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> | |
22 | #include <linux/file.h> | |
23 | #include <linux/writeback.h> | |
24 | #include <linux/blkdev.h> | |
25 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
26 | buffer_heads_over_limit */ | |
27 | #include <linux/mm_inline.h> | |
28 | #include <linux/pagevec.h> | |
29 | #include <linux/backing-dev.h> | |
30 | #include <linux/rmap.h> | |
31 | #include <linux/topology.h> | |
32 | #include <linux/cpu.h> | |
33 | #include <linux/cpuset.h> | |
34 | #include <linux/notifier.h> | |
35 | #include <linux/rwsem.h> | |
248a0301 | 36 | #include <linux/delay.h> |
1da177e4 LT |
37 | |
38 | #include <asm/tlbflush.h> | |
39 | #include <asm/div64.h> | |
40 | ||
41 | #include <linux/swapops.h> | |
42 | ||
0f8053a5 NP |
43 | #include "internal.h" |
44 | ||
1da177e4 | 45 | struct scan_control { |
1da177e4 LT |
46 | /* Incremented by the number of inactive pages that were scanned */ |
47 | unsigned long nr_scanned; | |
48 | ||
1da177e4 LT |
49 | unsigned long nr_mapped; /* From page_state */ |
50 | ||
1da177e4 | 51 | /* This context's GFP mask */ |
6daa0e28 | 52 | gfp_t gfp_mask; |
1da177e4 LT |
53 | |
54 | int may_writepage; | |
55 | ||
f1fd1067 CL |
56 | /* Can pages be swapped as part of reclaim? */ |
57 | int may_swap; | |
58 | ||
1da177e4 LT |
59 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
60 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
61 | * In this context, it doesn't matter that we scan the | |
62 | * whole list at once. */ | |
63 | int swap_cluster_max; | |
d6277db4 RW |
64 | |
65 | int swappiness; | |
1da177e4 LT |
66 | }; |
67 | ||
68 | /* | |
69 | * The list of shrinker callbacks used by to apply pressure to | |
70 | * ageable caches. | |
71 | */ | |
72 | struct shrinker { | |
73 | shrinker_t shrinker; | |
74 | struct list_head list; | |
75 | int seeks; /* seeks to recreate an obj */ | |
76 | long nr; /* objs pending delete */ | |
77 | }; | |
78 | ||
79 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
80 | ||
81 | #ifdef ARCH_HAS_PREFETCH | |
82 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
83 | do { \ | |
84 | if ((_page)->lru.prev != _base) { \ | |
85 | struct page *prev; \ | |
86 | \ | |
87 | prev = lru_to_page(&(_page->lru)); \ | |
88 | prefetch(&prev->_field); \ | |
89 | } \ | |
90 | } while (0) | |
91 | #else | |
92 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
93 | #endif | |
94 | ||
95 | #ifdef ARCH_HAS_PREFETCHW | |
96 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
97 | do { \ | |
98 | if ((_page)->lru.prev != _base) { \ | |
99 | struct page *prev; \ | |
100 | \ | |
101 | prev = lru_to_page(&(_page->lru)); \ | |
102 | prefetchw(&prev->_field); \ | |
103 | } \ | |
104 | } while (0) | |
105 | #else | |
106 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
107 | #endif | |
108 | ||
109 | /* | |
110 | * From 0 .. 100. Higher means more swappy. | |
111 | */ | |
112 | int vm_swappiness = 60; | |
113 | static long total_memory; | |
114 | ||
115 | static LIST_HEAD(shrinker_list); | |
116 | static DECLARE_RWSEM(shrinker_rwsem); | |
117 | ||
118 | /* | |
119 | * Add a shrinker callback to be called from the vm | |
120 | */ | |
121 | struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker) | |
122 | { | |
123 | struct shrinker *shrinker; | |
124 | ||
125 | shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL); | |
126 | if (shrinker) { | |
127 | shrinker->shrinker = theshrinker; | |
128 | shrinker->seeks = seeks; | |
129 | shrinker->nr = 0; | |
130 | down_write(&shrinker_rwsem); | |
131 | list_add_tail(&shrinker->list, &shrinker_list); | |
132 | up_write(&shrinker_rwsem); | |
133 | } | |
134 | return shrinker; | |
135 | } | |
136 | EXPORT_SYMBOL(set_shrinker); | |
137 | ||
138 | /* | |
139 | * Remove one | |
140 | */ | |
141 | void remove_shrinker(struct shrinker *shrinker) | |
142 | { | |
143 | down_write(&shrinker_rwsem); | |
144 | list_del(&shrinker->list); | |
145 | up_write(&shrinker_rwsem); | |
146 | kfree(shrinker); | |
147 | } | |
148 | EXPORT_SYMBOL(remove_shrinker); | |
149 | ||
150 | #define SHRINK_BATCH 128 | |
151 | /* | |
152 | * Call the shrink functions to age shrinkable caches | |
153 | * | |
154 | * Here we assume it costs one seek to replace a lru page and that it also | |
155 | * takes a seek to recreate a cache object. With this in mind we age equal | |
156 | * percentages of the lru and ageable caches. This should balance the seeks | |
157 | * generated by these structures. | |
158 | * | |
159 | * If the vm encounted mapped pages on the LRU it increase the pressure on | |
160 | * slab to avoid swapping. | |
161 | * | |
162 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
163 | * | |
164 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
165 | * are eligible for the caller's allocation attempt. It is used for balancing | |
166 | * slab reclaim versus page reclaim. | |
b15e0905 | 167 | * |
168 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 169 | */ |
69e05944 AM |
170 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
171 | unsigned long lru_pages) | |
1da177e4 LT |
172 | { |
173 | struct shrinker *shrinker; | |
69e05944 | 174 | unsigned long ret = 0; |
1da177e4 LT |
175 | |
176 | if (scanned == 0) | |
177 | scanned = SWAP_CLUSTER_MAX; | |
178 | ||
179 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 180 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
181 | |
182 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
183 | unsigned long long delta; | |
184 | unsigned long total_scan; | |
ea164d73 | 185 | unsigned long max_pass = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
186 | |
187 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 188 | delta *= max_pass; |
1da177e4 LT |
189 | do_div(delta, lru_pages + 1); |
190 | shrinker->nr += delta; | |
ea164d73 AA |
191 | if (shrinker->nr < 0) { |
192 | printk(KERN_ERR "%s: nr=%ld\n", | |
193 | __FUNCTION__, shrinker->nr); | |
194 | shrinker->nr = max_pass; | |
195 | } | |
196 | ||
197 | /* | |
198 | * Avoid risking looping forever due to too large nr value: | |
199 | * never try to free more than twice the estimate number of | |
200 | * freeable entries. | |
201 | */ | |
202 | if (shrinker->nr > max_pass * 2) | |
203 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
204 | |
205 | total_scan = shrinker->nr; | |
206 | shrinker->nr = 0; | |
207 | ||
208 | while (total_scan >= SHRINK_BATCH) { | |
209 | long this_scan = SHRINK_BATCH; | |
210 | int shrink_ret; | |
b15e0905 | 211 | int nr_before; |
1da177e4 | 212 | |
b15e0905 | 213 | nr_before = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
214 | shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask); |
215 | if (shrink_ret == -1) | |
216 | break; | |
b15e0905 | 217 | if (shrink_ret < nr_before) |
218 | ret += nr_before - shrink_ret; | |
1da177e4 LT |
219 | mod_page_state(slabs_scanned, this_scan); |
220 | total_scan -= this_scan; | |
221 | ||
222 | cond_resched(); | |
223 | } | |
224 | ||
225 | shrinker->nr += total_scan; | |
226 | } | |
227 | up_read(&shrinker_rwsem); | |
b15e0905 | 228 | return ret; |
1da177e4 LT |
229 | } |
230 | ||
231 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
232 | static inline int page_mapping_inuse(struct page *page) | |
233 | { | |
234 | struct address_space *mapping; | |
235 | ||
236 | /* Page is in somebody's page tables. */ | |
237 | if (page_mapped(page)) | |
