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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/mm/vmscan.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
6 | * | |
7 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
8 | * kswapd added: 7.1.96 sct | |
9 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
10 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
11 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
12 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
13 | */ | |
14 | ||
b1de0d13 MH |
15 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
16 | ||
1da177e4 | 17 | #include <linux/mm.h> |
5b3cc15a | 18 | #include <linux/sched/mm.h> |
1da177e4 | 19 | #include <linux/module.h> |
5a0e3ad6 | 20 | #include <linux/gfp.h> |
1da177e4 LT |
21 | #include <linux/kernel_stat.h> |
22 | #include <linux/swap.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/highmem.h> | |
70ddf637 | 26 | #include <linux/vmpressure.h> |
e129b5c2 | 27 | #include <linux/vmstat.h> |
1da177e4 LT |
28 | #include <linux/file.h> |
29 | #include <linux/writeback.h> | |
30 | #include <linux/blkdev.h> | |
31 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
32 | buffer_heads_over_limit */ | |
33 | #include <linux/mm_inline.h> | |
1da177e4 LT |
34 | #include <linux/backing-dev.h> |
35 | #include <linux/rmap.h> | |
36 | #include <linux/topology.h> | |
37 | #include <linux/cpu.h> | |
38 | #include <linux/cpuset.h> | |
3e7d3449 | 39 | #include <linux/compaction.h> |
1da177e4 LT |
40 | #include <linux/notifier.h> |
41 | #include <linux/rwsem.h> | |
248a0301 | 42 | #include <linux/delay.h> |
3218ae14 | 43 | #include <linux/kthread.h> |
7dfb7103 | 44 | #include <linux/freezer.h> |
66e1707b | 45 | #include <linux/memcontrol.h> |
873b4771 | 46 | #include <linux/delayacct.h> |
af936a16 | 47 | #include <linux/sysctl.h> |
929bea7c | 48 | #include <linux/oom.h> |
268bb0ce | 49 | #include <linux/prefetch.h> |
b1de0d13 | 50 | #include <linux/printk.h> |
f9fe48be | 51 | #include <linux/dax.h> |
1da177e4 LT |
52 | |
53 | #include <asm/tlbflush.h> | |
54 | #include <asm/div64.h> | |
55 | ||
56 | #include <linux/swapops.h> | |
117aad1e | 57 | #include <linux/balloon_compaction.h> |
1da177e4 | 58 | |
0f8053a5 NP |
59 | #include "internal.h" |
60 | ||
33906bc5 MG |
61 | #define CREATE_TRACE_POINTS |
62 | #include <trace/events/vmscan.h> | |
63 | ||
1da177e4 | 64 | struct scan_control { |
22fba335 KM |
65 | /* How many pages shrink_list() should reclaim */ |
66 | unsigned long nr_to_reclaim; | |
67 | ||
ee814fe2 JW |
68 | /* |
69 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
70 | * are scanned. | |
71 | */ | |
72 | nodemask_t *nodemask; | |
9e3b2f8c | 73 | |
f16015fb JW |
74 | /* |
75 | * The memory cgroup that hit its limit and as a result is the | |
76 | * primary target of this reclaim invocation. | |
77 | */ | |
78 | struct mem_cgroup *target_mem_cgroup; | |
66e1707b | 79 | |
1276ad68 | 80 | /* Writepage batching in laptop mode; RECLAIM_WRITE */ |
ee814fe2 JW |
81 | unsigned int may_writepage:1; |
82 | ||
83 | /* Can mapped pages be reclaimed? */ | |
84 | unsigned int may_unmap:1; | |
85 | ||
86 | /* Can pages be swapped as part of reclaim? */ | |
87 | unsigned int may_swap:1; | |
88 | ||
d6622f63 YX |
89 | /* |
90 | * Cgroups are not reclaimed below their configured memory.low, | |
