blob: e5aaaad159ef236a1580faafaf7e663547f5965e [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
43#include <asm/tlbflush.h>
44#include <asm/div64.h>
45
46#include <linux/swapops.h>
47
Nick Piggin0f8053a2006-03-22 00:08:33 -080048#include "internal.h"
49
Linus Torvalds1da177e2005-04-16 15:20:36 -070050struct scan_control {
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 /* Incremented by the number of inactive pages that were scanned */
52 unsigned long nr_scanned;
53
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 /* This context's GFP mask */
Al Viro6daa0e22005-10-21 03:18:50 -040055 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57 int may_writepage;
58
Christoph Lameterf1fd1062006-01-18 17:42:30 -080059 /* Can pages be swapped as part of reclaim? */
60 int may_swap;
61
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 /* This context's SWAP_CLUSTER_MAX. If freeing memory for
63 * suspend, we effectively ignore SWAP_CLUSTER_MAX.
64 * In this context, it doesn't matter that we scan the
65 * whole list at once. */
66 int swap_cluster_max;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -070067
68 int swappiness;
Nick Piggin408d8542006-09-25 23:31:27 -070069
70 int all_unreclaimable;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -070071
72 int order;
Balbir Singh66e17072008-02-07 00:13:56 -080073
74 /* Which cgroup do we reclaim from */
75 struct mem_cgroup *mem_cgroup;
76
77 /* Pluggable isolate pages callback */
78 unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
79 unsigned long *scanned, int order, int mode,
80 struct zone *z, struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -070081 int active, int file);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082};
83
Linus Torvalds1da177e2005-04-16 15:20:36 -070084#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
85
86#ifdef ARCH_HAS_PREFETCH
87#define prefetch_prev_lru_page(_page, _base, _field) \
88 do { \
89 if ((_page)->lru.prev != _base) { \
90 struct page *prev; \
91 \
92 prev = lru_to_page(&(_page->lru)); \
93 prefetch(&prev->_field); \
94 } \
95 } while (0)
96#else
97#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
98#endif
99
100#ifdef ARCH_HAS_PREFETCHW
101#define prefetchw_prev_lru_page(_page, _base, _field) \
102 do { \
103 if ((_page)->lru.prev != _base) { \
104 struct page *prev; \
105 \
106 prev = lru_to_page(&(_page->lru)); \
107 prefetchw(&prev->_field); \
108 } \
109 } while (0)
110#else
111#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
112#endif
113
114/*
115 * From 0 .. 100. Higher means more swappy.
116 */
117int vm_swappiness = 60;
Andrew Mortonbd1e22b2006-06-23 02:03:47 -0700118long vm_total_pages; /* The total number of pages which the VM controls */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120static LIST_HEAD(shrinker_list);
121static DECLARE_RWSEM(shrinker_rwsem);
122
Balbir Singh00f0b822008-03-04 14:28:39 -0800123#ifdef CONFIG_CGROUP_MEM_RES_CTLR
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -0800124#define scan_global_lru(sc) (!(sc)->mem_cgroup)
125#else
126#define scan_global_lru(sc) (1)
127#endif
128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129/*
130 * Add a shrinker callback to be called from the vm
131 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700132void register_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133{
Rusty Russell8e1f9362007-07-17 04:03:17 -0700134 shrinker->nr = 0;
135 down_write(&shrinker_rwsem);
136 list_add_tail(&shrinker->list, &shrinker_list);
137 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700139EXPORT_SYMBOL(register_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
141/*
142 * Remove one
143 */
Rusty Russell8e1f9362007-07-17 04:03:17 -0700144void unregister_shrinker(struct shrinker *shrinker)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145{
146 down_write(&shrinker_rwsem);
147 list_del(&shrinker->list);
148 up_write(&shrinker_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149}
Rusty Russell8e1f9362007-07-17 04:03:17 -0700150EXPORT_SYMBOL(unregister_shrinker);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152#define SHRINK_BATCH 128
153/*
154 * Call the shrink functions to age shrinkable caches
155 *
156 * Here we assume it costs one seek to replace a lru page and that it also
157 * takes a seek to recreate a cache object. With this in mind we age equal
158 * percentages of the lru and ageable caches. This should balance the seeks
159 * generated by these structures.
160 *
Simon Arlott183ff222007-10-20 01:27:18 +0200161 * If the vm encountered mapped pages on the LRU it increase the pressure on
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 * slab to avoid swapping.
163 *
164 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
165 *
166 * `lru_pages' represents the number of on-LRU pages in all the zones which
167 * are eligible for the caller's allocation attempt. It is used for balancing
168 * slab reclaim versus page reclaim.
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700169 *
170 * Returns the number of slab objects which we shrunk.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 */
Andrew Morton69e05942006-03-22 00:08:19 -0800172unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
173 unsigned long lru_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174{
175 struct shrinker *shrinker;
Andrew Morton69e05942006-03-22 00:08:19 -0800176 unsigned long ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
178 if (scanned == 0)
179 scanned = SWAP_CLUSTER_MAX;
180
181 if (!down_read_trylock(&shrinker_rwsem))
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700182 return 1; /* Assume we'll be able to shrink next time */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
184 list_for_each_entry(shrinker, &shrinker_list, list) {
185 unsigned long long delta;
186 unsigned long total_scan;
Rusty Russell8e1f9362007-07-17 04:03:17 -0700187 unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188
189 delta = (4 * scanned) / shrinker->seeks;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800190 delta *= max_pass;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 do_div(delta, lru_pages + 1);
192 shrinker->nr += delta;
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800193 if (shrinker->nr < 0) {
194 printk(KERN_ERR "%s: nr=%ld\n",
Harvey Harrisond40cee22008-04-30 00:55:07 -0700195 __func__, shrinker->nr);
Andrea Arcangeliea164d72005-11-28 13:44:15 -0800196 shrinker->nr = max_pass;
197 }
198
199 /*
200 * Avoid risking looping forever due to too large nr value:
201 * never try to free more than twice the estimate number of
202 * freeable entries.
203 */
204 if (shrinker->nr > max_pass * 2)
205 shrinker->nr = max_pass * 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206
207 total_scan = shrinker->nr;
208 shrinker->nr = 0;
209
210 while (total_scan >= SHRINK_BATCH) {
211 long this_scan = SHRINK_BATCH;
212 int shrink_ret;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700213 int nr_before;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214
Rusty Russell8e1f9362007-07-17 04:03:17 -0700215 nr_before = (*shrinker->shrink)(0, gfp_mask);
216 shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 if (shrink_ret == -1)
218 break;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700219 if (shrink_ret < nr_before)
220 ret += nr_before - shrink_ret;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700221 count_vm_events(SLABS_SCANNED, this_scan);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 total_scan -= this_scan;
223
224 cond_resched();
225 }
226
227 shrinker->nr += total_scan;
228 }
229 up_read(&shrinker_rwsem);
akpm@osdl.orgb15e0902005-06-21 17:14:35 -0700230 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231}
232
233/* Called without lock on whether page is mapped, so answer is unstable */
234static inline int page_mapping_inuse(struct page *page)
235{
236 struct address_space *mapping;
237
238 /* Page is in somebody's page tables. */
239 if (page_mapped(page))
240 return 1;
241
242 /* Be more reluctant to reclaim swapcache than pagecache */
243 if (PageSwapCache(page))
244 return 1;
245
246 mapping = page_mapping(page);
247 if (!mapping)
248 return 0;
249
250 /* File is mmap'd by somebody? */
251 return mapping_mapped(mapping);
252}
253
254static inline int is_page_cache_freeable(struct page *page)
255{
256 return page_count(page) - !!PagePrivate(page) == 2;
257}
258
259static int may_write_to_queue(struct backing_dev_info *bdi)
260{
Christoph Lameter930d9152006-01-08 01:00:47 -0800261 if (current->flags & PF_SWAPWRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 return 1;
263 if (!bdi_write_congested(bdi))
264 return 1;
265 if (bdi == current->backing_dev_info)
266 return 1;
267 return 0;
268}
269
270/*
271 * We detected a synchronous write error writing a page out. Probably
272 * -ENOSPC. We need to propagate that into the address_space for a subsequent
273 * fsync(), msync() or close().
274 *
275 * The tricky part is that after writepage we cannot touch the mapping: nothing
276 * prevents it from being freed up. But we have a ref on the page and once
277 * that page is locked, the mapping is pinned.
278 *
279 * We're allowed to run sleeping lock_page() here because we know the caller has
280 * __GFP_FS.
281 */
282static void handle_write_error(struct address_space *mapping,
283 struct page *page, int error)
284{
285 lock_page(page);
Guillaume Chazarain3e9f45b2007-05-08 00:23:25 -0700286 if (page_mapping(page) == mapping)
287 mapping_set_error(mapping, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 unlock_page(page);
289}
290
Andy Whitcroftc661b072007-08-22 14:01:26 -0700291/* Request for sync pageout. */
292enum pageout_io {
293 PAGEOUT_IO_ASYNC,
294 PAGEOUT_IO_SYNC,
295};
296
Christoph Lameter04e62a22006-06-23 02:03:38 -0700297/* possible outcome of pageout() */
298typedef enum {
299 /* failed to write page out, page is locked */
300 PAGE_KEEP,
301 /* move page to the active list, page is locked */
302 PAGE_ACTIVATE,
303 /* page has been sent to the disk successfully, page is unlocked */
304 PAGE_SUCCESS,
305 /* page is clean and locked */
306 PAGE_CLEAN,
307} pageout_t;
308
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309/*
Andrew Morton1742f192006-03-22 00:08:21 -0800310 * pageout is called by shrink_page_list() for each dirty page.
311 * Calls ->writepage().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700313static pageout_t pageout(struct page *page, struct address_space *mapping,
314 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315{
316 /*
317 * If the page is dirty, only perform writeback if that write
318 * will be non-blocking. To prevent this allocation from being
319 * stalled by pagecache activity. But note that there may be
320 * stalls if we need to run get_block(). We could test
321 * PagePrivate for that.
322 *
323 * If this process is currently in generic_file_write() against
324 * this page's queue, we can perform writeback even if that
325 * will block.
326 *
327 * If the page is swapcache, write it back even if that would
328 * block, for some throttling. This happens by accident, because
329 * swap_backing_dev_info is bust: it doesn't reflect the
330 * congestion state of the swapdevs. Easy to fix, if needed.
331 * See swapfile.c:page_queue_congested().
332 */
333 if (!is_page_cache_freeable(page))
334 return PAGE_KEEP;
335 if (!mapping) {
336 /*
337 * Some data journaling orphaned pages can have
338 * page->mapping == NULL while being dirty with clean buffers.
339 */
akpm@osdl.org323aca62005-04-16 15:24:06 -0700340 if (PagePrivate(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 if (try_to_free_buffers(page)) {
342 ClearPageDirty(page);
Harvey Harrisond40cee22008-04-30 00:55:07 -0700343 printk("%s: orphaned page\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 return PAGE_CLEAN;
345 }
346 }
347 return PAGE_KEEP;
348 }
349 if (mapping->a_ops->writepage == NULL)
350 return PAGE_ACTIVATE;
351 if (!may_write_to_queue(mapping->backing_dev_info))
352 return PAGE_KEEP;
353
354 if (clear_page_dirty_for_io(page)) {
355 int res;
356 struct writeback_control wbc = {
357 .sync_mode = WB_SYNC_NONE,
358 .nr_to_write = SWAP_CLUSTER_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700359 .range_start = 0,
360 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 .nonblocking = 1,
362 .for_reclaim = 1,
363 };
364
365 SetPageReclaim(page);
366 res = mapping->a_ops->writepage(page, &wbc);
367 if (res < 0)
368 handle_write_error(mapping, page, res);
Zach Brown994fc28c2005-12-15 14:28:17 -0800369 if (res == AOP_WRITEPAGE_ACTIVATE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 ClearPageReclaim(page);
371 return PAGE_ACTIVATE;
372 }
Andy Whitcroftc661b072007-08-22 14:01:26 -0700373
374 /*
375 * Wait on writeback if requested to. This happens when
376 * direct reclaiming a large contiguous area and the
377 * first attempt to free a range of pages fails.
