Christoph Lameterb69408e2008-10-18 20:26:14 -07001885 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08001886 unsigned long nr_to_scan;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001887 enum lru_list l;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001888 unsigned long nr_reclaimed;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08001889 unsigned long nr_to_reclaim = sc->nr_to_reclaim;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001890 unsigned long nr_scanned = sc->nr_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891
Mel Gorman3e7d3442011-01-13 15:45:56 -08001892restart:
1893 nr_reclaimed = 0;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001894 get_scan_count(zone, sc, nr, priority);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001895
Rik van Riel556adec2008-10-18 20:26:34 -07001896 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1897 nr[LRU_INACTIVE_FILE]) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001898 for_each_evictable_lru(l) {
Christoph Lameterb69408e2008-10-18 20:26:14 -07001899 if (nr[l]) {
KOSAKI Motohiroece74b22009-12-14 17:59:14 -08001900 nr_to_scan = min_t(unsigned long,
1901 nr[l], SWAP_CLUSTER_MAX);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001902 nr[l] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001904 nr_reclaimed += shrink_list(l, nr_to_scan,
1905 zone, sc, priority);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001906 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 }
Rik van Riela79311c2009-01-06 14:40:01 -08001908 /*
1909 * On large memory systems, scan >> priority can become
1910 * really large. This is fine for the starting priority;
1911 * we want to put equal scanning pressure on each zone.
1912 * However, if the VM has a harder time of freeing pages,
1913 * with multiple processes reclaiming pages, the total
1914 * freeing target can get unreasonably large.
1915 */
KOSAKI Motohiro338fde92009-12-14 17:59:15 -08001916 if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
Rik van Riela79311c2009-01-06 14:40:01 -08001917 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 }
Mel Gorman3e7d3442011-01-13 15:45:56 -08001919 sc->nr_reclaimed += nr_reclaimed;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001920
Rik van Riel556adec2008-10-18 20:26:34 -07001921 /*
1922 * Even if we did not try to evict anon pages at all, we want to
1923 * rebalance the anon lru active/inactive ratio.
1924 */
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001925 if (inactive_anon_is_low(zone, sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001926 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1927
Mel Gorman3e7d3442011-01-13 15:45:56 -08001928 /* reclaim/compaction might need reclaim to continue */
1929 if (should_continue_reclaim(zone, nr_reclaimed,
1930 sc->nr_scanned - nr_scanned, sc))
1931 goto restart;
1932
Andrew Morton232ea4d2007-02-28 20:13:21 -08001933 throttle_vm_writeout(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934}
1935
1936/*
1937 * This is the direct reclaim path, for page-allocating processes. We only
1938 * try to reclaim pages from zones which will satisfy the caller's allocation
1939 * request.
1940 *
Mel Gorman41858962009-06-16 15:32:12 -07001941 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
1942 * Because:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
1944 * allocation or
Mel Gorman41858962009-06-16 15:32:12 -07001945 * b) The target zone may be at high_wmark_pages(zone) but the lower zones
1946 * must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
1947 * zone defense algorithm.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949 * If a zone is deemed to be full of pinned pages then just give it a light
1950 * scan then give up on it.
1951 */
Minchan Kimd1908362010-09-22 13:05:01 -07001952static void shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08001953 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954{
Mel Gormandd1a2392008-04-28 02:12:17 -07001955 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001956 struct zone *zone;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001957
Mel Gormand4debc62010-08-09 17:19:29 -07001958 for_each_zone_zonelist_nodemask(zone, z, zonelist,
1959 gfp_zone(sc->gfp_mask), sc->nodemask) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08001960 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001962 /*
1963 * Take care memory controller reclaiming has small influence
1964 * to global LRU.
1965 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001966 if (scanning_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001967 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1968 continue;
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08001969 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001970 continue; /* Let kswapd poll it */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001971 }
Nick Piggin408d8542006-09-25 23:31:27 -07001972
Rik van Riela79311c2009-01-06 14:40:01 -08001973 shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974 }
Minchan Kimd1908362010-09-22 13:05:01 -07001975}
1976
1977static bool zone_reclaimable(struct zone *zone)
1978{
1979 return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
1980}
1981
1982/*
1983 * As hibernation is going on, kswapd is freezed so that it can't mark
1984 * the zone into all_unreclaimable. It can't handle OOM during hibernation.
1985 * So let's check zone's unreclaimable in direct reclaim as well as kswapd.
1986 */
1987static bool all_unreclaimable(struct zonelist *zonelist,
1988 struct scan_control *sc)
1989{
1990 struct zoneref *z;
1991 struct zone *zone;
1992 bool all_unreclaimable = true;
1993
1994 for_each_zone_zonelist_nodemask(zone, z, zonelist,
1995 gfp_zone(sc->gfp_mask), sc->nodemask) {
1996 if (!populated_zone(zone))
1997 continue;
1998 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1999 continue;
2000 if (zone_reclaimable(zone)) {
2001 all_unreclaimable = false;
2002 break;
2003 }
2004 }
2005
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002006 return all_unreclaimable;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002008
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009/*
2010 * This is the main entry point to direct page reclaim.
2011 *
2012 * If a full scan of the inactive list fails to free enough memory then we
2013 * are "out of memory" and something needs to be killed.
2014 *
2015 * If the caller is !__GFP_FS then the probability of a failure is reasonably
2016 * high - the zone may be full of dirty or under-writeback pages, which this
Jens Axboe5b0830c2009-09-23 19:37:09 +02002017 * caller can't do much about. We kick the writeback threads and take explicit
2018 * naps in the hope that some of these pages can be written. But if the
2019 * allocating task holds filesystem locks which prevent writeout this might not
2020 * work, and the allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07002021 *
2022 * returns: 0, if no pages reclaimed
2023 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 */
Mel Gormandac1d272008-04-28 02:12:12 -07002025static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Mel Gormandd1a2392008-04-28 02:12:17 -07002026 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027{
2028 int priority;
Andrew Morton69e05942006-03-22 00:08:19 -08002029 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 struct reclaim_state *reclaim_state = current->reclaim_state;
Mel Gormandd1a2392008-04-28 02:12:17 -07002031 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002032 struct zone *zone;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002033 unsigned long writeback_threshold;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002034
Miao Xiec0ff7452010-05-24 14:32:08 -07002035 get_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002036 delayacct_freepages_start();
2037
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08002038 if (scanning_global_lru(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002039 count_vm_event(ALLOCSTALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040
2041 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08002042 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002043 if (!priority)
2044 disable_swap_token();
Minchan Kimd1908362010-09-22 13:05:01 -07002045 shrink_zones(priority, zonelist, sc);
Balbir Singh66e17072008-02-07 00:13:56 -08002046 /*
2047 * Don't shrink slabs when reclaiming memory from
2048 * over limit cgroups
2049 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08002050 if (scanning_global_lru(sc)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002051 unsigned long lru_pages = 0;
Mel Gormand4debc62010-08-09 17:19:29 -07002052 for_each_zone_zonelist(zone, z, zonelist,
2053 gfp_zone(sc->gfp_mask)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002054 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2055 continue;
2056
2057 lru_pages += zone_reclaimable_pages(zone);
2058 }
2059
Mel Gormandd1a2392008-04-28 02:12:17 -07002060 shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002061 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08002062 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002063 reclaim_state->reclaimed_slab = 0;
2064 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 }
Balbir Singh66e17072008-02-07 00:13:56 -08002066 total_scanned += sc->nr_scanned;
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002067 if (sc->nr_reclaimed >= sc->nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069
2070 /*
2071 * Try to write back as many pages as we just scanned. This
2072 * tends to cause slow streaming writers to write data to the
2073 * disk smoothly, at the dirtying rate, which is nice. But
2074 * that's undesirable in laptop mode, where we *want* lumpy
2075 * writeout. So in laptop mode, write out the whole world.
