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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 |
91a45470 KH |
128 | #define scan_global_lru(sc) (!(sc)->mem_cgroup) |
129 | #else | |
130 | #define scan_global_lru(sc) (1) | |
131 | #endif | |
132 | ||
6e901571 KM |
133 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
134 | struct scan_control *sc) | |
135 | { | |
136 | return &zone->reclaim_stat; | |
137 | } | |
138 | ||
c9f299d9 KM |
139 | static unsigned long zone_nr_pages(struct zone *zone, struct scan_control *sc, |
140 | enum lru_list lru) | |
141 | { | |
142 | return zone_page_state(zone, NR_LRU_BASE + lru); | |
143 | } | |
144 | ||
145 | ||
1da177e4 LT |
146 | /* |
147 | * Add a shrinker callback to be called from the vm | |
148 | */ | |
8e1f936b | 149 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 150 | { |
8e1f936b RR |
151 | shrinker->nr = 0; |
152 | down_write(&shrinker_rwsem); | |
153 | list_add_tail(&shrinker->list, &shrinker_list); | |
154 | up_write(&shrinker_rwsem); | |
1da177e4 | 155 | } |
8e1f936b | 156 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
157 | |
158 | /* | |
159 | * Remove one | |
160 | */ | |
8e1f936b | 161 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
162 | { |
163 | down_write(&shrinker_rwsem); | |
164 | list_del(&shrinker->list); | |
165 | up_write(&shrinker_rwsem); | |
1da177e4 | 166 | } |
8e1f936b | 167 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
168 | |
169 | #define SHRINK_BATCH 128 | |
170 | /* | |
171 | * Call the shrink functions to age shrinkable caches | |
172 | * | |
173 | * Here we assume it costs one seek to replace a lru page and that it also | |
174 | * takes a seek to recreate a cache object. With this in mind we age equal | |
175 | * percentages of the lru and ageable caches. This should balance the seeks | |
176 | * generated by these structures. | |
177 | * | |
183ff22b | 178 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
179 | * slab to avoid swapping. |
180 | * | |
181 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
182 | * | |
183 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
184 | * are eligible for the caller's allocation attempt. It is used for balancing | |
185 | * slab reclaim versus page reclaim. | |
b15e0905 | 186 | * |
187 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 188 | */ |
69e05944 AM |
189 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
190 | unsigned long lru_pages) | |
1da177e4 LT |
191 | { |
192 | struct shrinker *shrinker; | |
69e05944 | 193 | unsigned long ret = 0; |
1da177e4 LT |
194 | |
195 | if (scanned == 0) | |
196 | scanned = SWAP_CLUSTER_MAX; | |
197 | ||
198 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 199 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
200 | |
201 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
202 | unsigned long long delta; | |
203 | unsigned long total_scan; | |
8e1f936b | 204 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
1da177e4 LT |
205 | |
206 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 207 | delta *= max_pass; |
1da177e4 LT |
208 | do_div(delta, lru_pages + 1); |
209 | shrinker->nr += delta; | |
ea164d73 AA |
210 | if (shrinker->nr < 0) { |
211 | printk(KERN_ERR "%s: nr=%ld\n", | |
d40cee24 | 212 | __func__, shrinker->nr); |
ea164d73 AA |
213 | shrinker->nr = max_pass; |
214 | } | |
215 | ||
216 | /* | |
217 | * Avoid risking looping forever due to too large nr value: | |
218 | * never try to free more than twice the estimate number of | |
219 | * freeable entries. | |
220 | */ | |
221 | if (shrinker->nr > max_pass * 2) | |
222 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
223 | |
224 | total_scan = shrinker->nr; | |
225 | shrinker->nr = 0; | |
226 | ||
227 | while (total_scan >= SHRINK_BATCH) { | |
228 | long this_scan = SHRINK_BATCH; | |
229 | int shrink_ret; | |
b15e0905 | 230 | int nr_before; |
1da177e4 | 231 | |
8e1f936b RR |
232 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
233 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); | |
1da177e4 LT |
234 | if (shrink_ret == -1) |
235 | break; | |
b15e0905 | 236 | if (shrink_ret < nr_before) |
237 | ret += nr_before - shrink_ret; | |
f8891e5e | 238 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
239 | total_scan -= this_scan; |
240 | ||
241 | cond_resched(); | |
242 | } | |
243 | ||
244 | shrinker->nr += total_scan; | |
245 | } | |
246 | up_read(&shrinker_rwsem); | |
b15e0905 | 247 | return ret; |
1da177e4 LT |
248 | } |
249 | ||
250 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
251 | static inline int page_mapping_inuse(struct page *page) | |
252 | { | |
253 | struct address_space *mapping; | |
254 | ||
255 | /* Page is in somebody's page tables. */ | |
256 | if (page_mapped(page)) | |
257 | return 1; | |
258 | ||
259 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
260 | if (PageSwapCache(page)) | |
261 | return 1; | |
262 | ||
263 | mapping = page_mapping(page); | |
264 | if (!mapping) | |
265 | return 0; | |
266 | ||
267 | /* File is mmap'd by somebody? */ | |
268 | return mapping_mapped(mapping); | |
269 | } | |
270 | ||
271 | static inline int is_page_cache_freeable(struct page *page) | |
272 | { | |
273 | return page_count(page) - !!PagePrivate(page) == 2; | |
274 | } | |
275 | ||
276 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
277 | { | |
930d9152 | 278 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
279 | return 1; |
280 | if (!bdi_write_congested(bdi)) | |
281 | return 1; | |
282 | if (bdi == current->backing_dev_info) | |
283 | return 1; | |
284 | return 0; | |
285 | } | |
286 | ||
287 | /* | |
288 | * We detected a synchronous write error writing a page out. Probably | |
289 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
290 | * fsync(), msync() or close(). | |
291 | * | |
292 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
293 | * prevents it from being freed up. But we have a ref on the page and once | |
294 | * that page is locked, the mapping is pinned. | |
295 | * | |
296 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
297 | * __GFP_FS. | |
298 | */ | |
299 | static void handle_write_error(struct address_space *mapping, | |
300 | struct page *page, int error) | |
301 | { | |
302 | lock_page(page); | |
3e9f45bd GC |
303 | if (page_mapping(page) == mapping) |
304 | mapping_set_error(mapping, error); | |
1da177e4 LT |
305 | unlock_page(page); |
306 | } | |
307 | ||
c661b078 AW |
308 | /* Request for sync pageout. */ |
309 | enum pageout_io { | |
310 | PAGEOUT_IO_ASYNC, | |
311 | PAGEOUT_IO_SYNC, | |
312 | }; | |
313 | ||
04e62a29 CL |
314 | /* possible outcome of pageout() */ |
315 | typedef enum { | |
316 | /* failed to write page out, page is locked */ | |
317 | PAGE_KEEP, | |
318 | /* move page to the active list, page is locked */ | |
319 | PAGE_ACTIVATE, | |
320 | /* page has been sent to the disk successfully, page is unlocked */ | |
321 | PAGE_SUCCESS, | |
322 | /* page is clean and locked */ | |
323 | PAGE_CLEAN, | |
324 | } pageout_t; | |
325 | ||
1da177e4 | 326 | /* |
1742f19f AM |
327 | * pageout is called by shrink_page_list() for each dirty page. |
328 | * Calls ->writepage(). | |
1da177e4 | 329 | */ |
c661b078 AW |
330 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
331 | enum pageout_io sync_writeback) | |
1da177e4 LT |
332 | { |
333 | /* | |
334 | * If the page is dirty, only perform writeback if that write | |
335 | * will be non-blocking. To prevent this allocation from being | |
336 | * stalled by pagecache activity. But note that there may be | |
337 | * stalls if we need to run get_block(). We could test | |
338 | * PagePrivate for that. | |
339 | * | |
340 | * If this process is currently in generic_file_write() against | |
341 | * this page's queue, we can perform writeback even if that | |
342 | * will block. | |
343 | * | |
344 | * If the page is swapcache, write it back even if that would | |
345 | * block, for some throttling. This happens by accident, because | |
346 | * swap_backing_dev_info is bust: it doesn't reflect the | |
347 | * congestion state of the swapdevs. Easy to fix, if needed. | |
348 | * See swapfile.c:page_queue_congested(). | |
349 | */ | |
350 | if (!is_page_cache_freeable(page)) | |
351 | return PAGE_KEEP; | |
352 | if (!mapping) { | |
353 | /* | |
354 | * Some data journaling orphaned pages can have | |
355 | * page->mapping == NULL while being dirty with clean buffers. | |
356 | */ | |
323aca6c | 357 | if (PagePrivate(page)) { |
1da177e4 LT |
358 | if (try_to_free_buffers(page)) { |
359 | ClearPageDirty(page); | |
d40cee24 | 360 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
361 | return PAGE_CLEAN; |
362 | } | |
363 | } | |
364 | return PAGE_KEEP; | |
365 | } | |
366 | if (mapping->a_ops->writepage == NULL) | |
367 | return PAGE_ACTIVATE; | |
368 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
369 | return PAGE_KEEP; | |
370 | ||
371 | if (clear_page_dirty_for_io(page)) { | |
372 | int res; | |
373 | struct writeback_control wbc = { | |
374 | .sync_mode = WB_SYNC_NONE, | |
375 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
376 | .range_start = 0, |
377 | .range_end = LLONG_MAX, | |
1da177e4 LT |
378 | .nonblocking = 1, |
379 | .for_reclaim = 1, | |
380 | }; | |
381 | ||
382 | SetPageReclaim(page); | |
383 | res = mapping->a_ops->writepage(page, &wbc); | |
384 | if (res < 0) | |
385 | handle_write_error(mapping, page, res); | |
994fc28c | 386 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
387 | ClearPageReclaim(page); |
388 | return PAGE_ACTIVATE; | |
389 | } | |
c661b078 AW |
390 | |
391 | /* | |
392 | * Wait on writeback if requested to. This happens when | |
393 | * direct reclaiming a large contiguous area and the | |
394 | * first attempt to free a range of pages fails. | |
395 | */ | |
396 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
397 | wait_on_page_writeback(page); | |
398 | ||
1da177e4 LT |
399 | if (!PageWriteback(page)) { |
400 | /* synchronous write or broken a_ops? */ | |
401 | ClearPageReclaim(page); | |
402 | } | |
e129b5c2 | 403 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
404 | return PAGE_SUCCESS; |
405 | } | |
406 | ||
407 | return PAGE_CLEAN; | |
408 | } | |
409 | ||
a649fd92 | 410 | /* |
e286781d NP |
411 | * Same as remove_mapping, but if the page is removed from the mapping, it |
412 | * gets returned with a refcount of 0. | |
a649fd92 | 413 | */ |
e286781d | 414 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 415 | { |
28e4d965 NP |
416 | BUG_ON(!PageLocked(page)); |
417 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 418 | |
19fd6231 | 419 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 420 | /* |
0fd0e6b0 NP |
421 | * The non racy check for a busy page. |
422 | * | |
423 | * Must be careful with the order of the tests. When someone has | |
424 | * a ref to the page, it may be possible that they dirty it then | |
425 | * drop the reference. So if PageDirty is tested before page_count | |
426 | * here, then the following race may occur: | |
427 | * | |
428 | * get_user_pages(&page); | |
429 | * [user mapping goes away] | |
430 | * write_to(page); | |
431 | * !PageDirty(page) [good] | |
432 | * SetPageDirty(page); | |
433 | * put_page(page); | |
434 | * !page_count(page) [good, discard it] | |
435 | * | |
436 | * [oops, our write_to data is lost] | |
437 | * | |
438 | * Reversing the order of the tests ensures such a situation cannot | |
439 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
440 | * load is not satisfied before that of page->_count. | |
441 | * | |
442 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
443 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 444 | */ |
e286781d | 445 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 446 | goto cannot_free; |
e286781d NP |
447 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
448 | if (unlikely(PageDirty(page))) { | |
449 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 450 | goto cannot_free; |
e286781d | 451 | } |
49d2e9cc CL |
452 | |
453 | if (PageSwapCache(page)) { | |
454 | swp_entry_t swap = { .val = page_private(page) }; | |