378 */
379 if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
380 wait_on_page_writeback(page);
381
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 if (!PageWriteback(page)) {
383 /* synchronous write or broken a_ops? */
384 ClearPageReclaim(page);
385 }
Andrew Mortone129b5c2006-09-27 01:50:00 -0700386 inc_zone_page_state(page, NR_VMSCAN_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 return PAGE_SUCCESS;
388 }
389
390 return PAGE_CLEAN;
391}
392
Andrew Mortona649fd92006-10-17 00:09:36 -0700393/*
Nick Piggine2867812008-07-25 19:45:30 -0700394 * Same as remove_mapping, but if the page is removed from the mapping, it
395 * gets returned with a refcount of 0.
Andrew Mortona649fd92006-10-17 00:09:36 -0700396 */
Nick Piggine2867812008-07-25 19:45:30 -0700397static int __remove_mapping(struct address_space *mapping, struct page *page)
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800398{
Nick Piggin28e4d962006-09-25 23:31:23 -0700399 BUG_ON(!PageLocked(page));
400 BUG_ON(mapping != page_mapping(page));
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800401
Nick Piggin19fd6232008-07-25 19:45:32 -0700402 spin_lock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800403 /*
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700404 * The non racy check for a busy page.
405 *
406 * Must be careful with the order of the tests. When someone has
407 * a ref to the page, it may be possible that they dirty it then
408 * drop the reference. So if PageDirty is tested before page_count
409 * here, then the following race may occur:
410 *
411 * get_user_pages(&page);
412 * [user mapping goes away]
413 * write_to(page);
414 * !PageDirty(page) [good]
415 * SetPageDirty(page);
416 * put_page(page);
417 * !page_count(page) [good, discard it]
418 *
419 * [oops, our write_to data is lost]
420 *
421 * Reversing the order of the tests ensures such a situation cannot
422 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
423 * load is not satisfied before that of page->_count.
424 *
425 * Note that if SetPageDirty is always performed via set_page_dirty,
426 * and thus under tree_lock, then this ordering is not required.
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800427 */
Nick Piggine2867812008-07-25 19:45:30 -0700428 if (!page_freeze_refs(page, 2))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800429 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700430 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
431 if (unlikely(PageDirty(page))) {
432 page_unfreeze_refs(page, 2);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800433 goto cannot_free;
Nick Piggine2867812008-07-25 19:45:30 -0700434 }
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800435
436 if (PageSwapCache(page)) {
437 swp_entry_t swap = { .val = page_private(page) };
438 __delete_from_swap_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700439 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800440 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -0700441 } else {
442 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700443 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800444 }
445
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800446 return 1;
447
448cannot_free:
Nick Piggin19fd6232008-07-25 19:45:32 -0700449 spin_unlock_irq(&mapping->tree_lock);
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800450 return 0;
451}
452
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453/*
Nick Piggine2867812008-07-25 19:45:30 -0700454 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
455 * someone else has a ref on the page, abort and return 0. If it was
456 * successfully detached, return 1. Assumes the caller has a single ref on
457 * this page.
458 */
459int remove_mapping(struct address_space *mapping, struct page *page)
460{
461 if (__remove_mapping(mapping, page)) {
462 /*
463 * Unfreezing the refcount with 1 rather than 2 effectively
464 * drops the pagecache ref for us without requiring another
465 * atomic operation.
466 */
467 page_unfreeze_refs(page, 1);
468 return 1;
469 }
470 return 0;
471}
472
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700473/**
474 * putback_lru_page - put previously isolated page onto appropriate LRU list
475 * @page: page to be put back to appropriate lru list
476 *
477 * Add previously isolated @page to appropriate LRU list.
478 * Page may still be unevictable for other reasons.
479 *
480 * lru_lock must not be held, interrupts must be enabled.
481 */
482#ifdef CONFIG_UNEVICTABLE_LRU
483void putback_lru_page(struct page *page)
484{
485 int lru;
486 int active = !!TestClearPageActive(page);
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700487 int was_unevictable = PageUnevictable(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700488
489 VM_BUG_ON(PageLRU(page));
490
491redo:
492 ClearPageUnevictable(page);
493
494 if (page_evictable(page, NULL)) {
495 /*
496 * For evictable pages, we can use the cache.
497 * In event of a race, worst case is we end up with an
498 * unevictable page on [in]active list.
499 * We know how to handle that.
500 */
501 lru = active + page_is_file_cache(page);
502 lru_cache_add_lru(page, lru);
503 } else {
504 /*
505 * Put unevictable pages directly on zone's unevictable
506 * list.
507 */
508 lru = LRU_UNEVICTABLE;
509 add_page_to_unevictable_list(page);
510 }
511 mem_cgroup_move_lists(page, lru);
512
513 /*
514 * page's status can change while we move it among lru. If an evictable
515 * page is on unevictable list, it never be freed. To avoid that,
516 * check after we added it to the list, again.
517 */
518 if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) {
519 if (!isolate_lru_page(page)) {
520 put_page(page);
521 goto redo;
522 }
523 /* This means someone else dropped this page from LRU
524 * So, it will be freed or putback to LRU again. There is
525 * nothing to do here.
526 */
527 }
528
Lee Schermerhornbbfd28e2008-10-18 20:26:40 -0700529 if (was_unevictable && lru != LRU_UNEVICTABLE)
530 count_vm_event(UNEVICTABLE_PGRESCUED);
531 else if (!was_unevictable && lru == LRU_UNEVICTABLE)
532 count_vm_event(UNEVICTABLE_PGCULLED);
533
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700534 put_page(page); /* drop ref from isolate */
535}
536
537#else /* CONFIG_UNEVICTABLE_LRU */
538
539void putback_lru_page(struct page *page)
540{
541 int lru;
542 VM_BUG_ON(PageLRU(page));
543
544 lru = !!TestClearPageActive(page) + page_is_file_cache(page);
545 lru_cache_add_lru(page, lru);
546 mem_cgroup_move_lists(page, lru);
547 put_page(page);
548}
549#endif /* CONFIG_UNEVICTABLE_LRU */
550
551
Nick Piggine2867812008-07-25 19:45:30 -0700552/*
Andrew Morton1742f192006-03-22 00:08:21 -0800553 * shrink_page_list() returns the number of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 */
Andrew Morton1742f192006-03-22 00:08:21 -0800555static unsigned long shrink_page_list(struct list_head *page_list,
Andy Whitcroftc661b072007-08-22 14:01:26 -0700556 struct scan_control *sc,
557 enum pageout_io sync_writeback)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558{
559 LIST_HEAD(ret_pages);
560 struct pagevec freed_pvec;
561 int pgactivate = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -0800562 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563
564 cond_resched();
565
566 pagevec_init(&freed_pvec, 1);
567 while (!list_empty(page_list)) {
568 struct address_space *mapping;
569 struct page *page;
570 int may_enter_fs;
571 int referenced;
572
573 cond_resched();
574
575 page = lru_to_page(page_list);
576 list_del(&page->lru);
577
Nick Piggin529ae9a2008-08-02 12:01:03 +0200578 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 goto keep;
580
Nick Piggin725d7042006-09-25 23:30:55 -0700581 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582
583 sc->nr_scanned++;
Christoph Lameter80e43422006-02-11 17:55:53 -0800584
Nick Pigginb291f002008-10-18 20:26:44 -0700585 if (unlikely(!page_evictable(page, NULL)))
586 goto cull_mlocked;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700587
Christoph Lameter80e43422006-02-11 17:55:53 -0800588 if (!sc->may_swap && page_mapped(page))
589 goto keep_locked;
590
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 /* Double the slab pressure for mapped and swapcache pages */
592 if (page_mapped(page) || PageSwapCache(page))
593 sc->nr_scanned++;
594
Andy Whitcroftc661b072007-08-22 14:01:26 -0700595 may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
596 (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
597
598 if (PageWriteback(page)) {
599 /*
600 * Synchronous reclaim is performed in two passes,
601 * first an asynchronous pass over the list to
602 * start parallel writeback, and a second synchronous
603 * pass to wait for the IO to complete. Wait here
604 * for any page for which writeback has already
605 * started.
606 */
607 if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
608 wait_on_page_writeback(page);
Andrew Morton4dd4b922008-03-24 12:29:52 -0700609 else
Andy Whitcroftc661b072007-08-22 14:01:26 -0700610 goto keep_locked;
611 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612
Balbir Singhbed71612008-02-07 00:14:01 -0800613 referenced = page_referenced(page, 1, sc->mem_cgroup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 /* In active use or really unfreeable? Activate it. */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700615 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
616 referenced && page_mapping_inuse(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 goto activate_locked;
618
619#ifdef CONFIG_SWAP
620 /*
621 * Anonymous process memory has backing store?
622 * Try to allocate it some swap space here.
623 */
Nick Pigginb291f002008-10-18 20:26:44 -0700624 if (PageAnon(page) && !PageSwapCache(page)) {
625 switch (try_to_munlock(page)) {
626 case SWAP_FAIL: /* shouldn't happen */
627 case SWAP_AGAIN:
628 goto keep_locked;
629 case SWAP_MLOCK:
630 goto cull_mlocked;
631 case SWAP_SUCCESS:
632 ; /* fall thru'; add to swap cache */
633 }
Christoph Lameter1480a542006-01-08 01:00:53 -0800634 if (!add_to_swap(page, GFP_ATOMIC))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 goto activate_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700636 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637#endif /* CONFIG_SWAP */
638
639 mapping = page_mapping(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640
641 /*
642 * The page is mapped into the page tables of one or more
643 * processes. Try to unmap it here.
644 */
645 if (page_mapped(page) && mapping) {
Christoph Lametera48d07a2006-02-01 03:05:38 -0800646 switch (try_to_unmap(page, 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 case SWAP_FAIL:
648 goto activate_locked;
649 case SWAP_AGAIN:
650 goto keep_locked;
Nick Pigginb291f002008-10-18 20:26:44 -0700651 case SWAP_MLOCK:
652 goto cull_mlocked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 case SWAP_SUCCESS:
654 ; /* try to free the page below */
655 }
656 }
657
658 if (PageDirty(page)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700659 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 goto keep_locked;
Andrew Morton4dd4b922008-03-24 12:29:52 -0700661 if (!may_enter_fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 goto keep_locked;
Christoph Lameter52a83632006-02-01 03:05:28 -0800663 if (!sc->may_writepage)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 goto keep_locked;
665
666 /* Page is dirty, try to write it out here */
Andy Whitcroftc661b072007-08-22 14:01:26 -0700667 switch (pageout(page, mapping, sync_writeback)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 case PAGE_KEEP:
669 goto keep_locked;
670 case PAGE_ACTIVATE:
671 goto activate_locked;
672 case PAGE_SUCCESS:
Andrew Morton4dd4b922008-03-24 12:29:52 -0700673 if (PageWriteback(page) || PageDirty(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 goto keep;
675 /*
676 * A synchronous write - probably a ramdisk. Go
677 * ahead and try to reclaim the page.
678 */
Nick Piggin529ae9a2008-08-02 12:01:03 +0200679 if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 goto keep;
681 if (PageDirty(page) || PageWriteback(page))
682 goto keep_locked;
683 mapping = page_mapping(page);
684 case PAGE_CLEAN:
685 ; /* try to free the page below */
686 }
687 }
688
689 /*
690 * If the page has buffers, try to free the buffer mappings
691 * associated with this page. If we succeed we try to free
692 * the page as well.
693 *
694 * We do this even if the page is PageDirty().
695 * try_to_release_page() does not perform I/O, but it is
696 * possible for a page to have PageDirty set, but it is actually
697 * clean (all its buffers are clean). This happens if the
698 * buffers were written out directly, with submit_bh(). ext3
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700699 * will do this, as well as the blockdev mapping.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 * try_to_release_page() will discover that cleanness and will
701 * drop the buffers and mark the page clean - it can be freed.
702 *
703 * Rarely, pages can have buffers and no ->mapping. These are
704 * the pages which were not successfully invalidated in
705 * truncate_complete_page(). We try to drop those buffers here
706 * and if that worked, and the page is no longer mapped into
707 * process address space (page_count == 1) it can be freed.
708 * Otherwise, leave the page on the LRU so it is swappable.
