Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/kernel_stat.h> | |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
27 | buffer_heads_over_limit */ | |
28 | #include <linux/mm_inline.h> | |
29 | #include <linux/pagevec.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/rmap.h> | |
32 | #include <linux/topology.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cpuset.h> | |
35 | #include <linux/notifier.h> | |
36 | #include <linux/rwsem.h> | |
248a0301 | 37 | #include <linux/delay.h> |
3218ae14 | 38 | #include <linux/kthread.h> |
7dfb7103 | 39 | #include <linux/freezer.h> |
66e1707b | 40 | #include <linux/memcontrol.h> |
873b4771 | 41 | #include <linux/delayacct.h> |
1da177e4 LT |
42 | |
43 | #include <asm/tlbflush.h> | |
44 | #include <asm/div64.h> | |
45 | ||
46 | #include <linux/swapops.h> | |
47 | ||
0f8053a5 NP |
48 | #include "internal.h" |
49 | ||
1da177e4 | 50 | struct scan_control { |
1da177e4 LT |
51 | /* Incremented by the number of inactive pages that were scanned */ |
52 | unsigned long nr_scanned; | |
53 | ||
1da177e4 | 54 | /* This context's GFP mask */ |
6daa0e28 | 55 | gfp_t gfp_mask; |
1da177e4 LT |
56 | |
57 | int may_writepage; | |
58 | ||
f1fd1067 CL |
59 | /* Can pages be swapped as part of reclaim? */ |
60 | int may_swap; | |
61 | ||
1da177e4 LT |
62 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
63 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
64 | * In this context, it doesn't matter that we scan the | |
65 | * whole list at once. */ | |
66 | int swap_cluster_max; | |
d6277db4 RW |
67 | |
68 | int swappiness; | |
408d8544 NP |
69 | |
70 | int all_unreclaimable; | |
5ad333eb AW |
71 | |
72 | int order; | |
66e1707b BS |
73 | |
74 | /* Which cgroup do we reclaim from */ | |
75 | struct mem_cgroup *mem_cgroup; | |
76 | ||
77 | /* Pluggable isolate pages callback */ | |
78 | unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst, | |
79 | unsigned long *scanned, int order, int mode, | |
80 | struct zone *z, struct mem_cgroup *mem_cont, | |
4f98a2fe | 81 | int active, int file); |
1da177e4 LT |
82 | }; |
83 | ||
1da177e4 LT |
84 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
85 | ||
86 | #ifdef ARCH_HAS_PREFETCH | |
87 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
88 | do { \ | |
89 | if ((_page)->lru.prev != _base) { \ | |
90 | struct page *prev; \ | |
91 | \ | |
92 | prev = lru_to_page(&(_page->lru)); \ | |
93 | prefetch(&prev->_field); \ | |
94 | } \ | |
95 | } while (0) | |
96 | #else | |
97 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
98 | #endif | |
99 | ||
100 | #ifdef ARCH_HAS_PREFETCHW | |
101 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
102 | do { \ | |
103 | if ((_page)->lru.prev != _base) { \ | |
104 | struct page *prev; \ | |
105 | \ | |
106 | prev = lru_to_page(&(_page->lru)); \ | |
107 | prefetchw(&prev->_field); \ | |
108 | } \ | |
109 | } while (0) | |
110 | #else | |
111 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
112 | #endif | |
113 | ||
114 | /* | |
115 | * From 0 .. 100. Higher means more swappy. | |
116 | */ | |
117 | int vm_swappiness = 60; | |
bd1e22b8 | 118 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
119 | |
120 | static LIST_HEAD(shrinker_list); | |
121 | static DECLARE_RWSEM(shrinker_rwsem); | |
122 | ||
00f0b825 | 123 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
91a45470 KH |
124 | #define scan_global_lru(sc) (!(sc)->mem_cgroup) |
125 | #else | |
126 | #define scan_global_lru(sc) (1) | |
127 | #endif | |
128 | ||
1da177e4 LT |
129 | /* |
130 | * Add a shrinker callback to be called from the vm | |
131 | */ | |
8e1f936b | 132 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 133 | { |
8e1f936b RR |
134 | shrinker->nr = 0; |
135 | down_write(&shrinker_rwsem); | |
136 | list_add_tail(&shrinker->list, &shrinker_list); | |
137 | up_write(&shrinker_rwsem); | |
1da177e4 | 138 | } |
8e1f936b | 139 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
140 | |
141 | /* | |
142 | * Remove one | |
143 | */ | |
8e1f936b | 144 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
145 | { |
146 | down_write(&shrinker_rwsem); | |
147 | list_del(&shrinker->list); | |
148 | up_write(&shrinker_rwsem); | |
1da177e4 | 149 | } |
8e1f936b | 150 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
151 | |
152 | #define SHRINK_BATCH 128 | |
153 | /* | |
154 | * Call the shrink functions to age shrinkable caches | |
155 | * | |
156 | * Here we assume it costs one seek to replace a lru page and that it also | |
157 | * takes a seek to recreate a cache object. With this in mind we age equal | |
158 | * percentages of the lru and ageable caches. This should balance the seeks | |
159 | * generated by these structures. | |
160 | * | |
183ff22b | 161 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
162 | * slab to avoid swapping. |
163 | * | |
164 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
165 | * | |
166 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
167 | * are eligible for the caller's allocation attempt. It is used for balancing | |
168 | * slab reclaim versus page reclaim. | |
b15e0905 | 169 | * |
170 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 171 | */ |
69e05944 AM |
172 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
173 | unsigned long lru_pages) | |
1da177e4 LT |
174 | { |
175 | struct shrinker *shrinker; | |
69e05944 | 176 | unsigned long ret = 0; |
1da177e4 LT |
177 | |
178 | if (scanned == 0) | |
179 | scanned = SWAP_CLUSTER_MAX; | |
180 | ||
181 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 182 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
183 | |
184 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
185 | unsigned long long delta; | |
186 | unsigned long total_scan; | |
8e1f936b | 187 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
1da177e4 LT |
188 | |
189 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 190 | delta *= max_pass; |
1da177e4 LT |
191 | do_div(delta, lru_pages + 1); |
192 | shrinker->nr += delta; | |
ea164d73 AA |
193 | if (shrinker->nr < 0) { |
194 | printk(KERN_ERR "%s: nr=%ld\n", | |
d40cee24 | 195 | __func__, shrinker->nr); |
ea164d73 AA |
196 | shrinker->nr = max_pass; |
197 | } | |
198 | ||
199 | /* | |
200 | * Avoid risking looping forever due to too large nr value: | |
201 | * never try to free more than twice the estimate number of | |
202 | * freeable entries. | |
203 | */ | |
204 | if (shrinker->nr > max_pass * 2) | |
205 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
206 | |
207 | total_scan = shrinker->nr; | |
208 | shrinker->nr = 0; | |
209 | ||
210 | while (total_scan >= SHRINK_BATCH) { | |
211 | long this_scan = SHRINK_BATCH; | |
212 | int shrink_ret; | |
b15e0905 | 213 | int nr_before; |
1da177e4 | 214 | |
8e1f936b RR |
215 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
216 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); | |
1da177e4 LT |
217 | if (shrink_ret == -1) |
218 | break; | |
b15e0905 | 219 | if (shrink_ret < nr_before) |
220 | ret += nr_before - shrink_ret; | |
f8891e5e | 221 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
222 | total_scan -= this_scan; |
223 | ||
224 | cond_resched(); | |
225 | } | |
226 | ||
227 | shrinker->nr += total_scan; | |
228 | } | |
229 | up_read(&shrinker_rwsem); | |
b15e0905 | 230 | return ret; |
1da177e4 LT |
231 | } |
232 | ||
233 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
234 | static inline int page_mapping_inuse(struct page *page) | |
235 | { | |
236 | struct address_space *mapping; | |
237 | ||
238 | /* Page is in somebody's page tables. */ | |
239 | if (page_mapped(page)) | |
240 | return 1; | |
241 | ||
242 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
243 | if (PageSwapCache(page)) | |
244 | return 1; | |
245 | ||
246 | mapping = page_mapping(page); | |
247 | if (!mapping) | |
248 | return 0; | |
249 | ||
250 | /* File is mmap'd by somebody? */ | |
251 | return mapping_mapped(mapping); | |
252 | } | |
253 | ||
254 | static inline int is_page_cache_freeable(struct page *page) | |
255 | { | |
256 | return page_count(page) - !!PagePrivate(page) == 2; | |
257 | } | |
258 | ||
259 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
260 | { | |
930d9152 | 261 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
262 | return 1; |
263 | if (!bdi_write_congested(bdi)) | |
264 | return 1; | |
265 | if (bdi == current->backing_dev_info) | |
266 | return 1; | |
267 | return 0; | |
268 | } | |
269 | ||
270 | /* | |
271 | * We detected a synchronous write error writing a page out. Probably | |
272 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
273 | * fsync(), msync() or close(). | |
274 | * | |
275 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
276 | * prevents it from being freed up. But we have a ref on the page and once | |
277 | * that page is locked, the mapping is pinned. | |
278 | * | |
279 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
280 | * __GFP_FS. | |
281 | */ | |
282 | static void handle_write_error(struct address_space *mapping, | |
283 | struct page *page, int error) | |
284 | { | |
285 | lock_page(page); | |
3e9f45bd GC |
286 | if (page_mapping(page) == mapping) |
287 | mapping_set_error(mapping, error); | |
1da177e4 LT |
288 | unlock_page(page); |
289 | } | |
290 | ||
c661b078 AW |
291 | /* Request for sync pageout. */ |
292 | enum pageout_io { | |
293 | PAGEOUT_IO_ASYNC, | |
294 | PAGEOUT_IO_SYNC, | |
295 | }; | |
296 | ||
04e62a29 CL |
297 | /* possible outcome of pageout() */ |
298 | typedef enum { | |
299 | /* failed to write page out, page is locked */ | |
300 | PAGE_KEEP, | |
301 | /* move page to the active list, page is locked */ | |
302 | PAGE_ACTIVATE, | |
303 | /* page has been sent to the disk successfully, page is unlocked */ | |
304 | PAGE_SUCCESS, | |
305 | /* page is clean and locked */ | |
306 | PAGE_CLEAN, | |
307 | } pageout_t; | |
308 | ||
1da177e4 | 309 | /* |
1742f19f AM |
310 | * pageout is called by shrink_page_list() for each dirty page. |
311 | * Calls ->writepage(). | |
1da177e4 | 312 | */ |
c661b078 AW |
313 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
314 | enum pageout_io sync_writeback) | |
1da177e4 LT |
315 | { |
316 | /* | |
317 | * If the page is dirty, only perform writeback if that write | |
318 | * will be non-blocking. To prevent this allocation from being | |
319 | * stalled by pagecache activity. But note that there may be | |
320 | * stalls if we need to run get_block(). We could test | |
321 | * PagePrivate for that. | |
322 | * | |
323 | * If this process is currently in generic_file_write() against | |
324 | * this page's queue, we can perform writeback even if that | |
325 | * will block. | |
326 | * | |
327 | * If the page is swapcache, write it back even if that would | |
328 | * block, for some throttling. This happens by accident, because | |
329 | * swap_backing_dev_info is bust: it doesn't reflect the | |
330 | * congestion state of the swapdevs. Easy to fix, if needed. | |
331 | * See swapfile.c:page_queue_congested(). | |
332 | */ | |
