Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/kernel_stat.h> | |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
27 | buffer_heads_over_limit */ | |
28 | #include <linux/mm_inline.h> | |
29 | #include <linux/pagevec.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/rmap.h> | |
32 | #include <linux/topology.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cpuset.h> | |
35 | #include <linux/notifier.h> | |
36 | #include <linux/rwsem.h> | |
248a0301 | 37 | #include <linux/delay.h> |
3218ae14 | 38 | #include <linux/kthread.h> |
1da177e4 LT |
39 | |
40 | #include <asm/tlbflush.h> | |
41 | #include <asm/div64.h> | |
42 | ||
43 | #include <linux/swapops.h> | |
44 | ||
0f8053a5 NP |
45 | #include "internal.h" |
46 | ||
1da177e4 | 47 | struct scan_control { |
1da177e4 LT |
48 | /* Incremented by the number of inactive pages that were scanned */ |
49 | unsigned long nr_scanned; | |
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; | |
408d8544 NP |
66 | |
67 | int all_unreclaimable; | |
1da177e4 LT |
68 | }; |
69 | ||
70 | /* | |
71 | * The list of shrinker callbacks used by to apply pressure to | |
72 | * ageable caches. | |
73 | */ | |
74 | struct shrinker { | |
75 | shrinker_t shrinker; | |
76 | struct list_head list; | |
77 | int seeks; /* seeks to recreate an obj */ | |
78 | long nr; /* objs pending delete */ | |
79 | }; | |
80 | ||
81 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) | |
82 | ||
83 | #ifdef ARCH_HAS_PREFETCH | |
84 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
85 | do { \ | |
86 | if ((_page)->lru.prev != _base) { \ | |
87 | struct page *prev; \ | |
88 | \ | |
89 | prev = lru_to_page(&(_page->lru)); \ | |
90 | prefetch(&prev->_field); \ | |
91 | } \ | |
92 | } while (0) | |
93 | #else | |
94 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
95 | #endif | |
96 | ||
97 | #ifdef ARCH_HAS_PREFETCHW | |
98 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
99 | do { \ | |
100 | if ((_page)->lru.prev != _base) { \ | |
101 | struct page *prev; \ | |
102 | \ | |
103 | prev = lru_to_page(&(_page->lru)); \ | |
104 | prefetchw(&prev->_field); \ | |
105 | } \ | |
106 | } while (0) | |
107 | #else | |
108 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
109 | #endif | |
110 | ||
111 | /* | |
112 | * From 0 .. 100. Higher means more swappy. | |
113 | */ | |
114 | int vm_swappiness = 60; | |
bd1e22b8 | 115 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
116 | |
117 | static LIST_HEAD(shrinker_list); | |
118 | static DECLARE_RWSEM(shrinker_rwsem); | |
119 | ||
120 | /* | |
121 | * Add a shrinker callback to be called from the vm | |
122 | */ | |
123 | struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker) | |
124 | { | |
125 | struct shrinker *shrinker; | |
126 | ||
127 | shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL); | |
128 | if (shrinker) { | |
129 | shrinker->shrinker = theshrinker; | |
130 | shrinker->seeks = seeks; | |
131 | shrinker->nr = 0; | |
132 | down_write(&shrinker_rwsem); | |
133 | list_add_tail(&shrinker->list, &shrinker_list); | |
134 | up_write(&shrinker_rwsem); | |
135 | } | |
136 | return shrinker; | |
137 | } | |
138 | EXPORT_SYMBOL(set_shrinker); | |
139 | ||
140 | /* | |
141 | * Remove one | |
142 | */ | |
143 | void remove_shrinker(struct shrinker *shrinker) | |
144 | { | |
145 | down_write(&shrinker_rwsem); | |
146 | list_del(&shrinker->list); | |
147 | up_write(&shrinker_rwsem); | |
148 | kfree(shrinker); | |
149 | } | |
150 | EXPORT_SYMBOL(remove_shrinker); | |
151 | ||
152 | #define SHRINK_BATCH 128 | |
153 | /* | |
154 | * Call the shrink functions to age shrinkable caches | |
155 | * | |
156 | * Here we assume it costs one seek to replace a lru page and that it also | |
157 | * takes a seek to recreate a cache object. With this in mind we age equal | |
158 | * percentages of the lru and ageable caches. This should balance the seeks | |
159 | * generated by these structures. | |
160 | * | |
161 | * If the vm encounted mapped pages on the LRU it increase the pressure on | |
162 | * slab to avoid swapping. | |
163 | * | |
164 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
165 | * | |
166 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
167 | * are eligible for the caller's allocation attempt. It is used for balancing | |
168 | * slab reclaim versus page reclaim. | |
b15e0905 | 169 | * |
170 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 171 | */ |
69e05944 AM |
172 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
173 | unsigned long lru_pages) | |
1da177e4 LT |
174 | { |
175 | struct shrinker *shrinker; | |
69e05944 | 176 | unsigned long ret = 0; |
1da177e4 LT |
177 | |
178 | if (scanned == 0) | |
179 | scanned = SWAP_CLUSTER_MAX; | |
180 | ||
181 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 182 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
183 | |
184 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
185 | unsigned long long delta; | |
186 | unsigned long total_scan; | |
ea164d73 | 187 | unsigned long max_pass = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
188 | |
189 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 190 | delta *= max_pass; |
1da177e4 LT |
191 | do_div(delta, lru_pages + 1); |
192 | shrinker->nr += delta; | |
ea164d73 AA |
193 | if (shrinker->nr < 0) { |
194 | printk(KERN_ERR "%s: nr=%ld\n", | |
195 | __FUNCTION__, shrinker->nr); | |
196 | shrinker->nr = max_pass; | |
197 | } | |
198 | ||
199 | /* | |
200 | * Avoid risking looping forever due to too large nr value: | |
201 | * never try to free more than twice the estimate number of | |
202 | * freeable entries. | |
203 | */ | |
204 | if (shrinker->nr > max_pass * 2) | |
205 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
206 | |
207 | total_scan = shrinker->nr; | |
208 | shrinker->nr = 0; | |
209 | ||
210 | while (total_scan >= SHRINK_BATCH) { | |
211 | long this_scan = SHRINK_BATCH; | |
212 | int shrink_ret; | |
b15e0905 | 213 | int nr_before; |
1da177e4 | 214 | |
b15e0905 | 215 | nr_before = (*shrinker->shrinker)(0, gfp_mask); |
1da177e4 LT |
216 | shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask); |
217 | if (shrink_ret == -1) | |
218 | break; | |
b15e0905 | 219 | if (shrink_ret < nr_before) |
220 | ret += nr_before - shrink_ret; | |
f8891e5e | 221 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
222 | total_scan -= this_scan; |
223 | ||
224 | cond_resched(); | |
225 | } | |
226 | ||
227 | shrinker->nr += total_scan; | |
228 | } | |
229 | up_read(&shrinker_rwsem); | |
b15e0905 | 230 | return ret; |
1da177e4 LT |
231 | } |
232 | ||
233 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
234 | static inline int page_mapping_inuse(struct page *page) | |
235 | { | |
236 | struct address_space *mapping; | |
237 | ||
238 | /* Page is in somebody's page tables. */ | |
239 | if (page_mapped(page)) | |
240 | return 1; | |
241 | ||
242 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
243 | if (PageSwapCache(page)) | |
244 | return 1; | |
245 | ||
246 | mapping = page_mapping(page); | |
247 | if (!mapping) | |
248 | return 0; | |
249 | ||
250 | /* File is mmap'd by somebody? */ | |
251 | return mapping_mapped(mapping); | |
252 | } | |
253 | ||
254 | static inline int is_page_cache_freeable(struct page *page) | |
255 | { | |
256 | return page_count(page) - !!PagePrivate(page) == 2; | |
257 | } | |
258 | ||
259 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
260 | { | |
930d9152 | 261 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
262 | return 1; |
263 | if (!bdi_write_congested(bdi)) | |
264 | return 1; | |
265 | if (bdi == current->backing_dev_info) | |
266 | return 1; | |
267 | return 0; | |
268 | } | |
269 | ||
270 | /* | |