91 | * unless we threaten to OOM. If any cgroups are skipped due to | |
92 | * memory.low and nothing was reclaimed, go back for memory.low. | |
93 | */ | |
94 | unsigned int memcg_low_reclaim:1; | |
95 | unsigned int memcg_low_skipped:1; | |
241994ed | 96 | |
ee814fe2 JW |
97 | unsigned int hibernation_mode:1; |
98 | ||
99 | /* One of the zones is ready for compaction */ | |
100 | unsigned int compaction_ready:1; | |
101 | ||
bb451fdf GT |
102 | /* Allocation order */ |
103 | s8 order; | |
104 | ||
105 | /* Scan (total_size >> priority) pages at once */ | |
106 | s8 priority; | |
107 | ||
108 | /* The highest zone to isolate pages for reclaim from */ | |
109 | s8 reclaim_idx; | |
110 | ||
111 | /* This context's GFP mask */ | |
112 | gfp_t gfp_mask; | |
113 | ||
ee814fe2 JW |
114 | /* Incremented by the number of inactive pages that were scanned */ |
115 | unsigned long nr_scanned; | |
116 | ||
117 | /* Number of pages freed so far during a call to shrink_zones() */ | |
118 | unsigned long nr_reclaimed; | |
d108c772 AR |
119 | |
120 | struct { | |
121 | unsigned int dirty; | |
122 | unsigned int unqueued_dirty; | |
123 | unsigned int congested; | |
124 | unsigned int writeback; | |
125 | unsigned int immediate; | |
126 | unsigned int file_taken; | |
127 | unsigned int taken; | |
128 | } nr; | |
1da177e4 LT |
129 | }; |
130 | ||
1da177e4 LT |
131 | #ifdef ARCH_HAS_PREFETCH |
132 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
133 | do { \ | |
134 | if ((_page)->lru.prev != _base) { \ | |
135 | struct page *prev; \ | |
136 | \ | |
137 | prev = lru_to_page(&(_page->lru)); \ | |
138 | prefetch(&prev->_field); \ | |
139 | } \ | |
140 | } while (0) | |
141 | #else | |
142 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
143 | #endif | |
144 | ||
145 | #ifdef ARCH_HAS_PREFETCHW | |
146 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
147 | do { \ | |
148 | if ((_page)->lru.prev != _base) { \ | |
149 | struct page *prev; \ | |
150 | \ | |
151 | prev = lru_to_page(&(_page->lru)); \ | |
152 | prefetchw(&prev->_field); \ | |
153 | } \ | |
154 | } while (0) | |
155 | #else | |
156 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
157 | #endif | |
158 | ||
159 | /* | |
160 | * From 0 .. 100. Higher means more swappy. | |
161 | */ | |
162 | int vm_swappiness = 60; | |
d0480be4 WSH |
163 | /* |
164 | * The total number of pages which are beyond the high watermark within all | |
165 | * zones. | |
166 | */ | |
167 | unsigned long vm_total_pages; | |
1da177e4 LT |
168 | |
169 | static LIST_HEAD(shrinker_list); | |
170 | static DECLARE_RWSEM(shrinker_rwsem); | |
171 | ||
b4c2b231 | 172 | #ifdef CONFIG_MEMCG_KMEM |
7e010df5 KT |
173 | |
174 | /* | |
175 | * We allow subsystems to populate their shrinker-related | |
176 | * LRU lists before register_shrinker_prepared() is called | |
177 | * for the shrinker, since we don't want to impose | |
178 | * restrictions on their internal registration order. | |
179 | * In this case shrink_slab_memcg() may find corresponding | |
180 | * bit is set in the shrinkers map. | |
181 | * | |
182 | * This value is used by the function to detect registering | |
183 | * shrinkers and to skip do_shrink_slab() calls for them. | |
184 | */ | |
185 | #define SHRINKER_REGISTERING ((struct shrinker *)~0UL) | |
186 | ||
b4c2b231 KT |
187 | static DEFINE_IDR(shrinker_idr); |
188 | static int shrinker_nr_max; | |
