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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/vmscan.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
12 */
13
14#include <linux/mm.h>
15#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090016#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/kernel_stat.h>
18#include <linux/swap.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/highmem.h>
Andrew Mortone129b5c2006-09-27 01:50:00 -070022#include <linux/vmstat.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/file.h>
24#include <linux/writeback.h>
25#include <linux/blkdev.h>
26#include <linux/buffer_head.h> /* for try_to_release_page(),
27 buffer_heads_over_limit */
28#include <linux/mm_inline.h>
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45#include <asm/tlbflush.h>
46#include <asm/div64.h>
47
48#include <linux/swapops.h>
49
Nick Piggin0f8053a2006-03-22 00:08:33 -080050#include "internal.h"
51
Mel Gorman33906bc2010-08-09 17:19:16 -070052#define CREATE_TRACE_POINTS
53#include <trace/events/vmscan.h>
54
Mel Gormanee64fc92011-01-13 15:45:55 -080055/*
Mel Gormanf3a310b2011-01-13 15:46:00 -080056 * reclaim_mode determines how the inactive list is shrunk
57 * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages
58 * RECLAIM_MODE_ASYNC: Do not block
59 * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
60 * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference
Mel Gormanee64fc92011-01-13 15:45:55 -080061 * page from the LRU and reclaim all pages within a
62 * naturally aligned range
Mel Gormanf3a310b2011-01-13 15:46:00 -080063 * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of
Mel Gorman3e7d3442011-01-13 15:45:56 -080064 * order-0 pages and then compact the zone
Mel Gormanee64fc92011-01-13 15:45:55 -080065 */
Mel Gormanf3a310b2011-01-13 15:46:00 -080066typedef unsigned __bitwise__ reclaim_mode_t;
67#define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u)
68#define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u)
69#define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u)
70#define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u)
71#define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u)
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -070072
Linus Torvalds1da177e2005-04-16 15:20:36 -070073struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 /* Incremented by the number of inactive pages that were scanned */
75 unsigned long nr_scanned;
76
Rik van Riela79311c2009-01-06 14:40:01 -080077 /* Number of pages freed so far during a call to shrink_zones() */
78 unsigned long nr_reclaimed;
79
KOSAKI Motohiro22fba332009-12-14 17:59:10 -080080 /* How many pages shrink_list() should reclaim */
81 unsigned long nr_to_reclaim;
82
KOSAKI Motohiro7b517552009-12-14 17:59:12 -080083 unsigned long hibernation_mode;
84
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040086 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
88 int may_writepage;
89
Johannes Weinera6dc60f82009-03-31 15:19:30 -070090 /* Can mapped pages be reclaimed? */
91 int may_unmap;
Christoph Lameterf1fd1062006-01-18 17:42:30 -080092
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -070093 /* Can pages be swapped as part of reclaim? */
94 int may_swap;
95
Rafael J. Wysockid6277db2006-06-23 02:03:18 -070096 int swappiness;
Nick Piggin408d8542006-09-25 23:31:27 -070097
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070098 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080099
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700100 /*
Nikanth Karthikesan415b54e2010-08-17 15:39:09 +0530101 * Intend to reclaim enough continuous memory rather than reclaim
102 * enough amount of memory. i.e, mode for high order allocation.
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700103 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800104 reclaim_mode_t reclaim_mode;
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -0700105
Balbir Singh66e17072008-02-07 00:13:56 -0800106 /* Which cgroup do we reclaim from */
107 struct mem_cgroup *mem_cgroup;
108
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700109 /*
110 * Nodemask of nodes allowed by the caller. If NULL, all nodes
111 * are scanned.
112 */
113 nodemask_t *nodemask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114};
115
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
117
118#ifdef ARCH_HAS_PREFETCH
119#define prefetch_prev_lru_page(_page, _base, _field) \
120 do { \
121 if ((_page)->lru.prev != _base) { \
122 struct page *prev; \
123 \
124 prev = lru_to_page(&(_page->lru)); \
125 prefetch(&prev->_field); \
126 } \
127 } while (0)
128#else
129#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
130#endif
131
132#ifdef ARCH_HAS_PREFETCHW
133#define prefetchw_prev_lru_page(_page, _base, _field) \
134 do { \
135 if ((_page)->lru.prev != _base) { \
136 struct page *prev; \
137 \
138 prev = lru_to_page(&(_page->lru)); \
139 prefetchw(&prev->_field); \
140 } \
141 } while (0)
142#else
143#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
144#endif
145
146/*
147 * From 0 .. 100. Higher means more swappy.
148 */
149int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700150long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152static LIST_HEAD(shrinker_list);
153static DECLARE_RWSEM(shrinker_rwsem);
154
Balbir Singh00f0b822008-03-04 14:28:39 -0800155#ifdef CONFIG_CGROUP_MEM_RES_CTLR
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800156#define scanning_global_lru(sc) (!(sc)->mem_cgroup)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800157#else
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800158#define scanning_global_lru(sc) (1)
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800159#endif
160
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800161static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
162 struct scan_control *sc)
163{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800164 if (!scanning_global_lru(sc))
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800165 return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone);
166
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800167 return &zone->reclaim_stat;
168}
169
Vincent Li0b217672009-09-21 17:03:09 -0700170static unsigned long zone_nr_lru_pages(struct zone *zone,
171 struct scan_control *sc, enum lru_list lru)
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800172{
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -0800173 if (!scanning_global_lru(sc))
KOSAKI Motohiroa3d8e052009-01-07 18:08:19 -0800174 return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru);
175
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800176 return zone_page_state(zone, NR_LRU_BASE + lru);
177}
178
179
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180/*
181 * Add a shrinker callback to be called from the vm
182 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700183void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184{
Rusty Russell8e1f9362007-07-17 04:03:17 -0700185 shrinker->nr = 0;
186 down_write(&shrinker_rwsem);
187 list_add_tail(&shrinker->list, &shrinker_list);
188 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700190EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
192/*
193 * Remove one
194 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700195void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196{
197 down_write(&shrinker_rwsem);
198 list_del(&shrinker->list);
199 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700201EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
203#define SHRINK_BATCH 128
204/*
205 * Call the shrink functions to age shrinkable caches
206 *
207 * Here we assume it costs one seek to replace a lru page and that it also
208 * takes a seek to recreate a cache object. With this in mind we age equal
209 * percentages of the lru and ageable caches. This should balance the seeks
210 * generated by these structures.
211 *
Simon Arlott183ff222007-10-20 01:27:18 +0200212 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 * slab to avoid swapping.
214 *
215 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
216 *
217 * `lru_pages' represents the number of on-LRU pages in all the zones which
218 * are eligible for the caller's allocation attempt. It is used for balancing
219 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700220 *
221 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 */
Andrew Morton69e05942006-03-22 00:08:19 -0800223unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
224 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225{
226 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800227 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228
229 if (scanned == 0)
230 scanned = SWAP_CLUSTER_MAX;
231
232 if (!down_read_trylock(&shrinker_rwsem))
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700233 return 1; /* Assume we'll be able to shrink next time */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
235 list_for_each_entry(shrinker, &shrinker_list, list) {
236 unsigned long long delta;
237 unsigned long total_scan;
Dave Chinner7f8275d2010-07-19 14:56:17 +1000238 unsigned long max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
Dave Chinner7f8275d2010-07-19 14:56:17 +1000240 max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 delta = (4 * scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800242 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 do_div(delta, lru_pages + 1);
244 shrinker->nr += delta;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800245 if (shrinker->nr < 0) {
David Rientjes88c3bd72009-03-31 15:23:29 -0700246 printk(KERN_ERR "shrink_slab: %pF negative objects to "
247 "delete nr=%ld\n",
248 shrinker->shrink, shrinker->nr);
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800249 shrinker->nr = max_pass;
250 }
251
252 /*
253 * Avoid risking looping forever due to too large nr value:
254 * never try to free more than twice the estimate number of
255 * freeable entries.
256 */
257 if (shrinker->nr > max_pass * 2)
258 shrinker->nr = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259
260 total_scan = shrinker->nr;
261 shrinker->nr = 0;
262
263 while (total_scan >= SHRINK_BATCH) {
264 long this_scan = SHRINK_BATCH;
265 int shrink_ret;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700266 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267
Dave Chinner7f8275d2010-07-19 14:56:17 +1000268 nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
269 shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
270 gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 if (shrink_ret == -1)
272 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700273 if (shrink_ret < nr_before)
274 ret += nr_before - shrink_ret;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700275 count_vm_events(SLABS_SCANNED, this_scan);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 total_scan -= this_scan;
277
278 cond_resched();
279 }
280
281 shrinker->nr += total_scan;
282 }
283 up_read(&shrinker_rwsem);
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700284 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285}
286
Mel Gormanf3a310b2011-01-13 15:46:00 -0800287static void set_reclaim_mode(int priority, struct scan_control *sc,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700288 bool sync)
289{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800290 reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700291
292 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800293 * Initially assume we are entering either lumpy reclaim or
294 * reclaim/compaction.Depending on the order, we will either set the
295 * sync mode or just reclaim order-0 pages later.
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700296 */
Mel Gorman3e7d3442011-01-13 15:45:56 -0800297 if (COMPACTION_BUILD)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800298 sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
Mel Gorman3e7d3442011-01-13 15:45:56 -0800299 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800300 sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700301
302 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800303 * Avoid using lumpy reclaim or reclaim/compaction if possible by
304 * restricting when its set to either costly allocations or when
305 * under memory pressure
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700306 */
307 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800308 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700309 else if (sc->order && priority < DEF_PRIORITY - 2)
Mel Gormanf3a310b2011-01-13 15:46:00 -0800310 sc->reclaim_mode |= syncmode;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700311 else
Mel Gormanf3a310b2011-01-13 15:46:00 -0800312 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700313}
314
Mel Gormanf3a310b2011-01-13 15:46:00 -0800315static void reset_reclaim_mode(struct scan_control *sc)
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700316{
Mel Gormanf3a310b2011-01-13 15:46:00 -0800317 sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700318}
319
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320static inline int is_page_cache_freeable(struct page *page)
321{
Johannes Weinerceddc3a2009-09-21 17:03:00 -0700322 /*
323 * A freeable page cache page is referenced only by the caller
324 * that isolated the page, the page cache radix tree and
325 * optional buffer heads at page->private.
326 */
Johannes Weineredcf4742009-09-21 17:02:59 -0700327 return page_count(page) - page_has_private(page) == 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328}
329
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700330static int may_write_to_queue(struct backing_dev_info *bdi,
331 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332{
Christoph Lameter930d9152006-01-08 01:00:47 -0800333 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 return 1;
335 if (!bdi_write_congested(bdi))
336 return 1;
337 if (bdi == current->backing_dev_info)
338 return 1;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700339
340 /* lumpy reclaim for hugepage often need a lot of write */
341 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
342 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 return 0;
344}
345
346/*
347 * We detected a synchronous write error writing a page out. Probably
348 * -ENOSPC. We need to propagate that into the address_space for a subsequent
349 * fsync(), msync() or close().
350 *
351 * The tricky part is that after writepage we cannot touch the mapping: nothing
352 * prevents it from being freed up. But we have a ref on the page and once
353 * that page is locked, the mapping is pinned.
354 *
355 * We're allowed to run sleeping lock_page() here because we know the caller has
356 * __GFP_FS.
357 */
358static void handle_write_error(struct address_space *mapping,
359 struct page *page, int error)
360{
Nick Piggina6aa62a2010-07-20 13:24:25 -0700361 lock_page_nosync(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700362 if (page_mapping(page) == mapping)
363 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 unlock_page(page);
365}
366
Christoph Lameter04e62a22006-06-23 02:03:38 -0700367/* possible outcome of pageout() */
368typedef enum {
369 /* failed to write page out, page is locked */
370 PAGE_KEEP,
371 /* move page to the active list, page is locked */
372 PAGE_ACTIVATE,
373 /* page has been sent to the disk successfully, page is unlocked */
374 PAGE_SUCCESS,
375 /* page is clean and locked */
376 PAGE_CLEAN,
377} pageout_t;
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379/*
Andrew Morton1742f192006-03-22 00:08:21 -0800380 * pageout is called by shrink_page_list() for each dirty page.
381 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700383static pageout_t pageout(struct page *page, struct address_space *mapping,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700384 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385{
386 /*
387 * If the page is dirty, only perform writeback if that write
388 * will be non-blocking. To prevent this allocation from being
389 * stalled by pagecache activity. But note that there may be
390 * stalls if we need to run get_block(). We could test
391 * PagePrivate for that.
392 *
Vincent Li6aceb532009-12-14 17:58:49 -0800393 * If this process is currently in __generic_file_aio_write() against
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 * this page's queue, we can perform writeback even if that
395 * will block.
396 *
397 * If the page is swapcache, write it back even if that would
398 * block, for some throttling. This happens by accident, because
399 * swap_backing_dev_info is bust: it doesn't reflect the
400 * congestion state of the swapdevs. Easy to fix, if needed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 */
402 if (!is_page_cache_freeable(page))
403 return PAGE_KEEP;
404 if (!mapping) {
405 /*
406 * Some data journaling orphaned pages can have
407 * page->mapping == NULL while being dirty with clean buffers.
408 */
David Howells266cf652009-04-03 16:42:36 +0100409 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 if (try_to_free_buffers(page)) {
411 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700412 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 return PAGE_CLEAN;
414 }
415 }
416 return PAGE_KEEP;
417 }
418 if (mapping->a_ops->writepage == NULL)
419 return PAGE_ACTIVATE;
Mel Gorman0e093d992010-10-26 14:21:45 -0700420 if (!may_write_to_queue(mapping->backing_dev_info, sc))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 return PAGE_KEEP;
422
423 if (clear_page_dirty_for_io(page)) {
424 int res;
425 struct writeback_control wbc = {
426 .sync_mode = WB_SYNC_NONE,
427 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700428 .range_start = 0,
429 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 .for_reclaim = 1,
431 };
432
433 SetPageReclaim(page);
434 res = mapping->a_ops->writepage(page, &wbc);
435 if (res < 0)
436 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800437 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 ClearPageReclaim(page);
439 return PAGE_ACTIVATE;
440 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700441
442 /*
443 * Wait on writeback if requested to. This happens when
444 * direct reclaiming a large contiguous area and the
445 * first attempt to free a range of pages fails.
446 */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700447 if (PageWriteback(page) &&
Mel Gormanf3a310b2011-01-13 15:46:00 -0800448 (sc->reclaim_mode & RECLAIM_MODE_SYNC))
Andy Whitcroftc661b072007-08-22 14:01:26 -0700449 wait_on_page_writeback(page);
450
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 if (!PageWriteback(page)) {
452 /* synchronous write or broken a_ops? */
453 ClearPageReclaim(page);
454 }
Mel Gorman755f0222010-08-09 17:19:18 -0700455 trace_mm_vmscan_writepage(page,
Mel Gormanf3a310b2011-01-13 15:46:00 -0800456 trace_reclaim_flags(page, sc->reclaim_mode));
Andrew Mortone129b5c2006-09-27 01:50:00 -0700457 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 return PAGE_SUCCESS;
459 }
460
461 return PAGE_CLEAN;
462}
463
Andrew Mortona649fd92006-10-17 00:09:36 -0700464/*
Nick Piggine2867812008-07-25 19:45:30 -0700465 * Same as remove_mapping, but if the page is removed from the mapping, it
466 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700467 */
Nick Piggine2867812008-07-25 19:45:30 -0700468static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800469{
Nick Piggin28e4d962006-09-25 23:31:23 -0700470 BUG_ON(!PageLocked(page));
471 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800472
Nick Piggin19fd6232008-07-25 19:45:32 -0700473 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800474 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700475 * The non racy check for a busy page.