271 | * We detected a synchronous write error writing a page out. Probably | |
272 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
273 | * fsync(), msync() or close(). | |
274 | * | |
275 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
276 | * prevents it from being freed up. But we have a ref on the page and once | |
277 | * that page is locked, the mapping is pinned. | |
278 | * | |
279 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
280 | * __GFP_FS. | |
281 | */ | |
282 | static void handle_write_error(struct address_space *mapping, | |
283 | struct page *page, int error) | |
284 | { | |
285 | lock_page(page); | |
286 | if (page_mapping(page) == mapping) { | |
287 | if (error == -ENOSPC) | |
288 | set_bit(AS_ENOSPC, &mapping->flags); | |
289 | else | |
290 | set_bit(AS_EIO, &mapping->flags); | |
291 | } | |
292 | unlock_page(page); | |
293 | } | |
294 | ||
04e62a29 CL |
295 | /* possible outcome of pageout() */ |
296 | typedef enum { | |
297 | /* failed to write page out, page is locked */ | |
298 | PAGE_KEEP, | |
299 | /* move page to the active list, page is locked */ | |
300 | PAGE_ACTIVATE, | |
301 | /* page has been sent to the disk successfully, page is unlocked */ | |
302 | PAGE_SUCCESS, | |
303 | /* page is clean and locked */ | |
304 | PAGE_CLEAN, | |
305 | } pageout_t; | |
306 | ||
1da177e4 | 307 | /* |
1742f19f AM |
308 | * pageout is called by shrink_page_list() for each dirty page. |
309 | * Calls ->writepage(). | |
1da177e4 | 310 | */ |
04e62a29 | 311 | static pageout_t pageout(struct page *page, struct address_space *mapping) |
1da177e4 LT |
312 | { |
313 | /* | |
314 | * If the page is dirty, only perform writeback if that write | |
315 | * will be non-blocking. To prevent this allocation from being | |
316 | * stalled by pagecache activity. But note that there may be | |
317 | * stalls if we need to run get_block(). We could test | |
318 | * PagePrivate for that. | |
319 | * | |
320 | * If this process is currently in generic_file_write() against | |
321 | * this page's queue, we can perform writeback even if that | |
322 | * will block. | |
323 | * | |
324 | * If the page is swapcache, write it back even if that would | |
325 | * block, for some throttling. This happens by accident, because | |
326 | * swap_backing_dev_info is bust: it doesn't reflect the | |
327 | * congestion state of the swapdevs. Easy to fix, if needed. | |
328 | * See swapfile.c:page_queue_congested(). | |
329 | */ | |
330 | if (!is_page_cache_freeable(page)) | |
331 | return PAGE_KEEP; | |
332 | if (!mapping) { | |
333 | /* | |
334 | * Some data journaling orphaned pages can have | |
335 | * page->mapping == NULL while being dirty with clean buffers. | |
336 | */ | |
323aca6c | 337 | if (PagePrivate(page)) { |
1da177e4 LT |
338 | if (try_to_free_buffers(page)) { |
339 | ClearPageDirty(page); | |
340 | printk("%s: orphaned page\n", __FUNCTION__); | |
341 | return PAGE_CLEAN; | |
342 | } | |
343 | } | |
344 | return PAGE_KEEP; | |
345 | } | |
346 | if (mapping->a_ops->writepage == NULL) | |
347 | return PAGE_ACTIVATE; | |
348 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
349 | return PAGE_KEEP; | |
350 | ||
351 | if (clear_page_dirty_for_io(page)) { | |
352 | int res; | |
353 | struct writeback_control wbc = { | |
354 | .sync_mode = WB_SYNC_NONE, | |
355 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
356 | .range_start = 0, |
357 | .range_end = LLONG_MAX, | |
1da177e4 LT |
358 | .nonblocking = 1, |
359 | .for_reclaim = 1, | |
360 | }; | |
361 | ||
362 | SetPageReclaim(page); | |
363 | res = mapping->a_ops->writepage(page, &wbc); | |
364 | if (res < 0) | |
365 | handle_write_error(mapping, page, res); | |
994fc28c | 366 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
367 | ClearPageReclaim(page); |
368 | return PAGE_ACTIVATE; | |
369 | } | |
370 | if (!PageWriteback(page)) { | |
371 | /* synchronous write or broken a_ops? */ | |
372 | ClearPageReclaim(page); | |
373 | } | |
e129b5c2 | 374 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
375 | return PAGE_SUCCESS; |
376 | } | |
377 | ||
378 | return PAGE_CLEAN; | |
379 | } | |
380 | ||
b20a3503 | 381 | int remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 382 | { |
28e4d965 NP |
383 | BUG_ON(!PageLocked(page)); |
384 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc CL |
385 | |
386 | write_lock_irq(&mapping->tree_lock); | |
49d2e9cc | 387 | /* |
0fd0e6b0 NP |
388 | * The non racy check for a busy page. |
389 | * | |
390 | * Must be careful with the order of the tests. When someone has | |
391 | * a ref to the page, it may be possible that they dirty it then | |
392 | * drop the reference. So if PageDirty is tested before page_count | |
393 | * here, then the following race may occur: | |
394 | * | |
395 | * get_user_pages(&page); | |
396 | * [user mapping goes away] | |
397 | * write_to(page); | |
398 | * !PageDirty(page) [good] | |
399 | * SetPageDirty(page); | |
400 | * put_page(page); | |
401 | * !page_count(page) [good, discard it] | |
402 | * | |
403 | * [oops, our write_to data is lost] | |
404 | * | |
405 | * Reversing the order of the tests ensures such a situation cannot | |
406 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
407 | * load is not satisfied before that of page->_count. | |
408 | * | |
409 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
410 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc CL |
411 | */ |
412 | if (unlikely(page_count(page) != 2)) | |
413 | goto cannot_free; | |
414 | smp_rmb(); | |
415 | if (unlikely(PageDirty(page))) | |
416 | goto cannot_free; | |
417 | ||
418 | if (PageSwapCache(page)) { | |
419 | swp_entry_t swap = { .val = page_private(page) }; | |
420 | __delete_from_swap_cache(page); | |
421 | write_unlock_irq(&mapping->tree_lock); | |
422 | swap_free(swap); | |
423 | __put_page(page); /* The pagecache ref */ | |
424 | return 1; | |
425 | } | |
426 | ||
427 | __remove_from_page_cache(page); | |
428 | write_unlock_irq(&mapping->tree_lock); | |
429 | __put_page(page); | |
430 | return 1; | |
431 | ||
432 | cannot_free: | |
433 | write_unlock_irq(&mapping->tree_lock); | |
434 | return 0; | |
435 | } | |
436 | ||
1da177e4 | 437 | /* |
1742f19f | 438 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 439 | */ |
1742f19f AM |
440 | static unsigned long shrink_page_list(struct list_head *page_list, |
441 | struct scan_control *sc) | |
1da177e4 LT |
442 | { |
443 | LIST_HEAD(ret_pages); | |
444 | struct pagevec freed_pvec; | |
445 | int pgactivate = 0; | |
05ff5137 | 446 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
447 | |
448 | cond_resched(); | |
449 | ||
450 | pagevec_init(&freed_pvec, 1); | |
451 | while (!list_empty(page_list)) { | |
452 | struct address_space *mapping; | |
453 | struct page *page; | |
454 | int may_enter_fs; | |
455 | int referenced; | |
456 | ||
457 | cond_resched(); | |
458 | ||
459 | page = lru_to_page(page_list); | |
460 | list_del(&page->lru); | |
461 | ||
462 | if (TestSetPageLocked(page)) | |
463 | goto keep; | |
464 | ||
725d704e | 465 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
466 | |
467 | sc->nr_scanned++; | |
80e43426 CL |
468 | |
469 | if (!sc->may_swap && page_mapped(page)) | |
470 | goto keep_locked; | |
471 | ||
1da177e4 LT |
472 | /* Double the slab pressure for mapped and swapcache pages */ |
473 | if (page_mapped(page) || PageSwapCache(page)) | |
474 | sc->nr_scanned++; | |
475 | ||
476 | if (PageWriteback(page)) | |
477 | goto keep_locked; | |
478 | ||
f7b7fd8f | 479 | referenced = page_referenced(page, 1); |
1da177e4 LT |
480 | /* In active use or really unfreeable? Activate it. */ |
481 | if (referenced && page_mapping_inuse(page)) | |
482 | goto activate_locked; | |
