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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> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
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> |
873b4771 | 41 | #include <linux/delayacct.h> |
af936a16 | 42 | #include <linux/sysctl.h> |
1da177e4 LT |
43 | |
44 | #include <asm/tlbflush.h> | |
45 | #include <asm/div64.h> | |
46 | ||
47 | #include <linux/swapops.h> | |
48 | ||
0f8053a5 NP |
49 | #include "internal.h" |
50 | ||
1da177e4 | 51 | struct scan_control { |
1da177e4 LT |
52 | /* Incremented by the number of inactive pages that were scanned */ |
53 | unsigned long nr_scanned; | |
54 | ||
a79311c1 RR |
55 | /* Number of pages freed so far during a call to shrink_zones() */ |
56 | unsigned long nr_reclaimed; | |
57 | ||
22fba335 KM |
58 | /* How many pages shrink_list() should reclaim */ |
59 | unsigned long nr_to_reclaim; | |
60 | ||
7b51755c KM |
61 | unsigned long hibernation_mode; |
62 | ||
1da177e4 | 63 | /* This context's GFP mask */ |
6daa0e28 | 64 | gfp_t gfp_mask; |
1da177e4 LT |
65 | |
66 | int may_writepage; | |
67 | ||
a6dc60f8 JW |
68 | /* Can mapped pages be reclaimed? */ |
69 | int may_unmap; | |
f1fd1067 | 70 | |
2e2e4259 KM |
71 | /* Can pages be swapped as part of reclaim? */ |
72 | int may_swap; | |
73 | ||
d6277db4 | 74 | int swappiness; |
408d8544 | 75 | |
5ad333eb | 76 | int order; |
66e1707b | 77 | |
5f53e762 KM |
78 | /* |
79 | * Intend to reclaim enough contenious memory rather than to reclaim | |
80 | * enough amount memory. I.e, it's the mode for high order allocation. | |
81 | */ | |
82 | bool lumpy_reclaim_mode; | |
83 | ||
66e1707b BS |
84 | /* Which cgroup do we reclaim from */ |
85 | struct mem_cgroup *mem_cgroup; | |
86 | ||
327c0e96 KH |
87 | /* |
88 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
89 | * are scanned. | |
90 | */ | |
91 | nodemask_t *nodemask; | |
1da177e4 LT |
92 | }; |
93 | ||
1da177e4 LT |
94 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
95 | ||
96 | #ifdef ARCH_HAS_PREFETCH | |
97 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
98 | do { \ | |
99 | if ((_page)->lru.prev != _base) { \ | |
100 | struct page *prev; \ | |
101 | \ | |
102 | prev = lru_to_page(&(_page->lru)); \ | |
103 | prefetch(&prev->_field); \ | |
104 | } \ | |
105 | } while (0) | |
106 | #else | |
107 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
108 | #endif | |
109 | ||
110 | #ifdef ARCH_HAS_PREFETCHW | |
111 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
112 | do { \ | |
113 | if ((_page)->lru.prev != _base) { \ | |
114 | struct page *prev; \ | |
115 | \ | |
116 | prev = lru_to_page(&(_page->lru)); \ | |
117 | prefetchw(&prev->_field); \ | |
118 | } \ | |
119 | } while (0) | |
120 | #else | |
121 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
122 | #endif | |
123 | ||
124 | /* | |
125 | * From 0 .. 100. Higher means more swappy. | |
126 | */ | |
127 | int vm_swappiness = 60; | |
bd1e22b8 | 128 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
129 | |
130 | static LIST_HEAD(shrinker_list); | |
131 | static DECLARE_RWSEM(shrinker_rwsem); | |
132 | ||
00f0b825 | 133 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 134 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 135 | #else |
e72e2bd6 | 136 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
137 | #endif |
138 | ||
6e901571 KM |
139 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
140 | struct scan_control *sc) | |
141 | { | |
e72e2bd6 | 142 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
143 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
144 | ||
6e901571 KM |
145 | return &zone->reclaim_stat; |
146 | } | |
147 | ||
0b217676 VL |
148 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
149 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 150 | { |
e72e2bd6 | 151 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
152 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
153 | ||
c9f299d9 KM |
154 | return zone_page_state(zone, NR_LRU_BASE + lru); |
155 | } | |
156 | ||
157 | ||
1da177e4 LT |
158 | /* |
159 | * Add a shrinker callback to be called from the vm | |
160 | */ | |
8e1f936b | 161 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 162 | { |
8e1f936b RR |
163 | shrinker->nr = 0; |
164 | down_write(&shrinker_rwsem); | |
165 | list_add_tail(&shrinker->list, &shrinker_list); | |
166 | up_write(&shrinker_rwsem); | |
1da177e4 | 167 | } |
8e1f936b | 168 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
169 | |
170 | /* | |
171 | * Remove one | |
172 | */ | |
8e1f936b | 173 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
174 | { |
175 | down_write(&shrinker_rwsem); | |
176 | list_del(&shrinker->list); | |
177 | up_write(&shrinker_rwsem); | |
1da177e4 | 178 | } |
8e1f936b | 179 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
180 | |
181 | #define SHRINK_BATCH 128 | |
182 | /* | |
183 | * Call the shrink functions to age shrinkable caches | |
184 | * | |
185 | * Here we assume it costs one seek to replace a lru page and that it also | |
186 | * takes a seek to recreate a cache object. With this in mind we age equal | |
187 | * percentages of the lru and ageable caches. This should balance the seeks | |
188 | * generated by these structures. | |
189 | * | |
183ff22b | 190 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
191 | * slab to avoid swapping. |
192 | * | |
193 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
194 | * | |
195 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
196 | * are eligible for the caller's allocation attempt. It is used for balancing | |
197 | * slab reclaim versus page reclaim. | |
b15e0905 | 198 | * |
199 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 200 | */ |
69e05944 AM |
201 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
202 | unsigned long lru_pages) | |
1da177e4 LT |
203 | { |
204 | struct shrinker *shrinker; | |
69e05944 | 205 | unsigned long ret = 0; |
1da177e4 LT |
206 | |
207 | if (scanned == 0) | |
208 | scanned = SWAP_CLUSTER_MAX; | |
209 | ||
210 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 211 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
212 | |
213 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
214 | unsigned long long delta; | |
215 | unsigned long total_scan; | |
7f8275d0 | 216 | unsigned long max_pass; |
1da177e4 | 217 | |
7f8275d0 | 218 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 219 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 220 | delta *= max_pass; |
1da177e4 LT |
221 | do_div(delta, lru_pages + 1); |
222 | shrinker->nr += delta; | |
ea164d73 | 223 | if (shrinker->nr < 0) { |
88c3bd70 DR |
224 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
225 | "delete nr=%ld\n", | |
226 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
227 | shrinker->nr = max_pass; |
228 | } | |
229 | ||
230 | /* | |
231 | * Avoid risking looping forever due to too large nr value: | |
232 | * never try to free more than twice the estimate number of | |
233 | * freeable entries. | |
234 | */ | |
235 | if (shrinker->nr > max_pass * 2) | |
236 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
237 | |
238 | total_scan = shrinker->nr; | |
239 | shrinker->nr = 0; | |
240 | ||
241 | while (total_scan >= SHRINK_BATCH) { | |
242 | long this_scan = SHRINK_BATCH; | |
243 | int shrink_ret; | |
b15e0905 | 244 | int nr_before; |
1da177e4 | 245 | |
7f8275d0 DC |
246 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
247 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
248 | gfp_mask); | |
1da177e4 LT |
249 | if (shrink_ret == -1) |
250 | break; | |
b15e0905 | 251 | if (shrink_ret < nr_before) |
252 | ret += nr_before - shrink_ret; | |
f8891e5e | 253 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
254 | total_scan -= this_scan; |
255 | ||
256 | cond_resched(); | |
257 | } | |
258 | ||
259 | shrinker->nr += total_scan; | |
260 | } | |
261 | up_read(&shrinker_rwsem); | |
b15e0905 | 262 | return ret; |
1da177e4 LT |
263 | } |
264 | ||
1da177e4 LT |
265 | static inline int is_page_cache_freeable(struct page *page) |
266 | { | |
ceddc3a5 JW |
267 | /* |
268 | * A freeable page cache page is referenced only by the caller | |
269 | * that isolated the page, the page cache radix tree and | |
270 | * optional buffer heads at page->private. | |
271 | */ | |
edcf4748 | 272 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
273 | } |
274 | ||
275 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
276 | { | |
930d9152 | 277 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
278 | return 1; |
279 | if (!bdi_write_congested(bdi)) | |
280 | return 1; | |
281 | if (bdi == current->backing_dev_info) | |
282 | return 1; | |
283 | return 0; | |
284 | } | |
285 | ||
286 | /* | |
287 | * We detected a synchronous write error writing a page out. Probably | |
288 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
289 | * fsync(), msync() or close(). | |
290 | * | |
291 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
292 | * prevents it from being freed up. But we have a ref on the page and once | |
293 | * that page is locked, the mapping is pinned. | |
294 | * | |
295 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
296 | * __GFP_FS. | |
297 | */ | |
298 | static void handle_write_error(struct address_space *mapping, | |
299 | struct page *page, int error) | |
300 | { | |
a6aa62a0 | 301 | lock_page_nosync(page); |
3e9f45bd GC |
302 | if (page_mapping(page) == mapping) |
303 | mapping_set_error(mapping, error); | |
1da177e4 LT |
304 | unlock_page(page); |
305 | } | |
306 | ||
c661b078 AW |
307 | /* Request for sync pageout. */ |
308 | enum pageout_io { | |
309 | PAGEOUT_IO_ASYNC, | |
310 | PAGEOUT_IO_SYNC, | |
311 | }; | |
312 | ||
04e62a29 CL |
313 | /* possible outcome of pageout() */ |
314 | typedef enum { | |
315 | /* failed to write page out, page is locked */ | |
316 | PAGE_KEEP, | |
317 | /* move page to the active list, page is locked */ | |
318 | PAGE_ACTIVATE, | |
319 | /* page has been sent to the disk successfully, page is unlocked */ | |
320 | PAGE_SUCCESS, | |
321 | /* page is clean and locked */ | |
322 | PAGE_CLEAN, | |
323 | } pageout_t; | |
324 | ||
1da177e4 | 325 | /* |
1742f19f AM |
326 | * pageout is called by shrink_page_list() for each dirty page. |
327 | * Calls ->writepage(). | |
1da177e4 | 328 | */ |
c661b078 AW |
329 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
330 | enum pageout_io sync_writeback) | |
1da177e4 LT |
331 | { |
332 | /* | |
333 | * If the page is dirty, only perform writeback if that write | |
334 | * will be non-blocking. To prevent this allocation from being | |
335 | * stalled by pagecache activity. But note that there may be | |
336 | * stalls if we need to run get_block(). We could test | |
337 | * PagePrivate for that. | |
338 | * | |
6aceb53b | 339 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
340 | * this page's queue, we can perform writeback even if that |
341 | * will block. | |
342 | * | |
343 | * If the page is swapcache, write it back even if that would | |
344 | * block, for some throttling. This happens by accident, because | |
345 | * swap_backing_dev_info is bust: it doesn't reflect the | |
346 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
347 | */ |
348 | if (!is_page_cache_freeable(page)) | |
349 | return PAGE_KEEP; | |
350 | if (!mapping) { | |
351 | /* | |
352 | * Some data journaling orphaned pages can have | |
353 | * page->mapping == NULL while being dirty with clean buffers. | |
354 | */ | |
266cf658 | 355 | if (page_has_private(page)) { |
1da177e4 LT |
356 | if (try_to_free_buffers(page)) { |
357 | ClearPageDirty(page); | |
d40cee24 | 358 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
359 | return PAGE_CLEAN; |
360 | } | |
361 | } | |
362 | return PAGE_KEEP; | |
363 | } | |
364 | if (mapping->a_ops->writepage == NULL) | |
365 | return PAGE_ACTIVATE; | |
366 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
367 | return PAGE_KEEP; | |
368 | ||
369 | if (clear_page_dirty_for_io(page)) { | |
370 | int res; | |
371 | struct writeback_control wbc = { | |
372 | .sync_mode = WB_SYNC_NONE, | |
373 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
374 | .range_start = 0, |
375 | .range_end = LLONG_MAX, | |
1da177e4 LT |
376 | .nonblocking = 1, |
377 | .for_reclaim = 1, | |
378 | }; | |
379 | ||
380 | SetPageReclaim(page); | |
381 | res = mapping->a_ops->writepage(page, &wbc); | |
382 | if (res < 0) | |
383 | handle_write_error(mapping, page, res); | |
994fc28c | 384 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
385 | ClearPageReclaim(page); |
386 | return PAGE_ACTIVATE; | |
387 | } | |
c661b078 AW |
388 | |
389 | /* | |
390 | * Wait on writeback if requested to. This happens when | |
391 | * direct reclaiming a large contiguous area and the | |
392 | * first attempt to free a range of pages fails. | |
393 | */ | |
394 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
395 | wait_on_page_writeback(page); | |
396 | ||
1da177e4 LT |
397 | if (!PageWriteback(page)) { |
398 | /* synchronous write or broken a_ops? */ | |
399 | ClearPageReclaim(page); | |
400 | } | |
e129b5c2 | 401 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
402 | return PAGE_SUCCESS; |
403 | } | |
404 | ||
405 | return PAGE_CLEAN; | |
406 | } | |
407 | ||
a649fd92 | 408 | /* |
e286781d NP |
409 | * Same as remove_mapping, but if the page is removed from the mapping, it |
410 | * gets returned with a refcount of 0. | |
a649fd92 | 411 | */ |
e286781d | 412 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 413 | { |
28e4d965 NP |
414 | BUG_ON(!PageLocked(page)); |
415 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 416 | |
19fd6231 | 417 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 418 | /* |
0fd0e6b0 NP |
419 | * The non racy check for a busy page. |
420 | * | |