238 | return 1; | |
239 | ||
240 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
241 | if (PageSwapCache(page)) | |
242 | return 1; | |
243 | ||
244 | mapping = page_mapping(page); | |
245 | if (!mapping) | |
246 | return 0; | |
247 | ||
248 | /* File is mmap'd by somebody? */ | |
249 | return mapping_mapped(mapping); | |
250 | } | |
251 | ||
252 | static inline int is_page_cache_freeable(struct page *page) | |
253 | { | |
254 | return page_count(page) - !!PagePrivate(page) == 2; | |
255 | } | |
256 | ||
257 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
258 | { | |
930d9152 | 259 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
260 | return 1; |
261 | if (!bdi_write_congested(bdi)) | |
262 | return 1; | |
263 | if (bdi == current->backing_dev_info) | |
264 | return 1; | |
265 | return 0; | |
266 | } | |
267 | ||
268 | /* | |
269 | * We detected a synchronous write error writing a page out. Probably | |
270 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
271 | * fsync(), msync() or close(). | |
272 | * | |
273 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
274 | * prevents it from being freed up. But we have a ref on the page and once | |
275 | * that page is locked, the mapping is pinned. | |
276 | * | |
277 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
278 | * __GFP_FS. | |
279 | */ | |
280 | static void handle_write_error(struct address_space *mapping, | |
281 | struct page *page, int error) | |
282 | { | |
283 | lock_page(page); | |
284 | if (page_mapping(page) == mapping) { | |
285 | if (error == -ENOSPC) | |
286 | set_bit(AS_ENOSPC, &mapping->flags); | |
287 | else | |
288 | set_bit(AS_EIO, &mapping->flags); | |
289 | } | |
290 | unlock_page(page); | |
291 | } | |
292 | ||
293 | /* | |
1742f19f AM |
294 | * pageout is called by shrink_page_list() for each dirty page. |
295 | * Calls ->writepage(). | |
1da177e4 | 296 | */ |
b20a3503 | 297 | pageout_t pageout(struct page *page, struct address_space *mapping) |
1da177e4 LT |
298 | { |
299 | /* | |
300 | * If the page is dirty, only perform writeback if that write | |
301 | * will be non-blocking. To prevent this allocation from being | |
302 | * stalled by pagecache activity. But note that there may be | |
303 | * stalls if we need to run get_block(). We could test | |
304 | * PagePrivate for that. | |
305 | * | |
306 | * If this process is currently in generic_file_write() against | |
307 | * this page's queue, we can perform writeback even if that | |
308 | * will block. | |
309 | * | |
310 | * If the page is swapcache, write it back even if that would | |
311 | * block, for some throttling. This happens by accident, because | |
312 | * swap_backing_dev_info is bust: it doesn't reflect the | |
313 | * congestion state of the swapdevs. Easy to fix, if needed. | |
314 | * See swapfile.c:page_queue_congested(). | |
315 | */ | |
316 | if (!is_page_cache_freeable(page)) | |
317 | return PAGE_KEEP; | |
318 | if (!mapping) { | |
319 | /* | |
320 | * Some data journaling orphaned pages can have | |
321 | * page->mapping == NULL while being dirty with clean buffers. | |
322 | */ | |
323aca6c | 323 | if (PagePrivate(page)) { |
1da177e4 LT |
324 | if (try_to_free_buffers(page)) { |
325 | ClearPageDirty(page); | |
326 | printk("%s: orphaned page\n", __FUNCTION__); | |
327 | return PAGE_CLEAN; | |
328 | } | |
329 | } | |
330 | return PAGE_KEEP; | |
331 | } | |
332 | if (mapping->a_ops->writepage == NULL) | |
333 | return PAGE_ACTIVATE; | |
334 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
335 | return PAGE_KEEP; | |
336 | ||
337 | if (clear_page_dirty_for_io(page)) { | |
338 | int res; | |
339 | struct writeback_control wbc = { | |
340 | .sync_mode = WB_SYNC_NONE, | |
341 | .nr_to_write = SWAP_CLUSTER_MAX, | |
342 | .nonblocking = 1, | |
343 | .for_reclaim = 1, | |
344 | }; | |
345 | ||
346 | SetPageReclaim(page); | |
347 | res = mapping->a_ops->writepage(page, &wbc); | |
348 | if (res < 0) | |
349 | handle_write_error(mapping, page, res); | |
994fc28c | 350 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
351 | ClearPageReclaim(page); |
352 | return PAGE_ACTIVATE; | |
353 | } | |
354 | if (!PageWriteback(page)) { | |
355 | /* synchronous write or broken a_ops? */ | |
356 | ClearPageReclaim(page); | |
357 | } | |
358 | ||
359 | return PAGE_SUCCESS; | |
360 | } | |
361 | ||
362 | return PAGE_CLEAN; | |
363 | } | |
364 | ||
b20a3503 | 365 | int remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc CL |
366 | { |
367 | if (!mapping) | |
368 | return 0; /* truncate got there first */ | |
369 | ||
370 | write_lock_irq(&mapping->tree_lock); | |
371 | ||
372 | /* | |
373 | * The non-racy check for busy page. It is critical to check | |
374 | * PageDirty _after_ making sure that the page is freeable and | |
375 | * not in use by anybody. (pagecache + us == 2) | |
376 | */ | |
377 | if (unlikely(page_count(page) != 2)) | |
378 | goto cannot_free; | |
379 | smp_rmb(); | |
380 | if (unlikely(PageDirty(page))) | |
381 | goto cannot_free; | |
382 | ||
383 | if (PageSwapCache(page)) { | |
384 | swp_entry_t swap = { .val = page_private(page) }; | |
385 | __delete_from_swap_cache(page); | |
386 | write_unlock_irq(&mapping->tree_lock); | |
387 | swap_free(swap); | |
388 | __put_page(page); /* The pagecache ref */ | |
389 | return 1; | |
390 | } | |
391 | ||
392 | __remove_from_page_cache(page); | |
393 | write_unlock_irq(&mapping->tree_lock); | |
394 | __put_page(page); | |
395 | return 1; | |
396 | ||
397 | cannot_free: | |
398 | write_unlock_irq(&mapping->tree_lock); | |
399 | return 0; | |
400 | } | |
401 | ||
1da177e4 | 402 | /* |
1742f19f | 403 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 404 | */ |
1742f19f AM |
405 | static unsigned long shrink_page_list(struct list_head *page_list, |
406 | struct scan_control *sc) | |
1da177e4 LT |
407 | { |
408 | LIST_HEAD(ret_pages); | |
409 | struct pagevec freed_pvec; | |
410 | int pgactivate = 0; | |
05ff5137 | 411 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
412 | |
413 | cond_resched(); | |
414 | ||
415 | pagevec_init(&freed_pvec, 1); | |
416 | while (!list_empty(page_list)) { | |
417 | struct address_space *mapping; | |
418 | struct page *page; | |
419 | int may_enter_fs; | |
420 | int referenced; | |
421 | ||
422 | cond_resched(); | |
423 | ||
424 | page = lru_to_page(page_list); | |
425 | list_del(&page->lru); | |
426 | ||
427 | if (TestSetPageLocked(page)) | |
428 | goto keep; | |
429 | ||
430 | BUG_ON(PageActive(page)); | |
431 | ||
432 | sc->nr_scanned++; | |
80e43426 CL |
433 | |
434 | if (!sc->may_swap && page_mapped(page)) | |
435 | goto keep_locked; | |
436 | ||
1da177e4 LT |
437 | /* Double the slab pressure for mapped and swapcache pages */ |
438 | if (page_mapped(page) || PageSwapCache(page)) | |
439 | sc->nr_scanned++; | |
440 | ||
441 | if (PageWriteback(page)) | |
442 | goto keep_locked; | |
443 | ||
f7b7fd8f | 444 | referenced = page_referenced(page, 1); |
1da177e4 LT |
445 | /* In active use or really unfreeable? Activate it. */ |
446 | if (referenced && page_mapping_inuse(page)) | |
447 | goto activate_locked; | |
448 | ||
449 | #ifdef CONFIG_SWAP | |
450 | /* | |
451 | * Anonymous process memory has backing store? | |
452 | * Try to allocate it some swap space here. | |
453 | */ | |
6e5ef1a9 | 454 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 455 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 456 | goto activate_locked; |
