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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/vmscan.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
12 */
13
14#include <linux/mm.h>
15#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090016#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/kernel_stat.h>
18#include <linux/swap.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/highmem.h>
Andrew Mortone129b5c2006-09-27 01:50:00 -070022#include <linux/vmstat.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/file.h>
24#include <linux/writeback.h>
25#include <linux/blkdev.h>
26#include <linux/buffer_head.h> /* for try_to_release_page(),
27 buffer_heads_over_limit */
28#include <linux/mm_inline.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/backing-dev.h>
30#include <linux/rmap.h>
31#include <linux/topology.h>
32#include <linux/cpu.h>
33#include <linux/cpuset.h>
Mel Gorman3e7d3442011-01-13 15:45:56 -080034#include <linux/compaction.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/notifier.h>
36#include <linux/rwsem.h>
Rafael J. Wysocki248a0302006-03-22 00:09:04 -080037#include <linux/delay.h>
Yasunori Goto3218ae12006-06-27 02:53:33 -070038#include <linux/kthread.h>
Nigel Cunningham7dfb7102006-12-06 20:34:23 -080039#include <linux/freezer.h>
Balbir Singh66e17072008-02-07 00:13:56 -080040#include <linux/memcontrol.h>
Keika Kobayashi873b4772008-07-25 01:48:52 -070041#include <linux/delayacct.h>
Lee Schermerhornaf936a12008-10-18 20:26:53 -070042#include <linux/sysctl.h>
KOSAKI Motohiro929bea72011-04-14 15:22:12 -070043#include <linux/oom.h>
Linus Torvalds268bb0c2011-05-20 12:50:29 -070044#include <linux/prefetch.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46#include <asm/tlbflush.h>
47#include <asm/div64.h>
48
49#include <linux/swapops.h>
50
Nick Piggin0f8053a2006-03-22 00:08:33 -080051#include "internal.h"
52
Mel Gorman33906bc2010-08-09 17:19:16 -070053#define CREATE_TRACE_POINTS
54#include <trace/events/vmscan.h>
55
Linus Torvalds1da177e2005-04-16 15:20:36 -070056struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 /* Incremented by the number of inactive pages that were scanned */
58 unsigned long nr_scanned;
59
Rik van Riela79311c2009-01-06 14:40:01 -080060 /* Number of pages freed so far during a call to shrink_zones() */
61 unsigned long nr_reclaimed;
62
KOSAKI Motohiro22fba332009-12-14 17:59:10 -080063 /* How many pages shrink_list() should reclaim */
64 unsigned long nr_to_reclaim;
65
KOSAKI Motohiro7b517552009-12-14 17:59:12 -080066 unsigned long hibernation_mode;
67
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040069 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
71 int may_writepage;
72
Johannes Weinera6dc60f82009-03-31 15:19:30 -070073 /* Can mapped pages be reclaimed? */
74 int may_unmap;
Christoph Lameterf1fd1062006-01-18 17:42:30 -080075
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -070076 /* Can pages be swapped as part of reclaim? */
77 int may_swap;
78
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070079 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080080
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -070081 /* Scan (total_size >> priority) pages at once */
82 int priority;
83
KOSAKI Motohiro5f53e762010-05-24 14:32:37 -070084 /*
Johannes Weinerf16015f2012-01-12 17:17:52 -080085 * The memory cgroup that hit its limit and as a result is the
86 * primary target of this reclaim invocation.
87 */
88 struct mem_cgroup *target_mem_cgroup;
Balbir Singh66e17072008-02-07 00:13:56 -080089
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -070090 /*
91 * Nodemask of nodes allowed by the caller. If NULL, all nodes
92 * are scanned.
93 */
94 nodemask_t *nodemask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070095};
96
Linus Torvalds1da177e2005-04-16 15:20:36 -070097#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
98
99#ifdef ARCH_HAS_PREFETCH
100#define prefetch_prev_lru_page(_page, _base, _field) \
101 do { \
102 if ((_page)->lru.prev != _base) { \
103 struct page *prev; \
104 \
105 prev = lru_to_page(&(_page->lru)); \
106 prefetch(&prev->_field); \
107 } \
108 } while (0)
109#else
110#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
111#endif
112
113#ifdef ARCH_HAS_PREFETCHW
114#define prefetchw_prev_lru_page(_page, _base, _field) \
115 do { \
116 if ((_page)->lru.prev != _base) { \
117 struct page *prev; \
118 \
119 prev = lru_to_page(&(_page->lru)); \
120 prefetchw(&prev->_field); \
121 } \
122 } while (0)
123#else
124#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
125#endif
126
127/*
128 * From 0 .. 100. Higher means more swappy.
129 */
130int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700131long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
133static LIST_HEAD(shrinker_list);
134static DECLARE_RWSEM(shrinker_rwsem);
135
Andrew Mortonc255a452012-07-31 16:43:02 -0700136#ifdef CONFIG_MEMCG
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800137static bool global_reclaim(struct scan_control *sc)
138{
Johannes Weinerf16015f2012-01-12 17:17:52 -0800139 return !sc->target_mem_cgroup;
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800140}
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800141#else
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800142static bool global_reclaim(struct scan_control *sc)
143{
144 return true;
145}
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800146#endif
147
Hugh Dickins4d7dcca2012-05-29 15:07:08 -0700148static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru)
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800149{
Hugh Dickinsc3c787e2012-05-29 15:06:52 -0700150 if (!mem_cgroup_disabled())
Hugh Dickins4d7dcca2012-05-29 15:07:08 -0700151 return mem_cgroup_get_lru_size(lruvec, lru);
KOSAKI Motohiroa3d8e052009-01-07 18:08:19 -0800152
Konstantin Khlebnikov074291f2012-05-29 15:07:00 -0700153 return zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru);
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800154}
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156/*
157 * Add a shrinker callback to be called from the vm
158 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700159void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160{
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800161 atomic_long_set(&shrinker->nr_in_batch, 0);
Rusty Russell8e1f9362007-07-17 04:03:17 -0700162 down_write(&shrinker_rwsem);
163 list_add_tail(&shrinker->list, &shrinker_list);
164 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700166EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167
168/*
169 * Remove one
170 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700171void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172{
173 down_write(&shrinker_rwsem);
174 list_del(&shrinker->list);
175 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700177EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
Ying Han1495f232011-05-24 17:12:27 -0700179static inline int do_shrinker_shrink(struct shrinker *shrinker,
180 struct shrink_control *sc,
181 unsigned long nr_to_scan)
182{
183 sc->nr_to_scan = nr_to_scan;
184 return (*shrinker->shrink)(shrinker, sc);
185}
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187#define SHRINK_BATCH 128
188/*
189 * Call the shrink functions to age shrinkable caches
190 *
191 * Here we assume it costs one seek to replace a lru page and that it also
192 * takes a seek to recreate a cache object. With this in mind we age equal
193 * percentages of the lru and ageable caches. This should balance the seeks
194 * generated by these structures.
195 *
Simon Arlott183ff222007-10-20 01:27:18 +0200196 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 * slab to avoid swapping.
198 *
199 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
200 *
201 * `lru_pages' represents the number of on-LRU pages in all the zones which
202 * are eligible for the caller's allocation attempt. It is used for balancing
203 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700204 *
205 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 */
Ying Hana09ed5e2011-05-24 17:12:26 -0700207unsigned long shrink_slab(struct shrink_control *shrink,
Ying Han1495f232011-05-24 17:12:27 -0700208 unsigned long nr_pages_scanned,
Ying Hana09ed5e2011-05-24 17:12:26 -0700209 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210{
211 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800212 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213
Ying Han1495f232011-05-24 17:12:27 -0700214 if (nr_pages_scanned == 0)
215 nr_pages_scanned = SWAP_CLUSTER_MAX;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Minchan Kimf06590b2011-05-24 17:11:11 -0700217 if (!down_read_trylock(&shrinker_rwsem)) {
218 /* Assume we'll be able to shrink next time */
219 ret = 1;
220 goto out;
221 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
223 list_for_each_entry(shrinker, &shrinker_list, list) {
224 unsigned long long delta;
Konstantin Khlebnikov635697c2011-12-08 14:33:51 -0800225 long total_scan;
226 long max_pass;
Dave Chinner09576072011-07-08 14:14:34 +1000227 int shrink_ret = 0;
Dave Chinneracf92b42011-07-08 14:14:35 +1000228 long nr;
229 long new_nr;
Dave Chinnere9299f52011-07-08 14:14:37 +1000230 long batch_size = shrinker->batch ? shrinker->batch
231 : SHRINK_BATCH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
Konstantin Khlebnikov635697c2011-12-08 14:33:51 -0800233 max_pass = do_shrinker_shrink(shrinker, shrink, 0);
234 if (max_pass <= 0)
235 continue;
236
Dave Chinneracf92b42011-07-08 14:14:35 +1000237 /*
238 * copy the current shrinker scan count into a local variable
239 * and zero it so that other concurrent shrinker invocations
240 * don't also do this scanning work.
241 */
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800242 nr = atomic_long_xchg(&shrinker->nr_in_batch, 0);
Dave Chinneracf92b42011-07-08 14:14:35 +1000243
244 total_scan = nr;
Ying Han1495f232011-05-24 17:12:27 -0700245 delta = (4 * nr_pages_scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800246 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 do_div(delta, lru_pages + 1);
Dave Chinneracf92b42011-07-08 14:14:35 +1000248 total_scan += delta;
249 if (total_scan < 0) {
David Rientjes88c3bd72009-03-31 15:23:29 -0700250 printk(KERN_ERR "shrink_slab: %pF negative objects to "
251 "delete nr=%ld\n",
Dave Chinneracf92b42011-07-08 14:14:35 +1000252 shrinker->shrink, total_scan);
253 total_scan = max_pass;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800254 }
255
256 /*
Dave Chinner3567b592011-07-08 14:14:36 +1000257 * We need to avoid excessive windup on filesystem shrinkers
258 * due to large numbers of GFP_NOFS allocations causing the
259 * shrinkers to return -1 all the time. This results in a large
260 * nr being built up so when a shrink that can do some work
261 * comes along it empties the entire cache due to nr >>>
262 * max_pass. This is bad for sustaining a working set in
263 * memory.
264 *
265 * Hence only allow the shrinker to scan the entire cache when
266 * a large delta change is calculated directly.
267 */
268 if (delta < max_pass / 4)
269 total_scan = min(total_scan, max_pass / 2);
270
271 /*
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800272 * Avoid risking looping forever due to too large nr value:
273 * never try to free more than twice the estimate number of
274 * freeable entries.
275 */
Dave Chinneracf92b42011-07-08 14:14:35 +1000276 if (total_scan > max_pass * 2)
277 total_scan = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278
Dave Chinneracf92b42011-07-08 14:14:35 +1000279 trace_mm_shrink_slab_start(shrinker, shrink, nr,
Dave Chinner09576072011-07-08 14:14:34 +1000280 nr_pages_scanned, lru_pages,
281 max_pass, delta, total_scan);
282
Dave Chinnere9299f52011-07-08 14:14:37 +1000283 while (total_scan >= batch_size) {
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700284 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Ying Han1495f232011-05-24 17:12:27 -0700286 nr_before = do_shrinker_shrink(shrinker, shrink, 0);
287 shrink_ret = do_shrinker_shrink(shrinker, shrink,
Dave Chinnere9299f52011-07-08 14:14:37 +1000288 batch_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 if (shrink_ret == -1)
290 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700291 if (shrink_ret < nr_before)
292 ret += nr_before - shrink_ret;
Dave Chinnere9299f52011-07-08 14:14:37 +1000293 count_vm_events(SLABS_SCANNED, batch_size);
294 total_scan -= batch_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295
296 cond_resched();
297 }
298
Dave Chinneracf92b42011-07-08 14:14:35 +1000299 /*
300 * move the unused scan count back into the shrinker in a
301 * manner that handles concurrent updates. If we exhausted the
302 * scan, there is no need to do an update.
303 */
Konstantin Khlebnikov83aeead2011-12-08 14:33:54 -0800304 if (total_scan > 0)
305 new_nr = atomic_long_add_return(total_scan,
306 &shrinker->nr_in_batch);
307 else
308 new_nr = atomic_long_read(&shrinker->nr_in_batch);
Dave Chinneracf92b42011-07-08 14:14:35 +1000309
310 trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 }
312 up_read(&shrinker_rwsem);
Minchan Kimf06590b2011-05-24 17:11:11 -0700313out:
314 cond_resched();
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700315 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316}
317
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318static inline int is_page_cache_freeable(struct page *page)
319{
Johannes Weinerceddc3a2009-09-21 17:03:00 -0700320 /*
321 * A freeable page cache page is referenced only by the caller
322 * that isolated the page, the page cache radix tree and
323 * optional buffer heads at page->private.
324 */
Johannes Weineredcf4742009-09-21 17:02:59 -0700325 return page_count(page) - page_has_private(page) == 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326}
327
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700328static int may_write_to_queue(struct backing_dev_info *bdi,
329 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330{
Christoph Lameter930d9152006-01-08 01:00:47 -0800331 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 return 1;
333 if (!bdi_write_congested(bdi))
334 return 1;
335 if (bdi == current->backing_dev_info)
336 return 1;
337 return 0;
338}
339
340/*
341 * We detected a synchronous write error writing a page out. Probably
342 * -ENOSPC. We need to propagate that into the address_space for a subsequent
343 * fsync(), msync() or close().
344 *
345 * The tricky part is that after writepage we cannot touch the mapping: nothing
346 * prevents it from being freed up. But we have a ref on the page and once
347 * that page is locked, the mapping is pinned.
348 *
349 * We're allowed to run sleeping lock_page() here because we know the caller has
350 * __GFP_FS.
351 */
352static void handle_write_error(struct address_space *mapping,
353 struct page *page, int error)
354{
Jens Axboe7eaceac2011-03-10 08:52:07 +0100355 lock_page(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700356 if (page_mapping(page) == mapping)
357 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 unlock_page(page);
359}
360
Christoph Lameter04e62a22006-06-23 02:03:38 -0700361/* possible outcome of pageout() */
362typedef enum {
363 /* failed to write page out, page is locked */
364 PAGE_KEEP,
365 /* move page to the active list, page is locked */
366 PAGE_ACTIVATE,
367 /* page has been sent to the disk successfully, page is unlocked */
368 PAGE_SUCCESS,
369 /* page is clean and locked */
370 PAGE_CLEAN,
371} pageout_t;
372
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373/*
Andrew Morton1742f192006-03-22 00:08:21 -0800374 * pageout is called by shrink_page_list() for each dirty page.
375 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700377static pageout_t pageout(struct page *page, struct address_space *mapping,
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700378 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379{
380 /*
381 * If the page is dirty, only perform writeback if that write
382 * will be non-blocking. To prevent this allocation from being
383 * stalled by pagecache activity. But note that there may be
384 * stalls if we need to run get_block(). We could test
385 * PagePrivate for that.
386 *
Vincent Li6aceb532009-12-14 17:58:49 -0800387 * If this process is currently in __generic_file_aio_write() against
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 * this page's queue, we can perform writeback even if that
389 * will block.
390 *
391 * If the page is swapcache, write it back even if that would
392 * block, for some throttling. This happens by accident, because
393 * swap_backing_dev_info is bust: it doesn't reflect the
394 * congestion state of the swapdevs. Easy to fix, if needed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 */
396 if (!is_page_cache_freeable(page))
397 return PAGE_KEEP;
398 if (!mapping) {
399 /*
400 * Some data journaling orphaned pages can have
401 * page->mapping == NULL while being dirty with clean buffers.
402 */
David Howells266cf652009-04-03 16:42:36 +0100403 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 if (try_to_free_buffers(page)) {
405 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700406 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 return PAGE_CLEAN;
408 }
409 }
410 return PAGE_KEEP;
411 }
412 if (mapping->a_ops->writepage == NULL)
413 return PAGE_ACTIVATE;
Mel Gorman0e093d992010-10-26 14:21:45 -0700414 if (!may_write_to_queue(mapping->backing_dev_info, sc))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 return PAGE_KEEP;
416
417 if (clear_page_dirty_for_io(page)) {
418 int res;
419 struct writeback_control wbc = {
420 .sync_mode = WB_SYNC_NONE,
421 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700422 .range_start = 0,
423 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 .for_reclaim = 1,
425 };
426
427 SetPageReclaim(page);
428 res = mapping->a_ops->writepage(page, &wbc);
429 if (res < 0)
430 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800431 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 ClearPageReclaim(page);
433 return PAGE_ACTIVATE;
434 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700435
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 if (!PageWriteback(page)) {
437 /* synchronous write or broken a_ops? */
438 ClearPageReclaim(page);
439 }
Mel Gorman23b9da52012-05-29 15:06:20 -0700440 trace_mm_vmscan_writepage(page, trace_reclaim_flags(page));
Andrew Mortone129b5c2006-09-27 01:50:00 -0700441 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 return PAGE_SUCCESS;
443 }
444
445 return PAGE_CLEAN;
446}
447
Andrew Mortona649fd92006-10-17 00:09:36 -0700448/*
Nick Piggine2867812008-07-25 19:45:30 -0700449 * Same as remove_mapping, but if the page is removed from the mapping, it
450 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700451 */
Nick Piggine2867812008-07-25 19:45:30 -0700452static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800453{
Nick Piggin28e4d962006-09-25 23:31:23 -0700454 BUG_ON(!PageLocked(page));
455 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800456
Nick Piggin19fd6232008-07-25 19:45:32 -0700457 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800458 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700459 * The non racy check for a busy page.
460 *
461 * Must be careful with the order of the tests. When someone has
462 * a ref to the page, it may be possible that they dirty it then
463 * drop the reference. So if PageDirty is tested before page_count
464 * here, then the following race may occur:
465 *
466 * get_user_pages(&page);
467 * [user mapping goes away]
468 * write_to(page);
469 * !PageDirty(page) [good]
470 * SetPageDirty(page);
471 * put_page(page);
472 * !page_count(page) [good, discard it]
473 *
474 * [oops, our write_to data is lost]
475 *
476 * Reversing the order of the tests ensures such a situation cannot
477 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
478 * load is not satisfied before that of page->_count.
479 *
480 * Note that if SetPageDirty is always performed via set_page_dirty,
481 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800482 */
Nick Piggine2867812008-07-25 19:45:30 -0700483 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800484 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700485 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
486 if (unlikely(PageDirty(page))) {
487 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800488 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700489 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800490
491 if (PageSwapCache(page)) {
492 swp_entry_t swap = { .val = page_private(page) };
493 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700494 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -0700495 swapcache_free(swap, page);
Nick Piggine2867812008-07-25 19:45:30 -0700496 } else {
Linus Torvalds6072d132010-12-01 13:35:19 -0500497 void (*freepage)(struct page *);
498
499 freepage = mapping->a_ops->freepage;
500
Minchan Kime64a7822011-03-22 16:32:44 -0700501 __delete_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700502 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700503 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500504
505 if (freepage != NULL)
506 freepage(page);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800507 }
508
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800509 return 1;
510
511cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700512 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800513 return 0;
514}
515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516/*
Nick Piggine2867812008-07-25 19:45:30 -0700517 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
518 * someone else has a ref on the page, abort and return 0. If it was
519 * successfully detached, return 1. Assumes the caller has a single ref on
520 * this page.
521 */
522int remove_mapping(struct address_space *mapping, struct page *page)
523{
524 if (__remove_mapping(mapping, page)) {
525 /*
526 * Unfreezing the refcount with 1 rather than 2 effectively
527 * drops the pagecache ref for us without requiring another
528 * atomic operation.
529 */
530 page_unfreeze_refs(page, 1);
531 return 1;
532 }
533 return 0;
534}
535
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700536/**
537 * putback_lru_page - put previously isolated page onto appropriate LRU list
538 * @page: page to be put back to appropriate lru list
539 *
540 * Add previously isolated @page to appropriate LRU list.
