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> |
3218ae14 | 37 | #include <linux/kthread.h> |
1da177e4 LT |
38 | |
39 | #include <asm/tlbflush.h> | |
40 | #include <asm/div64.h> | |
41 | ||
42 | #include <linux/swapops.h> | |
43 | ||
0f8053a5 NP |
44 | #include "internal.h" |
45 | ||
1da177e4 | 46 | struct scan_control { |
1da177e4 LT |
47 | /* Incremented by the number of inactive pages that were scanned */ |
48 | unsigned long nr_scanned; | |
49 | ||
1da177e4 | 50 | /* This context's GFP mask */ |
6daa0e28 | 51 | gfp_t gfp_mask; |
1da177e4 LT |
52 | |
53 | int may_writepage; | |
54 | ||
f1fd1067 CL |
55 | /* Can pages be swapped as part of reclaim? */ |
56 | int may_swap; | |
57 | ||
1da177e4 LT |
58 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
59 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
60 | * In this context, it doesn't matter that we scan the | |
61 | * whole list at once. */ | |
62 | int swap_cluster_max; | |
d6277db4 RW |
63 | |
64 | int swappiness; | |
408d8544 NP |
65 | |
66 | int all_unreclaimable; | |
1da177e4 LT |
67 | }; |
68 | ||
69 | /* | |
70 | * The list of shrinker callbacks used by to apply pressure to | |
71 | * ageable caches. | |
72 | */ | |
73 | struct shrinker { | |
74 | shrinker_t shrinker; | |
75 | struct list_head list; | |
76 | int seeks; /* seeks to recreate an obj */ | |
77 | long nr; /* objs pending delete */ | |
78 | }; | |
79 | ||
80 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
81 | ||
82 | #ifdef ARCH_HAS_PREFETCH | |
83 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
84 | do { \ | |
85 | if ((_page)->lru.prev != _base) { \ | |
86 | struct page *prev; \ | |
87 | \ | |
88 | prev = lru_to_page(&(_page->lru)); \ | |
89 | prefetch(&prev->_field); \ | |
90 | } \ | |
91 | } while (0) | |
92 | #else | |
93 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
94 | #endif | |
95 | ||
96 | #ifdef ARCH_HAS_PREFETCHW | |
97 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
98 | do { \ | |
99 | if ((_page)->lru.prev != _base) { \ | |
100 | struct page *prev; \ | |
101 | \ | |
102 | prev = lru_to_page(&(_page->lru)); \ | |
103 | prefetchw(&prev->_field); \ | |
104 | } \ | |
105 | } while (0) | |
106 | #else | |
107 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
108 | #endif | |
109 | ||
110 | /* | |
111 | * From 0 .. 100. Higher means more swappy. | |
112 | */ | |
113 | int vm_swappiness = 60; | |
bd1e22b8 | 114 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
115 | |
116 | static LIST_HEAD(shrinker_list); | |
117 | static DECLARE_RWSEM(shrinker_rwsem); | |
118 | ||
119 | /* | |
120 | * Add a shrinker callback to be called from the vm | |
121 | */ | |
122 | struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker) | |
123 | { | |
124 | struct shrinker *shrinker; | |
125 | ||
126 | shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL); | |
127 | if (shrinker) { | |
128 | shrinker->shrinker = theshrinker; | |
129 | shrinker->seeks = seeks; | |
130 | shrinker->nr = 0; | |
131 | down_write(&shrinker_rwsem); | |
132 | list_add_tail(&shrinker->list, &shrinker_list); | |
133 | up_write(&shrinker_rwsem); | |
134 | } | |
135 | return shrinker; | |
136 | } | |
137 | EXPORT_SYMBOL(set_shrinker); | |
138 | ||
139 | /* | |
140 | * Remove one | |
141 | */ | |
142 | void remove_shrinker(struct shrinker *shrinker) | |
143 | { | |
144 | down_write(&shrinker_rwsem); | |
145 | list_del(&shrinker->list); | |
146 | up_write(&shrinker_rwsem); | |
147 | kfree(shrinker); | |
148 | } | |
149 | EXPORT_SYMBOL(remove_shrinker); | |
150 | ||
151 | #define SHRINK_BATCH 128 | |
152 | /* | |
153 | * Call the shrink functions to age shrinkable caches | |
154 | * | |
155 | * Here we assume it costs one seek to replace a lru page and that it also | |
156 | * takes a seek to recreate a cache object. With this in mind we age equal | |
157 | * percentages of the lru and ageable caches. This should balance the seeks | |
158 | * generated by these structures. | |
159 | * | |
160 | * If the vm encounted mapped pages on the LRU it increase the pressure on | |
161 | * slab to avoid swapping. | |
162 | * | |
163 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
164 | * | |
165 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
166 | * are eligible for the caller's allocation attempt. It is used for balancing | |
167 | * slab reclaim versus page reclaim. | |
b15e0905 | 168 | * |
169 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 170 | */ |
69e05944 AM |
171 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
172 | unsigned long lru_pages) | |
1da177e4 LT |
173 | { |
174 | struct shrinker *shrinker; | |
69e05944 | 175 | unsigned long ret = 0; |
1da177e4 LT |
176 | |
177 | if (scanned == 0) | |
178 | scanned = SWAP_CLUSTER_MAX; | |
179 | ||
180 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 181 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
182 | |
183 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
184 | unsigned long long delta; | |
185 | unsigned long total_scan; | |
ea164d73 | 186 | unsigned long max_pass = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
187 | |
188 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 189 | delta *= max_pass; |
1da177e4 LT |
190 | do_div(delta, lru_pages + 1); |
191 | shrinker->nr += delta; | |
ea164d73 AA |
192 | if (shrinker->nr < 0) { |
193 | printk(KERN_ERR "%s: nr=%ld\n", | |
194 | __FUNCTION__, shrinker->nr); | |
195 | shrinker->nr = max_pass; | |
196 | } | |
197 | ||
198 | /* | |
199 | * Avoid risking looping forever due to too large nr value: | |
200 | * never try to free more than twice the estimate number of | |
201 | * freeable entries. | |
202 | */ | |
203 | if (shrinker->nr > max_pass * 2) | |
204 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
205 | |
206 | total_scan = shrinker->nr; | |
207 | shrinker->nr = 0; | |
208 | ||
209 | while (total_scan >= SHRINK_BATCH) { | |
210 | long this_scan = SHRINK_BATCH; | |
211 | int shrink_ret; | |
b15e0905 | 212 | int nr_before; |
1da177e4 | 213 | |
b15e0905 | 214 | nr_before = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
215 | shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask); |
216 | if (shrink_ret == -1) | |
217 | break; | |
b15e0905 | 218 | if (shrink_ret < nr_before) |
219 | ret += nr_before - shrink_ret; | |
f8891e5e | 220 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
221 | total_scan -= this_scan; |
222 | ||
223 | cond_resched(); | |
224 | } | |
225 | ||
226 | shrinker->nr += total_scan; | |
227 | } | |
228 | up_read(&shrinker_rwsem); | |
b15e0905 | 229 | return ret; |
1da177e4 LT |
230 | } |
231 | ||
232 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
233 | static inline int page_mapping_inuse(struct page *page) | |
234 | { | |
235 | struct address_space *mapping; | |
236 | ||
237 | /* Page is in somebody's page tables. */ | |
238 | if (page_mapped(page)) | |
239 | return 1; | |
240 | ||
241 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
242 | if (PageSwapCache(page)) | |
243 | return 1; | |
244 | ||
245 | mapping = page_mapping(page); | |
246 | if (!mapping) | |
247 | return 0; | |
248 | ||
249 | /* File is mmap'd by somebody? */ | |
250 | return mapping_mapped(mapping); | |
251 | } | |
252 | ||
253 | static inline int is_page_cache_freeable(struct page *page) | |
254 | { | |
255 | return page_count(page) - !!PagePrivate(page) == 2; | |
256 | } | |
257 | ||
258 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
259 | { | |
930d9152 | 260 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
261 | return 1; |
262 | if (!bdi_write_congested(bdi)) | |
