blob: b2bc06bffcfb177697d9125e64763ba92560f985 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/vmscan.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
12 */
13
14#include <linux/mm.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/kernel_stat.h>
18#include <linux/swap.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/highmem.h>
Andrew Mortone129b5c2006-09-27 01:50:00 -070022#include <linux/vmstat.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/file.h>
24#include <linux/writeback.h>
25#include <linux/blkdev.h>
26#include <linux/buffer_head.h> /* for try_to_release_page(),
27 buffer_heads_over_limit */
28#include <linux/mm_inline.h>
29#include <linux/pagevec.h>
30#include <linux/backing-dev.h>
31#include <linux/rmap.h>
32#include <linux/topology.h>
33#include <linux/cpu.h>
34#include <linux/cpuset.h>
35#include <linux/notifier.h>
36#include <linux/rwsem.h>
Rafael J. Wysocki248a0302006-03-22 00:09:04 -080037#include <linux/delay.h>
Yasunori Goto3218ae12006-06-27 02:53:33 -070038#include <linux/kthread.h>
Nigel Cunningham7dfb7102006-12-06 20:34:23 -080039#include <linux/freezer.h>
Balbir Singh66e17072008-02-07 00:13:56 -080040#include <linux/memcontrol.h>
Keika Kobayashi873b4772008-07-25 01:48:52 -070041#include <linux/delayacct.h>
Lee Schermerhornaf936a12008-10-18 20:26:53 -070042#include <linux/sysctl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44#include <asm/tlbflush.h>
45#include <asm/div64.h>
46
47#include <linux/swapops.h>
48
Nick Piggin0f8053a2006-03-22 00:08:33 -080049#include "internal.h"
50
Linus Torvalds1da177e2005-04-16 15:20:36 -070051struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 /* Incremented by the number of inactive pages that were scanned */
53 unsigned long nr_scanned;
54
Rik van Riela79311c2009-01-06 14:40:01 -080055 /* Number of pages freed so far during a call to shrink_zones() */
56 unsigned long nr_reclaimed;
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040059 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61 int may_writepage;
62
Christoph Lameterf1fd1062006-01-18 17:42:30 -080063 /* Can pages be swapped as part of reclaim? */
64 int may_swap;
65
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 /* This context's SWAP_CLUSTER_MAX. If freeing memory for
67 * suspend, we effectively ignore SWAP_CLUSTER_MAX.
68 * In this context, it doesn't matter that we scan the
69 * whole list at once. */
70 int swap_cluster_max;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -070071
72 int swappiness;
Nick Piggin408d8542006-09-25 23:31:27 -070073
74 int all_unreclaimable;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070075
76 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080077
78 /* Which cgroup do we reclaim from */
79 struct mem_cgroup *mem_cgroup;
80
81 /* Pluggable isolate pages callback */
82 unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
83 unsigned long *scanned, int order, int mode,
84 struct zone *z, struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -070085 int active, int file);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086};
87
Linus Torvalds1da177e2005-04-16 15:20:36 -070088#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
89
90#ifdef ARCH_HAS_PREFETCH
91#define prefetch_prev_lru_page(_page, _base, _field) \
92 do { \
93 if ((_page)->lru.prev != _base) { \
94 struct page *prev; \
95 \
96 prev = lru_to_page(&(_page->lru)); \
97 prefetch(&prev->_field); \
98 } \
99 } while (0)
100#else
101#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
102#endif
103
104#ifdef ARCH_HAS_PREFETCHW
105#define prefetchw_prev_lru_page(_page, _base, _field) \
106 do { \
107 if ((_page)->lru.prev != _base) { \
108 struct page *prev; \
109 \
110 prev = lru_to_page(&(_page->lru)); \
111 prefetchw(&prev->_field); \
112 } \
113 } while (0)
114#else
115#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
116#endif
117
118/*
119 * From 0 .. 100. Higher means more swappy.
120 */
121int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700122long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
124static LIST_HEAD(shrinker_list);
125static DECLARE_RWSEM(shrinker_rwsem);
126
Balbir Singh00f0b822008-03-04 14:28:39 -0800127#ifdef CONFIG_CGROUP_MEM_RES_CTLR
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800128#define scan_global_lru(sc) (!(sc)->mem_cgroup)
129#else
130#define scan_global_lru(sc) (1)
131#endif
132
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800133static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
134 struct scan_control *sc)
135{
136 return &zone->reclaim_stat;
137}
138
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -0800139static unsigned long zone_nr_pages(struct zone *zone, struct scan_control *sc,
140 enum lru_list lru)
141{
142 return zone_page_state(zone, NR_LRU_BASE + lru);
143}
144
145
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146/*
147 * Add a shrinker callback to be called from the vm
148 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700149void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150{
Rusty Russell8e1f9362007-07-17 04:03:17 -0700151 shrinker->nr = 0;
152 down_write(&shrinker_rwsem);
153 list_add_tail(&shrinker->list, &shrinker_list);
154 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700156EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158/*
159 * Remove one
160 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700161void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
163 down_write(&shrinker_rwsem);
164 list_del(&shrinker->list);
165 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700167EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
169#define SHRINK_BATCH 128
170/*
171 * Call the shrink functions to age shrinkable caches
172 *
173 * Here we assume it costs one seek to replace a lru page and that it also
174 * takes a seek to recreate a cache object. With this in mind we age equal
175 * percentages of the lru and ageable caches. This should balance the seeks
176 * generated by these structures.
177 *
Simon Arlott183ff222007-10-20 01:27:18 +0200178 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 * slab to avoid swapping.
180 *
181 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
182 *
183 * `lru_pages' represents the number of on-LRU pages in all the zones which
184 * are eligible for the caller's allocation attempt. It is used for balancing
185 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700186 *
187 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 */
Andrew Morton69e05942006-03-22 00:08:19 -0800189unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
190 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191{
192 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800193 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194
195 if (scanned == 0)
196 scanned = SWAP_CLUSTER_MAX;
197
198 if (!down_read_trylock(&shrinker_rwsem))
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700199 return 1; /* Assume we'll be able to shrink next time */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
201 list_for_each_entry(shrinker, &shrinker_list, list) {
202 unsigned long long delta;
203 unsigned long total_scan;
Rusty Russell8e1f9362007-07-17 04:03:17 -0700204 unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205
206 delta = (4 * scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800207 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 do_div(delta, lru_pages + 1);
209 shrinker->nr += delta;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800210 if (shrinker->nr < 0) {
211 printk(KERN_ERR "%s: nr=%ld\n",
Harvey Harrisond40cee22008-04-30 00:55:07 -0700212 __func__, shrinker->nr);
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800213 shrinker->nr = max_pass;
214 }
215
216 /*
217 * Avoid risking looping forever due to too large nr value:
218 * never try to free more than twice the estimate number of
219 * freeable entries.
220 */
221 if (shrinker->nr > max_pass * 2)
222 shrinker->nr = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223
224 total_scan = shrinker->nr;
225 shrinker->nr = 0;
226
227 while (total_scan >= SHRINK_BATCH) {
228 long this_scan = SHRINK_BATCH;
229 int shrink_ret;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700230 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
Rusty Russell8e1f9362007-07-17 04:03:17 -0700232 nr_before = (*shrinker->shrink)(0, gfp_mask);
233 shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 if (shrink_ret == -1)
235 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700236 if (shrink_ret < nr_before)
237 ret += nr_before - shrink_ret;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700238 count_vm_events(SLABS_SCANNED, this_scan);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 total_scan -= this_scan;
240
241 cond_resched();
242 }
243
244 shrinker->nr += total_scan;
245 }
246 up_read(&shrinker_rwsem);
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700247 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248}
249
250/* Called without lock on whether page is mapped, so answer is unstable */
251static inline int page_mapping_inuse(struct page *page)
252{
253 struct address_space *mapping;
254
255 /* Page is in somebody's page tables. */
256 if (page_mapped(page))
257 return 1;
258
259 /* Be more reluctant to reclaim swapcache than pagecache */
260 if (PageSwapCache(page))
261 return 1;
262
263 mapping = page_mapping(page);
264 if (!mapping)
265 return 0;
266
267 /* File is mmap'd by somebody? */
268 return mapping_mapped(mapping);
269}
270
271static inline int is_page_cache_freeable(struct page *page)
272{
273 return page_count(page) - !!PagePrivate(page) == 2;
274}
275
276static int may_write_to_queue(struct backing_dev_info *bdi)
277{
Christoph Lameter930d9152006-01-08 01:00:47 -0800278 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 return 1;
280 if (!bdi_write_congested(bdi))
281 return 1;
282 if (bdi == current->backing_dev_info)
283 return 1;
284 return 0;
285}
286
287/*
288 * We detected a synchronous write error writing a page out. Probably
289 * -ENOSPC. We need to propagate that into the address_space for a subsequent
290 * fsync(), msync() or close().
291 *
292 * The tricky part is that after writepage we cannot touch the mapping: nothing
293 * prevents it from being freed up. But we have a ref on the page and once
294 * that page is locked, the mapping is pinned.
295 *
296 * We're allowed to run sleeping lock_page() here because we know the caller has
297 * __GFP_FS.
298 */
299static void handle_write_error(struct address_space *mapping,
300 struct page *page, int error)
301{
302 lock_page(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700303 if (page_mapping(page) == mapping)
304 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 unlock_page(page);
306}
307
Andy Whitcroftc661b072007-08-22 14:01:26 -0700308/* Request for sync pageout. */
309enum pageout_io {
310 PAGEOUT_IO_ASYNC,
311 PAGEOUT_IO_SYNC,
312};
313
Christoph Lameter04e62a22006-06-23 02:03:38 -0700314/* possible outcome of pageout() */
315typedef enum {
316 /* failed to write page out, page is locked */
317 PAGE_KEEP,
318 /* move page to the active list, page is locked */
319 PAGE_ACTIVATE,
320 /* page has been sent to the disk successfully, page is unlocked */
321 PAGE_SUCCESS,
322 /* page is clean and locked */
323 PAGE_CLEAN,
324} pageout_t;
325
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326/*
Andrew Morton1742f192006-03-22 00:08:21 -0800327 * pageout is called by shrink_page_list() for each dirty page.
328 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700330static pageout_t pageout(struct page *page, struct address_space *mapping,
331 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332{
333 /*
334 * If the page is dirty, only perform writeback if that write
335 * will be non-blocking. To prevent this allocation from being
336 * stalled by pagecache activity. But note that there may be
337 * stalls if we need to run get_block(). We could test
338 * PagePrivate for that.
339 *
340 * If this process is currently in generic_file_write() against
341 * this page's queue, we can perform writeback even if that
342 * will block.
343 *
344 * If the page is swapcache, write it back even if that would
345 * block, for some throttling. This happens by accident, because
346 * swap_backing_dev_info is bust: it doesn't reflect the
347 * congestion state of the swapdevs. Easy to fix, if needed.
348 * See swapfile.c:page_queue_congested().
349 */
350 if (!is_page_cache_freeable(page))
351 return PAGE_KEEP;
352 if (!mapping) {
353 /*
354 * Some data journaling orphaned pages can have
355 * page->mapping == NULL while being dirty with clean buffers.