476 *
477 * Must be careful with the order of the tests. When someone has
478 * a ref to the page, it may be possible that they dirty it then
479 * drop the reference. So if PageDirty is tested before page_count
480 * here, then the following race may occur:
481 *
482 * get_user_pages(&page);
483 * [user mapping goes away]
484 * write_to(page);
485 * !PageDirty(page) [good]
486 * SetPageDirty(page);
487 * put_page(page);
488 * !page_count(page) [good, discard it]
489 *
490 * [oops, our write_to data is lost]
491 *
492 * Reversing the order of the tests ensures such a situation cannot
493 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
494 * load is not satisfied before that of page->_count.
495 *
496 * Note that if SetPageDirty is always performed via set_page_dirty,
497 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800498 */
Nick Piggine2867812008-07-25 19:45:30 -0700499 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800500 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700501 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
502 if (unlikely(PageDirty(page))) {
503 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800504 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700505 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800506
507 if (PageSwapCache(page)) {
508 swp_entry_t swap = { .val = page_private(page) };
509 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700510 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -0700511 swapcache_free(swap, page);
Nick Piggine2867812008-07-25 19:45:30 -0700512 } else {
Linus Torvalds6072d132010-12-01 13:35:19 -0500513 void (*freepage)(struct page *);
514
515 freepage = mapping->a_ops->freepage;
516
Nick Piggine2867812008-07-25 19:45:30 -0700517 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700518 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700519 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500520
521 if (freepage != NULL)
522 freepage(page);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800523 }
524
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800525 return 1;
526
527cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700528 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800529 return 0;
530}
531
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532/*
Nick Piggine2867812008-07-25 19:45:30 -0700533 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
534 * someone else has a ref on the page, abort and return 0. If it was
535 * successfully detached, return 1. Assumes the caller has a single ref on
536 * this page.
537 */
538int remove_mapping(struct address_space *mapping, struct page *page)
539{
540 if (__remove_mapping(mapping, page)) {
541 /*
542 * Unfreezing the refcount with 1 rather than 2 effectively
543 * drops the pagecache ref for us without requiring another
544 * atomic operation.
545 */
546 page_unfreeze_refs(page, 1);
547 return 1;
548 }
549 return 0;
550}
551
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700552/**
553 * putback_lru_page - put previously isolated page onto appropriate LRU list
554 * @page: page to be put back to appropriate lru list
555 *
556 * Add previously isolated @page to appropriate LRU list.
557 * Page may still be unevictable for other reasons.
558 *
559 * lru_lock must not be held, interrupts must be enabled.
560 */
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700561void putback_lru_page(struct page *page)
562{
563 int lru;
564 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700565 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700566
567 VM_BUG_ON(PageLRU(page));
568
569redo:
570 ClearPageUnevictable(page);
571
572 if (page_evictable(page, NULL)) {
573 /*
574 * For evictable pages, we can use the cache.
575 * In event of a race, worst case is we end up with an
576 * unevictable page on [in]active list.
577 * We know how to handle that.
578 */
Johannes Weiner401a8e12009-09-21 17:02:58 -0700579 lru = active + page_lru_base_type(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700580 lru_cache_add_lru(page, lru);
581 } else {
582 /*
583 * Put unevictable pages directly on zone's unevictable
584 * list.
585 */
586 lru = LRU_UNEVICTABLE;
587 add_page_to_unevictable_list(page);
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700588 /*
589 * When racing with an mlock clearing (page is
590 * unlocked), make sure that if the other thread does
591 * not observe our setting of PG_lru and fails
592 * isolation, we see PG_mlocked cleared below and move
593 * the page back to the evictable list.
594 *
595 * The other side is TestClearPageMlocked().
596 */
597 smp_mb();
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700598 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700599
600 /*
601 * page's status can change while we move it among lru. If an evictable
602 * page is on unevictable list, it never be freed. To avoid that,
603 * check after we added it to the list, again.
604 */
605 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
606 if (!isolate_lru_page(page)) {
607 put_page(page);
608 goto redo;
609 }
610 /* This means someone else dropped this page from LRU
611 * So, it will be freed or putback to LRU again. There is
612 * nothing to do here.
613 */
614 }
615
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700616 if (was_unevictable && lru != LRU_UNEVICTABLE)
617 count_vm_event(UNEVICTABLE_PGRESCUED);
618 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
619 count_vm_event(UNEVICTABLE_PGCULLED);
620
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700621 put_page(page); /* drop ref from isolate */
622}
623
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800624enum page_references {
625 PAGEREF_RECLAIM,
626 PAGEREF_RECLAIM_CLEAN,
Johannes Weiner645747462010-03-05 13:42:22 -0800627 PAGEREF_KEEP,
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800628 PAGEREF_ACTIVATE,
629};
630
631static enum page_references page_check_references(struct page *page,
632 struct scan_control *sc)
633{
Johannes Weiner645747462010-03-05 13:42:22 -0800634 int referenced_ptes, referenced_page;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800635 unsigned long vm_flags;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800636
Johannes Weiner645747462010-03-05 13:42:22 -0800637 referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags);
638 referenced_page = TestClearPageReferenced(page);
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800639
640 /* Lumpy reclaim - ignore references */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800641 if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM)
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800642 return PAGEREF_RECLAIM;
643
644 /*
645 * Mlock lost the isolation race with us. Let try_to_unmap()
646 * move the page to the unevictable list.
647 */
648 if (vm_flags & VM_LOCKED)
649 return PAGEREF_RECLAIM;
650
Johannes Weiner645747462010-03-05 13:42:22 -0800651 if (referenced_ptes) {
652 if (PageAnon(page))
653 return PAGEREF_ACTIVATE;
654 /*
655 * All mapped pages start out with page table
656 * references from the instantiating fault, so we need
657 * to look twice if a mapped file page is used more
658 * than once.
659 *
660 * Mark it and spare it for another trip around the
661 * inactive list. Another page table reference will
662 * lead to its activation.
663 *
664 * Note: the mark is set for activated pages as well
665 * so that recently deactivated but used pages are
666 * quickly recovered.
667 */
668 SetPageReferenced(page);
669
670 if (referenced_page)
671 return PAGEREF_ACTIVATE;
672
673 return PAGEREF_KEEP;
674 }
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800675
676 /* Reclaim if clean, defer dirty pages to writeback */
KOSAKI Motohiro2e302442010-10-26 14:21:46 -0700677 if (referenced_page && !PageSwapBacked(page))
Johannes Weiner645747462010-03-05 13:42:22 -0800678 return PAGEREF_RECLAIM_CLEAN;
679
680 return PAGEREF_RECLAIM;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800681}
682
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700683static noinline_for_stack void free_page_list(struct list_head *free_pages)
684{
685 struct pagevec freed_pvec;
686 struct page *page, *tmp;
687
688 pagevec_init(&freed_pvec, 1);
689
690 list_for_each_entry_safe(page, tmp, free_pages, lru) {
691 list_del(&page->lru);
692 if (!pagevec_add(&freed_pvec, page)) {
693 __pagevec_free(&freed_pvec);
694 pagevec_reinit(&freed_pvec);
695 }
696 }
697
698 pagevec_free(&freed_pvec);
699}
700
Nick Piggine2867812008-07-25 19:45:30 -0700701/*
Andrew Morton1742f192006-03-22 00:08:21 -0800702 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 */
Andrew Morton1742f192006-03-22 00:08:21 -0800704static unsigned long shrink_page_list(struct list_head *page_list,
Mel Gorman0e093d992010-10-26 14:21:45 -0700705 struct zone *zone,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700706 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707{
708 LIST_HEAD(ret_pages);
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700709 LIST_HEAD(free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 int pgactivate = 0;
Mel Gorman0e093d992010-10-26 14:21:45 -0700711 unsigned long nr_dirty = 0;
712 unsigned long nr_congested = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800713 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714
715 cond_resched();
716
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 while (!list_empty(page_list)) {
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800718 enum page_references references;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 struct address_space *mapping;
720 struct page *page;
721 int may_enter_fs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
723 cond_resched();
724
725 page = lru_to_page(page_list);
726 list_del(&page->lru);
727
Nick Piggin529ae9a2008-08-02 12:01:03 +0200728 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 goto keep;
730
Nick Piggin725d7042006-09-25 23:30:55 -0700731 VM_BUG_ON(PageActive(page));
Mel Gorman0e093d992010-10-26 14:21:45 -0700732 VM_BUG_ON(page_zone(page) != zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
734 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800735
Nick Pigginb291f002008-10-18 20:26:44 -0700736 if (unlikely(!page_evictable(page, NULL)))
737 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700738
Johannes Weinera6dc60f82009-03-31 15:19:30 -0700739 if (!sc->may_unmap && page_mapped(page))
Christoph Lameter80e43422006-02-11 17:55:53 -0800740 goto keep_locked;
741
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 /* Double the slab pressure for mapped and swapcache pages */
743 if (page_mapped(page) || PageSwapCache(page))
744 sc->nr_scanned++;
745
Andy Whitcroftc661b072007-08-22 14:01:26 -0700746 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
747 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
748
749 if (PageWriteback(page)) {
750 /*
751 * Synchronous reclaim is performed in two passes,
752 * first an asynchronous pass over the list to
753 * start parallel writeback, and a second synchronous
754 * pass to wait for the IO to complete. Wait here
755 * for any page for which writeback has already
756 * started.
757 */
Mel Gormanf3a310b2011-01-13 15:46:00 -0800758 if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) &&
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700759 may_enter_fs)
Andy Whitcroftc661b072007-08-22 14:01:26 -0700760 wait_on_page_writeback(page);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700761 else {
762 unlock_page(page);
763 goto keep_lumpy;
764 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700765 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800767 references = page_check_references(page, sc);
768 switch (references) {
769 case PAGEREF_ACTIVATE:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 goto activate_locked;
Johannes Weiner645747462010-03-05 13:42:22 -0800771 case PAGEREF_KEEP:
772 goto keep_locked;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800773 case PAGEREF_RECLAIM:
774 case PAGEREF_RECLAIM_CLEAN:
775 ; /* try to reclaim the page below */
776 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 /*
779 * Anonymous process memory has backing store?
780 * Try to allocate it some swap space here.
781 */
Nick Pigginb291f002008-10-18 20:26:44 -0700782 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800783 if (!(sc->gfp_mask & __GFP_IO))
784 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800785 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800787 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700788 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
790 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791
792 /*
793 * The page is mapped into the page tables of one or more
794 * processes. Try to unmap it here.
795 */
796 if (page_mapped(page) && mapping) {
Andi Kleen14fa31b2009-09-16 11:50:10 +0200797 switch (try_to_unmap(page, TTU_UNMAP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 case SWAP_FAIL:
799 goto activate_locked;
800 case SWAP_AGAIN:
801 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700802 case SWAP_MLOCK:
803 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 case SWAP_SUCCESS:
805 ; /* try to free the page below */
806 }
807 }
808
809 if (PageDirty(page)) {
Mel Gorman0e093d992010-10-26 14:21:45 -0700810 nr_dirty++;
811
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800812 if (references == PAGEREF_RECLAIM_CLEAN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700814 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800816 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 goto keep_locked;
818
819 /* Page is dirty, try to write it out here */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700820 switch (pageout(page, mapping, sc)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 case PAGE_KEEP:
Mel Gorman0e093d992010-10-26 14:21:45 -0700822 nr_congested++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 goto keep_locked;
824 case PAGE_ACTIVATE:
825 goto activate_locked;
826 case PAGE_SUCCESS:
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700827 if (PageWriteback(page))
828 goto keep_lumpy;
829 if (PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 goto keep;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 /*
833 * A synchronous write - probably a ramdisk. Go
834 * ahead and try to reclaim the page.
835 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200836 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 goto keep;
838 if (PageDirty(page) || PageWriteback(page))
839 goto keep_locked;
840 mapping = page_mapping(page);
841 case PAGE_CLEAN:
842 ; /* try to free the page below */
843 }
844 }
845
846 /*
847 * If the page has buffers, try to free the buffer mappings
848 * associated with this page. If we succeed we try to free
849 * the page as well.
850 *
851 * We do this even if the page is PageDirty().
852 * try_to_release_page() does not perform I/O, but it is
853 * possible for a page to have PageDirty set, but it is actually
854 * clean (all its buffers are clean). This happens if the
855 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700856 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 * try_to_release_page() will discover that cleanness and will
858 * drop the buffers and mark the page clean - it can be freed.
859 *
860 * Rarely, pages can have buffers and no ->mapping. These are
861 * the pages which were not successfully invalidated in
862 * truncate_complete_page(). We try to drop those buffers here
863 * and if that worked, and the page is no longer mapped into
864 * process address space (page_count == 1) it can be freed.
865 * Otherwise, leave the page on the LRU so it is swappable.
866 */
David Howells266cf652009-04-03 16:42:36 +0100867 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 if (!try_to_release_page(page, sc->gfp_mask))
869 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700870 if (!mapping && page_count(page) == 1) {
871 unlock_page(page);
872 if (put_page_testzero(page))
873 goto free_it;
874 else {
875 /*
876 * rare race with speculative reference.
877 * the speculative reference will free
878 * this page shortly, so we may
879 * increment nr_reclaimed here (and
880 * leave it off the LRU).
881 */
882 nr_reclaimed++;
883 continue;
884 }
885 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 }
887
Nick Piggine2867812008-07-25 19:45:30 -0700888 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800889 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890
Nick Piggina978d6f2008-10-18 20:26:58 -0700891 /*
892 * At this point, we have no other references and there is
893 * no way to pick any more up (removed from LRU, removed
894 * from pagecache). Can use non-atomic bitops now (and
895 * we obviously don't have to worry about waking up a process
896 * waiting on the page lock, because there are no references.
897 */
898 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700899free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800900 nr_reclaimed++;
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700901
902 /*
903 * Is there need to periodically free_page_list? It would
904 * appear not as the counts should be low
905 */
906 list_add(&page->lru, &free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 continue;
908
Nick Pigginb291f002008-10-18 20:26:44 -0700909cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800910 if (PageSwapCache(page))
911 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700912 unlock_page(page);
913 putback_lru_page(page);
Mel Gormanf3a310b2011-01-13 15:46:00 -0800914 reset_reclaim_mode(sc);
Nick Pigginb291f002008-10-18 20:26:44 -0700915 continue;
916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700918 /* Not a candidate for swapping, so reclaim swap space. */
919 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800920 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700921 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 SetPageActive(page);
923 pgactivate++;
924keep_locked:
925 unlock_page(page);
926keep:
Mel Gormanf3a310b2011-01-13 15:46:00 -0800927 reset_reclaim_mode(sc);
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700928keep_lumpy:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700930 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 }
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700932
Mel Gorman0e093d992010-10-26 14:21:45 -0700933 /*
934 * Tag a zone as congested if all the dirty pages encountered were
935 * backed by a congested BDI. In this case, reclaimers should just
936 * back off and wait for congestion to clear because further reclaim
937 * will encounter the same problem
938 */
Shaohua Li1dce071e2010-11-11 14:05:17 -0800939 if (nr_dirty == nr_congested && nr_dirty != 0)
Mel Gorman0e093d992010-10-26 14:21:45 -0700940 zone_set_flag(zone, ZONE_CONGESTED);
941
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700942 free_page_list(&free_pages);
943
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 list_splice(&ret_pages, page_list);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700945 count_vm_events(PGACTIVATE, pgactivate);
Andrew Morton05ff5132006-03-22 00:08:20 -0800946 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947}
948
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700949/*
950 * Attempt to remove the specified page from its LRU. Only take this page
951 * if it is of the appropriate PageActive status. Pages which are being
952 * freed elsewhere are also ignored.