263 | return 1; | |
264 | if (bdi == current->backing_dev_info) | |
265 | return 1; | |
266 | return 0; | |
267 | } | |
268 | ||
269 | /* | |
270 | * We detected a synchronous write error writing a page out. Probably | |
271 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
272 | * fsync(), msync() or close(). | |
273 | * | |
274 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
275 | * prevents it from being freed up. But we have a ref on the page and once | |
276 | * that page is locked, the mapping is pinned. | |
277 | * | |
278 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
279 | * __GFP_FS. | |
280 | */ | |
281 | static void handle_write_error(struct address_space *mapping, | |
282 | struct page *page, int error) | |
283 | { | |
284 | lock_page(page); | |
285 | if (page_mapping(page) == mapping) { | |
286 | if (error == -ENOSPC) | |
287 | set_bit(AS_ENOSPC, &mapping->flags); | |
288 | else | |
289 | set_bit(AS_EIO, &mapping->flags); | |
290 | } | |
291 | unlock_page(page); | |
292 | } | |
293 | ||
04e62a29 CL |
294 | /* possible outcome of pageout() */ |
295 | typedef enum { | |
296 | /* failed to write page out, page is locked */ | |
297 | PAGE_KEEP, | |
298 | /* move page to the active list, page is locked */ | |
299 | PAGE_ACTIVATE, | |
300 | /* page has been sent to the disk successfully, page is unlocked */ | |
301 | PAGE_SUCCESS, | |
302 | /* page is clean and locked */ | |
303 | PAGE_CLEAN, | |
304 | } pageout_t; | |
305 | ||
1da177e4 | 306 | /* |
1742f19f AM |
307 | * pageout is called by shrink_page_list() for each dirty page. |
308 | * Calls ->writepage(). | |
1da177e4 | 309 | */ |
04e62a29 | 310 | static pageout_t pageout(struct page *page, struct address_space *mapping) |
1da177e4 LT |
311 | { |
312 | /* | |
313 | * If the page is dirty, only perform writeback if that write | |
314 | * will be non-blocking. To prevent this allocation from being | |
315 | * stalled by pagecache activity. But note that there may be | |
316 | * stalls if we need to run get_block(). We could test | |
317 | * PagePrivate for that. | |
318 | * | |
319 | * If this process is currently in generic_file_write() against | |
320 | * this page's queue, we can perform writeback even if that | |
321 | * will block. | |
322 | * | |
323 | * If the page is swapcache, write it back even if that would | |
324 | * block, for some throttling. This happens by accident, because | |
325 | * swap_backing_dev_info is bust: it doesn't reflect the | |
326 | * congestion state of the swapdevs. Easy to fix, if needed. | |
327 | * See swapfile.c:page_queue_congested(). | |
328 | */ | |
329 | if (!is_page_cache_freeable(page)) | |
330 | return PAGE_KEEP; | |
331 | if (!mapping) { | |
332 | /* | |
333 | * Some data journaling orphaned pages can have | |
334 | * page->mapping == NULL while being dirty with clean buffers. | |
335 | */ | |
323aca6c | 336 | if (PagePrivate(page)) { |
1da177e4 LT |
337 | if (try_to_free_buffers(page)) { |
338 | ClearPageDirty(page); | |
339 | printk("%s: orphaned page\n", __FUNCTION__); | |
340 | return PAGE_CLEAN; | |
341 | } | |
342 | } | |
343 | return PAGE_KEEP; | |
344 | } | |
345 | if (mapping->a_ops->writepage == NULL) | |
346 | return PAGE_ACTIVATE; | |
347 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
348 | return PAGE_KEEP; | |
349 | ||
350 | if (clear_page_dirty_for_io(page)) { | |
351 | int res; | |
352 | struct writeback_control wbc = { | |
353 | .sync_mode = WB_SYNC_NONE, | |
354 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
355 | .range_start = 0, |
356 | .range_end = LLONG_MAX, | |
1da177e4 LT |
357 | .nonblocking = 1, |
358 | .for_reclaim = 1, | |
359 | }; | |
360 | ||
361 | SetPageReclaim(page); | |
362 | res = mapping->a_ops->writepage(page, &wbc); | |
363 | if (res < 0) | |
364 | handle_write_error(mapping, page, res); | |
994fc28c | 365 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
366 | ClearPageReclaim(page); |
367 | return PAGE_ACTIVATE; | |
368 | } | |
369 | if (!PageWriteback(page)) { | |
370 | /* synchronous write or broken a_ops? */ | |
371 | ClearPageReclaim(page); | |
372 | } | |
373 | ||
374 | return PAGE_SUCCESS; | |
375 | } | |
376 | ||
377 | return PAGE_CLEAN; | |
378 | } | |
379 | ||
b20a3503 | 380 | int remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 381 | { |
28e4d965 NP |
382 | BUG_ON(!PageLocked(page)); |
383 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc CL |
384 | |
385 | write_lock_irq(&mapping->tree_lock); | |
386 | ||
387 | /* | |
388 | * The non-racy check for busy page. It is critical to check | |
389 | * PageDirty _after_ making sure that the page is freeable and | |
390 | * not in use by anybody. (pagecache + us == 2) | |
391 | */ | |
392 | if (unlikely(page_count(page) != 2)) | |
393 | goto cannot_free; | |
394 | smp_rmb(); | |
395 | if (unlikely(PageDirty(page))) | |
396 | goto cannot_free; | |
397 | ||
398 | if (PageSwapCache(page)) { | |
399 | swp_entry_t swap = { .val = page_private(page) }; | |
400 | __delete_from_swap_cache(page); | |
401 | write_unlock_irq(&mapping->tree_lock); | |
402 | swap_free(swap); | |
403 | __put_page(page); /* The pagecache ref */ | |
404 | return 1; | |
405 | } | |
406 | ||
407 | __remove_from_page_cache(page); | |
408 | write_unlock_irq(&mapping->tree_lock); | |
409 | __put_page(page); | |
410 | return 1; | |
411 | ||
412 | cannot_free: | |
413 | write_unlock_irq(&mapping->tree_lock); | |
414 | return 0; | |
415 | } | |
416 | ||
1da177e4 | 417 | /* |
1742f19f | 418 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 419 | */ |
1742f19f AM |
420 | static unsigned long shrink_page_list(struct list_head *page_list, |
421 | struct scan_control *sc) | |
1da177e4 LT |
422 | { |
423 | LIST_HEAD(ret_pages); | |
424 | struct pagevec freed_pvec; | |
425 | int pgactivate = 0; | |
05ff5137 | 426 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
427 | |
428 | cond_resched(); | |
429 | ||
430 | pagevec_init(&freed_pvec, 1); | |
431 | while (!list_empty(page_list)) { | |
432 | struct address_space *mapping; | |
433 | struct page *page; | |
434 | int may_enter_fs; | |
435 | int referenced; | |
436 | ||
437 | cond_resched(); | |
438 | ||
439 | page = lru_to_page(page_list); | |
440 | list_del(&page->lru); | |
441 | ||
442 | if (TestSetPageLocked(page)) | |
443 | goto keep; | |
444 | ||
725d704e | 445 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
446 | |
447 | sc->nr_scanned++; | |
80e43426 CL |
448 | |
449 | if (!sc->may_swap && page_mapped(page)) | |
450 | goto keep_locked; | |
451 | ||
1da177e4 LT |
452 | /* Double the slab pressure for mapped and swapcache pages */ |
453 | if (page_mapped(page) || PageSwapCache(page)) | |
454 | sc->nr_scanned++; | |
455 | ||
456 | if (PageWriteback(page)) | |
457 | goto keep_locked; | |
458 | ||
f7b7fd8f | 459 | referenced = page_referenced(page, 1); |
1da177e4 LT |
460 | /* In active use or really unfreeable? Activate it. */ |
461 | if (referenced && page_mapping_inuse(page)) | |
462 | goto activate_locked; | |
463 | ||
464 | #ifdef CONFIG_SWAP | |
465 | /* | |
466 | * Anonymous process memory has backing store? | |
467 | * Try to allocate it some swap space here. | |
468 | */ | |
6e5ef1a9 | 469 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 470 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 471 | goto activate_locked; |
1da177e4 LT |
472 | #endif /* CONFIG_SWAP */ |
473 | ||
474 | mapping = page_mapping(page); | |
475 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || | |
476 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
477 | ||
478 | /* | |
479 | * The page is mapped into the page tables of one or more | |
