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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/kernel_stat.h> | |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
27 | buffer_heads_over_limit */ | |
28 | #include <linux/mm_inline.h> | |
29 | #include <linux/pagevec.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/rmap.h> | |
32 | #include <linux/topology.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cpuset.h> | |
35 | #include <linux/notifier.h> | |
36 | #include <linux/rwsem.h> | |
248a0301 | 37 | #include <linux/delay.h> |
3218ae14 | 38 | #include <linux/kthread.h> |
7dfb7103 | 39 | #include <linux/freezer.h> |
66e1707b | 40 | #include <linux/memcontrol.h> |
1da177e4 LT |
41 | |
42 | #include <asm/tlbflush.h> | |
43 | #include <asm/div64.h> | |
44 | ||
45 | #include <linux/swapops.h> | |
46 | ||
0f8053a5 NP |
47 | #include "internal.h" |
48 | ||
1da177e4 | 49 | struct scan_control { |
1da177e4 LT |
50 | /* Incremented by the number of inactive pages that were scanned */ |
51 | unsigned long nr_scanned; | |
52 | ||
1da177e4 | 53 | /* This context's GFP mask */ |
6daa0e28 | 54 | gfp_t gfp_mask; |
1da177e4 LT |
55 | |
56 | int may_writepage; | |
57 | ||
f1fd1067 CL |
58 | /* Can pages be swapped as part of reclaim? */ |
59 | int may_swap; | |
60 | ||
1da177e4 LT |
61 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
62 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
63 | * In this context, it doesn't matter that we scan the | |
64 | * whole list at once. */ | |
65 | int swap_cluster_max; | |
d6277db4 RW |
66 | |
67 | int swappiness; | |
408d8544 NP |
68 | |
69 | int all_unreclaimable; | |
5ad333eb AW |
70 | |
71 | int order; | |
66e1707b | 72 | |
f1a9ee75 RR |
73 | /* |
74 | * Pages that have (or should have) IO pending. If we run into | |
75 | * a lot of these, we're better off waiting a little for IO to | |
76 | * finish rather than scanning more pages in the VM. | |
77 | */ | |
78 | int nr_io_pages; | |
79 | ||
66e1707b BS |
80 | /* Which cgroup do we reclaim from */ |
81 | struct mem_cgroup *mem_cgroup; | |
82 | ||
83 | /* Pluggable isolate pages callback */ | |
84 | unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst, | |
85 | unsigned long *scanned, int order, int mode, | |
86 | struct zone *z, struct mem_cgroup *mem_cont, | |
87 | int active); | |
1da177e4 LT |
88 | }; |
89 | ||
1da177e4 LT |
90 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
91 | ||
92 | #ifdef ARCH_HAS_PREFETCH | |
93 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
94 | do { \ | |
95 | if ((_page)->lru.prev != _base) { \ | |
96 | struct page *prev; \ | |
97 | \ | |
98 | prev = lru_to_page(&(_page->lru)); \ | |
99 | prefetch(&prev->_field); \ | |
100 | } \ | |
101 | } while (0) | |
102 | #else | |
103 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
104 | #endif | |
105 | ||
106 | #ifdef ARCH_HAS_PREFETCHW | |
107 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
108 | do { \ | |
109 | if ((_page)->lru.prev != _base) { \ | |
110 | struct page *prev; \ | |
111 | \ | |
112 | prev = lru_to_page(&(_page->lru)); \ | |
113 | prefetchw(&prev->_field); \ | |
114 | } \ | |
115 | } while (0) | |
116 | #else | |
117 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
118 | #endif | |
119 | ||
120 | /* | |
121 | * From 0 .. 100. Higher means more swappy. | |
122 | */ | |
123 | int vm_swappiness = 60; | |
bd1e22b8 | 124 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
125 | |
126 | static LIST_HEAD(shrinker_list); | |
127 | static DECLARE_RWSEM(shrinker_rwsem); | |
128 | ||
91a45470 KH |
129 | #ifdef CONFIG_CGROUP_MEM_CONT |
130 | #define scan_global_lru(sc) (!(sc)->mem_cgroup) | |
131 | #else | |
132 | #define scan_global_lru(sc) (1) | |
133 | #endif | |
134 | ||
1da177e4 LT |
135 | /* |
136 | * Add a shrinker callback to be called from the vm | |
137 | */ | |
8e1f936b | 138 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 139 | { |
8e1f936b RR |
140 | shrinker->nr = 0; |
141 | down_write(&shrinker_rwsem); | |
142 | list_add_tail(&shrinker->list, &shrinker_list); | |
143 | up_write(&shrinker_rwsem); | |
1da177e4 | 144 | } |
8e1f936b | 145 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
146 | |
147 | /* | |
148 | * Remove one | |
149 | */ | |
8e1f936b | 150 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
151 | { |
152 | down_write(&shrinker_rwsem); | |
153 | list_del(&shrinker->list); | |
154 | up_write(&shrinker_rwsem); | |
1da177e4 | 155 | } |
8e1f936b | 156 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
157 | |
158 | #define SHRINK_BATCH 128 | |
159 | /* | |
160 | * Call the shrink functions to age shrinkable caches | |
161 | * | |
162 | * Here we assume it costs one seek to replace a lru page and that it also | |
163 | * takes a seek to recreate a cache object. With this in mind we age equal | |
164 | * percentages of the lru and ageable caches. This should balance the seeks | |
165 | * generated by these structures. | |
166 | * | |
183ff22b | 167 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
168 | * slab to avoid swapping. |
169 | * | |
170 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
171 | * | |
172 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
173 | * are eligible for the caller's allocation attempt. It is used for balancing | |
174 | * slab reclaim versus page reclaim. | |
b15e0905 | 175 | * |
176 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 177 | */ |
69e05944 AM |
178 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
179 | unsigned long lru_pages) | |
1da177e4 LT |
180 | { |
181 | struct shrinker *shrinker; | |
69e05944 | 182 | unsigned long ret = 0; |
1da177e4 LT |
183 | |
184 | if (scanned == 0) | |
185 | scanned = SWAP_CLUSTER_MAX; | |
186 | ||
187 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 188 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
189 | |
190 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
191 | unsigned long long delta; | |
192 | unsigned long total_scan; | |
8e1f936b | 193 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
1da177e4 LT |
194 | |
195 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 196 | delta *= max_pass; |
1da177e4 LT |
197 | do_div(delta, lru_pages + 1); |
198 | shrinker->nr += delta; | |
ea164d73 AA |
199 | if (shrinker->nr < 0) { |
200 | printk(KERN_ERR "%s: nr=%ld\n", | |
201 | __FUNCTION__, shrinker->nr); | |
202 | shrinker->nr = max_pass; | |
203 | } | |
204 | ||
205 | /* | |
206 | * Avoid risking looping forever due to too large nr value: | |
207 | * never try to free more than twice the estimate number of | |
208 | * freeable entries. | |
209 | */ | |
210 | if (shrinker->nr > max_pass * 2) | |
211 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
212 | |
213 | total_scan = shrinker->nr; | |
214 | shrinker->nr = 0; | |
215 | ||
216 | while (total_scan >= SHRINK_BATCH) { | |
217 | long this_scan = SHRINK_BATCH; | |
218 | int shrink_ret; | |
b15e0905 | 219 | int nr_before; |
1da177e4 | 220 | |
8e1f936b RR |
221 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
222 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); | |
1da177e4 LT |
223 | if (shrink_ret == -1) |
224 | break; | |
b15e0905 | 225 | if (shrink_ret < nr_before) |
226 | ret += nr_before - shrink_ret; | |
f8891e5e | 227 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
228 | total_scan -= this_scan; |
229 | ||
230 | cond_resched(); | |
231 | } | |
232 | ||
233 | shrinker->nr += total_scan; | |
234 | } | |
235 | up_read(&shrinker_rwsem); | |
b15e0905 | 236 | return ret; |
1da177e4 LT |
237 | } |
238 | ||
239 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
240 | static inline int page_mapping_inuse(struct page *page) | |
241 | { | |
242 | struct address_space *mapping; | |
243 | ||
244 | /* Page is in somebody's page tables. */ | |
245 | if (page_mapped(page)) | |
246 | return 1; | |
247 | ||
248 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
249 | if (PageSwapCache(page)) | |
250 | return 1; | |
251 | ||
252 | mapping = page_mapping(page); | |
253 | if (!mapping) | |
254 | return 0; | |
255 | ||
256 | /* File is mmap'd by somebody? */ | |
257 | return mapping_mapped(mapping); | |
258 | } | |
259 | ||
260 | static inline int is_page_cache_freeable(struct page *page) | |
261 | { | |
262 | return page_count(page) - !!PagePrivate(page) == 2; | |
263 | } | |
264 | ||
265 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
266 | { | |
930d9152 | 267 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
268 | return 1; |
269 | if (!bdi_write_congested(bdi)) | |
270 | return 1; | |
271 | if (bdi == current->backing_dev_info) | |
272 | return 1; | |
273 | return 0; | |
274 | } | |
275 | ||
276 | /* | |
277 | * We detected a synchronous write error writing a page out. Probably | |
278 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
279 | * fsync(), msync() or close(). | |
280 | * | |
281 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
282 | * prevents it from being freed up. But we have a ref on the page and once | |
283 | * that page is locked, the mapping is pinned. | |
284 | * | |
285 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
286 | * __GFP_FS. | |
287 | */ | |
288 | static void handle_write_error(struct address_space *mapping, | |
289 | struct page *page, int error) | |
290 | { | |
291 | lock_page(page); | |
3e9f45bd GC |
292 | if (page_mapping(page) == mapping) |
293 | mapping_set_error(mapping, error); | |
1da177e4 LT |
294 | unlock_page(page); |
295 | } | |
296 | ||
c661b078 AW |
297 | /* Request for sync pageout. */ |
298 | enum pageout_io { | |
299 | PAGEOUT_IO_ASYNC, | |
300 | PAGEOUT_IO_SYNC, | |
301 | }; | |
302 | ||
04e62a29 CL |
303 | /* possible outcome of pageout() */ |
304 | typedef enum { | |
305 | /* failed to write page out, page is locked */ | |
306 | PAGE_KEEP, | |
307 | /* move page to the active list, page is locked */ | |
308 | PAGE_ACTIVATE, | |