953 *
954 * page: page to consider
955 * mode: one of the LRU isolation modes defined above
956 *
957 * returns 0 on success, -ve errno on failure.
958 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700959int __isolate_lru_page(struct page *page, int mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700960{
961 int ret = -EINVAL;
962
963 /* Only take pages on the LRU. */
964 if (!PageLRU(page))
965 return ret;
966
967 /*
968 * When checking the active state, we need to be sure we are
969 * dealing with comparible boolean values. Take the logical not
970 * of each.
971 */
972 if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
973 return ret;
974
Johannes Weiner6c0b1352009-09-21 17:02:59 -0700975 if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700976 return ret;
977
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700978 /*
979 * When this function is being called for lumpy reclaim, we
980 * initially look into all LRU pages, active, inactive and
981 * unevictable; only give shrink_page_list evictable pages.
982 */
983 if (PageUnevictable(page))
984 return ret;
985
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700986 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800987
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700988 if (likely(get_page_unless_zero(page))) {
989 /*
990 * Be careful not to clear PageLRU until after we're
991 * sure the page is not being freed elsewhere -- the
992 * page release code relies on it.
993 */
994 ClearPageLRU(page);
995 ret = 0;
996 }
997
998 return ret;
999}
1000
Christoph Lameter49d2e9c2006-01-08 01:00:48 -08001001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002 * zone->lru_lock is heavily contended. Some of the functions that
1003 * shrink the lists perform better by taking out a batch of pages
1004 * and working on them outside the LRU lock.
1005 *
1006 * For pagecache intensive workloads, this function is the hottest
1007 * spot in the kernel (apart from copy_*_user functions).
1008 *
1009 * Appropriate locks must be held before calling this function.
1010 *
1011 * @nr_to_scan: The number of pages to look through on the list.
1012 * @src: The LRU list to pull pages off.
1013 * @dst: The temp list to put pages on to.
1014 * @scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001015 * @order: The caller's attempted allocation order
1016 * @mode: One of the LRU isolation modes
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001017 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 *
1019 * returns how many pages were moved onto *@dst.
1020 */
Andrew Morton69e05942006-03-22 00:08:19 -08001021static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
1022 struct list_head *src, struct list_head *dst,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001023 unsigned long *scanned, int order, int mode, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024{
Andrew Morton69e05942006-03-22 00:08:19 -08001025 unsigned long nr_taken = 0;
Mel Gormana8a94d12010-08-09 17:19:17 -07001026 unsigned long nr_lumpy_taken = 0;
1027 unsigned long nr_lumpy_dirty = 0;
1028 unsigned long nr_lumpy_failed = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001029 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001031 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001032 struct page *page;
1033 unsigned long pfn;
1034 unsigned long end_pfn;
1035 unsigned long page_pfn;
1036 int zone_id;
1037
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 page = lru_to_page(src);
1039 prefetchw_prev_lru_page(page, src, flags);
1040
Nick Piggin725d7042006-09-25 23:30:55 -07001041 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001042
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001043 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001044 case 0:
1045 list_move(&page->lru, dst);
KAMEZAWA Hiroyuki2ffebca2009-06-17 16:27:21 -07001046 mem_cgroup_del_lru(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001047 nr_taken += hpage_nr_pages(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001048 break;
Nick Piggin46453a62006-03-22 00:07:58 -08001049
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001050 case -EBUSY:
1051 /* else it is being freed elsewhere */
1052 list_move(&page->lru, src);
KAMEZAWA Hiroyuki2ffebca2009-06-17 16:27:21 -07001053 mem_cgroup_rotate_lru_list(page, page_lru(page));
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001054 continue;
1055
1056 default:
1057 BUG();
1058 }
1059
1060 if (!order)
1061 continue;
1062
1063 /*
1064 * Attempt to take all pages in the order aligned region
1065 * surrounding the tag page. Only take those pages of
1066 * the same active state as that tag page. We may safely
1067 * round the target page pfn down to the requested order
1068 * as the mem_map is guarenteed valid out to MAX_ORDER,
1069 * where that page is in a different zone we will detect
1070 * it from its zone id and abort this block scan.
1071 */
1072 zone_id = page_zone_id(page);
1073 page_pfn = page_to_pfn(page);
1074 pfn = page_pfn & ~((1 << order) - 1);
1075 end_pfn = pfn + (1 << order);
1076 for (; pfn < end_pfn; pfn++) {
1077 struct page *cursor_page;
1078
1079 /* The target page is in the block, ignore it. */
1080 if (unlikely(pfn == page_pfn))
1081 continue;
1082
1083 /* Avoid holes within the zone. */
1084 if (unlikely(!pfn_valid_within(pfn)))
1085 break;
1086
1087 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001088
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001089 /* Check that we have not crossed a zone boundary. */
1090 if (unlikely(page_zone_id(cursor_page) != zone_id))
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001091 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001092
1093 /*
1094 * If we don't have enough swap space, reclaiming of
1095 * anon page which don't already have a swap slot is
1096 * pointless.
1097 */
1098 if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001099 !PageSwapCache(cursor_page))
1100 break;
Minchan Kimde2e7562009-09-21 17:01:43 -07001101
KAMEZAWA Hiroyukiee993b12009-06-16 15:33:24 -07001102 if (__isolate_lru_page(cursor_page, mode, file) == 0) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001103 list_move(&cursor_page->lru, dst);
KAMEZAWA Hiroyukicb4cbcf2009-06-23 08:57:55 +09001104 mem_cgroup_del_lru(cursor_page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001105 nr_taken += hpage_nr_pages(page);
Mel Gormana8a94d12010-08-09 17:19:17 -07001106 nr_lumpy_taken++;
1107 if (PageDirty(cursor_page))
1108 nr_lumpy_dirty++;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001109 scan++;
Mel Gormana8a94d12010-08-09 17:19:17 -07001110 } else {
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001111 /* the page is freed already. */
1112 if (!page_count(cursor_page))
1113 continue;
1114 break;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001115 }
1116 }
KOSAKI Motohiro08fc4682010-10-26 14:21:44 -07001117
1118 /* If we break out of the loop above, lumpy reclaim failed */
1119 if (pfn < end_pfn)
1120 nr_lumpy_failed++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 }
1122
1123 *scanned = scan;
Mel Gormana8a94d12010-08-09 17:19:17 -07001124
1125 trace_mm_vmscan_lru_isolate(order,
1126 nr_to_scan, scan,
1127 nr_taken,
1128 nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed,
1129 mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 return nr_taken;
1131}
1132
Balbir Singh66e17072008-02-07 00:13:56 -08001133static unsigned long isolate_pages_global(unsigned long nr,
1134 struct list_head *dst,
1135 unsigned long *scanned, int order,
1136 int mode, struct zone *z,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001137 int active, int file)
Balbir Singh66e17072008-02-07 00:13:56 -08001138{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001139 int lru = LRU_BASE;
Balbir Singh66e17072008-02-07 00:13:56 -08001140 if (active)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001141 lru += LRU_ACTIVE;
1142 if (file)
1143 lru += LRU_FILE;
1144 return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001145 mode, file);
Balbir Singh66e17072008-02-07 00:13:56 -08001146}
1147
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148/*
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001149 * clear_active_flags() is a helper for shrink_active_list(), clearing
1150 * any active bits from the pages in the list.
1151 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001152static unsigned long clear_active_flags(struct list_head *page_list,
1153 unsigned int *count)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001154{
1155 int nr_active = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001156 int lru;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001157 struct page *page;
1158
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001159 list_for_each_entry(page, page_list, lru) {
Rik van Riel2c888cf2011-01-13 15:47:13 -08001160 int numpages = hpage_nr_pages(page);
Johannes Weiner401a8e12009-09-21 17:02:58 -07001161 lru = page_lru_base_type(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001162 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001163 lru += LRU_ACTIVE;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001164 ClearPageActive(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001165 nr_active += numpages;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001166 }
Mel Gorman1489fa12010-08-09 17:19:33 -07001167 if (count)
Rik van Riel2c888cf2011-01-13 15:47:13 -08001168 count[lru] += numpages;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001169 }
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001170
1171 return nr_active;
1172}
1173
Nick Piggin62695a82008-10-18 20:26:09 -07001174/**
1175 * isolate_lru_page - tries to isolate a page from its LRU list
1176 * @page: page to isolate from its LRU list
1177 *
1178 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1179 * vmstat statistic corresponding to whatever LRU list the page was on.
1180 *
1181 * Returns 0 if the page was removed from an LRU list.
1182 * Returns -EBUSY if the page was not on an LRU list.
1183 *
1184 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001185 * the active list, it will have PageActive set. If it was found on
1186 * the unevictable list, it will have the PageUnevictable bit set. That flag
1187 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001188 *
1189 * The vmstat statistic corresponding to the list on which the page was
1190 * found will be decremented.
1191 *
1192 * Restrictions:
1193 * (1) Must be called with an elevated refcount on the page. This is a
1194 * fundamentnal difference from isolate_lru_pages (which is called
1195 * without a stable reference).
1196 * (2) the lru_lock must not be held.
1197 * (3) interrupts must be enabled.
1198 */
1199int isolate_lru_page(struct page *page)
1200{
1201 int ret = -EBUSY;
1202
1203 if (PageLRU(page)) {
1204 struct zone *zone = page_zone(page);
1205
1206 spin_lock_irq(&zone->lru_lock);
1207 if (PageLRU(page) && get_page_unless_zero(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001208 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001209 ret = 0;
1210 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001211
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001212 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001213 }
1214 spin_unlock_irq(&zone->lru_lock);
1215 }
1216 return ret;
1217}
1218
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001219/*
Rik van Riel35cd7812009-09-21 17:01:38 -07001220 * Are there way too many processes in the direct reclaim path already?
1221 */
1222static int too_many_isolated(struct zone *zone, int file,
1223 struct scan_control *sc)
1224{
1225 unsigned long inactive, isolated;
1226
1227 if (current_is_kswapd())
1228 return 0;
1229
1230 if (!scanning_global_lru(sc))
1231 return 0;
1232
1233 if (file) {
1234 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1235 isolated = zone_page_state(zone, NR_ISOLATED_FILE);
1236 } else {
1237 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1238 isolated = zone_page_state(zone, NR_ISOLATED_ANON);
1239 }
1240
1241 return isolated > inactive;
1242}
1243
1244/*
Mel Gorman66635622010-08-09 17:19:30 -07001245 * TODO: Try merging with migrations version of putback_lru_pages
1246 */
1247static noinline_for_stack void
Mel Gorman1489fa12010-08-09 17:19:33 -07001248putback_lru_pages(struct zone *zone, struct scan_control *sc,
Mel Gorman66635622010-08-09 17:19:30 -07001249 unsigned long nr_anon, unsigned long nr_file,
1250 struct list_head *page_list)
1251{
1252 struct page *page;
1253 struct pagevec pvec;
Mel Gorman1489fa12010-08-09 17:19:33 -07001254 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Mel Gorman66635622010-08-09 17:19:30 -07001255
1256 pagevec_init(&pvec, 1);
1257
1258 /*
1259 * Put back any unfreeable pages.
1260 */
1261 spin_lock(&zone->lru_lock);
1262 while (!list_empty(page_list)) {
1263 int lru;
1264 page = lru_to_page(page_list);
1265 VM_BUG_ON(PageLRU(page));
1266 list_del(&page->lru);
1267 if (unlikely(!page_evictable(page, NULL))) {
1268 spin_unlock_irq(&zone->lru_lock);
1269 putback_lru_page(page);
1270 spin_lock_irq(&zone->lru_lock);
1271 continue;
1272 }
Linus Torvalds7a608572011-01-17 14:42:19 -08001273 SetPageLRU(page);
Mel Gorman66635622010-08-09 17:19:30 -07001274 lru = page_lru(page);
Linus Torvalds7a608572011-01-17 14:42:19 -08001275 add_page_to_lru_list(zone, page, lru);
Mel Gorman66635622010-08-09 17:19:30 -07001276 if (is_active_lru(lru)) {
1277 int file = is_file_lru(lru);
Rik van Riel9992af12011-01-13 15:47:13 -08001278 int numpages = hpage_nr_pages(page);
1279 reclaim_stat->recent_rotated[file] += numpages;
Mel Gorman66635622010-08-09 17:19:30 -07001280 }
1281 if (!pagevec_add(&pvec, page)) {
1282 spin_unlock_irq(&zone->lru_lock);
1283 __pagevec_release(&pvec);
1284 spin_lock_irq(&zone->lru_lock);
1285 }
1286 }
1287 __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
1288 __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
1289
1290 spin_unlock_irq(&zone->lru_lock);
1291 pagevec_release(&pvec);
1292}
1293
Mel Gorman1489fa12010-08-09 17:19:33 -07001294static noinline_for_stack void update_isolated_counts(struct zone *zone,
1295 struct scan_control *sc,
1296 unsigned long *nr_anon,
1297 unsigned long *nr_file,
1298 struct list_head *isolated_list)
1299{
1300 unsigned long nr_active;
1301 unsigned int count[NR_LRU_LISTS] = { 0, };
1302 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
1303
1304 nr_active = clear_active_flags(isolated_list, count);
1305 __count_vm_events(PGDEACTIVATE, nr_active);
1306
1307 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1308 -count[LRU_ACTIVE_FILE]);
1309 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1310 -count[LRU_INACTIVE_FILE]);
1311 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1312 -count[LRU_ACTIVE_ANON]);
1313 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1314 -count[LRU_INACTIVE_ANON]);
1315
1316 *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
1317 *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
1318 __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon);
1319 __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file);
1320
1321 reclaim_stat->recent_scanned[0] += *nr_anon;
1322 reclaim_stat->recent_scanned[1] += *nr_file;
1323}
1324
Mel Gorman66635622010-08-09 17:19:30 -07001325/*
Wu Fengguange31f36982010-08-09 17:20:01 -07001326 * Returns true if the caller should wait to clean dirty/writeback pages.
1327 *
1328 * If we are direct reclaiming for contiguous pages and we do not reclaim
1329 * everything in the list, try again and wait for writeback IO to complete.
1330 * This will stall high-order allocations noticeably. Only do that when really
1331 * need to free the pages under high memory pressure.
