Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #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> | |
248a0301 | 37 | #include <linux/delay.h> |
3218ae14 | 38 | #include <linux/kthread.h> |
7dfb7103 | 39 | #include <linux/freezer.h> |
66e1707b | 40 | #include <linux/memcontrol.h> |
873b4771 | 41 | #include <linux/delayacct.h> |
af936a16 | 42 | #include <linux/sysctl.h> |
1da177e4 LT |
43 | |
44 | #include <asm/tlbflush.h> | |
45 | #include <asm/div64.h> | |
46 | ||
47 | #include <linux/swapops.h> | |
48 | ||
0f8053a5 NP |
49 | #include "internal.h" |
50 | ||
1da177e4 | 51 | struct scan_control { |
1da177e4 LT |
52 | /* Incremented by the number of inactive pages that were scanned */ |
53 | unsigned long nr_scanned; | |
54 | ||
a79311c1 RR |
55 | /* Number of pages freed so far during a call to shrink_zones() */ |
56 | unsigned long nr_reclaimed; | |
57 | ||
1da177e4 | 58 | /* This context's GFP mask */ |
6daa0e28 | 59 | gfp_t gfp_mask; |
1da177e4 LT |
60 | |
61 | int may_writepage; | |
62 | ||
f1fd1067 CL |
63 | /* Can pages be swapped as part of reclaim? */ |
64 | int may_swap; | |
65 | ||
1da177e4 LT |
66 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
67 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
68 | * In this context, it doesn't matter that we scan the | |
69 | * whole list at once. */ | |
70 | int swap_cluster_max; | |
d6277db4 RW |
71 | |
72 | int swappiness; | |
408d8544 NP |
73 | |
74 | int all_unreclaimable; | |
5ad333eb AW |
75 | |
76 | int order; | |
66e1707b BS |
77 | |
78 | /* Which cgroup do we reclaim from */ | |
79 | struct mem_cgroup *mem_cgroup; | |
80 | ||
81 | /* Pluggable isolate pages callback */ | |
82 | unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst, | |
83 | unsigned long *scanned, int order, int mode, | |
84 | struct zone *z, struct mem_cgroup *mem_cont, | |
4f98a2fe | 85 | int active, int file); |
1da177e4 LT |
86 | }; |
87 | ||
1da177e4 LT |
88 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
89 | ||
90 | #ifdef ARCH_HAS_PREFETCH | |
91 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
92 | do { \ | |
93 | if ((_page)->lru.prev != _base) { \ | |
94 | struct page *prev; \ | |
95 | \ | |
96 | prev = lru_to_page(&(_page->lru)); \ | |
97 | prefetch(&prev->_field); \ | |
98 | } \ | |
99 | } while (0) | |
100 | #else | |
101 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
102 | #endif | |
103 | ||
104 | #ifdef ARCH_HAS_PREFETCHW | |
105 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
106 | do { \ | |
107 | if ((_page)->lru.prev != _base) { \ | |
108 | struct page *prev; \ | |
109 | \ | |
110 | prev = lru_to_page(&(_page->lru)); \ | |
111 | prefetchw(&prev->_field); \ | |
112 | } \ | |
113 | } while (0) | |
114 | #else | |
115 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
116 | #endif | |
117 | ||
118 | /* | |
119 | * From 0 .. 100. Higher means more swappy. | |
120 | */ | |
121 | int vm_swappiness = 60; | |
bd1e22b8 | 122 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
123 | |
124 | static LIST_HEAD(shrinker_list); | |
125 | static DECLARE_RWSEM(shrinker_rwsem); | |
126 | ||
00f0b825 | 127 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 128 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 129 | #else |
e72e2bd6 | 130 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
131 | #endif |
132 | ||
6e901571 KM |
133 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
134 | struct scan_control *sc) | |
135 | { | |
e72e2bd6 | 136 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
137 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
138 | ||
6e901571 KM |
139 | return &zone->reclaim_stat; |
140 | } | |
141 | ||
c9f299d9 KM |
142 | static unsigned long zone_nr_pages(struct zone *zone, struct scan_control *sc, |
143 | enum lru_list lru) | |
144 | { | |
e72e2bd6 | 145 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
146 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
147 | ||
c9f299d9 KM |
148 | return zone_page_state(zone, NR_LRU_BASE + lru); |
149 | } | |
150 | ||
151 | ||
1da177e4 LT |
152 | /* |
153 | * Add a shrinker callback to be called from the vm | |
154 | */ | |
8e1f936b | 155 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 156 | { |
8e1f936b RR |
157 | shrinker->nr = 0; |
158 | down_write(&shrinker_rwsem); | |
159 | list_add_tail(&shrinker->list, &shrinker_list); | |
160 | up_write(&shrinker_rwsem); | |
1da177e4 | 161 | } |
8e1f936b | 162 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
163 | |
164 | /* | |
165 | * Remove one | |
166 | */ | |
8e1f936b | 167 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
168 | { |
169 | down_write(&shrinker_rwsem); | |
170 | list_del(&shrinker->list); | |
171 | up_write(&shrinker_rwsem); | |
1da177e4 | 172 | } |
8e1f936b | 173 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
174 | |
175 | #define SHRINK_BATCH 128 | |
176 | /* | |
177 | * Call the shrink functions to age shrinkable caches | |
178 | * | |
179 | * Here we assume it costs one seek to replace a lru page and that it also | |
180 | * takes a seek to recreate a cache object. With this in mind we age equal | |
181 | * percentages of the lru and ageable caches. This should balance the seeks | |
182 | * generated by these structures. | |
183 | * | |
183ff22b | 184 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
185 | * slab to avoid swapping. |
186 | * | |
187 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
188 | * | |
189 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
190 | * are eligible for the caller's allocation attempt. It is used for balancing | |
191 | * slab reclaim versus page reclaim. | |
b15e0905 | 192 | * |
193 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 194 | */ |
69e05944 AM |
195 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
196 | unsigned long lru_pages) | |
1da177e4 LT |
197 | { |
198 | struct shrinker *shrinker; | |
69e05944 | 199 | unsigned long ret = 0; |
1da177e4 LT |
200 | |
201 | if (scanned == 0) | |
202 | scanned = SWAP_CLUSTER_MAX; | |
203 | ||
204 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 205 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
206 | |
207 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
208 | unsigned long long delta; | |
209 | unsigned long total_scan; | |
8e1f936b | 210 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
1da177e4 LT |
211 | |
212 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 213 | delta *= max_pass; |
1da177e4 LT |
214 | do_div(delta, lru_pages + 1); |
215 | shrinker->nr += delta; | |
ea164d73 AA |
216 | if (shrinker->nr < 0) { |
217 | printk(KERN_ERR "%s: nr=%ld\n", | |
d40cee24 | 218 | __func__, shrinker->nr); |
ea164d73 AA |
219 | shrinker->nr = max_pass; |
220 | } | |
221 | ||
222 | /* | |
223 | * Avoid risking looping forever due to too large nr value: | |
224 | * never try to free more than twice the estimate number of | |
225 | * freeable entries. | |
226 | */ | |
227 | if (shrinker->nr > max_pass * 2) | |
228 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
229 | |
230 | total_scan = shrinker->nr; | |
231 | shrinker->nr = 0; | |
232 | ||
233 | while (total_scan >= SHRINK_BATCH) { | |
234 | long this_scan = SHRINK_BATCH; | |
235 | int shrink_ret; | |
b15e0905 | 236 | int nr_before; |
1da177e4 | 237 | |
8e1f936b RR |
238 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
239 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); | |
1da177e4 LT |
240 | if (shrink_ret == -1) |
241 | break; | |
b15e0905 | 242 | if (shrink_ret < nr_before) |
243 | ret += nr_before - shrink_ret; | |
f8891e5e | 244 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
245 | total_scan -= this_scan; |
246 | ||
247 | cond_resched(); | |
248 | } | |
249 | ||
250 | shrinker->nr += total_scan; | |
251 | } | |
252 | up_read(&shrinker_rwsem); | |
b15e0905 | 253 | return ret; |
1da177e4 LT |
254 | } |
255 | ||
256 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
257 | static inline int page_mapping_inuse(struct page *page) | |
258 | { | |
259 | struct address_space *mapping; | |
260 | ||
261 | /* Page is in somebody's page tables. */ | |
262 | if (page_mapped(page)) | |
263 | return 1; | |
264 | ||
265 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
266 | if (PageSwapCache(page)) | |
267 | return 1; | |
268 | ||
269 | mapping = page_mapping(page); | |
270 | if (!mapping) | |
271 | return 0; | |
272 | ||
273 | /* File is mmap'd by somebody? */ | |
274 | return mapping_mapped(mapping); | |
275 | } | |
276 | ||
277 | static inline int is_page_cache_freeable(struct page *page) | |
278 | { | |
279 | return page_count(page) - !!PagePrivate(page) == 2; | |
280 | } | |
281 | ||
282 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
283 | { | |
930d9152 | 284 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
285 | return 1; |
286 | if (!bdi_write_congested(bdi)) | |
287 | return 1; | |
288 | if (bdi == current->backing_dev_info) | |
289 | return 1; | |
290 | return 0; | |
291 | } | |
292 | ||
293 | /* | |
294 | * We detected a synchronous write error writing a page out. Probably | |
295 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
296 | * fsync(), msync() or close(). | |
297 | * | |
298 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
299 | * prevents it from being freed up. But we have a ref on the page and once | |
300 | * that page is locked, the mapping is pinned. | |
301 | * | |
302 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
303 | * __GFP_FS. | |
304 | */ | |
305 | static void handle_write_error(struct address_space *mapping, | |
306 | struct page *page, int error) | |
307 | { | |
308 | lock_page(page); | |
3e9f45bd GC |
309 | if (page_mapping(page) == mapping) |
310 | mapping_set_error(mapping, error); | |
1da177e4 LT |
311 | unlock_page(page); |
312 | } | |
313 | ||
c661b078 AW |
314 | /* Request for sync pageout. */ |
315 | enum pageout_io { | |
316 | PAGEOUT_IO_ASYNC, | |
317 | PAGEOUT_IO_SYNC, | |
318 | }; | |
319 | ||
04e62a29 CL |
320 | /* possible outcome of pageout() */ |
321 | typedef enum { | |
322 | /* failed to write page out, page is locked */ | |
323 | PAGE_KEEP, | |
324 | /* move page to the active list, page is locked */ | |
325 | PAGE_ACTIVATE, | |
326 | /* page has been sent to the disk successfully, page is unlocked */ | |
327 | PAGE_SUCCESS, | |
328 | /* page is clean and locked */ | |
329 | PAGE_CLEAN, | |
330 | } pageout_t; | |
331 | ||
1da177e4 | 332 | /* |
1742f19f AM |
333 | * pageout is called by shrink_page_list() for each dirty page. |
334 | * Calls ->writepage(). | |
1da177e4 | 335 | */ |
c661b078 AW |
336 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
337 | enum pageout_io sync_writeback) | |
1da177e4 LT |
338 | { |
339 | /* | |
340 | * If the page is dirty, only perform writeback if that write | |
341 | * will be non-blocking. To prevent this allocation from being | |
342 | * stalled by pagecache activity. But note that there may be | |
343 | * stalls if we need to run get_block(). We could test | |
344 | * PagePrivate for that. | |
345 | * | |
346 | * If this process is currently in generic_file_write() against | |
347 | * this page's queue, we can perform writeback even if that | |
348 | * will block. | |
349 | * | |
350 | * If the page is swapcache, write it back even if that would | |
351 | * block, for some throttling. This happens by accident, because | |
352 | * swap_backing_dev_info is bust: it doesn't reflect the | |
353 | * congestion state of the swapdevs. Easy to fix, if needed. | |
354 | * See swapfile.c:page_queue_congested(). | |
355 | */ | |
356 | if (!is_page_cache_freeable(page)) | |
357 | return PAGE_KEEP; | |
358 | if (!mapping) { | |
359 | /* | |
360 | * Some data journaling orphaned pages can have | |
361 | * page->mapping == NULL while being dirty with clean buffers. | |
362 | */ | |
323aca6c | 363 | if (PagePrivate(page)) { |
1da177e4 LT |
364 | if (try_to_free_buffers(page)) { |
365 | ClearPageDirty(page); | |
d40cee24 | 366 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
367 | return PAGE_CLEAN; |
368 | } | |
369 | } | |
370 | return PAGE_KEEP; | |
371 | } | |
372 | if (mapping->a_ops->writepage == NULL) | |
373 | return PAGE_ACTIVATE; | |
374 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
375 | return PAGE_KEEP; | |
376 | ||
377 | if (clear_page_dirty_for_io(page)) { | |
378 | int res; | |
379 | struct writeback_control wbc = { | |
380 | .sync_mode = WB_SYNC_NONE, | |
381 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
382 | .range_start = 0, |
383 | .range_end = LLONG_MAX, | |