709 */
710 if (PagePrivate(page)) {
711 if (!try_to_release_page(page, sc->gfp_mask))
712 goto activate_locked;
Nick Piggine2867812008-07-25 19:45:30 -0700713 if (!mapping && page_count(page) == 1) {
714 unlock_page(page);
715 if (put_page_testzero(page))
716 goto free_it;
717 else {
718 /*
719 * rare race with speculative reference.
720 * the speculative reference will free
721 * this page shortly, so we may
722 * increment nr_reclaimed here (and
723 * leave it off the LRU).
724 */
725 nr_reclaimed++;
726 continue;
727 }
728 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 }
730
Nick Piggine2867812008-07-25 19:45:30 -0700731 if (!mapping || !__remove_mapping(mapping, page))
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800732 goto keep_locked;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 unlock_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700735free_it:
Andrew Morton05ff5132006-03-22 00:08:20 -0800736 nr_reclaimed++;
Nick Piggine2867812008-07-25 19:45:30 -0700737 if (!pagevec_add(&freed_pvec, page)) {
738 __pagevec_free(&freed_pvec);
739 pagevec_reinit(&freed_pvec);
740 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 continue;
742
Nick Pigginb291f002008-10-18 20:26:44 -0700743cull_mlocked:
744 unlock_page(page);
745 putback_lru_page(page);
746 continue;
747
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748activate_locked:
Rik van Riel68a223942008-10-18 20:26:23 -0700749 /* Not a candidate for swapping, so reclaim swap space. */
750 if (PageSwapCache(page) && vm_swap_full())
751 remove_exclusive_swap_page_ref(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700752 VM_BUG_ON(PageActive(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 SetPageActive(page);
754 pgactivate++;
755keep_locked:
756 unlock_page(page);
757keep:
758 list_add(&page->lru, &ret_pages);
Nick Pigginb291f002008-10-18 20:26:44 -0700759 VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 }
761 list_splice(&ret_pages, page_list);
762 if (pagevec_count(&freed_pvec))
Nick Piggine2867812008-07-25 19:45:30 -0700763 __pagevec_free(&freed_pvec);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700764 count_vm_events(PGACTIVATE, pgactivate);
Andrew Morton05ff5132006-03-22 00:08:20 -0800765 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766}
767
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700768/* LRU Isolation modes. */
769#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
770#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
771#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
772
773/*
774 * Attempt to remove the specified page from its LRU. Only take this page
775 * if it is of the appropriate PageActive status. Pages which are being
776 * freed elsewhere are also ignored.
777 *
778 * page: page to consider
779 * mode: one of the LRU isolation modes defined above
780 *
781 * returns 0 on success, -ve errno on failure.
782 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700783int __isolate_lru_page(struct page *page, int mode, int file)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700784{
785 int ret = -EINVAL;
786
787 /* Only take pages on the LRU. */
788 if (!PageLRU(page))
789 return ret;
790
791 /*
792 * When checking the active state, we need to be sure we are
793 * dealing with comparible boolean values. Take the logical not
794 * of each.
795 */
796 if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
797 return ret;
798
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700799 if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file))
800 return ret;
801
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700802 /*
803 * When this function is being called for lumpy reclaim, we
804 * initially look into all LRU pages, active, inactive and
805 * unevictable; only give shrink_page_list evictable pages.
806 */
807 if (PageUnevictable(page))
808 return ret;
809
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700810 ret = -EBUSY;
811 if (likely(get_page_unless_zero(page))) {
812 /*
813 * Be careful not to clear PageLRU until after we're
814 * sure the page is not being freed elsewhere -- the
815 * page release code relies on it.
816 */
817 ClearPageLRU(page);
818 ret = 0;
819 }
820
821 return ret;
822}
823
Christoph Lameter49d2e9c2006-01-08 01:00:48 -0800824/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 * zone->lru_lock is heavily contended. Some of the functions that
826 * shrink the lists perform better by taking out a batch of pages
827 * and working on them outside the LRU lock.
828 *
829 * For pagecache intensive workloads, this function is the hottest
830 * spot in the kernel (apart from copy_*_user functions).
831 *
832 * Appropriate locks must be held before calling this function.
833 *
834 * @nr_to_scan: The number of pages to look through on the list.
835 * @src: The LRU list to pull pages off.
836 * @dst: The temp list to put pages on to.
837 * @scanned: The number of pages that were scanned.
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700838 * @order: The caller's attempted allocation order
839 * @mode: One of the LRU isolation modes
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700840 * @file: True [1] if isolating file [!anon] pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 *
842 * returns how many pages were moved onto *@dst.
843 */
Andrew Morton69e05942006-03-22 00:08:19 -0800844static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
845 struct list_head *src, struct list_head *dst,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700846 unsigned long *scanned, int order, int mode, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847{
Andrew Morton69e05942006-03-22 00:08:19 -0800848 unsigned long nr_taken = 0;
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800849 unsigned long scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
Wu Fengguangc9b02d92006-03-22 00:08:23 -0800851 for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700852 struct page *page;
853 unsigned long pfn;
854 unsigned long end_pfn;
855 unsigned long page_pfn;
856 int zone_id;
857
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 page = lru_to_page(src);
859 prefetchw_prev_lru_page(page, src, flags);
860
Nick Piggin725d7042006-09-25 23:30:55 -0700861 VM_BUG_ON(!PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800862
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700863 switch (__isolate_lru_page(page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700864 case 0:
865 list_move(&page->lru, dst);
Nick Piggin7c8ee9a2006-03-22 00:08:03 -0800866 nr_taken++;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700867 break;
Nick Piggin46453a62006-03-22 00:07:58 -0800868
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700869 case -EBUSY:
870 /* else it is being freed elsewhere */
871 list_move(&page->lru, src);
872 continue;
873
874 default:
875 BUG();
876 }
877
878 if (!order)
879 continue;
880
881 /*
882 * Attempt to take all pages in the order aligned region
883 * surrounding the tag page. Only take those pages of
884 * the same active state as that tag page. We may safely
885 * round the target page pfn down to the requested order
886 * as the mem_map is guarenteed valid out to MAX_ORDER,
887 * where that page is in a different zone we will detect
888 * it from its zone id and abort this block scan.
889 */
890 zone_id = page_zone_id(page);
891 page_pfn = page_to_pfn(page);
892 pfn = page_pfn & ~((1 << order) - 1);
893 end_pfn = pfn + (1 << order);
894 for (; pfn < end_pfn; pfn++) {
895 struct page *cursor_page;
896
897 /* The target page is in the block, ignore it. */
898 if (unlikely(pfn == page_pfn))
899 continue;
900
901 /* Avoid holes within the zone. */
902 if (unlikely(!pfn_valid_within(pfn)))
903 break;
904
905 cursor_page = pfn_to_page(pfn);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700906
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700907 /* Check that we have not crossed a zone boundary. */
908 if (unlikely(page_zone_id(cursor_page) != zone_id))
909 continue;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700910 switch (__isolate_lru_page(cursor_page, mode, file)) {
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700911 case 0:
912 list_move(&cursor_page->lru, dst);
913 nr_taken++;
914 scan++;
915 break;
916
917 case -EBUSY:
918 /* else it is being freed elsewhere */
919 list_move(&cursor_page->lru, src);
920 default:
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700921 break; /* ! on LRU or wrong list */
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700922 }
923 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 }
925
926 *scanned = scan;
927 return nr_taken;
928}
929
Balbir Singh66e17072008-02-07 00:13:56 -0800930static unsigned long isolate_pages_global(unsigned long nr,
931 struct list_head *dst,
932 unsigned long *scanned, int order,
933 int mode, struct zone *z,
934 struct mem_cgroup *mem_cont,
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700935 int active, int file)
Balbir Singh66e17072008-02-07 00:13:56 -0800936{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700937 int lru = LRU_BASE;
Balbir Singh66e17072008-02-07 00:13:56 -0800938 if (active)
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700939 lru += LRU_ACTIVE;
940 if (file)
941 lru += LRU_FILE;
942 return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
943 mode, !!file);
Balbir Singh66e17072008-02-07 00:13:56 -0800944}
945
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946/*
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700947 * clear_active_flags() is a helper for shrink_active_list(), clearing
948 * any active bits from the pages in the list.
949 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700950static unsigned long clear_active_flags(struct list_head *page_list,
951 unsigned int *count)
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700952{
953 int nr_active = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700954 int lru;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700955 struct page *page;
956
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700957 list_for_each_entry(page, page_list, lru) {
958 lru = page_is_file_cache(page);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700959 if (PageActive(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700960 lru += LRU_ACTIVE;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700961 ClearPageActive(page);
962 nr_active++;
963 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700964 count[lru]++;
965 }
Andy Whitcroft5ad333e2007-07-17 04:03:16 -0700966
967 return nr_active;
968}
969
Nick Piggin62695a82008-10-18 20:26:09 -0700970/**
971 * isolate_lru_page - tries to isolate a page from its LRU list
972 * @page: page to isolate from its LRU list
973 *
974 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
975 * vmstat statistic corresponding to whatever LRU list the page was on.
976 *
977 * Returns 0 if the page was removed from an LRU list.
978 * Returns -EBUSY if the page was not on an LRU list.
979 *
980 * The returned page will have PageLRU() cleared. If it was found on
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700981 * the active list, it will have PageActive set. If it was found on
982 * the unevictable list, it will have the PageUnevictable bit set. That flag
983 * may need to be cleared by the caller before letting the page go.
Nick Piggin62695a82008-10-18 20:26:09 -0700984 *
985 * The vmstat statistic corresponding to the list on which the page was
986 * found will be decremented.
987 *
988 * Restrictions:
989 * (1) Must be called with an elevated refcount on the page. This is a
990 * fundamentnal difference from isolate_lru_pages (which is called
991 * without a stable reference).
992 * (2) the lru_lock must not be held.
993 * (3) interrupts must be enabled.
994 */
995int isolate_lru_page(struct page *page)
996{
997 int ret = -EBUSY;
998
999 if (PageLRU(page)) {
1000 struct zone *zone = page_zone(page);
1001
1002 spin_lock_irq(&zone->lru_lock);
1003 if (PageLRU(page) && get_page_unless_zero(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001004 int lru = page_lru(page);
Nick Piggin62695a82008-10-18 20:26:09 -07001005 ret = 0;
1006 ClearPageLRU(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001007
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001008 del_page_from_lru_list(zone, page, lru);
Nick Piggin62695a82008-10-18 20:26:09 -07001009 }
1010 spin_unlock_irq(&zone->lru_lock);
1011 }
1012 return ret;
1013}
1014
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001015/*
Andrew Morton1742f192006-03-22 00:08:21 -08001016 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1017 * of reclaimed pages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 */
Andrew Morton1742f192006-03-22 00:08:21 -08001019static unsigned long shrink_inactive_list(unsigned long max_scan,
Rik van Riel33c120e2008-10-18 20:26:36 -07001020 struct zone *zone, struct scan_control *sc,
1021 int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022{
1023 LIST_HEAD(page_list);
1024 struct pagevec pvec;
Andrew Morton69e05942006-03-22 00:08:19 -08001025 unsigned long nr_scanned = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -08001026 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027
1028 pagevec_init(&pvec, 1);
1029
1030 lru_add_drain();
1031 spin_lock_irq(&zone->lru_lock);
Andrew Morton69e05942006-03-22 00:08:19 -08001032 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 struct page *page;
Andrew Morton69e05942006-03-22 00:08:19 -08001034 unsigned long nr_taken;
1035 unsigned long nr_scan;
1036 unsigned long nr_freed;
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001037 unsigned long nr_active;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001038 unsigned int count[NR_LRU_LISTS] = { 0, };
Rik van Riel33c120e2008-10-18 20:26:36 -07001039 int mode = ISOLATE_INACTIVE;
1040
1041 /*
1042 * If we need a large contiguous chunk of memory, or have
1043 * trouble getting a small set of contiguous pages, we
1044 * will reclaim both active and inactive pages.
1045 *
1046 * We use the same threshold as pageout congestion_wait below.