455 | __delete_from_swap_cache(page); | |
19fd6231 | 456 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc | 457 | swap_free(swap); |
e286781d NP |
458 | } else { |
459 | __remove_from_page_cache(page); | |
19fd6231 | 460 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
461 | } |
462 | ||
49d2e9cc CL |
463 | return 1; |
464 | ||
465 | cannot_free: | |
19fd6231 | 466 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
467 | return 0; |
468 | } | |
469 | ||
e286781d NP |
470 | /* |
471 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
472 | * someone else has a ref on the page, abort and return 0. If it was | |
473 | * successfully detached, return 1. Assumes the caller has a single ref on | |
474 | * this page. | |
475 | */ | |
476 | int remove_mapping(struct address_space *mapping, struct page *page) | |
477 | { | |
478 | if (__remove_mapping(mapping, page)) { | |
479 | /* | |
480 | * Unfreezing the refcount with 1 rather than 2 effectively | |
481 | * drops the pagecache ref for us without requiring another | |
482 | * atomic operation. | |
483 | */ | |
484 | page_unfreeze_refs(page, 1); | |
485 | return 1; | |
486 | } | |
487 | return 0; | |
488 | } | |
489 | ||
894bc310 LS |
490 | /** |
491 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
492 | * @page: page to be put back to appropriate lru list | |
493 | * | |
494 | * Add previously isolated @page to appropriate LRU list. | |
495 | * Page may still be unevictable for other reasons. | |
496 | * | |
497 | * lru_lock must not be held, interrupts must be enabled. | |
498 | */ | |
499 | #ifdef CONFIG_UNEVICTABLE_LRU | |
500 | void putback_lru_page(struct page *page) | |
501 | { | |
502 | int lru; | |
503 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 504 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
505 | |
506 | VM_BUG_ON(PageLRU(page)); | |
507 | ||
508 | redo: | |
509 | ClearPageUnevictable(page); | |
510 | ||
511 | if (page_evictable(page, NULL)) { | |
512 | /* | |
513 | * For evictable pages, we can use the cache. | |
514 | * In event of a race, worst case is we end up with an | |
515 | * unevictable page on [in]active list. | |
516 | * We know how to handle that. | |
517 | */ | |
518 | lru = active + page_is_file_cache(page); | |
519 | lru_cache_add_lru(page, lru); | |
520 | } else { | |
521 | /* | |
522 | * Put unevictable pages directly on zone's unevictable | |
523 | * list. | |
524 | */ | |
525 | lru = LRU_UNEVICTABLE; | |
526 | add_page_to_unevictable_list(page); | |
527 | } | |
894bc310 LS |
528 | |
529 | /* | |
530 | * page's status can change while we move it among lru. If an evictable | |
531 | * page is on unevictable list, it never be freed. To avoid that, | |
532 | * check after we added it to the list, again. | |
533 | */ | |
534 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
535 | if (!isolate_lru_page(page)) { | |
536 | put_page(page); | |
537 | goto redo; | |
538 | } | |
539 | /* This means someone else dropped this page from LRU | |
540 | * So, it will be freed or putback to LRU again. There is | |
541 | * nothing to do here. | |
542 | */ | |
543 | } | |
544 | ||
bbfd28ee LS |
545 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
546 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
547 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
548 | count_vm_event(UNEVICTABLE_PGCULLED); | |
549 | ||
894bc310 LS |
550 | put_page(page); /* drop ref from isolate */ |
551 | } | |
552 | ||
553 | #else /* CONFIG_UNEVICTABLE_LRU */ | |
554 | ||
555 | void putback_lru_page(struct page *page) | |
556 | { | |
557 | int lru; | |
558 | VM_BUG_ON(PageLRU(page)); | |
559 | ||
560 | lru = !!TestClearPageActive(page) + page_is_file_cache(page); | |
561 | lru_cache_add_lru(page, lru); | |
894bc310 LS |
562 | put_page(page); |
563 | } | |
564 | #endif /* CONFIG_UNEVICTABLE_LRU */ | |
565 | ||
566 | ||
1da177e4 | 567 | /* |
1742f19f | 568 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 569 | */ |
1742f19f | 570 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
571 | struct scan_control *sc, |
572 | enum pageout_io sync_writeback) | |
1da177e4 LT |
573 | { |
574 | LIST_HEAD(ret_pages); | |
575 | struct pagevec freed_pvec; | |
576 | int pgactivate = 0; | |
05ff5137 | 577 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
578 | |
579 | cond_resched(); | |
580 | ||
581 | pagevec_init(&freed_pvec, 1); | |
582 | while (!list_empty(page_list)) { | |
583 | struct address_space *mapping; | |
584 | struct page *page; | |
585 | int may_enter_fs; | |
586 | int referenced; | |
587 | ||
588 | cond_resched(); | |
589 | ||
590 | page = lru_to_page(page_list); | |
591 | list_del(&page->lru); | |
592 | ||
529ae9aa | 593 | if (!trylock_page(page)) |
1da177e4 LT |
594 | goto keep; |
595 | ||
725d704e | 596 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
597 | |
598 | sc->nr_scanned++; | |
80e43426 | 599 | |
b291f000 NP |
600 | if (unlikely(!page_evictable(page, NULL))) |
601 | goto cull_mlocked; | |
894bc310 | 602 | |
80e43426 CL |
603 | if (!sc->may_swap && page_mapped(page)) |
604 | goto keep_locked; | |
605 | ||
1da177e4 LT |
606 | /* Double the slab pressure for mapped and swapcache pages */ |
607 | if (page_mapped(page) || PageSwapCache(page)) | |
608 | sc->nr_scanned++; | |
609 | ||
c661b078 AW |
610 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
611 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
612 | ||
613 | if (PageWriteback(page)) { | |
614 | /* | |
615 | * Synchronous reclaim is performed in two passes, | |
616 | * first an asynchronous pass over the list to | |
617 | * start parallel writeback, and a second synchronous | |
618 | * pass to wait for the IO to complete. Wait here | |
619 | * for any page for which writeback has already | |
620 | * started. | |
621 | */ | |
622 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
623 | wait_on_page_writeback(page); | |
4dd4b920 | 624 | else |
c661b078 AW |
625 | goto keep_locked; |
626 | } | |
1da177e4 | 627 | |
bed7161a | 628 | referenced = page_referenced(page, 1, sc->mem_cgroup); |
1da177e4 | 629 | /* In active use or really unfreeable? Activate it. */ |
5ad333eb AW |
630 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && |
631 | referenced && page_mapping_inuse(page)) | |
1da177e4 LT |
632 | goto activate_locked; |
633 | ||
1da177e4 LT |
634 | /* |
635 | * Anonymous process memory has backing store? | |
636 | * Try to allocate it some swap space here. | |
637 | */ | |
b291f000 | 638 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
639 | if (!(sc->gfp_mask & __GFP_IO)) |
640 | goto keep_locked; | |
ac47b003 | 641 | if (!add_to_swap(page)) |
1da177e4 | 642 | goto activate_locked; |
63eb6b93 | 643 | may_enter_fs = 1; |
b291f000 | 644 | } |
1da177e4 LT |
645 | |
646 | mapping = page_mapping(page); | |
1da177e4 LT |
647 | |
648 | /* | |
649 | * The page is mapped into the page tables of one or more | |
650 | * processes. Try to unmap it here. | |
651 | */ | |
652 | if (page_mapped(page) && mapping) { | |
a48d07af | 653 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
654 | case SWAP_FAIL: |
655 | goto activate_locked; | |
656 | case SWAP_AGAIN: | |
657 | goto keep_locked; | |
b291f000 NP |
658 | case SWAP_MLOCK: |
659 | goto cull_mlocked; | |
1da177e4 LT |
660 | case SWAP_SUCCESS: |
661 | ; /* try to free the page below */ | |
662 | } | |
663 | } | |
664 | ||
665 | if (PageDirty(page)) { | |
5ad333eb | 666 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) |
1da177e4 | 667 | goto keep_locked; |
4dd4b920 | 668 | if (!may_enter_fs) |
1da177e4 | 669 | goto keep_locked; |
52a8363e | 670 | if (!sc->may_writepage) |
1da177e4 LT |
671 | goto keep_locked; |
672 | ||
673 | /* Page is dirty, try to write it out here */ | |
c661b078 | 674 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
675 | case PAGE_KEEP: |
676 | goto keep_locked; | |
677 | case PAGE_ACTIVATE: | |
678 | goto activate_locked; | |
679 | case PAGE_SUCCESS: | |
4dd4b920 | 680 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
681 | goto keep; |
682 | /* | |
683 | * A synchronous write - probably a ramdisk. Go | |
684 | * ahead and try to reclaim the page. | |
685 | */ | |
529ae9aa | 686 | if (!trylock_page(page)) |
1da177e4 LT |
687 | goto keep; |
688 | if (PageDirty(page) || PageWriteback(page)) | |
689 | goto keep_locked; | |
690 | mapping = page_mapping(page); | |
691 | case PAGE_CLEAN: | |
692 | ; /* try to free the page below */ | |
693 | } | |
694 | } | |
695 | ||
696 | /* | |
697 | * If the page has buffers, try to free the buffer mappings | |
698 | * associated with this page. If we succeed we try to free | |
699 | * the page as well. | |
700 | * | |
701 | * We do this even if the page is PageDirty(). | |
702 | * try_to_release_page() does not perform I/O, but it is | |
703 | * possible for a page to have PageDirty set, but it is actually | |
704 | * clean (all its buffers are clean). This happens if the | |
705 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 706 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
707 | * try_to_release_page() will discover that cleanness and will |
708 | * drop the buffers and mark the page clean - it can be freed. | |
709 | * | |
710 | * Rarely, pages can have buffers and no ->mapping. These are | |
711 | * the pages which were not successfully invalidated in | |
712 | * truncate_complete_page(). We try to drop those buffers here | |
713 | * and if that worked, and the page is no longer mapped into | |
714 | * process address space (page_count == 1) it can be freed. | |
715 | * Otherwise, leave the page on the LRU so it is swappable. | |
716 | */ | |
717 | if (PagePrivate(page)) { | |
718 | if (!try_to_release_page(page, sc->gfp_mask)) | |
719 | goto activate_locked; | |
e286781d NP |
720 | if (!mapping && page_count(page) == 1) { |
721 | unlock_page(page); | |
722 | if (put_page_testzero(page)) | |
723 | goto free_it; | |
724 | else { | |
725 | /* | |
726 | * rare race with speculative reference. | |
727 | * the speculative reference will free | |
728 | * this page shortly, so we may | |
729 | * increment nr_reclaimed here (and | |
730 | * leave it off the LRU). | |
731 | */ | |
732 | nr_reclaimed++; | |
733 | continue; | |
734 | } | |
735 | } | |
1da177e4 LT |
736 | } |
737 | ||
e286781d | 738 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 739 | goto keep_locked; |
1da177e4 | 740 | |
a978d6f5 NP |
741 | /* |
742 | * At this point, we have no other references and there is | |
743 | * no way to pick any more up (removed from LRU, removed | |
744 | * from pagecache). Can use non-atomic bitops now (and | |
745 | * we obviously don't have to worry about waking up a process | |
746 | * waiting on the page lock, because there are no references. | |
747 | */ | |
748 | __clear_page_locked(page); | |
e286781d | 749 | free_it: |
05ff5137 | 750 | nr_reclaimed++; |
e286781d NP |
751 | if (!pagevec_add(&freed_pvec, page)) { |
752 | __pagevec_free(&freed_pvec); | |
753 | pagevec_reinit(&freed_pvec); | |
754 | } | |
1da177e4 LT |
755 | continue; |
756 | ||
b291f000 | 757 | cull_mlocked: |
63d6c5ad HD |
758 | if (PageSwapCache(page)) |
759 | try_to_free_swap(page); | |
b291f000 NP |
760 | unlock_page(page); |
761 | putback_lru_page(page); | |
762 | continue; | |
763 | ||
1da177e4 | 764 | activate_locked: |
68a22394 RR |
765 | /* Not a candidate for swapping, so reclaim swap space. */ |
766 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 767 | try_to_free_swap(page); |
894bc310 | 768 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
769 | SetPageActive(page); |
770 | pgactivate++; | |
771 | keep_locked: | |
772 | unlock_page(page); | |
773 | keep: | |
774 | list_add(&page->lru, &ret_pages); | |
b291f000 | 775 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 LT |
776 | } |
777 | list_splice(&ret_pages, page_list); | |
778 | if (pagevec_count(&freed_pvec)) | |
e286781d | 779 | __pagevec_free(&freed_pvec); |
f8891e5e | 780 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 781 | return nr_reclaimed; |
1da177e4 LT |
782 | } |
783 | ||
5ad333eb AW |
784 | /* LRU Isolation modes. */ |