333 | if (!is_page_cache_freeable(page)) | |
334 | return PAGE_KEEP; | |
335 | if (!mapping) { | |
336 | /* | |
337 | * Some data journaling orphaned pages can have | |
338 | * page->mapping == NULL while being dirty with clean buffers. | |
339 | */ | |
323aca6c | 340 | if (PagePrivate(page)) { |
1da177e4 LT |
341 | if (try_to_free_buffers(page)) { |
342 | ClearPageDirty(page); | |
d40cee24 | 343 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
344 | return PAGE_CLEAN; |
345 | } | |
346 | } | |
347 | return PAGE_KEEP; | |
348 | } | |
349 | if (mapping->a_ops->writepage == NULL) | |
350 | return PAGE_ACTIVATE; | |
351 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
352 | return PAGE_KEEP; | |
353 | ||
354 | if (clear_page_dirty_for_io(page)) { | |
355 | int res; | |
356 | struct writeback_control wbc = { | |
357 | .sync_mode = WB_SYNC_NONE, | |
358 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
359 | .range_start = 0, |
360 | .range_end = LLONG_MAX, | |
1da177e4 LT |
361 | .nonblocking = 1, |
362 | .for_reclaim = 1, | |
363 | }; | |
364 | ||
365 | SetPageReclaim(page); | |
366 | res = mapping->a_ops->writepage(page, &wbc); | |
367 | if (res < 0) | |
368 | handle_write_error(mapping, page, res); | |
994fc28c | 369 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
370 | ClearPageReclaim(page); |
371 | return PAGE_ACTIVATE; | |
372 | } | |
c661b078 AW |
373 | |
374 | /* | |
375 | * Wait on writeback if requested to. This happens when | |
376 | * direct reclaiming a large contiguous area and the | |
377 | * first attempt to free a range of pages fails. | |
378 | */ | |
379 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
380 | wait_on_page_writeback(page); | |
381 | ||
1da177e4 LT |
382 | if (!PageWriteback(page)) { |
383 | /* synchronous write or broken a_ops? */ | |
384 | ClearPageReclaim(page); | |
385 | } | |
e129b5c2 | 386 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
387 | return PAGE_SUCCESS; |
388 | } | |
389 | ||
390 | return PAGE_CLEAN; | |
391 | } | |
392 | ||
a649fd92 | 393 | /* |
e286781d NP |
394 | * Same as remove_mapping, but if the page is removed from the mapping, it |
395 | * gets returned with a refcount of 0. | |
a649fd92 | 396 | */ |
e286781d | 397 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 398 | { |
28e4d965 NP |
399 | BUG_ON(!PageLocked(page)); |
400 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 401 | |
19fd6231 | 402 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 403 | /* |
0fd0e6b0 NP |
404 | * The non racy check for a busy page. |
405 | * | |
406 | * Must be careful with the order of the tests. When someone has | |
407 | * a ref to the page, it may be possible that they dirty it then | |
408 | * drop the reference. So if PageDirty is tested before page_count | |
409 | * here, then the following race may occur: | |
410 | * | |
411 | * get_user_pages(&page); | |
412 | * [user mapping goes away] | |
413 | * write_to(page); | |
414 | * !PageDirty(page) [good] | |
415 | * SetPageDirty(page); | |
416 | * put_page(page); | |
417 | * !page_count(page) [good, discard it] | |
418 | * | |
419 | * [oops, our write_to data is lost] | |
420 | * | |
421 | * Reversing the order of the tests ensures such a situation cannot | |
422 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
423 | * load is not satisfied before that of page->_count. | |
424 | * | |
425 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
426 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 427 | */ |
e286781d | 428 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 429 | goto cannot_free; |
e286781d NP |
430 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
431 | if (unlikely(PageDirty(page))) { | |
432 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 433 | goto cannot_free; |
e286781d | 434 | } |
49d2e9cc CL |
435 | |
436 | if (PageSwapCache(page)) { | |
437 | swp_entry_t swap = { .val = page_private(page) }; | |
438 | __delete_from_swap_cache(page); | |
19fd6231 | 439 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc | 440 | swap_free(swap); |
e286781d NP |
441 | } else { |
442 | __remove_from_page_cache(page); | |
19fd6231 | 443 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
444 | } |
445 | ||
49d2e9cc CL |
446 | return 1; |
447 | ||
448 | cannot_free: | |
19fd6231 | 449 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
450 | return 0; |
451 | } | |
452 | ||
e286781d NP |
453 | /* |
454 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
455 | * someone else has a ref on the page, abort and return 0. If it was | |
456 | * successfully detached, return 1. Assumes the caller has a single ref on | |
457 | * this page. | |
458 | */ | |
459 | int remove_mapping(struct address_space *mapping, struct page *page) | |
460 | { | |
461 | if (__remove_mapping(mapping, page)) { | |
462 | /* | |
463 | * Unfreezing the refcount with 1 rather than 2 effectively | |
464 | * drops the pagecache ref for us without requiring another | |
465 | * atomic operation. | |
466 | */ | |
467 | page_unfreeze_refs(page, 1); | |
468 | return 1; | |
469 | } | |
470 | return 0; | |
471 | } | |
472 | ||
894bc310 LS |
473 | /** |
474 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
475 | * @page: page to be put back to appropriate lru list | |
476 | * | |
477 | * Add previously isolated @page to appropriate LRU list. | |
478 | * Page may still be unevictable for other reasons. | |
479 | * | |
480 | * lru_lock must not be held, interrupts must be enabled. | |
481 | */ | |
482 | #ifdef CONFIG_UNEVICTABLE_LRU | |
483 | void putback_lru_page(struct page *page) | |
484 | { | |
485 | int lru; | |
486 | int active = !!TestClearPageActive(page); | |
487 | ||
488 | VM_BUG_ON(PageLRU(page)); | |
489 | ||
490 | redo: | |
491 | ClearPageUnevictable(page); | |
492 | ||
493 | if (page_evictable(page, NULL)) { | |
494 | /* | |
495 | * For evictable pages, we can use the cache. | |
496 | * In event of a race, worst case is we end up with an | |
497 | * unevictable page on [in]active list. | |
498 | * We know how to handle that. | |
499 | */ | |
500 | lru = active + page_is_file_cache(page); | |
501 | lru_cache_add_lru(page, lru); | |
502 | } else { | |
503 | /* | |
504 | * Put unevictable pages directly on zone's unevictable | |
505 | * list. | |
506 | */ | |
507 | lru = LRU_UNEVICTABLE; | |
508 | add_page_to_unevictable_list(page); | |
509 | } | |
510 | mem_cgroup_move_lists(page, lru); | |
511 | ||
512 | /* | |
513 | * page's status can change while we move it among lru. If an evictable | |
514 | * page is on unevictable list, it never be freed. To avoid that, | |
515 | * check after we added it to the list, again. | |
516 | */ | |
517 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
518 | if (!isolate_lru_page(page)) { | |
519 | put_page(page); | |
520 | goto redo; | |
521 | } | |
522 | /* This means someone else dropped this page from LRU | |
523 | * So, it will be freed or putback to LRU again. There is | |
524 | * nothing to do here. | |
525 | */ | |
526 | } | |
527 | ||
528 | put_page(page); /* drop ref from isolate */ | |
529 | } | |
530 | ||
531 | #else /* CONFIG_UNEVICTABLE_LRU */ | |
532 | ||
533 | void putback_lru_page(struct page *page) | |
534 | { | |
535 | int lru; | |
536 | VM_BUG_ON(PageLRU(page)); | |
537 | ||
538 | lru = !!TestClearPageActive(page) + page_is_file_cache(page); | |
539 | lru_cache_add_lru(page, lru); | |
540 | mem_cgroup_move_lists(page, lru); | |
541 | put_page(page); | |
542 | } | |
543 | #endif /* CONFIG_UNEVICTABLE_LRU */ | |
544 | ||
545 | ||
1da177e4 | 546 | /* |
1742f19f | 547 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 548 | */ |
1742f19f | 549 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
550 | struct scan_control *sc, |
551 | enum pageout_io sync_writeback) | |
1da177e4 LT |
552 | { |
553 | LIST_HEAD(ret_pages); | |
554 | struct pagevec freed_pvec; | |
555 | int pgactivate = 0; | |
05ff5137 | 556 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
557 | |
558 | cond_resched(); | |
559 | ||
560 | pagevec_init(&freed_pvec, 1); | |
561 | while (!list_empty(page_list)) { | |
562 | struct address_space *mapping; | |
563 | struct page *page; | |
564 | int may_enter_fs; | |
565 | int referenced; | |
566 | ||
567 | cond_resched(); | |
568 | ||
569 | page = lru_to_page(page_list); | |
570 | list_del(&page->lru); | |
571 | ||
529ae9aa | 572 | if (!trylock_page(page)) |
1da177e4 LT |
573 | goto keep; |
574 | ||
725d704e | 575 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
576 | |
577 | sc->nr_scanned++; | |
80e43426 | 578 | |
894bc310 LS |
579 | if (unlikely(!page_evictable(page, NULL))) { |
580 | unlock_page(page); | |
581 | putback_lru_page(page); | |
582 | continue; | |
583 | } | |
584 | ||
80e43426 CL |
585 | if (!sc->may_swap && page_mapped(page)) |
586 | goto keep_locked; | |
587 | ||
1da177e4 LT |
588 | /* Double the slab pressure for mapped and swapcache pages */ |
589 | if (page_mapped(page) || PageSwapCache(page)) | |
590 | sc->nr_scanned++; | |
591 | ||
c661b078 AW |
592 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
593 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
594 | ||
595 | if (PageWriteback(page)) { | |
596 | /* | |
597 | * Synchronous reclaim is performed in two passes, | |
598 | * first an asynchronous pass over the list to | |
599 | * start parallel writeback, and a second synchronous | |
600 | * pass to wait for the IO to complete. Wait here | |
601 | * for any page for which writeback has already | |
602 | * started. | |
603 | */ | |
604 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
605 | wait_on_page_writeback(page); | |
4dd4b920 | 606 | else |
c661b078 AW |
607 | goto keep_locked; |
608 | } | |
1da177e4 | 609 | |
bed7161a | 610 | referenced = page_referenced(page, 1, sc->mem_cgroup); |
1da177e4 | 611 | /* In active use or really unfreeable? Activate it. */ |
5ad333eb AW |
612 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && |
613 | referenced && page_mapping_inuse(page)) | |
1da177e4 LT |
614 | goto activate_locked; |
615 | ||
616 | #ifdef CONFIG_SWAP | |
617 | /* | |
618 | * Anonymous process memory has backing store? | |
619 | * Try to allocate it some swap space here. | |
620 | */ | |
6e5ef1a9 | 621 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 622 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 623 | goto activate_locked; |
1da177e4 LT |
624 | #endif /* CONFIG_SWAP */ |
625 | ||
626 | mapping = page_mapping(page); | |
1da177e4 LT |
627 | |
628 | /* | |
629 | * The page is mapped into the page tables of one or more | |
630 | * processes. Try to unmap it here. | |
631 | */ | |
632 | if (page_mapped(page) && mapping) { | |
a48d07af | 633 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
634 | case SWAP_FAIL: |
635 | goto activate_locked; | |
636 | case SWAP_AGAIN: | |
637 | goto keep_locked; | |
638 | case SWAP_SUCCESS: | |
639 | ; /* try to free the page below */ | |
640 | } | |
641 | } | |
642 | ||
643 | if (PageDirty(page)) { | |
5ad333eb | 644 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) |