421 | * Must be careful with the order of the tests. When someone has | |
422 | * a ref to the page, it may be possible that they dirty it then | |
423 | * drop the reference. So if PageDirty is tested before page_count | |
424 | * here, then the following race may occur: | |
425 | * | |
426 | * get_user_pages(&page); | |
427 | * [user mapping goes away] | |
428 | * write_to(page); | |
429 | * !PageDirty(page) [good] | |
430 | * SetPageDirty(page); | |
431 | * put_page(page); | |
432 | * !page_count(page) [good, discard it] | |
433 | * | |
434 | * [oops, our write_to data is lost] | |
435 | * | |
436 | * Reversing the order of the tests ensures such a situation cannot | |
437 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
438 | * load is not satisfied before that of page->_count. | |
439 | * | |
440 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
441 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 442 | */ |
e286781d | 443 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 444 | goto cannot_free; |
e286781d NP |
445 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
446 | if (unlikely(PageDirty(page))) { | |
447 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 448 | goto cannot_free; |
e286781d | 449 | } |
49d2e9cc CL |
450 | |
451 | if (PageSwapCache(page)) { | |
452 | swp_entry_t swap = { .val = page_private(page) }; | |
453 | __delete_from_swap_cache(page); | |
19fd6231 | 454 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 455 | swapcache_free(swap, page); |
e286781d NP |
456 | } else { |
457 | __remove_from_page_cache(page); | |
19fd6231 | 458 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 459 | mem_cgroup_uncharge_cache_page(page); |
49d2e9cc CL |
460 | } |
461 | ||
49d2e9cc CL |
462 | return 1; |
463 | ||
464 | cannot_free: | |
19fd6231 | 465 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
466 | return 0; |
467 | } | |
468 | ||
e286781d NP |
469 | /* |
470 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
471 | * someone else has a ref on the page, abort and return 0. If it was | |
472 | * successfully detached, return 1. Assumes the caller has a single ref on | |
473 | * this page. | |
474 | */ | |
475 | int remove_mapping(struct address_space *mapping, struct page *page) | |
476 | { | |
477 | if (__remove_mapping(mapping, page)) { | |
478 | /* | |
479 | * Unfreezing the refcount with 1 rather than 2 effectively | |
480 | * drops the pagecache ref for us without requiring another | |
481 | * atomic operation. | |
482 | */ | |
483 | page_unfreeze_refs(page, 1); | |
484 | return 1; | |
485 | } | |
486 | return 0; | |
487 | } | |
488 | ||
894bc310 LS |
489 | /** |
490 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
491 | * @page: page to be put back to appropriate lru list | |
492 | * | |
493 | * Add previously isolated @page to appropriate LRU list. | |
494 | * Page may still be unevictable for other reasons. | |
495 | * | |
496 | * lru_lock must not be held, interrupts must be enabled. | |
497 | */ | |
894bc310 LS |
498 | void putback_lru_page(struct page *page) |
499 | { | |
500 | int lru; | |
501 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 502 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
503 | |
504 | VM_BUG_ON(PageLRU(page)); | |
505 | ||
506 | redo: | |
507 | ClearPageUnevictable(page); | |
508 | ||
509 | if (page_evictable(page, NULL)) { | |
510 | /* | |
511 | * For evictable pages, we can use the cache. | |
512 | * In event of a race, worst case is we end up with an | |
513 | * unevictable page on [in]active list. | |
514 | * We know how to handle that. | |
515 | */ | |
401a8e1c | 516 | lru = active + page_lru_base_type(page); |
894bc310 LS |
517 | lru_cache_add_lru(page, lru); |
518 | } else { | |
519 | /* | |
520 | * Put unevictable pages directly on zone's unevictable | |
521 | * list. | |
522 | */ | |
523 | lru = LRU_UNEVICTABLE; | |
524 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
525 | /* |
526 | * When racing with an mlock clearing (page is | |
527 | * unlocked), make sure that if the other thread does | |
528 | * not observe our setting of PG_lru and fails | |
529 | * isolation, we see PG_mlocked cleared below and move | |
530 | * the page back to the evictable list. | |
531 | * | |
532 | * The other side is TestClearPageMlocked(). | |
533 | */ | |
534 | smp_mb(); | |
894bc310 | 535 | } |
894bc310 LS |
536 | |
537 | /* | |
538 | * page's status can change while we move it among lru. If an evictable | |
539 | * page is on unevictable list, it never be freed. To avoid that, | |
540 | * check after we added it to the list, again. | |
541 | */ | |
542 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
543 | if (!isolate_lru_page(page)) { | |
544 | put_page(page); | |
545 | goto redo; | |
546 | } | |
547 | /* This means someone else dropped this page from LRU | |
548 | * So, it will be freed or putback to LRU again. There is | |
549 | * nothing to do here. | |
550 | */ | |
551 | } | |
552 | ||
bbfd28ee LS |
553 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
554 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
555 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
556 | count_vm_event(UNEVICTABLE_PGCULLED); | |
557 | ||
894bc310 LS |
558 | put_page(page); /* drop ref from isolate */ |
559 | } | |
560 | ||
dfc8d636 JW |
561 | enum page_references { |
562 | PAGEREF_RECLAIM, | |
563 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 564 | PAGEREF_KEEP, |
dfc8d636 JW |
565 | PAGEREF_ACTIVATE, |
566 | }; | |
567 | ||
568 | static enum page_references page_check_references(struct page *page, | |
569 | struct scan_control *sc) | |
570 | { | |
64574746 | 571 | int referenced_ptes, referenced_page; |
dfc8d636 | 572 | unsigned long vm_flags; |
dfc8d636 | 573 | |
64574746 JW |
574 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
575 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
576 | |
577 | /* Lumpy reclaim - ignore references */ | |
5f53e762 | 578 | if (sc->lumpy_reclaim_mode) |
dfc8d636 JW |
579 | return PAGEREF_RECLAIM; |
580 | ||
581 | /* | |
582 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
583 | * move the page to the unevictable list. | |
584 | */ | |
585 | if (vm_flags & VM_LOCKED) | |
586 | return PAGEREF_RECLAIM; | |
587 | ||
64574746 JW |
588 | if (referenced_ptes) { |
589 | if (PageAnon(page)) | |
590 | return PAGEREF_ACTIVATE; | |
591 | /* | |
592 | * All mapped pages start out with page table | |
593 | * references from the instantiating fault, so we need | |
594 | * to look twice if a mapped file page is used more | |
595 | * than once. | |
596 | * | |
597 | * Mark it and spare it for another trip around the | |
598 | * inactive list. Another page table reference will | |
599 | * lead to its activation. | |
600 | * | |
601 | * Note: the mark is set for activated pages as well | |
602 | * so that recently deactivated but used pages are | |
603 | * quickly recovered. | |
604 | */ | |
605 | SetPageReferenced(page); | |
606 | ||
607 | if (referenced_page) | |
608 | return PAGEREF_ACTIVATE; | |
609 | ||
610 | return PAGEREF_KEEP; | |
611 | } | |
dfc8d636 JW |
612 | |
613 | /* Reclaim if clean, defer dirty pages to writeback */ | |
64574746 JW |
614 | if (referenced_page) |
615 | return PAGEREF_RECLAIM_CLEAN; | |
616 | ||
617 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
618 | } |
619 | ||
1da177e4 | 620 | /* |
1742f19f | 621 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 622 | */ |
1742f19f | 623 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
624 | struct scan_control *sc, |
625 | enum pageout_io sync_writeback) | |
1da177e4 LT |
626 | { |
627 | LIST_HEAD(ret_pages); | |
628 | struct pagevec freed_pvec; | |
629 | int pgactivate = 0; | |
05ff5137 | 630 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
631 | |
632 | cond_resched(); | |
633 | ||
634 | pagevec_init(&freed_pvec, 1); | |
635 | while (!list_empty(page_list)) { | |
dfc8d636 | 636 | enum page_references references; |
1da177e4 LT |
637 | struct address_space *mapping; |
638 | struct page *page; | |
639 | int may_enter_fs; | |
1da177e4 LT |
640 | |
641 | cond_resched(); | |
642 | ||
643 | page = lru_to_page(page_list); | |
644 | list_del(&page->lru); | |
645 | ||
529ae9aa | 646 | if (!trylock_page(page)) |
1da177e4 LT |
647 | goto keep; |
648 | ||
725d704e | 649 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
650 | |
651 | sc->nr_scanned++; | |
80e43426 | 652 | |
b291f000 NP |
653 | if (unlikely(!page_evictable(page, NULL))) |
654 | goto cull_mlocked; | |
894bc310 | 655 | |
a6dc60f8 | 656 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
657 | goto keep_locked; |
658 | ||
1da177e4 LT |
659 | /* Double the slab pressure for mapped and swapcache pages */ |
660 | if (page_mapped(page) || PageSwapCache(page)) | |
661 | sc->nr_scanned++; | |
662 | ||
c661b078 AW |
663 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
664 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
665 | ||
666 | if (PageWriteback(page)) { | |
667 | /* | |
668 | * Synchronous reclaim is performed in two passes, | |
669 | * first an asynchronous pass over the list to | |
670 | * start parallel writeback, and a second synchronous | |
671 | * pass to wait for the IO to complete. Wait here | |
672 | * for any page for which writeback has already | |
673 | * started. | |
674 | */ | |
675 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
676 | wait_on_page_writeback(page); | |
4dd4b920 | 677 | else |
c661b078 AW |
678 | goto keep_locked; |
679 | } | |
1da177e4 | 680 | |
dfc8d636 JW |
681 | references = page_check_references(page, sc); |
682 | switch (references) { | |
683 | case PAGEREF_ACTIVATE: | |
1da177e4 | 684 | goto activate_locked; |
64574746 JW |
685 | case PAGEREF_KEEP: |
686 | goto keep_locked; | |
dfc8d636 JW |
687 | case PAGEREF_RECLAIM: |
688 | case PAGEREF_RECLAIM_CLEAN: | |
689 | ; /* try to reclaim the page below */ | |
690 | } | |
1da177e4 | 691 | |
1da177e4 LT |
692 | /* |
693 | * Anonymous process memory has backing store? | |
694 | * Try to allocate it some swap space here. | |
695 | */ | |
b291f000 | 696 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
697 | if (!(sc->gfp_mask & __GFP_IO)) |
698 | goto keep_locked; | |
ac47b003 | 699 | if (!add_to_swap(page)) |
1da177e4 | 700 | goto activate_locked; |
63eb6b93 | 701 | may_enter_fs = 1; |
b291f000 | 702 | } |
1da177e4 LT |
703 | |
704 | mapping = page_mapping(page); | |
1da177e4 LT |
705 | |
706 | /* | |
707 | * The page is mapped into the page tables of one or more | |
708 | * processes. Try to unmap it here. | |
709 | */ | |
710 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 711 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
712 | case SWAP_FAIL: |
713 | goto activate_locked; | |
714 | case SWAP_AGAIN: | |
715 | goto keep_locked; | |
b291f000 NP |
716 | case SWAP_MLOCK: |
717 | goto cull_mlocked; | |
1da177e4 LT |
718 | case SWAP_SUCCESS: |
719 | ; /* try to free the page below */ | |
720 | } | |
721 | } | |
722 | ||
723 | if (PageDirty(page)) { | |
dfc8d636 | 724 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 725 | goto keep_locked; |
4dd4b920 | 726 | if (!may_enter_fs) |
1da177e4 | 727 | goto keep_locked; |
52a8363e | 728 | if (!sc->may_writepage) |
1da177e4 LT |
729 | goto keep_locked; |
730 | ||
731 | /* Page is dirty, try to write it out here */ | |
c661b078 | 732 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
733 | case PAGE_KEEP: |
734 | goto keep_locked; | |
735 | case PAGE_ACTIVATE: | |
736 | goto activate_locked; | |
737 | case PAGE_SUCCESS: | |
4dd4b920 | 738 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
739 | goto keep; |
740 | /* | |
741 | * A synchronous write - probably a ramdisk. Go | |
742 | * ahead and try to reclaim the page. | |
743 | */ | |
529ae9aa | 744 | if (!trylock_page(page)) |
1da177e4 LT |
745 | goto keep; |
746 | if (PageDirty(page) || PageWriteback(page)) | |
747 | goto keep_locked; | |
748 | mapping = page_mapping(page); | |
749 | case PAGE_CLEAN: | |
750 | ; /* try to free the page below */ | |
751 | } | |
752 | } | |
753 | ||
754 | /* | |
755 | * If the page has buffers, try to free the buffer mappings | |
756 | * associated with this page. If we succeed we try to free | |
757 | * the page as well. | |
758 | * | |
759 | * We do this even if the page is PageDirty(). | |
760 | * try_to_release_page() does not perform I/O, but it is | |
761 | * possible for a page to have PageDirty set, but it is actually | |
762 | * clean (all its buffers are clean). This happens if the | |
763 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 764 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
765 | * try_to_release_page() will discover that cleanness and will |
766 | * drop the buffers and mark the page clean - it can be freed. | |
767 | * | |
768 | * Rarely, pages can have buffers and no ->mapping. These are | |
769 | * the pages which were not successfully invalidated in | |
770 | * truncate_complete_page(). We try to drop those buffers here | |
771 | * and if that worked, and the page is no longer mapped into | |
772 | * process address space (page_count == 1) it can be freed. | |
773 | * Otherwise, leave the page on the LRU so it is swappable. | |
774 | */ | |
266cf658 | 775 | if (page_has_private(page)) { |
1da177e4 LT |
776 | if (!try_to_release_page(page, sc->gfp_mask)) |
777 | goto activate_locked; | |
e286781d NP |
778 | if (!mapping && page_count(page) == 1) { |
779 | unlock_page(page); | |
780 | if (put_page_testzero(page)) | |
781 | goto free_it; | |
782 | else { | |
783 | /* | |
784 | * rare race with speculative reference. | |
785 | * the speculative reference will free | |
786 | * this page shortly, so we may | |
787 | * increment nr_reclaimed here (and | |
788 | * leave it off the LRU). | |
789 | */ | |
790 | nr_reclaimed++; | |
791 | continue; | |
792 | } | |
793 | } | |
1da177e4 LT |
794 | } |
795 | ||