1047 */
1048 if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
1049 mode = ISOLATE_BOTH;
1050 else if (sc->order && priority < DEF_PRIORITY - 2)
1051 mode = ISOLATE_BOTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052
Balbir Singh66e17072008-02-07 00:13:56 -08001053 nr_taken = sc->isolate_pages(sc->swap_cluster_max,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001054 &page_list, &nr_scan, sc->order, mode,
1055 zone, sc->mem_cgroup, 0, file);
1056 nr_active = clear_active_flags(&page_list, count);
Andy Whitcrofte9187bd2007-08-22 14:01:25 -07001057 __count_vm_events(PGDEACTIVATE, nr_active);
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001058
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001059 __mod_zone_page_state(zone, NR_ACTIVE_FILE,
1060 -count[LRU_ACTIVE_FILE]);
1061 __mod_zone_page_state(zone, NR_INACTIVE_FILE,
1062 -count[LRU_INACTIVE_FILE]);
1063 __mod_zone_page_state(zone, NR_ACTIVE_ANON,
1064 -count[LRU_ACTIVE_ANON]);
1065 __mod_zone_page_state(zone, NR_INACTIVE_ANON,
1066 -count[LRU_INACTIVE_ANON]);
1067
1068 if (scan_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001069 zone->pages_scanned += nr_scan;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001070 zone->recent_scanned[0] += count[LRU_INACTIVE_ANON];
1071 zone->recent_scanned[0] += count[LRU_ACTIVE_ANON];
1072 zone->recent_scanned[1] += count[LRU_INACTIVE_FILE];
1073 zone->recent_scanned[1] += count[LRU_ACTIVE_FILE];
1074 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 spin_unlock_irq(&zone->lru_lock);
1076
Andrew Morton69e05942006-03-22 00:08:19 -08001077 nr_scanned += nr_scan;
Andy Whitcroftc661b072007-08-22 14:01:26 -07001078 nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
1079
1080 /*
1081 * If we are direct reclaiming for contiguous pages and we do
1082 * not reclaim everything in the list, try again and wait
1083 * for IO to complete. This will stall high-order allocations
1084 * but that should be acceptable to the caller
1085 */
1086 if (nr_freed < nr_taken && !current_is_kswapd() &&
1087 sc->order > PAGE_ALLOC_COSTLY_ORDER) {
1088 congestion_wait(WRITE, HZ/10);
1089
1090 /*
1091 * The attempt at page out may have made some
1092 * of the pages active, mark them inactive again.
1093 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001094 nr_active = clear_active_flags(&page_list, count);
Andy Whitcroftc661b072007-08-22 14:01:26 -07001095 count_vm_events(PGDEACTIVATE, nr_active);
1096
1097 nr_freed += shrink_page_list(&page_list, sc,
1098 PAGEOUT_IO_SYNC);
1099 }
1100
Andrew Morton05ff5132006-03-22 00:08:20 -08001101 nr_reclaimed += nr_freed;
Nick Piggina74609f2006-01-06 00:11:20 -08001102 local_irq_disable();
1103 if (current_is_kswapd()) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001104 __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);
1105 __count_vm_events(KSWAPD_STEAL, nr_freed);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001106 } else if (scan_global_lru(sc))
Christoph Lameterf8891e52006-06-30 01:55:45 -07001107 __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001108
Shantanu Goel918d3f92006-12-29 16:48:59 -08001109 __count_zone_vm_events(PGSTEAL, zone, nr_freed);
Nick Piggina74609f2006-01-06 00:11:20 -08001110
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001111 if (nr_taken == 0)
1112 goto done;
1113
Nick Piggina74609f2006-01-06 00:11:20 -08001114 spin_lock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 /*
1116 * Put back any unfreeable pages.
1117 */
1118 while (!list_empty(&page_list)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001119 int lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 page = lru_to_page(&page_list);
Nick Piggin725d7042006-09-25 23:30:55 -07001121 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 list_del(&page->lru);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001123 if (unlikely(!page_evictable(page, NULL))) {
1124 spin_unlock_irq(&zone->lru_lock);
1125 putback_lru_page(page);
1126 spin_lock_irq(&zone->lru_lock);
1127 continue;
1128 }
1129 SetPageLRU(page);
1130 lru = page_lru(page);
1131 add_page_to_lru_list(zone, page, lru);
1132 mem_cgroup_move_lists(page, lru);
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001133 if (PageActive(page) && scan_global_lru(sc)) {
1134 int file = !!page_is_file_cache(page);
1135 zone->recent_rotated[file]++;
1136 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 if (!pagevec_add(&pvec, page)) {
1138 spin_unlock_irq(&zone->lru_lock);
1139 __pagevec_release(&pvec);
1140 spin_lock_irq(&zone->lru_lock);
1141 }
1142 }
Andrew Morton69e05942006-03-22 00:08:19 -08001143 } while (nr_scanned < max_scan);
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001144 spin_unlock(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145done:
Wu Fengguangfb8d14e2006-03-22 00:08:28 -08001146 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147 pagevec_release(&pvec);
Andrew Morton05ff5132006-03-22 00:08:20 -08001148 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149}
1150
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001151/*
1152 * We are about to scan this zone at a certain priority level. If that priority
1153 * level is smaller (ie: more urgent) than the previous priority, then note
1154 * that priority level within the zone. This is done so that when the next
1155 * process comes in to scan this zone, it will immediately start out at this
1156 * priority level rather than having to build up its own scanning priority.
1157 * Here, this priority affects only the reclaim-mapped threshold.
1158 */
1159static inline void note_zone_scanning_priority(struct zone *zone, int priority)
1160{
1161 if (priority < zone->prev_priority)
1162 zone->prev_priority = priority;
1163}
1164
Nick Piggin4ff1ffb2006-09-25 23:31:28 -07001165static inline int zone_is_near_oom(struct zone *zone)
1166{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001167 return zone->pages_scanned >= (zone_lru_pages(zone) * 3);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001168}
1169
1170/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 * This moves pages from the active list to the inactive list.
1172 *
1173 * We move them the other way if the page is referenced by one or more
1174 * processes, from rmap.
1175 *
1176 * If the pages are mostly unmapped, the processing is fast and it is
1177 * appropriate to hold zone->lru_lock across the whole operation. But if
1178 * the pages are mapped, the processing is slow (page_referenced()) so we
1179 * should drop zone->lru_lock around each page. It's impossible to balance
1180 * this, so instead we remove the pages from the LRU while processing them.
1181 * It is safe to rely on PG_active against the non-LRU pages in here because
1182 * nobody will play with that bit on a non-LRU page.
1183 *
1184 * The downside is that we have to touch page->_count against each page.
1185 * But we had to alter page->flags anyway.
1186 */
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001187
1188
Andrew Morton1742f192006-03-22 00:08:21 -08001189static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001190 struct scan_control *sc, int priority, int file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191{
Andrew Morton69e05942006-03-22 00:08:19 -08001192 unsigned long pgmoved;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 int pgdeactivate = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001194 unsigned long pgscanned;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 LIST_HEAD(l_hold); /* The pages which were snipped off */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001196 LIST_HEAD(l_inactive);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 struct page *page;
1198 struct pagevec pvec;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001199 enum lru_list lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
1201 lru_add_drain();
1202 spin_lock_irq(&zone->lru_lock);
Balbir Singh66e17072008-02-07 00:13:56 -08001203 pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
1204 ISOLATE_ACTIVE, zone,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001205 sc->mem_cgroup, 1, file);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001206 /*
1207 * zone->pages_scanned is used for detect zone's oom
1208 * mem_cgroup remembers nr_scan by itself.
1209 */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001210 if (scan_global_lru(sc)) {
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001211 zone->pages_scanned += pgscanned;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001212 zone->recent_scanned[!!file] += pgmoved;
1213 }
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001214
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001215 if (file)
1216 __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
1217 else
1218 __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 spin_unlock_irq(&zone->lru_lock);
1220
Rik van Riel556adec2008-10-18 20:26:34 -07001221 pgmoved = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 while (!list_empty(&l_hold)) {
1223 cond_resched();
1224 page = lru_to_page(&l_hold);
1225 list_del(&page->lru);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001226
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001227 if (unlikely(!page_evictable(page, NULL))) {
1228 putback_lru_page(page);
1229 continue;
1230 }
1231
Rik van Riel7e9cd482008-10-18 20:26:35 -07001232 /* page_referenced clears PageReferenced */
1233 if (page_mapping_inuse(page) &&
1234 page_referenced(page, 0, sc->mem_cgroup))
1235 pgmoved++;
1236
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 list_add(&page->lru, &l_inactive);
1238 }
1239
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001240 /*
Rik van Riel7e9cd482008-10-18 20:26:35 -07001241 * Count referenced pages from currently used mappings as
1242 * rotated, even though they are moved to the inactive list.
1243 * This helps balance scan pressure between file and anonymous
1244 * pages in get_scan_ratio.
1245 */
Rik van Riel556adec2008-10-18 20:26:34 -07001246 zone->recent_rotated[!!file] += pgmoved;
1247
1248 /*
Rik van Riel7e9cd482008-10-18 20:26:35 -07001249 * Move the pages to the [file or anon] inactive list.
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001250 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 pagevec_init(&pvec, 1);
Rik van Riel7e9cd482008-10-18 20:26:35 -07001252
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 pgmoved = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001254 lru = LRU_BASE + file * LRU_FILE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 spin_lock_irq(&zone->lru_lock);
1256 while (!list_empty(&l_inactive)) {
1257 page = lru_to_page(&l_inactive);
1258 prefetchw_prev_lru_page(page, &l_inactive, flags);
Nick Piggin725d7042006-09-25 23:30:55 -07001259 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -08001260 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -07001261 VM_BUG_ON(!PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -08001262 ClearPageActive(page);
1263
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001264 list_move(&page->lru, &zone->lru[lru].list);
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001265 mem_cgroup_move_lists(page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 pgmoved++;
1267 if (!pagevec_add(&pvec, page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001268 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 spin_unlock_irq(&zone->lru_lock);
1270 pgdeactivate += pgmoved;
1271 pgmoved = 0;
1272 if (buffer_heads_over_limit)
1273 pagevec_strip(&pvec);
1274 __pagevec_release(&pvec);
1275 spin_lock_irq(&zone->lru_lock);
1276 }
1277 }
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001278 __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 pgdeactivate += pgmoved;
1280 if (buffer_heads_over_limit) {
1281 spin_unlock_irq(&zone->lru_lock);
1282 pagevec_strip(&pvec);
1283 spin_lock_irq(&zone->lru_lock);
1284 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001285 __count_zone_vm_events(PGREFILL, zone, pgscanned);
1286 __count_vm_events(PGDEACTIVATE, pgdeactivate);
1287 spin_unlock_irq(&zone->lru_lock);
Rik van Riel68a223942008-10-18 20:26:23 -07001288 if (vm_swap_full())
1289 pagevec_swap_free(&pvec);
Nick Piggina74609f2006-01-06 00:11:20 -08001290
1291 pagevec_release(&pvec);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292}
1293
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001294static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
Christoph Lameterb69408e2008-10-18 20:26:14 -07001295 struct zone *zone, struct scan_control *sc, int priority)
1296{
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001297 int file = is_file_lru(lru);
1298
Rik van Riel556adec2008-10-18 20:26:34 -07001299 if (lru == LRU_ACTIVE_FILE) {
1300 shrink_active_list(nr_to_scan, zone, sc, priority, file);
1301 return 0;
1302 }
1303
1304 if (lru == LRU_ACTIVE_ANON &&
1305 (!scan_global_lru(sc) || inactive_anon_is_low(zone))) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001306 shrink_active_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001307 return 0;
1308 }
Rik van Riel33c120e2008-10-18 20:26:36 -07001309 return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001310}
1311
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312/*
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001313 * Determine how aggressively the anon and file LRU lists should be
1314 * scanned. The relative value of each set of LRU lists is determined
1315 * by looking at the fraction of the pages scanned we did rotate back
1316 * onto the active list instead of evict.
1317 *
1318 * percent[0] specifies how much pressure to put on ram/swap backed
1319 * memory, while percent[1] determines pressure on the file LRUs.