1da177e4 | 645 | goto keep_locked; |
4dd4b920 | 646 | if (!may_enter_fs) |
1da177e4 | 647 | goto keep_locked; |
52a8363e | 648 | if (!sc->may_writepage) |
1da177e4 LT |
649 | goto keep_locked; |
650 | ||
651 | /* Page is dirty, try to write it out here */ | |
c661b078 | 652 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
653 | case PAGE_KEEP: |
654 | goto keep_locked; | |
655 | case PAGE_ACTIVATE: | |
656 | goto activate_locked; | |
657 | case PAGE_SUCCESS: | |
4dd4b920 | 658 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
659 | goto keep; |
660 | /* | |
661 | * A synchronous write - probably a ramdisk. Go | |
662 | * ahead and try to reclaim the page. | |
663 | */ | |
529ae9aa | 664 | if (!trylock_page(page)) |
1da177e4 LT |
665 | goto keep; |
666 | if (PageDirty(page) || PageWriteback(page)) | |
667 | goto keep_locked; | |
668 | mapping = page_mapping(page); | |
669 | case PAGE_CLEAN: | |
670 | ; /* try to free the page below */ | |
671 | } | |
672 | } | |
673 | ||
674 | /* | |
675 | * If the page has buffers, try to free the buffer mappings | |
676 | * associated with this page. If we succeed we try to free | |
677 | * the page as well. | |
678 | * | |
679 | * We do this even if the page is PageDirty(). | |
680 | * try_to_release_page() does not perform I/O, but it is | |
681 | * possible for a page to have PageDirty set, but it is actually | |
682 | * clean (all its buffers are clean). This happens if the | |
683 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 684 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
685 | * try_to_release_page() will discover that cleanness and will |
686 | * drop the buffers and mark the page clean - it can be freed. | |
687 | * | |
688 | * Rarely, pages can have buffers and no ->mapping. These are | |
689 | * the pages which were not successfully invalidated in | |
690 | * truncate_complete_page(). We try to drop those buffers here | |
691 | * and if that worked, and the page is no longer mapped into | |
692 | * process address space (page_count == 1) it can be freed. | |
693 | * Otherwise, leave the page on the LRU so it is swappable. | |
694 | */ | |
695 | if (PagePrivate(page)) { | |
696 | if (!try_to_release_page(page, sc->gfp_mask)) | |
697 | goto activate_locked; | |
e286781d NP |
698 | if (!mapping && page_count(page) == 1) { |
699 | unlock_page(page); | |
700 | if (put_page_testzero(page)) | |
701 | goto free_it; | |
702 | else { | |
703 | /* | |
704 | * rare race with speculative reference. | |
705 | * the speculative reference will free | |
706 | * this page shortly, so we may | |
707 | * increment nr_reclaimed here (and | |
708 | * leave it off the LRU). | |
709 | */ | |
710 | nr_reclaimed++; | |
711 | continue; | |
712 | } | |
713 | } | |
1da177e4 LT |
714 | } |
715 | ||
e286781d | 716 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 717 | goto keep_locked; |
1da177e4 | 718 | |
1da177e4 | 719 | unlock_page(page); |
e286781d | 720 | free_it: |
05ff5137 | 721 | nr_reclaimed++; |
e286781d NP |
722 | if (!pagevec_add(&freed_pvec, page)) { |
723 | __pagevec_free(&freed_pvec); | |
724 | pagevec_reinit(&freed_pvec); | |
725 | } | |
1da177e4 LT |
726 | continue; |
727 | ||
728 | activate_locked: | |
68a22394 RR |
729 | /* Not a candidate for swapping, so reclaim swap space. */ |
730 | if (PageSwapCache(page) && vm_swap_full()) | |
731 | remove_exclusive_swap_page_ref(page); | |
894bc310 | 732 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
733 | SetPageActive(page); |
734 | pgactivate++; | |
735 | keep_locked: | |
736 | unlock_page(page); | |
737 | keep: | |
738 | list_add(&page->lru, &ret_pages); | |
725d704e | 739 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
740 | } |
741 | list_splice(&ret_pages, page_list); | |
742 | if (pagevec_count(&freed_pvec)) | |
e286781d | 743 | __pagevec_free(&freed_pvec); |
f8891e5e | 744 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 745 | return nr_reclaimed; |
1da177e4 LT |
746 | } |
747 | ||
5ad333eb AW |
748 | /* LRU Isolation modes. */ |
749 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ | |
750 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ | |
751 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ | |
752 | ||
753 | /* | |
754 | * Attempt to remove the specified page from its LRU. Only take this page | |
755 | * if it is of the appropriate PageActive status. Pages which are being | |
756 | * freed elsewhere are also ignored. | |
757 | * | |
758 | * page: page to consider | |
759 | * mode: one of the LRU isolation modes defined above | |
760 | * | |
761 | * returns 0 on success, -ve errno on failure. | |
762 | */ | |
4f98a2fe | 763 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
764 | { |
765 | int ret = -EINVAL; | |
766 | ||
767 | /* Only take pages on the LRU. */ | |
768 | if (!PageLRU(page)) | |
769 | return ret; | |
770 | ||
771 | /* | |
772 | * When checking the active state, we need to be sure we are | |
773 | * dealing with comparible boolean values. Take the logical not | |
774 | * of each. | |
775 | */ | |
776 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
777 | return ret; | |
778 | ||
4f98a2fe RR |
779 | if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file)) |
780 | return ret; | |
781 | ||
894bc310 LS |
782 | /* |
783 | * When this function is being called for lumpy reclaim, we | |
784 | * initially look into all LRU pages, active, inactive and | |
785 | * unevictable; only give shrink_page_list evictable pages. | |
786 | */ | |
787 | if (PageUnevictable(page)) | |
788 | return ret; | |
789 | ||
5ad333eb AW |
790 | ret = -EBUSY; |
791 | if (likely(get_page_unless_zero(page))) { | |
792 | /* | |
793 | * Be careful not to clear PageLRU until after we're | |
794 | * sure the page is not being freed elsewhere -- the | |
795 | * page release code relies on it. | |
796 | */ | |
797 | ClearPageLRU(page); | |
798 | ret = 0; | |
799 | } | |
800 | ||
801 | return ret; | |
802 | } | |
803 | ||
1da177e4 LT |
804 | /* |
805 | * zone->lru_lock is heavily contended. Some of the functions that | |
806 | * shrink the lists perform better by taking out a batch of pages | |
807 | * and working on them outside the LRU lock. | |
808 | * | |
809 | * For pagecache intensive workloads, this function is the hottest | |
810 | * spot in the kernel (apart from copy_*_user functions). | |
811 | * | |
812 | * Appropriate locks must be held before calling this function. | |
813 | * | |
814 | * @nr_to_scan: The number of pages to look through on the list. | |
815 | * @src: The LRU list to pull pages off. | |
816 | * @dst: The temp list to put pages on to. | |
817 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
818 | * @order: The caller's attempted allocation order |
819 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 820 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
821 | * |
822 | * returns how many pages were moved onto *@dst. | |
823 | */ | |
69e05944 AM |
824 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
825 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 826 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 827 | { |
69e05944 | 828 | unsigned long nr_taken = 0; |
c9b02d97 | 829 | unsigned long scan; |
1da177e4 | 830 | |
c9b02d97 | 831 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
832 | struct page *page; |
833 | unsigned long pfn; | |
834 | unsigned long end_pfn; | |
835 | unsigned long page_pfn; | |
836 | int zone_id; | |
837 | ||
1da177e4 LT |
838 | page = lru_to_page(src); |
839 | prefetchw_prev_lru_page(page, src, flags); | |
840 | ||
725d704e | 841 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 842 | |
4f98a2fe | 843 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
844 | case 0: |
845 | list_move(&page->lru, dst); | |
7c8ee9a8 | 846 | nr_taken++; |
5ad333eb AW |
847 | break; |
848 | ||
849 | case -EBUSY: | |
850 | /* else it is being freed elsewhere */ | |
851 | list_move(&page->lru, src); | |
852 | continue; | |
46453a6e | 853 | |
5ad333eb AW |
854 | default: |
855 | BUG(); | |
856 | } | |
857 | ||
858 | if (!order) | |
859 | continue; | |
860 | ||
861 | /* | |
862 | * Attempt to take all pages in the order aligned region | |
863 | * surrounding the tag page. Only take those pages of | |
864 | * the same active state as that tag page. We may safely | |
865 | * round the target page pfn down to the requested order | |
866 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
867 | * where that page is in a different zone we will detect | |
868 | * it from its zone id and abort this block scan. | |
869 | */ | |
870 | zone_id = page_zone_id(page); | |
871 | page_pfn = page_to_pfn(page); | |
872 | pfn = page_pfn & ~((1 << order) - 1); | |
873 | end_pfn = pfn + (1 << order); | |
874 | for (; pfn < end_pfn; pfn++) { | |
875 | struct page *cursor_page; | |
876 | ||
877 | /* The target page is in the block, ignore it. */ | |
878 | if (unlikely(pfn == page_pfn)) | |
879 | continue; | |
880 | ||
881 | /* Avoid holes within the zone. */ | |
882 | if (unlikely(!pfn_valid_within(pfn))) | |
883 | break; | |
884 | ||
885 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 886 | |
5ad333eb AW |
887 | /* Check that we have not crossed a zone boundary. */ |
888 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
889 | continue; | |
4f98a2fe | 890 | switch (__isolate_lru_page(cursor_page, mode, file)) { |
5ad333eb AW |
891 | case 0: |
892 | list_move(&cursor_page->lru, dst); | |
893 | nr_taken++; | |
894 | scan++; | |
895 | break; | |
896 | ||
897 | case -EBUSY: | |
898 | /* else it is being freed elsewhere */ | |
899 | list_move(&cursor_page->lru, src); | |
900 | default: | |
894bc310 | 901 | break; /* ! on LRU or wrong list */ |
5ad333eb AW |
902 | } |
903 | } | |
1da177e4 LT |
904 | } |
905 | ||
906 | *scanned = scan; | |
907 | return nr_taken; | |
908 | } | |
909 | ||
66e1707b BS |
910 | static unsigned long isolate_pages_global(unsigned long nr, |
911 | struct list_head *dst, | |
912 | unsigned long *scanned, int order, | |
913 | int mode, struct zone *z, | |
914 | struct mem_cgroup *mem_cont, | |
4f98a2fe | 915 | int active, int file) |
66e1707b | 916 | { |
4f98a2fe | 917 | int lru = LRU_BASE; |
66e1707b | 918 | if (active) |
4f98a2fe RR |
919 | lru += LRU_ACTIVE; |
920 | if (file) | |
921 | lru += LRU_FILE; | |
922 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
923 | mode, !!file); | |
66e1707b BS |
924 | } |
925 | ||
5ad333eb AW |
926 | /* |
927 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
928 | * any active bits from the pages in the list. | |
929 | */ | |
4f98a2fe RR |
930 | static unsigned long clear_active_flags(struct list_head *page_list, |
931 | unsigned int *count) | |
5ad333eb AW |
932 | { |
933 | int nr_active = 0; | |
4f98a2fe | 934 | int lru; |
5ad333eb AW |
935 | struct page *page; |
936 | ||
4f98a2fe RR |
937 | list_for_each_entry(page, page_list, lru) { |
938 | lru = page_is_file_cache(page); | |
5ad333eb | 939 | if (PageActive(page)) { |
4f98a2fe | 940 | lru += LRU_ACTIVE; |
5ad333eb AW |
941 | ClearPageActive(page); |