1da177e4 LT |
457 | #endif /* CONFIG_SWAP */ |
458 | ||
459 | mapping = page_mapping(page); | |
460 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || | |
461 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
462 | ||
463 | /* | |
464 | * The page is mapped into the page tables of one or more | |
465 | * processes. Try to unmap it here. | |
466 | */ | |
467 | if (page_mapped(page) && mapping) { | |
a48d07af | 468 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
469 | case SWAP_FAIL: |
470 | goto activate_locked; | |
471 | case SWAP_AGAIN: | |
472 | goto keep_locked; | |
473 | case SWAP_SUCCESS: | |
474 | ; /* try to free the page below */ | |
475 | } | |
476 | } | |
477 | ||
478 | if (PageDirty(page)) { | |
479 | if (referenced) | |
480 | goto keep_locked; | |
481 | if (!may_enter_fs) | |
482 | goto keep_locked; | |
52a8363e | 483 | if (!sc->may_writepage) |
1da177e4 LT |
484 | goto keep_locked; |
485 | ||
486 | /* Page is dirty, try to write it out here */ | |
487 | switch(pageout(page, mapping)) { | |
488 | case PAGE_KEEP: | |
489 | goto keep_locked; | |
490 | case PAGE_ACTIVATE: | |
491 | goto activate_locked; | |
492 | case PAGE_SUCCESS: | |
493 | if (PageWriteback(page) || PageDirty(page)) | |
494 | goto keep; | |
495 | /* | |
496 | * A synchronous write - probably a ramdisk. Go | |
497 | * ahead and try to reclaim the page. | |
498 | */ | |
499 | if (TestSetPageLocked(page)) | |
500 | goto keep; | |
501 | if (PageDirty(page) || PageWriteback(page)) | |
502 | goto keep_locked; | |
503 | mapping = page_mapping(page); | |
504 | case PAGE_CLEAN: | |
505 | ; /* try to free the page below */ | |
506 | } | |
507 | } | |
508 | ||
509 | /* | |
510 | * If the page has buffers, try to free the buffer mappings | |
511 | * associated with this page. If we succeed we try to free | |
512 | * the page as well. | |
513 | * | |
514 | * We do this even if the page is PageDirty(). | |
515 | * try_to_release_page() does not perform I/O, but it is | |
516 | * possible for a page to have PageDirty set, but it is actually | |
517 | * clean (all its buffers are clean). This happens if the | |
518 | * buffers were written out directly, with submit_bh(). ext3 | |
519 | * will do this, as well as the blockdev mapping. | |
520 | * try_to_release_page() will discover that cleanness and will | |
521 | * drop the buffers and mark the page clean - it can be freed. | |
522 | * | |
523 | * Rarely, pages can have buffers and no ->mapping. These are | |
524 | * the pages which were not successfully invalidated in | |
525 | * truncate_complete_page(). We try to drop those buffers here | |
526 | * and if that worked, and the page is no longer mapped into | |
527 | * process address space (page_count == 1) it can be freed. | |
528 | * Otherwise, leave the page on the LRU so it is swappable. | |
529 | */ | |
530 | if (PagePrivate(page)) { | |
531 | if (!try_to_release_page(page, sc->gfp_mask)) | |
532 | goto activate_locked; | |
533 | if (!mapping && page_count(page) == 1) | |
534 | goto free_it; | |
535 | } | |
536 | ||
49d2e9cc CL |
537 | if (!remove_mapping(mapping, page)) |
538 | goto keep_locked; | |
1da177e4 LT |
539 | |
540 | free_it: | |
541 | unlock_page(page); | |
05ff5137 | 542 | nr_reclaimed++; |
1da177e4 LT |
543 | if (!pagevec_add(&freed_pvec, page)) |
544 | __pagevec_release_nonlru(&freed_pvec); | |
545 | continue; | |
546 | ||
547 | activate_locked: | |
548 | SetPageActive(page); | |
549 | pgactivate++; | |
550 | keep_locked: | |
551 | unlock_page(page); | |
552 | keep: | |
553 | list_add(&page->lru, &ret_pages); | |
554 | BUG_ON(PageLRU(page)); | |
555 | } | |
556 | list_splice(&ret_pages, page_list); | |
557 | if (pagevec_count(&freed_pvec)) | |
558 | __pagevec_release_nonlru(&freed_pvec); | |
559 | mod_page_state(pgactivate, pgactivate); | |
05ff5137 | 560 | return nr_reclaimed; |
1da177e4 LT |
561 | } |
562 | ||
563 | /* | |
564 | * zone->lru_lock is heavily contended. Some of the functions that | |
565 | * shrink the lists perform better by taking out a batch of pages | |
566 | * and working on them outside the LRU lock. | |
567 | * | |
568 | * For pagecache intensive workloads, this function is the hottest | |
569 | * spot in the kernel (apart from copy_*_user functions). | |
570 | * | |
571 | * Appropriate locks must be held before calling this function. | |
572 | * | |
573 | * @nr_to_scan: The number of pages to look through on the list. | |
574 | * @src: The LRU list to pull pages off. | |
575 | * @dst: The temp list to put pages on to. | |
576 | * @scanned: The number of pages that were scanned. | |
577 | * | |
578 | * returns how many pages were moved onto *@dst. | |
579 | */ | |
69e05944 AM |
580 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
581 | struct list_head *src, struct list_head *dst, | |
582 | unsigned long *scanned) | |
1da177e4 | 583 | { |
69e05944 | 584 | unsigned long nr_taken = 0; |
1da177e4 | 585 | struct page *page; |
c9b02d97 | 586 | unsigned long scan; |
1da177e4 | 587 | |
c9b02d97 | 588 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
7c8ee9a8 | 589 | struct list_head *target; |
1da177e4 LT |
590 | page = lru_to_page(src); |
591 | prefetchw_prev_lru_page(page, src, flags); | |
592 | ||
8d438f96 NP |
593 | BUG_ON(!PageLRU(page)); |
594 | ||
053837fc | 595 | list_del(&page->lru); |
7c8ee9a8 NP |
596 | target = src; |
597 | if (likely(get_page_unless_zero(page))) { | |
053837fc | 598 | /* |
7c8ee9a8 NP |
599 | * Be careful not to clear PageLRU until after we're |
600 | * sure the page is not being freed elsewhere -- the | |
601 | * page release code relies on it. | |
053837fc | 602 | */ |
7c8ee9a8 NP |
603 | ClearPageLRU(page); |
604 | target = dst; | |
605 | nr_taken++; | |
606 | } /* else it is being freed elsewhere */ | |
46453a6e | 607 | |
7c8ee9a8 | 608 | list_add(&page->lru, target); |
1da177e4 LT |
609 | } |
610 | ||
611 | *scanned = scan; | |
612 | return nr_taken; | |
613 | } | |
614 | ||
615 | /* | |
1742f19f AM |
616 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
617 | * of reclaimed pages | |
1da177e4 | 618 | */ |
1742f19f AM |
619 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
620 | struct zone *zone, struct scan_control *sc) | |
1da177e4 LT |
621 | { |
622 | LIST_HEAD(page_list); | |
623 | struct pagevec pvec; | |
69e05944 | 624 | unsigned long nr_scanned = 0; |
05ff5137 | 625 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
626 | |
627 | pagevec_init(&pvec, 1); | |
628 | ||
629 | lru_add_drain(); | |
630 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 631 | do { |
1da177e4 | 632 | struct page *page; |
69e05944 AM |
633 | unsigned long nr_taken; |
634 | unsigned long nr_scan; | |
635 | unsigned long nr_freed; | |
1da177e4 LT |
636 | |
637 | nr_taken = isolate_lru_pages(sc->swap_cluster_max, | |
638 | &zone->inactive_list, | |
639 | &page_list, &nr_scan); | |
640 | zone->nr_inactive -= nr_taken; | |
641 | zone->pages_scanned += nr_scan; | |
642 | spin_unlock_irq(&zone->lru_lock); | |
643 | ||
69e05944 | 644 | nr_scanned += nr_scan; |
1742f19f | 645 | nr_freed = shrink_page_list(&page_list, sc); |
05ff5137 | 646 | nr_reclaimed += nr_freed; |
a74609fa NP |
647 | local_irq_disable(); |
648 | if (current_is_kswapd()) { | |
649 | __mod_page_state_zone(zone, pgscan_kswapd, nr_scan); | |
650 | __mod_page_state(kswapd_steal, nr_freed); | |
651 | } else | |