1da177e4 LT |
384 | .nonblocking = 1, |
385 | .for_reclaim = 1, | |
386 | }; | |
387 | ||
388 | SetPageReclaim(page); | |
389 | res = mapping->a_ops->writepage(page, &wbc); | |
390 | if (res < 0) | |
391 | handle_write_error(mapping, page, res); | |
994fc28c | 392 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
393 | ClearPageReclaim(page); |
394 | return PAGE_ACTIVATE; | |
395 | } | |
c661b078 AW |
396 | |
397 | /* | |
398 | * Wait on writeback if requested to. This happens when | |
399 | * direct reclaiming a large contiguous area and the | |
400 | * first attempt to free a range of pages fails. | |
401 | */ | |
402 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
403 | wait_on_page_writeback(page); | |
404 | ||
1da177e4 LT |
405 | if (!PageWriteback(page)) { |
406 | /* synchronous write or broken a_ops? */ | |
407 | ClearPageReclaim(page); | |
408 | } | |
e129b5c2 | 409 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
410 | return PAGE_SUCCESS; |
411 | } | |
412 | ||
413 | return PAGE_CLEAN; | |
414 | } | |
415 | ||
a649fd92 | 416 | /* |
e286781d NP |
417 | * Same as remove_mapping, but if the page is removed from the mapping, it |
418 | * gets returned with a refcount of 0. | |
a649fd92 | 419 | */ |
e286781d | 420 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 421 | { |
28e4d965 NP |
422 | BUG_ON(!PageLocked(page)); |
423 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 424 | |
19fd6231 | 425 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 426 | /* |
0fd0e6b0 NP |
427 | * The non racy check for a busy page. |
428 | * | |
429 | * Must be careful with the order of the tests. When someone has | |
430 | * a ref to the page, it may be possible that they dirty it then | |
431 | * drop the reference. So if PageDirty is tested before page_count | |
432 | * here, then the following race may occur: | |
433 | * | |
434 | * get_user_pages(&page); | |
435 | * [user mapping goes away] | |
436 | * write_to(page); | |
437 | * !PageDirty(page) [good] | |
438 | * SetPageDirty(page); | |
439 | * put_page(page); | |
440 | * !page_count(page) [good, discard it] | |
441 | * | |
442 | * [oops, our write_to data is lost] | |
443 | * | |
444 | * Reversing the order of the tests ensures such a situation cannot | |
445 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
446 | * load is not satisfied before that of page->_count. | |
447 | * | |
448 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
449 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 450 | */ |
e286781d | 451 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 452 | goto cannot_free; |
e286781d NP |
453 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
454 | if (unlikely(PageDirty(page))) { | |
455 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 456 | goto cannot_free; |
e286781d | 457 | } |
49d2e9cc CL |
458 | |
459 | if (PageSwapCache(page)) { | |
460 | swp_entry_t swap = { .val = page_private(page) }; | |
461 | __delete_from_swap_cache(page); | |
19fd6231 | 462 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc | 463 | swap_free(swap); |
e286781d NP |
464 | } else { |
465 | __remove_from_page_cache(page); | |
19fd6231 | 466 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
467 | } |
468 | ||
49d2e9cc CL |
469 | return 1; |
470 | ||
471 | cannot_free: | |
19fd6231 | 472 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
473 | return 0; |
474 | } | |
475 | ||
e286781d NP |
476 | /* |
477 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
478 | * someone else has a ref on the page, abort and return 0. If it was | |
479 | * successfully detached, return 1. Assumes the caller has a single ref on | |
480 | * this page. | |
481 | */ | |
482 | int remove_mapping(struct address_space *mapping, struct page *page) | |
483 | { | |
484 | if (__remove_mapping(mapping, page)) { | |
485 | /* | |
486 | * Unfreezing the refcount with 1 rather than 2 effectively | |
487 | * drops the pagecache ref for us without requiring another | |
488 | * atomic operation. | |
489 | */ | |
490 | page_unfreeze_refs(page, 1); | |
491 | return 1; | |
492 | } | |
493 | return 0; | |
494 | } | |
495 | ||
894bc310 LS |
496 | /** |
497 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
498 | * @page: page to be put back to appropriate lru list | |
499 | * | |
500 | * Add previously isolated @page to appropriate LRU list. | |
501 | * Page may still be unevictable for other reasons. | |
502 | * | |
503 | * lru_lock must not be held, interrupts must be enabled. | |
504 | */ | |
505 | #ifdef CONFIG_UNEVICTABLE_LRU | |
506 | void putback_lru_page(struct page *page) | |
507 | { | |
508 | int lru; | |
509 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 510 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
511 | |
512 | VM_BUG_ON(PageLRU(page)); | |
513 | ||
514 | redo: | |
515 | ClearPageUnevictable(page); | |
516 | ||
517 | if (page_evictable(page, NULL)) { | |
518 | /* | |
519 | * For evictable pages, we can use the cache. | |
520 | * In event of a race, worst case is we end up with an | |
521 | * unevictable page on [in]active list. | |
522 | * We know how to handle that. | |
523 | */ | |
524 | lru = active + page_is_file_cache(page); | |
525 | lru_cache_add_lru(page, lru); | |
526 | } else { | |
527 | /* | |
528 | * Put unevictable pages directly on zone's unevictable | |
529 | * list. | |
530 | */ | |
531 | lru = LRU_UNEVICTABLE; | |
532 | add_page_to_unevictable_list(page); | |
533 | } | |
894bc310 LS |
534 | |
535 | /* | |
536 | * page's status can change while we move it among lru. If an evictable | |
537 | * page is on unevictable list, it never be freed. To avoid that, | |
538 | * check after we added it to the list, again. | |
539 | */ | |
540 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
541 | if (!isolate_lru_page(page)) { | |
542 | put_page(page); | |
543 | goto redo; | |
544 | } | |
545 | /* This means someone else dropped this page from LRU | |
546 | * So, it will be freed or putback to LRU again. There is | |
547 | * nothing to do here. | |
548 | */ | |
549 | } | |
550 | ||
bbfd28ee LS |
551 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
552 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
553 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
554 | count_vm_event(UNEVICTABLE_PGCULLED); | |
555 | ||
894bc310 LS |
556 | put_page(page); /* drop ref from isolate */ |
557 | } | |
558 | ||
559 | #else /* CONFIG_UNEVICTABLE_LRU */ | |
560 | ||
561 | void putback_lru_page(struct page *page) | |
562 | { | |
563 | int lru; | |
564 | VM_BUG_ON(PageLRU(page)); | |
565 | ||
566 | lru = !!TestClearPageActive(page) + page_is_file_cache(page); | |
567 | lru_cache_add_lru(page, lru); | |
894bc310 LS |
568 | put_page(page); |
569 | } | |
570 | #endif /* CONFIG_UNEVICTABLE_LRU */ | |
571 | ||
572 | ||
1da177e4 | 573 | /* |
1742f19f | 574 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 575 | */ |
1742f19f | 576 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
577 | struct scan_control *sc, |
578 | enum pageout_io sync_writeback) | |
1da177e4 LT |
579 | { |
580 | LIST_HEAD(ret_pages); | |
581 | struct pagevec freed_pvec; | |
582 | int pgactivate = 0; | |
05ff5137 | 583 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
584 | |
585 | cond_resched(); | |
586 | ||
587 | pagevec_init(&freed_pvec, 1); | |
588 | while (!list_empty(page_list)) { | |
589 | struct address_space *mapping; | |
590 | struct page *page; | |
591 | int may_enter_fs; | |
592 | int referenced; | |
593 | ||
594 | cond_resched(); | |
595 | ||
596 | page = lru_to_page(page_list); | |
597 | list_del(&page->lru); | |
598 | ||
529ae9aa | 599 | if (!trylock_page(page)) |
1da177e4 LT |
600 | goto keep; |
601 | ||
725d704e | 602 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
603 | |
604 | sc->nr_scanned++; | |
80e43426 | 605 | |
b291f000 NP |
606 | if (unlikely(!page_evictable(page, NULL))) |
607 | goto cull_mlocked; | |
894bc310 | 608 | |
80e43426 CL |
609 | if (!sc->may_swap && page_mapped(page)) |
610 | goto keep_locked; | |
611 | ||
1da177e4 LT |
612 | /* Double the slab pressure for mapped and swapcache pages */ |
613 | if (page_mapped(page) || PageSwapCache(page)) | |
614 | sc->nr_scanned++; | |
615 | ||
c661b078 AW |
616 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
617 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
618 | ||
619 | if (PageWriteback(page)) { | |
620 | /* | |
621 | * Synchronous reclaim is performed in two passes, | |
622 | * first an asynchronous pass over the list to | |
623 | * start parallel writeback, and a second synchronous | |
624 | * pass to wait for the IO to complete. Wait here | |
625 | * for any page for which writeback has already | |
626 | * started. | |
627 | */ | |
628 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
629 | wait_on_page_writeback(page); | |
4dd4b920 | 630 | else |
c661b078 AW |
631 | goto keep_locked; |
632 | } | |
1da177e4 | 633 | |
bed7161a | 634 | referenced = page_referenced(page, 1, sc->mem_cgroup); |
1da177e4 | 635 | /* In active use or really unfreeable? Activate it. */ |
5ad333eb AW |
636 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && |
637 | referenced && page_mapping_inuse(page)) | |
1da177e4 LT |
638 | goto activate_locked; |
639 | ||
1da177e4 LT |
640 | /* |
641 | * Anonymous process memory has backing store? | |
642 | * Try to allocate it some swap space here. | |
643 | */ | |
b291f000 | 644 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
645 | if (!(sc->gfp_mask & __GFP_IO)) |
646 | goto keep_locked; | |
ac47b003 | 647 | if (!add_to_swap(page)) |
1da177e4 | 648 | goto activate_locked; |
63eb6b93 | 649 | may_enter_fs = 1; |
b291f000 | 650 | } |
1da177e4 LT |
651 | |
652 | mapping = page_mapping(page); | |
1da177e4 LT |
653 | |
654 | /* | |
655 | * The page is mapped into the page tables of one or more | |
656 | * processes. Try to unmap it here. | |
657 | */ | |
658 | if (page_mapped(page) && mapping) { | |
a48d07af | 659 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
660 | case SWAP_FAIL: |
661 | goto activate_locked; | |
662 | case SWAP_AGAIN: | |
663 | goto keep_locked; | |
b291f000 NP |
664 | case SWAP_MLOCK: |
665 | goto cull_mlocked; | |
1da177e4 LT |
666 | case SWAP_SUCCESS: |
667 | ; /* try to free the page below */ | |
668 | } | |
669 | } | |
670 | ||
671 | if (PageDirty(page)) { | |
5ad333eb | 672 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) |
1da177e4 | 673 | goto keep_locked; |
4dd4b920 | 674 | if (!may_enter_fs) |
1da177e4 | 675 | goto keep_locked; |
52a8363e | 676 | if (!sc->may_writepage) |
1da177e4 LT |
677 | goto keep_locked; |
678 | ||
679 | /* Page is dirty, try to write it out here */ | |
c661b078 | 680 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
681 | case PAGE_KEEP: |
682 | goto keep_locked; | |
683 | case PAGE_ACTIVATE: | |
684 | goto activate_locked; | |
685 | case PAGE_SUCCESS: | |
4dd4b920 | 686 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
687 | goto keep; |
688 | /* | |
689 | * A synchronous write - probably a ramdisk. Go | |
690 | * ahead and try to reclaim the page. | |
691 | */ | |
529ae9aa | 692 | if (!trylock_page(page)) |
1da177e4 LT |
693 | goto keep; |
694 | if (PageDirty(page) || PageWriteback(page)) | |
695 | goto keep_locked; | |
696 | mapping = page_mapping(page); | |
697 | case PAGE_CLEAN: | |
698 | ; /* try to free the page below */ | |
699 | } | |
700 | } | |
701 | ||
702 | /* | |
703 | * If the page has buffers, try to free the buffer mappings | |
704 | * associated with this page. If we succeed we try to free | |
705 | * the page as well. | |
706 | * | |
707 | * We do this even if the page is PageDirty(). | |
708 | * try_to_release_page() does not perform I/O, but it is | |
709 | * possible for a page to have PageDirty set, but it is actually | |
710 | * clean (all its buffers are clean). This happens if the | |
711 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 712 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
713 | * try_to_release_page() will discover that cleanness and will |
714 | * drop the buffers and mark the page clean - it can be freed. | |
715 | * | |
716 | * Rarely, pages can have buffers and no ->mapping. These are | |
717 | * the pages which were not successfully invalidated in | |
718 | * truncate_complete_page(). We try to drop those buffers here | |
719 | * and if that worked, and the page is no longer mapped into | |
720 | * process address space (page_count == 1) it can be freed. | |
721 | * Otherwise, leave the page on the LRU so it is swappable. | |
