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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 | ||
33906bc5 MG |
51 | #define CREATE_TRACE_POINTS |
52 | #include <trace/events/vmscan.h> | |
53 | ||
1da177e4 | 54 | struct scan_control { |
1da177e4 LT |
55 | /* Incremented by the number of inactive pages that were scanned */ |
56 | unsigned long nr_scanned; | |
57 | ||
a79311c1 RR |
58 | /* Number of pages freed so far during a call to shrink_zones() */ |
59 | unsigned long nr_reclaimed; | |
60 | ||
22fba335 KM |
61 | /* How many pages shrink_list() should reclaim */ |
62 | unsigned long nr_to_reclaim; | |
63 | ||
7b51755c KM |
64 | unsigned long hibernation_mode; |
65 | ||
1da177e4 | 66 | /* This context's GFP mask */ |
6daa0e28 | 67 | gfp_t gfp_mask; |
1da177e4 LT |
68 | |
69 | int may_writepage; | |
70 | ||
a6dc60f8 JW |
71 | /* Can mapped pages be reclaimed? */ |
72 | int may_unmap; | |
f1fd1067 | 73 | |
2e2e4259 KM |
74 | /* Can pages be swapped as part of reclaim? */ |
75 | int may_swap; | |
76 | ||
d6277db4 | 77 | int swappiness; |
408d8544 | 78 | |
5ad333eb | 79 | int order; |
66e1707b | 80 | |
5f53e762 KM |
81 | /* |
82 | * Intend to reclaim enough contenious memory rather than to reclaim | |
83 | * enough amount memory. I.e, it's the mode for high order allocation. | |
84 | */ | |
85 | bool lumpy_reclaim_mode; | |
86 | ||
66e1707b BS |
87 | /* Which cgroup do we reclaim from */ |
88 | struct mem_cgroup *mem_cgroup; | |
89 | ||
327c0e96 KH |
90 | /* |
91 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
92 | * are scanned. | |
93 | */ | |
94 | nodemask_t *nodemask; | |
1da177e4 LT |
95 | }; |
96 | ||
1da177e4 LT |
97 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
98 | ||
99 | #ifdef ARCH_HAS_PREFETCH | |
100 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
101 | do { \ | |
102 | if ((_page)->lru.prev != _base) { \ | |
103 | struct page *prev; \ | |
104 | \ | |
105 | prev = lru_to_page(&(_page->lru)); \ | |
106 | prefetch(&prev->_field); \ | |
107 | } \ | |
108 | } while (0) | |
109 | #else | |
110 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
111 | #endif | |
112 | ||
113 | #ifdef ARCH_HAS_PREFETCHW | |
114 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
115 | do { \ | |
116 | if ((_page)->lru.prev != _base) { \ | |
117 | struct page *prev; \ | |
118 | \ | |
119 | prev = lru_to_page(&(_page->lru)); \ | |
120 | prefetchw(&prev->_field); \ | |
121 | } \ | |
122 | } while (0) | |
123 | #else | |
124 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
125 | #endif | |
126 | ||
127 | /* | |
128 | * From 0 .. 100. Higher means more swappy. | |
129 | */ | |
130 | int vm_swappiness = 60; | |
bd1e22b8 | 131 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
132 | |
133 | static LIST_HEAD(shrinker_list); | |
134 | static DECLARE_RWSEM(shrinker_rwsem); | |
135 | ||
00f0b825 | 136 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 137 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 138 | #else |
e72e2bd6 | 139 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
140 | #endif |
141 | ||
6e901571 KM |
142 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
143 | struct scan_control *sc) | |
144 | { | |
e72e2bd6 | 145 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
146 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
147 | ||
6e901571 KM |
148 | return &zone->reclaim_stat; |
149 | } | |
150 | ||
0b217676 VL |
151 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
152 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 153 | { |
e72e2bd6 | 154 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
155 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
156 | ||
c9f299d9 KM |
157 | return zone_page_state(zone, NR_LRU_BASE + lru); |
158 | } | |
159 | ||
160 | ||
1da177e4 LT |
161 | /* |
162 | * Add a shrinker callback to be called from the vm | |
163 | */ | |
8e1f936b | 164 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 165 | { |
8e1f936b RR |
166 | shrinker->nr = 0; |
167 | down_write(&shrinker_rwsem); | |
168 | list_add_tail(&shrinker->list, &shrinker_list); | |
169 | up_write(&shrinker_rwsem); | |
1da177e4 | 170 | } |
8e1f936b | 171 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
172 | |
173 | /* | |
174 | * Remove one | |
175 | */ | |
8e1f936b | 176 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
177 | { |
178 | down_write(&shrinker_rwsem); | |
179 | list_del(&shrinker->list); | |
180 | up_write(&shrinker_rwsem); | |
1da177e4 | 181 | } |
8e1f936b | 182 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
183 | |
184 | #define SHRINK_BATCH 128 | |
185 | /* | |
186 | * Call the shrink functions to age shrinkable caches | |
187 | * | |
188 | * Here we assume it costs one seek to replace a lru page and that it also | |
189 | * takes a seek to recreate a cache object. With this in mind we age equal | |
190 | * percentages of the lru and ageable caches. This should balance the seeks | |
191 | * generated by these structures. | |
192 | * | |
183ff22b | 193 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
194 | * slab to avoid swapping. |
195 | * | |
196 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
197 | * | |
198 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
199 | * are eligible for the caller's allocation attempt. It is used for balancing | |
200 | * slab reclaim versus page reclaim. | |
b15e0905 | 201 | * |
202 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 203 | */ |
69e05944 AM |
204 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
205 | unsigned long lru_pages) | |
1da177e4 LT |
206 | { |
207 | struct shrinker *shrinker; | |
69e05944 | 208 | unsigned long ret = 0; |
1da177e4 LT |
209 | |
210 | if (scanned == 0) | |
211 | scanned = SWAP_CLUSTER_MAX; | |
212 | ||
213 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 214 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
215 | |
216 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
217 | unsigned long long delta; | |
218 | unsigned long total_scan; | |
7f8275d0 | 219 | unsigned long max_pass; |
1da177e4 | 220 | |
7f8275d0 | 221 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 222 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 223 | delta *= max_pass; |
1da177e4 LT |
224 | do_div(delta, lru_pages + 1); |
225 | shrinker->nr += delta; | |
ea164d73 | 226 | if (shrinker->nr < 0) { |
88c3bd70 DR |
227 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
228 | "delete nr=%ld\n", | |
229 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
230 | shrinker->nr = max_pass; |
231 | } | |
232 | ||
233 | /* | |
234 | * Avoid risking looping forever due to too large nr value: | |
235 | * never try to free more than twice the estimate number of | |
236 | * freeable entries. | |
237 | */ | |
238 | if (shrinker->nr > max_pass * 2) | |
239 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
240 | |
241 | total_scan = shrinker->nr; | |
242 | shrinker->nr = 0; | |
243 | ||
244 | while (total_scan >= SHRINK_BATCH) { | |
245 | long this_scan = SHRINK_BATCH; | |
246 | int shrink_ret; | |
b15e0905 | 247 | int nr_before; |
1da177e4 | 248 | |
7f8275d0 DC |
249 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
250 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
251 | gfp_mask); | |
1da177e4 LT |
252 | if (shrink_ret == -1) |
253 | break; | |
b15e0905 | 254 | if (shrink_ret < nr_before) |
255 | ret += nr_before - shrink_ret; | |
f8891e5e | 256 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
257 | total_scan -= this_scan; |
258 | ||
259 | cond_resched(); | |
260 | } | |
261 | ||
262 | shrinker->nr += total_scan; | |
263 | } | |
264 | up_read(&shrinker_rwsem); | |
b15e0905 | 265 | return ret; |
1da177e4 LT |
266 | } |
267 | ||
1da177e4 LT |
268 | static inline int is_page_cache_freeable(struct page *page) |
269 | { | |
ceddc3a5 JW |
270 | /* |
271 | * A freeable page cache page is referenced only by the caller | |
272 | * that isolated the page, the page cache radix tree and | |
273 | * optional buffer heads at page->private. | |
274 | */ | |
edcf4748 | 275 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
276 | } |
277 | ||
278 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
279 | { | |
930d9152 | 280 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
281 | return 1; |
282 | if (!bdi_write_congested(bdi)) | |
283 | return 1; | |
284 | if (bdi == current->backing_dev_info) | |
285 | return 1; | |
286 | return 0; | |
287 | } | |
288 | ||
289 | /* | |
290 | * We detected a synchronous write error writing a page out. Probably | |
291 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
292 | * fsync(), msync() or close(). | |
293 | * | |
294 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
295 | * prevents it from being freed up. But we have a ref on the page and once | |
296 | * that page is locked, the mapping is pinned. | |
297 | * | |
298 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
299 | * __GFP_FS. | |
300 | */ | |
301 | static void handle_write_error(struct address_space *mapping, | |
302 | struct page *page, int error) | |
303 | { | |
a6aa62a0 | 304 | lock_page_nosync(page); |
3e9f45bd GC |
305 | if (page_mapping(page) == mapping) |
306 | mapping_set_error(mapping, error); | |
1da177e4 LT |
307 | unlock_page(page); |
308 | } | |
309 | ||
c661b078 AW |
310 | /* Request for sync pageout. */ |
311 | enum pageout_io { | |
312 | PAGEOUT_IO_ASYNC, | |
313 | PAGEOUT_IO_SYNC, | |
314 | }; | |
315 | ||
04e62a29 CL |
316 | /* possible outcome of pageout() */ |
317 | typedef enum { | |
318 | /* failed to write page out, page is locked */ | |
319 | PAGE_KEEP, | |
320 | /* move page to the active list, page is locked */ | |
321 | PAGE_ACTIVATE, | |
322 | /* page has been sent to the disk successfully, page is unlocked */ | |
323 | PAGE_SUCCESS, | |
324 | /* page is clean and locked */ | |
325 | PAGE_CLEAN, | |
326 | } pageout_t; | |
327 | ||
1da177e4 | 328 | /* |
1742f19f AM |
329 | * pageout is called by shrink_page_list() for each dirty page. |
330 | * Calls ->writepage(). | |
1da177e4 | 331 | */ |
c661b078 AW |
332 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
333 | enum pageout_io sync_writeback) | |
1da177e4 LT |
334 | { |
335 | /* | |
336 | * If the page is dirty, only perform writeback if that write | |
337 | * will be non-blocking. To prevent this allocation from being | |
338 | * stalled by pagecache activity. But note that there may be | |
339 | * stalls if we need to run get_block(). We could test | |
340 | * PagePrivate for that. | |
341 | * | |
6aceb53b | 342 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
343 | * this page's queue, we can perform writeback even if that |
344 | * will block. | |
345 | * | |
346 | * If the page is swapcache, write it back even if that would | |
347 | * block, for some throttling. This happens by accident, because | |
348 | * swap_backing_dev_info is bust: it doesn't reflect the | |
349 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
350 | */ |
351 | if (!is_page_cache_freeable(page)) | |
352 | return PAGE_KEEP; | |
353 | if (!mapping) { | |
354 | /* | |
355 | * Some data journaling orphaned pages can have | |
356 | * page->mapping == NULL while being dirty with clean buffers. | |
357 | */ | |
266cf658 | 358 | if (page_has_private(page)) { |
1da177e4 LT |
359 | if (try_to_free_buffers(page)) { |
360 | ClearPageDirty(page); | |
d40cee24 | 361 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
362 | return PAGE_CLEAN; |
363 | } | |
364 | } | |
365 | return PAGE_KEEP; | |
366 | } | |
367 | if (mapping->a_ops->writepage == NULL) | |
368 | return PAGE_ACTIVATE; | |
369 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
370 | return PAGE_KEEP; | |
371 | ||
372 | if (clear_page_dirty_for_io(page)) { | |
373 | int res; | |
374 | struct writeback_control wbc = { | |
375 | .sync_mode = WB_SYNC_NONE, | |
376 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
377 | .range_start = 0, |
378 | .range_end = LLONG_MAX, | |
1da177e4 LT |
379 | .nonblocking = 1, |
380 | .for_reclaim = 1, | |
381 | }; | |
382 | ||
383 | SetPageReclaim(page); | |
384 | res = mapping->a_ops->writepage(page, &wbc); | |
385 | if (res < 0) | |
386 | handle_write_error(mapping, page, res); | |
994fc28c | 387 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
388 | ClearPageReclaim(page); |
389 | return PAGE_ACTIVATE; | |
390 | } | |
c661b078 AW |
391 | |
392 | /* | |
393 | * Wait on writeback if requested to. This happens when | |
394 | * direct reclaiming a large contiguous area and the | |
395 | * first attempt to free a range of pages fails. | |
396 | */ | |
397 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
398 | wait_on_page_writeback(page); | |
399 | ||
1da177e4 LT |
400 | if (!PageWriteback(page)) { |
401 | /* synchronous write or broken a_ops? */ | |
402 | ClearPageReclaim(page); | |
403 | } | |
755f0225 MG |
404 | trace_mm_vmscan_writepage(page, |
405 | trace_reclaim_flags(page, sync_writeback)); | |
e129b5c2 | 406 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
407 | return PAGE_SUCCESS; |
408 | } | |
409 | ||
410 | return PAGE_CLEAN; | |
411 | } | |
412 | ||
a649fd92 | 413 | /* |
e286781d NP |
414 | * Same as remove_mapping, but if the page is removed from the mapping, it |
415 | * gets returned with a refcount of 0. | |
a649fd92 | 416 | */ |
e286781d | 417 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 418 | { |
28e4d965 NP |
419 | BUG_ON(!PageLocked(page)); |
420 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 421 | |
19fd6231 | 422 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 423 | /* |
0fd0e6b0 NP |
424 | * The non racy check for a busy page. |
425 | * | |
426 | * Must be careful with the order of the tests. When someone has | |