e286781d | 796 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 797 | goto keep_locked; |
1da177e4 | 798 | |
a978d6f5 NP |
799 | /* |
800 | * At this point, we have no other references and there is | |
801 | * no way to pick any more up (removed from LRU, removed | |
802 | * from pagecache). Can use non-atomic bitops now (and | |
803 | * we obviously don't have to worry about waking up a process | |
804 | * waiting on the page lock, because there are no references. | |
805 | */ | |
806 | __clear_page_locked(page); | |
e286781d | 807 | free_it: |
05ff5137 | 808 | nr_reclaimed++; |
e286781d NP |
809 | if (!pagevec_add(&freed_pvec, page)) { |
810 | __pagevec_free(&freed_pvec); | |
811 | pagevec_reinit(&freed_pvec); | |
812 | } | |
1da177e4 LT |
813 | continue; |
814 | ||
b291f000 | 815 | cull_mlocked: |
63d6c5ad HD |
816 | if (PageSwapCache(page)) |
817 | try_to_free_swap(page); | |
b291f000 NP |
818 | unlock_page(page); |
819 | putback_lru_page(page); | |
820 | continue; | |
821 | ||
1da177e4 | 822 | activate_locked: |
68a22394 RR |
823 | /* Not a candidate for swapping, so reclaim swap space. */ |
824 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 825 | try_to_free_swap(page); |
894bc310 | 826 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
827 | SetPageActive(page); |
828 | pgactivate++; | |
829 | keep_locked: | |
830 | unlock_page(page); | |
831 | keep: | |
832 | list_add(&page->lru, &ret_pages); | |
b291f000 | 833 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 LT |
834 | } |
835 | list_splice(&ret_pages, page_list); | |
836 | if (pagevec_count(&freed_pvec)) | |
e286781d | 837 | __pagevec_free(&freed_pvec); |
f8891e5e | 838 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 839 | return nr_reclaimed; |
1da177e4 LT |
840 | } |
841 | ||
5ad333eb AW |
842 | /* |
843 | * Attempt to remove the specified page from its LRU. Only take this page | |
844 | * if it is of the appropriate PageActive status. Pages which are being | |
845 | * freed elsewhere are also ignored. | |
846 | * | |
847 | * page: page to consider | |
848 | * mode: one of the LRU isolation modes defined above | |
849 | * | |
850 | * returns 0 on success, -ve errno on failure. | |
851 | */ | |
4f98a2fe | 852 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
853 | { |
854 | int ret = -EINVAL; | |
855 | ||
856 | /* Only take pages on the LRU. */ | |
857 | if (!PageLRU(page)) | |
858 | return ret; | |
859 | ||
860 | /* | |
861 | * When checking the active state, we need to be sure we are | |
862 | * dealing with comparible boolean values. Take the logical not | |
863 | * of each. | |
864 | */ | |
865 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
866 | return ret; | |
867 | ||
6c0b1351 | 868 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
869 | return ret; |
870 | ||
894bc310 LS |
871 | /* |
872 | * When this function is being called for lumpy reclaim, we | |
873 | * initially look into all LRU pages, active, inactive and | |
874 | * unevictable; only give shrink_page_list evictable pages. | |
875 | */ | |
876 | if (PageUnevictable(page)) | |
877 | return ret; | |
878 | ||
5ad333eb | 879 | ret = -EBUSY; |
08e552c6 | 880 | |
5ad333eb AW |
881 | if (likely(get_page_unless_zero(page))) { |
882 | /* | |
883 | * Be careful not to clear PageLRU until after we're | |
884 | * sure the page is not being freed elsewhere -- the | |
885 | * page release code relies on it. | |
886 | */ | |
887 | ClearPageLRU(page); | |
888 | ret = 0; | |
889 | } | |
890 | ||
891 | return ret; | |
892 | } | |
893 | ||
1da177e4 LT |
894 | /* |
895 | * zone->lru_lock is heavily contended. Some of the functions that | |
896 | * shrink the lists perform better by taking out a batch of pages | |
897 | * and working on them outside the LRU lock. | |
898 | * | |
899 | * For pagecache intensive workloads, this function is the hottest | |
900 | * spot in the kernel (apart from copy_*_user functions). | |
901 | * | |
902 | * Appropriate locks must be held before calling this function. | |
903 | * | |
904 | * @nr_to_scan: The number of pages to look through on the list. | |
905 | * @src: The LRU list to pull pages off. | |
906 | * @dst: The temp list to put pages on to. | |
907 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
908 | * @order: The caller's attempted allocation order |
909 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 910 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
911 | * |
912 | * returns how many pages were moved onto *@dst. | |
913 | */ | |
69e05944 AM |
914 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
915 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 916 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 917 | { |
69e05944 | 918 | unsigned long nr_taken = 0; |
c9b02d97 | 919 | unsigned long scan; |
1da177e4 | 920 | |
c9b02d97 | 921 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
922 | struct page *page; |
923 | unsigned long pfn; | |
924 | unsigned long end_pfn; | |
925 | unsigned long page_pfn; | |
926 | int zone_id; | |
927 | ||
1da177e4 LT |
928 | page = lru_to_page(src); |
929 | prefetchw_prev_lru_page(page, src, flags); | |
930 | ||
725d704e | 931 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 932 | |
4f98a2fe | 933 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
934 | case 0: |
935 | list_move(&page->lru, dst); | |
2ffebca6 | 936 | mem_cgroup_del_lru(page); |
7c8ee9a8 | 937 | nr_taken++; |
5ad333eb AW |
938 | break; |
939 | ||
940 | case -EBUSY: | |
941 | /* else it is being freed elsewhere */ | |
942 | list_move(&page->lru, src); | |
2ffebca6 | 943 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 944 | continue; |
46453a6e | 945 | |
5ad333eb AW |
946 | default: |
947 | BUG(); | |
948 | } | |
949 | ||
950 | if (!order) | |
951 | continue; | |
952 | ||
953 | /* | |
954 | * Attempt to take all pages in the order aligned region | |
955 | * surrounding the tag page. Only take those pages of | |
956 | * the same active state as that tag page. We may safely | |
957 | * round the target page pfn down to the requested order | |
958 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
959 | * where that page is in a different zone we will detect | |
960 | * it from its zone id and abort this block scan. | |
961 | */ | |
962 | zone_id = page_zone_id(page); | |
963 | page_pfn = page_to_pfn(page); | |
964 | pfn = page_pfn & ~((1 << order) - 1); | |
965 | end_pfn = pfn + (1 << order); | |
966 | for (; pfn < end_pfn; pfn++) { | |
967 | struct page *cursor_page; | |
968 | ||
969 | /* The target page is in the block, ignore it. */ | |
970 | if (unlikely(pfn == page_pfn)) | |
971 | continue; | |
972 | ||
973 | /* Avoid holes within the zone. */ | |
974 | if (unlikely(!pfn_valid_within(pfn))) | |
975 | break; | |
976 | ||
977 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 978 | |
5ad333eb AW |
979 | /* Check that we have not crossed a zone boundary. */ |
980 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
981 | continue; | |
de2e7567 MK |
982 | |
983 | /* | |
984 | * If we don't have enough swap space, reclaiming of | |
985 | * anon page which don't already have a swap slot is | |
986 | * pointless. | |
987 | */ | |
988 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
989 | !PageSwapCache(cursor_page)) | |
990 | continue; | |
991 | ||
ee993b13 | 992 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 993 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 994 | mem_cgroup_del_lru(cursor_page); |
5ad333eb AW |
995 | nr_taken++; |
996 | scan++; | |
5ad333eb AW |
997 | } |
998 | } | |
1da177e4 LT |
999 | } |
1000 | ||
1001 | *scanned = scan; | |
1002 | return nr_taken; | |
1003 | } | |
1004 | ||
66e1707b BS |
1005 | static unsigned long isolate_pages_global(unsigned long nr, |
1006 | struct list_head *dst, | |
1007 | unsigned long *scanned, int order, | |
1008 | int mode, struct zone *z, | |
4f98a2fe | 1009 | int active, int file) |
66e1707b | 1010 | { |
4f98a2fe | 1011 | int lru = LRU_BASE; |
66e1707b | 1012 | if (active) |
4f98a2fe RR |
1013 | lru += LRU_ACTIVE; |
1014 | if (file) | |
1015 | lru += LRU_FILE; | |
1016 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1017 | mode, file); |
66e1707b BS |
1018 | } |
1019 | ||
5ad333eb AW |
1020 | /* |
1021 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1022 | * any active bits from the pages in the list. | |
1023 | */ | |
4f98a2fe RR |
1024 | static unsigned long clear_active_flags(struct list_head *page_list, |
1025 | unsigned int *count) | |
5ad333eb AW |
1026 | { |
1027 | int nr_active = 0; | |
4f98a2fe | 1028 | int lru; |
5ad333eb AW |
1029 | struct page *page; |
1030 | ||
4f98a2fe | 1031 | list_for_each_entry(page, page_list, lru) { |
401a8e1c | 1032 | lru = page_lru_base_type(page); |
5ad333eb | 1033 | if (PageActive(page)) { |
4f98a2fe | 1034 | lru += LRU_ACTIVE; |
5ad333eb AW |
1035 | ClearPageActive(page); |
1036 | nr_active++; | |
1037 | } | |
4f98a2fe RR |
1038 | count[lru]++; |
1039 | } | |
5ad333eb AW |
1040 | |
1041 | return nr_active; | |
1042 | } | |
1043 | ||
62695a84 NP |
1044 | /** |
1045 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1046 | * @page: page to isolate from its LRU list | |
1047 | * | |
1048 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1049 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1050 | * | |
1051 | * Returns 0 if the page was removed from an LRU list. | |
1052 | * Returns -EBUSY if the page was not on an LRU list. | |
1053 | * | |
1054 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1055 | * the active list, it will have PageActive set. If it was found on |
1056 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1057 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1058 | * |
1059 | * The vmstat statistic corresponding to the list on which the page was | |
1060 | * found will be decremented. | |
1061 | * | |
1062 | * Restrictions: | |
1063 | * (1) Must be called with an elevated refcount on the page. This is a | |
1064 | * fundamentnal difference from isolate_lru_pages (which is called | |
1065 | * without a stable reference). | |
1066 | * (2) the lru_lock must not be held. | |
1067 | * (3) interrupts must be enabled. | |
1068 | */ | |
1069 | int isolate_lru_page(struct page *page) | |
1070 | { | |
1071 | int ret = -EBUSY; | |
1072 | ||
1073 | if (PageLRU(page)) { | |
1074 | struct zone *zone = page_zone(page); | |
1075 | ||
1076 | spin_lock_irq(&zone->lru_lock); | |
1077 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1078 | int lru = page_lru(page); |
62695a84 NP |
1079 | ret = 0; |
1080 | ClearPageLRU(page); | |
4f98a2fe | 1081 | |
4f98a2fe | 1082 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1083 | } |
1084 | spin_unlock_irq(&zone->lru_lock); | |
1085 | } | |
1086 | return ret; | |
1087 | } | |
1088 | ||
35cd7815 RR |
1089 | /* |
1090 | * Are there way too many processes in the direct reclaim path already? | |
1091 | */ | |
1092 | static int too_many_isolated(struct zone *zone, int file, | |
1093 | struct scan_control *sc) | |
1094 | { | |
1095 | unsigned long inactive, isolated; | |
1096 | ||
1097 | if (current_is_kswapd()) | |
1098 | return 0; | |
1099 | ||
1100 | if (!scanning_global_lru(sc)) | |
1101 | return 0; | |
1102 | ||
1103 | if (file) { | |
1104 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1105 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1106 | } else { | |
1107 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1108 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1109 | } | |
1110 | ||
1111 | return isolated > inactive; | |
1112 | } | |
1113 | ||
1da177e4 | 1114 | /* |
1742f19f AM |
1115 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1116 | * of reclaimed pages | |
1da177e4 | 1117 | */ |
1742f19f | 1118 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
33c120ed RR |
1119 | struct zone *zone, struct scan_control *sc, |
1120 | int priority, int file) | |
1da177e4 LT |
1121 | { |
1122 | LIST_HEAD(page_list); | |
1123 | struct pagevec pvec; | |
69e05944 | 1124 | unsigned long nr_scanned = 0; |
05ff5137 | 1125 | unsigned long nr_reclaimed = 0; |
6e901571 | 1126 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
78dc583d | 1127 | |
35cd7815 | 1128 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1129 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1130 | |
1131 | /* We are about to die and free our memory. Return now. */ | |
1132 | if (fatal_signal_pending(current)) | |
1133 | return SWAP_CLUSTER_MAX; | |
1134 | } | |
1135 | ||
1da177e4 LT |
1136 | |
1137 | pagevec_init(&pvec, 1); | |
1138 | ||
1139 | lru_add_drain(); | |
1140 | spin_lock_irq(&zone->lru_lock); | |
69e05944 | 1141 | do { |
1da177e4 | 1142 | struct page *page; |
69e05944 AM |
1143 | unsigned long nr_taken; |
1144 | unsigned long nr_scan; | |
1145 | unsigned long nr_freed; | |
5ad333eb | 1146 | unsigned long nr_active; |
4f98a2fe | 1147 | unsigned int count[NR_LRU_LISTS] = { 0, }; |
5f53e762 | 1148 | int mode = sc->lumpy_reclaim_mode ? ISOLATE_BOTH : ISOLATE_INACTIVE; |
a731286d KM |
1149 | unsigned long nr_anon; |
1150 | unsigned long nr_file; | |
1da177e4 | 1151 | |
b35ea17b | 1152 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1153 | nr_taken = isolate_pages_global(SWAP_CLUSTER_MAX, |
1154 | &page_list, &nr_scan, | |
1155 | sc->order, mode, | |
1156 | zone, 0, file); | |
b35ea17b KM |
1157 | zone->pages_scanned += nr_scan; |
1158 | if (current_is_kswapd()) | |
1159 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1160 | nr_scan); | |
1161 | else | |
1162 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1163 | nr_scan); | |
8b25c6d2 JW |
1164 | } else { |
1165 | nr_taken = mem_cgroup_isolate_pages(SWAP_CLUSTER_MAX, | |
1166 | &page_list, &nr_scan, | |
1167 | sc->order, mode, | |
1168 | zone, sc->mem_cgroup, | |
1169 | 0, file); | |
1170 | /* | |
1171 | * mem_cgroup_isolate_pages() keeps track of | |