942 | nr_active++; | |
943 | } | |
4f98a2fe RR |
944 | count[lru]++; |
945 | } | |
5ad333eb AW |
946 | |
947 | return nr_active; | |
948 | } | |
949 | ||
62695a84 NP |
950 | /** |
951 | * isolate_lru_page - tries to isolate a page from its LRU list | |
952 | * @page: page to isolate from its LRU list | |
953 | * | |
954 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
955 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
956 | * | |
957 | * Returns 0 if the page was removed from an LRU list. | |
958 | * Returns -EBUSY if the page was not on an LRU list. | |
959 | * | |
960 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
961 | * the active list, it will have PageActive set. If it was found on |
962 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
963 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
964 | * |
965 | * The vmstat statistic corresponding to the list on which the page was | |
966 | * found will be decremented. | |
967 | * | |
968 | * Restrictions: | |
969 | * (1) Must be called with an elevated refcount on the page. This is a | |
970 | * fundamentnal difference from isolate_lru_pages (which is called | |
971 | * without a stable reference). | |
972 | * (2) the lru_lock must not be held. | |
973 | * (3) interrupts must be enabled. | |
974 | */ | |
975 | int isolate_lru_page(struct page *page) | |
976 | { | |
977 | int ret = -EBUSY; | |
978 | ||
979 | if (PageLRU(page)) { | |
980 | struct zone *zone = page_zone(page); | |
981 | ||
982 | spin_lock_irq(&zone->lru_lock); | |
983 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 984 | int lru = page_lru(page); |
62695a84 NP |
985 | ret = 0; |
986 | ClearPageLRU(page); | |
4f98a2fe | 987 | |
4f98a2fe | 988 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
989 | } |
990 | spin_unlock_irq(&zone->lru_lock); | |
991 | } | |
992 | return ret; | |
993 | } | |
994 | ||
1da177e4 | 995 | /* |
1742f19f AM |
996 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
997 | * of reclaimed pages | |
1da177e4 | 998 | */ |
1742f19f | 999 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
33c120ed RR |
1000 | struct zone *zone, struct scan_control *sc, |
1001 | int priority, int file) | |
1da177e4 LT |
1002 | { |
1003 | LIST_HEAD(page_list); | |
1004 | struct pagevec pvec; | |
69e05944 | 1005 | unsigned long nr_scanned = 0; |
05ff5137 | 1006 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
1007 | |
1008 | pagevec_init(&pvec, 1); | |
1009 | ||
1010 | lru_add_drain(); | |
1011 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 1012 | do { |
1da177e4 | 1013 | struct page *page; |
69e05944 AM |
1014 | unsigned long nr_taken; |
1015 | unsigned long nr_scan; | |
1016 | unsigned long nr_freed; | |
5ad333eb | 1017 | unsigned long nr_active; |
4f98a2fe | 1018 | unsigned int count[NR_LRU_LISTS] = { 0, }; |
33c120ed RR |
1019 | int mode = ISOLATE_INACTIVE; |
1020 | ||
1021 | /* | |
1022 | * If we need a large contiguous chunk of memory, or have | |
1023 | * trouble getting a small set of contiguous pages, we | |
1024 | * will reclaim both active and inactive pages. | |
1025 | * | |
1026 | * We use the same threshold as pageout congestion_wait below. | |
1027 | */ | |
1028 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1029 | mode = ISOLATE_BOTH; | |
1030 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1031 | mode = ISOLATE_BOTH; | |
1da177e4 | 1032 | |
66e1707b | 1033 | nr_taken = sc->isolate_pages(sc->swap_cluster_max, |
4f98a2fe RR |
1034 | &page_list, &nr_scan, sc->order, mode, |
1035 | zone, sc->mem_cgroup, 0, file); | |
1036 | nr_active = clear_active_flags(&page_list, count); | |
e9187bdc | 1037 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb | 1038 | |
4f98a2fe RR |
1039 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1040 | -count[LRU_ACTIVE_FILE]); | |
1041 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1042 | -count[LRU_INACTIVE_FILE]); | |
1043 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1044 | -count[LRU_ACTIVE_ANON]); | |
1045 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1046 | -count[LRU_INACTIVE_ANON]); | |
1047 | ||
1048 | if (scan_global_lru(sc)) { | |
1cfb419b | 1049 | zone->pages_scanned += nr_scan; |
4f98a2fe RR |
1050 | zone->recent_scanned[0] += count[LRU_INACTIVE_ANON]; |
1051 | zone->recent_scanned[0] += count[LRU_ACTIVE_ANON]; | |
1052 | zone->recent_scanned[1] += count[LRU_INACTIVE_FILE]; | |
1053 | zone->recent_scanned[1] += count[LRU_ACTIVE_FILE]; | |
1054 | } | |
1da177e4 LT |
1055 | spin_unlock_irq(&zone->lru_lock); |
1056 | ||
69e05944 | 1057 | nr_scanned += nr_scan; |
c661b078 AW |
1058 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
1059 | ||
1060 | /* | |
1061 | * If we are direct reclaiming for contiguous pages and we do | |
1062 | * not reclaim everything in the list, try again and wait | |
1063 | * for IO to complete. This will stall high-order allocations | |
1064 | * but that should be acceptable to the caller | |
1065 | */ | |
1066 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
1067 | sc->order > PAGE_ALLOC_COSTLY_ORDER) { | |
1068 | congestion_wait(WRITE, HZ/10); | |
1069 | ||
1070 | /* | |
1071 | * The attempt at page out may have made some | |
1072 | * of the pages active, mark them inactive again. | |
1073 | */ | |
4f98a2fe | 1074 | nr_active = clear_active_flags(&page_list, count); |
c661b078 AW |
1075 | count_vm_events(PGDEACTIVATE, nr_active); |
1076 | ||
1077 | nr_freed += shrink_page_list(&page_list, sc, | |
1078 | PAGEOUT_IO_SYNC); | |
1079 | } | |
1080 | ||
05ff5137 | 1081 | nr_reclaimed += nr_freed; |
a74609fa NP |
1082 | local_irq_disable(); |
1083 | if (current_is_kswapd()) { | |
f8891e5e CL |
1084 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
1085 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
1cfb419b | 1086 | } else if (scan_global_lru(sc)) |
f8891e5e | 1087 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
1cfb419b | 1088 | |
918d3f90 | 1089 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa | 1090 | |
fb8d14e1 WF |
1091 | if (nr_taken == 0) |
1092 | goto done; | |
1093 | ||
a74609fa | 1094 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
1095 | /* |
1096 | * Put back any unfreeable pages. | |
1097 | */ | |
1098 | while (!list_empty(&page_list)) { | |
894bc310 | 1099 | int lru; |
1da177e4 | 1100 | page = lru_to_page(&page_list); |
725d704e | 1101 | VM_BUG_ON(PageLRU(page)); |
1da177e4 | 1102 | list_del(&page->lru); |
894bc310 LS |
1103 | if (unlikely(!page_evictable(page, NULL))) { |
1104 | spin_unlock_irq(&zone->lru_lock); | |
1105 | putback_lru_page(page); | |
1106 | spin_lock_irq(&zone->lru_lock); | |
1107 | continue; | |
1108 | } | |
1109 | SetPageLRU(page); | |
1110 | lru = page_lru(page); | |
1111 | add_page_to_lru_list(zone, page, lru); | |
1112 | mem_cgroup_move_lists(page, lru); | |
4f98a2fe RR |
1113 | if (PageActive(page) && scan_global_lru(sc)) { |
1114 | int file = !!page_is_file_cache(page); | |
1115 | zone->recent_rotated[file]++; | |
1116 | } | |
1da177e4 LT |
1117 | if (!pagevec_add(&pvec, page)) { |
1118 | spin_unlock_irq(&zone->lru_lock); | |
1119 | __pagevec_release(&pvec); | |
1120 | spin_lock_irq(&zone->lru_lock); | |
1121 | } | |
1122 | } | |
69e05944 | 1123 | } while (nr_scanned < max_scan); |
fb8d14e1 | 1124 | spin_unlock(&zone->lru_lock); |
1da177e4 | 1125 | done: |
fb8d14e1 | 1126 | local_irq_enable(); |
1da177e4 | 1127 | pagevec_release(&pvec); |
05ff5137 | 1128 | return nr_reclaimed; |
1da177e4 LT |
1129 | } |
1130 | ||
3bb1a852 MB |
1131 | /* |
1132 | * We are about to scan this zone at a certain priority level. If that priority | |
1133 | * level is smaller (ie: more urgent) than the previous priority, then note | |
1134 | * that priority level within the zone. This is done so that when the next | |
1135 | * process comes in to scan this zone, it will immediately start out at this | |
1136 | * priority level rather than having to build up its own scanning priority. | |
1137 | * Here, this priority affects only the reclaim-mapped threshold. | |
1138 | */ | |
1139 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
1140 | { | |
1141 | if (priority < zone->prev_priority) | |
1142 | zone->prev_priority = priority; | |
1143 | } | |
1144 | ||
4ff1ffb4 NP |
1145 | static inline int zone_is_near_oom(struct zone *zone) |
1146 | { | |
4f98a2fe | 1147 | return zone->pages_scanned >= (zone_lru_pages(zone) * 3); |
1cfb419b KH |
1148 | } |
1149 | ||
1da177e4 LT |
1150 | /* |
1151 | * This moves pages from the active list to the inactive list. | |
1152 | * | |
1153 | * We move them the other way if the page is referenced by one or more | |
1154 | * processes, from rmap. | |
1155 | * | |
1156 | * If the pages are mostly unmapped, the processing is fast and it is | |
1157 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1158 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1159 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1160 | * this, so instead we remove the pages from the LRU while processing them. | |
1161 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1162 | * nobody will play with that bit on a non-LRU page. | |
1163 | * | |
1164 | * The downside is that we have to touch page->_count against each page. | |
1165 | * But we had to alter page->flags anyway. | |
1166 | */ | |
1cfb419b KH |
1167 | |
1168 | ||
1742f19f | 1169 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1170 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1171 | { |
69e05944 | 1172 | unsigned long pgmoved; |
1da177e4 | 1173 | int pgdeactivate = 0; |
69e05944 | 1174 | unsigned long pgscanned; |
1da177e4 | 1175 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
b69408e8 | 1176 | LIST_HEAD(l_inactive); |
1da177e4 LT |
1177 | struct page *page; |
1178 | struct pagevec pvec; | |
4f98a2fe | 1179 | enum lru_list lru; |
1da177e4 LT |
1180 | |
1181 | lru_add_drain(); | |
1182 | spin_lock_irq(&zone->lru_lock); | |
66e1707b BS |
1183 | pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, |
1184 | ISOLATE_ACTIVE, zone, | |
4f98a2fe | 1185 | sc->mem_cgroup, 1, file); |
1cfb419b KH |
1186 | /* |
1187 | * zone->pages_scanned is used for detect zone's oom | |
1188 | * mem_cgroup remembers nr_scan by itself. | |
1189 | */ | |
4f98a2fe | 1190 | if (scan_global_lru(sc)) { |
1cfb419b | 1191 | zone->pages_scanned += pgscanned; |
4f98a2fe RR |
1192 | zone->recent_scanned[!!file] += pgmoved; |
1193 | } | |
1cfb419b | 1194 | |
4f98a2fe RR |
1195 | if (file) |
1196 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved); | |
1197 | else | |
1198 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved); | |
1da177e4 LT |
1199 | spin_unlock_irq(&zone->lru_lock); |
1200 | ||
556adecb | 1201 | pgmoved = 0; |
1da177e4 LT |
1202 | while (!list_empty(&l_hold)) { |
1203 | cond_resched(); | |
1204 | page = lru_to_page(&l_hold); | |
1205 | list_del(&page->lru); | |
7e9cd484 | 1206 | |
894bc310 LS |
1207 | if (unlikely(!page_evictable(page, NULL))) { |
1208 | putback_lru_page(page); | |
1209 | continue; | |
1210 | } | |
1211 | ||
7e9cd484 RR |