541 * Page may still be unevictable for other reasons.
542 *
543 * lru_lock must not be held, interrupts must be enabled.
544 */
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700545void putback_lru_page(struct page *page)
546{
547 int lru;
548 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700549 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700550
551 VM_BUG_ON(PageLRU(page));
552
553redo:
554 ClearPageUnevictable(page);
555
Hugh Dickins39b5f292012-10-08 16:33:18 -0700556 if (page_evictable(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700557 /*
558 * For evictable pages, we can use the cache.
559 * In event of a race, worst case is we end up with an
560 * unevictable page on [in]active list.
561 * We know how to handle that.
562 */
Johannes Weiner401a8e12009-09-21 17:02:58 -0700563 lru = active + page_lru_base_type(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700564 lru_cache_add_lru(page, lru);
565 } else {
566 /*
567 * Put unevictable pages directly on zone's unevictable
568 * list.
569 */
570 lru = LRU_UNEVICTABLE;
571 add_page_to_unevictable_list(page);
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700572 /*
Minchan Kim21ee9f32011-10-31 17:09:28 -0700573 * When racing with an mlock or AS_UNEVICTABLE clearing
574 * (page is unlocked) make sure that if the other thread
575 * does not observe our setting of PG_lru and fails
Hugh Dickins24513262012-01-20 14:34:21 -0800576 * isolation/check_move_unevictable_pages,
Minchan Kim21ee9f32011-10-31 17:09:28 -0700577 * we see PG_mlocked/AS_UNEVICTABLE cleared below and move
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700578 * the page back to the evictable list.
579 *
Minchan Kim21ee9f32011-10-31 17:09:28 -0700580 * The other side is TestClearPageMlocked() or shmem_lock().
Johannes Weiner6a7b9542009-10-26 16:50:00 -0700581 */
582 smp_mb();
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700583 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700584
585 /*
586 * page's status can change while we move it among lru. If an evictable
587 * page is on unevictable list, it never be freed. To avoid that,
588 * check after we added it to the list, again.
589 */
Hugh Dickins39b5f292012-10-08 16:33:18 -0700590 if (lru == LRU_UNEVICTABLE && page_evictable(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700591 if (!isolate_lru_page(page)) {
592 put_page(page);
593 goto redo;
594 }
595 /* This means someone else dropped this page from LRU
596 * So, it will be freed or putback to LRU again. There is
597 * nothing to do here.
598 */
599 }
600
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700601 if (was_unevictable && lru != LRU_UNEVICTABLE)
602 count_vm_event(UNEVICTABLE_PGRESCUED);
603 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
604 count_vm_event(UNEVICTABLE_PGCULLED);
605
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700606 put_page(page); /* drop ref from isolate */
607}
608
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800609enum page_references {
610 PAGEREF_RECLAIM,
611 PAGEREF_RECLAIM_CLEAN,
Johannes Weiner645747462010-03-05 13:42:22 -0800612 PAGEREF_KEEP,
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800613 PAGEREF_ACTIVATE,
614};
615
616static enum page_references page_check_references(struct page *page,
617 struct scan_control *sc)
618{
Johannes Weiner645747462010-03-05 13:42:22 -0800619 int referenced_ptes, referenced_page;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800620 unsigned long vm_flags;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800621
Johannes Weinerc3ac9a82012-05-29 15:06:25 -0700622 referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
623 &vm_flags);
Johannes Weiner645747462010-03-05 13:42:22 -0800624 referenced_page = TestClearPageReferenced(page);
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800625
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800626 /*
627 * Mlock lost the isolation race with us. Let try_to_unmap()
628 * move the page to the unevictable list.
629 */
630 if (vm_flags & VM_LOCKED)
631 return PAGEREF_RECLAIM;
632
Johannes Weiner645747462010-03-05 13:42:22 -0800633 if (referenced_ptes) {
Michal Hockoe48982732012-05-29 15:06:45 -0700634 if (PageSwapBacked(page))
Johannes Weiner645747462010-03-05 13:42:22 -0800635 return PAGEREF_ACTIVATE;
636 /*
637 * All mapped pages start out with page table
638 * references from the instantiating fault, so we need
639 * to look twice if a mapped file page is used more
640 * than once.
641 *
642 * Mark it and spare it for another trip around the
643 * inactive list. Another page table reference will
644 * lead to its activation.
645 *
646 * Note: the mark is set for activated pages as well
647 * so that recently deactivated but used pages are
648 * quickly recovered.
649 */
650 SetPageReferenced(page);
651
Konstantin Khlebnikov34dbc672012-01-10 15:06:59 -0800652 if (referenced_page || referenced_ptes > 1)
Johannes Weiner645747462010-03-05 13:42:22 -0800653 return PAGEREF_ACTIVATE;
654
Konstantin Khlebnikovc909e992012-01-10 15:07:03 -0800655 /*
656 * Activate file-backed executable pages after first usage.
657 */
658 if (vm_flags & VM_EXEC)
659 return PAGEREF_ACTIVATE;
660
Johannes Weiner645747462010-03-05 13:42:22 -0800661 return PAGEREF_KEEP;
662 }
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800663
664 /* Reclaim if clean, defer dirty pages to writeback */
KOSAKI Motohiro2e302442010-10-26 14:21:46 -0700665 if (referenced_page && !PageSwapBacked(page))
Johannes Weiner645747462010-03-05 13:42:22 -0800666 return PAGEREF_RECLAIM_CLEAN;
667
668 return PAGEREF_RECLAIM;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800669}
670
Nick Piggine2867812008-07-25 19:45:30 -0700671/*
Andrew Morton1742f192006-03-22 00:08:21 -0800672 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 */
Andrew Morton1742f192006-03-22 00:08:21 -0800674static unsigned long shrink_page_list(struct list_head *page_list,
Konstantin Khlebnikov6a18adb2012-05-29 15:06:59 -0700675 struct zone *zone,
Mel Gormanf84f6e22011-10-31 17:07:51 -0700676 struct scan_control *sc,
Minchan Kim02c6de82012-10-08 16:31:55 -0700677 enum ttu_flags ttu_flags,
Mel Gorman92df3a72011-10-31 17:07:56 -0700678 unsigned long *ret_nr_dirty,
Minchan Kim02c6de82012-10-08 16:31:55 -0700679 unsigned long *ret_nr_writeback,
680 bool force_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681{
682 LIST_HEAD(ret_pages);
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700683 LIST_HEAD(free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 int pgactivate = 0;
Mel Gorman0e093d992010-10-26 14:21:45 -0700685 unsigned long nr_dirty = 0;
686 unsigned long nr_congested = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800687 unsigned long nr_reclaimed = 0;
Mel Gorman92df3a72011-10-31 17:07:56 -0700688 unsigned long nr_writeback = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689
690 cond_resched();
691
Tim Chen69980e32012-07-31 16:46:08 -0700692 mem_cgroup_uncharge_start();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 while (!list_empty(page_list)) {
694 struct address_space *mapping;
695 struct page *page;
696 int may_enter_fs;
Minchan Kim02c6de82012-10-08 16:31:55 -0700697 enum page_references references = PAGEREF_RECLAIM_CLEAN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
699 cond_resched();
700
701 page = lru_to_page(page_list);
702 list_del(&page->lru);
703
Nick Piggin529ae9a2008-08-02 12:01:03 +0200704 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 goto keep;
706
Nick Piggin725d7042006-09-25 23:30:55 -0700707 VM_BUG_ON(PageActive(page));
Konstantin Khlebnikov6a18adb2012-05-29 15:06:59 -0700708 VM_BUG_ON(page_zone(page) != zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709
710 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800711
Hugh Dickins39b5f292012-10-08 16:33:18 -0700712 if (unlikely(!page_evictable(page)))
Nick Pigginb291f002008-10-18 20:26:44 -0700713 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700714
Johannes Weinera6dc60f82009-03-31 15:19:30 -0700715 if (!sc->may_unmap && page_mapped(page))
Christoph Lameter80e43422006-02-11 17:55:53 -0800716 goto keep_locked;
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 /* Double the slab pressure for mapped and swapcache pages */
719 if (page_mapped(page) || PageSwapCache(page))
720 sc->nr_scanned++;
721
Andy Whitcroftc661b072007-08-22 14:01:26 -0700722 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
723 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
724
725 if (PageWriteback(page)) {
Michal Hockoe62e3842012-07-31 16:45:55 -0700726 /*
727 * memcg doesn't have any dirty pages throttling so we
728 * could easily OOM just because too many pages are in
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700729 * writeback and there is nothing else to reclaim.
Michal Hockoe62e3842012-07-31 16:45:55 -0700730 *
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700731 * Check __GFP_IO, certainly because a loop driver
Michal Hockoe62e3842012-07-31 16:45:55 -0700732 * thread might enter reclaim, and deadlock if it waits
733 * on a page for which it is needed to do the write
734 * (loop masks off __GFP_IO|__GFP_FS for this reason);
735 * but more thought would probably show more reasons.
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700736 *
737 * Don't require __GFP_FS, since we're not going into
738 * the FS, just waiting on its writeback completion.
739 * Worryingly, ext4 gfs2 and xfs allocate pages with
740 * grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so
741 * testing may_enter_fs here is liable to OOM on them.
Michal Hockoe62e3842012-07-31 16:45:55 -0700742 */
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700743 if (global_reclaim(sc) ||
744 !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) {
745 /*
746 * This is slightly racy - end_page_writeback()
747 * might have just cleared PageReclaim, then
748 * setting PageReclaim here end up interpreted
749 * as PageReadahead - but that does not matter
750 * enough to care. What we do want is for this
751 * page to have PageReclaim set next time memcg
752 * reclaim reaches the tests above, so it will
753 * then wait_on_page_writeback() to avoid OOM;
754 * and it's also appropriate in global reclaim.
755 */
756 SetPageReclaim(page);
Michal Hockoe62e3842012-07-31 16:45:55 -0700757 nr_writeback++;
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700758 goto keep_locked;
Michal Hockoe62e3842012-07-31 16:45:55 -0700759 }
Hugh Dickinsc3b94f42012-07-31 16:45:59 -0700760 wait_on_page_writeback(page);
Andy Whitcroftc661b072007-08-22 14:01:26 -0700761 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Minchan Kim02c6de82012-10-08 16:31:55 -0700763 if (!force_reclaim)
764 references = page_check_references(page, sc);
765
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800766 switch (references) {
767 case PAGEREF_ACTIVATE:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 goto activate_locked;
Johannes Weiner645747462010-03-05 13:42:22 -0800769 case PAGEREF_KEEP:
770 goto keep_locked;
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800771 case PAGEREF_RECLAIM:
772 case PAGEREF_RECLAIM_CLEAN:
773 ; /* try to reclaim the page below */
774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 /*
777 * Anonymous process memory has backing store?
778 * Try to allocate it some swap space here.
779 */
Nick Pigginb291f002008-10-18 20:26:44 -0700780 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800781 if (!(sc->gfp_mask & __GFP_IO))
782 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800783 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800785 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700786 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787
788 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
790 /*
791 * The page is mapped into the page tables of one or more
792 * processes. Try to unmap it here.
793 */
794 if (page_mapped(page) && mapping) {
Minchan Kim02c6de82012-10-08 16:31:55 -0700795 switch (try_to_unmap(page, ttu_flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 case SWAP_FAIL:
797 goto activate_locked;
798 case SWAP_AGAIN:
799 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700800 case SWAP_MLOCK:
801 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 case SWAP_SUCCESS:
803 ; /* try to free the page below */
804 }
805 }
806
807 if (PageDirty(page)) {
Mel Gorman0e093d992010-10-26 14:21:45 -0700808 nr_dirty++;
809
Mel Gormanee728862011-10-31 17:07:38 -0700810 /*
811 * Only kswapd can writeback filesystem pages to
Mel Gormanf84f6e22011-10-31 17:07:51 -0700812 * avoid risk of stack overflow but do not writeback
813 * unless under significant pressure.
Mel Gormanee728862011-10-31 17:07:38 -0700814 */
Mel Gormanf84f6e22011-10-31 17:07:51 -0700815 if (page_is_file_cache(page) &&
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -0700816 (!current_is_kswapd() ||
817 sc->priority >= DEF_PRIORITY - 2)) {
Mel Gorman49ea7eb2011-10-31 17:07:59 -0700818 /*
819 * Immediately reclaim when written back.
820 * Similar in principal to deactivate_page()
821 * except we already have the page isolated
822 * and know it's dirty
823 */
824 inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE);
825 SetPageReclaim(page);
826
Mel Gormanee728862011-10-31 17:07:38 -0700827 goto keep_locked;
828 }
829
Johannes Weinerdfc8d632010-03-05 13:42:19 -0800830 if (references == PAGEREF_RECLAIM_CLEAN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700832 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800834 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 goto keep_locked;
836
837 /* Page is dirty, try to write it out here */
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700838 switch (pageout(page, mapping, sc)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 case PAGE_KEEP:
Mel Gorman0e093d992010-10-26 14:21:45 -0700840 nr_congested++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 goto keep_locked;
842 case PAGE_ACTIVATE:
843 goto activate_locked;
844 case PAGE_SUCCESS:
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700845 if (PageWriteback(page))
Mel Gorman41ac1992012-05-29 15:06:19 -0700846 goto keep;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700847 if (PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 goto keep;
KOSAKI Motohiro7d3579e2010-10-26 14:21:42 -0700849
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 /*
851 * A synchronous write - probably a ramdisk. Go
852 * ahead and try to reclaim the page.
853 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200854 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 goto keep;
856 if (PageDirty(page) || PageWriteback(page))
857 goto keep_locked;
858 mapping = page_mapping(page);
859 case PAGE_CLEAN:
860 ; /* try to free the page below */
861 }
862 }
863
864 /*
865 * If the page has buffers, try to free the buffer mappings
866 * associated with this page. If we succeed we try to free
867 * the page as well.
868 *
869 * We do this even if the page is PageDirty().
870 * try_to_release_page() does not perform I/O, but it is
871 * possible for a page to have PageDirty set, but it is actually
872 * clean (all its buffers are clean). This happens if the
873 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700874 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 * try_to_release_page() will discover that cleanness and will
876 * drop the buffers and mark the page clean - it can be freed.
877 *
878 * Rarely, pages can have buffers and no ->mapping. These are
879 * the pages which were not successfully invalidated in
880 * truncate_complete_page(). We try to drop those buffers here
881 * and if that worked, and the page is no longer mapped into
882 * process address space (page_count == 1) it can be freed.
883 * Otherwise, leave the page on the LRU so it is swappable.
884 */
David Howells266cf652009-04-03 16:42:36 +0100885 if (page_has_private(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 if (!try_to_release_page(page, sc->gfp_mask))
887 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700888 if (!mapping && page_count(page) == 1) {
889 unlock_page(page);
890 if (put_page_testzero(page))
891 goto free_it;
892 else {
893 /*
894 * rare race with speculative reference.
895 * the speculative reference will free
896 * this page shortly, so we may
897 * increment nr_reclaimed here (and
898 * leave it off the LRU).
899 */
900 nr_reclaimed++;
901 continue;
902 }
903 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 }
905
Nick Piggine2867812008-07-25 19:45:30 -0700906 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800907 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908
Nick Piggina978d6f2008-10-18 20:26:58 -0700909 /*
910 * At this point, we have no other references and there is
911 * no way to pick any more up (removed from LRU, removed
912 * from pagecache). Can use non-atomic bitops now (and
913 * we obviously don't have to worry about waking up a process
914 * waiting on the page lock, because there are no references.
915 */
916 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700917free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800918 nr_reclaimed++;
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700919
920 /*
921 * Is there need to periodically free_page_list? It would
922 * appear not as the counts should be low
923 */
924 list_add(&page->lru, &free_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 continue;
926
Nick Pigginb291f002008-10-18 20:26:44 -0700927cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800928 if (PageSwapCache(page))
929 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700930 unlock_page(page);
931 putback_lru_page(page);
932 continue;
933
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700935 /* Not a candidate for swapping, so reclaim swap space. */
936 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800937 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700938 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 SetPageActive(page);
940 pgactivate++;
941keep_locked:
942 unlock_page(page);
943keep:
944 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700945 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 }
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700947
Mel Gorman0e093d992010-10-26 14:21:45 -0700948 /*
949 * Tag a zone as congested if all the dirty pages encountered were
950 * backed by a congested BDI. In this case, reclaimers should just
951 * back off and wait for congestion to clear because further reclaim
952 * will encounter the same problem
953 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -0800954 if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))
Konstantin Khlebnikov6a18adb2012-05-29 15:06:59 -0700955 zone_set_flag(zone, ZONE_CONGESTED);
Mel Gorman0e093d992010-10-26 14:21:45 -0700956
Konstantin Khlebnikovcc598502012-01-10 15:07:04 -0800957 free_hot_cold_page_list(&free_pages, 1);
Mel Gormanabe4c3b2010-08-09 17:19:31 -0700958
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 list_splice(&ret_pages, page_list);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700960 count_vm_events(PGACTIVATE, pgactivate);
Tim Chen69980e32012-07-31 16:46:08 -0700961 mem_cgroup_uncharge_end();
Mel Gorman92df3a72011-10-31 17:07:56 -0700962 *ret_nr_dirty += nr_dirty;
963 *ret_nr_writeback += nr_writeback;
Andrew Morton05ff5132006-03-22 00:08:20 -0800964 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965}
966
Minchan Kim02c6de82012-10-08 16:31:55 -0700967unsigned long reclaim_clean_pages_from_list(struct zone *zone,
968 struct list_head *page_list)
969{
970 struct scan_control sc = {
971 .gfp_mask = GFP_KERNEL,
972 .priority = DEF_PRIORITY,
973 .may_unmap = 1,
974 };
975 unsigned long ret, dummy1, dummy2;
976 struct page *page, *next;
977 LIST_HEAD(clean_pages);
978
979 list_for_each_entry_safe(page, next, page_list, lru) {
980 if (page_is_file_cache(page) && !PageDirty(page)) {
981 ClearPageActive(page);
982 list_move(&page->lru, &clean_pages);
983 }
984 }
985
986 ret = shrink_page_list(&clean_pages, zone, &sc,
987 TTU_UNMAP|TTU_IGNORE_ACCESS,
988 &dummy1, &dummy2, true);
989 list_splice(&clean_pages, page_list);
990 __mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
991 return ret;
992}
993
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700994/*
995 * Attempt to remove the specified page from its LRU. Only take this page
996 * if it is of the appropriate PageActive status. Pages which are being
997 * freed elsewhere are also ignored.
998 *
999 * page: page to consider
1000 * mode: one of the LRU isolation modes defined above
1001 *
1002 * returns 0 on success, -ve errno on failure.
1003 */
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -07001004int __isolate_lru_page(struct page *page, isolate_mode_t mode)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001005{
1006 int ret = -EINVAL;
1007
1008 /* Only take pages on the LRU. */
1009 if (!PageLRU(page))
1010 return ret;
1011
Minchan Kime46a2872012-10-08 16:33:48 -07001012 /* Compaction should not handle unevictable pages but CMA can do so */
1013 if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001014 return ret;
1015
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001016 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08001017
Mel Gormanc8244932012-01-12 17:19:38 -08001018 /*
1019 * To minimise LRU disruption, the caller can indicate that it only
1020 * wants to isolate pages it will be able to operate on without
1021 * blocking - clean pages for the most part.