1172 | * scanned pages on its own. | |
1173 | */ | |
b35ea17b KM |
1174 | } |
1175 | ||
1176 | if (nr_taken == 0) | |
1177 | goto done; | |
1178 | ||
4f98a2fe | 1179 | nr_active = clear_active_flags(&page_list, count); |
e9187bdc | 1180 | __count_vm_events(PGDEACTIVATE, nr_active); |
5ad333eb | 1181 | |
4f98a2fe RR |
1182 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1183 | -count[LRU_ACTIVE_FILE]); | |
1184 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1185 | -count[LRU_INACTIVE_FILE]); | |
1186 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1187 | -count[LRU_ACTIVE_ANON]); | |
1188 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1189 | -count[LRU_INACTIVE_ANON]); | |
1190 | ||
a731286d KM |
1191 | nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; |
1192 | nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1193 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon); | |
1194 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file); | |
3e2f41f1 | 1195 | |
62c0c2f1 HS |
1196 | reclaim_stat->recent_scanned[0] += nr_anon; |
1197 | reclaim_stat->recent_scanned[1] += nr_file; | |
3e2f41f1 | 1198 | |
1da177e4 LT |
1199 | spin_unlock_irq(&zone->lru_lock); |
1200 | ||
69e05944 | 1201 | nr_scanned += nr_scan; |
c661b078 AW |
1202 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
1203 | ||
1204 | /* | |
1205 | * If we are direct reclaiming for contiguous pages and we do | |
1206 | * not reclaim everything in the list, try again and wait | |
1207 | * for IO to complete. This will stall high-order allocations | |
1208 | * but that should be acceptable to the caller | |
1209 | */ | |
1210 | if (nr_freed < nr_taken && !current_is_kswapd() && | |
5f53e762 | 1211 | sc->lumpy_reclaim_mode) { |
8aa7e847 | 1212 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
c661b078 AW |
1213 | |
1214 | /* | |
1215 | * The attempt at page out may have made some | |
1216 | * of the pages active, mark them inactive again. | |
1217 | */ | |
4f98a2fe | 1218 | nr_active = clear_active_flags(&page_list, count); |
c661b078 AW |
1219 | count_vm_events(PGDEACTIVATE, nr_active); |
1220 | ||
1221 | nr_freed += shrink_page_list(&page_list, sc, | |
1222 | PAGEOUT_IO_SYNC); | |
1223 | } | |
1224 | ||
05ff5137 | 1225 | nr_reclaimed += nr_freed; |
b35ea17b | 1226 | |
a74609fa | 1227 | local_irq_disable(); |
b35ea17b | 1228 | if (current_is_kswapd()) |
f8891e5e | 1229 | __count_vm_events(KSWAPD_STEAL, nr_freed); |
918d3f90 | 1230 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
a74609fa NP |
1231 | |
1232 | spin_lock(&zone->lru_lock); | |
1da177e4 LT |
1233 | /* |
1234 | * Put back any unfreeable pages. | |
1235 | */ | |
1236 | while (!list_empty(&page_list)) { | |
894bc310 | 1237 | int lru; |
1da177e4 | 1238 | page = lru_to_page(&page_list); |
725d704e | 1239 | VM_BUG_ON(PageLRU(page)); |
1da177e4 | 1240 | list_del(&page->lru); |
894bc310 LS |
1241 | if (unlikely(!page_evictable(page, NULL))) { |
1242 | spin_unlock_irq(&zone->lru_lock); | |
1243 | putback_lru_page(page); | |
1244 | spin_lock_irq(&zone->lru_lock); | |
1245 | continue; | |
1246 | } | |
1247 | SetPageLRU(page); | |
1248 | lru = page_lru(page); | |
1249 | add_page_to_lru_list(zone, page, lru); | |
74a1c48f | 1250 | if (is_active_lru(lru)) { |
b7c46d15 | 1251 | int file = is_file_lru(lru); |
6e901571 | 1252 | reclaim_stat->recent_rotated[file]++; |
4f98a2fe | 1253 | } |
1da177e4 LT |
1254 | if (!pagevec_add(&pvec, page)) { |
1255 | spin_unlock_irq(&zone->lru_lock); | |
1256 | __pagevec_release(&pvec); | |
1257 | spin_lock_irq(&zone->lru_lock); | |
1258 | } | |
1259 | } | |
a731286d KM |
1260 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); |
1261 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1262 | ||
69e05944 | 1263 | } while (nr_scanned < max_scan); |
b35ea17b | 1264 | |
1da177e4 | 1265 | done: |
b35ea17b | 1266 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 | 1267 | pagevec_release(&pvec); |
05ff5137 | 1268 | return nr_reclaimed; |
1da177e4 LT |
1269 | } |
1270 | ||
3bb1a852 MB |
1271 | /* |
1272 | * We are about to scan this zone at a certain priority level. If that priority | |
1273 | * level is smaller (ie: more urgent) than the previous priority, then note | |
1274 | * that priority level within the zone. This is done so that when the next | |
1275 | * process comes in to scan this zone, it will immediately start out at this | |
1276 | * priority level rather than having to build up its own scanning priority. | |
1277 | * Here, this priority affects only the reclaim-mapped threshold. | |
1278 | */ | |
1279 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) | |
1280 | { | |
1281 | if (priority < zone->prev_priority) | |
1282 | zone->prev_priority = priority; | |
1283 | } | |
1284 | ||
1da177e4 LT |
1285 | /* |
1286 | * This moves pages from the active list to the inactive list. | |
1287 | * | |
1288 | * We move them the other way if the page is referenced by one or more | |
1289 | * processes, from rmap. | |
1290 | * | |
1291 | * If the pages are mostly unmapped, the processing is fast and it is | |
1292 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1293 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1294 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1295 | * this, so instead we remove the pages from the LRU while processing them. | |
1296 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1297 | * nobody will play with that bit on a non-LRU page. | |
1298 | * | |
1299 | * The downside is that we have to touch page->_count against each page. | |
1300 | * But we had to alter page->flags anyway. | |
1301 | */ | |
1cfb419b | 1302 | |
3eb4140f WF |
1303 | static void move_active_pages_to_lru(struct zone *zone, |
1304 | struct list_head *list, | |
1305 | enum lru_list lru) | |
1306 | { | |
1307 | unsigned long pgmoved = 0; | |
1308 | struct pagevec pvec; | |
1309 | struct page *page; | |
1310 | ||
1311 | pagevec_init(&pvec, 1); | |
1312 | ||
1313 | while (!list_empty(list)) { | |
1314 | page = lru_to_page(list); | |
3eb4140f WF |
1315 | |
1316 | VM_BUG_ON(PageLRU(page)); | |
1317 | SetPageLRU(page); | |
1318 | ||
3eb4140f WF |
1319 | list_move(&page->lru, &zone->lru[lru].list); |
1320 | mem_cgroup_add_lru_list(page, lru); | |
1321 | pgmoved++; | |
1322 | ||
1323 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1324 | spin_unlock_irq(&zone->lru_lock); | |
1325 | if (buffer_heads_over_limit) | |
1326 | pagevec_strip(&pvec); | |
1327 | __pagevec_release(&pvec); | |
1328 | spin_lock_irq(&zone->lru_lock); | |
1329 | } | |
1330 | } | |
1331 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1332 | if (!is_active_lru(lru)) | |
1333 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1334 | } | |
1cfb419b | 1335 | |
1742f19f | 1336 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1337 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1338 | { |
44c241f1 | 1339 | unsigned long nr_taken; |
69e05944 | 1340 | unsigned long pgscanned; |
6fe6b7e3 | 1341 | unsigned long vm_flags; |
1da177e4 | 1342 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1343 | LIST_HEAD(l_active); |
b69408e8 | 1344 | LIST_HEAD(l_inactive); |
1da177e4 | 1345 | struct page *page; |
6e901571 | 1346 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1347 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1348 | |
1349 | lru_add_drain(); | |
1350 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1351 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1352 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1353 | &pgscanned, sc->order, | |
1354 | ISOLATE_ACTIVE, zone, | |
1355 | 1, file); | |
1cfb419b | 1356 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1357 | } else { |
1358 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1359 | &pgscanned, sc->order, | |
1360 | ISOLATE_ACTIVE, zone, | |
1361 | sc->mem_cgroup, 1, file); | |
1362 | /* | |
1363 | * mem_cgroup_isolate_pages() keeps track of | |
1364 | * scanned pages on its own. | |
1365 | */ | |
4f98a2fe | 1366 | } |
8b25c6d2 | 1367 | |
b7c46d15 | 1368 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1369 | |
3eb4140f | 1370 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1371 | if (file) |
44c241f1 | 1372 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1373 | else |
44c241f1 | 1374 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1375 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1376 | spin_unlock_irq(&zone->lru_lock); |
1377 | ||
1da177e4 LT |
1378 | while (!list_empty(&l_hold)) { |
1379 | cond_resched(); | |
1380 | page = lru_to_page(&l_hold); | |
1381 | list_del(&page->lru); | |
7e9cd484 | 1382 | |
894bc310 LS |
1383 | if (unlikely(!page_evictable(page, NULL))) { |
1384 | putback_lru_page(page); | |
1385 | continue; | |
1386 | } | |
1387 | ||
64574746 | 1388 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
44c241f1 | 1389 | nr_rotated++; |
8cab4754 WF |
1390 | /* |
1391 | * Identify referenced, file-backed active pages and | |
1392 | * give them one more trip around the active list. So | |
1393 | * that executable code get better chances to stay in | |
1394 | * memory under moderate memory pressure. Anon pages | |
1395 | * are not likely to be evicted by use-once streaming | |
1396 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1397 | * so we ignore them here. | |
1398 | */ | |
41e20983 | 1399 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1400 | list_add(&page->lru, &l_active); |
1401 | continue; | |
1402 | } | |
1403 | } | |
7e9cd484 | 1404 | |
5205e56e | 1405 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1406 | list_add(&page->lru, &l_inactive); |
1407 | } | |
1408 | ||
b555749a | 1409 | /* |
8cab4754 | 1410 | * Move pages back to the lru list. |
b555749a | 1411 | */ |
2a1dc509 | 1412 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1413 | /* |
8cab4754 WF |
1414 | * Count referenced pages from currently used mappings as rotated, |
1415 | * even though only some of them are actually re-activated. This | |
1416 | * helps balance scan pressure between file and anonymous pages in | |
1417 | * get_scan_ratio. | |
7e9cd484 | 1418 | */ |
b7c46d15 | 1419 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1420 | |
3eb4140f WF |
1421 | move_active_pages_to_lru(zone, &l_active, |
1422 | LRU_ACTIVE + file * LRU_FILE); | |
1423 | move_active_pages_to_lru(zone, &l_inactive, | |
1424 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1425 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1426 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1427 | } |
1428 | ||
14797e23 | 1429 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1430 | { |
1431 | unsigned long active, inactive; | |
1432 | ||
1433 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1434 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1435 | ||
1436 | if (inactive * zone->inactive_ratio < active) | |
1437 | return 1; | |
1438 | ||
1439 | return 0; | |
1440 | } | |
1441 | ||
14797e23 KM |
1442 | /** |
1443 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1444 | * @zone: zone to check | |
1445 | * @sc: scan control of this context | |
1446 | * | |
1447 | * Returns true if the zone does not have enough inactive anon pages, | |
1448 | * meaning some active anon pages need to be deactivated. | |
1449 | */ | |
1450 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1451 | { | |
1452 | int low; | |
1453 | ||
e72e2bd6 | 1454 | if (scanning_global_lru(sc)) |
14797e23 KM |
1455 | low = inactive_anon_is_low_global(zone); |
1456 | else | |
c772be93 | 1457 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1458 | return low; |
1459 | } | |
1460 | ||
56e49d21 RR |
1461 | static int inactive_file_is_low_global(struct zone *zone) |
1462 | { | |
1463 | unsigned long active, inactive; | |
1464 | ||
1465 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1466 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1467 | ||
1468 | return (active > inactive); | |
1469 | } | |
1470 | ||
1471 | /** | |
1472 | * inactive_file_is_low - check if file pages need to be deactivated | |
1473 | * @zone: zone to check | |
1474 | * @sc: scan control of this context | |
1475 | * | |
1476 | * When the system is doing streaming IO, memory pressure here | |
1477 | * ensures that active file pages get deactivated, until more | |
1478 | * than half of the file pages are on the inactive list. | |
1479 | * | |
1480 | * Once we get to that situation, protect the system's working | |
1481 | * set from being evicted by disabling active file page aging. | |
1482 | * | |
1483 | * This uses a different ratio than the anonymous pages, because | |
1484 | * the page cache uses a use-once replacement algorithm. | |
1485 | */ | |
1486 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1487 | { | |
1488 | int low; | |
1489 | ||
1490 | if (scanning_global_lru(sc)) | |
1491 | low = inactive_file_is_low_global(zone); | |
1492 | else | |
1493 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1494 | return low; | |
1495 | } | |
1496 | ||
b39415b2 RR |
1497 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1498 | int file) | |
1499 | { | |
1500 | if (file) | |
1501 | return inactive_file_is_low(zone, sc); | |
1502 | else | |
1503 | return inactive_anon_is_low(zone, sc); | |
1504 | } | |
1505 | ||
4f98a2fe | 1506 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1507 | struct zone *zone, struct scan_control *sc, int priority) |
1508 | { | |
4f98a2fe RR |
1509 | int file = is_file_lru(lru); |
1510 | ||
b39415b2 RR |
1511 | if (is_active_lru(lru)) { |
1512 | if (inactive_list_is_low(zone, sc, file)) | |
1513 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1514 | return 0; |
1515 | } | |
1516 | ||
33c120ed | 1517 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1518 | } |
1519 | ||
76a33fc3 SL |
1520 | /* |
1521 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1522 | * until we collected @swap_cluster_max pages to scan. | |