1212 | /* page_referenced clears PageReferenced */ |
1213 | if (page_mapping_inuse(page) && | |
1214 | page_referenced(page, 0, sc->mem_cgroup)) | |
1215 | pgmoved++; | |
1216 | ||
1da177e4 LT |
1217 | list_add(&page->lru, &l_inactive); |
1218 | } | |
1219 | ||
556adecb | 1220 | /* |
7e9cd484 RR |
1221 | * Count referenced pages from currently used mappings as |
1222 | * rotated, even though they are moved to the inactive list. | |
1223 | * This helps balance scan pressure between file and anonymous | |
1224 | * pages in get_scan_ratio. | |
1225 | */ | |
556adecb RR |
1226 | zone->recent_rotated[!!file] += pgmoved; |
1227 | ||
4f98a2fe | 1228 | /* |
7e9cd484 | 1229 | * Move the pages to the [file or anon] inactive list. |
4f98a2fe | 1230 | */ |
1da177e4 | 1231 | pagevec_init(&pvec, 1); |
7e9cd484 | 1232 | |
1da177e4 | 1233 | pgmoved = 0; |
4f98a2fe | 1234 | lru = LRU_BASE + file * LRU_FILE; |
1da177e4 LT |
1235 | spin_lock_irq(&zone->lru_lock); |
1236 | while (!list_empty(&l_inactive)) { | |
1237 | page = lru_to_page(&l_inactive); | |
1238 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 1239 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1240 | SetPageLRU(page); |
725d704e | 1241 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
1242 | ClearPageActive(page); |
1243 | ||
4f98a2fe | 1244 | list_move(&page->lru, &zone->lru[lru].list); |
894bc310 | 1245 | mem_cgroup_move_lists(page, lru); |
1da177e4 LT |
1246 | pgmoved++; |
1247 | if (!pagevec_add(&pvec, page)) { | |
4f98a2fe | 1248 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1249 | spin_unlock_irq(&zone->lru_lock); |
1250 | pgdeactivate += pgmoved; | |
1251 | pgmoved = 0; | |
1252 | if (buffer_heads_over_limit) | |
1253 | pagevec_strip(&pvec); | |
1254 | __pagevec_release(&pvec); | |
1255 | spin_lock_irq(&zone->lru_lock); | |
1256 | } | |
1257 | } | |
4f98a2fe | 1258 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1da177e4 LT |
1259 | pgdeactivate += pgmoved; |
1260 | if (buffer_heads_over_limit) { | |
1261 | spin_unlock_irq(&zone->lru_lock); | |
1262 | pagevec_strip(&pvec); | |
1263 | spin_lock_irq(&zone->lru_lock); | |
1264 | } | |
f8891e5e CL |
1265 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1266 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
1267 | spin_unlock_irq(&zone->lru_lock); | |
68a22394 RR |
1268 | if (vm_swap_full()) |
1269 | pagevec_swap_free(&pvec); | |
1da177e4 | 1270 | |
a74609fa | 1271 | pagevec_release(&pvec); |
1da177e4 LT |
1272 | } |
1273 | ||
4f98a2fe | 1274 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1275 | struct zone *zone, struct scan_control *sc, int priority) |
1276 | { | |
4f98a2fe RR |
1277 | int file = is_file_lru(lru); |
1278 | ||
556adecb RR |
1279 | if (lru == LRU_ACTIVE_FILE) { |
1280 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
1281 | return 0; | |
1282 | } | |
1283 | ||
1284 | if (lru == LRU_ACTIVE_ANON && | |
1285 | (!scan_global_lru(sc) || inactive_anon_is_low(zone))) { | |
4f98a2fe | 1286 | shrink_active_list(nr_to_scan, zone, sc, priority, file); |
b69408e8 CL |
1287 | return 0; |
1288 | } | |
33c120ed | 1289 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1290 | } |
1291 | ||
1292 | /* | |
1293 | * Determine how aggressively the anon and file LRU lists should be | |
1294 | * scanned. The relative value of each set of LRU lists is determined | |
1295 | * by looking at the fraction of the pages scanned we did rotate back | |
1296 | * onto the active list instead of evict. | |
1297 | * | |
1298 | * percent[0] specifies how much pressure to put on ram/swap backed | |
1299 | * memory, while percent[1] determines pressure on the file LRUs. | |
1300 | */ | |
1301 | static void get_scan_ratio(struct zone *zone, struct scan_control *sc, | |
1302 | unsigned long *percent) | |
1303 | { | |
1304 | unsigned long anon, file, free; | |
1305 | unsigned long anon_prio, file_prio; | |
1306 | unsigned long ap, fp; | |
1307 | ||
1308 | anon = zone_page_state(zone, NR_ACTIVE_ANON) + | |
1309 | zone_page_state(zone, NR_INACTIVE_ANON); | |
1310 | file = zone_page_state(zone, NR_ACTIVE_FILE) + | |
1311 | zone_page_state(zone, NR_INACTIVE_FILE); | |
1312 | free = zone_page_state(zone, NR_FREE_PAGES); | |
1313 | ||
1314 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1315 | if (nr_swap_pages <= 0) { | |
1316 | percent[0] = 0; | |
1317 | percent[1] = 100; | |
1318 | return; | |
1319 | } | |
1320 | ||
1321 | /* If we have very few page cache pages, force-scan anon pages. */ | |
1322 | if (unlikely(file + free <= zone->pages_high)) { | |
1323 | percent[0] = 100; | |
1324 | percent[1] = 0; | |
1325 | return; | |
1326 | } | |
1327 | ||
1328 | /* | |
1329 | * OK, so we have swap space and a fair amount of page cache | |
1330 | * pages. We use the recently rotated / recently scanned | |
1331 | * ratios to determine how valuable each cache is. | |
1332 | * | |
1333 | * Because workloads change over time (and to avoid overflow) | |
1334 | * we keep these statistics as a floating average, which ends | |
1335 | * up weighing recent references more than old ones. | |
1336 | * | |
1337 | * anon in [0], file in [1] | |
1338 | */ | |
1339 | if (unlikely(zone->recent_scanned[0] > anon / 4)) { | |
1340 | spin_lock_irq(&zone->lru_lock); | |
1341 | zone->recent_scanned[0] /= 2; | |
1342 | zone->recent_rotated[0] /= 2; | |
1343 | spin_unlock_irq(&zone->lru_lock); | |
1344 | } | |
1345 | ||
1346 | if (unlikely(zone->recent_scanned[1] > file / 4)) { | |
1347 | spin_lock_irq(&zone->lru_lock); | |
1348 | zone->recent_scanned[1] /= 2; | |
1349 | zone->recent_rotated[1] /= 2; | |
1350 | spin_unlock_irq(&zone->lru_lock); | |
1351 | } | |
1352 | ||
1353 | /* | |
1354 | * With swappiness at 100, anonymous and file have the same priority. | |
1355 | * This scanning priority is essentially the inverse of IO cost. | |
1356 | */ | |
1357 | anon_prio = sc->swappiness; | |
1358 | file_prio = 200 - sc->swappiness; | |
1359 | ||
1360 | /* | |
1361 | * anon recent_rotated[0] | |
1362 | * %anon = 100 * ----------- / ----------------- * IO cost | |
1363 | * anon + file rotate_sum | |
1364 | */ | |
1365 | ap = (anon_prio + 1) * (zone->recent_scanned[0] + 1); | |
1366 | ap /= zone->recent_rotated[0] + 1; | |
1367 | ||
1368 | fp = (file_prio + 1) * (zone->recent_scanned[1] + 1); | |
1369 | fp /= zone->recent_rotated[1] + 1; | |
1370 | ||
1371 | /* Normalize to percentages */ | |
1372 | percent[0] = 100 * ap / (ap + fp + 1); | |
1373 | percent[1] = 100 - percent[0]; | |
b69408e8 CL |
1374 | } |
1375 | ||
4f98a2fe | 1376 | |
1da177e4 LT |
1377 | /* |
1378 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1379 | */ | |
05ff5137 AM |
1380 | static unsigned long shrink_zone(int priority, struct zone *zone, |
1381 | struct scan_control *sc) | |
1da177e4 | 1382 | { |
b69408e8 | 1383 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1384 | unsigned long nr_to_scan; |
05ff5137 | 1385 | unsigned long nr_reclaimed = 0; |
4f98a2fe | 1386 | unsigned long percent[2]; /* anon @ 0; file @ 1 */ |
b69408e8 | 1387 | enum lru_list l; |
1da177e4 | 1388 | |
4f98a2fe RR |
1389 | get_scan_ratio(zone, sc, percent); |
1390 | ||
894bc310 | 1391 | for_each_evictable_lru(l) { |
4f98a2fe RR |
1392 | if (scan_global_lru(sc)) { |
1393 | int file = is_file_lru(l); | |
1394 | int scan; | |
1395 | /* | |
1396 | * Add one to nr_to_scan just to make sure that the | |
1397 | * kernel will slowly sift through each list. | |
1398 | */ | |
1399 | scan = zone_page_state(zone, NR_LRU_BASE + l); | |
1400 | if (priority) { | |
1401 | scan >>= priority; | |
1402 | scan = (scan * percent[file]) / 100; | |
1403 | } | |
1404 | zone->lru[l].nr_scan += scan + 1; | |
b69408e8 CL |
1405 | nr[l] = zone->lru[l].nr_scan; |
1406 | if (nr[l] >= sc->swap_cluster_max) | |
1407 | zone->lru[l].nr_scan = 0; | |
1408 | else | |
1409 | nr[l] = 0; | |
4f98a2fe RR |
1410 | } else { |
1411 | /* | |
1412 | * This reclaim occurs not because zone memory shortage | |
1413 | * but because memory controller hits its limit. | |
1414 | * Don't modify zone reclaim related data. | |
1415 | */ | |
1416 | nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone, | |
1417 | priority, l); | |
b69408e8 | 1418 | } |
1cfb419b | 1419 | } |
1da177e4 | 1420 | |
556adecb RR |
1421 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1422 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1423 | for_each_evictable_lru(l) { |
b69408e8 CL |
1424 | if (nr[l]) { |
1425 | nr_to_scan = min(nr[l], | |
1da177e4 | 1426 | (unsigned long)sc->swap_cluster_max); |
b69408e8 | 1427 | nr[l] -= nr_to_scan; |
1da177e4 | 1428 | |
b69408e8 CL |
1429 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1430 | zone, sc, priority); | |
1431 | } | |
1da177e4 LT |
1432 | } |
1433 | } | |
1434 | ||
556adecb RR |
1435 | /* |
1436 | * Even if we did not try to evict anon pages at all, we want to | |
1437 | * rebalance the anon lru active/inactive ratio. | |
1438 | */ | |
1439 | if (!scan_global_lru(sc) || inactive_anon_is_low(zone)) | |
1440 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); | |
1441 | else if (!scan_global_lru(sc)) | |
1442 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); | |
1443 | ||
232ea4d6 | 1444 | throttle_vm_writeout(sc->gfp_mask); |
05ff5137 | 1445 | return nr_reclaimed; |
1da177e4 LT |
1446 | } |
1447 | ||
1448 | /* | |
1449 | * This is the direct reclaim path, for page-allocating processes. We only | |
1450 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1451 | * request. | |
1452 | * | |
1453 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
1454 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
1455 | * allocation or | |
1456 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
1457 | * satisfy the `incremental min' zone defense algorithm. | |
1458 | * | |
1459 | * Returns the number of reclaimed pages. | |
1460 | * | |
1461 | * If a zone is deemed to be full of pinned pages then just give it a light | |
1462 | * scan then give up on it. | |
1463 | */ | |
dac1d27b | 1464 | static unsigned long shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1465 | struct scan_control *sc) |
1da177e4 | 1466 | { |
54a6eb5c | 1467 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
05ff5137 | 1468 | unsigned long nr_reclaimed = 0; |
dd1a239f | 1469 | struct zoneref *z; |
54a6eb5c | 1470 | struct zone *zone; |
1cfb419b | 1471 | |
408d8544 | 1472 | sc->all_unreclaimable = 1; |
54a6eb5c | 1473 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
f3fe6512 | 1474 | if (!populated_zone(zone)) |
1da177e4 | 1475 | continue; |
1cfb419b KH |
1476 | /* |
1477 | * Take care memory controller reclaiming has small influence | |
1478 | * to global LRU. | |
1479 | */ | |
1480 | if (scan_global_lru(sc)) { | |
1481 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1482 | continue; | |
1483 | note_zone_scanning_priority(zone, priority); | |
1da177e4 | 1484 | |
1cfb419b KH |
1485 | if (zone_is_all_unreclaimable(zone) && |
1486 | priority != DEF_PRIORITY) | |
1487 | continue; /* Let kswapd poll it */ | |
1488 | sc->all_unreclaimable = 0; | |
1489 | } else { | |