1332 */
1333static inline bool should_reclaim_stall(unsigned long nr_taken,
1334 unsigned long nr_freed,
1335 int priority,
1336 struct scan_control *sc)
1337{
1338 int lumpy_stall_priority;
1339
1340 /* kswapd should not stall on sync IO */
1341 if (current_is_kswapd())
1342 return false;
1343
1344 /* Only stall on lumpy reclaim */
Mel Gormanf3a310b2011-01-13 15:46:00 -08001345 if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
Wu Fengguange31f36982010-08-09 17:20:01 -07001346 return false;
1347
1348 /* If we have relaimed everything on the isolated list, no stall */
1349 if (nr_freed == nr_taken)
1350 return false;
1351
1352 /*
1353 * For high-order allocations, there are two stall thresholds.
1354 * High-cost allocations stall immediately where as lower
1355 * order allocations such as stacks require the scanning
1356 * priority to be much higher before stalling.
1357 */
1358 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1359 lumpy_stall_priority = DEF_PRIORITY;
1360 else
1361 lumpy_stall_priority = DEF_PRIORITY / 3;
1362
1363 return priority <= lumpy_stall_priority;
1364}
1365
1366/*
Andrew Morton1742f192006-03-22 00:08:21 -08001367 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1368 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 */
Mel Gorman66635622010-08-09 17:19:30 -07001370static noinline_for_stack unsigned long
1371shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
1372 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373{
1374 LIST_HEAD(page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001375 unsigned long nr_scanned;
Andrew Morton05ff5132006-03-22 00:08:20 -08001376 unsigned long nr_reclaimed = 0;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001377 unsigned long nr_taken;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001378 unsigned long nr_anon;
1379 unsigned long nr_file;
KOSAKI Motohiro78dc5832009-06-16 15:31:40 -07001380
Rik van Riel35cd7812009-09-21 17:01:38 -07001381 while (unlikely(too_many_isolated(zone, file, sc))) {
KOSAKI Motohiro58355c72009-10-26 16:49:35 -07001382 congestion_wait(BLK_RW_ASYNC, HZ/10);
Rik van Riel35cd7812009-09-21 17:01:38 -07001383
1384 /* We are about to die and free our memory. Return now. */
1385 if (fatal_signal_pending(current))
1386 return SWAP_CLUSTER_MAX;
1387 }
1388
Mel Gormanf3a310b2011-01-13 15:46:00 -08001389 set_reclaim_mode(priority, sc, false);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 lru_add_drain();
1391 spin_lock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001393 if (scanning_global_lru(sc)) {
1394 nr_taken = isolate_pages_global(nr_to_scan,
1395 &page_list, &nr_scanned, sc->order,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001396 sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
Mel Gorman3e7d3442011-01-13 15:45:56 -08001397 ISOLATE_BOTH : ISOLATE_INACTIVE,
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001398 zone, 0, file);
1399 zone->pages_scanned += nr_scanned;
KOSAKI Motohirob35ea172009-09-21 17:01:36 -07001400 if (current_is_kswapd())
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001401 __count_zone_vm_events(PGSCAN_KSWAPD, zone,
1402 nr_scanned);
1403 else
1404 __count_zone_vm_events(PGSCAN_DIRECT, zone,
1405 nr_scanned);
1406 } else {
1407 nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
1408 &page_list, &nr_scanned, sc->order,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001409 sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ?
Mel Gorman3e7d3442011-01-13 15:45:56 -08001410 ISOLATE_BOTH : ISOLATE_INACTIVE,
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001411 zone, sc->mem_cgroup,
1412 0, file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 /*
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001414 * mem_cgroup_isolate_pages() keeps track of
1415 * scanned pages on its own.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 */
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001417 }
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001418
Mel Gorman66635622010-08-09 17:19:30 -07001419 if (nr_taken == 0) {
1420 spin_unlock_irq(&zone->lru_lock);
1421 return 0;
1422 }
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001423
Mel Gorman1489fa12010-08-09 17:19:33 -07001424 update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001425
1426 spin_unlock_irq(&zone->lru_lock);
1427
Mel Gorman0e093d992010-10-26 14:21:45 -07001428 nr_reclaimed = shrink_page_list(&page_list, zone, sc);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001429
Wu Fengguange31f36982010-08-09 17:20:01 -07001430 /* Check if we should syncronously wait for writeback */
1431 if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
Mel Gormanf3a310b2011-01-13 15:46:00 -08001432 set_reclaim_mode(priority, sc, true);
Mel Gorman0e093d992010-10-26 14:21:45 -07001433 nr_reclaimed += shrink_page_list(&page_list, zone, sc);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001434 }
1435
1436 local_irq_disable();
1437 if (current_is_kswapd())
1438 __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
1439 __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
1440
Mel Gorman1489fa12010-08-09 17:19:33 -07001441 putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
Mel Gormane11da5b2010-10-26 14:21:40 -07001442
1443 trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
1444 zone_idx(zone),
1445 nr_scanned, nr_reclaimed,
1446 priority,
Mel Gormanf3a310b2011-01-13 15:46:00 -08001447 trace_shrink_flags(file, sc->reclaim_mode));
Andrew Morton05ff5132006-03-22 00:08:20 -08001448 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449}
1450
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001451/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 * This moves pages from the active list to the inactive list.
1453 *
1454 * We move them the other way if the page is referenced by one or more
1455 * processes, from rmap.
1456 *
1457 * If the pages are mostly unmapped, the processing is fast and it is
1458 * appropriate to hold zone->lru_lock across the whole operation. But if
1459 * the pages are mapped, the processing is slow (page_referenced()) so we
1460 * should drop zone->lru_lock around each page. It's impossible to balance
1461 * this, so instead we remove the pages from the LRU while processing them.
1462 * It is safe to rely on PG_active against the non-LRU pages in here because
1463 * nobody will play with that bit on a non-LRU page.
1464 *
1465 * The downside is that we have to touch page->_count against each page.
1466 * But we had to alter page->flags anyway.
1467 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001468
Wu Fengguang3eb41402009-06-16 15:33:13 -07001469static void move_active_pages_to_lru(struct zone *zone,
1470 struct list_head *list,
1471 enum lru_list lru)
1472{
1473 unsigned long pgmoved = 0;
1474 struct pagevec pvec;
1475 struct page *page;
1476
1477 pagevec_init(&pvec, 1);
1478
1479 while (!list_empty(list)) {
1480 page = lru_to_page(list);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001481
1482 VM_BUG_ON(PageLRU(page));
1483 SetPageLRU(page);
1484
Wu Fengguang3eb41402009-06-16 15:33:13 -07001485 list_move(&page->lru, &zone->lru[lru].list);
1486 mem_cgroup_add_lru_list(page, lru);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001487 pgmoved += hpage_nr_pages(page);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001488
1489 if (!pagevec_add(&pvec, page) || list_empty(list)) {
1490 spin_unlock_irq(&zone->lru_lock);
1491 if (buffer_heads_over_limit)
1492 pagevec_strip(&pvec);
1493 __pagevec_release(&pvec);
1494 spin_lock_irq(&zone->lru_lock);
1495 }
1496 }
1497 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
1498 if (!is_active_lru(lru))
1499 __count_vm_events(PGDEACTIVATE, pgmoved);
1500}
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001501
Andrew Morton1742f192006-03-22 00:08:21 -08001502static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001503 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504{
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001505 unsigned long nr_taken;
Andrew Morton69e05942006-03-22 00:08:19 -08001506 unsigned long pgscanned;
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -07001507 unsigned long vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 LIST_HEAD(l_hold); /* The pages which were snipped off */
Wu Fengguang8cab4752009-06-16 15:33:12 -07001509 LIST_HEAD(l_active);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001510 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 struct page *page;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001512 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001513 unsigned long nr_rotated = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514
1515 lru_add_drain();
1516 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001517 if (scanning_global_lru(sc)) {
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001518 nr_taken = isolate_pages_global(nr_pages, &l_hold,
1519 &pgscanned, sc->order,
1520 ISOLATE_ACTIVE, zone,
1521 1, file);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001522 zone->pages_scanned += pgscanned;
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001523 } else {
1524 nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
1525 &pgscanned, sc->order,
1526 ISOLATE_ACTIVE, zone,
1527 sc->mem_cgroup, 1, file);
1528 /*
1529 * mem_cgroup_isolate_pages() keeps track of
1530 * scanned pages on its own.
1531 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001532 }
Johannes Weiner8b25c6d2010-05-24 14:32:40 -07001533
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001534 reclaim_stat->recent_scanned[file] += nr_taken;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001535
Wu Fengguang3eb41402009-06-16 15:33:13 -07001536 __count_zone_vm_events(PGREFILL, zone, pgscanned);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001537 if (file)
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001538 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001539 else
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001540 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001541 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 spin_unlock_irq(&zone->lru_lock);
1543
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 while (!list_empty(&l_hold)) {
1545 cond_resched();
1546 page = lru_to_page(&l_hold);
1547 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001548
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001549 if (unlikely(!page_evictable(page, NULL))) {
1550 putback_lru_page(page);
1551 continue;
1552 }
1553
Johannes Weiner645747462010-03-05 13:42:22 -08001554 if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
Rik van Riel9992af12011-01-13 15:47:13 -08001555 nr_rotated += hpage_nr_pages(page);
Wu Fengguang8cab4752009-06-16 15:33:12 -07001556 /*
1557 * Identify referenced, file-backed active pages and
1558 * give them one more trip around the active list. So
1559 * that executable code get better chances to stay in
1560 * memory under moderate memory pressure. Anon pages
1561 * are not likely to be evicted by use-once streaming
1562 * IO, plus JVM can create lots of anon VM_EXEC pages,
1563 * so we ignore them here.
1564 */
Wu Fengguang41e20982009-10-26 16:49:53 -07001565 if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
Wu Fengguang8cab4752009-06-16 15:33:12 -07001566 list_add(&page->lru, &l_active);
1567 continue;
1568 }
1569 }
Rik van Riel7e9cd482008-10-18 20:26:35 -07001570
KOSAKI Motohiro5205e562009-09-21 17:01:44 -07001571 ClearPageActive(page); /* we are de-activating */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 list_add(&page->lru, &l_inactive);
1573 }
1574
Andrew Mortonb5557492009-01-06 14:40:13 -08001575 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001576 * Move pages back to the lru list.
Andrew Mortonb5557492009-01-06 14:40:13 -08001577 */
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001578 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001579 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001580 * Count referenced pages from currently used mappings as rotated,
1581 * even though only some of them are actually re-activated. This
1582 * helps balance scan pressure between file and anonymous pages in
1583 * get_scan_ratio.
Rik van Riel7e9cd482008-10-18 20:26:35 -07001584 */
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001585 reclaim_stat->recent_rotated[file] += nr_rotated;
Rik van Riel556adec2008-10-18 20:26:34 -07001586
Wu Fengguang3eb41402009-06-16 15:33:13 -07001587 move_active_pages_to_lru(zone, &l_active,
1588 LRU_ACTIVE + file * LRU_FILE);
1589 move_active_pages_to_lru(zone, &l_inactive,
1590 LRU_BASE + file * LRU_FILE);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001591 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001592 spin_unlock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593}
1594
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001595#ifdef CONFIG_SWAP
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001596static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001597{
1598 unsigned long active, inactive;
1599
1600 active = zone_page_state(zone, NR_ACTIVE_ANON);
1601 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1602
1603 if (inactive * zone->inactive_ratio < active)
1604 return 1;
1605
1606 return 0;
1607}
1608
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001609/**
1610 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1611 * @zone: zone to check
1612 * @sc: scan control of this context
1613 *
1614 * Returns true if the zone does not have enough inactive anon pages,
1615 * meaning some active anon pages need to be deactivated.
1616 */
1617static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc)
1618{
1619 int low;
1620
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001621 /*
1622 * If we don't have swap space, anonymous page deactivation
1623 * is pointless.
1624 */
1625 if (!total_swap_pages)
1626 return 0;
1627
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001628 if (scanning_global_lru(sc))
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001629 low = inactive_anon_is_low_global(zone);
1630 else
KOSAKI Motohiroc772be92009-01-07 18:08:25 -08001631 low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001632 return low;
1633}
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001634#else
1635static inline int inactive_anon_is_low(struct zone *zone,
1636 struct scan_control *sc)
1637{
1638 return 0;
1639}
1640#endif
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001641
Rik van Riel56e49d22009-06-16 15:32:28 -07001642static int inactive_file_is_low_global(struct zone *zone)
1643{
1644 unsigned long active, inactive;
1645
1646 active = zone_page_state(zone, NR_ACTIVE_FILE);
1647 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1648
1649 return (active > inactive);
1650}
1651
1652/**
1653 * inactive_file_is_low - check if file pages need to be deactivated
1654 * @zone: zone to check
1655 * @sc: scan control of this context
1656 *
1657 * When the system is doing streaming IO, memory pressure here
1658 * ensures that active file pages get deactivated, until more
1659 * than half of the file pages are on the inactive list.
1660 *
1661 * Once we get to that situation, protect the system's working
1662 * set from being evicted by disabling active file page aging.
1663 *
1664 * This uses a different ratio than the anonymous pages, because
1665 * the page cache uses a use-once replacement algorithm.
1666 */
1667static int inactive_file_is_low(struct zone *zone, struct scan_control *sc)
1668{
1669 int low;
1670
1671 if (scanning_global_lru(sc))
1672 low = inactive_file_is_low_global(zone);
1673 else
1674 low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup);
1675 return low;
1676}
1677
Rik van Rielb39415b2009-12-14 17:59:48 -08001678static int inactive_list_is_low(struct zone *zone, struct scan_control *sc,
1679 int file)
1680{
1681 if (file)
1682 return inactive_file_is_low(zone, sc);
1683 else
1684 return inactive_anon_is_low(zone, sc);
1685}
1686
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001687static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Christoph Lameterb69408e2008-10-18 20:26:14 -07001688 struct zone *zone, struct scan_control *sc, int priority)
1689{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001690 int file = is_file_lru(lru);
1691
Rik van Rielb39415b2009-12-14 17:59:48 -08001692 if (is_active_lru(lru)) {
1693 if (inactive_list_is_low(zone, sc, file))
1694 shrink_active_list(nr_to_scan, zone, sc, priority, file);
Rik van Riel556adec2008-10-18 20:26:34 -07001695 return 0;
1696 }
1697
Rik van Riel33c120e2008-10-18 20:26:36 -07001698 return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001699}
1700
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701/*
Shaohua Li76a33fc2010-05-24 14:32:36 -07001702 * Smallish @nr_to_scan's are deposited in @nr_saved_scan,
1703 * until we collected @swap_cluster_max pages to scan.
1704 */
1705static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
1706 unsigned long *nr_saved_scan)
1707{
1708 unsigned long nr;
1709
1710 *nr_saved_scan += nr_to_scan;
1711 nr = *nr_saved_scan;
1712
1713 if (nr >= SWAP_CLUSTER_MAX)
1714 *nr_saved_scan = 0;
1715 else
1716 nr = 0;
1717
1718 return nr;
1719}
1720
1721/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001722 * Determine how aggressively the anon and file LRU lists should be
1723 * scanned. The relative value of each set of LRU lists is determined
1724 * by looking at the fraction of the pages scanned we did rotate back
1725 * onto the active list instead of evict.