483 | ||
484 | #ifdef CONFIG_SWAP | |
485 | /* | |
486 | * Anonymous process memory has backing store? | |
487 | * Try to allocate it some swap space here. | |
488 | */ | |
6e5ef1a9 | 489 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 490 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 491 | goto activate_locked; |
1da177e4 LT |
492 | #endif /* CONFIG_SWAP */ |
493 | ||
494 | mapping = page_mapping(page); | |
495 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || | |
496 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
497 | ||
498 | /* | |
499 | * The page is mapped into the page tables of one or more | |
500 | * processes. Try to unmap it here. | |
501 | */ | |
502 | if (page_mapped(page) && mapping) { | |
a48d07af | 503 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
504 | case SWAP_FAIL: |
505 | goto activate_locked; | |
506 | case SWAP_AGAIN: | |
507 | goto keep_locked; | |
508 | case SWAP_SUCCESS: | |
509 | ; /* try to free the page below */ | |
510 | } | |
511 | } | |
512 | ||
513 | if (PageDirty(page)) { | |
514 | if (referenced) | |
515 | goto keep_locked; | |
516 | if (!may_enter_fs) | |
517 | goto keep_locked; | |
52a8363e | 518 | if (!sc->may_writepage) |
1da177e4 LT |
519 | goto keep_locked; |
520 | ||
521 | /* Page is dirty, try to write it out here */ | |
522 | switch(pageout(page, mapping)) { | |
523 | case PAGE_KEEP: | |
524 | goto keep_locked; | |
525 | case PAGE_ACTIVATE: | |
526 | goto activate_locked; | |
527 | case PAGE_SUCCESS: | |
528 | if (PageWriteback(page) || PageDirty(page)) | |
529 | goto keep; | |
530 | /* | |
531 | * A synchronous write - probably a ramdisk. Go | |
532 | * ahead and try to reclaim the page. | |
533 | */ | |
534 | if (TestSetPageLocked(page)) | |
535 | goto keep; | |
536 | if (PageDirty(page) || PageWriteback(page)) | |
537 | goto keep_locked; | |
538 | mapping = page_mapping(page); | |
539 | case PAGE_CLEAN: | |
540 | ; /* try to free the page below */ | |
541 | } | |
542 | } | |
543 | ||
544 | /* | |
545 | * If the page has buffers, try to free the buffer mappings | |
546 | * associated with this page. If we succeed we try to free | |
547 | * the page as well. | |
548 | * | |
549 | * We do this even if the page is PageDirty(). | |
550 | * try_to_release_page() does not perform I/O, but it is | |
551 | * possible for a page to have PageDirty set, but it is actually | |
552 | * clean (all its buffers are clean). This happens if the | |
553 | * buffers were written out directly, with submit_bh(). ext3 | |
554 | * will do this, as well as the blockdev mapping. | |
555 | * try_to_release_page() will discover that cleanness and will | |
556 | * drop the buffers and mark the page clean - it can be freed. | |
557 | * | |
558 | * Rarely, pages can have buffers and no ->mapping. These are | |
559 | * the pages which were not successfully invalidated in | |
560 | * truncate_complete_page(). We try to drop those buffers here | |
561 | * and if that worked, and the page is no longer mapped into | |
562 | * process address space (page_count == 1) it can be freed. | |
563 | * Otherwise, leave the page on the LRU so it is swappable. | |
564 | */ | |
565 | if (PagePrivate(page)) { | |
566 | if (!try_to_release_page(page, sc->gfp_mask)) | |
567 | goto activate_locked; | |
568 | if (!mapping && page_count(page) == 1) | |
569 | goto free_it; | |
570 | } | |
571 | ||
28e4d965 | 572 | if (!mapping || !remove_mapping(mapping, page)) |
49d2e9cc | 573 | goto keep_locked; |
1da177e4 LT |
574 | |
575 | free_it: | |
576 | unlock_page(page); | |
05ff5137 | 577 | nr_reclaimed++; |
1da177e4 LT |
578 | if (!pagevec_add(&freed_pvec, page)) |
579 | __pagevec_release_nonlru(&freed_pvec); | |
580 | continue; | |
581 | ||
582 | activate_locked: | |
583 | SetPageActive(page); | |
584 | pgactivate++; | |
585 | keep_locked: | |
586 | unlock_page(page); | |
587 | keep: | |
588 | list_add(&page->lru, &ret_pages); | |
725d704e | 589 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
590 | } |
591 | list_splice(&ret_pages, page_list); | |
592 | if (pagevec_count(&freed_pvec)) | |
593 | __pagevec_release_nonlru(&freed_pvec); | |
f8891e5e | 594 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 595 | return nr_reclaimed; |
1da177e4 LT |
596 | } |
597 | ||
598 | /* | |
599 | * zone->lru_lock is heavily contended. Some of the functions that | |
600 | * shrink the lists perform better by taking out a batch of pages | |
601 | * and working on them outside the LRU lock. | |
602 | * | |
603 | * For pagecache intensive workloads, this function is the hottest | |
604 | * spot in the kernel (apart from copy_*_user functions). | |
605 | * | |
606 | * Appropriate locks must be held before calling this function. | |
607 | * | |
608 | * @nr_to_scan: The number of pages to look through on the list. | |
609 | * @src: The LRU list to pull pages off. | |
610 | * @dst: The temp list to put pages on to. | |
611 | * @scanned: The number of pages that were scanned. | |
612 | * | |
613 | * returns how many pages were moved onto *@dst. | |
614 | */ | |
69e05944 AM |
615 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
616 | struct list_head *src, struct list_head *dst, | |
617 | unsigned long *scanned) | |
1da177e4 | 618 | { |
69e05944 | 619 | unsigned long nr_taken = 0; |
1da177e4 | 620 | struct page *page; |
c9b02d97 | 621 | unsigned long scan; |
1da177e4 | 622 | |
c9b02d97 | 623 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
7c8ee9a8 | 624 | struct list_head *target; |
1da177e4 LT |
625 | page = lru_to_page(src); |
626 | prefetchw_prev_lru_page(page, src, flags); | |
627 | ||
725d704e | 628 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 629 | |
053837fc | 630 | list_del(&page->lru); |
7c8ee9a8 NP |
631 | target = src; |
632 | if (likely(get_page_unless_zero(page))) { | |
053837fc | 633 | /* |
7c8ee9a8 NP |
634 | * Be careful not to clear PageLRU until after we're |
635 | * sure the page is not being freed elsewhere -- the | |
636 | * page release code relies on it. | |
053837fc | 637 | */ |
7c8ee9a8 NP |
638 | ClearPageLRU(page); |
639 | target = dst; | |
640 | nr_taken++; | |
641 | } /* else it is being freed elsewhere */ | |
46453a6e | 642 | |
7c8ee9a8 | 643 | list_add(&page->lru, target); |
1da177e4 LT |
644 | } |
645 | ||
646 | *scanned = scan; | |
647 | return nr_taken; | |
648 | } | |
649 | ||
650 | /* | |
1742f19f AM |
651 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
652 | * of reclaimed pages | |
1da177e4 | 653 | */ |
1742f19f AM |
654 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
655 | struct zone *zone, struct scan_control *sc) | |
1da177e4 LT |
656 | { |
657 | LIST_HEAD(page_list); | |
658 | struct pagevec pvec; | |
69e05944 | 659 | unsigned long nr_scanned = 0; |
05ff5137 | 660 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
661 | |
662 | pagevec_init(&pvec, 1); | |
663 | ||
664 | lru_add_drain(); | |
665 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 666 | do { |
1da177e4 | 667 | struct page *page; |
69e05944 AM |
668 | unsigned long nr_taken; |
669 | unsigned long nr_scan; | |
670 | unsigned long nr_freed; | |
1da177e4 LT |
671 | |
672 | nr_taken = isolate_lru_pages(sc->swap_cluster_max, | |
673 | &zone->inactive_list, | |
674 | &page_list, &nr_scan); | |
675 | zone->nr_inactive -= nr_taken; | |
676 | zone->pages_scanned += nr_scan; | |
677 | spin_unlock_irq(&zone->lru_lock); | |
678 | ||
69e05944 | 679 | nr_scanned += nr_scan; |
1742f19f | 680 | nr_freed = shrink_page_list(&page_list, sc); |
05ff5137 | 681 | nr_reclaimed += nr_freed; |
a74609fa NP |
682 | local_irq_disable(); |
683 | if (current_is_kswapd()) { | |
f8891e5e CL |
684 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