785 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ | |
786 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ | |
787 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ | |
788 | ||
789 | /* | |
790 | * Attempt to remove the specified page from its LRU. Only take this page | |
791 | * if it is of the appropriate PageActive status. Pages which are being | |
792 | * freed elsewhere are also ignored. | |
793 | * | |
794 | * page: page to consider | |
795 | * mode: one of the LRU isolation modes defined above | |
796 | * | |
797 | * returns 0 on success, -ve errno on failure. | |
798 | */ | |
4f98a2fe | 799 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
800 | { |
801 | int ret = -EINVAL; | |
802 | ||
803 | /* Only take pages on the LRU. */ | |
804 | if (!PageLRU(page)) | |
805 | return ret; | |
806 | ||
807 | /* | |
808 | * When checking the active state, we need to be sure we are | |
809 | * dealing with comparible boolean values. Take the logical not | |
810 | * of each. | |
811 | */ | |
812 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
813 | return ret; | |
814 | ||
4f98a2fe RR |
815 | if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file)) |
816 | return ret; | |
817 | ||
894bc310 LS |
818 | /* |
819 | * When this function is being called for lumpy reclaim, we | |
820 | * initially look into all LRU pages, active, inactive and | |
821 | * unevictable; only give shrink_page_list evictable pages. | |
822 | */ | |
823 | if (PageUnevictable(page)) | |
824 | return ret; | |
825 | ||
5ad333eb | 826 | ret = -EBUSY; |
08e552c6 | 827 | |
5ad333eb AW |
828 | if (likely(get_page_unless_zero(page))) { |
829 | /* | |
830 | * Be careful not to clear PageLRU until after we're | |
831 | * sure the page is not being freed elsewhere -- the | |
832 | * page release code relies on it. | |
833 | */ | |
834 | ClearPageLRU(page); | |
835 | ret = 0; | |
08e552c6 | 836 | mem_cgroup_del_lru(page); |
5ad333eb AW |
837 | } |
838 | ||
839 | return ret; | |
840 | } | |
841 | ||
1da177e4 LT |
842 | /* |
843 | * zone->lru_lock is heavily contended. Some of the functions that | |
844 | * shrink the lists perform better by taking out a batch of pages | |
845 | * and working on them outside the LRU lock. | |
846 | * | |
847 | * For pagecache intensive workloads, this function is the hottest | |
848 | * spot in the kernel (apart from copy_*_user functions). | |
849 | * | |
850 | * Appropriate locks must be held before calling this function. | |
851 | * | |
852 | * @nr_to_scan: The number of pages to look through on the list. | |
853 | * @src: The LRU list to pull pages off. | |
854 | * @dst: The temp list to put pages on to. | |
855 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
856 | * @order: The caller's attempted allocation order |
857 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 858 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
859 | * |
860 | * returns how many pages were moved onto *@dst. | |
861 | */ | |
69e05944 AM |
862 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
863 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 864 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 865 | { |
69e05944 | 866 | unsigned long nr_taken = 0; |
c9b02d97 | 867 | unsigned long scan; |
1da177e4 | 868 | |
c9b02d97 | 869 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
870 | struct page *page; |
871 | unsigned long pfn; | |
872 | unsigned long end_pfn; | |
873 | unsigned long page_pfn; | |
874 | int zone_id; | |
875 | ||
1da177e4 LT |
876 | page = lru_to_page(src); |
877 | prefetchw_prev_lru_page(page, src, flags); | |
878 | ||
725d704e | 879 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 880 | |
4f98a2fe | 881 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
882 | case 0: |
883 | list_move(&page->lru, dst); | |
7c8ee9a8 | 884 | nr_taken++; |
5ad333eb AW |
885 | break; |
886 | ||
887 | case -EBUSY: | |
888 | /* else it is being freed elsewhere */ | |
889 | list_move(&page->lru, src); | |
890 | continue; | |
46453a6e | 891 | |
5ad333eb AW |
892 | default: |
893 | BUG(); | |
894 | } | |
895 | ||
896 | if (!order) | |
897 | continue; | |
898 | ||
899 | /* | |
900 | * Attempt to take all pages in the order aligned region | |
901 | * surrounding the tag page. Only take those pages of | |
902 | * the same active state as that tag page. We may safely | |
903 | * round the target page pfn down to the requested order | |
904 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
905 | * where that page is in a different zone we will detect | |
906 | * it from its zone id and abort this block scan. | |
907 | */ | |
908 | zone_id = page_zone_id(page); | |
909 | page_pfn = page_to_pfn(page); | |
910 | pfn = page_pfn & ~((1 << order) - 1); | |
911 | end_pfn = pfn + (1 << order); | |
912 | for (; pfn < end_pfn; pfn++) { | |
913 | struct page *cursor_page; | |
914 | ||
915 | /* The target page is in the block, ignore it. */ | |
916 | if (unlikely(pfn == page_pfn)) | |
917 | continue; | |
918 | ||
919 | /* Avoid holes within the zone. */ | |
920 | if (unlikely(!pfn_valid_within(pfn))) | |
921 | break; | |
922 | ||
923 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 924 | |
5ad333eb AW |
925 | /* Check that we have not crossed a zone boundary. */ |
926 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
927 | continue; | |
4f98a2fe | 928 | switch (__isolate_lru_page(cursor_page, mode, file)) { |
5ad333eb AW |
929 | case 0: |
930 | list_move(&cursor_page->lru, dst); | |
931 | nr_taken++; | |
932 | scan++; | |
933 | break; | |
934 | ||
935 | case -EBUSY: | |
936 | /* else it is being freed elsewhere */ | |
937 | list_move(&cursor_page->lru, src); | |
938 | default: | |
894bc310 | 939 | break; /* ! on LRU or wrong list */ |
5ad333eb AW |
940 | } |
941 | } | |
1da177e4 LT |
942 | } |
943 | ||
944 | *scanned = scan; | |
945 | return nr_taken; | |
946 | } | |
947 | ||
66e1707b BS |
948 | static unsigned long isolate_pages_global(unsigned long nr, |
949 | struct list_head *dst, | |
950 | unsigned long *scanned, int order, | |
951 | int mode, struct zone *z, | |
952 | struct mem_cgroup *mem_cont, | |
4f98a2fe | 953 | int active, int file) |
66e1707b | 954 | { |
4f98a2fe | 955 | int lru = LRU_BASE; |
66e1707b | 956 | if (active) |
4f98a2fe RR |
957 | lru += LRU_ACTIVE; |
958 | if (file) | |
959 | lru += LRU_FILE; | |
960 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
961 | mode, !!file); | |
66e1707b BS |
962 | } |
963 | ||
5ad333eb AW |
964 | /* |
965 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
966 | * any active bits from the pages in the list. | |
967 | */ | |
4f98a2fe RR |
968 | static unsigned long clear_active_flags(struct list_head *page_list, |
969 | unsigned int *count) | |
5ad333eb AW |
970 | { |
971 | int nr_active = 0; | |
4f98a2fe | 972 | int lru; |
5ad333eb AW |
973 | struct page *page; |
974 | ||
4f98a2fe RR |
975 | list_for_each_entry(page, page_list, lru) { |
976 | lru = page_is_file_cache(page); | |
5ad333eb | 977 | if (PageActive(page)) { |
4f98a2fe | 978 | lru += LRU_ACTIVE; |
5ad333eb AW |
979 | ClearPageActive(page); |
980 | nr_active++; | |
981 | } | |
4f98a2fe RR |
982 | count[lru]++; |
983 | } | |
5ad333eb AW |
984 | |
985 | return nr_active; | |
986 | } | |
987 | ||
62695a84 NP |
988 | /** |
989 | * isolate_lru_page - tries to isolate a page from its LRU list | |
990 | * @page: page to isolate from its LRU list | |
991 | * | |
992 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
993 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
994 | * | |
995 | * Returns 0 if the page was removed from an LRU list. | |
996 | * Returns -EBUSY if the page was not on an LRU list. | |
997 | * | |
998 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
999 | * the active list, it will have PageActive set. If it was found on |
1000 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1001 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1002 | * |
1003 | * The vmstat statistic corresponding to the list on which the page was | |
1004 | * found will be decremented. | |
1005 | * | |
1006 | * Restrictions: | |
1007 | * (1) Must be called with an elevated refcount on the page. This is a | |
1008 | * fundamentnal difference from isolate_lru_pages (which is called | |
1009 | * without a stable reference). | |
1010 | * (2) the lru_lock must not be held. | |
1011 | * (3) interrupts must be enabled. | |
1012 | */ | |
1013 | int isolate_lru_page(struct page *page) | |
1014 | { | |
1015 | int ret = -EBUSY; | |
1016 | ||
1017 | if (PageLRU(page)) { | |
1018 | struct zone *zone = page_zone(page); | |
1019 | ||
1020 | spin_lock_irq(&zone->lru_lock); | |
1021 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1022 | int lru = page_lru(page); |
62695a84 NP |
1023 | ret = 0; |
1024 | ClearPageLRU(page); | |
4f98a2fe | 1025 | |
4f98a2fe | 1026 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1027 | } |
1028 | spin_unlock_irq(&zone->lru_lock); | |
1029 | } | |
1030 | return ret; | |
1031 | } | |
1032 | ||
1da177e4 | 1033 | /* |
1742f19f AM |
1034 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1035 | * of reclaimed pages | |
1da177e4 | 1036 | */ |
1742f19f | 1037 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
33c120ed RR |
1038 | struct zone *zone, struct scan_control *sc, |
1039 | int priority, int file) | |
1da177e4 LT |
1040 | { |
1041 | LIST_HEAD(page_list); | |
1042 | struct pagevec pvec; | |
69e05944 | 1043 | unsigned long nr_scanned = 0; |
05ff5137 | 1044 | unsigned long nr_reclaimed = 0; |
6e901571 | 1045 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1da177e4 LT |
1046 | |
1047 | pagevec_init(&pvec, 1); | |
1048 | ||
1049 | lru_add_drain(); | |
1050 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 1051 | do { |
1da177e4 | 1052 | struct page *page; |
69e05944 AM |
1053 | unsigned long nr_taken; |
1054 | unsigned long nr_scan; | |
1055 | unsigned long nr_freed; | |
5ad333eb | 1056 | unsigned long nr_active; |
4f98a2fe | 1057 | unsigned int count[NR_LRU_LISTS] = { 0, }; |
33c120ed RR |
1058 | int mode = ISOLATE_INACTIVE; |
1059 | ||
1060 | /* | |
1061 | * If we need a large contiguous chunk of memory, or have | |
1062 | * trouble getting a small set of contiguous pages, we | |
1063 | * will reclaim both active and inactive pages. | |
1064 | * | |
1065 | * We use the same threshold as pageout congestion_wait below. | |
1066 | */ | |
1067 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1068 | mode = ISOLATE_BOTH; | |
1069 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1070 | mode = ISOLATE_BOTH; | |
1da177e4 | 1071 | |
66e1707b | 1072 | nr_taken = sc->isolate_pages(sc->swap_cluster_max, |
4f98a2fe RR |
1073 | &page_list, &nr_scan, sc->order, mode, |
1074 | zone, sc->mem_cgroup, 0, file); | |
1075 | nr_active = clear_active_flags(&page_list, count); | |
e9187bdc | 1076 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb | 1077 | |
4f98a2fe RR |
1078 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1079 | -count[LRU_ACTIVE_FILE]); | |
1080 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1081 | -count[LRU_INACTIVE_FILE]); | |
1082 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1083 | -count[LRU_ACTIVE_ANON]); | |
1084 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1085 | -count[LRU_INACTIVE_ANON]); | |
1086 | ||
1087 | if (scan_global_lru(sc)) { | |
1cfb419b | 1088 | zone->pages_scanned += nr_scan; |
6e901571 KM |
1089 | reclaim_stat->recent_scanned[0] += |
1090 | count[LRU_INACTIVE_ANON]; | |
1091 | reclaim_stat->recent_scanned[0] += | |
1092 | count[LRU_ACTIVE_ANON]; | |
1093 | reclaim_stat->recent_scanned[1] += | |
1094 | count[LRU_INACTIVE_FILE]; | |
1095 | reclaim_stat->recent_scanned[1] += | |
1096 | count[LRU_ACTIVE_FILE]; | |
4f98a2fe | 1097 | } |
1da177e4 LT |
1098 | spin_unlock_irq(&zone->lru_lock); |
1099 | ||
69e05944 | 1100 | nr_scanned += nr_scan; |
c661b078 AW |
1101 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
1102 | ||
1103 | /* | |
1104 | * If we are direct reclaiming for contiguous pages and we do | |
1105 | * not reclaim everything in the list, try again and wait | |