722 | */ | |
723 | if (PagePrivate(page)) { | |
724 | if (!try_to_release_page(page, sc->gfp_mask)) | |
725 | goto activate_locked; | |
e286781d NP |
726 | if (!mapping && page_count(page) == 1) { |
727 | unlock_page(page); | |
728 | if (put_page_testzero(page)) | |
729 | goto free_it; | |
730 | else { | |
731 | /* | |
732 | * rare race with speculative reference. | |
733 | * the speculative reference will free | |
734 | * this page shortly, so we may | |
735 | * increment nr_reclaimed here (and | |
736 | * leave it off the LRU). | |
737 | */ | |
738 | nr_reclaimed++; | |
739 | continue; | |
740 | } | |
741 | } | |
1da177e4 LT |
742 | } |
743 | ||
e286781d | 744 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 745 | goto keep_locked; |
1da177e4 | 746 | |
a978d6f5 NP |
747 | /* |
748 | * At this point, we have no other references and there is | |
749 | * no way to pick any more up (removed from LRU, removed | |
750 | * from pagecache). Can use non-atomic bitops now (and | |
751 | * we obviously don't have to worry about waking up a process | |
752 | * waiting on the page lock, because there are no references. | |
753 | */ | |
754 | __clear_page_locked(page); | |
e286781d | 755 | free_it: |
05ff5137 | 756 | nr_reclaimed++; |
e286781d NP |
757 | if (!pagevec_add(&freed_pvec, page)) { |
758 | __pagevec_free(&freed_pvec); | |
759 | pagevec_reinit(&freed_pvec); | |
760 | } | |
1da177e4 LT |
761 | continue; |
762 | ||
b291f000 | 763 | cull_mlocked: |
63d6c5ad HD |
764 | if (PageSwapCache(page)) |
765 | try_to_free_swap(page); | |
b291f000 NP |
766 | unlock_page(page); |
767 | putback_lru_page(page); | |
768 | continue; | |
769 | ||
1da177e4 | 770 | activate_locked: |
68a22394 RR |
771 | /* Not a candidate for swapping, so reclaim swap space. */ |
772 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 773 | try_to_free_swap(page); |
894bc310 | 774 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
775 | SetPageActive(page); |
776 | pgactivate++; | |
777 | keep_locked: | |
778 | unlock_page(page); | |
779 | keep: | |
780 | list_add(&page->lru, &ret_pages); | |
b291f000 | 781 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 LT |
782 | } |
783 | list_splice(&ret_pages, page_list); | |
784 | if (pagevec_count(&freed_pvec)) | |
e286781d | 785 | __pagevec_free(&freed_pvec); |
f8891e5e | 786 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 787 | return nr_reclaimed; |
1da177e4 LT |
788 | } |
789 | ||
5ad333eb AW |
790 | /* LRU Isolation modes. */ |
791 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ | |
792 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ | |
793 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ | |
794 | ||
795 | /* | |
796 | * Attempt to remove the specified page from its LRU. Only take this page | |
797 | * if it is of the appropriate PageActive status. Pages which are being | |
798 | * freed elsewhere are also ignored. | |
799 | * | |
800 | * page: page to consider | |
801 | * mode: one of the LRU isolation modes defined above | |
802 | * | |
803 | * returns 0 on success, -ve errno on failure. | |
804 | */ | |
4f98a2fe | 805 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
806 | { |
807 | int ret = -EINVAL; | |
808 | ||
809 | /* Only take pages on the LRU. */ | |
810 | if (!PageLRU(page)) | |
811 | return ret; | |
812 | ||
813 | /* | |
814 | * When checking the active state, we need to be sure we are | |
815 | * dealing with comparible boolean values. Take the logical not | |
816 | * of each. | |
817 | */ | |
818 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
819 | return ret; | |
820 | ||
4f98a2fe RR |
821 | if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file)) |
822 | return ret; | |
823 | ||
894bc310 LS |
824 | /* |
825 | * When this function is being called for lumpy reclaim, we | |
826 | * initially look into all LRU pages, active, inactive and | |
827 | * unevictable; only give shrink_page_list evictable pages. | |
828 | */ | |
829 | if (PageUnevictable(page)) | |
830 | return ret; | |
831 | ||
5ad333eb | 832 | ret = -EBUSY; |
08e552c6 | 833 | |
5ad333eb AW |
834 | if (likely(get_page_unless_zero(page))) { |
835 | /* | |
836 | * Be careful not to clear PageLRU until after we're | |
837 | * sure the page is not being freed elsewhere -- the | |
838 | * page release code relies on it. | |
839 | */ | |
840 | ClearPageLRU(page); | |
841 | ret = 0; | |
08e552c6 | 842 | mem_cgroup_del_lru(page); |
5ad333eb AW |
843 | } |
844 | ||
845 | return ret; | |
846 | } | |
847 | ||
1da177e4 LT |
848 | /* |
849 | * zone->lru_lock is heavily contended. Some of the functions that | |
850 | * shrink the lists perform better by taking out a batch of pages | |
851 | * and working on them outside the LRU lock. | |
852 | * | |
853 | * For pagecache intensive workloads, this function is the hottest | |
854 | * spot in the kernel (apart from copy_*_user functions). | |
855 | * | |
856 | * Appropriate locks must be held before calling this function. | |
857 | * | |
858 | * @nr_to_scan: The number of pages to look through on the list. | |
859 | * @src: The LRU list to pull pages off. | |
860 | * @dst: The temp list to put pages on to. | |
861 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
862 | * @order: The caller's attempted allocation order |
863 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 864 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
865 | * |
866 | * returns how many pages were moved onto *@dst. | |
867 | */ | |
69e05944 AM |
868 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
869 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 870 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 871 | { |
69e05944 | 872 | unsigned long nr_taken = 0; |
c9b02d97 | 873 | unsigned long scan; |
1da177e4 | 874 | |
c9b02d97 | 875 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
876 | struct page *page; |
877 | unsigned long pfn; | |
878 | unsigned long end_pfn; | |
879 | unsigned long page_pfn; | |
880 | int zone_id; | |
881 | ||
1da177e4 LT |
882 | page = lru_to_page(src); |
883 | prefetchw_prev_lru_page(page, src, flags); | |
884 | ||
725d704e | 885 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 886 | |
4f98a2fe | 887 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
888 | case 0: |
889 | list_move(&page->lru, dst); | |
7c8ee9a8 | 890 | nr_taken++; |
5ad333eb AW |
891 | break; |
892 | ||
893 | case -EBUSY: | |
894 | /* else it is being freed elsewhere */ | |
895 | list_move(&page->lru, src); | |
896 | continue; | |
46453a6e | 897 | |
5ad333eb AW |
898 | default: |
899 | BUG(); | |
900 | } | |
901 | ||
902 | if (!order) | |
903 | continue; | |
904 | ||
905 | /* | |
906 | * Attempt to take all pages in the order aligned region | |
907 | * surrounding the tag page. Only take those pages of | |
908 | * the same active state as that tag page. We may safely | |
909 | * round the target page pfn down to the requested order | |
910 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
911 | * where that page is in a different zone we will detect | |
912 | * it from its zone id and abort this block scan. | |
913 | */ | |
914 | zone_id = page_zone_id(page); | |
915 | page_pfn = page_to_pfn(page); | |
916 | pfn = page_pfn & ~((1 << order) - 1); | |
917 | end_pfn = pfn + (1 << order); | |
918 | for (; pfn < end_pfn; pfn++) { | |
919 | struct page *cursor_page; | |
920 | ||
921 | /* The target page is in the block, ignore it. */ | |
922 | if (unlikely(pfn == page_pfn)) | |
923 | continue; | |
924 | ||
925 | /* Avoid holes within the zone. */ | |
926 | if (unlikely(!pfn_valid_within(pfn))) | |
927 | break; | |
928 | ||
929 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 930 | |
5ad333eb AW |
931 | /* Check that we have not crossed a zone boundary. */ |
932 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
933 | continue; | |
4f98a2fe | 934 | switch (__isolate_lru_page(cursor_page, mode, file)) { |
5ad333eb AW |
935 | case 0: |
936 | list_move(&cursor_page->lru, dst); | |
937 | nr_taken++; | |
938 | scan++; | |
939 | break; | |
940 | ||
941 | case -EBUSY: | |
942 | /* else it is being freed elsewhere */ | |
943 | list_move(&cursor_page->lru, src); | |
944 | default: | |
894bc310 | 945 | break; /* ! on LRU or wrong list */ |
5ad333eb AW |
946 | } |
947 | } | |
1da177e4 LT |
948 | } |
949 | ||
950 | *scanned = scan; | |
951 | return nr_taken; | |
952 | } | |
953 | ||
66e1707b BS |
954 | static unsigned long isolate_pages_global(unsigned long nr, |
955 | struct list_head *dst, | |
956 | unsigned long *scanned, int order, | |
957 | int mode, struct zone *z, | |
958 | struct mem_cgroup *mem_cont, | |
4f98a2fe | 959 | int active, int file) |
66e1707b | 960 | { |
4f98a2fe | 961 | int lru = LRU_BASE; |
66e1707b | 962 | if (active) |
4f98a2fe RR |
963 | lru += LRU_ACTIVE; |
964 | if (file) | |
965 | lru += LRU_FILE; | |
966 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
967 | mode, !!file); | |
66e1707b BS |
968 | } |
969 | ||
5ad333eb AW |
970 | /* |
971 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
972 | * any active bits from the pages in the list. | |
973 | */ | |
4f98a2fe RR |
974 | static unsigned long clear_active_flags(struct list_head *page_list, |
975 | unsigned int *count) | |
5ad333eb AW |
976 | { |
977 | int nr_active = 0; | |
4f98a2fe | 978 | int lru; |
5ad333eb AW |
979 | struct page *page; |
980 | ||
4f98a2fe RR |
981 | list_for_each_entry(page, page_list, lru) { |
982 | lru = page_is_file_cache(page); | |
5ad333eb | 983 | if (PageActive(page)) { |
4f98a2fe | 984 | lru += LRU_ACTIVE; |
5ad333eb AW |
985 | ClearPageActive(page); |
986 | nr_active++; | |
987 | } | |
4f98a2fe RR |
988 | count[lru]++; |
989 | } | |
5ad333eb AW |
990 | |
991 | return nr_active; | |
992 | } | |
993 | ||
62695a84 NP |
994 | /** |
995 | * isolate_lru_page - tries to isolate a page from its LRU list | |
996 | * @page: page to isolate from its LRU list | |
997 | * | |
998 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
999 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1000 | * | |
1001 | * Returns 0 if the page was removed from an LRU list. | |
1002 | * Returns -EBUSY if the page was not on an LRU list. | |
1003 | * | |
1004 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1005 | * the active list, it will have PageActive set. If it was found on |
1006 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1007 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1008 | * |
1009 | * The vmstat statistic corresponding to the list on which the page was | |
1010 | * found will be decremented. | |
1011 | * | |
1012 | * Restrictions: | |
1013 | * (1) Must be called with an elevated refcount on the page. This is a | |
1014 | * fundamentnal difference from isolate_lru_pages (which is called | |
1015 | * without a stable reference). | |
1016 | * (2) the lru_lock must not be held. | |
1017 | * (3) interrupts must be enabled. | |
1018 | */ | |
1019 | int isolate_lru_page(struct page *page) | |
1020 | { | |
1021 | int ret = -EBUSY; | |
1022 | ||
1023 | if (PageLRU(page)) { | |
1024 | struct zone *zone = page_zone(page); | |
1025 | ||
1026 | spin_lock_irq(&zone->lru_lock); | |
1027 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1028 | int lru = page_lru(page); |
62695a84 NP |
1029 | ret = 0; |
1030 | ClearPageLRU(page); | |
4f98a2fe | 1031 | |
4f98a2fe | 1032 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1033 | } |
1034 | spin_unlock_irq(&zone->lru_lock); | |
1035 | } | |
1036 | return ret; | |
1037 | } | |
1038 | ||
1da177e4 | 1039 | /* |
1742f19f AM |
1040 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1041 | * of reclaimed pages | |
1da177e4 | 1042 | */ |
1742f19f | 1043 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
33c120ed RR |
1044 | struct zone *zone, struct scan_control *sc, |
1045 | int priority, int file) | |
1da177e4 LT |
1046 | { |
1047 | LIST_HEAD(page_list); | |
1048 | struct pagevec pvec; | |
69e05944 | 1049 | unsigned long nr_scanned = 0; |
05ff5137 | 1050 | unsigned long nr_reclaimed = 0; |
6e901571 | 1051 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1da177e4 LT |
1052 | |
1053 | pagevec_init(&pvec, 1); | |
1054 | ||
1055 | lru_add_drain(); | |
1056 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 1057 | do { |
1da177e4 | 1058 | struct page *page; |
69e05944 AM |
1059 | unsigned long nr_taken; |
1060 | unsigned long nr_scan; | |
1061 | unsigned long nr_freed; | |
5ad333eb | 1062 | unsigned long nr_active; |
4f98a2fe | 1063 | unsigned int count[NR_LRU_LISTS] = { 0, }; |
33c120ed RR |