1490 | /* | |
1491 | * Ignore cpuset limitation here. We just want to reduce | |
1492 | * # of used pages by us regardless of memory shortage. | |
1493 | */ | |
1494 | sc->all_unreclaimable = 0; | |
1495 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, | |
1496 | priority); | |
1497 | } | |
408d8544 | 1498 | |
05ff5137 | 1499 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 1500 | } |
1cfb419b | 1501 | |
05ff5137 | 1502 | return nr_reclaimed; |
1da177e4 | 1503 | } |
4f98a2fe | 1504 | |
1da177e4 LT |
1505 | /* |
1506 | * This is the main entry point to direct page reclaim. | |
1507 | * | |
1508 | * If a full scan of the inactive list fails to free enough memory then we | |
1509 | * are "out of memory" and something needs to be killed. | |
1510 | * | |
1511 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1512 | * high - the zone may be full of dirty or under-writeback pages, which this | |
1513 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
1514 | * hope that some of these pages can be written. But if the allocating task | |
1515 | * holds filesystem locks which prevent writeout this might not work, and the | |
1516 | * allocation attempt will fail. | |
a41f24ea NA |
1517 | * |
1518 | * returns: 0, if no pages reclaimed | |
1519 | * else, the number of pages reclaimed | |
1da177e4 | 1520 | */ |
dac1d27b | 1521 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1522 | struct scan_control *sc) |
1da177e4 LT |
1523 | { |
1524 | int priority; | |
c700be3d | 1525 | unsigned long ret = 0; |
69e05944 | 1526 | unsigned long total_scanned = 0; |
05ff5137 | 1527 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1528 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 | 1529 | unsigned long lru_pages = 0; |
dd1a239f | 1530 | struct zoneref *z; |
54a6eb5c | 1531 | struct zone *zone; |
dd1a239f | 1532 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
1da177e4 | 1533 | |
873b4771 KK |
1534 | delayacct_freepages_start(); |
1535 | ||
1cfb419b KH |
1536 | if (scan_global_lru(sc)) |
1537 | count_vm_event(ALLOCSTALL); | |
1538 | /* | |
1539 | * mem_cgroup will not do shrink_slab. | |
1540 | */ | |
1541 | if (scan_global_lru(sc)) { | |
54a6eb5c | 1542 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1da177e4 | 1543 | |
1cfb419b KH |
1544 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1545 | continue; | |
1da177e4 | 1546 | |
4f98a2fe | 1547 | lru_pages += zone_lru_pages(zone); |
1cfb419b | 1548 | } |
1da177e4 LT |
1549 | } |
1550 | ||
1551 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1552 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1553 | if (!priority) |
1554 | disable_swap_token(); | |
dac1d27b | 1555 | nr_reclaimed += shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1556 | /* |
1557 | * Don't shrink slabs when reclaiming memory from | |
1558 | * over limit cgroups | |
1559 | */ | |
91a45470 | 1560 | if (scan_global_lru(sc)) { |
dd1a239f | 1561 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 KH |
1562 | if (reclaim_state) { |
1563 | nr_reclaimed += reclaim_state->reclaimed_slab; | |
1564 | reclaim_state->reclaimed_slab = 0; | |
1565 | } | |
1da177e4 | 1566 | } |
66e1707b BS |
1567 | total_scanned += sc->nr_scanned; |
1568 | if (nr_reclaimed >= sc->swap_cluster_max) { | |
a41f24ea | 1569 | ret = nr_reclaimed; |
1da177e4 LT |
1570 | goto out; |
1571 | } | |
1572 | ||
1573 | /* | |
1574 | * Try to write back as many pages as we just scanned. This | |
1575 | * tends to cause slow streaming writers to write data to the | |
1576 | * disk smoothly, at the dirtying rate, which is nice. But | |
1577 | * that's undesirable in laptop mode, where we *want* lumpy | |
1578 | * writeout. So in laptop mode, write out the whole world. | |
1579 | */ | |
66e1707b BS |
1580 | if (total_scanned > sc->swap_cluster_max + |
1581 | sc->swap_cluster_max / 2) { | |
687a21ce | 1582 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
66e1707b | 1583 | sc->may_writepage = 1; |
1da177e4 LT |
1584 | } |
1585 | ||
1586 | /* Take a nap, wait for some writeback to complete */ | |
4dd4b920 | 1587 | if (sc->nr_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1588 | congestion_wait(WRITE, HZ/10); |
1da177e4 | 1589 | } |
87547ee9 | 1590 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
91a45470 | 1591 | if (!sc->all_unreclaimable && scan_global_lru(sc)) |
a41f24ea | 1592 | ret = nr_reclaimed; |
1da177e4 | 1593 | out: |
3bb1a852 MB |
1594 | /* |
1595 | * Now that we've scanned all the zones at this priority level, note | |
1596 | * that level within the zone so that the next thread which performs | |
1597 | * scanning of this zone will immediately start out at this priority | |
1598 | * level. This affects only the decision whether or not to bring | |
1599 | * mapped pages onto the inactive list. | |
1600 | */ | |
1601 | if (priority < 0) | |
1602 | priority = 0; | |
1da177e4 | 1603 | |
1cfb419b | 1604 | if (scan_global_lru(sc)) { |
54a6eb5c | 1605 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1cfb419b KH |
1606 | |
1607 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1608 | continue; | |
1609 | ||
1610 | zone->prev_priority = priority; | |
1611 | } | |
1612 | } else | |
1613 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); | |
1da177e4 | 1614 | |
873b4771 KK |
1615 | delayacct_freepages_end(); |
1616 | ||
1da177e4 LT |
1617 | return ret; |
1618 | } | |
1619 | ||
dac1d27b MG |
1620 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
1621 | gfp_t gfp_mask) | |
66e1707b BS |
1622 | { |
1623 | struct scan_control sc = { | |
1624 | .gfp_mask = gfp_mask, | |
1625 | .may_writepage = !laptop_mode, | |
1626 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1627 | .may_swap = 1, | |
1628 | .swappiness = vm_swappiness, | |
1629 | .order = order, | |
1630 | .mem_cgroup = NULL, | |
1631 | .isolate_pages = isolate_pages_global, | |
1632 | }; | |
1633 | ||
dd1a239f | 1634 | return do_try_to_free_pages(zonelist, &sc); |
66e1707b BS |
1635 | } |
1636 | ||
00f0b825 | 1637 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1638 | |
e1a1cd59 BS |
1639 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
1640 | gfp_t gfp_mask) | |
66e1707b BS |
1641 | { |
1642 | struct scan_control sc = { | |
66e1707b BS |
1643 | .may_writepage = !laptop_mode, |
1644 | .may_swap = 1, | |
1645 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1646 | .swappiness = vm_swappiness, | |
1647 | .order = 0, | |
1648 | .mem_cgroup = mem_cont, | |
1649 | .isolate_pages = mem_cgroup_isolate_pages, | |
1650 | }; | |
dac1d27b | 1651 | struct zonelist *zonelist; |
66e1707b | 1652 | |
dd1a239f MG |
1653 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1654 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1655 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1656 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1657 | } |
1658 | #endif | |
1659 | ||
1da177e4 LT |
1660 | /* |
1661 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1662 | * they are all at pages_high. | |
1663 | * | |
1da177e4 LT |
1664 | * Returns the number of pages which were actually freed. |
1665 | * | |
1666 | * There is special handling here for zones which are full of pinned pages. | |
1667 | * This can happen if the pages are all mlocked, or if they are all used by | |
1668 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1669 | * What we do is to detect the case where all pages in the zone have been | |
1670 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1671 | * dead and from now on, only perform a short scan. Basically we're polling | |
1672 | * the zone for when the problem goes away. | |
1673 | * | |
1674 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1675 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1676 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1677 | * of the number of free pages in the lower zones. This interoperates with | |
1678 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1679 | * across the zones. | |
1680 | */ | |
d6277db4 | 1681 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1682 | { |
1da177e4 LT |
1683 | int all_zones_ok; |
1684 | int priority; | |
1685 | int i; | |
69e05944 | 1686 | unsigned long total_scanned; |
05ff5137 | 1687 | unsigned long nr_reclaimed; |
1da177e4 | 1688 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1689 | struct scan_control sc = { |
1690 | .gfp_mask = GFP_KERNEL, | |
1691 | .may_swap = 1, | |
d6277db4 RW |
1692 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1693 | .swappiness = vm_swappiness, | |
5ad333eb | 1694 | .order = order, |
66e1707b BS |
1695 | .mem_cgroup = NULL, |
1696 | .isolate_pages = isolate_pages_global, | |
179e9639 | 1697 | }; |
3bb1a852 MB |
1698 | /* |
1699 | * temp_priority is used to remember the scanning priority at which | |
1700 | * this zone was successfully refilled to free_pages == pages_high. | |
1701 | */ | |
1702 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
1703 | |
1704 | loop_again: | |
1705 | total_scanned = 0; | |
05ff5137 | 1706 | nr_reclaimed = 0; |
c0bbbc73 | 1707 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1708 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 1709 | |
3bb1a852 MB |
1710 | for (i = 0; i < pgdat->nr_zones; i++) |
1711 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
1712 | |
1713 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1714 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1715 | unsigned long lru_pages = 0; | |
1716 | ||
f7b7fd8f RR |
1717 | /* The swap token gets in the way of swapout... */ |
1718 | if (!priority) | |
1719 | disable_swap_token(); | |
1720 | ||
1da177e4 LT |
1721 | all_zones_ok = 1; |
1722 | ||
d6277db4 RW |
1723 | /* |
1724 | * Scan in the highmem->dma direction for the highest | |
1725 | * zone which needs scanning | |
1726 | */ | |
1727 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1728 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1729 | |
d6277db4 RW |
1730 | if (!populated_zone(zone)) |
1731 | continue; | |
1da177e4 | 1732 | |
e815af95 DR |
1733 | if (zone_is_all_unreclaimable(zone) && |
1734 | priority != DEF_PRIORITY) | |
d6277db4 | 1735 | continue; |
1da177e4 | 1736 | |
556adecb RR |
1737 | /* |
1738 | * Do some background aging of the anon list, to give | |
1739 | * pages a chance to be referenced before reclaiming. | |
1740 | */ | |
1741 | if (inactive_anon_is_low(zone)) | |
1742 | shrink_active_list(SWAP_CLUSTER_MAX, zone, | |
1743 | &sc, priority, 0); | |
1744 | ||
d6277db4 RW |
1745 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1746 | 0, 0)) { | |
1747 | end_zone = i; | |
e1dbeda6 | 1748 | break; |
1da177e4 | 1749 | } |
1da177e4 | 1750 | } |
e1dbeda6 AM |
1751 | if (i < 0) |
1752 | goto out; | |
1753 | ||
1da177e4 LT |
1754 | for (i = 0; i <= end_zone; i++) { |
1755 | struct zone *zone = pgdat->node_zones + i; | |
1756 | ||
4f98a2fe | 1757 | lru_pages += zone_lru_pages(zone); |
1da177e4 LT |
1758 | } |
1759 | ||
1760 | /* | |
1761 | * Now scan the zone in the dma->highmem direction, stopping | |
1762 | * at the last zone which needs scanning. | |
