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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> |
1da177e4 LT |
40 | |
41 | #include <asm/tlbflush.h> | |
42 | #include <asm/div64.h> | |
43 | ||
44 | #include <linux/swapops.h> | |
45 | ||
0f8053a5 NP |
46 | #include "internal.h" |
47 | ||
1da177e4 | 48 | struct scan_control { |
1da177e4 LT |
49 | /* Incremented by the number of inactive pages that were scanned */ |
50 | unsigned long nr_scanned; | |
51 | ||
1da177e4 | 52 | /* This context's GFP mask */ |
6daa0e28 | 53 | gfp_t gfp_mask; |
1da177e4 LT |
54 | |
55 | int may_writepage; | |
56 | ||
f1fd1067 CL |
57 | /* Can pages be swapped as part of reclaim? */ |
58 | int may_swap; | |
59 | ||
1da177e4 LT |
60 | /* This context's SWAP_CLUSTER_MAX. If freeing memory for |
61 | * suspend, we effectively ignore SWAP_CLUSTER_MAX. | |
62 | * In this context, it doesn't matter that we scan the | |
63 | * whole list at once. */ | |
64 | int swap_cluster_max; | |
d6277db4 RW |
65 | |
66 | int swappiness; | |
408d8544 NP |
67 | |
68 | int all_unreclaimable; | |
5ad333eb AW |
69 | |
70 | int order; | |
1da177e4 LT |
71 | }; |
72 | ||
1da177e4 LT |
73 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
74 | ||
75 | #ifdef ARCH_HAS_PREFETCH | |
76 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
77 | do { \ | |
78 | if ((_page)->lru.prev != _base) { \ | |
79 | struct page *prev; \ | |
80 | \ | |
81 | prev = lru_to_page(&(_page->lru)); \ | |
82 | prefetch(&prev->_field); \ | |
83 | } \ | |
84 | } while (0) | |
85 | #else | |
86 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
87 | #endif | |
88 | ||
89 | #ifdef ARCH_HAS_PREFETCHW | |
90 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
91 | do { \ | |
92 | if ((_page)->lru.prev != _base) { \ | |
93 | struct page *prev; \ | |
94 | \ | |
95 | prev = lru_to_page(&(_page->lru)); \ | |
96 | prefetchw(&prev->_field); \ | |
97 | } \ | |
98 | } while (0) | |
99 | #else | |
100 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
101 | #endif | |
102 | ||
103 | /* | |
104 | * From 0 .. 100. Higher means more swappy. | |
105 | */ | |
106 | int vm_swappiness = 60; | |
bd1e22b8 | 107 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
108 | |
109 | static LIST_HEAD(shrinker_list); | |
110 | static DECLARE_RWSEM(shrinker_rwsem); | |
111 | ||
112 | /* | |
113 | * Add a shrinker callback to be called from the vm | |
114 | */ | |
8e1f936b | 115 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 116 | { |
8e1f936b RR |
117 | shrinker->nr = 0; |
118 | down_write(&shrinker_rwsem); | |
119 | list_add_tail(&shrinker->list, &shrinker_list); | |
120 | up_write(&shrinker_rwsem); | |
1da177e4 | 121 | } |
8e1f936b | 122 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
123 | |
124 | /* | |
125 | * Remove one | |
126 | */ | |
8e1f936b | 127 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
128 | { |
129 | down_write(&shrinker_rwsem); | |
130 | list_del(&shrinker->list); | |
131 | up_write(&shrinker_rwsem); | |
1da177e4 | 132 | } |
8e1f936b | 133 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
134 | |
135 | #define SHRINK_BATCH 128 | |
136 | /* | |
137 | * Call the shrink functions to age shrinkable caches | |
138 | * | |
139 | * Here we assume it costs one seek to replace a lru page and that it also | |
140 | * takes a seek to recreate a cache object. With this in mind we age equal | |
141 | * percentages of the lru and ageable caches. This should balance the seeks | |
142 | * generated by these structures. | |
143 | * | |
144 | * If the vm encounted mapped pages on the LRU it increase the pressure on | |
145 | * slab to avoid swapping. | |
146 | * | |
147 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
148 | * | |
149 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
150 | * are eligible for the caller's allocation attempt. It is used for balancing | |
151 | * slab reclaim versus page reclaim. | |
b15e0905 | 152 | * |
153 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 154 | */ |
69e05944 AM |
155 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
156 | unsigned long lru_pages) | |
1da177e4 LT |
157 | { |
158 | struct shrinker *shrinker; | |
69e05944 | 159 | unsigned long ret = 0; |
1da177e4 LT |
160 | |
161 | if (scanned == 0) | |
162 | scanned = SWAP_CLUSTER_MAX; | |
163 | ||
164 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 165 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
166 | |
167 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
168 | unsigned long long delta; | |
169 | unsigned long total_scan; | |
8e1f936b | 170 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
1da177e4 LT |
171 | |
172 | delta = (4 * scanned) / shrinker->seeks; | |
ea164d73 | 173 | delta *= max_pass; |
1da177e4 LT |
174 | do_div(delta, lru_pages + 1); |
175 | shrinker->nr += delta; | |
ea164d73 AA |
176 | if (shrinker->nr < 0) { |
177 | printk(KERN_ERR "%s: nr=%ld\n", | |
178 | __FUNCTION__, shrinker->nr); | |
179 | shrinker->nr = max_pass; | |
180 | } | |
181 | ||
182 | /* | |
183 | * Avoid risking looping forever due to too large nr value: | |
184 | * never try to free more than twice the estimate number of | |
185 | * freeable entries. | |
186 | */ | |
187 | if (shrinker->nr > max_pass * 2) | |
188 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
189 | |
190 | total_scan = shrinker->nr; | |
191 | shrinker->nr = 0; | |
192 | ||
193 | while (total_scan >= SHRINK_BATCH) { | |
194 | long this_scan = SHRINK_BATCH; | |
195 | int shrink_ret; | |
b15e0905 | 196 | int nr_before; |
1da177e4 | 197 | |
8e1f936b RR |
198 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
199 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); | |
1da177e4 LT |
200 | if (shrink_ret == -1) |
201 | break; | |
b15e0905 | 202 | if (shrink_ret < nr_before) |
203 | ret += nr_before - shrink_ret; | |
f8891e5e | 204 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
205 | total_scan -= this_scan; |
206 | ||
207 | cond_resched(); | |
208 | } | |
209 | ||
210 | shrinker->nr += total_scan; | |
211 | } | |
212 | up_read(&shrinker_rwsem); | |
b15e0905 | 213 | return ret; |
1da177e4 LT |
214 | } |
215 | ||
216 | /* Called without lock on whether page is mapped, so answer is unstable */ | |
217 | static inline int page_mapping_inuse(struct page *page) | |
218 | { | |
219 | struct address_space *mapping; | |
220 | ||
221 | /* Page is in somebody's page tables. */ | |
222 | if (page_mapped(page)) | |
223 | return 1; | |
224 | ||
225 | /* Be more reluctant to reclaim swapcache than pagecache */ | |
226 | if (PageSwapCache(page)) | |
227 | return 1; | |
228 | ||
229 | mapping = page_mapping(page); | |
230 | if (!mapping) | |
231 | return 0; | |
232 | ||
233 | /* File is mmap'd by somebody? */ | |
234 | return mapping_mapped(mapping); | |
235 | } | |
236 | ||
237 | static inline int is_page_cache_freeable(struct page *page) | |
238 | { | |
239 | return page_count(page) - !!PagePrivate(page) == 2; | |
240 | } | |
241 | ||
242 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
243 | { | |
930d9152 | 244 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
245 | return 1; |
246 | if (!bdi_write_congested(bdi)) | |
247 | return 1; | |
248 | if (bdi == current->backing_dev_info) | |
249 | return 1; | |
250 | return 0; | |
251 | } | |
252 | ||
253 | /* | |
254 | * We detected a synchronous write error writing a page out. Probably | |
255 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
256 | * fsync(), msync() or close(). | |
257 | * | |
258 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
259 | * prevents it from being freed up. But we have a ref on the page and once | |
260 | * that page is locked, the mapping is pinned. | |
261 | * | |
262 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
263 | * __GFP_FS. | |
264 | */ | |
265 | static void handle_write_error(struct address_space *mapping, | |
266 | struct page *page, int error) | |
267 | { | |
268 | lock_page(page); | |
3e9f45bd GC |
269 | if (page_mapping(page) == mapping) |
270 | mapping_set_error(mapping, error); | |
1da177e4 LT |
271 | unlock_page(page); |
272 | } | |
273 | ||
c661b078 AW |
274 | /* Request for sync pageout. */ |
275 | enum pageout_io { | |
276 | PAGEOUT_IO_ASYNC, | |
277 | PAGEOUT_IO_SYNC, | |
278 | }; | |
279 | ||
04e62a29 CL |
280 | /* possible outcome of pageout() */ |
281 | typedef enum { | |
282 | /* failed to write page out, page is locked */ | |
283 | PAGE_KEEP, | |
284 | /* move page to the active list, page is locked */ | |
285 | PAGE_ACTIVATE, | |
286 | /* page has been sent to the disk successfully, page is unlocked */ | |
287 | PAGE_SUCCESS, | |
288 | /* page is clean and locked */ | |
289 | PAGE_CLEAN, | |
290 | } pageout_t; | |
291 | ||
1da177e4 | 292 | /* |
1742f19f AM |
293 | * pageout is called by shrink_page_list() for each dirty page. |
294 | * Calls ->writepage(). | |
1da177e4 | 295 | */ |
c661b078 AW |
296 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