356 */
akpm@osdl.org323aca62005-04-16 15:24:06 -0700357 if (PagePrivate(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 if (try_to_free_buffers(page)) {
359 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700360 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 return PAGE_CLEAN;
362 }
363 }
364 return PAGE_KEEP;
365 }
366 if (mapping->a_ops->writepage == NULL)
367 return PAGE_ACTIVATE;
368 if (!may_write_to_queue(mapping->backing_dev_info))
369 return PAGE_KEEP;
370
371 if (clear_page_dirty_for_io(page)) {
372 int res;
373 struct writeback_control wbc = {
374 .sync_mode = WB_SYNC_NONE,
375 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700376 .range_start = 0,
377 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 .nonblocking = 1,
379 .for_reclaim = 1,
380 };
381
382 SetPageReclaim(page);
383 res = mapping->a_ops->writepage(page, &wbc);
384 if (res < 0)
385 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800386 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 ClearPageReclaim(page);
388 return PAGE_ACTIVATE;
389 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700390
391 /*
392 * Wait on writeback if requested to. This happens when
393 * direct reclaiming a large contiguous area and the
394 * first attempt to free a range of pages fails.
395 */
396 if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
397 wait_on_page_writeback(page);
398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 if (!PageWriteback(page)) {
400 /* synchronous write or broken a_ops? */
401 ClearPageReclaim(page);
402 }
Andrew Mortone129b5c2006-09-27 01:50:00 -0700403 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 return PAGE_SUCCESS;
405 }
406
407 return PAGE_CLEAN;
408}
409
Andrew Mortona649fd92006-10-17 00:09:36 -0700410/*
Nick Piggine2867812008-07-25 19:45:30 -0700411 * Same as remove_mapping, but if the page is removed from the mapping, it
412 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700413 */
Nick Piggine2867812008-07-25 19:45:30 -0700414static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800415{
Nick Piggin28e4d962006-09-25 23:31:23 -0700416 BUG_ON(!PageLocked(page));
417 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800418
Nick Piggin19fd6232008-07-25 19:45:32 -0700419 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800420 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700421 * The non racy check for a busy page.
422 *
423 * Must be careful with the order of the tests. When someone has
424 * a ref to the page, it may be possible that they dirty it then
425 * drop the reference. So if PageDirty is tested before page_count
426 * here, then the following race may occur:
427 *
428 * get_user_pages(&page);
429 * [user mapping goes away]
430 * write_to(page);
431 * !PageDirty(page) [good]
432 * SetPageDirty(page);
433 * put_page(page);
434 * !page_count(page) [good, discard it]
435 *
436 * [oops, our write_to data is lost]
437 *
438 * Reversing the order of the tests ensures such a situation cannot
439 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
440 * load is not satisfied before that of page->_count.
441 *
442 * Note that if SetPageDirty is always performed via set_page_dirty,
443 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800444 */
Nick Piggine2867812008-07-25 19:45:30 -0700445 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800446 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700447 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
448 if (unlikely(PageDirty(page))) {
449 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800450 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700451 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800452
453 if (PageSwapCache(page)) {
454 swp_entry_t swap = { .val = page_private(page) };
455 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700456 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800457 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -0700458 } else {
459 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700460 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800461 }
462
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800463 return 1;
464
465cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700466 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800467 return 0;
468}
469
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470/*
Nick Piggine2867812008-07-25 19:45:30 -0700471 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
472 * someone else has a ref on the page, abort and return 0. If it was
473 * successfully detached, return 1. Assumes the caller has a single ref on
474 * this page.
475 */
476int remove_mapping(struct address_space *mapping, struct page *page)
477{
478 if (__remove_mapping(mapping, page)) {
479 /*
480 * Unfreezing the refcount with 1 rather than 2 effectively
481 * drops the pagecache ref for us without requiring another
482 * atomic operation.
483 */
484 page_unfreeze_refs(page, 1);
485 return 1;
486 }
487 return 0;
488}
489
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700490/**
491 * putback_lru_page - put previously isolated page onto appropriate LRU list
492 * @page: page to be put back to appropriate lru list
493 *
494 * Add previously isolated @page to appropriate LRU list.
495 * Page may still be unevictable for other reasons.
496 *
497 * lru_lock must not be held, interrupts must be enabled.
498 */
499#ifdef CONFIG_UNEVICTABLE_LRU
500void putback_lru_page(struct page *page)
501{
502 int lru;
503 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700504 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700505
506 VM_BUG_ON(PageLRU(page));
507
508redo:
509 ClearPageUnevictable(page);
510
511 if (page_evictable(page, NULL)) {
512 /*
513 * For evictable pages, we can use the cache.
514 * In event of a race, worst case is we end up with an
515 * unevictable page on [in]active list.
516 * We know how to handle that.
517 */
518 lru = active + page_is_file_cache(page);
519 lru_cache_add_lru(page, lru);
520 } else {
521 /*
522 * Put unevictable pages directly on zone's unevictable
523 * list.
524 */
525 lru = LRU_UNEVICTABLE;
526 add_page_to_unevictable_list(page);
527 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700528
529 /*
530 * page's status can change while we move it among lru. If an evictable
531 * page is on unevictable list, it never be freed. To avoid that,
532 * check after we added it to the list, again.
533 */
534 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
535 if (!isolate_lru_page(page)) {
536 put_page(page);
537 goto redo;
538 }
539 /* This means someone else dropped this page from LRU
540 * So, it will be freed or putback to LRU again. There is
541 * nothing to do here.
542 */
543 }
544
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700545 if (was_unevictable && lru != LRU_UNEVICTABLE)
546 count_vm_event(UNEVICTABLE_PGRESCUED);
547 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
548 count_vm_event(UNEVICTABLE_PGCULLED);
549
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700550 put_page(page); /* drop ref from isolate */
551}
552
553#else /* CONFIG_UNEVICTABLE_LRU */
554
555void putback_lru_page(struct page *page)
556{
557 int lru;
558 VM_BUG_ON(PageLRU(page));
559
560 lru = !!TestClearPageActive(page) + page_is_file_cache(page);
561 lru_cache_add_lru(page, lru);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700562 put_page(page);
563}
564#endif /* CONFIG_UNEVICTABLE_LRU */
565
566
Nick Piggine2867812008-07-25 19:45:30 -0700567/*
Andrew Morton1742f192006-03-22 00:08:21 -0800568 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 */
Andrew Morton1742f192006-03-22 00:08:21 -0800570static unsigned long shrink_page_list(struct list_head *page_list,
Andy Whitcroftc661b072007-08-22 14:01:26 -0700571 struct scan_control *sc,
572 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573{
574 LIST_HEAD(ret_pages);
575 struct pagevec freed_pvec;
576 int pgactivate = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800577 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
579 cond_resched();
580
581 pagevec_init(&freed_pvec, 1);
582 while (!list_empty(page_list)) {
583 struct address_space *mapping;
584 struct page *page;
585 int may_enter_fs;
586 int referenced;
587
588 cond_resched();
589
590 page = lru_to_page(page_list);
591 list_del(&page->lru);
592
Nick Piggin529ae9a2008-08-02 12:01:03 +0200593 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 goto keep;
595
Nick Piggin725d7042006-09-25 23:30:55 -0700596 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597
598 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800599
Nick Pigginb291f002008-10-18 20:26:44 -0700600 if (unlikely(!page_evictable(page, NULL)))
601 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700602
Christoph Lameter80e43422006-02-11 17:55:53 -0800603 if (!sc->may_swap && page_mapped(page))
604 goto keep_locked;
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 /* Double the slab pressure for mapped and swapcache pages */
607 if (page_mapped(page) || PageSwapCache(page))
608 sc->nr_scanned++;
609
Andy Whitcroftc661b072007-08-22 14:01:26 -0700610 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
611 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
612
613 if (PageWriteback(page)) {
614 /*
615 * Synchronous reclaim is performed in two passes,
616 * first an asynchronous pass over the list to
617 * start parallel writeback, and a second synchronous
618 * pass to wait for the IO to complete. Wait here
619 * for any page for which writeback has already
620 * started.
621 */
622 if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
623 wait_on_page_writeback(page);
Andrew Morton4dd4b922008-03-24 12:29:52 -0700624 else
Andy Whitcroftc661b072007-08-22 14:01:26 -0700625 goto keep_locked;
626 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
Balbir Singhbed71612008-02-07 00:14:01 -0800628 referenced = page_referenced(page, 1, sc->mem_cgroup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 /* In active use or really unfreeable? Activate it. */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700630 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
631 referenced && page_mapping_inuse(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 goto activate_locked;
633
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 /*
635 * Anonymous process memory has backing store?
636 * Try to allocate it some swap space here.
637 */
Nick Pigginb291f002008-10-18 20:26:44 -0700638 if (PageAnon(page) && !PageSwapCache(page)) {
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800639 if (!(sc->gfp_mask & __GFP_IO))
640 goto keep_locked;
Hugh Dickinsac47b002009-01-06 14:39:39 -0800641 if (!add_to_swap(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 goto activate_locked;
Hugh Dickins63eb6b92008-11-19 15:36:37 -0800643 may_enter_fs = 1;
Nick Pigginb291f002008-10-18 20:26:44 -0700644 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645
646 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647
648 /*
649 * The page is mapped into the page tables of one or more
650 * processes. Try to unmap it here.
651 */
652 if (page_mapped(page) && mapping) {
Christoph Lametera48d07a2006-02-01 03:05:38 -0800653 switch (try_to_unmap(page, 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 case SWAP_FAIL:
655 goto activate_locked;
656 case SWAP_AGAIN:
657 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700658 case SWAP_MLOCK:
659 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 case SWAP_SUCCESS:
661 ; /* try to free the page below */
662 }
663 }
664
665 if (PageDirty(page)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700666 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700668 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800670 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 goto keep_locked;
672
673 /* Page is dirty, try to write it out here */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700674 switch (pageout(page, mapping, sync_writeback)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 case PAGE_KEEP:
676 goto keep_locked;
677 case PAGE_ACTIVATE:
678 goto activate_locked;
679 case PAGE_SUCCESS:
Andrew Morton4dd4b922008-03-24 12:29:52 -0700680 if (PageWriteback(page) || PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 goto keep;
682 /*
683 * A synchronous write - probably a ramdisk. Go
684 * ahead and try to reclaim the page.
685 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200686 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 goto keep;
688 if (PageDirty(page) || PageWriteback(page))
689 goto keep_locked;
690 mapping = page_mapping(page);
691 case PAGE_CLEAN:
692 ; /* try to free the page below */
693 }
694 }
695
696 /*
697 * If the page has buffers, try to free the buffer mappings
698 * associated with this page. If we succeed we try to free
699 * the page as well.
700 *
701 * We do this even if the page is PageDirty().
702 * try_to_release_page() does not perform I/O, but it is
703 * possible for a page to have PageDirty set, but it is actually
704 * clean (all its buffers are clean). This happens if the
705 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700706 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 * try_to_release_page() will discover that cleanness and will
708 * drop the buffers and mark the page clean - it can be freed.
709 *
710 * Rarely, pages can have buffers and no ->mapping. These are
711 * the pages which were not successfully invalidated in
712 * truncate_complete_page(). We try to drop those buffers here
713 * and if that worked, and the page is no longer mapped into
714 * process address space (page_count == 1) it can be freed.
715 * Otherwise, leave the page on the LRU so it is swappable.
716 */
717 if (PagePrivate(page)) {
718 if (!try_to_release_page(page, sc->gfp_mask))
719 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700720 if (!mapping && page_count(page) == 1) {
721 unlock_page(page);
722 if (put_page_testzero(page))
723 goto free_it;
724 else {
725 /*
726 * rare race with speculative reference.
727 * the speculative reference will free
728 * this page shortly, so we may
729 * increment nr_reclaimed here (and
730 * leave it off the LRU).
731 */
732 nr_reclaimed++;
733 continue;
734 }
735 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 }
737
Nick Piggine2867812008-07-25 19:45:30 -0700738 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800739 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740
Nick Piggina978d6f2008-10-18 20:26:58 -0700741 /*
742 * At this point, we have no other references and there is
743 * no way to pick any more up (removed from LRU, removed
744 * from pagecache). Can use non-atomic bitops now (and
745 * we obviously don't have to worry about waking up a process
746 * waiting on the page lock, because there are no references.