1022 *
1023 * ISOLATE_CLEAN means that only clean pages should be isolated. This
1024 * is used by reclaim when it is cannot write to backing storage
1025 *
1026 * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages
1027 * that it is possible to migrate without blocking
1028 */
1029 if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {
1030 /* All the caller can do on PageWriteback is block */
1031 if (PageWriteback(page))
1032 return ret;
1033
1034 if (PageDirty(page)) {
1035 struct address_space *mapping;
1036
1037 /* ISOLATE_CLEAN means only clean pages */
1038 if (mode & ISOLATE_CLEAN)
1039 return ret;
1040
1041 /*
1042 * Only pages without mappings or that have a
1043 * ->migratepage callback are possible to migrate
1044 * without blocking
1045 */
1046 mapping = page_mapping(page);
1047 if (mapping && !mapping->a_ops->migratepage)
1048 return ret;
1049 }
1050 }
Minchan Kim39deaf82011-10-31 17:06:51 -07001051
Minchan Kimf80c0672011-10-31 17:06:55 -07001052 if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
1053 return ret;
1054
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001055 if (likely(get_page_unless_zero(page))) {
1056 /*
1057 * Be careful not to clear PageLRU until after we're
1058 * sure the page is not being freed elsewhere -- the
1059 * page release code relies on it.
1060 */
1061 ClearPageLRU(page);
1062 ret = 0;
1063 }
1064
1065 return ret;
1066}
1067
Christoph Lameter49d2e9c2006-01-08 01:00:48 -08001068/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 * zone->lru_lock is heavily contended. Some of the functions that
1070 * shrink the lists perform better by taking out a batch of pages
1071 * and working on them outside the LRU lock.
1072 *
1073 * For pagecache intensive workloads, this function is the hottest
1074 * spot in the kernel (apart from copy_*_user functions).
1075 *
1076 * Appropriate locks must be held before calling this function.
1077 *
1078 * @nr_to_scan: The number of pages to look through on the list.
Konstantin Khlebnikov5dc35972012-05-29 15:06:58 -07001079 * @lruvec: The LRU vector to pull pages from.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 * @dst: The temp list to put pages on to.
Hugh Dickinsf6260122012-01-12 17:20:06 -08001081 * @nr_scanned: The number of pages that were scanned.
Rik van Rielfe2c2a12012-03-21 16:33:51 -07001082 * @sc: The scan_control struct for this reclaim session
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001083 * @mode: One of the LRU isolation modes
Konstantin Khlebnikov3cb99452012-05-29 15:06:53 -07001084 * @lru: LRU list id for isolating
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 *
1086 * returns how many pages were moved onto *@dst.
1087 */
Andrew Morton69e05942006-03-22 00:08:19 -08001088static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
Konstantin Khlebnikov5dc35972012-05-29 15:06:58 -07001089 struct lruvec *lruvec, struct list_head *dst,
Rik van Rielfe2c2a12012-03-21 16:33:51 -07001090 unsigned long *nr_scanned, struct scan_control *sc,
Konstantin Khlebnikov3cb99452012-05-29 15:06:53 -07001091 isolate_mode_t mode, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092{
Hugh Dickins75b00af2012-05-29 15:07:09 -07001093 struct list_head *src = &lruvec->lists[lru];
Andrew Morton69e05942006-03-22 00:08:19 -08001094 unsigned long nr_taken = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001095 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096
Wu Fengguangc9b02d92006-03-22 00:08:23 -08001097 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001098 struct page *page;
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001099 int nr_pages;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 page = lru_to_page(src);
1102 prefetchw_prev_lru_page(page, src, flags);
1103
Nick Piggin725d7042006-09-25 23:30:55 -07001104 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001105
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -07001106 switch (__isolate_lru_page(page, mode)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001107 case 0:
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001108 nr_pages = hpage_nr_pages(page);
1109 mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001110 list_move(&page->lru, dst);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001111 nr_taken += nr_pages;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001112 break;
Nick Piggin46453a62006-03-22 00:07:58 -08001113
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001114 case -EBUSY:
1115 /* else it is being freed elsewhere */
1116 list_move(&page->lru, src);
1117 continue;
1118
1119 default:
1120 BUG();
1121 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 }
1123
Hugh Dickinsf6260122012-01-12 17:20:06 -08001124 *nr_scanned = scan;
Hugh Dickins75b00af2012-05-29 15:07:09 -07001125 trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan,
1126 nr_taken, mode, is_file_lru(lru));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 return nr_taken;
1128}
1129
Nick Piggin62695a82008-10-18 20:26:09 -07001130/**
1131 * isolate_lru_page - tries to isolate a page from its LRU list
1132 * @page: page to isolate from its LRU list
1133 *
1134 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1135 * vmstat statistic corresponding to whatever LRU list the page was on.
1136 *
1137 * Returns 0 if the page was removed from an LRU list.
1138 * Returns -EBUSY if the page was not on an LRU list.
1139 *
1140 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001141 * the active list, it will have PageActive set. If it was found on
1142 * the unevictable list, it will have the PageUnevictable bit set. That flag
1143 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001144 *
1145 * The vmstat statistic corresponding to the list on which the page was
1146 * found will be decremented.
1147 *
1148 * Restrictions:
1149 * (1) Must be called with an elevated refcount on the page. This is a
1150 * fundamentnal difference from isolate_lru_pages (which is called
1151 * without a stable reference).
1152 * (2) the lru_lock must not be held.
1153 * (3) interrupts must be enabled.
1154 */
1155int isolate_lru_page(struct page *page)
1156{
1157 int ret = -EBUSY;
1158
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001159 VM_BUG_ON(!page_count(page));
1160
Nick Piggin62695a82008-10-18 20:26:09 -07001161 if (PageLRU(page)) {
1162 struct zone *zone = page_zone(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001163 struct lruvec *lruvec;
Nick Piggin62695a82008-10-18 20:26:09 -07001164
1165 spin_lock_irq(&zone->lru_lock);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001166 lruvec = mem_cgroup_page_lruvec(page, zone);
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001167 if (PageLRU(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001168 int lru = page_lru(page);
Konstantin Khlebnikov0c917312011-05-24 17:12:21 -07001169 get_page(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001170 ClearPageLRU(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001171 del_page_from_lru_list(page, lruvec, lru);
1172 ret = 0;
Nick Piggin62695a82008-10-18 20:26:09 -07001173 }
1174 spin_unlock_irq(&zone->lru_lock);
1175 }
1176 return ret;
1177}
1178
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001179/*
Fengguang Wud37dd5d2012-12-18 14:23:28 -08001180 * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and
1181 * then get resheduled. When there are massive number of tasks doing page
1182 * allocation, such sleeping direct reclaimers may keep piling up on each CPU,
1183 * the LRU list will go small and be scanned faster than necessary, leading to
1184 * unnecessary swapping, thrashing and OOM.
Rik van Riel35cd7812009-09-21 17:01:38 -07001185 */
1186static int too_many_isolated(struct zone *zone, int file,
1187 struct scan_control *sc)
1188{
1189 unsigned long inactive, isolated;
1190
1191 if (current_is_kswapd())
1192 return 0;
1193
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001194 if (!global_reclaim(sc))
Rik van Riel35cd7812009-09-21 17:01:38 -07001195 return 0;
1196
1197 if (file) {
1198 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1199 isolated = zone_page_state(zone, NR_ISOLATED_FILE);
1200 } else {
1201 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1202 isolated = zone_page_state(zone, NR_ISOLATED_ANON);
1203 }
1204
Fengguang Wu3cf23842012-12-18 14:23:31 -08001205 /*
1206 * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
1207 * won't get blocked by normal direct-reclaimers, forming a circular
1208 * deadlock.
1209 */
1210 if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS)
1211 inactive >>= 3;
1212
Rik van Riel35cd7812009-09-21 17:01:38 -07001213 return isolated > inactive;
1214}
1215
Mel Gorman66635622010-08-09 17:19:30 -07001216static noinline_for_stack void
Hugh Dickins75b00af2012-05-29 15:07:09 -07001217putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
Mel Gorman66635622010-08-09 17:19:30 -07001218{
Konstantin Khlebnikov27ac81d2012-05-29 15:07:00 -07001219 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
1220 struct zone *zone = lruvec_zone(lruvec);
Hugh Dickins3f797682012-01-12 17:20:07 -08001221 LIST_HEAD(pages_to_free);
Mel Gorman66635622010-08-09 17:19:30 -07001222
Mel Gorman66635622010-08-09 17:19:30 -07001223 /*
1224 * Put back any unfreeable pages.
1225 */
Mel Gorman66635622010-08-09 17:19:30 -07001226 while (!list_empty(page_list)) {
Hugh Dickins3f797682012-01-12 17:20:07 -08001227 struct page *page = lru_to_page(page_list);
Mel Gorman66635622010-08-09 17:19:30 -07001228 int lru;
Hugh Dickins3f797682012-01-12 17:20:07 -08001229
Mel Gorman66635622010-08-09 17:19:30 -07001230 VM_BUG_ON(PageLRU(page));
1231 list_del(&page->lru);
Hugh Dickins39b5f292012-10-08 16:33:18 -07001232 if (unlikely(!page_evictable(page))) {
Mel Gorman66635622010-08-09 17:19:30 -07001233 spin_unlock_irq(&zone->lru_lock);
1234 putback_lru_page(page);
1235 spin_lock_irq(&zone->lru_lock);
1236 continue;
1237 }
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001238
1239 lruvec = mem_cgroup_page_lruvec(page, zone);
1240
Linus Torvalds7a608572011-01-17 14:42:19 -08001241 SetPageLRU(page);
Mel Gorman66635622010-08-09 17:19:30 -07001242 lru = page_lru(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001243 add_page_to_lru_list(page, lruvec, lru);
1244
Mel Gorman66635622010-08-09 17:19:30 -07001245 if (is_active_lru(lru)) {
1246 int file = is_file_lru(lru);
Rik van Riel9992af12011-01-13 15:47:13 -08001247 int numpages = hpage_nr_pages(page);
1248 reclaim_stat->recent_rotated[file] += numpages;
Mel Gorman66635622010-08-09 17:19:30 -07001249 }
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001250 if (put_page_testzero(page)) {
1251 __ClearPageLRU(page);
1252 __ClearPageActive(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001253 del_page_from_lru_list(page, lruvec, lru);
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001254
1255 if (unlikely(PageCompound(page))) {
1256 spin_unlock_irq(&zone->lru_lock);
1257 (*get_compound_page_dtor(page))(page);
1258 spin_lock_irq(&zone->lru_lock);
1259 } else
1260 list_add(&page->lru, &pages_to_free);
Mel Gorman66635622010-08-09 17:19:30 -07001261 }
1262 }
Mel Gorman66635622010-08-09 17:19:30 -07001263
Hugh Dickins3f797682012-01-12 17:20:07 -08001264 /*
1265 * To save our caller's stack, now use input list for pages to free.
1266 */
1267 list_splice(&pages_to_free, page_list);
Mel Gorman66635622010-08-09 17:19:30 -07001268}
1269
1270/*
Andrew Morton1742f192006-03-22 00:08:21 -08001271 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1272 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 */
Mel Gorman66635622010-08-09 17:19:30 -07001274static noinline_for_stack unsigned long
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001275shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001276 struct scan_control *sc, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277{
1278 LIST_HEAD(page_list);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001279 unsigned long nr_scanned;
Andrew Morton05ff5132006-03-22 00:08:20 -08001280 unsigned long nr_reclaimed = 0;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001281 unsigned long nr_taken;
Mel Gorman92df3a72011-10-31 17:07:56 -07001282 unsigned long nr_dirty = 0;
1283 unsigned long nr_writeback = 0;
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -07001284 isolate_mode_t isolate_mode = 0;
Konstantin Khlebnikov3cb99452012-05-29 15:06:53 -07001285 int file = is_file_lru(lru);
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001286 struct zone *zone = lruvec_zone(lruvec);
1287 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
KOSAKI Motohiro78dc5832009-06-16 15:31:40 -07001288
Rik van Riel35cd7812009-09-21 17:01:38 -07001289 while (unlikely(too_many_isolated(zone, file, sc))) {
KOSAKI Motohiro58355c72009-10-26 16:49:35 -07001290 congestion_wait(BLK_RW_ASYNC, HZ/10);
Rik van Riel35cd7812009-09-21 17:01:38 -07001291
1292 /* We are about to die and free our memory. Return now. */
1293 if (fatal_signal_pending(current))
1294 return SWAP_CLUSTER_MAX;
1295 }
1296
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 lru_add_drain();
Minchan Kimf80c0672011-10-31 17:06:55 -07001298
1299 if (!sc->may_unmap)
Hillf Danton61317282012-03-21 16:33:48 -07001300 isolate_mode |= ISOLATE_UNMAPPED;
Minchan Kimf80c0672011-10-31 17:06:55 -07001301 if (!sc->may_writepage)
Hillf Danton61317282012-03-21 16:33:48 -07001302 isolate_mode |= ISOLATE_CLEAN;
Minchan Kimf80c0672011-10-31 17:06:55 -07001303
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 spin_lock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
Konstantin Khlebnikov5dc35972012-05-29 15:06:58 -07001306 nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list,
1307 &nr_scanned, sc, isolate_mode, lru);
Konstantin Khlebnikov95d918f2012-05-29 15:06:59 -07001308
1309 __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
1310 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
1311
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001312 if (global_reclaim(sc)) {
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001313 zone->pages_scanned += nr_scanned;
KOSAKI Motohirob35ea172009-09-21 17:01:36 -07001314 if (current_is_kswapd())
Hugh Dickins75b00af2012-05-29 15:07:09 -07001315 __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001316 else
Hugh Dickins75b00af2012-05-29 15:07:09 -07001317 __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001318 }
Hillf Dantond563c052012-03-21 16:34:02 -07001319 spin_unlock_irq(&zone->lru_lock);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001320
Hillf Dantond563c052012-03-21 16:34:02 -07001321 if (nr_taken == 0)
Mel Gorman66635622010-08-09 17:19:30 -07001322 return 0;
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001323
Minchan Kim02c6de82012-10-08 16:31:55 -07001324 nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
1325 &nr_dirty, &nr_writeback, false);
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001326
Hugh Dickins3f797682012-01-12 17:20:07 -08001327 spin_lock_irq(&zone->lru_lock);
1328
Konstantin Khlebnikov95d918f2012-05-29 15:06:59 -07001329 reclaim_stat->recent_scanned[file] += nr_taken;
Hillf Dantond563c052012-03-21 16:34:02 -07001330
Ying Han904249a2012-04-25 16:01:48 -07001331 if (global_reclaim(sc)) {
1332 if (current_is_kswapd())
1333 __count_zone_vm_events(PGSTEAL_KSWAPD, zone,
1334 nr_reclaimed);
1335 else
1336 __count_zone_vm_events(PGSTEAL_DIRECT, zone,
1337 nr_reclaimed);
1338 }
KOSAKI Motohiroe247dbc2010-08-09 17:19:28 -07001339
Konstantin Khlebnikov27ac81d2012-05-29 15:07:00 -07001340 putback_inactive_pages(lruvec, &page_list);
Hugh Dickins3f797682012-01-12 17:20:07 -08001341
Konstantin Khlebnikov95d918f2012-05-29 15:06:59 -07001342 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
Hugh Dickins3f797682012-01-12 17:20:07 -08001343
1344 spin_unlock_irq(&zone->lru_lock);
1345
1346 free_hot_cold_page_list(&page_list, 1);
Mel Gormane11da5b2010-10-26 14:21:40 -07001347
Mel Gorman92df3a72011-10-31 17:07:56 -07001348 /*
1349 * If reclaim is isolating dirty pages under writeback, it implies
1350 * that the long-lived page allocation rate is exceeding the page
1351 * laundering rate. Either the global limits are not being effective
1352 * at throttling processes due to the page distribution throughout
1353 * zones or there is heavy usage of a slow backing device. The
1354 * only option is to throttle from reclaim context which is not ideal
1355 * as there is no guarantee the dirtying process is throttled in the
1356 * same way balance_dirty_pages() manages.
1357 *
1358 * This scales the number of dirty pages that must be under writeback
1359 * before throttling depending on priority. It is a simple backoff
1360 * function that has the most effect in the range DEF_PRIORITY to
1361 * DEF_PRIORITY-2 which is the priority reclaim is considered to be
1362 * in trouble and reclaim is considered to be in trouble.
1363 *
1364 * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
1365 * DEF_PRIORITY-1 50% must be PageWriteback
1366 * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
1367 * ...
1368 * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
1369 * isolated page is PageWriteback
1370 */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001371 if (nr_writeback && nr_writeback >=
1372 (nr_taken >> (DEF_PRIORITY - sc->priority)))
Mel Gorman92df3a72011-10-31 17:07:56 -07001373 wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
1374
Mel Gormane11da5b2010-10-26 14:21:40 -07001375 trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
1376 zone_idx(zone),
1377 nr_scanned, nr_reclaimed,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001378 sc->priority,
Mel Gorman23b9da52012-05-29 15:06:20 -07001379 trace_shrink_flags(file));
Andrew Morton05ff5132006-03-22 00:08:20 -08001380 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381}
1382
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001383/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 * This moves pages from the active list to the inactive list.
1385 *
1386 * We move them the other way if the page is referenced by one or more
1387 * processes, from rmap.
1388 *
1389 * If the pages are mostly unmapped, the processing is fast and it is
1390 * appropriate to hold zone->lru_lock across the whole operation. But if
1391 * the pages are mapped, the processing is slow (page_referenced()) so we
1392 * should drop zone->lru_lock around each page. It's impossible to balance
1393 * this, so instead we remove the pages from the LRU while processing them.
1394 * It is safe to rely on PG_active against the non-LRU pages in here because
1395 * nobody will play with that bit on a non-LRU page.
1396 *
1397 * The downside is that we have to touch page->_count against each page.
1398 * But we had to alter page->flags anyway.