297 | enum pageout_io sync_writeback) | |
1da177e4 LT |
298 | { |
299 | /* | |
300 | * If the page is dirty, only perform writeback if that write | |
301 | * will be non-blocking. To prevent this allocation from being | |
302 | * stalled by pagecache activity. But note that there may be | |
303 | * stalls if we need to run get_block(). We could test | |
304 | * PagePrivate for that. | |
305 | * | |
306 | * If this process is currently in generic_file_write() against | |
307 | * this page's queue, we can perform writeback even if that | |
308 | * will block. | |
309 | * | |
310 | * If the page is swapcache, write it back even if that would | |
311 | * block, for some throttling. This happens by accident, because | |
312 | * swap_backing_dev_info is bust: it doesn't reflect the | |
313 | * congestion state of the swapdevs. Easy to fix, if needed. | |
314 | * See swapfile.c:page_queue_congested(). | |
315 | */ | |
316 | if (!is_page_cache_freeable(page)) | |
317 | return PAGE_KEEP; | |
318 | if (!mapping) { | |
319 | /* | |
320 | * Some data journaling orphaned pages can have | |
321 | * page->mapping == NULL while being dirty with clean buffers. | |
322 | */ | |
323aca6c | 323 | if (PagePrivate(page)) { |
1da177e4 LT |
324 | if (try_to_free_buffers(page)) { |
325 | ClearPageDirty(page); | |
326 | printk("%s: orphaned page\n", __FUNCTION__); | |
327 | return PAGE_CLEAN; | |
328 | } | |
329 | } | |
330 | return PAGE_KEEP; | |
331 | } | |
332 | if (mapping->a_ops->writepage == NULL) | |
333 | return PAGE_ACTIVATE; | |
334 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
335 | return PAGE_KEEP; | |
336 | ||
337 | if (clear_page_dirty_for_io(page)) { | |
338 | int res; | |
339 | struct writeback_control wbc = { | |
340 | .sync_mode = WB_SYNC_NONE, | |
341 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
342 | .range_start = 0, |
343 | .range_end = LLONG_MAX, | |
1da177e4 LT |
344 | .nonblocking = 1, |
345 | .for_reclaim = 1, | |
346 | }; | |
347 | ||
348 | SetPageReclaim(page); | |
349 | res = mapping->a_ops->writepage(page, &wbc); | |
350 | if (res < 0) | |
351 | handle_write_error(mapping, page, res); | |
994fc28c | 352 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
353 | ClearPageReclaim(page); |
354 | return PAGE_ACTIVATE; | |
355 | } | |
c661b078 AW |
356 | |
357 | /* | |
358 | * Wait on writeback if requested to. This happens when | |
359 | * direct reclaiming a large contiguous area and the | |
360 | * first attempt to free a range of pages fails. | |
361 | */ | |
362 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
363 | wait_on_page_writeback(page); | |
364 | ||
1da177e4 LT |
365 | if (!PageWriteback(page)) { |
366 | /* synchronous write or broken a_ops? */ | |
367 | ClearPageReclaim(page); | |
368 | } | |
e129b5c2 | 369 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
370 | return PAGE_SUCCESS; |
371 | } | |
372 | ||
373 | return PAGE_CLEAN; | |
374 | } | |
375 | ||
a649fd92 AM |
376 | /* |
377 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
378 | * someone else has a ref on the page, abort and return 0. If it was | |
379 | * successfully detached, return 1. Assumes the caller has a single ref on | |
380 | * this page. | |
381 | */ | |
b20a3503 | 382 | int remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 383 | { |
28e4d965 NP |
384 | BUG_ON(!PageLocked(page)); |
385 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc CL |
386 | |
387 | write_lock_irq(&mapping->tree_lock); | |
49d2e9cc | 388 | /* |
0fd0e6b0 NP |
389 | * The non racy check for a busy page. |
390 | * | |
391 | * Must be careful with the order of the tests. When someone has | |
392 | * a ref to the page, it may be possible that they dirty it then | |
393 | * drop the reference. So if PageDirty is tested before page_count | |
394 | * here, then the following race may occur: | |
395 | * | |
396 | * get_user_pages(&page); | |
397 | * [user mapping goes away] | |
398 | * write_to(page); | |
399 | * !PageDirty(page) [good] | |
400 | * SetPageDirty(page); | |
401 | * put_page(page); | |
402 | * !page_count(page) [good, discard it] | |
403 | * | |
404 | * [oops, our write_to data is lost] | |
405 | * | |
406 | * Reversing the order of the tests ensures such a situation cannot | |
407 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
408 | * load is not satisfied before that of page->_count. | |
409 | * | |
410 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
411 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc CL |
412 | */ |
413 | if (unlikely(page_count(page) != 2)) | |
414 | goto cannot_free; | |
415 | smp_rmb(); | |
416 | if (unlikely(PageDirty(page))) | |
417 | goto cannot_free; | |
418 | ||
419 | if (PageSwapCache(page)) { | |
420 | swp_entry_t swap = { .val = page_private(page) }; | |
421 | __delete_from_swap_cache(page); | |
422 | write_unlock_irq(&mapping->tree_lock); | |
423 | swap_free(swap); | |
424 | __put_page(page); /* The pagecache ref */ | |
425 | return 1; | |
426 | } | |
427 | ||
428 | __remove_from_page_cache(page); | |
429 | write_unlock_irq(&mapping->tree_lock); | |
430 | __put_page(page); | |
431 | return 1; | |
432 | ||
433 | cannot_free: | |
434 | write_unlock_irq(&mapping->tree_lock); | |
435 | return 0; | |
436 | } | |
437 | ||
1da177e4 | 438 | /* |
1742f19f | 439 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 440 | */ |
1742f19f | 441 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
442 | struct scan_control *sc, |
443 | enum pageout_io sync_writeback) | |
1da177e4 LT |
444 | { |
445 | LIST_HEAD(ret_pages); | |
446 | struct pagevec freed_pvec; | |
447 | int pgactivate = 0; | |
05ff5137 | 448 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
449 | |
450 | cond_resched(); | |
451 | ||
452 | pagevec_init(&freed_pvec, 1); | |
453 | while (!list_empty(page_list)) { | |
454 | struct address_space *mapping; | |
455 | struct page *page; | |
456 | int may_enter_fs; | |
457 | int referenced; | |
458 | ||
459 | cond_resched(); | |
460 | ||
461 | page = lru_to_page(page_list); | |
462 | list_del(&page->lru); | |
463 | ||
464 | if (TestSetPageLocked(page)) | |
465 | goto keep; | |
466 | ||
725d704e | 467 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
468 | |
469 | sc->nr_scanned++; | |
80e43426 CL |
470 | |
471 | if (!sc->may_swap && page_mapped(page)) | |
472 | goto keep_locked; | |
473 | ||
1da177e4 LT |
474 | /* Double the slab pressure for mapped and swapcache pages */ |
475 | if (page_mapped(page) || PageSwapCache(page)) | |
476 | sc->nr_scanned++; | |
477 | ||
c661b078 AW |
478 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
479 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
480 | ||
481 | if (PageWriteback(page)) { | |
482 | /* | |
483 | * Synchronous reclaim is performed in two passes, | |
484 | * first an asynchronous pass over the list to | |
485 | * start parallel writeback, and a second synchronous | |
486 | * pass to wait for the IO to complete. Wait here | |
487 | * for any page for which writeback has already | |
488 | * started. | |
489 | */ | |
490 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
491 | wait_on_page_writeback(page); | |
492 | else | |
493 | goto keep_locked; | |
494 | } | |
1da177e4 | 495 | |
f7b7fd8f | 496 | referenced = page_referenced(page, 1); |
1da177e4 | 497 | /* In active use or really unfreeable? Activate it. */ |
5ad333eb AW |
498 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && |
499 | referenced && page_mapping_inuse(page)) | |
1da177e4 LT |
500 | goto activate_locked; |
501 | ||
502 | #ifdef CONFIG_SWAP | |
503 | /* | |
504 | * Anonymous process memory has backing store? | |
505 | * Try to allocate it some swap space here. | |
506 | */ | |
6e5ef1a9 | 507 | if (PageAnon(page) && !PageSwapCache(page)) |
1480a540 | 508 | if (!add_to_swap(page, GFP_ATOMIC)) |
1da177e4 | 509 | goto activate_locked; |
1da177e4 LT |
510 | #endif /* CONFIG_SWAP */ |
511 | ||
512 | mapping = page_mapping(page); | |
1da177e4 LT |
513 | |
514 | /* | |
515 | * The page is mapped into the page tables of one or more | |
516 | * processes. Try to unmap it here. | |
517 | */ | |
518 | if (page_mapped(page) && mapping) { | |
a48d07af | 519 | switch (try_to_unmap(page, 0)) { |
1da177e4 LT |
520 | case SWAP_FAIL: |
521 | goto activate_locked; | |
522 | case SWAP_AGAIN: | |
523 | goto keep_locked; | |
524 | case SWAP_SUCCESS: | |
525 | ; /* try to free the page below */ | |
526 | } | |
527 | } | |
528 | ||
529 | if (PageDirty(page)) { | |
5ad333eb | 530 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) |
1da177e4 LT |
531 | goto keep_locked; |
532 | if (!may_enter_fs) | |
533 | goto keep_locked; | |
52a8363e | 534 | if (!sc->may_writepage) |
1da177e4 LT |
535 | goto keep_locked; |
536 | ||
537 | /* Page is dirty, try to write it out here */ | |
c661b078 | 538 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
539 | case PAGE_KEEP: |
540 | goto keep_locked; | |