309 | /* page has been sent to the disk successfully, page is unlocked */ | |
310 | PAGE_SUCCESS, | |
311 | /* page is clean and locked */ | |
312 | PAGE_CLEAN, | |
313 | } pageout_t; | |
314 | ||
1da177e4 | 315 | /* |
1742f19f AM |
316 | * pageout is called by shrink_page_list() for each dirty page. |
317 | * Calls ->writepage(). | |
1da177e4 | 318 | */ |
c661b078 AW |
319 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
320 | enum pageout_io sync_writeback) | |
1da177e4 LT |
321 | { |
322 | /* | |
323 | * If the page is dirty, only perform writeback if that write | |
324 | * will be non-blocking. To prevent this allocation from being | |
325 | * stalled by pagecache activity. But note that there may be | |
326 | * stalls if we need to run get_block(). We could test | |
327 | * PagePrivate for that. | |
328 | * | |
329 | * If this process is currently in generic_file_write() against | |
330 | * this page's queue, we can perform writeback even if that | |
331 | * will block. | |
332 | * | |
333 | * If the page is swapcache, write it back even if that would | |
334 | * block, for some throttling. This happens by accident, because | |
335 | * swap_backing_dev_info is bust: it doesn't reflect the | |
336 | * congestion state of the swapdevs. Easy to fix, if needed. | |
337 | * See swapfile.c:page_queue_congested(). | |
338 | */ | |
339 | if (!is_page_cache_freeable(page)) | |
340 | return PAGE_KEEP; | |
341 | if (!mapping) { | |
342 | /* | |
343 | * Some data journaling orphaned pages can have | |
344 | * page->mapping == NULL while being dirty with clean buffers. | |
345 | */ | |
323aca6c | 346 | if (PagePrivate(page)) { |
1da177e4 LT |
347 | if (try_to_free_buffers(page)) { |
348 | ClearPageDirty(page); | |
349 | printk("%s: orphaned page\n", __FUNCTION__); | |
350 | return PAGE_CLEAN; | |
351 | } | |
352 | } | |
353 | return PAGE_KEEP; | |
354 | } | |
355 | if (mapping->a_ops->writepage == NULL) | |
356 | return PAGE_ACTIVATE; | |
357 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
358 | return PAGE_KEEP; | |
359 | ||
360 | if (clear_page_dirty_for_io(page)) { | |
361 | int res; | |
362 | struct writeback_control wbc = { | |
363 | .sync_mode = WB_SYNC_NONE, | |
364 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
365 | .range_start = 0, |
366 | .range_end = LLONG_MAX, | |
1da177e4 LT |
367 | .nonblocking = 1, |
368 | .for_reclaim = 1, | |
369 | }; | |
370 | ||
371 | SetPageReclaim(page); | |
372 | res = mapping->a_ops->writepage(page, &wbc); | |
373 | if (res < 0) | |
374 | handle_write_error(mapping, page, res); | |
994fc28c | 375 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
376 | ClearPageReclaim(page); |
377 | return PAGE_ACTIVATE; | |
378 | } | |
c661b078 AW |
379 | |
380 | /* | |
381 | * Wait on writeback if requested to. This happens when | |
382 | * direct reclaiming a large contiguous area and the | |
383 | * first attempt to free a range of pages fails. | |
384 | */ | |
385 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
386 | wait_on_page_writeback(page); | |
387 | ||
1da177e4 LT |
388 | if (!PageWriteback(page)) { |
389 | /* synchronous write or broken a_ops? */ | |
390 | ClearPageReclaim(page); | |
391 | } | |
e129b5c2 | 392 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
393 | return PAGE_SUCCESS; |
394 | } | |
395 | ||
396 | return PAGE_CLEAN; | |
397 | } | |
398 | ||
a649fd92 AM |
399 | /* |
400 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
401 | * someone else has a ref on the page, abort and return 0. If it was | |
402 | * successfully detached, return 1. Assumes the caller has a single ref on | |
403 | * this page. | |
404 | */ | |
b20a3503 | 405 | int remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 406 | { |
28e4d965 NP |
407 | BUG_ON(!PageLocked(page)); |
408 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc CL |
409 | |
410 | write_lock_irq(&mapping->tree_lock); | |
49d2e9cc | 411 | /* |
0fd0e6b0 NP |
412 | * The non racy check for a busy page. |
413 | * | |
414 | * Must be careful with the order of the tests. When someone has | |
415 | * a ref to the page, it may be possible that they dirty it then | |
416 | * drop the reference. So if PageDirty is tested before page_count | |
417 | * here, then the following race may occur: | |
418 | * | |
419 | * get_user_pages(&page); | |
420 | * [user mapping goes away] | |
421 | * write_to(page); | |
422 | * !PageDirty(page) [good] | |
423 | * SetPageDirty(page); | |
424 | * put_page(page); | |
425 | * !page_count(page) [good, discard it] | |
426 | * | |
427 | * [oops, our write_to data is lost] | |
428 | * | |
429 | * Reversing the order of the tests ensures such a situation cannot | |
430 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
431 | * load is not satisfied before that of page->_count. | |
432 | * | |
433 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
434 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc CL |
435 | */ |
436 | if (unlikely(page_count(page) != 2)) | |
437 | goto cannot_free; | |
438 | smp_rmb(); | |
439 | if (unlikely(PageDirty(page))) | |
440 | goto cannot_free; | |
441 | ||
442 | if (PageSwapCache(page)) { | |
443 | swp_entry_t swap = { .val = page_private(page) }; | |
444 | __delete_from_swap_cache(page); | |
445 | write_unlock_irq(&mapping->tree_lock); | |
446 | swap_free(swap); | |
447 | __put_page(page); /* The pagecache ref */ | |
448 | return 1; | |
449 | } | |
450 | ||
451 | __remove_from_page_cache(page); | |
452 | write_unlock_irq(&mapping->tree_lock); | |
453 | __put_page(page); | |
454 | return 1; | |
455 | ||
456 | cannot_free: | |
457 | write_unlock_irq(&mapping->tree_lock); | |
458 | return 0; | |
459 | } | |
460 | ||
1da177e4 | 461 | /* |
1742f19f | 462 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 463 | */ |
1742f19f | 464 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
465 | struct scan_control *sc, |
466 | enum pageout_io sync_writeback) | |
1da177e4 LT |
467 | { |
468 | LIST_HEAD(ret_pages); | |
469 | struct pagevec freed_pvec; | |
470 | int pgactivate = 0; | |
05ff5137 | 471 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
472 | |
473 | cond_resched(); | |
474 | ||
475 | pagevec_init(&freed_pvec, 1); | |
476 | while (!list_empty(page_list)) { | |
477 | struct address_space *mapping; | |
478 | struct page *page; | |
479 | int may_enter_fs; | |
480 | int referenced; | |
481 | ||
482 | cond_resched(); | |
483 | ||
484 | page = lru_to_page(page_list); | |
485 | list_del(&page->lru); | |
486 | ||
487 | if (TestSetPageLocked(page)) | |
488 | goto keep; | |
489 | ||
725d704e | 490 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
491 | |
492 | sc->nr_scanned++; | |
80e43426 CL |
493 | |
494 | if (!sc->may_swap && page_mapped(page)) | |
495 | goto keep_locked; | |
496 | ||
1da177e4 LT |
497 | /* Double the slab pressure for mapped and swapcache pages */ |
498 | if (page_mapped(page) || PageSwapCache(page)) | |
499 | sc->nr_scanned++; | |
500 | ||
c661b078 AW |
501 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
502 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
503 | ||
504 | if (PageWriteback(page)) { | |
505 | /* | |
506 | * Synchronous reclaim is performed in two passes, | |
507 | * first an asynchronous pass over the list to | |
508 | * start parallel writeback, and a second synchronous | |
509 | * pass to wait for the IO to complete. Wait here | |
510 | * for any page for which writeback has already | |
511 | * started. | |
512 | */ | |
513 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
514 | wait_on_page_writeback(page); | |
f1a9ee75 RR |
515 | else { |
516 | sc->nr_io_pages++; | |
c661b078 | 517 | goto keep_locked; |
f1a9ee75 | 518 | } |
c661b078 | 519 | } |
1da177e4 | 520 | |
bed7161a | 521 | referenced = page_referenced(page, 1, sc->mem_cgroup); |
1da177e4 | 522 | /* In active use or really unfreeable? Activate it. */ |
5ad333eb AW |
523 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && |
524 | referenced && page_mapping_inuse(page)) | |
1da177e4 LT |
525 | goto activate_locked; |
526 | ||
527 | #ifdef CONFIG_SWAP | |
528 | /* | |
529 | * Anonymous process memory has backing store? | |
530 | * Try to allocate it some swap space here. | |
531 | */ | |
6e5ef1a9 | 532 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 533 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 534 | goto activate_locked; |
1da177e4 LT |
535 | #endif /* CONFIG_SWAP */ |
536 | ||
537 | mapping = page_mapping(page); | |
1da177e4 LT |
538 | |
539 | /* | |
540 | * The page is mapped into the page tables of one or more | |
541 | * processes. Try to unmap it here. | |
542 | */ | |
543 | if (page_mapped(page) && mapping) { | |
a48d07af | 544 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
545 | case SWAP_FAIL: |
546 | goto activate_locked; | |
547 | case SWAP_AGAIN: | |
548 | goto keep_locked; | |
549 | case SWAP_SUCCESS: | |
550 | ; /* try to free the page below */ | |
551 | } | |
552 | } | |
553 | ||
554 | if (PageDirty(page)) { | |
5ad333eb | 555 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) |
1da177e4 | 556 | goto keep_locked; |
f1a9ee75 RR |
557 | if (!may_enter_fs) { |
558 | sc->nr_io_pages++; | |
1da177e4 | 559 | goto keep_locked; |
f1a9ee75 | 560 | } |
52a8363e | 561 | if (!sc->may_writepage) |
1da177e4 LT |
562 | goto keep_locked; |
563 | ||
564 | /* Page is dirty, try to write it out here */ | |
c661b078 | 565 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
566 | case PAGE_KEEP: |
567 | goto keep_locked; | |
568 | case PAGE_ACTIVATE: | |
569 | goto activate_locked; | |
570 | case PAGE_SUCCESS: | |
f1a9ee75 RR |
571 | if (PageWriteback(page) || PageDirty(page)) { |
572 | sc->nr_io_pages++; | |
1da177e4 | 573 | goto keep; |
f1a9ee75 | 574 | } |
1da177e4 LT |
575 | /* |
576 | * A synchronous write - probably a ramdisk. Go | |
577 | * ahead and try to reclaim the page. | |
578 | */ | |
579 | if (TestSetPageLocked(page)) | |
580 | goto keep; | |