685 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
a74609fa | 686 | } else |
f8891e5e CL |
687 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
688 | __count_vm_events(PGACTIVATE, nr_freed); | |
a74609fa | 689 | |
fb8d14e1 WF |
690 | if (nr_taken == 0) |
691 | goto done; | |
692 | ||
a74609fa | 693 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
694 | /* |
695 | * Put back any unfreeable pages. | |
696 | */ | |
697 | while (!list_empty(&page_list)) { | |
698 | page = lru_to_page(&page_list); | |
725d704e | 699 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 700 | SetPageLRU(page); |
1da177e4 LT |
701 | list_del(&page->lru); |
702 | if (PageActive(page)) | |
703 | add_page_to_active_list(zone, page); | |
704 | else | |
705 | add_page_to_inactive_list(zone, page); | |
706 | if (!pagevec_add(&pvec, page)) { | |
707 | spin_unlock_irq(&zone->lru_lock); | |
708 | __pagevec_release(&pvec); | |
709 | spin_lock_irq(&zone->lru_lock); | |
710 | } | |
711 | } | |
69e05944 | 712 | } while (nr_scanned < max_scan); |
fb8d14e1 | 713 | spin_unlock(&zone->lru_lock); |
1da177e4 | 714 | done: |
fb8d14e1 | 715 | local_irq_enable(); |
1da177e4 | 716 | pagevec_release(&pvec); |
05ff5137 | 717 | return nr_reclaimed; |
1da177e4 LT |
718 | } |
719 | ||
4ff1ffb4 NP |
720 | static inline int zone_is_near_oom(struct zone *zone) |
721 | { | |
722 | return zone->pages_scanned >= (zone->nr_active + zone->nr_inactive)*3; | |
723 | } | |
724 | ||
1da177e4 LT |
725 | /* |
726 | * This moves pages from the active list to the inactive list. | |
727 | * | |
728 | * We move them the other way if the page is referenced by one or more | |
729 | * processes, from rmap. | |
730 | * | |
731 | * If the pages are mostly unmapped, the processing is fast and it is | |
732 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
733 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
734 | * should drop zone->lru_lock around each page. It's impossible to balance | |
735 | * this, so instead we remove the pages from the LRU while processing them. | |
736 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
737 | * nobody will play with that bit on a non-LRU page. | |
738 | * | |
739 | * The downside is that we have to touch page->_count against each page. | |
740 | * But we had to alter page->flags anyway. | |
741 | */ | |
1742f19f AM |
742 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
743 | struct scan_control *sc) | |
1da177e4 | 744 | { |
69e05944 | 745 | unsigned long pgmoved; |
1da177e4 | 746 | int pgdeactivate = 0; |
69e05944 | 747 | unsigned long pgscanned; |
1da177e4 LT |
748 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
749 | LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ | |
750 | LIST_HEAD(l_active); /* Pages to go onto the active_list */ | |
751 | struct page *page; | |
752 | struct pagevec pvec; | |
753 | int reclaim_mapped = 0; | |
2903fb16 | 754 | |
6e5ef1a9 | 755 | if (sc->may_swap) { |
2903fb16 CL |
756 | long mapped_ratio; |
757 | long distress; | |
758 | long swap_tendency; | |
759 | ||
4ff1ffb4 NP |
760 | if (zone_is_near_oom(zone)) |
761 | goto force_reclaim_mapped; | |
762 | ||
2903fb16 CL |
763 | /* |
764 | * `distress' is a measure of how much trouble we're having | |
765 | * reclaiming pages. 0 -> no problems. 100 -> great trouble. | |
766 | */ | |
767 | distress = 100 >> zone->prev_priority; | |
768 | ||
769 | /* | |
770 | * The point of this algorithm is to decide when to start | |
771 | * reclaiming mapped memory instead of just pagecache. Work out | |
772 | * how much memory | |
773 | * is mapped. | |
774 | */ | |
f3dbd344 CL |
775 | mapped_ratio = ((global_page_state(NR_FILE_MAPPED) + |
776 | global_page_state(NR_ANON_PAGES)) * 100) / | |
bf02cf4b | 777 | vm_total_pages; |
2903fb16 CL |
778 | |
779 | /* | |
780 | * Now decide how much we really want to unmap some pages. The | |
781 | * mapped ratio is downgraded - just because there's a lot of | |
782 | * mapped memory doesn't necessarily mean that page reclaim | |
783 | * isn't succeeding. | |
784 | * | |
785 | * The distress ratio is important - we don't want to start | |
786 | * going oom. | |
787 | * | |
788 | * A 100% value of vm_swappiness overrides this algorithm | |
789 | * altogether. | |
790 | */ | |
d6277db4 | 791 | swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; |
2903fb16 CL |
792 | |
793 | /* | |
794 | * Now use this metric to decide whether to start moving mapped | |
795 | * memory onto the inactive list. | |
796 | */ | |
797 | if (swap_tendency >= 100) | |
4ff1ffb4 | 798 | force_reclaim_mapped: |
2903fb16 CL |
799 | reclaim_mapped = 1; |
800 | } | |
1da177e4 LT |
801 | |
802 | lru_add_drain(); | |
803 | spin_lock_irq(&zone->lru_lock); | |
804 | pgmoved = isolate_lru_pages(nr_pages, &zone->active_list, | |
805 | &l_hold, &pgscanned); | |
806 | zone->pages_scanned += pgscanned; | |
807 | zone->nr_active -= pgmoved; | |
808 | spin_unlock_irq(&zone->lru_lock); | |
809 | ||
1da177e4 LT |
810 | while (!list_empty(&l_hold)) { |
811 | cond_resched(); | |
812 | page = lru_to_page(&l_hold); | |
813 | list_del(&page->lru); | |
814 | if (page_mapped(page)) { | |
815 | if (!reclaim_mapped || | |
816 | (total_swap_pages == 0 && PageAnon(page)) || | |
f7b7fd8f | 817 | page_referenced(page, 0)) { |
1da177e4 LT |
818 | list_add(&page->lru, &l_active); |
819 | continue; | |
820 | } | |
821 | } | |
822 | list_add(&page->lru, &l_inactive); | |
823 | } | |
824 | ||
825 | pagevec_init(&pvec, 1); | |
826 | pgmoved = 0; | |
827 | spin_lock_irq(&zone->lru_lock); | |
828 | while (!list_empty(&l_inactive)) { | |
829 | page = lru_to_page(&l_inactive); | |
830 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 831 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 832 | SetPageLRU(page); |
725d704e | 833 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
834 | ClearPageActive(page); |
835 | ||
1da177e4 LT |
836 | list_move(&page->lru, &zone->inactive_list); |
837 | pgmoved++; | |
838 | if (!pagevec_add(&pvec, page)) { | |
839 | zone->nr_inactive += pgmoved; | |
840 | spin_unlock_irq(&zone->lru_lock); | |
841 | pgdeactivate += pgmoved; | |
842 | pgmoved = 0; | |
843 | if (buffer_heads_over_limit) | |
844 | pagevec_strip(&pvec); | |
845 | __pagevec_release(&pvec); | |
846 | spin_lock_irq(&zone->lru_lock); | |
847 | } | |
848 | } | |
849 | zone->nr_inactive += pgmoved; | |
850 | pgdeactivate += pgmoved; | |
851 | if (buffer_heads_over_limit) { | |
852 | spin_unlock_irq(&zone->lru_lock); | |
853 | pagevec_strip(&pvec); | |
854 | spin_lock_irq(&zone->lru_lock); | |
855 | } | |
856 | ||
857 | pgmoved = 0; | |
858 | while (!list_empty(&l_active)) { | |
859 | page = lru_to_page(&l_active); | |
860 | prefetchw_prev_lru_page(page, &l_active, flags); | |
725d704e | 861 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 862 | SetPageLRU(page); |
725d704e | 863 | VM_BUG_ON(!PageActive(page)); |
1da177e4 LT |
864 | list_move(&page->lru, &zone->active_list); |
865 | pgmoved++; | |
866 | if (!pagevec_add(&pvec, page)) { | |
867 | zone->nr_active += pgmoved; | |
868 | pgmoved = 0; | |
869 | spin_unlock_irq(&zone->lru_lock); | |
870 | __pagevec_release(&pvec); | |
871 | spin_lock_irq(&zone->lru_lock); | |
872 | } | |
873 | } | |
874 | zone->nr_active += pgmoved; | |
a74609fa | 875 | |
f8891e5e CL |
876 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
877 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
878 | spin_unlock_irq(&zone->lru_lock); | |
1da177e4 | 879 | |
a74609fa | 880 | pagevec_release(&pvec); |
1da177e4 LT |
881 | } |
882 | ||
883 | /* | |
884 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
885 | */ | |
05ff5137 AM |
886 | static unsigned long shrink_zone(int priority, struct zone *zone, |