1726 *
Shaohua Li76a33fc2010-05-24 14:32:36 -07001727 * nr[0] = anon pages to scan; nr[1] = file pages to scan
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001728 */
Shaohua Li76a33fc2010-05-24 14:32:36 -07001729static void get_scan_count(struct zone *zone, struct scan_control *sc,
1730 unsigned long *nr, int priority)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001731{
1732 unsigned long anon, file, free;
1733 unsigned long anon_prio, file_prio;
1734 unsigned long ap, fp;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001735 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Shaohua Li76a33fc2010-05-24 14:32:36 -07001736 u64 fraction[2], denominator;
1737 enum lru_list l;
1738 int noswap = 0;
1739
1740 /* If we have no swap space, do not bother scanning anon pages. */
1741 if (!sc->may_swap || (nr_swap_pages <= 0)) {
1742 noswap = 1;
1743 fraction[0] = 0;
1744 fraction[1] = 1;
1745 denominator = 1;
1746 goto out;
1747 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001748
Vincent Li0b217672009-09-21 17:03:09 -07001749 anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +
1750 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON);
1751 file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +
1752 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
Hugh Dickinsb9627162009-01-06 14:39:41 -08001753
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001754 if (scanning_global_lru(sc)) {
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001755 free = zone_page_state(zone, NR_FREE_PAGES);
1756 /* If we have very few page cache pages,
1757 force-scan anon pages. */
Mel Gorman41858962009-06-16 15:32:12 -07001758 if (unlikely(file + free <= high_wmark_pages(zone))) {
Shaohua Li76a33fc2010-05-24 14:32:36 -07001759 fraction[0] = 1;
1760 fraction[1] = 0;
1761 denominator = 1;
1762 goto out;
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001763 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001764 }
1765
1766 /*
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001767 * With swappiness at 100, anonymous and file have the same priority.
1768 * This scanning priority is essentially the inverse of IO cost.
1769 */
1770 anon_prio = sc->swappiness;
1771 file_prio = 200 - sc->swappiness;
1772
1773 /*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001774 * OK, so we have swap space and a fair amount of page cache
1775 * pages. We use the recently rotated / recently scanned
1776 * ratios to determine how valuable each cache is.
1777 *
1778 * Because workloads change over time (and to avoid overflow)
1779 * we keep these statistics as a floating average, which ends
1780 * up weighing recent references more than old ones.
1781 *
1782 * anon in [0], file in [1]
1783 */
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001784 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001785 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001786 reclaim_stat->recent_scanned[0] /= 2;
1787 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001788 }
1789
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001790 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001791 reclaim_stat->recent_scanned[1] /= 2;
1792 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001793 }
1794
1795 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001796 * The amount of pressure on anon vs file pages is inversely
1797 * proportional to the fraction of recently scanned pages on
1798 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001799 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001800 ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
1801 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001802
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001803 fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
1804 fp /= reclaim_stat->recent_rotated[1] + 1;
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001805 spin_unlock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001806
Shaohua Li76a33fc2010-05-24 14:32:36 -07001807 fraction[0] = ap;
1808 fraction[1] = fp;
1809 denominator = ap + fp + 1;
1810out:
1811 for_each_evictable_lru(l) {
1812 int file = is_file_lru(l);
1813 unsigned long scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001814
Shaohua Li76a33fc2010-05-24 14:32:36 -07001815 scan = zone_nr_lru_pages(zone, sc, l);
1816 if (priority || noswap) {
1817 scan >>= priority;
1818 scan = div64_u64(scan * fraction[file], denominator);
1819 }
1820 nr[l] = nr_scan_try_batch(scan,
1821 &reclaim_stat->nr_saved_scan[l]);
1822 }
Wu Fengguang6e08a362009-06-16 15:32:29 -07001823}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001824
1825/*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001826 * Reclaim/compaction depends on a number of pages being freed. To avoid
1827 * disruption to the system, a small number of order-0 pages continue to be
1828 * rotated and reclaimed in the normal fashion. However, by the time we get
1829 * back to the allocator and call try_to_compact_zone(), we ensure that
1830 * there are enough free pages for it to be likely successful
1831 */
1832static inline bool should_continue_reclaim(struct zone *zone,
1833 unsigned long nr_reclaimed,
1834 unsigned long nr_scanned,
1835 struct scan_control *sc)
1836{
1837 unsigned long pages_for_compaction;
1838 unsigned long inactive_lru_pages;
1839
1840 /* If not in reclaim/compaction mode, stop */
Mel Gormanf3a310b2011-01-13 15:46:00 -08001841 if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001842 return false;
1843
1844 /*
1845 * If we failed to reclaim and have scanned the full list, stop.
1846 * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far
1847 * faster but obviously would be less likely to succeed
1848 * allocation. If this is desirable, use GFP_REPEAT to decide
1849 * if both reclaimed and scanned should be checked or just
1850 * reclaimed
1851 */
1852 if (!nr_reclaimed && !nr_scanned)
1853 return false;
1854
1855 /*
1856 * If we have not reclaimed enough pages for compaction and the
1857 * inactive lists are large enough, continue reclaiming
1858 */
1859 pages_for_compaction = (2UL << sc->order);
1860 inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) +
1861 zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
1862 if (sc->nr_reclaimed < pages_for_compaction &&
1863 inactive_lru_pages > pages_for_compaction)
1864 return true;
1865
1866 /* If compaction would go ahead or the allocation would succeed, stop */
1867 switch (compaction_suitable(zone, sc->order)) {
1868 case COMPACT_PARTIAL:
1869 case COMPACT_CONTINUE:
1870 return false;
1871 default:
1872 return true;
1873 }
1874}
1875
1876/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1878 */
Rik van Riela79311c2009-01-06 14:40:01 -08001879static void shrink_zone(int priority, struct zone *zone,
Andrew Morton05ff5132006-03-22 00:08:20 -08001880 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881{
Christoph Lameterb69408e2008-10-18 20:26:14 -07001882 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08001883 unsigned long nr_to_scan;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001884 enum lru_list l;
Johannes Weinerf0fdc5e2011-02-10 15:01:34 -08001885 unsigned long nr_reclaimed, nr_scanned;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08001886 unsigned long nr_to_reclaim = sc->nr_to_reclaim;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887
Mel Gorman3e7d3442011-01-13 15:45:56 -08001888restart:
1889 nr_reclaimed = 0;
Johannes Weinerf0fdc5e2011-02-10 15:01:34 -08001890 nr_scanned = sc->nr_scanned;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001891 get_scan_count(zone, sc, nr, priority);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001892
Rik van Riel556adec2008-10-18 20:26:34 -07001893 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1894 nr[LRU_INACTIVE_FILE]) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001895 for_each_evictable_lru(l) {
Christoph Lameterb69408e2008-10-18 20:26:14 -07001896 if (nr[l]) {
KOSAKI Motohiroece74b22009-12-14 17:59:14 -08001897 nr_to_scan = min_t(unsigned long,
1898 nr[l], SWAP_CLUSTER_MAX);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001899 nr[l] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001901 nr_reclaimed += shrink_list(l, nr_to_scan,
1902 zone, sc, priority);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001903 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904 }
Rik van Riela79311c2009-01-06 14:40:01 -08001905 /*
1906 * On large memory systems, scan >> priority can become
1907 * really large. This is fine for the starting priority;
1908 * we want to put equal scanning pressure on each zone.
1909 * However, if the VM has a harder time of freeing pages,
1910 * with multiple processes reclaiming pages, the total
1911 * freeing target can get unreasonably large.
1912 */
KOSAKI Motohiro338fde92009-12-14 17:59:15 -08001913 if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
Rik van Riela79311c2009-01-06 14:40:01 -08001914 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915 }
Mel Gorman3e7d3442011-01-13 15:45:56 -08001916 sc->nr_reclaimed += nr_reclaimed;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001917
Rik van Riel556adec2008-10-18 20:26:34 -07001918 /*
1919 * Even if we did not try to evict anon pages at all, we want to
1920 * rebalance the anon lru active/inactive ratio.
1921 */
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001922 if (inactive_anon_is_low(zone, sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001923 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1924
Mel Gorman3e7d3442011-01-13 15:45:56 -08001925 /* reclaim/compaction might need reclaim to continue */
1926 if (should_continue_reclaim(zone, nr_reclaimed,
1927 sc->nr_scanned - nr_scanned, sc))
1928 goto restart;
1929
Andrew Morton232ea4d2007-02-28 20:13:21 -08001930 throttle_vm_writeout(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931}
1932
1933/*
1934 * This is the direct reclaim path, for page-allocating processes. We only
1935 * try to reclaim pages from zones which will satisfy the caller's allocation
1936 * request.
1937 *
Mel Gorman41858962009-06-16 15:32:12 -07001938 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
1939 * Because:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
1941 * allocation or
Mel Gorman41858962009-06-16 15:32:12 -07001942 * b) The target zone may be at high_wmark_pages(zone) but the lower zones
1943 * must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
1944 * zone defense algorithm.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 * If a zone is deemed to be full of pinned pages then just give it a light
1947 * scan then give up on it.
1948 */
Minchan Kimd1908362010-09-22 13:05:01 -07001949static void shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08001950 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951{
Mel Gormandd1a2392008-04-28 02:12:17 -07001952 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001953 struct zone *zone;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001954
Mel Gormand4debc62010-08-09 17:19:29 -07001955 for_each_zone_zonelist_nodemask(zone, z, zonelist,
1956 gfp_zone(sc->gfp_mask), sc->nodemask) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08001957 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001959 /*
1960 * Take care memory controller reclaiming has small influence
1961 * to global LRU.
1962 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08001963 if (scanning_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001964 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1965 continue;
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08001966 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001967 continue; /* Let kswapd poll it */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001968 }
Nick Piggin408d8542006-09-25 23:31:27 -07001969
Rik van Riela79311c2009-01-06 14:40:01 -08001970 shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 }
Minchan Kimd1908362010-09-22 13:05:01 -07001972}
1973
1974static bool zone_reclaimable(struct zone *zone)
1975{
1976 return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
1977}
1978
1979/*
1980 * As hibernation is going on, kswapd is freezed so that it can't mark
1981 * the zone into all_unreclaimable. It can't handle OOM during hibernation.
1982 * So let's check zone's unreclaimable in direct reclaim as well as kswapd.
1983 */
1984static bool all_unreclaimable(struct zonelist *zonelist,
1985 struct scan_control *sc)
1986{
1987 struct zoneref *z;
1988 struct zone *zone;
1989 bool all_unreclaimable = true;
1990
1991 for_each_zone_zonelist_nodemask(zone, z, zonelist,
1992 gfp_zone(sc->gfp_mask), sc->nodemask) {
1993 if (!populated_zone(zone))
1994 continue;
1995 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1996 continue;
1997 if (zone_reclaimable(zone)) {
1998 all_unreclaimable = false;
1999 break;
2000 }
2001 }
2002
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002003 return all_unreclaimable;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002005
Linus Torvalds1da177e2005-04-16 15:20:36 -07002006/*
2007 * This is the main entry point to direct page reclaim.
2008 *
2009 * If a full scan of the inactive list fails to free enough memory then we
2010 * are "out of memory" and something needs to be killed.
2011 *
2012 * If the caller is !__GFP_FS then the probability of a failure is reasonably
2013 * high - the zone may be full of dirty or under-writeback pages, which this
Jens Axboe5b0830c2009-09-23 19:37:09 +02002014 * caller can't do much about. We kick the writeback threads and take explicit
2015 * naps in the hope that some of these pages can be written. But if the
2016 * allocating task holds filesystem locks which prevent writeout this might not
2017 * work, and the allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07002018 *
2019 * returns: 0, if no pages reclaimed
2020 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021 */
Mel Gormandac1d272008-04-28 02:12:12 -07002022static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Mel Gormandd1a2392008-04-28 02:12:17 -07002023 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024{
2025 int priority;
Andrew Morton69e05942006-03-22 00:08:19 -08002026 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027 struct reclaim_state *reclaim_state = current->reclaim_state;
Mel Gormandd1a2392008-04-28 02:12:17 -07002028 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002029 struct zone *zone;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002030 unsigned long writeback_threshold;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002031
Miao Xiec0ff7452010-05-24 14:32:08 -07002032 get_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002033 delayacct_freepages_start();
2034
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08002035 if (scanning_global_lru(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002036 count_vm_event(ALLOCSTALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037
2038 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08002039 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002040 if (!priority)
2041 disable_swap_token();
Minchan Kimd1908362010-09-22 13:05:01 -07002042 shrink_zones(priority, zonelist, sc);
Balbir Singh66e17072008-02-07 00:13:56 -08002043 /*
2044 * Don't shrink slabs when reclaiming memory from
2045 * over limit cgroups
2046 */
KAMEZAWA Hiroyukie72e2bd2009-01-07 18:08:23 -08002047 if (scanning_global_lru(sc)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002048 unsigned long lru_pages = 0;
Mel Gormand4debc62010-08-09 17:19:29 -07002049 for_each_zone_zonelist(zone, z, zonelist,
2050 gfp_zone(sc->gfp_mask)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002051 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2052 continue;
2053
2054 lru_pages += zone_reclaimable_pages(zone);
2055 }
2056
Mel Gormandd1a2392008-04-28 02:12:17 -07002057 shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002058 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08002059 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002060 reclaim_state->reclaimed_slab = 0;
2061 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062 }
Balbir Singh66e17072008-02-07 00:13:56 -08002063 total_scanned += sc->nr_scanned;
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002064 if (sc->nr_reclaimed >= sc->nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066
2067 /*
2068 * Try to write back as many pages as we just scanned. This
2069 * tends to cause slow streaming writers to write data to the
2070 * disk smoothly, at the dirtying rate, which is nice. But
2071 * that's undesirable in laptop mode, where we *want* lumpy
2072 * writeout. So in laptop mode, write out the whole world.