427 | * a ref to the page, it may be possible that they dirty it then | |
428 | * drop the reference. So if PageDirty is tested before page_count | |
429 | * here, then the following race may occur: | |
430 | * | |
431 | * get_user_pages(&page); | |
432 | * [user mapping goes away] | |
433 | * write_to(page); | |
434 | * !PageDirty(page) [good] | |
435 | * SetPageDirty(page); | |
436 | * put_page(page); | |
437 | * !page_count(page) [good, discard it] | |
438 | * | |
439 | * [oops, our write_to data is lost] | |
440 | * | |
441 | * Reversing the order of the tests ensures such a situation cannot | |
442 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
443 | * load is not satisfied before that of page->_count. | |
444 | * | |
445 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
446 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 447 | */ |
e286781d | 448 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 449 | goto cannot_free; |
e286781d NP |
450 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
451 | if (unlikely(PageDirty(page))) { | |
452 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 453 | goto cannot_free; |
e286781d | 454 | } |
49d2e9cc CL |
455 | |
456 | if (PageSwapCache(page)) { | |
457 | swp_entry_t swap = { .val = page_private(page) }; | |
458 | __delete_from_swap_cache(page); | |
19fd6231 | 459 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 460 | swapcache_free(swap, page); |
e286781d NP |
461 | } else { |
462 | __remove_from_page_cache(page); | |
19fd6231 | 463 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 464 | mem_cgroup_uncharge_cache_page(page); |
49d2e9cc CL |
465 | } |
466 | ||
49d2e9cc CL |
467 | return 1; |
468 | ||
469 | cannot_free: | |
19fd6231 | 470 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
471 | return 0; |
472 | } | |
473 | ||
e286781d NP |
474 | /* |
475 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
476 | * someone else has a ref on the page, abort and return 0. If it was | |
477 | * successfully detached, return 1. Assumes the caller has a single ref on | |
478 | * this page. | |
479 | */ | |
480 | int remove_mapping(struct address_space *mapping, struct page *page) | |
481 | { | |
482 | if (__remove_mapping(mapping, page)) { | |
483 | /* | |
484 | * Unfreezing the refcount with 1 rather than 2 effectively | |
485 | * drops the pagecache ref for us without requiring another | |
486 | * atomic operation. | |
487 | */ | |
488 | page_unfreeze_refs(page, 1); | |
489 | return 1; | |
490 | } | |
491 | return 0; | |
492 | } | |
493 | ||
894bc310 LS |
494 | /** |
495 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
496 | * @page: page to be put back to appropriate lru list | |
497 | * | |
498 | * Add previously isolated @page to appropriate LRU list. | |
499 | * Page may still be unevictable for other reasons. | |
500 | * | |
501 | * lru_lock must not be held, interrupts must be enabled. | |
502 | */ | |
894bc310 LS |
503 | void putback_lru_page(struct page *page) |
504 | { | |
505 | int lru; | |
506 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 507 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
508 | |
509 | VM_BUG_ON(PageLRU(page)); | |
510 | ||
511 | redo: | |
512 | ClearPageUnevictable(page); | |
513 | ||
514 | if (page_evictable(page, NULL)) { | |
515 | /* | |
516 | * For evictable pages, we can use the cache. | |
517 | * In event of a race, worst case is we end up with an | |
518 | * unevictable page on [in]active list. | |
519 | * We know how to handle that. | |
520 | */ | |
401a8e1c | 521 | lru = active + page_lru_base_type(page); |
894bc310 LS |
522 | lru_cache_add_lru(page, lru); |
523 | } else { | |
524 | /* | |
525 | * Put unevictable pages directly on zone's unevictable | |
526 | * list. | |
527 | */ | |
528 | lru = LRU_UNEVICTABLE; | |
529 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
530 | /* |
531 | * When racing with an mlock clearing (page is | |
532 | * unlocked), make sure that if the other thread does | |
533 | * not observe our setting of PG_lru and fails | |
534 | * isolation, we see PG_mlocked cleared below and move | |
535 | * the page back to the evictable list. | |
536 | * | |
537 | * The other side is TestClearPageMlocked(). | |
538 | */ | |
539 | smp_mb(); | |
894bc310 | 540 | } |
894bc310 LS |
541 | |
542 | /* | |
543 | * page's status can change while we move it among lru. If an evictable | |
544 | * page is on unevictable list, it never be freed. To avoid that, | |
545 | * check after we added it to the list, again. | |
546 | */ | |
547 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
548 | if (!isolate_lru_page(page)) { | |
549 | put_page(page); | |
550 | goto redo; | |
551 | } | |
552 | /* This means someone else dropped this page from LRU | |
553 | * So, it will be freed or putback to LRU again. There is | |
554 | * nothing to do here. | |
555 | */ | |
556 | } | |
557 | ||
bbfd28ee LS |
558 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
559 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
560 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
561 | count_vm_event(UNEVICTABLE_PGCULLED); | |
562 | ||
894bc310 LS |
563 | put_page(page); /* drop ref from isolate */ |
564 | } | |
565 | ||
dfc8d636 JW |
566 | enum page_references { |
567 | PAGEREF_RECLAIM, | |
568 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 569 | PAGEREF_KEEP, |
dfc8d636 JW |
570 | PAGEREF_ACTIVATE, |
571 | }; | |
572 | ||
573 | static enum page_references page_check_references(struct page *page, | |
574 | struct scan_control *sc) | |
575 | { | |
64574746 | 576 | int referenced_ptes, referenced_page; |
dfc8d636 | 577 | unsigned long vm_flags; |
dfc8d636 | 578 | |
64574746 JW |
579 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
580 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
581 | |
582 | /* Lumpy reclaim - ignore references */ | |
5f53e762 | 583 | if (sc->lumpy_reclaim_mode) |
dfc8d636 JW |
584 | return PAGEREF_RECLAIM; |
585 | ||
586 | /* | |
587 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
588 | * move the page to the unevictable list. | |
589 | */ | |
590 | if (vm_flags & VM_LOCKED) | |
591 | return PAGEREF_RECLAIM; | |
592 | ||
64574746 JW |
593 | if (referenced_ptes) { |
594 | if (PageAnon(page)) | |
595 | return PAGEREF_ACTIVATE; | |
596 | /* | |
597 | * All mapped pages start out with page table | |
598 | * references from the instantiating fault, so we need | |
599 | * to look twice if a mapped file page is used more | |
600 | * than once. | |
601 | * | |
602 | * Mark it and spare it for another trip around the | |
603 | * inactive list. Another page table reference will | |
604 | * lead to its activation. | |
605 | * | |
606 | * Note: the mark is set for activated pages as well | |
607 | * so that recently deactivated but used pages are | |
608 | * quickly recovered. | |
609 | */ | |
610 | SetPageReferenced(page); | |
611 | ||
612 | if (referenced_page) | |
613 | return PAGEREF_ACTIVATE; | |
614 | ||
615 | return PAGEREF_KEEP; | |
616 | } | |
dfc8d636 JW |
617 | |
618 | /* Reclaim if clean, defer dirty pages to writeback */ | |
64574746 JW |
619 | if (referenced_page) |
620 | return PAGEREF_RECLAIM_CLEAN; | |
621 | ||
622 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
623 | } |
624 | ||
abe4c3b5 MG |
625 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
626 | { | |
627 | struct pagevec freed_pvec; | |
628 | struct page *page, *tmp; | |
629 | ||
630 | pagevec_init(&freed_pvec, 1); | |
631 | ||
632 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
633 | list_del(&page->lru); | |
634 | if (!pagevec_add(&freed_pvec, page)) { | |
635 | __pagevec_free(&freed_pvec); | |
636 | pagevec_reinit(&freed_pvec); | |
637 | } | |
638 | } | |
639 | ||
640 | pagevec_free(&freed_pvec); | |
641 | } | |
642 | ||
1da177e4 | 643 | /* |
1742f19f | 644 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 645 | */ |
1742f19f | 646 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
647 | struct scan_control *sc, |
648 | enum pageout_io sync_writeback) | |
1da177e4 LT |
649 | { |
650 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 651 | LIST_HEAD(free_pages); |
1da177e4 | 652 | int pgactivate = 0; |
05ff5137 | 653 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
654 | |
655 | cond_resched(); | |
656 | ||
1da177e4 | 657 | while (!list_empty(page_list)) { |
dfc8d636 | 658 | enum page_references references; |
1da177e4 LT |
659 | struct address_space *mapping; |
660 | struct page *page; | |
661 | int may_enter_fs; | |
1da177e4 LT |
662 | |
663 | cond_resched(); | |
664 | ||
665 | page = lru_to_page(page_list); | |
666 | list_del(&page->lru); | |
667 | ||
529ae9aa | 668 | if (!trylock_page(page)) |
1da177e4 LT |
669 | goto keep; |
670 | ||
725d704e | 671 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
672 | |
673 | sc->nr_scanned++; | |
80e43426 | 674 | |
b291f000 NP |
675 | if (unlikely(!page_evictable(page, NULL))) |
676 | goto cull_mlocked; | |
894bc310 | 677 | |
a6dc60f8 | 678 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
679 | goto keep_locked; |
680 | ||
1da177e4 LT |
681 | /* Double the slab pressure for mapped and swapcache pages */ |
682 | if (page_mapped(page) || PageSwapCache(page)) | |
683 | sc->nr_scanned++; | |
684 | ||
c661b078 AW |
685 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
686 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
687 | ||
688 | if (PageWriteback(page)) { | |
689 | /* | |
690 | * Synchronous reclaim is performed in two passes, | |
691 | * first an asynchronous pass over the list to | |
692 | * start parallel writeback, and a second synchronous | |
693 | * pass to wait for the IO to complete. Wait here | |
694 | * for any page for which writeback has already | |
695 | * started. | |
696 | */ | |
697 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
698 | wait_on_page_writeback(page); | |
4dd4b920 | 699 | else |
c661b078 AW |
700 | goto keep_locked; |
701 | } | |
1da177e4 | 702 | |
dfc8d636 JW |
703 | references = page_check_references(page, sc); |
704 | switch (references) { | |
705 | case PAGEREF_ACTIVATE: | |
1da177e4 | 706 | goto activate_locked; |
64574746 JW |
707 | case PAGEREF_KEEP: |
708 | goto keep_locked; | |
dfc8d636 JW |
709 | case PAGEREF_RECLAIM: |
710 | case PAGEREF_RECLAIM_CLEAN: | |
711 | ; /* try to reclaim the page below */ | |
712 | } | |
1da177e4 | 713 | |
1da177e4 LT |
714 | /* |
715 | * Anonymous process memory has backing store? | |
716 | * Try to allocate it some swap space here. | |
717 | */ | |
b291f000 | 718 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
719 | if (!(sc->gfp_mask & __GFP_IO)) |
720 | goto keep_locked; | |
ac47b003 | 721 | if (!add_to_swap(page)) |
1da177e4 | 722 | goto activate_locked; |
63eb6b93 | 723 | may_enter_fs = 1; |
b291f000 | 724 | } |
1da177e4 LT |
725 | |
726 | mapping = page_mapping(page); | |
1da177e4 LT |
727 | |
728 | /* | |
729 | * The page is mapped into the page tables of one or more | |
730 | * processes. Try to unmap it here. | |
731 | */ | |
732 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 733 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
734 | case SWAP_FAIL: |
735 | goto activate_locked; | |
736 | case SWAP_AGAIN: | |
737 | goto keep_locked; | |
b291f000 NP |
738 | case SWAP_MLOCK: |
739 | goto cull_mlocked; | |
1da177e4 LT |
740 | case SWAP_SUCCESS: |
741 | ; /* try to free the page below */ | |
742 | } | |
743 | } | |
744 | ||
745 | if (PageDirty(page)) { | |
dfc8d636 | 746 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 747 | goto keep_locked; |
4dd4b920 | 748 | if (!may_enter_fs) |
1da177e4 | 749 | goto keep_locked; |
52a8363e | 750 | if (!sc->may_writepage) |
1da177e4 LT |
751 | goto keep_locked; |
752 | ||
753 | /* Page is dirty, try to write it out here */ | |
c661b078 | 754 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
755 | case PAGE_KEEP: |
756 | goto keep_locked; | |
757 | case PAGE_ACTIVATE: | |
758 | goto activate_locked; | |
759 | case PAGE_SUCCESS: | |
4dd4b920 | 760 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
761 | goto keep; |
762 | /* | |
763 | * A synchronous write - probably a ramdisk. Go | |
764 | * ahead and try to reclaim the page. | |
765 | */ | |
529ae9aa | 766 | if (!trylock_page(page)) |
1da177e4 LT |
767 | goto keep; |
768 | if (PageDirty(page) || PageWriteback(page)) | |
769 | goto keep_locked; | |
770 | mapping = page_mapping(page); | |
771 | case PAGE_CLEAN: | |
772 | ; /* try to free the page below */ | |
773 | } | |
774 | } | |
775 | ||
776 | /* | |
777 | * If the page has buffers, try to free the buffer mappings | |
778 | * associated with this page. If we succeed we try to free | |
779 | * the page as well. | |
780 | * | |
781 | * We do this even if the page is PageDirty(). | |
782 | * try_to_release_page() does not perform I/O, but it is | |
783 | * possible for a page to have PageDirty set, but it is actually | |
784 | * clean (all its buffers are clean). This happens if the | |
785 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 786 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
787 | * try_to_release_page() will discover that cleanness and will |
788 | * drop the buffers and mark the page clean - it can be freed. | |
789 | * | |
790 | * Rarely, pages can have buffers and no ->mapping. These are | |
791 | * the pages which were not successfully invalidated in | |
792 | * truncate_complete_page(). We try to drop those buffers here | |
793 | * and if that worked, and the page is no longer mapped into | |
794 | * process address space (page_count == 1) it can be freed. | |
795 | * Otherwise, leave the page on the LRU so it is swappable. | |
796 | */ | |
266cf658 | 797 | if (page_has_private(page)) { |
1da177e4 LT |
798 | if (!try_to_release_page(page, sc->gfp_mask)) |