1106 | * for IO to complete. This will stall high-order allocations | |
1107 | * but that should be acceptable to the caller | |
1108 | */ | |
1109 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
1110 | sc->order > PAGE_ALLOC_COSTLY_ORDER) { | |
1111 | congestion_wait(WRITE, HZ/10); | |
1112 | ||
1113 | /* | |
1114 | * The attempt at page out may have made some | |
1115 | * of the pages active, mark them inactive again. | |
1116 | */ | |
4f98a2fe | 1117 | nr_active = clear_active_flags(&page_list, count); |
c661b078 AW |
1118 | count_vm_events(PGDEACTIVATE, nr_active); |
1119 | ||
1120 | nr_freed += shrink_page_list(&page_list, sc, | |
1121 | PAGEOUT_IO_SYNC); | |
1122 | } | |
1123 | ||
05ff5137 | 1124 | nr_reclaimed += nr_freed; |
a74609fa NP |
1125 | local_irq_disable(); |
1126 | if (current_is_kswapd()) { | |
f8891e5e CL |
1127 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
1128 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
1cfb419b | 1129 | } else if (scan_global_lru(sc)) |
f8891e5e | 1130 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
1cfb419b | 1131 | |
918d3f90 | 1132 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa | 1133 | |
fb8d14e1 WF |
1134 | if (nr_taken == 0) |
1135 | goto done; | |
1136 | ||
a74609fa | 1137 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
1138 | /* |
1139 | * Put back any unfreeable pages. | |
1140 | */ | |
1141 | while (!list_empty(&page_list)) { | |
894bc310 | 1142 | int lru; |
1da177e4 | 1143 | page = lru_to_page(&page_list); |
725d704e | 1144 | VM_BUG_ON(PageLRU(page)); |
1da177e4 | 1145 | list_del(&page->lru); |
894bc310 LS |
1146 | if (unlikely(!page_evictable(page, NULL))) { |
1147 | spin_unlock_irq(&zone->lru_lock); | |
1148 | putback_lru_page(page); | |
1149 | spin_lock_irq(&zone->lru_lock); | |
1150 | continue; | |
1151 | } | |
1152 | SetPageLRU(page); | |
1153 | lru = page_lru(page); | |
1154 | add_page_to_lru_list(zone, page, lru); | |
4f98a2fe RR |
1155 | if (PageActive(page) && scan_global_lru(sc)) { |
1156 | int file = !!page_is_file_cache(page); | |
6e901571 | 1157 | reclaim_stat->recent_rotated[file]++; |
4f98a2fe | 1158 | } |
1da177e4 LT |
1159 | if (!pagevec_add(&pvec, page)) { |
1160 | spin_unlock_irq(&zone->lru_lock); | |
1161 | __pagevec_release(&pvec); | |
1162 | spin_lock_irq(&zone->lru_lock); | |
1163 | } | |
1164 | } | |
69e05944 | 1165 | } while (nr_scanned < max_scan); |
fb8d14e1 | 1166 | spin_unlock(&zone->lru_lock); |
1da177e4 | 1167 | done: |
fb8d14e1 | 1168 | local_irq_enable(); |
1da177e4 | 1169 | pagevec_release(&pvec); |
05ff5137 | 1170 | return nr_reclaimed; |
1da177e4 LT |
1171 | } |
1172 | ||
3bb1a852 MB |
1173 | /* |
1174 | * We are about to scan this zone at a certain priority level. If that priority | |
1175 | * level is smaller (ie: more urgent) than the previous priority, then note | |
1176 | * that priority level within the zone. This is done so that when the next | |
1177 | * process comes in to scan this zone, it will immediately start out at this | |
1178 | * priority level rather than having to build up its own scanning priority. | |
1179 | * Here, this priority affects only the reclaim-mapped threshold. | |
1180 | */ | |
1181 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
1182 | { | |
1183 | if (priority < zone->prev_priority) | |
1184 | zone->prev_priority = priority; | |
1185 | } | |
1186 | ||
1da177e4 LT |
1187 | /* |
1188 | * This moves pages from the active list to the inactive list. | |
1189 | * | |
1190 | * We move them the other way if the page is referenced by one or more | |
1191 | * processes, from rmap. | |
1192 | * | |
1193 | * If the pages are mostly unmapped, the processing is fast and it is | |
1194 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1195 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1196 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1197 | * this, so instead we remove the pages from the LRU while processing them. | |
1198 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1199 | * nobody will play with that bit on a non-LRU page. | |
1200 | * | |
1201 | * The downside is that we have to touch page->_count against each page. | |
1202 | * But we had to alter page->flags anyway. | |
1203 | */ | |
1cfb419b KH |
1204 | |
1205 | ||
1742f19f | 1206 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1207 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1208 | { |
69e05944 | 1209 | unsigned long pgmoved; |
1da177e4 | 1210 | int pgdeactivate = 0; |
69e05944 | 1211 | unsigned long pgscanned; |
1da177e4 | 1212 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
b69408e8 | 1213 | LIST_HEAD(l_inactive); |
1da177e4 LT |
1214 | struct page *page; |
1215 | struct pagevec pvec; | |
4f98a2fe | 1216 | enum lru_list lru; |
6e901571 | 1217 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1da177e4 LT |
1218 | |
1219 | lru_add_drain(); | |
1220 | spin_lock_irq(&zone->lru_lock); | |
66e1707b BS |
1221 | pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, |
1222 | ISOLATE_ACTIVE, zone, | |
4f98a2fe | 1223 | sc->mem_cgroup, 1, file); |
1cfb419b KH |
1224 | /* |
1225 | * zone->pages_scanned is used for detect zone's oom | |
1226 | * mem_cgroup remembers nr_scan by itself. | |
1227 | */ | |
4f98a2fe | 1228 | if (scan_global_lru(sc)) { |
1cfb419b | 1229 | zone->pages_scanned += pgscanned; |
6e901571 | 1230 | reclaim_stat->recent_scanned[!!file] += pgmoved; |
4f98a2fe | 1231 | } |
1cfb419b | 1232 | |
4f98a2fe RR |
1233 | if (file) |
1234 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved); | |
1235 | else | |
1236 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved); | |
1da177e4 LT |
1237 | spin_unlock_irq(&zone->lru_lock); |
1238 | ||
556adecb | 1239 | pgmoved = 0; |
1da177e4 LT |
1240 | while (!list_empty(&l_hold)) { |
1241 | cond_resched(); | |
1242 | page = lru_to_page(&l_hold); | |
1243 | list_del(&page->lru); | |
7e9cd484 | 1244 | |
894bc310 LS |
1245 | if (unlikely(!page_evictable(page, NULL))) { |
1246 | putback_lru_page(page); | |
1247 | continue; | |
1248 | } | |
1249 | ||
7e9cd484 RR |
1250 | /* page_referenced clears PageReferenced */ |
1251 | if (page_mapping_inuse(page) && | |
1252 | page_referenced(page, 0, sc->mem_cgroup)) | |
1253 | pgmoved++; | |
1254 | ||
1da177e4 LT |
1255 | list_add(&page->lru, &l_inactive); |
1256 | } | |
1257 | ||
b555749a AM |
1258 | /* |
1259 | * Move the pages to the [file or anon] inactive list. | |
1260 | */ | |
1261 | pagevec_init(&pvec, 1); | |
1262 | pgmoved = 0; | |
1263 | lru = LRU_BASE + file * LRU_FILE; | |
1264 | ||
2a1dc509 | 1265 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1266 | /* |
7e9cd484 RR |
1267 | * Count referenced pages from currently used mappings as |
1268 | * rotated, even though they are moved to the inactive list. | |
1269 | * This helps balance scan pressure between file and anonymous | |
1270 | * pages in get_scan_ratio. | |
1271 | */ | |
077cbc58 | 1272 | if (scan_global_lru(sc)) |
6e901571 | 1273 | reclaim_stat->recent_rotated[!!file] += pgmoved; |
556adecb | 1274 | |
1da177e4 LT |
1275 | while (!list_empty(&l_inactive)) { |
1276 | page = lru_to_page(&l_inactive); | |
1277 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 1278 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1279 | SetPageLRU(page); |
725d704e | 1280 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
1281 | ClearPageActive(page); |
1282 | ||
4f98a2fe | 1283 | list_move(&page->lru, &zone->lru[lru].list); |
08e552c6 | 1284 | mem_cgroup_add_lru_list(page, lru); |
1da177e4 LT |
1285 | pgmoved++; |
1286 | if (!pagevec_add(&pvec, page)) { | |
4f98a2fe | 1287 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1288 | spin_unlock_irq(&zone->lru_lock); |
1289 | pgdeactivate += pgmoved; | |
1290 | pgmoved = 0; | |
1291 | if (buffer_heads_over_limit) | |
1292 | pagevec_strip(&pvec); | |
1293 | __pagevec_release(&pvec); | |
1294 | spin_lock_irq(&zone->lru_lock); | |
1295 | } | |
1296 | } | |
4f98a2fe | 1297 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1298 | pgdeactivate += pgmoved; |
1299 | if (buffer_heads_over_limit) { | |
1300 | spin_unlock_irq(&zone->lru_lock); | |
1301 | pagevec_strip(&pvec); | |
1302 | spin_lock_irq(&zone->lru_lock); | |
1303 | } | |
f8891e5e CL |
1304 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1305 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
1306 | spin_unlock_irq(&zone->lru_lock); | |
68a22394 RR |
1307 | if (vm_swap_full()) |
1308 | pagevec_swap_free(&pvec); | |
1da177e4 | 1309 | |
a74609fa | 1310 | pagevec_release(&pvec); |
1da177e4 LT |
1311 | } |
1312 | ||
f89eb90e KM |
1313 | /** |
1314 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1315 | * @zone: zone to check | |
1316 | * | |
1317 | * Returns true if the zone does not have enough inactive anon pages, | |
1318 | * meaning some active anon pages need to be deactivated. | |
1319 | */ | |
1320 | static int inactive_anon_is_low(struct zone *zone) | |
1321 | { | |
1322 | unsigned long active, inactive; | |
1323 | ||
1324 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1325 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1326 | ||
1327 | if (inactive * zone->inactive_ratio < active) | |
1328 | return 1; | |
1329 | ||
1330 | return 0; | |
1331 | } | |
1332 | ||
4f98a2fe | 1333 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1334 | struct zone *zone, struct scan_control *sc, int priority) |
1335 | { | |
4f98a2fe RR |
1336 | int file = is_file_lru(lru); |
1337 | ||
556adecb RR |
1338 | if (lru == LRU_ACTIVE_FILE) { |
1339 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
1340 | return 0; | |
1341 | } | |
1342 | ||
1343 | if (lru == LRU_ACTIVE_ANON && | |
1344 | (!scan_global_lru(sc) || inactive_anon_is_low(zone))) { | |
4f98a2fe | 1345 | shrink_active_list(nr_to_scan, zone, sc, priority, file); |
b69408e8 CL |
1346 | return 0; |
1347 | } | |
33c120ed | 1348 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1349 | } |
1350 | ||
1351 | /* | |
1352 | * Determine how aggressively the anon and file LRU lists should be | |
1353 | * scanned. The relative value of each set of LRU lists is determined | |
1354 | * by looking at the fraction of the pages scanned we did rotate back | |
1355 | * onto the active list instead of evict. | |
1356 | * | |
1357 | * percent[0] specifies how much pressure to put on ram/swap backed | |
1358 | * memory, while percent[1] determines pressure on the file LRUs. | |
1359 | */ | |
1360 | static void get_scan_ratio(struct zone *zone, struct scan_control *sc, | |
1361 | unsigned long *percent) | |
1362 | { | |
1363 | unsigned long anon, file, free; | |
1364 | unsigned long anon_prio, file_prio; | |
1365 | unsigned long ap, fp; | |
6e901571 | 1366 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
4f98a2fe | 1367 | |
4f98a2fe RR |
1368 | /* If we have no swap space, do not bother scanning anon pages. */ |
1369 | if (nr_swap_pages <= 0) { | |
1370 | percent[0] = 0; | |
1371 | percent[1] = 100; | |
1372 | return; | |
1373 | } | |
1374 | ||
c9f299d9 KM |
1375 | anon = zone_nr_pages(zone, sc, LRU_ACTIVE_ANON) + |
1376 | zone_nr_pages(zone, sc, LRU_INACTIVE_ANON); | |
1377 | file = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1378 | zone_nr_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1379 | |
eeee9a8c KM |
1380 | if (scan_global_lru(sc)) { |
1381 | free = zone_page_state(zone, NR_FREE_PAGES); | |
1382 | /* If we have very few page cache pages, | |
1383 | force-scan anon pages. */ | |
1384 | if (unlikely(file + free <= zone->pages_high)) { | |
1385 | percent[0] = 100; | |
1386 | percent[1] = 0; | |
1387 | return; | |
1388 | } | |
4f98a2fe RR |
1389 | } |
1390 | ||
1391 | /* | |
1392 | * OK, so we have swap space and a fair amount of page cache | |
1393 | * pages. We use the recently rotated / recently scanned | |
1394 | * ratios to determine how valuable each cache is. | |
1395 | * | |
1396 | * Because workloads change over time (and to avoid overflow) | |
1397 | * we keep these statistics as a floating average, which ends | |
1398 | * up weighing recent references more than old ones. | |
1399 | * | |
1400 | * anon in [0], file in [1] | |