1320 */
1321static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
1322 unsigned long *percent)
1323{
1324 unsigned long anon, file, free;
1325 unsigned long anon_prio, file_prio;
1326 unsigned long ap, fp;
1327
1328 anon = zone_page_state(zone, NR_ACTIVE_ANON) +
1329 zone_page_state(zone, NR_INACTIVE_ANON);
1330 file = zone_page_state(zone, NR_ACTIVE_FILE) +
1331 zone_page_state(zone, NR_INACTIVE_FILE);
1332 free = zone_page_state(zone, NR_FREE_PAGES);
1333
1334 /* If we have no swap space, do not bother scanning anon pages. */
1335 if (nr_swap_pages <= 0) {
1336 percent[0] = 0;
1337 percent[1] = 100;
1338 return;
1339 }
1340
1341 /* If we have very few page cache pages, force-scan anon pages. */
1342 if (unlikely(file + free <= zone->pages_high)) {
1343 percent[0] = 100;
1344 percent[1] = 0;
1345 return;
1346 }
1347
1348 /*
1349 * OK, so we have swap space and a fair amount of page cache
1350 * pages. We use the recently rotated / recently scanned
1351 * ratios to determine how valuable each cache is.
1352 *
1353 * Because workloads change over time (and to avoid overflow)
1354 * we keep these statistics as a floating average, which ends
1355 * up weighing recent references more than old ones.
1356 *
1357 * anon in [0], file in [1]
1358 */
1359 if (unlikely(zone->recent_scanned[0] > anon / 4)) {
1360 spin_lock_irq(&zone->lru_lock);
1361 zone->recent_scanned[0] /= 2;
1362 zone->recent_rotated[0] /= 2;
1363 spin_unlock_irq(&zone->lru_lock);
1364 }
1365
1366 if (unlikely(zone->recent_scanned[1] > file / 4)) {
1367 spin_lock_irq(&zone->lru_lock);
1368 zone->recent_scanned[1] /= 2;
1369 zone->recent_rotated[1] /= 2;
1370 spin_unlock_irq(&zone->lru_lock);
1371 }
1372
1373 /*
1374 * With swappiness at 100, anonymous and file have the same priority.
1375 * This scanning priority is essentially the inverse of IO cost.
1376 */
1377 anon_prio = sc->swappiness;
1378 file_prio = 200 - sc->swappiness;
1379
1380 /*
1381 * anon recent_rotated[0]
1382 * %anon = 100 * ----------- / ----------------- * IO cost
1383 * anon + file rotate_sum
1384 */
1385 ap = (anon_prio + 1) * (zone->recent_scanned[0] + 1);
1386 ap /= zone->recent_rotated[0] + 1;
1387
1388 fp = (file_prio + 1) * (zone->recent_scanned[1] + 1);
1389 fp /= zone->recent_rotated[1] + 1;
1390
1391 /* Normalize to percentages */
1392 percent[0] = 100 * ap / (ap + fp + 1);
1393 percent[1] = 100 - percent[0];
1394}
1395
1396
1397/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1399 */
Andrew Morton05ff5132006-03-22 00:08:20 -08001400static unsigned long shrink_zone(int priority, struct zone *zone,
1401 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402{
Christoph Lameterb69408e2008-10-18 20:26:14 -07001403 unsigned long nr[NR_LRU_LISTS];
Christoph Lameter86959492006-03-22 00:08:18 -08001404 unsigned long nr_to_scan;
Andrew Morton05ff5132006-03-22 00:08:20 -08001405 unsigned long nr_reclaimed = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001406 unsigned long percent[2]; /* anon @ 0; file @ 1 */
Christoph Lameterb69408e2008-10-18 20:26:14 -07001407 enum lru_list l;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001409 get_scan_ratio(zone, sc, percent);
1410
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001411 for_each_evictable_lru(l) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001412 if (scan_global_lru(sc)) {
1413 int file = is_file_lru(l);
1414 int scan;
1415 /*
1416 * Add one to nr_to_scan just to make sure that the
1417 * kernel will slowly sift through each list.
1418 */
1419 scan = zone_page_state(zone, NR_LRU_BASE + l);
1420 if (priority) {
1421 scan >>= priority;
1422 scan = (scan * percent[file]) / 100;
1423 }
1424 zone->lru[l].nr_scan += scan + 1;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001425 nr[l] = zone->lru[l].nr_scan;
1426 if (nr[l] >= sc->swap_cluster_max)
1427 zone->lru[l].nr_scan = 0;
1428 else
1429 nr[l] = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001430 } else {
1431 /*
1432 * This reclaim occurs not because zone memory shortage
1433 * but because memory controller hits its limit.
1434 * Don't modify zone reclaim related data.
1435 */
1436 nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone,
1437 priority, l);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001438 }
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001439 }
1440
Rik van Riel556adec2008-10-18 20:26:34 -07001441 while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
1442 nr[LRU_INACTIVE_FILE]) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -07001443 for_each_evictable_lru(l) {
Christoph Lameterb69408e2008-10-18 20:26:14 -07001444 if (nr[l]) {
1445 nr_to_scan = min(nr[l],
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446 (unsigned long)sc->swap_cluster_max);
Christoph Lameterb69408e2008-10-18 20:26:14 -07001447 nr[l] -= nr_to_scan;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
Christoph Lameterb69408e2008-10-18 20:26:14 -07001449 nr_reclaimed += shrink_list(l, nr_to_scan,
1450 zone, sc, priority);
1451 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 }
1453 }
1454
Rik van Riel556adec2008-10-18 20:26:34 -07001455 /*
1456 * Even if we did not try to evict anon pages at all, we want to
1457 * rebalance the anon lru active/inactive ratio.
1458 */
1459 if (!scan_global_lru(sc) || inactive_anon_is_low(zone))
1460 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1461 else if (!scan_global_lru(sc))
1462 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
1463
Andrew Morton232ea4d2007-02-28 20:13:21 -08001464 throttle_vm_writeout(sc->gfp_mask);
Andrew Morton05ff5132006-03-22 00:08:20 -08001465 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466}
1467
1468/*
1469 * This is the direct reclaim path, for page-allocating processes. We only
1470 * try to reclaim pages from zones which will satisfy the caller's allocation
1471 * request.
1472 *
1473 * We reclaim from a zone even if that zone is over pages_high. Because:
1474 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
1475 * allocation or
1476 * b) The zones may be over pages_high but they must go *over* pages_high to
1477 * satisfy the `incremental min' zone defense algorithm.
1478 *
1479 * Returns the number of reclaimed pages.
1480 *
1481 * If a zone is deemed to be full of pinned pages then just give it a light
1482 * scan then give up on it.
1483 */
Mel Gormandac1d272008-04-28 02:12:12 -07001484static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
Andrew Morton05ff5132006-03-22 00:08:20 -08001485 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486{
Mel Gorman54a6eb52008-04-28 02:12:16 -07001487 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Andrew Morton05ff5132006-03-22 00:08:20 -08001488 unsigned long nr_reclaimed = 0;
Mel Gormandd1a2392008-04-28 02:12:17 -07001489 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001490 struct zone *zone;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001491
Nick Piggin408d8542006-09-25 23:31:27 -07001492 sc->all_unreclaimable = 1;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001493 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Con Kolivasf3fe6512006-01-06 00:11:15 -08001494 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 continue;
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001496 /*
1497 * Take care memory controller reclaiming has small influence
1498 * to global LRU.
1499 */
1500 if (scan_global_lru(sc)) {
1501 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1502 continue;
1503 note_zone_scanning_priority(zone, priority);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001505 if (zone_is_all_unreclaimable(zone) &&
1506 priority != DEF_PRIORITY)
1507 continue; /* Let kswapd poll it */
1508 sc->all_unreclaimable = 0;
1509 } else {
1510 /*
1511 * Ignore cpuset limitation here. We just want to reduce
1512 * # of used pages by us regardless of memory shortage.
1513 */
1514 sc->all_unreclaimable = 0;
1515 mem_cgroup_note_reclaim_priority(sc->mem_cgroup,
1516 priority);
1517 }
Nick Piggin408d8542006-09-25 23:31:27 -07001518
Andrew Morton05ff5132006-03-22 00:08:20 -08001519 nr_reclaimed += shrink_zone(priority, zone, sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520 }
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001521
Andrew Morton05ff5132006-03-22 00:08:20 -08001522 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523}
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525/*
1526 * This is the main entry point to direct page reclaim.
1527 *
1528 * If a full scan of the inactive list fails to free enough memory then we
1529 * are "out of memory" and something needs to be killed.
1530 *
1531 * If the caller is !__GFP_FS then the probability of a failure is reasonably
1532 * high - the zone may be full of dirty or under-writeback pages, which this
1533 * caller can't do much about. We kick pdflush and take explicit naps in the
1534 * hope that some of these pages can be written. But if the allocating task
1535 * holds filesystem locks which prevent writeout this might not work, and the
1536 * allocation attempt will fail.
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07001537 *
1538 * returns: 0, if no pages reclaimed
1539 * else, the number of pages reclaimed
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 */
Mel Gormandac1d272008-04-28 02:12:12 -07001541static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
Mel Gormandd1a2392008-04-28 02:12:17 -07001542 struct scan_control *sc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543{
1544 int priority;
kosaki.motohiro@jp.fujitsu.comc700be32008-06-12 15:21:27 -07001545 unsigned long ret = 0;
Andrew Morton69e05942006-03-22 00:08:19 -08001546 unsigned long total_scanned = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -08001547 unsigned long nr_reclaimed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 struct reclaim_state *reclaim_state = current->reclaim_state;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 unsigned long lru_pages = 0;
Mel Gormandd1a2392008-04-28 02:12:17 -07001550 struct zoneref *z;
Mel Gorman54a6eb52008-04-28 02:12:16 -07001551 struct zone *zone;
Mel Gormandd1a2392008-04-28 02:12:17 -07001552 enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553
Keika Kobayashi873b4772008-07-25 01:48:52 -07001554 delayacct_freepages_start();
1555
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001556 if (scan_global_lru(sc))
1557 count_vm_event(ALLOCSTALL);
1558 /*
1559 * mem_cgroup will not do shrink_slab.
1560 */
1561 if (scan_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001562 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001564 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1565 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001567 lru_pages += zone_lru_pages(zone);
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001568 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 }
1570
1571 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
Balbir Singh66e17072008-02-07 00:13:56 -08001572 sc->nr_scanned = 0;
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001573 if (!priority)
1574 disable_swap_token();
Mel Gormandac1d272008-04-28 02:12:12 -07001575 nr_reclaimed += shrink_zones(priority, zonelist, sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001576 /*
1577 * Don't shrink slabs when reclaiming memory from
1578 * over limit cgroups
1579 */
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001580 if (scan_global_lru(sc)) {
Mel Gormandd1a2392008-04-28 02:12:17 -07001581 shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001582 if (reclaim_state) {
1583 nr_reclaimed += reclaim_state->reclaimed_slab;
1584 reclaim_state->reclaimed_slab = 0;
1585 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 }
Balbir Singh66e17072008-02-07 00:13:56 -08001587 total_scanned += sc->nr_scanned;
1588 if (nr_reclaimed >= sc->swap_cluster_max) {
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07001589 ret = nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 goto out;
1591 }
1592
1593 /*
1594 * Try to write back as many pages as we just scanned. This
1595 * tends to cause slow streaming writers to write data to the
1596 * disk smoothly, at the dirtying rate, which is nice. But
1597 * that's undesirable in laptop mode, where we *want* lumpy
1598 * writeout. So in laptop mode, write out the whole world.
1599 */
Balbir Singh66e17072008-02-07 00:13:56 -08001600 if (total_scanned > sc->swap_cluster_max +
1601 sc->swap_cluster_max / 2) {
Pekka J Enberg687a21c2005-06-28 20:44:55 -07001602 wakeup_pdflush(laptop_mode ? 0 : total_scanned);
Balbir Singh66e17072008-02-07 00:13:56 -08001603 sc->may_writepage = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 }
1605
1606 /* Take a nap, wait for some writeback to complete */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001607 if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001608 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 }
Fernando Luis Vazquez Cao87547ee2008-07-29 22:33:42 -07001610 /* top priority shrink_zones still had more to do? don't OOM, then */
KAMEZAWA Hiroyuki91a45472008-02-07 00:14:29 -08001611 if (!sc->all_unreclaimable && scan_global_lru(sc))
Nishanth Aravamudana41f24e2008-04-29 00:58:25 -07001612 ret = nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613out:
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001614 /*
1615 * Now that we've scanned all the zones at this priority level, note
1616 * that level within the zone so that the next thread which performs
1617 * scanning of this zone will immediately start out at this priority
1618 * level. This affects only the decision whether or not to bring
1619 * mapped pages onto the inactive list.