652 | __mod_page_state_zone(zone, pgscan_direct, nr_scan); | |
653 | __mod_page_state_zone(zone, pgsteal, nr_freed); | |
654 | ||
fb8d14e1 WF |
655 | if (nr_taken == 0) |
656 | goto done; | |
657 | ||
a74609fa | 658 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
659 | /* |
660 | * Put back any unfreeable pages. | |
661 | */ | |
662 | while (!list_empty(&page_list)) { | |
663 | page = lru_to_page(&page_list); | |
8d438f96 NP |
664 | BUG_ON(PageLRU(page)); |
665 | SetPageLRU(page); | |
1da177e4 LT |
666 | list_del(&page->lru); |
667 | if (PageActive(page)) | |
668 | add_page_to_active_list(zone, page); | |
669 | else | |
670 | add_page_to_inactive_list(zone, page); | |
671 | if (!pagevec_add(&pvec, page)) { | |
672 | spin_unlock_irq(&zone->lru_lock); | |
673 | __pagevec_release(&pvec); | |
674 | spin_lock_irq(&zone->lru_lock); | |
675 | } | |
676 | } | |
69e05944 | 677 | } while (nr_scanned < max_scan); |
fb8d14e1 | 678 | spin_unlock(&zone->lru_lock); |
1da177e4 | 679 | done: |
fb8d14e1 | 680 | local_irq_enable(); |
1da177e4 | 681 | pagevec_release(&pvec); |
05ff5137 | 682 | return nr_reclaimed; |
1da177e4 LT |
683 | } |
684 | ||
685 | /* | |
686 | * This moves pages from the active list to the inactive list. | |
687 | * | |
688 | * We move them the other way if the page is referenced by one or more | |
689 | * processes, from rmap. | |
690 | * | |
691 | * If the pages are mostly unmapped, the processing is fast and it is | |
692 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
693 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
694 | * should drop zone->lru_lock around each page. It's impossible to balance | |
695 | * this, so instead we remove the pages from the LRU while processing them. | |
696 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
697 | * nobody will play with that bit on a non-LRU page. | |
698 | * | |
699 | * The downside is that we have to touch page->_count against each page. | |
700 | * But we had to alter page->flags anyway. | |
701 | */ | |
1742f19f AM |
702 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
703 | struct scan_control *sc) | |
1da177e4 | 704 | { |
69e05944 | 705 | unsigned long pgmoved; |
1da177e4 | 706 | int pgdeactivate = 0; |
69e05944 | 707 | unsigned long pgscanned; |
1da177e4 LT |
708 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
709 | LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ | |
710 | LIST_HEAD(l_active); /* Pages to go onto the active_list */ | |
711 | struct page *page; | |
712 | struct pagevec pvec; | |
713 | int reclaim_mapped = 0; | |
2903fb16 | 714 | |
6e5ef1a9 | 715 | if (sc->may_swap) { |
2903fb16 CL |
716 | long mapped_ratio; |
717 | long distress; | |
718 | long swap_tendency; | |
719 | ||
720 | /* | |
721 | * `distress' is a measure of how much trouble we're having | |
722 | * reclaiming pages. 0 -> no problems. 100 -> great trouble. | |
723 | */ | |
724 | distress = 100 >> zone->prev_priority; | |
725 | ||
726 | /* | |
727 | * The point of this algorithm is to decide when to start | |
728 | * reclaiming mapped memory instead of just pagecache. Work out | |
729 | * how much memory | |
730 | * is mapped. | |
731 | */ | |
732 | mapped_ratio = (sc->nr_mapped * 100) / total_memory; | |
733 | ||
734 | /* | |
735 | * Now decide how much we really want to unmap some pages. The | |
736 | * mapped ratio is downgraded - just because there's a lot of | |
737 | * mapped memory doesn't necessarily mean that page reclaim | |
738 | * isn't succeeding. | |
739 | * | |
740 | * The distress ratio is important - we don't want to start | |
741 | * going oom. | |
742 | * | |
743 | * A 100% value of vm_swappiness overrides this algorithm | |
744 | * altogether. | |
745 | */ | |
d6277db4 | 746 | swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; |
2903fb16 CL |
747 | |
748 | /* | |
749 | * Now use this metric to decide whether to start moving mapped | |
750 | * memory onto the inactive list. | |
751 | */ | |
752 | if (swap_tendency >= 100) | |
753 | reclaim_mapped = 1; | |
754 | } | |
1da177e4 LT |
755 | |
756 | lru_add_drain(); | |
757 | spin_lock_irq(&zone->lru_lock); | |
758 | pgmoved = isolate_lru_pages(nr_pages, &zone->active_list, | |
759 | &l_hold, &pgscanned); | |
760 | zone->pages_scanned += pgscanned; | |
761 | zone->nr_active -= pgmoved; | |
762 | spin_unlock_irq(&zone->lru_lock); | |
763 | ||
1da177e4 LT |
764 | while (!list_empty(&l_hold)) { |
765 | cond_resched(); | |
766 | page = lru_to_page(&l_hold); | |
767 | list_del(&page->lru); | |
768 | if (page_mapped(page)) { | |
769 | if (!reclaim_mapped || | |
770 | (total_swap_pages == 0 && PageAnon(page)) || | |
f7b7fd8f | 771 | page_referenced(page, 0)) { |
1da177e4 LT |
772 | list_add(&page->lru, &l_active); |
773 | continue; | |
774 | } | |
775 | } | |
776 | list_add(&page->lru, &l_inactive); | |
777 | } | |
778 | ||
779 | pagevec_init(&pvec, 1); | |
780 | pgmoved = 0; | |
781 | spin_lock_irq(&zone->lru_lock); | |
782 | while (!list_empty(&l_inactive)) { | |
783 | page = lru_to_page(&l_inactive); | |
784 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
8d438f96 NP |
785 | BUG_ON(PageLRU(page)); |
786 | SetPageLRU(page); | |
4c84cacf NP |
787 | BUG_ON(!PageActive(page)); |
788 | ClearPageActive(page); | |
789 | ||
1da177e4 LT |
790 | list_move(&page->lru, &zone->inactive_list); |
791 | pgmoved++; | |
792 | if (!pagevec_add(&pvec, page)) { | |
793 | zone->nr_inactive += pgmoved; | |
794 | spin_unlock_irq(&zone->lru_lock); | |
795 | pgdeactivate += pgmoved; | |
796 | pgmoved = 0; | |
797 | if (buffer_heads_over_limit) | |
798 | pagevec_strip(&pvec); | |
799 | __pagevec_release(&pvec); | |
800 | spin_lock_irq(&zone->lru_lock); | |
801 | } | |
802 | } | |
803 | zone->nr_inactive += pgmoved; | |
804 | pgdeactivate += pgmoved; | |
805 | if (buffer_heads_over_limit) { | |
806 | spin_unlock_irq(&zone->lru_lock); | |
807 | pagevec_strip(&pvec); | |
808 | spin_lock_irq(&zone->lru_lock); | |
809 | } | |
810 | ||
811 | pgmoved = 0; | |
812 | while (!list_empty(&l_active)) { | |
813 | page = lru_to_page(&l_active); | |
814 | prefetchw_prev_lru_page(page, &l_active, flags); | |
8d438f96 NP |
815 | BUG_ON(PageLRU(page)); |
816 | SetPageLRU(page); | |
1da177e4 LT |
817 | BUG_ON(!PageActive(page)); |
818 | list_move(&page->lru, &zone->active_list); | |
819 | pgmoved++; | |
820 | if (!pagevec_add(&pvec, page)) { | |
821 | zone->nr_active += pgmoved; | |
822 | pgmoved = 0; | |
823 | spin_unlock_irq(&zone->lru_lock); | |
824 | __pagevec_release(&pvec); | |
825 | spin_lock_irq(&zone->lru_lock); | |
826 | } | |
827 | } | |
828 | zone->nr_active += pgmoved; | |
a74609fa NP |
829 | spin_unlock(&zone->lru_lock); |
830 | ||
831 | __mod_page_state_zone(zone, pgrefill, pgscanned); | |
832 | __mod_page_state(pgdeactivate, pgdeactivate); | |
833 | local_irq_enable(); | |
1da177e4 | 834 | |
a74609fa | 835 | pagevec_release(&pvec); |
1da177e4 LT |
836 | } |
837 | ||
838 | /* | |
839 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
840 | */ | |
05ff5137 AM |
841 | static unsigned long shrink_zone(int priority, struct zone *zone, |
842 | struct scan_control *sc) | |
1da177e4 LT |
843 | { |
844 | unsigned long nr_active; | |
845 | unsigned long nr_inactive; | |
8695949a | 846 | unsigned long nr_to_scan; |
05ff5137 | 847 | unsigned long nr_reclaimed = 0; |
1da177e4 | 848 | |
53e9a615 MH |
849 | atomic_inc(&zone->reclaim_in_progress); |
850 | ||
1da177e4 LT |
851 | /* |