480 | * processes. Try to unmap it here. | |
481 | */ | |
482 | if (page_mapped(page) && mapping) { | |
a48d07af | 483 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
484 | case SWAP_FAIL: |
485 | goto activate_locked; | |
486 | case SWAP_AGAIN: | |
487 | goto keep_locked; | |
488 | case SWAP_SUCCESS: | |
489 | ; /* try to free the page below */ | |
490 | } | |
491 | } | |
492 | ||
493 | if (PageDirty(page)) { | |
494 | if (referenced) | |
495 | goto keep_locked; | |
496 | if (!may_enter_fs) | |
497 | goto keep_locked; | |
52a8363e | 498 | if (!sc->may_writepage) |
1da177e4 LT |
499 | goto keep_locked; |
500 | ||
501 | /* Page is dirty, try to write it out here */ | |
502 | switch(pageout(page, mapping)) { | |
503 | case PAGE_KEEP: | |
504 | goto keep_locked; | |
505 | case PAGE_ACTIVATE: | |
506 | goto activate_locked; | |
507 | case PAGE_SUCCESS: | |
508 | if (PageWriteback(page) || PageDirty(page)) | |
509 | goto keep; | |
510 | /* | |
511 | * A synchronous write - probably a ramdisk. Go | |
512 | * ahead and try to reclaim the page. | |
513 | */ | |
514 | if (TestSetPageLocked(page)) | |
515 | goto keep; | |
516 | if (PageDirty(page) || PageWriteback(page)) | |
517 | goto keep_locked; | |
518 | mapping = page_mapping(page); | |
519 | case PAGE_CLEAN: | |
520 | ; /* try to free the page below */ | |
521 | } | |
522 | } | |
523 | ||
524 | /* | |
525 | * If the page has buffers, try to free the buffer mappings | |
526 | * associated with this page. If we succeed we try to free | |
527 | * the page as well. | |
528 | * | |
529 | * We do this even if the page is PageDirty(). | |
530 | * try_to_release_page() does not perform I/O, but it is | |
531 | * possible for a page to have PageDirty set, but it is actually | |
532 | * clean (all its buffers are clean). This happens if the | |
533 | * buffers were written out directly, with submit_bh(). ext3 | |
534 | * will do this, as well as the blockdev mapping. | |
535 | * try_to_release_page() will discover that cleanness and will | |
536 | * drop the buffers and mark the page clean - it can be freed. | |
537 | * | |
538 | * Rarely, pages can have buffers and no ->mapping. These are | |
539 | * the pages which were not successfully invalidated in | |
540 | * truncate_complete_page(). We try to drop those buffers here | |
541 | * and if that worked, and the page is no longer mapped into | |
542 | * process address space (page_count == 1) it can be freed. | |
543 | * Otherwise, leave the page on the LRU so it is swappable. | |
544 | */ | |
545 | if (PagePrivate(page)) { | |
546 | if (!try_to_release_page(page, sc->gfp_mask)) | |
547 | goto activate_locked; | |
548 | if (!mapping && page_count(page) == 1) | |
549 | goto free_it; | |
550 | } | |
551 | ||
28e4d965 | 552 | if (!mapping || !remove_mapping(mapping, page)) |
49d2e9cc | 553 | goto keep_locked; |
1da177e4 LT |
554 | |
555 | free_it: | |
556 | unlock_page(page); | |
05ff5137 | 557 | nr_reclaimed++; |
1da177e4 LT |
558 | if (!pagevec_add(&freed_pvec, page)) |
559 | __pagevec_release_nonlru(&freed_pvec); | |
560 | continue; | |
561 | ||
562 | activate_locked: | |
563 | SetPageActive(page); | |
564 | pgactivate++; | |
565 | keep_locked: | |
566 | unlock_page(page); | |
567 | keep: | |
568 | list_add(&page->lru, &ret_pages); | |
725d704e | 569 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
570 | } |
571 | list_splice(&ret_pages, page_list); | |
572 | if (pagevec_count(&freed_pvec)) | |
573 | __pagevec_release_nonlru(&freed_pvec); | |
f8891e5e | 574 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 575 | return nr_reclaimed; |
1da177e4 LT |
576 | } |
577 | ||
578 | /* | |
579 | * zone->lru_lock is heavily contended. Some of the functions that | |
580 | * shrink the lists perform better by taking out a batch of pages | |
581 | * and working on them outside the LRU lock. | |
582 | * | |
583 | * For pagecache intensive workloads, this function is the hottest | |
584 | * spot in the kernel (apart from copy_*_user functions). | |
585 | * | |
586 | * Appropriate locks must be held before calling this function. | |
587 | * | |
588 | * @nr_to_scan: The number of pages to look through on the list. | |
589 | * @src: The LRU list to pull pages off. | |
590 | * @dst: The temp list to put pages on to. | |
591 | * @scanned: The number of pages that were scanned. | |
592 | * | |
593 | * returns how many pages were moved onto *@dst. | |
594 | */ | |
69e05944 AM |
595 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
596 | struct list_head *src, struct list_head *dst, | |
597 | unsigned long *scanned) | |
1da177e4 | 598 | { |
69e05944 | 599 | unsigned long nr_taken = 0; |
1da177e4 | 600 | struct page *page; |
c9b02d97 | 601 | unsigned long scan; |
1da177e4 | 602 | |
c9b02d97 | 603 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
7c8ee9a8 | 604 | struct list_head *target; |
1da177e4 LT |
605 | page = lru_to_page(src); |
606 | prefetchw_prev_lru_page(page, src, flags); | |
607 | ||
725d704e | 608 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 609 | |
053837fc | 610 | list_del(&page->lru); |
7c8ee9a8 NP |
611 | target = src; |
612 | if (likely(get_page_unless_zero(page))) { | |
053837fc | 613 | /* |
7c8ee9a8 NP |
614 | * Be careful not to clear PageLRU until after we're |
615 | * sure the page is not being freed elsewhere -- the | |
616 | * page release code relies on it. | |
053837fc | 617 | */ |
7c8ee9a8 NP |
618 | ClearPageLRU(page); |
619 | target = dst; | |
620 | nr_taken++; | |
621 | } /* else it is being freed elsewhere */ | |
46453a6e | 622 | |
7c8ee9a8 | 623 | list_add(&page->lru, target); |
1da177e4 LT |
624 | } |
625 | ||
626 | *scanned = scan; | |
627 | return nr_taken; | |
628 | } | |
629 | ||
630 | /* | |
1742f19f AM |
631 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
632 | * of reclaimed pages | |
1da177e4 | 633 | */ |
1742f19f AM |
634 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
635 | struct zone *zone, struct scan_control *sc) | |
1da177e4 LT |
636 | { |
637 | LIST_HEAD(page_list); | |
638 | struct pagevec pvec; | |
69e05944 | 639 | unsigned long nr_scanned = 0; |
05ff5137 | 640 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
641 | |
642 | pagevec_init(&pvec, 1); | |
643 | ||
644 | lru_add_drain(); | |
645 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 646 | do { |
1da177e4 | 647 | struct page *page; |
69e05944 AM |
648 | unsigned long nr_taken; |
649 | unsigned long nr_scan; | |
650 | unsigned long nr_freed; | |
1da177e4 LT |
651 | |
652 | nr_taken = isolate_lru_pages(sc->swap_cluster_max, | |
653 | &zone->inactive_list, | |
654 | &page_list, &nr_scan); | |
655 | zone->nr_inactive -= nr_taken; | |
656 | zone->pages_scanned += nr_scan; | |
657 | spin_unlock_irq(&zone->lru_lock); | |
658 | ||
69e05944 | 659 | nr_scanned += nr_scan; |
1742f19f | 660 | nr_freed = shrink_page_list(&page_list, sc); |
05ff5137 | 661 | nr_reclaimed += nr_freed; |
a74609fa NP |
662 | local_irq_disable(); |
663 | if (current_is_kswapd()) { | |
f8891e5e CL |
664 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
665 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
a74609fa | 666 | } else |
f8891e5e CL |
667 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
668 | __count_vm_events(PGACTIVATE, nr_freed); | |
a74609fa | 669 | |
fb8d14e1 WF |
670 | if (nr_taken == 0) |
671 | goto done; | |
672 | ||
a74609fa | 673 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
674 | /* |
675 | * Put back any unfreeable pages. | |
676 | */ | |
677 | while (!list_empty(&page_list)) { | |
678 | page = lru_to_page(&page_list); | |