2076 */
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002077 writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
2078 if (total_scanned > writeback_threshold) {
Jens Axboe03ba3782009-09-09 09:08:54 +02002079 wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
Balbir Singh66e17072008-02-07 00:13:56 -08002080 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 }
2082
2083 /* Take a nap, wait for some writeback to complete */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002084 if (!sc->hibernation_mode && sc->nr_scanned &&
Mel Gorman0e093d992010-10-26 14:21:45 -07002085 priority < DEF_PRIORITY - 2) {
2086 struct zone *preferred_zone;
2087
2088 first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
2089 NULL, &preferred_zone);
2090 wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
2091 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 }
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002093
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094out:
Keika Kobayashi873b4772008-07-25 01:48:52 -07002095 delayacct_freepages_end();
Miao Xiec0ff7452010-05-24 14:32:08 -07002096 put_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002097
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002098 if (sc->nr_reclaimed)
2099 return sc->nr_reclaimed;
2100
2101 /* top priority shrink_zones still had more to do? don't OOM, then */
Minchan Kimd1908362010-09-22 13:05:01 -07002102 if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002103 return 1;
2104
2105 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106}
2107
Mel Gormandac1d272008-04-28 02:12:12 -07002108unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002109 gfp_t gfp_mask, nodemask_t *nodemask)
Balbir Singh66e17072008-02-07 00:13:56 -08002110{
Mel Gorman33906bc2010-08-09 17:19:16 -07002111 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002112 struct scan_control sc = {
2113 .gfp_mask = gfp_mask,
2114 .may_writepage = !laptop_mode,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002115 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002116 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002117 .may_swap = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08002118 .swappiness = vm_swappiness,
2119 .order = order,
2120 .mem_cgroup = NULL,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002121 .nodemask = nodemask,
Balbir Singh66e17072008-02-07 00:13:56 -08002122 };
2123
Mel Gorman33906bc2010-08-09 17:19:16 -07002124 trace_mm_vmscan_direct_reclaim_begin(order,
2125 sc.may_writepage,
2126 gfp_mask);
2127
2128 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
2129
2130 trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
2131
2132 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002133}
2134
Balbir Singh00f0b822008-03-04 14:28:39 -08002135#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08002136
Balbir Singh4e416952009-09-23 15:56:39 -07002137unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
2138 gfp_t gfp_mask, bool noswap,
2139 unsigned int swappiness,
KOSAKI Motohiro14fec792010-08-10 18:03:05 -07002140 struct zone *zone)
Balbir Singh4e416952009-09-23 15:56:39 -07002141{
2142 struct scan_control sc = {
KOSAKI Motohirob8f5c562010-08-10 18:03:02 -07002143 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh4e416952009-09-23 15:56:39 -07002144 .may_writepage = !laptop_mode,
2145 .may_unmap = 1,
2146 .may_swap = !noswap,
Balbir Singh4e416952009-09-23 15:56:39 -07002147 .swappiness = swappiness,
2148 .order = 0,
2149 .mem_cgroup = mem,
Balbir Singh4e416952009-09-23 15:56:39 -07002150 };
Balbir Singh4e416952009-09-23 15:56:39 -07002151 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2152 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002153
2154 trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
2155 sc.may_writepage,
2156 sc.gfp_mask);
2157
Balbir Singh4e416952009-09-23 15:56:39 -07002158 /*
2159 * NOTE: Although we can get the priority field, using it
2160 * here is not a good idea, since it limits the pages we can scan.
2161 * if we don't reclaim here, the shrink_zone from balance_pgdat
2162 * will pick up pages from other mem cgroup's as well. We hack
2163 * the priority and make it zero.
2164 */
2165 shrink_zone(0, zone, &sc);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002166
2167 trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
2168
Balbir Singh4e416952009-09-23 15:56:39 -07002169 return sc.nr_reclaimed;
2170}
2171
Balbir Singhe1a1cd52008-02-07 00:14:02 -08002172unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002173 gfp_t gfp_mask,
2174 bool noswap,
2175 unsigned int swappiness)
Balbir Singh66e17072008-02-07 00:13:56 -08002176{
Balbir Singh4e416952009-09-23 15:56:39 -07002177 struct zonelist *zonelist;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002178 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002179 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08002180 .may_writepage = !laptop_mode,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002181 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002182 .may_swap = !noswap,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002183 .nr_to_reclaim = SWAP_CLUSTER_MAX,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002184 .swappiness = swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002185 .order = 0,
2186 .mem_cgroup = mem_cont,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002187 .nodemask = NULL, /* we don't care the placement */
Balbir Singh66e17072008-02-07 00:13:56 -08002188 };
Balbir Singh66e17072008-02-07 00:13:56 -08002189
Mel Gormandd1a2392008-04-28 02:12:17 -07002190 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2191 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
2192 zonelist = NODE_DATA(numa_node_id())->node_zonelists;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002193
2194 trace_mm_vmscan_memcg_reclaim_begin(0,
2195 sc.may_writepage,
2196 sc.gfp_mask);
2197
2198 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
2199
2200 trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
2201
2202 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002203}
2204#endif
2205
Mel Gorman1741c872011-01-13 15:46:21 -08002206/*
2207 * pgdat_balanced is used when checking if a node is balanced for high-order
2208 * allocations. Only zones that meet watermarks and are in a zone allowed
2209 * by the callers classzone_idx are added to balanced_pages. The total of
2210 * balanced pages must be at least 25% of the zones allowed by classzone_idx
2211 * for the node to be considered balanced. Forcing all zones to be balanced
2212 * for high orders can cause excessive reclaim when there are imbalanced zones.
2213 * The choice of 25% is due to
2214 * o a 16M DMA zone that is balanced will not balance a zone on any
2215 * reasonable sized machine
2216 * o On all other machines, the top zone must be at least a reasonable
2217 * precentage of the middle zones. For example, on 32-bit x86, highmem
2218 * would need to be at least 256M for it to be balance a whole node.