747 */
748 __clear_page_locked(page);
Nick Piggine2867812008-07-25 19:45:30 -0700749free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800750 nr_reclaimed++;
Nick Piggine2867812008-07-25 19:45:30 -0700751 if (!pagevec_add(&freed_pvec, page)) {
752 __pagevec_free(&freed_pvec);
753 pagevec_reinit(&freed_pvec);
754 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 continue;
756
Nick Pigginb291f002008-10-18 20:26:44 -0700757cull_mlocked:
Hugh Dickins63d6c5a2009-01-06 14:39:38 -0800758 if (PageSwapCache(page))
759 try_to_free_swap(page);
Nick Pigginb291f002008-10-18 20:26:44 -0700760 unlock_page(page);
761 putback_lru_page(page);
762 continue;
763
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700765 /* Not a candidate for swapping, so reclaim swap space. */
766 if (PageSwapCache(page) && vm_swap_full())
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800767 try_to_free_swap(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700768 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 SetPageActive(page);
770 pgactivate++;
771keep_locked:
772 unlock_page(page);
773keep:
774 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700775 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 }
777 list_splice(&ret_pages, page_list);
778 if (pagevec_count(&freed_pvec))
Nick Piggine2867812008-07-25 19:45:30 -0700779 __pagevec_free(&freed_pvec);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700780 count_vm_events(PGACTIVATE, pgactivate);
Andrew Morton05ff5132006-03-22 00:08:20 -0800781 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782}
783
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700784/* LRU Isolation modes. */
785#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
786#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
787#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
788
789/*
790 * Attempt to remove the specified page from its LRU. Only take this page
791 * if it is of the appropriate PageActive status. Pages which are being
792 * freed elsewhere are also ignored.
793 *
794 * page: page to consider
795 * mode: one of the LRU isolation modes defined above
796 *
797 * returns 0 on success, -ve errno on failure.
798 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700799int __isolate_lru_page(struct page *page, int mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700800{
801 int ret = -EINVAL;
802
803 /* Only take pages on the LRU. */
804 if (!PageLRU(page))
805 return ret;
806
807 /*
808 * When checking the active state, we need to be sure we are
809 * dealing with comparible boolean values. Take the logical not
810 * of each.
811 */
812 if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
813 return ret;
814
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700815 if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file))
816 return ret;
817
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700818 /*
819 * When this function is being called for lumpy reclaim, we
820 * initially look into all LRU pages, active, inactive and
821 * unevictable; only give shrink_page_list evictable pages.
822 */
823 if (PageUnevictable(page))
824 return ret;
825
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700826 ret = -EBUSY;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800827
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700828 if (likely(get_page_unless_zero(page))) {
829 /*
830 * Be careful not to clear PageLRU until after we're
831 * sure the page is not being freed elsewhere -- the
832 * page release code relies on it.
833 */
834 ClearPageLRU(page);
835 ret = 0;
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -0800836 mem_cgroup_del_lru(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700837 }
838
839 return ret;
840}
841
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800842/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 * zone->lru_lock is heavily contended. Some of the functions that
844 * shrink the lists perform better by taking out a batch of pages
845 * and working on them outside the LRU lock.
846 *
847 * For pagecache intensive workloads, this function is the hottest
848 * spot in the kernel (apart from copy_*_user functions).
849 *
850 * Appropriate locks must be held before calling this function.
851 *
852 * @nr_to_scan: The number of pages to look through on the list.
853 * @src: The LRU list to pull pages off.
854 * @dst: The temp list to put pages on to.
855 * @scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700856 * @order: The caller's attempted allocation order
857 * @mode: One of the LRU isolation modes
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700858 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 *
860 * returns how many pages were moved onto *@dst.
861 */
Andrew Morton69e05942006-03-22 00:08:19 -0800862static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
863 struct list_head *src, struct list_head *dst,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700864 unsigned long *scanned, int order, int mode, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865{
Andrew Morton69e05942006-03-22 00:08:19 -0800866 unsigned long nr_taken = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800867 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800869 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700870 struct page *page;
871 unsigned long pfn;
872 unsigned long end_pfn;
873 unsigned long page_pfn;
874 int zone_id;
875
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 page = lru_to_page(src);
877 prefetchw_prev_lru_page(page, src, flags);
878
Nick Piggin725d7042006-09-25 23:30:55 -0700879 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800880
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700881 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700882 case 0:
883 list_move(&page->lru, dst);
Nick Piggin7c8ee9a2006-03-22 00:08:03 -0800884 nr_taken++;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700885 break;
Nick Piggin46453a62006-03-22 00:07:58 -0800886
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700887 case -EBUSY:
888 /* else it is being freed elsewhere */
889 list_move(&page->lru, src);
890 continue;
891
892 default:
893 BUG();
894 }
895
896 if (!order)
897 continue;
898
899 /*
900 * Attempt to take all pages in the order aligned region
901 * surrounding the tag page. Only take those pages of
902 * the same active state as that tag page. We may safely
903 * round the target page pfn down to the requested order
904 * as the mem_map is guarenteed valid out to MAX_ORDER,
905 * where that page is in a different zone we will detect
906 * it from its zone id and abort this block scan.
907 */
908 zone_id = page_zone_id(page);
909 page_pfn = page_to_pfn(page);
910 pfn = page_pfn & ~((1 << order) - 1);
911 end_pfn = pfn + (1 << order);
912 for (; pfn < end_pfn; pfn++) {
913 struct page *cursor_page;
914
915 /* The target page is in the block, ignore it. */
916 if (unlikely(pfn == page_pfn))
917 continue;
918
919 /* Avoid holes within the zone. */
920 if (unlikely(!pfn_valid_within(pfn)))
921 break;
922
923 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700924
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700925 /* Check that we have not crossed a zone boundary. */
926 if (unlikely(page_zone_id(cursor_page) != zone_id))
927 continue;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700928 switch (__isolate_lru_page(cursor_page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700929 case 0:
930 list_move(&cursor_page->lru, dst);
931 nr_taken++;
932 scan++;
933 break;
934
935 case -EBUSY:
936 /* else it is being freed elsewhere */
937 list_move(&cursor_page->lru, src);
938 default:
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700939 break; /* ! on LRU or wrong list */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700940 }
941 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 }
943
944 *scanned = scan;
945 return nr_taken;
946}
947
Balbir Singh66e17072008-02-07 00:13:56 -0800948static unsigned long isolate_pages_global(unsigned long nr,
949 struct list_head *dst,
950 unsigned long *scanned, int order,
951 int mode, struct zone *z,
952 struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700953 int active, int file)
Balbir Singh66e17072008-02-07 00:13:56 -0800954{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700955 int lru = LRU_BASE;
Balbir Singh66e17072008-02-07 00:13:56 -0800956 if (active)
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700957 lru += LRU_ACTIVE;
958 if (file)
959 lru += LRU_FILE;
960 return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
961 mode, !!file);
Balbir Singh66e17072008-02-07 00:13:56 -0800962}
963
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964/*
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700965 * clear_active_flags() is a helper for shrink_active_list(), clearing
966 * any active bits from the pages in the list.
967 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700968static unsigned long clear_active_flags(struct list_head *page_list,
969 unsigned int *count)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700970{
971 int nr_active = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700972 int lru;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700973 struct page *page;
974
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700975 list_for_each_entry(page, page_list, lru) {
976 lru = page_is_file_cache(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700977 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700978 lru += LRU_ACTIVE;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700979 ClearPageActive(page);
980 nr_active++;
981 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700982 count[lru]++;
983 }
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700984
985 return nr_active;
986}
987
Nick Piggin62695a82008-10-18 20:26:09 -0700988/**
989 * isolate_lru_page - tries to isolate a page from its LRU list
990 * @page: page to isolate from its LRU list
991 *
992 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
993 * vmstat statistic corresponding to whatever LRU list the page was on.
994 *
995 * Returns 0 if the page was removed from an LRU list.
996 * Returns -EBUSY if the page was not on an LRU list.
997 *
998 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700999 * the active list, it will have PageActive set. If it was found on
1000 * the unevictable list, it will have the PageUnevictable bit set. That flag
1001 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -07001002 *
1003 * The vmstat statistic corresponding to the list on which the page was
1004 * found will be decremented.
1005 *
1006 * Restrictions:
1007 * (1) Must be called with an elevated refcount on the page. This is a
1008 * fundamentnal difference from isolate_lru_pages (which is called
1009 * without a stable reference).
1010 * (2) the lru_lock must not be held.
1011 * (3) interrupts must be enabled.
1012 */
1013int isolate_lru_page(struct page *page)
1014{
1015 int ret = -EBUSY;
1016
1017 if (PageLRU(page)) {
1018 struct zone *zone = page_zone(page);
1019
1020 spin_lock_irq(&zone->lru_lock);
1021 if (PageLRU(page) && get_page_unless_zero(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001022 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001023 ret = 0;
1024 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001025
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001026 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001027 }
1028 spin_unlock_irq(&zone->lru_lock);
1029 }
1030 return ret;
1031}
1032
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001033/*
Andrew Morton1742f192006-03-22 00:08:21 -08001034 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1035 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 */
Andrew Morton1742f192006-03-22 00:08:21 -08001037static unsigned long shrink_inactive_list(unsigned long max_scan,
Rik van Riel33c120e2008-10-18 20:26:36 -07001038 struct zone *zone, struct scan_control *sc,
1039 int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040{
1041 LIST_HEAD(page_list);
1042 struct pagevec pvec;
Andrew Morton69e05942006-03-22 00:08:19 -08001043 unsigned long nr_scanned = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -08001044 unsigned long nr_reclaimed = 0;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001045 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046
1047 pagevec_init(&pvec, 1);
1048
1049 lru_add_drain();
1050 spin_lock_irq(&zone->lru_lock);
Andrew Morton69e05942006-03-22 00:08:19 -08001051 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 struct page *page;
Andrew Morton69e05942006-03-22 00:08:19 -08001053 unsigned long nr_taken;
1054 unsigned long nr_scan;
1055 unsigned long nr_freed;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001056 unsigned long nr_active;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001057 unsigned int count[NR_LRU_LISTS] = { 0, };
Rik van Riel33c120e2008-10-18 20:26:36 -07001058 int mode = ISOLATE_INACTIVE;
1059
1060 /*
1061 * If we need a large contiguous chunk of memory, or have
1062 * trouble getting a small set of contiguous pages, we
1063 * will reclaim both active and inactive pages.
1064 *
1065 * We use the same threshold as pageout congestion_wait below.