581 | if (PageDirty(page) || PageWriteback(page)) | |
582 | goto keep_locked; | |
583 | mapping = page_mapping(page); | |
584 | case PAGE_CLEAN: | |
585 | ; /* try to free the page below */ | |
586 | } | |
587 | } | |
588 | ||
589 | /* | |
590 | * If the page has buffers, try to free the buffer mappings | |
591 | * associated with this page. If we succeed we try to free | |
592 | * the page as well. | |
593 | * | |
594 | * We do this even if the page is PageDirty(). | |
595 | * try_to_release_page() does not perform I/O, but it is | |
596 | * possible for a page to have PageDirty set, but it is actually | |
597 | * clean (all its buffers are clean). This happens if the | |
598 | * buffers were written out directly, with submit_bh(). ext3 | |
599 | * will do this, as well as the blockdev mapping. | |
600 | * try_to_release_page() will discover that cleanness and will | |
601 | * drop the buffers and mark the page clean - it can be freed. | |
602 | * | |
603 | * Rarely, pages can have buffers and no ->mapping. These are | |
604 | * the pages which were not successfully invalidated in | |
605 | * truncate_complete_page(). We try to drop those buffers here | |
606 | * and if that worked, and the page is no longer mapped into | |
607 | * process address space (page_count == 1) it can be freed. | |
608 | * Otherwise, leave the page on the LRU so it is swappable. | |
609 | */ | |
610 | if (PagePrivate(page)) { | |
611 | if (!try_to_release_page(page, sc->gfp_mask)) | |
612 | goto activate_locked; | |
613 | if (!mapping && page_count(page) == 1) | |
614 | goto free_it; | |
615 | } | |
616 | ||
28e4d965 | 617 | if (!mapping || !remove_mapping(mapping, page)) |
49d2e9cc | 618 | goto keep_locked; |
1da177e4 LT |
619 | |
620 | free_it: | |
621 | unlock_page(page); | |
05ff5137 | 622 | nr_reclaimed++; |
1da177e4 LT |
623 | if (!pagevec_add(&freed_pvec, page)) |
624 | __pagevec_release_nonlru(&freed_pvec); | |
625 | continue; | |
626 | ||
627 | activate_locked: | |
628 | SetPageActive(page); | |
629 | pgactivate++; | |
630 | keep_locked: | |
631 | unlock_page(page); | |
632 | keep: | |
633 | list_add(&page->lru, &ret_pages); | |
725d704e | 634 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
635 | } |
636 | list_splice(&ret_pages, page_list); | |
637 | if (pagevec_count(&freed_pvec)) | |
638 | __pagevec_release_nonlru(&freed_pvec); | |
f8891e5e | 639 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 640 | return nr_reclaimed; |
1da177e4 LT |
641 | } |
642 | ||
5ad333eb AW |
643 | /* LRU Isolation modes. */ |
644 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ | |
645 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ | |
646 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ | |
647 | ||
648 | /* | |
649 | * Attempt to remove the specified page from its LRU. Only take this page | |
650 | * if it is of the appropriate PageActive status. Pages which are being | |
651 | * freed elsewhere are also ignored. | |
652 | * | |
653 | * page: page to consider | |
654 | * mode: one of the LRU isolation modes defined above | |
655 | * | |
656 | * returns 0 on success, -ve errno on failure. | |
657 | */ | |
66e1707b | 658 | int __isolate_lru_page(struct page *page, int mode) |
5ad333eb AW |
659 | { |
660 | int ret = -EINVAL; | |
661 | ||
662 | /* Only take pages on the LRU. */ | |
663 | if (!PageLRU(page)) | |
664 | return ret; | |
665 | ||
666 | /* | |
667 | * When checking the active state, we need to be sure we are | |
668 | * dealing with comparible boolean values. Take the logical not | |
669 | * of each. | |
670 | */ | |
671 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
672 | return ret; | |
673 | ||
674 | ret = -EBUSY; | |
675 | if (likely(get_page_unless_zero(page))) { | |
676 | /* | |
677 | * Be careful not to clear PageLRU until after we're | |
678 | * sure the page is not being freed elsewhere -- the | |
679 | * page release code relies on it. | |
680 | */ | |
681 | ClearPageLRU(page); | |
682 | ret = 0; | |
683 | } | |
684 | ||
685 | return ret; | |
686 | } | |
687 | ||
1da177e4 LT |
688 | /* |
689 | * zone->lru_lock is heavily contended. Some of the functions that | |
690 | * shrink the lists perform better by taking out a batch of pages | |
691 | * and working on them outside the LRU lock. | |
692 | * | |
693 | * For pagecache intensive workloads, this function is the hottest | |
694 | * spot in the kernel (apart from copy_*_user functions). | |
695 | * | |
696 | * Appropriate locks must be held before calling this function. | |
697 | * | |
698 | * @nr_to_scan: The number of pages to look through on the list. | |
699 | * @src: The LRU list to pull pages off. | |
700 | * @dst: The temp list to put pages on to. | |
701 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
702 | * @order: The caller's attempted allocation order |
703 | * @mode: One of the LRU isolation modes | |
1da177e4 LT |
704 | * |
705 | * returns how many pages were moved onto *@dst. | |
706 | */ | |
69e05944 AM |
707 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
708 | struct list_head *src, struct list_head *dst, | |
5ad333eb | 709 | unsigned long *scanned, int order, int mode) |
1da177e4 | 710 | { |
69e05944 | 711 | unsigned long nr_taken = 0; |
c9b02d97 | 712 | unsigned long scan; |
1da177e4 | 713 | |
c9b02d97 | 714 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
715 | struct page *page; |
716 | unsigned long pfn; | |
717 | unsigned long end_pfn; | |
718 | unsigned long page_pfn; | |
719 | int zone_id; | |
720 | ||
1da177e4 LT |
721 | page = lru_to_page(src); |
722 | prefetchw_prev_lru_page(page, src, flags); | |
723 | ||
725d704e | 724 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 725 | |
5ad333eb AW |
726 | switch (__isolate_lru_page(page, mode)) { |
727 | case 0: | |
728 | list_move(&page->lru, dst); | |
7c8ee9a8 | 729 | nr_taken++; |
5ad333eb AW |
730 | break; |
731 | ||
732 | case -EBUSY: | |
733 | /* else it is being freed elsewhere */ | |
734 | list_move(&page->lru, src); | |
735 | continue; | |
46453a6e | 736 | |
5ad333eb AW |
737 | default: |
738 | BUG(); | |
739 | } | |
740 | ||
741 | if (!order) | |
742 | continue; | |
743 | ||
744 | /* | |
745 | * Attempt to take all pages in the order aligned region | |
746 | * surrounding the tag page. Only take those pages of | |
747 | * the same active state as that tag page. We may safely | |
748 | * round the target page pfn down to the requested order | |
749 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
750 | * where that page is in a different zone we will detect | |
751 | * it from its zone id and abort this block scan. | |
752 | */ | |
753 | zone_id = page_zone_id(page); | |
754 | page_pfn = page_to_pfn(page); | |
755 | pfn = page_pfn & ~((1 << order) - 1); | |
756 | end_pfn = pfn + (1 << order); | |
757 | for (; pfn < end_pfn; pfn++) { | |
758 | struct page *cursor_page; | |
759 | ||
760 | /* The target page is in the block, ignore it. */ | |
761 | if (unlikely(pfn == page_pfn)) | |
762 | continue; | |
763 | ||
764 | /* Avoid holes within the zone. */ | |
765 | if (unlikely(!pfn_valid_within(pfn))) | |
766 | break; | |
767 | ||
768 | cursor_page = pfn_to_page(pfn); | |
769 | /* Check that we have not crossed a zone boundary. */ | |
770 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
771 | continue; | |
772 | switch (__isolate_lru_page(cursor_page, mode)) { | |
773 | case 0: | |
774 | list_move(&cursor_page->lru, dst); | |
775 | nr_taken++; | |
776 | scan++; | |
777 | break; | |
778 | ||
779 | case -EBUSY: | |
780 | /* else it is being freed elsewhere */ | |
781 | list_move(&cursor_page->lru, src); | |
782 | default: | |
783 | break; | |
784 | } | |
785 | } | |
1da177e4 LT |
786 | } |
787 | ||
788 | *scanned = scan; | |
789 | return nr_taken; | |
790 | } | |
791 | ||
66e1707b BS |
792 | static unsigned long isolate_pages_global(unsigned long nr, |
793 | struct list_head *dst, | |
794 | unsigned long *scanned, int order, | |
795 | int mode, struct zone *z, | |
796 | struct mem_cgroup *mem_cont, | |
797 | int active) | |
798 | { | |
799 | if (active) | |
800 | return isolate_lru_pages(nr, &z->active_list, dst, | |
801 | scanned, order, mode); | |
802 | else | |
803 | return isolate_lru_pages(nr, &z->inactive_list, dst, | |
804 | scanned, order, mode); | |
805 | } | |
806 | ||
5ad333eb AW |
807 | /* |
808 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
809 | * any active bits from the pages in the list. | |
810 | */ | |
811 | static unsigned long clear_active_flags(struct list_head *page_list) | |
812 | { | |
813 | int nr_active = 0; | |
814 | struct page *page; | |
815 | ||
816 | list_for_each_entry(page, page_list, lru) | |
817 | if (PageActive(page)) { | |
818 | ClearPageActive(page); | |
819 | nr_active++; | |
820 | } | |
821 | ||
822 | return nr_active; | |
823 | } | |
824 | ||
1da177e4 | 825 | /* |
1742f19f AM |
826 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
827 | * of reclaimed pages | |
1da177e4 | 828 | */ |
1742f19f AM |
829 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
830 | struct zone *zone, struct scan_control *sc) | |
1da177e4 LT |
831 | { |
832 | LIST_HEAD(page_list); | |
833 | struct pagevec pvec; | |
69e05944 | 834 | unsigned long nr_scanned = 0; |
05ff5137 | 835 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
836 | |
837 | pagevec_init(&pvec, 1); | |
838 | ||
839 | lru_add_drain(); | |
840 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 841 | do { |
1da177e4 | 842 | struct page *page; |
69e05944 AM |
843 | unsigned long nr_taken; |
844 | unsigned long nr_scan; | |
845 | unsigned long nr_freed; | |
5ad333eb | 846 | unsigned long nr_active; |
1da177e4 | 847 | |
66e1707b | 848 | nr_taken = sc->isolate_pages(sc->swap_cluster_max, |
5ad333eb AW |
849 | &page_list, &nr_scan, sc->order, |
850 | (sc->order > PAGE_ALLOC_COSTLY_ORDER)? | |
66e1707b BS |
851 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
852 | zone, sc->mem_cgroup, 0); | |