541 | case PAGE_ACTIVATE: | |
542 | goto activate_locked; | |
543 | case PAGE_SUCCESS: | |
544 | if (PageWriteback(page) || PageDirty(page)) | |
545 | goto keep; | |
546 | /* | |
547 | * A synchronous write - probably a ramdisk. Go | |
548 | * ahead and try to reclaim the page. | |
549 | */ | |
550 | if (TestSetPageLocked(page)) | |
551 | goto keep; | |
552 | if (PageDirty(page) || PageWriteback(page)) | |
553 | goto keep_locked; | |
554 | mapping = page_mapping(page); | |
555 | case PAGE_CLEAN: | |
556 | ; /* try to free the page below */ | |
557 | } | |
558 | } | |
559 | ||
560 | /* | |
561 | * If the page has buffers, try to free the buffer mappings | |
562 | * associated with this page. If we succeed we try to free | |
563 | * the page as well. | |
564 | * | |
565 | * We do this even if the page is PageDirty(). | |
566 | * try_to_release_page() does not perform I/O, but it is | |
567 | * possible for a page to have PageDirty set, but it is actually | |
568 | * clean (all its buffers are clean). This happens if the | |
569 | * buffers were written out directly, with submit_bh(). ext3 | |
570 | * will do this, as well as the blockdev mapping. | |
571 | * try_to_release_page() will discover that cleanness and will | |
572 | * drop the buffers and mark the page clean - it can be freed. | |
573 | * | |
574 | * Rarely, pages can have buffers and no ->mapping. These are | |
575 | * the pages which were not successfully invalidated in | |
576 | * truncate_complete_page(). We try to drop those buffers here | |
577 | * and if that worked, and the page is no longer mapped into | |
578 | * process address space (page_count == 1) it can be freed. | |
579 | * Otherwise, leave the page on the LRU so it is swappable. | |
580 | */ | |
581 | if (PagePrivate(page)) { | |
582 | if (!try_to_release_page(page, sc->gfp_mask)) | |
583 | goto activate_locked; | |
584 | if (!mapping && page_count(page) == 1) | |
585 | goto free_it; | |
586 | } | |
587 | ||
28e4d965 | 588 | if (!mapping || !remove_mapping(mapping, page)) |
49d2e9cc | 589 | goto keep_locked; |
1da177e4 LT |
590 | |
591 | free_it: | |
592 | unlock_page(page); | |
05ff5137 | 593 | nr_reclaimed++; |
1da177e4 LT |
594 | if (!pagevec_add(&freed_pvec, page)) |
595 | __pagevec_release_nonlru(&freed_pvec); | |
596 | continue; | |
597 | ||
598 | activate_locked: | |
599 | SetPageActive(page); | |
600 | pgactivate++; | |
601 | keep_locked: | |
602 | unlock_page(page); | |
603 | keep: | |
604 | list_add(&page->lru, &ret_pages); | |
725d704e | 605 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
606 | } |
607 | list_splice(&ret_pages, page_list); | |
608 | if (pagevec_count(&freed_pvec)) | |
609 | __pagevec_release_nonlru(&freed_pvec); | |
f8891e5e | 610 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 611 | return nr_reclaimed; |
1da177e4 LT |
612 | } |
613 | ||
5ad333eb AW |
614 | /* LRU Isolation modes. */ |
615 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ | |
616 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ | |
617 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ | |
618 | ||
619 | /* | |
620 | * Attempt to remove the specified page from its LRU. Only take this page | |
621 | * if it is of the appropriate PageActive status. Pages which are being | |
622 | * freed elsewhere are also ignored. | |
623 | * | |
624 | * page: page to consider | |
625 | * mode: one of the LRU isolation modes defined above | |
626 | * | |
627 | * returns 0 on success, -ve errno on failure. | |
628 | */ | |
629 | static int __isolate_lru_page(struct page *page, int mode) | |
630 | { | |
631 | int ret = -EINVAL; | |
632 | ||
633 | /* Only take pages on the LRU. */ | |
634 | if (!PageLRU(page)) | |
635 | return ret; | |
636 | ||
637 | /* | |
638 | * When checking the active state, we need to be sure we are | |
639 | * dealing with comparible boolean values. Take the logical not | |
640 | * of each. | |
641 | */ | |
642 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
643 | return ret; | |
644 | ||
645 | ret = -EBUSY; | |
646 | if (likely(get_page_unless_zero(page))) { | |
647 | /* | |
648 | * Be careful not to clear PageLRU until after we're | |
649 | * sure the page is not being freed elsewhere -- the | |
650 | * page release code relies on it. | |
651 | */ | |
652 | ClearPageLRU(page); | |
653 | ret = 0; | |
654 | } | |
655 | ||
656 | return ret; | |
657 | } | |
658 | ||
1da177e4 LT |
659 | /* |
660 | * zone->lru_lock is heavily contended. Some of the functions that | |
661 | * shrink the lists perform better by taking out a batch of pages | |
662 | * and working on them outside the LRU lock. | |
663 | * | |
664 | * For pagecache intensive workloads, this function is the hottest | |
665 | * spot in the kernel (apart from copy_*_user functions). | |
666 | * | |
667 | * Appropriate locks must be held before calling this function. | |
668 | * | |
669 | * @nr_to_scan: The number of pages to look through on the list. | |
670 | * @src: The LRU list to pull pages off. | |
671 | * @dst: The temp list to put pages on to. | |
672 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
673 | * @order: The caller's attempted allocation order |
674 | * @mode: One of the LRU isolation modes | |
1da177e4 LT |
675 | * |
676 | * returns how many pages were moved onto *@dst. | |
677 | */ | |
69e05944 AM |
678 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
679 | struct list_head *src, struct list_head *dst, | |
5ad333eb | 680 | unsigned long *scanned, int order, int mode) |
1da177e4 | 681 | { |
69e05944 | 682 | unsigned long nr_taken = 0; |
c9b02d97 | 683 | unsigned long scan; |
1da177e4 | 684 | |
c9b02d97 | 685 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
686 | struct page *page; |
687 | unsigned long pfn; | |
688 | unsigned long end_pfn; | |
689 | unsigned long page_pfn; | |
690 | int zone_id; | |
691 | ||
1da177e4 LT |
692 | page = lru_to_page(src); |
693 | prefetchw_prev_lru_page(page, src, flags); | |
694 | ||
725d704e | 695 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 696 | |
5ad333eb AW |
697 | switch (__isolate_lru_page(page, mode)) { |
698 | case 0: | |
699 | list_move(&page->lru, dst); | |
7c8ee9a8 | 700 | nr_taken++; |
5ad333eb AW |
701 | break; |
702 | ||
703 | case -EBUSY: | |
704 | /* else it is being freed elsewhere */ | |
705 | list_move(&page->lru, src); | |
706 | continue; | |
46453a6e | 707 | |
5ad333eb AW |
708 | default: |
709 | BUG(); | |
710 | } | |
711 | ||
712 | if (!order) | |
713 | continue; | |
714 | ||
715 | /* | |
716 | * Attempt to take all pages in the order aligned region | |
717 | * surrounding the tag page. Only take those pages of | |
718 | * the same active state as that tag page. We may safely | |
719 | * round the target page pfn down to the requested order | |
720 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
721 | * where that page is in a different zone we will detect | |
722 | * it from its zone id and abort this block scan. | |
723 | */ | |
724 | zone_id = page_zone_id(page); | |
725 | page_pfn = page_to_pfn(page); | |
726 | pfn = page_pfn & ~((1 << order) - 1); | |
727 | end_pfn = pfn + (1 << order); | |
728 | for (; pfn < end_pfn; pfn++) { | |
729 | struct page *cursor_page; | |
730 | ||
731 | /* The target page is in the block, ignore it. */ | |
732 | if (unlikely(pfn == page_pfn)) | |
733 | continue; | |
734 | ||
735 | /* Avoid holes within the zone. */ | |
736 | if (unlikely(!pfn_valid_within(pfn))) | |
737 | break; | |
738 | ||
739 | cursor_page = pfn_to_page(pfn); | |
740 | /* Check that we have not crossed a zone boundary. */ | |
741 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
742 | continue; | |
743 | switch (__isolate_lru_page(cursor_page, mode)) { | |
744 | case 0: | |
745 | list_move(&cursor_page->lru, dst); | |
746 | nr_taken++; | |
747 | scan++; | |
748 | break; | |
749 | ||
750 | case -EBUSY: | |
751 | /* else it is being freed elsewhere */ | |
752 | list_move(&cursor_page->lru, src); | |
753 | default: | |
754 | break; | |
755 | } | |
756 | } | |
1da177e4 LT |
757 | } |
758 | ||
759 | *scanned = scan; | |
760 | return nr_taken; | |
761 | } | |
762 | ||
5ad333eb AW |
763 | /* |
764 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
765 | * any active bits from the pages in the list. | |
766 | */ | |
767 | static unsigned long clear_active_flags(struct list_head *page_list) | |
768 | { | |
769 | int nr_active = 0; | |
770 | struct page *page; | |
771 | ||
772 | list_for_each_entry(page, page_list, lru) | |
773 | if (PageActive(page)) { | |
774 | ClearPageActive(page); | |
775 | nr_active++; | |
776 | } | |
777 | ||
778 | return nr_active; | |
779 | } | |
780 | ||
1da177e4 | 781 | /* |
1742f19f AM |
782 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
783 | * of reclaimed pages | |
1da177e4 | 784 | */ |
1742f19f AM |
785 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
786 | struct zone *zone, struct scan_control *sc) | |
1da177e4 LT |
787 | { |