1620 */
1621 if (priority < 0)
1622 priority = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001624 if (scan_global_lru(sc)) {
Mel Gorman54a6eb52008-04-28 02:12:16 -07001625 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
KAMEZAWA Hiroyuki1cfb4192008-02-07 00:14:37 -08001627 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
1628 continue;
1629
1630 zone->prev_priority = priority;
1631 }
1632 } else
1633 mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority);
1634
Keika Kobayashi873b4772008-07-25 01:48:52 -07001635 delayacct_freepages_end();
1636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 return ret;
1638}
1639
Mel Gormandac1d272008-04-28 02:12:12 -07001640unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
1641 gfp_t gfp_mask)
Balbir Singh66e17072008-02-07 00:13:56 -08001642{
1643 struct scan_control sc = {
1644 .gfp_mask = gfp_mask,
1645 .may_writepage = !laptop_mode,
1646 .swap_cluster_max = SWAP_CLUSTER_MAX,
1647 .may_swap = 1,
1648 .swappiness = vm_swappiness,
1649 .order = order,
1650 .mem_cgroup = NULL,
1651 .isolate_pages = isolate_pages_global,
1652 };
1653
Mel Gormandd1a2392008-04-28 02:12:17 -07001654 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001655}
1656
Balbir Singh00f0b822008-03-04 14:28:39 -08001657#ifdef CONFIG_CGROUP_MEM_RES_CTLR
Balbir Singh66e17072008-02-07 00:13:56 -08001658
Balbir Singhe1a1cd52008-02-07 00:14:02 -08001659unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
1660 gfp_t gfp_mask)
Balbir Singh66e17072008-02-07 00:13:56 -08001661{
1662 struct scan_control sc = {
Balbir Singh66e17072008-02-07 00:13:56 -08001663 .may_writepage = !laptop_mode,
1664 .may_swap = 1,
1665 .swap_cluster_max = SWAP_CLUSTER_MAX,
1666 .swappiness = vm_swappiness,
1667 .order = 0,
1668 .mem_cgroup = mem_cont,
1669 .isolate_pages = mem_cgroup_isolate_pages,
1670 };
Mel Gormandac1d272008-04-28 02:12:12 -07001671 struct zonelist *zonelist;
Balbir Singh66e17072008-02-07 00:13:56 -08001672
Mel Gormandd1a2392008-04-28 02:12:17 -07001673 sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
1674 (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
1675 zonelist = NODE_DATA(numa_node_id())->node_zonelists;
1676 return do_try_to_free_pages(zonelist, &sc);
Balbir Singh66e17072008-02-07 00:13:56 -08001677}
1678#endif
1679
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680/*
1681 * For kswapd, balance_pgdat() will work across all this node's zones until
1682 * they are all at pages_high.
1683 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684 * Returns the number of pages which were actually freed.
1685 *
1686 * There is special handling here for zones which are full of pinned pages.
1687 * This can happen if the pages are all mlocked, or if they are all used by
1688 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
1689 * What we do is to detect the case where all pages in the zone have been
1690 * scanned twice and there has been zero successful reclaim. Mark the zone as
1691 * dead and from now on, only perform a short scan. Basically we're polling
1692 * the zone for when the problem goes away.
1693 *
1694 * kswapd scans the zones in the highmem->normal->dma direction. It skips
1695 * zones which have free_pages > pages_high, but once a zone is found to have
1696 * free_pages <= pages_high, we scan that zone and the lower zones regardless
1697 * of the number of free pages in the lower zones. This interoperates with
1698 * the page allocator fallback scheme to ensure that aging of pages is balanced
1699 * across the zones.
1700 */
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001701static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 int all_zones_ok;
1704 int priority;
1705 int i;
Andrew Morton69e05942006-03-22 00:08:19 -08001706 unsigned long total_scanned;
Andrew Morton05ff5132006-03-22 00:08:20 -08001707 unsigned long nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 struct reclaim_state *reclaim_state = current->reclaim_state;
Andrew Morton179e9632006-03-22 00:08:18 -08001709 struct scan_control sc = {
1710 .gfp_mask = GFP_KERNEL,
1711 .may_swap = 1,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001712 .swap_cluster_max = SWAP_CLUSTER_MAX,
1713 .swappiness = vm_swappiness,
Andy Whitcroft5ad333e2007-07-17 04:03:16 -07001714 .order = order,
Balbir Singh66e17072008-02-07 00:13:56 -08001715 .mem_cgroup = NULL,
1716 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08001717 };
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001718 /*
1719 * temp_priority is used to remember the scanning priority at which
1720 * this zone was successfully refilled to free_pages == pages_high.
1721 */
1722 int temp_priority[MAX_NR_ZONES];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723
1724loop_again:
1725 total_scanned = 0;
Andrew Morton05ff5132006-03-22 00:08:20 -08001726 nr_reclaimed = 0;
Christoph Lameterc0bbbc72006-06-11 15:22:26 -07001727 sc.may_writepage = !laptop_mode;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001728 count_vm_event(PAGEOUTRUN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001730 for (i = 0; i < pgdat->nr_zones; i++)
1731 temp_priority[i] = DEF_PRIORITY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732
1733 for (priority = DEF_PRIORITY; priority >= 0; priority--) {
1734 int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
1735 unsigned long lru_pages = 0;
1736
Rik van Rielf7b7fd82005-11-28 13:44:07 -08001737 /* The swap token gets in the way of swapout... */
1738 if (!priority)
1739 disable_swap_token();
1740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 all_zones_ok = 1;
1742
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001743 /*
1744 * Scan in the highmem->dma direction for the highest
1745 * zone which needs scanning
1746 */
1747 for (i = pgdat->nr_zones - 1; i >= 0; i--) {
1748 struct zone *zone = pgdat->node_zones + i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001750 if (!populated_zone(zone))
1751 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752
David Rientjese815af92007-10-16 23:25:54 -07001753 if (zone_is_all_unreclaimable(zone) &&
1754 priority != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001755 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756
Rik van Riel556adec2008-10-18 20:26:34 -07001757 /*
1758 * Do some background aging of the anon list, to give
1759 * pages a chance to be referenced before reclaiming.
1760 */
1761 if (inactive_anon_is_low(zone))
1762 shrink_active_list(SWAP_CLUSTER_MAX, zone,
1763 &sc, priority, 0);
1764
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001765 if (!zone_watermark_ok(zone, order, zone->pages_high,
1766 0, 0)) {
1767 end_zone = i;
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001768 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 }
Andrew Mortone1dbeda2006-12-06 20:32:01 -08001771 if (i < 0)
1772 goto out;
1773
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 for (i = 0; i <= end_zone; i++) {
1775 struct zone *zone = pgdat->node_zones + i;
1776
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001777 lru_pages += zone_lru_pages(zone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 }
1779
1780 /*
1781 * Now scan the zone in the dma->highmem direction, stopping
1782 * at the last zone which needs scanning.
1783 *
1784 * We do this because the page allocator works in the opposite
1785 * direction. This prevents the page allocator from allocating
1786 * pages behind kswapd's direction of progress, which would
1787 * cause too much scanning of the lower zones.
1788 */
1789 for (i = 0; i <= end_zone; i++) {
1790 struct zone *zone = pgdat->node_zones + i;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001791 int nr_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792
Con Kolivasf3fe6512006-01-06 00:11:15 -08001793 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 continue;
1795
David Rientjese815af92007-10-16 23:25:54 -07001796 if (zone_is_all_unreclaimable(zone) &&
1797 priority != DEF_PRIORITY)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 continue;
1799
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001800 if (!zone_watermark_ok(zone, order, zone->pages_high,
1801 end_zone, 0))
1802 all_zones_ok = 0;
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001803 temp_priority[i] = priority;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 sc.nr_scanned = 0;
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001805 note_zone_scanning_priority(zone, priority);
Rik van Riel32a43302007-10-16 01:24:50 -07001806 /*
1807 * We put equal pressure on every zone, unless one
1808 * zone has way too many pages free already.
1809 */
1810 if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
1811 end_zone, 0))
1812 nr_reclaimed += shrink_zone(priority, zone, &sc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 reclaim_state->reclaimed_slab = 0;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001814 nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
1815 lru_pages);
Andrew Morton05ff5132006-03-22 00:08:20 -08001816 nr_reclaimed += reclaim_state->reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817 total_scanned += sc.nr_scanned;
David Rientjese815af92007-10-16 23:25:54 -07001818 if (zone_is_all_unreclaimable(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819 continue;
akpm@osdl.orgb15e0902005-06-21 17:14:35 -07001820 if (nr_slab == 0 && zone->pages_scanned >=
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001821 (zone_lru_pages(zone) * 6))
David Rientjese815af92007-10-16 23:25:54 -07001822 zone_set_flag(zone,
1823 ZONE_ALL_UNRECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001824 /*
1825 * If we've done a decent amount of scanning and
1826 * the reclaim ratio is low, start doing writepage
1827 * even in laptop mode
1828 */
1829 if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
Andrew Morton05ff5132006-03-22 00:08:20 -08001830 total_scanned > nr_reclaimed + nr_reclaimed / 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 sc.may_writepage = 1;
1832 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 if (all_zones_ok)
1834 break; /* kswapd: all done */
1835 /*
1836 * OK, kswapd is getting into trouble. Take a nap, then take
1837 * another pass across the zones.
1838 */
Andrew Morton4dd4b922008-03-24 12:29:52 -07001839 if (total_scanned && priority < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07001840 congestion_wait(WRITE, HZ/10);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841
1842 /*
1843 * We do this so kswapd doesn't build up large priorities for
1844 * example when it is freeing in parallel with allocators. It
1845 * matches the direct reclaim path behaviour in terms of impact
1846 * on zone->*_priority.
1847 */
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001848 if (nr_reclaimed >= SWAP_CLUSTER_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 break;
1850 }
1851out:
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001852 /*
1853 * Note within each zone the priority level at which this zone was
1854 * brought into a happy state. So that the next thread which scans this
1855 * zone will start out at that priority level.
1856 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 for (i = 0; i < pgdat->nr_zones; i++) {
1858 struct zone *zone = pgdat->node_zones + i;
1859
Martin Bligh3bb1a8522006-10-28 10:38:24 -07001860 zone->prev_priority = temp_priority[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861 }
1862 if (!all_zones_ok) {
1863 cond_resched();
Rafael J. Wysocki83573762006-12-06 20:34:18 -08001864
1865 try_to_freeze();
1866
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 goto loop_again;
1868 }
1869
Andrew Morton05ff5132006-03-22 00:08:20 -08001870 return nr_reclaimed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871}
1872
1873/*
1874 * The background pageout daemon, started as a kernel thread
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001875 * from the init process.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 *
1877 * This basically trickles out pages so that we have _some_
1878 * free memory available even if there is no other activity
1879 * that frees anything up. This is needed for things like routing
1880 * etc, where we otherwise might have all activity going on in
1881 * asynchronous contexts that cannot page things out.
1882 *
1883 * If there are applications that are active memory-allocators
1884 * (most normal use), this basically shouldn't matter.
1885 */
1886static int kswapd(void *p)
1887{
1888 unsigned long order;
1889 pg_data_t *pgdat = (pg_data_t*)p;
1890 struct task_struct *tsk = current;
1891 DEFINE_WAIT(wait);
1892 struct reclaim_state reclaim_state = {
1893 .reclaimed_slab = 0,
1894 };
Mike Travisc5f59f02008-04-04 18:11:10 -07001895 node_to_cpumask_ptr(cpumask, pgdat->node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
Mike Travisc5f59f02008-04-04 18:11:10 -07001897 if (!cpus_empty(*cpumask))
1898 set_cpus_allowed_ptr(tsk, cpumask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 current->reclaim_state = &reclaim_state;
1900
1901 /*
1902 * Tell the memory management that we're a "memory allocator",
1903 * and that if we need more memory we should get access to it
1904 * regardless (see "__alloc_pages()"). "kswapd" should
1905 * never get caught in the normal page freeing logic.