189 | ||
190 | static int prealloc_memcg_shrinker(struct shrinker *shrinker) | |
191 | { | |
192 | int id, ret = -ENOMEM; | |
193 | ||
194 | down_write(&shrinker_rwsem); | |
195 | /* This may call shrinker, so it must use down_read_trylock() */ | |
7e010df5 | 196 | id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); |
b4c2b231 KT |
197 | if (id < 0) |
198 | goto unlock; | |
199 | ||
0a4465d3 KT |
200 | if (id >= shrinker_nr_max) { |
201 | if (memcg_expand_shrinker_maps(id)) { | |
202 | idr_remove(&shrinker_idr, id); | |
203 | goto unlock; | |
204 | } | |
205 | ||
b4c2b231 | 206 | shrinker_nr_max = id + 1; |
0a4465d3 | 207 | } |
b4c2b231 KT |
208 | shrinker->id = id; |
209 | ret = 0; | |
210 | unlock: | |
211 | up_write(&shrinker_rwsem); | |
212 | return ret; | |
213 | } | |
214 | ||
215 | static void unregister_memcg_shrinker(struct shrinker *shrinker) | |
216 | { | |
217 | int id = shrinker->id; | |
218 | ||
219 | BUG_ON(id < 0); | |
220 | ||
221 | down_write(&shrinker_rwsem); | |
222 | idr_remove(&shrinker_idr, id); | |
223 | up_write(&shrinker_rwsem); | |
224 | } | |
225 | #else /* CONFIG_MEMCG_KMEM */ | |
226 | static int prealloc_memcg_shrinker(struct shrinker *shrinker) | |
227 | { | |
228 | return 0; | |
229 | } | |
230 | ||
231 | static void unregister_memcg_shrinker(struct shrinker *shrinker) | |
232 | { | |
233 | } | |
234 | #endif /* CONFIG_MEMCG_KMEM */ | |
235 | ||
c255a458 | 236 | #ifdef CONFIG_MEMCG |
89b5fae5 JW |
237 | static bool global_reclaim(struct scan_control *sc) |
238 | { | |
f16015fb | 239 | return !sc->target_mem_cgroup; |
89b5fae5 | 240 | } |
97c9341f TH |
241 | |
242 | /** | |
243 | * sane_reclaim - is the usual dirty throttling mechanism operational? | |
244 | * @sc: scan_control in question | |
245 | * | |
246 | * The normal page dirty throttling mechanism in balance_dirty_pages() is | |
247 | * completely broken with the legacy memcg and direct stalling in | |
248 | * shrink_page_list() is used for throttling instead, which lacks all the | |
249 | * niceties such as fairness, adaptive pausing, bandwidth proportional | |
250 | * allocation and configurability. | |
251 | * | |
252 | * This function tests whether the vmscan currently in progress can assume | |
253 | * that the normal dirty throttling mechanism is operational. | |
254 | */ | |
255 | static bool sane_reclaim(struct scan_control *sc) | |
256 | { | |
257 | struct mem_cgroup *memcg = sc->target_mem_cgroup; | |
258 | ||
259 | if (!memcg) | |
260 | return true; | |
261 | #ifdef CONFIG_CGROUP_WRITEBACK | |
69234ace | 262 | if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) |
97c9341f TH |
263 | return true; |
264 | #endif | |
265 | return false; | |
266 | } | |
e3c1ac58 AR |
267 | |
268 | static void set_memcg_congestion(pg_data_t *pgdat, | |
269 | struct mem_cgroup *memcg, | |
270 | bool congested) | |
271 | { | |
272 | struct mem_cgroup_per_node *mn; | |
273 | ||
274 | if (!memcg) | |
275 | return; | |
276 | ||
277 | mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); | |
278 | WRITE_ONCE(mn->congested, congested); | |
279 | } | |
280 | ||
281 | static bool memcg_congested(pg_data_t *pgdat, | |
282 | struct mem_cgroup *memcg) | |
283 | { | |
284 | struct mem_cgroup_per_node *mn; | |
285 | ||
286 | mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); | |
287 | return READ_ONCE(mn->congested); | |