1399 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001400
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001401static void move_active_pages_to_lru(struct lruvec *lruvec,
Wu Fengguang3eb41402009-06-16 15:33:13 -07001402 struct list_head *list,
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001403 struct list_head *pages_to_free,
Wu Fengguang3eb41402009-06-16 15:33:13 -07001404 enum lru_list lru)
1405{
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001406 struct zone *zone = lruvec_zone(lruvec);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001407 unsigned long pgmoved = 0;
Wu Fengguang3eb41402009-06-16 15:33:13 -07001408 struct page *page;
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001409 int nr_pages;
Wu Fengguang3eb41402009-06-16 15:33:13 -07001410
Wu Fengguang3eb41402009-06-16 15:33:13 -07001411 while (!list_empty(list)) {
1412 page = lru_to_page(list);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001413 lruvec = mem_cgroup_page_lruvec(page, zone);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001414
1415 VM_BUG_ON(PageLRU(page));
1416 SetPageLRU(page);
1417
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001418 nr_pages = hpage_nr_pages(page);
1419 mem_cgroup_update_lru_size(lruvec, lru, nr_pages);
Johannes Weiner925b7672012-01-12 17:18:15 -08001420 list_move(&page->lru, &lruvec->lists[lru]);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001421 pgmoved += nr_pages;
Wu Fengguang3eb41402009-06-16 15:33:13 -07001422
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001423 if (put_page_testzero(page)) {
1424 __ClearPageLRU(page);
1425 __ClearPageActive(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001426 del_page_from_lru_list(page, lruvec, lru);
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001427
1428 if (unlikely(PageCompound(page))) {
1429 spin_unlock_irq(&zone->lru_lock);
1430 (*get_compound_page_dtor(page))(page);
1431 spin_lock_irq(&zone->lru_lock);
1432 } else
1433 list_add(&page->lru, pages_to_free);
Wu Fengguang3eb41402009-06-16 15:33:13 -07001434 }
1435 }
1436 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
1437 if (!is_active_lru(lru))
1438 __count_vm_events(PGDEACTIVATE, pgmoved);
1439}
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001440
Hugh Dickinsf6260122012-01-12 17:20:06 -08001441static void shrink_active_list(unsigned long nr_to_scan,
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001442 struct lruvec *lruvec,
Johannes Weinerf16015f2012-01-12 17:17:52 -08001443 struct scan_control *sc,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001444 enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445{
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001446 unsigned long nr_taken;
Hugh Dickinsf6260122012-01-12 17:20:06 -08001447 unsigned long nr_scanned;
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -07001448 unsigned long vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 LIST_HEAD(l_hold); /* The pages which were snipped off */
Wu Fengguang8cab4752009-06-16 15:33:12 -07001450 LIST_HEAD(l_active);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001451 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 struct page *page;
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001453 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
KOSAKI Motohiro44c241f2009-09-21 17:01:35 -07001454 unsigned long nr_rotated = 0;
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -07001455 isolate_mode_t isolate_mode = 0;
Konstantin Khlebnikov3cb99452012-05-29 15:06:53 -07001456 int file = is_file_lru(lru);
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001457 struct zone *zone = lruvec_zone(lruvec);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458
1459 lru_add_drain();
Minchan Kimf80c0672011-10-31 17:06:55 -07001460
1461 if (!sc->may_unmap)
Hillf Danton61317282012-03-21 16:33:48 -07001462 isolate_mode |= ISOLATE_UNMAPPED;
Minchan Kimf80c0672011-10-31 17:06:55 -07001463 if (!sc->may_writepage)
Hillf Danton61317282012-03-21 16:33:48 -07001464 isolate_mode |= ISOLATE_CLEAN;
Minchan Kimf80c0672011-10-31 17:06:55 -07001465
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 spin_lock_irq(&zone->lru_lock);
Johannes Weiner925b7672012-01-12 17:18:15 -08001467
Konstantin Khlebnikov5dc35972012-05-29 15:06:58 -07001468 nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
1469 &nr_scanned, sc, isolate_mode, lru);
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001470 if (global_reclaim(sc))
Hugh Dickinsf6260122012-01-12 17:20:06 -08001471 zone->pages_scanned += nr_scanned;
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001472
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001473 reclaim_stat->recent_scanned[file] += nr_taken;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001474
Hugh Dickinsf6260122012-01-12 17:20:06 -08001475 __count_zone_vm_events(PGREFILL, zone, nr_scanned);
Konstantin Khlebnikov3cb99452012-05-29 15:06:53 -07001476 __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001477 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 spin_unlock_irq(&zone->lru_lock);
1479
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480 while (!list_empty(&l_hold)) {
1481 cond_resched();
1482 page = lru_to_page(&l_hold);
1483 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001484
Hugh Dickins39b5f292012-10-08 16:33:18 -07001485 if (unlikely(!page_evictable(page))) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001486 putback_lru_page(page);
1487 continue;
1488 }
1489
Mel Gormancc715d92012-03-21 16:34:00 -07001490 if (unlikely(buffer_heads_over_limit)) {
1491 if (page_has_private(page) && trylock_page(page)) {
1492 if (page_has_private(page))
1493 try_to_release_page(page, 0);
1494 unlock_page(page);
1495 }
1496 }
1497
Johannes Weinerc3ac9a82012-05-29 15:06:25 -07001498 if (page_referenced(page, 0, sc->target_mem_cgroup,
1499 &vm_flags)) {
Rik van Riel9992af12011-01-13 15:47:13 -08001500 nr_rotated += hpage_nr_pages(page);
Wu Fengguang8cab4752009-06-16 15:33:12 -07001501 /*
1502 * Identify referenced, file-backed active pages and
1503 * give them one more trip around the active list. So
1504 * that executable code get better chances to stay in
1505 * memory under moderate memory pressure. Anon pages
1506 * are not likely to be evicted by use-once streaming
1507 * IO, plus JVM can create lots of anon VM_EXEC pages,
1508 * so we ignore them here.
1509 */
Wu Fengguang41e20982009-10-26 16:49:53 -07001510 if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
Wu Fengguang8cab4752009-06-16 15:33:12 -07001511 list_add(&page->lru, &l_active);
1512 continue;
1513 }
1514 }
Rik van Riel7e9cd482008-10-18 20:26:35 -07001515
KOSAKI Motohiro5205e562009-09-21 17:01:44 -07001516 ClearPageActive(page); /* we are de-activating */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 list_add(&page->lru, &l_inactive);
1518 }
1519
Andrew Mortonb5557492009-01-06 14:40:13 -08001520 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001521 * Move pages back to the lru list.
Andrew Mortonb5557492009-01-06 14:40:13 -08001522 */
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001523 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001524 /*
Wu Fengguang8cab4752009-06-16 15:33:12 -07001525 * Count referenced pages from currently used mappings as rotated,
1526 * even though only some of them are actually re-activated. This
1527 * helps balance scan pressure between file and anonymous pages in
1528 * get_scan_ratio.
Rik van Riel7e9cd482008-10-18 20:26:35 -07001529 */
Johannes Weinerb7c46d12009-09-21 17:02:56 -07001530 reclaim_stat->recent_rotated[file] += nr_rotated;
Rik van Riel556adec2008-10-18 20:26:34 -07001531
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001532 move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
1533 move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
KOSAKI Motohiroa7312862009-09-21 17:01:37 -07001534 __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001535 spin_unlock_irq(&zone->lru_lock);
Hugh Dickins2bcf8872012-01-12 17:19:56 -08001536
1537 free_hot_cold_page_list(&l_hold, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538}
1539
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001540#ifdef CONFIG_SWAP
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001541static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001542{
1543 unsigned long active, inactive;
1544
1545 active = zone_page_state(zone, NR_ACTIVE_ANON);
1546 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1547
1548 if (inactive * zone->inactive_ratio < active)
1549 return 1;
1550
1551 return 0;
1552}
1553
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001554/**
1555 * inactive_anon_is_low - check if anonymous pages need to be deactivated
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001556 * @lruvec: LRU vector to check
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001557 *
1558 * Returns true if the zone does not have enough inactive anon pages,
1559 * meaning some active anon pages need to be deactivated.
1560 */
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001561static int inactive_anon_is_low(struct lruvec *lruvec)
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001562{
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001563 /*
1564 * If we don't have swap space, anonymous page deactivation
1565 * is pointless.
1566 */
1567 if (!total_swap_pages)
1568 return 0;
1569
Hugh Dickinsc3c787e2012-05-29 15:06:52 -07001570 if (!mem_cgroup_disabled())
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001571 return mem_cgroup_inactive_anon_is_low(lruvec);
Johannes Weinerf16015f2012-01-12 17:17:52 -08001572
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001573 return inactive_anon_is_low_global(lruvec_zone(lruvec));
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001574}
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001575#else
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001576static inline int inactive_anon_is_low(struct lruvec *lruvec)
Minchan Kim74e3f3c2010-10-26 14:21:31 -07001577{
1578 return 0;
1579}
1580#endif
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001581
Rik van Riel56e49d22009-06-16 15:32:28 -07001582static int inactive_file_is_low_global(struct zone *zone)
1583{
1584 unsigned long active, inactive;
1585
1586 active = zone_page_state(zone, NR_ACTIVE_FILE);
1587 inactive = zone_page_state(zone, NR_INACTIVE_FILE);
1588
1589 return (active > inactive);
1590}
1591
1592/**
1593 * inactive_file_is_low - check if file pages need to be deactivated
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001594 * @lruvec: LRU vector to check
Rik van Riel56e49d22009-06-16 15:32:28 -07001595 *
1596 * When the system is doing streaming IO, memory pressure here
1597 * ensures that active file pages get deactivated, until more
1598 * than half of the file pages are on the inactive list.
1599 *
1600 * Once we get to that situation, protect the system's working
1601 * set from being evicted by disabling active file page aging.
1602 *
1603 * This uses a different ratio than the anonymous pages, because
1604 * the page cache uses a use-once replacement algorithm.
1605 */
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001606static int inactive_file_is_low(struct lruvec *lruvec)
Rik van Riel56e49d22009-06-16 15:32:28 -07001607{
Hugh Dickinsc3c787e2012-05-29 15:06:52 -07001608 if (!mem_cgroup_disabled())
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001609 return mem_cgroup_inactive_file_is_low(lruvec);
Rik van Riel56e49d22009-06-16 15:32:28 -07001610
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001611 return inactive_file_is_low_global(lruvec_zone(lruvec));
Rik van Riel56e49d22009-06-16 15:32:28 -07001612}
1613
Hugh Dickins75b00af2012-05-29 15:07:09 -07001614static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
Rik van Rielb39415b2009-12-14 17:59:48 -08001615{
Hugh Dickins75b00af2012-05-29 15:07:09 -07001616 if (is_file_lru(lru))
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001617 return inactive_file_is_low(lruvec);
Rik van Rielb39415b2009-12-14 17:59:48 -08001618 else
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07001619 return inactive_anon_is_low(lruvec);
Rik van Rielb39415b2009-12-14 17:59:48 -08001620}
1621
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001622static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001623 struct lruvec *lruvec, struct scan_control *sc)
Christoph Lameterb69408e2008-10-18 20:26:14 -07001624{
Rik van Rielb39415b2009-12-14 17:59:48 -08001625 if (is_active_lru(lru)) {
Hugh Dickins75b00af2012-05-29 15:07:09 -07001626 if (inactive_list_is_low(lruvec, lru))
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001627 shrink_active_list(nr_to_scan, lruvec, sc, lru);
Rik van Riel556adec2008-10-18 20:26:34 -07001628 return 0;
1629 }
1630
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07001631 return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001632}
1633
Konstantin Khlebnikov3d58ab52012-05-29 15:06:57 -07001634static int vmscan_swappiness(struct scan_control *sc)
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001635{
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001636 if (global_reclaim(sc))
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001637 return vm_swappiness;
Konstantin Khlebnikov3d58ab52012-05-29 15:06:57 -07001638 return mem_cgroup_swappiness(sc->target_mem_cgroup);
KAMEZAWA Hiroyuki1f4c0252011-07-26 16:08:21 -07001639}
1640
Johannes Weiner9a265112013-02-22 16:32:17 -08001641enum scan_balance {
1642 SCAN_EQUAL,
1643 SCAN_FRACT,
1644 SCAN_ANON,
1645 SCAN_FILE,
1646};
1647
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001649 * Determine how aggressively the anon and file LRU lists should be
1650 * scanned. The relative value of each set of LRU lists is determined
1651 * by looking at the fraction of the pages scanned we did rotate back
1652 * onto the active list instead of evict.
1653 *
Wanpeng Libe7bd592012-06-14 20:41:02 +08001654 * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
1655 * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001656 */
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001657static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001658 unsigned long *nr)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001659{
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001660 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
Johannes Weiner9a265112013-02-22 16:32:17 -08001661 u64 fraction[2];
1662 u64 denominator = 0; /* gcc */
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001663 struct zone *zone = lruvec_zone(lruvec);
Johannes Weiner9a265112013-02-22 16:32:17 -08001664 unsigned long anon_prio, file_prio;
1665 enum scan_balance scan_balance;
1666 unsigned long anon, file, free;
1667 bool force_scan = false;
1668 unsigned long ap, fp;
1669 enum lru_list lru;
KAMEZAWA Hiroyuki246e87a2011-05-26 16:25:34 -07001670
Johannes Weinerf11c0ca2011-10-31 17:07:27 -07001671 /*
1672 * If the zone or memcg is small, nr[l] can be 0. This
1673 * results in no scanning on this priority and a potential
1674 * priority drop. Global direct reclaim can go to the next
1675 * zone and tends to have no problems. Global kswapd is for
1676 * zone balancing and it needs to scan a minimum amount. When
1677 * reclaiming for a memcg, a priority drop can cause high
1678 * latencies, so it's better to scan a minimum amount there as
1679 * well.
1680 */
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001681 if (current_is_kswapd() && zone->all_unreclaimable)
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001682 force_scan = true;
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001683 if (!global_reclaim(sc))
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001684 force_scan = true;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001685
1686 /* If we have no swap space, do not bother scanning anon pages. */
1687 if (!sc->may_swap || (nr_swap_pages <= 0)) {
Johannes Weiner9a265112013-02-22 16:32:17 -08001688 scan_balance = SCAN_FILE;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001689 goto out;
1690 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001691
Johannes Weiner10316b32013-02-22 16:32:14 -08001692 /*
1693 * Global reclaim will swap to prevent OOM even with no
1694 * swappiness, but memcg users want to use this knob to
1695 * disable swapping for individual groups completely when
1696 * using the memory controller's swap limit feature would be
1697 * too expensive.
1698 */
1699 if (!global_reclaim(sc) && !vmscan_swappiness(sc)) {
Johannes Weiner9a265112013-02-22 16:32:17 -08001700 scan_balance = SCAN_FILE;
Johannes Weiner10316b32013-02-22 16:32:14 -08001701 goto out;
1702 }
1703
1704 /*
1705 * Do not apply any pressure balancing cleverness when the
1706 * system is close to OOM, scan both anon and file equally
1707 * (unless the swappiness setting disagrees with swapping).
1708 */
1709 if (!sc->priority && vmscan_swappiness(sc)) {
Johannes Weiner9a265112013-02-22 16:32:17 -08001710 scan_balance = SCAN_EQUAL;
Johannes Weiner10316b32013-02-22 16:32:14 -08001711 goto out;
1712 }
1713
Hugh Dickins4d7dcca2012-05-29 15:07:08 -07001714 anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
1715 get_lru_size(lruvec, LRU_INACTIVE_ANON);
1716 file = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
1717 get_lru_size(lruvec, LRU_INACTIVE_FILE);
Johannes Weinera4d3e9e2011-09-14 16:21:52 -07001718
Johannes Weiner11d16c22013-02-22 16:32:15 -08001719 /*
1720 * If it's foreseeable that reclaiming the file cache won't be
1721 * enough to get the zone back into a desirable shape, we have
1722 * to swap. Better start now and leave the - probably heavily
1723 * thrashing - remaining file pages alone.
1724 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08001725 if (global_reclaim(sc)) {
Johannes Weiner11d16c22013-02-22 16:32:15 -08001726 free = zone_page_state(zone, NR_FREE_PAGES);
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001727 if (unlikely(file + free <= high_wmark_pages(zone))) {
Johannes Weiner9a265112013-02-22 16:32:17 -08001728 scan_balance = SCAN_ANON;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001729 goto out;
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001730 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001731 }
1732
1733 /*
Johannes Weiner7c5bd702013-02-22 16:32:10 -08001734 * There is enough inactive page cache, do not reclaim
1735 * anything from the anonymous working set right now.
1736 */
1737 if (!inactive_file_is_low(lruvec)) {
Johannes Weiner9a265112013-02-22 16:32:17 -08001738 scan_balance = SCAN_FILE;
Johannes Weiner7c5bd702013-02-22 16:32:10 -08001739 goto out;
1740 }
1741
Johannes Weiner9a265112013-02-22 16:32:17 -08001742 scan_balance = SCAN_FRACT;
1743
Johannes Weiner7c5bd702013-02-22 16:32:10 -08001744 /*
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001745 * With swappiness at 100, anonymous and file have the same priority.
1746 * This scanning priority is essentially the inverse of IO cost.
1747 */
Konstantin Khlebnikov3d58ab52012-05-29 15:06:57 -07001748 anon_prio = vmscan_swappiness(sc);
Hugh Dickins75b00af2012-05-29 15:07:09 -07001749 file_prio = 200 - anon_prio;
KOSAKI Motohiro58c37f62010-08-09 17:19:51 -07001750
1751 /*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001752 * OK, so we have swap space and a fair amount of page cache
1753 * pages. We use the recently rotated / recently scanned
1754 * ratios to determine how valuable each cache is.
1755 *
1756 * Because workloads change over time (and to avoid overflow)
1757 * we keep these statistics as a floating average, which ends
1758 * up weighing recent references more than old ones.
1759 *
1760 * anon in [0], file in [1]
1761 */
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001762 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001763 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001764 reclaim_stat->recent_scanned[0] /= 2;
1765 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001766 }
1767
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001768 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001769 reclaim_stat->recent_scanned[1] /= 2;
1770 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001771 }
1772
1773 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001774 * The amount of pressure on anon vs file pages is inversely
1775 * proportional to the fraction of recently scanned pages on
1776 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001777 */
Satoru Moriyafe350042012-05-29 15:06:47 -07001778 ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001779 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001780
Satoru Moriyafe350042012-05-29 15:06:47 -07001781 fp = file_prio * (reclaim_stat->recent_scanned[1] + 1);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001782 fp /= reclaim_stat->recent_rotated[1] + 1;
Konstantin Khlebnikov90126372012-05-29 15:07:01 -07001783 spin_unlock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001784
Shaohua Li76a33fc2010-05-24 14:32:36 -07001785 fraction[0] = ap;
1786 fraction[1] = fp;
1787 denominator = ap + fp + 1;
1788out:
Hugh Dickins41113042012-01-12 17:20:01 -08001789 for_each_evictable_lru(lru) {
1790 int file = is_file_lru(lru);
Johannes Weinerd778df52013-02-22 16:32:12 -08001791 unsigned long size;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001792 unsigned long scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001793
Johannes Weinerd778df52013-02-22 16:32:12 -08001794 size = get_lru_size(lruvec, lru);
Johannes Weiner10316b32013-02-22 16:32:14 -08001795 scan = size >> sc->priority;
Johannes Weiner9a265112013-02-22 16:32:17 -08001796
Johannes Weiner10316b32013-02-22 16:32:14 -08001797 if (!scan && force_scan)
1798 scan = min(size, SWAP_CLUSTER_MAX);
Johannes Weiner9a265112013-02-22 16:32:17 -08001799
1800 switch (scan_balance) {
1801 case SCAN_EQUAL:
1802 /* Scan lists relative to size */
1803 break;
1804 case SCAN_FRACT:
1805 /*
1806 * Scan types proportional to swappiness and
1807 * their relative recent reclaim efficiency.
1808 */
1809 scan = div64_u64(scan * fraction[file], denominator);
1810 break;
1811 case SCAN_FILE:
1812 case SCAN_ANON:
1813 /* Scan one type exclusively */
1814 if ((scan_balance == SCAN_FILE) != file)
1815 scan = 0;
1816 break;
1817 default:
1818 /* Look ma, no brain */
1819 BUG();
1820 }
Hugh Dickins41113042012-01-12 17:20:01 -08001821 nr[lru] = scan;
Shaohua Li76a33fc2010-05-24 14:32:36 -07001822 }
Wu Fengguang6e08a362009-06-16 15:32:29 -07001823}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001824
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001825/*
1826 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1827 */
1828static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
1829{
1830 unsigned long nr[NR_LRU_LISTS];
1831 unsigned long nr_to_scan;
1832 enum lru_list lru;
1833 unsigned long nr_reclaimed = 0;
1834 unsigned long nr_to_reclaim = sc->nr_to_reclaim;
1835 struct blk_plug plug;
1836
1837 get_scan_count(lruvec, sc, nr);
1838
1839 blk_start_plug(&plug);
1840 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1841 nr[LRU_INACTIVE_FILE]) {
1842 for_each_evictable_lru(lru) {
1843 if (nr[lru]) {
1844 nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
1845 nr[lru] -= nr_to_scan;
1846
1847 nr_reclaimed += shrink_list(lru, nr_to_scan,
1848 lruvec, sc);
1849 }
1850 }
1851 /*
1852 * On large memory systems, scan >> priority can become
1853 * really large. This is fine for the starting priority;
1854 * we want to put equal scanning pressure on each zone.
1855 * However, if the VM has a harder time of freeing pages,
1856 * with multiple processes reclaiming pages, the total
1857 * freeing target can get unreasonably large.
1858 */
1859 if (nr_reclaimed >= nr_to_reclaim &&
1860 sc->priority < DEF_PRIORITY)
1861 break;
1862 }
1863 blk_finish_plug(&plug);
1864 sc->nr_reclaimed += nr_reclaimed;
1865
1866 /*
1867 * Even if we did not try to evict anon pages at all, we want to
1868 * rebalance the anon lru active/inactive ratio.