725d704e | 679 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 680 | SetPageLRU(page); |
1da177e4 LT |
681 | list_del(&page->lru); |
682 | if (PageActive(page)) | |
683 | add_page_to_active_list(zone, page); | |
684 | else | |
685 | add_page_to_inactive_list(zone, page); | |
686 | if (!pagevec_add(&pvec, page)) { | |
687 | spin_unlock_irq(&zone->lru_lock); | |
688 | __pagevec_release(&pvec); | |
689 | spin_lock_irq(&zone->lru_lock); | |
690 | } | |
691 | } | |
69e05944 | 692 | } while (nr_scanned < max_scan); |
fb8d14e1 | 693 | spin_unlock(&zone->lru_lock); |
1da177e4 | 694 | done: |
fb8d14e1 | 695 | local_irq_enable(); |
1da177e4 | 696 | pagevec_release(&pvec); |
05ff5137 | 697 | return nr_reclaimed; |
1da177e4 LT |
698 | } |
699 | ||
4ff1ffb4 NP |
700 | static inline int zone_is_near_oom(struct zone *zone) |
701 | { | |
702 | return zone->pages_scanned >= (zone->nr_active + zone->nr_inactive)*3; | |
703 | } | |
704 | ||
1da177e4 LT |
705 | /* |
706 | * This moves pages from the active list to the inactive list. | |
707 | * | |
708 | * We move them the other way if the page is referenced by one or more | |
709 | * processes, from rmap. | |
710 | * | |
711 | * If the pages are mostly unmapped, the processing is fast and it is | |
712 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
713 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
714 | * should drop zone->lru_lock around each page. It's impossible to balance | |
715 | * this, so instead we remove the pages from the LRU while processing them. | |
716 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
717 | * nobody will play with that bit on a non-LRU page. | |
718 | * | |
719 | * The downside is that we have to touch page->_count against each page. | |
720 | * But we had to alter page->flags anyway. | |
721 | */ | |
1742f19f AM |
722 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
723 | struct scan_control *sc) | |
1da177e4 | 724 | { |
69e05944 | 725 | unsigned long pgmoved; |
1da177e4 | 726 | int pgdeactivate = 0; |
69e05944 | 727 | unsigned long pgscanned; |
1da177e4 LT |
728 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
729 | LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ | |
730 | LIST_HEAD(l_active); /* Pages to go onto the active_list */ | |
731 | struct page *page; | |
732 | struct pagevec pvec; | |
733 | int reclaim_mapped = 0; | |
2903fb16 | 734 | |
6e5ef1a9 | 735 | if (sc->may_swap) { |
2903fb16 CL |
736 | long mapped_ratio; |
737 | long distress; | |
738 | long swap_tendency; | |
739 | ||
4ff1ffb4 NP |
740 | if (zone_is_near_oom(zone)) |
741 | goto force_reclaim_mapped; | |
742 | ||
2903fb16 CL |
743 | /* |
744 | * `distress' is a measure of how much trouble we're having | |
745 | * reclaiming pages. 0 -> no problems. 100 -> great trouble. | |
746 | */ | |
747 | distress = 100 >> zone->prev_priority; | |
748 | ||
749 | /* | |
750 | * The point of this algorithm is to decide when to start | |
751 | * reclaiming mapped memory instead of just pagecache. Work out | |
752 | * how much memory | |
753 | * is mapped. | |
754 | */ | |
f3dbd344 CL |
755 | mapped_ratio = ((global_page_state(NR_FILE_MAPPED) + |
756 | global_page_state(NR_ANON_PAGES)) * 100) / | |
bf02cf4b | 757 | vm_total_pages; |
2903fb16 CL |
758 | |
759 | /* | |
760 | * Now decide how much we really want to unmap some pages. The | |
761 | * mapped ratio is downgraded - just because there's a lot of | |
762 | * mapped memory doesn't necessarily mean that page reclaim | |
763 | * isn't succeeding. | |
764 | * | |
765 | * The distress ratio is important - we don't want to start | |
766 | * going oom. | |
767 | * | |
768 | * A 100% value of vm_swappiness overrides this algorithm | |
769 | * altogether. | |
770 | */ | |
d6277db4 | 771 | swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; |
2903fb16 CL |
772 | |
773 | /* | |
774 | * Now use this metric to decide whether to start moving mapped | |
775 | * memory onto the inactive list. | |
776 | */ | |
777 | if (swap_tendency >= 100) | |
4ff1ffb4 | 778 | force_reclaim_mapped: |
2903fb16 CL |
779 | reclaim_mapped = 1; |
780 | } | |
1da177e4 LT |
781 | |
782 | lru_add_drain(); | |
783 | spin_lock_irq(&zone->lru_lock); | |
784 | pgmoved = isolate_lru_pages(nr_pages, &zone->active_list, | |
785 | &l_hold, &pgscanned); | |
786 | zone->pages_scanned += pgscanned; | |
787 | zone->nr_active -= pgmoved; | |
788 | spin_unlock_irq(&zone->lru_lock); | |
789 | ||
1da177e4 LT |
790 | while (!list_empty(&l_hold)) { |
791 | cond_resched(); | |
792 | page = lru_to_page(&l_hold); | |
793 | list_del(&page->lru); | |
794 | if (page_mapped(page)) { | |
795 | if (!reclaim_mapped || | |
796 | (total_swap_pages == 0 && PageAnon(page)) || | |
f7b7fd8f | 797 | page_referenced(page, 0)) { |
1da177e4 LT |
798 | list_add(&page->lru, &l_active); |
799 | continue; | |
800 | } | |
801 | } | |
802 | list_add(&page->lru, &l_inactive); | |
803 | } | |
804 | ||
805 | pagevec_init(&pvec, 1); | |
806 | pgmoved = 0; | |
807 | spin_lock_irq(&zone->lru_lock); | |
808 | while (!list_empty(&l_inactive)) { | |
809 | page = lru_to_page(&l_inactive); | |
810 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 811 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 812 | SetPageLRU(page); |
725d704e | 813 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
814 | ClearPageActive(page); |
815 | ||
1da177e4 LT |
816 | list_move(&page->lru, &zone->inactive_list); |
817 | pgmoved++; | |
818 | if (!pagevec_add(&pvec, page)) { | |
819 | zone->nr_inactive += pgmoved; | |
820 | spin_unlock_irq(&zone->lru_lock); | |
821 | pgdeactivate += pgmoved; | |
822 | pgmoved = 0; | |
823 | if (buffer_heads_over_limit) | |
824 | pagevec_strip(&pvec); | |
825 | __pagevec_release(&pvec); | |
826 | spin_lock_irq(&zone->lru_lock); | |
827 | } | |
828 | } | |
829 | zone->nr_inactive += pgmoved; | |
830 | pgdeactivate += pgmoved; | |
831 | if (buffer_heads_over_limit) { | |
832 | spin_unlock_irq(&zone->lru_lock); | |
833 | pagevec_strip(&pvec); | |
834 | spin_lock_irq(&zone->lru_lock); | |
835 | } | |
836 | ||
837 | pgmoved = 0; | |
838 | while (!list_empty(&l_active)) { | |
839 | page = lru_to_page(&l_active); | |
840 | prefetchw_prev_lru_page(page, &l_active, flags); | |
725d704e | 841 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 842 | SetPageLRU(page); |
725d704e | 843 | VM_BUG_ON(!PageActive(page)); |
1da177e4 LT |
844 | list_move(&page->lru, &zone->active_list); |
845 | pgmoved++; | |
846 | if (!pagevec_add(&pvec, page)) { | |
847 | zone->nr_active += pgmoved; | |
848 | pgmoved = 0; | |
849 | spin_unlock_irq(&zone->lru_lock); | |
850 | __pagevec_release(&pvec); | |
851 | spin_lock_irq(&zone->lru_lock); | |
852 | } | |
853 | } | |
854 | zone->nr_active += pgmoved; | |
a74609fa | 855 | |
f8891e5e CL |
856 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
857 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
858 | spin_unlock_irq(&zone->lru_lock); | |
1da177e4 | 859 | |
a74609fa | 860 | pagevec_release(&pvec); |
1da177e4 LT |
861 | } |
862 | ||
863 | /* | |
864 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
865 | */ | |
05ff5137 AM |
866 | static unsigned long shrink_zone(int priority, struct zone *zone, |
867 | struct scan_control *sc) | |
1da177e4 LT |
868 | { |
869 | unsigned long nr_active; | |
870 | unsigned long nr_inactive; | |
8695949a | 871 | unsigned long nr_to_scan; |
05ff5137 | 872 | unsigned long nr_reclaimed = 0; |
1da177e4 | 873 | |
53e9a615 MH |
874 | atomic_inc(&zone->reclaim_in_progress); |
875 | ||
1da177e4 LT |
876 | /* |
877 | * Add one to `nr_to_scan' just to make sure that the kernel will | |