852 | * Add one to `nr_to_scan' just to make sure that the kernel will | |
853 | * slowly sift through the active list. | |
854 | */ | |
8695949a | 855 | zone->nr_scan_active += (zone->nr_active >> priority) + 1; |
1da177e4 LT |
856 | nr_active = zone->nr_scan_active; |
857 | if (nr_active >= sc->swap_cluster_max) | |
858 | zone->nr_scan_active = 0; | |
859 | else | |
860 | nr_active = 0; | |
861 | ||
8695949a | 862 | zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1; |
1da177e4 LT |
863 | nr_inactive = zone->nr_scan_inactive; |
864 | if (nr_inactive >= sc->swap_cluster_max) | |
865 | zone->nr_scan_inactive = 0; | |
866 | else | |
867 | nr_inactive = 0; | |
868 | ||
1da177e4 LT |
869 | while (nr_active || nr_inactive) { |
870 | if (nr_active) { | |
8695949a | 871 | nr_to_scan = min(nr_active, |
1da177e4 | 872 | (unsigned long)sc->swap_cluster_max); |
8695949a | 873 | nr_active -= nr_to_scan; |
1742f19f | 874 | shrink_active_list(nr_to_scan, zone, sc); |
1da177e4 LT |
875 | } |
876 | ||
877 | if (nr_inactive) { | |
8695949a | 878 | nr_to_scan = min(nr_inactive, |
1da177e4 | 879 | (unsigned long)sc->swap_cluster_max); |
8695949a | 880 | nr_inactive -= nr_to_scan; |
1742f19f AM |
881 | nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, |
882 | sc); | |
1da177e4 LT |
883 | } |
884 | } | |
885 | ||
886 | throttle_vm_writeout(); | |
53e9a615 MH |
887 | |
888 | atomic_dec(&zone->reclaim_in_progress); | |
05ff5137 | 889 | return nr_reclaimed; |
1da177e4 LT |
890 | } |
891 | ||
892 | /* | |
893 | * This is the direct reclaim path, for page-allocating processes. We only | |
894 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
895 | * request. | |
896 | * | |
897 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
898 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
899 | * allocation or | |
900 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
901 | * satisfy the `incremental min' zone defense algorithm. | |
902 | * | |
903 | * Returns the number of reclaimed pages. | |
904 | * | |
905 | * If a zone is deemed to be full of pinned pages then just give it a light | |
906 | * scan then give up on it. | |
907 | */ | |
1742f19f | 908 | static unsigned long shrink_zones(int priority, struct zone **zones, |
05ff5137 | 909 | struct scan_control *sc) |
1da177e4 | 910 | { |
05ff5137 | 911 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
912 | int i; |
913 | ||
914 | for (i = 0; zones[i] != NULL; i++) { | |
915 | struct zone *zone = zones[i]; | |
916 | ||
f3fe6512 | 917 | if (!populated_zone(zone)) |
1da177e4 LT |
918 | continue; |
919 | ||
9bf2229f | 920 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
921 | continue; |
922 | ||
8695949a CL |
923 | zone->temp_priority = priority; |
924 | if (zone->prev_priority > priority) | |
925 | zone->prev_priority = priority; | |
1da177e4 | 926 | |
8695949a | 927 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
928 | continue; /* Let kswapd poll it */ |
929 | ||
05ff5137 | 930 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 931 | } |
05ff5137 | 932 | return nr_reclaimed; |
1da177e4 LT |
933 | } |
934 | ||
935 | /* | |
936 | * This is the main entry point to direct page reclaim. | |
937 | * | |
938 | * If a full scan of the inactive list fails to free enough memory then we | |
939 | * are "out of memory" and something needs to be killed. | |
940 | * | |
941 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
942 | * high - the zone may be full of dirty or under-writeback pages, which this | |
943 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
944 | * hope that some of these pages can be written. But if the allocating task | |
945 | * holds filesystem locks which prevent writeout this might not work, and the | |
946 | * allocation attempt will fail. | |
947 | */ | |
69e05944 | 948 | unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask) |
1da177e4 LT |
949 | { |
950 | int priority; | |
951 | int ret = 0; | |
69e05944 | 952 | unsigned long total_scanned = 0; |
05ff5137 | 953 | unsigned long nr_reclaimed = 0; |
1da177e4 | 954 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 LT |
955 | unsigned long lru_pages = 0; |
956 | int i; | |
179e9639 AM |
957 | struct scan_control sc = { |
958 | .gfp_mask = gfp_mask, | |
959 | .may_writepage = !laptop_mode, | |
960 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
961 | .may_swap = 1, | |
d6277db4 | 962 | .swappiness = vm_swappiness, |
179e9639 | 963 | }; |
1da177e4 LT |
964 | |
965 | inc_page_state(allocstall); | |
966 | ||
967 | for (i = 0; zones[i] != NULL; i++) { | |
968 | struct zone *zone = zones[i]; | |
969 | ||
9bf2229f | 970 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
971 | continue; |
972 | ||
973 | zone->temp_priority = DEF_PRIORITY; | |
974 | lru_pages += zone->nr_active + zone->nr_inactive; | |
975 | } | |
976 | ||
977 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
978 | sc.nr_mapped = read_page_state(nr_mapped); | |
979 | sc.nr_scanned = 0; | |
f7b7fd8f RR |
980 | if (!priority) |
981 | disable_swap_token(); | |
1742f19f | 982 | nr_reclaimed += shrink_zones(priority, zones, &sc); |
1da177e4 LT |
983 | shrink_slab(sc.nr_scanned, gfp_mask, lru_pages); |
984 | if (reclaim_state) { | |
05ff5137 | 985 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
986 | reclaim_state->reclaimed_slab = 0; |
987 | } | |
988 | total_scanned += sc.nr_scanned; | |
05ff5137 | 989 | if (nr_reclaimed >= sc.swap_cluster_max) { |
1da177e4 LT |
990 | ret = 1; |
991 | goto out; | |
992 | } | |
993 | ||
994 | /* | |
995 | * Try to write back as many pages as we just scanned. This | |
996 | * tends to cause slow streaming writers to write data to the | |
997 | * disk smoothly, at the dirtying rate, which is nice. But | |
998 | * that's undesirable in laptop mode, where we *want* lumpy | |
999 | * writeout. So in laptop mode, write out the whole world. | |
1000 | */ | |
179e9639 AM |
1001 | if (total_scanned > sc.swap_cluster_max + |
1002 | sc.swap_cluster_max / 2) { | |
687a21ce | 1003 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
1da177e4 LT |
1004 | sc.may_writepage = 1; |
1005 | } | |
1006 | ||
1007 | /* Take a nap, wait for some writeback to complete */ | |
1008 | if (sc.nr_scanned && priority < DEF_PRIORITY - 2) | |
1009 | blk_congestion_wait(WRITE, HZ/10); | |
1010 | } | |
1011 | out: | |
1012 | for (i = 0; zones[i] != 0; i++) { | |
1013 | struct zone *zone = zones[i]; | |
1014 | ||
9bf2229f | 1015 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
1016 | continue; |
1017 | ||
1018 | zone->prev_priority = zone->temp_priority; | |
1019 | } | |
1020 | return ret; | |
1021 | } | |
1022 | ||
1023 | /* | |
1024 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1025 | * they are all at pages_high. | |
1026 | * | |
1da177e4 LT |
1027 | * Returns the number of pages which were actually freed. |
1028 | * | |
1029 | * There is special handling here for zones which are full of pinned pages. | |
1030 | * This can happen if the pages are all mlocked, or if they are all used by | |
1031 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1032 | * What we do is to detect the case where all pages in the zone have been | |
1033 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1034 | * dead and from now on, only perform a short scan. Basically we're polling | |
1035 | * the zone for when the problem goes away. | |
1036 | * | |