1869 */
1870 if (inactive_anon_is_low(lruvec))
1871 shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
1872 sc, LRU_ACTIVE_ANON);
1873
1874 throttle_vm_writeout(sc->gfp_mask);
1875}
1876
Mel Gorman23b9da52012-05-29 15:06:20 -07001877/* Use reclaim/compaction for costly allocs or under memory pressure */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001878static bool in_reclaim_compaction(struct scan_control *sc)
Mel Gorman23b9da52012-05-29 15:06:20 -07001879{
Kirill A. Shutemovd84da3f2012-12-11 16:00:31 -08001880 if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
Mel Gorman23b9da52012-05-29 15:06:20 -07001881 (sc->order > PAGE_ALLOC_COSTLY_ORDER ||
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001882 sc->priority < DEF_PRIORITY - 2))
Mel Gorman23b9da52012-05-29 15:06:20 -07001883 return true;
1884
1885 return false;
1886}
1887
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001888/*
Mel Gorman23b9da52012-05-29 15:06:20 -07001889 * Reclaim/compaction is used for high-order allocation requests. It reclaims
1890 * order-0 pages before compacting the zone. should_continue_reclaim() returns
1891 * true if more pages should be reclaimed such that when the page allocator
1892 * calls try_to_compact_zone() that it will have enough free pages to succeed.
1893 * It will give up earlier than that if there is difficulty reclaiming pages.
Mel Gorman3e7d3442011-01-13 15:45:56 -08001894 */
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001895static inline bool should_continue_reclaim(struct zone *zone,
Mel Gorman3e7d3442011-01-13 15:45:56 -08001896 unsigned long nr_reclaimed,
1897 unsigned long nr_scanned,
1898 struct scan_control *sc)
1899{
1900 unsigned long pages_for_compaction;
1901 unsigned long inactive_lru_pages;
1902
1903 /* If not in reclaim/compaction mode, stop */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001904 if (!in_reclaim_compaction(sc))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001905 return false;
1906
Mel Gorman28765922011-02-25 14:44:20 -08001907 /* Consider stopping depending on scan and reclaim activity */
1908 if (sc->gfp_mask & __GFP_REPEAT) {
1909 /*
1910 * For __GFP_REPEAT allocations, stop reclaiming if the
1911 * full LRU list has been scanned and we are still failing
1912 * to reclaim pages. This full LRU scan is potentially
1913 * expensive but a __GFP_REPEAT caller really wants to succeed
1914 */
1915 if (!nr_reclaimed && !nr_scanned)
1916 return false;
1917 } else {
1918 /*
1919 * For non-__GFP_REPEAT allocations which can presumably
1920 * fail without consequence, stop if we failed to reclaim
1921 * any pages from the last SWAP_CLUSTER_MAX number of
1922 * pages that were scanned. This will return to the
1923 * caller faster at the risk reclaim/compaction and
1924 * the resulting allocation attempt fails
1925 */
1926 if (!nr_reclaimed)
1927 return false;
1928 }
Mel Gorman3e7d3442011-01-13 15:45:56 -08001929
1930 /*
1931 * If we have not reclaimed enough pages for compaction and the
1932 * inactive lists are large enough, continue reclaiming
1933 */
1934 pages_for_compaction = (2UL << sc->order);
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001935 inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE);
Minchan Kim86cfd3a2012-01-10 15:08:18 -08001936 if (nr_swap_pages > 0)
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001937 inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001938 if (sc->nr_reclaimed < pages_for_compaction &&
1939 inactive_lru_pages > pages_for_compaction)
1940 return true;
1941
1942 /* If compaction would go ahead or the allocation would succeed, stop */
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001943 switch (compaction_suitable(zone, sc->order)) {
Mel Gorman3e7d3442011-01-13 15:45:56 -08001944 case COMPACT_PARTIAL:
1945 case COMPACT_CONTINUE:
1946 return false;
1947 default:
1948 return true;
1949 }
1950}
1951
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07001952static void shrink_zone(struct zone *zone, struct scan_control *sc)
Johannes Weinerf16015f2012-01-12 17:17:52 -08001953{
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001954 unsigned long nr_reclaimed, nr_scanned;
Johannes Weinerf16015f2012-01-12 17:17:52 -08001955
Johannes Weiner56600482012-01-12 17:17:59 -08001956 do {
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001957 struct mem_cgroup *root = sc->target_mem_cgroup;
1958 struct mem_cgroup_reclaim_cookie reclaim = {
1959 .zone = zone,
1960 .priority = sc->priority,
1961 };
1962 struct mem_cgroup *memcg;
Johannes Weiner56600482012-01-12 17:17:59 -08001963
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001964 nr_reclaimed = sc->nr_reclaimed;
1965 nr_scanned = sc->nr_scanned;
Konstantin Khlebnikovf9be23d2012-05-29 15:07:02 -07001966
Johannes Weiner9b4f98c2013-02-22 16:32:19 -08001967 memcg = mem_cgroup_iter(root, NULL, &reclaim);
1968 do {
1969 struct lruvec *lruvec;
1970
1971 lruvec = mem_cgroup_zone_lruvec(zone, memcg);
1972
1973 shrink_lruvec(lruvec, sc);
1974
1975 /*
1976 * Limit reclaim has historically picked one
1977 * memcg and scanned it with decreasing
1978 * priority levels until nr_to_reclaim had
1979 * been reclaimed. This priority cycle is
1980 * thus over after a single memcg.
1981 *
1982 * Direct reclaim and kswapd, on the other
1983 * hand, have to scan all memory cgroups to
1984 * fulfill the overall scan target for the
1985 * zone.
1986 */
1987 if (!global_reclaim(sc)) {
1988 mem_cgroup_iter_break(root, memcg);
1989 break;
1990 }
1991 memcg = mem_cgroup_iter(root, memcg, &reclaim);
1992 } while (memcg);
1993 } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
1994 sc->nr_scanned - nr_scanned, sc));
Johannes Weinerf16015f2012-01-12 17:17:52 -08001995}
1996
Mel Gormanfe4b1b22012-01-12 17:19:45 -08001997/* Returns true if compaction should go ahead for a high-order request */
1998static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
1999{
2000 unsigned long balance_gap, watermark;
2001 bool watermark_ok;
2002
2003 /* Do not consider compaction for orders reclaim is meant to satisfy */
2004 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER)
2005 return false;
2006
2007 /*
2008 * Compaction takes time to run and there are potentially other
2009 * callers using the pages just freed. Continue reclaiming until
2010 * there is a buffer of free pages available to give compaction
2011 * a reasonable chance of completing and allocating the page
2012 */
2013 balance_gap = min(low_wmark_pages(zone),
2014 (zone->present_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
2015 KSWAPD_ZONE_BALANCE_GAP_RATIO);
2016 watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order);
2017 watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0);
2018
2019 /*
2020 * If compaction is deferred, reclaim up to a point where
2021 * compaction will have a chance of success when re-enabled
2022 */
Rik van Rielaff62242012-03-21 16:33:52 -07002023 if (compaction_deferred(zone, sc->order))
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002024 return watermark_ok;
2025
2026 /* If compaction is not ready to start, keep reclaiming */
2027 if (!compaction_suitable(zone, sc->order))
2028 return false;
2029
2030 return watermark_ok;
2031}
2032
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033/*
2034 * This is the direct reclaim path, for page-allocating processes. We only
2035 * try to reclaim pages from zones which will satisfy the caller's allocation
2036 * request.
2037 *
Mel Gorman41858962009-06-16 15:32:12 -07002038 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
2039 * Because:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
2041 * allocation or
Mel Gorman41858962009-06-16 15:32:12 -07002042 * b) The target zone may be at high_wmark_pages(zone) but the lower zones
2043 * must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
2044 * zone defense algorithm.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002046 * If a zone is deemed to be full of pinned pages then just give it a light
2047 * scan then give up on it.
Mel Gormane0c23272011-10-31 17:09:33 -07002048 *
2049 * This function returns true if a zone is being reclaimed for a costly
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002050 * high-order allocation and compaction is ready to begin. This indicates to
Mel Gorman0cee34f2012-01-12 17:19:49 -08002051 * the caller that it should consider retrying the allocation instead of
2052 * further reclaim.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002054static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055{
Mel Gormandd1a2392008-04-28 02:12:17 -07002056 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002057 struct zone *zone;
Ying Hand149e3b2011-05-26 16:25:27 -07002058 unsigned long nr_soft_reclaimed;
2059 unsigned long nr_soft_scanned;
Mel Gorman0cee34f2012-01-12 17:19:49 -08002060 bool aborted_reclaim = false;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002061
Mel Gormancc715d92012-03-21 16:34:00 -07002062 /*
2063 * If the number of buffer_heads in the machine exceeds the maximum
2064 * allowed level, force direct reclaim to scan the highmem zone as
2065 * highmem pages could be pinning lowmem pages storing buffer_heads
2066 */
2067 if (buffer_heads_over_limit)
2068 sc->gfp_mask |= __GFP_HIGHMEM;
2069
Mel Gormand4debc62010-08-09 17:19:29 -07002070 for_each_zone_zonelist_nodemask(zone, z, zonelist,
2071 gfp_zone(sc->gfp_mask), sc->nodemask) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08002072 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002074 /*
2075 * Take care memory controller reclaiming has small influence
2076 * to global LRU.
2077 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002078 if (global_reclaim(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002079 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2080 continue;
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002081 if (zone->all_unreclaimable &&
2082 sc->priority != DEF_PRIORITY)
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002083 continue; /* Let kswapd poll it */
Kirill A. Shutemovd84da3f2012-12-11 16:00:31 -08002084 if (IS_ENABLED(CONFIG_COMPACTION)) {
Rik van Riele0887c12011-10-31 17:09:31 -07002085 /*
Mel Gormane0c23272011-10-31 17:09:33 -07002086 * If we already have plenty of memory free for
2087 * compaction in this zone, don't free any more.
2088 * Even though compaction is invoked for any
2089 * non-zero order, only frequent costly order
2090 * reclamation is disruptive enough to become a
Copot Alexandruc7cfa372012-03-21 16:34:10 -07002091 * noticeable problem, like transparent huge
2092 * page allocations.
Rik van Riele0887c12011-10-31 17:09:31 -07002093 */
Mel Gormanfe4b1b22012-01-12 17:19:45 -08002094 if (compaction_ready(zone, sc)) {
Mel Gorman0cee34f2012-01-12 17:19:49 -08002095 aborted_reclaim = true;
Rik van Riele0887c12011-10-31 17:09:31 -07002096 continue;
Mel Gormane0c23272011-10-31 17:09:33 -07002097 }
Rik van Riele0887c12011-10-31 17:09:31 -07002098 }
KAMEZAWA Hiroyukiac34a1a2011-06-27 16:18:12 -07002099 /*
2100 * This steals pages from memory cgroups over softlimit
2101 * and returns the number of reclaimed pages and
2102 * scanned pages. This works for global memory pressure
2103 * and balancing, not for a memcg's limit.
2104 */
2105 nr_soft_scanned = 0;
2106 nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
2107 sc->order, sc->gfp_mask,
2108 &nr_soft_scanned);
2109 sc->nr_reclaimed += nr_soft_reclaimed;
2110 sc->nr_scanned += nr_soft_scanned;
2111 /* need some check for avoid more shrink_zone() */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002112 }
Nick Piggin408d8542006-09-25 23:31:27 -07002113
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002114 shrink_zone(zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 }
Mel Gormane0c23272011-10-31 17:09:33 -07002116
Mel Gorman0cee34f2012-01-12 17:19:49 -08002117 return aborted_reclaim;
Minchan Kimd1908362010-09-22 13:05:01 -07002118}
2119
2120static bool zone_reclaimable(struct zone *zone)
2121{
2122 return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
2123}
2124
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002125/* All zones in zonelist are unreclaimable? */
Minchan Kimd1908362010-09-22 13:05:01 -07002126static bool all_unreclaimable(struct zonelist *zonelist,
2127 struct scan_control *sc)
2128{
2129 struct zoneref *z;
2130 struct zone *zone;
Minchan Kimd1908362010-09-22 13:05:01 -07002131
2132 for_each_zone_zonelist_nodemask(zone, z, zonelist,
2133 gfp_zone(sc->gfp_mask), sc->nodemask) {
2134 if (!populated_zone(zone))
2135 continue;
2136 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2137 continue;
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002138 if (!zone->all_unreclaimable)
2139 return false;
Minchan Kimd1908362010-09-22 13:05:01 -07002140 }
2141
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002142 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002144
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145/*
2146 * This is the main entry point to direct page reclaim.
2147 *
2148 * If a full scan of the inactive list fails to free enough memory then we
2149 * are "out of memory" and something needs to be killed.
2150 *
2151 * If the caller is !__GFP_FS then the probability of a failure is reasonably
2152 * high - the zone may be full of dirty or under-writeback pages, which this
Jens Axboe5b0830c2009-09-23 19:37:09 +02002153 * caller can't do much about. We kick the writeback threads and take explicit
2154 * naps in the hope that some of these pages can be written. But if the
2155 * allocating task holds filesystem locks which prevent writeout this might not
2156 * work, and the allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07002157 *
2158 * returns: 0, if no pages reclaimed
2159 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 */
Mel Gormandac1d272008-04-28 02:12:12 -07002161static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Ying Hana09ed5e2011-05-24 17:12:26 -07002162 struct scan_control *sc,
2163 struct shrink_control *shrink)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164{
Andrew Morton69e05942006-03-22 00:08:19 -08002165 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 struct reclaim_state *reclaim_state = current->reclaim_state;
Mel Gormandd1a2392008-04-28 02:12:17 -07002167 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07002168 struct zone *zone;
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002169 unsigned long writeback_threshold;
Mel Gorman0cee34f2012-01-12 17:19:49 -08002170 bool aborted_reclaim;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171
Keika Kobayashi873b4772008-07-25 01:48:52 -07002172 delayacct_freepages_start();
2173
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002174 if (global_reclaim(sc))
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08002175 count_vm_event(ALLOCSTALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002177 do {
Balbir Singh66e17072008-02-07 00:13:56 -08002178 sc->nr_scanned = 0;
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002179 aborted_reclaim = shrink_zones(zonelist, sc);
Mel Gormane0c23272011-10-31 17:09:33 -07002180
Balbir Singh66e17072008-02-07 00:13:56 -08002181 /*
2182 * Don't shrink slabs when reclaiming memory from
2183 * over limit cgroups
2184 */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002185 if (global_reclaim(sc)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002186 unsigned long lru_pages = 0;
Mel Gormand4debc62010-08-09 17:19:29 -07002187 for_each_zone_zonelist(zone, z, zonelist,
2188 gfp_zone(sc->gfp_mask)) {
KOSAKI Motohiroc6a8a8c2010-08-09 17:19:14 -07002189 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
2190 continue;
2191
2192 lru_pages += zone_reclaimable_pages(zone);
2193 }
2194
Ying Han1495f232011-05-24 17:12:27 -07002195 shrink_slab(shrink, sc->nr_scanned, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002196 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08002197 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08002198 reclaim_state->reclaimed_slab = 0;
2199 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200 }
Balbir Singh66e17072008-02-07 00:13:56 -08002201 total_scanned += sc->nr_scanned;
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002202 if (sc->nr_reclaimed >= sc->nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204
2205 /*
2206 * Try to write back as many pages as we just scanned. This
2207 * tends to cause slow streaming writers to write data to the
2208 * disk smoothly, at the dirtying rate, which is nice. But
2209 * that's undesirable in laptop mode, where we *want* lumpy
2210 * writeout. So in laptop mode, write out the whole world.
2211 */
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002212 writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
2213 if (total_scanned > writeback_threshold) {
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002214 wakeup_flusher_threads(laptop_mode ? 0 : total_scanned,
2215 WB_REASON_TRY_TO_FREE_PAGES);
Balbir Singh66e17072008-02-07 00:13:56 -08002216 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217 }
2218
2219 /* Take a nap, wait for some writeback to complete */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08002220 if (!sc->hibernation_mode && sc->nr_scanned &&
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002221 sc->priority < DEF_PRIORITY - 2) {
Mel Gorman0e093d992010-10-26 14:21:45 -07002222 struct zone *preferred_zone;
2223
2224 first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
David Rientjesf33261d2011-01-25 15:07:20 -08002225 &cpuset_current_mems_allowed,
2226 &preferred_zone);
Mel Gorman0e093d992010-10-26 14:21:45 -07002227 wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
2228 }
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002229 } while (--sc->priority >= 0);
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002230
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231out:
Keika Kobayashi873b4772008-07-25 01:48:52 -07002232 delayacct_freepages_end();
2233
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002234 if (sc->nr_reclaimed)
2235 return sc->nr_reclaimed;
2236
KOSAKI Motohiro929bea72011-04-14 15:22:12 -07002237 /*
2238 * As hibernation is going on, kswapd is freezed so that it can't mark
2239 * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
2240 * check.
2241 */
2242 if (oom_killer_disabled)
2243 return 0;
2244
Mel Gorman0cee34f2012-01-12 17:19:49 -08002245 /* Aborted reclaim to try compaction? don't OOM, then */
2246 if (aborted_reclaim)
Mel Gorman73350842012-01-12 17:19:33 -08002247 return 1;
2248
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002249 /* top priority shrink_zones still had more to do? don't OOM, then */
Johannes Weiner89b5fae2012-01-12 17:17:50 -08002250 if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))
KOSAKI Motohirobb21c7c2010-06-04 14:15:05 -07002251 return 1;
2252
2253 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254}
2255
Mel Gorman55150612012-07-31 16:44:35 -07002256static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
2257{
2258 struct zone *zone;
2259 unsigned long pfmemalloc_reserve = 0;
2260 unsigned long free_pages = 0;
2261 int i;
2262 bool wmark_ok;
2263
2264 for (i = 0; i <= ZONE_NORMAL; i++) {
2265 zone = &pgdat->node_zones[i];
2266 pfmemalloc_reserve += min_wmark_pages(zone);
2267 free_pages += zone_page_state(zone, NR_FREE_PAGES);
2268 }
2269
2270 wmark_ok = free_pages > pfmemalloc_reserve / 2;
2271
2272 /* kswapd must be awake if processes are being throttled */
2273 if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) {
2274 pgdat->classzone_idx = min(pgdat->classzone_idx,
2275 (enum zone_type)ZONE_NORMAL);
2276 wake_up_interruptible(&pgdat->kswapd_wait);
2277 }
2278
2279 return wmark_ok;
2280}
2281
2282/*
2283 * Throttle direct reclaimers if backing storage is backed by the network
2284 * and the PFMEMALLOC reserve for the preferred node is getting dangerously
2285 * depleted. kswapd will continue to make progress and wake the processes
Mel Gorman50694c22012-11-26 16:29:48 -08002286 * when the low watermark is reached.
2287 *
2288 * Returns true if a fatal signal was delivered during throttling. If this
2289 * happens, the page allocator should not consider triggering the OOM killer.
Mel Gorman55150612012-07-31 16:44:35 -07002290 */
Mel Gorman50694c22012-11-26 16:29:48 -08002291static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
Mel Gorman55150612012-07-31 16:44:35 -07002292 nodemask_t *nodemask)
2293{
2294 struct zone *zone;
2295 int high_zoneidx = gfp_zone(gfp_mask);
2296 pg_data_t *pgdat;
2297
2298 /*
2299 * Kernel threads should not be throttled as they may be indirectly
2300 * responsible for cleaning pages necessary for reclaim to make forward
2301 * progress. kjournald for example may enter direct reclaim while
2302 * committing a transaction where throttling it could forcing other
2303 * processes to block on log_wait_commit().