788 | LIST_HEAD(page_list); | |
789 | struct pagevec pvec; | |
69e05944 | 790 | unsigned long nr_scanned = 0; |
05ff5137 | 791 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
792 | |
793 | pagevec_init(&pvec, 1); | |
794 | ||
795 | lru_add_drain(); | |
796 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 797 | do { |
1da177e4 | 798 | struct page *page; |
69e05944 AM |
799 | unsigned long nr_taken; |
800 | unsigned long nr_scan; | |
801 | unsigned long nr_freed; | |
5ad333eb | 802 | unsigned long nr_active; |
1da177e4 LT |
803 | |
804 | nr_taken = isolate_lru_pages(sc->swap_cluster_max, | |
5ad333eb AW |
805 | &zone->inactive_list, |
806 | &page_list, &nr_scan, sc->order, | |
807 | (sc->order > PAGE_ALLOC_COSTLY_ORDER)? | |
808 | ISOLATE_BOTH : ISOLATE_INACTIVE); | |
809 | nr_active = clear_active_flags(&page_list); | |
e9187bdc | 810 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb AW |
811 | |
812 | __mod_zone_page_state(zone, NR_ACTIVE, -nr_active); | |
813 | __mod_zone_page_state(zone, NR_INACTIVE, | |
814 | -(nr_taken - nr_active)); | |
1da177e4 LT |
815 | zone->pages_scanned += nr_scan; |
816 | spin_unlock_irq(&zone->lru_lock); | |
817 | ||
69e05944 | 818 | nr_scanned += nr_scan; |
c661b078 AW |
819 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
820 | ||
821 | /* | |
822 | * If we are direct reclaiming for contiguous pages and we do | |
823 | * not reclaim everything in the list, try again and wait | |
824 | * for IO to complete. This will stall high-order allocations | |
825 | * but that should be acceptable to the caller | |
826 | */ | |
827 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
828 | sc->order > PAGE_ALLOC_COSTLY_ORDER) { | |
829 | congestion_wait(WRITE, HZ/10); | |
830 | ||
831 | /* | |
832 | * The attempt at page out may have made some | |
833 | * of the pages active, mark them inactive again. | |
834 | */ | |
835 | nr_active = clear_active_flags(&page_list); | |
836 | count_vm_events(PGDEACTIVATE, nr_active); | |
837 | ||
838 | nr_freed += shrink_page_list(&page_list, sc, | |
839 | PAGEOUT_IO_SYNC); | |
840 | } | |
841 | ||
05ff5137 | 842 | nr_reclaimed += nr_freed; |
a74609fa NP |
843 | local_irq_disable(); |
844 | if (current_is_kswapd()) { | |
f8891e5e CL |
845 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan); |
846 | __count_vm_events(KSWAPD_STEAL, nr_freed); | |
a74609fa | 847 | } else |
f8891e5e | 848 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan); |
918d3f90 | 849 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa | 850 | |
fb8d14e1 WF |
851 | if (nr_taken == 0) |
852 | goto done; | |
853 | ||
a74609fa | 854 | spin_lock(&zone->lru_lock); |
1da177e4 LT |
855 | /* |
856 | * Put back any unfreeable pages. | |
857 | */ | |
858 | while (!list_empty(&page_list)) { | |
859 | page = lru_to_page(&page_list); | |
725d704e | 860 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 861 | SetPageLRU(page); |
1da177e4 LT |
862 | list_del(&page->lru); |
863 | if (PageActive(page)) | |
864 | add_page_to_active_list(zone, page); | |
865 | else | |
866 | add_page_to_inactive_list(zone, page); | |
867 | if (!pagevec_add(&pvec, page)) { | |
868 | spin_unlock_irq(&zone->lru_lock); | |
869 | __pagevec_release(&pvec); | |
870 | spin_lock_irq(&zone->lru_lock); | |
871 | } | |
872 | } | |
69e05944 | 873 | } while (nr_scanned < max_scan); |
fb8d14e1 | 874 | spin_unlock(&zone->lru_lock); |
1da177e4 | 875 | done: |
fb8d14e1 | 876 | local_irq_enable(); |
1da177e4 | 877 | pagevec_release(&pvec); |
05ff5137 | 878 | return nr_reclaimed; |
1da177e4 LT |
879 | } |
880 | ||
3bb1a852 MB |
881 | /* |
882 | * We are about to scan this zone at a certain priority level. If that priority | |
883 | * level is smaller (ie: more urgent) than the previous priority, then note | |
884 | * that priority level within the zone. This is done so that when the next | |
885 | * process comes in to scan this zone, it will immediately start out at this | |
886 | * priority level rather than having to build up its own scanning priority. | |
887 | * Here, this priority affects only the reclaim-mapped threshold. | |
888 | */ | |
889 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
890 | { | |
891 | if (priority < zone->prev_priority) | |
892 | zone->prev_priority = priority; | |
893 | } | |
894 | ||
4ff1ffb4 NP |
895 | static inline int zone_is_near_oom(struct zone *zone) |
896 | { | |
c8785385 CL |
897 | return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE) |
898 | + zone_page_state(zone, NR_INACTIVE))*3; | |
4ff1ffb4 NP |
899 | } |
900 | ||
1da177e4 LT |
901 | /* |
902 | * This moves pages from the active list to the inactive list. | |
903 | * | |
904 | * We move them the other way if the page is referenced by one or more | |
905 | * processes, from rmap. | |
906 | * | |
907 | * If the pages are mostly unmapped, the processing is fast and it is | |
908 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
909 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
910 | * should drop zone->lru_lock around each page. It's impossible to balance | |
911 | * this, so instead we remove the pages from the LRU while processing them. | |
912 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
913 | * nobody will play with that bit on a non-LRU page. | |
914 | * | |
915 | * The downside is that we have to touch page->_count against each page. | |
916 | * But we had to alter page->flags anyway. | |
917 | */ | |
1742f19f | 918 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
bbdb396a | 919 | struct scan_control *sc, int priority) |
1da177e4 | 920 | { |
69e05944 | 921 | unsigned long pgmoved; |
1da177e4 | 922 | int pgdeactivate = 0; |
69e05944 | 923 | unsigned long pgscanned; |
1da177e4 LT |
924 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
925 | LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ | |
926 | LIST_HEAD(l_active); /* Pages to go onto the active_list */ | |
927 | struct page *page; | |
928 | struct pagevec pvec; | |
929 | int reclaim_mapped = 0; | |
2903fb16 | 930 | |
6e5ef1a9 | 931 | if (sc->may_swap) { |
2903fb16 CL |
932 | long mapped_ratio; |
933 | long distress; | |
934 | long swap_tendency; | |
935 | ||
4ff1ffb4 NP |
936 | if (zone_is_near_oom(zone)) |
937 | goto force_reclaim_mapped; | |
938 | ||
2903fb16 CL |
939 | /* |
940 | * `distress' is a measure of how much trouble we're having | |
941 | * reclaiming pages. 0 -> no problems. 100 -> great trouble. | |
942 | */ | |
bbdb396a | 943 | distress = 100 >> min(zone->prev_priority, priority); |
2903fb16 CL |
944 | |
945 | /* | |
946 | * The point of this algorithm is to decide when to start | |
947 | * reclaiming mapped memory instead of just pagecache. Work out | |
948 | * how much memory | |
949 | * is mapped. | |
950 | */ | |
f3dbd344 CL |
951 | mapped_ratio = ((global_page_state(NR_FILE_MAPPED) + |
952 | global_page_state(NR_ANON_PAGES)) * 100) / | |
bf02cf4b | 953 | vm_total_pages; |
2903fb16 CL |
954 | |
955 | /* | |
956 | * Now decide how much we really want to unmap some pages. The | |
957 | * mapped ratio is downgraded - just because there's a lot of | |
958 | * mapped memory doesn't necessarily mean that page reclaim | |
959 | * isn't succeeding. | |
960 | * | |
961 | * The distress ratio is important - we don't want to start | |
962 | * going oom. | |
963 | * | |
964 | * A 100% value of vm_swappiness overrides this algorithm | |
965 | * altogether. | |
966 | */ | |
d6277db4 | 967 | swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; |
2903fb16 CL |
968 | |
969 | /* | |
970 | * Now use this metric to decide whether to start moving mapped | |
971 | * memory onto the inactive list. | |
972 | */ | |
973 | if (swap_tendency >= 100) | |
4ff1ffb4 | 974 | force_reclaim_mapped: |
2903fb16 CL |
975 | reclaim_mapped = 1; |
976 | } | |
1da177e4 LT |
977 | |
978 | lru_add_drain(); | |
979 | spin_lock_irq(&zone->lru_lock); | |
980 | pgmoved = isolate_lru_pages(nr_pages, &zone->active_list, | |
5ad333eb | 981 | &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE); |
1da177e4 | 982 | zone->pages_scanned += pgscanned; |
c8785385 | 983 | __mod_zone_page_state(zone, NR_ACTIVE, -pgmoved); |
1da177e4 LT |
984 | spin_unlock_irq(&zone->lru_lock); |
985 | ||
1da177e4 LT |
986 | while (!list_empty(&l_hold)) { |
987 | cond_resched(); | |
988 | page = lru_to_page(&l_hold); | |
989 | list_del(&page->lru); | |
990 | if (page_mapped(page)) { | |
991 | if (!reclaim_mapped || | |
992 | (total_swap_pages == 0 && PageAnon(page)) || | |
f7b7fd8f | 993 | page_referenced(page, 0)) { |
1da177e4 LT |
994 | list_add(&page->lru, &l_active); |
995 | continue; | |
996 | } | |
997 | } | |
998 | list_add(&page->lru, &l_inactive); | |
999 | } | |
1000 | ||
1001 | pagevec_init(&pvec, 1); | |
1002 | pgmoved = 0; | |
1003 | spin_lock_irq(&zone->lru_lock); | |
1004 | while (!list_empty(&l_inactive)) { | |
1005 | page = lru_to_page(&l_inactive); | |
1006 | prefetchw_prev_lru_page(page, &l_inactive, flags); | |