2219 * Similarly, on x86-64 the Normal zone would need to be at least 1G
2220 * to balance a node on its own. These seemed like reasonable ratios.
2221 */
2222static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
2223 int classzone_idx)
2224{
2225 unsigned long present_pages = 0;
2226 int i;
2227
2228 for (i = 0; i <= classzone_idx; i++)
2229 present_pages += pgdat->node_zones[i].present_pages;
2230
2231 return balanced_pages > (present_pages >> 2);
2232}
2233
Mel Gormanf50de2d2009-12-14 17:58:53 -08002234/* is kswapd sleeping prematurely? */
Mel Gormandc83edd2011-01-13 15:46:26 -08002235static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
2236 int classzone_idx)
Mel Gormanf50de2d2009-12-14 17:58:53 -08002237{
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002238 int i;
Mel Gorman1741c872011-01-13 15:46:21 -08002239 unsigned long balanced = 0;
2240 bool all_zones_ok = true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002241
2242 /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
2243 if (remaining)
Mel Gormandc83edd2011-01-13 15:46:26 -08002244 return true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002245
Mel Gorman0abdee22011-01-13 15:46:22 -08002246 /* Check the watermark levels */
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002247 for (i = 0; i < pgdat->nr_zones; i++) {
2248 struct zone *zone = pgdat->node_zones + i;
2249
2250 if (!populated_zone(zone))
2251 continue;
2252
Mel Gorman355b09c2011-01-13 15:46:24 -08002253 /*
2254 * balance_pgdat() skips over all_unreclaimable after
2255 * DEF_PRIORITY. Effectively, it considers them balanced so
2256 * they must be considered balanced here as well if kswapd
2257 * is to sleep
2258 */
2259 if (zone->all_unreclaimable) {
2260 balanced += zone->present_pages;
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002261 continue;
Mel Gorman355b09c2011-01-13 15:46:24 -08002262 }
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002263
Mel Gorman88f5acf2011-01-13 15:45:41 -08002264 if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
Mel Gormandc83edd2011-01-13 15:46:26 -08002265 classzone_idx, 0))
Mel Gorman1741c872011-01-13 15:46:21 -08002266 all_zones_ok = false;
2267 else
2268 balanced += zone->present_pages;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002269 }
Mel Gormanf50de2d2009-12-14 17:58:53 -08002270
Mel Gorman1741c872011-01-13 15:46:21 -08002271 /*
2272 * For high-order requests, the balanced zones must contain at least
2273 * 25% of the nodes pages for kswapd to sleep. For order-0, all zones
2274 * must be balanced
2275 */
2276 if (order)
Mel Gormandc83edd2011-01-13 15:46:26 -08002277 return pgdat_balanced(pgdat, balanced, classzone_idx);
Mel Gorman1741c872011-01-13 15:46:21 -08002278 else
2279 return !all_zones_ok;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002280}
2281
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282/*
2283 * For kswapd, balance_pgdat() will work across all this node's zones until
Mel Gorman41858962009-06-16 15:32:12 -07002284 * they are all at high_wmark_pages(zone).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285 *
Mel Gorman0abdee22011-01-13 15:46:22 -08002286 * Returns the final order kswapd was reclaiming at
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287 *
2288 * There is special handling here for zones which are full of pinned pages.
2289 * This can happen if the pages are all mlocked, or if they are all used by
2290 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
2291 * What we do is to detect the case where all pages in the zone have been
2292 * scanned twice and there has been zero successful reclaim. Mark the zone as
2293 * dead and from now on, only perform a short scan. Basically we're polling
2294 * the zone for when the problem goes away.
2295 *
2296 * kswapd scans the zones in the highmem->normal->dma direction. It skips
Mel Gorman41858962009-06-16 15:32:12 -07002297 * zones which have free_pages > high_wmark_pages(zone), but once a zone is
2298 * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
2299 * lower zones regardless of the number of free pages in the lower zones. This
2300 * interoperates with the page allocator fallback scheme to ensure that aging
2301 * of pages is balanced across the zones.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302 */
Mel Gorman99504742011-01-13 15:46:20 -08002303static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
Mel Gormandc83edd2011-01-13 15:46:26 -08002304 int *classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002305{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 int all_zones_ok;
Mel Gorman1741c872011-01-13 15:46:21 -08002307 unsigned long balanced;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 int priority;
2309 int i;
Mel Gorman99504742011-01-13 15:46:20 -08002310 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
Andrew Morton69e05942006-03-22 00:08:19 -08002311 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 struct reclaim_state *reclaim_state = current->reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08002313 struct scan_control sc = {
2314 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002315 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002316 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002317 /*
2318 * kswapd doesn't want to be bailed out while reclaim. because
2319 * we want to put equal scanning pressure on each zone.
2320 */
2321 .nr_to_reclaim = ULONG_MAX,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002322 .swappiness = vm_swappiness,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07002323 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08002324 .mem_cgroup = NULL,
Andrew Morton179e9632006-03-22 00:08:18 -08002325 };
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326loop_again:
2327 total_scanned = 0;
Rik van Riela79311c2009-01-06 14:40:01 -08002328 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07002329 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07002330 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 unsigned long lru_pages = 0;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002334 int has_under_min_watermark_zone = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002335
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002336 /* The swap token gets in the way of swapout... */
2337 if (!priority)
2338 disable_swap_token();
2339
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340 all_zones_ok = 1;
Mel Gorman1741c872011-01-13 15:46:21 -08002341 balanced = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002343 /*
2344 * Scan in the highmem->dma direction for the highest
2345 * zone which needs scanning
2346 */
2347 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
2348 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002350 if (!populated_zone(zone))
2351 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002353 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002354 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355
Rik van Riel556adec2008-10-18 20:26:34 -07002356 /*
2357 * Do some background aging of the anon list, to give
2358 * pages a chance to be referenced before reclaiming.
2359 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08002360 if (inactive_anon_is_low(zone, &sc))
Rik van Riel556adec2008-10-18 20:26:34 -07002361 shrink_active_list(SWAP_CLUSTER_MAX, zone,
2362 &sc, priority, 0);
2363
Mel Gorman88f5acf2011-01-13 15:45:41 -08002364 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman41858962009-06-16 15:32:12 -07002365 high_wmark_pages(zone), 0, 0)) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002366 end_zone = i;
Mel Gormandc83edd2011-01-13 15:46:26 -08002367 *classzone_idx = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002368 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002371 if (i < 0)
2372 goto out;
2373
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374 for (i = 0; i <= end_zone; i++) {
2375 struct zone *zone = pgdat->node_zones + i;
2376
Wu Fengguangadea02a2009-09-21 17:01:42 -07002377 lru_pages += zone_reclaimable_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002378 }
2379
2380 /*
2381 * Now scan the zone in the dma->highmem direction, stopping
2382 * at the last zone which needs scanning.