1401 | */ | |
6e901571 | 1402 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
4f98a2fe | 1403 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1404 | reclaim_stat->recent_scanned[0] /= 2; |
1405 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1406 | spin_unlock_irq(&zone->lru_lock); |
1407 | } | |
1408 | ||
6e901571 | 1409 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
4f98a2fe | 1410 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1411 | reclaim_stat->recent_scanned[1] /= 2; |
1412 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1413 | spin_unlock_irq(&zone->lru_lock); |
1414 | } | |
1415 | ||
1416 | /* | |
1417 | * With swappiness at 100, anonymous and file have the same priority. | |
1418 | * This scanning priority is essentially the inverse of IO cost. | |
1419 | */ | |
1420 | anon_prio = sc->swappiness; | |
1421 | file_prio = 200 - sc->swappiness; | |
1422 | ||
1423 | /* | |
00d8089c RR |
1424 | * The amount of pressure on anon vs file pages is inversely |
1425 | * proportional to the fraction of recently scanned pages on | |
1426 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1427 | */ |
6e901571 KM |
1428 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1429 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1430 | |
6e901571 KM |
1431 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1432 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
4f98a2fe RR |
1433 | |
1434 | /* Normalize to percentages */ | |
1435 | percent[0] = 100 * ap / (ap + fp + 1); | |
1436 | percent[1] = 100 - percent[0]; | |
b69408e8 CL |
1437 | } |
1438 | ||
4f98a2fe | 1439 | |
1da177e4 LT |
1440 | /* |
1441 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1442 | */ | |
a79311c1 | 1443 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1444 | struct scan_control *sc) |
1da177e4 | 1445 | { |
b69408e8 | 1446 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1447 | unsigned long nr_to_scan; |
4f98a2fe | 1448 | unsigned long percent[2]; /* anon @ 0; file @ 1 */ |
b69408e8 | 1449 | enum lru_list l; |
01dbe5c9 KM |
1450 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
1451 | unsigned long swap_cluster_max = sc->swap_cluster_max; | |
1da177e4 | 1452 | |
4f98a2fe RR |
1453 | get_scan_ratio(zone, sc, percent); |
1454 | ||
894bc310 | 1455 | for_each_evictable_lru(l) { |
4f98a2fe RR |
1456 | if (scan_global_lru(sc)) { |
1457 | int file = is_file_lru(l); | |
1458 | int scan; | |
e0f79b8f | 1459 | |
4f98a2fe RR |
1460 | scan = zone_page_state(zone, NR_LRU_BASE + l); |
1461 | if (priority) { | |
1462 | scan >>= priority; | |
1463 | scan = (scan * percent[file]) / 100; | |
1464 | } | |
e0f79b8f | 1465 | zone->lru[l].nr_scan += scan; |
b69408e8 | 1466 | nr[l] = zone->lru[l].nr_scan; |
01dbe5c9 | 1467 | if (nr[l] >= swap_cluster_max) |
b69408e8 CL |
1468 | zone->lru[l].nr_scan = 0; |
1469 | else | |
1470 | nr[l] = 0; | |
4f98a2fe RR |
1471 | } else { |
1472 | /* | |
1473 | * This reclaim occurs not because zone memory shortage | |
1474 | * but because memory controller hits its limit. | |
1475 | * Don't modify zone reclaim related data. | |
1476 | */ | |
1477 | nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone, | |
1478 | priority, l); | |
b69408e8 | 1479 | } |
1cfb419b | 1480 | } |
1da177e4 | 1481 | |
556adecb RR |
1482 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1483 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1484 | for_each_evictable_lru(l) { |
b69408e8 | 1485 | if (nr[l]) { |
01dbe5c9 | 1486 | nr_to_scan = min(nr[l], swap_cluster_max); |
b69408e8 | 1487 | nr[l] -= nr_to_scan; |
1da177e4 | 1488 | |
01dbe5c9 KM |
1489 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1490 | zone, sc, priority); | |
b69408e8 | 1491 | } |
1da177e4 | 1492 | } |
a79311c1 RR |
1493 | /* |
1494 | * On large memory systems, scan >> priority can become | |
1495 | * really large. This is fine for the starting priority; | |
1496 | * we want to put equal scanning pressure on each zone. | |
1497 | * However, if the VM has a harder time of freeing pages, | |
1498 | * with multiple processes reclaiming pages, the total | |
1499 | * freeing target can get unreasonably large. | |
1500 | */ | |
01dbe5c9 | 1501 | if (nr_reclaimed > swap_cluster_max && |
a79311c1 RR |
1502 | priority < DEF_PRIORITY && !current_is_kswapd()) |
1503 | break; | |
1da177e4 LT |
1504 | } |
1505 | ||
01dbe5c9 KM |
1506 | sc->nr_reclaimed = nr_reclaimed; |
1507 | ||
556adecb RR |
1508 | /* |
1509 | * Even if we did not try to evict anon pages at all, we want to | |
1510 | * rebalance the anon lru active/inactive ratio. | |
1511 | */ | |
1512 | if (!scan_global_lru(sc) || inactive_anon_is_low(zone)) | |
1513 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); | |
1514 | else if (!scan_global_lru(sc)) | |
1515 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); | |
1516 | ||
232ea4d6 | 1517 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1518 | } |
1519 | ||
1520 | /* | |
1521 | * This is the direct reclaim path, for page-allocating processes. We only | |
1522 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1523 | * request. | |
1524 | * | |
1525 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
1526 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
1527 | * allocation or | |
1528 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
1529 | * satisfy the `incremental min' zone defense algorithm. | |
1530 | * | |
1da177e4 LT |
1531 | * If a zone is deemed to be full of pinned pages then just give it a light |
1532 | * scan then give up on it. | |
1533 | */ | |
a79311c1 | 1534 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1535 | struct scan_control *sc) |
1da177e4 | 1536 | { |
54a6eb5c | 1537 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
dd1a239f | 1538 | struct zoneref *z; |
54a6eb5c | 1539 | struct zone *zone; |
1cfb419b | 1540 | |
408d8544 | 1541 | sc->all_unreclaimable = 1; |
54a6eb5c | 1542 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
f3fe6512 | 1543 | if (!populated_zone(zone)) |
1da177e4 | 1544 | continue; |
1cfb419b KH |
1545 | /* |
1546 | * Take care memory controller reclaiming has small influence | |
1547 | * to global LRU. | |
1548 | */ | |
1549 | if (scan_global_lru(sc)) { | |
1550 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1551 | continue; | |
1552 | note_zone_scanning_priority(zone, priority); | |
1da177e4 | 1553 | |
1cfb419b KH |
1554 | if (zone_is_all_unreclaimable(zone) && |
1555 | priority != DEF_PRIORITY) | |
1556 | continue; /* Let kswapd poll it */ | |
1557 | sc->all_unreclaimable = 0; | |
1558 | } else { | |
1559 | /* | |
1560 | * Ignore cpuset limitation here. We just want to reduce | |
1561 | * # of used pages by us regardless of memory shortage. | |
1562 | */ | |
1563 | sc->all_unreclaimable = 0; | |
1564 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, | |
1565 | priority); | |
1566 | } | |
408d8544 | 1567 | |
a79311c1 | 1568 | shrink_zone(priority, zone, sc); |
1da177e4 LT |
1569 | } |
1570 | } | |
4f98a2fe | 1571 | |
1da177e4 LT |
1572 | /* |
1573 | * This is the main entry point to direct page reclaim. | |
1574 | * | |
1575 | * If a full scan of the inactive list fails to free enough memory then we | |
1576 | * are "out of memory" and something needs to be killed. | |
1577 | * | |
1578 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1579 | * high - the zone may be full of dirty or under-writeback pages, which this | |
1580 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
1581 | * hope that some of these pages can be written. But if the allocating task | |
1582 | * holds filesystem locks which prevent writeout this might not work, and the | |
1583 | * allocation attempt will fail. | |
a41f24ea NA |
1584 | * |
1585 | * returns: 0, if no pages reclaimed | |
1586 | * else, the number of pages reclaimed | |
1da177e4 | 1587 | */ |
dac1d27b | 1588 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1589 | struct scan_control *sc) |
1da177e4 LT |
1590 | { |
1591 | int priority; | |
c700be3d | 1592 | unsigned long ret = 0; |
69e05944 | 1593 | unsigned long total_scanned = 0; |
1da177e4 | 1594 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 | 1595 | unsigned long lru_pages = 0; |
dd1a239f | 1596 | struct zoneref *z; |
54a6eb5c | 1597 | struct zone *zone; |
dd1a239f | 1598 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
1da177e4 | 1599 | |
873b4771 KK |
1600 | delayacct_freepages_start(); |
1601 | ||
1cfb419b KH |
1602 | if (scan_global_lru(sc)) |
1603 | count_vm_event(ALLOCSTALL); | |
1604 | /* | |
1605 | * mem_cgroup will not do shrink_slab. | |
1606 | */ | |
1607 | if (scan_global_lru(sc)) { | |
54a6eb5c | 1608 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1da177e4 | 1609 | |
1cfb419b KH |
1610 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1611 | continue; | |
1da177e4 | 1612 | |
4f98a2fe | 1613 | lru_pages += zone_lru_pages(zone); |
1cfb419b | 1614 | } |
1da177e4 LT |
1615 | } |
1616 | ||
1617 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1618 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1619 | if (!priority) |
1620 | disable_swap_token(); | |
a79311c1 | 1621 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1622 | /* |
1623 | * Don't shrink slabs when reclaiming memory from | |
1624 | * over limit cgroups | |
1625 | */ | |
91a45470 | 1626 | if (scan_global_lru(sc)) { |
dd1a239f | 1627 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1628 | if (reclaim_state) { |
a79311c1 | 1629 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1630 | reclaim_state->reclaimed_slab = 0; |
1631 | } | |
1da177e4 | 1632 | } |
66e1707b | 1633 | total_scanned += sc->nr_scanned; |
a79311c1 RR |
1634 | if (sc->nr_reclaimed >= sc->swap_cluster_max) { |
1635 | ret = sc->nr_reclaimed; | |
1da177e4 LT |
1636 | goto out; |
1637 | } | |
1638 | ||
1639 | /* | |
1640 | * Try to write back as many pages as we just scanned. This | |
1641 | * tends to cause slow streaming writers to write data to the | |
1642 | * disk smoothly, at the dirtying rate, which is nice. But | |
1643 | * that's undesirable in laptop mode, where we *want* lumpy | |
1644 | * writeout. So in laptop mode, write out the whole world. | |
1645 | */ | |
66e1707b BS |
1646 | if (total_scanned > sc->swap_cluster_max + |
1647 | sc->swap_cluster_max / 2) { | |
687a21ce | 1648 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
66e1707b | 1649 | sc->may_writepage = 1; |
1da177e4 LT |
1650 | } |
1651 | ||
1652 | /* Take a nap, wait for some writeback to complete */ | |
4dd4b920 | 1653 | if (sc->nr_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1654 | congestion_wait(WRITE, HZ/10); |
1da177e4 | 1655 | } |
87547ee9 | 1656 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
91a45470 | 1657 | if (!sc->all_unreclaimable && scan_global_lru(sc)) |
a79311c1 | 1658 | ret = sc->nr_reclaimed; |
1da177e4 | 1659 | out: |
3bb1a852 MB |
1660 | /* |
1661 | * Now that we've scanned all the zones at this priority level, note | |
1662 | * that level within the zone so that the next thread which performs | |
1663 | * scanning of this zone will immediately start out at this priority | |
1664 | * level. This affects only the decision whether or not to bring | |
1665 | * mapped pages onto the inactive list. | |
1666 | */ | |
1667 | if (priority < 0) | |
1668 | priority = 0; | |
1da177e4 | 1669 | |
1cfb419b | 1670 | if (scan_global_lru(sc)) { |
54a6eb5c | 1671 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1cfb419b KH |
1672 | |
1673 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1674 | continue; | |
1675 | ||
1676 | zone->prev_priority = priority; | |
1677 | } | |
1678 | } else | |
1679 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); | |
1da177e4 | 1680 | |
873b4771 KK |
1681 | delayacct_freepages_end(); |
1682 | ||
1da177e4 LT |
1683 | return ret; |
1684 | } | |
1685 | ||
dac1d27b MG |
1686 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
1687 | gfp_t gfp_mask) | |
66e1707b BS |
1688 | { |
1689 | struct scan_control sc = { | |
1690 | .gfp_mask = gfp_mask, | |
1691 | .may_writepage = !laptop_mode, | |