725d704e | 1007 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1008 | SetPageLRU(page); |
725d704e | 1009 | VM_BUG_ON(!PageActive(page)); |
4c84cacf NP |
1010 | ClearPageActive(page); |
1011 | ||
1da177e4 LT |
1012 | list_move(&page->lru, &zone->inactive_list); |
1013 | pgmoved++; | |
1014 | if (!pagevec_add(&pvec, page)) { | |
c8785385 | 1015 | __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); |
1da177e4 LT |
1016 | spin_unlock_irq(&zone->lru_lock); |
1017 | pgdeactivate += pgmoved; | |
1018 | pgmoved = 0; | |
1019 | if (buffer_heads_over_limit) | |
1020 | pagevec_strip(&pvec); | |
1021 | __pagevec_release(&pvec); | |
1022 | spin_lock_irq(&zone->lru_lock); | |
1023 | } | |
1024 | } | |
c8785385 | 1025 | __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); |
1da177e4 LT |
1026 | pgdeactivate += pgmoved; |
1027 | if (buffer_heads_over_limit) { | |
1028 | spin_unlock_irq(&zone->lru_lock); | |
1029 | pagevec_strip(&pvec); | |
1030 | spin_lock_irq(&zone->lru_lock); | |
1031 | } | |
1032 | ||
1033 | pgmoved = 0; | |
1034 | while (!list_empty(&l_active)) { | |
1035 | page = lru_to_page(&l_active); | |
1036 | prefetchw_prev_lru_page(page, &l_active, flags); | |
725d704e | 1037 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 1038 | SetPageLRU(page); |
725d704e | 1039 | VM_BUG_ON(!PageActive(page)); |
1da177e4 LT |
1040 | list_move(&page->lru, &zone->active_list); |
1041 | pgmoved++; | |
1042 | if (!pagevec_add(&pvec, page)) { | |
c8785385 | 1043 | __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); |
1da177e4 LT |
1044 | pgmoved = 0; |
1045 | spin_unlock_irq(&zone->lru_lock); | |
1046 | __pagevec_release(&pvec); | |
1047 | spin_lock_irq(&zone->lru_lock); | |
1048 | } | |
1049 | } | |
c8785385 | 1050 | __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); |
a74609fa | 1051 | |
f8891e5e CL |
1052 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1053 | __count_vm_events(PGDEACTIVATE, pgdeactivate); | |
1054 | spin_unlock_irq(&zone->lru_lock); | |
1da177e4 | 1055 | |
a74609fa | 1056 | pagevec_release(&pvec); |
1da177e4 LT |
1057 | } |
1058 | ||
1059 | /* | |
1060 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1061 | */ | |
05ff5137 AM |
1062 | static unsigned long shrink_zone(int priority, struct zone *zone, |
1063 | struct scan_control *sc) | |
1da177e4 LT |
1064 | { |
1065 | unsigned long nr_active; | |
1066 | unsigned long nr_inactive; | |
8695949a | 1067 | unsigned long nr_to_scan; |
05ff5137 | 1068 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1069 | |
53e9a615 MH |
1070 | atomic_inc(&zone->reclaim_in_progress); |
1071 | ||
1da177e4 LT |
1072 | /* |
1073 | * Add one to `nr_to_scan' just to make sure that the kernel will | |
1074 | * slowly sift through the active list. | |
1075 | */ | |
c8785385 CL |
1076 | zone->nr_scan_active += |
1077 | (zone_page_state(zone, NR_ACTIVE) >> priority) + 1; | |
1da177e4 LT |
1078 | nr_active = zone->nr_scan_active; |
1079 | if (nr_active >= sc->swap_cluster_max) | |
1080 | zone->nr_scan_active = 0; | |
1081 | else | |
1082 | nr_active = 0; | |
1083 | ||
c8785385 CL |
1084 | zone->nr_scan_inactive += |
1085 | (zone_page_state(zone, NR_INACTIVE) >> priority) + 1; | |
1da177e4 LT |
1086 | nr_inactive = zone->nr_scan_inactive; |
1087 | if (nr_inactive >= sc->swap_cluster_max) | |
1088 | zone->nr_scan_inactive = 0; | |
1089 | else | |
1090 | nr_inactive = 0; | |
1091 | ||
1da177e4 LT |
1092 | while (nr_active || nr_inactive) { |
1093 | if (nr_active) { | |
8695949a | 1094 | nr_to_scan = min(nr_active, |
1da177e4 | 1095 | (unsigned long)sc->swap_cluster_max); |
8695949a | 1096 | nr_active -= nr_to_scan; |
bbdb396a | 1097 | shrink_active_list(nr_to_scan, zone, sc, priority); |
1da177e4 LT |
1098 | } |
1099 | ||
1100 | if (nr_inactive) { | |
8695949a | 1101 | nr_to_scan = min(nr_inactive, |
1da177e4 | 1102 | (unsigned long)sc->swap_cluster_max); |
8695949a | 1103 | nr_inactive -= nr_to_scan; |
1742f19f AM |
1104 | nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, |
1105 | sc); | |
1da177e4 LT |
1106 | } |
1107 | } | |
1108 | ||
232ea4d6 | 1109 | throttle_vm_writeout(sc->gfp_mask); |
53e9a615 MH |
1110 | |
1111 | atomic_dec(&zone->reclaim_in_progress); | |
05ff5137 | 1112 | return nr_reclaimed; |
1da177e4 LT |
1113 | } |
1114 | ||
1115 | /* | |
1116 | * This is the direct reclaim path, for page-allocating processes. We only | |
1117 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1118 | * request. | |
1119 | * | |
1120 | * We reclaim from a zone even if that zone is over pages_high. Because: | |
1121 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order | |
1122 | * allocation or | |
1123 | * b) The zones may be over pages_high but they must go *over* pages_high to | |
1124 | * satisfy the `incremental min' zone defense algorithm. | |
1125 | * | |
1126 | * Returns the number of reclaimed pages. | |
1127 | * | |
1128 | * If a zone is deemed to be full of pinned pages then just give it a light | |
1129 | * scan then give up on it. | |
1130 | */ | |
1742f19f | 1131 | static unsigned long shrink_zones(int priority, struct zone **zones, |
05ff5137 | 1132 | struct scan_control *sc) |
1da177e4 | 1133 | { |
05ff5137 | 1134 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
1135 | int i; |
1136 | ||
408d8544 | 1137 | sc->all_unreclaimable = 1; |
1da177e4 LT |
1138 | for (i = 0; zones[i] != NULL; i++) { |
1139 | struct zone *zone = zones[i]; | |
1140 | ||
f3fe6512 | 1141 | if (!populated_zone(zone)) |
1da177e4 LT |
1142 | continue; |
1143 | ||
02a0e53d | 1144 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 LT |
1145 | continue; |
1146 | ||
3bb1a852 | 1147 | note_zone_scanning_priority(zone, priority); |
1da177e4 | 1148 | |
8695949a | 1149 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
1150 | continue; /* Let kswapd poll it */ |
1151 | ||
408d8544 NP |
1152 | sc->all_unreclaimable = 0; |
1153 | ||
05ff5137 | 1154 | nr_reclaimed += shrink_zone(priority, zone, sc); |
1da177e4 | 1155 | } |
05ff5137 | 1156 | return nr_reclaimed; |
1da177e4 LT |
1157 | } |
1158 | ||
1159 | /* | |
1160 | * This is the main entry point to direct page reclaim. | |
1161 | * | |
1162 | * If a full scan of the inactive list fails to free enough memory then we | |
1163 | * are "out of memory" and something needs to be killed. | |
1164 | * | |
1165 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1166 | * high - the zone may be full of dirty or under-writeback pages, which this | |
1167 | * caller can't do much about. We kick pdflush and take explicit naps in the | |
1168 | * hope that some of these pages can be written. But if the allocating task | |
1169 | * holds filesystem locks which prevent writeout this might not work, and the | |
1170 | * allocation attempt will fail. | |
1171 | */ | |
5ad333eb | 1172 | unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask) |
1da177e4 LT |
1173 | { |
1174 | int priority; | |
1175 | int ret = 0; | |
69e05944 | 1176 | unsigned long total_scanned = 0; |
05ff5137 | 1177 | unsigned long nr_reclaimed = 0; |
1da177e4 | 1178 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 LT |
1179 | unsigned long lru_pages = 0; |
1180 | int i; | |
179e9639 AM |
1181 | struct scan_control sc = { |
1182 | .gfp_mask = gfp_mask, | |
1183 | .may_writepage = !laptop_mode, | |
1184 | .swap_cluster_max = SWAP_CLUSTER_MAX, | |
1185 | .may_swap = 1, | |
d6277db4 | 1186 | .swappiness = vm_swappiness, |
5ad333eb | 1187 | .order = order, |
179e9639 | 1188 | }; |
1da177e4 | 1189 | |
f8891e5e | 1190 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
1191 | |
1192 | for (i = 0; zones[i] != NULL; i++) { | |
1193 | struct zone *zone = zones[i]; | |
1194 | ||
02a0e53d | 1195 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 LT |
1196 | continue; |
1197 | ||
c8785385 CL |
1198 | lru_pages += zone_page_state(zone, NR_ACTIVE) |
1199 | + zone_page_state(zone, NR_INACTIVE); | |
1da177e4 LT |
1200 | } |
1201 | ||
1202 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1da177e4 | 1203 | sc.nr_scanned = 0; |
f7b7fd8f RR |
1204 | if (!priority) |
1205 | disable_swap_token(); | |
1742f19f | 1206 | nr_reclaimed += shrink_zones(priority, zones, &sc); |
1da177e4 LT |
1207 | shrink_slab(sc.nr_scanned, gfp_mask, lru_pages); |
1208 | if (reclaim_state) { | |
05ff5137 | 1209 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1210 | reclaim_state->reclaimed_slab = 0; |
1211 | } | |
1212 | total_scanned += sc.nr_scanned; | |
05ff5137 | 1213 | if (nr_reclaimed >= sc.swap_cluster_max) { |
1da177e4 LT |
1214 | ret = 1; |
1215 | goto out; | |
1216 | } | |
1217 | ||
1218 | /* | |
1219 | * Try to write back as many pages as we just scanned. This | |
1220 | * tends to cause slow streaming writers to write data to the | |
1221 | * disk smoothly, at the dirtying rate, which is nice. But | |
1222 | * that's undesirable in laptop mode, where we *want* lumpy | |
1223 | * writeout. So in laptop mode, write out the whole world. | |
1224 | */ | |