5ad333eb | 853 | nr_active = clear_active_flags(&page_list); |
e9187bdc | 854 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb AW |
855 | |
856 | __mod_zone_page_state(zone, NR_ACTIVE, -nr_active); | |
857 | __mod_zone_page_state(zone, NR_INACTIVE, | |
858 | -(nr_taken - nr_active)); | |
1cfb419b KH |
859 | if (scan_global_lru(sc)) |
860 | zone->pages_scanned += nr_scan; | |
1da177e4 LT |
861 | spin_unlock_irq(&zone->lru_lock); |
862 | ||
69e05944 | 863 | nr_scanned += nr_scan; |
c661b078 AW |
864 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
865 | ||
866 | /* | |
867 | * If we are direct reclaiming for contiguous pages and we do | |
868 | * not reclaim everything in the list, try again and wait | |
869 | * for IO to complete. This will stall high-order allocations | |
870 | * but that should be acceptable to the caller | |
871 | */ | |
872 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
873 | sc->order > PAGE_ALLOC_COSTLY_ORDER) { | |
874 | congestion_wait(WRITE, HZ/10); | |
875 | ||
876 | /* | |
877 | * The attempt at page out may have made some | |
878 | * of the pages active, mark them inactive again. | |
879 | */ | |
880 | nr_active = clear_active_flags(&page_list); | |
881 | count_vm_events(PGDEACTIVATE, nr_active); | |
882 | ||
883 | nr_freed += shrink_page_list(&page_list, sc, | |
884 | PAGEOUT_IO_SYNC); | |
885 | } | |
886 | ||
05ff5137 | 887 | nr_reclaimed += nr_freed; |
a74609fa NP |
888 | local_irq_disable(); |
889 | if (current_is_kswapd()) { | |
f8891e5e CL |
890 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
891 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
1cfb419b | 892 | } else if (scan_global_lru(sc)) |
f8891e5e | 893 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
1cfb419b | 894 | |
918d3f90 | 895 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa | 896 | |
fb8d14e1 WF |
897 | if (nr_taken == 0) |
898 | goto done; | |
899 | ||
a74609fa | 900 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
901 | /* |
902 | * Put back any unfreeable pages. | |
903 | */ | |
904 | while (!list_empty(&page_list)) { | |
905 | page = lru_to_page(&page_list); | |
725d704e | 906 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 907 | SetPageLRU(page); |
1da177e4 LT |
908 | list_del(&page->lru); |
909 | if (PageActive(page)) | |
910 | add_page_to_active_list(zone, page); | |
911 | else | |
912 | add_page_to_inactive_list(zone, page); | |
913 | if (!pagevec_add(&pvec, page)) { | |
914 | spin_unlock_irq(&zone->lru_lock); | |
915 | __pagevec_release(&pvec); | |
916 | spin_lock_irq(&zone->lru_lock); | |
917 | } | |
918 | } | |
69e05944 | 919 | } while (nr_scanned < max_scan); |
fb8d14e1 | 920 | spin_unlock(&zone->lru_lock); |
1da177e4 | 921 | done: |
fb8d14e1 | 922 | local_irq_enable(); |
1da177e4 | 923 | pagevec_release(&pvec); |
05ff5137 | 924 | return nr_reclaimed; |
1da177e4 LT |
925 | } |
926 | ||
3bb1a852 MB |
927 | /* |
928 | * We are about to scan this zone at a certain priority level. If that priority | |
929 | * level is smaller (ie: more urgent) than the previous priority, then note | |
930 | * that priority level within the zone. This is done so that when the next | |
931 | * process comes in to scan this zone, it will immediately start out at this | |
932 | * priority level rather than having to build up its own scanning priority. | |
933 | * Here, this priority affects only the reclaim-mapped threshold. | |
934 | */ | |
935 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
936 | { | |
937 | if (priority < zone->prev_priority) | |
938 | zone->prev_priority = priority; | |
939 | } | |
940 | ||
4ff1ffb4 NP |
941 | static inline int zone_is_near_oom(struct zone *zone) |
942 | { | |
c8785385 CL |
943 | return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE) |
944 | + zone_page_state(zone, NR_INACTIVE))*3; | |
4ff1ffb4 NP |
945 | } |
946 | ||
1cfb419b KH |
947 | /* |
948 | * Determine we should try to reclaim mapped pages. | |
949 | * This is called only when sc->mem_cgroup is NULL. | |
950 | */ | |
951 | static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone, | |
952 | int priority) | |
953 | { | |
954 | long mapped_ratio; | |
955 | long distress; | |
956 | long swap_tendency; | |
957 | long imbalance; | |
958 | int reclaim_mapped = 0; | |
959 | int prev_priority; | |
960 | ||
961 | if (scan_global_lru(sc) && zone_is_near_oom(zone)) | |
962 | return 1; | |
963 | /* | |
964 | * `distress' is a measure of how much trouble we're having | |
965 | * reclaiming pages. 0 -> no problems. 100 -> great trouble. | |
966 | */ | |
967 | if (scan_global_lru(sc)) | |
968 | prev_priority = zone->prev_priority; | |
969 | else | |
970 | prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup); | |
971 | ||
972 | distress = 100 >> min(prev_priority, priority); | |
973 | ||
974 | /* | |
975 | * The point of this algorithm is to decide when to start | |
976 | * reclaiming mapped memory instead of just pagecache. Work out | |
977 | * how much memory | |
978 | * is mapped. | |
979 | */ | |
980 | if (scan_global_lru(sc)) | |
981 | mapped_ratio = ((global_page_state(NR_FILE_MAPPED) + | |
982 | global_page_state(NR_ANON_PAGES)) * 100) / | |
983 | vm_total_pages; | |
984 | else | |
985 | mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup); | |
986 | ||
987 | /* | |
988 | * Now decide how much we really want to unmap some pages. The | |
989 | * mapped ratio is downgraded - just because there's a lot of | |
990 | * mapped memory doesn't necessarily mean that page reclaim | |
991 | * isn't succeeding. | |
992 | * | |
993 | * The distress ratio is important - we don't want to start | |
994 | * going oom. | |
995 | * | |
996 | * A 100% value of vm_swappiness overrides this algorithm | |
997 | * altogether. | |
998 | */ | |
999 | swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; | |
1000 | ||
1001 | /* | |
1002 | * If there's huge imbalance between active and inactive | |
1003 | * (think active 100 times larger than inactive) we should | |
1004 | * become more permissive, or the system will take too much | |
1005 | * cpu before it start swapping during memory pressure. | |
1006 | * Distress is about avoiding early-oom, this is about | |
1007 | * making swappiness graceful despite setting it to low | |
1008 | * values. | |
1009 | * | |
1010 | * Avoid div by zero with nr_inactive+1, and max resulting | |
1011 | * value is vm_total_pages. | |
1012 | */ | |
1013 | if (scan_global_lru(sc)) { | |
1014 | imbalance = zone_page_state(zone, NR_ACTIVE); | |
1015 | imbalance /= zone_page_state(zone, NR_INACTIVE) + 1; | |
1016 | } else | |
1017 | imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup); | |
1018 | ||
1019 | /* | |
1020 | * Reduce the effect of imbalance if swappiness is low, | |
1021 | * this means for a swappiness very low, the imbalance | |
1022 | * must be much higher than 100 for this logic to make | |
1023 | * the difference. | |
1024 | * | |
1025 | * Max temporary value is vm_total_pages*100. | |
1026 | */ | |
1027 | imbalance *= (vm_swappiness + 1); | |
1028 | imbalance /= 100; | |
1029 | ||
1030 | /* | |
1031 | * If not much of the ram is mapped, makes the imbalance | |
1032 | * less relevant, it's high priority we refill the inactive | |
1033 | * list with mapped pages only in presence of high ratio of | |
1034 | * mapped pages. | |
1035 | * | |
1036 | * Max temporary value is vm_total_pages*100. | |
1037 | */ | |
1038 | imbalance *= mapped_ratio; | |
1039 | imbalance /= 100; | |
1040 | ||
1041 | /* apply imbalance feedback to swap_tendency */ | |
1042 | swap_tendency += imbalance; | |
1043 | ||
1044 | /* | |
1045 | * Now use this metric to decide whether to start moving mapped | |
1046 | * memory onto the inactive list. | |
1047 | */ | |
1048 | if (swap_tendency >= 100) | |
1049 | reclaim_mapped = 1; | |
1050 | ||
1051 | return reclaim_mapped; | |
1052 | } | |
1053 | ||
1da177e4 LT |
1054 | /* |
1055 | * This moves pages from the active list to the inactive list. | |
1056 | * | |
1057 | * We move them the other way if the page is referenced by one or more | |
1058 | * processes, from rmap. | |
1059 | * | |
1060 | * If the pages are mostly unmapped, the processing is fast and it is | |
1061 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1062 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1063 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1064 | * this, so instead we remove the pages from the LRU while processing them. | |
1065 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1066 | * nobody will play with that bit on a non-LRU page. | |
1067 | * | |
1068 | * The downside is that we have to touch page->_count against each page. | |
1069 | * But we had to alter page->flags anyway. | |
1070 | */ | |
1cfb419b KH |
1071 | |
1072 | ||
1742f19f | 1073 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
bbdb396a | 1074 | struct scan_control *sc, int priority) |
1da177e4 | 1075 | { |
69e05944 | 1076 | unsigned long pgmoved; |
1da177e4 | 1077 | int pgdeactivate = 0; |
69e05944 | 1078 | unsigned long pgscanned; |
1da177e4 LT |
1079 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
1080 | LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ | |
1081 | LIST_HEAD(l_active); /* Pages to go onto the active_list */ | |
1082 | struct page *page; | |
1083 | struct pagevec pvec; | |
1084 | int reclaim_mapped = 0; | |
2903fb16 | 1085 | |
1cfb419b KH |
1086 | if (sc->may_swap) |
1087 | reclaim_mapped = calc_reclaim_mapped(sc, zone, priority); | |
1da177e4 LT |
1088 | |
1089 | lru_add_drain(); | |
1090 | spin_lock_irq(&zone->lru_lock); | |
66e1707b BS |
1091 | pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, |
1092 | ISOLATE_ACTIVE, zone, | |
1093 | sc->mem_cgroup, 1); | |
1cfb419b KH |
1094 | /* |
1095 | * zone->pages_scanned is used for detect zone's oom | |
1096 | * mem_cgroup remembers nr_scan by itself. | |
1097 | */ | |
1098 | if (scan_global_lru(sc)) | |
1099 | zone->pages_scanned += pgscanned; | |