2383 *
2384 * We do this because the page allocator works in the opposite
2385 * direction. This prevents the page allocator from allocating
2386 * pages behind kswapd's direction of progress, which would
2387 * cause too much scanning of the lower zones.
2388 */
2389 for (i = 0; i <= end_zone; i++) {
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002390 int compaction;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002391 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07002392 int nr_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393
Con Kolivasf3fe6512006-01-06 00:11:15 -08002394 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002395 continue;
2396
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002397 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398 continue;
2399
Linus Torvalds1da177e2005-04-16 15:20:36 -07002400 sc.nr_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002401
Balbir Singh4e416952009-09-23 15:56:39 -07002402 /*
2403 * Call soft limit reclaim before calling shrink_zone.
2404 * For now we ignore the return value
2405 */
KOSAKI Motohiro00918b62010-08-10 18:03:05 -07002406 mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
2407
Rik van Riel32a43302007-10-16 01:24:50 -07002408 /*
2409 * We put equal pressure on every zone, unless one
2410 * zone has way too many pages free already.
2411 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002412 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman41858962009-06-16 15:32:12 -07002413 8*high_wmark_pages(zone), end_zone, 0))
Rik van Riela79311c2009-01-06 14:40:01 -08002414 shrink_zone(priority, zone, &sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415 reclaim_state->reclaimed_slab = 0;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07002416 nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
2417 lru_pages);
Rik van Riela79311c2009-01-06 14:40:01 -08002418 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419 total_scanned += sc.nr_scanned;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002420
2421 compaction = 0;
2422 if (order &&
2423 zone_watermark_ok(zone, 0,
2424 high_wmark_pages(zone),
2425 end_zone, 0) &&
2426 !zone_watermark_ok(zone, order,
2427 high_wmark_pages(zone),
2428 end_zone, 0)) {
2429 compact_zone_order(zone,
2430 order,
2431 sc.gfp_mask, false,
2432 COMPACT_MODE_KSWAPD);
2433 compaction = 1;
2434 }
2435
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002436 if (zone->all_unreclaimable)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002437 continue;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002438 if (!compaction && nr_slab == 0 &&
2439 !zone_reclaimable(zone))
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002440 zone->all_unreclaimable = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002441 /*
2442 * If we've done a decent amount of scanning and
2443 * the reclaim ratio is low, start doing writepage
2444 * even in laptop mode
2445 */
2446 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08002447 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002448 sc.may_writepage = 1;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002449
Mel Gorman88f5acf2011-01-13 15:45:41 -08002450 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002451 high_wmark_pages(zone), end_zone, 0)) {
2452 all_zones_ok = 0;
2453 /*
2454 * We are still under min water mark. This
2455 * means that we have a GFP_ATOMIC allocation
2456 * failure risk. Hurry up!
2457 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002458 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002459 min_wmark_pages(zone), end_zone, 0))
2460 has_under_min_watermark_zone = 1;
Mel Gorman0e093d992010-10-26 14:21:45 -07002461 } else {
2462 /*
2463 * If a zone reaches its high watermark,
2464 * consider it to be no longer congested. It's
2465 * possible there are dirty pages backed by
2466 * congested BDIs but as pressure is relieved,
2467 * spectulatively avoid congestion waits
2468 */
2469 zone_clear_flag(zone, ZONE_CONGESTED);
Mel Gormandc83edd2011-01-13 15:46:26 -08002470 if (i <= *classzone_idx)
Mel Gorman1741c872011-01-13 15:46:21 -08002471 balanced += zone->present_pages;
Minchan Kim45973d72010-03-05 13:41:45 -08002472 }
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002473
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 }
Mel Gormandc83edd2011-01-13 15:46:26 -08002475 if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002476 break; /* kswapd: all done */
2477 /*
2478 * OK, kswapd is getting into trouble. Take a nap, then take
2479 * another pass across the zones.
2480 */
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002481 if (total_scanned && (priority < DEF_PRIORITY - 2)) {
2482 if (has_under_min_watermark_zone)
2483 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
2484 else
2485 congestion_wait(BLK_RW_ASYNC, HZ/10);
2486 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487
2488 /*
2489 * We do this so kswapd doesn't build up large priorities for
2490 * example when it is freeing in parallel with allocators. It
2491 * matches the direct reclaim path behaviour in terms of impact
2492 * on zone->*_priority.
2493 */
Rik van Riela79311c2009-01-06 14:40:01 -08002494 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495 break;
2496 }
2497out:
Mel Gorman99504742011-01-13 15:46:20 -08002498
2499 /*
2500 * order-0: All zones must meet high watermark for a balanced node
Mel Gorman1741c872011-01-13 15:46:21 -08002501 * high-order: Balanced zones must make up at least 25% of the node
2502 * for the node to be balanced
Mel Gorman99504742011-01-13 15:46:20 -08002503 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002504 if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08002506
2507 try_to_freeze();
2508
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08002509 /*
2510 * Fragmentation may mean that the system cannot be
2511 * rebalanced for high-order allocations in all zones.
2512 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
2513 * it means the zones have been fully scanned and are still
2514 * not balanced. For high-order allocations, there is
2515 * little point trying all over again as kswapd may
2516 * infinite loop.
2517 *
2518 * Instead, recheck all watermarks at order-0 as they
2519 * are the most important. If watermarks are ok, kswapd will go
2520 * back to sleep. High-order users can still perform direct
2521 * reclaim if they wish.
2522 */
2523 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
2524 order = sc.order = 0;
2525
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526 goto loop_again;
2527 }
2528
Mel Gorman99504742011-01-13 15:46:20 -08002529 /*
2530 * If kswapd was reclaiming at a higher order, it has the option of
2531 * sleeping without all zones being balanced. Before it does, it must
2532 * ensure that the watermarks for order-0 on *all* zones are met and
2533 * that the congestion flags are cleared. The congestion flag must
2534 * be cleared as kswapd is the only mechanism that clears the flag
2535 * and it is potentially going to sleep here.
2536 */
2537 if (order) {
2538 for (i = 0; i <= end_zone; i++) {
2539 struct zone *zone = pgdat->node_zones + i;
2540
2541 if (!populated_zone(zone))
2542 continue;
2543
2544 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
2545 continue;
2546
2547 /* Confirm the zone is balanced for order-0 */
2548 if (!zone_watermark_ok(zone, 0,
2549 high_wmark_pages(zone), 0, 0)) {
2550 order = sc.order = 0;
2551 goto loop_again;
2552 }
2553
2554 /* If balanced, clear the congested flag */
2555 zone_clear_flag(zone, ZONE_CONGESTED);
2556 }
2557 }
2558
Mel Gorman0abdee22011-01-13 15:46:22 -08002559 /*
2560 * Return the order we were reclaiming at so sleeping_prematurely()
2561 * makes a decision on the order we were last reclaiming at. However,
2562 * if another caller entered the allocator slow path while kswapd
2563 * was awake, order will remain at the higher level
2564 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002565 *classzone_idx = end_zone;
Mel Gorman0abdee22011-01-13 15:46:22 -08002566 return order;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567}
2568
Mel Gormandc83edd2011-01-13 15:46:26 -08002569static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002570{
2571 long remaining = 0;
2572 DEFINE_WAIT(wait);
2573
2574 if (freezing(current) || kthread_should_stop())
2575 return;
2576
2577 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2578
2579 /* Try to sleep for a short interval */
Mel Gormandc83edd2011-01-13 15:46:26 -08002580 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002581 remaining = schedule_timeout(HZ/10);
2582 finish_wait(&pgdat->kswapd_wait, &wait);
2583 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2584 }
2585
2586 /*
2587 * After a short sleep, check if it was a premature sleep. If not, then
2588 * go fully to sleep until explicitly woken up.