179e9639 AM |
1225 | if (total_scanned > sc.swap_cluster_max + |
1226 | sc.swap_cluster_max / 2) { | |
687a21ce | 1227 | wakeup_pdflush(laptop_mode ? 0 : total_scanned); |
1da177e4 LT |
1228 | sc.may_writepage = 1; |
1229 | } | |
1230 | ||
1231 | /* Take a nap, wait for some writeback to complete */ | |
1232 | if (sc.nr_scanned && priority < DEF_PRIORITY - 2) | |
3fcfab16 | 1233 | congestion_wait(WRITE, HZ/10); |
1da177e4 | 1234 | } |
408d8544 NP |
1235 | /* top priority shrink_caches still had more to do? don't OOM, then */ |
1236 | if (!sc.all_unreclaimable) | |
1237 | ret = 1; | |
1da177e4 | 1238 | out: |
3bb1a852 MB |
1239 | /* |
1240 | * Now that we've scanned all the zones at this priority level, note | |
1241 | * that level within the zone so that the next thread which performs | |
1242 | * scanning of this zone will immediately start out at this priority | |
1243 | * level. This affects only the decision whether or not to bring | |
1244 | * mapped pages onto the inactive list. | |
1245 | */ | |
1246 | if (priority < 0) | |
1247 | priority = 0; | |
1da177e4 LT |
1248 | for (i = 0; zones[i] != 0; i++) { |
1249 | struct zone *zone = zones[i]; | |
1250 | ||
02a0e53d | 1251 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 LT |
1252 | continue; |
1253 | ||
3bb1a852 | 1254 | zone->prev_priority = priority; |
1da177e4 LT |
1255 | } |
1256 | return ret; | |
1257 | } | |
1258 | ||
1259 | /* | |
1260 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
1261 | * they are all at pages_high. | |
1262 | * | |
1da177e4 LT |
1263 | * Returns the number of pages which were actually freed. |
1264 | * | |
1265 | * There is special handling here for zones which are full of pinned pages. | |
1266 | * This can happen if the pages are all mlocked, or if they are all used by | |
1267 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1268 | * What we do is to detect the case where all pages in the zone have been | |
1269 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1270 | * dead and from now on, only perform a short scan. Basically we're polling | |
1271 | * the zone for when the problem goes away. | |
1272 | * | |
1273 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
1274 | * zones which have free_pages > pages_high, but once a zone is found to have | |
1275 | * free_pages <= pages_high, we scan that zone and the lower zones regardless | |
1276 | * of the number of free pages in the lower zones. This interoperates with | |
1277 | * the page allocator fallback scheme to ensure that aging of pages is balanced | |
1278 | * across the zones. | |
1279 | */ | |
d6277db4 | 1280 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1281 | { |
1da177e4 LT |
1282 | int all_zones_ok; |
1283 | int priority; | |
1284 | int i; | |
69e05944 | 1285 | unsigned long total_scanned; |
05ff5137 | 1286 | unsigned long nr_reclaimed; |
1da177e4 | 1287 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
1288 | struct scan_control sc = { |
1289 | .gfp_mask = GFP_KERNEL, | |
1290 | .may_swap = 1, | |
d6277db4 RW |
1291 | .swap_cluster_max = SWAP_CLUSTER_MAX, |
1292 | .swappiness = vm_swappiness, | |
5ad333eb | 1293 | .order = order, |
179e9639 | 1294 | }; |
3bb1a852 MB |
1295 | /* |
1296 | * temp_priority is used to remember the scanning priority at which | |
1297 | * this zone was successfully refilled to free_pages == pages_high. | |
1298 | */ | |
1299 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
1300 | |
1301 | loop_again: | |
1302 | total_scanned = 0; | |
05ff5137 | 1303 | nr_reclaimed = 0; |
c0bbbc73 | 1304 | sc.may_writepage = !laptop_mode; |
f8891e5e | 1305 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 1306 | |
3bb1a852 MB |
1307 | for (i = 0; i < pgdat->nr_zones; i++) |
1308 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
1309 | |
1310 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
1311 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
1312 | unsigned long lru_pages = 0; | |
1313 | ||
f7b7fd8f RR |
1314 | /* The swap token gets in the way of swapout... */ |
1315 | if (!priority) | |
1316 | disable_swap_token(); | |
1317 | ||
1da177e4 LT |
1318 | all_zones_ok = 1; |
1319 | ||
d6277db4 RW |
1320 | /* |
1321 | * Scan in the highmem->dma direction for the highest | |
1322 | * zone which needs scanning | |
1323 | */ | |
1324 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
1325 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 1326 | |
d6277db4 RW |
1327 | if (!populated_zone(zone)) |
1328 | continue; | |
1da177e4 | 1329 | |
d6277db4 RW |
1330 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1331 | continue; | |
1da177e4 | 1332 | |
d6277db4 RW |
1333 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1334 | 0, 0)) { | |
1335 | end_zone = i; | |
e1dbeda6 | 1336 | break; |
1da177e4 | 1337 | } |
1da177e4 | 1338 | } |
e1dbeda6 AM |
1339 | if (i < 0) |
1340 | goto out; | |
1341 | ||
1da177e4 LT |
1342 | for (i = 0; i <= end_zone; i++) { |
1343 | struct zone *zone = pgdat->node_zones + i; | |
1344 | ||
c8785385 CL |
1345 | lru_pages += zone_page_state(zone, NR_ACTIVE) |
1346 | + zone_page_state(zone, NR_INACTIVE); | |
1da177e4 LT |
1347 | } |
1348 | ||
1349 | /* | |
1350 | * Now scan the zone in the dma->highmem direction, stopping | |
1351 | * at the last zone which needs scanning. | |
1352 | * | |
1353 | * We do this because the page allocator works in the opposite | |
1354 | * direction. This prevents the page allocator from allocating | |
1355 | * pages behind kswapd's direction of progress, which would | |
1356 | * cause too much scanning of the lower zones. | |
1357 | */ | |
1358 | for (i = 0; i <= end_zone; i++) { | |
1359 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 1360 | int nr_slab; |
1da177e4 | 1361 | |
f3fe6512 | 1362 | if (!populated_zone(zone)) |
1da177e4 LT |
1363 | continue; |
1364 | ||
1365 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
1366 | continue; | |
1367 | ||
d6277db4 RW |
1368 | if (!zone_watermark_ok(zone, order, zone->pages_high, |
1369 | end_zone, 0)) | |
1370 | all_zones_ok = 0; | |
3bb1a852 | 1371 | temp_priority[i] = priority; |
1da177e4 | 1372 | sc.nr_scanned = 0; |
3bb1a852 | 1373 | note_zone_scanning_priority(zone, priority); |
32a4330d RR |
1374 | /* |
1375 | * We put equal pressure on every zone, unless one | |
1376 | * zone has way too many pages free already. | |
1377 | */ | |
1378 | if (!zone_watermark_ok(zone, order, 8*zone->pages_high, | |
1379 | end_zone, 0)) | |
1380 | nr_reclaimed += shrink_zone(priority, zone, &sc); | |
1da177e4 | 1381 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 1382 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
1383 | lru_pages); | |
05ff5137 | 1384 | nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 LT |
1385 | total_scanned += sc.nr_scanned; |
1386 | if (zone->all_unreclaimable) | |
1387 | continue; | |
b15e0905 | 1388 | if (nr_slab == 0 && zone->pages_scanned >= |
c8785385 CL |
1389 | (zone_page_state(zone, NR_ACTIVE) |
1390 | + zone_page_state(zone, NR_INACTIVE)) * 6) | |
1391 | zone->all_unreclaimable = 1; | |
1da177e4 LT |
1392 | /* |
1393 | * If we've done a decent amount of scanning and | |
1394 | * the reclaim ratio is low, start doing writepage | |
1395 | * even in laptop mode | |
1396 | */ | |
1397 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
05ff5137 | 1398 | total_scanned > nr_reclaimed + nr_reclaimed / 2) |
1da177e4 LT |
1399 | sc.may_writepage = 1; |
1400 | } | |
1da177e4 LT |
1401 | if (all_zones_ok) |
1402 | break; /* kswapd: all done */ | |
1403 | /* | |
1404 | * OK, kswapd is getting into trouble. Take a nap, then take | |
1405 | * another pass across the zones. | |
1406 | */ | |
1407 | if (total_scanned && priority < DEF_PRIORITY - 2) | |
3fcfab16 | 1408 | congestion_wait(WRITE, HZ/10); |
1da177e4 LT |
1409 | |
1410 | /* | |
1411 | * We do this so kswapd doesn't build up large priorities for | |
1412 | * example when it is freeing in parallel with allocators. It | |
1413 | * matches the direct reclaim path behaviour in terms of impact | |
1414 | * on zone->*_priority. | |
1415 | */ | |
d6277db4 | 1416 | if (nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
1417 | break; |
1418 | } | |
1419 | out: | |
3bb1a852 MB |
1420 | /* |
1421 | * Note within each zone the priority level at which this zone was | |
1422 | * brought into a happy state. So that the next thread which scans this | |
1423 | * zone will start out at that priority level. | |
1424 | */ | |
1da177e4 LT |
1425 | for (i = 0; i < pgdat->nr_zones; i++) { |
1426 | struct zone *zone = pgdat->node_zones + i; | |
1427 | ||
3bb1a852 | 1428 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
1429 | } |
1430 | if (!all_zones_ok) { | |
1431 | cond_resched(); | |
8357376d RW |
1432 | |
1433 | try_to_freeze(); | |
1434 | ||
1da177e4 LT |
1435 | goto loop_again; |
1436 | } | |
1437 | ||
05ff5137 | 1438 | return nr_reclaimed; |
1da177e4 LT |
1439 | } |
1440 | ||
1441 | /* | |