799 | goto activate_locked; | |
e286781d NP |
800 | if (!mapping && page_count(page) == 1) { |
801 | unlock_page(page); | |
802 | if (put_page_testzero(page)) | |
803 | goto free_it; | |
804 | else { | |
805 | /* | |
806 | * rare race with speculative reference. | |
807 | * the speculative reference will free | |
808 | * this page shortly, so we may | |
809 | * increment nr_reclaimed here (and | |
810 | * leave it off the LRU). | |
811 | */ | |
812 | nr_reclaimed++; | |
813 | continue; | |
814 | } | |
815 | } | |
1da177e4 LT |
816 | } |
817 | ||
e286781d | 818 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 819 | goto keep_locked; |
1da177e4 | 820 | |
a978d6f5 NP |
821 | /* |
822 | * At this point, we have no other references and there is | |
823 | * no way to pick any more up (removed from LRU, removed | |
824 | * from pagecache). Can use non-atomic bitops now (and | |
825 | * we obviously don't have to worry about waking up a process | |
826 | * waiting on the page lock, because there are no references. | |
827 | */ | |
828 | __clear_page_locked(page); | |
e286781d | 829 | free_it: |
05ff5137 | 830 | nr_reclaimed++; |
abe4c3b5 MG |
831 | |
832 | /* | |
833 | * Is there need to periodically free_page_list? It would | |
834 | * appear not as the counts should be low | |
835 | */ | |
836 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
837 | continue; |
838 | ||
b291f000 | 839 | cull_mlocked: |
63d6c5ad HD |
840 | if (PageSwapCache(page)) |
841 | try_to_free_swap(page); | |
b291f000 NP |
842 | unlock_page(page); |
843 | putback_lru_page(page); | |
844 | continue; | |
845 | ||
1da177e4 | 846 | activate_locked: |
68a22394 RR |
847 | /* Not a candidate for swapping, so reclaim swap space. */ |
848 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 849 | try_to_free_swap(page); |
894bc310 | 850 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
851 | SetPageActive(page); |
852 | pgactivate++; | |
853 | keep_locked: | |
854 | unlock_page(page); | |
855 | keep: | |
856 | list_add(&page->lru, &ret_pages); | |
b291f000 | 857 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 858 | } |
abe4c3b5 MG |
859 | |
860 | free_page_list(&free_pages); | |
861 | ||
1da177e4 | 862 | list_splice(&ret_pages, page_list); |
f8891e5e | 863 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 864 | return nr_reclaimed; |
1da177e4 LT |
865 | } |
866 | ||
5ad333eb AW |
867 | /* |
868 | * Attempt to remove the specified page from its LRU. Only take this page | |
869 | * if it is of the appropriate PageActive status. Pages which are being | |
870 | * freed elsewhere are also ignored. | |
871 | * | |
872 | * page: page to consider | |
873 | * mode: one of the LRU isolation modes defined above | |
874 | * | |
875 | * returns 0 on success, -ve errno on failure. | |
876 | */ | |
4f98a2fe | 877 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
878 | { |
879 | int ret = -EINVAL; | |
880 | ||
881 | /* Only take pages on the LRU. */ | |
882 | if (!PageLRU(page)) | |
883 | return ret; | |
884 | ||
885 | /* | |
886 | * When checking the active state, we need to be sure we are | |
887 | * dealing with comparible boolean values. Take the logical not | |
888 | * of each. | |
889 | */ | |
890 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
891 | return ret; | |
892 | ||
6c0b1351 | 893 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
894 | return ret; |
895 | ||
894bc310 LS |
896 | /* |
897 | * When this function is being called for lumpy reclaim, we | |
898 | * initially look into all LRU pages, active, inactive and | |
899 | * unevictable; only give shrink_page_list evictable pages. | |
900 | */ | |
901 | if (PageUnevictable(page)) | |
902 | return ret; | |
903 | ||
5ad333eb | 904 | ret = -EBUSY; |
08e552c6 | 905 | |
5ad333eb AW |
906 | if (likely(get_page_unless_zero(page))) { |
907 | /* | |
908 | * Be careful not to clear PageLRU until after we're | |
909 | * sure the page is not being freed elsewhere -- the | |
910 | * page release code relies on it. | |
911 | */ | |
912 | ClearPageLRU(page); | |
913 | ret = 0; | |
914 | } | |
915 | ||
916 | return ret; | |
917 | } | |
918 | ||
1da177e4 LT |
919 | /* |
920 | * zone->lru_lock is heavily contended. Some of the functions that | |
921 | * shrink the lists perform better by taking out a batch of pages | |
922 | * and working on them outside the LRU lock. | |
923 | * | |
924 | * For pagecache intensive workloads, this function is the hottest | |
925 | * spot in the kernel (apart from copy_*_user functions). | |
926 | * | |
927 | * Appropriate locks must be held before calling this function. | |
928 | * | |
929 | * @nr_to_scan: The number of pages to look through on the list. | |
930 | * @src: The LRU list to pull pages off. | |
931 | * @dst: The temp list to put pages on to. | |
932 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
933 | * @order: The caller's attempted allocation order |
934 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 935 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
936 | * |
937 | * returns how many pages were moved onto *@dst. | |
938 | */ | |
69e05944 AM |
939 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
940 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 941 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 942 | { |
69e05944 | 943 | unsigned long nr_taken = 0; |
a8a94d15 MG |
944 | unsigned long nr_lumpy_taken = 0; |
945 | unsigned long nr_lumpy_dirty = 0; | |
946 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 947 | unsigned long scan; |
1da177e4 | 948 | |
c9b02d97 | 949 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
950 | struct page *page; |
951 | unsigned long pfn; | |
952 | unsigned long end_pfn; | |
953 | unsigned long page_pfn; | |
954 | int zone_id; | |
955 | ||
1da177e4 LT |
956 | page = lru_to_page(src); |
957 | prefetchw_prev_lru_page(page, src, flags); | |
958 | ||
725d704e | 959 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 960 | |
4f98a2fe | 961 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
962 | case 0: |
963 | list_move(&page->lru, dst); | |
2ffebca6 | 964 | mem_cgroup_del_lru(page); |
7c8ee9a8 | 965 | nr_taken++; |
5ad333eb AW |
966 | break; |
967 | ||
968 | case -EBUSY: | |
969 | /* else it is being freed elsewhere */ | |
970 | list_move(&page->lru, src); | |
2ffebca6 | 971 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 972 | continue; |
46453a6e | 973 | |
5ad333eb AW |
974 | default: |
975 | BUG(); | |
976 | } | |
977 | ||
978 | if (!order) | |
979 | continue; | |
980 | ||
981 | /* | |
982 | * Attempt to take all pages in the order aligned region | |
983 | * surrounding the tag page. Only take those pages of | |
984 | * the same active state as that tag page. We may safely | |
985 | * round the target page pfn down to the requested order | |
986 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
987 | * where that page is in a different zone we will detect | |
988 | * it from its zone id and abort this block scan. | |
989 | */ | |
990 | zone_id = page_zone_id(page); | |
991 | page_pfn = page_to_pfn(page); | |
992 | pfn = page_pfn & ~((1 << order) - 1); | |
993 | end_pfn = pfn + (1 << order); | |
994 | for (; pfn < end_pfn; pfn++) { | |
995 | struct page *cursor_page; | |
996 | ||
997 | /* The target page is in the block, ignore it. */ | |
998 | if (unlikely(pfn == page_pfn)) | |
999 | continue; | |
1000 | ||
1001 | /* Avoid holes within the zone. */ | |
1002 | if (unlikely(!pfn_valid_within(pfn))) | |
1003 | break; | |
1004 | ||
1005 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1006 | |
5ad333eb AW |
1007 | /* Check that we have not crossed a zone boundary. */ |
1008 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
1009 | continue; | |
de2e7567 MK |
1010 | |
1011 | /* | |
1012 | * If we don't have enough swap space, reclaiming of | |
1013 | * anon page which don't already have a swap slot is | |
1014 | * pointless. | |
1015 | */ | |
1016 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
1017 | !PageSwapCache(cursor_page)) | |
1018 | continue; | |
1019 | ||
ee993b13 | 1020 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1021 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1022 | mem_cgroup_del_lru(cursor_page); |
5ad333eb | 1023 | nr_taken++; |
a8a94d15 MG |
1024 | nr_lumpy_taken++; |
1025 | if (PageDirty(cursor_page)) | |
1026 | nr_lumpy_dirty++; | |
5ad333eb | 1027 | scan++; |
a8a94d15 MG |
1028 | } else { |
1029 | if (mode == ISOLATE_BOTH && | |
1030 | page_count(cursor_page)) | |
1031 | nr_lumpy_failed++; | |
5ad333eb AW |
1032 | } |
1033 | } | |
1da177e4 LT |
1034 | } |
1035 | ||
1036 | *scanned = scan; | |
a8a94d15 MG |
1037 | |
1038 | trace_mm_vmscan_lru_isolate(order, | |
1039 | nr_to_scan, scan, | |
1040 | nr_taken, | |
1041 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1042 | mode); | |
1da177e4 LT |
1043 | return nr_taken; |
1044 | } | |
1045 | ||
66e1707b BS |
1046 | static unsigned long isolate_pages_global(unsigned long nr, |
1047 | struct list_head *dst, | |
1048 | unsigned long *scanned, int order, | |
1049 | int mode, struct zone *z, | |
4f98a2fe | 1050 | int active, int file) |
66e1707b | 1051 | { |
4f98a2fe | 1052 | int lru = LRU_BASE; |
66e1707b | 1053 | if (active) |
4f98a2fe RR |
1054 | lru += LRU_ACTIVE; |
1055 | if (file) | |
1056 | lru += LRU_FILE; | |
1057 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1058 | mode, file); |
66e1707b BS |
1059 | } |
1060 | ||
5ad333eb AW |
1061 | /* |
1062 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1063 | * any active bits from the pages in the list. | |
1064 | */ | |
4f98a2fe RR |
1065 | static unsigned long clear_active_flags(struct list_head *page_list, |
1066 | unsigned int *count) | |
5ad333eb AW |
1067 | { |
1068 | int nr_active = 0; | |
4f98a2fe | 1069 | int lru; |
5ad333eb AW |
1070 | struct page *page; |
1071 | ||
4f98a2fe | 1072 | list_for_each_entry(page, page_list, lru) { |
401a8e1c | 1073 | lru = page_lru_base_type(page); |
5ad333eb | 1074 | if (PageActive(page)) { |
4f98a2fe | 1075 | lru += LRU_ACTIVE; |
5ad333eb AW |
1076 | ClearPageActive(page); |
1077 | nr_active++; | |
1078 | } | |
1489fa14 MG |
1079 | if (count) |
1080 | count[lru]++; | |
4f98a2fe | 1081 | } |
5ad333eb AW |
1082 | |
1083 | return nr_active; | |
1084 | } | |
1085 | ||
62695a84 NP |
1086 | /** |
1087 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1088 | * @page: page to isolate from its LRU list | |
1089 | * | |
1090 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1091 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1092 | * | |
1093 | * Returns 0 if the page was removed from an LRU list. | |
1094 | * Returns -EBUSY if the page was not on an LRU list. | |
1095 | * | |
1096 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1097 | * the active list, it will have PageActive set. If it was found on |
1098 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1099 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1100 | * |
1101 | * The vmstat statistic corresponding to the list on which the page was | |
1102 | * found will be decremented. | |
1103 | * | |
1104 | * Restrictions: | |
1105 | * (1) Must be called with an elevated refcount on the page. This is a | |
1106 | * fundamentnal difference from isolate_lru_pages (which is called | |
1107 | * without a stable reference). | |
1108 | * (2) the lru_lock must not be held. | |
1109 | * (3) interrupts must be enabled. | |
1110 | */ | |
1111 | int isolate_lru_page(struct page *page) | |
1112 | { | |
1113 | int ret = -EBUSY; | |
1114 | ||
1115 | if (PageLRU(page)) { | |
1116 | struct zone *zone = page_zone(page); | |
1117 | ||
1118 | spin_lock_irq(&zone->lru_lock); | |
1119 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1120 | int lru = page_lru(page); |
62695a84 NP |
1121 | ret = 0; |
1122 | ClearPageLRU(page); | |
4f98a2fe | 1123 | |
4f98a2fe | 1124 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1125 | } |
1126 | spin_unlock_irq(&zone->lru_lock); | |
1127 | } | |
1128 | return ret; | |
1129 | } | |
1130 | ||
35cd7815 RR |
1131 | /* |
1132 | * Are there way too many processes in the direct reclaim path already? | |
1133 | */ | |
1134 | static int too_many_isolated(struct zone *zone, int file, | |
1135 | struct scan_control *sc) | |
1136 | { | |
1137 | unsigned long inactive, isolated; | |
1138 | ||
1139 | if (current_is_kswapd()) | |
1140 | return 0; | |
1141 | ||
1142 | if (!scanning_global_lru(sc)) | |
1143 | return 0; | |
1144 | ||
1145 | if (file) { | |
1146 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1147 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1148 | } else { | |
1149 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1150 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1151 | } | |
1152 | ||
1153 | return isolated > inactive; | |
1154 | } | |
1155 | ||
66635629 MG |
1156 | /* |
1157 | * TODO: Try merging with migrations version of putback_lru_pages | |
1158 | */ | |
1159 | static noinline_for_stack void | |
1489fa14 | 1160 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1161 | unsigned long nr_anon, unsigned long nr_file, |
1162 | struct list_head *page_list) | |
1163 | { | |
1164 | struct page *page; | |
1165 | struct pagevec pvec; | |
1489fa14 | 1166 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1167 | |
1168 | pagevec_init(&pvec, 1); | |
1169 | ||
1170 | /* | |
1171 | * Put back any unfreeable pages. | |
1172 | */ | |
1173 | spin_lock(&zone->lru_lock); | |
1174 | while (!list_empty(page_list)) { | |
1175 | int lru; | |
1176 | page = lru_to_page(page_list); | |
1177 | VM_BUG_ON(PageLRU(page)); | |
1178 | list_del(&page->lru); | |
1179 | if (unlikely(!page_evictable(page, NULL))) { | |
1180 | spin_unlock_irq(&zone->lru_lock); | |
1181 | putback_lru_page(page); | |