1523 | */ | |
1524 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1525 | unsigned long *nr_saved_scan) | |
1526 | { | |
1527 | unsigned long nr; | |
1528 | ||
1529 | *nr_saved_scan += nr_to_scan; | |
1530 | nr = *nr_saved_scan; | |
1531 | ||
1532 | if (nr >= SWAP_CLUSTER_MAX) | |
1533 | *nr_saved_scan = 0; | |
1534 | else | |
1535 | nr = 0; | |
1536 | ||
1537 | return nr; | |
1538 | } | |
1539 | ||
4f98a2fe RR |
1540 | /* |
1541 | * Determine how aggressively the anon and file LRU lists should be | |
1542 | * scanned. The relative value of each set of LRU lists is determined | |
1543 | * by looking at the fraction of the pages scanned we did rotate back | |
1544 | * onto the active list instead of evict. | |
1545 | * | |
76a33fc3 | 1546 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1547 | */ |
76a33fc3 SL |
1548 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1549 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1550 | { |
1551 | unsigned long anon, file, free; | |
1552 | unsigned long anon_prio, file_prio; | |
1553 | unsigned long ap, fp; | |
6e901571 | 1554 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1555 | u64 fraction[2], denominator; |
1556 | enum lru_list l; | |
1557 | int noswap = 0; | |
1558 | ||
1559 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1560 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1561 | noswap = 1; | |
1562 | fraction[0] = 0; | |
1563 | fraction[1] = 1; | |
1564 | denominator = 1; | |
1565 | goto out; | |
1566 | } | |
4f98a2fe | 1567 | |
0b217676 VL |
1568 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1569 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1570 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1571 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1572 | |
e72e2bd6 | 1573 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1574 | free = zone_page_state(zone, NR_FREE_PAGES); |
1575 | /* If we have very few page cache pages, | |
1576 | force-scan anon pages. */ | |
41858966 | 1577 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1578 | fraction[0] = 1; |
1579 | fraction[1] = 0; | |
1580 | denominator = 1; | |
1581 | goto out; | |
eeee9a8c | 1582 | } |
4f98a2fe RR |
1583 | } |
1584 | ||
1585 | /* | |
1586 | * OK, so we have swap space and a fair amount of page cache | |
1587 | * pages. We use the recently rotated / recently scanned | |
1588 | * ratios to determine how valuable each cache is. | |
1589 | * | |
1590 | * Because workloads change over time (and to avoid overflow) | |
1591 | * we keep these statistics as a floating average, which ends | |
1592 | * up weighing recent references more than old ones. | |
1593 | * | |
1594 | * anon in [0], file in [1] | |
1595 | */ | |
6e901571 | 1596 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
4f98a2fe | 1597 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1598 | reclaim_stat->recent_scanned[0] /= 2; |
1599 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1600 | spin_unlock_irq(&zone->lru_lock); |
1601 | } | |
1602 | ||
6e901571 | 1603 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
4f98a2fe | 1604 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1605 | reclaim_stat->recent_scanned[1] /= 2; |
1606 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1607 | spin_unlock_irq(&zone->lru_lock); |
1608 | } | |
1609 | ||
1610 | /* | |
1611 | * With swappiness at 100, anonymous and file have the same priority. | |
1612 | * This scanning priority is essentially the inverse of IO cost. | |
1613 | */ | |
1614 | anon_prio = sc->swappiness; | |
1615 | file_prio = 200 - sc->swappiness; | |
1616 | ||
1617 | /* | |
00d8089c RR |
1618 | * The amount of pressure on anon vs file pages is inversely |
1619 | * proportional to the fraction of recently scanned pages on | |
1620 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1621 | */ |
6e901571 KM |
1622 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1623 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1624 | |
6e901571 KM |
1625 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1626 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
4f98a2fe | 1627 | |
76a33fc3 SL |
1628 | fraction[0] = ap; |
1629 | fraction[1] = fp; | |
1630 | denominator = ap + fp + 1; | |
1631 | out: | |
1632 | for_each_evictable_lru(l) { | |
1633 | int file = is_file_lru(l); | |
1634 | unsigned long scan; | |
6e08a369 | 1635 | |
76a33fc3 SL |
1636 | scan = zone_nr_lru_pages(zone, sc, l); |
1637 | if (priority || noswap) { | |
1638 | scan >>= priority; | |
1639 | scan = div64_u64(scan * fraction[file], denominator); | |
1640 | } | |
1641 | nr[l] = nr_scan_try_batch(scan, | |
1642 | &reclaim_stat->nr_saved_scan[l]); | |
1643 | } | |
6e08a369 | 1644 | } |
4f98a2fe | 1645 | |
5f53e762 KM |
1646 | static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc) |
1647 | { | |
1648 | /* | |
1649 | * If we need a large contiguous chunk of memory, or have | |
1650 | * trouble getting a small set of contiguous pages, we | |
1651 | * will reclaim both active and inactive pages. | |
1652 | */ | |
1653 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1654 | sc->lumpy_reclaim_mode = 1; | |
1655 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1656 | sc->lumpy_reclaim_mode = 1; | |
1657 | else | |
1658 | sc->lumpy_reclaim_mode = 0; | |
1659 | } | |
1660 | ||
1da177e4 LT |
1661 | /* |
1662 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1663 | */ | |
a79311c1 | 1664 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1665 | struct scan_control *sc) |
1da177e4 | 1666 | { |
b69408e8 | 1667 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1668 | unsigned long nr_to_scan; |
b69408e8 | 1669 | enum lru_list l; |
01dbe5c9 | 1670 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
22fba335 | 1671 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1672 | |
76a33fc3 | 1673 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1674 | |
5f53e762 KM |
1675 | set_lumpy_reclaim_mode(priority, sc); |
1676 | ||
556adecb RR |
1677 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1678 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1679 | for_each_evictable_lru(l) { |
b69408e8 | 1680 | if (nr[l]) { |
ece74b2e KM |
1681 | nr_to_scan = min_t(unsigned long, |
1682 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1683 | nr[l] -= nr_to_scan; |
1da177e4 | 1684 | |
01dbe5c9 KM |
1685 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1686 | zone, sc, priority); | |
b69408e8 | 1687 | } |
1da177e4 | 1688 | } |
a79311c1 RR |
1689 | /* |
1690 | * On large memory systems, scan >> priority can become | |
1691 | * really large. This is fine for the starting priority; | |
1692 | * we want to put equal scanning pressure on each zone. | |
1693 | * However, if the VM has a harder time of freeing pages, | |
1694 | * with multiple processes reclaiming pages, the total | |
1695 | * freeing target can get unreasonably large. | |
1696 | */ | |
338fde90 | 1697 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1698 | break; |
1da177e4 LT |
1699 | } |
1700 | ||
01dbe5c9 KM |
1701 | sc->nr_reclaimed = nr_reclaimed; |
1702 | ||
556adecb RR |
1703 | /* |
1704 | * Even if we did not try to evict anon pages at all, we want to | |
1705 | * rebalance the anon lru active/inactive ratio. | |
1706 | */ | |
69c85481 | 1707 | if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) |
556adecb RR |
1708 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1709 | ||
232ea4d6 | 1710 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1711 | } |
1712 | ||
1713 | /* | |
1714 | * This is the direct reclaim path, for page-allocating processes. We only | |
1715 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1716 | * request. | |
1717 | * | |
41858966 MG |
1718 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1719 | * Because: | |
1da177e4 LT |
1720 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1721 | * allocation or | |
41858966 MG |
1722 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1723 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1724 | * zone defense algorithm. | |
1da177e4 | 1725 | * |
1da177e4 LT |
1726 | * If a zone is deemed to be full of pinned pages then just give it a light |
1727 | * scan then give up on it. | |
1728 | */ | |
bb21c7ce | 1729 | static bool shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1730 | struct scan_control *sc) |
1da177e4 | 1731 | { |
54a6eb5c | 1732 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
dd1a239f | 1733 | struct zoneref *z; |
54a6eb5c | 1734 | struct zone *zone; |
bb21c7ce | 1735 | bool all_unreclaimable = true; |
1cfb419b | 1736 | |
327c0e96 KH |
1737 | for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, |
1738 | sc->nodemask) { | |
f3fe6512 | 1739 | if (!populated_zone(zone)) |
1da177e4 | 1740 | continue; |
1cfb419b KH |
1741 | /* |
1742 | * Take care memory controller reclaiming has small influence | |
1743 | * to global LRU. | |
1744 | */ | |
e72e2bd6 | 1745 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1746 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1747 | continue; | |
1748 | note_zone_scanning_priority(zone, priority); | |
1da177e4 | 1749 | |
93e4a89a | 1750 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1751 | continue; /* Let kswapd poll it */ |
1cfb419b KH |
1752 | } else { |
1753 | /* | |
1754 | * Ignore cpuset limitation here. We just want to reduce | |
1755 | * # of used pages by us regardless of memory shortage. | |
1756 | */ | |
1cfb419b KH |
1757 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, |
1758 | priority); | |
1759 | } | |
408d8544 | 1760 | |
a79311c1 | 1761 | shrink_zone(priority, zone, sc); |
bb21c7ce | 1762 | all_unreclaimable = false; |
1da177e4 | 1763 | } |
bb21c7ce | 1764 | return all_unreclaimable; |
1da177e4 | 1765 | } |
4f98a2fe | 1766 | |
1da177e4 LT |
1767 | /* |
1768 | * This is the main entry point to direct page reclaim. | |
1769 | * | |
1770 | * If a full scan of the inactive list fails to free enough memory then we | |
1771 | * are "out of memory" and something needs to be killed. | |
1772 | * | |
1773 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1774 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
1775 | * caller can't do much about. We kick the writeback threads and take explicit |
1776 | * naps in the hope that some of these pages can be written. But if the | |
1777 | * allocating task holds filesystem locks which prevent writeout this might not | |
1778 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
1779 | * |
1780 | * returns: 0, if no pages reclaimed | |
1781 | * else, the number of pages reclaimed | |
1da177e4 | 1782 | */ |
dac1d27b | 1783 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1784 | struct scan_control *sc) |
1da177e4 LT |
1785 | { |
1786 | int priority; | |
bb21c7ce | 1787 | bool all_unreclaimable; |
69e05944 | 1788 | unsigned long total_scanned = 0; |
1da177e4 | 1789 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1da177e4 | 1790 | unsigned long lru_pages = 0; |
dd1a239f | 1791 | struct zoneref *z; |
54a6eb5c | 1792 | struct zone *zone; |
dd1a239f | 1793 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
22fba335 | 1794 | unsigned long writeback_threshold; |
1da177e4 | 1795 | |
c0ff7453 | 1796 | get_mems_allowed(); |
873b4771 KK |
1797 | delayacct_freepages_start(); |
1798 | ||
e72e2bd6 | 1799 | if (scanning_global_lru(sc)) |
1cfb419b KH |
1800 | count_vm_event(ALLOCSTALL); |
1801 | /* | |
1802 | * mem_cgroup will not do shrink_slab. | |
1803 | */ | |
e72e2bd6 | 1804 | if (scanning_global_lru(sc)) { |
54a6eb5c | 1805 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1da177e4 | 1806 | |
1cfb419b KH |
1807 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1808 | continue; | |
1da177e4 | 1809 | |
adea02a1 | 1810 | lru_pages += zone_reclaimable_pages(zone); |
1cfb419b | 1811 | } |
1da177e4 LT |
1812 | } |
1813 | ||
1814 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1815 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1816 | if (!priority) |
1817 | disable_swap_token(); | |
bb21c7ce | 1818 | all_unreclaimable = shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1819 | /* |
1820 | * Don't shrink slabs when reclaiming memory from | |
1821 | * over limit cgroups | |
1822 | */ | |
e72e2bd6 | 1823 | if (scanning_global_lru(sc)) { |
dd1a239f | 1824 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1825 | if (reclaim_state) { |
a79311c1 | 1826 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1827 | reclaim_state->reclaimed_slab = 0; |
1828 | } | |
1da177e4 | 1829 | } |
66e1707b | 1830 | total_scanned += sc->nr_scanned; |
bb21c7ce | 1831 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 1832 | goto out; |
1da177e4 LT |
1833 | |
1834 | /* | |
1835 | * Try to write back as many pages as we just scanned. This | |
1836 | * tends to cause slow streaming writers to write data to the | |
1837 | * disk smoothly, at the dirtying rate, which is nice. But | |
1838 | * that's undesirable in laptop mode, where we *want* lumpy | |
1839 | * writeout. So in laptop mode, write out the whole world. | |
1840 | */ | |
22fba335 KM |
1841 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
1842 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 1843 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 1844 | sc->may_writepage = 1; |
1da177e4 LT |
1845 | } |
1846 | ||
1847 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c KM |
1848 | if (!sc->hibernation_mode && sc->nr_scanned && |
1849 | priority < DEF_PRIORITY - 2) | |
8aa7e847 | 1850 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1da177e4 | 1851 | } |
bb21c7ce | 1852 | |
1da177e4 | 1853 | out: |
3bb1a852 MB |
1854 | /* |
1855 | * Now that we've scanned all the zones at this priority level, note | |
1856 | * that level within the zone so that the next thread which performs | |