1692 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1693 | .may_swap = 1, | |
1694 | .swappiness = vm_swappiness, | |
1695 | .order = order, | |
1696 | .mem_cgroup = NULL, | |
1697 | .isolate_pages = isolate_pages_global, | |
1698 | }; | |
1699 | ||
dd1a239f | 1700 | return do_try_to_free_pages(zonelist, &sc); |
66e1707b BS |
1701 | } |
1702 | ||
00f0b825 | 1703 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1704 | |
e1a1cd59 | 1705 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
8c7c6e34 KH |
1706 | gfp_t gfp_mask, |
1707 | bool noswap) | |
66e1707b BS |
1708 | { |
1709 | struct scan_control sc = { | |
66e1707b BS |
1710 | .may_writepage = !laptop_mode, |
1711 | .may_swap = 1, | |
1712 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1713 | .swappiness = vm_swappiness, | |
1714 | .order = 0, | |
1715 | .mem_cgroup = mem_cont, | |
1716 | .isolate_pages = mem_cgroup_isolate_pages, | |
1717 | }; | |
dac1d27b | 1718 | struct zonelist *zonelist; |
66e1707b | 1719 | |
8c7c6e34 KH |
1720 | if (noswap) |
1721 | sc.may_swap = 0; | |
1722 | ||
dd1a239f MG |
1723 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1724 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1725 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1726 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1727 | } |
1728 | #endif | |
1729 | ||
1da177e4 LT |
1730 | /* |
1731 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1732 | * they are all at pages_high. | |
1733 | * | |
1da177e4 LT |
1734 | * Returns the number of pages which were actually freed. |
1735 | * | |
1736 | * There is special handling here for zones which are full of pinned pages. | |
1737 | * This can happen if the pages are all mlocked, or if they are all used by | |
1738 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1739 | * What we do is to detect the case where all pages in the zone have been | |
1740 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1741 | * dead and from now on, only perform a short scan. Basically we're polling | |
1742 | * the zone for when the problem goes away. | |
1743 | * | |
1744 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1745 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1746 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1747 | * of the number of free pages in the lower zones. This interoperates with | |
1748 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1749 | * across the zones. | |
1750 | */ | |
d6277db4 | 1751 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1752 | { |
1da177e4 LT |
1753 | int all_zones_ok; |
1754 | int priority; | |
1755 | int i; | |
69e05944 | 1756 | unsigned long total_scanned; |
1da177e4 | 1757 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1758 | struct scan_control sc = { |
1759 | .gfp_mask = GFP_KERNEL, | |
1760 | .may_swap = 1, | |
d6277db4 RW |
1761 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1762 | .swappiness = vm_swappiness, | |
5ad333eb | 1763 | .order = order, |
66e1707b BS |
1764 | .mem_cgroup = NULL, |
1765 | .isolate_pages = isolate_pages_global, | |
179e9639 | 1766 | }; |
3bb1a852 MB |
1767 | /* |
1768 | * temp_priority is used to remember the scanning priority at which | |
1769 | * this zone was successfully refilled to free_pages == pages_high. | |
1770 | */ | |
1771 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
1772 | |
1773 | loop_again: | |
1774 | total_scanned = 0; | |
a79311c1 | 1775 | sc.nr_reclaimed = 0; |
c0bbbc73 | 1776 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1777 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 1778 | |
3bb1a852 MB |
1779 | for (i = 0; i < pgdat->nr_zones; i++) |
1780 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
1781 | |
1782 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1783 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1784 | unsigned long lru_pages = 0; | |
1785 | ||
f7b7fd8f RR |
1786 | /* The swap token gets in the way of swapout... */ |
1787 | if (!priority) | |
1788 | disable_swap_token(); | |
1789 | ||
1da177e4 LT |
1790 | all_zones_ok = 1; |
1791 | ||
d6277db4 RW |
1792 | /* |
1793 | * Scan in the highmem->dma direction for the highest | |
1794 | * zone which needs scanning | |
1795 | */ | |
1796 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1797 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1798 | |
d6277db4 RW |
1799 | if (!populated_zone(zone)) |
1800 | continue; | |
1da177e4 | 1801 | |
e815af95 DR |
1802 | if (zone_is_all_unreclaimable(zone) && |
1803 | priority != DEF_PRIORITY) | |
d6277db4 | 1804 | continue; |
1da177e4 | 1805 | |
556adecb RR |
1806 | /* |
1807 | * Do some background aging of the anon list, to give | |
1808 | * pages a chance to be referenced before reclaiming. | |
1809 | */ | |
1810 | if (inactive_anon_is_low(zone)) | |
1811 | shrink_active_list(SWAP_CLUSTER_MAX, zone, | |
1812 | &sc, priority, 0); | |
1813 | ||
d6277db4 RW |
1814 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1815 | 0, 0)) { | |
1816 | end_zone = i; | |
e1dbeda6 | 1817 | break; |
1da177e4 | 1818 | } |
1da177e4 | 1819 | } |
e1dbeda6 AM |
1820 | if (i < 0) |
1821 | goto out; | |
1822 | ||
1da177e4 LT |
1823 | for (i = 0; i <= end_zone; i++) { |
1824 | struct zone *zone = pgdat->node_zones + i; | |
1825 | ||
4f98a2fe | 1826 | lru_pages += zone_lru_pages(zone); |
1da177e4 LT |
1827 | } |
1828 | ||
1829 | /* | |
1830 | * Now scan the zone in the dma->highmem direction, stopping | |
1831 | * at the last zone which needs scanning. | |
1832 | * | |
1833 | * We do this because the page allocator works in the opposite | |
1834 | * direction. This prevents the page allocator from allocating | |
1835 | * pages behind kswapd's direction of progress, which would | |
1836 | * cause too much scanning of the lower zones. | |
1837 | */ | |
1838 | for (i = 0; i <= end_zone; i++) { | |
1839 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1840 | int nr_slab; |
1da177e4 | 1841 | |
f3fe6512 | 1842 | if (!populated_zone(zone)) |
1da177e4 LT |
1843 | continue; |
1844 | ||
e815af95 DR |
1845 | if (zone_is_all_unreclaimable(zone) && |
1846 | priority != DEF_PRIORITY) | |
1da177e4 LT |
1847 | continue; |
1848 | ||
d6277db4 RW |
1849 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1850 | end_zone, 0)) | |
1851 | all_zones_ok = 0; | |
3bb1a852 | 1852 | temp_priority[i] = priority; |
1da177e4 | 1853 | sc.nr_scanned = 0; |
3bb1a852 | 1854 | note_zone_scanning_priority(zone, priority); |
32a4330d RR |
1855 | /* |
1856 | * We put equal pressure on every zone, unless one | |
1857 | * zone has way too many pages free already. | |
1858 | */ | |
1859 | if (!zone_watermark_ok(zone, order, 8*zone->pages_high, | |
1860 | end_zone, 0)) | |
a79311c1 | 1861 | shrink_zone(priority, zone, &sc); |
1da177e4 | 1862 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1863 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1864 | lru_pages); | |
a79311c1 | 1865 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 1866 | total_scanned += sc.nr_scanned; |
e815af95 | 1867 | if (zone_is_all_unreclaimable(zone)) |
1da177e4 | 1868 | continue; |
b15e0905 | 1869 | if (nr_slab == 0 && zone->pages_scanned >= |
4f98a2fe | 1870 | (zone_lru_pages(zone) * 6)) |
e815af95 DR |
1871 | zone_set_flag(zone, |
1872 | ZONE_ALL_UNRECLAIMABLE); | |
1da177e4 LT |
1873 | /* |
1874 | * If we've done a decent amount of scanning and | |
1875 | * the reclaim ratio is low, start doing writepage | |
1876 | * even in laptop mode | |
1877 | */ | |
1878 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 1879 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 LT |
1880 | sc.may_writepage = 1; |
1881 | } | |
1da177e4 LT |
1882 | if (all_zones_ok) |
1883 | break; /* kswapd: all done */ | |
1884 | /* | |
1885 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1886 | * another pass across the zones. | |
1887 | */ | |
4dd4b920 | 1888 | if (total_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1889 | congestion_wait(WRITE, HZ/10); |
1da177e4 LT |
1890 | |
1891 | /* | |
1892 | * We do this so kswapd doesn't build up large priorities for | |
1893 | * example when it is freeing in parallel with allocators. It | |
1894 | * matches the direct reclaim path behaviour in terms of impact | |
1895 | * on zone->*_priority. | |
1896 | */ | |
a79311c1 | 1897 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1898 | break; |
1899 | } | |
1900 | out: | |
3bb1a852 MB |
1901 | /* |
1902 | * Note within each zone the priority level at which this zone was | |
1903 | * brought into a happy state. So that the next thread which scans this | |
1904 | * zone will start out at that priority level. | |
1905 | */ | |
1da177e4 LT |
1906 | for (i = 0; i < pgdat->nr_zones; i++) { |
1907 | struct zone *zone = pgdat->node_zones + i; | |
1908 | ||
3bb1a852 | 1909 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
1910 | } |
1911 | if (!all_zones_ok) { | |
1912 | cond_resched(); | |
8357376d RW |
1913 | |
1914 | try_to_freeze(); | |
1915 | ||
73ce02e9 KM |
1916 | /* |
1917 | * Fragmentation may mean that the system cannot be | |
1918 | * rebalanced for high-order allocations in all zones. | |
1919 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
1920 | * it means the zones have been fully scanned and are still | |
1921 | * not balanced. For high-order allocations, there is | |
1922 | * little point trying all over again as kswapd may | |
1923 | * infinite loop. | |
1924 | * | |
1925 | * Instead, recheck all watermarks at order-0 as they | |
1926 | * are the most important. If watermarks are ok, kswapd will go | |
1927 | * back to sleep. High-order users can still perform direct | |
1928 | * reclaim if they wish. | |
1929 | */ | |
1930 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
1931 | order = sc.order = 0; | |
1932 | ||
1da177e4 LT |
1933 | goto loop_again; |
1934 | } | |
1935 | ||
a79311c1 | 1936 | return sc.nr_reclaimed; |
1da177e4 LT |
1937 | } |
1938 | ||
1939 | /* | |
1940 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 1941 | * from the init process. |
1da177e4 LT |
1942 | * |
1943 | * This basically trickles out pages so that we have _some_ | |
1944 | * free memory available even if there is no other activity | |
1945 | * that frees anything up. This is needed for things like routing | |
1946 | * etc, where we otherwise might have all activity going on in | |
1947 | * asynchronous contexts that cannot page things out. | |
1948 | * | |
1949 | * If there are applications that are active memory-allocators | |
1950 | * (most normal use), this basically shouldn't matter. | |
1951 | */ | |
1952 | static int kswapd(void *p) | |
1953 | { | |
1954 | unsigned long order; | |
1955 | pg_data_t *pgdat = (pg_data_t*)p; | |
1956 | struct task_struct *tsk = current; | |
1957 | DEFINE_WAIT(wait); | |
1958 | struct reclaim_state reclaim_state = { | |
1959 | .reclaimed_slab = 0, | |
1960 | }; | |
c5f59f08 | 1961 | node_to_cpumask_ptr(cpumask, pgdat->node_id); |
1da177e4 | 1962 | |
174596a0 | 1963 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 1964 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
1965 | current->reclaim_state = &reclaim_state; |
1966 | ||
1967 | /* | |
1968 | * Tell the memory management that we're a "memory allocator", | |
1969 | * and that if we need more memory we should get access to it | |
1970 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1971 | * never get caught in the normal page freeing logic. | |
1972 | * | |
1973 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1974 | * you need a small amount of memory in order to be able to | |
1975 | * page out something else, and this flag essentially protects | |
1976 | * us from recursively trying to free more memory as we're | |
1977 | * trying to free the first piece of memory in the first place). | |
1978 | */ | |
930d9152 | 1979 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 1980 | set_freezable(); |
1da177e4 LT |
1981 | |
1982 | order = 0; | |
1983 | for ( ; ; ) { | |
1984 | unsigned long new_order; | |
3e1d1d28 | 1985 | |
1da177e4 LT |
1986 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
1987 | new_order = pgdat->kswapd_max_order; | |