1182 | spin_lock_irq(&zone->lru_lock); | |
1183 | continue; | |
1184 | } | |
1185 | SetPageLRU(page); | |
1186 | lru = page_lru(page); | |
1187 | add_page_to_lru_list(zone, page, lru); | |
1188 | if (is_active_lru(lru)) { | |
1189 | int file = is_file_lru(lru); | |
1190 | reclaim_stat->recent_rotated[file]++; | |
1191 | } | |
1192 | if (!pagevec_add(&pvec, page)) { | |
1193 | spin_unlock_irq(&zone->lru_lock); | |
1194 | __pagevec_release(&pvec); | |
1195 | spin_lock_irq(&zone->lru_lock); | |
1196 | } | |
1197 | } | |
1198 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1199 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1200 | ||
1201 | spin_unlock_irq(&zone->lru_lock); | |
1202 | pagevec_release(&pvec); | |
1203 | } | |
1204 | ||
1489fa14 MG |
1205 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1206 | struct scan_control *sc, | |
1207 | unsigned long *nr_anon, | |
1208 | unsigned long *nr_file, | |
1209 | struct list_head *isolated_list) | |
1210 | { | |
1211 | unsigned long nr_active; | |
1212 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1213 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1214 | ||
1215 | nr_active = clear_active_flags(isolated_list, count); | |
1216 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1217 | ||
1218 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1219 | -count[LRU_ACTIVE_FILE]); | |
1220 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1221 | -count[LRU_INACTIVE_FILE]); | |
1222 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1223 | -count[LRU_ACTIVE_ANON]); | |
1224 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1225 | -count[LRU_INACTIVE_ANON]); | |
1226 | ||
1227 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1228 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1229 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1230 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1231 | ||
1232 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1233 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1234 | } | |
1235 | ||
1da177e4 | 1236 | /* |
1742f19f AM |
1237 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1238 | * of reclaimed pages | |
1da177e4 | 1239 | */ |
66635629 MG |
1240 | static noinline_for_stack unsigned long |
1241 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1242 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1243 | { |
1244 | LIST_HEAD(page_list); | |
e247dbce | 1245 | unsigned long nr_scanned; |
05ff5137 | 1246 | unsigned long nr_reclaimed = 0; |
e247dbce KM |
1247 | unsigned long nr_taken; |
1248 | unsigned long nr_active; | |
e247dbce KM |
1249 | unsigned long nr_anon; |
1250 | unsigned long nr_file; | |
78dc583d | 1251 | |
35cd7815 | 1252 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1253 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1254 | |
1255 | /* We are about to die and free our memory. Return now. */ | |
1256 | if (fatal_signal_pending(current)) | |
1257 | return SWAP_CLUSTER_MAX; | |
1258 | } | |
1259 | ||
1da177e4 | 1260 | |
1da177e4 LT |
1261 | lru_add_drain(); |
1262 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1263 | |
e247dbce KM |
1264 | if (scanning_global_lru(sc)) { |
1265 | nr_taken = isolate_pages_global(nr_to_scan, | |
1266 | &page_list, &nr_scanned, sc->order, | |
1267 | sc->lumpy_reclaim_mode ? | |
1268 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
1269 | zone, 0, file); | |
1270 | zone->pages_scanned += nr_scanned; | |
1271 | if (current_is_kswapd()) | |
1272 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1273 | nr_scanned); | |
1274 | else | |
1275 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1276 | nr_scanned); | |
1277 | } else { | |
1278 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1279 | &page_list, &nr_scanned, sc->order, | |
1280 | sc->lumpy_reclaim_mode ? | |
1281 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
1282 | zone, sc->mem_cgroup, | |
1283 | 0, file); | |
1284 | /* | |
1285 | * mem_cgroup_isolate_pages() keeps track of | |
1286 | * scanned pages on its own. | |
1287 | */ | |
1288 | } | |
b35ea17b | 1289 | |
66635629 MG |
1290 | if (nr_taken == 0) { |
1291 | spin_unlock_irq(&zone->lru_lock); | |
1292 | return 0; | |
1293 | } | |
5ad333eb | 1294 | |
1489fa14 | 1295 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1296 | |
e247dbce | 1297 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1298 | |
e247dbce | 1299 | nr_reclaimed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
c661b078 | 1300 | |
e247dbce KM |
1301 | /* |
1302 | * If we are direct reclaiming for contiguous pages and we do | |
1303 | * not reclaim everything in the list, try again and wait | |
1304 | * for IO to complete. This will stall high-order allocations | |
1305 | * but that should be acceptable to the caller | |
1306 | */ | |
1307 | if (nr_reclaimed < nr_taken && !current_is_kswapd() && | |
1308 | sc->lumpy_reclaim_mode) { | |
1309 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
c661b078 | 1310 | |
e247dbce KM |
1311 | /* |
1312 | * The attempt at page out may have made some | |
1313 | * of the pages active, mark them inactive again. | |
1314 | */ | |
1489fa14 | 1315 | nr_active = clear_active_flags(&page_list, NULL); |
e247dbce | 1316 | count_vm_events(PGDEACTIVATE, nr_active); |
c661b078 | 1317 | |
e247dbce KM |
1318 | nr_reclaimed += shrink_page_list(&page_list, sc, PAGEOUT_IO_SYNC); |
1319 | } | |
b35ea17b | 1320 | |
e247dbce KM |
1321 | local_irq_disable(); |
1322 | if (current_is_kswapd()) | |
1323 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1324 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1325 | |
1489fa14 | 1326 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
05ff5137 | 1327 | return nr_reclaimed; |
1da177e4 LT |
1328 | } |
1329 | ||
1330 | /* | |
1331 | * This moves pages from the active list to the inactive list. | |
1332 | * | |
1333 | * We move them the other way if the page is referenced by one or more | |
1334 | * processes, from rmap. | |
1335 | * | |
1336 | * If the pages are mostly unmapped, the processing is fast and it is | |
1337 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1338 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1339 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1340 | * this, so instead we remove the pages from the LRU while processing them. | |
1341 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1342 | * nobody will play with that bit on a non-LRU page. | |
1343 | * | |
1344 | * The downside is that we have to touch page->_count against each page. | |
1345 | * But we had to alter page->flags anyway. | |
1346 | */ | |
1cfb419b | 1347 | |
3eb4140f WF |
1348 | static void move_active_pages_to_lru(struct zone *zone, |
1349 | struct list_head *list, | |
1350 | enum lru_list lru) | |
1351 | { | |
1352 | unsigned long pgmoved = 0; | |
1353 | struct pagevec pvec; | |
1354 | struct page *page; | |
1355 | ||
1356 | pagevec_init(&pvec, 1); | |
1357 | ||
1358 | while (!list_empty(list)) { | |
1359 | page = lru_to_page(list); | |
3eb4140f WF |
1360 | |
1361 | VM_BUG_ON(PageLRU(page)); | |
1362 | SetPageLRU(page); | |
1363 | ||
3eb4140f WF |
1364 | list_move(&page->lru, &zone->lru[lru].list); |
1365 | mem_cgroup_add_lru_list(page, lru); | |
1366 | pgmoved++; | |
1367 | ||
1368 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1369 | spin_unlock_irq(&zone->lru_lock); | |
1370 | if (buffer_heads_over_limit) | |
1371 | pagevec_strip(&pvec); | |
1372 | __pagevec_release(&pvec); | |
1373 | spin_lock_irq(&zone->lru_lock); | |
1374 | } | |
1375 | } | |
1376 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1377 | if (!is_active_lru(lru)) | |
1378 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1379 | } | |
1cfb419b | 1380 | |
1742f19f | 1381 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1382 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1383 | { |
44c241f1 | 1384 | unsigned long nr_taken; |
69e05944 | 1385 | unsigned long pgscanned; |
6fe6b7e3 | 1386 | unsigned long vm_flags; |
1da177e4 | 1387 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1388 | LIST_HEAD(l_active); |
b69408e8 | 1389 | LIST_HEAD(l_inactive); |
1da177e4 | 1390 | struct page *page; |
6e901571 | 1391 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1392 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1393 | |
1394 | lru_add_drain(); | |
1395 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1396 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1397 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1398 | &pgscanned, sc->order, | |
1399 | ISOLATE_ACTIVE, zone, | |
1400 | 1, file); | |
1cfb419b | 1401 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1402 | } else { |
1403 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1404 | &pgscanned, sc->order, | |
1405 | ISOLATE_ACTIVE, zone, | |
1406 | sc->mem_cgroup, 1, file); | |
1407 | /* | |
1408 | * mem_cgroup_isolate_pages() keeps track of | |
1409 | * scanned pages on its own. | |
1410 | */ | |
4f98a2fe | 1411 | } |
8b25c6d2 | 1412 | |
b7c46d15 | 1413 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1414 | |
3eb4140f | 1415 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1416 | if (file) |
44c241f1 | 1417 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1418 | else |
44c241f1 | 1419 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1420 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1421 | spin_unlock_irq(&zone->lru_lock); |
1422 | ||
1da177e4 LT |
1423 | while (!list_empty(&l_hold)) { |
1424 | cond_resched(); | |
1425 | page = lru_to_page(&l_hold); | |
1426 | list_del(&page->lru); | |
7e9cd484 | 1427 | |
894bc310 LS |
1428 | if (unlikely(!page_evictable(page, NULL))) { |
1429 | putback_lru_page(page); | |
1430 | continue; | |
1431 | } | |
1432 | ||
64574746 | 1433 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
44c241f1 | 1434 | nr_rotated++; |
8cab4754 WF |
1435 | /* |
1436 | * Identify referenced, file-backed active pages and | |
1437 | * give them one more trip around the active list. So | |
1438 | * that executable code get better chances to stay in | |
1439 | * memory under moderate memory pressure. Anon pages | |
1440 | * are not likely to be evicted by use-once streaming | |
1441 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1442 | * so we ignore them here. | |
1443 | */ | |
41e20983 | 1444 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1445 | list_add(&page->lru, &l_active); |
1446 | continue; | |
1447 | } | |
1448 | } | |
7e9cd484 | 1449 | |
5205e56e | 1450 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1451 | list_add(&page->lru, &l_inactive); |
1452 | } | |
1453 | ||
b555749a | 1454 | /* |
8cab4754 | 1455 | * Move pages back to the lru list. |
b555749a | 1456 | */ |
2a1dc509 | 1457 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1458 | /* |
8cab4754 WF |
1459 | * Count referenced pages from currently used mappings as rotated, |
1460 | * even though only some of them are actually re-activated. This | |
1461 | * helps balance scan pressure between file and anonymous pages in | |
1462 | * get_scan_ratio. | |
7e9cd484 | 1463 | */ |
b7c46d15 | 1464 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1465 | |
3eb4140f WF |
1466 | move_active_pages_to_lru(zone, &l_active, |
1467 | LRU_ACTIVE + file * LRU_FILE); | |
1468 | move_active_pages_to_lru(zone, &l_inactive, | |
1469 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1470 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1471 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1472 | } |
1473 | ||
14797e23 | 1474 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1475 | { |
1476 | unsigned long active, inactive; | |
1477 | ||
1478 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1479 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1480 | ||
1481 | if (inactive * zone->inactive_ratio < active) | |
1482 | return 1; | |
1483 | ||
1484 | return 0; | |
1485 | } | |
1486 | ||
14797e23 KM |
1487 | /** |
1488 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1489 | * @zone: zone to check | |
1490 | * @sc: scan control of this context | |
1491 | * | |
1492 | * Returns true if the zone does not have enough inactive anon pages, | |
1493 | * meaning some active anon pages need to be deactivated. | |
1494 | */ | |
1495 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1496 | { | |
1497 | int low; | |
1498 | ||
e72e2bd6 | 1499 | if (scanning_global_lru(sc)) |
14797e23 KM |
1500 | low = inactive_anon_is_low_global(zone); |
1501 | else | |
c772be93 | 1502 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1503 | return low; |
1504 | } | |
1505 | ||
56e49d21 RR |
1506 | static int inactive_file_is_low_global(struct zone *zone) |
1507 | { | |
1508 | unsigned long active, inactive; | |
1509 | ||
1510 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1511 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1512 | ||
1513 | return (active > inactive); | |
1514 | } | |
1515 | ||
1516 | /** | |
1517 | * inactive_file_is_low - check if file pages need to be deactivated | |
1518 | * @zone: zone to check | |
1519 | * @sc: scan control of this context | |
1520 | * | |
1521 | * When the system is doing streaming IO, memory pressure here | |
1522 | * ensures that active file pages get deactivated, until more | |
1523 | * than half of the file pages are on the inactive list. | |
1524 | * | |
1525 | * Once we get to that situation, protect the system's working | |
1526 | * set from being evicted by disabling active file page aging. | |
1527 | * | |
1528 | * This uses a different ratio than the anonymous pages, because | |
1529 | * the page cache uses a use-once replacement algorithm. | |
1530 | */ | |
1531 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1532 | { | |
1533 | int low; | |