1064 | int mode = ISOLATE_INACTIVE; |
1065 | ||
1066 | /* | |
1067 | * If we need a large contiguous chunk of memory, or have | |
1068 | * trouble getting a small set of contiguous pages, we | |
1069 | * will reclaim both active and inactive pages. | |
1070 | * | |
1071 | * We use the same threshold as pageout congestion_wait below. | |
1072 | */ | |
1073 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1074 | mode = ISOLATE_BOTH; | |
1075 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1076 | mode = ISOLATE_BOTH; | |
1da177e4 | 1077 | |
66e1707b | 1078 | nr_taken = sc->isolate_pages(sc->swap_cluster_max, |
4f98a2fe RR |
1079 | &page_list, &nr_scan, sc->order, mode, |
1080 | zone, sc->mem_cgroup, 0, file); | |
1081 | nr_active = clear_active_flags(&page_list, count); | |
e9187bdc | 1082 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb | 1083 | |
4f98a2fe RR |
1084 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1085 | -count[LRU_ACTIVE_FILE]); | |
1086 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1087 | -count[LRU_INACTIVE_FILE]); | |
1088 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1089 | -count[LRU_ACTIVE_ANON]); | |
1090 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1091 | -count[LRU_INACTIVE_ANON]); | |
1092 | ||
e72e2bd6 | 1093 | if (scanning_global_lru(sc)) |
1cfb419b | 1094 | zone->pages_scanned += nr_scan; |
3e2f41f1 KM |
1095 | |
1096 | reclaim_stat->recent_scanned[0] += count[LRU_INACTIVE_ANON]; | |
1097 | reclaim_stat->recent_scanned[0] += count[LRU_ACTIVE_ANON]; | |
1098 | reclaim_stat->recent_scanned[1] += count[LRU_INACTIVE_FILE]; | |
1099 | reclaim_stat->recent_scanned[1] += count[LRU_ACTIVE_FILE]; | |
1100 | ||
1da177e4 LT |
1101 | spin_unlock_irq(&zone->lru_lock); |
1102 | ||
69e05944 | 1103 | nr_scanned += nr_scan; |
c661b078 AW |
1104 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
1105 | ||
1106 | /* | |
1107 | * If we are direct reclaiming for contiguous pages and we do | |
1108 | * not reclaim everything in the list, try again and wait | |
1109 | * for IO to complete. This will stall high-order allocations | |
1110 | * but that should be acceptable to the caller | |
1111 | */ | |
1112 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
1113 | sc->order > PAGE_ALLOC_COSTLY_ORDER) { | |
1114 | congestion_wait(WRITE, HZ/10); | |
1115 | ||
1116 | /* | |
1117 | * The attempt at page out may have made some | |
1118 | * of the pages active, mark them inactive again. | |
1119 | */ | |
4f98a2fe | 1120 | nr_active = clear_active_flags(&page_list, count); |
c661b078 AW |
1121 | count_vm_events(PGDEACTIVATE, nr_active); |
1122 | ||
1123 | nr_freed += shrink_page_list(&page_list, sc, | |
1124 | PAGEOUT_IO_SYNC); | |
1125 | } | |
1126 | ||
05ff5137 | 1127 | nr_reclaimed += nr_freed; |
a74609fa NP |
1128 | local_irq_disable(); |
1129 | if (current_is_kswapd()) { | |
f8891e5e CL |
1130 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
1131 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
e72e2bd6 | 1132 | } else if (scanning_global_lru(sc)) |
f8891e5e | 1133 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
1cfb419b | 1134 | |
918d3f90 | 1135 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa | 1136 | |
fb8d14e1 WF |
1137 | if (nr_taken == 0) |
1138 | goto done; | |
1139 | ||
a74609fa | 1140 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
1141 | /* |
1142 | * Put back any unfreeable pages. | |
1143 | */ | |
1144 | while (!list_empty(&page_list)) { | |
894bc310 | 1145 | int lru; |
1da177e4 | 1146 | page = lru_to_page(&page_list); |
725d704e | 1147 | VM_BUG_ON(PageLRU(page)); |
1da177e4 | 1148 | list_del(&page->lru); |
894bc310 LS |
1149 | if (unlikely(!page_evictable(page, NULL))) { |
1150 | spin_unlock_irq(&zone->lru_lock); | |
1151 | putback_lru_page(page); | |
1152 | spin_lock_irq(&zone->lru_lock); | |
1153 | continue; | |
1154 | } | |
1155 | SetPageLRU(page); | |
1156 | lru = page_lru(page); | |
1157 | add_page_to_lru_list(zone, page, lru); | |
3e2f41f1 | 1158 | if (PageActive(page)) { |
4f98a2fe | 1159 | int file = !!page_is_file_cache(page); |
6e901571 | 1160 | reclaim_stat->recent_rotated[file]++; |
4f98a2fe | 1161 | } |
1da177e4 LT |
1162 | if (!pagevec_add(&pvec, page)) { |
1163 | spin_unlock_irq(&zone->lru_lock); | |
1164 | __pagevec_release(&pvec); | |
1165 | spin_lock_irq(&zone->lru_lock); | |
1166 | } | |
1167 | } | |
69e05944 | 1168 | } while (nr_scanned < max_scan); |
fb8d14e1 | 1169 | spin_unlock(&zone->lru_lock); |
1da177e4 | 1170 | done: |
fb8d14e1 | 1171 | local_irq_enable(); |
1da177e4 | 1172 | pagevec_release(&pvec); |
05ff5137 | 1173 | return nr_reclaimed; |
1da177e4 LT |
1174 | } |
1175 | ||
3bb1a852 MB |
1176 | /* |
1177 | * We are about to scan this zone at a certain priority level. If that priority | |
1178 | * level is smaller (ie: more urgent) than the previous priority, then note | |
1179 | * that priority level within the zone. This is done so that when the next | |
1180 | * process comes in to scan this zone, it will immediately start out at this | |
1181 | * priority level rather than having to build up its own scanning priority. | |
1182 | * Here, this priority affects only the reclaim-mapped threshold. | |
1183 | */ | |
1184 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
1185 | { | |
1186 | if (priority < zone->prev_priority) | |
1187 | zone->prev_priority = priority; | |
1188 | } | |
1189 | ||
1da177e4 LT |
1190 | /* |
1191 | * This moves pages from the active list to the inactive list. | |
1192 | * | |
1193 | * We move them the other way if the page is referenced by one or more | |
1194 | * processes, from rmap. | |
1195 | * | |
1196 | * If the pages are mostly unmapped, the processing is fast and it is | |
1197 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1198 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1199 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1200 | * this, so instead we remove the pages from the LRU while processing them. | |
1201 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1202 | * nobody will play with that bit on a non-LRU page. | |
1203 | * | |
1204 | * The downside is that we have to touch page->_count against each page. | |
1205 | * But we had to alter page->flags anyway. | |
1206 | */ | |
1cfb419b KH |
1207 | |
1208 | ||
1742f19f | 1209 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1210 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1211 | { |
69e05944 | 1212 | unsigned long pgmoved; |
1da177e4 | 1213 | int pgdeactivate = 0; |
69e05944 | 1214 | unsigned long pgscanned; |
1da177e4 | 1215 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
b69408e8 | 1216 | LIST_HEAD(l_inactive); |
1da177e4 LT |
1217 | struct page *page; |
1218 | struct pagevec pvec; | |
4f98a2fe | 1219 | enum lru_list lru; |
6e901571 | 1220 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1da177e4 LT |
1221 | |
1222 | lru_add_drain(); | |
1223 | spin_lock_irq(&zone->lru_lock); | |
66e1707b BS |
1224 | pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, |
1225 | ISOLATE_ACTIVE, zone, | |
4f98a2fe | 1226 | sc->mem_cgroup, 1, file); |
1cfb419b KH |
1227 | /* |
1228 | * zone->pages_scanned is used for detect zone's oom | |
1229 | * mem_cgroup remembers nr_scan by itself. | |
1230 | */ | |
e72e2bd6 | 1231 | if (scanning_global_lru(sc)) { |
1cfb419b | 1232 | zone->pages_scanned += pgscanned; |
4f98a2fe | 1233 | } |
3e2f41f1 | 1234 | reclaim_stat->recent_scanned[!!file] += pgmoved; |
1cfb419b | 1235 | |
4f98a2fe RR |
1236 | if (file) |
1237 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved); | |
1238 | else | |
1239 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved); | |
1da177e4 LT |
1240 | spin_unlock_irq(&zone->lru_lock); |
1241 | ||
556adecb | 1242 | pgmoved = 0; |
1da177e4 LT |
1243 | while (!list_empty(&l_hold)) { |
1244 | cond_resched(); | |
1245 | page = lru_to_page(&l_hold); | |
1246 | list_del(&page->lru); | |
7e9cd484 | 1247 | |
894bc310 LS |
1248 | if (unlikely(!page_evictable(page, NULL))) { |
1249 | putback_lru_page(page); | |
1250 | continue; | |
1251 | } | |
1252 | ||
7e9cd484 RR |
1253 | /* page_referenced clears PageReferenced */ |
1254 | if (page_mapping_inuse(page) && | |
1255 | page_referenced(page, 0, sc->mem_cgroup)) | |
1256 | pgmoved++; | |
1257 | ||
1da177e4 LT |
1258 | list_add(&page->lru, &l_inactive); |
1259 | } | |
1260 | ||
b555749a AM |
1261 | /* |
1262 | * Move the pages to the [file or anon] inactive list. | |
1263 | */ | |
1264 | pagevec_init(&pvec, 1); | |
1265 | pgmoved = 0; | |
1266 | lru = LRU_BASE + file * LRU_FILE; | |
1267 | ||
2a1dc509 | 1268 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1269 | /* |
7e9cd484 RR |
1270 | * Count referenced pages from currently used mappings as |
1271 | * rotated, even though they are moved to the inactive list. | |
1272 | * This helps balance scan pressure between file and anonymous | |
1273 | * pages in get_scan_ratio. | |
1274 | */ | |
3e2f41f1 | 1275 | reclaim_stat->recent_rotated[!!file] += pgmoved; |
556adecb | 1276 | |
1da177e4 LT |
1277 | while (!list_empty(&l_inactive)) { |
1278 | page = lru_to_page(&l_inactive); | |
1279 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 1280 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1281 | SetPageLRU(page); |
725d704e | 1282 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
1283 | ClearPageActive(page); |
1284 | ||
4f98a2fe | 1285 | list_move(&page->lru, &zone->lru[lru].list); |
08e552c6 | 1286 | mem_cgroup_add_lru_list(page, lru); |
1da177e4 LT |
1287 | pgmoved++; |
1288 | if (!pagevec_add(&pvec, page)) { | |
4f98a2fe | 1289 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1290 | spin_unlock_irq(&zone->lru_lock); |
1291 | pgdeactivate += pgmoved; | |
1292 | pgmoved = 0; | |
1293 | if (buffer_heads_over_limit) | |
1294 | pagevec_strip(&pvec); | |
1295 | __pagevec_release(&pvec); | |
1296 | spin_lock_irq(&zone->lru_lock); | |
1297 | } | |
1298 | } | |
4f98a2fe | 1299 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1300 | pgdeactivate += pgmoved; |
1301 | if (buffer_heads_over_limit) { | |
1302 | spin_unlock_irq(&zone->lru_lock); | |
1303 | pagevec_strip(&pvec); | |
1304 | spin_lock_irq(&zone->lru_lock); | |
1305 | } | |
f8891e5e CL |
1306 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1307 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
1308 | spin_unlock_irq(&zone->lru_lock); | |
68a22394 RR |
1309 | if (vm_swap_full()) |
1310 | pagevec_swap_free(&pvec); | |
1da177e4 | 1311 | |
a74609fa | 1312 | pagevec_release(&pvec); |
1da177e4 LT |
1313 | } |
1314 | ||
14797e23 | 1315 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1316 | { |
1317 | unsigned long active, inactive; | |
1318 | ||
1319 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1320 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1321 | ||
1322 | if (inactive * zone->inactive_ratio < active) | |
1323 | return 1; | |
1324 | ||
1325 | return 0; | |
1326 | } | |
1327 | ||
14797e23 KM |
1328 | /** |
1329 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1330 | * @zone: zone to check | |
1331 | * @sc: scan control of this context | |
1332 | * | |
1333 | * Returns true if the zone does not have enough inactive anon pages, | |
1334 | * meaning some active anon pages need to be deactivated. | |
1335 | */ | |
1336 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1337 | { | |
1338 | int low; | |
1339 | ||
e72e2bd6 | 1340 | if (scanning_global_lru(sc)) |
14797e23 KM |
1341 | low = inactive_anon_is_low_global(zone); |
1342 | else | |
c772be93 | 1343 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1344 | return low; |
1345 | } | |
1346 | ||
4f98a2fe | 1347 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1348 | struct zone *zone, struct scan_control *sc, int priority) |
1349 | { | |
4f98a2fe RR |
1350 | int file = is_file_lru(lru); |
1351 | ||
556adecb RR |
1352 | if (lru == LRU_ACTIVE_FILE) { |
1353 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
1354 | return 0; | |
1355 | } | |
1356 | ||
14797e23 | 1357 | if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) { |
4f98a2fe | 1358 | shrink_active_list(nr_to_scan, zone, sc, priority, file); |
b69408e8 CL |
1359 | return 0; |
1360 | } | |
33c120ed | 1361 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1362 | } |
1363 | ||
1364 | /* | |
1365 | * Determine how aggressively the anon and file LRU lists should be | |
1366 | * scanned. The relative value of each set of LRU lists is determined | |
1367 | * by looking at the fraction of the pages scanned we did rotate back | |