1857 | * scanning of this zone will immediately start out at this priority | |
1858 | * level. This affects only the decision whether or not to bring | |
1859 | * mapped pages onto the inactive list. | |
1860 | */ | |
1861 | if (priority < 0) | |
1862 | priority = 0; | |
1da177e4 | 1863 | |
e72e2bd6 | 1864 | if (scanning_global_lru(sc)) { |
54a6eb5c | 1865 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1cfb419b KH |
1866 | |
1867 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1868 | continue; | |
1869 | ||
1870 | zone->prev_priority = priority; | |
1871 | } | |
1872 | } else | |
1873 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); | |
1da177e4 | 1874 | |
873b4771 | 1875 | delayacct_freepages_end(); |
c0ff7453 | 1876 | put_mems_allowed(); |
873b4771 | 1877 | |
bb21c7ce KM |
1878 | if (sc->nr_reclaimed) |
1879 | return sc->nr_reclaimed; | |
1880 | ||
1881 | /* top priority shrink_zones still had more to do? don't OOM, then */ | |
1882 | if (scanning_global_lru(sc) && !all_unreclaimable) | |
1883 | return 1; | |
1884 | ||
1885 | return 0; | |
1da177e4 LT |
1886 | } |
1887 | ||
dac1d27b | 1888 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 1889 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b BS |
1890 | { |
1891 | struct scan_control sc = { | |
1892 | .gfp_mask = gfp_mask, | |
1893 | .may_writepage = !laptop_mode, | |
22fba335 | 1894 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 1895 | .may_unmap = 1, |
2e2e4259 | 1896 | .may_swap = 1, |
66e1707b BS |
1897 | .swappiness = vm_swappiness, |
1898 | .order = order, | |
1899 | .mem_cgroup = NULL, | |
327c0e96 | 1900 | .nodemask = nodemask, |
66e1707b BS |
1901 | }; |
1902 | ||
dd1a239f | 1903 | return do_try_to_free_pages(zonelist, &sc); |
66e1707b BS |
1904 | } |
1905 | ||
00f0b825 | 1906 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1907 | |
4e416953 BS |
1908 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
1909 | gfp_t gfp_mask, bool noswap, | |
1910 | unsigned int swappiness, | |
1911 | struct zone *zone, int nid) | |
1912 | { | |
1913 | struct scan_control sc = { | |
1914 | .may_writepage = !laptop_mode, | |
1915 | .may_unmap = 1, | |
1916 | .may_swap = !noswap, | |
4e416953 BS |
1917 | .swappiness = swappiness, |
1918 | .order = 0, | |
1919 | .mem_cgroup = mem, | |
4e416953 BS |
1920 | }; |
1921 | nodemask_t nm = nodemask_of_node(nid); | |
1922 | ||
1923 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | | |
1924 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1925 | sc.nodemask = &nm; | |
1926 | sc.nr_reclaimed = 0; | |
1927 | sc.nr_scanned = 0; | |
1928 | /* | |
1929 | * NOTE: Although we can get the priority field, using it | |
1930 | * here is not a good idea, since it limits the pages we can scan. | |
1931 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
1932 | * will pick up pages from other mem cgroup's as well. We hack | |
1933 | * the priority and make it zero. | |
1934 | */ | |
1935 | shrink_zone(0, zone, &sc); | |
1936 | return sc.nr_reclaimed; | |
1937 | } | |
1938 | ||
e1a1cd59 | 1939 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
1940 | gfp_t gfp_mask, |
1941 | bool noswap, | |
1942 | unsigned int swappiness) | |
66e1707b | 1943 | { |
4e416953 | 1944 | struct zonelist *zonelist; |
66e1707b | 1945 | struct scan_control sc = { |
66e1707b | 1946 | .may_writepage = !laptop_mode, |
a6dc60f8 | 1947 | .may_unmap = 1, |
2e2e4259 | 1948 | .may_swap = !noswap, |
22fba335 | 1949 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 1950 | .swappiness = swappiness, |
66e1707b BS |
1951 | .order = 0, |
1952 | .mem_cgroup = mem_cont, | |
327c0e96 | 1953 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 1954 | }; |
66e1707b | 1955 | |
dd1a239f MG |
1956 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1957 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1958 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1959 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1960 | } |
1961 | #endif | |
1962 | ||
f50de2d3 | 1963 | /* is kswapd sleeping prematurely? */ |
bb3ab596 | 1964 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
f50de2d3 | 1965 | { |
bb3ab596 | 1966 | int i; |
f50de2d3 MG |
1967 | |
1968 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
1969 | if (remaining) | |
1970 | return 1; | |
1971 | ||
1972 | /* If after HZ/10, a zone is below the high mark, it's premature */ | |
bb3ab596 KM |
1973 | for (i = 0; i < pgdat->nr_zones; i++) { |
1974 | struct zone *zone = pgdat->node_zones + i; | |
1975 | ||
1976 | if (!populated_zone(zone)) | |
1977 | continue; | |
1978 | ||
93e4a89a | 1979 | if (zone->all_unreclaimable) |
de3fab39 KM |
1980 | continue; |
1981 | ||
f50de2d3 MG |
1982 | if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), |
1983 | 0, 0)) | |
1984 | return 1; | |
bb3ab596 | 1985 | } |
f50de2d3 MG |
1986 | |
1987 | return 0; | |
1988 | } | |
1989 | ||
1da177e4 LT |
1990 | /* |
1991 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 1992 | * they are all at high_wmark_pages(zone). |
1da177e4 | 1993 | * |
1da177e4 LT |
1994 | * Returns the number of pages which were actually freed. |
1995 | * | |
1996 | * There is special handling here for zones which are full of pinned pages. | |
1997 | * This can happen if the pages are all mlocked, or if they are all used by | |
1998 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1999 | * What we do is to detect the case where all pages in the zone have been | |
2000 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2001 | * dead and from now on, only perform a short scan. Basically we're polling | |
2002 | * the zone for when the problem goes away. | |
2003 | * | |
2004 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2005 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2006 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2007 | * lower zones regardless of the number of free pages in the lower zones. This | |
2008 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2009 | * of pages is balanced across the zones. | |
1da177e4 | 2010 | */ |
d6277db4 | 2011 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 2012 | { |
1da177e4 LT |
2013 | int all_zones_ok; |
2014 | int priority; | |
2015 | int i; | |
69e05944 | 2016 | unsigned long total_scanned; |
1da177e4 | 2017 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2018 | struct scan_control sc = { |
2019 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2020 | .may_unmap = 1, |
2e2e4259 | 2021 | .may_swap = 1, |
22fba335 KM |
2022 | /* |
2023 | * kswapd doesn't want to be bailed out while reclaim. because | |
2024 | * we want to put equal scanning pressure on each zone. | |
2025 | */ | |
2026 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2027 | .swappiness = vm_swappiness, |
5ad333eb | 2028 | .order = order, |
66e1707b | 2029 | .mem_cgroup = NULL, |
179e9639 | 2030 | }; |
3bb1a852 MB |
2031 | /* |
2032 | * temp_priority is used to remember the scanning priority at which | |
41858966 MG |
2033 | * this zone was successfully refilled to |
2034 | * free_pages == high_wmark_pages(zone). | |
3bb1a852 MB |
2035 | */ |
2036 | int temp_priority[MAX_NR_ZONES]; | |
1da177e4 LT |
2037 | |
2038 | loop_again: | |
2039 | total_scanned = 0; | |
a79311c1 | 2040 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2041 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2042 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2043 | |
3bb1a852 MB |
2044 | for (i = 0; i < pgdat->nr_zones; i++) |
2045 | temp_priority[i] = DEF_PRIORITY; | |
1da177e4 LT |
2046 | |
2047 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
2048 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
2049 | unsigned long lru_pages = 0; | |
bb3ab596 | 2050 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2051 | |
f7b7fd8f RR |
2052 | /* The swap token gets in the way of swapout... */ |
2053 | if (!priority) | |
2054 | disable_swap_token(); | |
2055 | ||
1da177e4 LT |
2056 | all_zones_ok = 1; |
2057 | ||
d6277db4 RW |
2058 | /* |
2059 | * Scan in the highmem->dma direction for the highest | |
2060 | * zone which needs scanning | |
2061 | */ | |
2062 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2063 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2064 | |
d6277db4 RW |
2065 | if (!populated_zone(zone)) |
2066 | continue; | |
1da177e4 | 2067 | |
93e4a89a | 2068 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2069 | continue; |
1da177e4 | 2070 | |
556adecb RR |
2071 | /* |
2072 | * Do some background aging of the anon list, to give | |
2073 | * pages a chance to be referenced before reclaiming. | |
2074 | */ | |
14797e23 | 2075 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2076 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2077 | &sc, priority, 0); | |
2078 | ||
41858966 MG |
2079 | if (!zone_watermark_ok(zone, order, |
2080 | high_wmark_pages(zone), 0, 0)) { | |
d6277db4 | 2081 | end_zone = i; |
e1dbeda6 | 2082 | break; |
1da177e4 | 2083 | } |
1da177e4 | 2084 | } |
e1dbeda6 AM |
2085 | if (i < 0) |
2086 | goto out; | |
2087 | ||
1da177e4 LT |
2088 | for (i = 0; i <= end_zone; i++) { |
2089 | struct zone *zone = pgdat->node_zones + i; | |
2090 | ||
adea02a1 | 2091 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2092 | } |
2093 | ||
2094 | /* | |
2095 | * Now scan the zone in the dma->highmem direction, stopping | |
2096 | * at the last zone which needs scanning. | |
2097 | * | |
2098 | * We do this because the page allocator works in the opposite | |
2099 | * direction. This prevents the page allocator from allocating | |
2100 | * pages behind kswapd's direction of progress, which would | |
2101 | * cause too much scanning of the lower zones. | |
2102 | */ | |
2103 | for (i = 0; i <= end_zone; i++) { | |
2104 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2105 | int nr_slab; |
4e416953 | 2106 | int nid, zid; |
1da177e4 | 2107 | |
f3fe6512 | 2108 | if (!populated_zone(zone)) |
1da177e4 LT |
2109 | continue; |
2110 | ||
93e4a89a | 2111 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2112 | continue; |
2113 | ||
3bb1a852 | 2114 | temp_priority[i] = priority; |
1da177e4 | 2115 | sc.nr_scanned = 0; |
3bb1a852 | 2116 | note_zone_scanning_priority(zone, priority); |
4e416953 BS |
2117 | |
2118 | nid = pgdat->node_id; | |
2119 | zid = zone_idx(zone); | |
2120 | /* | |
2121 | * Call soft limit reclaim before calling shrink_zone. | |
2122 | * For now we ignore the return value | |
2123 | */ | |
2124 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask, | |
2125 | nid, zid); | |
32a4330d RR |
2126 | /* |
2127 | * We put equal pressure on every zone, unless one | |
2128 | * zone has way too many pages free already. | |
2129 | */ | |
41858966 MG |
2130 | if (!zone_watermark_ok(zone, order, |
2131 | 8*high_wmark_pages(zone), end_zone, 0)) | |
a79311c1 | 2132 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2133 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2134 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2135 | lru_pages); | |
a79311c1 | 2136 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2137 | total_scanned += sc.nr_scanned; |
93e4a89a | 2138 | if (zone->all_unreclaimable) |
1da177e4 | 2139 | continue; |
93e4a89a KM |
2140 | if (nr_slab == 0 && |
2141 | zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) | |
2142 | zone->all_unreclaimable = 1; | |
1da177e4 LT |
2143 | /* |
2144 | * If we've done a decent amount of scanning and | |
2145 | * the reclaim ratio is low, start doing writepage | |
2146 | * even in laptop mode | |
2147 | */ | |
2148 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2149 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2150 | sc.may_writepage = 1; |
bb3ab596 | 2151 | |
45973d74 MK |
2152 | if (!zone_watermark_ok(zone, order, |
2153 | high_wmark_pages(zone), end_zone, 0)) { | |
2154 | all_zones_ok = 0; | |
2155 | /* | |
2156 | * We are still under min water mark. This | |
2157 | * means that we have a GFP_ATOMIC allocation | |
2158 | * failure risk. Hurry up! | |
2159 | */ | |
2160 | if (!zone_watermark_ok(zone, order, | |
2161 | min_wmark_pages(zone), end_zone, 0)) | |
2162 | has_under_min_watermark_zone = 1; | |
2163 | } | |
bb3ab596 | 2164 | |
1da177e4 | 2165 | } |
1da177e4 LT |
2166 | if (all_zones_ok) |
2167 | break; /* kswapd: all done */ | |
2168 | /* | |
2169 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2170 | * another pass across the zones. | |
2171 | */ | |
bb3ab596 KM |
2172 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2173 | if (has_under_min_watermark_zone) | |
2174 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2175 | else | |
2176 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2177 | } | |
1da177e4 LT |
2178 | |
2179 | /* | |
2180 | * We do this so kswapd doesn't build up large priorities for | |
2181 | * example when it is freeing in parallel with allocators. It | |
2182 | * matches the direct reclaim path behaviour in terms of impact | |
2183 | * on zone->*_priority. | |
2184 | */ | |
a79311c1 | 2185 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2186 | break; |
2187 | } | |
2188 | out: | |
3bb1a852 MB |
2189 | /* |
2190 | * Note within each zone the priority level at which this zone was | |
2191 | * brought into a happy state. So that the next thread which scans this | |
2192 | * zone will start out at that priority level. | |
2193 | */ | |
1da177e4 LT |
2194 | for (i = 0; i < pgdat->nr_zones; i++) { |
2195 | struct zone *zone = pgdat->node_zones + i; | |
2196 | ||
3bb1a852 | 2197 | zone->prev_priority = temp_priority[i]; |
1da177e4 LT |
2198 | } |
2199 | if (!all_zones_ok) { | |
2200 | cond_resched(); | |
8357376d RW |
2201 | |
2202 | try_to_freeze(); | |
2203 | ||
73ce02e9 KM |
2204 | /* |
2205 | * Fragmentation may mean that the system cannot be | |
2206 | * rebalanced for high-order allocations in all zones. | |