1037 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1038 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1039 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1040 | * of the number of free pages in the lower zones. This interoperates with | |
1041 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1042 | * across the zones. | |
1043 | */ | |
d6277db4 | 1044 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1045 | { |
1da177e4 LT |
1046 | int all_zones_ok; |
1047 | int priority; | |
1048 | int i; | |
69e05944 | 1049 | unsigned long total_scanned; |
05ff5137 | 1050 | unsigned long nr_reclaimed; |
1da177e4 | 1051 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1052 | struct scan_control sc = { |
1053 | .gfp_mask = GFP_KERNEL, | |
1054 | .may_swap = 1, | |
d6277db4 RW |
1055 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1056 | .swappiness = vm_swappiness, | |
179e9639 | 1057 | }; |
1da177e4 LT |
1058 | |
1059 | loop_again: | |
1060 | total_scanned = 0; | |
05ff5137 | 1061 | nr_reclaimed = 0; |
c0bbbc73 | 1062 | sc.may_writepage = !laptop_mode; |
1da177e4 LT |
1063 | sc.nr_mapped = read_page_state(nr_mapped); |
1064 | ||
1065 | inc_page_state(pageoutrun); | |
1066 | ||
1067 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1068 | struct zone *zone = pgdat->node_zones + i; | |
1069 | ||
1070 | zone->temp_priority = DEF_PRIORITY; | |
1071 | } | |
1072 | ||
1073 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1074 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1075 | unsigned long lru_pages = 0; | |
1076 | ||
f7b7fd8f RR |
1077 | /* The swap token gets in the way of swapout... */ |
1078 | if (!priority) | |
1079 | disable_swap_token(); | |
1080 | ||
1da177e4 LT |
1081 | all_zones_ok = 1; |
1082 | ||
d6277db4 RW |
1083 | /* |
1084 | * Scan in the highmem->dma direction for the highest | |
1085 | * zone which needs scanning | |
1086 | */ | |
1087 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1088 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1089 | |
d6277db4 RW |
1090 | if (!populated_zone(zone)) |
1091 | continue; | |
1da177e4 | 1092 | |
d6277db4 RW |
1093 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1094 | continue; | |
1da177e4 | 1095 | |
d6277db4 RW |
1096 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1097 | 0, 0)) { | |
1098 | end_zone = i; | |
1099 | goto scan; | |
1da177e4 | 1100 | } |
1da177e4 | 1101 | } |
d6277db4 | 1102 | goto out; |
1da177e4 LT |
1103 | scan: |
1104 | for (i = 0; i <= end_zone; i++) { | |
1105 | struct zone *zone = pgdat->node_zones + i; | |
1106 | ||
1107 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1108 | } | |
1109 | ||
1110 | /* | |
1111 | * Now scan the zone in the dma->highmem direction, stopping | |
1112 | * at the last zone which needs scanning. | |
1113 | * | |
1114 | * We do this because the page allocator works in the opposite | |
1115 | * direction. This prevents the page allocator from allocating | |
1116 | * pages behind kswapd's direction of progress, which would | |
1117 | * cause too much scanning of the lower zones. | |
1118 | */ | |
1119 | for (i = 0; i <= end_zone; i++) { | |
1120 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1121 | int nr_slab; |
1da177e4 | 1122 | |
f3fe6512 | 1123 | if (!populated_zone(zone)) |
1da177e4 LT |
1124 | continue; |
1125 | ||
1126 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
1127 | continue; | |
1128 | ||
d6277db4 RW |
1129 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1130 | end_zone, 0)) | |
1131 | all_zones_ok = 0; | |
1da177e4 LT |
1132 | zone->temp_priority = priority; |
1133 | if (zone->prev_priority > priority) | |
1134 | zone->prev_priority = priority; | |
1135 | sc.nr_scanned = 0; | |
05ff5137 | 1136 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
1da177e4 | 1137 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1138 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1139 | lru_pages); | |
05ff5137 | 1140 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1141 | total_scanned += sc.nr_scanned; |
1142 | if (zone->all_unreclaimable) | |
1143 | continue; | |
b15e0905 | 1144 | if (nr_slab == 0 && zone->pages_scanned >= |
1145 | (zone->nr_active + zone->nr_inactive) * 4) | |
1da177e4 LT |
1146 | zone->all_unreclaimable = 1; |
1147 | /* | |
1148 | * If we've done a decent amount of scanning and | |
1149 | * the reclaim ratio is low, start doing writepage | |
1150 | * even in laptop mode | |
1151 | */ | |
1152 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1153 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1154 | sc.may_writepage = 1; |
1155 | } | |
1da177e4 LT |
1156 | if (all_zones_ok) |
1157 | break; /* kswapd: all done */ | |
1158 | /* | |
1159 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1160 | * another pass across the zones. | |
1161 | */ | |
1162 | if (total_scanned && priority < DEF_PRIORITY - 2) | |
1163 | blk_congestion_wait(WRITE, HZ/10); | |
1164 | ||
1165 | /* | |
1166 | * We do this so kswapd doesn't build up large priorities for | |
1167 | * example when it is freeing in parallel with allocators. It | |
1168 | * matches the direct reclaim path behaviour in terms of impact | |
1169 | * on zone->*_priority. | |
1170 | */ | |
d6277db4 | 1171 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1172 | break; |
1173 | } | |
1174 | out: | |
1175 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1176 | struct zone *zone = pgdat->node_zones + i; | |
1177 | ||
1178 | zone->prev_priority = zone->temp_priority; | |
1179 | } | |
1180 | if (!all_zones_ok) { | |
1181 | cond_resched(); | |
1182 | goto loop_again; | |
1183 | } | |
1184 | ||
05ff5137 | 1185 | return nr_reclaimed; |
1da177e4 LT |
1186 | } |
1187 | ||
1188 | /* | |
1189 | * The background pageout daemon, started as a kernel thread | |
1190 | * from the init process. | |
1191 | * | |
1192 | * This basically trickles out pages so that we have _some_ | |
1193 | * free memory available even if there is no other activity | |
1194 | * that frees anything up. This is needed for things like routing | |
1195 | * etc, where we otherwise might have all activity going on in | |
1196 | * asynchronous contexts that cannot page things out. | |
1197 | * | |
1198 | * If there are applications that are active memory-allocators | |
1199 | * (most normal use), this basically shouldn't matter. | |
1200 | */ | |
1201 | static int kswapd(void *p) | |
1202 | { | |
1203 | unsigned long order; | |
1204 | pg_data_t *pgdat = (pg_data_t*)p; | |
1205 | struct task_struct *tsk = current; | |
1206 | DEFINE_WAIT(wait); | |
1207 | struct reclaim_state reclaim_state = { | |
1208 | .reclaimed_slab = 0, | |
1209 | }; | |
1210 | cpumask_t cpumask; | |
1211 | ||
1212 | daemonize("kswapd%d", pgdat->node_id); | |
1213 | cpumask = node_to_cpumask(pgdat->node_id); | |
1214 | if (!cpus_empty(cpumask)) | |
1215 | set_cpus_allowed(tsk, cpumask); | |
1216 | current->reclaim_state = &reclaim_state; | |
1217 | ||
1218 | /* | |
1219 | * Tell the memory management that we're a "memory allocator", | |
1220 | * and that if we need more memory we should get access to it | |
1221 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1222 | * never get caught in the normal page freeing logic. | |
1223 | * | |
1224 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1225 | * you need a small amount of memory in order to be able to | |
1226 | * page out something else, and this flag essentially protects | |