1368 | * onto the active list instead of evict. | |
1369 | * | |
1370 | * percent[0] specifies how much pressure to put on ram/swap backed | |
1371 | * memory, while percent[1] determines pressure on the file LRUs. | |
1372 | */ | |
1373 | static void get_scan_ratio(struct zone *zone, struct scan_control *sc, | |
1374 | unsigned long *percent) | |
1375 | { | |
1376 | unsigned long anon, file, free; | |
1377 | unsigned long anon_prio, file_prio; | |
1378 | unsigned long ap, fp; | |
6e901571 | 1379 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
4f98a2fe | 1380 | |
4f98a2fe RR |
1381 | /* If we have no swap space, do not bother scanning anon pages. */ |
1382 | if (nr_swap_pages <= 0) { | |
1383 | percent[0] = 0; | |
1384 | percent[1] = 100; | |
1385 | return; | |
1386 | } | |
1387 | ||
c9f299d9 KM |
1388 | anon = zone_nr_pages(zone, sc, LRU_ACTIVE_ANON) + |
1389 | zone_nr_pages(zone, sc, LRU_INACTIVE_ANON); | |
1390 | file = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1391 | zone_nr_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1392 | |
e72e2bd6 | 1393 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1394 | free = zone_page_state(zone, NR_FREE_PAGES); |
1395 | /* If we have very few page cache pages, | |
1396 | force-scan anon pages. */ | |
1397 | if (unlikely(file + free <= zone->pages_high)) { | |
1398 | percent[0] = 100; | |
1399 | percent[1] = 0; | |
1400 | return; | |
1401 | } | |
4f98a2fe RR |
1402 | } |
1403 | ||
1404 | /* | |
1405 | * OK, so we have swap space and a fair amount of page cache | |
1406 | * pages. We use the recently rotated / recently scanned | |
1407 | * ratios to determine how valuable each cache is. | |
1408 | * | |
1409 | * Because workloads change over time (and to avoid overflow) | |
1410 | * we keep these statistics as a floating average, which ends | |
1411 | * up weighing recent references more than old ones. | |
1412 | * | |
1413 | * anon in [0], file in [1] | |
1414 | */ | |
6e901571 | 1415 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
4f98a2fe | 1416 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1417 | reclaim_stat->recent_scanned[0] /= 2; |
1418 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1419 | spin_unlock_irq(&zone->lru_lock); |
1420 | } | |
1421 | ||
6e901571 | 1422 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
4f98a2fe | 1423 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1424 | reclaim_stat->recent_scanned[1] /= 2; |
1425 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1426 | spin_unlock_irq(&zone->lru_lock); |
1427 | } | |
1428 | ||
1429 | /* | |
1430 | * With swappiness at 100, anonymous and file have the same priority. | |
1431 | * This scanning priority is essentially the inverse of IO cost. | |
1432 | */ | |
1433 | anon_prio = sc->swappiness; | |
1434 | file_prio = 200 - sc->swappiness; | |
1435 | ||
1436 | /* | |
00d8089c RR |
1437 | * The amount of pressure on anon vs file pages is inversely |
1438 | * proportional to the fraction of recently scanned pages on | |
1439 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1440 | */ |
6e901571 KM |
1441 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1442 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1443 | |
6e901571 KM |
1444 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1445 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
4f98a2fe RR |
1446 | |
1447 | /* Normalize to percentages */ | |
1448 | percent[0] = 100 * ap / (ap + fp + 1); | |
1449 | percent[1] = 100 - percent[0]; | |
b69408e8 CL |
1450 | } |
1451 | ||
4f98a2fe | 1452 | |
1da177e4 LT |
1453 | /* |
1454 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1455 | */ | |
a79311c1 | 1456 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1457 | struct scan_control *sc) |
1da177e4 | 1458 | { |
b69408e8 | 1459 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1460 | unsigned long nr_to_scan; |
4f98a2fe | 1461 | unsigned long percent[2]; /* anon @ 0; file @ 1 */ |
b69408e8 | 1462 | enum lru_list l; |
01dbe5c9 KM |
1463 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
1464 | unsigned long swap_cluster_max = sc->swap_cluster_max; | |
1da177e4 | 1465 | |
4f98a2fe RR |
1466 | get_scan_ratio(zone, sc, percent); |
1467 | ||
894bc310 | 1468 | for_each_evictable_lru(l) { |
9439c1c9 KM |
1469 | int file = is_file_lru(l); |
1470 | int scan; | |
e0f79b8f | 1471 | |
9439c1c9 KM |
1472 | scan = zone_page_state(zone, NR_LRU_BASE + l); |
1473 | if (priority) { | |
1474 | scan >>= priority; | |
1475 | scan = (scan * percent[file]) / 100; | |
1476 | } | |
e72e2bd6 | 1477 | if (scanning_global_lru(sc)) { |
e0f79b8f | 1478 | zone->lru[l].nr_scan += scan; |
b69408e8 | 1479 | nr[l] = zone->lru[l].nr_scan; |
01dbe5c9 | 1480 | if (nr[l] >= swap_cluster_max) |
b69408e8 CL |
1481 | zone->lru[l].nr_scan = 0; |
1482 | else | |
1483 | nr[l] = 0; | |
9439c1c9 KM |
1484 | } else |
1485 | nr[l] = scan; | |
1cfb419b | 1486 | } |
1da177e4 | 1487 | |
556adecb RR |
1488 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1489 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1490 | for_each_evictable_lru(l) { |
b69408e8 | 1491 | if (nr[l]) { |
01dbe5c9 | 1492 | nr_to_scan = min(nr[l], swap_cluster_max); |
b69408e8 | 1493 | nr[l] -= nr_to_scan; |
1da177e4 | 1494 | |
01dbe5c9 KM |
1495 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1496 | zone, sc, priority); | |
b69408e8 | 1497 | } |
1da177e4 | 1498 | } |
a79311c1 RR |
1499 | /* |
1500 | * On large memory systems, scan >> priority can become | |
1501 | * really large. This is fine for the starting priority; | |
1502 | * we want to put equal scanning pressure on each zone. | |
1503 | * However, if the VM has a harder time of freeing pages, | |
1504 | * with multiple processes reclaiming pages, the total | |
1505 | * freeing target can get unreasonably large. | |
1506 | */ | |
01dbe5c9 | 1507 | if (nr_reclaimed > swap_cluster_max && |
a79311c1 RR |
1508 | priority < DEF_PRIORITY && !current_is_kswapd()) |
1509 | break; | |
1da177e4 LT |
1510 | } |
1511 | ||
01dbe5c9 KM |
1512 | sc->nr_reclaimed = nr_reclaimed; |
1513 | ||
556adecb RR |
1514 | /* |
1515 | * Even if we did not try to evict anon pages at all, we want to | |
1516 | * rebalance the anon lru active/inactive ratio. | |
1517 | */ | |
14797e23 | 1518 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1519 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1520 | ||
232ea4d6 | 1521 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1522 | } |
1523 | ||
1524 | /* | |
1525 | * This is the direct reclaim path, for page-allocating processes. We only | |
1526 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1527 | * request. | |
1528 | * | |
1529 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
1530 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
1531 | * allocation or | |
1532 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
1533 | * satisfy the `incremental min' zone defense algorithm. | |
1534 | * | |
1da177e4 LT |
1535 | * If a zone is deemed to be full of pinned pages then just give it a light |
1536 | * scan then give up on it. | |
1537 | */ | |
a79311c1 | 1538 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1539 | struct scan_control *sc) |
1da177e4 | 1540 | { |
54a6eb5c | 1541 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
dd1a239f | 1542 | struct zoneref *z; |
54a6eb5c | 1543 | struct zone *zone; |
1cfb419b | 1544 | |
408d8544 | 1545 | sc->all_unreclaimable = 1; |
54a6eb5c | 1546 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
f3fe6512 | 1547 | if (!populated_zone(zone)) |
1da177e4 | 1548 | continue; |
1cfb419b KH |
1549 | /* |
1550 | * Take care memory controller reclaiming has small influence | |
1551 | * to global LRU. | |
1552 | */ | |
e72e2bd6 | 1553 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1554 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1555 | continue; | |
1556 | note_zone_scanning_priority(zone, priority); | |
1da177e4 | 1557 | |
1cfb419b KH |
1558 | if (zone_is_all_unreclaimable(zone) && |
1559 | priority != DEF_PRIORITY) | |
1560 | continue; /* Let kswapd poll it */ | |
1561 | sc->all_unreclaimable = 0; | |
1562 | } else { | |
1563 | /* | |
1564 | * Ignore cpuset limitation here. We just want to reduce | |
1565 | * # of used pages by us regardless of memory shortage. | |
1566 | */ | |
1567 | sc->all_unreclaimable = 0; | |
1568 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, | |
1569 | priority); | |
1570 | } | |
408d8544 | 1571 | |
a79311c1 | 1572 | shrink_zone(priority, zone, sc); |
1da177e4 LT |
1573 | } |
1574 | } | |
4f98a2fe | 1575 | |
1da177e4 LT |
1576 | /* |
1577 | * This is the main entry point to direct page reclaim. | |
1578 | * | |
1579 | * If a full scan of the inactive list fails to free enough memory then we | |
1580 | * are "out of memory" and something needs to be killed. | |
1581 | * | |
1582 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1583 | * high - the zone may be full of dirty or under-writeback pages, which this | |
1584 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
1585 | * hope that some of these pages can be written. But if the allocating task | |
1586 | * holds filesystem locks which prevent writeout this might not work, and the | |
1587 | * allocation attempt will fail. | |
a41f24ea NA |
1588 | * |
1589 | * returns: 0, if no pages reclaimed | |
1590 | * else, the number of pages reclaimed | |
1da177e4 | 1591 | */ |
dac1d27b | 1592 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1593 | struct scan_control *sc) |
1da177e4 LT |
1594 | { |
1595 | int priority; | |
c700be3d | 1596 | unsigned long ret = 0; |
69e05944 | 1597 | unsigned long total_scanned = 0; |
1da177e4 | 1598 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 | 1599 | unsigned long lru_pages = 0; |
dd1a239f | 1600 | struct zoneref *z; |
54a6eb5c | 1601 | struct zone *zone; |
dd1a239f | 1602 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
1da177e4 | 1603 | |
873b4771 KK |
1604 | delayacct_freepages_start(); |
1605 | ||
e72e2bd6 | 1606 | if (scanning_global_lru(sc)) |
1cfb419b KH |
1607 | count_vm_event(ALLOCSTALL); |
1608 | /* | |
1609 | * mem_cgroup will not do shrink_slab. | |
1610 | */ | |
e72e2bd6 | 1611 | if (scanning_global_lru(sc)) { |
54a6eb5c | 1612 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1da177e4 | 1613 | |
1cfb419b KH |
1614 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1615 | continue; | |
1da177e4 | 1616 | |
4f98a2fe | 1617 | lru_pages += zone_lru_pages(zone); |
1cfb419b | 1618 | } |
1da177e4 LT |
1619 | } |
1620 | ||
1621 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1622 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1623 | if (!priority) |
1624 | disable_swap_token(); | |
a79311c1 | 1625 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1626 | /* |
1627 | * Don't shrink slabs when reclaiming memory from | |
1628 | * over limit cgroups | |
1629 | */ | |
e72e2bd6 | 1630 | if (scanning_global_lru(sc)) { |
dd1a239f | 1631 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1632 | if (reclaim_state) { |
a79311c1 | 1633 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1634 | reclaim_state->reclaimed_slab = 0; |
1635 | } | |
1da177e4 | 1636 | } |
66e1707b | 1637 | total_scanned += sc->nr_scanned; |
a79311c1 RR |
1638 | if (sc->nr_reclaimed >= sc->swap_cluster_max) { |
1639 | ret = sc->nr_reclaimed; | |
1da177e4 LT |
1640 | goto out; |
1641 | } | |
1642 | ||
1643 | /* | |
1644 | * Try to write back as many pages as we just scanned. This | |
1645 | * tends to cause slow streaming writers to write data to the | |
1646 | * disk smoothly, at the dirtying rate, which is nice. But | |
1647 | * that's undesirable in laptop mode, where we *want* lumpy | |
1648 | * writeout. So in laptop mode, write out the whole world. | |
1649 | */ | |
66e1707b BS |
1650 | if (total_scanned > sc->swap_cluster_max + |
1651 | sc->swap_cluster_max / 2) { | |
687a21ce | 1652 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
66e1707b | 1653 | sc->may_writepage = 1; |
1da177e4 LT |
1654 | } |
1655 | ||
1656 | /* Take a nap, wait for some writeback to complete */ | |
4dd4b920 | 1657 | if (sc->nr_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1658 | congestion_wait(WRITE, HZ/10); |
1da177e4 | 1659 | } |
87547ee9 | 1660 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
e72e2bd6 | 1661 | if (!sc->all_unreclaimable && scanning_global_lru(sc)) |
a79311c1 | 1662 | ret = sc->nr_reclaimed; |
1da177e4 | 1663 | out: |
3bb1a852 MB |
1664 | /* |
1665 | * Now that we've scanned all the zones at this priority level, note | |