288 | ||
289 | } | |
91a45470 | 290 | #else |
89b5fae5 JW |
291 | static bool global_reclaim(struct scan_control *sc) |
292 | { | |
293 | return true; | |
294 | } | |
97c9341f TH |
295 | |
296 | static bool sane_reclaim(struct scan_control *sc) | |
297 | { | |
298 | return true; | |
299 | } | |
e3c1ac58 AR |
300 | |
301 | static inline void set_memcg_congestion(struct pglist_data *pgdat, | |
302 | struct mem_cgroup *memcg, bool congested) | |
303 | { | |
304 | } | |
305 | ||
306 | static inline bool memcg_congested(struct pglist_data *pgdat, | |
307 | struct mem_cgroup *memcg) | |
308 | { | |
309 | return false; | |
310 | ||
311 | } | |
91a45470 KH |
312 | #endif |
313 | ||
5a1c84b4 MG |
314 | /* |
315 | * This misses isolated pages which are not accounted for to save counters. | |
316 | * As the data only determines if reclaim or compaction continues, it is | |
317 | * not expected that isolated pages will be a dominating factor. | |
318 | */ | |
319 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
320 | { | |
321 | unsigned long nr; | |
322 | ||
323 | nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + | |
324 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); | |
325 | if (get_nr_swap_pages() > 0) | |
326 | nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + | |
327 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); | |
328 | ||
329 | return nr; | |
330 | } | |
331 | ||
fd538803 MH |
332 | /** |
333 | * lruvec_lru_size - Returns the number of pages on the given LRU list. | |
334 | * @lruvec: lru vector | |
335 | * @lru: lru to use | |
336 | * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list) | |
337 | */ | |
338 | unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx) | |
c9f299d9 | 339 | { |
fd538803 MH |
340 | unsigned long lru_size; |
341 | int zid; | |
342 | ||
c3c787e8 | 343 | if (!mem_cgroup_disabled()) |
fd538803 MH |
344 | lru_size = mem_cgroup_get_lru_size(lruvec, lru); |
345 | else | |
346 | lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru); | |
a3d8e054 | 347 | |
fd538803 MH |
348 | for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) { |
349 | struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid]; | |
350 | unsigned long size; | |
c9f299d9 | 351 | |
fd538803 MH |
352 | if (!managed_zone(zone)) |
353 | continue; | |
354 | ||
355 | if (!mem_cgroup_disabled()) | |
356 | size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid); | |
357 | else | |
358 | size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid], | |
359 | NR_ZONE_LRU_BASE + lru); | |
360 | lru_size -= min(size, lru_size); | |
361 | } | |
362 | ||
363 | return lru_size; | |
b4536f0c | 364 | |
b4536f0c MH |
365 | } |
366 | ||
1da177e4 | 367 | /* |
1d3d4437 | 368 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 369 | */ |
8e04944f | 370 | int prealloc_shrinker(struct shrinker *shrinker) |
1da177e4 | 371 | { |
1d3d4437 GC |
372 | size_t size = sizeof(*shrinker->nr_deferred); |
373 | ||
1d3d4437 GC |
374 | if (shrinker->flags & SHRINKER_NUMA_AWARE) |
375 | size *= nr_node_ids; | |
376 | ||
377 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
378 | if (!shrinker->nr_deferred) | |
379 | return -ENOMEM; | |
b4c2b231 KT |
380 | |
381 | if (shrinker->flags & SHRINKER_MEMCG_AWARE) { | |
382 | if (prealloc_memcg_shrinker(shrinker)) | |
383 | goto free_deferred; | |