1442 | * The background pageout daemon, started as a kernel thread | |
1443 | * from the init process. | |
1444 | * | |
1445 | * This basically trickles out pages so that we have _some_ | |
1446 | * free memory available even if there is no other activity | |
1447 | * that frees anything up. This is needed for things like routing | |
1448 | * etc, where we otherwise might have all activity going on in | |
1449 | * asynchronous contexts that cannot page things out. | |
1450 | * | |
1451 | * If there are applications that are active memory-allocators | |
1452 | * (most normal use), this basically shouldn't matter. | |
1453 | */ | |
1454 | static int kswapd(void *p) | |
1455 | { | |
1456 | unsigned long order; | |
1457 | pg_data_t *pgdat = (pg_data_t*)p; | |
1458 | struct task_struct *tsk = current; | |
1459 | DEFINE_WAIT(wait); | |
1460 | struct reclaim_state reclaim_state = { | |
1461 | .reclaimed_slab = 0, | |
1462 | }; | |
1463 | cpumask_t cpumask; | |
1464 | ||
1da177e4 LT |
1465 | cpumask = node_to_cpumask(pgdat->node_id); |
1466 | if (!cpus_empty(cpumask)) | |
1467 | set_cpus_allowed(tsk, cpumask); | |
1468 | current->reclaim_state = &reclaim_state; | |
1469 | ||
1470 | /* | |
1471 | * Tell the memory management that we're a "memory allocator", | |
1472 | * and that if we need more memory we should get access to it | |
1473 | * regardless (see "__alloc_pages()"). "kswapd" should | |
1474 | * never get caught in the normal page freeing logic. | |
1475 | * | |
1476 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
1477 | * you need a small amount of memory in order to be able to | |
1478 | * page out something else, and this flag essentially protects | |
1479 | * us from recursively trying to free more memory as we're | |
1480 | * trying to free the first piece of memory in the first place). | |
1481 | */ | |
930d9152 | 1482 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 1483 | set_freezable(); |
1da177e4 LT |
1484 | |
1485 | order = 0; | |
1486 | for ( ; ; ) { | |
1487 | unsigned long new_order; | |
3e1d1d28 | 1488 | |
1da177e4 LT |
1489 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
1490 | new_order = pgdat->kswapd_max_order; | |
1491 | pgdat->kswapd_max_order = 0; | |
1492 | if (order < new_order) { | |
1493 | /* | |
1494 | * Don't sleep if someone wants a larger 'order' | |
1495 | * allocation | |
1496 | */ | |
1497 | order = new_order; | |
1498 | } else { | |
b1296cc4 RW |
1499 | if (!freezing(current)) |
1500 | schedule(); | |
1501 | ||
1da177e4 LT |
1502 | order = pgdat->kswapd_max_order; |
1503 | } | |
1504 | finish_wait(&pgdat->kswapd_wait, &wait); | |
1505 | ||
b1296cc4 RW |
1506 | if (!try_to_freeze()) { |
1507 | /* We can speed up thawing tasks if we don't call | |
1508 | * balance_pgdat after returning from the refrigerator | |
1509 | */ | |
1510 | balance_pgdat(pgdat, order); | |
1511 | } | |
1da177e4 LT |
1512 | } |
1513 | return 0; | |
1514 | } | |
1515 | ||
1516 | /* | |
1517 | * A zone is low on free memory, so wake its kswapd task to service it. | |
1518 | */ | |
1519 | void wakeup_kswapd(struct zone *zone, int order) | |
1520 | { | |
1521 | pg_data_t *pgdat; | |
1522 | ||
f3fe6512 | 1523 | if (!populated_zone(zone)) |
1da177e4 LT |
1524 | return; |
1525 | ||
1526 | pgdat = zone->zone_pgdat; | |
7fb1d9fc | 1527 | if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0)) |
1da177e4 LT |
1528 | return; |
1529 | if (pgdat->kswapd_max_order < order) | |
1530 | pgdat->kswapd_max_order = order; | |
02a0e53d | 1531 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 1532 | return; |
8d0986e2 | 1533 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 1534 | return; |
8d0986e2 | 1535 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
1536 | } |
1537 | ||
1538 | #ifdef CONFIG_PM | |
1539 | /* | |
d6277db4 RW |
1540 | * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages |
1541 | * from LRU lists system-wide, for given pass and priority, and returns the | |
1542 | * number of reclaimed pages | |
1543 | * | |
1544 | * For pass > 3 we also try to shrink the LRU lists that contain a few pages | |
1545 | */ | |
e07aa05b NC |
1546 | static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, |
1547 | int pass, struct scan_control *sc) | |
d6277db4 RW |
1548 | { |
1549 | struct zone *zone; | |
1550 | unsigned long nr_to_scan, ret = 0; | |
1551 | ||
1552 | for_each_zone(zone) { | |
1553 | ||
1554 | if (!populated_zone(zone)) | |
1555 | continue; | |
1556 | ||
1557 | if (zone->all_unreclaimable && prio != DEF_PRIORITY) | |
1558 | continue; | |
1559 | ||
1560 | /* For pass = 0 we don't shrink the active list */ | |
1561 | if (pass > 0) { | |
c8785385 CL |
1562 | zone->nr_scan_active += |
1563 | (zone_page_state(zone, NR_ACTIVE) >> prio) + 1; | |
d6277db4 RW |
1564 | if (zone->nr_scan_active >= nr_pages || pass > 3) { |
1565 | zone->nr_scan_active = 0; | |
c8785385 CL |
1566 | nr_to_scan = min(nr_pages, |
1567 | zone_page_state(zone, NR_ACTIVE)); | |
bbdb396a | 1568 | shrink_active_list(nr_to_scan, zone, sc, prio); |
d6277db4 RW |
1569 | } |
1570 | } | |
1571 | ||
c8785385 CL |
1572 | zone->nr_scan_inactive += |
1573 | (zone_page_state(zone, NR_INACTIVE) >> prio) + 1; | |
d6277db4 RW |
1574 | if (zone->nr_scan_inactive >= nr_pages || pass > 3) { |
1575 | zone->nr_scan_inactive = 0; | |
c8785385 CL |
1576 | nr_to_scan = min(nr_pages, |
1577 | zone_page_state(zone, NR_INACTIVE)); | |
d6277db4 RW |
1578 | ret += shrink_inactive_list(nr_to_scan, zone, sc); |
1579 | if (ret >= nr_pages) | |
1580 | return ret; | |
1581 | } | |
1582 | } | |
1583 | ||
1584 | return ret; | |
1585 | } | |
1586 | ||
76395d37 AM |
1587 | static unsigned long count_lru_pages(void) |
1588 | { | |
c8785385 | 1589 | return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE); |
76395d37 AM |
1590 | } |
1591 | ||
d6277db4 RW |
1592 | /* |
1593 | * Try to free `nr_pages' of memory, system-wide, and return the number of | |
1594 | * freed pages. | |
1595 | * | |
1596 | * Rather than trying to age LRUs the aim is to preserve the overall | |
1597 | * LRU order by reclaiming preferentially | |
1598 | * inactive > active > active referenced > active mapped | |
1da177e4 | 1599 | */ |
69e05944 | 1600 | unsigned long shrink_all_memory(unsigned long nr_pages) |
1da177e4 | 1601 | { |
d6277db4 | 1602 | unsigned long lru_pages, nr_slab; |
69e05944 | 1603 | unsigned long ret = 0; |
d6277db4 RW |
1604 | int pass; |
1605 | struct reclaim_state reclaim_state; | |
d6277db4 RW |
1606 | struct scan_control sc = { |
1607 | .gfp_mask = GFP_KERNEL, | |
1608 | .may_swap = 0, | |
1609 | .swap_cluster_max = nr_pages, | |
1610 | .may_writepage = 1, | |
1611 | .swappiness = vm_swappiness, | |
1da177e4 LT |
1612 | }; |
1613 | ||
1614 | current->reclaim_state = &reclaim_state; | |
69e05944 | 1615 | |
76395d37 | 1616 | lru_pages = count_lru_pages(); |
972d1a7b | 1617 | nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); |
d6277db4 RW |
1618 | /* If slab caches are huge, it's better to hit them first */ |
1619 | while (nr_slab >= lru_pages) { | |
1620 | reclaim_state.reclaimed_slab = 0; | |
1621 | shrink_slab(nr_pages, sc.gfp_mask, lru_pages); | |
1622 | if (!reclaim_state.reclaimed_slab) | |
1da177e4 | 1623 | break; |
d6277db4 RW |
1624 | |
1625 | ret += reclaim_state.reclaimed_slab; | |
1626 | if (ret >= nr_pages) | |
1627 | goto out; | |
1628 | ||
1629 | nr_slab -= reclaim_state.reclaimed_slab; | |
1da177e4 | 1630 | } |
d6277db4 RW |
1631 | |
1632 | /* | |
1633 | * We try to shrink LRUs in 5 passes: | |
1634 | * 0 = Reclaim from inactive_list only | |
1635 | * 1 = Reclaim from active list but don't reclaim mapped | |
1636 | * 2 = 2nd pass of type 1 | |
1637 | * 3 = Reclaim mapped (normal reclaim) | |
1638 | * 4 = 2nd pass of type 3 | |
1639 | */ | |
1640 | for (pass = 0; pass < 5; pass++) { | |
1641 | int prio; | |
1642 | ||
d6277db4 RW |
1643 | /* Force reclaiming mapped pages in the passes #3 and #4 */ |
1644 | if (pass > 2) { | |
1645 | sc.may_swap = 1; | |
1646 | sc.swappiness = 100; | |
1647 | } | |
1648 | ||
1649 | for (prio = DEF_PRIORITY; prio >= 0; prio--) { | |
1650 | unsigned long nr_to_scan = nr_pages - ret; | |
1651 | ||
d6277db4 | 1652 | sc.nr_scanned = 0; |
d6277db4 RW |
1653 | ret += shrink_all_zones(nr_to_scan, prio, pass, &sc); |
1654 | if (ret >= nr_pages) | |
1655 | goto out; | |
1656 | ||
1657 | reclaim_state.reclaimed_slab = 0; | |
76395d37 AM |
1658 | shrink_slab(sc.nr_scanned, sc.gfp_mask, |
1659 | count_lru_pages()); | |
d6277db4 RW |
1660 | ret += reclaim_state.reclaimed_slab; |
1661 | if (ret >= nr_pages) | |
1662 | goto out; | |
1663 | ||
1664 | if (sc.nr_scanned && prio < DEF_PRIORITY - 2) | |
3fcfab16 | 1665 | congestion_wait(WRITE, HZ / 10); |
d6277db4 | 1666 | } |
248a0301 | 1667 | } |
d6277db4 RW |
1668 | |
1669 | /* | |
1670 | * If ret = 0, we could not shrink LRUs, but there may be something | |
1671 | * in slab caches | |
1672 | */ | |
76395d37 | 1673 | if (!ret) { |
d6277db4 RW |