1666 | * that level within the zone so that the next thread which performs | |
1667 | * scanning of this zone will immediately start out at this priority | |
1668 | * level. This affects only the decision whether or not to bring | |
1669 | * mapped pages onto the inactive list. | |
1670 | */ | |
1671 | if (priority < 0) | |
1672 | priority = 0; | |
1da177e4 | 1673 | |
e72e2bd6 | 1674 | if (scanning_global_lru(sc)) { |
54a6eb5c | 1675 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1cfb419b KH |
1676 | |
1677 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1678 | continue; | |
1679 | ||
1680 | zone->prev_priority = priority; | |
1681 | } | |
1682 | } else | |
1683 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); | |
1da177e4 | 1684 | |
873b4771 KK |
1685 | delayacct_freepages_end(); |
1686 | ||
1da177e4 LT |
1687 | return ret; |
1688 | } | |
1689 | ||
dac1d27b MG |
1690 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
1691 | gfp_t gfp_mask) | |
66e1707b BS |
1692 | { |
1693 | struct scan_control sc = { | |
1694 | .gfp_mask = gfp_mask, | |
1695 | .may_writepage = !laptop_mode, | |
1696 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1697 | .may_swap = 1, | |
1698 | .swappiness = vm_swappiness, | |
1699 | .order = order, | |
1700 | .mem_cgroup = NULL, | |
1701 | .isolate_pages = isolate_pages_global, | |
1702 | }; | |
1703 | ||
dd1a239f | 1704 | return do_try_to_free_pages(zonelist, &sc); |
66e1707b BS |
1705 | } |
1706 | ||
00f0b825 | 1707 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1708 | |
e1a1cd59 | 1709 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
1710 | gfp_t gfp_mask, |
1711 | bool noswap, | |
1712 | unsigned int swappiness) | |
66e1707b BS |
1713 | { |
1714 | struct scan_control sc = { | |
66e1707b BS |
1715 | .may_writepage = !laptop_mode, |
1716 | .may_swap = 1, | |
1717 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
a7885eb8 | 1718 | .swappiness = swappiness, |
66e1707b BS |
1719 | .order = 0, |
1720 | .mem_cgroup = mem_cont, | |
1721 | .isolate_pages = mem_cgroup_isolate_pages, | |
1722 | }; | |
dac1d27b | 1723 | struct zonelist *zonelist; |
66e1707b | 1724 | |
8c7c6e34 KH |
1725 | if (noswap) |
1726 | sc.may_swap = 0; | |
1727 | ||
dd1a239f MG |
1728 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1729 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1730 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1731 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1732 | } |
1733 | #endif | |
1734 | ||
1da177e4 LT |
1735 | /* |
1736 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1737 | * they are all at pages_high. | |
1738 | * | |
1da177e4 LT |
1739 | * Returns the number of pages which were actually freed. |
1740 | * | |
1741 | * There is special handling here for zones which are full of pinned pages. | |
1742 | * This can happen if the pages are all mlocked, or if they are all used by | |
1743 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1744 | * What we do is to detect the case where all pages in the zone have been | |
1745 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1746 | * dead and from now on, only perform a short scan. Basically we're polling | |
1747 | * the zone for when the problem goes away. | |
1748 | * | |
1749 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1750 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1751 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1752 | * of the number of free pages in the lower zones. This interoperates with | |
1753 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1754 | * across the zones. | |
1755 | */ | |
d6277db4 | 1756 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1757 | { |
1da177e4 LT |
1758 | int all_zones_ok; |
1759 | int priority; | |
1760 | int i; | |
69e05944 | 1761 | unsigned long total_scanned; |
1da177e4 | 1762 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1763 | struct scan_control sc = { |
1764 | .gfp_mask = GFP_KERNEL, | |
1765 | .may_swap = 1, | |
d6277db4 RW |
1766 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1767 | .swappiness = vm_swappiness, | |
5ad333eb | 1768 | .order = order, |
66e1707b BS |
1769 | .mem_cgroup = NULL, |
1770 | .isolate_pages = isolate_pages_global, | |
179e9639 | 1771 | }; |
3bb1a852 MB |
1772 | /* |
1773 | * temp_priority is used to remember the scanning priority at which | |
1774 | * this zone was successfully refilled to free_pages == pages_high. | |
1775 | */ | |
1776 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
1777 | |
1778 | loop_again: | |
1779 | total_scanned = 0; | |
a79311c1 | 1780 | sc.nr_reclaimed = 0; |
c0bbbc73 | 1781 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1782 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 1783 | |
3bb1a852 MB |
1784 | for (i = 0; i < pgdat->nr_zones; i++) |
1785 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
1786 | |
1787 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1788 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1789 | unsigned long lru_pages = 0; | |
1790 | ||
f7b7fd8f RR |
1791 | /* The swap token gets in the way of swapout... */ |
1792 | if (!priority) | |
1793 | disable_swap_token(); | |
1794 | ||
1da177e4 LT |
1795 | all_zones_ok = 1; |
1796 | ||
d6277db4 RW |
1797 | /* |
1798 | * Scan in the highmem->dma direction for the highest | |
1799 | * zone which needs scanning | |
1800 | */ | |
1801 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1802 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1803 | |
d6277db4 RW |
1804 | if (!populated_zone(zone)) |
1805 | continue; | |
1da177e4 | 1806 | |
e815af95 DR |
1807 | if (zone_is_all_unreclaimable(zone) && |
1808 | priority != DEF_PRIORITY) | |
d6277db4 | 1809 | continue; |
1da177e4 | 1810 | |
556adecb RR |
1811 | /* |
1812 | * Do some background aging of the anon list, to give | |
1813 | * pages a chance to be referenced before reclaiming. | |
1814 | */ | |
14797e23 | 1815 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
1816 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
1817 | &sc, priority, 0); | |
1818 | ||
d6277db4 RW |
1819 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1820 | 0, 0)) { | |
1821 | end_zone = i; | |
e1dbeda6 | 1822 | break; |
1da177e4 | 1823 | } |
1da177e4 | 1824 | } |
e1dbeda6 AM |
1825 | if (i < 0) |
1826 | goto out; | |
1827 | ||
1da177e4 LT |
1828 | for (i = 0; i <= end_zone; i++) { |
1829 | struct zone *zone = pgdat->node_zones + i; | |
1830 | ||
4f98a2fe | 1831 | lru_pages += zone_lru_pages(zone); |
1da177e4 LT |
1832 | } |
1833 | ||
1834 | /* | |
1835 | * Now scan the zone in the dma->highmem direction, stopping | |
1836 | * at the last zone which needs scanning. | |
1837 | * | |
1838 | * We do this because the page allocator works in the opposite | |
1839 | * direction. This prevents the page allocator from allocating | |
1840 | * pages behind kswapd's direction of progress, which would | |
1841 | * cause too much scanning of the lower zones. | |
1842 | */ | |
1843 | for (i = 0; i <= end_zone; i++) { | |
1844 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1845 | int nr_slab; |
1da177e4 | 1846 | |
f3fe6512 | 1847 | if (!populated_zone(zone)) |
1da177e4 LT |
1848 | continue; |
1849 | ||
e815af95 DR |
1850 | if (zone_is_all_unreclaimable(zone) && |
1851 | priority != DEF_PRIORITY) | |
1da177e4 LT |
1852 | continue; |
1853 | ||
d6277db4 RW |
1854 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1855 | end_zone, 0)) | |
1856 | all_zones_ok = 0; | |
3bb1a852 | 1857 | temp_priority[i] = priority; |
1da177e4 | 1858 | sc.nr_scanned = 0; |
3bb1a852 | 1859 | note_zone_scanning_priority(zone, priority); |
32a4330d RR |
1860 | /* |
1861 | * We put equal pressure on every zone, unless one | |
1862 | * zone has way too many pages free already. | |
1863 | */ | |
1864 | if (!zone_watermark_ok(zone, order, 8*zone->pages_high, | |
1865 | end_zone, 0)) | |
a79311c1 | 1866 | shrink_zone(priority, zone, &sc); |
1da177e4 | 1867 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1868 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1869 | lru_pages); | |
a79311c1 | 1870 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 1871 | total_scanned += sc.nr_scanned; |
e815af95 | 1872 | if (zone_is_all_unreclaimable(zone)) |
1da177e4 | 1873 | continue; |
b15e0905 | 1874 | if (nr_slab == 0 && zone->pages_scanned >= |
4f98a2fe | 1875 | (zone_lru_pages(zone) * 6)) |
e815af95 DR |
1876 | zone_set_flag(zone, |
1877 | ZONE_ALL_UNRECLAIMABLE); | |
1da177e4 LT |
1878 | /* |
1879 | * If we've done a decent amount of scanning and | |
1880 | * the reclaim ratio is low, start doing writepage | |
1881 | * even in laptop mode | |
1882 | */ | |
1883 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 1884 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 LT |
1885 | sc.may_writepage = 1; |
1886 | } | |
1da177e4 LT |
1887 | if (all_zones_ok) |
1888 | break; /* kswapd: all done */ | |
1889 | /* | |
1890 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1891 | * another pass across the zones. | |
1892 | */ | |
4dd4b920 | 1893 | if (total_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1894 | congestion_wait(WRITE, HZ/10); |
1da177e4 LT |
1895 | |
1896 | /* | |
1897 | * We do this so kswapd doesn't build up large priorities for | |
1898 | * example when it is freeing in parallel with allocators. It | |
1899 | * matches the direct reclaim path behaviour in terms of impact | |
1900 | * on zone->*_priority. | |
1901 | */ | |
a79311c1 | 1902 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1903 | break; |
1904 | } | |
1905 | out: | |
3bb1a852 MB |
1906 | /* |
1907 | * Note within each zone the priority level at which this zone was | |
1908 | * brought into a happy state. So that the next thread which scans this | |
1909 | * zone will start out at that priority level. | |
1910 | */ | |
1da177e4 LT |
1911 | for (i = 0; i < pgdat->nr_zones; i++) { |
1912 | struct zone *zone = pgdat->node_zones + i; | |
1913 | ||
3bb1a852 | 1914 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
1915 | } |
1916 | if (!all_zones_ok) { | |
1917 | cond_resched(); | |
8357376d RW |
1918 | |
1919 | try_to_freeze(); | |
1920 | ||
73ce02e9 KM |
1921 | /* |
1922 | * Fragmentation may mean that the system cannot be | |
1923 | * rebalanced for high-order allocations in all zones. | |
1924 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
1925 | * it means the zones have been fully scanned and are still | |
1926 | * not balanced. For high-order allocations, there is | |
1927 | * little point trying all over again as kswapd may | |
1928 | * infinite loop. | |
1929 | * | |
1930 | * Instead, recheck all watermarks at order-0 as they | |
1931 | * are the most important. If watermarks are ok, kswapd will go | |
1932 | * back to sleep. High-order users can still perform direct | |
1933 | * reclaim if they wish. | |
1934 | */ | |
1935 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
1936 | order = sc.order = 0; | |
1937 | ||
1da177e4 LT |
1938 | goto loop_again; |
1939 | } | |
1940 | ||
a79311c1 | 1941 | return sc.nr_reclaimed; |
1da177e4 LT |
1942 | } |
1943 | ||
1944 | /* | |
1945 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 1946 | * from the init process. |
1da177e4 LT |
1947 | * |
1948 | * This basically trickles out pages so that we have _some_ | |
1949 | * free memory available even if there is no other activity | |
1950 | * that frees anything up. This is needed for things like routing | |
1951 | * etc, where we otherwise might have all activity going on in | |
1952 | * asynchronous contexts that cannot page things out. | |
1953 | * | |
1954 | * If there are applications that are active memory-allocators | |
1955 | * (most normal use), this basically shouldn't matter. | |
1956 | */ | |
1957 | static int kswapd(void *p) | |
1958 | { | |
1959 | unsigned long order; | |
1960 | pg_data_t *pgdat = (pg_data_t*)p; | |
1961 | struct task_struct *tsk = current; | |
1962 | DEFINE_WAIT(wait); | |
1963 | struct reclaim_state reclaim_state = { | |
1964 | .reclaimed_slab = 0, | |
1965 | }; | |
c5f59f08 | 1966 | node_to_cpumask_ptr(cpumask, pgdat->node_id); |
1da177e4 | 1967 | |
174596a0 | 1968 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 1969 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
1970 | current->reclaim_state = &reclaim_state; |
1971 | ||
1972 | /* | |
1973 | * Tell the memory management that we're a "memory allocator", | |
1974 | * and that if we need more memory we should get access to it | |