1906 *
1907 * (Kswapd normally doesn't need memory anyway, but sometimes
1908 * you need a small amount of memory in order to be able to
1909 * page out something else, and this flag essentially protects
1910 * us from recursively trying to free more memory as we're
1911 * trying to free the first piece of memory in the first place).
1912 */
Christoph Lameter930d9152006-01-08 01:00:47 -08001913 tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
Rafael J. Wysocki83144182007-07-17 04:03:35 -07001914 set_freezable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915
1916 order = 0;
1917 for ( ; ; ) {
1918 unsigned long new_order;
Christoph Lameter3e1d1d22005-06-24 23:13:50 -07001919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
1921 new_order = pgdat->kswapd_max_order;
1922 pgdat->kswapd_max_order = 0;
1923 if (order < new_order) {
1924 /*
1925 * Don't sleep if someone wants a larger 'order'
1926 * allocation
1927 */
1928 order = new_order;
1929 } else {
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07001930 if (!freezing(current))
1931 schedule();
1932
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 order = pgdat->kswapd_max_order;
1934 }
1935 finish_wait(&pgdat->kswapd_wait, &wait);
1936
Rafael J. Wysockib1296cc2007-05-06 14:50:48 -07001937 if (!try_to_freeze()) {
1938 /* We can speed up thawing tasks if we don't call
1939 * balance_pgdat after returning from the refrigerator
1940 */
1941 balance_pgdat(pgdat, order);
1942 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 }
1944 return 0;
1945}
1946
1947/*
1948 * A zone is low on free memory, so wake its kswapd task to service it.
1949 */
1950void wakeup_kswapd(struct zone *zone, int order)
1951{
1952 pg_data_t *pgdat;
1953
Con Kolivasf3fe6512006-01-06 00:11:15 -08001954 if (!populated_zone(zone))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 return;
1956
1957 pgdat = zone->zone_pgdat;
Rohit Seth7fb1d9f2005-11-13 16:06:43 -08001958 if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959 return;
1960 if (pgdat->kswapd_max_order < order)
1961 pgdat->kswapd_max_order = order;
Paul Jackson02a0e532006-12-13 00:34:25 -08001962 if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07001964 if (!waitqueue_active(&pgdat->kswapd_wait))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965 return;
Con Kolivas8d0986e2005-09-13 01:25:07 -07001966 wake_up_interruptible(&pgdat->kswapd_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967}
1968
Rik van Riel4f98a2f2008-10-18 20:26:32 -07001969unsigned long global_lru_pages(void)
1970{
1971 return global_page_state(NR_ACTIVE_ANON)
1972 + global_page_state(NR_ACTIVE_FILE)
1973 + global_page_state(NR_INACTIVE_ANON)
1974 + global_page_state(NR_INACTIVE_FILE);
1975}
1976
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977#ifdef CONFIG_PM
1978/*
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001979 * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages
1980 * from LRU lists system-wide, for given pass and priority, and returns the
1981 * number of reclaimed pages
1982 *
1983 * For pass > 3 we also try to shrink the LRU lists that contain a few pages
1984 */
Nigel Cunninghame07aa052006-12-22 01:07:21 -08001985static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
1986 int pass, struct scan_control *sc)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001987{
1988 struct zone *zone;
1989 unsigned long nr_to_scan, ret = 0;
Christoph Lameterb69408e2008-10-18 20:26:14 -07001990 enum lru_list l;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001991
1992 for_each_zone(zone) {
1993
1994 if (!populated_zone(zone))
1995 continue;
1996
David Rientjese815af92007-10-16 23:25:54 -07001997 if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07001998 continue;
1999
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002000 for_each_evictable_lru(l) {
2001 /* For pass = 0, we don't shrink the active list */
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002002 if (pass == 0 &&
2003 (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE))
Christoph Lameterb69408e2008-10-18 20:26:14 -07002004 continue;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002005
Christoph Lameterb69408e2008-10-18 20:26:14 -07002006 zone->lru[l].nr_scan +=
2007 (zone_page_state(zone, NR_LRU_BASE + l)
2008 >> prio) + 1;
2009 if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
2010 zone->lru[l].nr_scan = 0;
2011 nr_to_scan = min(nr_pages,
2012 zone_page_state(zone,
2013 NR_LRU_BASE + l));
2014 ret += shrink_list(l, nr_to_scan, zone,
2015 sc, prio);
2016 if (ret >= nr_pages)
2017 return ret;
2018 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002019 }
2020 }
2021
2022 return ret;
2023}
2024
2025/*
2026 * Try to free `nr_pages' of memory, system-wide, and return the number of
2027 * freed pages.
2028 *
2029 * Rather than trying to age LRUs the aim is to preserve the overall
2030 * LRU order by reclaiming preferentially
2031 * inactive > active > active referenced > active mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 */
Andrew Morton69e05942006-03-22 00:08:19 -08002033unsigned long shrink_all_memory(unsigned long nr_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002034{
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002035 unsigned long lru_pages, nr_slab;
Andrew Morton69e05942006-03-22 00:08:19 -08002036 unsigned long ret = 0;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002037 int pass;
2038 struct reclaim_state reclaim_state;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002039 struct scan_control sc = {
2040 .gfp_mask = GFP_KERNEL,
2041 .may_swap = 0,
2042 .swap_cluster_max = nr_pages,
2043 .may_writepage = 1,
2044 .swappiness = vm_swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002045 .isolate_pages = isolate_pages_global,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002046 };
2047
2048 current->reclaim_state = &reclaim_state;
Andrew Morton69e05942006-03-22 00:08:19 -08002049
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002050 lru_pages = global_lru_pages();
Christoph Lameter972d1a72006-09-25 23:31:51 -07002051 nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002052 /* If slab caches are huge, it's better to hit them first */
2053 while (nr_slab >= lru_pages) {
2054 reclaim_state.reclaimed_slab = 0;
2055 shrink_slab(nr_pages, sc.gfp_mask, lru_pages);
2056 if (!reclaim_state.reclaimed_slab)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 break;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002058
2059 ret += reclaim_state.reclaimed_slab;
2060 if (ret >= nr_pages)
2061 goto out;
2062
2063 nr_slab -= reclaim_state.reclaimed_slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002065
2066 /*
2067 * We try to shrink LRUs in 5 passes:
2068 * 0 = Reclaim from inactive_list only
2069 * 1 = Reclaim from active list but don't reclaim mapped
2070 * 2 = 2nd pass of type 1
2071 * 3 = Reclaim mapped (normal reclaim)
2072 * 4 = 2nd pass of type 3
2073 */
2074 for (pass = 0; pass < 5; pass++) {
2075 int prio;
2076
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002077 /* Force reclaiming mapped pages in the passes #3 and #4 */
2078 if (pass > 2) {
2079 sc.may_swap = 1;
2080 sc.swappiness = 100;
2081 }
2082
2083 for (prio = DEF_PRIORITY; prio >= 0; prio--) {
2084 unsigned long nr_to_scan = nr_pages - ret;
2085
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002086 sc.nr_scanned = 0;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002087 ret += shrink_all_zones(nr_to_scan, prio, pass, &sc);
2088 if (ret >= nr_pages)
2089 goto out;
2090
2091 reclaim_state.reclaimed_slab = 0;
Andrew Morton76395d32007-01-05 16:37:05 -08002092 shrink_slab(sc.nr_scanned, sc.gfp_mask,
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002093 global_lru_pages());
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002094 ret += reclaim_state.reclaimed_slab;
2095 if (ret >= nr_pages)
2096 goto out;
2097
2098 if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
Andrew Morton3fcfab12006-10-19 23:28:16 -07002099 congestion_wait(WRITE, HZ / 10);
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002100 }
Rafael J. Wysocki248a0302006-03-22 00:09:04 -08002101 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002102
2103 /*
2104 * If ret = 0, we could not shrink LRUs, but there may be something
2105 * in slab caches
2106 */
Andrew Morton76395d32007-01-05 16:37:05 -08002107 if (!ret) {
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002108 do {
2109 reclaim_state.reclaimed_slab = 0;
Rik van Riel4f98a2f2008-10-18 20:26:32 -07002110 shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002111 ret += reclaim_state.reclaimed_slab;
2112 } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
Andrew Morton76395d32007-01-05 16:37:05 -08002113 }
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002114
2115out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002116 current->reclaim_state = NULL;
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002117
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 return ret;
2119}
2120#endif
2121
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122/* It's optimal to keep kswapds on the same CPUs as their memory, but
2123 not required for correctness. So if the last cpu in a node goes
2124 away, we get changed to run anywhere: as the first one comes back,
2125 restore their cpu bindings. */
Chandra Seetharaman9c7b2162006-06-27 02:54:07 -07002126static int __devinit cpu_callback(struct notifier_block *nfb,
Andrew Morton69e05942006-03-22 00:08:19 -08002127 unsigned long action, void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128{
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002129 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002131 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
Yasunori Goto58c0a4a2007-10-16 01:25:40 -07002132 for_each_node_state(nid, N_HIGH_MEMORY) {
Mike Travisc5f59f02008-04-04 18:11:10 -07002133 pg_data_t *pgdat = NODE_DATA(nid);
2134 node_to_cpumask_ptr(mask, pgdat->node_id);
2135
2136 if (any_online_cpu(*mask) < nr_cpu_ids)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 /* One of our CPUs online: restore mask */
Mike Travisc5f59f02008-04-04 18:11:10 -07002138 set_cpus_allowed_ptr(pgdat->kswapd, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 }
2140 }
2141 return NOTIFY_OK;
2142}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
Yasunori Goto3218ae12006-06-27 02:53:33 -07002144/*
2145 * This kswapd start function will be called by init and node-hot-add.
2146 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
2147 */
2148int kswapd_run(int nid)
2149{
2150 pg_data_t *pgdat = NODE_DATA(nid);
2151 int ret = 0;
2152
2153 if (pgdat->kswapd)
2154 return 0;
2155
2156 pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
2157 if (IS_ERR(pgdat->kswapd)) {
2158 /* failure at boot is fatal */
2159 BUG_ON(system_state == SYSTEM_BOOTING);
2160 printk("Failed to start kswapd on node %d\n",nid);
2161 ret = -1;
2162 }
2163 return ret;
2164}
2165
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166static int __init kswapd_init(void)
2167{
Yasunori Goto3218ae12006-06-27 02:53:33 -07002168 int nid;
Andrew Morton69e05942006-03-22 00:08:19 -08002169
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 swap_setup();
Christoph Lameter9422ffb2007-10-16 01:25:31 -07002171 for_each_node_state(nid, N_HIGH_MEMORY)
Yasunori Goto3218ae12006-06-27 02:53:33 -07002172 kswapd_run(nid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173 hotcpu_notifier(cpu_callback, 0);
2174 return 0;
2175}
2176
2177module_init(kswapd_init)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002178
2179#ifdef CONFIG_NUMA
2180/*
2181 * Zone reclaim mode
2182 *
2183 * If non-zero call zone_reclaim when the number of free pages falls below
2184 * the watermarks.
Christoph Lameter9eeff232006-01-18 17:42:31 -08002185 */
2186int zone_reclaim_mode __read_mostly;
2187
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002188#define RECLAIM_OFF 0
Fernando Luis Vazquez Cao7d034312008-07-29 22:33:41 -07002189#define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
Christoph Lameter1b2ffb72006-02-01 03:05:34 -08002190#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
2191#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
2192
Christoph Lameter9eeff232006-01-18 17:42:31 -08002193/*
Christoph Lametera92f7122006-02-01 03:05:32 -08002194 * Priority for ZONE_RECLAIM. This determines the fraction of pages
2195 * of a node considered for each zone_reclaim. 4 scans 1/16th of
2196 * a zone.
2197 */
2198#define ZONE_RECLAIM_PRIORITY 4
2199
Christoph Lameter9eeff232006-01-18 17:42:31 -08002200/*
Christoph Lameter96146342006-07-03 00:24:13 -07002201 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
2202 * occur.