1534 | ||
1535 | if (scanning_global_lru(sc)) | |
1536 | low = inactive_file_is_low_global(zone); | |
1537 | else | |
1538 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1539 | return low; | |
1540 | } | |
1541 | ||
b39415b2 RR |
1542 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1543 | int file) | |
1544 | { | |
1545 | if (file) | |
1546 | return inactive_file_is_low(zone, sc); | |
1547 | else | |
1548 | return inactive_anon_is_low(zone, sc); | |
1549 | } | |
1550 | ||
4f98a2fe | 1551 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1552 | struct zone *zone, struct scan_control *sc, int priority) |
1553 | { | |
4f98a2fe RR |
1554 | int file = is_file_lru(lru); |
1555 | ||
b39415b2 RR |
1556 | if (is_active_lru(lru)) { |
1557 | if (inactive_list_is_low(zone, sc, file)) | |
1558 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1559 | return 0; |
1560 | } | |
1561 | ||
33c120ed | 1562 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1563 | } |
1564 | ||
76a33fc3 SL |
1565 | /* |
1566 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1567 | * until we collected @swap_cluster_max pages to scan. | |
1568 | */ | |
1569 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1570 | unsigned long *nr_saved_scan) | |
1571 | { | |
1572 | unsigned long nr; | |
1573 | ||
1574 | *nr_saved_scan += nr_to_scan; | |
1575 | nr = *nr_saved_scan; | |
1576 | ||
1577 | if (nr >= SWAP_CLUSTER_MAX) | |
1578 | *nr_saved_scan = 0; | |
1579 | else | |
1580 | nr = 0; | |
1581 | ||
1582 | return nr; | |
1583 | } | |
1584 | ||
4f98a2fe RR |
1585 | /* |
1586 | * Determine how aggressively the anon and file LRU lists should be | |
1587 | * scanned. The relative value of each set of LRU lists is determined | |
1588 | * by looking at the fraction of the pages scanned we did rotate back | |
1589 | * onto the active list instead of evict. | |
1590 | * | |
76a33fc3 | 1591 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1592 | */ |
76a33fc3 SL |
1593 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1594 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1595 | { |
1596 | unsigned long anon, file, free; | |
1597 | unsigned long anon_prio, file_prio; | |
1598 | unsigned long ap, fp; | |
6e901571 | 1599 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1600 | u64 fraction[2], denominator; |
1601 | enum lru_list l; | |
1602 | int noswap = 0; | |
1603 | ||
1604 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1605 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1606 | noswap = 1; | |
1607 | fraction[0] = 0; | |
1608 | fraction[1] = 1; | |
1609 | denominator = 1; | |
1610 | goto out; | |
1611 | } | |
4f98a2fe | 1612 | |
0b217676 VL |
1613 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1614 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1615 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1616 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1617 | |
e72e2bd6 | 1618 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1619 | free = zone_page_state(zone, NR_FREE_PAGES); |
1620 | /* If we have very few page cache pages, | |
1621 | force-scan anon pages. */ | |
41858966 | 1622 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1623 | fraction[0] = 1; |
1624 | fraction[1] = 0; | |
1625 | denominator = 1; | |
1626 | goto out; | |
eeee9a8c | 1627 | } |
4f98a2fe RR |
1628 | } |
1629 | ||
1630 | /* | |
1631 | * OK, so we have swap space and a fair amount of page cache | |
1632 | * pages. We use the recently rotated / recently scanned | |
1633 | * ratios to determine how valuable each cache is. | |
1634 | * | |
1635 | * Because workloads change over time (and to avoid overflow) | |
1636 | * we keep these statistics as a floating average, which ends | |
1637 | * up weighing recent references more than old ones. | |
1638 | * | |
1639 | * anon in [0], file in [1] | |
1640 | */ | |
6e901571 | 1641 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
4f98a2fe | 1642 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1643 | reclaim_stat->recent_scanned[0] /= 2; |
1644 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1645 | spin_unlock_irq(&zone->lru_lock); |
1646 | } | |
1647 | ||
6e901571 | 1648 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
4f98a2fe | 1649 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1650 | reclaim_stat->recent_scanned[1] /= 2; |
1651 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1652 | spin_unlock_irq(&zone->lru_lock); |
1653 | } | |
1654 | ||
1655 | /* | |
1656 | * With swappiness at 100, anonymous and file have the same priority. | |
1657 | * This scanning priority is essentially the inverse of IO cost. | |
1658 | */ | |
1659 | anon_prio = sc->swappiness; | |
1660 | file_prio = 200 - sc->swappiness; | |
1661 | ||
1662 | /* | |
00d8089c RR |
1663 | * The amount of pressure on anon vs file pages is inversely |
1664 | * proportional to the fraction of recently scanned pages on | |
1665 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1666 | */ |
6e901571 KM |
1667 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1668 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1669 | |
6e901571 KM |
1670 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1671 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
4f98a2fe | 1672 | |
76a33fc3 SL |
1673 | fraction[0] = ap; |
1674 | fraction[1] = fp; | |
1675 | denominator = ap + fp + 1; | |
1676 | out: | |
1677 | for_each_evictable_lru(l) { | |
1678 | int file = is_file_lru(l); | |
1679 | unsigned long scan; | |
6e08a369 | 1680 | |
76a33fc3 SL |
1681 | scan = zone_nr_lru_pages(zone, sc, l); |
1682 | if (priority || noswap) { | |
1683 | scan >>= priority; | |
1684 | scan = div64_u64(scan * fraction[file], denominator); | |
1685 | } | |
1686 | nr[l] = nr_scan_try_batch(scan, | |
1687 | &reclaim_stat->nr_saved_scan[l]); | |
1688 | } | |
6e08a369 | 1689 | } |
4f98a2fe | 1690 | |
5f53e762 KM |
1691 | static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc) |
1692 | { | |
1693 | /* | |
1694 | * If we need a large contiguous chunk of memory, or have | |
1695 | * trouble getting a small set of contiguous pages, we | |
1696 | * will reclaim both active and inactive pages. | |
1697 | */ | |
1698 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1699 | sc->lumpy_reclaim_mode = 1; | |
1700 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1701 | sc->lumpy_reclaim_mode = 1; | |
1702 | else | |
1703 | sc->lumpy_reclaim_mode = 0; | |
1704 | } | |
1705 | ||
1da177e4 LT |
1706 | /* |
1707 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1708 | */ | |
a79311c1 | 1709 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1710 | struct scan_control *sc) |
1da177e4 | 1711 | { |
b69408e8 | 1712 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1713 | unsigned long nr_to_scan; |
b69408e8 | 1714 | enum lru_list l; |
01dbe5c9 | 1715 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
22fba335 | 1716 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1717 | |
76a33fc3 | 1718 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1719 | |
5f53e762 KM |
1720 | set_lumpy_reclaim_mode(priority, sc); |
1721 | ||
556adecb RR |
1722 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1723 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1724 | for_each_evictable_lru(l) { |
b69408e8 | 1725 | if (nr[l]) { |
ece74b2e KM |
1726 | nr_to_scan = min_t(unsigned long, |
1727 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1728 | nr[l] -= nr_to_scan; |
1da177e4 | 1729 | |
01dbe5c9 KM |
1730 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1731 | zone, sc, priority); | |
b69408e8 | 1732 | } |
1da177e4 | 1733 | } |
a79311c1 RR |
1734 | /* |
1735 | * On large memory systems, scan >> priority can become | |
1736 | * really large. This is fine for the starting priority; | |
1737 | * we want to put equal scanning pressure on each zone. | |
1738 | * However, if the VM has a harder time of freeing pages, | |
1739 | * with multiple processes reclaiming pages, the total | |
1740 | * freeing target can get unreasonably large. | |
1741 | */ | |
338fde90 | 1742 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1743 | break; |
1da177e4 LT |
1744 | } |
1745 | ||
01dbe5c9 KM |
1746 | sc->nr_reclaimed = nr_reclaimed; |
1747 | ||
556adecb RR |
1748 | /* |
1749 | * Even if we did not try to evict anon pages at all, we want to | |
1750 | * rebalance the anon lru active/inactive ratio. | |
1751 | */ | |
69c85481 | 1752 | if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) |
556adecb RR |
1753 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1754 | ||
232ea4d6 | 1755 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1756 | } |
1757 | ||
1758 | /* | |
1759 | * This is the direct reclaim path, for page-allocating processes. We only | |
1760 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1761 | * request. | |
1762 | * | |
41858966 MG |
1763 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1764 | * Because: | |
1da177e4 LT |
1765 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1766 | * allocation or | |
41858966 MG |
1767 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1768 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1769 | * zone defense algorithm. | |
1da177e4 | 1770 | * |
1da177e4 LT |
1771 | * If a zone is deemed to be full of pinned pages then just give it a light |
1772 | * scan then give up on it. | |
1773 | */ | |
bb21c7ce | 1774 | static bool shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1775 | struct scan_control *sc) |
1da177e4 | 1776 | { |
dd1a239f | 1777 | struct zoneref *z; |
54a6eb5c | 1778 | struct zone *zone; |
bb21c7ce | 1779 | bool all_unreclaimable = true; |
1cfb419b | 1780 | |
d4debc66 MG |
1781 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1782 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1783 | if (!populated_zone(zone)) |
1da177e4 | 1784 | continue; |
1cfb419b KH |
1785 | /* |
1786 | * Take care memory controller reclaiming has small influence | |
1787 | * to global LRU. | |
1788 | */ | |
e72e2bd6 | 1789 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1790 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1791 | continue; | |
93e4a89a | 1792 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1793 | continue; /* Let kswapd poll it */ |
1cfb419b | 1794 | } |
408d8544 | 1795 | |
a79311c1 | 1796 | shrink_zone(priority, zone, sc); |
bb21c7ce | 1797 | all_unreclaimable = false; |
1da177e4 | 1798 | } |
bb21c7ce | 1799 | return all_unreclaimable; |
1da177e4 | 1800 | } |
4f98a2fe | 1801 | |
1da177e4 LT |
1802 | /* |
1803 | * This is the main entry point to direct page reclaim. | |
1804 | * | |
1805 | * If a full scan of the inactive list fails to free enough memory then we | |
1806 | * are "out of memory" and something needs to be killed. | |
1807 | * | |
1808 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1809 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
1810 | * caller can't do much about. We kick the writeback threads and take explicit |
1811 | * naps in the hope that some of these pages can be written. But if the | |
1812 | * allocating task holds filesystem locks which prevent writeout this might not | |
1813 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
1814 | * |
1815 | * returns: 0, if no pages reclaimed | |
1816 | * else, the number of pages reclaimed | |
1da177e4 | 1817 | */ |
dac1d27b | 1818 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1819 | struct scan_control *sc) |
1da177e4 LT |
1820 | { |
1821 | int priority; | |
bb21c7ce | 1822 | bool all_unreclaimable; |
69e05944 | 1823 | unsigned long total_scanned = 0; |
1da177e4 | 1824 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 1825 | struct zoneref *z; |
54a6eb5c | 1826 | struct zone *zone; |
22fba335 | 1827 | unsigned long writeback_threshold; |
1da177e4 | 1828 | |
c0ff7453 | 1829 | get_mems_allowed(); |
873b4771 KK |
1830 | delayacct_freepages_start(); |
1831 | ||
e72e2bd6 | 1832 | if (scanning_global_lru(sc)) |
1cfb419b | 1833 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
1834 | |
1835 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1836 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1837 | if (!priority) |
1838 | disable_swap_token(); | |
bb21c7ce | 1839 | all_unreclaimable = shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1840 | /* |
1841 | * Don't shrink slabs when reclaiming memory from | |
1842 | * over limit cgroups | |
1843 | */ | |
e72e2bd6 | 1844 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 1845 | unsigned long lru_pages = 0; |
d4debc66 MG |
1846 | for_each_zone_zonelist(zone, z, zonelist, |
1847 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
1848 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1849 | continue; | |
1850 | ||
1851 | lru_pages += zone_reclaimable_pages(zone); | |
1852 | } | |
1853 | ||
dd1a239f | 1854 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1855 | if (reclaim_state) { |
a79311c1 | 1856 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1857 | reclaim_state->reclaimed_slab = 0; |
1858 | } | |
1da177e4 | 1859 | } |
66e1707b | 1860 | total_scanned += sc->nr_scanned; |
bb21c7ce | 1861 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 1862 | goto out; |
1da177e4 LT |
1863 | |
1864 | /* | |
1865 | * Try to write back as many pages as we just scanned. This | |
1866 | * tends to cause slow streaming writers to write data to the | |
1867 | * disk smoothly, at the dirtying rate, which is nice. But | |
1868 | * that's undesirable in laptop mode, where we *want* lumpy | |
1869 | * writeout. So in laptop mode, write out the whole world. | |
1870 | */ | |
22fba335 KM |
1871 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
1872 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 1873 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 1874 | sc->may_writepage = 1; |