384 | } | |
385 | ||
8e04944f | 386 | return 0; |
b4c2b231 KT |
387 | |
388 | free_deferred: | |
389 | kfree(shrinker->nr_deferred); | |
390 | shrinker->nr_deferred = NULL; | |
391 | return -ENOMEM; | |
8e04944f TH |
392 | } |
393 | ||
394 | void free_prealloced_shrinker(struct shrinker *shrinker) | |
395 | { | |
b4c2b231 KT |
396 | if (!shrinker->nr_deferred) |
397 | return; | |
398 | ||
399 | if (shrinker->flags & SHRINKER_MEMCG_AWARE) | |
400 | unregister_memcg_shrinker(shrinker); | |
401 | ||
8e04944f TH |
402 | kfree(shrinker->nr_deferred); |
403 | shrinker->nr_deferred = NULL; | |
404 | } | |
1d3d4437 | 405 | |
8e04944f TH |
406 | void register_shrinker_prepared(struct shrinker *shrinker) |
407 | { | |
8e1f936b RR |
408 | down_write(&shrinker_rwsem); |
409 | list_add_tail(&shrinker->list, &shrinker_list); | |
7e010df5 | 410 | #ifdef CONFIG_MEMCG_KMEM |
8df4a44c KT |
411 | if (shrinker->flags & SHRINKER_MEMCG_AWARE) |
412 | idr_replace(&shrinker_idr, shrinker, shrinker->id); | |
7e010df5 | 413 | #endif |
8e1f936b | 414 | up_write(&shrinker_rwsem); |
8e04944f TH |
415 | } |
416 | ||
417 | int register_shrinker(struct shrinker *shrinker) | |
418 | { | |
419 | int err = prealloc_shrinker(shrinker); | |
420 | ||
421 | if (err) | |
422 | return err; | |
423 | register_shrinker_prepared(shrinker); | |
1d3d4437 | 424 | return 0; |
1da177e4 | 425 | } |
8e1f936b | 426 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
427 | |
428 | /* | |
429 | * Remove one | |
430 | */ | |
8e1f936b | 431 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 | 432 | { |
bb422a73 TH |
433 | if (!shrinker->nr_deferred) |
434 | return; | |
b4c2b231 KT |
435 | if (shrinker->flags & SHRINKER_MEMCG_AWARE) |
436 | unregister_memcg_shrinker(shrinker); | |
1da177e4 LT |
437 | down_write(&shrinker_rwsem); |
438 | list_del(&shrinker->list); | |
439 | up_write(&shrinker_rwsem); | |
ae393321 | 440 | kfree(shrinker->nr_deferred); |
bb422a73 | 441 | shrinker->nr_deferred = NULL; |
1da177e4 | 442 | } |
8e1f936b | 443 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
444 | |
445 | #define SHRINK_BATCH 128 | |
1d3d4437 | 446 | |
cb731d6c | 447 | static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, |
9092c71b | 448 | struct shrinker *shrinker, int priority) |
1d3d4437 GC |
449 | { |
450 | unsigned long freed = 0; | |
451 | unsigned long long delta; | |
452 | long total_scan; | |
d5bc5fd3 | 453 | long freeable; |
1d3d4437 GC |
454 | long nr; |
455 | long new_nr; | |
456 | int nid = shrinkctl->nid; | |
457 | long batch_size = shrinker->batch ? shrinker->batch | |
458 | : SHRINK_BATCH; | |
5f33a080 | 459 | long scanned = 0, next_deferred; |
1d3d4437 | 460 | |
ac7fb3ad KT |
461 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) |
462 | nid = 0; | |
463 | ||
d5bc5fd3 | 464 | freeable = shrinker->count_objects(shrinker, shrinkctl); |
9b996468 KT |
465 | if (freeable == 0 || freeable == SHRINK_EMPTY) |
466 | return freeable; | |
1d3d4437 GC |
467 | |
468 | /* | |
469 | * copy the current shrinker scan count into a local variable | |
470 | * and zero it so that other concurrent shrinker invocations | |
471 | * don't also do this scanning work. | |
472 | */ | |
473 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
474 | ||
475 | total_scan = nr; | |
9092c71b JB |
476 | delta = freeable >> priority; |
477 | delta *= 4; | |