2073 */
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002074 writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
2075 if (total_scanned > writeback_threshold) {
Jens Axboe03ba3782009-09-09 09:08:54 +02002076 wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
Balbir Singh66e17072008-02-07 00:13:56 -08002077 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 }
2079
2080 /* Take a nap, wait for some writeback to complete */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002081 if (!sc->hibernation_mode && sc->nr_scanned &&
Mel Gorman0e093d992010-10-26 14:21:45 -07002082 priority < DEF_PRIORITY - 2) {
2083 struct zone *preferred_zone;
2084
2085 first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
David Rientjesf33261d2011-01-25 15:07:20 -08002086 &cpuset_current_mems_allowed,
2087 &preferred_zone);
Mel Gorman0e093d992010-10-26 14:21:45 -07002088 wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
2089 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 }
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002091
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092out:
Keika Kobayashi873b4772008-07-25 01:48:52 -07002093 delayacct_freepages_end();
Miao Xiec0ff7452010-05-24 14:32:08 -07002094 put_mems_allowed();
Keika Kobayashi873b4772008-07-25 01:48:52 -07002095
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002096 if (sc->nr_reclaimed)
2097 return sc->nr_reclaimed;
2098
2099 /* top priority shrink_zones still had more to do? don't OOM, then */
Minchan Kimd1908362010-09-22 13:05:01 -07002100 if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002101 return 1;
2102
2103 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002104}
2105
Mel Gormandac1d272008-04-28 02:12:12 -07002106unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002107 gfp_t gfp_mask, nodemask_t *nodemask)
Balbir Singh66e17072008-02-07 00:13:56 -08002108{
Mel Gorman33906bc2010-08-09 17:19:16 -07002109 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002110 struct scan_control sc = {
2111 .gfp_mask = gfp_mask,
2112 .may_writepage = !laptop_mode,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002113 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002114 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002115 .may_swap = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08002116 .swappiness = vm_swappiness,
2117 .order = order,
2118 .mem_cgroup = NULL,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002119 .nodemask = nodemask,
Balbir Singh66e17072008-02-07 00:13:56 -08002120 };
2121
Mel Gorman33906bc2010-08-09 17:19:16 -07002122 trace_mm_vmscan_direct_reclaim_begin(order,
2123 sc.may_writepage,
2124 gfp_mask);
2125
2126 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
2127
2128 trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
2129
2130 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002131}
2132
Balbir Singh00f0b822008-03-04 14:28:39 -08002133#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08002134
Balbir Singh4e416952009-09-23 15:56:39 -07002135unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
2136 gfp_t gfp_mask, bool noswap,
2137 unsigned int swappiness,
KOSAKI Motohiro14fec792010-08-10 18:03:05 -07002138 struct zone *zone)
Balbir Singh4e416952009-09-23 15:56:39 -07002139{
2140 struct scan_control sc = {
KOSAKI Motohirob8f5c562010-08-10 18:03:02 -07002141 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh4e416952009-09-23 15:56:39 -07002142 .may_writepage = !laptop_mode,
2143 .may_unmap = 1,
2144 .may_swap = !noswap,
Balbir Singh4e416952009-09-23 15:56:39 -07002145 .swappiness = swappiness,
2146 .order = 0,
2147 .mem_cgroup = mem,
Balbir Singh4e416952009-09-23 15:56:39 -07002148 };
Balbir Singh4e416952009-09-23 15:56:39 -07002149 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2150 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002151
2152 trace_mm_vmscan_memcg_softlimit_reclaim_begin(0,
2153 sc.may_writepage,
2154 sc.gfp_mask);
2155
Balbir Singh4e416952009-09-23 15:56:39 -07002156 /*
2157 * NOTE: Although we can get the priority field, using it
2158 * here is not a good idea, since it limits the pages we can scan.
2159 * if we don't reclaim here, the shrink_zone from balance_pgdat
2160 * will pick up pages from other mem cgroup's as well. We hack
2161 * the priority and make it zero.
2162 */
2163 shrink_zone(0, zone, &sc);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002164
2165 trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
2166
Balbir Singh4e416952009-09-23 15:56:39 -07002167 return sc.nr_reclaimed;
2168}
2169
Balbir Singhe1a1cd52008-02-07 00:14:02 -08002170unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002171 gfp_t gfp_mask,
2172 bool noswap,
2173 unsigned int swappiness)
Balbir Singh66e17072008-02-07 00:13:56 -08002174{
Balbir Singh4e416952009-09-23 15:56:39 -07002175 struct zonelist *zonelist;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002176 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002177 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08002178 .may_writepage = !laptop_mode,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002179 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002180 .may_swap = !noswap,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002181 .nr_to_reclaim = SWAP_CLUSTER_MAX,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002182 .swappiness = swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002183 .order = 0,
2184 .mem_cgroup = mem_cont,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002185 .nodemask = NULL, /* we don't care the placement */
Balbir Singh66e17072008-02-07 00:13:56 -08002186 };
Balbir Singh66e17072008-02-07 00:13:56 -08002187
Mel Gormandd1a2392008-04-28 02:12:17 -07002188 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2189 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
2190 zonelist = NODE_DATA(numa_node_id())->node_zonelists;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002191
2192 trace_mm_vmscan_memcg_reclaim_begin(0,
2193 sc.may_writepage,
2194 sc.gfp_mask);
2195
2196 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
2197
2198 trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
2199
2200 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002201}
2202#endif
2203
Mel Gorman1741c872011-01-13 15:46:21 -08002204/*
2205 * pgdat_balanced is used when checking if a node is balanced for high-order
2206 * allocations. Only zones that meet watermarks and are in a zone allowed
2207 * by the callers classzone_idx are added to balanced_pages. The total of
2208 * balanced pages must be at least 25% of the zones allowed by classzone_idx
2209 * for the node to be considered balanced. Forcing all zones to be balanced
2210 * for high orders can cause excessive reclaim when there are imbalanced zones.
2211 * The choice of 25% is due to
2212 * o a 16M DMA zone that is balanced will not balance a zone on any
2213 * reasonable sized machine
2214 * o On all other machines, the top zone must be at least a reasonable
2215 * precentage of the middle zones. For example, on 32-bit x86, highmem
2216 * would need to be at least 256M for it to be balance a whole node.
2217 * Similarly, on x86-64 the Normal zone would need to be at least 1G
2218 * to balance a node on its own. These seemed like reasonable ratios.
2219 */
2220static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
2221 int classzone_idx)
2222{
2223 unsigned long present_pages = 0;
2224 int i;
2225
2226 for (i = 0; i <= classzone_idx; i++)
2227 present_pages += pgdat->node_zones[i].present_pages;
2228
2229 return balanced_pages > (present_pages >> 2);
2230}
2231
Mel Gormanf50de2d2009-12-14 17:58:53 -08002232/* is kswapd sleeping prematurely? */
Mel Gormandc83edd2011-01-13 15:46:26 -08002233static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
2234 int classzone_idx)
Mel Gormanf50de2d2009-12-14 17:58:53 -08002235{
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002236 int i;
Mel Gorman1741c872011-01-13 15:46:21 -08002237 unsigned long balanced = 0;
2238 bool all_zones_ok = true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002239
2240 /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
2241 if (remaining)
Mel Gormandc83edd2011-01-13 15:46:26 -08002242 return true;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002243
Mel Gorman0abdee22011-01-13 15:46:22 -08002244 /* Check the watermark levels */
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002245 for (i = 0; i < pgdat->nr_zones; i++) {
2246 struct zone *zone = pgdat->node_zones + i;
2247
2248 if (!populated_zone(zone))
2249 continue;
2250
Mel Gorman355b09c2011-01-13 15:46:24 -08002251 /*
2252 * balance_pgdat() skips over all_unreclaimable after
2253 * DEF_PRIORITY. Effectively, it considers them balanced so
2254 * they must be considered balanced here as well if kswapd
2255 * is to sleep
2256 */
2257 if (zone->all_unreclaimable) {
2258 balanced += zone->present_pages;
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002259 continue;
Mel Gorman355b09c2011-01-13 15:46:24 -08002260 }
KOSAKI Motohirode3fab32010-01-15 17:01:25 -08002261
Mel Gorman88f5acf2011-01-13 15:45:41 -08002262 if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
Mel Gormandc83edd2011-01-13 15:46:26 -08002263 classzone_idx, 0))
Mel Gorman1741c872011-01-13 15:46:21 -08002264 all_zones_ok = false;
2265 else
2266 balanced += zone->present_pages;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002267 }
Mel Gormanf50de2d2009-12-14 17:58:53 -08002268
Mel Gorman1741c872011-01-13 15:46:21 -08002269 /*
2270 * For high-order requests, the balanced zones must contain at least
2271 * 25% of the nodes pages for kswapd to sleep. For order-0, all zones
2272 * must be balanced
2273 */
2274 if (order)
Mel Gormandc83edd2011-01-13 15:46:26 -08002275 return pgdat_balanced(pgdat, balanced, classzone_idx);
Mel Gorman1741c872011-01-13 15:46:21 -08002276 else
2277 return !all_zones_ok;
Mel Gormanf50de2d2009-12-14 17:58:53 -08002278}
2279
Linus Torvalds1da177e2005-04-16 15:20:36 -07002280/*
2281 * For kswapd, balance_pgdat() will work across all this node's zones until
Mel Gorman41858962009-06-16 15:32:12 -07002282 * they are all at high_wmark_pages(zone).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283 *
Mel Gorman0abdee22011-01-13 15:46:22 -08002284 * Returns the final order kswapd was reclaiming at
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285 *
2286 * There is special handling here for zones which are full of pinned pages.
2287 * This can happen if the pages are all mlocked, or if they are all used by
2288 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
2289 * What we do is to detect the case where all pages in the zone have been
2290 * scanned twice and there has been zero successful reclaim. Mark the zone as
2291 * dead and from now on, only perform a short scan. Basically we're polling
2292 * the zone for when the problem goes away.
2293 *
2294 * kswapd scans the zones in the highmem->normal->dma direction. It skips
Mel Gorman41858962009-06-16 15:32:12 -07002295 * zones which have free_pages > high_wmark_pages(zone), but once a zone is
2296 * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
2297 * lower zones regardless of the number of free pages in the lower zones. This
2298 * interoperates with the page allocator fallback scheme to ensure that aging
2299 * of pages is balanced across the zones.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002300 */
Mel Gorman99504742011-01-13 15:46:20 -08002301static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
Mel Gormandc83edd2011-01-13 15:46:26 -08002302 int *classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002303{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 int all_zones_ok;
Mel Gorman1741c872011-01-13 15:46:21 -08002305 unsigned long balanced;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 int priority;
2307 int i;
Mel Gorman99504742011-01-13 15:46:20 -08002308 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
Andrew Morton69e05942006-03-22 00:08:19 -08002309 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002310 struct reclaim_state *reclaim_state = current->reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08002311 struct scan_control sc = {
2312 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002313 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002314 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002315 /*
2316 * kswapd doesn't want to be bailed out while reclaim. because
2317 * we want to put equal scanning pressure on each zone.
2318 */
2319 .nr_to_reclaim = ULONG_MAX,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002320 .swappiness = vm_swappiness,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07002321 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08002322 .mem_cgroup = NULL,
Andrew Morton179e9632006-03-22 00:08:18 -08002323 };
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324loop_again:
2325 total_scanned = 0;
Rik van Riela79311c2009-01-06 14:40:01 -08002326 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07002327 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07002328 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329
Linus Torvalds1da177e2005-04-16 15:20:36 -07002330 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331 unsigned long lru_pages = 0;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002332 int has_under_min_watermark_zone = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333
Rik van Rielf7b7fd82005-11-28 13:44:07 -08002334 /* The swap token gets in the way of swapout... */
2335 if (!priority)
2336 disable_swap_token();
2337
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 all_zones_ok = 1;
Mel Gorman1741c872011-01-13 15:46:21 -08002339 balanced = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002341 /*
2342 * Scan in the highmem->dma direction for the highest
2343 * zone which needs scanning
2344 */
2345 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
2346 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002348 if (!populated_zone(zone))
2349 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002351 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002352 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353
Rik van Riel556adec2008-10-18 20:26:34 -07002354 /*
2355 * Do some background aging of the anon list, to give
2356 * pages a chance to be referenced before reclaiming.
2357 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08002358 if (inactive_anon_is_low(zone, &sc))
Rik van Riel556adec2008-10-18 20:26:34 -07002359 shrink_active_list(SWAP_CLUSTER_MAX, zone,
2360 &sc, priority, 0);
2361
Mel Gorman88f5acf2011-01-13 15:45:41 -08002362 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman41858962009-06-16 15:32:12 -07002363 high_wmark_pages(zone), 0, 0)) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002364 end_zone = i;
Mel Gormandc83edd2011-01-13 15:46:26 -08002365 *classzone_idx = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002366 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002369 if (i < 0)
2370 goto out;
2371
Linus Torvalds1da177e2005-04-16 15:20:36 -07002372 for (i = 0; i <= end_zone; i++) {
2373 struct zone *zone = pgdat->node_zones + i;
2374
Wu Fengguangadea02a2009-09-21 17:01:42 -07002375 lru_pages += zone_reclaimable_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 }
2377
2378 /*
2379 * Now scan the zone in the dma->highmem direction, stopping
2380 * at the last zone which needs scanning.
2381 *
2382 * We do this because the page allocator works in the opposite
2383 * direction. This prevents the page allocator from allocating
2384 * pages behind kswapd's direction of progress, which would
2385 * cause too much scanning of the lower zones.
2386 */
2387 for (i = 0; i <= end_zone; i++) {
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002388 int compaction;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002389 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07002390 int nr_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002391
Con Kolivasf3fe6512006-01-06 00:11:15 -08002392 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393 continue;
2394
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002395 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002396 continue;
2397
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398 sc.nr_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002399
Balbir Singh4e416952009-09-23 15:56:39 -07002400 /*
2401 * Call soft limit reclaim before calling shrink_zone.
2402 * For now we ignore the return value
2403 */
KOSAKI Motohiro00918b62010-08-10 18:03:05 -07002404 mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
2405
Rik van Riel32a43302007-10-16 01:24:50 -07002406 /*
2407 * We put equal pressure on every zone, unless one
2408 * zone has way too many pages free already.
2409 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002410 if (!zone_watermark_ok_safe(zone, order,
Mel Gorman41858962009-06-16 15:32:12 -07002411 8*high_wmark_pages(zone), end_zone, 0))
Rik van Riela79311c2009-01-06 14:40:01 -08002412 shrink_zone(priority, zone, &sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002413 reclaim_state->reclaimed_slab = 0;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07002414 nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
2415 lru_pages);
Rik van Riela79311c2009-01-06 14:40:01 -08002416 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002417 total_scanned += sc.nr_scanned;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002418
2419 compaction = 0;
2420 if (order &&
2421 zone_watermark_ok(zone, 0,
2422 high_wmark_pages(zone),
2423 end_zone, 0) &&
2424 !zone_watermark_ok(zone, order,
2425 high_wmark_pages(zone),
2426 end_zone, 0)) {
2427 compact_zone_order(zone,
2428 order,
2429 sc.gfp_mask, false,
2430 COMPACT_MODE_KSWAPD);
2431 compaction = 1;
2432 }
2433
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002434 if (zone->all_unreclaimable)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 continue;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002436 if (!compaction && nr_slab == 0 &&
2437 !zone_reclaimable(zone))
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08002438 zone->all_unreclaimable = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439 /*
2440 * If we've done a decent amount of scanning and
2441 * the reclaim ratio is low, start doing writepage
2442 * even in laptop mode
2443 */
2444 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08002445 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002446 sc.may_writepage = 1;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002447
Mel Gorman88f5acf2011-01-13 15:45:41 -08002448 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002449 high_wmark_pages(zone), end_zone, 0)) {
2450 all_zones_ok = 0;
2451 /*
2452 * We are still under min water mark. This
2453 * means that we have a GFP_ATOMIC allocation
2454 * failure risk. Hurry up!
2455 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002456 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002457 min_wmark_pages(zone), end_zone, 0))
2458 has_under_min_watermark_zone = 1;
Mel Gorman0e093d992010-10-26 14:21:45 -07002459 } else {
2460 /*
2461 * If a zone reaches its high watermark,
2462 * consider it to be no longer congested. It's
2463 * possible there are dirty pages backed by
2464 * congested BDIs but as pressure is relieved,
2465 * spectulatively avoid congestion waits
2466 */
2467 zone_clear_flag(zone, ZONE_CONGESTED);
Mel Gormandc83edd2011-01-13 15:46:26 -08002468 if (i <= *classzone_idx)
Mel Gorman1741c872011-01-13 15:46:21 -08002469 balanced += zone->present_pages;
Minchan Kim45973d72010-03-05 13:41:45 -08002470 }
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002471
Linus Torvalds1da177e2005-04-16 15:20:36 -07002472 }
Mel Gormandc83edd2011-01-13 15:46:26 -08002473 if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 break; /* kswapd: all done */
2475 /*
2476 * OK, kswapd is getting into trouble. Take a nap, then take
2477 * another pass across the zones.