887 | struct scan_control *sc) | |
1da177e4 LT |
888 | { |
889 | unsigned long nr_active; | |
890 | unsigned long nr_inactive; | |
8695949a | 891 | unsigned long nr_to_scan; |
05ff5137 | 892 | unsigned long nr_reclaimed = 0; |
1da177e4 | 893 | |
53e9a615 MH |
894 | atomic_inc(&zone->reclaim_in_progress); |
895 | ||
1da177e4 LT |
896 | /* |
897 | * Add one to `nr_to_scan' just to make sure that the kernel will | |
898 | * slowly sift through the active list. | |
899 | */ | |
8695949a | 900 | zone->nr_scan_active += (zone->nr_active >> priority) + 1; |
1da177e4 LT |
901 | nr_active = zone->nr_scan_active; |
902 | if (nr_active >= sc->swap_cluster_max) | |
903 | zone->nr_scan_active = 0; | |
904 | else | |
905 | nr_active = 0; | |
906 | ||
8695949a | 907 | zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1; |
1da177e4 LT |
908 | nr_inactive = zone->nr_scan_inactive; |
909 | if (nr_inactive >= sc->swap_cluster_max) | |
910 | zone->nr_scan_inactive = 0; | |
911 | else | |
912 | nr_inactive = 0; | |
913 | ||
1da177e4 LT |
914 | while (nr_active || nr_inactive) { |
915 | if (nr_active) { | |
8695949a | 916 | nr_to_scan = min(nr_active, |
1da177e4 | 917 | (unsigned long)sc->swap_cluster_max); |
8695949a | 918 | nr_active -= nr_to_scan; |
1742f19f | 919 | shrink_active_list(nr_to_scan, zone, sc); |
1da177e4 LT |
920 | } |
921 | ||
922 | if (nr_inactive) { | |
8695949a | 923 | nr_to_scan = min(nr_inactive, |
1da177e4 | 924 | (unsigned long)sc->swap_cluster_max); |
8695949a | 925 | nr_inactive -= nr_to_scan; |
1742f19f AM |
926 | nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, |
927 | sc); | |
1da177e4 LT |
928 | } |
929 | } | |
930 | ||
931 | throttle_vm_writeout(); | |
53e9a615 MH |
932 | |
933 | atomic_dec(&zone->reclaim_in_progress); | |
05ff5137 | 934 | return nr_reclaimed; |
1da177e4 LT |
935 | } |
936 | ||
937 | /* | |
938 | * This is the direct reclaim path, for page-allocating processes. We only | |
939 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
940 | * request. | |
941 | * | |
942 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
943 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
944 | * allocation or | |
945 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
946 | * satisfy the `incremental min' zone defense algorithm. | |
947 | * | |
948 | * Returns the number of reclaimed pages. | |
949 | * | |
950 | * If a zone is deemed to be full of pinned pages then just give it a light | |
951 | * scan then give up on it. | |
952 | */ | |
1742f19f | 953 | static unsigned long shrink_zones(int priority, struct zone **zones, |
05ff5137 | 954 | struct scan_control *sc) |
1da177e4 | 955 | { |
05ff5137 | 956 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
957 | int i; |
958 | ||
408d8544 | 959 | sc->all_unreclaimable = 1; |
1da177e4 LT |
960 | for (i = 0; zones[i] != NULL; i++) { |
961 | struct zone *zone = zones[i]; | |
962 | ||
f3fe6512 | 963 | if (!populated_zone(zone)) |
1da177e4 LT |
964 | continue; |
965 | ||
9bf2229f | 966 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
967 | continue; |
968 | ||
8695949a CL |
969 | zone->temp_priority = priority; |
970 | if (zone->prev_priority > priority) | |
971 | zone->prev_priority = priority; | |
1da177e4 | 972 | |
8695949a | 973 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
974 | continue; /* Let kswapd poll it */ |
975 | ||
408d8544 NP |
976 | sc->all_unreclaimable = 0; |
977 | ||
05ff5137 | 978 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 979 | } |
05ff5137 | 980 | return nr_reclaimed; |
1da177e4 LT |
981 | } |
982 | ||
983 | /* | |
984 | * This is the main entry point to direct page reclaim. | |
985 | * | |
986 | * If a full scan of the inactive list fails to free enough memory then we | |
987 | * are "out of memory" and something needs to be killed. | |
988 | * | |
989 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
990 | * high - the zone may be full of dirty or under-writeback pages, which this | |
991 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
992 | * hope that some of these pages can be written. But if the allocating task | |
993 | * holds filesystem locks which prevent writeout this might not work, and the | |
994 | * allocation attempt will fail. | |
995 | */ | |
69e05944 | 996 | unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask) |
1da177e4 LT |
997 | { |
998 | int priority; | |
999 | int ret = 0; | |
69e05944 | 1000 | unsigned long total_scanned = 0; |
05ff5137 | 1001 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1002 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 LT |
1003 | unsigned long lru_pages = 0; |
1004 | int i; | |
179e9639 AM |
1005 | struct scan_control sc = { |
1006 | .gfp_mask = gfp_mask, | |
1007 | .may_writepage = !laptop_mode, | |
1008 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1009 | .may_swap = 1, | |
d6277db4 | 1010 | .swappiness = vm_swappiness, |
179e9639 | 1011 | }; |
1da177e4 | 1012 | |
f8891e5e | 1013 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
1014 | |
1015 | for (i = 0; zones[i] != NULL; i++) { | |
1016 | struct zone *zone = zones[i]; | |
1017 | ||
9bf2229f | 1018 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
1019 | continue; |
1020 | ||
1021 | zone->temp_priority = DEF_PRIORITY; | |
1022 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1023 | } | |
1024 | ||
1025 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1da177e4 | 1026 | sc.nr_scanned = 0; |
f7b7fd8f RR |
1027 | if (!priority) |
1028 | disable_swap_token(); | |
1742f19f | 1029 | nr_reclaimed += shrink_zones(priority, zones, &sc); |
1da177e4 LT |
1030 | shrink_slab(sc.nr_scanned, gfp_mask, lru_pages); |
1031 | if (reclaim_state) { | |
05ff5137 | 1032 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1033 | reclaim_state->reclaimed_slab = 0; |
1034 | } | |
1035 | total_scanned += sc.nr_scanned; | |
05ff5137 | 1036 | if (nr_reclaimed >= sc.swap_cluster_max) { |
1da177e4 LT |
1037 | ret = 1; |
1038 | goto out; | |
1039 | } | |
1040 | ||
1041 | /* | |
1042 | * Try to write back as many pages as we just scanned. This | |
1043 | * tends to cause slow streaming writers to write data to the | |
1044 | * disk smoothly, at the dirtying rate, which is nice. But | |
1045 | * that's undesirable in laptop mode, where we *want* lumpy | |
1046 | * writeout. So in laptop mode, write out the whole world. | |
1047 | */ | |
179e9639 AM |
1048 | if (total_scanned > sc.swap_cluster_max + |
1049 | sc.swap_cluster_max / 2) { | |
687a21ce | 1050 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
1da177e4 LT |
1051 | sc.may_writepage = 1; |
1052 | } | |
1053 | ||
1054 | /* Take a nap, wait for some writeback to complete */ | |
1055 | if (sc.nr_scanned && priority < DEF_PRIORITY - 2) | |
1056 | blk_congestion_wait(WRITE, HZ/10); | |
1057 | } | |
408d8544 NP |
1058 | /* top priority shrink_caches still had more to do? don't OOM, then */ |
1059 | if (!sc.all_unreclaimable) | |
1060 | ret = 1; | |
1da177e4 LT |
1061 | out: |
1062 | for (i = 0; zones[i] != 0; i++) { | |
1063 | struct zone *zone = zones[i]; | |
1064 | ||
9bf2229f | 1065 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 LT |
1066 | continue; |
1067 | ||
1068 | zone->prev_priority = zone->temp_priority; | |
1069 | } | |
1070 | return ret; | |
1071 | } | |
1072 | ||
1073 | /* | |
1074 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1075 | * they are all at pages_high. | |
1076 | * | |
1da177e4 LT |
1077 | * Returns the number of pages which were actually freed. |
1078 | * | |
1079 | * There is special handling here for zones which are full of pinned pages. | |
1080 | * This can happen if the pages are all mlocked, or if they are all used by | |