478 | do_div(delta, shrinker->seeks); | |
1d3d4437 GC |
479 | total_scan += delta; |
480 | if (total_scan < 0) { | |
8612c663 | 481 | pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", |
a0b02131 | 482 | shrinker->scan_objects, total_scan); |
d5bc5fd3 | 483 | total_scan = freeable; |
5f33a080 SL |
484 | next_deferred = nr; |
485 | } else | |
486 | next_deferred = total_scan; | |
1d3d4437 GC |
487 | |
488 | /* | |
489 | * We need to avoid excessive windup on filesystem shrinkers | |
490 | * due to large numbers of GFP_NOFS allocations causing the | |
491 | * shrinkers to return -1 all the time. This results in a large | |
492 | * nr being built up so when a shrink that can do some work | |
493 | * comes along it empties the entire cache due to nr >>> | |
d5bc5fd3 | 494 | * freeable. This is bad for sustaining a working set in |
1d3d4437 GC |
495 | * memory. |
496 | * | |
497 | * Hence only allow the shrinker to scan the entire cache when | |
498 | * a large delta change is calculated directly. | |
499 | */ | |
d5bc5fd3 VD |
500 | if (delta < freeable / 4) |
501 | total_scan = min(total_scan, freeable / 2); | |
1d3d4437 GC |
502 | |
503 | /* | |
504 | * Avoid risking looping forever due to too large nr value: | |
505 | * never try to free more than twice the estimate number of | |
506 | * freeable entries. | |
507 | */ | |
d5bc5fd3 VD |
508 | if (total_scan > freeable * 2) |
509 | total_scan = freeable * 2; | |
1d3d4437 GC |
510 | |
511 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
9092c71b | 512 | freeable, delta, total_scan, priority); |
1d3d4437 | 513 | |
0b1fb40a VD |
514 | /* |
515 | * Normally, we should not scan less than batch_size objects in one | |
516 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
517 | * than batch_size objects in total and we are really tight on memory, | |
518 | * we will try to reclaim all available objects, otherwise we can end | |
519 | * up failing allocations although there are plenty of reclaimable | |
520 | * objects spread over several slabs with usage less than the | |
521 | * batch_size. | |
522 | * | |
523 | * We detect the "tight on memory" situations by looking at the total | |
524 | * number of objects we want to scan (total_scan). If it is greater | |
d5bc5fd3 | 525 | * than the total number of objects on slab (freeable), we must be |
0b1fb40a VD |
526 | * scanning at high prio and therefore should try to reclaim as much as |
527 | * possible. | |
528 | */ | |
529 | while (total_scan >= batch_size || | |
d5bc5fd3 | 530 | total_scan >= freeable) { |
a0b02131 | 531 | unsigned long ret; |
0b1fb40a | 532 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 533 | |
0b1fb40a | 534 | shrinkctl->nr_to_scan = nr_to_scan; |
d460acb5 | 535 | shrinkctl->nr_scanned = nr_to_scan; |
a0b02131 DC |
536 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
537 | if (ret == SHRINK_STOP) | |
538 | break; | |
539 | freed += ret; | |
1d3d4437 | 540 | |
d460acb5 CW |
541 | count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); |
542 | total_scan -= shrinkctl->nr_scanned; | |
543 | scanned += shrinkctl->nr_scanned; | |
1d3d4437 GC |
544 | |
545 | cond_resched(); | |
546 | } | |
547 | ||
5f33a080 SL |
548 | if (next_deferred >= scanned) |
549 | next_deferred -= scanned; | |
550 | else | |
551 | next_deferred = 0; | |
1d3d4437 GC |
552 | /* |