1066 */
1067 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1068 mode = ISOLATE_BOTH;
1069 else if (sc->order && priority < DEF_PRIORITY - 2)
1070 mode = ISOLATE_BOTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071
Balbir Singh66e17072008-02-07 00:13:56 -08001072 nr_taken = sc->isolate_pages(sc->swap_cluster_max,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001073 &page_list, &nr_scan, sc->order, mode,
1074 zone, sc->mem_cgroup, 0, file);
1075 nr_active = clear_active_flags(&page_list, count);
Andy Whitcrofte9187bd2007-08-22 14:01:25 -07001076 __count_vm_events(PGDEACTIVATE, nr_active);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001077
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001078 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1079 -count[LRU_ACTIVE_FILE]);
1080 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1081 -count[LRU_INACTIVE_FILE]);
1082 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1083 -count[LRU_ACTIVE_ANON]);
1084 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1085 -count[LRU_INACTIVE_ANON]);
1086
1087 if (scan_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001088 zone->pages_scanned += nr_scan;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001089 reclaim_stat->recent_scanned[0] +=
1090 count[LRU_INACTIVE_ANON];
1091 reclaim_stat->recent_scanned[0] +=
1092 count[LRU_ACTIVE_ANON];
1093 reclaim_stat->recent_scanned[1] +=
1094 count[LRU_INACTIVE_FILE];
1095 reclaim_stat->recent_scanned[1] +=
1096 count[LRU_ACTIVE_FILE];
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001097 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 spin_unlock_irq(&zone->lru_lock);
1099
Andrew Morton69e05942006-03-22 00:08:19 -08001100 nr_scanned += nr_scan;
Andy Whitcroftc661b072007-08-22 14:01:26 -07001101 nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
1102
1103 /*
1104 * If we are direct reclaiming for contiguous pages and we do
1105 * not reclaim everything in the list, try again and wait
1106 * for IO to complete. This will stall high-order allocations
1107 * but that should be acceptable to the caller
1108 */
1109 if (nr_freed < nr_taken && !current_is_kswapd() &&
1110 sc->order > PAGE_ALLOC_COSTLY_ORDER) {
1111 congestion_wait(WRITE, HZ/10);
1112
1113 /*
1114 * The attempt at page out may have made some
1115 * of the pages active, mark them inactive again.
1116 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001117 nr_active = clear_active_flags(&page_list, count);
Andy Whitcroftc661b072007-08-22 14:01:26 -07001118 count_vm_events(PGDEACTIVATE, nr_active);
1119
1120 nr_freed += shrink_page_list(&page_list, sc,
1121 PAGEOUT_IO_SYNC);
1122 }
1123
Andrew Morton05ff5132006-03-22 00:08:20 -08001124 nr_reclaimed += nr_freed;
Nick Piggina74609f2006-01-06 00:11:20 -08001125 local_irq_disable();
1126 if (current_is_kswapd()) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001127 __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);
1128 __count_vm_events(KSWAPD_STEAL, nr_freed);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001129 } else if (scan_global_lru(sc))
Christoph Lameterf8891e52006-06-30 01:55:45 -07001130 __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001131
Shantanu Goel918d3f92006-12-29 16:48:59 -08001132 __count_zone_vm_events(PGSTEAL, zone, nr_freed);
Nick Piggina74609f2006-01-06 00:11:20 -08001133
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001134 if (nr_taken == 0)
1135 goto done;
1136
Nick Piggina74609f2006-01-06 00:11:20 -08001137 spin_lock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 /*
1139 * Put back any unfreeable pages.
1140 */
1141 while (!list_empty(&page_list)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001142 int lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 page = lru_to_page(&page_list);
Nick Piggin725d7042006-09-25 23:30:55 -07001144 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 list_del(&page->lru);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001146 if (unlikely(!page_evictable(page, NULL))) {
1147 spin_unlock_irq(&zone->lru_lock);
1148 putback_lru_page(page);
1149 spin_lock_irq(&zone->lru_lock);
1150 continue;
1151 }
1152 SetPageLRU(page);
1153 lru = page_lru(page);
1154 add_page_to_lru_list(zone, page, lru);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001155 if (PageActive(page) && scan_global_lru(sc)) {
1156 int file = !!page_is_file_cache(page);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001157 reclaim_stat->recent_rotated[file]++;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 if (!pagevec_add(&pvec, page)) {
1160 spin_unlock_irq(&zone->lru_lock);
1161 __pagevec_release(&pvec);
1162 spin_lock_irq(&zone->lru_lock);
1163 }
1164 }
Andrew Morton69e05942006-03-22 00:08:19 -08001165 } while (nr_scanned < max_scan);
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001166 spin_unlock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167done:
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001168 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 pagevec_release(&pvec);
Andrew Morton05ff5132006-03-22 00:08:20 -08001170 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171}
1172
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001173/*
1174 * We are about to scan this zone at a certain priority level. If that priority
1175 * level is smaller (ie: more urgent) than the previous priority, then note
1176 * that priority level within the zone. This is done so that when the next
1177 * process comes in to scan this zone, it will immediately start out at this
1178 * priority level rather than having to build up its own scanning priority.
1179 * Here, this priority affects only the reclaim-mapped threshold.
1180 */
1181static inline void note_zone_scanning_priority(struct zone *zone, int priority)
1182{
1183 if (priority < zone->prev_priority)
1184 zone->prev_priority = priority;
1185}
1186
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001187/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 * This moves pages from the active list to the inactive list.
1189 *
1190 * We move them the other way if the page is referenced by one or more
1191 * processes, from rmap.
1192 *
1193 * If the pages are mostly unmapped, the processing is fast and it is
1194 * appropriate to hold zone->lru_lock across the whole operation. But if
1195 * the pages are mapped, the processing is slow (page_referenced()) so we
1196 * should drop zone->lru_lock around each page. It's impossible to balance
1197 * this, so instead we remove the pages from the LRU while processing them.
1198 * It is safe to rely on PG_active against the non-LRU pages in here because
1199 * nobody will play with that bit on a non-LRU page.
1200 *
1201 * The downside is that we have to touch page->_count against each page.
1202 * But we had to alter page->flags anyway.
1203 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001204
1205
Andrew Morton1742f192006-03-22 00:08:21 -08001206static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001207 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208{
Andrew Morton69e05942006-03-22 00:08:19 -08001209 unsigned long pgmoved;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 int pgdeactivate = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001211 unsigned long pgscanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 LIST_HEAD(l_hold); /* The pages which were snipped off */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001213 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 struct page *page;
1215 struct pagevec pvec;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001216 enum lru_list lru;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001217 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218
1219 lru_add_drain();
1220 spin_lock_irq(&zone->lru_lock);
Balbir Singh66e17072008-02-07 00:13:56 -08001221 pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
1222 ISOLATE_ACTIVE, zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001223 sc->mem_cgroup, 1, file);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001224 /*
1225 * zone->pages_scanned is used for detect zone's oom
1226 * mem_cgroup remembers nr_scan by itself.
1227 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001228 if (scan_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001229 zone->pages_scanned += pgscanned;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001230 reclaim_stat->recent_scanned[!!file] += pgmoved;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001231 }
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001232
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001233 if (file)
1234 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
1235 else
1236 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 spin_unlock_irq(&zone->lru_lock);
1238
Rik van Riel556adec2008-10-18 20:26:34 -07001239 pgmoved = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240 while (!list_empty(&l_hold)) {
1241 cond_resched();
1242 page = lru_to_page(&l_hold);
1243 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001244
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001245 if (unlikely(!page_evictable(page, NULL))) {
1246 putback_lru_page(page);
1247 continue;
1248 }
1249
Rik van Riel7e9cd482008-10-18 20:26:35 -07001250 /* page_referenced clears PageReferenced */
1251 if (page_mapping_inuse(page) &&
1252 page_referenced(page, 0, sc->mem_cgroup))
1253 pgmoved++;
1254
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 list_add(&page->lru, &l_inactive);
1256 }
1257
Andrew Mortonb5557492009-01-06 14:40:13 -08001258 /*
1259 * Move the pages to the [file or anon] inactive list.
1260 */
1261 pagevec_init(&pvec, 1);
1262 pgmoved = 0;
1263 lru = LRU_BASE + file * LRU_FILE;
1264
Johannes Weiner2a1dc502008-12-01 03:00:35 +01001265 spin_lock_irq(&zone->lru_lock);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001266 /*
Rik van Riel7e9cd482008-10-18 20:26:35 -07001267 * Count referenced pages from currently used mappings as
1268 * rotated, even though they are moved to the inactive list.
1269 * This helps balance scan pressure between file and anonymous
1270 * pages in get_scan_ratio.
1271 */
KOSAKI Motohiro077cbc52009-01-06 14:39:42 -08001272 if (scan_global_lru(sc))
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001273 reclaim_stat->recent_rotated[!!file] += pgmoved;
Rik van Riel556adec2008-10-18 20:26:34 -07001274
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275 while (!list_empty(&l_inactive)) {
1276 page = lru_to_page(&l_inactive);
1277 prefetchw_prev_lru_page(page, &l_inactive, flags);
Nick Piggin725d7042006-09-25 23:30:55 -07001278 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001279 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -07001280 VM_BUG_ON(!PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -08001281 ClearPageActive(page);
1282
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001283 list_move(&page->lru, &zone->lru[lru].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08001284 mem_cgroup_add_lru_list(page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 pgmoved++;
1286 if (!pagevec_add(&pvec, page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001287 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 spin_unlock_irq(&zone->lru_lock);
1289 pgdeactivate += pgmoved;
1290 pgmoved = 0;
1291 if (buffer_heads_over_limit)
1292 pagevec_strip(&pvec);
1293 __pagevec_release(&pvec);
1294 spin_lock_irq(&zone->lru_lock);
1295 }
1296 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001297 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 pgdeactivate += pgmoved;
1299 if (buffer_heads_over_limit) {
1300 spin_unlock_irq(&zone->lru_lock);
1301 pagevec_strip(&pvec);
1302 spin_lock_irq(&zone->lru_lock);
1303 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001304 __count_zone_vm_events(PGREFILL, zone, pgscanned);
1305 __count_vm_events(PGDEACTIVATE, pgdeactivate);
1306 spin_unlock_irq(&zone->lru_lock);
Rik van Riel68a223942008-10-18 20:26:23 -07001307 if (vm_swap_full())
1308 pagevec_swap_free(&pvec);
Nick Piggina74609f2006-01-06 00:11:20 -08001309
1310 pagevec_release(&pvec);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311}
1312
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001313static int inactive_anon_is_low_global(struct zone *zone)
KOSAKI Motohirof89eb902009-01-07 18:08:14 -08001314{
1315 unsigned long active, inactive;
1316
1317 active = zone_page_state(zone, NR_ACTIVE_ANON);
1318 inactive = zone_page_state(zone, NR_INACTIVE_ANON);
1319
1320 if (inactive * zone->inactive_ratio < active)
1321 return 1;
1322
1323 return 0;
1324}
1325
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001326/**
1327 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1328 * @zone: zone to check
1329 * @sc: scan control of this context
1330 *
1331 * Returns true if the zone does not have enough inactive anon pages,
1332 * meaning some active anon pages need to be deactivated.
1333 */
1334static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc)
1335{
1336 int low;
1337
1338 if (scan_global_lru(sc))
1339 low = inactive_anon_is_low_global(zone);
1340 else
1341 low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup, zone);
1342 return low;
1343}
1344
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001345static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Christoph Lameterb69408e2008-10-18 20:26:14 -07001346 struct zone *zone, struct scan_control *sc, int priority)
1347{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001348 int file = is_file_lru(lru);
1349
Rik van Riel556adec2008-10-18 20:26:34 -07001350 if (lru == LRU_ACTIVE_FILE) {
1351 shrink_active_list(nr_to_scan, zone, sc, priority, file);
1352 return 0;
1353 }
1354
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001355 if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001356 shrink_active_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001357 return 0;
1358 }
Rik van Riel33c120e2008-10-18 20:26:36 -07001359 return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001360}
1361
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001363 * Determine how aggressively the anon and file LRU lists should be
1364 * scanned. The relative value of each set of LRU lists is determined
1365 * by looking at the fraction of the pages scanned we did rotate back
1366 * onto the active list instead of evict.
1367 *
1368 * percent[0] specifies how much pressure to put on ram/swap backed
1369 * memory, while percent[1] determines pressure on the file LRUs.