1988 | pgdat->kswapd_max_order = 0; | |
1989 | if (order < new_order) { | |
1990 | /* | |
1991 | * Don't sleep if someone wants a larger 'order' | |
1992 | * allocation | |
1993 | */ | |
1994 | order = new_order; | |
1995 | } else { | |
b1296cc4 RW |
1996 | if (!freezing(current)) |
1997 | schedule(); | |
1998 | ||
1da177e4 LT |
1999 | order = pgdat->kswapd_max_order; |
2000 | } | |
2001 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2002 | ||
b1296cc4 RW |
2003 | if (!try_to_freeze()) { |
2004 | /* We can speed up thawing tasks if we don't call | |
2005 | * balance_pgdat after returning from the refrigerator | |
2006 | */ | |
2007 | balance_pgdat(pgdat, order); | |
2008 | } | |
1da177e4 LT |
2009 | } |
2010 | return 0; | |
2011 | } | |
2012 | ||
2013 | /* | |
2014 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2015 | */ | |
2016 | void wakeup_kswapd(struct zone *zone, int order) | |
2017 | { | |
2018 | pg_data_t *pgdat; | |
2019 | ||
f3fe6512 | 2020 | if (!populated_zone(zone)) |
1da177e4 LT |
2021 | return; |
2022 | ||
2023 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 2024 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
2025 | return; |
2026 | if (pgdat->kswapd_max_order < order) | |
2027 | pgdat->kswapd_max_order = order; | |
02a0e53d | 2028 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2029 | return; |
8d0986e2 | 2030 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2031 | return; |
8d0986e2 | 2032 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2033 | } |
2034 | ||
4f98a2fe RR |
2035 | unsigned long global_lru_pages(void) |
2036 | { | |
2037 | return global_page_state(NR_ACTIVE_ANON) | |
2038 | + global_page_state(NR_ACTIVE_FILE) | |
2039 | + global_page_state(NR_INACTIVE_ANON) | |
2040 | + global_page_state(NR_INACTIVE_FILE); | |
2041 | } | |
2042 | ||
1da177e4 LT |
2043 | #ifdef CONFIG_PM |
2044 | /* | |
d6277db4 RW |
2045 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
2046 | * from LRU lists system-wide, for given pass and priority, and returns the | |
2047 | * number of reclaimed pages | |
2048 | * | |
2049 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
2050 | */ | |
e07aa05b NC |
2051 | static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, |
2052 | int pass, struct scan_control *sc) | |
d6277db4 RW |
2053 | { |
2054 | struct zone *zone; | |
2055 | unsigned long nr_to_scan, ret = 0; | |
b69408e8 | 2056 | enum lru_list l; |
d6277db4 RW |
2057 | |
2058 | for_each_zone(zone) { | |
2059 | ||
2060 | if (!populated_zone(zone)) | |
2061 | continue; | |
2062 | ||
e815af95 | 2063 | if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) |
d6277db4 RW |
2064 | continue; |
2065 | ||
894bc310 LS |
2066 | for_each_evictable_lru(l) { |
2067 | /* For pass = 0, we don't shrink the active list */ | |
4f98a2fe RR |
2068 | if (pass == 0 && |
2069 | (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE)) | |
b69408e8 CL |
2070 | continue; |
2071 | ||
2072 | zone->lru[l].nr_scan += | |
2073 | (zone_page_state(zone, NR_LRU_BASE + l) | |
2074 | >> prio) + 1; | |
2075 | if (zone->lru[l].nr_scan >= nr_pages || pass > 3) { | |
2076 | zone->lru[l].nr_scan = 0; | |
c8785385 | 2077 | nr_to_scan = min(nr_pages, |
b69408e8 CL |
2078 | zone_page_state(zone, |
2079 | NR_LRU_BASE + l)); | |
2080 | ret += shrink_list(l, nr_to_scan, zone, | |
2081 | sc, prio); | |
2082 | if (ret >= nr_pages) | |
2083 | return ret; | |
d6277db4 RW |
2084 | } |
2085 | } | |
d6277db4 RW |
2086 | } |
2087 | ||
2088 | return ret; | |
2089 | } | |
2090 | ||
2091 | /* | |
2092 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
2093 | * freed pages. | |
2094 | * | |
2095 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2096 | * LRU order by reclaiming preferentially | |
2097 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2098 | */ |
69e05944 | 2099 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 2100 | { |
d6277db4 | 2101 | unsigned long lru_pages, nr_slab; |
69e05944 | 2102 | unsigned long ret = 0; |
d6277db4 RW |
2103 | int pass; |
2104 | struct reclaim_state reclaim_state; | |
d6277db4 RW |
2105 | struct scan_control sc = { |
2106 | .gfp_mask = GFP_KERNEL, | |
2107 | .may_swap = 0, | |
2108 | .swap_cluster_max = nr_pages, | |
2109 | .may_writepage = 1, | |
2110 | .swappiness = vm_swappiness, | |
66e1707b | 2111 | .isolate_pages = isolate_pages_global, |
1da177e4 LT |
2112 | }; |
2113 | ||
2114 | current->reclaim_state = &reclaim_state; | |
69e05944 | 2115 | |
4f98a2fe | 2116 | lru_pages = global_lru_pages(); |
972d1a7b | 2117 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
2118 | /* If slab caches are huge, it's better to hit them first */ |
2119 | while (nr_slab >= lru_pages) { | |
2120 | reclaim_state.reclaimed_slab = 0; | |
2121 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
2122 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 2123 | break; |
d6277db4 RW |
2124 | |
2125 | ret += reclaim_state.reclaimed_slab; | |
2126 | if (ret >= nr_pages) | |
2127 | goto out; | |
2128 | ||
2129 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 2130 | } |
d6277db4 RW |
2131 | |
2132 | /* | |
2133 | * We try to shrink LRUs in 5 passes: | |
2134 | * 0 = Reclaim from inactive_list only | |
2135 | * 1 = Reclaim from active list but don't reclaim mapped | |
2136 | * 2 = 2nd pass of type 1 | |
2137 | * 3 = Reclaim mapped (normal reclaim) | |
2138 | * 4 = 2nd pass of type 3 | |
2139 | */ | |
2140 | for (pass = 0; pass < 5; pass++) { | |
2141 | int prio; | |
2142 | ||
d6277db4 RW |
2143 | /* Force reclaiming mapped pages in the passes #3 and #4 */ |
2144 | if (pass > 2) { | |
2145 | sc.may_swap = 1; | |
2146 | sc.swappiness = 100; | |
2147 | } | |
2148 | ||
2149 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
2150 | unsigned long nr_to_scan = nr_pages - ret; | |
2151 | ||
d6277db4 | 2152 | sc.nr_scanned = 0; |
d6277db4 RW |
2153 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
2154 | if (ret >= nr_pages) | |
2155 | goto out; | |
2156 | ||
2157 | reclaim_state.reclaimed_slab = 0; | |
76395d37 | 2158 | shrink_slab(sc.nr_scanned, sc.gfp_mask, |
4f98a2fe | 2159 | global_lru_pages()); |
d6277db4 RW |
2160 | ret += reclaim_state.reclaimed_slab; |
2161 | if (ret >= nr_pages) | |
2162 | goto out; | |
2163 | ||
2164 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
3fcfab16 | 2165 | congestion_wait(WRITE, HZ / 10); |
d6277db4 | 2166 | } |
248a0301 | 2167 | } |
d6277db4 RW |
2168 | |
2169 | /* | |
2170 | * If ret = 0, we could not shrink LRUs, but there may be something | |
2171 | * in slab caches | |
2172 | */ | |
76395d37 | 2173 | if (!ret) { |
d6277db4 RW |
2174 | do { |
2175 | reclaim_state.reclaimed_slab = 0; | |
4f98a2fe | 2176 | shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages()); |
d6277db4 RW |
2177 | ret += reclaim_state.reclaimed_slab; |
2178 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
76395d37 | 2179 | } |
d6277db4 RW |
2180 | |
2181 | out: | |
1da177e4 | 2182 | current->reclaim_state = NULL; |
d6277db4 | 2183 | |
1da177e4 LT |
2184 | return ret; |
2185 | } | |
2186 | #endif | |
2187 | ||
1da177e4 LT |
2188 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2189 | not required for correctness. So if the last cpu in a node goes | |
2190 | away, we get changed to run anywhere: as the first one comes back, | |
2191 | restore their cpu bindings. */ | |
9c7b216d | 2192 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2193 | unsigned long action, void *hcpu) |
1da177e4 | 2194 | { |
58c0a4a7 | 2195 | int nid; |
1da177e4 | 2196 | |
8bb78442 | 2197 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2198 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 MT |
2199 | pg_data_t *pgdat = NODE_DATA(nid); |
2200 | node_to_cpumask_ptr(mask, pgdat->node_id); | |
2201 | ||
3e597945 | 2202 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2203 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2204 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2205 | } |
2206 | } | |
2207 | return NOTIFY_OK; | |
2208 | } | |
1da177e4 | 2209 | |
3218ae14 YG |
2210 | /* |
2211 | * This kswapd start function will be called by init and node-hot-add. | |
2212 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2213 | */ | |
2214 | int kswapd_run(int nid) | |
2215 | { | |
2216 | pg_data_t *pgdat = NODE_DATA(nid); | |
2217 | int ret = 0; | |
2218 | ||
2219 | if (pgdat->kswapd) | |
2220 | return 0; | |
2221 | ||
2222 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2223 | if (IS_ERR(pgdat->kswapd)) { | |
2224 | /* failure at boot is fatal */ | |
2225 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2226 | printk("Failed to start kswapd on node %d\n",nid); | |
2227 | ret = -1; | |
2228 | } | |
2229 | return ret; | |
2230 | } | |
2231 | ||
1da177e4 LT |
2232 | static int __init kswapd_init(void) |
2233 | { | |
3218ae14 | 2234 | int nid; |
69e05944 | 2235 | |
1da177e4 | 2236 | swap_setup(); |
9422ffba | 2237 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2238 | kswapd_run(nid); |
1da177e4 LT |
2239 | hotcpu_notifier(cpu_callback, 0); |
2240 | return 0; | |
2241 | } | |
2242 | ||
2243 | module_init(kswapd_init) | |
9eeff239 CL |
2244 | |
2245 | #ifdef CONFIG_NUMA | |
2246 | /* | |
2247 | * Zone reclaim mode | |
2248 | * | |
2249 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2250 | * the watermarks. | |
9eeff239 CL |
2251 | */ |
2252 | int zone_reclaim_mode __read_mostly; | |
2253 | ||
1b2ffb78 | 2254 | #define RECLAIM_OFF 0 |
7d03431c | 2255 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2256 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2257 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2258 | ||
a92f7126 CL |
2259 | /* |
2260 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2261 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2262 | * a zone. | |
2263 | */ | |
2264 | #define ZONE_RECLAIM_PRIORITY 4 | |
2265 | ||
9614634f CL |
2266 | /* |
2267 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2268 | * occur. | |
2269 | */ | |
2270 | int sysctl_min_unmapped_ratio = 1; | |
2271 | ||
0ff38490 CL |
2272 | /* |
2273 | * If the number of slab pages in a zone grows beyond this percentage then | |
2274 | * slab reclaim needs to occur. | |
2275 | */ | |
2276 | int sysctl_min_slab_ratio = 5; | |
2277 | ||
9eeff239 CL |
2278 | /* |
2279 | * Try to free up some pages from this zone through reclaim. | |
2280 | */ | |
179e9639 | 2281 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2282 | { |
7fb2d46d | 2283 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2284 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2285 | struct task_struct *p = current; |
2286 | struct reclaim_state reclaim_state; | |
8695949a | 2287 | int priority; |
179e9639 AM |
2288 | struct scan_control sc = { |
2289 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
2290 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
2291 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
2292 | SWAP_CLUSTER_MAX), | |
179e9639 | 2293 | .gfp_mask = gfp_mask, |
d6277db4 | 2294 | .swappiness = vm_swappiness, |
66e1707b | 2295 | .isolate_pages = isolate_pages_global, |
179e9639 | 2296 | }; |
83e33a47 | 2297 | unsigned long slab_reclaimable; |
9eeff239 CL |
2298 | |
2299 | disable_swap_token(); | |
9eeff239 | 2300 | cond_resched(); |
d4f7796e CL |
2301 | /* |
2302 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2303 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2304 | * and RECLAIM_SWAP. | |
2305 | */ | |
2306 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
2307 | reclaim_state.reclaimed_slab = 0; |
2308 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2309 | |
0ff38490 CL |
2310 | if (zone_page_state(zone, NR_FILE_PAGES) - |
2311 | zone_page_state(zone, NR_FILE_MAPPED) > | |
2312 | zone->min_unmapped_pages) { | |
2313 | /* | |
2314 | * Free memory by calling shrink zone with increasing | |
2315 | * priorities until we have enough memory freed. | |
2316 | */ | |
2317 | priority = ZONE_RECLAIM_PRIORITY; | |
2318 | do { | |
3bb1a852 | 2319 | note_zone_scanning_priority(zone, priority); |