878 | * slowly sift through the active list. | |
879 | */ | |
8695949a | 880 | zone->nr_scan_active += (zone->nr_active >> priority) + 1; |
1da177e4 LT |
881 | nr_active = zone->nr_scan_active; |
882 | if (nr_active >= sc->swap_cluster_max) | |
883 | zone->nr_scan_active = 0; | |
884 | else | |
885 | nr_active = 0; | |
886 | ||
8695949a | 887 | zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1; |
1da177e4 LT |
888 | nr_inactive = zone->nr_scan_inactive; |
889 | if (nr_inactive >= sc->swap_cluster_max) | |
890 | zone->nr_scan_inactive = 0; | |
891 | else | |
892 | nr_inactive = 0; | |
893 | ||
1da177e4 LT |
894 | while (nr_active || nr_inactive) { |
895 | if (nr_active) { | |
8695949a | 896 | nr_to_scan = min(nr_active, |
1da177e4 | 897 | (unsigned long)sc->swap_cluster_max); |
8695949a | 898 | nr_active -= nr_to_scan; |
1742f19f | 899 | shrink_active_list(nr_to_scan, zone, sc); |
1da177e4 LT |
900 | } |
901 | ||
902 | if (nr_inactive) { | |
8695949a | 903 | nr_to_scan = min(nr_inactive, |
1da177e4 | 904 | (unsigned long)sc->swap_cluster_max); |
8695949a | 905 | nr_inactive -= nr_to_scan; |
1742f19f AM |
906 | nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, |
907 | sc); | |
1da177e4 LT |
908 | } |
909 | } | |
910 | ||
911 | throttle_vm_writeout(); | |
53e9a615 MH |
912 | |
913 | atomic_dec(&zone->reclaim_in_progress); | |
05ff5137 | 914 | return nr_reclaimed; |
1da177e4 LT |
915 | } |
916 | ||
917 | /* | |
918 | * This is the direct reclaim path, for page-allocating processes. We only | |
919 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
920 | * request. | |
921 | * | |
922 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
923 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
924 | * allocation or | |
925 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
926 | * satisfy the `incremental min' zone defense algorithm. | |
927 | * | |
928 | * Returns the number of reclaimed pages. | |
929 | * | |
930 | * If a zone is deemed to be full of pinned pages then just give it a light | |
931 | * scan then give up on it. | |
932 | */ | |
1742f19f | 933 | static unsigned long shrink_zones(int priority, struct zone **zones, |
05ff5137 | 934 | struct scan_control *sc) |
1da177e4 | 935 | { |
05ff5137 | 936 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
937 | int i; |
938 | ||
408d8544 | 939 | sc->all_unreclaimable = 1; |
1da177e4 LT |
940 | for (i = 0; zones[i] != NULL; i++) { |
941 | struct zone *zone = zones[i]; | |
942 | ||
f3fe6512 | 943 | if (!populated_zone(zone)) |
1da177e4 LT |
944 | continue; |
945 | ||
9bf2229f | 946 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
947 | continue; |
948 | ||
8695949a CL |
949 | zone->temp_priority = priority; |
950 | if (zone->prev_priority > priority) | |
951 | zone->prev_priority = priority; | |
1da177e4 | 952 | |
8695949a | 953 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
954 | continue; /* Let kswapd poll it */ |
955 | ||
408d8544 NP |
956 | sc->all_unreclaimable = 0; |
957 | ||
05ff5137 | 958 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 959 | } |
05ff5137 | 960 | return nr_reclaimed; |
1da177e4 LT |
961 | } |
962 | ||
963 | /* | |
964 | * This is the main entry point to direct page reclaim. | |
965 | * | |
966 | * If a full scan of the inactive list fails to free enough memory then we | |
967 | * are "out of memory" and something needs to be killed. | |
968 | * | |
969 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
970 | * high - the zone may be full of dirty or under-writeback pages, which this | |
971 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
972 | * hope that some of these pages can be written. But if the allocating task | |
973 | * holds filesystem locks which prevent writeout this might not work, and the | |
974 | * allocation attempt will fail. | |
975 | */ | |
69e05944 | 976 | unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask) |
1da177e4 LT |
977 | { |
978 | int priority; | |
979 | int ret = 0; | |
69e05944 | 980 | unsigned long total_scanned = 0; |
05ff5137 | 981 | unsigned long nr_reclaimed = 0; |
1da177e4 | 982 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 LT |
983 | unsigned long lru_pages = 0; |
984 | int i; | |
179e9639 AM |
985 | struct scan_control sc = { |
986 | .gfp_mask = gfp_mask, | |
987 | .may_writepage = !laptop_mode, | |
988 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
989 | .may_swap = 1, | |
d6277db4 | 990 | .swappiness = vm_swappiness, |
179e9639 | 991 | }; |
1da177e4 | 992 | |
f8891e5e | 993 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
994 | |
995 | for (i = 0; zones[i] != NULL; i++) { | |
996 | struct zone *zone = zones[i]; | |
997 | ||
9bf2229f | 998 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
999 | continue; |
1000 | ||
1001 | zone->temp_priority = DEF_PRIORITY; | |
1002 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1003 | } | |
1004 | ||
1005 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1da177e4 | 1006 | sc.nr_scanned = 0; |
f7b7fd8f RR |
1007 | if (!priority) |
1008 | disable_swap_token(); | |
1742f19f | 1009 | nr_reclaimed += shrink_zones(priority, zones, &sc); |
1da177e4 LT |
1010 | shrink_slab(sc.nr_scanned, gfp_mask, lru_pages); |
1011 | if (reclaim_state) { | |
05ff5137 | 1012 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1013 | reclaim_state->reclaimed_slab = 0; |
1014 | } | |
1015 | total_scanned += sc.nr_scanned; | |
05ff5137 | 1016 | if (nr_reclaimed >= sc.swap_cluster_max) { |
1da177e4 LT |
1017 | ret = 1; |
1018 | goto out; | |
1019 | } | |
1020 | ||
1021 | /* | |
1022 | * Try to write back as many pages as we just scanned. This | |
1023 | * tends to cause slow streaming writers to write data to the | |
1024 | * disk smoothly, at the dirtying rate, which is nice. But | |
1025 | * that's undesirable in laptop mode, where we *want* lumpy | |
1026 | * writeout. So in laptop mode, write out the whole world. | |
1027 | */ | |
179e9639 AM |
1028 | if (total_scanned > sc.swap_cluster_max + |
1029 | sc.swap_cluster_max / 2) { | |
687a21ce | 1030 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
1da177e4 LT |
1031 | sc.may_writepage = 1; |
1032 | } | |
1033 | ||
1034 | /* Take a nap, wait for some writeback to complete */ | |
1035 | if (sc.nr_scanned && priority < DEF_PRIORITY - 2) | |
1036 | blk_congestion_wait(WRITE, HZ/10); | |
1037 | } | |
408d8544 NP |
1038 | /* top priority shrink_caches still had more to do? don't OOM, then */ |
1039 | if (!sc.all_unreclaimable) | |
1040 | ret = 1; | |
1da177e4 LT |
1041 | out: |
1042 | for (i = 0; zones[i] != 0; i++) { | |
1043 | struct zone *zone = zones[i]; | |
1044 | ||
9bf2229f | 1045 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
1046 | continue; |
1047 | ||
1048 | zone->prev_priority = zone->temp_priority; | |
1049 | } | |
1050 | return ret; | |
1051 | } | |
1052 | ||
1053 | /* | |
1054 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1055 | * they are all at pages_high. | |
1056 | * | |
1da177e4 LT |
1057 | * Returns the number of pages which were actually freed. |
1058 | * | |
1059 | * There is special handling here for zones which are full of pinned pages. | |
1060 | * This can happen if the pages are all mlocked, or if they are all used by | |
1061 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1062 | * What we do is to detect the case where all pages in the zone have been | |
1063 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1064 | * dead and from now on, only perform a short scan. Basically we're polling | |
1065 | * the zone for when the problem goes away. | |
1066 | * | |