1da177e4 LT |
1875 | } |
1876 | ||
1877 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c KM |
1878 | if (!sc->hibernation_mode && sc->nr_scanned && |
1879 | priority < DEF_PRIORITY - 2) | |
8aa7e847 | 1880 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1da177e4 | 1881 | } |
bb21c7ce | 1882 | |
1da177e4 | 1883 | out: |
3bb1a852 MB |
1884 | /* |
1885 | * Now that we've scanned all the zones at this priority level, note | |
1886 | * that level within the zone so that the next thread which performs | |
1887 | * scanning of this zone will immediately start out at this priority | |
1888 | * level. This affects only the decision whether or not to bring | |
1889 | * mapped pages onto the inactive list. | |
1890 | */ | |
1891 | if (priority < 0) | |
1892 | priority = 0; | |
1da177e4 | 1893 | |
873b4771 | 1894 | delayacct_freepages_end(); |
c0ff7453 | 1895 | put_mems_allowed(); |
873b4771 | 1896 | |
bb21c7ce KM |
1897 | if (sc->nr_reclaimed) |
1898 | return sc->nr_reclaimed; | |
1899 | ||
1900 | /* top priority shrink_zones still had more to do? don't OOM, then */ | |
1901 | if (scanning_global_lru(sc) && !all_unreclaimable) | |
1902 | return 1; | |
1903 | ||
1904 | return 0; | |
1da177e4 LT |
1905 | } |
1906 | ||
dac1d27b | 1907 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 1908 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 1909 | { |
33906bc5 | 1910 | unsigned long nr_reclaimed; |
66e1707b BS |
1911 | struct scan_control sc = { |
1912 | .gfp_mask = gfp_mask, | |
1913 | .may_writepage = !laptop_mode, | |
22fba335 | 1914 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 1915 | .may_unmap = 1, |
2e2e4259 | 1916 | .may_swap = 1, |
66e1707b BS |
1917 | .swappiness = vm_swappiness, |
1918 | .order = order, | |
1919 | .mem_cgroup = NULL, | |
327c0e96 | 1920 | .nodemask = nodemask, |
66e1707b BS |
1921 | }; |
1922 | ||
33906bc5 MG |
1923 | trace_mm_vmscan_direct_reclaim_begin(order, |
1924 | sc.may_writepage, | |
1925 | gfp_mask); | |
1926 | ||
1927 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
1928 | ||
1929 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
1930 | ||
1931 | return nr_reclaimed; | |
66e1707b BS |
1932 | } |
1933 | ||
00f0b825 | 1934 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1935 | |
4e416953 BS |
1936 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
1937 | gfp_t gfp_mask, bool noswap, | |
1938 | unsigned int swappiness, | |
1939 | struct zone *zone, int nid) | |
1940 | { | |
1941 | struct scan_control sc = { | |
1942 | .may_writepage = !laptop_mode, | |
1943 | .may_unmap = 1, | |
1944 | .may_swap = !noswap, | |
4e416953 BS |
1945 | .swappiness = swappiness, |
1946 | .order = 0, | |
1947 | .mem_cgroup = mem, | |
4e416953 BS |
1948 | }; |
1949 | nodemask_t nm = nodemask_of_node(nid); | |
1950 | ||
1951 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | | |
1952 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1953 | sc.nodemask = &nm; | |
1954 | sc.nr_reclaimed = 0; | |
1955 | sc.nr_scanned = 0; | |
1956 | /* | |
1957 | * NOTE: Although we can get the priority field, using it | |
1958 | * here is not a good idea, since it limits the pages we can scan. | |
1959 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
1960 | * will pick up pages from other mem cgroup's as well. We hack | |
1961 | * the priority and make it zero. | |
1962 | */ | |
1963 | shrink_zone(0, zone, &sc); | |
1964 | return sc.nr_reclaimed; | |
1965 | } | |
1966 | ||
e1a1cd59 | 1967 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
1968 | gfp_t gfp_mask, |
1969 | bool noswap, | |
1970 | unsigned int swappiness) | |
66e1707b | 1971 | { |
4e416953 | 1972 | struct zonelist *zonelist; |
66e1707b | 1973 | struct scan_control sc = { |
66e1707b | 1974 | .may_writepage = !laptop_mode, |
a6dc60f8 | 1975 | .may_unmap = 1, |
2e2e4259 | 1976 | .may_swap = !noswap, |
22fba335 | 1977 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 1978 | .swappiness = swappiness, |
66e1707b BS |
1979 | .order = 0, |
1980 | .mem_cgroup = mem_cont, | |
327c0e96 | 1981 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 1982 | }; |
66e1707b | 1983 | |
dd1a239f MG |
1984 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1985 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1986 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1987 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1988 | } |
1989 | #endif | |
1990 | ||
f50de2d3 | 1991 | /* is kswapd sleeping prematurely? */ |
bb3ab596 | 1992 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
f50de2d3 | 1993 | { |
bb3ab596 | 1994 | int i; |
f50de2d3 MG |
1995 | |
1996 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
1997 | if (remaining) | |
1998 | return 1; | |
1999 | ||
2000 | /* If after HZ/10, a zone is below the high mark, it's premature */ | |
bb3ab596 KM |
2001 | for (i = 0; i < pgdat->nr_zones; i++) { |
2002 | struct zone *zone = pgdat->node_zones + i; | |
2003 | ||
2004 | if (!populated_zone(zone)) | |
2005 | continue; | |
2006 | ||
93e4a89a | 2007 | if (zone->all_unreclaimable) |
de3fab39 KM |
2008 | continue; |
2009 | ||
f50de2d3 MG |
2010 | if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), |
2011 | 0, 0)) | |
2012 | return 1; | |
bb3ab596 | 2013 | } |
f50de2d3 MG |
2014 | |
2015 | return 0; | |
2016 | } | |
2017 | ||
1da177e4 LT |
2018 | /* |
2019 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2020 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2021 | * |
1da177e4 LT |
2022 | * Returns the number of pages which were actually freed. |
2023 | * | |
2024 | * There is special handling here for zones which are full of pinned pages. | |
2025 | * This can happen if the pages are all mlocked, or if they are all used by | |
2026 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2027 | * What we do is to detect the case where all pages in the zone have been | |
2028 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2029 | * dead and from now on, only perform a short scan. Basically we're polling | |
2030 | * the zone for when the problem goes away. | |
2031 | * | |
2032 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2033 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2034 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2035 | * lower zones regardless of the number of free pages in the lower zones. This | |
2036 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2037 | * of pages is balanced across the zones. | |
1da177e4 | 2038 | */ |
d6277db4 | 2039 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 2040 | { |
1da177e4 LT |
2041 | int all_zones_ok; |
2042 | int priority; | |
2043 | int i; | |
69e05944 | 2044 | unsigned long total_scanned; |
1da177e4 | 2045 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2046 | struct scan_control sc = { |
2047 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2048 | .may_unmap = 1, |
2e2e4259 | 2049 | .may_swap = 1, |
22fba335 KM |
2050 | /* |
2051 | * kswapd doesn't want to be bailed out while reclaim. because | |
2052 | * we want to put equal scanning pressure on each zone. | |
2053 | */ | |
2054 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2055 | .swappiness = vm_swappiness, |
5ad333eb | 2056 | .order = order, |
66e1707b | 2057 | .mem_cgroup = NULL, |
179e9639 | 2058 | }; |
1da177e4 LT |
2059 | loop_again: |
2060 | total_scanned = 0; | |
a79311c1 | 2061 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2062 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2063 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2064 | |
1da177e4 LT |
2065 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
2066 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
2067 | unsigned long lru_pages = 0; | |
bb3ab596 | 2068 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2069 | |
f7b7fd8f RR |
2070 | /* The swap token gets in the way of swapout... */ |
2071 | if (!priority) | |
2072 | disable_swap_token(); | |
2073 | ||
1da177e4 LT |
2074 | all_zones_ok = 1; |
2075 | ||
d6277db4 RW |
2076 | /* |
2077 | * Scan in the highmem->dma direction for the highest | |
2078 | * zone which needs scanning | |
2079 | */ | |
2080 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2081 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2082 | |
d6277db4 RW |
2083 | if (!populated_zone(zone)) |
2084 | continue; | |
1da177e4 | 2085 | |
93e4a89a | 2086 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2087 | continue; |
1da177e4 | 2088 | |
556adecb RR |
2089 | /* |
2090 | * Do some background aging of the anon list, to give | |
2091 | * pages a chance to be referenced before reclaiming. | |
2092 | */ | |
14797e23 | 2093 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2094 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2095 | &sc, priority, 0); | |
2096 | ||
41858966 MG |
2097 | if (!zone_watermark_ok(zone, order, |
2098 | high_wmark_pages(zone), 0, 0)) { | |
d6277db4 | 2099 | end_zone = i; |
e1dbeda6 | 2100 | break; |
1da177e4 | 2101 | } |
1da177e4 | 2102 | } |
e1dbeda6 AM |
2103 | if (i < 0) |
2104 | goto out; | |
2105 | ||
1da177e4 LT |
2106 | for (i = 0; i <= end_zone; i++) { |
2107 | struct zone *zone = pgdat->node_zones + i; | |
2108 | ||
adea02a1 | 2109 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2110 | } |
2111 | ||
2112 | /* | |
2113 | * Now scan the zone in the dma->highmem direction, stopping | |
2114 | * at the last zone which needs scanning. | |
2115 | * | |
2116 | * We do this because the page allocator works in the opposite | |
2117 | * direction. This prevents the page allocator from allocating | |
2118 | * pages behind kswapd's direction of progress, which would | |
2119 | * cause too much scanning of the lower zones. | |
2120 | */ | |
2121 | for (i = 0; i <= end_zone; i++) { | |
2122 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2123 | int nr_slab; |
4e416953 | 2124 | int nid, zid; |
1da177e4 | 2125 | |
f3fe6512 | 2126 | if (!populated_zone(zone)) |
1da177e4 LT |
2127 | continue; |
2128 | ||
93e4a89a | 2129 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2130 | continue; |
2131 | ||
1da177e4 | 2132 | sc.nr_scanned = 0; |
4e416953 BS |
2133 | |
2134 | nid = pgdat->node_id; | |
2135 | zid = zone_idx(zone); | |
2136 | /* | |
2137 | * Call soft limit reclaim before calling shrink_zone. | |
2138 | * For now we ignore the return value | |
2139 | */ | |
2140 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask, | |
2141 | nid, zid); | |
32a4330d RR |
2142 | /* |
2143 | * We put equal pressure on every zone, unless one | |
2144 | * zone has way too many pages free already. | |
2145 | */ | |
41858966 MG |
2146 | if (!zone_watermark_ok(zone, order, |
2147 | 8*high_wmark_pages(zone), end_zone, 0)) | |
a79311c1 | 2148 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2149 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2150 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2151 | lru_pages); | |
a79311c1 | 2152 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2153 | total_scanned += sc.nr_scanned; |
93e4a89a | 2154 | if (zone->all_unreclaimable) |
1da177e4 | 2155 | continue; |
93e4a89a KM |
2156 | if (nr_slab == 0 && |
2157 | zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) | |
2158 | zone->all_unreclaimable = 1; | |
1da177e4 LT |
2159 | /* |
2160 | * If we've done a decent amount of scanning and | |
2161 | * the reclaim ratio is low, start doing writepage | |
2162 | * even in laptop mode | |
2163 | */ | |
2164 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2165 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2166 | sc.may_writepage = 1; |
bb3ab596 | 2167 | |
45973d74 MK |
2168 | if (!zone_watermark_ok(zone, order, |
2169 | high_wmark_pages(zone), end_zone, 0)) { | |
2170 | all_zones_ok = 0; | |
2171 | /* | |
2172 | * We are still under min water mark. This | |
2173 | * means that we have a GFP_ATOMIC allocation | |
2174 | * failure risk. Hurry up! | |
2175 | */ | |
2176 | if (!zone_watermark_ok(zone, order, | |
2177 | min_wmark_pages(zone), end_zone, 0)) | |
2178 | has_under_min_watermark_zone = 1; | |
2179 | } | |
bb3ab596 | 2180 | |
1da177e4 | 2181 | } |
1da177e4 LT |
2182 | if (all_zones_ok) |
2183 | break; /* kswapd: all done */ | |
2184 | /* | |
2185 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2186 | * another pass across the zones. | |
2187 | */ | |
bb3ab596 KM |
2188 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2189 | if (has_under_min_watermark_zone) | |
2190 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2191 | else | |
2192 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2193 | } | |
1da177e4 LT |
2194 | |
2195 | /* | |
2196 | * We do this so kswapd doesn't build up large priorities for | |
2197 | * example when it is freeing in parallel with allocators. It | |
2198 | * matches the direct reclaim path behaviour in terms of impact | |
2199 | * on zone->*_priority. | |
2200 | */ | |
a79311c1 | 2201 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2202 | break; |
2203 | } | |
2204 | out: | |
1da177e4 LT |
2205 | if (!all_zones_ok) { |
2206 | cond_resched(); | |
8357376d RW |
2207 | |
2208 | try_to_freeze(); | |
2209 | ||
73ce02e9 KM |
2210 | /* |
2211 | * Fragmentation may mean that the system cannot be | |
2212 | * rebalanced for high-order allocations in all zones. | |
2213 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2214 | * it means the zones have been fully scanned and are still | |
2215 | * not balanced. For high-order allocations, there is | |
2216 | * little point trying all over again as kswapd may | |
2217 | * infinite loop. | |
2218 | * | |
2219 | * Instead, recheck all watermarks at order-0 as they | |
2220 | * are the most important. If watermarks are ok, kswapd will go | |