2203 */
2204int sysctl_min_unmapped_ratio = 1;
2205
2206/*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002207 * If the number of slab pages in a zone grows beyond this percentage then
2208 * slab reclaim needs to occur.
2209 */
2210int sysctl_min_slab_ratio = 5;
2211
2212/*
Christoph Lameter9eeff232006-01-18 17:42:31 -08002213 * Try to free up some pages from this zone through reclaim.
2214 */
Andrew Morton179e9632006-03-22 00:08:18 -08002215static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
Christoph Lameter9eeff232006-01-18 17:42:31 -08002216{
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002217 /* Minimum pages needed in order to stay on node */
Andrew Morton69e05942006-03-22 00:08:19 -08002218 const unsigned long nr_pages = 1 << order;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002219 struct task_struct *p = current;
2220 struct reclaim_state reclaim_state;
Christoph Lameter86959492006-03-22 00:08:18 -08002221 int priority;
Andrew Morton05ff5132006-03-22 00:08:20 -08002222 unsigned long nr_reclaimed = 0;
Andrew Morton179e9632006-03-22 00:08:18 -08002223 struct scan_control sc = {
2224 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
2225 .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
Andrew Morton69e05942006-03-22 00:08:19 -08002226 .swap_cluster_max = max_t(unsigned long, nr_pages,
2227 SWAP_CLUSTER_MAX),
Andrew Morton179e9632006-03-22 00:08:18 -08002228 .gfp_mask = gfp_mask,
Rafael J. Wysockid6277db2006-06-23 02:03:18 -07002229 .swappiness = vm_swappiness,
Balbir Singh66e17072008-02-07 00:13:56 -08002230 .isolate_pages = isolate_pages_global,
Andrew Morton179e9632006-03-22 00:08:18 -08002231 };
Christoph Lameter83e33a42006-09-25 23:31:53 -07002232 unsigned long slab_reclaimable;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002233
2234 disable_swap_token();
Christoph Lameter9eeff232006-01-18 17:42:31 -08002235 cond_resched();
Christoph Lameterd4f77962006-02-24 13:04:22 -08002236 /*
2237 * We need to be able to allocate from the reserves for RECLAIM_SWAP
2238 * and we also need to be able to write out pages for RECLAIM_WRITE
2239 * and RECLAIM_SWAP.
2240 */
2241 p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002242 reclaim_state.reclaimed_slab = 0;
2243 p->reclaim_state = &reclaim_state;
Christoph Lameterc84db232006-02-01 03:05:29 -08002244
Christoph Lameter0ff38492006-09-25 23:31:52 -07002245 if (zone_page_state(zone, NR_FILE_PAGES) -
2246 zone_page_state(zone, NR_FILE_MAPPED) >
2247 zone->min_unmapped_pages) {
2248 /*
2249 * Free memory by calling shrink zone with increasing
2250 * priorities until we have enough memory freed.
2251 */
2252 priority = ZONE_RECLAIM_PRIORITY;
2253 do {
Martin Bligh3bb1a8522006-10-28 10:38:24 -07002254 note_zone_scanning_priority(zone, priority);
Christoph Lameter0ff38492006-09-25 23:31:52 -07002255 nr_reclaimed += shrink_zone(priority, zone, &sc);
2256 priority--;
2257 } while (priority >= 0 && nr_reclaimed < nr_pages);
2258 }
Christoph Lameterc84db232006-02-01 03:05:29 -08002259
Christoph Lameter83e33a42006-09-25 23:31:53 -07002260 slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
2261 if (slab_reclaimable > zone->min_slab_pages) {
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002262 /*
Christoph Lameter7fb2d462006-03-22 00:08:22 -08002263 * shrink_slab() does not currently allow us to determine how
Christoph Lameter0ff38492006-09-25 23:31:52 -07002264 * many pages were freed in this zone. So we take the current
2265 * number of slab pages and shake the slab until it is reduced
2266 * by the same nr_pages that we used for reclaiming unmapped
2267 * pages.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002268 *
Christoph Lameter0ff38492006-09-25 23:31:52 -07002269 * Note that shrink_slab will free memory on all zones and may
2270 * take a long time.
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002271 */
Christoph Lameter0ff38492006-09-25 23:31:52 -07002272 while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
Christoph Lameter83e33a42006-09-25 23:31:53 -07002273 zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
2274 slab_reclaimable - nr_pages)
Christoph Lameter0ff38492006-09-25 23:31:52 -07002275 ;
Christoph Lameter83e33a42006-09-25 23:31:53 -07002276
2277 /*
2278 * Update nr_reclaimed by the number of slab pages we
2279 * reclaimed from this zone.
2280 */
2281 nr_reclaimed += slab_reclaimable -
2282 zone_page_state(zone, NR_SLAB_RECLAIMABLE);
Christoph Lameter2a16e3f2006-02-01 03:05:35 -08002283 }
2284
Christoph Lameter9eeff232006-01-18 17:42:31 -08002285 p->reclaim_state = NULL;
Christoph Lameterd4f77962006-02-24 13:04:22 -08002286 current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
Andrew Morton05ff5132006-03-22 00:08:20 -08002287 return nr_reclaimed >= nr_pages;
Christoph Lameter9eeff232006-01-18 17:42:31 -08002288}
Andrew Morton179e9632006-03-22 00:08:18 -08002289
2290int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
2291{
Andrew Morton179e9632006-03-22 00:08:18 -08002292 int node_id;
David Rientjesd773ed62007-10-16 23:26:01 -07002293 int ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002294
2295 /*
Christoph Lameter0ff38492006-09-25 23:31:52 -07002296 * Zone reclaim reclaims unmapped file backed pages and
2297 * slab pages if we are over the defined limits.
Christoph Lameter34aa1332006-06-30 01:55:37 -07002298 *
Christoph Lameter96146342006-07-03 00:24:13 -07002299 * A small portion of unmapped file backed pages is needed for
2300 * file I/O otherwise pages read by file I/O will be immediately
2301 * thrown out if the zone is overallocated. So we do not reclaim
2302 * if less than a specified percentage of the zone is used by
2303 * unmapped file backed pages.
Andrew Morton179e9632006-03-22 00:08:18 -08002304 */
Christoph Lameter34aa1332006-06-30 01:55:37 -07002305 if (zone_page_state(zone, NR_FILE_PAGES) -
Christoph Lameter0ff38492006-09-25 23:31:52 -07002306 zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages
2307 && zone_page_state(zone, NR_SLAB_RECLAIMABLE)
2308 <= zone->min_slab_pages)
Christoph Lameter96146342006-07-03 00:24:13 -07002309 return 0;
Andrew Morton179e9632006-03-22 00:08:18 -08002310
David Rientjesd773ed62007-10-16 23:26:01 -07002311 if (zone_is_all_unreclaimable(zone))
2312 return 0;
2313
Andrew Morton179e9632006-03-22 00:08:18 -08002314 /*
David Rientjesd773ed62007-10-16 23:26:01 -07002315 * Do not scan if the allocation should not be delayed.
Andrew Morton179e9632006-03-22 00:08:18 -08002316 */
David Rientjesd773ed62007-10-16 23:26:01 -07002317 if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC))
Andrew Morton179e9632006-03-22 00:08:18 -08002318 return 0;
2319
2320 /*
2321 * Only run zone reclaim on the local zone or on zones that do not
2322 * have associated processors. This will favor the local processor
2323 * over remote processors and spread off node memory allocations
2324 * as wide as possible.
2325 */
Christoph Lameter89fa3022006-09-25 23:31:55 -07002326 node_id = zone_to_nid(zone);
Christoph Lameter37c07082007-10-16 01:25:36 -07002327 if (node_state(node_id, N_CPU) && node_id != numa_node_id())
Andrew Morton179e9632006-03-22 00:08:18 -08002328 return 0;
David Rientjesd773ed62007-10-16 23:26:01 -07002329
2330 if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
2331 return 0;
2332 ret = __zone_reclaim(zone, gfp_mask, order);
2333 zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
2334
2335 return ret;
Andrew Morton179e9632006-03-22 00:08:18 -08002336}
Christoph Lameter9eeff232006-01-18 17:42:31 -08002337#endif
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002338
2339#ifdef CONFIG_UNEVICTABLE_LRU
2340/*
2341 * page_evictable - test whether a page is evictable
2342 * @page: the page to test
2343 * @vma: the VMA in which the page is or will be mapped, may be NULL
2344 *
2345 * Test whether page is evictable--i.e., should be placed on active/inactive
Nick Pigginb291f002008-10-18 20:26:44 -07002346 * lists vs unevictable list. The vma argument is !NULL when called from the
2347 * fault path to determine how to instantate a new page.
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002348 *
2349 * Reasons page might not be evictable:
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002350 * (1) page's mapping marked unevictable
Nick Pigginb291f002008-10-18 20:26:44 -07002351 * (2) page is part of an mlocked VMA
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002352 *
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002353 */
2354int page_evictable(struct page *page, struct vm_area_struct *vma)
2355{
2356
Lee Schermerhornba9ddf42008-10-18 20:26:42 -07002357 if (mapping_unevictable(page_mapping(page)))
2358 return 0;
2359
Nick Pigginb291f002008-10-18 20:26:44 -07002360 if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page)))
2361 return 0;
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002362
2363 return 1;
2364}
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07002365
2366/**
2367 * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
2368 * @page: page to check evictability and move to appropriate lru list
2369 * @zone: zone page is in
2370 *
2371 * Checks a page for evictability and moves the page to the appropriate
2372 * zone lru list.
2373 *
2374 * Restrictions: zone->lru_lock must be held, page must be on LRU and must
2375 * have PageUnevictable set.
2376 */
2377static void check_move_unevictable_page(struct page *page, struct zone *zone)
2378{
2379 VM_BUG_ON(PageActive(page));
2380
2381retry:
2382 ClearPageUnevictable(page);
2383 if (page_evictable(page, NULL)) {
2384 enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page);
2385 __dec_zone_state(zone, NR_UNEVICTABLE);
2386 list_move(&page->lru, &zone->lru[l].list);
2387 __inc_zone_state(zone, NR_INACTIVE_ANON + l);
2388 __count_vm_event(UNEVICTABLE_PGRESCUED);
2389 } else {
2390 /*
2391 * rotate unevictable list
2392 */
2393 SetPageUnevictable(page);
2394 list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
2395 if (page_evictable(page, NULL))
2396 goto retry;
2397 }
2398}
2399
2400/**
2401 * scan_mapping_unevictable_pages - scan an address space for evictable pages
2402 * @mapping: struct address_space to scan for evictable pages
2403 *
2404 * Scan all pages in mapping. Check unevictable pages for
2405 * evictability and move them to the appropriate zone lru list.
2406 */
2407void scan_mapping_unevictable_pages(struct address_space *mapping)
2408{
2409 pgoff_t next = 0;
2410 pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >>
2411 PAGE_CACHE_SHIFT;
2412 struct zone *zone;
2413 struct pagevec pvec;
2414
2415 if (mapping->nrpages == 0)
2416 return;
2417
2418 pagevec_init(&pvec, 0);
2419 while (next < end &&
2420 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
2421 int i;
2422 int pg_scanned = 0;
2423
2424 zone = NULL;
2425
2426 for (i = 0; i < pagevec_count(&pvec); i++) {
2427 struct page *page = pvec.pages[i];
2428 pgoff_t page_index = page->index;
2429 struct zone *pagezone = page_zone(page);
2430
2431 pg_scanned++;
2432 if (page_index > next)
2433 next = page_index;
2434 next++;
2435
2436 if (pagezone != zone) {
2437 if (zone)
2438 spin_unlock_irq(&zone->lru_lock);
2439 zone = pagezone;
2440 spin_lock_irq(&zone->lru_lock);
2441 }
2442
2443 if (PageLRU(page) && PageUnevictable(page))
2444 check_move_unevictable_page(page, zone);
2445 }
2446 if (zone)
2447 spin_unlock_irq(&zone->lru_lock);
2448 pagevec_release(&pvec);
2449
2450 count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
2451 }
2452
2453}
Lee Schermerhorn894bc312008-10-18 20:26:39 -07002454#endif