1067 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1068 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1069 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1070 | * of the number of free pages in the lower zones. This interoperates with | |
1071 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1072 | * across the zones. | |
1073 | */ | |
d6277db4 | 1074 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1075 | { |
1da177e4 LT |
1076 | int all_zones_ok; |
1077 | int priority; | |
1078 | int i; | |
69e05944 | 1079 | unsigned long total_scanned; |
05ff5137 | 1080 | unsigned long nr_reclaimed; |
1da177e4 | 1081 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1082 | struct scan_control sc = { |
1083 | .gfp_mask = GFP_KERNEL, | |
1084 | .may_swap = 1, | |
d6277db4 RW |
1085 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1086 | .swappiness = vm_swappiness, | |
179e9639 | 1087 | }; |
1da177e4 LT |
1088 | |
1089 | loop_again: | |
1090 | total_scanned = 0; | |
05ff5137 | 1091 | nr_reclaimed = 0; |
c0bbbc73 | 1092 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1093 | count_vm_event(PAGEOUTRUN); |
1da177e4 LT |
1094 | |
1095 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1096 | struct zone *zone = pgdat->node_zones + i; | |
1097 | ||
1098 | zone->temp_priority = DEF_PRIORITY; | |
1099 | } | |
1100 | ||
1101 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1102 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1103 | unsigned long lru_pages = 0; | |
1104 | ||
f7b7fd8f RR |
1105 | /* The swap token gets in the way of swapout... */ |
1106 | if (!priority) | |
1107 | disable_swap_token(); | |
1108 | ||
1da177e4 LT |
1109 | all_zones_ok = 1; |
1110 | ||
d6277db4 RW |
1111 | /* |
1112 | * Scan in the highmem->dma direction for the highest | |
1113 | * zone which needs scanning | |
1114 | */ | |
1115 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1116 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1117 | |
d6277db4 RW |
1118 | if (!populated_zone(zone)) |
1119 | continue; | |
1da177e4 | 1120 | |
d6277db4 RW |
1121 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1122 | continue; | |
1da177e4 | 1123 | |
d6277db4 RW |
1124 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1125 | 0, 0)) { | |
1126 | end_zone = i; | |
1127 | goto scan; | |
1da177e4 | 1128 | } |
1da177e4 | 1129 | } |
d6277db4 | 1130 | goto out; |
1da177e4 LT |
1131 | scan: |
1132 | for (i = 0; i <= end_zone; i++) { | |
1133 | struct zone *zone = pgdat->node_zones + i; | |
1134 | ||
1135 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1136 | } | |
1137 | ||
1138 | /* | |
1139 | * Now scan the zone in the dma->highmem direction, stopping | |
1140 | * at the last zone which needs scanning. | |
1141 | * | |
1142 | * We do this because the page allocator works in the opposite | |
1143 | * direction. This prevents the page allocator from allocating | |
1144 | * pages behind kswapd's direction of progress, which would | |
1145 | * cause too much scanning of the lower zones. | |
1146 | */ | |
1147 | for (i = 0; i <= end_zone; i++) { | |
1148 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1149 | int nr_slab; |
1da177e4 | 1150 | |
f3fe6512 | 1151 | if (!populated_zone(zone)) |
1da177e4 LT |
1152 | continue; |
1153 | ||
1154 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
1155 | continue; | |
1156 | ||
d6277db4 RW |
1157 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1158 | end_zone, 0)) | |
1159 | all_zones_ok = 0; | |
1da177e4 LT |
1160 | zone->temp_priority = priority; |
1161 | if (zone->prev_priority > priority) | |
1162 | zone->prev_priority = priority; | |
1163 | sc.nr_scanned = 0; | |
05ff5137 | 1164 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
1da177e4 | 1165 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1166 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1167 | lru_pages); | |
05ff5137 | 1168 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1169 | total_scanned += sc.nr_scanned; |
1170 | if (zone->all_unreclaimable) | |
1171 | continue; | |
b15e0905 | 1172 | if (nr_slab == 0 && zone->pages_scanned >= |
4ff1ffb4 | 1173 | (zone->nr_active + zone->nr_inactive) * 6) |
1da177e4 LT |
1174 | zone->all_unreclaimable = 1; |
1175 | /* | |
1176 | * If we've done a decent amount of scanning and | |
1177 | * the reclaim ratio is low, start doing writepage | |
1178 | * even in laptop mode | |
1179 | */ | |
1180 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1181 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1182 | sc.may_writepage = 1; |
1183 | } | |
1da177e4 LT |
1184 | if (all_zones_ok) |
1185 | break; /* kswapd: all done */ | |
1186 | /* | |
1187 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1188 | * another pass across the zones. | |
1189 | */ | |
1190 | if (total_scanned && priority < DEF_PRIORITY - 2) | |
1191 | blk_congestion_wait(WRITE, HZ/10); | |
1192 | ||
1193 | /* | |
1194 | * We do this so kswapd doesn't build up large priorities for | |
1195 | * example when it is freeing in parallel with allocators. It | |
1196 | * matches the direct reclaim path behaviour in terms of impact | |
1197 | * on zone->*_priority. | |
1198 | */ | |
d6277db4 | 1199 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1200 | break; |
1201 | } | |
1202 | out: | |
1203 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1204 | struct zone *zone = pgdat->node_zones + i; | |
1205 | ||
1206 | zone->prev_priority = zone->temp_priority; | |
1207 | } | |
1208 | if (!all_zones_ok) { | |
1209 | cond_resched(); | |
1210 | goto loop_again; | |
1211 | } | |
1212 | ||
05ff5137 | 1213 | return nr_reclaimed; |
1da177e4 LT |
1214 | } |
1215 | ||
1216 | /* | |
1217 | * The background pageout daemon, started as a kernel thread | |
1218 | * from the init process. | |
1219 | * | |
1220 | * This basically trickles out pages so that we have _some_ | |
1221 | * free memory available even if there is no other activity | |
1222 | * that frees anything up. This is needed for things like routing | |
1223 | * etc, where we otherwise might have all activity going on in | |
1224 | * asynchronous contexts that cannot page things out. | |
1225 | * | |
1226 | * If there are applications that are active memory-allocators | |
1227 | * (most normal use), this basically shouldn't matter. | |
1228 | */ | |
1229 | static int kswapd(void *p) | |
1230 | { | |
1231 | unsigned long order; | |
1232 | pg_data_t *pgdat = (pg_data_t*)p; | |
1233 | struct task_struct *tsk = current; | |
1234 | DEFINE_WAIT(wait); | |
1235 | struct reclaim_state reclaim_state = { | |
1236 | .reclaimed_slab = 0, | |
1237 | }; | |
1238 | cpumask_t cpumask; | |
1239 | ||
1da177e4 LT |
1240 | cpumask = node_to_cpumask(pgdat->node_id); |
1241 | if (!cpus_empty(cpumask)) | |
1242 | set_cpus_allowed(tsk, cpumask); | |
1243 | current->reclaim_state = &reclaim_state; | |
1244 | ||
1245 | /* | |
1246 | * Tell the memory management that we're a "memory allocator", | |
1247 | * and that if we need more memory we should get access to it | |
1248 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1249 | * never get caught in the normal page freeing logic. | |
1250 | * | |
1251 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1252 | * you need a small amount of memory in order to be able to | |
1253 | * page out something else, and this flag essentially protects | |
1254 | * us from recursively trying to free more memory as we're | |
1255 | * trying to free the first piece of memory in the first place). | |
1256 | */ | |
930d9152 | 1257 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
1da177e4 LT |