2207 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2208 | * it means the zones have been fully scanned and are still | |
2209 | * not balanced. For high-order allocations, there is | |
2210 | * little point trying all over again as kswapd may | |
2211 | * infinite loop. | |
2212 | * | |
2213 | * Instead, recheck all watermarks at order-0 as they | |
2214 | * are the most important. If watermarks are ok, kswapd will go | |
2215 | * back to sleep. High-order users can still perform direct | |
2216 | * reclaim if they wish. | |
2217 | */ | |
2218 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2219 | order = sc.order = 0; | |
2220 | ||
1da177e4 LT |
2221 | goto loop_again; |
2222 | } | |
2223 | ||
a79311c1 | 2224 | return sc.nr_reclaimed; |
1da177e4 LT |
2225 | } |
2226 | ||
2227 | /* | |
2228 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2229 | * from the init process. |
1da177e4 LT |
2230 | * |
2231 | * This basically trickles out pages so that we have _some_ | |
2232 | * free memory available even if there is no other activity | |
2233 | * that frees anything up. This is needed for things like routing | |
2234 | * etc, where we otherwise might have all activity going on in | |
2235 | * asynchronous contexts that cannot page things out. | |
2236 | * | |
2237 | * If there are applications that are active memory-allocators | |
2238 | * (most normal use), this basically shouldn't matter. | |
2239 | */ | |
2240 | static int kswapd(void *p) | |
2241 | { | |
2242 | unsigned long order; | |
2243 | pg_data_t *pgdat = (pg_data_t*)p; | |
2244 | struct task_struct *tsk = current; | |
2245 | DEFINE_WAIT(wait); | |
2246 | struct reclaim_state reclaim_state = { | |
2247 | .reclaimed_slab = 0, | |
2248 | }; | |
a70f7302 | 2249 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2250 | |
cf40bd16 NP |
2251 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2252 | ||
174596a0 | 2253 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2254 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2255 | current->reclaim_state = &reclaim_state; |
2256 | ||
2257 | /* | |
2258 | * Tell the memory management that we're a "memory allocator", | |
2259 | * and that if we need more memory we should get access to it | |
2260 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2261 | * never get caught in the normal page freeing logic. | |
2262 | * | |
2263 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2264 | * you need a small amount of memory in order to be able to | |
2265 | * page out something else, and this flag essentially protects | |
2266 | * us from recursively trying to free more memory as we're | |
2267 | * trying to free the first piece of memory in the first place). | |
2268 | */ | |
930d9152 | 2269 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2270 | set_freezable(); |
1da177e4 LT |
2271 | |
2272 | order = 0; | |
2273 | for ( ; ; ) { | |
2274 | unsigned long new_order; | |
8fe23e05 | 2275 | int ret; |
3e1d1d28 | 2276 | |
1da177e4 LT |
2277 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2278 | new_order = pgdat->kswapd_max_order; | |
2279 | pgdat->kswapd_max_order = 0; | |
2280 | if (order < new_order) { | |
2281 | /* | |
2282 | * Don't sleep if someone wants a larger 'order' | |
2283 | * allocation | |
2284 | */ | |
2285 | order = new_order; | |
2286 | } else { | |
f50de2d3 MG |
2287 | if (!freezing(current) && !kthread_should_stop()) { |
2288 | long remaining = 0; | |
2289 | ||
2290 | /* Try to sleep for a short interval */ | |
bb3ab596 | 2291 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
f50de2d3 MG |
2292 | remaining = schedule_timeout(HZ/10); |
2293 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2294 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2295 | } | |
2296 | ||
2297 | /* | |
2298 | * After a short sleep, check if it was a | |
2299 | * premature sleep. If not, then go fully | |
2300 | * to sleep until explicitly woken up | |
2301 | */ | |
bb3ab596 | 2302 | if (!sleeping_prematurely(pgdat, order, remaining)) |
f50de2d3 MG |
2303 | schedule(); |
2304 | else { | |
2305 | if (remaining) | |
bb3ab596 | 2306 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); |
f50de2d3 | 2307 | else |
bb3ab596 | 2308 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); |
f50de2d3 MG |
2309 | } |
2310 | } | |
b1296cc4 | 2311 | |
1da177e4 LT |
2312 | order = pgdat->kswapd_max_order; |
2313 | } | |
2314 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2315 | ||
8fe23e05 DR |
2316 | ret = try_to_freeze(); |
2317 | if (kthread_should_stop()) | |
2318 | break; | |
2319 | ||
2320 | /* | |
2321 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2322 | * after returning from the refrigerator | |
2323 | */ | |
2324 | if (!ret) | |
b1296cc4 | 2325 | balance_pgdat(pgdat, order); |
1da177e4 LT |
2326 | } |
2327 | return 0; | |
2328 | } | |
2329 | ||
2330 | /* | |
2331 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2332 | */ | |
2333 | void wakeup_kswapd(struct zone *zone, int order) | |
2334 | { | |
2335 | pg_data_t *pgdat; | |
2336 | ||
f3fe6512 | 2337 | if (!populated_zone(zone)) |
1da177e4 LT |
2338 | return; |
2339 | ||
2340 | pgdat = zone->zone_pgdat; | |
41858966 | 2341 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) |
1da177e4 LT |
2342 | return; |
2343 | if (pgdat->kswapd_max_order < order) | |
2344 | pgdat->kswapd_max_order = order; | |
02a0e53d | 2345 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2346 | return; |
8d0986e2 | 2347 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2348 | return; |
8d0986e2 | 2349 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2350 | } |
2351 | ||
adea02a1 WF |
2352 | /* |
2353 | * The reclaimable count would be mostly accurate. | |
2354 | * The less reclaimable pages may be | |
2355 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2356 | * - mapped pages, which may require several travels to be reclaimed | |
2357 | * - dirty pages, which is not "instantly" reclaimable | |
2358 | */ | |
2359 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2360 | { |
adea02a1 WF |
2361 | int nr; |
2362 | ||
2363 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2364 | global_page_state(NR_INACTIVE_FILE); | |
2365 | ||
2366 | if (nr_swap_pages > 0) | |
2367 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2368 | global_page_state(NR_INACTIVE_ANON); | |
2369 | ||
2370 | return nr; | |
2371 | } | |
2372 | ||
2373 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2374 | { | |
2375 | int nr; | |
2376 | ||
2377 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2378 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2379 | ||
2380 | if (nr_swap_pages > 0) | |
2381 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2382 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2383 | ||
2384 | return nr; | |
4f98a2fe RR |
2385 | } |
2386 | ||
c6f37f12 | 2387 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2388 | /* |
7b51755c | 2389 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2390 | * freed pages. |
2391 | * | |
2392 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2393 | * LRU order by reclaiming preferentially | |
2394 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2395 | */ |
7b51755c | 2396 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2397 | { |
d6277db4 | 2398 | struct reclaim_state reclaim_state; |
d6277db4 | 2399 | struct scan_control sc = { |
7b51755c KM |
2400 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2401 | .may_swap = 1, | |
2402 | .may_unmap = 1, | |
d6277db4 | 2403 | .may_writepage = 1, |
7b51755c KM |
2404 | .nr_to_reclaim = nr_to_reclaim, |
2405 | .hibernation_mode = 1, | |
2406 | .swappiness = vm_swappiness, | |
2407 | .order = 0, | |
1da177e4 | 2408 | }; |
7b51755c KM |
2409 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2410 | struct task_struct *p = current; | |
2411 | unsigned long nr_reclaimed; | |
1da177e4 | 2412 | |
7b51755c KM |
2413 | p->flags |= PF_MEMALLOC; |
2414 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2415 | reclaim_state.reclaimed_slab = 0; | |
2416 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2417 | |
7b51755c | 2418 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2419 | |
7b51755c KM |
2420 | p->reclaim_state = NULL; |
2421 | lockdep_clear_current_reclaim_state(); | |
2422 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2423 | |
7b51755c | 2424 | return nr_reclaimed; |
1da177e4 | 2425 | } |
c6f37f12 | 2426 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2427 | |
1da177e4 LT |
2428 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2429 | not required for correctness. So if the last cpu in a node goes | |
2430 | away, we get changed to run anywhere: as the first one comes back, | |
2431 | restore their cpu bindings. */ | |
9c7b216d | 2432 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2433 | unsigned long action, void *hcpu) |
1da177e4 | 2434 | { |
58c0a4a7 | 2435 | int nid; |
1da177e4 | 2436 | |
8bb78442 | 2437 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2438 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2439 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2440 | const struct cpumask *mask; |
2441 | ||
2442 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2443 | |
3e597945 | 2444 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2445 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2446 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2447 | } |
2448 | } | |
2449 | return NOTIFY_OK; | |
2450 | } | |
1da177e4 | 2451 | |
3218ae14 YG |
2452 | /* |
2453 | * This kswapd start function will be called by init and node-hot-add. | |
2454 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2455 | */ | |
2456 | int kswapd_run(int nid) | |
2457 | { | |
2458 | pg_data_t *pgdat = NODE_DATA(nid); | |
2459 | int ret = 0; | |
2460 | ||
2461 | if (pgdat->kswapd) | |
2462 | return 0; | |
2463 | ||
2464 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2465 | if (IS_ERR(pgdat->kswapd)) { | |
2466 | /* failure at boot is fatal */ | |
2467 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2468 | printk("Failed to start kswapd on node %d\n",nid); | |
2469 | ret = -1; | |
2470 | } | |
2471 | return ret; | |
2472 | } | |
2473 | ||
8fe23e05 DR |
2474 | /* |
2475 | * Called by memory hotplug when all memory in a node is offlined. | |
2476 | */ | |
2477 | void kswapd_stop(int nid) | |
2478 | { | |
2479 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2480 | ||
2481 | if (kswapd) | |
2482 | kthread_stop(kswapd); | |
2483 | } | |
2484 | ||
1da177e4 LT |
2485 | static int __init kswapd_init(void) |
2486 | { | |
3218ae14 | 2487 | int nid; |
69e05944 | 2488 | |
1da177e4 | 2489 | swap_setup(); |
9422ffba | 2490 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2491 | kswapd_run(nid); |
1da177e4 LT |
2492 | hotcpu_notifier(cpu_callback, 0); |
2493 | return 0; | |
2494 | } | |
2495 | ||
2496 | module_init(kswapd_init) | |
9eeff239 CL |
2497 | |
2498 | #ifdef CONFIG_NUMA | |
2499 | /* | |
2500 | * Zone reclaim mode | |
2501 | * | |
2502 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2503 | * the watermarks. | |
9eeff239 CL |
2504 | */ |
2505 | int zone_reclaim_mode __read_mostly; | |
2506 | ||
1b2ffb78 | 2507 | #define RECLAIM_OFF 0 |
7d03431c | 2508 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2509 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2510 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2511 | ||
a92f7126 CL |
2512 | /* |
2513 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2514 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2515 | * a zone. | |
2516 | */ | |
2517 | #define ZONE_RECLAIM_PRIORITY 4 | |
2518 | ||
9614634f CL |
2519 | /* |
2520 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2521 | * occur. | |
2522 | */ | |
2523 | int sysctl_min_unmapped_ratio = 1; | |
2524 | ||
0ff38490 CL |
2525 | /* |
2526 | * If the number of slab pages in a zone grows beyond this percentage then | |
2527 | * slab reclaim needs to occur. | |
2528 | */ | |
2529 | int sysctl_min_slab_ratio = 5; | |
2530 | ||
90afa5de MG |
2531 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2532 | { | |
2533 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2534 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2535 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2536 | ||
2537 | /* | |
2538 | * It's possible for there to be more file mapped pages than | |
2539 | * accounted for by the pages on the file LRU lists because | |
2540 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2541 | */ | |
2542 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2543 | } | |
2544 | ||
2545 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2546 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2547 | { | |
2548 | long nr_pagecache_reclaimable; | |
2549 | long delta = 0; | |
2550 | ||
2551 | /* | |
2552 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2553 | * potentially reclaimable. Otherwise, we have to worry about | |
2554 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2555 | * a better estimate | |
2556 | */ | |
2557 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2558 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2559 | else | |
2560 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2561 | ||
2562 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2563 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2564 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2565 | ||
2566 | /* Watch for any possible underflows due to delta */ | |
2567 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2568 | delta = nr_pagecache_reclaimable; | |
2569 | ||
2570 | return nr_pagecache_reclaimable - delta; | |
2571 | } | |
2572 | ||
9eeff239 CL |
2573 | /* |
2574 | * Try to free up some pages from this zone through reclaim. | |
2575 | */ | |