2478 */
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002479 if (total_scanned && (priority < DEF_PRIORITY - 2)) {
2480 if (has_under_min_watermark_zone)
2481 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
2482 else
2483 congestion_wait(BLK_RW_ASYNC, HZ/10);
2484 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002485
2486 /*
2487 * We do this so kswapd doesn't build up large priorities for
2488 * example when it is freeing in parallel with allocators. It
2489 * matches the direct reclaim path behaviour in terms of impact
2490 * on zone->*_priority.
2491 */
Rik van Riela79311c2009-01-06 14:40:01 -08002492 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002493 break;
2494 }
2495out:
Mel Gorman99504742011-01-13 15:46:20 -08002496
2497 /*
2498 * order-0: All zones must meet high watermark for a balanced node
Mel Gorman1741c872011-01-13 15:46:21 -08002499 * high-order: Balanced zones must make up at least 25% of the node
2500 * for the node to be balanced
Mel Gorman99504742011-01-13 15:46:20 -08002501 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002502 if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002503 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08002504
2505 try_to_freeze();
2506
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08002507 /*
2508 * Fragmentation may mean that the system cannot be
2509 * rebalanced for high-order allocations in all zones.
2510 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
2511 * it means the zones have been fully scanned and are still
2512 * not balanced. For high-order allocations, there is
2513 * little point trying all over again as kswapd may
2514 * infinite loop.
2515 *
2516 * Instead, recheck all watermarks at order-0 as they
2517 * are the most important. If watermarks are ok, kswapd will go
2518 * back to sleep. High-order users can still perform direct
2519 * reclaim if they wish.
2520 */
2521 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
2522 order = sc.order = 0;
2523
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524 goto loop_again;
2525 }
2526
Mel Gorman99504742011-01-13 15:46:20 -08002527 /*
2528 * If kswapd was reclaiming at a higher order, it has the option of
2529 * sleeping without all zones being balanced. Before it does, it must
2530 * ensure that the watermarks for order-0 on *all* zones are met and
2531 * that the congestion flags are cleared. The congestion flag must
2532 * be cleared as kswapd is the only mechanism that clears the flag
2533 * and it is potentially going to sleep here.
2534 */
2535 if (order) {
2536 for (i = 0; i <= end_zone; i++) {
2537 struct zone *zone = pgdat->node_zones + i;
2538
2539 if (!populated_zone(zone))
2540 continue;
2541
2542 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
2543 continue;
2544
2545 /* Confirm the zone is balanced for order-0 */
2546 if (!zone_watermark_ok(zone, 0,
2547 high_wmark_pages(zone), 0, 0)) {
2548 order = sc.order = 0;
2549 goto loop_again;
2550 }
2551
2552 /* If balanced, clear the congested flag */
2553 zone_clear_flag(zone, ZONE_CONGESTED);
2554 }
2555 }
2556
Mel Gorman0abdee22011-01-13 15:46:22 -08002557 /*
2558 * Return the order we were reclaiming at so sleeping_prematurely()
2559 * makes a decision on the order we were last reclaiming at. However,
2560 * if another caller entered the allocator slow path while kswapd
2561 * was awake, order will remain at the higher level
2562 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002563 *classzone_idx = end_zone;
Mel Gorman0abdee22011-01-13 15:46:22 -08002564 return order;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565}
2566
Mel Gormandc83edd2011-01-13 15:46:26 -08002567static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002568{
2569 long remaining = 0;
2570 DEFINE_WAIT(wait);
2571
2572 if (freezing(current) || kthread_should_stop())
2573 return;
2574
2575 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2576
2577 /* Try to sleep for a short interval */
Mel Gormandc83edd2011-01-13 15:46:26 -08002578 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002579 remaining = schedule_timeout(HZ/10);
2580 finish_wait(&pgdat->kswapd_wait, &wait);
2581 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2582 }
2583
2584 /*
2585 * After a short sleep, check if it was a premature sleep. If not, then
2586 * go fully to sleep until explicitly woken up.
2587 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002588 if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002589 trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
2590
2591 /*
2592 * vmstat counters are not perfectly accurate and the estimated
2593 * value for counters such as NR_FREE_PAGES can deviate from the
2594 * true value by nr_online_cpus * threshold. To avoid the zone
2595 * watermarks being breached while under pressure, we reduce the
2596 * per-cpu vmstat threshold while kswapd is awake and restore
2597 * them before going back to sleep.
2598 */
2599 set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
2600 schedule();
2601 set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
2602 } else {
2603 if (remaining)
2604 count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
2605 else
2606 count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
2607 }
2608 finish_wait(&pgdat->kswapd_wait, &wait);
2609}
2610
Linus Torvalds1da177e2005-04-16 15:20:36 -07002611/*
2612 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002613 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002614 *
2615 * This basically trickles out pages so that we have _some_
2616 * free memory available even if there is no other activity
2617 * that frees anything up. This is needed for things like routing
2618 * etc, where we otherwise might have all activity going on in
2619 * asynchronous contexts that cannot page things out.
2620 *
2621 * If there are applications that are active memory-allocators
2622 * (most normal use), this basically shouldn't matter.
2623 */
2624static int kswapd(void *p)
2625{
2626 unsigned long order;
Mel Gorman99504742011-01-13 15:46:20 -08002627 int classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002628 pg_data_t *pgdat = (pg_data_t*)p;
2629 struct task_struct *tsk = current;
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002630
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631 struct reclaim_state reclaim_state = {
2632 .reclaimed_slab = 0,
2633 };
Rusty Russella70f7302009-03-13 14:49:46 +10302634 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002635
Nick Piggincf40bd12009-01-21 08:12:39 +01002636 lockdep_set_current_reclaim_state(GFP_KERNEL);
2637
Rusty Russell174596a2009-01-01 10:12:29 +10302638 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07002639 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640 current->reclaim_state = &reclaim_state;
2641
2642 /*
2643 * Tell the memory management that we're a "memory allocator",
2644 * and that if we need more memory we should get access to it
2645 * regardless (see "__alloc_pages()"). "kswapd" should
2646 * never get caught in the normal page freeing logic.
2647 *
2648 * (Kswapd normally doesn't need memory anyway, but sometimes
2649 * you need a small amount of memory in order to be able to
2650 * page out something else, and this flag essentially protects
2651 * us from recursively trying to free more memory as we're
2652 * trying to free the first piece of memory in the first place).
2653 */
Christoph Lameter930d9152006-01-08 01:00:47 -08002654 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07002655 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656
2657 order = 0;
Mel Gorman99504742011-01-13 15:46:20 -08002658 classzone_idx = MAX_NR_ZONES - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002659 for ( ; ; ) {
2660 unsigned long new_order;
Mel Gorman99504742011-01-13 15:46:20 -08002661 int new_classzone_idx;
David Rientjes8fe23e02009-12-14 17:58:33 -08002662 int ret;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07002663
Linus Torvalds1da177e2005-04-16 15:20:36 -07002664 new_order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08002665 new_classzone_idx = pgdat->classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666 pgdat->kswapd_max_order = 0;
Mel Gorman99504742011-01-13 15:46:20 -08002667 pgdat->classzone_idx = MAX_NR_ZONES - 1;
2668 if (order < new_order || classzone_idx > new_classzone_idx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002669 /*
2670 * Don't sleep if someone wants a larger 'order'
Mel Gorman99504742011-01-13 15:46:20 -08002671 * allocation or has tigher zone constraints
Linus Torvalds1da177e2005-04-16 15:20:36 -07002672 */
2673 order = new_order;
Mel Gorman99504742011-01-13 15:46:20 -08002674 classzone_idx = new_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002675 } else {
Mel Gormandc83edd2011-01-13 15:46:26 -08002676 kswapd_try_to_sleep(pgdat, order, classzone_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677 order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08002678 classzone_idx = pgdat->classzone_idx;
Mel Gorman4d405022011-01-13 15:46:23 -08002679 pgdat->kswapd_max_order = 0;
2680 pgdat->classzone_idx = MAX_NR_ZONES - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002681 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002682
David Rientjes8fe23e02009-12-14 17:58:33 -08002683 ret = try_to_freeze();
2684 if (kthread_should_stop())
2685 break;
2686
2687 /*
2688 * We can speed up thawing tasks if we don't call balance_pgdat
2689 * after returning from the refrigerator
2690 */
Mel Gorman33906bc2010-08-09 17:19:16 -07002691 if (!ret) {
2692 trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
Mel Gormandc83edd2011-01-13 15:46:26 -08002693 order = balance_pgdat(pgdat, order, &classzone_idx);
Mel Gorman33906bc2010-08-09 17:19:16 -07002694 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002695 }
2696 return 0;
2697}
2698
2699/*
2700 * A zone is low on free memory, so wake its kswapd task to service it.
2701 */
Mel Gorman99504742011-01-13 15:46:20 -08002702void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002703{
2704 pg_data_t *pgdat;
2705
Con Kolivasf3fe6512006-01-06 00:11:15 -08002706 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002707 return;
2708
Paul Jackson02a0e532006-12-13 00:34:25 -08002709 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002710 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08002711 pgdat = zone->zone_pgdat;
Mel Gorman99504742011-01-13 15:46:20 -08002712 if (pgdat->kswapd_max_order < order) {
Mel Gorman88f5acf2011-01-13 15:45:41 -08002713 pgdat->kswapd_max_order = order;
Mel Gorman99504742011-01-13 15:46:20 -08002714 pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
2715 }
Con Kolivas8d0986e2005-09-13 01:25:07 -07002716 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08002718 if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
2719 return;
2720
2721 trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
Con Kolivas8d0986e2005-09-13 01:25:07 -07002722 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002723}
2724
Wu Fengguangadea02a2009-09-21 17:01:42 -07002725/*
2726 * The reclaimable count would be mostly accurate.
2727 * The less reclaimable pages may be
2728 * - mlocked pages, which will be moved to unevictable list when encountered
2729 * - mapped pages, which may require several travels to be reclaimed
2730 * - dirty pages, which is not "instantly" reclaimable
2731 */
2732unsigned long global_reclaimable_pages(void)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002733{
Wu Fengguangadea02a2009-09-21 17:01:42 -07002734 int nr;
2735
2736 nr = global_page_state(NR_ACTIVE_FILE) +
2737 global_page_state(NR_INACTIVE_FILE);
2738
2739 if (nr_swap_pages > 0)
2740 nr += global_page_state(NR_ACTIVE_ANON) +
2741 global_page_state(NR_INACTIVE_ANON);
2742
2743 return nr;
2744}
2745
2746unsigned long zone_reclaimable_pages(struct zone *zone)
2747{
2748 int nr;
2749
2750 nr = zone_page_state(zone, NR_ACTIVE_FILE) +
2751 zone_page_state(zone, NR_INACTIVE_FILE);
2752
2753 if (nr_swap_pages > 0)
2754 nr += zone_page_state(zone, NR_ACTIVE_ANON) +
2755 zone_page_state(zone, NR_INACTIVE_ANON);
2756
2757 return nr;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002758}
2759
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02002760#ifdef CONFIG_HIBERNATION
Linus Torvalds1da177e2005-04-16 15:20:36 -07002761/*
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002762 * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002763 * freed pages.
2764 *
2765 * Rather than trying to age LRUs the aim is to preserve the overall
2766 * LRU order by reclaiming preferentially
2767 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002768 */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002769unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002771 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002772 struct scan_control sc = {
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002773 .gfp_mask = GFP_HIGHUSER_MOVABLE,
2774 .may_swap = 1,
2775 .may_unmap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002776 .may_writepage = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002777 .nr_to_reclaim = nr_to_reclaim,
2778 .hibernation_mode = 1,
2779 .swappiness = vm_swappiness,
2780 .order = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002781 };
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002782 struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
2783 struct task_struct *p = current;
2784 unsigned long nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002785
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002786 p->flags |= PF_MEMALLOC;
2787 lockdep_set_current_reclaim_state(sc.gfp_mask);
2788 reclaim_state.reclaimed_slab = 0;
2789 p->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08002790
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002791 nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002792
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002793 p->reclaim_state = NULL;
2794 lockdep_clear_current_reclaim_state();
2795 p->flags &= ~PF_MEMALLOC;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002796
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002797 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002798}
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02002799#endif /* CONFIG_HIBERNATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800
Linus Torvalds1da177e2005-04-16 15:20:36 -07002801/* It's optimal to keep kswapds on the same CPUs as their memory, but
2802 not required for correctness. So if the last cpu in a node goes
2803 away, we get changed to run anywhere: as the first one comes back,
2804 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07002805static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08002806 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002807{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002808 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002810 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002811 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07002812 pg_data_t *pgdat = NODE_DATA(nid);
Rusty Russella70f7302009-03-13 14:49:46 +10302813 const struct cpumask *mask;
2814
2815 mask = cpumask_of_node(pgdat->node_id);
Mike Travisc5f59f02008-04-04 18:11:10 -07002816
Rusty Russell3e597942009-01-01 10:12:24 +10302817 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002818 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07002819 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002820 }
2821 }
2822 return NOTIFY_OK;
2823}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002824
Yasunori Goto3218ae12006-06-27 02:53:33 -07002825/*
2826 * This kswapd start function will be called by init and node-hot-add.
2827 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
2828 */
2829int kswapd_run(int nid)
2830{
2831 pg_data_t *pgdat = NODE_DATA(nid);
2832 int ret = 0;
2833
2834 if (pgdat->kswapd)
2835 return 0;
2836
2837 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
2838 if (IS_ERR(pgdat->kswapd)) {
2839 /* failure at boot is fatal */
2840 BUG_ON(system_state == SYSTEM_BOOTING);
2841 printk("Failed to start kswapd on node %d\n",nid);
2842 ret = -1;
2843 }
2844 return ret;
2845}
2846
David Rientjes8fe23e02009-12-14 17:58:33 -08002847/*
2848 * Called by memory hotplug when all memory in a node is offlined.
2849 */
2850void kswapd_stop(int nid)
2851{
2852 struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
2853
2854 if (kswapd)
2855 kthread_stop(kswapd);
2856}
2857
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858static int __init kswapd_init(void)
2859{
Yasunori Goto3218ae12006-06-27 02:53:33 -07002860 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08002861
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07002863 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07002864 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865 hotcpu_notifier(cpu_callback, 0);
2866 return 0;
2867}
2868
2869module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002870
2871#ifdef CONFIG_NUMA
2872/*
2873 * Zone reclaim mode
2874 *
2875 * If non-zero call zone_reclaim when the number of free pages falls below
2876 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08002877 */
2878int zone_reclaim_mode __read_mostly;
2879
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002880#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07002881#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002882#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
2883#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
2884
Christoph Lameter9eeff232006-01-18 17:42:31 -08002885/*
Christoph Lametera92f7122006-02-01 03:05:32 -08002886 * Priority for ZONE_RECLAIM. This determines the fraction of pages
2887 * of a node considered for each zone_reclaim. 4 scans 1/16th of
2888 * a zone.