1258 | |
1259 | order = 0; | |
1260 | for ( ; ; ) { | |
1261 | unsigned long new_order; | |
3e1d1d28 CL |
1262 | |
1263 | try_to_freeze(); | |
1da177e4 LT |
1264 | |
1265 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
1266 | new_order = pgdat->kswapd_max_order; | |
1267 | pgdat->kswapd_max_order = 0; | |
1268 | if (order < new_order) { | |
1269 | /* | |
1270 | * Don't sleep if someone wants a larger 'order' | |
1271 | * allocation | |
1272 | */ | |
1273 | order = new_order; | |
1274 | } else { | |
1275 | schedule(); | |
1276 | order = pgdat->kswapd_max_order; | |
1277 | } | |
1278 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1279 | ||
d6277db4 | 1280 | balance_pgdat(pgdat, order); |
1da177e4 LT |
1281 | } |
1282 | return 0; | |
1283 | } | |
1284 | ||
1285 | /* | |
1286 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1287 | */ | |
1288 | void wakeup_kswapd(struct zone *zone, int order) | |
1289 | { | |
1290 | pg_data_t *pgdat; | |
1291 | ||
f3fe6512 | 1292 | if (!populated_zone(zone)) |
1da177e4 LT |
1293 | return; |
1294 | ||
1295 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1296 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1297 | return; |
1298 | if (pgdat->kswapd_max_order < order) | |
1299 | pgdat->kswapd_max_order = order; | |
9bf2229f | 1300 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 | 1301 | return; |
8d0986e2 | 1302 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1303 | return; |
8d0986e2 | 1304 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1305 | } |
1306 | ||
1307 | #ifdef CONFIG_PM | |
1308 | /* | |
d6277db4 RW |
1309 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1310 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1311 | * number of reclaimed pages | |
1312 | * | |
1313 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1314 | */ | |
1315 | static unsigned long shrink_all_zones(unsigned long nr_pages, int pass, | |
1316 | int prio, struct scan_control *sc) | |
1317 | { | |
1318 | struct zone *zone; | |
1319 | unsigned long nr_to_scan, ret = 0; | |
1320 | ||
1321 | for_each_zone(zone) { | |
1322 | ||
1323 | if (!populated_zone(zone)) | |
1324 | continue; | |
1325 | ||
1326 | if (zone->all_unreclaimable && prio != DEF_PRIORITY) | |
1327 | continue; | |
1328 | ||
1329 | /* For pass = 0 we don't shrink the active list */ | |
1330 | if (pass > 0) { | |
1331 | zone->nr_scan_active += (zone->nr_active >> prio) + 1; | |
1332 | if (zone->nr_scan_active >= nr_pages || pass > 3) { | |
1333 | zone->nr_scan_active = 0; | |
1334 | nr_to_scan = min(nr_pages, zone->nr_active); | |
1335 | shrink_active_list(nr_to_scan, zone, sc); | |
1336 | } | |
1337 | } | |
1338 | ||
1339 | zone->nr_scan_inactive += (zone->nr_inactive >> prio) + 1; | |
1340 | if (zone->nr_scan_inactive >= nr_pages || pass > 3) { | |
1341 | zone->nr_scan_inactive = 0; | |
1342 | nr_to_scan = min(nr_pages, zone->nr_inactive); | |
1343 | ret += shrink_inactive_list(nr_to_scan, zone, sc); | |
1344 | if (ret >= nr_pages) | |
1345 | return ret; | |
1346 | } | |
1347 | } | |
1348 | ||
1349 | return ret; | |
1350 | } | |
1351 | ||
1352 | /* | |
1353 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
1354 | * freed pages. | |
1355 | * | |
1356 | * Rather than trying to age LRUs the aim is to preserve the overall | |
1357 | * LRU order by reclaiming preferentially | |
1358 | * inactive > active > active referenced > active mapped | |
1da177e4 | 1359 | */ |
69e05944 | 1360 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 1361 | { |
d6277db4 | 1362 | unsigned long lru_pages, nr_slab; |
69e05944 | 1363 | unsigned long ret = 0; |
d6277db4 RW |
1364 | int pass; |
1365 | struct reclaim_state reclaim_state; | |
1366 | struct zone *zone; | |
1367 | struct scan_control sc = { | |
1368 | .gfp_mask = GFP_KERNEL, | |
1369 | .may_swap = 0, | |
1370 | .swap_cluster_max = nr_pages, | |
1371 | .may_writepage = 1, | |
1372 | .swappiness = vm_swappiness, | |
1da177e4 LT |
1373 | }; |
1374 | ||
1375 | current->reclaim_state = &reclaim_state; | |
69e05944 | 1376 | |
d6277db4 RW |
1377 | lru_pages = 0; |
1378 | for_each_zone(zone) | |
1379 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1380 | ||
972d1a7b | 1381 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
1382 | /* If slab caches are huge, it's better to hit them first */ |
1383 | while (nr_slab >= lru_pages) { | |
1384 | reclaim_state.reclaimed_slab = 0; | |
1385 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1386 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 1387 | break; |
d6277db4 RW |
1388 | |
1389 | ret += reclaim_state.reclaimed_slab; | |
1390 | if (ret >= nr_pages) | |
1391 | goto out; | |
1392 | ||
1393 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 1394 | } |
d6277db4 RW |
1395 | |
1396 | /* | |
1397 | * We try to shrink LRUs in 5 passes: | |
1398 | * 0 = Reclaim from inactive_list only | |
1399 | * 1 = Reclaim from active list but don't reclaim mapped | |
1400 | * 2 = 2nd pass of type 1 | |
1401 | * 3 = Reclaim mapped (normal reclaim) | |
1402 | * 4 = 2nd pass of type 3 | |
1403 | */ | |
1404 | for (pass = 0; pass < 5; pass++) { | |
1405 | int prio; | |
1406 | ||
1407 | /* Needed for shrinking slab caches later on */ | |
1408 | if (!lru_pages) | |
1409 | for_each_zone(zone) { | |
1410 | lru_pages += zone->nr_active; | |
1411 | lru_pages += zone->nr_inactive; | |
1412 | } | |
1413 | ||
1414 | /* Force reclaiming mapped pages in the passes #3 and #4 */ | |
1415 | if (pass > 2) { | |
1416 | sc.may_swap = 1; | |
1417 | sc.swappiness = 100; | |
1418 | } | |
1419 | ||
1420 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
1421 | unsigned long nr_to_scan = nr_pages - ret; | |
1422 | ||
d6277db4 | 1423 | sc.nr_scanned = 0; |
d6277db4 RW |
1424 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
1425 | if (ret >= nr_pages) | |
1426 | goto out; | |
1427 | ||
1428 | reclaim_state.reclaimed_slab = 0; | |
1429 | shrink_slab(sc.nr_scanned, sc.gfp_mask, lru_pages); | |
1430 | ret += reclaim_state.reclaimed_slab; | |
1431 | if (ret >= nr_pages) | |
1432 | goto out; | |
1433 | ||
1434 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
1435 | blk_congestion_wait(WRITE, HZ / 10); | |
1436 | } | |
1437 | ||
1438 | lru_pages = 0; | |
248a0301 | 1439 | } |
d6277db4 RW |
1440 | |
1441 | /* | |
1442 | * If ret = 0, we could not shrink LRUs, but there may be something | |
1443 | * in slab caches | |
1444 | */ | |
1445 | if (!ret) | |
1446 | do { | |
1447 | reclaim_state.reclaimed_slab = 0; | |
1448 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1449 | ret += reclaim_state.reclaimed_slab; | |
1450 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
1451 | ||
1452 | out: | |
1da177e4 | 1453 | current->reclaim_state = NULL; |
d6277db4 | 1454 | |
1da177e4 LT |
1455 | return ret; |
1456 | } | |
1457 | #endif | |
1458 | ||
1459 | #ifdef CONFIG_HOTPLUG_CPU | |
1460 | /* It's optimal to keep kswapds on the same CPUs as their memory, but | |
1461 | not required for correctness. So if the last cpu in a node goes | |
1462 | away, we get changed to run anywhere: as the first one comes back, | |
1463 | restore their cpu bindings. */ | |
9c7b216d | 1464 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 1465 | unsigned long action, void *hcpu) |
1da177e4 LT |
1466 | { |
1467 | pg_data_t *pgdat; | |
1468 | cpumask_t mask; | |
1469 | ||
1470 | if (action == CPU_ONLINE) { | |
ec936fc5 | 1471 | for_each_online_pgdat(pgdat) { |
1da177e4 LT |
1472 | mask = node_to_cpumask(pgdat->node_id); |
1473 | if (any_online_cpu(mask) != NR_CPUS) | |
1474 | /* One of our CPUs online: restore mask */ | |