1100 | ||
c8785385 | 1101 | __mod_zone_page_state(zone, NR_ACTIVE, -pgmoved); |
1da177e4 LT |
1102 | spin_unlock_irq(&zone->lru_lock); |
1103 | ||
1da177e4 LT |
1104 | while (!list_empty(&l_hold)) { |
1105 | cond_resched(); | |
1106 | page = lru_to_page(&l_hold); | |
1107 | list_del(&page->lru); | |
1108 | if (page_mapped(page)) { | |
1109 | if (!reclaim_mapped || | |
1110 | (total_swap_pages == 0 && PageAnon(page)) || | |
bed7161a | 1111 | page_referenced(page, 0, sc->mem_cgroup)) { |
1da177e4 LT |
1112 | list_add(&page->lru, &l_active); |
1113 | continue; | |
1114 | } | |
1115 | } | |
1116 | list_add(&page->lru, &l_inactive); | |
1117 | } | |
1118 | ||
1119 | pagevec_init(&pvec, 1); | |
1120 | pgmoved = 0; | |
1121 | spin_lock_irq(&zone->lru_lock); | |
1122 | while (!list_empty(&l_inactive)) { | |
1123 | page = lru_to_page(&l_inactive); | |
1124 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 1125 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1126 | SetPageLRU(page); |
725d704e | 1127 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
1128 | ClearPageActive(page); |
1129 | ||
1da177e4 | 1130 | list_move(&page->lru, &zone->inactive_list); |
66e1707b | 1131 | mem_cgroup_move_lists(page_get_page_cgroup(page), false); |
1da177e4 LT |
1132 | pgmoved++; |
1133 | if (!pagevec_add(&pvec, page)) { | |
c8785385 | 1134 | __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); |
1da177e4 LT |
1135 | spin_unlock_irq(&zone->lru_lock); |
1136 | pgdeactivate += pgmoved; | |
1137 | pgmoved = 0; | |
1138 | if (buffer_heads_over_limit) | |
1139 | pagevec_strip(&pvec); | |
1140 | __pagevec_release(&pvec); | |
1141 | spin_lock_irq(&zone->lru_lock); | |
1142 | } | |
1143 | } | |
c8785385 | 1144 | __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); |
1da177e4 LT |
1145 | pgdeactivate += pgmoved; |
1146 | if (buffer_heads_over_limit) { | |
1147 | spin_unlock_irq(&zone->lru_lock); | |
1148 | pagevec_strip(&pvec); | |
1149 | spin_lock_irq(&zone->lru_lock); | |
1150 | } | |
1151 | ||
1152 | pgmoved = 0; | |
1153 | while (!list_empty(&l_active)) { | |
1154 | page = lru_to_page(&l_active); | |
1155 | prefetchw_prev_lru_page(page, &l_active, flags); | |
725d704e | 1156 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1157 | SetPageLRU(page); |
725d704e | 1158 | VM_BUG_ON(!PageActive(page)); |
1da177e4 | 1159 | list_move(&page->lru, &zone->active_list); |
66e1707b | 1160 | mem_cgroup_move_lists(page_get_page_cgroup(page), true); |
1da177e4 LT |
1161 | pgmoved++; |
1162 | if (!pagevec_add(&pvec, page)) { | |
c8785385 | 1163 | __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); |
1da177e4 LT |
1164 | pgmoved = 0; |
1165 | spin_unlock_irq(&zone->lru_lock); | |
1166 | __pagevec_release(&pvec); | |
1167 | spin_lock_irq(&zone->lru_lock); | |
1168 | } | |
1169 | } | |
c8785385 | 1170 | __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); |
a74609fa | 1171 | |
f8891e5e CL |
1172 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1173 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
1174 | spin_unlock_irq(&zone->lru_lock); | |
1da177e4 | 1175 | |
a74609fa | 1176 | pagevec_release(&pvec); |
1da177e4 LT |
1177 | } |
1178 | ||
1179 | /* | |
1180 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1181 | */ | |
05ff5137 AM |
1182 | static unsigned long shrink_zone(int priority, struct zone *zone, |
1183 | struct scan_control *sc) | |
1da177e4 LT |
1184 | { |
1185 | unsigned long nr_active; | |
1186 | unsigned long nr_inactive; | |
8695949a | 1187 | unsigned long nr_to_scan; |
05ff5137 | 1188 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1189 | |
1cfb419b KH |
1190 | if (scan_global_lru(sc)) { |
1191 | /* | |
1192 | * Add one to nr_to_scan just to make sure that the kernel | |
1193 | * will slowly sift through the active list. | |
1194 | */ | |
1195 | zone->nr_scan_active += | |
1196 | (zone_page_state(zone, NR_ACTIVE) >> priority) + 1; | |
1197 | nr_active = zone->nr_scan_active; | |
1198 | zone->nr_scan_inactive += | |
1199 | (zone_page_state(zone, NR_INACTIVE) >> priority) + 1; | |
1200 | nr_inactive = zone->nr_scan_inactive; | |
1201 | if (nr_inactive >= sc->swap_cluster_max) | |
1202 | zone->nr_scan_inactive = 0; | |
1203 | else | |
1204 | nr_inactive = 0; | |
1205 | ||
1206 | if (nr_active >= sc->swap_cluster_max) | |
1207 | zone->nr_scan_active = 0; | |
1208 | else | |
1209 | nr_active = 0; | |
1210 | } else { | |
1211 | /* | |
1212 | * This reclaim occurs not because zone memory shortage but | |
1213 | * because memory controller hits its limit. | |
1214 | * Then, don't modify zone reclaim related data. | |
1215 | */ | |
1216 | nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup, | |
1217 | zone, priority); | |
1218 | ||
1219 | nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup, | |
1220 | zone, priority); | |
1221 | } | |
1da177e4 | 1222 | |
1da177e4 | 1223 | |
1da177e4 LT |
1224 | while (nr_active || nr_inactive) { |
1225 | if (nr_active) { | |
8695949a | 1226 | nr_to_scan = min(nr_active, |
1da177e4 | 1227 | (unsigned long)sc->swap_cluster_max); |
8695949a | 1228 | nr_active -= nr_to_scan; |
bbdb396a | 1229 | shrink_active_list(nr_to_scan, zone, sc, priority); |
1da177e4 LT |
1230 | } |
1231 | ||
1232 | if (nr_inactive) { | |
8695949a | 1233 | nr_to_scan = min(nr_inactive, |
1da177e4 | 1234 | (unsigned long)sc->swap_cluster_max); |
8695949a | 1235 | nr_inactive -= nr_to_scan; |
1742f19f AM |
1236 | nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, |
1237 | sc); | |
1da177e4 LT |
1238 | } |
1239 | } | |
1240 | ||
232ea4d6 | 1241 | throttle_vm_writeout(sc->gfp_mask); |
05ff5137 | 1242 | return nr_reclaimed; |
1da177e4 LT |
1243 | } |
1244 | ||
1245 | /* | |
1246 | * This is the direct reclaim path, for page-allocating processes. We only | |
1247 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1248 | * request. | |
1249 | * | |
1250 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
1251 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
1252 | * allocation or | |
1253 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
1254 | * satisfy the `incremental min' zone defense algorithm. | |
1255 | * | |
1256 | * Returns the number of reclaimed pages. | |
1257 | * | |
1258 | * If a zone is deemed to be full of pinned pages then just give it a light | |
1259 | * scan then give up on it. | |
1260 | */ | |
1742f19f | 1261 | static unsigned long shrink_zones(int priority, struct zone **zones, |
05ff5137 | 1262 | struct scan_control *sc) |
1da177e4 | 1263 | { |
05ff5137 | 1264 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
1265 | int i; |
1266 | ||
1cfb419b | 1267 | |
408d8544 | 1268 | sc->all_unreclaimable = 1; |
1da177e4 LT |
1269 | for (i = 0; zones[i] != NULL; i++) { |
1270 | struct zone *zone = zones[i]; | |
1271 | ||
f3fe6512 | 1272 | if (!populated_zone(zone)) |
1da177e4 | 1273 | continue; |
1cfb419b KH |
1274 | /* |
1275 | * Take care memory controller reclaiming has small influence | |
1276 | * to global LRU. | |
1277 | */ | |
1278 | if (scan_global_lru(sc)) { | |
1279 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1280 | continue; | |
1281 | note_zone_scanning_priority(zone, priority); | |
1da177e4 | 1282 | |
1cfb419b KH |
1283 | if (zone_is_all_unreclaimable(zone) && |
1284 | priority != DEF_PRIORITY) | |
1285 | continue; /* Let kswapd poll it */ | |
1286 | sc->all_unreclaimable = 0; | |
1287 | } else { | |
1288 | /* | |
1289 | * Ignore cpuset limitation here. We just want to reduce | |
1290 | * # of used pages by us regardless of memory shortage. | |
1291 | */ | |
1292 | sc->all_unreclaimable = 0; | |
1293 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, | |
1294 | priority); | |
1295 | } | |
408d8544 | 1296 | |
05ff5137 | 1297 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 1298 | } |
1cfb419b | 1299 | |
05ff5137 | 1300 | return nr_reclaimed; |
1da177e4 LT |
1301 | } |
1302 | ||
1303 | /* | |
1304 | * This is the main entry point to direct page reclaim. | |
1305 | * | |
1306 | * If a full scan of the inactive list fails to free enough memory then we | |
1307 | * are "out of memory" and something needs to be killed. | |
1308 | * | |
1309 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1310 | * high - the zone may be full of dirty or under-writeback pages, which this | |
1311 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
1312 | * hope that some of these pages can be written. But if the allocating task | |
1313 | * holds filesystem locks which prevent writeout this might not work, and the | |
1314 | * allocation attempt will fail. | |
1315 | */ | |
66e1707b BS |
1316 | static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask, |
1317 | struct scan_control *sc) | |
1da177e4 LT |
1318 | { |
1319 | int priority; | |
1320 | int ret = 0; | |
69e05944 | 1321 | unsigned long total_scanned = 0; |
05ff5137 | 1322 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1323 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 LT |
1324 | unsigned long lru_pages = 0; |
1325 | int i; | |
1da177e4 | 1326 | |
1cfb419b KH |
1327 | if (scan_global_lru(sc)) |
1328 | count_vm_event(ALLOCSTALL); | |
1329 | /* | |
1330 | * mem_cgroup will not do shrink_slab. | |
1331 | */ | |
1332 | if (scan_global_lru(sc)) { | |
1333 | for (i = 0; zones[i] != NULL; i++) { | |
1334 | struct zone *zone = zones[i]; | |
1da177e4 | 1335 | |
1cfb419b KH |
1336 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1337 | continue; | |
1da177e4 | 1338 | |
1cfb419b KH |
1339 | lru_pages += zone_page_state(zone, NR_ACTIVE) |
1340 | + zone_page_state(zone, NR_INACTIVE); | |
1341 | } | |
1da177e4 LT |
1342 | } |
1343 | ||
1344 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1345 | sc->nr_scanned = 0; |
f1a9ee75 | 1346 | sc->nr_io_pages = 0; |
f7b7fd8f RR |
1347 | if (!priority) |
1348 | disable_swap_token(); | |
66e1707b BS |
1349 | nr_reclaimed += shrink_zones(priority, zones, sc); |
1350 | /* | |