1370 */
1371static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
1372 unsigned long *percent)
1373{
1374 unsigned long anon, file, free;
1375 unsigned long anon_prio, file_prio;
1376 unsigned long ap, fp;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001377 struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001378
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001379 /* If we have no swap space, do not bother scanning anon pages. */
1380 if (nr_swap_pages <= 0) {
1381 percent[0] = 0;
1382 percent[1] = 100;
1383 return;
1384 }
1385
KOSAKI Motohiroc9f299d2009-01-07 18:08:16 -08001386 anon = zone_nr_pages(zone, sc, LRU_ACTIVE_ANON) +
1387 zone_nr_pages(zone, sc, LRU_INACTIVE_ANON);
1388 file = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) +
1389 zone_nr_pages(zone, sc, LRU_INACTIVE_FILE);
Hugh Dickinsb9627162009-01-06 14:39:41 -08001390
KOSAKI Motohiroeeee9a82009-01-07 18:08:17 -08001391 if (scan_global_lru(sc)) {
1392 free = zone_page_state(zone, NR_FREE_PAGES);
1393 /* If we have very few page cache pages,
1394 force-scan anon pages. */
1395 if (unlikely(file + free <= zone->pages_high)) {
1396 percent[0] = 100;
1397 percent[1] = 0;
1398 return;
1399 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001400 }
1401
1402 /*
1403 * OK, so we have swap space and a fair amount of page cache
1404 * pages. We use the recently rotated / recently scanned
1405 * ratios to determine how valuable each cache is.
1406 *
1407 * Because workloads change over time (and to avoid overflow)
1408 * we keep these statistics as a floating average, which ends
1409 * up weighing recent references more than old ones.
1410 *
1411 * anon in [0], file in [1]
1412 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001413 if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001414 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001415 reclaim_stat->recent_scanned[0] /= 2;
1416 reclaim_stat->recent_rotated[0] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001417 spin_unlock_irq(&zone->lru_lock);
1418 }
1419
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001420 if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001421 spin_lock_irq(&zone->lru_lock);
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001422 reclaim_stat->recent_scanned[1] /= 2;
1423 reclaim_stat->recent_rotated[1] /= 2;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001424 spin_unlock_irq(&zone->lru_lock);
1425 }
1426
1427 /*
1428 * With swappiness at 100, anonymous and file have the same priority.
1429 * This scanning priority is essentially the inverse of IO cost.
1430 */
1431 anon_prio = sc->swappiness;
1432 file_prio = 200 - sc->swappiness;
1433
1434 /*
Rik van Riel00d80892008-11-19 15:36:44 -08001435 * The amount of pressure on anon vs file pages is inversely
1436 * proportional to the fraction of recently scanned pages on
1437 * each list that were recently referenced and in active use.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001438 */
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001439 ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
1440 ap /= reclaim_stat->recent_rotated[0] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001441
KOSAKI Motohiro6e901572009-01-07 18:08:15 -08001442 fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
1443 fp /= reclaim_stat->recent_rotated[1] + 1;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001444
1445 /* Normalize to percentages */
1446 percent[0] = 100 * ap / (ap + fp + 1);
1447 percent[1] = 100 - percent[0];
1448}
1449
1450
1451/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1453 */
Rik van Riela79311c2009-01-06 14:40:01 -08001454static void shrink_zone(int priority, struct zone *zone,
Andrew Morton05ff5132006-03-22 00:08:20 -08001455 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456{
Christoph Lameterb69408e2008-10-18 20:26:14 -07001457 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08001458 unsigned long nr_to_scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001459 unsigned long percent[2]; /* anon @ 0; file @ 1 */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001460 enum lru_list l;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001461 unsigned long nr_reclaimed = sc->nr_reclaimed;
1462 unsigned long swap_cluster_max = sc->swap_cluster_max;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001464 get_scan_ratio(zone, sc, percent);
1465
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001466 for_each_evictable_lru(l) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001467 if (scan_global_lru(sc)) {
1468 int file = is_file_lru(l);
1469 int scan;
Johannes Weinere0f79b82008-10-18 20:26:55 -07001470
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001471 scan = zone_page_state(zone, NR_LRU_BASE + l);
1472 if (priority) {
1473 scan >>= priority;
1474 scan = (scan * percent[file]) / 100;
1475 }
Johannes Weinere0f79b82008-10-18 20:26:55 -07001476 zone->lru[l].nr_scan += scan;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001477 nr[l] = zone->lru[l].nr_scan;
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001478 if (nr[l] >= swap_cluster_max)
Christoph Lameterb69408e2008-10-18 20:26:14 -07001479 zone->lru[l].nr_scan = 0;
1480 else
1481 nr[l] = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001482 } else {
1483 /*
1484 * This reclaim occurs not because zone memory shortage
1485 * but because memory controller hits its limit.
1486 * Don't modify zone reclaim related data.
1487 */
1488 nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone,
1489 priority, l);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001490 }
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001491 }
1492
Rik van Riel556adec2008-10-18 20:26:34 -07001493 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1494 nr[LRU_INACTIVE_FILE]) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001495 for_each_evictable_lru(l) {
Christoph Lameterb69408e2008-10-18 20:26:14 -07001496 if (nr[l]) {
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001497 nr_to_scan = min(nr[l], swap_cluster_max);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001498 nr[l] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001500 nr_reclaimed += shrink_list(l, nr_to_scan,
1501 zone, sc, priority);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001502 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 }
Rik van Riela79311c2009-01-06 14:40:01 -08001504 /*
1505 * On large memory systems, scan >> priority can become
1506 * really large. This is fine for the starting priority;
1507 * we want to put equal scanning pressure on each zone.
1508 * However, if the VM has a harder time of freeing pages,
1509 * with multiple processes reclaiming pages, the total
1510 * freeing target can get unreasonably large.
1511 */
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001512 if (nr_reclaimed > swap_cluster_max &&
Rik van Riela79311c2009-01-06 14:40:01 -08001513 priority < DEF_PRIORITY && !current_is_kswapd())
1514 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 }
1516
KOSAKI Motohiro01dbe5c2009-01-06 14:40:02 -08001517 sc->nr_reclaimed = nr_reclaimed;
1518
Rik van Riel556adec2008-10-18 20:26:34 -07001519 /*
1520 * Even if we did not try to evict anon pages at all, we want to
1521 * rebalance the anon lru active/inactive ratio.
1522 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001523 if (inactive_anon_is_low(zone, sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001524 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1525
Andrew Morton232ea4d2007-02-28 20:13:21 -08001526 throttle_vm_writeout(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527}
1528
1529/*
1530 * This is the direct reclaim path, for page-allocating processes. We only
1531 * try to reclaim pages from zones which will satisfy the caller's allocation
1532 * request.
1533 *
1534 * We reclaim from a zone even if that zone is over pages_high. Because:
1535 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
1536 * allocation or
1537 * b) The zones may be over pages_high but they must go *over* pages_high to
1538 * satisfy the `incremental min' zone defense algorithm.
1539 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 * If a zone is deemed to be full of pinned pages then just give it a light
1541 * scan then give up on it.
1542 */
Rik van Riela79311c2009-01-06 14:40:01 -08001543static void shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08001544 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545{
Mel Gorman54a6eb52008-04-28 02:12:16 -07001546 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Mel Gormandd1a2392008-04-28 02:12:17 -07001547 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001548 struct zone *zone;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001549
Nick Piggin408d8542006-09-25 23:31:27 -07001550 sc->all_unreclaimable = 1;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001551 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08001552 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001554 /*
1555 * Take care memory controller reclaiming has small influence
1556 * to global LRU.
1557 */
1558 if (scan_global_lru(sc)) {
1559 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1560 continue;
1561 note_zone_scanning_priority(zone, priority);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001563 if (zone_is_all_unreclaimable(zone) &&
1564 priority != DEF_PRIORITY)
1565 continue; /* Let kswapd poll it */
1566 sc->all_unreclaimable = 0;
1567 } else {
1568 /*
1569 * Ignore cpuset limitation here. We just want to reduce
1570 * # of used pages by us regardless of memory shortage.
1571 */
1572 sc->all_unreclaimable = 0;
1573 mem_cgroup_note_reclaim_priority(sc->mem_cgroup,
1574 priority);
1575 }
Nick Piggin408d8542006-09-25 23:31:27 -07001576
Rik van Riela79311c2009-01-06 14:40:01 -08001577 shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 }
1579}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001580
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581/*
1582 * This is the main entry point to direct page reclaim.
1583 *
1584 * If a full scan of the inactive list fails to free enough memory then we
1585 * are "out of memory" and something needs to be killed.
1586 *
1587 * If the caller is !__GFP_FS then the probability of a failure is reasonably
1588 * high - the zone may be full of dirty or under-writeback pages, which this
1589 * caller can't do much about. We kick pdflush and take explicit naps in the
1590 * hope that some of these pages can be written. But if the allocating task
1591 * holds filesystem locks which prevent writeout this might not work, and the
1592 * allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07001593 *
1594 * returns: 0, if no pages reclaimed
1595 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 */
Mel Gormandac1d272008-04-28 02:12:12 -07001597static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Mel Gormandd1a2392008-04-28 02:12:17 -07001598 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599{
1600 int priority;
kosaki.motohiro@jp.fujitsu.comc700be32008-06-12 15:21:27 -07001601 unsigned long ret = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001602 unsigned long total_scanned = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 struct reclaim_state *reclaim_state = current->reclaim_state;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 unsigned long lru_pages = 0;
Mel Gormandd1a2392008-04-28 02:12:17 -07001605 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001606 struct zone *zone;
Mel Gormandd1a2392008-04-28 02:12:17 -07001607 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
Keika Kobayashi873b4772008-07-25 01:48:52 -07001609 delayacct_freepages_start();
1610
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001611 if (scan_global_lru(sc))
1612 count_vm_event(ALLOCSTALL);
1613 /*
1614 * mem_cgroup will not do shrink_slab.
1615 */
1616 if (scan_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001617 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001619 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1620 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001622 lru_pages += zone_lru_pages(zone);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001623 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 }
1625
1626 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08001627 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001628 if (!priority)
1629 disable_swap_token();
Rik van Riela79311c2009-01-06 14:40:01 -08001630 shrink_zones(priority, zonelist, sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001631 /*
1632 * Don't shrink slabs when reclaiming memory from
1633 * over limit cgroups
1634 */
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001635 if (scan_global_lru(sc)) {
Mel Gormandd1a2392008-04-28 02:12:17 -07001636 shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001637 if (reclaim_state) {
Rik van Riela79311c2009-01-06 14:40:01 -08001638 sc->nr_reclaimed += reclaim_state->reclaimed_slab;
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001639 reclaim_state->reclaimed_slab = 0;
1640 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 }
Balbir Singh66e17072008-02-07 00:13:56 -08001642 total_scanned += sc->nr_scanned;
Rik van Riela79311c2009-01-06 14:40:01 -08001643 if (sc->nr_reclaimed >= sc->swap_cluster_max) {
1644 ret = sc->nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 goto out;
1646 }
1647
1648 /*
1649 * Try to write back as many pages as we just scanned. This
1650 * tends to cause slow streaming writers to write data to the
1651 * disk smoothly, at the dirtying rate, which is nice. But
1652 * that's undesirable in laptop mode, where we *want* lumpy
1653 * writeout. So in laptop mode, write out the whole world.
1654 */
Balbir Singh66e17072008-02-07 00:13:56 -08001655 if (total_scanned > sc->swap_cluster_max +
1656 sc->swap_cluster_max / 2) {
Pekka J Enberg687a21c2005-06-28 20:44:55 -07001657 wakeup_pdflush(laptop_mode ? 0 : total_scanned);
Balbir Singh66e17072008-02-07 00:13:56 -08001658 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 }
1660
1661 /* Take a nap, wait for some writeback to complete */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001662 if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001663 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 }
Fernando Luis Vazquez Cao87547ee2008-07-29 22:33:42 -07001665 /* top priority shrink_zones still had more to do? don't OOM, then */
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001666 if (!sc->all_unreclaimable && scan_global_lru(sc))
Rik van Riela79311c2009-01-06 14:40:01 -08001667 ret = sc->nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668out:
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001669 /*
1670 * Now that we've scanned all the zones at this priority level, note
1671 * that level within the zone so that the next thread which performs
1672 * scanning of this zone will immediately start out at this priority
1673 * level. This affects only the decision whether or not to bring
1674 * mapped pages onto the inactive list.