2589 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002590 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002591 trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
2592
2593 /*
2594 * vmstat counters are not perfectly accurate and the estimated
2595 * value for counters such as NR_FREE_PAGES can deviate from the
2596 * true value by nr_online_cpus * threshold. To avoid the zone
2597 * watermarks being breached while under pressure, we reduce the
2598 * per-cpu vmstat threshold while kswapd is awake and restore
2599 * them before going back to sleep.
2600 */
2601 set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
2602 schedule();
2603 set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
2604 } else {
2605 if (remaining)
2606 count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
2607 else
2608 count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
2609 }
2610 finish_wait(&pgdat->kswapd_wait, &wait);
2611}
2612
Linus Torvalds1da177e2005-04-16 15:20:36 -07002613/*
2614 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002615 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 *
2617 * This basically trickles out pages so that we have _some_
2618 * free memory available even if there is no other activity
2619 * that frees anything up. This is needed for things like routing
2620 * etc, where we otherwise might have all activity going on in
2621 * asynchronous contexts that cannot page things out.
2622 *
2623 * If there are applications that are active memory-allocators
2624 * (most normal use), this basically shouldn't matter.
2625 */
2626static int kswapd(void *p)
2627{
2628 unsigned long order;
Mel Gorman99504742011-01-13 15:46:20 -08002629 int classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630 pg_data_t *pgdat = (pg_data_t*)p;
2631 struct task_struct *tsk = current;
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002632
Linus Torvalds1da177e2005-04-16 15:20:36 -07002633 struct reclaim_state reclaim_state = {
2634 .reclaimed_slab = 0,
2635 };
Rusty Russella70f7302009-03-13 14:49:46 +10302636 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002637
Nick Piggincf40bd12009-01-21 08:12:39 +01002638 lockdep_set_current_reclaim_state(GFP_KERNEL);
2639
Rusty Russell174596a2009-01-01 10:12:29 +10302640 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07002641 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642 current->reclaim_state = &reclaim_state;
2643
2644 /*
2645 * Tell the memory management that we're a "memory allocator",
2646 * and that if we need more memory we should get access to it
2647 * regardless (see "__alloc_pages()"). "kswapd" should
2648 * never get caught in the normal page freeing logic.
2649 *
2650 * (Kswapd normally doesn't need memory anyway, but sometimes
2651 * you need a small amount of memory in order to be able to
2652 * page out something else, and this flag essentially protects
2653 * us from recursively trying to free more memory as we're
2654 * trying to free the first piece of memory in the first place).
2655 */
Christoph Lameter930d9152006-01-08 01:00:47 -08002656 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07002657 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002658
2659 order = 0;
Mel Gorman99504742011-01-13 15:46:20 -08002660 classzone_idx = MAX_NR_ZONES - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661 for ( ; ; ) {
2662 unsigned long new_order;
Mel Gorman99504742011-01-13 15:46:20 -08002663 int new_classzone_idx;
David Rientjes8fe23e02009-12-14 17:58:33 -08002664 int ret;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07002665
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666 new_order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08002667 new_classzone_idx = pgdat->classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668 pgdat->kswapd_max_order = 0;
Mel Gorman99504742011-01-13 15:46:20 -08002669 pgdat->classzone_idx = MAX_NR_ZONES - 1;
2670 if (order < new_order || classzone_idx > new_classzone_idx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671 /*
2672 * Don't sleep if someone wants a larger 'order'
Mel Gorman99504742011-01-13 15:46:20 -08002673 * allocation or has tigher zone constraints
Linus Torvalds1da177e2005-04-16 15:20:36 -07002674 */
2675 order = new_order;
Mel Gorman99504742011-01-13 15:46:20 -08002676 classzone_idx = new_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677 } else {
Mel Gormandc83edd2011-01-13 15:46:26 -08002678 kswapd_try_to_sleep(pgdat, order, classzone_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002679 order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08002680 classzone_idx = pgdat->classzone_idx;
Mel Gorman4d405022011-01-13 15:46:23 -08002681 pgdat->kswapd_max_order = 0;
2682 pgdat->classzone_idx = MAX_NR_ZONES - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002684
David Rientjes8fe23e02009-12-14 17:58:33 -08002685 ret = try_to_freeze();
2686 if (kthread_should_stop())
2687 break;
2688
2689 /*
2690 * We can speed up thawing tasks if we don't call balance_pgdat
2691 * after returning from the refrigerator
2692 */
Mel Gorman33906bc2010-08-09 17:19:16 -07002693 if (!ret) {
2694 trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
Mel Gormandc83edd2011-01-13 15:46:26 -08002695 order = balance_pgdat(pgdat, order, &classzone_idx);
Mel Gorman33906bc2010-08-09 17:19:16 -07002696 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002697 }
2698 return 0;
2699}
2700
2701/*
2702 * A zone is low on free memory, so wake its kswapd task to service it.
2703 */
Mel Gorman99504742011-01-13 15:46:20 -08002704void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705{
2706 pg_data_t *pgdat;
2707
Con Kolivasf3fe6512006-01-06 00:11:15 -08002708 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002709 return;
2710
Paul Jackson02a0e532006-12-13 00:34:25 -08002711 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002712 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08002713 pgdat = zone->zone_pgdat;
Mel Gorman99504742011-01-13 15:46:20 -08002714 if (pgdat->kswapd_max_order < order) {
Mel Gorman88f5acf2011-01-13 15:45:41 -08002715 pgdat->kswapd_max_order = order;
Mel Gorman99504742011-01-13 15:46:20 -08002716 pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
2717 }
Con Kolivas8d0986e2005-09-13 01:25:07 -07002718 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002719 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08002720 if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
2721 return;
2722
2723 trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
Con Kolivas8d0986e2005-09-13 01:25:07 -07002724 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002725}
2726
Wu Fengguangadea02a2009-09-21 17:01:42 -07002727/*
2728 * The reclaimable count would be mostly accurate.