1763 | * | |
1764 | * We do this because the page allocator works in the opposite | |
1765 | * direction. This prevents the page allocator from allocating | |
1766 | * pages behind kswapd's direction of progress, which would | |
1767 | * cause too much scanning of the lower zones. | |
1768 | */ | |
1769 | for (i = 0; i <= end_zone; i++) { | |
1770 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1771 | int nr_slab; |
1da177e4 | 1772 | |
f3fe6512 | 1773 | if (!populated_zone(zone)) |
1da177e4 LT |
1774 | continue; |
1775 | ||
e815af95 DR |
1776 | if (zone_is_all_unreclaimable(zone) && |
1777 | priority != DEF_PRIORITY) | |
1da177e4 LT |
1778 | continue; |
1779 | ||
d6277db4 RW |
1780 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1781 | end_zone, 0)) | |
1782 | all_zones_ok = 0; | |
3bb1a852 | 1783 | temp_priority[i] = priority; |
1da177e4 | 1784 | sc.nr_scanned = 0; |
3bb1a852 | 1785 | note_zone_scanning_priority(zone, priority); |
32a4330d RR |
1786 | /* |
1787 | * We put equal pressure on every zone, unless one | |
1788 | * zone has way too many pages free already. | |
1789 | */ | |
1790 | if (!zone_watermark_ok(zone, order, 8*zone->pages_high, | |
1791 | end_zone, 0)) | |
1792 | nr_reclaimed += shrink_zone(priority, zone, &sc); | |
1da177e4 | 1793 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1794 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1795 | lru_pages); | |
05ff5137 | 1796 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 1797 | total_scanned += sc.nr_scanned; |
e815af95 | 1798 | if (zone_is_all_unreclaimable(zone)) |
1da177e4 | 1799 | continue; |
b15e0905 | 1800 | if (nr_slab == 0 && zone->pages_scanned >= |
4f98a2fe | 1801 | (zone_lru_pages(zone) * 6)) |
e815af95 DR |
1802 | zone_set_flag(zone, |
1803 | ZONE_ALL_UNRECLAIMABLE); | |
1da177e4 LT |
1804 | /* |
1805 | * If we've done a decent amount of scanning and | |
1806 | * the reclaim ratio is low, start doing writepage | |
1807 | * even in laptop mode | |
1808 | */ | |
1809 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1810 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1811 | sc.may_writepage = 1; |
1812 | } | |
1da177e4 LT |
1813 | if (all_zones_ok) |
1814 | break; /* kswapd: all done */ | |
1815 | /* | |
1816 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1817 | * another pass across the zones. | |
1818 | */ | |
4dd4b920 | 1819 | if (total_scanned && priority < DEF_PRIORITY - 2) |
3fcfab16 | 1820 | congestion_wait(WRITE, HZ/10); |
1da177e4 LT |
1821 | |
1822 | /* | |
1823 | * We do this so kswapd doesn't build up large priorities for | |
1824 | * example when it is freeing in parallel with allocators. It | |
1825 | * matches the direct reclaim path behaviour in terms of impact | |
1826 | * on zone->*_priority. | |
1827 | */ | |
d6277db4 | 1828 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1829 | break; |
1830 | } | |
1831 | out: | |
3bb1a852 MB |
1832 | /* |
1833 | * Note within each zone the priority level at which this zone was | |
1834 | * brought into a happy state. So that the next thread which scans this | |
1835 | * zone will start out at that priority level. | |
1836 | */ | |
1da177e4 LT |
1837 | for (i = 0; i < pgdat->nr_zones; i++) { |
1838 | struct zone *zone = pgdat->node_zones + i; | |
1839 | ||
3bb1a852 | 1840 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
1841 | } |
1842 | if (!all_zones_ok) { | |
1843 | cond_resched(); | |
8357376d RW |
1844 | |
1845 | try_to_freeze(); | |
1846 | ||
1da177e4 LT |
1847 | goto loop_again; |
1848 | } | |
1849 | ||
05ff5137 | 1850 | return nr_reclaimed; |
1da177e4 LT |
1851 | } |
1852 | ||
1853 | /* | |
1854 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 1855 | * from the init process. |
1da177e4 LT |
1856 | * |
1857 | * This basically trickles out pages so that we have _some_ | |
1858 | * free memory available even if there is no other activity | |
1859 | * that frees anything up. This is needed for things like routing | |
1860 | * etc, where we otherwise might have all activity going on in | |
1861 | * asynchronous contexts that cannot page things out. | |
1862 | * | |
1863 | * If there are applications that are active memory-allocators | |
1864 | * (most normal use), this basically shouldn't matter. | |
1865 | */ | |
1866 | static int kswapd(void *p) | |
1867 | { | |
1868 | unsigned long order; | |
1869 | pg_data_t *pgdat = (pg_data_t*)p; | |
1870 | struct task_struct *tsk = current; | |
1871 | DEFINE_WAIT(wait); | |
1872 | struct reclaim_state reclaim_state = { | |
1873 | .reclaimed_slab = 0, | |
1874 | }; | |
c5f59f08 | 1875 | node_to_cpumask_ptr(cpumask, pgdat->node_id); |
1da177e4 | 1876 | |
c5f59f08 MT |
1877 | if (!cpus_empty(*cpumask)) |
1878 | set_cpus_allowed_ptr(tsk, cpumask); | |
1da177e4 LT |
1879 | current->reclaim_state = &reclaim_state; |
1880 | ||
1881 | /* | |
1882 | * Tell the memory management that we're a "memory allocator", | |
1883 | * and that if we need more memory we should get access to it | |
1884 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1885 | * never get caught in the normal page freeing logic. | |
1886 | * | |
1887 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1888 | * you need a small amount of memory in order to be able to | |
1889 | * page out something else, and this flag essentially protects | |
1890 | * us from recursively trying to free more memory as we're | |
1891 | * trying to free the first piece of memory in the first place). | |
1892 | */ | |
930d9152 | 1893 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 1894 | set_freezable(); |
1da177e4 LT |
1895 | |
1896 | order = 0; | |
1897 | for ( ; ; ) { | |
1898 | unsigned long new_order; | |
3e1d1d28 | 1899 | |
1da177e4 LT |
1900 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
1901 | new_order = pgdat->kswapd_max_order; | |
1902 | pgdat->kswapd_max_order = 0; | |
1903 | if (order < new_order) { | |
1904 | /* | |
1905 | * Don't sleep if someone wants a larger 'order' | |
1906 | * allocation | |
1907 | */ | |
1908 | order = new_order; | |
1909 | } else { | |
b1296cc4 RW |
1910 | if (!freezing(current)) |
1911 | schedule(); | |
1912 | ||
1da177e4 LT |
1913 | order = pgdat->kswapd_max_order; |
1914 | } | |
1915 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1916 | ||
b1296cc4 RW |
1917 | if (!try_to_freeze()) { |
1918 | /* We can speed up thawing tasks if we don't call | |
1919 | * balance_pgdat after returning from the refrigerator | |
1920 | */ | |
1921 | balance_pgdat(pgdat, order); | |
1922 | } | |
1da177e4 LT |
1923 | } |
1924 | return 0; | |
1925 | } | |
1926 | ||
1927 | /* | |
1928 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1929 | */ | |
1930 | void wakeup_kswapd(struct zone *zone, int order) | |
1931 | { | |
1932 | pg_data_t *pgdat; | |
1933 | ||
f3fe6512 | 1934 | if (!populated_zone(zone)) |
1da177e4 LT |
1935 | return; |
1936 | ||
1937 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1938 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1939 | return; |
1940 | if (pgdat->kswapd_max_order < order) | |
1941 | pgdat->kswapd_max_order = order; | |
02a0e53d | 1942 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 1943 | return; |
8d0986e2 | 1944 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1945 | return; |
8d0986e2 | 1946 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1947 | } |
1948 | ||
4f98a2fe RR |
1949 | unsigned long global_lru_pages(void) |
1950 | { | |
1951 | return global_page_state(NR_ACTIVE_ANON) | |
1952 | + global_page_state(NR_ACTIVE_FILE) | |
1953 | + global_page_state(NR_INACTIVE_ANON) | |
1954 | + global_page_state(NR_INACTIVE_FILE); | |
1955 | } | |
1956 | ||
1da177e4 LT |
1957 | #ifdef CONFIG_PM |
1958 | /* | |
d6277db4 RW |
1959 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1960 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1961 | * number of reclaimed pages | |
1962 | * | |
1963 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1964 | */ | |
e07aa05b NC |
1965 | static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, |
1966 | int pass, struct scan_control *sc) | |
d6277db4 RW |
1967 | { |
1968 | struct zone *zone; | |
1969 | unsigned long nr_to_scan, ret = 0; | |
b69408e8 | 1970 | enum lru_list l; |
d6277db4 RW |
1971 | |
1972 | for_each_zone(zone) { | |
1973 | ||
1974 | if (!populated_zone(zone)) | |
1975 | continue; | |
1976 | ||
e815af95 | 1977 | if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) |
d6277db4 RW |
1978 | continue; |
1979 | ||
894bc310 LS |
1980 | for_each_evictable_lru(l) { |
1981 | /* For pass = 0, we don't shrink the active list */ | |
4f98a2fe RR |
1982 | if (pass == 0 && |
1983 | (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE)) | |
b69408e8 CL |
1984 | continue; |
1985 | ||
1986 | zone->lru[l].nr_scan += | |
1987 | (zone_page_state(zone, NR_LRU_BASE + l) | |
1988 | >> prio) + 1; | |
1989 | if (zone->lru[l].nr_scan >= nr_pages || pass > 3) { | |
1990 | zone->lru[l].nr_scan = 0; | |
c8785385 | 1991 | nr_to_scan = min(nr_pages, |
b69408e8 CL |
1992 | zone_page_state(zone, |
1993 | NR_LRU_BASE + l)); | |
1994 | ret += shrink_list(l, nr_to_scan, zone, | |
1995 | sc, prio); | |
1996 | if (ret >= nr_pages) | |
1997 | return ret; | |
d6277db4 RW |
1998 | } |
1999 | } | |
d6277db4 RW |
2000 | } |
2001 | ||
2002 | return ret; | |
2003 | } | |
2004 | ||
2005 | /* | |
2006 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
2007 | * freed pages. | |
2008 | * | |
2009 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2010 | * LRU order by reclaiming preferentially | |
2011 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2012 | */ |
69e05944 | 2013 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 2014 | { |
d6277db4 | 2015 | unsigned long lru_pages, nr_slab; |
69e05944 | 2016 | unsigned long ret = 0; |
d6277db4 RW |
2017 | int pass; |
2018 | struct reclaim_state reclaim_state; | |
d6277db4 RW |
2019 | struct scan_control sc = { |
2020 | .gfp_mask = GFP_KERNEL, | |
2021 | .may_swap = 0, | |
2022 | .swap_cluster_max = nr_pages, | |
2023 | .may_writepage = 1, | |
2024 | .swappiness = vm_swappiness, | |
66e1707b | 2025 | .isolate_pages = isolate_pages_global, |
1da177e4 LT |
2026 | }; |
2027 | ||
2028 | current->reclaim_state = &reclaim_state; | |
69e05944 | 2029 | |
4f98a2fe | 2030 | lru_pages = global_lru_pages(); |
972d1a7b | 2031 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
2032 | /* If slab caches are huge, it's better to hit them first */ |
2033 | while (nr_slab >= lru_pages) { | |
2034 | reclaim_state.reclaimed_slab = 0; | |
2035 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
2036 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 2037 | break; |
d6277db4 RW |
2038 | |
2039 | ret += reclaim_state.reclaimed_slab; | |
2040 | if (ret >= nr_pages) | |
2041 | goto out; | |
2042 | ||
2043 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 2044 | } |
d6277db4 RW |
2045 | |
2046 | /* | |
2047 | * We try to shrink LRUs in 5 passes: | |
2048 | * 0 = Reclaim from inactive_list only | |