2304 */
2305 if (current->flags & PF_KTHREAD)
Mel Gorman50694c22012-11-26 16:29:48 -08002306 goto out;
2307
2308 /*
2309 * If a fatal signal is pending, this process should not throttle.
2310 * It should return quickly so it can exit and free its memory
2311 */
2312 if (fatal_signal_pending(current))
2313 goto out;
Mel Gorman55150612012-07-31 16:44:35 -07002314
2315 /* Check if the pfmemalloc reserves are ok */
2316 first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
2317 pgdat = zone->zone_pgdat;
2318 if (pfmemalloc_watermark_ok(pgdat))
Mel Gorman50694c22012-11-26 16:29:48 -08002319 goto out;
Mel Gorman55150612012-07-31 16:44:35 -07002320
Mel Gorman68243e72012-07-31 16:44:39 -07002321 /* Account for the throttling */
2322 count_vm_event(PGSCAN_DIRECT_THROTTLE);
2323
Mel Gorman55150612012-07-31 16:44:35 -07002324 /*
2325 * If the caller cannot enter the filesystem, it's possible that it
2326 * is due to the caller holding an FS lock or performing a journal
2327 * transaction in the case of a filesystem like ext[3|4]. In this case,
2328 * it is not safe to block on pfmemalloc_wait as kswapd could be
2329 * blocked waiting on the same lock. Instead, throttle for up to a
2330 * second before continuing.
2331 */
2332 if (!(gfp_mask & __GFP_FS)) {
2333 wait_event_interruptible_timeout(pgdat->pfmemalloc_wait,
2334 pfmemalloc_watermark_ok(pgdat), HZ);
Mel Gorman50694c22012-11-26 16:29:48 -08002335
2336 goto check_pending;
Mel Gorman55150612012-07-31 16:44:35 -07002337 }
2338
2339 /* Throttle until kswapd wakes the process */
2340 wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
2341 pfmemalloc_watermark_ok(pgdat));
Mel Gorman50694c22012-11-26 16:29:48 -08002342
2343check_pending:
2344 if (fatal_signal_pending(current))
2345 return true;
2346
2347out:
2348 return false;
Mel Gorman55150612012-07-31 16:44:35 -07002349}
2350
Mel Gormandac1d272008-04-28 02:12:12 -07002351unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002352 gfp_t gfp_mask, nodemask_t *nodemask)
Balbir Singh66e17072008-02-07 00:13:56 -08002353{
Mel Gorman33906bc2010-08-09 17:19:16 -07002354 unsigned long nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002355 struct scan_control sc = {
2356 .gfp_mask = gfp_mask,
2357 .may_writepage = !laptop_mode,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002358 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002359 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002360 .may_swap = 1,
Balbir Singh66e17072008-02-07 00:13:56 -08002361 .order = order,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002362 .priority = DEF_PRIORITY,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002363 .target_mem_cgroup = NULL,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002364 .nodemask = nodemask,
Balbir Singh66e17072008-02-07 00:13:56 -08002365 };
Ying Hana09ed5e2011-05-24 17:12:26 -07002366 struct shrink_control shrink = {
2367 .gfp_mask = sc.gfp_mask,
2368 };
Balbir Singh66e17072008-02-07 00:13:56 -08002369
Mel Gorman55150612012-07-31 16:44:35 -07002370 /*
Mel Gorman50694c22012-11-26 16:29:48 -08002371 * Do not enter reclaim if fatal signal was delivered while throttled.
2372 * 1 is returned so that the page allocator does not OOM kill at this
2373 * point.
Mel Gorman55150612012-07-31 16:44:35 -07002374 */
Mel Gorman50694c22012-11-26 16:29:48 -08002375 if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask))
Mel Gorman55150612012-07-31 16:44:35 -07002376 return 1;
2377
Mel Gorman33906bc2010-08-09 17:19:16 -07002378 trace_mm_vmscan_direct_reclaim_begin(order,
2379 sc.may_writepage,
2380 gfp_mask);
2381
Ying Hana09ed5e2011-05-24 17:12:26 -07002382 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
Mel Gorman33906bc2010-08-09 17:19:16 -07002383
2384 trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
2385
2386 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002387}
2388
Andrew Mortonc255a452012-07-31 16:43:02 -07002389#ifdef CONFIG_MEMCG
Balbir Singh66e17072008-02-07 00:13:56 -08002390
Johannes Weiner72835c82012-01-12 17:18:32 -08002391unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
Balbir Singh4e416952009-09-23 15:56:39 -07002392 gfp_t gfp_mask, bool noswap,
Ying Han0ae5e892011-05-26 16:25:25 -07002393 struct zone *zone,
2394 unsigned long *nr_scanned)
Balbir Singh4e416952009-09-23 15:56:39 -07002395{
2396 struct scan_control sc = {
Ying Han0ae5e892011-05-26 16:25:25 -07002397 .nr_scanned = 0,
KOSAKI Motohirob8f5c562010-08-10 18:03:02 -07002398 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh4e416952009-09-23 15:56:39 -07002399 .may_writepage = !laptop_mode,
2400 .may_unmap = 1,
2401 .may_swap = !noswap,
Balbir Singh4e416952009-09-23 15:56:39 -07002402 .order = 0,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002403 .priority = 0,
Johannes Weiner72835c82012-01-12 17:18:32 -08002404 .target_mem_cgroup = memcg,
Balbir Singh4e416952009-09-23 15:56:39 -07002405 };
Konstantin Khlebnikovf9be23d2012-05-29 15:07:02 -07002406 struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
Ying Han0ae5e892011-05-26 16:25:25 -07002407
Balbir Singh4e416952009-09-23 15:56:39 -07002408 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2409 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002410
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002411 trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002412 sc.may_writepage,
2413 sc.gfp_mask);
2414
Balbir Singh4e416952009-09-23 15:56:39 -07002415 /*
2416 * NOTE: Although we can get the priority field, using it
2417 * here is not a good idea, since it limits the pages we can scan.
2418 * if we don't reclaim here, the shrink_zone from balance_pgdat
2419 * will pick up pages from other mem cgroup's as well. We hack
2420 * the priority and make it zero.
2421 */
Konstantin Khlebnikovf9be23d2012-05-29 15:07:02 -07002422 shrink_lruvec(lruvec, &sc);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002423
2424 trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
2425
Ying Han0ae5e892011-05-26 16:25:25 -07002426 *nr_scanned = sc.nr_scanned;
Balbir Singh4e416952009-09-23 15:56:39 -07002427 return sc.nr_reclaimed;
2428}
2429
Johannes Weiner72835c82012-01-12 17:18:32 -08002430unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
KOSAKI Motohiroa7885eb2009-01-07 18:08:24 -08002431 gfp_t gfp_mask,
Johannes Weiner185efc02011-09-14 16:21:58 -07002432 bool noswap)
Balbir Singh66e17072008-02-07 00:13:56 -08002433{
Balbir Singh4e416952009-09-23 15:56:39 -07002434 struct zonelist *zonelist;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002435 unsigned long nr_reclaimed;
Ying Han889976d2011-05-26 16:25:33 -07002436 int nid;
Balbir Singh66e17072008-02-07 00:13:56 -08002437 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08002438 .may_writepage = !laptop_mode,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002439 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002440 .may_swap = !noswap,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002441 .nr_to_reclaim = SWAP_CLUSTER_MAX,
Balbir Singh66e17072008-02-07 00:13:56 -08002442 .order = 0,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002443 .priority = DEF_PRIORITY,
Johannes Weiner72835c82012-01-12 17:18:32 -08002444 .target_mem_cgroup = memcg,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -07002445 .nodemask = NULL, /* we don't care the placement */
Ying Hana09ed5e2011-05-24 17:12:26 -07002446 .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
2447 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
2448 };
2449 struct shrink_control shrink = {
2450 .gfp_mask = sc.gfp_mask,
Balbir Singh66e17072008-02-07 00:13:56 -08002451 };
Balbir Singh66e17072008-02-07 00:13:56 -08002452
Ying Han889976d2011-05-26 16:25:33 -07002453 /*
2454 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
2455 * take care of from where we get pages. So the node where we start the
2456 * scan does not need to be the current node.
2457 */
Johannes Weiner72835c82012-01-12 17:18:32 -08002458 nid = mem_cgroup_select_victim_node(memcg);
Ying Han889976d2011-05-26 16:25:33 -07002459
2460 zonelist = NODE_DATA(nid)->node_zonelists;
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002461
2462 trace_mm_vmscan_memcg_reclaim_begin(0,
2463 sc.may_writepage,
2464 sc.gfp_mask);
2465
Ying Hana09ed5e2011-05-24 17:12:26 -07002466 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
KOSAKI Motohirobdce6d92010-08-09 17:19:56 -07002467
2468 trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
2469
2470 return nr_reclaimed;
Balbir Singh66e17072008-02-07 00:13:56 -08002471}
2472#endif
2473
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002474static void age_active_anon(struct zone *zone, struct scan_control *sc)
Johannes Weinerf16015f2012-01-12 17:17:52 -08002475{
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002476 struct mem_cgroup *memcg;
Johannes Weinerf16015f2012-01-12 17:17:52 -08002477
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002478 if (!total_swap_pages)
2479 return;
2480
2481 memcg = mem_cgroup_iter(NULL, NULL, NULL);
2482 do {
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07002483 struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002484
Konstantin Khlebnikovc56d5c72012-05-29 15:07:00 -07002485 if (inactive_anon_is_low(lruvec))
Konstantin Khlebnikov1a93be02012-05-29 15:07:01 -07002486 shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002487 sc, LRU_ACTIVE_ANON);
Johannes Weinerb95a2f22012-01-12 17:18:06 -08002488
2489 memcg = mem_cgroup_iter(NULL, memcg, NULL);
2490 } while (memcg);
Johannes Weinerf16015f2012-01-12 17:17:52 -08002491}
2492
Johannes Weiner60cefed2012-11-29 13:54:23 -08002493static bool zone_balanced(struct zone *zone, int order,
2494 unsigned long balance_gap, int classzone_idx)
2495{
2496 if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
2497 balance_gap, classzone_idx, 0))
2498 return false;
2499
Kirill A. Shutemovd84da3f2012-12-11 16:00:31 -08002500 if (IS_ENABLED(CONFIG_COMPACTION) && order &&
2501 !compaction_suitable(zone, order))
Johannes Weiner60cefed2012-11-29 13:54:23 -08002502 return false;
2503
2504 return true;
2505}
2506
Mel Gorman1741c872011-01-13 15:46:21 -08002507/*
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002508 * pgdat_balanced() is used when checking if a node is balanced.
2509 *
2510 * For order-0, all zones must be balanced!
2511 *
2512 * For high-order allocations only zones that meet watermarks and are in a
2513 * zone allowed by the callers classzone_idx are added to balanced_pages. The
2514 * total of balanced pages must be at least 25% of the zones allowed by
2515 * classzone_idx for the node to be considered balanced. Forcing all zones to
2516 * be balanced for high orders can cause excessive reclaim when there are
2517 * imbalanced zones.
Mel Gorman1741c872011-01-13 15:46:21 -08002518 * The choice of 25% is due to
2519 * o a 16M DMA zone that is balanced will not balance a zone on any
2520 * reasonable sized machine
2521 * o On all other machines, the top zone must be at least a reasonable
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002522 * percentage of the middle zones. For example, on 32-bit x86, highmem
Mel Gorman1741c872011-01-13 15:46:21 -08002523 * would need to be at least 256M for it to be balance a whole node.
2524 * Similarly, on x86-64 the Normal zone would need to be at least 1G
2525 * to balance a node on its own. These seemed like reasonable ratios.
2526 */
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002527static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx)
Mel Gorman1741c872011-01-13 15:46:21 -08002528{
2529 unsigned long present_pages = 0;
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002530 unsigned long balanced_pages = 0;
Mel Gorman1741c872011-01-13 15:46:21 -08002531 int i;
2532
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002533 /* Check the watermark levels */
2534 for (i = 0; i <= classzone_idx; i++) {
2535 struct zone *zone = pgdat->node_zones + i;
Mel Gorman1741c872011-01-13 15:46:21 -08002536
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002537 if (!populated_zone(zone))
2538 continue;
2539
2540 present_pages += zone->present_pages;
2541
2542 /*
2543 * A special case here:
2544 *
2545 * balance_pgdat() skips over all_unreclaimable after
2546 * DEF_PRIORITY. Effectively, it considers them balanced so
2547 * they must be considered balanced here as well!
2548 */
2549 if (zone->all_unreclaimable) {
2550 balanced_pages += zone->present_pages;
2551 continue;
2552 }
2553
2554 if (zone_balanced(zone, order, 0, i))
2555 balanced_pages += zone->present_pages;
2556 else if (!order)
2557 return false;
2558 }
2559
2560 if (order)
2561 return balanced_pages >= (present_pages >> 2);
2562 else
2563 return true;
Mel Gorman1741c872011-01-13 15:46:21 -08002564}
2565
Mel Gorman55150612012-07-31 16:44:35 -07002566/*
2567 * Prepare kswapd for sleeping. This verifies that there are no processes
2568 * waiting in throttle_direct_reclaim() and that watermarks have been met.
2569 *
2570 * Returns true if kswapd is ready to sleep
2571 */
2572static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
Mel Gormandc83edd2011-01-13 15:46:26 -08002573 int classzone_idx)
Mel Gormanf50de2d2009-12-14 17:58:53 -08002574{
Mel Gormanf50de2d2009-12-14 17:58:53 -08002575 /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
2576 if (remaining)
Mel Gorman55150612012-07-31 16:44:35 -07002577 return false;
2578
2579 /*
2580 * There is a potential race between when kswapd checks its watermarks
2581 * and a process gets throttled. There is also a potential race if
2582 * processes get throttled, kswapd wakes, a large process exits therby
2583 * balancing the zones that causes kswapd to miss a wakeup. If kswapd
2584 * is going to sleep, no process should be sleeping on pfmemalloc_wait
2585 * so wake them now if necessary. If necessary, processes will wake
2586 * kswapd and get throttled again
2587 */
2588 if (waitqueue_active(&pgdat->pfmemalloc_wait)) {
2589 wake_up(&pgdat->pfmemalloc_wait);
2590 return false;
2591 }
Mel Gormanf50de2d2009-12-14 17:58:53 -08002592
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002593 return pgdat_balanced(pgdat, order, classzone_idx);
Mel Gormanf50de2d2009-12-14 17:58:53 -08002594}
2595
Linus Torvalds1da177e2005-04-16 15:20:36 -07002596/*
2597 * For kswapd, balance_pgdat() will work across all this node's zones until
Mel Gorman41858962009-06-16 15:32:12 -07002598 * they are all at high_wmark_pages(zone).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 *
Mel Gorman0abdee22011-01-13 15:46:22 -08002600 * Returns the final order kswapd was reclaiming at
Linus Torvalds1da177e2005-04-16 15:20:36 -07002601 *
2602 * There is special handling here for zones which are full of pinned pages.
2603 * This can happen if the pages are all mlocked, or if they are all used by
2604 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
2605 * What we do is to detect the case where all pages in the zone have been
2606 * scanned twice and there has been zero successful reclaim. Mark the zone as
2607 * dead and from now on, only perform a short scan. Basically we're polling
2608 * the zone for when the problem goes away.
2609 *
2610 * kswapd scans the zones in the highmem->normal->dma direction. It skips
Mel Gorman41858962009-06-16 15:32:12 -07002611 * zones which have free_pages > high_wmark_pages(zone), but once a zone is
2612 * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
2613 * lower zones regardless of the number of free pages in the lower zones. This
2614 * interoperates with the page allocator fallback scheme to ensure that aging
2615 * of pages is balanced across the zones.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 */
Mel Gorman99504742011-01-13 15:46:20 -08002617static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
Mel Gormandc83edd2011-01-13 15:46:26 -08002618 int *classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002619{
Zlatko Calusiccda73a12012-12-20 00:25:13 +01002620 struct zone *unbalanced_zone;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621 int i;
Mel Gorman99504742011-01-13 15:46:20 -08002622 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
Andrew Morton69e05942006-03-22 00:08:19 -08002623 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002624 struct reclaim_state *reclaim_state = current->reclaim_state;
Ying Han0ae5e892011-05-26 16:25:25 -07002625 unsigned long nr_soft_reclaimed;
2626 unsigned long nr_soft_scanned;
Andrew Morton179e9632006-03-22 00:08:18 -08002627 struct scan_control sc = {
2628 .gfp_mask = GFP_KERNEL,
Johannes Weinera6dc60f82009-03-31 15:19:30 -07002629 .may_unmap = 1,
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07002630 .may_swap = 1,
KOSAKI Motohiro22fba332009-12-14 17:59:10 -08002631 /*
2632 * kswapd doesn't want to be bailed out while reclaim. because
2633 * we want to put equal scanning pressure on each zone.
2634 */
2635 .nr_to_reclaim = ULONG_MAX,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07002636 .order = order,
Johannes Weinerf16015f2012-01-12 17:17:52 -08002637 .target_mem_cgroup = NULL,
Andrew Morton179e9632006-03-22 00:08:18 -08002638 };
Ying Hana09ed5e2011-05-24 17:12:26 -07002639 struct shrink_control shrink = {
2640 .gfp_mask = sc.gfp_mask,
2641 };
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642loop_again:
2643 total_scanned = 0;
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002644 sc.priority = DEF_PRIORITY;
Rik van Riela79311c2009-01-06 14:40:01 -08002645 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07002646 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07002647 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002649 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002650 unsigned long lru_pages = 0;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002651 int has_under_min_watermark_zone = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652
Zlatko Calusiccda73a12012-12-20 00:25:13 +01002653 unbalanced_zone = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002655 /*
2656 * Scan in the highmem->dma direction for the highest
2657 * zone which needs scanning
2658 */
2659 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
2660 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002662 if (!populated_zone(zone))
2663 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002664
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002665 if (zone->all_unreclaimable &&
2666 sc.priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002667 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668
Rik van Riel556adec2008-10-18 20:26:34 -07002669 /*
2670 * Do some background aging of the anon list, to give
2671 * pages a chance to be referenced before reclaiming.
2672 */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002673 age_active_anon(zone, &sc);
Rik van Riel556adec2008-10-18 20:26:34 -07002674
Mel Gormancc715d92012-03-21 16:34:00 -07002675 /*
2676 * If the number of buffer_heads in the machine
2677 * exceeds the maximum allowed level and this node
2678 * has a highmem zone, force kswapd to reclaim from
2679 * it to relieve lowmem pressure.
2680 */
2681 if (buffer_heads_over_limit && is_highmem_idx(i)) {
2682 end_zone = i;
2683 break;
2684 }
2685
Johannes Weiner60cefed2012-11-29 13:54:23 -08002686 if (!zone_balanced(zone, order, 0, 0)) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002687 end_zone = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002688 break;
Shaohua Li439423f2011-08-25 15:59:12 -07002689 } else {
2690 /* If balanced, clear the congested flag */
2691 zone_clear_flag(zone, ZONE_CONGESTED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002692 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002693 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08002694 if (i < 0)
2695 goto out;
2696
Linus Torvalds1da177e2005-04-16 15:20:36 -07002697 for (i = 0; i <= end_zone; i++) {
2698 struct zone *zone = pgdat->node_zones + i;
2699
Wu Fengguangadea02a2009-09-21 17:01:42 -07002700 lru_pages += zone_reclaimable_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002701 }
2702
2703 /*
2704 * Now scan the zone in the dma->highmem direction, stopping
2705 * at the last zone which needs scanning.
2706 *
2707 * We do this because the page allocator works in the opposite
2708 * direction. This prevents the page allocator from allocating
2709 * pages behind kswapd's direction of progress, which would
2710 * cause too much scanning of the lower zones.