2729 * The less reclaimable pages may be
2730 * - mlocked pages, which will be moved to unevictable list when encountered
2731 * - mapped pages, which may require several travels to be reclaimed
2732 * - dirty pages, which is not "instantly" reclaimable
2733 */
2734unsigned long global_reclaimable_pages(void)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002735{
Wu Fengguangadea02a2009-09-21 17:01:42 -07002736 int nr;
2737
2738 nr = global_page_state(NR_ACTIVE_FILE) +
2739 global_page_state(NR_INACTIVE_FILE);
2740
2741 if (nr_swap_pages > 0)
2742 nr += global_page_state(NR_ACTIVE_ANON) +
2743 global_page_state(NR_INACTIVE_ANON);
2744
2745 return nr;
2746}
2747
2748unsigned long zone_reclaimable_pages(struct zone *zone)
2749{
2750 int nr;
2751
2752 nr = zone_page_state(zone, NR_ACTIVE_FILE) +
2753 zone_page_state(zone, NR_INACTIVE_FILE);
2754
2755 if (nr_swap_pages > 0)
2756 nr += zone_page_state(zone, NR_ACTIVE_ANON) +
2757 zone_page_state(zone, NR_INACTIVE_ANON);
2758
2759 return nr;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002760}
2761
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02002762#ifdef CONFIG_HIBERNATION
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763/*
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002764 * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002765 * freed pages.
2766 *
2767 * Rather than trying to age LRUs the aim is to preserve the overall
2768 * LRU order by reclaiming preferentially
2769 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770 */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002771unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002772{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002773 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002774 struct scan_control sc = {
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002775 .gfp_mask = GFP_HIGHUSER_MOVABLE,
2776 .may_swap = 1,
2777 .may_unmap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002778 .may_writepage = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002779 .nr_to_reclaim = nr_to_reclaim,
2780 .hibernation_mode = 1,
2781 .swappiness = vm_swappiness,
2782 .order = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002783 };
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002784 struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
2785 struct task_struct *p = current;
2786 unsigned long nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002787
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002788 p->flags |= PF_MEMALLOC;
2789 lockdep_set_current_reclaim_state(sc.gfp_mask);
2790 reclaim_state.reclaimed_slab = 0;
2791 p->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08002792
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002793 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002794
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002795 p->reclaim_state = NULL;
2796 lockdep_clear_current_reclaim_state();
2797 p->flags &= ~PF_MEMALLOC;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002798
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002799 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800}
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02002801#endif /* CONFIG_HIBERNATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002802
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803/* It's optimal to keep kswapds on the same CPUs as their memory, but
2804 not required for correctness. So if the last cpu in a node goes
2805 away, we get changed to run anywhere: as the first one comes back,
2806 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07002807static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08002808 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002810 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002811
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002812 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002813 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07002814 pg_data_t *pgdat = NODE_DATA(nid);
Rusty Russella70f7302009-03-13 14:49:46 +10302815 const struct cpumask *mask;
2816
2817 mask = cpumask_of_node(pgdat->node_id);
Mike Travisc5f59f02008-04-04 18:11:10 -07002818
Rusty Russell3e597942009-01-01 10:12:24 +10302819 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002820 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07002821 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002822 }
2823 }
2824 return NOTIFY_OK;
2825}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826
Yasunori Goto3218ae12006-06-27 02:53:33 -07002827/*
2828 * This kswapd start function will be called by init and node-hot-add.
2829 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
2830 */
2831int kswapd_run(int nid)
2832{
2833 pg_data_t *pgdat = NODE_DATA(nid);
2834 int ret = 0;
2835
2836 if (pgdat->kswapd)
2837 return 0;
2838
2839 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
2840 if (IS_ERR(pgdat->kswapd)) {
2841 /* failure at boot is fatal */
2842 BUG_ON(system_state == SYSTEM_BOOTING);
2843 printk("Failed to start kswapd on node %d\n",nid);
2844 ret = -1;
2845 }
2846 return ret;
2847}
2848
David Rientjes8fe23e02009-12-14 17:58:33 -08002849/*
2850 * Called by memory hotplug when all memory in a node is offlined.
2851 */
2852void kswapd_stop(int nid)
2853{
2854 struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
2855
2856 if (kswapd)
2857 kthread_stop(kswapd);
2858}
2859
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860static int __init kswapd_init(void)
2861{
Yasunori Goto3218ae12006-06-27 02:53:33 -07002862 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08002863
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07002865 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07002866 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867 hotcpu_notifier(cpu_callback, 0);
2868 return 0;
2869}
2870
2871module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002872
2873#ifdef CONFIG_NUMA
2874/*
2875 * Zone reclaim mode
2876 *
2877 * If non-zero call zone_reclaim when the number of free pages falls below
2878 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08002879 */
2880int zone_reclaim_mode __read_mostly;
2881
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002882#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07002883#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002884#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
2885#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
2886
Christoph Lameter9eeff232006-01-18 17:42:31 -08002887/*
Christoph Lametera92f7122006-02-01 03:05:32 -08002888 * Priority for ZONE_RECLAIM. This determines the fraction of pages
2889 * of a node considered for each zone_reclaim. 4 scans 1/16th of
2890 * a zone.
2891 */
2892#define ZONE_RECLAIM_PRIORITY 4
2893
Christoph Lameter9eeff232006-01-18 17:42:31 -08002894/*
Christoph Lameter96146342006-07-03 00:24:13 -07002895 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
2896 * occur.
2897 */
2898int sysctl_min_unmapped_ratio = 1;
2899
2900/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002901 * If the number of slab pages in a zone grows beyond this percentage then
2902 * slab reclaim needs to occur.
2903 */
2904int sysctl_min_slab_ratio = 5;
2905
Mel Gorman90afa5d2009-06-16 15:33:20 -07002906static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
2907{
2908 unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
2909 unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
2910 zone_page_state(zone, NR_ACTIVE_FILE);
2911
2912 /*
2913 * It's possible for there to be more file mapped pages than
2914 * accounted for by the pages on the file LRU lists because
2915 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
2916 */
2917 return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
2918}
2919
2920/* Work out how many page cache pages we can reclaim in this reclaim_mode */
2921static long zone_pagecache_reclaimable(struct zone *zone)
2922{
2923 long nr_pagecache_reclaimable;
2924 long delta = 0;
2925
2926 /*
2927 * If RECLAIM_SWAP is set, then all file pages are considered
2928 * potentially reclaimable. Otherwise, we have to worry about
2929 * pages like swapcache and zone_unmapped_file_pages() provides
2930 * a better estimate
2931 */
2932 if (zone_reclaim_mode & RECLAIM_SWAP)
2933 nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
2934 else
2935 nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
2936
2937 /* If we can't clean pages, remove dirty pages from consideration */
2938 if (!(zone_reclaim_mode & RECLAIM_WRITE))
2939 delta += zone_page_state(zone, NR_FILE_DIRTY);
2940
2941 /* Watch for any possible underflows due to delta */
2942 if (unlikely(delta > nr_pagecache_reclaimable))
2943 delta = nr_pagecache_reclaimable;
2944
2945 return nr_pagecache_reclaimable - delta;
2946}
2947
Christoph Lameter0ff38492006-09-25 23:31:52 -07002948/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08002949 * Try to free up some pages from this zone through reclaim.