1351 | * Don't shrink slabs when reclaiming memory from | |
1352 | * over limit cgroups | |
1353 | */ | |
91a45470 | 1354 | if (scan_global_lru(sc)) { |
66e1707b | 1355 | shrink_slab(sc->nr_scanned, gfp_mask, lru_pages); |
91a45470 KH |
1356 | if (reclaim_state) { |
1357 | nr_reclaimed += reclaim_state->reclaimed_slab; | |
1358 | reclaim_state->reclaimed_slab = 0; | |
1359 | } | |
1da177e4 | 1360 | } |
66e1707b BS |
1361 | total_scanned += sc->nr_scanned; |
1362 | if (nr_reclaimed >= sc->swap_cluster_max) { | |
1da177e4 LT |
1363 | ret = 1; |
1364 | goto out; | |
1365 | } | |
1366 | ||
1367 | /* | |
1368 | * Try to write back as many pages as we just scanned. This | |
1369 | * tends to cause slow streaming writers to write data to the | |
1370 | * disk smoothly, at the dirtying rate, which is nice. But | |
1371 | * that's undesirable in laptop mode, where we *want* lumpy | |
1372 | * writeout. So in laptop mode, write out the whole world. | |
1373 | */ | |
66e1707b BS |
1374 | if (total_scanned > sc->swap_cluster_max + |
1375 | sc->swap_cluster_max / 2) { | |
687a21ce | 1376 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
66e1707b | 1377 | sc->may_writepage = 1; |
1da177e4 LT |
1378 | } |
1379 | ||
1380 | /* Take a nap, wait for some writeback to complete */ | |
f1a9ee75 RR |
1381 | if (sc->nr_scanned && priority < DEF_PRIORITY - 2 && |
1382 | sc->nr_io_pages > sc->swap_cluster_max) | |
3fcfab16 | 1383 | congestion_wait(WRITE, HZ/10); |
1da177e4 | 1384 | } |
408d8544 | 1385 | /* top priority shrink_caches still had more to do? don't OOM, then */ |
91a45470 | 1386 | if (!sc->all_unreclaimable && scan_global_lru(sc)) |
408d8544 | 1387 | ret = 1; |
1da177e4 | 1388 | out: |
3bb1a852 MB |
1389 | /* |
1390 | * Now that we've scanned all the zones at this priority level, note | |
1391 | * that level within the zone so that the next thread which performs | |
1392 | * scanning of this zone will immediately start out at this priority | |
1393 | * level. This affects only the decision whether or not to bring | |
1394 | * mapped pages onto the inactive list. | |
1395 | */ | |
1396 | if (priority < 0) | |
1397 | priority = 0; | |
1da177e4 | 1398 | |
1cfb419b KH |
1399 | if (scan_global_lru(sc)) { |
1400 | for (i = 0; zones[i] != NULL; i++) { | |
1401 | struct zone *zone = zones[i]; | |
1402 | ||
1403 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1404 | continue; | |
1405 | ||
1406 | zone->prev_priority = priority; | |
1407 | } | |
1408 | } else | |
1409 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); | |
1da177e4 | 1410 | |
1da177e4 LT |
1411 | return ret; |
1412 | } | |
1413 | ||
66e1707b BS |
1414 | unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask) |
1415 | { | |
1416 | struct scan_control sc = { | |
1417 | .gfp_mask = gfp_mask, | |
1418 | .may_writepage = !laptop_mode, | |
1419 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1420 | .may_swap = 1, | |
1421 | .swappiness = vm_swappiness, | |
1422 | .order = order, | |
1423 | .mem_cgroup = NULL, | |
1424 | .isolate_pages = isolate_pages_global, | |
1425 | }; | |
1426 | ||
1427 | return do_try_to_free_pages(zones, gfp_mask, &sc); | |
1428 | } | |
1429 | ||
1430 | #ifdef CONFIG_CGROUP_MEM_CONT | |
1431 | ||
e1a1cd59 BS |
1432 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
1433 | gfp_t gfp_mask) | |
66e1707b BS |
1434 | { |
1435 | struct scan_control sc = { | |
e1a1cd59 | 1436 | .gfp_mask = gfp_mask, |
66e1707b BS |
1437 | .may_writepage = !laptop_mode, |
1438 | .may_swap = 1, | |
1439 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1440 | .swappiness = vm_swappiness, | |
1441 | .order = 0, | |
1442 | .mem_cgroup = mem_cont, | |
1443 | .isolate_pages = mem_cgroup_isolate_pages, | |
1444 | }; | |
66e1707b | 1445 | struct zone **zones; |
e1a1cd59 | 1446 | int target_zone = gfp_zone(GFP_HIGHUSER_MOVABLE); |
66e1707b | 1447 | |
417eead3 KH |
1448 | zones = NODE_DATA(numa_node_id())->node_zonelists[target_zone].zones; |
1449 | if (do_try_to_free_pages(zones, sc.gfp_mask, &sc)) | |
1450 | return 1; | |
66e1707b BS |
1451 | return 0; |
1452 | } | |
1453 | #endif | |
1454 | ||
1da177e4 LT |
1455 | /* |
1456 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1457 | * they are all at pages_high. | |
1458 | * | |
1da177e4 LT |
1459 | * Returns the number of pages which were actually freed. |
1460 | * | |
1461 | * There is special handling here for zones which are full of pinned pages. | |
1462 | * This can happen if the pages are all mlocked, or if they are all used by | |
1463 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1464 | * What we do is to detect the case where all pages in the zone have been | |
1465 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1466 | * dead and from now on, only perform a short scan. Basically we're polling | |
1467 | * the zone for when the problem goes away. | |
1468 | * | |
1469 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1470 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1471 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1472 | * of the number of free pages in the lower zones. This interoperates with | |
1473 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1474 | * across the zones. | |
1475 | */ | |
d6277db4 | 1476 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1477 | { |
1da177e4 LT |
1478 | int all_zones_ok; |
1479 | int priority; | |
1480 | int i; | |
69e05944 | 1481 | unsigned long total_scanned; |
05ff5137 | 1482 | unsigned long nr_reclaimed; |
1da177e4 | 1483 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1484 | struct scan_control sc = { |
1485 | .gfp_mask = GFP_KERNEL, | |
1486 | .may_swap = 1, | |
d6277db4 RW |
1487 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1488 | .swappiness = vm_swappiness, | |
5ad333eb | 1489 | .order = order, |
66e1707b BS |
1490 | .mem_cgroup = NULL, |
1491 | .isolate_pages = isolate_pages_global, | |
179e9639 | 1492 | }; |
3bb1a852 MB |
1493 | /* |
1494 | * temp_priority is used to remember the scanning priority at which | |
1495 | * this zone was successfully refilled to free_pages == pages_high. | |
1496 | */ | |
1497 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
1498 | |
1499 | loop_again: | |
1500 | total_scanned = 0; | |
05ff5137 | 1501 | nr_reclaimed = 0; |
c0bbbc73 | 1502 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1503 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 1504 | |
3bb1a852 MB |
1505 | for (i = 0; i < pgdat->nr_zones; i++) |
1506 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
1507 | |
1508 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1509 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1510 | unsigned long lru_pages = 0; | |
1511 | ||
f7b7fd8f RR |
1512 | /* The swap token gets in the way of swapout... */ |
1513 | if (!priority) | |
1514 | disable_swap_token(); | |
1515 | ||
f1a9ee75 | 1516 | sc.nr_io_pages = 0; |
1da177e4 LT |
1517 | all_zones_ok = 1; |
1518 | ||
d6277db4 RW |
1519 | /* |
1520 | * Scan in the highmem->dma direction for the highest | |
1521 | * zone which needs scanning | |
1522 | */ | |
1523 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1524 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1525 | |
d6277db4 RW |
1526 | if (!populated_zone(zone)) |
1527 | continue; | |
1da177e4 | 1528 | |
e815af95 DR |
1529 | if (zone_is_all_unreclaimable(zone) && |
1530 | priority != DEF_PRIORITY) | |
d6277db4 | 1531 | continue; |
1da177e4 | 1532 | |
d6277db4 RW |
1533 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1534 | 0, 0)) { | |
1535 | end_zone = i; | |
e1dbeda6 | 1536 | break; |
1da177e4 | 1537 | } |
1da177e4 | 1538 | } |
e1dbeda6 AM |
1539 | if (i < 0) |
1540 | goto out; | |
1541 | ||
1da177e4 LT |
1542 | for (i = 0; i <= end_zone; i++) { |
1543 | struct zone *zone = pgdat->node_zones + i; | |
1544 | ||
c8785385 CL |
1545 | lru_pages += zone_page_state(zone, NR_ACTIVE) |
1546 | + zone_page_state(zone, NR_INACTIVE); | |
1da177e4 LT |
1547 | } |
1548 | ||
1549 | /* | |
1550 | * Now scan the zone in the dma->highmem direction, stopping | |
1551 | * at the last zone which needs scanning. | |
1552 | * | |
1553 | * We do this because the page allocator works in the opposite | |
1554 | * direction. This prevents the page allocator from allocating | |
1555 | * pages behind kswapd's direction of progress, which would | |
1556 | * cause too much scanning of the lower zones. | |
1557 | */ | |
1558 | for (i = 0; i <= end_zone; i++) { | |
1559 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1560 | int nr_slab; |
1da177e4 | 1561 | |
f3fe6512 | 1562 | if (!populated_zone(zone)) |
1da177e4 LT |
1563 | continue; |
1564 | ||
e815af95 DR |
1565 | if (zone_is_all_unreclaimable(zone) && |
1566 | priority != DEF_PRIORITY) | |
1da177e4 LT |
1567 | continue; |
1568 | ||
d6277db4 RW |
1569 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1570 | end_zone, 0)) | |
1571 | all_zones_ok = 0; | |
3bb1a852 | 1572 | temp_priority[i] = priority; |
1da177e4 | 1573 | sc.nr_scanned = 0; |
3bb1a852 | 1574 | note_zone_scanning_priority(zone, priority); |
32a4330d RR |
1575 | /* |
1576 | * We put equal pressure on every zone, unless one | |
1577 | * zone has way too many pages free already. | |
1578 | */ | |
1579 | if (!zone_watermark_ok(zone, order, 8*zone->pages_high, | |
1580 | end_zone, 0)) | |
1581 | nr_reclaimed += shrink_zone(priority, zone, &sc); | |
1da177e4 | 1582 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1583 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1584 | lru_pages); | |
05ff5137 | 1585 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 1586 | total_scanned += sc.nr_scanned; |
e815af95 | 1587 | if (zone_is_all_unreclaimable(zone)) |
1da177e4 | 1588 | continue; |
b15e0905 | 1589 | if (nr_slab == 0 && zone->pages_scanned >= |
c8785385 CL |
1590 | (zone_page_state(zone, NR_ACTIVE) |
1591 | + zone_page_state(zone, NR_INACTIVE)) * 6) | |
e815af95 DR |
1592 | zone_set_flag(zone, |