2711 */
2712 for (i = 0; i <= end_zone; i++) {
2713 struct zone *zone = pgdat->node_zones + i;
Rik van Rielfe2c2a12012-03-21 16:33:51 -07002714 int nr_slab, testorder;
Mel Gorman8afdcec2011-03-22 16:33:04 -07002715 unsigned long balance_gap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002716
Con Kolivasf3fe6512006-01-06 00:11:15 -08002717 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002718 continue;
2719
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002720 if (zone->all_unreclaimable &&
2721 sc.priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002722 continue;
2723
Linus Torvalds1da177e2005-04-16 15:20:36 -07002724 sc.nr_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002725
Ying Han0ae5e892011-05-26 16:25:25 -07002726 nr_soft_scanned = 0;
Balbir Singh4e416952009-09-23 15:56:39 -07002727 /*
2728 * Call soft limit reclaim before calling shrink_zone.
Balbir Singh4e416952009-09-23 15:56:39 -07002729 */
Ying Han0ae5e892011-05-26 16:25:25 -07002730 nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
2731 order, sc.gfp_mask,
2732 &nr_soft_scanned);
2733 sc.nr_reclaimed += nr_soft_reclaimed;
2734 total_scanned += nr_soft_scanned;
KOSAKI Motohiro00918b62010-08-10 18:03:05 -07002735
Rik van Riel32a43302007-10-16 01:24:50 -07002736 /*
Mel Gorman8afdcec2011-03-22 16:33:04 -07002737 * We put equal pressure on every zone, unless
2738 * one zone has way too many pages free
2739 * already. The "too many pages" is defined
2740 * as the high wmark plus a "gap" where the
2741 * gap is either the low watermark or 1%
2742 * of the zone, whichever is smaller.
Rik van Riel32a43302007-10-16 01:24:50 -07002743 */
Mel Gorman8afdcec2011-03-22 16:33:04 -07002744 balance_gap = min(low_wmark_pages(zone),
2745 (zone->present_pages +
2746 KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
2747 KSWAPD_ZONE_BALANCE_GAP_RATIO);
Rik van Rielfe2c2a12012-03-21 16:33:51 -07002748 /*
2749 * Kswapd reclaims only single pages with compaction
2750 * enabled. Trying too hard to reclaim until contiguous
2751 * free pages have become available can hurt performance
2752 * by evicting too much useful data from memory.
2753 * Do not reclaim more than needed for compaction.
2754 */
2755 testorder = order;
Kirill A. Shutemovd84da3f2012-12-11 16:00:31 -08002756 if (IS_ENABLED(CONFIG_COMPACTION) && order &&
Rik van Rielfe2c2a12012-03-21 16:33:51 -07002757 compaction_suitable(zone, order) !=
2758 COMPACT_SKIPPED)
2759 testorder = 0;
2760
Mel Gormancc715d92012-03-21 16:34:00 -07002761 if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
Johannes Weiner60cefed2012-11-29 13:54:23 -08002762 !zone_balanced(zone, testorder,
2763 balance_gap, end_zone)) {
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002764 shrink_zone(zone, &sc);
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08002765
Mel Gormand7868da2011-07-08 15:39:38 -07002766 reclaim_state->reclaimed_slab = 0;
2767 nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
2768 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
2769 total_scanned += sc.nr_scanned;
2770
2771 if (nr_slab == 0 && !zone_reclaimable(zone))
2772 zone->all_unreclaimable = 1;
2773 }
2774
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775 /*
2776 * If we've done a decent amount of scanning and
2777 * the reclaim ratio is low, start doing writepage
2778 * even in laptop mode
2779 */
2780 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08002781 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 sc.may_writepage = 1;
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002783
Mel Gorman215ddd62011-07-08 15:39:40 -07002784 if (zone->all_unreclaimable) {
2785 if (end_zone && end_zone == i)
2786 end_zone--;
Mel Gormand7868da2011-07-08 15:39:38 -07002787 continue;
Mel Gorman215ddd62011-07-08 15:39:40 -07002788 }
Mel Gormand7868da2011-07-08 15:39:38 -07002789
Johannes Weiner60cefed2012-11-29 13:54:23 -08002790 if (!zone_balanced(zone, testorder, 0, end_zone)) {
Zlatko Calusiccda73a12012-12-20 00:25:13 +01002791 unbalanced_zone = zone;
Minchan Kim45973d72010-03-05 13:41:45 -08002792 /*
2793 * We are still under min water mark. This
2794 * means that we have a GFP_ATOMIC allocation
2795 * failure risk. Hurry up!
2796 */
Mel Gorman88f5acf2011-01-13 15:45:41 -08002797 if (!zone_watermark_ok_safe(zone, order,
Minchan Kim45973d72010-03-05 13:41:45 -08002798 min_wmark_pages(zone), end_zone, 0))
2799 has_under_min_watermark_zone = 1;
Mel Gorman0e093d992010-10-26 14:21:45 -07002800 } else {
2801 /*
2802 * If a zone reaches its high watermark,
2803 * consider it to be no longer congested. It's
2804 * possible there are dirty pages backed by
2805 * congested BDIs but as pressure is relieved,
Wanpeng Liab8704b2012-06-17 09:27:18 +08002806 * speculatively avoid congestion waits
Mel Gorman0e093d992010-10-26 14:21:45 -07002807 */
2808 zone_clear_flag(zone, ZONE_CONGESTED);
Minchan Kim45973d72010-03-05 13:41:45 -08002809 }
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002810
Linus Torvalds1da177e2005-04-16 15:20:36 -07002811 }
Mel Gorman55150612012-07-31 16:44:35 -07002812
2813 /*
2814 * If the low watermark is met there is no need for processes
2815 * to be throttled on pfmemalloc_wait as they should not be
2816 * able to safely make forward progress. Wake them
2817 */
2818 if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
2819 pfmemalloc_watermark_ok(pgdat))
2820 wake_up(&pgdat->pfmemalloc_wait);
2821
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002822 if (pgdat_balanced(pgdat, order, *classzone_idx))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823 break; /* kswapd: all done */
2824 /*
2825 * OK, kswapd is getting into trouble. Take a nap, then take
2826 * another pass across the zones.
2827 */
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002828 if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) {
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002829 if (has_under_min_watermark_zone)
2830 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
Zlatko Calusicecccd122012-12-28 03:16:38 +01002831 else if (unbalanced_zone)
Zlatko Calusiccda73a12012-12-20 00:25:13 +01002832 wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10);
KOSAKI Motohirobb3ab592009-12-14 17:58:55 -08002833 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834
2835 /*
2836 * We do this so kswapd doesn't build up large priorities for
2837 * example when it is freeing in parallel with allocators. It
2838 * matches the direct reclaim path behaviour in terms of impact
2839 * on zone->*_priority.
2840 */
Rik van Riela79311c2009-01-06 14:40:01 -08002841 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842 break;
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07002843 } while (--sc.priority >= 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002844out:
Mel Gorman99504742011-01-13 15:46:20 -08002845
Zlatko Calusic4ae0a482012-12-23 15:12:54 +01002846 if (!pgdat_balanced(pgdat, order, *classzone_idx)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08002848
2849 try_to_freeze();
2850
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08002851 /*
2852 * Fragmentation may mean that the system cannot be
2853 * rebalanced for high-order allocations in all zones.
2854 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
2855 * it means the zones have been fully scanned and are still
2856 * not balanced. For high-order allocations, there is
2857 * little point trying all over again as kswapd may
2858 * infinite loop.
2859 *
2860 * Instead, recheck all watermarks at order-0 as they
2861 * are the most important. If watermarks are ok, kswapd will go
2862 * back to sleep. High-order users can still perform direct
2863 * reclaim if they wish.
2864 */
2865 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
2866 order = sc.order = 0;
2867
Linus Torvalds1da177e2005-04-16 15:20:36 -07002868 goto loop_again;
2869 }
2870
Mel Gorman99504742011-01-13 15:46:20 -08002871 /*
2872 * If kswapd was reclaiming at a higher order, it has the option of
2873 * sleeping without all zones being balanced. Before it does, it must
2874 * ensure that the watermarks for order-0 on *all* zones are met and
2875 * that the congestion flags are cleared. The congestion flag must
2876 * be cleared as kswapd is the only mechanism that clears the flag
2877 * and it is potentially going to sleep here.
2878 */
2879 if (order) {
Rik van Riel7be62de2012-03-21 16:33:52 -07002880 int zones_need_compaction = 1;
2881
Mel Gorman99504742011-01-13 15:46:20 -08002882 for (i = 0; i <= end_zone; i++) {
2883 struct zone *zone = pgdat->node_zones + i;
2884
2885 if (!populated_zone(zone))
2886 continue;
2887
Rik van Riel7be62de2012-03-21 16:33:52 -07002888 /* Check if the memory needs to be defragmented. */
2889 if (zone_watermark_ok(zone, order,
2890 low_wmark_pages(zone), *classzone_idx, 0))
2891 zones_need_compaction = 0;
Mel Gorman99504742011-01-13 15:46:20 -08002892 }
Rik van Riel7be62de2012-03-21 16:33:52 -07002893
2894 if (zones_need_compaction)
2895 compact_pgdat(pgdat, order);
Mel Gorman99504742011-01-13 15:46:20 -08002896 }
2897
Mel Gorman0abdee22011-01-13 15:46:22 -08002898 /*
Mel Gorman55150612012-07-31 16:44:35 -07002899 * Return the order we were reclaiming at so prepare_kswapd_sleep()
Mel Gorman0abdee22011-01-13 15:46:22 -08002900 * makes a decision on the order we were last reclaiming at. However,
2901 * if another caller entered the allocator slow path while kswapd
2902 * was awake, order will remain at the higher level
2903 */
Mel Gormandc83edd2011-01-13 15:46:26 -08002904 *classzone_idx = end_zone;
Mel Gorman0abdee22011-01-13 15:46:22 -08002905 return order;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002906}
2907
Mel Gormandc83edd2011-01-13 15:46:26 -08002908static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002909{
2910 long remaining = 0;
2911 DEFINE_WAIT(wait);
2912
2913 if (freezing(current) || kthread_should_stop())
2914 return;
2915
2916 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2917
2918 /* Try to sleep for a short interval */
Mel Gorman55150612012-07-31 16:44:35 -07002919 if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002920 remaining = schedule_timeout(HZ/10);
2921 finish_wait(&pgdat->kswapd_wait, &wait);
2922 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
2923 }
2924
2925 /*
2926 * After a short sleep, check if it was a premature sleep. If not, then
2927 * go fully to sleep until explicitly woken up.
2928 */
Mel Gorman55150612012-07-31 16:44:35 -07002929 if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) {
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002930 trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
2931
2932 /*
2933 * vmstat counters are not perfectly accurate and the estimated
2934 * value for counters such as NR_FREE_PAGES can deviate from the
2935 * true value by nr_online_cpus * threshold. To avoid the zone
2936 * watermarks being breached while under pressure, we reduce the
2937 * per-cpu vmstat threshold while kswapd is awake and restore
2938 * them before going back to sleep.
2939 */
2940 set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
Aaditya Kumar1c7e7f62012-07-17 15:48:07 -07002941
Mel Gorman62997022012-10-08 16:32:47 -07002942 /*
2943 * Compaction records what page blocks it recently failed to
2944 * isolate pages from and skips them in the future scanning.
2945 * When kswapd is going to sleep, it is reasonable to assume
2946 * that pages and compaction may succeed so reset the cache.
2947 */
2948 reset_isolation_suitable(pgdat);
2949
Aaditya Kumar1c7e7f62012-07-17 15:48:07 -07002950 if (!kthread_should_stop())
2951 schedule();
2952
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002953 set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
2954 } else {
2955 if (remaining)
2956 count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
2957 else
2958 count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
2959 }
2960 finish_wait(&pgdat->kswapd_wait, &wait);
2961}
2962
Linus Torvalds1da177e2005-04-16 15:20:36 -07002963/*
2964 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002965 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002966 *
2967 * This basically trickles out pages so that we have _some_
2968 * free memory available even if there is no other activity
2969 * that frees anything up. This is needed for things like routing
2970 * etc, where we otherwise might have all activity going on in
2971 * asynchronous contexts that cannot page things out.
2972 *
2973 * If there are applications that are active memory-allocators
2974 * (most normal use), this basically shouldn't matter.
2975 */
2976static int kswapd(void *p)
2977{
Mel Gorman215ddd62011-07-08 15:39:40 -07002978 unsigned long order, new_order;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07002979 unsigned balanced_order;
Mel Gorman215ddd62011-07-08 15:39:40 -07002980 int classzone_idx, new_classzone_idx;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07002981 int balanced_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002982 pg_data_t *pgdat = (pg_data_t*)p;
2983 struct task_struct *tsk = current;
KOSAKI Motohirof0bc0a62011-01-13 15:45:50 -08002984
Linus Torvalds1da177e2005-04-16 15:20:36 -07002985 struct reclaim_state reclaim_state = {
2986 .reclaimed_slab = 0,
2987 };
Rusty Russella70f7302009-03-13 14:49:46 +10302988 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002989
Nick Piggincf40bd12009-01-21 08:12:39 +01002990 lockdep_set_current_reclaim_state(GFP_KERNEL);
2991
Rusty Russell174596a2009-01-01 10:12:29 +10302992 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07002993 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002994 current->reclaim_state = &reclaim_state;
2995
2996 /*
2997 * Tell the memory management that we're a "memory allocator",
2998 * and that if we need more memory we should get access to it
2999 * regardless (see "__alloc_pages()"). "kswapd" should
3000 * never get caught in the normal page freeing logic.
3001 *
3002 * (Kswapd normally doesn't need memory anyway, but sometimes
3003 * you need a small amount of memory in order to be able to
3004 * page out something else, and this flag essentially protects
3005 * us from recursively trying to free more memory as we're
3006 * trying to free the first piece of memory in the first place).
3007 */
Christoph Lameter930d9152006-01-08 01:00:47 -08003008 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07003009 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003010
Mel Gorman215ddd62011-07-08 15:39:40 -07003011 order = new_order = 0;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003012 balanced_order = 0;
Mel Gorman215ddd62011-07-08 15:39:40 -07003013 classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003014 balanced_classzone_idx = classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003015 for ( ; ; ) {
Jeff Liu6f6313d2012-12-11 16:02:48 -08003016 bool ret;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07003017
Mel Gorman215ddd62011-07-08 15:39:40 -07003018 /*
3019 * If the last balance_pgdat was unsuccessful it's unlikely a
3020 * new request of a similar or harder type will succeed soon
3021 * so consider going to sleep on the basis we reclaimed at
3022 */
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003023 if (balanced_classzone_idx >= new_classzone_idx &&
3024 balanced_order == new_order) {
Mel Gorman215ddd62011-07-08 15:39:40 -07003025 new_order = pgdat->kswapd_max_order;
3026 new_classzone_idx = pgdat->classzone_idx;
3027 pgdat->kswapd_max_order = 0;
3028 pgdat->classzone_idx = pgdat->nr_zones - 1;
3029 }
3030
Mel Gorman99504742011-01-13 15:46:20 -08003031 if (order < new_order || classzone_idx > new_classzone_idx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003032 /*
3033 * Don't sleep if someone wants a larger 'order'
Mel Gorman99504742011-01-13 15:46:20 -08003034 * allocation or has tigher zone constraints
Linus Torvalds1da177e2005-04-16 15:20:36 -07003035 */
3036 order = new_order;
Mel Gorman99504742011-01-13 15:46:20 -08003037 classzone_idx = new_classzone_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003038 } else {
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003039 kswapd_try_to_sleep(pgdat, balanced_order,
3040 balanced_classzone_idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003041 order = pgdat->kswapd_max_order;
Mel Gorman99504742011-01-13 15:46:20 -08003042 classzone_idx = pgdat->classzone_idx;
Alex,Shif0dfcde2011-10-31 17:08:45 -07003043 new_order = order;
3044 new_classzone_idx = classzone_idx;
Mel Gorman4d405022011-01-13 15:46:23 -08003045 pgdat->kswapd_max_order = 0;
Mel Gorman215ddd62011-07-08 15:39:40 -07003046 pgdat->classzone_idx = pgdat->nr_zones - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003047 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003048
David Rientjes8fe23e02009-12-14 17:58:33 -08003049 ret = try_to_freeze();
3050 if (kthread_should_stop())
3051 break;
3052
3053 /*
3054 * We can speed up thawing tasks if we don't call balance_pgdat
3055 * after returning from the refrigerator
3056 */
Mel Gorman33906bc2010-08-09 17:19:16 -07003057 if (!ret) {
3058 trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
Alex,Shid2ebd0f62011-10-31 17:08:39 -07003059 balanced_classzone_idx = classzone_idx;
3060 balanced_order = balance_pgdat(pgdat, order,
3061 &balanced_classzone_idx);
Mel Gorman33906bc2010-08-09 17:19:16 -07003062 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003063 }
Takamori Yamaguchib0a8cc52012-11-08 15:53:39 -08003064
3065 current->reclaim_state = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003066 return 0;
3067}
3068
3069/*
3070 * A zone is low on free memory, so wake its kswapd task to service it.
3071 */
Mel Gorman99504742011-01-13 15:46:20 -08003072void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003073{
3074 pg_data_t *pgdat;
3075
Con Kolivasf3fe6512006-01-06 00:11:15 -08003076 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003077 return;
3078
Paul Jackson02a0e532006-12-13 00:34:25 -08003079 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003080 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08003081 pgdat = zone->zone_pgdat;
Mel Gorman99504742011-01-13 15:46:20 -08003082 if (pgdat->kswapd_max_order < order) {
Mel Gorman88f5acf2011-01-13 15:45:41 -08003083 pgdat->kswapd_max_order = order;
Mel Gorman99504742011-01-13 15:46:20 -08003084 pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
3085 }
Con Kolivas8d0986e2005-09-13 01:25:07 -07003086 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003087 return;
Mel Gorman88f5acf2011-01-13 15:45:41 -08003088 if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
3089 return;
3090
3091 trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
Con Kolivas8d0986e2005-09-13 01:25:07 -07003092 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003093}
3094
Wu Fengguangadea02a2009-09-21 17:01:42 -07003095/*
3096 * The reclaimable count would be mostly accurate.
3097 * The less reclaimable pages may be
3098 * - mlocked pages, which will be moved to unevictable list when encountered
3099 * - mapped pages, which may require several travels to be reclaimed
3100 * - dirty pages, which is not "instantly" reclaimable
3101 */
3102unsigned long global_reclaimable_pages(void)
Rik van Riel4f98a2f2008-10-18 20:26:32 -07003103{
Wu Fengguangadea02a2009-09-21 17:01:42 -07003104 int nr;
3105
3106 nr = global_page_state(NR_ACTIVE_FILE) +
3107 global_page_state(NR_INACTIVE_FILE);
3108
3109 if (nr_swap_pages > 0)
3110 nr += global_page_state(NR_ACTIVE_ANON) +
3111 global_page_state(NR_INACTIVE_ANON);
3112
3113 return nr;
3114}
3115
3116unsigned long zone_reclaimable_pages(struct zone *zone)
3117{
3118 int nr;
3119
3120 nr = zone_page_state(zone, NR_ACTIVE_FILE) +
3121 zone_page_state(zone, NR_INACTIVE_FILE);
3122
3123 if (nr_swap_pages > 0)
3124 nr += zone_page_state(zone, NR_ACTIVE_ANON) +
3125 zone_page_state(zone, NR_INACTIVE_ANON);
3126
3127 return nr;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07003128}
3129
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02003130#ifdef CONFIG_HIBERNATION
Linus Torvalds1da177e2005-04-16 15:20:36 -07003131/*
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003132 * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003133 * freed pages.