1081 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1082 | * What we do is to detect the case where all pages in the zone have been | |
1083 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1084 | * dead and from now on, only perform a short scan. Basically we're polling | |
1085 | * the zone for when the problem goes away. | |
1086 | * | |
1087 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1088 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1089 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1090 | * of the number of free pages in the lower zones. This interoperates with | |
1091 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1092 | * across the zones. | |
1093 | */ | |
d6277db4 | 1094 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1095 | { |
1da177e4 LT |
1096 | int all_zones_ok; |
1097 | int priority; | |
1098 | int i; | |
69e05944 | 1099 | unsigned long total_scanned; |
05ff5137 | 1100 | unsigned long nr_reclaimed; |
1da177e4 | 1101 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1102 | struct scan_control sc = { |
1103 | .gfp_mask = GFP_KERNEL, | |
1104 | .may_swap = 1, | |
d6277db4 RW |
1105 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1106 | .swappiness = vm_swappiness, | |
179e9639 | 1107 | }; |
1da177e4 LT |
1108 | |
1109 | loop_again: | |
1110 | total_scanned = 0; | |
05ff5137 | 1111 | nr_reclaimed = 0; |
c0bbbc73 | 1112 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1113 | count_vm_event(PAGEOUTRUN); |
1da177e4 LT |
1114 | |
1115 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1116 | struct zone *zone = pgdat->node_zones + i; | |
1117 | ||
1118 | zone->temp_priority = DEF_PRIORITY; | |
1119 | } | |
1120 | ||
1121 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1122 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1123 | unsigned long lru_pages = 0; | |
1124 | ||
f7b7fd8f RR |
1125 | /* The swap token gets in the way of swapout... */ |
1126 | if (!priority) | |
1127 | disable_swap_token(); | |
1128 | ||
1da177e4 LT |
1129 | all_zones_ok = 1; |
1130 | ||
d6277db4 RW |
1131 | /* |
1132 | * Scan in the highmem->dma direction for the highest | |
1133 | * zone which needs scanning | |
1134 | */ | |
1135 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1136 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1137 | |
d6277db4 RW |
1138 | if (!populated_zone(zone)) |
1139 | continue; | |
1da177e4 | 1140 | |
d6277db4 RW |
1141 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1142 | continue; | |
1da177e4 | 1143 | |
d6277db4 RW |
1144 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1145 | 0, 0)) { | |
1146 | end_zone = i; | |
1147 | goto scan; | |
1da177e4 | 1148 | } |
1da177e4 | 1149 | } |
d6277db4 | 1150 | goto out; |
1da177e4 LT |
1151 | scan: |
1152 | for (i = 0; i <= end_zone; i++) { | |
1153 | struct zone *zone = pgdat->node_zones + i; | |
1154 | ||
1155 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1156 | } | |
1157 | ||
1158 | /* | |
1159 | * Now scan the zone in the dma->highmem direction, stopping | |
1160 | * at the last zone which needs scanning. | |
1161 | * | |
1162 | * We do this because the page allocator works in the opposite | |
1163 | * direction. This prevents the page allocator from allocating | |
1164 | * pages behind kswapd's direction of progress, which would | |
1165 | * cause too much scanning of the lower zones. | |
1166 | */ | |
1167 | for (i = 0; i <= end_zone; i++) { | |
1168 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1169 | int nr_slab; |
1da177e4 | 1170 | |
f3fe6512 | 1171 | if (!populated_zone(zone)) |
1da177e4 LT |
1172 | continue; |
1173 | ||
1174 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
1175 | continue; | |
1176 | ||
d6277db4 RW |
1177 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1178 | end_zone, 0)) | |
1179 | all_zones_ok = 0; | |
1da177e4 LT |
1180 | zone->temp_priority = priority; |
1181 | if (zone->prev_priority > priority) | |
1182 | zone->prev_priority = priority; | |
1183 | sc.nr_scanned = 0; | |
05ff5137 | 1184 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
1da177e4 | 1185 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1186 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1187 | lru_pages); | |
05ff5137 | 1188 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1189 | total_scanned += sc.nr_scanned; |
1190 | if (zone->all_unreclaimable) | |
1191 | continue; | |
b15e0905 | 1192 | if (nr_slab == 0 && zone->pages_scanned >= |
4ff1ffb4 | 1193 | (zone->nr_active + zone->nr_inactive) * 6) |
1da177e4 LT |
1194 | zone->all_unreclaimable = 1; |
1195 | /* | |
1196 | * If we've done a decent amount of scanning and | |
1197 | * the reclaim ratio is low, start doing writepage | |
1198 | * even in laptop mode | |
1199 | */ | |
1200 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1201 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1202 | sc.may_writepage = 1; |
1203 | } | |
1da177e4 LT |
1204 | if (all_zones_ok) |
1205 | break; /* kswapd: all done */ | |
1206 | /* | |
1207 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1208 | * another pass across the zones. | |
1209 | */ | |
1210 | if (total_scanned && priority < DEF_PRIORITY - 2) | |
1211 | blk_congestion_wait(WRITE, HZ/10); | |
1212 | ||
1213 | /* | |
1214 | * We do this so kswapd doesn't build up large priorities for | |
1215 | * example when it is freeing in parallel with allocators. It | |
1216 | * matches the direct reclaim path behaviour in terms of impact | |
1217 | * on zone->*_priority. | |
1218 | */ | |
d6277db4 | 1219 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1220 | break; |
1221 | } | |
1222 | out: | |
1223 | for (i = 0; i < pgdat->nr_zones; i++) { | |
1224 | struct zone *zone = pgdat->node_zones + i; | |
1225 | ||
1226 | zone->prev_priority = zone->temp_priority; | |
1227 | } | |
1228 | if (!all_zones_ok) { | |
1229 | cond_resched(); | |
1230 | goto loop_again; | |
1231 | } | |
1232 | ||
05ff5137 | 1233 | return nr_reclaimed; |
1da177e4 LT |
1234 | } |
1235 | ||
1236 | /* | |
1237 | * The background pageout daemon, started as a kernel thread | |
1238 | * from the init process. | |
1239 | * | |
1240 | * This basically trickles out pages so that we have _some_ | |
1241 | * free memory available even if there is no other activity | |
1242 | * that frees anything up. This is needed for things like routing | |
1243 | * etc, where we otherwise might have all activity going on in | |
1244 | * asynchronous contexts that cannot page things out. | |
1245 | * | |
1246 | * If there are applications that are active memory-allocators | |
1247 | * (most normal use), this basically shouldn't matter. | |
1248 | */ | |
1249 | static int kswapd(void *p) | |
1250 | { | |
1251 | unsigned long order; | |
1252 | pg_data_t *pgdat = (pg_data_t*)p; | |
1253 | struct task_struct *tsk = current; | |
1254 | DEFINE_WAIT(wait); | |
1255 | struct reclaim_state reclaim_state = { | |
1256 | .reclaimed_slab = 0, | |
1257 | }; | |
1258 | cpumask_t cpumask; | |
1259 | ||
1da177e4 LT |
1260 | cpumask = node_to_cpumask(pgdat->node_id); |
1261 | if (!cpus_empty(cpumask)) | |
1262 | set_cpus_allowed(tsk, cpumask); | |
1263 | current->reclaim_state = &reclaim_state; | |
1264 | ||
1265 | /* | |
1266 | * Tell the memory management that we're a "memory allocator", | |
1267 | * and that if we need more memory we should get access to it | |
1268 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1269 | * never get caught in the normal page freeing logic. | |
1270 | * | |
1271 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1272 | * you need a small amount of memory in order to be able to | |
1273 | * page out something else, and this flag essentially protects | |
1274 | * us from recursively trying to free more memory as we're | |