2049 | * 1 = Reclaim from active list but don't reclaim mapped | |
2050 | * 2 = 2nd pass of type 1 | |
2051 | * 3 = Reclaim mapped (normal reclaim) | |
2052 | * 4 = 2nd pass of type 3 | |
2053 | */ | |
2054 | for (pass = 0; pass < 5; pass++) { | |
2055 | int prio; | |
2056 | ||
d6277db4 RW |
2057 | /* Force reclaiming mapped pages in the passes #3 and #4 */ |
2058 | if (pass > 2) { | |
2059 | sc.may_swap = 1; | |
2060 | sc.swappiness = 100; | |
2061 | } | |
2062 | ||
2063 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
2064 | unsigned long nr_to_scan = nr_pages - ret; | |
2065 | ||
d6277db4 | 2066 | sc.nr_scanned = 0; |
d6277db4 RW |
2067 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
2068 | if (ret >= nr_pages) | |
2069 | goto out; | |
2070 | ||
2071 | reclaim_state.reclaimed_slab = 0; | |
76395d37 | 2072 | shrink_slab(sc.nr_scanned, sc.gfp_mask, |
4f98a2fe | 2073 | global_lru_pages()); |
d6277db4 RW |
2074 | ret += reclaim_state.reclaimed_slab; |
2075 | if (ret >= nr_pages) | |
2076 | goto out; | |
2077 | ||
2078 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
3fcfab16 | 2079 | congestion_wait(WRITE, HZ / 10); |
d6277db4 | 2080 | } |
248a0301 | 2081 | } |
d6277db4 RW |
2082 | |
2083 | /* | |
2084 | * If ret = 0, we could not shrink LRUs, but there may be something | |
2085 | * in slab caches | |
2086 | */ | |
76395d37 | 2087 | if (!ret) { |
d6277db4 RW |
2088 | do { |
2089 | reclaim_state.reclaimed_slab = 0; | |
4f98a2fe | 2090 | shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages()); |
d6277db4 RW |
2091 | ret += reclaim_state.reclaimed_slab; |
2092 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
76395d37 | 2093 | } |
d6277db4 RW |
2094 | |
2095 | out: | |
1da177e4 | 2096 | current->reclaim_state = NULL; |
d6277db4 | 2097 | |
1da177e4 LT |
2098 | return ret; |
2099 | } | |
2100 | #endif | |
2101 | ||
1da177e4 LT |
2102 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2103 | not required for correctness. So if the last cpu in a node goes | |
2104 | away, we get changed to run anywhere: as the first one comes back, | |
2105 | restore their cpu bindings. */ | |
9c7b216d | 2106 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2107 | unsigned long action, void *hcpu) |
1da177e4 | 2108 | { |
58c0a4a7 | 2109 | int nid; |
1da177e4 | 2110 | |
8bb78442 | 2111 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2112 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 MT |
2113 | pg_data_t *pgdat = NODE_DATA(nid); |
2114 | node_to_cpumask_ptr(mask, pgdat->node_id); | |
2115 | ||
2116 | if (any_online_cpu(*mask) < nr_cpu_ids) | |
1da177e4 | 2117 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2118 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2119 | } |
2120 | } | |
2121 | return NOTIFY_OK; | |
2122 | } | |
1da177e4 | 2123 | |
3218ae14 YG |
2124 | /* |
2125 | * This kswapd start function will be called by init and node-hot-add. | |
2126 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2127 | */ | |
2128 | int kswapd_run(int nid) | |
2129 | { | |
2130 | pg_data_t *pgdat = NODE_DATA(nid); | |
2131 | int ret = 0; | |
2132 | ||
2133 | if (pgdat->kswapd) | |
2134 | return 0; | |
2135 | ||
2136 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2137 | if (IS_ERR(pgdat->kswapd)) { | |
2138 | /* failure at boot is fatal */ | |
2139 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2140 | printk("Failed to start kswapd on node %d\n",nid); | |
2141 | ret = -1; | |
2142 | } | |
2143 | return ret; | |
2144 | } | |
2145 | ||
1da177e4 LT |
2146 | static int __init kswapd_init(void) |
2147 | { | |
3218ae14 | 2148 | int nid; |
69e05944 | 2149 | |
1da177e4 | 2150 | swap_setup(); |
9422ffba | 2151 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2152 | kswapd_run(nid); |
1da177e4 LT |
2153 | hotcpu_notifier(cpu_callback, 0); |
2154 | return 0; | |
2155 | } | |
2156 | ||
2157 | module_init(kswapd_init) | |
9eeff239 CL |
2158 | |
2159 | #ifdef CONFIG_NUMA | |
2160 | /* | |
2161 | * Zone reclaim mode | |
2162 | * | |
2163 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2164 | * the watermarks. | |
9eeff239 CL |
2165 | */ |
2166 | int zone_reclaim_mode __read_mostly; | |
2167 | ||
1b2ffb78 | 2168 | #define RECLAIM_OFF 0 |
7d03431c | 2169 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2170 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2171 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2172 | ||
a92f7126 CL |
2173 | /* |
2174 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2175 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2176 | * a zone. | |
2177 | */ | |
2178 | #define ZONE_RECLAIM_PRIORITY 4 | |
2179 | ||
9614634f CL |
2180 | /* |
2181 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2182 | * occur. | |
2183 | */ | |
2184 | int sysctl_min_unmapped_ratio = 1; | |
2185 | ||
0ff38490 CL |
2186 | /* |
2187 | * If the number of slab pages in a zone grows beyond this percentage then | |
2188 | * slab reclaim needs to occur. | |
2189 | */ | |
2190 | int sysctl_min_slab_ratio = 5; | |
2191 | ||
9eeff239 CL |
2192 | /* |
2193 | * Try to free up some pages from this zone through reclaim. | |
2194 | */ | |
179e9639 | 2195 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2196 | { |
7fb2d46d | 2197 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2198 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2199 | struct task_struct *p = current; |
2200 | struct reclaim_state reclaim_state; | |
8695949a | 2201 | int priority; |
05ff5137 | 2202 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
2203 | struct scan_control sc = { |
2204 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
2205 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
2206 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
2207 | SWAP_CLUSTER_MAX), | |
179e9639 | 2208 | .gfp_mask = gfp_mask, |
d6277db4 | 2209 | .swappiness = vm_swappiness, |
66e1707b | 2210 | .isolate_pages = isolate_pages_global, |
179e9639 | 2211 | }; |
83e33a47 | 2212 | unsigned long slab_reclaimable; |
9eeff239 CL |
2213 | |
2214 | disable_swap_token(); | |
9eeff239 | 2215 | cond_resched(); |
d4f7796e CL |
2216 | /* |
2217 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2218 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2219 | * and RECLAIM_SWAP. | |
2220 | */ | |
2221 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
2222 | reclaim_state.reclaimed_slab = 0; |
2223 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2224 | |
0ff38490 CL |
2225 | if (zone_page_state(zone, NR_FILE_PAGES) - |
2226 | zone_page_state(zone, NR_FILE_MAPPED) > | |
2227 | zone->min_unmapped_pages) { | |
2228 | /* | |
2229 | * Free memory by calling shrink zone with increasing | |
2230 | * priorities until we have enough memory freed. | |
2231 | */ | |
2232 | priority = ZONE_RECLAIM_PRIORITY; | |
2233 | do { | |
3bb1a852 | 2234 | note_zone_scanning_priority(zone, priority); |
0ff38490 CL |
2235 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
2236 | priority--; | |
2237 | } while (priority >= 0 && nr_reclaimed < nr_pages); | |
2238 | } | |
c84db23c | 2239 | |
83e33a47 CL |
2240 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2241 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2242 | /* |
7fb2d46d | 2243 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2244 | * many pages were freed in this zone. So we take the current |
2245 | * number of slab pages and shake the slab until it is reduced | |
2246 | * by the same nr_pages that we used for reclaiming unmapped | |
2247 | * pages. | |
2a16e3f4 | 2248 | * |
0ff38490 CL |
2249 | * Note that shrink_slab will free memory on all zones and may |
2250 | * take a long time. | |
2a16e3f4 | 2251 | */ |
0ff38490 | 2252 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2253 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2254 | slab_reclaimable - nr_pages) | |
0ff38490 | 2255 | ; |
83e33a47 CL |
2256 | |
2257 | /* | |
2258 | * Update nr_reclaimed by the number of slab pages we | |
2259 | * reclaimed from this zone. | |
2260 | */ | |
2261 | nr_reclaimed += slab_reclaimable - | |
2262 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); | |
2a16e3f4 CL |
2263 | } |
2264 | ||
9eeff239 | 2265 | p->reclaim_state = NULL; |
d4f7796e | 2266 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
05ff5137 | 2267 | return nr_reclaimed >= nr_pages; |
9eeff239 | 2268 | } |
179e9639 AM |
2269 | |
2270 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2271 | { | |
179e9639 | 2272 | int node_id; |
d773ed6b | 2273 | int ret; |
179e9639 AM |
2274 | |
2275 | /* | |
0ff38490 CL |
2276 | * Zone reclaim reclaims unmapped file backed pages and |
2277 | * slab pages if we are over the defined limits. | |
34aa1330 | 2278 | * |
9614634f CL |
2279 | * A small portion of unmapped file backed pages is needed for |
2280 | * file I/O otherwise pages read by file I/O will be immediately | |
2281 | * thrown out if the zone is overallocated. So we do not reclaim | |
2282 | * if less than a specified percentage of the zone is used by | |
2283 | * unmapped file backed pages. | |
179e9639 | 2284 | */ |
34aa1330 | 2285 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
2286 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
2287 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
2288 | <= zone->min_slab_pages) | |
9614634f | 2289 | return 0; |
179e9639 | 2290 | |
d773ed6b DR |
2291 | if (zone_is_all_unreclaimable(zone)) |
2292 | return 0; | |
2293 | ||
179e9639 | 2294 | /* |
d773ed6b | 2295 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2296 | */ |
d773ed6b | 2297 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
179e9639 AM |
2298 | return 0; |
2299 | ||
2300 | /* | |
2301 | * Only run zone reclaim on the local zone or on zones that do not | |
2302 | * have associated processors. This will favor the local processor | |
2303 | * over remote processors and spread off node memory allocations | |
2304 | * as wide as possible. | |
2305 | */ | |
89fa3024 | 2306 | node_id = zone_to_nid(zone); |
37c0708d | 2307 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
179e9639 | 2308 | return 0; |
d773ed6b DR |
2309 | |
2310 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
2311 | return 0; | |
2312 | ret = __zone_reclaim(zone, gfp_mask, order); | |
2313 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2314 | ||
2315 | return ret; | |
179e9639 | 2316 | } |
9eeff239 | 2317 | #endif |
894bc310 LS |
2318 | |
2319 | #ifdef CONFIG_UNEVICTABLE_LRU | |
2320 | /* | |
2321 | * page_evictable - test whether a page is evictable | |
2322 | * @page: the page to test | |
2323 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2324 | * | |
2325 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
2326 | * lists vs unevictable list. | |
2327 | * | |
2328 | * Reasons page might not be evictable: | |
2329 | * TODO - later patches | |
2330 | */ | |
2331 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2332 | { | |
2333 | ||
2334 | /* TODO: test page [!]evictable conditions */ | |
2335 | ||
2336 | return 1; | |
2337 | } | |
2338 | #endif |