2950 */
Andrew Morton179e9632006-03-22 00:08:18 -08002951static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002952{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002953 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08002954 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002955 struct task_struct *p = current;
2956 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08002957 int priority;
Andrew Morton179e9632006-03-22 00:08:18 -08002958 struct scan_control sc = {
2959 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002960 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002961 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002962 .nr_to_reclaim = max_t(unsigned long, nr_pages,
2963 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08002964 .gfp_mask = gfp_mask,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002965 .swappiness = vm_swappiness,
Johannes Weinerbd2f6192009-03-31 15:19:38 -07002966 .order = order,
Andrew Morton179e9632006-03-22 00:08:18 -08002967 };
KOSAKI Motohiro15748042010-08-09 17:19:50 -07002968 unsigned long nr_slab_pages0, nr_slab_pages1;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002969
Christoph Lameter9eeff232006-01-18 17:42:31 -08002970 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08002971 /*
2972 * We need to be able to allocate from the reserves for RECLAIM_SWAP
2973 * and we also need to be able to write out pages for RECLAIM_WRITE
2974 * and RECLAIM_SWAP.
2975 */
2976 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08002977 lockdep_set_current_reclaim_state(gfp_mask);
Christoph Lameter9eeff232006-01-18 17:42:31 -08002978 reclaim_state.reclaimed_slab = 0;
2979 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08002980
Mel Gorman90afa5d2009-06-16 15:33:20 -07002981 if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
Christoph Lameter0ff38492006-09-25 23:31:52 -07002982 /*
2983 * Free memory by calling shrink zone with increasing
2984 * priorities until we have enough memory freed.
2985 */
2986 priority = ZONE_RECLAIM_PRIORITY;
2987 do {
Rik van Riela79311c2009-01-06 14:40:01 -08002988 shrink_zone(priority, zone, &sc);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002989 priority--;
Rik van Riela79311c2009-01-06 14:40:01 -08002990 } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002991 }
Christoph Lameterc84db232006-02-01 03:05:29 -08002992
KOSAKI Motohiro15748042010-08-09 17:19:50 -07002993 nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
2994 if (nr_slab_pages0 > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002995 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002996 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07002997 * many pages were freed in this zone. So we take the current
2998 * number of slab pages and shake the slab until it is reduced
2999 * by the same nr_pages that we used for reclaiming unmapped
3000 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003001 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07003002 * Note that shrink_slab will free memory on all zones and may
3003 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003004 */
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003005 for (;;) {
3006 unsigned long lru_pages = zone_reclaimable_pages(zone);
3007
3008 /* No reclaimable slab or very low memory pressure */
3009 if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages))
3010 break;
3011
3012 /* Freed enough memory */
3013 nr_slab_pages1 = zone_page_state(zone,
3014 NR_SLAB_RECLAIMABLE);
3015 if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
3016 break;
3017 }
Christoph Lameter83e33a42006-09-25 23:31:53 -07003018
3019 /*
3020 * Update nr_reclaimed by the number of slab pages we
3021 * reclaimed from this zone.
3022 */
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003023 nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3024 if (nr_slab_pages1 < nr_slab_pages0)
3025 sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003026 }
3027
Christoph Lameter9eeff232006-01-18 17:42:31 -08003028 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08003029 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003030 lockdep_clear_current_reclaim_state();
Rik van Riela79311c2009-01-06 14:40:01 -08003031 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003032}
Andrew Morton179e9632006-03-22 00:08:18 -08003033
3034int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
3035{
Andrew Morton179e9632006-03-22 00:08:18 -08003036 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07003037 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003038
3039 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003040 * Zone reclaim reclaims unmapped file backed pages and
3041 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07003042 *
Christoph Lameter96146342006-07-03 00:24:13 -07003043 * A small portion of unmapped file backed pages is needed for
3044 * file I/O otherwise pages read by file I/O will be immediately
3045 * thrown out if the zone is overallocated. So we do not reclaim
3046 * if less than a specified percentage of the zone is used by
3047 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08003048 */
Mel Gorman90afa5d2009-06-16 15:33:20 -07003049 if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
3050 zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003051 return ZONE_RECLAIM_FULL;
Andrew Morton179e9632006-03-22 00:08:18 -08003052
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08003053 if (zone->all_unreclaimable)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003054 return ZONE_RECLAIM_FULL;
David Rientjesd773ed62007-10-16 23:26:01 -07003055
Andrew Morton179e9632006-03-22 00:08:18 -08003056 /*
David Rientjesd773ed62007-10-16 23:26:01 -07003057 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08003058 */
David Rientjesd773ed62007-10-16 23:26:01 -07003059 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003060 return ZONE_RECLAIM_NOSCAN;
Andrew Morton179e9632006-03-22 00:08:18 -08003061
3062 /*
3063 * Only run zone reclaim on the local zone or on zones that do not
3064 * have associated processors. This will favor the local processor
3065 * over remote processors and spread off node memory allocations
3066 * as wide as possible.
3067 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07003068 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07003069 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Mel Gormanfa5e0842009-06-16 15:33:22 -07003070 return ZONE_RECLAIM_NOSCAN;
David Rientjesd773ed62007-10-16 23:26:01 -07003071
3072 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003073 return ZONE_RECLAIM_NOSCAN;
3074
David Rientjesd773ed62007-10-16 23:26:01 -07003075 ret = __zone_reclaim(zone, gfp_mask, order);
3076 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
3077
Mel Gorman24cf725182009-06-16 15:33:23 -07003078 if (!ret)
3079 count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
3080
David Rientjesd773ed62007-10-16 23:26:01 -07003081 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003082}
Christoph Lameter9eeff232006-01-18 17:42:31 -08003083#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003084
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003085/*
3086 * page_evictable - test whether a page is evictable
3087 * @page: the page to test
3088 * @vma: the VMA in which the page is or will be mapped, may be NULL
3089 *
3090 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07003091 * lists vs unevictable list. The vma argument is !NULL when called from the
3092 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003093 *
3094 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003095 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07003096 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003097 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003098 */
3099int page_evictable(struct page *page, struct vm_area_struct *vma)
3100{
3101
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003102 if (mapping_unevictable(page_mapping(page)))
3103 return 0;
3104
Nick Pigginb291f002008-10-18 20:26:44 -07003105 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
3106 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003107
3108 return 1;
3109}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003110
3111/**
3112 * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
3113 * @page: page to check evictability and move to appropriate lru list
3114 * @zone: zone page is in
3115 *
3116 * Checks a page for evictability and moves the page to the appropriate
3117 * zone lru list.