1975 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1976 | * never get caught in the normal page freeing logic. | |
1977 | * | |
1978 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1979 | * you need a small amount of memory in order to be able to | |
1980 | * page out something else, and this flag essentially protects | |
1981 | * us from recursively trying to free more memory as we're | |
1982 | * trying to free the first piece of memory in the first place). | |
1983 | */ | |
930d9152 | 1984 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 1985 | set_freezable(); |
1da177e4 LT |
1986 | |
1987 | order = 0; | |
1988 | for ( ; ; ) { | |
1989 | unsigned long new_order; | |
3e1d1d28 | 1990 | |
1da177e4 LT |
1991 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
1992 | new_order = pgdat->kswapd_max_order; | |
1993 | pgdat->kswapd_max_order = 0; | |
1994 | if (order < new_order) { | |
1995 | /* | |
1996 | * Don't sleep if someone wants a larger 'order' | |
1997 | * allocation | |
1998 | */ | |
1999 | order = new_order; | |
2000 | } else { | |
b1296cc4 RW |
2001 | if (!freezing(current)) |
2002 | schedule(); | |
2003 | ||
1da177e4 LT |
2004 | order = pgdat->kswapd_max_order; |
2005 | } | |
2006 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2007 | ||
b1296cc4 RW |
2008 | if (!try_to_freeze()) { |
2009 | /* We can speed up thawing tasks if we don't call | |
2010 | * balance_pgdat after returning from the refrigerator | |
2011 | */ | |
2012 | balance_pgdat(pgdat, order); | |
2013 | } | |
1da177e4 LT |
2014 | } |
2015 | return 0; | |
2016 | } | |
2017 | ||
2018 | /* | |
2019 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2020 | */ | |
2021 | void wakeup_kswapd(struct zone *zone, int order) | |
2022 | { | |
2023 | pg_data_t *pgdat; | |
2024 | ||
f3fe6512 | 2025 | if (!populated_zone(zone)) |
1da177e4 LT |
2026 | return; |
2027 | ||
2028 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 2029 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
2030 | return; |
2031 | if (pgdat->kswapd_max_order < order) | |
2032 | pgdat->kswapd_max_order = order; | |
02a0e53d | 2033 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2034 | return; |
8d0986e2 | 2035 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2036 | return; |
8d0986e2 | 2037 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2038 | } |
2039 | ||
4f98a2fe RR |
2040 | unsigned long global_lru_pages(void) |
2041 | { | |
2042 | return global_page_state(NR_ACTIVE_ANON) | |
2043 | + global_page_state(NR_ACTIVE_FILE) | |
2044 | + global_page_state(NR_INACTIVE_ANON) | |
2045 | + global_page_state(NR_INACTIVE_FILE); | |
2046 | } | |
2047 | ||
1da177e4 LT |
2048 | #ifdef CONFIG_PM |
2049 | /* | |
d6277db4 RW |
2050 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
2051 | * from LRU lists system-wide, for given pass and priority, and returns the | |
2052 | * number of reclaimed pages | |
2053 | * | |
2054 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
2055 | */ | |
e07aa05b NC |
2056 | static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, |
2057 | int pass, struct scan_control *sc) | |
d6277db4 RW |
2058 | { |
2059 | struct zone *zone; | |
0cb57258 | 2060 | unsigned long ret = 0; |
d6277db4 RW |
2061 | |
2062 | for_each_zone(zone) { | |
0cb57258 | 2063 | enum lru_list l; |
d6277db4 RW |
2064 | |
2065 | if (!populated_zone(zone)) | |
2066 | continue; | |
e815af95 | 2067 | if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) |
d6277db4 RW |
2068 | continue; |
2069 | ||
894bc310 | 2070 | for_each_evictable_lru(l) { |
0cb57258 JW |
2071 | enum zone_stat_item ls = NR_LRU_BASE + l; |
2072 | unsigned long lru_pages = zone_page_state(zone, ls); | |
2073 | ||
894bc310 | 2074 | /* For pass = 0, we don't shrink the active list */ |
0cb57258 JW |
2075 | if (pass == 0 && (l == LRU_ACTIVE_ANON || |
2076 | l == LRU_ACTIVE_FILE)) | |
b69408e8 CL |
2077 | continue; |
2078 | ||
0cb57258 | 2079 | zone->lru[l].nr_scan += (lru_pages >> prio) + 1; |
b69408e8 | 2080 | if (zone->lru[l].nr_scan >= nr_pages || pass > 3) { |
0cb57258 JW |
2081 | unsigned long nr_to_scan; |
2082 | ||
b69408e8 | 2083 | zone->lru[l].nr_scan = 0; |
0cb57258 | 2084 | nr_to_scan = min(nr_pages, lru_pages); |
b69408e8 CL |
2085 | ret += shrink_list(l, nr_to_scan, zone, |
2086 | sc, prio); | |
2087 | if (ret >= nr_pages) | |
2088 | return ret; | |
d6277db4 RW |
2089 | } |
2090 | } | |
d6277db4 | 2091 | } |
d6277db4 RW |
2092 | return ret; |
2093 | } | |
2094 | ||
2095 | /* | |
2096 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
2097 | * freed pages. | |
2098 | * | |
2099 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2100 | * LRU order by reclaiming preferentially | |
2101 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2102 | */ |
69e05944 | 2103 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 2104 | { |
d6277db4 | 2105 | unsigned long lru_pages, nr_slab; |
69e05944 | 2106 | unsigned long ret = 0; |
d6277db4 RW |
2107 | int pass; |
2108 | struct reclaim_state reclaim_state; | |
d6277db4 RW |
2109 | struct scan_control sc = { |
2110 | .gfp_mask = GFP_KERNEL, | |
2111 | .may_swap = 0, | |
2112 | .swap_cluster_max = nr_pages, | |
2113 | .may_writepage = 1, | |
66e1707b | 2114 | .isolate_pages = isolate_pages_global, |
1da177e4 LT |
2115 | }; |
2116 | ||
2117 | current->reclaim_state = &reclaim_state; | |
69e05944 | 2118 | |
4f98a2fe | 2119 | lru_pages = global_lru_pages(); |
972d1a7b | 2120 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
2121 | /* If slab caches are huge, it's better to hit them first */ |
2122 | while (nr_slab >= lru_pages) { | |
2123 | reclaim_state.reclaimed_slab = 0; | |
2124 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
2125 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 2126 | break; |
d6277db4 RW |
2127 | |
2128 | ret += reclaim_state.reclaimed_slab; | |
2129 | if (ret >= nr_pages) | |
2130 | goto out; | |
2131 | ||
2132 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 2133 | } |
d6277db4 RW |
2134 | |
2135 | /* | |
2136 | * We try to shrink LRUs in 5 passes: | |
2137 | * 0 = Reclaim from inactive_list only | |
2138 | * 1 = Reclaim from active list but don't reclaim mapped | |
2139 | * 2 = 2nd pass of type 1 | |
2140 | * 3 = Reclaim mapped (normal reclaim) | |
2141 | * 4 = 2nd pass of type 3 | |
2142 | */ | |
2143 | for (pass = 0; pass < 5; pass++) { | |
2144 | int prio; | |
2145 | ||
d6277db4 | 2146 | /* Force reclaiming mapped pages in the passes #3 and #4 */ |
3049103d | 2147 | if (pass > 2) |
d6277db4 | 2148 | sc.may_swap = 1; |
d6277db4 RW |
2149 | |
2150 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
2151 | unsigned long nr_to_scan = nr_pages - ret; | |
2152 | ||
d6277db4 | 2153 | sc.nr_scanned = 0; |
d6277db4 RW |
2154 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
2155 | if (ret >= nr_pages) | |
2156 | goto out; | |
2157 | ||
2158 | reclaim_state.reclaimed_slab = 0; | |
76395d37 | 2159 | shrink_slab(sc.nr_scanned, sc.gfp_mask, |
4f98a2fe | 2160 | global_lru_pages()); |
d6277db4 RW |
2161 | ret += reclaim_state.reclaimed_slab; |
2162 | if (ret >= nr_pages) | |
2163 | goto out; | |
2164 | ||
2165 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
3fcfab16 | 2166 | congestion_wait(WRITE, HZ / 10); |
d6277db4 | 2167 | } |
248a0301 | 2168 | } |
d6277db4 RW |
2169 | |
2170 | /* | |
2171 | * If ret = 0, we could not shrink LRUs, but there may be something | |
2172 | * in slab caches | |
2173 | */ | |
76395d37 | 2174 | if (!ret) { |
d6277db4 RW |
2175 | do { |
2176 | reclaim_state.reclaimed_slab = 0; | |
4f98a2fe | 2177 | shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages()); |
d6277db4 RW |
2178 | ret += reclaim_state.reclaimed_slab; |
2179 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
76395d37 | 2180 | } |
d6277db4 RW |
2181 | |
2182 | out: | |
1da177e4 | 2183 | current->reclaim_state = NULL; |
d6277db4 | 2184 | |
1da177e4 LT |
2185 | return ret; |
2186 | } | |
2187 | #endif | |
2188 | ||
1da177e4 LT |
2189 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2190 | not required for correctness. So if the last cpu in a node goes | |
2191 | away, we get changed to run anywhere: as the first one comes back, | |
2192 | restore their cpu bindings. */ | |
9c7b216d | 2193 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2194 | unsigned long action, void *hcpu) |
1da177e4 | 2195 | { |
58c0a4a7 | 2196 | int nid; |
1da177e4 | 2197 | |
8bb78442 | 2198 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2199 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 MT |
2200 | pg_data_t *pgdat = NODE_DATA(nid); |
2201 | node_to_cpumask_ptr(mask, pgdat->node_id); | |
2202 | ||
3e597945 | 2203 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2204 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2205 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2206 | } |
2207 | } | |
2208 | return NOTIFY_OK; | |
2209 | } | |
1da177e4 | 2210 | |
3218ae14 YG |
2211 | /* |
2212 | * This kswapd start function will be called by init and node-hot-add. | |
2213 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2214 | */ | |
2215 | int kswapd_run(int nid) | |
2216 | { | |
2217 | pg_data_t *pgdat = NODE_DATA(nid); | |
2218 | int ret = 0; | |
2219 | ||
2220 | if (pgdat->kswapd) | |
2221 | return 0; | |
2222 | ||
2223 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2224 | if (IS_ERR(pgdat->kswapd)) { | |
2225 | /* failure at boot is fatal */ | |
2226 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2227 | printk("Failed to start kswapd on node %d\n",nid); | |
2228 | ret = -1; | |
2229 | } | |
2230 | return ret; | |
2231 | } | |
2232 | ||
1da177e4 LT |
2233 | static int __init kswapd_init(void) |
2234 | { | |
3218ae14 | 2235 | int nid; |
69e05944 | 2236 | |
1da177e4 | 2237 | swap_setup(); |
9422ffba | 2238 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2239 | kswapd_run(nid); |
1da177e4 LT |
2240 | hotcpu_notifier(cpu_callback, 0); |
2241 | return 0; | |
2242 | } | |
2243 | ||
2244 | module_init(kswapd_init) | |
9eeff239 CL |
2245 | |
2246 | #ifdef CONFIG_NUMA | |
2247 | /* | |
2248 | * Zone reclaim mode | |
2249 | * | |
2250 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2251 | * the watermarks. | |
9eeff239 CL |
2252 | */ |
2253 | int zone_reclaim_mode __read_mostly; | |
2254 | ||
1b2ffb78 | 2255 | #define RECLAIM_OFF 0 |
7d03431c | 2256 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2257 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2258 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2259 | ||
a92f7126 CL |
2260 | /* |
2261 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2262 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2263 | * a zone. | |
2264 | */ | |
2265 | #define ZONE_RECLAIM_PRIORITY 4 | |
2266 | ||
9614634f CL |
2267 | /* |
2268 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2269 | * occur. | |
2270 | */ | |
2271 | int sysctl_min_unmapped_ratio = 1; | |
2272 | ||
0ff38490 CL |
2273 | /* |
2274 | * If the number of slab pages in a zone grows beyond this percentage then | |
2275 | * slab reclaim needs to occur. | |
2276 | */ | |
2277 | int sysctl_min_slab_ratio = 5; | |
2278 | ||
9eeff239 CL |
2279 | /* |
2280 | * Try to free up some pages from this zone through reclaim. | |
2281 | */ | |
179e9639 | 2282 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2283 | { |
7fb2d46d | 2284 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2285 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2286 | struct task_struct *p = current; |
2287 | struct reclaim_state reclaim_state; | |
8695949a | 2288 | int priority; |
179e9639 AM |
2289 | struct scan_control sc = { |
2290 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
2291 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
2292 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
2293 | SWAP_CLUSTER_MAX), | |
179e9639 | 2294 | .gfp_mask = gfp_mask, |
d6277db4 | 2295 | .swappiness = vm_swappiness, |
66e1707b | 2296 | .isolate_pages = isolate_pages_global, |
179e9639 | 2297 | }; |
83e33a47 | 2298 | unsigned long slab_reclaimable; |
9eeff239 CL |
2299 | |
2300 | disable_swap_token(); | |
9eeff239 | 2301 | cond_resched(); |
d4f7796e CL |
2302 | /* |
2303 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2304 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2305 | * and RECLAIM_SWAP. | |
2306 | */ | |
2307 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
2308 | reclaim_state.reclaimed_slab = 0; |
2309 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2310 | |
0ff38490 CL |