1475 | set_cpus_allowed(pgdat->kswapd, mask); | |
1476 | } | |
1477 | } | |
1478 | return NOTIFY_OK; | |
1479 | } | |
1480 | #endif /* CONFIG_HOTPLUG_CPU */ | |
1481 | ||
3218ae14 YG |
1482 | /* |
1483 | * This kswapd start function will be called by init and node-hot-add. | |
1484 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
1485 | */ | |
1486 | int kswapd_run(int nid) | |
1487 | { | |
1488 | pg_data_t *pgdat = NODE_DATA(nid); | |
1489 | int ret = 0; | |
1490 | ||
1491 | if (pgdat->kswapd) | |
1492 | return 0; | |
1493 | ||
1494 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
1495 | if (IS_ERR(pgdat->kswapd)) { | |
1496 | /* failure at boot is fatal */ | |
1497 | BUG_ON(system_state == SYSTEM_BOOTING); | |
1498 | printk("Failed to start kswapd on node %d\n",nid); | |
1499 | ret = -1; | |
1500 | } | |
1501 | return ret; | |
1502 | } | |
1503 | ||
1da177e4 LT |
1504 | static int __init kswapd_init(void) |
1505 | { | |
3218ae14 | 1506 | int nid; |
69e05944 | 1507 | |
1da177e4 | 1508 | swap_setup(); |
3218ae14 YG |
1509 | for_each_online_node(nid) |
1510 | kswapd_run(nid); | |
1da177e4 LT |
1511 | hotcpu_notifier(cpu_callback, 0); |
1512 | return 0; | |
1513 | } | |
1514 | ||
1515 | module_init(kswapd_init) | |
9eeff239 CL |
1516 | |
1517 | #ifdef CONFIG_NUMA | |
1518 | /* | |
1519 | * Zone reclaim mode | |
1520 | * | |
1521 | * If non-zero call zone_reclaim when the number of free pages falls below | |
1522 | * the watermarks. | |
9eeff239 CL |
1523 | */ |
1524 | int zone_reclaim_mode __read_mostly; | |
1525 | ||
1b2ffb78 CL |
1526 | #define RECLAIM_OFF 0 |
1527 | #define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */ | |
1528 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ | |
1529 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
1530 | ||
a92f7126 CL |
1531 | /* |
1532 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
1533 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
1534 | * a zone. | |
1535 | */ | |
1536 | #define ZONE_RECLAIM_PRIORITY 4 | |
1537 | ||
9614634f CL |
1538 | /* |
1539 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
1540 | * occur. | |
1541 | */ | |
1542 | int sysctl_min_unmapped_ratio = 1; | |
1543 | ||
0ff38490 CL |
1544 | /* |
1545 | * If the number of slab pages in a zone grows beyond this percentage then | |
1546 | * slab reclaim needs to occur. | |
1547 | */ | |
1548 | int sysctl_min_slab_ratio = 5; | |
1549 | ||
9eeff239 CL |
1550 | /* |
1551 | * Try to free up some pages from this zone through reclaim. | |
1552 | */ | |
179e9639 | 1553 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 1554 | { |
7fb2d46d | 1555 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 1556 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
1557 | struct task_struct *p = current; |
1558 | struct reclaim_state reclaim_state; | |
8695949a | 1559 | int priority; |
05ff5137 | 1560 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
1561 | struct scan_control sc = { |
1562 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
1563 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
1564 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
1565 | SWAP_CLUSTER_MAX), | |
179e9639 | 1566 | .gfp_mask = gfp_mask, |
d6277db4 | 1567 | .swappiness = vm_swappiness, |
179e9639 | 1568 | }; |
83e33a47 | 1569 | unsigned long slab_reclaimable; |
9eeff239 CL |
1570 | |
1571 | disable_swap_token(); | |
9eeff239 | 1572 | cond_resched(); |
d4f7796e CL |
1573 | /* |
1574 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
1575 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
1576 | * and RECLAIM_SWAP. | |
1577 | */ | |
1578 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
1579 | reclaim_state.reclaimed_slab = 0; |
1580 | p->reclaim_state = &reclaim_state; | |
c84db23c | 1581 | |
0ff38490 CL |
1582 | if (zone_page_state(zone, NR_FILE_PAGES) - |
1583 | zone_page_state(zone, NR_FILE_MAPPED) > | |
1584 | zone->min_unmapped_pages) { | |
1585 | /* | |
1586 | * Free memory by calling shrink zone with increasing | |
1587 | * priorities until we have enough memory freed. | |
1588 | */ | |
1589 | priority = ZONE_RECLAIM_PRIORITY; | |
1590 | do { | |
1591 | nr_reclaimed += shrink_zone(priority, zone, &sc); | |
1592 | priority--; | |
1593 | } while (priority >= 0 && nr_reclaimed < nr_pages); | |
1594 | } | |
c84db23c | 1595 | |
83e33a47 CL |
1596 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
1597 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 1598 | /* |
7fb2d46d | 1599 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
1600 | * many pages were freed in this zone. So we take the current |
1601 | * number of slab pages and shake the slab until it is reduced | |
1602 | * by the same nr_pages that we used for reclaiming unmapped | |
1603 | * pages. | |
2a16e3f4 | 1604 | * |
0ff38490 CL |
1605 | * Note that shrink_slab will free memory on all zones and may |
1606 | * take a long time. | |
2a16e3f4 | 1607 | */ |
0ff38490 | 1608 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
1609 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
1610 | slab_reclaimable - nr_pages) | |
0ff38490 | 1611 | ; |
83e33a47 CL |
1612 | |
1613 | /* | |
1614 | * Update nr_reclaimed by the number of slab pages we | |
1615 | * reclaimed from this zone. | |
1616 | */ | |
1617 | nr_reclaimed += slab_reclaimable - | |
1618 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); | |
2a16e3f4 CL |
1619 | } |
1620 | ||
9eeff239 | 1621 | p->reclaim_state = NULL; |
d4f7796e | 1622 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
05ff5137 | 1623 | return nr_reclaimed >= nr_pages; |
9eeff239 | 1624 | } |
179e9639 AM |
1625 | |
1626 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
1627 | { | |
1628 | cpumask_t mask; | |
1629 | int node_id; | |
1630 | ||
1631 | /* | |
0ff38490 CL |
1632 | * Zone reclaim reclaims unmapped file backed pages and |
1633 | * slab pages if we are over the defined limits. | |
34aa1330 | 1634 | * |
9614634f CL |
1635 | * A small portion of unmapped file backed pages is needed for |
1636 | * file I/O otherwise pages read by file I/O will be immediately | |
1637 | * thrown out if the zone is overallocated. So we do not reclaim | |
1638 | * if less than a specified percentage of the zone is used by | |
1639 | * unmapped file backed pages. | |
179e9639 | 1640 | */ |
34aa1330 | 1641 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
1642 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
1643 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
1644 | <= zone->min_slab_pages) | |
9614634f | 1645 | return 0; |
179e9639 AM |
1646 | |
1647 | /* | |
1648 | * Avoid concurrent zone reclaims, do not reclaim in a zone that does | |
1649 | * not have reclaimable pages and if we should not delay the allocation | |
1650 | * then do not scan. | |
1651 | */ | |
1652 | if (!(gfp_mask & __GFP_WAIT) || | |
1653 | zone->all_unreclaimable || | |
1654 | atomic_read(&zone->reclaim_in_progress) > 0 || | |
1655 | (current->flags & PF_MEMALLOC)) | |
1656 | return 0; | |
1657 | ||
1658 | /* | |
1659 | * Only run zone reclaim on the local zone or on zones that do not | |
1660 | * have associated processors. This will favor the local processor | |
1661 | * over remote processors and spread off node memory allocations | |
1662 | * as wide as possible. | |
1663 | */ | |
89fa3024 | 1664 | node_id = zone_to_nid(zone); |
179e9639 AM |
1665 | mask = node_to_cpumask(node_id); |
1666 | if (!cpus_empty(mask) && node_id != numa_node_id()) | |
1667 | return 0; | |
1668 | return __zone_reclaim(zone, gfp_mask, order); | |
1669 | } | |
9eeff239 | 1670 | #endif |