1675 */
1676 if (priority < 0)
1677 priority = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001679 if (scan_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001680 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001682 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1683 continue;
1684
1685 zone->prev_priority = priority;
1686 }
1687 } else
1688 mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority);
1689
Keika Kobayashi873b4772008-07-25 01:48:52 -07001690 delayacct_freepages_end();
1691
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 return ret;
1693}
1694
Mel Gormandac1d272008-04-28 02:12:12 -07001695unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
1696 gfp_t gfp_mask)
Balbir Singh66e17072008-02-07 00:13:56 -08001697{
1698 struct scan_control sc = {
1699 .gfp_mask = gfp_mask,
1700 .may_writepage = !laptop_mode,
1701 .swap_cluster_max = SWAP_CLUSTER_MAX,
1702 .may_swap = 1,
1703 .swappiness = vm_swappiness,
1704 .order = order,
1705 .mem_cgroup = NULL,
1706 .isolate_pages = isolate_pages_global,
1707 };
1708
Mel Gormandd1a2392008-04-28 02:12:17 -07001709 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001710}
1711
Balbir Singh00f0b822008-03-04 14:28:39 -08001712#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08001713
Balbir Singhe1a1cd52008-02-07 00:14:02 -08001714unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
KAMEZAWA Hiroyuki8c7c6e342009-01-07 18:08:00 -08001715 gfp_t gfp_mask,
1716 bool noswap)
Balbir Singh66e17072008-02-07 00:13:56 -08001717{
1718 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08001719 .may_writepage = !laptop_mode,
1720 .may_swap = 1,
1721 .swap_cluster_max = SWAP_CLUSTER_MAX,
1722 .swappiness = vm_swappiness,
1723 .order = 0,
1724 .mem_cgroup = mem_cont,
1725 .isolate_pages = mem_cgroup_isolate_pages,
1726 };
Mel Gormandac1d272008-04-28 02:12:12 -07001727 struct zonelist *zonelist;
Balbir Singh66e17072008-02-07 00:13:56 -08001728
KAMEZAWA Hiroyuki8c7c6e342009-01-07 18:08:00 -08001729 if (noswap)
1730 sc.may_swap = 0;
1731
Mel Gormandd1a2392008-04-28 02:12:17 -07001732 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
1733 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
1734 zonelist = NODE_DATA(numa_node_id())->node_zonelists;
1735 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001736}
1737#endif
1738
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739/*
1740 * For kswapd, balance_pgdat() will work across all this node's zones until
1741 * they are all at pages_high.
1742 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 * Returns the number of pages which were actually freed.
1744 *
1745 * There is special handling here for zones which are full of pinned pages.
1746 * This can happen if the pages are all mlocked, or if they are all used by
1747 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
1748 * What we do is to detect the case where all pages in the zone have been
1749 * scanned twice and there has been zero successful reclaim. Mark the zone as
1750 * dead and from now on, only perform a short scan. Basically we're polling
1751 * the zone for when the problem goes away.
1752 *
1753 * kswapd scans the zones in the highmem->normal->dma direction. It skips
1754 * zones which have free_pages > pages_high, but once a zone is found to have
1755 * free_pages <= pages_high, we scan that zone and the lower zones regardless
1756 * of the number of free pages in the lower zones. This interoperates with
1757 * the page allocator fallback scheme to ensure that aging of pages is balanced
1758 * across the zones.
1759 */
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001760static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 int all_zones_ok;
1763 int priority;
1764 int i;
Andrew Morton69e05942006-03-22 00:08:19 -08001765 unsigned long total_scanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 struct reclaim_state *reclaim_state = current->reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08001767 struct scan_control sc = {
1768 .gfp_mask = GFP_KERNEL,
1769 .may_swap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001770 .swap_cluster_max = SWAP_CLUSTER_MAX,
1771 .swappiness = vm_swappiness,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001772 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08001773 .mem_cgroup = NULL,
1774 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08001775 };
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001776 /*
1777 * temp_priority is used to remember the scanning priority at which
1778 * this zone was successfully refilled to free_pages == pages_high.
1779 */
1780 int temp_priority[MAX_NR_ZONES];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781
1782loop_again:
1783 total_scanned = 0;
Rik van Riela79311c2009-01-06 14:40:01 -08001784 sc.nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07001785 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001786 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001788 for (i = 0; i < pgdat->nr_zones; i++)
1789 temp_priority[i] = DEF_PRIORITY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790
1791 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
1792 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
1793 unsigned long lru_pages = 0;
1794
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001795 /* The swap token gets in the way of swapout... */
1796 if (!priority)
1797 disable_swap_token();
1798
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799 all_zones_ok = 1;
1800
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001801 /*
1802 * Scan in the highmem->dma direction for the highest
1803 * zone which needs scanning
1804 */
1805 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
1806 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001808 if (!populated_zone(zone))
1809 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810
David Rientjese815af92007-10-16 23:25:54 -07001811 if (zone_is_all_unreclaimable(zone) &&
1812 priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001813 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814
Rik van Riel556adec2008-10-18 20:26:34 -07001815 /*
1816 * Do some background aging of the anon list, to give
1817 * pages a chance to be referenced before reclaiming.
1818 */
KOSAKI Motohiro14797e22009-01-07 18:08:18 -08001819 if (inactive_anon_is_low(zone, &sc))
Rik van Riel556adec2008-10-18 20:26:34 -07001820 shrink_active_list(SWAP_CLUSTER_MAX, zone,
1821 &sc, priority, 0);
1822
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001823 if (!zone_watermark_ok(zone, order, zone->pages_high,
1824 0, 0)) {
1825 end_zone = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001826 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001829 if (i < 0)
1830 goto out;
1831
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 for (i = 0; i <= end_zone; i++) {
1833 struct zone *zone = pgdat->node_zones + i;
1834
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001835 lru_pages += zone_lru_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 }
1837
1838 /*
1839 * Now scan the zone in the dma->highmem direction, stopping
1840 * at the last zone which needs scanning.
1841 *
1842 * We do this because the page allocator works in the opposite
1843 * direction. This prevents the page allocator from allocating
1844 * pages behind kswapd's direction of progress, which would
1845 * cause too much scanning of the lower zones.
1846 */
1847 for (i = 0; i <= end_zone; i++) {
1848 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001849 int nr_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850
Con Kolivasf3fe6512006-01-06 00:11:15 -08001851 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 continue;
1853
David Rientjese815af92007-10-16 23:25:54 -07001854 if (zone_is_all_unreclaimable(zone) &&
1855 priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 continue;
1857
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001858 if (!zone_watermark_ok(zone, order, zone->pages_high,
1859 end_zone, 0))
1860 all_zones_ok = 0;
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001861 temp_priority[i] = priority;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 sc.nr_scanned = 0;
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001863 note_zone_scanning_priority(zone, priority);
Rik van Riel32a43302007-10-16 01:24:50 -07001864 /*
1865 * We put equal pressure on every zone, unless one
1866 * zone has way too many pages free already.
1867 */
1868 if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
1869 end_zone, 0))
Rik van Riela79311c2009-01-06 14:40:01 -08001870 shrink_zone(priority, zone, &sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 reclaim_state->reclaimed_slab = 0;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001872 nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
1873 lru_pages);
Rik van Riela79311c2009-01-06 14:40:01 -08001874 sc.nr_reclaimed += reclaim_state->reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 total_scanned += sc.nr_scanned;
David Rientjese815af92007-10-16 23:25:54 -07001876 if (zone_is_all_unreclaimable(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 continue;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001878 if (nr_slab == 0 && zone->pages_scanned >=
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001879 (zone_lru_pages(zone) * 6))
David Rientjese815af92007-10-16 23:25:54 -07001880 zone_set_flag(zone,
1881 ZONE_ALL_UNRECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 /*
1883 * If we've done a decent amount of scanning and
1884 * the reclaim ratio is low, start doing writepage
1885 * even in laptop mode
1886 */
1887 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Rik van Riela79311c2009-01-06 14:40:01 -08001888 total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 sc.may_writepage = 1;
1890 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891 if (all_zones_ok)
1892 break; /* kswapd: all done */
1893 /*
1894 * OK, kswapd is getting into trouble. Take a nap, then take
1895 * another pass across the zones.
1896 */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001897 if (total_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001898 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899
1900 /*
1901 * We do this so kswapd doesn't build up large priorities for
1902 * example when it is freeing in parallel with allocators. It
1903 * matches the direct reclaim path behaviour in terms of impact
1904 * on zone->*_priority.
1905 */
Rik van Riela79311c2009-01-06 14:40:01 -08001906 if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 break;
1908 }
1909out:
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001910 /*
1911 * Note within each zone the priority level at which this zone was
1912 * brought into a happy state. So that the next thread which scans this
1913 * zone will start out at that priority level.
1914 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915 for (i = 0; i < pgdat->nr_zones; i++) {
1916 struct zone *zone = pgdat->node_zones + i;
1917
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001918 zone->prev_priority = temp_priority[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 }
1920 if (!all_zones_ok) {
1921 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08001922
1923 try_to_freeze();
1924
KOSAKI Motohiro73ce02e2009-01-06 14:40:33 -08001925 /*
1926 * Fragmentation may mean that the system cannot be
1927 * rebalanced for high-order allocations in all zones.
1928 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
1929 * it means the zones have been fully scanned and are still
1930 * not balanced. For high-order allocations, there is
1931 * little point trying all over again as kswapd may
1932 * infinite loop.
1933 *
1934 * Instead, recheck all watermarks at order-0 as they
1935 * are the most important. If watermarks are ok, kswapd will go
1936 * back to sleep. High-order users can still perform direct
1937 * reclaim if they wish.
1938 */
1939 if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
1940 order = sc.order = 0;
1941
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942 goto loop_again;
1943 }
1944
Rik van Riela79311c2009-01-06 14:40:01 -08001945 return sc.nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946}
1947
1948/*
1949 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001950 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 *
1952 * This basically trickles out pages so that we have _some_
1953 * free memory available even if there is no other activity
1954 * that frees anything up. This is needed for things like routing
1955 * etc, where we otherwise might have all activity going on in
1956 * asynchronous contexts that cannot page things out.
1957 *
1958 * If there are applications that are active memory-allocators
1959 * (most normal use), this basically shouldn't matter.
1960 */
1961static int kswapd(void *p)
1962{
1963 unsigned long order;
1964 pg_data_t *pgdat = (pg_data_t*)p;
1965 struct task_struct *tsk = current;
1966 DEFINE_WAIT(wait);
1967 struct reclaim_state reclaim_state = {
1968 .reclaimed_slab = 0,
1969 };
Mike Travisc5f59f02008-04-04 18:11:10 -07001970 node_to_cpumask_ptr(cpumask, pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971
Rusty Russell174596a2009-01-01 10:12:29 +10301972 if (!cpumask_empty(cpumask))
Mike Travisc5f59f02008-04-04 18:11:10 -07001973 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974 current->reclaim_state = &reclaim_state;
1975
1976 /*
1977 * Tell the memory management that we're a "memory allocator",
1978 * and that if we need more memory we should get access to it
1979 * regardless (see "__alloc_pages()"). "kswapd" should
1980 * never get caught in the normal page freeing logic.