2221 | * back to sleep. High-order users can still perform direct | |
2222 | * reclaim if they wish. | |
2223 | */ | |
2224 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2225 | order = sc.order = 0; | |
2226 | ||
1da177e4 LT |
2227 | goto loop_again; |
2228 | } | |
2229 | ||
a79311c1 | 2230 | return sc.nr_reclaimed; |
1da177e4 LT |
2231 | } |
2232 | ||
2233 | /* | |
2234 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2235 | * from the init process. |
1da177e4 LT |
2236 | * |
2237 | * This basically trickles out pages so that we have _some_ | |
2238 | * free memory available even if there is no other activity | |
2239 | * that frees anything up. This is needed for things like routing | |
2240 | * etc, where we otherwise might have all activity going on in | |
2241 | * asynchronous contexts that cannot page things out. | |
2242 | * | |
2243 | * If there are applications that are active memory-allocators | |
2244 | * (most normal use), this basically shouldn't matter. | |
2245 | */ | |
2246 | static int kswapd(void *p) | |
2247 | { | |
2248 | unsigned long order; | |
2249 | pg_data_t *pgdat = (pg_data_t*)p; | |
2250 | struct task_struct *tsk = current; | |
2251 | DEFINE_WAIT(wait); | |
2252 | struct reclaim_state reclaim_state = { | |
2253 | .reclaimed_slab = 0, | |
2254 | }; | |
a70f7302 | 2255 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2256 | |
cf40bd16 NP |
2257 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2258 | ||
174596a0 | 2259 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2260 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2261 | current->reclaim_state = &reclaim_state; |
2262 | ||
2263 | /* | |
2264 | * Tell the memory management that we're a "memory allocator", | |
2265 | * and that if we need more memory we should get access to it | |
2266 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2267 | * never get caught in the normal page freeing logic. | |
2268 | * | |
2269 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2270 | * you need a small amount of memory in order to be able to | |
2271 | * page out something else, and this flag essentially protects | |
2272 | * us from recursively trying to free more memory as we're | |
2273 | * trying to free the first piece of memory in the first place). | |
2274 | */ | |
930d9152 | 2275 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2276 | set_freezable(); |
1da177e4 LT |
2277 | |
2278 | order = 0; | |
2279 | for ( ; ; ) { | |
2280 | unsigned long new_order; | |
8fe23e05 | 2281 | int ret; |
3e1d1d28 | 2282 | |
1da177e4 LT |
2283 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2284 | new_order = pgdat->kswapd_max_order; | |
2285 | pgdat->kswapd_max_order = 0; | |
2286 | if (order < new_order) { | |
2287 | /* | |
2288 | * Don't sleep if someone wants a larger 'order' | |
2289 | * allocation | |
2290 | */ | |
2291 | order = new_order; | |
2292 | } else { | |
f50de2d3 MG |
2293 | if (!freezing(current) && !kthread_should_stop()) { |
2294 | long remaining = 0; | |
2295 | ||
2296 | /* Try to sleep for a short interval */ | |
bb3ab596 | 2297 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
f50de2d3 MG |
2298 | remaining = schedule_timeout(HZ/10); |
2299 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2300 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2301 | } | |
2302 | ||
2303 | /* | |
2304 | * After a short sleep, check if it was a | |
2305 | * premature sleep. If not, then go fully | |
2306 | * to sleep until explicitly woken up | |
2307 | */ | |
33906bc5 MG |
2308 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
2309 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); | |
f50de2d3 | 2310 | schedule(); |
33906bc5 | 2311 | } else { |
f50de2d3 | 2312 | if (remaining) |
bb3ab596 | 2313 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); |
f50de2d3 | 2314 | else |
bb3ab596 | 2315 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); |
f50de2d3 MG |
2316 | } |
2317 | } | |
b1296cc4 | 2318 | |
1da177e4 LT |
2319 | order = pgdat->kswapd_max_order; |
2320 | } | |
2321 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2322 | ||
8fe23e05 DR |
2323 | ret = try_to_freeze(); |
2324 | if (kthread_should_stop()) | |
2325 | break; | |
2326 | ||
2327 | /* | |
2328 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2329 | * after returning from the refrigerator | |
2330 | */ | |
33906bc5 MG |
2331 | if (!ret) { |
2332 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
b1296cc4 | 2333 | balance_pgdat(pgdat, order); |
33906bc5 | 2334 | } |
1da177e4 LT |
2335 | } |
2336 | return 0; | |
2337 | } | |
2338 | ||
2339 | /* | |
2340 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2341 | */ | |
2342 | void wakeup_kswapd(struct zone *zone, int order) | |
2343 | { | |
2344 | pg_data_t *pgdat; | |
2345 | ||
f3fe6512 | 2346 | if (!populated_zone(zone)) |
1da177e4 LT |
2347 | return; |
2348 | ||
2349 | pgdat = zone->zone_pgdat; | |
41858966 | 2350 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) |
1da177e4 LT |
2351 | return; |
2352 | if (pgdat->kswapd_max_order < order) | |
2353 | pgdat->kswapd_max_order = order; | |
33906bc5 | 2354 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); |
02a0e53d | 2355 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2356 | return; |
8d0986e2 | 2357 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2358 | return; |
8d0986e2 | 2359 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2360 | } |
2361 | ||
adea02a1 WF |
2362 | /* |
2363 | * The reclaimable count would be mostly accurate. | |
2364 | * The less reclaimable pages may be | |
2365 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2366 | * - mapped pages, which may require several travels to be reclaimed | |
2367 | * - dirty pages, which is not "instantly" reclaimable | |
2368 | */ | |
2369 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2370 | { |
adea02a1 WF |
2371 | int nr; |
2372 | ||
2373 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2374 | global_page_state(NR_INACTIVE_FILE); | |
2375 | ||
2376 | if (nr_swap_pages > 0) | |
2377 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2378 | global_page_state(NR_INACTIVE_ANON); | |
2379 | ||
2380 | return nr; | |
2381 | } | |
2382 | ||
2383 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2384 | { | |
2385 | int nr; | |
2386 | ||
2387 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2388 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2389 | ||
2390 | if (nr_swap_pages > 0) | |
2391 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2392 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2393 | ||
2394 | return nr; | |
4f98a2fe RR |
2395 | } |
2396 | ||
c6f37f12 | 2397 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2398 | /* |
7b51755c | 2399 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2400 | * freed pages. |
2401 | * | |
2402 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2403 | * LRU order by reclaiming preferentially | |
2404 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2405 | */ |
7b51755c | 2406 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2407 | { |
d6277db4 | 2408 | struct reclaim_state reclaim_state; |
d6277db4 | 2409 | struct scan_control sc = { |
7b51755c KM |
2410 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2411 | .may_swap = 1, | |
2412 | .may_unmap = 1, | |
d6277db4 | 2413 | .may_writepage = 1, |
7b51755c KM |
2414 | .nr_to_reclaim = nr_to_reclaim, |
2415 | .hibernation_mode = 1, | |
2416 | .swappiness = vm_swappiness, | |
2417 | .order = 0, | |
1da177e4 | 2418 | }; |
7b51755c KM |
2419 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2420 | struct task_struct *p = current; | |
2421 | unsigned long nr_reclaimed; | |
1da177e4 | 2422 | |
7b51755c KM |
2423 | p->flags |= PF_MEMALLOC; |
2424 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2425 | reclaim_state.reclaimed_slab = 0; | |
2426 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2427 | |
7b51755c | 2428 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2429 | |
7b51755c KM |
2430 | p->reclaim_state = NULL; |
2431 | lockdep_clear_current_reclaim_state(); | |
2432 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2433 | |
7b51755c | 2434 | return nr_reclaimed; |
1da177e4 | 2435 | } |
c6f37f12 | 2436 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2437 | |
1da177e4 LT |
2438 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2439 | not required for correctness. So if the last cpu in a node goes | |
2440 | away, we get changed to run anywhere: as the first one comes back, | |
2441 | restore their cpu bindings. */ | |
9c7b216d | 2442 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2443 | unsigned long action, void *hcpu) |
1da177e4 | 2444 | { |
58c0a4a7 | 2445 | int nid; |
1da177e4 | 2446 | |
8bb78442 | 2447 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2448 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2449 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2450 | const struct cpumask *mask; |
2451 | ||
2452 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2453 | |
3e597945 | 2454 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2455 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2456 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2457 | } |
2458 | } | |
2459 | return NOTIFY_OK; | |
2460 | } | |
1da177e4 | 2461 | |
3218ae14 YG |
2462 | /* |
2463 | * This kswapd start function will be called by init and node-hot-add. | |
2464 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2465 | */ | |
2466 | int kswapd_run(int nid) | |
2467 | { | |
2468 | pg_data_t *pgdat = NODE_DATA(nid); | |
2469 | int ret = 0; | |
2470 | ||
2471 | if (pgdat->kswapd) | |
2472 | return 0; | |
2473 | ||
2474 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2475 | if (IS_ERR(pgdat->kswapd)) { | |
2476 | /* failure at boot is fatal */ | |
2477 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2478 | printk("Failed to start kswapd on node %d\n",nid); | |
2479 | ret = -1; | |
2480 | } | |
2481 | return ret; | |
2482 | } | |
2483 | ||
8fe23e05 DR |
2484 | /* |
2485 | * Called by memory hotplug when all memory in a node is offlined. | |
2486 | */ | |
2487 | void kswapd_stop(int nid) | |
2488 | { | |
2489 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2490 | ||
2491 | if (kswapd) | |
2492 | kthread_stop(kswapd); | |
2493 | } | |
2494 | ||
1da177e4 LT |
2495 | static int __init kswapd_init(void) |
2496 | { | |
3218ae14 | 2497 | int nid; |
69e05944 | 2498 | |
1da177e4 | 2499 | swap_setup(); |
9422ffba | 2500 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2501 | kswapd_run(nid); |
1da177e4 LT |
2502 | hotcpu_notifier(cpu_callback, 0); |
2503 | return 0; | |
2504 | } | |
2505 | ||
2506 | module_init(kswapd_init) | |
9eeff239 CL |
2507 | |
2508 | #ifdef CONFIG_NUMA | |
2509 | /* | |
2510 | * Zone reclaim mode | |
2511 | * | |
2512 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2513 | * the watermarks. | |
9eeff239 CL |
2514 | */ |
2515 | int zone_reclaim_mode __read_mostly; | |
2516 | ||
1b2ffb78 | 2517 | #define RECLAIM_OFF 0 |
7d03431c | 2518 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2519 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2520 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2521 | ||
a92f7126 CL |
2522 | /* |
2523 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2524 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2525 | * a zone. | |
2526 | */ | |
2527 | #define ZONE_RECLAIM_PRIORITY 4 | |
2528 | ||
9614634f CL |
2529 | /* |
2530 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2531 | * occur. | |
2532 | */ | |
2533 | int sysctl_min_unmapped_ratio = 1; | |
2534 | ||
0ff38490 CL |
2535 | /* |
2536 | * If the number of slab pages in a zone grows beyond this percentage then | |
2537 | * slab reclaim needs to occur. | |
2538 | */ | |
2539 | int sysctl_min_slab_ratio = 5; | |
2540 | ||
90afa5de MG |
2541 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2542 | { | |
2543 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2544 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2545 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2546 | ||
2547 | /* | |
2548 | * It's possible for there to be more file mapped pages than | |
2549 | * accounted for by the pages on the file LRU lists because | |
2550 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2551 | */ | |
2552 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2553 | } | |
2554 | ||
2555 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2556 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2557 | { | |
2558 | long nr_pagecache_reclaimable; | |
2559 | long delta = 0; | |
2560 | ||
2561 | /* | |
2562 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2563 | * potentially reclaimable. Otherwise, we have to worry about | |
2564 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2565 | * a better estimate | |
2566 | */ | |
2567 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2568 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2569 | else | |
2570 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2571 | ||
2572 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2573 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2574 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2575 | ||
2576 | /* Watch for any possible underflows due to delta */ | |
2577 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2578 | delta = nr_pagecache_reclaimable; | |
2579 | ||
2580 | return nr_pagecache_reclaimable - delta; | |
2581 | } | |
2582 | ||
9eeff239 CL |
2583 | /* |
2584 | * Try to free up some pages from this zone through reclaim. | |
2585 | */ | |
179e9639 | 2586 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2587 | { |