2311 | if (zone_page_state(zone, NR_FILE_PAGES) - |
2312 | zone_page_state(zone, NR_FILE_MAPPED) > | |
2313 | zone->min_unmapped_pages) { | |
2314 | /* | |
2315 | * Free memory by calling shrink zone with increasing | |
2316 | * priorities until we have enough memory freed. | |
2317 | */ | |
2318 | priority = ZONE_RECLAIM_PRIORITY; | |
2319 | do { | |
3bb1a852 | 2320 | note_zone_scanning_priority(zone, priority); |
a79311c1 | 2321 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2322 | priority--; |
a79311c1 | 2323 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2324 | } |
c84db23c | 2325 | |
83e33a47 CL |
2326 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2327 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2328 | /* |
7fb2d46d | 2329 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2330 | * many pages were freed in this zone. So we take the current |
2331 | * number of slab pages and shake the slab until it is reduced | |
2332 | * by the same nr_pages that we used for reclaiming unmapped | |
2333 | * pages. | |
2a16e3f4 | 2334 | * |
0ff38490 CL |
2335 | * Note that shrink_slab will free memory on all zones and may |
2336 | * take a long time. | |
2a16e3f4 | 2337 | */ |
0ff38490 | 2338 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2339 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2340 | slab_reclaimable - nr_pages) | |
0ff38490 | 2341 | ; |
83e33a47 CL |
2342 | |
2343 | /* | |
2344 | * Update nr_reclaimed by the number of slab pages we | |
2345 | * reclaimed from this zone. | |
2346 | */ | |
a79311c1 | 2347 | sc.nr_reclaimed += slab_reclaimable - |
83e33a47 | 2348 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2a16e3f4 CL |
2349 | } |
2350 | ||
9eeff239 | 2351 | p->reclaim_state = NULL; |
d4f7796e | 2352 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
a79311c1 | 2353 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2354 | } |
179e9639 AM |
2355 | |
2356 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2357 | { | |
179e9639 | 2358 | int node_id; |
d773ed6b | 2359 | int ret; |
179e9639 AM |
2360 | |
2361 | /* | |
0ff38490 CL |
2362 | * Zone reclaim reclaims unmapped file backed pages and |
2363 | * slab pages if we are over the defined limits. | |
34aa1330 | 2364 | * |
9614634f CL |
2365 | * A small portion of unmapped file backed pages is needed for |
2366 | * file I/O otherwise pages read by file I/O will be immediately | |
2367 | * thrown out if the zone is overallocated. So we do not reclaim | |
2368 | * if less than a specified percentage of the zone is used by | |
2369 | * unmapped file backed pages. | |
179e9639 | 2370 | */ |
34aa1330 | 2371 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
2372 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
2373 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
2374 | <= zone->min_slab_pages) | |
9614634f | 2375 | return 0; |
179e9639 | 2376 | |
d773ed6b DR |
2377 | if (zone_is_all_unreclaimable(zone)) |
2378 | return 0; | |
2379 | ||
179e9639 | 2380 | /* |
d773ed6b | 2381 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2382 | */ |
d773ed6b | 2383 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
179e9639 AM |
2384 | return 0; |
2385 | ||
2386 | /* | |
2387 | * Only run zone reclaim on the local zone or on zones that do not | |
2388 | * have associated processors. This will favor the local processor | |
2389 | * over remote processors and spread off node memory allocations | |
2390 | * as wide as possible. | |
2391 | */ | |
89fa3024 | 2392 | node_id = zone_to_nid(zone); |
37c0708d | 2393 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
179e9639 | 2394 | return 0; |
d773ed6b DR |
2395 | |
2396 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
2397 | return 0; | |
2398 | ret = __zone_reclaim(zone, gfp_mask, order); | |
2399 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2400 | ||
2401 | return ret; | |
179e9639 | 2402 | } |
9eeff239 | 2403 | #endif |
894bc310 LS |
2404 | |
2405 | #ifdef CONFIG_UNEVICTABLE_LRU | |
2406 | /* | |
2407 | * page_evictable - test whether a page is evictable | |
2408 | * @page: the page to test | |
2409 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2410 | * | |
2411 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2412 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2413 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2414 | * |
2415 | * Reasons page might not be evictable: | |
ba9ddf49 | 2416 | * (1) page's mapping marked unevictable |
b291f000 | 2417 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2418 | * |
894bc310 LS |
2419 | */ |
2420 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2421 | { | |
2422 | ||
ba9ddf49 LS |
2423 | if (mapping_unevictable(page_mapping(page))) |
2424 | return 0; | |
2425 | ||
b291f000 NP |
2426 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2427 | return 0; | |
894bc310 LS |
2428 | |
2429 | return 1; | |
2430 | } | |
89e004ea LS |
2431 | |
2432 | /** | |
2433 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2434 | * @page: page to check evictability and move to appropriate lru list | |
2435 | * @zone: zone page is in | |
2436 | * | |
2437 | * Checks a page for evictability and moves the page to the appropriate | |
2438 | * zone lru list. | |
2439 | * | |
2440 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2441 | * have PageUnevictable set. | |
2442 | */ | |
2443 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2444 | { | |
2445 | VM_BUG_ON(PageActive(page)); | |
2446 | ||
2447 | retry: | |
2448 | ClearPageUnevictable(page); | |
2449 | if (page_evictable(page, NULL)) { | |
2450 | enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page); | |
af936a16 | 2451 | |
89e004ea LS |
2452 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2453 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2454 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2455 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2456 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2457 | } else { | |
2458 | /* | |
2459 | * rotate unevictable list | |
2460 | */ | |
2461 | SetPageUnevictable(page); | |
2462 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2463 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2464 | if (page_evictable(page, NULL)) |
2465 | goto retry; | |
2466 | } | |
2467 | } | |
2468 | ||
2469 | /** | |
2470 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2471 | * @mapping: struct address_space to scan for evictable pages | |
2472 | * | |
2473 | * Scan all pages in mapping. Check unevictable pages for | |
2474 | * evictability and move them to the appropriate zone lru list. | |
2475 | */ | |
2476 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2477 | { | |
2478 | pgoff_t next = 0; | |
2479 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2480 | PAGE_CACHE_SHIFT; | |
2481 | struct zone *zone; | |
2482 | struct pagevec pvec; | |
2483 | ||
2484 | if (mapping->nrpages == 0) | |
2485 | return; | |
2486 | ||
2487 | pagevec_init(&pvec, 0); | |
2488 | while (next < end && | |
2489 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2490 | int i; | |
2491 | int pg_scanned = 0; | |
2492 | ||
2493 | zone = NULL; | |
2494 | ||
2495 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2496 | struct page *page = pvec.pages[i]; | |
2497 | pgoff_t page_index = page->index; | |
2498 | struct zone *pagezone = page_zone(page); | |
2499 | ||
2500 | pg_scanned++; | |
2501 | if (page_index > next) | |
2502 | next = page_index; | |
2503 | next++; | |
2504 | ||
2505 | if (pagezone != zone) { | |
2506 | if (zone) | |
2507 | spin_unlock_irq(&zone->lru_lock); | |
2508 | zone = pagezone; | |
2509 | spin_lock_irq(&zone->lru_lock); | |
2510 | } | |
2511 | ||
2512 | if (PageLRU(page) && PageUnevictable(page)) | |
2513 | check_move_unevictable_page(page, zone); | |
2514 | } | |
2515 | if (zone) | |
2516 | spin_unlock_irq(&zone->lru_lock); | |
2517 | pagevec_release(&pvec); | |
2518 | ||
2519 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2520 | } | |
2521 | ||
2522 | } | |
af936a16 LS |
2523 | |
2524 | /** | |
2525 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2526 | * @zone - zone of which to scan the unevictable list | |
2527 | * | |
2528 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2529 | * evictable. Move those that have to @zone's inactive list where they | |
2530 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2531 | * to reactivate them. Pages that are still unevictable are rotated | |
2532 | * back onto @zone's unevictable list. | |
2533 | */ | |
2534 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2535 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2536 | { |
2537 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2538 | unsigned long scan; | |
2539 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2540 | ||
2541 | while (nr_to_scan > 0) { | |
2542 | unsigned long batch_size = min(nr_to_scan, | |
2543 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2544 | ||
2545 | spin_lock_irq(&zone->lru_lock); | |
2546 | for (scan = 0; scan < batch_size; scan++) { | |
2547 | struct page *page = lru_to_page(l_unevictable); | |
2548 | ||
2549 | if (!trylock_page(page)) | |
2550 | continue; | |
2551 | ||
2552 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
2553 | ||
2554 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
2555 | check_move_unevictable_page(page, zone); | |
2556 | ||
2557 | unlock_page(page); | |
2558 | } | |
2559 | spin_unlock_irq(&zone->lru_lock); | |
2560 | ||
2561 | nr_to_scan -= batch_size; | |
2562 | } | |
2563 | } | |
2564 | ||
2565 | ||
2566 | /** | |
2567 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
2568 | * | |
2569 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
2570 | * pages that have become evictable. Move those back to the zones' | |
2571 | * inactive list where they become candidates for reclaim. | |
2572 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
2573 | * and we add swap to the system. As such, it runs in the context of a task | |
2574 | * that has possibly/probably made some previously unevictable pages | |
2575 | * evictable. | |
2576 | */ | |
ff30153b | 2577 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
2578 | { |
2579 | struct zone *zone; | |
2580 | ||
2581 | for_each_zone(zone) { | |
2582 | scan_zone_unevictable_pages(zone); | |
2583 | } | |
2584 | } | |
2585 | ||
2586 | /* | |
2587 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
2588 | * all nodes' unevictable lists for evictable pages | |
2589 | */ | |
2590 | unsigned long scan_unevictable_pages; | |
2591 | ||
2592 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
2593 | struct file *file, void __user *buffer, | |
2594 | size_t *length, loff_t *ppos) | |
2595 | { | |
2596 | proc_doulongvec_minmax(table, write, file, buffer, length, ppos); | |
2597 | ||
2598 | if (write && *(unsigned long *)table->data) | |
2599 | scan_all_zones_unevictable_pages(); | |
2600 | ||
2601 | scan_unevictable_pages = 0; | |
2602 | return 0; | |
2603 | } | |
2604 | ||
2605 | /* | |
2606 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
2607 | * a specified node's per zone unevictable lists for evictable pages. | |
2608 | */ | |
2609 | ||
2610 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
2611 | struct sysdev_attribute *attr, | |
2612 | char *buf) | |
2613 | { | |
2614 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
2615 | } | |
2616 | ||
2617 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
2618 | struct sysdev_attribute *attr, | |
2619 | const char *buf, size_t count) | |
2620 | { | |
2621 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
2622 | struct zone *zone; | |
2623 | unsigned long res; | |
2624 | unsigned long req = strict_strtoul(buf, 10, &res); | |
2625 | ||
2626 | if (!req) | |
2627 | return 1; /* zero is no-op */ | |
2628 | ||
2629 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
2630 | if (!populated_zone(zone)) | |
2631 | continue; | |
2632 | scan_zone_unevictable_pages(zone); | |
2633 | } | |
2634 | return 1; | |
2635 | } | |
2636 | ||
2637 | ||
2638 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
2639 | read_scan_unevictable_node, | |
2640 | write_scan_unevictable_node); | |
2641 | ||
2642 | int scan_unevictable_register_node(struct node *node) | |
2643 | { | |
2644 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2645 | } | |
2646 | ||
2647 | void scan_unevictable_unregister_node(struct node *node) | |
2648 | { | |
2649 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2650 | } | |
2651 | ||
894bc310 | 2652 | #endif |