1593 | ZONE_ALL_UNRECLAIMABLE); | |
1da177e4 LT |
1594 | /* |
1595 | * If we've done a decent amount of scanning and | |
1596 | * the reclaim ratio is low, start doing writepage | |
1597 | * even in laptop mode | |
1598 | */ | |
1599 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1600 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1601 | sc.may_writepage = 1; |
1602 | } | |
1da177e4 LT |
1603 | if (all_zones_ok) |
1604 | break; /* kswapd: all done */ | |
1605 | /* | |
1606 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1607 | * another pass across the zones. | |
1608 | */ | |
f1a9ee75 RR |
1609 | if (total_scanned && priority < DEF_PRIORITY - 2 && |
1610 | sc.nr_io_pages > sc.swap_cluster_max) | |
3fcfab16 | 1611 | congestion_wait(WRITE, HZ/10); |
1da177e4 LT |
1612 | |
1613 | /* | |
1614 | * We do this so kswapd doesn't build up large priorities for | |
1615 | * example when it is freeing in parallel with allocators. It | |
1616 | * matches the direct reclaim path behaviour in terms of impact | |
1617 | * on zone->*_priority. | |
1618 | */ | |
d6277db4 | 1619 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1620 | break; |
1621 | } | |
1622 | out: | |
3bb1a852 MB |
1623 | /* |
1624 | * Note within each zone the priority level at which this zone was | |
1625 | * brought into a happy state. So that the next thread which scans this | |
1626 | * zone will start out at that priority level. | |
1627 | */ | |
1da177e4 LT |
1628 | for (i = 0; i < pgdat->nr_zones; i++) { |
1629 | struct zone *zone = pgdat->node_zones + i; | |
1630 | ||
3bb1a852 | 1631 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
1632 | } |
1633 | if (!all_zones_ok) { | |
1634 | cond_resched(); | |
8357376d RW |
1635 | |
1636 | try_to_freeze(); | |
1637 | ||
1da177e4 LT |
1638 | goto loop_again; |
1639 | } | |
1640 | ||
05ff5137 | 1641 | return nr_reclaimed; |
1da177e4 LT |
1642 | } |
1643 | ||
1644 | /* | |
1645 | * The background pageout daemon, started as a kernel thread | |
1646 | * from the init process. | |
1647 | * | |
1648 | * This basically trickles out pages so that we have _some_ | |
1649 | * free memory available even if there is no other activity | |
1650 | * that frees anything up. This is needed for things like routing | |
1651 | * etc, where we otherwise might have all activity going on in | |
1652 | * asynchronous contexts that cannot page things out. | |
1653 | * | |
1654 | * If there are applications that are active memory-allocators | |
1655 | * (most normal use), this basically shouldn't matter. | |
1656 | */ | |
1657 | static int kswapd(void *p) | |
1658 | { | |
1659 | unsigned long order; | |
1660 | pg_data_t *pgdat = (pg_data_t*)p; | |
1661 | struct task_struct *tsk = current; | |
1662 | DEFINE_WAIT(wait); | |
1663 | struct reclaim_state reclaim_state = { | |
1664 | .reclaimed_slab = 0, | |
1665 | }; | |
1666 | cpumask_t cpumask; | |
1667 | ||
1da177e4 LT |
1668 | cpumask = node_to_cpumask(pgdat->node_id); |
1669 | if (!cpus_empty(cpumask)) | |
1670 | set_cpus_allowed(tsk, cpumask); | |
1671 | current->reclaim_state = &reclaim_state; | |
1672 | ||
1673 | /* | |
1674 | * Tell the memory management that we're a "memory allocator", | |
1675 | * and that if we need more memory we should get access to it | |
1676 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1677 | * never get caught in the normal page freeing logic. | |
1678 | * | |
1679 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1680 | * you need a small amount of memory in order to be able to | |
1681 | * page out something else, and this flag essentially protects | |
1682 | * us from recursively trying to free more memory as we're | |
1683 | * trying to free the first piece of memory in the first place). | |
1684 | */ | |
930d9152 | 1685 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 1686 | set_freezable(); |
1da177e4 LT |
1687 | |
1688 | order = 0; | |
1689 | for ( ; ; ) { | |
1690 | unsigned long new_order; | |
3e1d1d28 | 1691 | |
1da177e4 LT |
1692 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
1693 | new_order = pgdat->kswapd_max_order; | |
1694 | pgdat->kswapd_max_order = 0; | |
1695 | if (order < new_order) { | |
1696 | /* | |
1697 | * Don't sleep if someone wants a larger 'order' | |
1698 | * allocation | |
1699 | */ | |
1700 | order = new_order; | |
1701 | } else { | |
b1296cc4 RW |
1702 | if (!freezing(current)) |
1703 | schedule(); | |
1704 | ||
1da177e4 LT |
1705 | order = pgdat->kswapd_max_order; |
1706 | } | |
1707 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1708 | ||
b1296cc4 RW |
1709 | if (!try_to_freeze()) { |
1710 | /* We can speed up thawing tasks if we don't call | |
1711 | * balance_pgdat after returning from the refrigerator | |
1712 | */ | |
1713 | balance_pgdat(pgdat, order); | |
1714 | } | |
1da177e4 LT |
1715 | } |
1716 | return 0; | |
1717 | } | |
1718 | ||
1719 | /* | |
1720 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1721 | */ | |
1722 | void wakeup_kswapd(struct zone *zone, int order) | |
1723 | { | |
1724 | pg_data_t *pgdat; | |
1725 | ||
f3fe6512 | 1726 | if (!populated_zone(zone)) |
1da177e4 LT |
1727 | return; |
1728 | ||
1729 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1730 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1731 | return; |
1732 | if (pgdat->kswapd_max_order < order) | |
1733 | pgdat->kswapd_max_order = order; | |
02a0e53d | 1734 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 1735 | return; |
8d0986e2 | 1736 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1737 | return; |
8d0986e2 | 1738 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1739 | } |
1740 | ||
1741 | #ifdef CONFIG_PM | |
1742 | /* | |
d6277db4 RW |
1743 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1744 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1745 | * number of reclaimed pages | |
1746 | * | |
1747 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1748 | */ | |
e07aa05b NC |
1749 | static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, |
1750 | int pass, struct scan_control *sc) | |
d6277db4 RW |
1751 | { |
1752 | struct zone *zone; | |
1753 | unsigned long nr_to_scan, ret = 0; | |
1754 | ||
1755 | for_each_zone(zone) { | |
1756 | ||
1757 | if (!populated_zone(zone)) | |
1758 | continue; | |
1759 | ||
e815af95 | 1760 | if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) |
d6277db4 RW |
1761 | continue; |
1762 | ||
1763 | /* For pass = 0 we don't shrink the active list */ | |
1764 | if (pass > 0) { | |
c8785385 CL |
1765 | zone->nr_scan_active += |
1766 | (zone_page_state(zone, NR_ACTIVE) >> prio) + 1; | |
d6277db4 RW |
1767 | if (zone->nr_scan_active >= nr_pages || pass > 3) { |
1768 | zone->nr_scan_active = 0; | |
c8785385 CL |
1769 | nr_to_scan = min(nr_pages, |
1770 | zone_page_state(zone, NR_ACTIVE)); | |
bbdb396a | 1771 | shrink_active_list(nr_to_scan, zone, sc, prio); |
d6277db4 RW |
1772 | } |
1773 | } | |
1774 | ||
c8785385 CL |
1775 | zone->nr_scan_inactive += |
1776 | (zone_page_state(zone, NR_INACTIVE) >> prio) + 1; | |
d6277db4 RW |
1777 | if (zone->nr_scan_inactive >= nr_pages || pass > 3) { |
1778 | zone->nr_scan_inactive = 0; | |
c8785385 CL |
1779 | nr_to_scan = min(nr_pages, |
1780 | zone_page_state(zone, NR_INACTIVE)); | |
d6277db4 RW |
1781 | ret += shrink_inactive_list(nr_to_scan, zone, sc); |
1782 | if (ret >= nr_pages) | |
1783 | return ret; | |
1784 | } | |
1785 | } | |
1786 | ||
1787 | return ret; | |
1788 | } | |
1789 | ||
76395d37 AM |
1790 | static unsigned long count_lru_pages(void) |
1791 | { | |
c8785385 | 1792 | return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE); |
76395d37 AM |
1793 | } |
1794 | ||
d6277db4 RW |
1795 | /* |
1796 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
1797 | * freed pages. | |
1798 | * | |
1799 | * Rather than trying to age LRUs the aim is to preserve the overall | |
1800 | * LRU order by reclaiming preferentially | |
1801 | * inactive > active > active referenced > active mapped | |
1da177e4 | 1802 | */ |
69e05944 | 1803 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 1804 | { |
d6277db4 | 1805 | unsigned long lru_pages, nr_slab; |
69e05944 | 1806 | unsigned long ret = 0; |
d6277db4 RW |
1807 | int pass; |
1808 | struct reclaim_state reclaim_state; | |
d6277db4 RW |
1809 | struct scan_control sc = { |
1810 | .gfp_mask = GFP_KERNEL, | |
1811 | .may_swap = 0, | |
1812 | .swap_cluster_max = nr_pages, | |
1813 | .may_writepage = 1, | |
1814 | .swappiness = vm_swappiness, | |
66e1707b | 1815 | .isolate_pages = isolate_pages_global, |
1da177e4 LT |
1816 | }; |
1817 | ||
1818 | current->reclaim_state = &reclaim_state; | |
69e05944 | 1819 | |
76395d37 | 1820 | lru_pages = count_lru_pages(); |
972d1a7b | 1821 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
1822 | /* If slab caches are huge, it's better to hit them first */ |
1823 | while (nr_slab >= lru_pages) { | |
1824 | reclaim_state.reclaimed_slab = 0; | |
1825 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1826 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 1827 | break; |
d6277db4 RW |
1828 | |
1829 | ret += reclaim_state.reclaimed_slab; | |
1830 | if (ret >= nr_pages) | |
1831 | goto out; | |
1832 | ||
1833 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 1834 | } |
d6277db4 RW |
1835 | |
1836 | /* | |
1837 | * We try to shrink LRUs in 5 passes: | |
1838 | * 0 = Reclaim from inactive_list only | |
1839 | * 1 = Reclaim from active list but don't reclaim mapped | |
1840 | * 2 = 2nd pass of type 1 | |
1841 | * 3 = Reclaim mapped (normal reclaim) | |
1842 | * 4 = 2nd pass of type 3 | |
1843 | */ | |
1844 | for (pass = 0; pass < 5; pass++) { | |
1845 | int prio; | |
1846 | ||
d6277db4 RW |
1847 | /* Force reclaiming mapped pages in the passes #3 and #4 */ |
1848 | if (pass > 2) { | |
1849 | sc.may_swap = 1; | |
1850 | sc.swappiness = 100; | |
1851 | } | |
1852 | ||
1853 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