7fb2d46d | 2588 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2589 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2590 | struct task_struct *p = current; |
2591 | struct reclaim_state reclaim_state; | |
8695949a | 2592 | int priority; |
179e9639 AM |
2593 | struct scan_control sc = { |
2594 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2595 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2596 | .may_swap = 1, |
22fba335 KM |
2597 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2598 | SWAP_CLUSTER_MAX), | |
179e9639 | 2599 | .gfp_mask = gfp_mask, |
d6277db4 | 2600 | .swappiness = vm_swappiness, |
bd2f6199 | 2601 | .order = order, |
179e9639 | 2602 | }; |
15748048 | 2603 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 2604 | |
9eeff239 | 2605 | cond_resched(); |
d4f7796e CL |
2606 | /* |
2607 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2608 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2609 | * and RECLAIM_SWAP. | |
2610 | */ | |
2611 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2612 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2613 | reclaim_state.reclaimed_slab = 0; |
2614 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2615 | |
90afa5de | 2616 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2617 | /* |
2618 | * Free memory by calling shrink zone with increasing | |
2619 | * priorities until we have enough memory freed. | |
2620 | */ | |
2621 | priority = ZONE_RECLAIM_PRIORITY; | |
2622 | do { | |
a79311c1 | 2623 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2624 | priority--; |
a79311c1 | 2625 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2626 | } |
c84db23c | 2627 | |
15748048 KM |
2628 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2629 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 2630 | /* |
7fb2d46d | 2631 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2632 | * many pages were freed in this zone. So we take the current |
2633 | * number of slab pages and shake the slab until it is reduced | |
2634 | * by the same nr_pages that we used for reclaiming unmapped | |
2635 | * pages. | |
2a16e3f4 | 2636 | * |
0ff38490 CL |
2637 | * Note that shrink_slab will free memory on all zones and may |
2638 | * take a long time. | |
2a16e3f4 | 2639 | */ |
0ff38490 | 2640 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
15748048 KM |
2641 | (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages > |
2642 | nr_slab_pages0)) | |
0ff38490 | 2643 | ; |
83e33a47 CL |
2644 | |
2645 | /* | |
2646 | * Update nr_reclaimed by the number of slab pages we | |
2647 | * reclaimed from this zone. | |
2648 | */ | |
15748048 KM |
2649 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2650 | if (nr_slab_pages1 < nr_slab_pages0) | |
2651 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
2652 | } |
2653 | ||
9eeff239 | 2654 | p->reclaim_state = NULL; |
d4f7796e | 2655 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 2656 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 2657 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2658 | } |
179e9639 AM |
2659 | |
2660 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2661 | { | |
179e9639 | 2662 | int node_id; |
d773ed6b | 2663 | int ret; |
179e9639 AM |
2664 | |
2665 | /* | |
0ff38490 CL |
2666 | * Zone reclaim reclaims unmapped file backed pages and |
2667 | * slab pages if we are over the defined limits. | |
34aa1330 | 2668 | * |
9614634f CL |
2669 | * A small portion of unmapped file backed pages is needed for |
2670 | * file I/O otherwise pages read by file I/O will be immediately | |
2671 | * thrown out if the zone is overallocated. So we do not reclaim | |
2672 | * if less than a specified percentage of the zone is used by | |
2673 | * unmapped file backed pages. | |
179e9639 | 2674 | */ |
90afa5de MG |
2675 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2676 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 2677 | return ZONE_RECLAIM_FULL; |
179e9639 | 2678 | |
93e4a89a | 2679 | if (zone->all_unreclaimable) |
fa5e084e | 2680 | return ZONE_RECLAIM_FULL; |
d773ed6b | 2681 | |
179e9639 | 2682 | /* |
d773ed6b | 2683 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2684 | */ |
d773ed6b | 2685 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 2686 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
2687 | |
2688 | /* | |
2689 | * Only run zone reclaim on the local zone or on zones that do not | |
2690 | * have associated processors. This will favor the local processor | |
2691 | * over remote processors and spread off node memory allocations | |
2692 | * as wide as possible. | |
2693 | */ | |
89fa3024 | 2694 | node_id = zone_to_nid(zone); |
37c0708d | 2695 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 2696 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
2697 | |
2698 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
2699 | return ZONE_RECLAIM_NOSCAN; |
2700 | ||
d773ed6b DR |
2701 | ret = __zone_reclaim(zone, gfp_mask, order); |
2702 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2703 | ||
24cf7251 MG |
2704 | if (!ret) |
2705 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
2706 | ||
d773ed6b | 2707 | return ret; |
179e9639 | 2708 | } |
9eeff239 | 2709 | #endif |
894bc310 | 2710 | |
894bc310 LS |
2711 | /* |
2712 | * page_evictable - test whether a page is evictable | |
2713 | * @page: the page to test | |
2714 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2715 | * | |
2716 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2717 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2718 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2719 | * |
2720 | * Reasons page might not be evictable: | |
ba9ddf49 | 2721 | * (1) page's mapping marked unevictable |
b291f000 | 2722 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2723 | * |
894bc310 LS |
2724 | */ |
2725 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2726 | { | |
2727 | ||
ba9ddf49 LS |
2728 | if (mapping_unevictable(page_mapping(page))) |
2729 | return 0; | |
2730 | ||
b291f000 NP |
2731 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2732 | return 0; | |
894bc310 LS |
2733 | |
2734 | return 1; | |
2735 | } | |
89e004ea LS |
2736 | |
2737 | /** | |
2738 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2739 | * @page: page to check evictability and move to appropriate lru list | |
2740 | * @zone: zone page is in | |
2741 | * | |
2742 | * Checks a page for evictability and moves the page to the appropriate | |
2743 | * zone lru list. | |
2744 | * | |
2745 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2746 | * have PageUnevictable set. | |
2747 | */ | |
2748 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2749 | { | |
2750 | VM_BUG_ON(PageActive(page)); | |
2751 | ||
2752 | retry: | |
2753 | ClearPageUnevictable(page); | |
2754 | if (page_evictable(page, NULL)) { | |
401a8e1c | 2755 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 2756 | |
89e004ea LS |
2757 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2758 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2759 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2760 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2761 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2762 | } else { | |
2763 | /* | |
2764 | * rotate unevictable list | |
2765 | */ | |
2766 | SetPageUnevictable(page); | |
2767 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2768 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2769 | if (page_evictable(page, NULL)) |
2770 | goto retry; | |
2771 | } | |
2772 | } | |
2773 | ||
2774 | /** | |
2775 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2776 | * @mapping: struct address_space to scan for evictable pages | |
2777 | * | |
2778 | * Scan all pages in mapping. Check unevictable pages for | |
2779 | * evictability and move them to the appropriate zone lru list. | |
2780 | */ | |
2781 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2782 | { | |
2783 | pgoff_t next = 0; | |
2784 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2785 | PAGE_CACHE_SHIFT; | |
2786 | struct zone *zone; | |
2787 | struct pagevec pvec; | |
2788 | ||
2789 | if (mapping->nrpages == 0) | |
2790 | return; | |
2791 | ||
2792 | pagevec_init(&pvec, 0); | |
2793 | while (next < end && | |
2794 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2795 | int i; | |
2796 | int pg_scanned = 0; | |
2797 | ||
2798 | zone = NULL; | |
2799 | ||
2800 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2801 | struct page *page = pvec.pages[i]; | |
2802 | pgoff_t page_index = page->index; | |
2803 | struct zone *pagezone = page_zone(page); | |
2804 | ||
2805 | pg_scanned++; | |
2806 | if (page_index > next) | |
2807 | next = page_index; | |
2808 | next++; | |
2809 | ||
2810 | if (pagezone != zone) { | |
2811 | if (zone) | |
2812 | spin_unlock_irq(&zone->lru_lock); | |
2813 | zone = pagezone; | |
2814 | spin_lock_irq(&zone->lru_lock); | |
2815 | } | |
2816 | ||
2817 | if (PageLRU(page) && PageUnevictable(page)) | |
2818 | check_move_unevictable_page(page, zone); | |
2819 | } | |
2820 | if (zone) | |
2821 | spin_unlock_irq(&zone->lru_lock); | |
2822 | pagevec_release(&pvec); | |
2823 | ||
2824 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2825 | } | |
2826 | ||
2827 | } | |
af936a16 LS |
2828 | |
2829 | /** | |
2830 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2831 | * @zone - zone of which to scan the unevictable list | |
2832 | * | |
2833 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2834 | * evictable. Move those that have to @zone's inactive list where they | |
2835 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2836 | * to reactivate them. Pages that are still unevictable are rotated | |
2837 | * back onto @zone's unevictable list. | |
2838 | */ | |
2839 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2840 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2841 | { |
2842 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2843 | unsigned long scan; | |
2844 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2845 | ||
2846 | while (nr_to_scan > 0) { | |
2847 | unsigned long batch_size = min(nr_to_scan, | |
2848 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2849 | ||
2850 | spin_lock_irq(&zone->lru_lock); | |
2851 | for (scan = 0; scan < batch_size; scan++) { | |
2852 | struct page *page = lru_to_page(l_unevictable); | |
2853 | ||
2854 | if (!trylock_page(page)) | |
2855 | continue; | |
2856 | ||
2857 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
2858 | ||
2859 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
2860 | check_move_unevictable_page(page, zone); | |
2861 | ||
2862 | unlock_page(page); | |
2863 | } | |
2864 | spin_unlock_irq(&zone->lru_lock); | |
2865 | ||
2866 | nr_to_scan -= batch_size; | |
2867 | } | |
2868 | } | |
2869 | ||
2870 | ||
2871 | /** | |
2872 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
2873 | * | |
2874 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
2875 | * pages that have become evictable. Move those back to the zones' | |
2876 | * inactive list where they become candidates for reclaim. | |
2877 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
2878 | * and we add swap to the system. As such, it runs in the context of a task | |
2879 | * that has possibly/probably made some previously unevictable pages | |
2880 | * evictable. | |
2881 | */ | |
ff30153b | 2882 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
2883 | { |
2884 | struct zone *zone; | |
2885 | ||
2886 | for_each_zone(zone) { | |
2887 | scan_zone_unevictable_pages(zone); | |
2888 | } | |
2889 | } | |
2890 | ||
2891 | /* | |
2892 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
2893 | * all nodes' unevictable lists for evictable pages | |
2894 | */ | |
2895 | unsigned long scan_unevictable_pages; | |
2896 | ||
2897 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 2898 | void __user *buffer, |
af936a16 LS |
2899 | size_t *length, loff_t *ppos) |
2900 | { | |
8d65af78 | 2901 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
2902 | |
2903 | if (write && *(unsigned long *)table->data) | |
2904 | scan_all_zones_unevictable_pages(); | |
2905 | ||
2906 | scan_unevictable_pages = 0; | |
2907 | return 0; | |
2908 | } | |
2909 | ||
2910 | /* | |
2911 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
2912 | * a specified node's per zone unevictable lists for evictable pages. | |
2913 | */ | |
2914 | ||
2915 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
2916 | struct sysdev_attribute *attr, | |
2917 | char *buf) | |
2918 | { | |
2919 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
2920 | } | |
2921 | ||
2922 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
2923 | struct sysdev_attribute *attr, | |
2924 | const char *buf, size_t count) | |
2925 | { | |
2926 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
2927 | struct zone *zone; | |
2928 | unsigned long res; | |
2929 | unsigned long req = strict_strtoul(buf, 10, &res); | |
2930 | ||
2931 | if (!req) | |
2932 | return 1; /* zero is no-op */ | |
2933 | ||
2934 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
2935 | if (!populated_zone(zone)) | |
2936 | continue; | |
2937 | scan_zone_unevictable_pages(zone); | |
2938 | } | |
2939 | return 1; | |
2940 | } | |
2941 | ||
2942 | ||
2943 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
2944 | read_scan_unevictable_node, | |
2945 | write_scan_unevictable_node); | |
2946 | ||
2947 | int scan_unevictable_register_node(struct node *node) | |
2948 | { | |
2949 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2950 | } | |
2951 | ||
2952 | void scan_unevictable_unregister_node(struct node *node) | |
2953 | { | |
2954 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2955 | } | |
2956 |