179e9639 | 2576 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2577 | { |
7fb2d46d | 2578 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2579 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2580 | struct task_struct *p = current; |
2581 | struct reclaim_state reclaim_state; | |
8695949a | 2582 | int priority; |
179e9639 AM |
2583 | struct scan_control sc = { |
2584 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2585 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2586 | .may_swap = 1, |
22fba335 KM |
2587 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2588 | SWAP_CLUSTER_MAX), | |
179e9639 | 2589 | .gfp_mask = gfp_mask, |
d6277db4 | 2590 | .swappiness = vm_swappiness, |
bd2f6199 | 2591 | .order = order, |
179e9639 | 2592 | }; |
83e33a47 | 2593 | unsigned long slab_reclaimable; |
9eeff239 CL |
2594 | |
2595 | disable_swap_token(); | |
9eeff239 | 2596 | cond_resched(); |
d4f7796e CL |
2597 | /* |
2598 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2599 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2600 | * and RECLAIM_SWAP. | |
2601 | */ | |
2602 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2603 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2604 | reclaim_state.reclaimed_slab = 0; |
2605 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2606 | |
90afa5de | 2607 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2608 | /* |
2609 | * Free memory by calling shrink zone with increasing | |
2610 | * priorities until we have enough memory freed. | |
2611 | */ | |
2612 | priority = ZONE_RECLAIM_PRIORITY; | |
2613 | do { | |
3bb1a852 | 2614 | note_zone_scanning_priority(zone, priority); |
a79311c1 | 2615 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2616 | priority--; |
a79311c1 | 2617 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2618 | } |
c84db23c | 2619 | |
83e33a47 CL |
2620 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2621 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2622 | /* |
7fb2d46d | 2623 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2624 | * many pages were freed in this zone. So we take the current |
2625 | * number of slab pages and shake the slab until it is reduced | |
2626 | * by the same nr_pages that we used for reclaiming unmapped | |
2627 | * pages. | |
2a16e3f4 | 2628 | * |
0ff38490 CL |
2629 | * Note that shrink_slab will free memory on all zones and may |
2630 | * take a long time. | |
2a16e3f4 | 2631 | */ |
0ff38490 | 2632 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2633 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2634 | slab_reclaimable - nr_pages) | |
0ff38490 | 2635 | ; |
83e33a47 CL |
2636 | |
2637 | /* | |
2638 | * Update nr_reclaimed by the number of slab pages we | |
2639 | * reclaimed from this zone. | |
2640 | */ | |
a79311c1 | 2641 | sc.nr_reclaimed += slab_reclaimable - |
83e33a47 | 2642 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2a16e3f4 CL |
2643 | } |
2644 | ||
9eeff239 | 2645 | p->reclaim_state = NULL; |
d4f7796e | 2646 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 2647 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 2648 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2649 | } |
179e9639 AM |
2650 | |
2651 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2652 | { | |
179e9639 | 2653 | int node_id; |
d773ed6b | 2654 | int ret; |
179e9639 AM |
2655 | |
2656 | /* | |
0ff38490 CL |
2657 | * Zone reclaim reclaims unmapped file backed pages and |
2658 | * slab pages if we are over the defined limits. | |
34aa1330 | 2659 | * |
9614634f CL |
2660 | * A small portion of unmapped file backed pages is needed for |
2661 | * file I/O otherwise pages read by file I/O will be immediately | |
2662 | * thrown out if the zone is overallocated. So we do not reclaim | |
2663 | * if less than a specified percentage of the zone is used by | |
2664 | * unmapped file backed pages. | |
179e9639 | 2665 | */ |
90afa5de MG |
2666 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2667 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 2668 | return ZONE_RECLAIM_FULL; |
179e9639 | 2669 | |
93e4a89a | 2670 | if (zone->all_unreclaimable) |
fa5e084e | 2671 | return ZONE_RECLAIM_FULL; |
d773ed6b | 2672 | |
179e9639 | 2673 | /* |
d773ed6b | 2674 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2675 | */ |
d773ed6b | 2676 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 2677 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
2678 | |
2679 | /* | |
2680 | * Only run zone reclaim on the local zone or on zones that do not | |
2681 | * have associated processors. This will favor the local processor | |
2682 | * over remote processors and spread off node memory allocations | |
2683 | * as wide as possible. | |
2684 | */ | |
89fa3024 | 2685 | node_id = zone_to_nid(zone); |
37c0708d | 2686 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 2687 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
2688 | |
2689 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
2690 | return ZONE_RECLAIM_NOSCAN; |
2691 | ||
d773ed6b DR |
2692 | ret = __zone_reclaim(zone, gfp_mask, order); |
2693 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2694 | ||
24cf7251 MG |
2695 | if (!ret) |
2696 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
2697 | ||
d773ed6b | 2698 | return ret; |
179e9639 | 2699 | } |
9eeff239 | 2700 | #endif |
894bc310 | 2701 | |
894bc310 LS |
2702 | /* |
2703 | * page_evictable - test whether a page is evictable | |
2704 | * @page: the page to test | |
2705 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2706 | * | |
2707 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2708 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2709 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2710 | * |
2711 | * Reasons page might not be evictable: | |
ba9ddf49 | 2712 | * (1) page's mapping marked unevictable |
b291f000 | 2713 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2714 | * |
894bc310 LS |
2715 | */ |
2716 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2717 | { | |
2718 | ||
ba9ddf49 LS |
2719 | if (mapping_unevictable(page_mapping(page))) |
2720 | return 0; | |
2721 | ||
b291f000 NP |
2722 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2723 | return 0; | |
894bc310 LS |
2724 | |
2725 | return 1; | |
2726 | } | |
89e004ea LS |
2727 | |
2728 | /** | |
2729 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2730 | * @page: page to check evictability and move to appropriate lru list | |
2731 | * @zone: zone page is in | |
2732 | * | |
2733 | * Checks a page for evictability and moves the page to the appropriate | |
2734 | * zone lru list. | |
2735 | * | |
2736 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2737 | * have PageUnevictable set. | |
2738 | */ | |
2739 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2740 | { | |
2741 | VM_BUG_ON(PageActive(page)); | |
2742 | ||
2743 | retry: | |
2744 | ClearPageUnevictable(page); | |
2745 | if (page_evictable(page, NULL)) { | |
401a8e1c | 2746 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 2747 | |
89e004ea LS |
2748 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2749 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2750 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2751 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2752 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2753 | } else { | |
2754 | /* | |
2755 | * rotate unevictable list | |
2756 | */ | |
2757 | SetPageUnevictable(page); | |
2758 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2759 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2760 | if (page_evictable(page, NULL)) |
2761 | goto retry; | |
2762 | } | |
2763 | } | |
2764 | ||
2765 | /** | |
2766 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2767 | * @mapping: struct address_space to scan for evictable pages | |
2768 | * | |
2769 | * Scan all pages in mapping. Check unevictable pages for | |
2770 | * evictability and move them to the appropriate zone lru list. | |
2771 | */ | |
2772 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2773 | { | |
2774 | pgoff_t next = 0; | |
2775 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2776 | PAGE_CACHE_SHIFT; | |
2777 | struct zone *zone; | |
2778 | struct pagevec pvec; | |
2779 | ||
2780 | if (mapping->nrpages == 0) | |
2781 | return; | |
2782 | ||
2783 | pagevec_init(&pvec, 0); | |
2784 | while (next < end && | |
2785 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2786 | int i; | |
2787 | int pg_scanned = 0; | |
2788 | ||
2789 | zone = NULL; | |
2790 | ||
2791 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2792 | struct page *page = pvec.pages[i]; | |
2793 | pgoff_t page_index = page->index; | |
2794 | struct zone *pagezone = page_zone(page); | |
2795 | ||
2796 | pg_scanned++; | |
2797 | if (page_index > next) | |
2798 | next = page_index; | |
2799 | next++; | |
2800 | ||
2801 | if (pagezone != zone) { | |
2802 | if (zone) | |
2803 | spin_unlock_irq(&zone->lru_lock); | |
2804 | zone = pagezone; | |
2805 | spin_lock_irq(&zone->lru_lock); | |
2806 | } | |
2807 | ||
2808 | if (PageLRU(page) && PageUnevictable(page)) | |
2809 | check_move_unevictable_page(page, zone); | |
2810 | } | |
2811 | if (zone) | |
2812 | spin_unlock_irq(&zone->lru_lock); | |
2813 | pagevec_release(&pvec); | |
2814 | ||
2815 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2816 | } | |
2817 | ||
2818 | } | |
af936a16 LS |
2819 | |
2820 | /** | |
2821 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2822 | * @zone - zone of which to scan the unevictable list | |
2823 | * | |
2824 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2825 | * evictable. Move those that have to @zone's inactive list where they | |
2826 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2827 | * to reactivate them. Pages that are still unevictable are rotated | |
2828 | * back onto @zone's unevictable list. | |
2829 | */ | |
2830 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2831 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2832 | { |
2833 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2834 | unsigned long scan; | |
2835 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2836 | ||
2837 | while (nr_to_scan > 0) { | |
2838 | unsigned long batch_size = min(nr_to_scan, | |
2839 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2840 | ||
2841 | spin_lock_irq(&zone->lru_lock); | |
2842 | for (scan = 0; scan < batch_size; scan++) { | |
2843 | struct page *page = lru_to_page(l_unevictable); | |
2844 | ||
2845 | if (!trylock_page(page)) | |
2846 | continue; | |
2847 | ||
2848 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
2849 | ||
2850 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
2851 | check_move_unevictable_page(page, zone); | |
2852 | ||
2853 | unlock_page(page); | |
2854 | } | |
2855 | spin_unlock_irq(&zone->lru_lock); | |
2856 | ||
2857 | nr_to_scan -= batch_size; | |
2858 | } | |
2859 | } | |
2860 | ||
2861 | ||
2862 | /** | |
2863 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
2864 | * | |
2865 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
2866 | * pages that have become evictable. Move those back to the zones' | |
2867 | * inactive list where they become candidates for reclaim. | |
2868 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
2869 | * and we add swap to the system. As such, it runs in the context of a task | |
2870 | * that has possibly/probably made some previously unevictable pages | |
2871 | * evictable. | |
2872 | */ | |
ff30153b | 2873 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
2874 | { |
2875 | struct zone *zone; | |
2876 | ||
2877 | for_each_zone(zone) { | |
2878 | scan_zone_unevictable_pages(zone); | |
2879 | } | |
2880 | } | |
2881 | ||
2882 | /* | |
2883 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
2884 | * all nodes' unevictable lists for evictable pages | |
2885 | */ | |
2886 | unsigned long scan_unevictable_pages; | |
2887 | ||
2888 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 2889 | void __user *buffer, |
af936a16 LS |
2890 | size_t *length, loff_t *ppos) |
2891 | { | |
8d65af78 | 2892 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
2893 | |
2894 | if (write && *(unsigned long *)table->data) | |
2895 | scan_all_zones_unevictable_pages(); | |
2896 | ||
2897 | scan_unevictable_pages = 0; | |
2898 | return 0; | |
2899 | } | |
2900 | ||
2901 | /* | |
2902 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
2903 | * a specified node's per zone unevictable lists for evictable pages. | |
2904 | */ | |
2905 | ||
2906 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
2907 | struct sysdev_attribute *attr, | |
2908 | char *buf) | |
2909 | { | |
2910 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
2911 | } | |
2912 | ||
2913 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
2914 | struct sysdev_attribute *attr, | |
2915 | const char *buf, size_t count) | |
2916 | { | |
2917 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
2918 | struct zone *zone; | |
2919 | unsigned long res; | |
2920 | unsigned long req = strict_strtoul(buf, 10, &res); | |
2921 | ||
2922 | if (!req) | |
2923 | return 1; /* zero is no-op */ | |
2924 | ||
2925 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
2926 | if (!populated_zone(zone)) | |
2927 | continue; | |
2928 | scan_zone_unevictable_pages(zone); | |
2929 | } | |
2930 | return 1; | |
2931 | } | |
2932 | ||
2933 | ||
2934 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
2935 | read_scan_unevictable_node, | |
2936 | write_scan_unevictable_node); | |
2937 | ||
2938 | int scan_unevictable_register_node(struct node *node) | |
2939 | { | |
2940 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2941 | } | |
2942 | ||
2943 | void scan_unevictable_unregister_node(struct node *node) | |
2944 | { | |
2945 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2946 | } | |
2947 |