553 | * move the unused scan count back into the shrinker in a | |
554 | * manner that handles concurrent updates. If we exhausted the | |
555 | * scan, there is no need to do an update. | |
556 | */ | |
5f33a080 SL |
557 | if (next_deferred > 0) |
558 | new_nr = atomic_long_add_return(next_deferred, | |
1d3d4437 GC |
559 | &shrinker->nr_deferred[nid]); |
560 | else | |
561 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
562 | ||
df9024a8 | 563 | trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); |
1d3d4437 | 564 | return freed; |
1495f230 YH |
565 | } |
566 | ||
b0dedc49 KT |
567 | #ifdef CONFIG_MEMCG_KMEM |
568 | static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, | |
569 | struct mem_cgroup *memcg, int priority) | |
570 | { | |
571 | struct memcg_shrinker_map *map; | |
572 | unsigned long freed = 0; | |
573 | int ret, i; | |
574 | ||
575 | if (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)) | |
576 | return 0; | |
577 | ||
578 | if (!down_read_trylock(&shrinker_rwsem)) | |
579 | return 0; | |
580 | ||
581 | map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map, | |
582 | true); | |
583 | if (unlikely(!map)) | |
584 | goto unlock; | |
585 | ||
586 | for_each_set_bit(i, map->map, shrinker_nr_max) { | |
587 | struct shrink_control sc = { | |
588 | .gfp_mask = gfp_mask, | |
589 | .nid = nid, | |
590 | .memcg = memcg, | |
591 | }; | |
592 | struct shrinker *shrinker; | |
593 | ||
594 | shrinker = idr_find(&shrinker_idr, i); | |
7e010df5 KT |
595 | if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) { |
596 | if (!shrinker) | |
597 | clear_bit(i, map->map); | |
b0dedc49 KT |
598 | continue; |
599 | } | |
600 | ||
b0dedc49 | 601 | ret = do_shrink_slab(&sc, shrinker, priority); |
f90280d6 KT |
602 | if (ret == SHRINK_EMPTY) { |
603 | clear_bit(i, map->map); | |
604 | /* | |
605 | * After the shrinker reported that it had no objects to | |
606 | * free, but before we cleared the corresponding bit in | |
607 | * the memcg shrinker map, a new object might have been | |
608 | * added. To make sure, we have the bit set in this | |
609 | * case, we invoke the shrinker one more time and reset | |
610 | * the bit if it reports that it is not empty anymore. | |
611 | * The memory barrier here pairs with the barrier in | |
612 | * memcg_set_shrinker_bit(): | |
613 | * | |
614 | * list_lru_add() shrink_slab_memcg() | |
615 | * list_add_tail() clear_bit() | |
616 | * <MB> <MB> | |
617 | * set_bit() do_shrink_slab() | |
618 | */ | |
619 | smp_mb__after_atomic(); | |
620 | ret = do_shrink_slab(&sc, shrinker, priority); | |
621 | if (ret == SHRINK_EMPTY) | |
622 | ret = 0; | |
623 | else | |
624 | memcg_set_shrinker_bit(memcg, nid, i); | |
625 | } | |
b0dedc49 KT |
626 | freed += ret; |
627 | ||
628 | if (rwsem_is_contended(&shrinker_rwsem)) { | |
629 | freed = freed ? : 1; | |
630 | break; | |
631 | } | |
632 | } | |
633 | unlock: | |
634 | up_read(&shrinker_rwsem); | |
635 | return freed; | |
636 | } | |
637 | #else /* CONFIG_MEMCG_KMEM */ | |
638 | static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, | |
639 | struct mem_cgroup *memcg, int priority) | |
640 | { | |
641 | return 0; | |
642 | } | |
643 | #endif /* CONFIG_MEMCG_KMEM */ | |
644 | ||
6b4f7799 | 645 | /** |
cb731d6c | 646 | * shrink_slab - shrink slab caches |
6b4f7799 JW |
647 | * @gfp_mask: allocation context |