3134 *
3135 * Rather than trying to age LRUs the aim is to preserve the overall
3136 * LRU order by reclaiming preferentially
3137 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07003138 */
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003139unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003140{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003141 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003142 struct scan_control sc = {
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003143 .gfp_mask = GFP_HIGHUSER_MOVABLE,
3144 .may_swap = 1,
3145 .may_unmap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003146 .may_writepage = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003147 .nr_to_reclaim = nr_to_reclaim,
3148 .hibernation_mode = 1,
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003149 .order = 0,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07003150 .priority = DEF_PRIORITY,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003151 };
Ying Hana09ed5e2011-05-24 17:12:26 -07003152 struct shrink_control shrink = {
3153 .gfp_mask = sc.gfp_mask,
3154 };
3155 struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003156 struct task_struct *p = current;
3157 unsigned long nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003158
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003159 p->flags |= PF_MEMALLOC;
3160 lockdep_set_current_reclaim_state(sc.gfp_mask);
3161 reclaim_state.reclaimed_slab = 0;
3162 p->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08003163
Ying Hana09ed5e2011-05-24 17:12:26 -07003164 nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003165
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003166 p->reclaim_state = NULL;
3167 lockdep_clear_current_reclaim_state();
3168 p->flags &= ~PF_MEMALLOC;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07003169
KOSAKI Motohiro7b517552009-12-14 17:59:12 -08003170 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003171}
Rafael J. Wysockic6f37f12009-05-24 22:16:31 +02003172#endif /* CONFIG_HIBERNATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003173
Linus Torvalds1da177e2005-04-16 15:20:36 -07003174/* It's optimal to keep kswapds on the same CPUs as their memory, but
3175 not required for correctness. So if the last cpu in a node goes
3176 away, we get changed to run anywhere: as the first one comes back,
3177 restore their cpu bindings. */
Greg Kroah-Hartmanfcb35a92012-12-21 15:01:06 -08003178static int cpu_callback(struct notifier_block *nfb, unsigned long action,
3179 void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003180{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07003181 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003182
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003183 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Lai Jiangshan48fb2e22012-12-12 13:51:43 -08003184 for_each_node_state(nid, N_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07003185 pg_data_t *pgdat = NODE_DATA(nid);
Rusty Russella70f7302009-03-13 14:49:46 +10303186 const struct cpumask *mask;
3187
3188 mask = cpumask_of_node(pgdat->node_id);
Mike Travisc5f59f02008-04-04 18:11:10 -07003189
Rusty Russell3e597942009-01-01 10:12:24 +10303190 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003191 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07003192 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003193 }
3194 }
3195 return NOTIFY_OK;
3196}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003197
Yasunori Goto3218ae12006-06-27 02:53:33 -07003198/*
3199 * This kswapd start function will be called by init and node-hot-add.
3200 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
3201 */
3202int kswapd_run(int nid)
3203{
3204 pg_data_t *pgdat = NODE_DATA(nid);
3205 int ret = 0;
3206
3207 if (pgdat->kswapd)
3208 return 0;
3209
3210 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
3211 if (IS_ERR(pgdat->kswapd)) {
3212 /* failure at boot is fatal */
3213 BUG_ON(system_state == SYSTEM_BOOTING);
Wen Congyang18b48d52012-09-17 14:08:55 -07003214 pgdat->kswapd = NULL;
Gavin Shand5dc0ad2012-10-08 16:29:27 -07003215 pr_err("Failed to start kswapd on node %d\n", nid);
3216 ret = PTR_ERR(pgdat->kswapd);
Yasunori Goto3218ae12006-06-27 02:53:33 -07003217 }
3218 return ret;
3219}
3220
David Rientjes8fe23e02009-12-14 17:58:33 -08003221/*
Jiang Liud8adde12012-07-11 14:01:52 -07003222 * Called by memory hotplug when all memory in a node is offlined. Caller must
3223 * hold lock_memory_hotplug().
David Rientjes8fe23e02009-12-14 17:58:33 -08003224 */
3225void kswapd_stop(int nid)
3226{
3227 struct task_struct *kswapd = NODE_DATA(nid)->kswapd;
3228
Jiang Liud8adde12012-07-11 14:01:52 -07003229 if (kswapd) {
David Rientjes8fe23e02009-12-14 17:58:33 -08003230 kthread_stop(kswapd);
Jiang Liud8adde12012-07-11 14:01:52 -07003231 NODE_DATA(nid)->kswapd = NULL;
3232 }
David Rientjes8fe23e02009-12-14 17:58:33 -08003233}
3234
Linus Torvalds1da177e2005-04-16 15:20:36 -07003235static int __init kswapd_init(void)
3236{
Yasunori Goto3218ae12006-06-27 02:53:33 -07003237 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08003238
Linus Torvalds1da177e2005-04-16 15:20:36 -07003239 swap_setup();
Lai Jiangshan48fb2e22012-12-12 13:51:43 -08003240 for_each_node_state(nid, N_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07003241 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003242 hotcpu_notifier(cpu_callback, 0);
3243 return 0;
3244}
3245
3246module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08003247
3248#ifdef CONFIG_NUMA
3249/*
3250 * Zone reclaim mode
3251 *
3252 * If non-zero call zone_reclaim when the number of free pages falls below
3253 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08003254 */
3255int zone_reclaim_mode __read_mostly;
3256
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08003257#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07003258#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08003259#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
3260#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
3261
Christoph Lameter9eeff232006-01-18 17:42:31 -08003262/*
Christoph Lametera92f7122006-02-01 03:05:32 -08003263 * Priority for ZONE_RECLAIM. This determines the fraction of pages
3264 * of a node considered for each zone_reclaim. 4 scans 1/16th of
3265 * a zone.
3266 */
3267#define ZONE_RECLAIM_PRIORITY 4
3268
Christoph Lameter9eeff232006-01-18 17:42:31 -08003269/*
Christoph Lameter96146342006-07-03 00:24:13 -07003270 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
3271 * occur.
3272 */
3273int sysctl_min_unmapped_ratio = 1;
3274
3275/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003276 * If the number of slab pages in a zone grows beyond this percentage then
3277 * slab reclaim needs to occur.
3278 */
3279int sysctl_min_slab_ratio = 5;
3280
Mel Gorman90afa5d2009-06-16 15:33:20 -07003281static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
3282{
3283 unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
3284 unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
3285 zone_page_state(zone, NR_ACTIVE_FILE);
3286
3287 /*
3288 * It's possible for there to be more file mapped pages than
3289 * accounted for by the pages on the file LRU lists because
3290 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
3291 */
3292 return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
3293}
3294
3295/* Work out how many page cache pages we can reclaim in this reclaim_mode */
3296static long zone_pagecache_reclaimable(struct zone *zone)
3297{
3298 long nr_pagecache_reclaimable;
3299 long delta = 0;
3300
3301 /*
3302 * If RECLAIM_SWAP is set, then all file pages are considered
3303 * potentially reclaimable. Otherwise, we have to worry about
3304 * pages like swapcache and zone_unmapped_file_pages() provides
3305 * a better estimate
3306 */
3307 if (zone_reclaim_mode & RECLAIM_SWAP)
3308 nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
3309 else
3310 nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
3311
3312 /* If we can't clean pages, remove dirty pages from consideration */
3313 if (!(zone_reclaim_mode & RECLAIM_WRITE))
3314 delta += zone_page_state(zone, NR_FILE_DIRTY);
3315
3316 /* Watch for any possible underflows due to delta */
3317 if (unlikely(delta > nr_pagecache_reclaimable))
3318 delta = nr_pagecache_reclaimable;
3319
3320 return nr_pagecache_reclaimable - delta;
3321}
3322
Christoph Lameter0ff38492006-09-25 23:31:52 -07003323/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08003324 * Try to free up some pages from this zone through reclaim.
3325 */
Andrew Morton179e9632006-03-22 00:08:18 -08003326static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08003327{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08003328 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08003329 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003330 struct task_struct *p = current;
3331 struct reclaim_state reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08003332 struct scan_control sc = {
3333 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
Johannes Weinera6dc60f82009-03-31 15:19:30 -07003334 .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
KOSAKI Motohiro2e2e4252009-04-21 12:24:57 -07003335 .may_swap = 1,
Andrew Morton62b726c2013-02-22 16:32:24 -08003336 .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08003337 .gfp_mask = gfp_mask,
Johannes Weinerbd2f6192009-03-31 15:19:38 -07003338 .order = order,
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07003339 .priority = ZONE_RECLAIM_PRIORITY,
Andrew Morton179e9632006-03-22 00:08:18 -08003340 };
Ying Hana09ed5e2011-05-24 17:12:26 -07003341 struct shrink_control shrink = {
3342 .gfp_mask = sc.gfp_mask,
3343 };
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003344 unsigned long nr_slab_pages0, nr_slab_pages1;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003345
Christoph Lameter9eeff232006-01-18 17:42:31 -08003346 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08003347 /*
3348 * We need to be able to allocate from the reserves for RECLAIM_SWAP
3349 * and we also need to be able to write out pages for RECLAIM_WRITE
3350 * and RECLAIM_SWAP.
3351 */
3352 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003353 lockdep_set_current_reclaim_state(gfp_mask);
Christoph Lameter9eeff232006-01-18 17:42:31 -08003354 reclaim_state.reclaimed_slab = 0;
3355 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08003356
Mel Gorman90afa5d2009-06-16 15:33:20 -07003357 if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
Christoph Lameter0ff38492006-09-25 23:31:52 -07003358 /*
3359 * Free memory by calling shrink zone with increasing
3360 * priorities until we have enough memory freed.
3361 */
Christoph Lameter0ff38492006-09-25 23:31:52 -07003362 do {
Konstantin Khlebnikov9e3b2f82012-05-29 15:06:57 -07003363 shrink_zone(zone, &sc);
3364 } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
Christoph Lameter0ff38492006-09-25 23:31:52 -07003365 }
Christoph Lameterc84db232006-02-01 03:05:29 -08003366
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003367 nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3368 if (nr_slab_pages0 > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003369 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08003370 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07003371 * many pages were freed in this zone. So we take the current
3372 * number of slab pages and shake the slab until it is reduced
3373 * by the same nr_pages that we used for reclaiming unmapped
3374 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003375 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07003376 * Note that shrink_slab will free memory on all zones and may
3377 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003378 */
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003379 for (;;) {
3380 unsigned long lru_pages = zone_reclaimable_pages(zone);
3381
3382 /* No reclaimable slab or very low memory pressure */
Ying Han1495f232011-05-24 17:12:27 -07003383 if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages))
KOSAKI Motohiro4dc4b3d2010-08-09 17:19:54 -07003384 break;
3385
3386 /* Freed enough memory */
3387 nr_slab_pages1 = zone_page_state(zone,
3388 NR_SLAB_RECLAIMABLE);
3389 if (nr_slab_pages1 + nr_pages <= nr_slab_pages0)
3390 break;
3391 }
Christoph Lameter83e33a42006-09-25 23:31:53 -07003392
3393 /*
3394 * Update nr_reclaimed by the number of slab pages we
3395 * reclaimed from this zone.
3396 */
KOSAKI Motohiro15748042010-08-09 17:19:50 -07003397 nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
3398 if (nr_slab_pages1 < nr_slab_pages0)
3399 sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1;
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08003400 }
3401
Christoph Lameter9eeff232006-01-18 17:42:31 -08003402 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08003403 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
KOSAKI Motohiro76ca5422010-03-05 13:41:47 -08003404 lockdep_clear_current_reclaim_state();
Rik van Riela79311c2009-01-06 14:40:01 -08003405 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08003406}
Andrew Morton179e9632006-03-22 00:08:18 -08003407
3408int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
3409{
Andrew Morton179e9632006-03-22 00:08:18 -08003410 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07003411 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003412
3413 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07003414 * Zone reclaim reclaims unmapped file backed pages and
3415 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07003416 *
Christoph Lameter96146342006-07-03 00:24:13 -07003417 * A small portion of unmapped file backed pages is needed for
3418 * file I/O otherwise pages read by file I/O will be immediately
3419 * thrown out if the zone is overallocated. So we do not reclaim
3420 * if less than a specified percentage of the zone is used by
3421 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08003422 */
Mel Gorman90afa5d2009-06-16 15:33:20 -07003423 if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
3424 zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003425 return ZONE_RECLAIM_FULL;
Andrew Morton179e9632006-03-22 00:08:18 -08003426
KOSAKI Motohiro93e4a892010-03-05 13:41:55 -08003427 if (zone->all_unreclaimable)
Mel Gormanfa5e0842009-06-16 15:33:22 -07003428 return ZONE_RECLAIM_FULL;
David Rientjesd773ed62007-10-16 23:26:01 -07003429
Andrew Morton179e9632006-03-22 00:08:18 -08003430 /*
David Rientjesd773ed62007-10-16 23:26:01 -07003431 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08003432 */
David Rientjesd773ed62007-10-16 23:26:01 -07003433 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003434 return ZONE_RECLAIM_NOSCAN;
Andrew Morton179e9632006-03-22 00:08:18 -08003435
3436 /*
3437 * Only run zone reclaim on the local zone or on zones that do not
3438 * have associated processors. This will favor the local processor
3439 * over remote processors and spread off node memory allocations
3440 * as wide as possible.
3441 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07003442 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07003443 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Mel Gormanfa5e0842009-06-16 15:33:22 -07003444 return ZONE_RECLAIM_NOSCAN;
David Rientjesd773ed62007-10-16 23:26:01 -07003445
3446 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
Mel Gormanfa5e0842009-06-16 15:33:22 -07003447 return ZONE_RECLAIM_NOSCAN;
3448
David Rientjesd773ed62007-10-16 23:26:01 -07003449 ret = __zone_reclaim(zone, gfp_mask, order);
3450 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
3451
Mel Gorman24cf725182009-06-16 15:33:23 -07003452 if (!ret)
3453 count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
3454
David Rientjesd773ed62007-10-16 23:26:01 -07003455 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08003456}
Christoph Lameter9eeff232006-01-18 17:42:31 -08003457#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003458
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003459/*
3460 * page_evictable - test whether a page is evictable
3461 * @page: the page to test
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003462 *
3463 * Test whether page is evictable--i.e., should be placed on active/inactive
Hugh Dickins39b5f292012-10-08 16:33:18 -07003464 * lists vs unevictable list.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003465 *
3466 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003467 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07003468 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07003469 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003470 */
Hugh Dickins39b5f292012-10-08 16:33:18 -07003471int page_evictable(struct page *page)
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003472{
Hugh Dickins39b5f292012-10-08 16:33:18 -07003473 return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07003474}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003475
Hugh Dickins850465792012-01-20 14:34:19 -08003476#ifdef CONFIG_SHMEM
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003477/**
Hugh Dickins24513262012-01-20 14:34:21 -08003478 * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list
3479 * @pages: array of pages to check
3480 * @nr_pages: number of pages to check
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003481 *
Hugh Dickins24513262012-01-20 14:34:21 -08003482 * Checks pages for evictability and moves them to the appropriate lru list.
Hugh Dickins850465792012-01-20 14:34:19 -08003483 *
3484 * This function is only used for SysV IPC SHM_UNLOCK.
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003485 */
Hugh Dickins24513262012-01-20 14:34:21 -08003486void check_move_unevictable_pages(struct page **pages, int nr_pages)
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003487{
Johannes Weiner925b7672012-01-12 17:18:15 -08003488 struct lruvec *lruvec;
Hugh Dickins24513262012-01-20 14:34:21 -08003489 struct zone *zone = NULL;
3490 int pgscanned = 0;
3491 int pgrescued = 0;
3492 int i;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003493
Hugh Dickins24513262012-01-20 14:34:21 -08003494 for (i = 0; i < nr_pages; i++) {
3495 struct page *page = pages[i];
3496 struct zone *pagezone;
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003497
Hugh Dickins24513262012-01-20 14:34:21 -08003498 pgscanned++;
3499 pagezone = page_zone(page);
3500 if (pagezone != zone) {
3501 if (zone)
3502 spin_unlock_irq(&zone->lru_lock);
3503 zone = pagezone;
3504 spin_lock_irq(&zone->lru_lock);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003505 }
Hugh Dickinsfa9add62012-05-29 15:07:09 -07003506 lruvec = mem_cgroup_page_lruvec(page, zone);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003507
Hugh Dickins24513262012-01-20 14:34:21 -08003508 if (!PageLRU(page) || !PageUnevictable(page))
3509 continue;
3510
Hugh Dickins39b5f292012-10-08 16:33:18 -07003511 if (page_evictable(page)) {
Hugh Dickins24513262012-01-20 14:34:21 -08003512 enum lru_list lru = page_lru_base_type(page);
3513
3514 VM_BUG_ON(PageActive(page));
3515 ClearPageUnevictable(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07003516 del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE);
3517 add_page_to_lru_list(page, lruvec, lru);
Hugh Dickins24513262012-01-20 14:34:21 -08003518 pgrescued++;
3519 }
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07003520 }
Hugh Dickins24513262012-01-20 14:34:21 -08003521
3522 if (zone) {
3523 __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
3524 __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
3525 spin_unlock_irq(&zone->lru_lock);
3526 }
Hugh Dickins850465792012-01-20 14:34:19 -08003527}
3528#endif /* CONFIG_SHMEM */
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003529
Johannes Weiner264e56d2011-10-31 17:09:13 -07003530static void warn_scan_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003531{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003532 printk_once(KERN_WARNING
KOSAKI Motohiro25bd91b2012-01-10 15:07:40 -08003533 "%s: The scan_unevictable_pages sysctl/node-interface has been "
Johannes Weiner264e56d2011-10-31 17:09:13 -07003534 "disabled for lack of a legitimate use case. If you have "
KOSAKI Motohiro25bd91b2012-01-10 15:07:40 -08003535 "one, please send an email to linux-mm@kvack.org.\n",
3536 current->comm);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003537}
3538
3539/*
3540 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
3541 * all nodes' unevictable lists for evictable pages
3542 */
3543unsigned long scan_unevictable_pages;
3544
3545int scan_unevictable_handler(struct ctl_table *table, int write,
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003546 void __user *buffer,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003547 size_t *length, loff_t *ppos)
3548{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003549 warn_scan_unevictable_pages();
Alexey Dobriyan8d65af72009-09-23 15:57:19 -07003550 proc_doulongvec_minmax(table, write, buffer, length, ppos);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003551 scan_unevictable_pages = 0;
3552 return 0;
3553}
3554
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003555#ifdef CONFIG_NUMA
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003556/*
3557 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
3558 * a specified node's per zone unevictable lists for evictable pages.
3559 */
3560
Kay Sievers10fbcf42011-12-21 14:48:43 -08003561static ssize_t read_scan_unevictable_node(struct device *dev,
3562 struct device_attribute *attr,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003563 char *buf)
3564{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003565 warn_scan_unevictable_pages();
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003566 return sprintf(buf, "0\n"); /* always zero; should fit... */
3567}
3568
Kay Sievers10fbcf42011-12-21 14:48:43 -08003569static ssize_t write_scan_unevictable_node(struct device *dev,
3570 struct device_attribute *attr,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003571 const char *buf, size_t count)
3572{
Johannes Weiner264e56d2011-10-31 17:09:13 -07003573 warn_scan_unevictable_pages();
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003574 return 1;
3575}
3576
3577
Kay Sievers10fbcf42011-12-21 14:48:43 -08003578static DEVICE_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003579 read_scan_unevictable_node,
3580 write_scan_unevictable_node);
3581
3582int scan_unevictable_register_node(struct node *node)
3583{
Kay Sievers10fbcf42011-12-21 14:48:43 -08003584 return device_create_file(&node->dev, &dev_attr_scan_unevictable_pages);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003585}
3586
3587void scan_unevictable_unregister_node(struct node *node)
3588{
Kay Sievers10fbcf42011-12-21 14:48:43 -08003589 device_remove_file(&node->dev, &dev_attr_scan_unevictable_pages);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07003590}
Thadeu Lima de Souza Cascardoe4455ab2010-10-26 14:21:28 -07003591#endif