1275 | * trying to free the first piece of memory in the first place). | |
1276 | */ | |
930d9152 | 1277 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
1da177e4 LT |
1278 | |
1279 | order = 0; | |
1280 | for ( ; ; ) { | |
1281 | unsigned long new_order; | |
3e1d1d28 CL |
1282 | |
1283 | try_to_freeze(); | |
1da177e4 LT |
1284 | |
1285 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
1286 | new_order = pgdat->kswapd_max_order; | |
1287 | pgdat->kswapd_max_order = 0; | |
1288 | if (order < new_order) { | |
1289 | /* | |
1290 | * Don't sleep if someone wants a larger 'order' | |
1291 | * allocation | |
1292 | */ | |
1293 | order = new_order; | |
1294 | } else { | |
1295 | schedule(); | |
1296 | order = pgdat->kswapd_max_order; | |
1297 | } | |
1298 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1299 | ||
d6277db4 | 1300 | balance_pgdat(pgdat, order); |
1da177e4 LT |
1301 | } |
1302 | return 0; | |
1303 | } | |
1304 | ||
1305 | /* | |
1306 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1307 | */ | |
1308 | void wakeup_kswapd(struct zone *zone, int order) | |
1309 | { | |
1310 | pg_data_t *pgdat; | |
1311 | ||
f3fe6512 | 1312 | if (!populated_zone(zone)) |
1da177e4 LT |
1313 | return; |
1314 | ||
1315 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1316 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1317 | return; |
1318 | if (pgdat->kswapd_max_order < order) | |
1319 | pgdat->kswapd_max_order = order; | |
9bf2229f | 1320 | if (!cpuset_zone_allowed(zone, __GFP_HARDWALL)) |
1da177e4 | 1321 | return; |
8d0986e2 | 1322 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1323 | return; |
8d0986e2 | 1324 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1325 | } |
1326 | ||
1327 | #ifdef CONFIG_PM | |
1328 | /* | |
d6277db4 RW |
1329 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1330 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1331 | * number of reclaimed pages | |
1332 | * | |
1333 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1334 | */ | |
1335 | static unsigned long shrink_all_zones(unsigned long nr_pages, int pass, | |
1336 | int prio, struct scan_control *sc) | |
1337 | { | |
1338 | struct zone *zone; | |
1339 | unsigned long nr_to_scan, ret = 0; | |
1340 | ||
1341 | for_each_zone(zone) { | |
1342 | ||
1343 | if (!populated_zone(zone)) | |
1344 | continue; | |
1345 | ||
1346 | if (zone->all_unreclaimable && prio != DEF_PRIORITY) | |
1347 | continue; | |
1348 | ||
1349 | /* For pass = 0 we don't shrink the active list */ | |
1350 | if (pass > 0) { | |
1351 | zone->nr_scan_active += (zone->nr_active >> prio) + 1; | |
1352 | if (zone->nr_scan_active >= nr_pages || pass > 3) { | |
1353 | zone->nr_scan_active = 0; | |
1354 | nr_to_scan = min(nr_pages, zone->nr_active); | |
1355 | shrink_active_list(nr_to_scan, zone, sc); | |
1356 | } | |
1357 | } | |
1358 | ||
1359 | zone->nr_scan_inactive += (zone->nr_inactive >> prio) + 1; | |
1360 | if (zone->nr_scan_inactive >= nr_pages || pass > 3) { | |
1361 | zone->nr_scan_inactive = 0; | |
1362 | nr_to_scan = min(nr_pages, zone->nr_inactive); | |
1363 | ret += shrink_inactive_list(nr_to_scan, zone, sc); | |
1364 | if (ret >= nr_pages) | |
1365 | return ret; | |
1366 | } | |
1367 | } | |
1368 | ||
1369 | return ret; | |
1370 | } | |
1371 | ||
1372 | /* | |
1373 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
1374 | * freed pages. | |
1375 | * | |
1376 | * Rather than trying to age LRUs the aim is to preserve the overall | |
1377 | * LRU order by reclaiming preferentially | |
1378 | * inactive > active > active referenced > active mapped | |
1da177e4 | 1379 | */ |
69e05944 | 1380 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 1381 | { |
d6277db4 | 1382 | unsigned long lru_pages, nr_slab; |
69e05944 | 1383 | unsigned long ret = 0; |
d6277db4 RW |
1384 | int pass; |
1385 | struct reclaim_state reclaim_state; | |
1386 | struct zone *zone; | |
1387 | struct scan_control sc = { | |
1388 | .gfp_mask = GFP_KERNEL, | |
1389 | .may_swap = 0, | |
1390 | .swap_cluster_max = nr_pages, | |
1391 | .may_writepage = 1, | |
1392 | .swappiness = vm_swappiness, | |
1da177e4 LT |
1393 | }; |
1394 | ||
1395 | current->reclaim_state = &reclaim_state; | |
69e05944 | 1396 | |
d6277db4 RW |
1397 | lru_pages = 0; |
1398 | for_each_zone(zone) | |
1399 | lru_pages += zone->nr_active + zone->nr_inactive; | |
1400 | ||
972d1a7b | 1401 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
1402 | /* If slab caches are huge, it's better to hit them first */ |
1403 | while (nr_slab >= lru_pages) { | |
1404 | reclaim_state.reclaimed_slab = 0; | |
1405 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1406 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 1407 | break; |
d6277db4 RW |
1408 | |
1409 | ret += reclaim_state.reclaimed_slab; | |
1410 | if (ret >= nr_pages) | |
1411 | goto out; | |
1412 | ||
1413 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 1414 | } |
d6277db4 RW |
1415 | |
1416 | /* | |
1417 | * We try to shrink LRUs in 5 passes: | |
1418 | * 0 = Reclaim from inactive_list only | |
1419 | * 1 = Reclaim from active list but don't reclaim mapped | |
1420 | * 2 = 2nd pass of type 1 | |
1421 | * 3 = Reclaim mapped (normal reclaim) | |
1422 | * 4 = 2nd pass of type 3 | |
1423 | */ | |
1424 | for (pass = 0; pass < 5; pass++) { | |
1425 | int prio; | |
1426 | ||
1427 | /* Needed for shrinking slab caches later on */ | |
1428 | if (!lru_pages) | |
1429 | for_each_zone(zone) { | |
1430 | lru_pages += zone->nr_active; | |
1431 | lru_pages += zone->nr_inactive; | |
1432 | } | |
1433 | ||
1434 | /* Force reclaiming mapped pages in the passes #3 and #4 */ | |
1435 | if (pass > 2) { | |
1436 | sc.may_swap = 1; | |
1437 | sc.swappiness = 100; | |
1438 | } | |
1439 | ||
1440 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
1441 | unsigned long nr_to_scan = nr_pages - ret; | |
1442 | ||
d6277db4 | 1443 | sc.nr_scanned = 0; |
d6277db4 RW |
1444 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
1445 | if (ret >= nr_pages) | |
1446 | goto out; | |
1447 | ||
1448 | reclaim_state.reclaimed_slab = 0; | |
1449 | shrink_slab(sc.nr_scanned, sc.gfp_mask, lru_pages); | |
1450 | ret += reclaim_state.reclaimed_slab; | |
1451 | if (ret >= nr_pages) | |
1452 | goto out; | |
1453 | ||
1454 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
1455 | blk_congestion_wait(WRITE, HZ / 10); | |
1456 | } | |
1457 | ||
1458 | lru_pages = 0; | |
248a0301 | 1459 | } |
d6277db4 RW |
1460 | |
1461 | /* | |
1462 | * If ret = 0, we could not shrink LRUs, but there may be something | |
1463 | * in slab caches | |
1464 | */ | |
1465 | if (!ret) | |
1466 | do { | |
1467 | reclaim_state.reclaimed_slab = 0; | |
1468 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1469 | ret += reclaim_state.reclaimed_slab; | |
1470 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
1471 | ||
1472 | out: | |
1da177e4 | 1473 | current->reclaim_state = NULL; |
d6277db4 | 1474 | |
1da177e4 LT |
1475 | return ret; |
1476 | } | |
1477 | #endif | |
1478 | ||
1479 | #ifdef CONFIG_HOTPLUG_CPU | |
1480 | /* It's optimal to keep kswapds on the same CPUs as their memory, but | |
1481 | not required for correctness. So if the last cpu in a node goes | |
1482 | away, we get changed to run anywhere: as the first one comes back, | |
1483 | restore their cpu bindings. */ | |
9c7b216d | 1484 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 1485 | unsigned long action, void *hcpu) |
1da177e4 LT |
1486 | { |
1487 | pg_data_t *pgdat; | |
1488 | cpumask_t mask; | |
1489 | ||
1490 | if (action == CPU_ONLINE) { | |
ec936fc5 | 1491 | for_each_online_pgdat(pgdat) { |
1da177e4 LT |
1492 | mask = node_to_cpumask(pgdat->node_id); |