3118 *
3119 * Restrictions: zone->lru_lock must be held, page must be on LRU and must
3120 * have PageUnevictable set.
3121 */
3122static void check_move_unevictable_page(struct page *page, struct zone *zone)
3123{
3124 VM_BUG_ON(PageActive(page));
3125
3126retry:
3127 ClearPageUnevictable(page);
3128 if (page_evictable(page, NULL)) {
Johannes Weiner401a8e12009-09-21 17:02:58 -07003129 enum lru_list l = page_lru_base_type(page);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003130
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003131 __dec_zone_state(zone, NR_UNEVICTABLE);
3132 list_move(&page->lru, &zone->lru[l].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08003133 mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003134 __inc_zone_state(zone, NR_INACTIVE_ANON + l);
3135 __count_vm_event(UNEVICTABLE_PGRESCUED);
3136 } else {
3137 /*
3138 * rotate unevictable list
3139 */
3140 SetPageUnevictable(page);
3141 list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08003142 mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003143 if (page_evictable(page, NULL))
3144 goto retry;
3145 }
3146}
3147
3148/**
3149 * scan_mapping_unevictable_pages - scan an address space for evictable pages
3150 * @mapping: struct address_space to scan for evictable pages
3151 *
3152 * Scan all pages in mapping. Check unevictable pages for
3153 * evictability and move them to the appropriate zone lru list.
3154 */
3155void scan_mapping_unevictable_pages(struct address_space *mapping)
3156{
3157 pgoff_t next = 0;
3158 pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
3159 PAGE_CACHE_SHIFT;
3160 struct zone *zone;
3161 struct pagevec pvec;
3162
3163 if (mapping->nrpages == 0)
3164 return;
3165
3166 pagevec_init(&pvec, 0);
3167 while (next < end &&
3168 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
3169 int i;
3170 int pg_scanned = 0;
3171
3172 zone = NULL;
3173
3174 for (i = 0; i < pagevec_count(&pvec); i++) {
3175 struct page *page = pvec.pages[i];
3176 pgoff_t page_index = page->index;
3177 struct zone *pagezone = page_zone(page);
3178
3179 pg_scanned++;
3180 if (page_index > next)
3181 next = page_index;
3182 next++;
3183
3184 if (pagezone != zone) {
3185 if (zone)
3186 spin_unlock_irq(&zone->lru_lock);
3187 zone = pagezone;
3188 spin_lock_irq(&zone->lru_lock);
3189 }
3190
3191 if (PageLRU(page) && PageUnevictable(page))
3192 check_move_unevictable_page(page, zone);
3193 }
3194 if (zone)
3195 spin_unlock_irq(&zone->lru_lock);
3196 pagevec_release(&pvec);
3197
3198 count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
3199 }
3200
3201}
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003202
3203/**
3204 * scan_zone_unevictable_pages - check unevictable list for evictable pages
3205 * @zone - zone of which to scan the unevictable list
3206 *
3207 * Scan @zone's unevictable LRU lists to check for pages that have become
3208 * evictable. Move those that have to @zone's inactive list where they
3209 * become candidates for reclaim, unless shrink_inactive_zone() decides
3210 * to reactivate them. Pages that are still unevictable are rotated
3211 * back onto @zone's unevictable list.
3212 */
3213#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
KOSAKI Motohiro14b90b22009-01-06 14:39:45 -08003214static void scan_zone_unevictable_pages(struct zone *zone)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003215{
3216 struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
3217 unsigned long scan;
3218 unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
3219
3220 while (nr_to_scan > 0) {
3221 unsigned long batch_size = min(nr_to_scan,
3222 SCAN_UNEVICTABLE_BATCH_SIZE);
3223
3224 spin_lock_irq(&zone->lru_lock);
3225 for (scan = 0; scan < batch_size; scan++) {
3226 struct page *page = lru_to_page(l_unevictable);
3227
3228 if (!trylock_page(page))
3229 continue;
3230
3231 prefetchw_prev_lru_page(page, l_unevictable, flags);
3232
3233 if (likely(PageLRU(page) && PageUnevictable(page)))
3234 check_move_unevictable_page(page, zone);
3235
3236 unlock_page(page);
3237 }
3238 spin_unlock_irq(&zone->lru_lock);
3239
3240 nr_to_scan -= batch_size;
3241 }
3242}
3243
3244
3245/**
3246 * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
3247 *
3248 * A really big hammer: scan all zones' unevictable LRU lists to check for
3249 * pages that have become evictable. Move those back to the zones'
3250 * inactive list where they become candidates for reclaim.
3251 * This occurs when, e.g., we have unswappable pages on the unevictable lists,
3252 * and we add swap to the system. As such, it runs in the context of a task
3253 * that has possibly/probably made some previously unevictable pages
3254 * evictable.
3255 */
KOSAKI Motohiroff301532009-01-06 14:39:44 -08003256static void scan_all_zones_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003257{
3258 struct zone *zone;
3259
3260 for_each_zone(zone) {
3261 scan_zone_unevictable_pages(zone);
3262 }
3263}
3264
3265/*
3266 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
3267 * all nodes' unevictable lists for evictable pages
3268 */
3269unsigned long scan_unevictable_pages;
3270
3271int scan_unevictable_handler(struct ctl_table *table, int write,
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003272 void __user *buffer,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003273 size_t *length, loff_t *ppos)
3274{
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003275 proc_doulongvec_minmax(table, write, buffer, length, ppos);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003276
3277 if (write && *(unsigned long *)table->data)
3278 scan_all_zones_unevictable_pages();
3279
3280 scan_unevictable_pages = 0;
3281 return 0;
3282}
3283
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003284#ifdef CONFIG_NUMA
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003285/*
3286 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
3287 * a specified node's per zone unevictable lists for evictable pages.
3288 */
3289
3290static ssize_t read_scan_unevictable_node(struct sys_device *dev,
3291 struct sysdev_attribute *attr,
3292 char *buf)
3293{
3294 return sprintf(buf, "0\n"); /* always zero; should fit... */
3295}
3296
3297static ssize_t write_scan_unevictable_node(struct sys_device *dev,
3298 struct sysdev_attribute *attr,
3299 const char *buf, size_t count)
3300{
3301 struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
3302 struct zone *zone;
3303 unsigned long res;
3304 unsigned long req = strict_strtoul(buf, 10, &res);
3305
3306 if (!req)
3307 return 1; /* zero is no-op */
3308
3309 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
3310 if (!populated_zone(zone))
3311 continue;
3312 scan_zone_unevictable_pages(zone);
3313 }
3314 return 1;
3315}
3316
3317
3318static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
3319 read_scan_unevictable_node,
3320 write_scan_unevictable_node);
3321
3322int scan_unevictable_register_node(struct node *node)
3323{
3324 return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
3325}
3326
3327void scan_unevictable_unregister_node(struct node *node)
3328{
3329 sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
3330}
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003331#endif