2889 */
2890#define ZONE_RECLAIM_PRIORITY 4
2891
Christoph Lameter9eeff232006-01-18 17:42:31 -08002892/*
Christoph Lameter96146342006-07-03 00:24:13 -07002893 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
2894 * occur.
2895 */
2896int sysctl_min_unmapped_ratio = 1;
2897
2898/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002899 * If the number of slab pages in a zone grows beyond this percentage then
2900 * slab reclaim needs to occur.
2901 */
2902int sysctl_min_slab_ratio = 5;
2903
Mel Gorman90afa5d2009-06-16 15:33:20 -07002904static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
2905{
2906 unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
2907 unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
2908 zone_page_state(zone, NR_ACTIVE_FILE);
2909
2910 /*
2911 * It's possible for there to be more file mapped pages than
2912 * accounted for by the pages on the file LRU lists because
2913 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
2914 */
2915 return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
2916}
2917
2918/* Work out how many page cache pages we can reclaim in this reclaim_mode */
2919static long zone_pagecache_reclaimable(struct zone *zone)
2920{
2921 long nr_pagecache_reclaimable;
2922 long delta = 0;
2923
2924 /*
2925 * If RECLAIM_SWAP is set, then all file pages are considered
2926 * potentially reclaimable. Otherwise, we have to worry about
2927 * pages like swapcache and zone_unmapped_file_pages() provides
2928 * a better estimate
2929 */
2930 if (zone_reclaim_mode & RECLAIM_SWAP)
2931 nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
2932 else
2933 nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
2934
2935 /* If we can't clean pages, remove dirty pages from consideration */
2936 if (!(zone_reclaim_mode & RECLAIM_WRITE))
2937 delta += zone_page_state(zone, NR_FILE_DIRTY);
2938
2939 /* Watch for any possible underflows due to delta */
2940 if (unlikely(delta > nr_pagecache_reclaimable))
2941 delta = nr_pagecache_reclaimable;
2942
2943 return nr_pagecache_reclaimable - delta;
2944}
2945
Christoph Lameter0ff38492006-09-25 23:31:52 -07002946/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08002947 * Try to free up some pages from this zone through reclaim.
2948 */
Andrew Morton179e9632006-03-22 00:08:18 -08002949static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002950{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002951 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08002952 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002953 struct task_struct *p = current;
2954 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08002955 int priority;
Andrew Morton179e9632006-03-22 00:08:18 -08002956 struct scan_control sc = {
2957 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002958 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002959 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002960 .nr_to_reclaim = max_t(unsigned long, nr_pages,
2961 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08002962 .gfp_mask = gfp_mask,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002963 .swappiness = vm_swappiness,
Johannes Weinerbd2f6192009-03-31 15:19:38 -07002964 .order = order,
Andrew Morton179e9632006-03-22 00:08:18 -08002965 };
KOSAKI Motohiro15748042010-08-09 17:19:50 -07002966 unsigned long nr_slab_pages0, nr_slab_pages1;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002967
Christoph Lameter9eeff232006-01-18 17:42:31 -08002968 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08002969 /*
2970 * We need to be able to allocate from the reserves for RECLAIM_SWAP
2971 * and we also need to be able to write out pages for RECLAIM_WRITE
2972 * and RECLAIM_SWAP.
2973 */
2974 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08002975 lockdep_set_current_reclaim_state(gfp_mask);
Christoph Lameter9eeff232006-01-18 17:42:31 -08002976 reclaim_state.reclaimed_slab = 0;
2977 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08002978
Mel Gorman90afa5d2009-06-16 15:33:20 -07002979 if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
Christoph Lameter0ff38492006-09-25 23:31:52 -07002980 /*
2981 * Free memory by calling shrink zone with increasing
2982 * priorities until we have enough memory freed.
2983 */
2984 priority = ZONE_RECLAIM_PRIORITY;
2985 do {
Rik van Riela79311c2009-01-06 14:40:01 -08002986 shrink_zone(priority, zone, &sc);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002987 priority--;
Rik van Riela79311c2009-01-06 14:40:01 -08002988 } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002989 }
Christoph Lameterc84db232006-02-01 03:05:29 -08002990
KOSAKI Motohiro15748042010-08-09 17:19:50 -07002991 nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
2992 if (nr_slab_pages0 > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002993 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002994 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07002995 * many pages were freed in this zone. So we take the current
2996 * number of slab pages and shake the slab until it is reduced
2997 * by the same nr_pages that we used for reclaiming unmapped
2998 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002999 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07003000 * Note that shrink_slab will free memory on all zones and may
3001 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003002 */
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003003 for (;;) {
3004 unsigned long lru_pages = zone_reclaimable_pages(zone);
3005
3006 /* No reclaimable slab or very low memory pressure */
3007 if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages))
3008 break;
3009
3010 /* Freed enough memory */
3011 nr_slab_pages1 = zone_page_state(zone,
3012 NR_SLAB_RECLAIMABLE);
3013 if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
3014 break;
3015 }
Christoph Lameter83e33a42006-09-25 23:31:53 -07003016
3017 /*
3018 * Update nr_reclaimed by the number of slab pages we
3019 * reclaimed from this zone.
3020 */
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003021 nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3022 if (nr_slab_pages1 < nr_slab_pages0)
3023 sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003024 }
3025
Christoph Lameter9eeff232006-01-18 17:42:31 -08003026 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08003027 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003028 lockdep_clear_current_reclaim_state();
Rik van Riela79311c2009-01-06 14:40:01 -08003029 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003030}
Andrew Morton179e9632006-03-22 00:08:18 -08003031
3032int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
3033{
Andrew Morton179e9632006-03-22 00:08:18 -08003034 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07003035 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003036
3037 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003038 * Zone reclaim reclaims unmapped file backed pages and
3039 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07003040 *
Christoph Lameter96146342006-07-03 00:24:13 -07003041 * A small portion of unmapped file backed pages is needed for
3042 * file I/O otherwise pages read by file I/O will be immediately
3043 * thrown out if the zone is overallocated. So we do not reclaim
3044 * if less than a specified percentage of the zone is used by
3045 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08003046 */
Mel Gorman90afa5d2009-06-16 15:33:20 -07003047 if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
3048 zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003049 return ZONE_RECLAIM_FULL;
Andrew Morton179e9632006-03-22 00:08:18 -08003050
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08003051 if (zone->all_unreclaimable)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003052 return ZONE_RECLAIM_FULL;
David Rientjesd773ed62007-10-16 23:26:01 -07003053
Andrew Morton179e9632006-03-22 00:08:18 -08003054 /*
David Rientjesd773ed62007-10-16 23:26:01 -07003055 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08003056 */
David Rientjesd773ed62007-10-16 23:26:01 -07003057 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003058 return ZONE_RECLAIM_NOSCAN;
Andrew Morton179e9632006-03-22 00:08:18 -08003059
3060 /*
3061 * Only run zone reclaim on the local zone or on zones that do not
3062 * have associated processors. This will favor the local processor
3063 * over remote processors and spread off node memory allocations
3064 * as wide as possible.
3065 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07003066 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07003067 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Mel Gormanfa5e0842009-06-16 15:33:22 -07003068 return ZONE_RECLAIM_NOSCAN;
David Rientjesd773ed62007-10-16 23:26:01 -07003069
3070 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003071 return ZONE_RECLAIM_NOSCAN;
3072
David Rientjesd773ed62007-10-16 23:26:01 -07003073 ret = __zone_reclaim(zone, gfp_mask, order);
3074 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
3075
Mel Gorman24cf725182009-06-16 15:33:23 -07003076 if (!ret)
3077 count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
3078
David Rientjesd773ed62007-10-16 23:26:01 -07003079 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003080}
Christoph Lameter9eeff232006-01-18 17:42:31 -08003081#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003082
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003083/*
3084 * page_evictable - test whether a page is evictable
3085 * @page: the page to test
3086 * @vma: the VMA in which the page is or will be mapped, may be NULL
3087 *
3088 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07003089 * lists vs unevictable list. The vma argument is !NULL when called from the
3090 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003091 *
3092 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003093 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07003094 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003095 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003096 */
3097int page_evictable(struct page *page, struct vm_area_struct *vma)
3098{
3099
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003100 if (mapping_unevictable(page_mapping(page)))
3101 return 0;
3102
Nick Pigginb291f002008-10-18 20:26:44 -07003103 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
3104 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003105
3106 return 1;
3107}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003108
3109/**
3110 * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
3111 * @page: page to check evictability and move to appropriate lru list
3112 * @zone: zone page is in
3113 *
3114 * Checks a page for evictability and moves the page to the appropriate
3115 * zone lru list.
3116 *
3117 * Restrictions: zone->lru_lock must be held, page must be on LRU and must
3118 * have PageUnevictable set.
3119 */
3120static void check_move_unevictable_page(struct page *page, struct zone *zone)
3121{
3122 VM_BUG_ON(PageActive(page));
3123
3124retry:
3125 ClearPageUnevictable(page);
3126 if (page_evictable(page, NULL)) {
Johannes Weiner401a8e12009-09-21 17:02:58 -07003127 enum lru_list l = page_lru_base_type(page);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003128
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003129 __dec_zone_state(zone, NR_UNEVICTABLE);
3130 list_move(&page->lru, &zone->lru[l].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08003131 mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003132 __inc_zone_state(zone, NR_INACTIVE_ANON + l);
3133 __count_vm_event(UNEVICTABLE_PGRESCUED);
3134 } else {
3135 /*
3136 * rotate unevictable list
3137 */
3138 SetPageUnevictable(page);
3139 list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08003140 mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003141 if (page_evictable(page, NULL))
3142 goto retry;
3143 }
3144}
3145
3146/**
3147 * scan_mapping_unevictable_pages - scan an address space for evictable pages
3148 * @mapping: struct address_space to scan for evictable pages
3149 *
3150 * Scan all pages in mapping. Check unevictable pages for
3151 * evictability and move them to the appropriate zone lru list.
3152 */
3153void scan_mapping_unevictable_pages(struct address_space *mapping)
3154{
3155 pgoff_t next = 0;
3156 pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
3157 PAGE_CACHE_SHIFT;
3158 struct zone *zone;
3159 struct pagevec pvec;
3160
3161 if (mapping->nrpages == 0)
3162 return;
3163
3164 pagevec_init(&pvec, 0);
3165 while (next < end &&
3166 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
3167 int i;
3168 int pg_scanned = 0;
3169
3170 zone = NULL;
3171
3172 for (i = 0; i < pagevec_count(&pvec); i++) {
3173 struct page *page = pvec.pages[i];
3174 pgoff_t page_index = page->index;
3175 struct zone *pagezone = page_zone(page);
3176
3177 pg_scanned++;
3178 if (page_index > next)
3179 next = page_index;
3180 next++;
3181
3182 if (pagezone != zone) {
3183 if (zone)
3184 spin_unlock_irq(&zone->lru_lock);
3185 zone = pagezone;
3186 spin_lock_irq(&zone->lru_lock);
3187 }
3188
3189 if (PageLRU(page) && PageUnevictable(page))
3190 check_move_unevictable_page(page, zone);
3191 }
3192 if (zone)
3193 spin_unlock_irq(&zone->lru_lock);
3194 pagevec_release(&pvec);
3195
3196 count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
3197 }
3198
3199}
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003200
3201/**
3202 * scan_zone_unevictable_pages - check unevictable list for evictable pages
3203 * @zone - zone of which to scan the unevictable list
3204 *
3205 * Scan @zone's unevictable LRU lists to check for pages that have become
3206 * evictable. Move those that have to @zone's inactive list where they
3207 * become candidates for reclaim, unless shrink_inactive_zone() decides
3208 * to reactivate them. Pages that are still unevictable are rotated
3209 * back onto @zone's unevictable list.
3210 */
3211#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
KOSAKI Motohiro14b90b22009-01-06 14:39:45 -08003212static void scan_zone_unevictable_pages(struct zone *zone)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003213{
3214 struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
3215 unsigned long scan;
3216 unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
3217
3218 while (nr_to_scan > 0) {
3219 unsigned long batch_size = min(nr_to_scan,
3220 SCAN_UNEVICTABLE_BATCH_SIZE);
3221
3222 spin_lock_irq(&zone->lru_lock);
3223 for (scan = 0; scan < batch_size; scan++) {
3224 struct page *page = lru_to_page(l_unevictable);
3225
3226 if (!trylock_page(page))
3227 continue;
3228
3229 prefetchw_prev_lru_page(page, l_unevictable, flags);
3230
3231 if (likely(PageLRU(page) && PageUnevictable(page)))
3232 check_move_unevictable_page(page, zone);
3233
3234 unlock_page(page);
3235 }
3236 spin_unlock_irq(&zone->lru_lock);
3237
3238 nr_to_scan -= batch_size;
3239 }
3240}
3241
3242
3243/**
3244 * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
3245 *
3246 * A really big hammer: scan all zones' unevictable LRU lists to check for
3247 * pages that have become evictable. Move those back to the zones'
3248 * inactive list where they become candidates for reclaim.
3249 * This occurs when, e.g., we have unswappable pages on the unevictable lists,
3250 * and we add swap to the system. As such, it runs in the context of a task
3251 * that has possibly/probably made some previously unevictable pages
3252 * evictable.
3253 */
KOSAKI Motohiroff301532009-01-06 14:39:44 -08003254static void scan_all_zones_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003255{
3256 struct zone *zone;
3257
3258 for_each_zone(zone) {
3259 scan_zone_unevictable_pages(zone);
3260 }
3261}
3262
3263/*
3264 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
3265 * all nodes' unevictable lists for evictable pages
3266 */
3267unsigned long scan_unevictable_pages;
3268
3269int scan_unevictable_handler(struct ctl_table *table, int write,
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003270 void __user *buffer,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003271 size_t *length, loff_t *ppos)
3272{
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003273 proc_doulongvec_minmax(table, write, buffer, length, ppos);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003274
3275 if (write && *(unsigned long *)table->data)
3276 scan_all_zones_unevictable_pages();
3277
3278 scan_unevictable_pages = 0;
3279 return 0;
3280}
3281
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003282#ifdef CONFIG_NUMA
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003283/*
3284 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
3285 * a specified node's per zone unevictable lists for evictable pages.
3286 */
3287
3288static ssize_t read_scan_unevictable_node(struct sys_device *dev,
3289 struct sysdev_attribute *attr,
3290 char *buf)
3291{
3292 return sprintf(buf, "0\n"); /* always zero; should fit... */
3293}
3294
3295static ssize_t write_scan_unevictable_node(struct sys_device *dev,
3296 struct sysdev_attribute *attr,
3297 const char *buf, size_t count)
3298{
3299 struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
3300 struct zone *zone;
3301 unsigned long res;
3302 unsigned long req = strict_strtoul(buf, 10, &res);
3303
3304 if (!req)
3305 return 1; /* zero is no-op */
3306
3307 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
3308 if (!populated_zone(zone))
3309 continue;
3310 scan_zone_unevictable_pages(zone);
3311 }
3312 return 1;
3313}
3314
3315
3316static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
3317 read_scan_unevictable_node,
3318 write_scan_unevictable_node);
3319
3320int scan_unevictable_register_node(struct node *node)
3321{
3322 return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
3323}
3324
3325void scan_unevictable_unregister_node(struct node *node)
3326{
3327 sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
3328}
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003329#endif