1854 | unsigned long nr_to_scan = nr_pages - ret; | |
1855 | ||
d6277db4 | 1856 | sc.nr_scanned = 0; |
d6277db4 RW |
1857 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
1858 | if (ret >= nr_pages) | |
1859 | goto out; | |
1860 | ||
1861 | reclaim_state.reclaimed_slab = 0; | |
76395d37 AM |
1862 | shrink_slab(sc.nr_scanned, sc.gfp_mask, |
1863 | count_lru_pages()); | |
d6277db4 RW |
1864 | ret += reclaim_state.reclaimed_slab; |
1865 | if (ret >= nr_pages) | |
1866 | goto out; | |
1867 | ||
1868 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
3fcfab16 | 1869 | congestion_wait(WRITE, HZ / 10); |
d6277db4 | 1870 | } |
248a0301 | 1871 | } |
d6277db4 RW |
1872 | |
1873 | /* | |
1874 | * If ret = 0, we could not shrink LRUs, but there may be something | |
1875 | * in slab caches | |
1876 | */ | |
76395d37 | 1877 | if (!ret) { |
d6277db4 RW |
1878 | do { |
1879 | reclaim_state.reclaimed_slab = 0; | |
76395d37 | 1880 | shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages()); |
d6277db4 RW |
1881 | ret += reclaim_state.reclaimed_slab; |
1882 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
76395d37 | 1883 | } |
d6277db4 RW |
1884 | |
1885 | out: | |
1da177e4 | 1886 | current->reclaim_state = NULL; |
d6277db4 | 1887 | |
1da177e4 LT |
1888 | return ret; |
1889 | } | |
1890 | #endif | |
1891 | ||
1da177e4 LT |
1892 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
1893 | not required for correctness. So if the last cpu in a node goes | |
1894 | away, we get changed to run anywhere: as the first one comes back, | |
1895 | restore their cpu bindings. */ | |
9c7b216d | 1896 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 1897 | unsigned long action, void *hcpu) |
1da177e4 LT |
1898 | { |
1899 | pg_data_t *pgdat; | |
1900 | cpumask_t mask; | |
58c0a4a7 | 1901 | int nid; |
1da177e4 | 1902 | |
8bb78442 | 1903 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 YG |
1904 | for_each_node_state(nid, N_HIGH_MEMORY) { |
1905 | pgdat = NODE_DATA(nid); | |
1da177e4 LT |
1906 | mask = node_to_cpumask(pgdat->node_id); |
1907 | if (any_online_cpu(mask) != NR_CPUS) | |
1908 | /* One of our CPUs online: restore mask */ | |
1909 | set_cpus_allowed(pgdat->kswapd, mask); | |
1910 | } | |
1911 | } | |
1912 | return NOTIFY_OK; | |
1913 | } | |
1da177e4 | 1914 | |
3218ae14 YG |
1915 | /* |
1916 | * This kswapd start function will be called by init and node-hot-add. | |
1917 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
1918 | */ | |
1919 | int kswapd_run(int nid) | |
1920 | { | |
1921 | pg_data_t *pgdat = NODE_DATA(nid); | |
1922 | int ret = 0; | |
1923 | ||
1924 | if (pgdat->kswapd) | |
1925 | return 0; | |
1926 | ||
1927 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
1928 | if (IS_ERR(pgdat->kswapd)) { | |
1929 | /* failure at boot is fatal */ | |
1930 | BUG_ON(system_state == SYSTEM_BOOTING); | |
1931 | printk("Failed to start kswapd on node %d\n",nid); | |
1932 | ret = -1; | |
1933 | } | |
1934 | return ret; | |
1935 | } | |
1936 | ||
1da177e4 LT |
1937 | static int __init kswapd_init(void) |
1938 | { | |
3218ae14 | 1939 | int nid; |
69e05944 | 1940 | |
1da177e4 | 1941 | swap_setup(); |
9422ffba | 1942 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 1943 | kswapd_run(nid); |
1da177e4 LT |
1944 | hotcpu_notifier(cpu_callback, 0); |
1945 | return 0; | |
1946 | } | |
1947 | ||
1948 | module_init(kswapd_init) | |
9eeff239 CL |
1949 | |
1950 | #ifdef CONFIG_NUMA | |
1951 | /* | |
1952 | * Zone reclaim mode | |
1953 | * | |
1954 | * If non-zero call zone_reclaim when the number of free pages falls below | |
1955 | * the watermarks. | |
9eeff239 CL |
1956 | */ |
1957 | int zone_reclaim_mode __read_mostly; | |
1958 | ||
1b2ffb78 CL |
1959 | #define RECLAIM_OFF 0 |
1960 | #define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */ | |
1961 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ | |
1962 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
1963 | ||
a92f7126 CL |
1964 | /* |
1965 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
1966 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
1967 | * a zone. | |
1968 | */ | |
1969 | #define ZONE_RECLAIM_PRIORITY 4 | |
1970 | ||
9614634f CL |
1971 | /* |
1972 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
1973 | * occur. | |
1974 | */ | |
1975 | int sysctl_min_unmapped_ratio = 1; | |
1976 | ||
0ff38490 CL |
1977 | /* |
1978 | * If the number of slab pages in a zone grows beyond this percentage then | |
1979 | * slab reclaim needs to occur. | |
1980 | */ | |
1981 | int sysctl_min_slab_ratio = 5; | |
1982 | ||
9eeff239 CL |
1983 | /* |
1984 | * Try to free up some pages from this zone through reclaim. | |
1985 | */ | |
179e9639 | 1986 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 1987 | { |
7fb2d46d | 1988 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 1989 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
1990 | struct task_struct *p = current; |
1991 | struct reclaim_state reclaim_state; | |
8695949a | 1992 | int priority; |
05ff5137 | 1993 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
1994 | struct scan_control sc = { |
1995 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
1996 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
1997 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
1998 | SWAP_CLUSTER_MAX), | |
179e9639 | 1999 | .gfp_mask = gfp_mask, |
d6277db4 | 2000 | .swappiness = vm_swappiness, |
66e1707b | 2001 | .isolate_pages = isolate_pages_global, |
179e9639 | 2002 | }; |
83e33a47 | 2003 | unsigned long slab_reclaimable; |
9eeff239 CL |
2004 | |
2005 | disable_swap_token(); | |
9eeff239 | 2006 | cond_resched(); |
d4f7796e CL |
2007 | /* |
2008 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2009 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2010 | * and RECLAIM_SWAP. | |
2011 | */ | |
2012 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
2013 | reclaim_state.reclaimed_slab = 0; |
2014 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2015 | |
0ff38490 CL |
2016 | if (zone_page_state(zone, NR_FILE_PAGES) - |
2017 | zone_page_state(zone, NR_FILE_MAPPED) > | |
2018 | zone->min_unmapped_pages) { | |
2019 | /* | |
2020 | * Free memory by calling shrink zone with increasing | |
2021 | * priorities until we have enough memory freed. | |
2022 | */ | |
2023 | priority = ZONE_RECLAIM_PRIORITY; | |
2024 | do { | |
3bb1a852 | 2025 | note_zone_scanning_priority(zone, priority); |
0ff38490 CL |
2026 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
2027 | priority--; | |
2028 | } while (priority >= 0 && nr_reclaimed < nr_pages); | |
2029 | } | |
c84db23c | 2030 | |
83e33a47 CL |
2031 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2032 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2033 | /* |
7fb2d46d | 2034 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2035 | * many pages were freed in this zone. So we take the current |
2036 | * number of slab pages and shake the slab until it is reduced | |
2037 | * by the same nr_pages that we used for reclaiming unmapped | |
2038 | * pages. | |
2a16e3f4 | 2039 | * |
0ff38490 CL |
2040 | * Note that shrink_slab will free memory on all zones and may |
2041 | * take a long time. | |
2a16e3f4 | 2042 | */ |
0ff38490 | 2043 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2044 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2045 | slab_reclaimable - nr_pages) | |
0ff38490 | 2046 | ; |
83e33a47 CL |
2047 | |
2048 | /* | |
2049 | * Update nr_reclaimed by the number of slab pages we | |
2050 | * reclaimed from this zone. | |
2051 | */ | |
2052 | nr_reclaimed += slab_reclaimable - | |
2053 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); | |
2a16e3f4 CL |
2054 | } |
2055 | ||
9eeff239 | 2056 | p->reclaim_state = NULL; |
d4f7796e | 2057 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
05ff5137 | 2058 | return nr_reclaimed >= nr_pages; |
9eeff239 | 2059 | } |
179e9639 AM |
2060 | |
2061 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2062 | { | |
179e9639 | 2063 | int node_id; |
d773ed6b | 2064 | int ret; |
179e9639 AM |
2065 | |
2066 | /* | |
0ff38490 CL |
2067 | * Zone reclaim reclaims unmapped file backed pages and |
2068 | * slab pages if we are over the defined limits. | |
34aa1330 | 2069 | * |
9614634f CL |
2070 | * A small portion of unmapped file backed pages is needed for |
2071 | * file I/O otherwise pages read by file I/O will be immediately | |
2072 | * thrown out if the zone is overallocated. So we do not reclaim | |
2073 | * if less than a specified percentage of the zone is used by | |
2074 | * unmapped file backed pages. | |
179e9639 | 2075 | */ |
34aa1330 | 2076 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
2077 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
2078 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
2079 | <= zone->min_slab_pages) | |
9614634f | 2080 | return 0; |
179e9639 | 2081 | |
d773ed6b DR |
2082 | if (zone_is_all_unreclaimable(zone)) |
2083 | return 0; | |
2084 | ||
179e9639 | 2085 | /* |
d773ed6b | 2086 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2087 | */ |
d773ed6b | 2088 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
179e9639 AM |
2089 | return 0; |
2090 | ||
2091 | /* | |
2092 | * Only run zone reclaim on the local zone or on zones that do not | |
2093 | * have associated processors. This will favor the local processor | |
2094 | * over remote processors and spread off node memory allocations | |
2095 | * as wide as possible. | |
2096 | */ | |
89fa3024 | 2097 | node_id = zone_to_nid(zone); |
37c0708d | 2098 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
179e9639 | 2099 | return 0; |
d773ed6b DR |
2100 | |
2101 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
2102 | return 0; | |
2103 | ret = __zone_reclaim(zone, gfp_mask, order); | |
2104 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2105 | ||
2106 | return ret; | |
179e9639 | 2107 | } |
9eeff239 | 2108 | #endif |