1227 | * us from recursively trying to free more memory as we're | |
1228 | * trying to free the first piece of memory in the first place). | |
1229 | */ | |
930d9152 | 1230 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
1da177e4 LT |
1231 | |
1232 | order = 0; | |
1233 | for ( ; ; ) { | |
1234 | unsigned long new_order; | |
3e1d1d28 CL |
1235 | |
1236 | try_to_freeze(); | |
1da177e4 LT |
1237 | |
1238 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
1239 | new_order = pgdat->kswapd_max_order; | |
1240 | pgdat->kswapd_max_order = 0; | |
1241 | if (order < new_order) { | |
1242 | /* | |
1243 | * Don't sleep if someone wants a larger 'order' | |
1244 | * allocation | |
1245 | */ | |
1246 | order = new_order; | |
1247 | } else { | |
1248 | schedule(); | |
1249 | order = pgdat->kswapd_max_order; | |
1250 | } | |
1251 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1252 | ||
d6277db4 | 1253 | balance_pgdat(pgdat, order); |
1da177e4 LT |
1254 | } |
1255 | return 0; | |
1256 | } | |
1257 | ||
1258 | /* | |
1259 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1260 | */ | |
1261 | void wakeup_kswapd(struct zone *zone, int order) | |
1262 | { | |
1263 | pg_data_t *pgdat; | |
1264 | ||
f3fe6512 | 1265 | if (!populated_zone(zone)) |
1da177e4 LT |
1266 | return; |
1267 | ||
1268 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1269 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1270 | return; |
1271 | if (pgdat->kswapd_max_order < order) | |
1272 | pgdat->kswapd_max_order = order; | |
9bf2229f | 1273 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 | 1274 | return; |
8d0986e2 | 1275 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1276 | return; |
8d0986e2 | 1277 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1278 | } |
1279 | ||
1280 | #ifdef CONFIG_PM | |
1281 | /* | |
d6277db4 RW |
1282 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1283 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1284 | * number of reclaimed pages | |
1285 | * | |
1286 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1287 | */ | |
1288 | static unsigned long shrink_all_zones(unsigned long nr_pages, int pass, | |
1289 | int prio, struct scan_control *sc) | |
1290 | { | |
1291 | struct zone *zone; | |
1292 | unsigned long nr_to_scan, ret = 0; | |
1293 | ||
1294 | for_each_zone(zone) { | |
1295 | ||
1296 | if (!populated_zone(zone)) | |
1297 | continue; | |
1298 | ||
1299 | if (zone->all_unreclaimable && prio != DEF_PRIORITY) | |
1300 | continue; | |
1301 | ||
1302 | /* For pass = 0 we don't shrink the active list */ | |
1303 | if (pass > 0) { | |
1304 | zone->nr_scan_active += (zone->nr_active >> prio) + 1; | |
1305 | if (zone->nr_scan_active >= nr_pages || pass > 3) { | |
1306 | zone->nr_scan_active = 0; | |
1307 | nr_to_scan = min(nr_pages, zone->nr_active); | |
1308 | shrink_active_list(nr_to_scan, zone, sc); | |
1309 | } | |
1310 | } | |
1311 | ||
1312 | zone->nr_scan_inactive += (zone->nr_inactive >> prio) + 1; | |
1313 | if (zone->nr_scan_inactive >= nr_pages || pass > 3) { | |
1314 | zone->nr_scan_inactive = 0; | |
1315 | nr_to_scan = min(nr_pages, zone->nr_inactive); | |
1316 | ret += shrink_inactive_list(nr_to_scan, zone, sc); | |
1317 | if (ret >= nr_pages) | |
1318 | return ret; | |
1319 | } | |
1320 | } | |
1321 | ||
1322 | return ret; | |
1323 | } | |
1324 | ||
1325 | /* | |
1326 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
1327 | * freed pages. | |
1328 | * | |
1329 | * Rather than trying to age LRUs the aim is to preserve the overall | |
1330 | * LRU order by reclaiming preferentially | |
1331 | * inactive > active > active referenced > active mapped | |
1da177e4 | 1332 | */ |
69e05944 | 1333 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 1334 | { |
d6277db4 | 1335 | unsigned long lru_pages, nr_slab; |
69e05944 | 1336 | unsigned long ret = 0; |
d6277db4 RW |
1337 | int pass; |
1338 | struct reclaim_state reclaim_state; | |
1339 | struct zone *zone; | |
1340 | struct scan_control sc = { | |
1341 | .gfp_mask = GFP_KERNEL, | |
1342 | .may_swap = 0, | |
1343 | .swap_cluster_max = nr_pages, | |
1344 | .may_writepage = 1, | |
1345 | .swappiness = vm_swappiness, | |
1da177e4 LT |
1346 | }; |
1347 | ||
1348 | current->reclaim_state = &reclaim_state; | |
69e05944 | 1349 | |
d6277db4 RW |
1350 | lru_pages = 0; |
1351 | for_each_zone(zone) | |
1352 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1353 | ||
1354 | nr_slab = read_page_state(nr_slab); | |
1355 | /* If slab caches are huge, it's better to hit them first */ | |
1356 | while (nr_slab >= lru_pages) { | |
1357 | reclaim_state.reclaimed_slab = 0; | |
1358 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1359 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 1360 | break; |
d6277db4 RW |
1361 | |
1362 | ret += reclaim_state.reclaimed_slab; | |
1363 | if (ret >= nr_pages) | |
1364 | goto out; | |
1365 | ||
1366 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 1367 | } |
d6277db4 RW |
1368 | |
1369 | /* | |
1370 | * We try to shrink LRUs in 5 passes: | |
1371 | * 0 = Reclaim from inactive_list only | |
1372 | * 1 = Reclaim from active list but don't reclaim mapped | |
1373 | * 2 = 2nd pass of type 1 | |
1374 | * 3 = Reclaim mapped (normal reclaim) | |
1375 | * 4 = 2nd pass of type 3 | |
1376 | */ | |
1377 | for (pass = 0; pass < 5; pass++) { | |
1378 | int prio; | |
1379 | ||
1380 | /* Needed for shrinking slab caches later on */ | |
1381 | if (!lru_pages) | |
1382 | for_each_zone(zone) { | |
1383 | lru_pages += zone->nr_active; | |
1384 | lru_pages += zone->nr_inactive; | |
1385 | } | |
1386 | ||
1387 | /* Force reclaiming mapped pages in the passes #3 and #4 */ | |
1388 | if (pass > 2) { | |
1389 | sc.may_swap = 1; | |
1390 | sc.swappiness = 100; | |
1391 | } | |
1392 | ||
1393 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
1394 | unsigned long nr_to_scan = nr_pages - ret; | |
1395 | ||
1396 | sc.nr_mapped = read_page_state(nr_mapped); | |
1397 | sc.nr_scanned = 0; | |
1398 | ||
1399 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); | |
1400 | if (ret >= nr_pages) | |
1401 | goto out; | |
1402 | ||
1403 | reclaim_state.reclaimed_slab = 0; | |
1404 | shrink_slab(sc.nr_scanned, sc.gfp_mask, lru_pages); | |
1405 | ret += reclaim_state.reclaimed_slab; | |
1406 | if (ret >= nr_pages) | |
1407 | goto out; | |
1408 | ||
1409 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
1410 | blk_congestion_wait(WRITE, HZ / 10); | |
1411 | } | |
1412 | ||
1413 | lru_pages = 0; | |
248a0301 | 1414 | } |
d6277db4 RW |
1415 | |
1416 | /* | |
1417 | * If ret = 0, we could not shrink LRUs, but there may be something | |
1418 | * in slab caches | |
1419 | */ | |
1420 | if (!ret) | |
1421 | do { | |
1422 | reclaim_state.reclaimed_slab = 0; | |
1423 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1424 | ret += reclaim_state.reclaimed_slab; | |
1425 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
1426 | ||
1427 | out: | |
1da177e4 | 1428 | current->reclaim_state = NULL; |
d6277db4 | 1429 | |
1da177e4 LT |
1430 | return ret; |
1431 | } | |
1432 | #endif | |
1433 | ||
1434 | #ifdef CONFIG_HOTPLUG_CPU | |
1435 | /* It's optimal to keep kswapds on the same CPUs as their memory, but | |
1436 | not required for correctness. So if the last cpu in a node goes | |
1437 | away, we get changed to run anywhere: as the first one comes back, | |