1674 | do { |
1675 | reclaim_state.reclaimed_slab = 0; | |
76395d37 | 1676 | shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages()); |
d6277db4 RW |
1677 | ret += reclaim_state.reclaimed_slab; |
1678 | } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); | |
76395d37 | 1679 | } |
d6277db4 RW |
1680 | |
1681 | out: | |
1da177e4 | 1682 | current->reclaim_state = NULL; |
d6277db4 | 1683 | |
1da177e4 LT |
1684 | return ret; |
1685 | } | |
1686 | #endif | |
1687 | ||
1da177e4 LT |
1688 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
1689 | not required for correctness. So if the last cpu in a node goes | |
1690 | away, we get changed to run anywhere: as the first one comes back, | |
1691 | restore their cpu bindings. */ | |
9c7b216d | 1692 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 1693 | unsigned long action, void *hcpu) |
1da177e4 LT |
1694 | { |
1695 | pg_data_t *pgdat; | |
1696 | cpumask_t mask; | |
1697 | ||
8bb78442 | 1698 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
ec936fc5 | 1699 | for_each_online_pgdat(pgdat) { |
1da177e4 LT |
1700 | mask = node_to_cpumask(pgdat->node_id); |
1701 | if (any_online_cpu(mask) != NR_CPUS) | |
1702 | /* One of our CPUs online: restore mask */ | |
1703 | set_cpus_allowed(pgdat->kswapd, mask); | |
1704 | } | |
1705 | } | |
1706 | return NOTIFY_OK; | |
1707 | } | |
1da177e4 | 1708 | |
3218ae14 YG |
1709 | /* |
1710 | * This kswapd start function will be called by init and node-hot-add. | |
1711 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
1712 | */ | |
1713 | int kswapd_run(int nid) | |
1714 | { | |
1715 | pg_data_t *pgdat = NODE_DATA(nid); | |
1716 | int ret = 0; | |
1717 | ||
1718 | if (pgdat->kswapd) | |
1719 | return 0; | |
1720 | ||
1721 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
1722 | if (IS_ERR(pgdat->kswapd)) { | |
1723 | /* failure at boot is fatal */ | |
1724 | BUG_ON(system_state == SYSTEM_BOOTING); | |
1725 | printk("Failed to start kswapd on node %d\n",nid); | |
1726 | ret = -1; | |
1727 | } | |
1728 | return ret; | |
1729 | } | |
1730 | ||
1da177e4 LT |
1731 | static int __init kswapd_init(void) |
1732 | { | |
3218ae14 | 1733 | int nid; |
69e05944 | 1734 | |
1da177e4 | 1735 | swap_setup(); |
3218ae14 YG |
1736 | for_each_online_node(nid) |
1737 | kswapd_run(nid); | |
1da177e4 LT |
1738 | hotcpu_notifier(cpu_callback, 0); |
1739 | return 0; | |
1740 | } | |
1741 | ||
1742 | module_init(kswapd_init) | |
9eeff239 CL |
1743 | |
1744 | #ifdef CONFIG_NUMA | |
1745 | /* | |
1746 | * Zone reclaim mode | |
1747 | * | |
1748 | * If non-zero call zone_reclaim when the number of free pages falls below | |
1749 | * the watermarks. | |
9eeff239 CL |
1750 | */ |
1751 | int zone_reclaim_mode __read_mostly; | |
1752 | ||
1b2ffb78 CL |
1753 | #define RECLAIM_OFF 0 |
1754 | #define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */ | |
1755 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ | |
1756 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
1757 | ||
a92f7126 CL |
1758 | /* |
1759 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
1760 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
1761 | * a zone. | |
1762 | */ | |
1763 | #define ZONE_RECLAIM_PRIORITY 4 | |
1764 | ||
9614634f CL |
1765 | /* |
1766 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
1767 | * occur. | |
1768 | */ | |
1769 | int sysctl_min_unmapped_ratio = 1; | |
1770 | ||
0ff38490 CL |
1771 | /* |
1772 | * If the number of slab pages in a zone grows beyond this percentage then | |
1773 | * slab reclaim needs to occur. | |
1774 | */ | |
1775 | int sysctl_min_slab_ratio = 5; | |
1776 | ||
9eeff239 CL |
1777 | /* |
1778 | * Try to free up some pages from this zone through reclaim. | |
1779 | */ | |
179e9639 | 1780 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 1781 | { |
7fb2d46d | 1782 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 1783 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
1784 | struct task_struct *p = current; |
1785 | struct reclaim_state reclaim_state; | |
8695949a | 1786 | int priority; |
05ff5137 | 1787 | unsigned long nr_reclaimed = 0; |
179e9639 AM |
1788 | struct scan_control sc = { |
1789 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
1790 | .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP), | |
69e05944 AM |
1791 | .swap_cluster_max = max_t(unsigned long, nr_pages, |
1792 | SWAP_CLUSTER_MAX), | |
179e9639 | 1793 | .gfp_mask = gfp_mask, |
d6277db4 | 1794 | .swappiness = vm_swappiness, |
179e9639 | 1795 | }; |
83e33a47 | 1796 | unsigned long slab_reclaimable; |
9eeff239 CL |
1797 | |
1798 | disable_swap_token(); | |
9eeff239 | 1799 | cond_resched(); |
d4f7796e CL |
1800 | /* |
1801 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
1802 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
1803 | * and RECLAIM_SWAP. | |
1804 | */ | |
1805 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
9eeff239 CL |
1806 | reclaim_state.reclaimed_slab = 0; |
1807 | p->reclaim_state = &reclaim_state; | |
c84db23c | 1808 | |
0ff38490 CL |
1809 | if (zone_page_state(zone, NR_FILE_PAGES) - |
1810 | zone_page_state(zone, NR_FILE_MAPPED) > | |
1811 | zone->min_unmapped_pages) { | |
1812 | /* | |
1813 | * Free memory by calling shrink zone with increasing | |
1814 | * priorities until we have enough memory freed. | |
1815 | */ | |
1816 | priority = ZONE_RECLAIM_PRIORITY; | |
1817 | do { | |
3bb1a852 | 1818 | note_zone_scanning_priority(zone, priority); |
0ff38490 CL |
1819 | nr_reclaimed += shrink_zone(priority, zone, &sc); |
1820 | priority--; | |
1821 | } while (priority >= 0 && nr_reclaimed < nr_pages); | |
1822 | } | |
c84db23c | 1823 | |
83e33a47 CL |
1824 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
1825 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 1826 | /* |
7fb2d46d | 1827 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
1828 | * many pages were freed in this zone. So we take the current |
1829 | * number of slab pages and shake the slab until it is reduced | |
1830 | * by the same nr_pages that we used for reclaiming unmapped | |
1831 | * pages. | |
2a16e3f4 | 1832 | * |
0ff38490 CL |
1833 | * Note that shrink_slab will free memory on all zones and may |
1834 | * take a long time. | |
2a16e3f4 | 1835 | */ |
0ff38490 | 1836 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
1837 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
1838 | slab_reclaimable - nr_pages) | |
0ff38490 | 1839 | ; |
83e33a47 CL |
1840 | |
1841 | /* | |
1842 | * Update nr_reclaimed by the number of slab pages we | |
1843 | * reclaimed from this zone. | |
1844 | */ | |
1845 | nr_reclaimed += slab_reclaimable - | |
1846 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); | |
2a16e3f4 CL |
1847 | } |
1848 | ||
9eeff239 | 1849 | p->reclaim_state = NULL; |
d4f7796e | 1850 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
05ff5137 | 1851 | return nr_reclaimed >= nr_pages; |
9eeff239 | 1852 | } |
179e9639 AM |
1853 | |
1854 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
1855 | { | |
1856 | cpumask_t mask; | |
1857 | int node_id; | |
1858 | ||
1859 | /* | |
0ff38490 CL |
1860 | * Zone reclaim reclaims unmapped file backed pages and |
1861 | * slab pages if we are over the defined limits. | |
34aa1330 | 1862 | * |
9614634f CL |
1863 | * A small portion of unmapped file backed pages is needed for |
1864 | * file I/O otherwise pages read by file I/O will be immediately | |
1865 | * thrown out if the zone is overallocated. So we do not reclaim | |
1866 | * if less than a specified percentage of the zone is used by | |
1867 | * unmapped file backed pages. | |
179e9639 | 1868 | */ |
34aa1330 | 1869 | if (zone_page_state(zone, NR_FILE_PAGES) - |
0ff38490 CL |
1870 | zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages |
1871 | && zone_page_state(zone, NR_SLAB_RECLAIMABLE) | |
1872 | <= zone->min_slab_pages) | |
9614634f | 1873 | return 0; |
179e9639 AM |
1874 | |
1875 | /* | |
1876 | * Avoid concurrent zone reclaims, do not reclaim in a zone that does | |
1877 | * not have reclaimable pages and if we should not delay the allocation | |
1878 | * then do not scan. | |
1879 | */ | |
1880 | if (!(gfp_mask & __GFP_WAIT) || | |
1881 | zone->all_unreclaimable || | |
1882 | atomic_read(&zone->reclaim_in_progress) > 0 || | |
1883 | (current->flags & PF_MEMALLOC)) | |
1884 | return 0; | |
1885 | ||
1886 | /* | |
1887 | * Only run zone reclaim on the local zone or on zones that do not | |
1888 | * have associated processors. This will favor the local processor | |
1889 | * over remote processors and spread off node memory allocations | |
1890 | * as wide as possible. | |
1891 | */ | |
89fa3024 | 1892 | node_id = zone_to_nid(zone); |
179e9639 AM |
1893 | mask = node_to_cpumask(node_id); |
1894 | if (!cpus_empty(mask) && node_id != numa_node_id()) | |
1895 | return 0; | |
1896 | return __zone_reclaim(zone, gfp_mask, order); | |
1897 | } | |
9eeff239 | 1898 | #endif |