a79311c1 | 2320 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2321 | priority--; |
a79311c1 | 2322 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2323 | } |
c84db23c | 2324 | |
83e33a47 CL |
2325 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2326 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2327 | /* |
7fb2d46d | 2328 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2329 | * many pages were freed in this zone. So we take the current |
2330 | * number of slab pages and shake the slab until it is reduced | |
2331 | * by the same nr_pages that we used for reclaiming unmapped | |
2332 | * pages. | |
2a16e3f4 | 2333 | * |
0ff38490 CL |
2334 | * Note that shrink_slab will free memory on all zones and may |
2335 | * take a long time. | |
2a16e3f4 | 2336 | */ |
0ff38490 | 2337 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2338 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2339 | slab_reclaimable - nr_pages) | |
0ff38490 | 2340 | ; |
83e33a47 CL |
2341 | |
2342 | /* | |
2343 | * Update nr_reclaimed by the number of slab pages we | |
2344 | * reclaimed from this zone. | |
2345 | */ | |
a79311c1 | 2346 | sc.nr_reclaimed += slab_reclaimable - |
83e33a47 | 2347 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2a16e3f4 CL |
2348 | } |
2349 | ||
9eeff239 | 2350 | p->reclaim_state = NULL; |
d4f7796e | 2351 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
a79311c1 | 2352 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2353 | } |
179e9639 AM |
2354 | |
2355 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2356 | { | |
179e9639 | 2357 | int node_id; |
d773ed6b | 2358 | int ret; |
179e9639 AM |
2359 | |
2360 | /* | |
0ff38490 CL |
2361 | * Zone reclaim reclaims unmapped file backed pages and |
2362 | * slab pages if we are over the defined limits. | |
34aa1330 | 2363 | * |
9614634f CL |
2364 | * A small portion of unmapped file backed pages is needed for |
2365 | * file I/O otherwise pages read by file I/O will be immediately | |
2366 | * thrown out if the zone is overallocated. So we do not reclaim | |
2367 | * if less than a specified percentage of the zone is used by | |
2368 | * unmapped file backed pages. | |
179e9639 | 2369 | */ |
34aa1330 | 2370 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
2371 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
2372 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
2373 | <= zone->min_slab_pages) | |
9614634f | 2374 | return 0; |
179e9639 | 2375 | |
d773ed6b DR |
2376 | if (zone_is_all_unreclaimable(zone)) |
2377 | return 0; | |
2378 | ||
179e9639 | 2379 | /* |
d773ed6b | 2380 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2381 | */ |
d773ed6b | 2382 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
179e9639 AM |
2383 | return 0; |
2384 | ||
2385 | /* | |
2386 | * Only run zone reclaim on the local zone or on zones that do not | |
2387 | * have associated processors. This will favor the local processor | |
2388 | * over remote processors and spread off node memory allocations | |
2389 | * as wide as possible. | |
2390 | */ | |
89fa3024 | 2391 | node_id = zone_to_nid(zone); |
37c0708d | 2392 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
179e9639 | 2393 | return 0; |
d773ed6b DR |
2394 | |
2395 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
2396 | return 0; | |
2397 | ret = __zone_reclaim(zone, gfp_mask, order); | |
2398 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2399 | ||
2400 | return ret; | |
179e9639 | 2401 | } |
9eeff239 | 2402 | #endif |
894bc310 LS |
2403 | |
2404 | #ifdef CONFIG_UNEVICTABLE_LRU | |
2405 | /* | |
2406 | * page_evictable - test whether a page is evictable | |
2407 | * @page: the page to test | |
2408 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2409 | * | |
2410 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2411 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2412 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2413 | * |
2414 | * Reasons page might not be evictable: | |
ba9ddf49 | 2415 | * (1) page's mapping marked unevictable |
b291f000 | 2416 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2417 | * |
894bc310 LS |
2418 | */ |
2419 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2420 | { | |
2421 | ||
ba9ddf49 LS |
2422 | if (mapping_unevictable(page_mapping(page))) |
2423 | return 0; | |
2424 | ||
b291f000 NP |
2425 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2426 | return 0; | |
894bc310 LS |
2427 | |
2428 | return 1; | |
2429 | } | |
89e004ea LS |
2430 | |
2431 | /** | |
2432 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2433 | * @page: page to check evictability and move to appropriate lru list | |
2434 | * @zone: zone page is in | |
2435 | * | |
2436 | * Checks a page for evictability and moves the page to the appropriate | |
2437 | * zone lru list. | |
2438 | * | |
2439 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2440 | * have PageUnevictable set. | |
2441 | */ | |
2442 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2443 | { | |
2444 | VM_BUG_ON(PageActive(page)); | |
2445 | ||
2446 | retry: | |
2447 | ClearPageUnevictable(page); | |
2448 | if (page_evictable(page, NULL)) { | |
2449 | enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page); | |
af936a16 | 2450 | |
89e004ea LS |
2451 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2452 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2453 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2454 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2455 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2456 | } else { | |
2457 | /* | |
2458 | * rotate unevictable list | |
2459 | */ | |
2460 | SetPageUnevictable(page); | |
2461 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2462 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2463 | if (page_evictable(page, NULL)) |
2464 | goto retry; | |
2465 | } | |
2466 | } | |
2467 | ||
2468 | /** | |
2469 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2470 | * @mapping: struct address_space to scan for evictable pages | |
2471 | * | |
2472 | * Scan all pages in mapping. Check unevictable pages for | |
2473 | * evictability and move them to the appropriate zone lru list. | |
2474 | */ | |
2475 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2476 | { | |
2477 | pgoff_t next = 0; | |
2478 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2479 | PAGE_CACHE_SHIFT; | |
2480 | struct zone *zone; | |
2481 | struct pagevec pvec; | |
2482 | ||
2483 | if (mapping->nrpages == 0) | |
2484 | return; | |
2485 | ||
2486 | pagevec_init(&pvec, 0); | |
2487 | while (next < end && | |
2488 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2489 | int i; | |
2490 | int pg_scanned = 0; | |
2491 | ||
2492 | zone = NULL; | |
2493 | ||
2494 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2495 | struct page *page = pvec.pages[i]; | |
2496 | pgoff_t page_index = page->index; | |
2497 | struct zone *pagezone = page_zone(page); | |
2498 | ||
2499 | pg_scanned++; | |
2500 | if (page_index > next) | |
2501 | next = page_index; | |
2502 | next++; | |
2503 | ||
2504 | if (pagezone != zone) { | |
2505 | if (zone) | |
2506 | spin_unlock_irq(&zone->lru_lock); | |
2507 | zone = pagezone; | |
2508 | spin_lock_irq(&zone->lru_lock); | |
2509 | } | |
2510 | ||
2511 | if (PageLRU(page) && PageUnevictable(page)) | |
2512 | check_move_unevictable_page(page, zone); | |
2513 | } | |
2514 | if (zone) | |
2515 | spin_unlock_irq(&zone->lru_lock); | |
2516 | pagevec_release(&pvec); | |
2517 | ||
2518 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2519 | } | |
2520 | ||
2521 | } | |
af936a16 LS |
2522 | |
2523 | /** | |
2524 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2525 | * @zone - zone of which to scan the unevictable list | |
2526 | * | |
2527 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2528 | * evictable. Move those that have to @zone's inactive list where they | |
2529 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2530 | * to reactivate them. Pages that are still unevictable are rotated | |
2531 | * back onto @zone's unevictable list. | |
2532 | */ | |
2533 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2534 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2535 | { |
2536 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2537 | unsigned long scan; | |
2538 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2539 | ||
2540 | while (nr_to_scan > 0) { | |
2541 | unsigned long batch_size = min(nr_to_scan, | |
2542 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2543 | ||
2544 | spin_lock_irq(&zone->lru_lock); | |
2545 | for (scan = 0; scan < batch_size; scan++) { | |
2546 | struct page *page = lru_to_page(l_unevictable); | |
2547 | ||
2548 | if (!trylock_page(page)) | |
2549 | continue; | |
2550 | ||
2551 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
2552 | ||
2553 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
2554 | check_move_unevictable_page(page, zone); | |
2555 | ||
2556 | unlock_page(page); | |
2557 | } | |
2558 | spin_unlock_irq(&zone->lru_lock); | |
2559 | ||
2560 | nr_to_scan -= batch_size; | |
2561 | } | |
2562 | } | |
2563 | ||
2564 | ||
2565 | /** | |
2566 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
2567 | * | |
2568 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
2569 | * pages that have become evictable. Move those back to the zones' | |
2570 | * inactive list where they become candidates for reclaim. | |
2571 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
2572 | * and we add swap to the system. As such, it runs in the context of a task | |
2573 | * that has possibly/probably made some previously unevictable pages | |
2574 | * evictable. | |
2575 | */ | |
ff30153b | 2576 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
2577 | { |
2578 | struct zone *zone; | |
2579 | ||
2580 | for_each_zone(zone) { | |
2581 | scan_zone_unevictable_pages(zone); | |
2582 | } | |
2583 | } | |
2584 | ||
2585 | /* | |
2586 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
2587 | * all nodes' unevictable lists for evictable pages | |
2588 | */ | |
2589 | unsigned long scan_unevictable_pages; | |
2590 | ||
2591 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
2592 | struct file *file, void __user *buffer, | |
2593 | size_t *length, loff_t *ppos) | |
2594 | { | |
2595 | proc_doulongvec_minmax(table, write, file, buffer, length, ppos); | |
2596 | ||
2597 | if (write && *(unsigned long *)table->data) | |
2598 | scan_all_zones_unevictable_pages(); | |
2599 | ||
2600 | scan_unevictable_pages = 0; | |
2601 | return 0; | |
2602 | } | |
2603 | ||
2604 | /* | |
2605 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
2606 | * a specified node's per zone unevictable lists for evictable pages. | |
2607 | */ | |
2608 | ||
2609 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
2610 | struct sysdev_attribute *attr, | |
2611 | char *buf) | |
2612 | { | |
2613 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
2614 | } | |
2615 | ||
2616 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
2617 | struct sysdev_attribute *attr, | |
2618 | const char *buf, size_t count) | |
2619 | { | |
2620 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
2621 | struct zone *zone; | |
2622 | unsigned long res; | |
2623 | unsigned long req = strict_strtoul(buf, 10, &res); | |
2624 | ||
2625 | if (!req) | |
2626 | return 1; /* zero is no-op */ | |
2627 | ||
2628 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
2629 | if (!populated_zone(zone)) | |
2630 | continue; | |
2631 | scan_zone_unevictable_pages(zone); | |
2632 | } | |
2633 | return 1; | |
2634 | } | |
2635 | ||
2636 | ||
2637 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
2638 | read_scan_unevictable_node, | |
2639 | write_scan_unevictable_node); | |
2640 | ||
2641 | int scan_unevictable_register_node(struct node *node) | |
2642 | { | |
2643 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2644 | } | |
2645 | ||
2646 | void scan_unevictable_unregister_node(struct node *node) | |
2647 | { | |
2648 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2649 | } | |
2650 | ||
894bc310 | 2651 | #endif |