1493 | if (any_online_cpu(mask) != NR_CPUS) | |
1494 | /* One of our CPUs online: restore mask */ | |
1495 | set_cpus_allowed(pgdat->kswapd, mask); | |
1496 | } | |
1497 | } | |
1498 | return NOTIFY_OK; | |
1499 | } | |
1500 | #endif /* CONFIG_HOTPLUG_CPU */ | |
1501 | ||
3218ae14 YG |
1502 | /* |
1503 | * This kswapd start function will be called by init and node-hot-add. | |
1504 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
1505 | */ | |
1506 | int kswapd_run(int nid) | |
1507 | { | |
1508 | pg_data_t *pgdat = NODE_DATA(nid); | |
1509 | int ret = 0; | |
1510 | ||
1511 | if (pgdat->kswapd) | |
1512 | return 0; | |
1513 | ||
1514 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
1515 | if (IS_ERR(pgdat->kswapd)) { | |
1516 | /* failure at boot is fatal */ | |
1517 | BUG_ON(system_state == SYSTEM_BOOTING); | |
1518 | printk("Failed to start kswapd on node %d\n",nid); | |
1519 | ret = -1; | |
1520 | } | |
1521 | return ret; | |
1522 | } | |
1523 | ||
1da177e4 LT |
1524 | static int __init kswapd_init(void) |
1525 | { | |
3218ae14 | 1526 | int nid; |
69e05944 | 1527 | |
1da177e4 | 1528 | swap_setup(); |
3218ae14 YG |
1529 | for_each_online_node(nid) |
1530 | kswapd_run(nid); | |
1da177e4 LT |
1531 | hotcpu_notifier(cpu_callback, 0); |
1532 | return 0; | |
1533 | } | |
1534 | ||
1535 | module_init(kswapd_init) | |
9eeff239 CL |
1536 | |
1537 | #ifdef CONFIG_NUMA | |
1538 | /* | |
1539 | * Zone reclaim mode | |
1540 | * | |
1541 | * If non-zero call zone_reclaim when the number of free pages falls below | |
1542 | * the watermarks. | |
9eeff239 CL |
1543 | */ |
1544 | int zone_reclaim_mode __read_mostly; | |
1545 | ||
1b2ffb78 CL |
1546 | #define RECLAIM_OFF 0 |
1547 | #define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */ | |
1548 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ | |
1549 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
1550 | ||
a92f7126 CL |
1551 | /* |
1552 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
1553 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
1554 | * a zone. | |
1555 | */ | |
1556 | #define ZONE_RECLAIM_PRIORITY 4 | |
1557 | ||
9614634f CL |
1558 | /* |
1559 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
1560 | * occur. | |
1561 | */ | |
1562 | int sysctl_min_unmapped_ratio = 1; | |
1563 | ||
0ff38490 CL |
1564 | /* |
1565 | * If the number of slab pages in a zone grows beyond this percentage then | |
1566 | * slab reclaim needs to occur. | |
1567 | */ | |
1568 | int sysctl_min_slab_ratio = 5; | |
1569 | ||
9eeff239 CL |
1570 | /* |
1571 | * Try to free up some pages from this zone through reclaim. | |
1572 | */ | |
179e9639 | 1573 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 1574 | { |
7fb2d46d | 1575 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 1576 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
1577 | struct task_struct *p = current; |
1578 | struct reclaim_state reclaim_state; | |
8695949a | 1579 | int priority; |
05ff5137 | 1580 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
1581 | struct scan_control sc = { |
1582 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
1583 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
1584 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
1585 | SWAP_CLUSTER_MAX), | |
179e9639 | 1586 | .gfp_mask = gfp_mask, |
d6277db4 | 1587 | .swappiness = vm_swappiness, |
179e9639 | 1588 | }; |
83e33a47 | 1589 | unsigned long slab_reclaimable; |
9eeff239 CL |
1590 | |
1591 | disable_swap_token(); | |
9eeff239 | 1592 | cond_resched(); |
d4f7796e CL |
1593 | /* |
1594 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
1595 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
1596 | * and RECLAIM_SWAP. | |
1597 | */ | |
1598 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
1599 | reclaim_state.reclaimed_slab = 0; |
1600 | p->reclaim_state = &reclaim_state; | |
c84db23c | 1601 | |
0ff38490 CL |
1602 | if (zone_page_state(zone, NR_FILE_PAGES) - |
1603 | zone_page_state(zone, NR_FILE_MAPPED) > | |
1604 | zone->min_unmapped_pages) { | |
1605 | /* | |
1606 | * Free memory by calling shrink zone with increasing | |
1607 | * priorities until we have enough memory freed. | |
1608 | */ | |
1609 | priority = ZONE_RECLAIM_PRIORITY; | |
1610 | do { | |
1611 | nr_reclaimed += shrink_zone(priority, zone, &sc); | |
1612 | priority--; | |
1613 | } while (priority >= 0 && nr_reclaimed < nr_pages); | |
1614 | } | |
c84db23c | 1615 | |
83e33a47 CL |
1616 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
1617 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 1618 | /* |
7fb2d46d | 1619 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
1620 | * many pages were freed in this zone. So we take the current |
1621 | * number of slab pages and shake the slab until it is reduced | |
1622 | * by the same nr_pages that we used for reclaiming unmapped | |
1623 | * pages. | |
2a16e3f4 | 1624 | * |
0ff38490 CL |
1625 | * Note that shrink_slab will free memory on all zones and may |
1626 | * take a long time. | |
2a16e3f4 | 1627 | */ |
0ff38490 | 1628 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
1629 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
1630 | slab_reclaimable - nr_pages) | |
0ff38490 | 1631 | ; |
83e33a47 CL |
1632 | |
1633 | /* | |
1634 | * Update nr_reclaimed by the number of slab pages we | |
1635 | * reclaimed from this zone. | |
1636 | */ | |
1637 | nr_reclaimed += slab_reclaimable - | |
1638 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); | |
2a16e3f4 CL |
1639 | } |
1640 | ||
9eeff239 | 1641 | p->reclaim_state = NULL; |
d4f7796e | 1642 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
05ff5137 | 1643 | return nr_reclaimed >= nr_pages; |
9eeff239 | 1644 | } |
179e9639 AM |
1645 | |
1646 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
1647 | { | |
1648 | cpumask_t mask; | |
1649 | int node_id; | |
1650 | ||
1651 | /* | |
0ff38490 CL |
1652 | * Zone reclaim reclaims unmapped file backed pages and |
1653 | * slab pages if we are over the defined limits. | |
34aa1330 | 1654 | * |
9614634f CL |
1655 | * A small portion of unmapped file backed pages is needed for |
1656 | * file I/O otherwise pages read by file I/O will be immediately | |
1657 | * thrown out if the zone is overallocated. So we do not reclaim | |
1658 | * if less than a specified percentage of the zone is used by | |
1659 | * unmapped file backed pages. | |
179e9639 | 1660 | */ |
34aa1330 | 1661 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
1662 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
1663 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
1664 | <= zone->min_slab_pages) | |
9614634f | 1665 | return 0; |
179e9639 AM |
1666 | |
1667 | /* | |
1668 | * Avoid concurrent zone reclaims, do not reclaim in a zone that does | |
1669 | * not have reclaimable pages and if we should not delay the allocation | |
1670 | * then do not scan. | |
1671 | */ | |
1672 | if (!(gfp_mask & __GFP_WAIT) || | |
1673 | zone->all_unreclaimable || | |
1674 | atomic_read(&zone->reclaim_in_progress) > 0 || | |
1675 | (current->flags & PF_MEMALLOC)) | |
1676 | return 0; | |
1677 | ||
1678 | /* | |
1679 | * Only run zone reclaim on the local zone or on zones that do not | |
1680 | * have associated processors. This will favor the local processor | |
1681 | * over remote processors and spread off node memory allocations | |
1682 | * as wide as possible. | |
1683 | */ | |
89fa3024 | 1684 | node_id = zone_to_nid(zone); |
179e9639 AM |
1685 | mask = node_to_cpumask(node_id); |
1686 | if (!cpus_empty(mask) && node_id != numa_node_id()) | |
1687 | return 0; | |
1688 | return __zone_reclaim(zone, gfp_mask, order); | |
1689 | } | |
9eeff239 | 1690 | #endif |