1438 | restore their cpu bindings. */ | |
83d722f7 | 1439 | static int cpu_callback(struct notifier_block *nfb, |
69e05944 | 1440 | unsigned long action, void *hcpu) |
1da177e4 LT |
1441 | { |
1442 | pg_data_t *pgdat; | |
1443 | cpumask_t mask; | |
1444 | ||
1445 | if (action == CPU_ONLINE) { | |
ec936fc5 | 1446 | for_each_online_pgdat(pgdat) { |
1da177e4 LT |
1447 | mask = node_to_cpumask(pgdat->node_id); |
1448 | if (any_online_cpu(mask) != NR_CPUS) | |
1449 | /* One of our CPUs online: restore mask */ | |
1450 | set_cpus_allowed(pgdat->kswapd, mask); | |
1451 | } | |
1452 | } | |
1453 | return NOTIFY_OK; | |
1454 | } | |
1455 | #endif /* CONFIG_HOTPLUG_CPU */ | |
1456 | ||
1457 | static int __init kswapd_init(void) | |
1458 | { | |
1459 | pg_data_t *pgdat; | |
69e05944 | 1460 | |
1da177e4 | 1461 | swap_setup(); |
ec936fc5 | 1462 | for_each_online_pgdat(pgdat) { |
69e05944 AM |
1463 | pid_t pid; |
1464 | ||
1465 | pid = kernel_thread(kswapd, pgdat, CLONE_KERNEL); | |
1466 | BUG_ON(pid < 0); | |
05eeae20 | 1467 | read_lock(&tasklist_lock); |
69e05944 | 1468 | pgdat->kswapd = find_task_by_pid(pid); |
05eeae20 | 1469 | read_unlock(&tasklist_lock); |
69e05944 | 1470 | } |
1da177e4 LT |
1471 | total_memory = nr_free_pagecache_pages(); |
1472 | hotcpu_notifier(cpu_callback, 0); | |
1473 | return 0; | |
1474 | } | |
1475 | ||
1476 | module_init(kswapd_init) | |
9eeff239 CL |
1477 | |
1478 | #ifdef CONFIG_NUMA | |
1479 | /* | |
1480 | * Zone reclaim mode | |
1481 | * | |
1482 | * If non-zero call zone_reclaim when the number of free pages falls below | |
1483 | * the watermarks. | |
1484 | * | |
1485 | * In the future we may add flags to the mode. However, the page allocator | |
1486 | * should only have to check that zone_reclaim_mode != 0 before calling | |
1487 | * zone_reclaim(). | |
1488 | */ | |
1489 | int zone_reclaim_mode __read_mostly; | |
1490 | ||
1b2ffb78 CL |
1491 | #define RECLAIM_OFF 0 |
1492 | #define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */ | |
1493 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ | |
1494 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2a16e3f4 | 1495 | #define RECLAIM_SLAB (1<<3) /* Do a global slab shrink if the zone is out of memory */ |
1b2ffb78 | 1496 | |
9eeff239 CL |
1497 | /* |
1498 | * Mininum time between zone reclaim scans | |
1499 | */ | |
2a11ff06 | 1500 | int zone_reclaim_interval __read_mostly = 30*HZ; |
a92f7126 CL |
1501 | |
1502 | /* | |
1503 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
1504 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
1505 | * a zone. | |
1506 | */ | |
1507 | #define ZONE_RECLAIM_PRIORITY 4 | |
1508 | ||
9eeff239 CL |
1509 | /* |
1510 | * Try to free up some pages from this zone through reclaim. | |
1511 | */ | |
179e9639 | 1512 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 1513 | { |
7fb2d46d | 1514 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 1515 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
1516 | struct task_struct *p = current; |
1517 | struct reclaim_state reclaim_state; | |
8695949a | 1518 | int priority; |
05ff5137 | 1519 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
1520 | struct scan_control sc = { |
1521 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
1522 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
1523 | .nr_mapped = read_page_state(nr_mapped), | |
69e05944 AM |
1524 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
1525 | SWAP_CLUSTER_MAX), | |
179e9639 | 1526 | .gfp_mask = gfp_mask, |
d6277db4 | 1527 | .swappiness = vm_swappiness, |
179e9639 | 1528 | }; |
9eeff239 CL |
1529 | |
1530 | disable_swap_token(); | |
9eeff239 | 1531 | cond_resched(); |
d4f7796e CL |
1532 | /* |
1533 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
1534 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
1535 | * and RECLAIM_SWAP. | |
1536 | */ | |
1537 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
1538 | reclaim_state.reclaimed_slab = 0; |
1539 | p->reclaim_state = &reclaim_state; | |
c84db23c | 1540 | |
a92f7126 CL |
1541 | /* |
1542 | * Free memory by calling shrink zone with increasing priorities | |
1543 | * until we have enough memory freed. | |
1544 | */ | |
8695949a | 1545 | priority = ZONE_RECLAIM_PRIORITY; |
a92f7126 | 1546 | do { |
05ff5137 | 1547 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
8695949a | 1548 | priority--; |
05ff5137 | 1549 | } while (priority >= 0 && nr_reclaimed < nr_pages); |
c84db23c | 1550 | |
05ff5137 | 1551 | if (nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) { |
2a16e3f4 | 1552 | /* |
7fb2d46d CL |
1553 | * shrink_slab() does not currently allow us to determine how |
1554 | * many pages were freed in this zone. So we just shake the slab | |
1555 | * a bit and then go off node for this particular allocation | |
1556 | * despite possibly having freed enough memory to allocate in | |
1557 | * this zone. If we freed local memory then the next | |
1558 | * allocations will be local again. | |
2a16e3f4 CL |
1559 | * |
1560 | * shrink_slab will free memory on all zones and may take | |
1561 | * a long time. | |
1562 | */ | |
1563 | shrink_slab(sc.nr_scanned, gfp_mask, order); | |
2a16e3f4 CL |
1564 | } |
1565 | ||
9eeff239 | 1566 | p->reclaim_state = NULL; |
d4f7796e | 1567 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
9eeff239 | 1568 | |
7fb2d46d CL |
1569 | if (nr_reclaimed == 0) { |
1570 | /* | |
1571 | * We were unable to reclaim enough pages to stay on node. We | |
1572 | * now allow off node accesses for a certain time period before | |
1573 | * trying again to reclaim pages from the local zone. | |
1574 | */ | |
9eeff239 | 1575 | zone->last_unsuccessful_zone_reclaim = jiffies; |
7fb2d46d | 1576 | } |
9eeff239 | 1577 | |
05ff5137 | 1578 | return nr_reclaimed >= nr_pages; |
9eeff239 | 1579 | } |
179e9639 AM |
1580 | |
1581 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
1582 | { | |
1583 | cpumask_t mask; | |
1584 | int node_id; | |
1585 | ||
1586 | /* | |
1587 | * Do not reclaim if there was a recent unsuccessful attempt at zone | |
1588 | * reclaim. In that case we let allocations go off node for the | |
1589 | * zone_reclaim_interval. Otherwise we would scan for each off-node | |
1590 | * page allocation. | |
1591 | */ | |
1592 | if (time_before(jiffies, | |
1593 | zone->last_unsuccessful_zone_reclaim + zone_reclaim_interval)) | |
1594 | return 0; | |
1595 | ||
1596 | /* | |
1597 | * Avoid concurrent zone reclaims, do not reclaim in a zone that does | |
1598 | * not have reclaimable pages and if we should not delay the allocation | |
1599 | * then do not scan. | |
1600 | */ | |
1601 | if (!(gfp_mask & __GFP_WAIT) || | |
1602 | zone->all_unreclaimable || | |
1603 | atomic_read(&zone->reclaim_in_progress) > 0 || | |
1604 | (current->flags & PF_MEMALLOC)) | |
1605 | return 0; | |
1606 | ||
1607 | /* | |
1608 | * Only run zone reclaim on the local zone or on zones that do not | |
1609 | * have associated processors. This will favor the local processor | |
1610 | * over remote processors and spread off node memory allocations | |
1611 | * as wide as possible. | |
1612 | */ | |
1613 | node_id = zone->zone_pgdat->node_id; | |
1614 | mask = node_to_cpumask(node_id); | |
1615 | if (!cpus_empty(mask) && node_id != numa_node_id()) | |
1616 | return 0; | |
1617 | return __zone_reclaim(zone, gfp_mask, order); | |
1618 | } | |
9eeff239 | 1619 | #endif |