1981 *
1982 * (Kswapd normally doesn't need memory anyway, but sometimes
1983 * you need a small amount of memory in order to be able to
1984 * page out something else, and this flag essentially protects
1985 * us from recursively trying to free more memory as we're
1986 * trying to free the first piece of memory in the first place).
1987 */
Christoph Lameter930d9152006-01-08 01:00:47 -08001988 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07001989 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
1991 order = 0;
1992 for ( ; ; ) {
1993 unsigned long new_order;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07001994
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
1996 new_order = pgdat->kswapd_max_order;
1997 pgdat->kswapd_max_order = 0;
1998 if (order < new_order) {
1999 /*
2000 * Don't sleep if someone wants a larger 'order'
2001 * allocation
2002 */
2003 order = new_order;
2004 } else {
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07002005 if (!freezing(current))
2006 schedule();
2007
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 order = pgdat->kswapd_max_order;
2009 }
2010 finish_wait(&pgdat->kswapd_wait, &wait);
2011
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07002012 if (!try_to_freeze()) {
2013 /* We can speed up thawing tasks if we don't call
2014 * balance_pgdat after returning from the refrigerator
2015 */
2016 balance_pgdat(pgdat, order);
2017 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 }
2019 return 0;
2020}
2021
2022/*
2023 * A zone is low on free memory, so wake its kswapd task to service it.
2024 */
2025void wakeup_kswapd(struct zone *zone, int order)
2026{
2027 pg_data_t *pgdat;
2028
Con Kolivasf3fe6512006-01-06 00:11:15 -08002029 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 return;
2031
2032 pgdat = zone->zone_pgdat;
Rohit Seth7fb1d9f2005-11-13 16:06:43 -08002033 if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002034 return;
2035 if (pgdat->kswapd_max_order < order)
2036 pgdat->kswapd_max_order = order;
Paul Jackson02a0e532006-12-13 00:34:25 -08002037 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07002039 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07002041 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042}
2043
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002044unsigned long global_lru_pages(void)
2045{
2046 return global_page_state(NR_ACTIVE_ANON)
2047 + global_page_state(NR_ACTIVE_FILE)
2048 + global_page_state(NR_INACTIVE_ANON)
2049 + global_page_state(NR_INACTIVE_FILE);
2050}
2051
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052#ifdef CONFIG_PM
2053/*
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002054 * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages
2055 * from LRU lists system-wide, for given pass and priority, and returns the
2056 * number of reclaimed pages
2057 *
2058 * For pass > 3 we also try to shrink the LRU lists that contain a few pages
2059 */
Nigel Cunninghame07aa052006-12-22 01:07:21 -08002060static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
2061 int pass, struct scan_control *sc)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002062{
2063 struct zone *zone;
2064 unsigned long nr_to_scan, ret = 0;
Christoph Lameterb69408e2008-10-18 20:26:14 -07002065 enum lru_list l;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002066
2067 for_each_zone(zone) {
2068
2069 if (!populated_zone(zone))
2070 continue;
2071
David Rientjese815af92007-10-16 23:25:54 -07002072 if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002073 continue;
2074
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002075 for_each_evictable_lru(l) {
2076 /* For pass = 0, we don't shrink the active list */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002077 if (pass == 0 &&
2078 (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE))
Christoph Lameterb69408e2008-10-18 20:26:14 -07002079 continue;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002080
Christoph Lameterb69408e2008-10-18 20:26:14 -07002081 zone->lru[l].nr_scan +=
2082 (zone_page_state(zone, NR_LRU_BASE + l)
2083 >> prio) + 1;
2084 if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
2085 zone->lru[l].nr_scan = 0;
2086 nr_to_scan = min(nr_pages,
2087 zone_page_state(zone,
2088 NR_LRU_BASE + l));
2089 ret += shrink_list(l, nr_to_scan, zone,
2090 sc, prio);
2091 if (ret >= nr_pages)
2092 return ret;
2093 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002094 }
2095 }
2096
2097 return ret;
2098}
2099
2100/*
2101 * Try to free `nr_pages' of memory, system-wide, and return the number of
2102 * freed pages.
2103 *
2104 * Rather than trying to age LRUs the aim is to preserve the overall
2105 * LRU order by reclaiming preferentially
2106 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 */
Andrew Morton69e05942006-03-22 00:08:19 -08002108unsigned long shrink_all_memory(unsigned long nr_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002110 unsigned long lru_pages, nr_slab;
Andrew Morton69e05942006-03-22 00:08:19 -08002111 unsigned long ret = 0;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002112 int pass;
2113 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002114 struct scan_control sc = {
2115 .gfp_mask = GFP_KERNEL,
2116 .may_swap = 0,
2117 .swap_cluster_max = nr_pages,
2118 .may_writepage = 1,
2119 .swappiness = vm_swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002120 .isolate_pages = isolate_pages_global,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121 };
2122
2123 current->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08002124
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002125 lru_pages = global_lru_pages();
Christoph Lameter972d1a72006-09-25 23:31:51 -07002126 nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002127 /* If slab caches are huge, it's better to hit them first */
2128 while (nr_slab >= lru_pages) {
2129 reclaim_state.reclaimed_slab = 0;
2130 shrink_slab(nr_pages, sc.gfp_mask, lru_pages);
2131 if (!reclaim_state.reclaimed_slab)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132 break;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002133
2134 ret += reclaim_state.reclaimed_slab;
2135 if (ret >= nr_pages)
2136 goto out;
2137
2138 nr_slab -= reclaim_state.reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002140
2141 /*
2142 * We try to shrink LRUs in 5 passes:
2143 * 0 = Reclaim from inactive_list only
2144 * 1 = Reclaim from active list but don't reclaim mapped
2145 * 2 = 2nd pass of type 1
2146 * 3 = Reclaim mapped (normal reclaim)
2147 * 4 = 2nd pass of type 3
2148 */
2149 for (pass = 0; pass < 5; pass++) {
2150 int prio;
2151
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002152 /* Force reclaiming mapped pages in the passes #3 and #4 */
2153 if (pass > 2) {
2154 sc.may_swap = 1;
2155 sc.swappiness = 100;
2156 }
2157
2158 for (prio = DEF_PRIORITY; prio >= 0; prio--) {
2159 unsigned long nr_to_scan = nr_pages - ret;
2160
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002161 sc.nr_scanned = 0;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002162 ret += shrink_all_zones(nr_to_scan, prio, pass, &sc);
2163 if (ret >= nr_pages)
2164 goto out;
2165
2166 reclaim_state.reclaimed_slab = 0;
Andrew Morton76395d32007-01-05 16:37:05 -08002167 shrink_slab(sc.nr_scanned, sc.gfp_mask,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002168 global_lru_pages());
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002169 ret += reclaim_state.reclaimed_slab;
2170 if (ret >= nr_pages)
2171 goto out;
2172
2173 if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07002174 congestion_wait(WRITE, HZ / 10);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002175 }
Rafael J. Wysocki248a0302006-03-22 00:09:04 -08002176 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002177
2178 /*
2179 * If ret = 0, we could not shrink LRUs, but there may be something
2180 * in slab caches
2181 */
Andrew Morton76395d32007-01-05 16:37:05 -08002182 if (!ret) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002183 do {
2184 reclaim_state.reclaimed_slab = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002185 shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002186 ret += reclaim_state.reclaimed_slab;
2187 } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
Andrew Morton76395d32007-01-05 16:37:05 -08002188 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002189
2190out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 current->reclaim_state = NULL;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002192
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 return ret;
2194}
2195#endif
2196
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197/* It's optimal to keep kswapds on the same CPUs as their memory, but
2198 not required for correctness. So if the last cpu in a node goes
2199 away, we get changed to run anywhere: as the first one comes back,
2200 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07002201static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08002202 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002204 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002206 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002207 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07002208 pg_data_t *pgdat = NODE_DATA(nid);
2209 node_to_cpumask_ptr(mask, pgdat->node_id);
2210
Rusty Russell3e597942009-01-01 10:12:24 +10302211 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07002213 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 }
2215 }
2216 return NOTIFY_OK;
2217}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218
Yasunori Goto3218ae12006-06-27 02:53:33 -07002219/*
2220 * This kswapd start function will be called by init and node-hot-add.
2221 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
2222 */
2223int kswapd_run(int nid)
2224{
2225 pg_data_t *pgdat = NODE_DATA(nid);
2226 int ret = 0;
2227
2228 if (pgdat->kswapd)
2229 return 0;
2230
2231 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
2232 if (IS_ERR(pgdat->kswapd)) {
2233 /* failure at boot is fatal */
2234 BUG_ON(system_state == SYSTEM_BOOTING);
2235 printk("Failed to start kswapd on node %d\n",nid);
2236 ret = -1;
2237 }
2238 return ret;
2239}
2240
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241static int __init kswapd_init(void)
2242{
Yasunori Goto3218ae12006-06-27 02:53:33 -07002243 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08002244
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07002246 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07002247 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 hotcpu_notifier(cpu_callback, 0);
2249 return 0;
2250}
2251
2252module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002253
2254#ifdef CONFIG_NUMA
2255/*
2256 * Zone reclaim mode
2257 *
2258 * If non-zero call zone_reclaim when the number of free pages falls below
2259 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08002260 */
2261int zone_reclaim_mode __read_mostly;
2262
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002263#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07002264#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002265#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
2266#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
2267
Christoph Lameter9eeff232006-01-18 17:42:31 -08002268/*
Christoph Lametera92f7122006-02-01 03:05:32 -08002269 * Priority for ZONE_RECLAIM. This determines the fraction of pages
2270 * of a node considered for each zone_reclaim. 4 scans 1/16th of
2271 * a zone.
2272 */
2273#define ZONE_RECLAIM_PRIORITY 4
2274
Christoph Lameter9eeff232006-01-18 17:42:31 -08002275/*
Christoph Lameter96146342006-07-03 00:24:13 -07002276 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
2277 * occur.
2278 */
2279int sysctl_min_unmapped_ratio = 1;
2280
2281/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002282 * If the number of slab pages in a zone grows beyond this percentage then
2283 * slab reclaim needs to occur.
2284 */
2285int sysctl_min_slab_ratio = 5;
2286
2287/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08002288 * Try to free up some pages from this zone through reclaim.
2289 */
Andrew Morton179e9632006-03-22 00:08:18 -08002290static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002291{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002292 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08002293 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002294 struct task_struct *p = current;
2295 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08002296 int priority;
Andrew Morton179e9632006-03-22 00:08:18 -08002297 struct scan_control sc = {
2298 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
2299 .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
Andrew Morton69e05942006-03-22 00:08:19 -08002300 .swap_cluster_max = max_t(unsigned long, nr_pages,
2301 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08002302 .gfp_mask = gfp_mask,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002303 .swappiness = vm_swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002304 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08002305 };
Christoph Lameter83e33a42006-09-25 23:31:53 -07002306 unsigned long slab_reclaimable;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002307
2308 disable_swap_token();
Christoph Lameter9eeff232006-01-18 17:42:31 -08002309 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08002310 /*
2311 * We need to be able to allocate from the reserves for RECLAIM_SWAP
2312 * and we also need to be able to write out pages for RECLAIM_WRITE
2313 * and RECLAIM_SWAP.
2314 */
2315 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002316 reclaim_state.reclaimed_slab = 0;
2317 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08002318
Christoph Lameter0ff38492006-09-25 23:31:52 -07002319 if (zone_page_state(zone, NR_FILE_PAGES) -
2320 zone_page_state(zone, NR_FILE_MAPPED) >
2321 zone->min_unmapped_pages) {
2322 /*
2323 * Free memory by calling shrink zone with increasing
2324 * priorities until we have enough memory freed.
2325 */
2326 priority = ZONE_RECLAIM_PRIORITY;
2327 do {
Martin Bligh3bb1a8522006-10-28 10:38:24 -07002328 note_zone_scanning_priority(zone, priority);
Rik van Riela79311c2009-01-06 14:40:01 -08002329 shrink_zone(priority, zone, &sc);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002330 priority--;
Rik van Riela79311c2009-01-06 14:40:01 -08002331 } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002332 }
Christoph Lameterc84db232006-02-01 03:05:29 -08002333
Christoph Lameter83e33a42006-09-25 23:31:53 -07002334 slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
2335 if (slab_reclaimable > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002336 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002337 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07002338 * many pages were freed in this zone. So we take the current
2339 * number of slab pages and shake the slab until it is reduced
2340 * by the same nr_pages that we used for reclaiming unmapped
2341 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002342 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07002343 * Note that shrink_slab will free memory on all zones and may
2344 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002345 */
Christoph Lameter0ff38492006-09-25 23:31:52 -07002346 while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
Christoph Lameter83e33a42006-09-25 23:31:53 -07002347 zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
2348 slab_reclaimable - nr_pages)
Christoph Lameter0ff38492006-09-25 23:31:52 -07002349 ;
Christoph Lameter83e33a42006-09-25 23:31:53 -07002350
2351 /*
2352 * Update nr_reclaimed by the number of slab pages we
2353 * reclaimed from this zone.
2354 */
Rik van Riela79311c2009-01-06 14:40:01 -08002355 sc.nr_reclaimed += slab_reclaimable -
Christoph Lameter83e33a42006-09-25 23:31:53 -07002356 zone_page_state(zone, NR_SLAB_RECLAIMABLE);
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002357 }
2358
Christoph Lameter9eeff232006-01-18 17:42:31 -08002359 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08002360 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
Rik van Riela79311c2009-01-06 14:40:01 -08002361 return sc.nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002362}
Andrew Morton179e9632006-03-22 00:08:18 -08002363
2364int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
2365{
Andrew Morton179e9632006-03-22 00:08:18 -08002366 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07002367 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002368
2369 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002370 * Zone reclaim reclaims unmapped file backed pages and
2371 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07002372 *
Christoph Lameter96146342006-07-03 00:24:13 -07002373 * A small portion of unmapped file backed pages is needed for
2374 * file I/O otherwise pages read by file I/O will be immediately
2375 * thrown out if the zone is overallocated. So we do not reclaim
2376 * if less than a specified percentage of the zone is used by
2377 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08002378 */
Christoph Lameter34aa1332006-06-30 01:55:37 -07002379 if (zone_page_state(zone, NR_FILE_PAGES) -
Christoph Lameter0ff38492006-09-25 23:31:52 -07002380 zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages
2381 && zone_page_state(zone, NR_SLAB_RECLAIMABLE)
2382 <= zone->min_slab_pages)
Christoph Lameter96146342006-07-03 00:24:13 -07002383 return 0;
Andrew Morton179e9632006-03-22 00:08:18 -08002384
David Rientjesd773ed62007-10-16 23:26:01 -07002385 if (zone_is_all_unreclaimable(zone))
2386 return 0;
2387
Andrew Morton179e9632006-03-22 00:08:18 -08002388 /*
David Rientjesd773ed62007-10-16 23:26:01 -07002389 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08002390 */
David Rientjesd773ed62007-10-16 23:26:01 -07002391 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Andrew Morton179e9632006-03-22 00:08:18 -08002392 return 0;
2393
2394 /*
2395 * Only run zone reclaim on the local zone or on zones that do not
2396 * have associated processors. This will favor the local processor
2397 * over remote processors and spread off node memory allocations
2398 * as wide as possible.
2399 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07002400 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07002401 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Andrew Morton179e9632006-03-22 00:08:18 -08002402 return 0;
David Rientjesd773ed62007-10-16 23:26:01 -07002403
2404 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
2405 return 0;
2406 ret = __zone_reclaim(zone, gfp_mask, order);
2407 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
2408
2409 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002410}
Christoph Lameter9eeff232006-01-18 17:42:31 -08002411#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002412
2413#ifdef CONFIG_UNEVICTABLE_LRU
2414/*
2415 * page_evictable - test whether a page is evictable
2416 * @page: the page to test
2417 * @vma: the VMA in which the page is or will be mapped, may be NULL
2418 *
2419 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07002420 * lists vs unevictable list. The vma argument is !NULL when called from the
2421 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002422 *
2423 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002424 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07002425 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002426 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002427 */
2428int page_evictable(struct page *page, struct vm_area_struct *vma)
2429{
2430
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002431 if (mapping_unevictable(page_mapping(page)))
2432 return 0;
2433
Nick Pigginb291f002008-10-18 20:26:44 -07002434 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
2435 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002436
2437 return 1;
2438}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002439
2440/**
2441 * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
2442 * @page: page to check evictability and move to appropriate lru list
2443 * @zone: zone page is in
2444 *
2445 * Checks a page for evictability and moves the page to the appropriate
2446 * zone lru list.
2447 *
2448 * Restrictions: zone->lru_lock must be held, page must be on LRU and must
2449 * have PageUnevictable set.
2450 */
2451static void check_move_unevictable_page(struct page *page, struct zone *zone)
2452{
2453 VM_BUG_ON(PageActive(page));
2454
2455retry:
2456 ClearPageUnevictable(page);
2457 if (page_evictable(page, NULL)) {
2458 enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page);
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002459
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002460 __dec_zone_state(zone, NR_UNEVICTABLE);
2461 list_move(&page->lru, &zone->lru[l].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08002462 mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002463 __inc_zone_state(zone, NR_INACTIVE_ANON + l);
2464 __count_vm_event(UNEVICTABLE_PGRESCUED);
2465 } else {
2466 /*
2467 * rotate unevictable list
2468 */
2469 SetPageUnevictable(page);
2470 list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -08002471 mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002472 if (page_evictable(page, NULL))
2473 goto retry;
2474 }
2475}
2476
2477/**
2478 * scan_mapping_unevictable_pages - scan an address space for evictable pages
2479 * @mapping: struct address_space to scan for evictable pages
2480 *
2481 * Scan all pages in mapping. Check unevictable pages for
2482 * evictability and move them to the appropriate zone lru list.
2483 */
2484void scan_mapping_unevictable_pages(struct address_space *mapping)
2485{
2486 pgoff_t next = 0;
2487 pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
2488 PAGE_CACHE_SHIFT;
2489 struct zone *zone;
2490 struct pagevec pvec;
2491
2492 if (mapping->nrpages == 0)
2493 return;
2494
2495 pagevec_init(&pvec, 0);
2496 while (next < end &&
2497 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
2498 int i;
2499 int pg_scanned = 0;
2500
2501 zone = NULL;
2502
2503 for (i = 0; i < pagevec_count(&pvec); i++) {
2504 struct page *page = pvec.pages[i];
2505 pgoff_t page_index = page->index;
2506 struct zone *pagezone = page_zone(page);
2507
2508 pg_scanned++;
2509 if (page_index > next)
2510 next = page_index;
2511 next++;
2512
2513 if (pagezone != zone) {
2514 if (zone)
2515 spin_unlock_irq(&zone->lru_lock);
2516 zone = pagezone;
2517 spin_lock_irq(&zone->lru_lock);
2518 }
2519
2520 if (PageLRU(page) && PageUnevictable(page))
2521 check_move_unevictable_page(page, zone);
2522 }
2523 if (zone)
2524 spin_unlock_irq(&zone->lru_lock);
2525 pagevec_release(&pvec);
2526
2527 count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
2528 }
2529
2530}
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002531
2532/**
2533 * scan_zone_unevictable_pages - check unevictable list for evictable pages
2534 * @zone - zone of which to scan the unevictable list
2535 *
2536 * Scan @zone's unevictable LRU lists to check for pages that have become
2537 * evictable. Move those that have to @zone's inactive list where they
2538 * become candidates for reclaim, unless shrink_inactive_zone() decides
2539 * to reactivate them. Pages that are still unevictable are rotated
2540 * back onto @zone's unevictable list.
2541 */
2542#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
KOSAKI Motohiro14b90b22009-01-06 14:39:45 -08002543static void scan_zone_unevictable_pages(struct zone *zone)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002544{
2545 struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
2546 unsigned long scan;
2547 unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
2548
2549 while (nr_to_scan > 0) {
2550 unsigned long batch_size = min(nr_to_scan,
2551 SCAN_UNEVICTABLE_BATCH_SIZE);
2552
2553 spin_lock_irq(&zone->lru_lock);
2554 for (scan = 0; scan < batch_size; scan++) {
2555 struct page *page = lru_to_page(l_unevictable);
2556
2557 if (!trylock_page(page))
2558 continue;
2559
2560 prefetchw_prev_lru_page(page, l_unevictable, flags);
2561
2562 if (likely(PageLRU(page) && PageUnevictable(page)))
2563 check_move_unevictable_page(page, zone);
2564
2565 unlock_page(page);
2566 }
2567 spin_unlock_irq(&zone->lru_lock);
2568
2569 nr_to_scan -= batch_size;
2570 }
2571}
2572
2573
2574/**
2575 * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages
2576 *
2577 * A really big hammer: scan all zones' unevictable LRU lists to check for
2578 * pages that have become evictable. Move those back to the zones'
2579 * inactive list where they become candidates for reclaim.
2580 * This occurs when, e.g., we have unswappable pages on the unevictable lists,
2581 * and we add swap to the system. As such, it runs in the context of a task
2582 * that has possibly/probably made some previously unevictable pages
2583 * evictable.
2584 */
KOSAKI Motohiroff301532009-01-06 14:39:44 -08002585static void scan_all_zones_unevictable_pages(void)
Lee Schermerhornaf936a12008-10-18 20:26:53 -07002586{
2587 struct zone *zone;
2588
2589 for_each_zone(zone) {
2590 scan_zone_unevictable_pages(zone);
2591 }
2592}
2593
2594/*
2595 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
2596 * all nodes' unevictable lists for evictable pages
2597 */
2598unsigned long scan_unevictable_pages;
2599
2600int scan_unevictable_handler(struct ctl_table *table, int write,
2601 struct file *file, void __user *buffer,
2602 size_t *length, loff_t *ppos)
2603{
2604 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
2605
2606 if (write && *(unsigned long *)table->data)
2607 scan_all_zones_unevictable_pages();
2608
2609 scan_unevictable_pages = 0;
2610 return 0;
2611}
2612
2613/*
2614 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
2615 * a specified node's per zone unevictable lists for evictable pages.
2616 */
2617
2618static ssize_t read_scan_unevictable_node(struct sys_device *dev,
2619 struct sysdev_attribute *attr,
2620 char *buf)
2621{
2622 return sprintf(buf, "0\n"); /* always zero; should fit... */
2623}
2624
2625static ssize_t write_scan_unevictable_node(struct sys_device *dev,
2626 struct sysdev_attribute *attr,
2627 const char *buf, size_t count)
2628{
2629 struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
2630 struct zone *zone;
2631 unsigned long res;
2632 unsigned long req = strict_strtoul(buf, 10, &res);
2633
2634 if (!req)
2635 return 1; /* zero is no-op */
2636
2637 for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
2638 if (!populated_zone(zone))
2639 continue;
2640 scan_zone_unevictable_pages(zone);
2641 }
2642 return 1;
2643}
2644
2645
2646static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR,
2647 read_scan_unevictable_node,
2648 write_scan_unevictable_node);
2649
2650int scan_unevictable_register_node(struct node *node)
2651{
2652 return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages);
2653}
2654
2655void scan_unevictable_unregister_node(struct node *node)
2656{
2657 sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
2658}
2659
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002660#endif