648 | * @nid: node whose slab caches to target | |
cb731d6c | 649 | * @memcg: memory cgroup whose slab caches to target |
9092c71b | 650 | * @priority: the reclaim priority |
1da177e4 | 651 | * |
6b4f7799 | 652 | * Call the shrink functions to age shrinkable caches. |
1da177e4 | 653 | * |
6b4f7799 JW |
654 | * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, |
655 | * unaware shrinkers will receive a node id of 0 instead. | |
1da177e4 | 656 | * |
aeed1d32 VD |
657 | * @memcg specifies the memory cgroup to target. Unaware shrinkers |
658 | * are called only if it is the root cgroup. | |
cb731d6c | 659 | * |
9092c71b JB |
660 | * @priority is sc->priority, we take the number of objects and >> by priority |
661 | * in order to get the scan target. | |
b15e0905 | 662 | * |
6b4f7799 | 663 | * Returns the number of reclaimed slab objects. |
1da177e4 | 664 | */ |
cb731d6c VD |
665 | static unsigned long shrink_slab(gfp_t gfp_mask, int nid, |
666 | struct mem_cgroup *memcg, | |
9092c71b | 667 | int priority) |
1da177e4 LT |
668 | { |
669 | struct shrinker *shrinker; | |
24f7c6b9 | 670 | unsigned long freed = 0; |
9b996468 | 671 | int ret; |
1da177e4 | 672 | |
aeed1d32 | 673 | if (!mem_cgroup_is_root(memcg)) |
b0dedc49 | 674 | return shrink_slab_memcg(gfp_mask, nid, memcg, priority); |
cb731d6c | 675 | |
e830c63a | 676 | if (!down_read_trylock(&shrinker_rwsem)) |
f06590bd | 677 | goto out; |
1da177e4 LT |
678 | |
679 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
6b4f7799 JW |
680 | struct shrink_control sc = { |
681 | .gfp_mask = gfp_mask, | |
682 | .nid = nid, | |
cb731d6c | 683 | .memcg = memcg, |
6b4f7799 | 684 | }; |
ec97097b | 685 | |
9b996468 KT |
686 | ret = do_shrink_slab(&sc, shrinker, priority); |
687 | if (ret == SHRINK_EMPTY) | |
688 | ret = 0; | |
689 | freed += ret; | |
e496612c MK |
690 | /* |
691 | * Bail out if someone want to register a new shrinker to | |
692 | * prevent the regsitration from being stalled for long periods | |
693 | * by parallel ongoing shrinking. | |
694 | */ | |
695 | if (rwsem_is_contended(&shrinker_rwsem)) { | |
696 | freed = freed ? : 1; | |
697 | break; | |
698 | } | |
1da177e4 | 699 | } |
6b4f7799 | 700 | |
1da177e4 | 701 | up_read(&shrinker_rwsem); |
f06590bd MK |
702 | out: |
703 | cond_resched(); | |
24f7c6b9 | 704 | return freed; |
1da177e4 LT |
705 | } |
706 | ||
cb731d6c VD |
707 | void drop_slab_node(int nid) |
708 | { | |
709 | unsigned long freed; | |
710 | ||
711 | do { | |
712 | struct mem_cgroup *memcg = NULL; | |
713 | ||
714 | freed = 0; | |
aeed1d32 | 715 | memcg = mem_cgroup_iter(NULL, NULL, NULL); |
cb731d6c | 716 | do { |
9092c71b | 717 | freed += shrink_slab(GFP_KERNEL, nid, memcg, 0); |
cb731d6c VD |
718 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); |
719 | } while (freed > 10); | |
720 | } | |
721 | ||
722 | void drop_slab(void) | |
723 | { | |
724 | int nid; | |
725 | ||
726 | for_each_online_node(nid) | |
727 | drop_slab_node(nid); | |
728 | } | |
729 | ||
1da177e4 LT |
730 | static inline int is_page_cache_freeable(struct page *page) |
731 | { | |
ceddc3a5 JW |
732 | /* |
733 | * A freeable page cache page is referenced only by the caller | |
734 | * that isolated the page, the page cache radix tree and | |
735 | * optional buffer heads at page->private. | |
736 | */ | |
bd4c82c2 HY |
737 | int radix_pins = PageTransHuge(page) && PageSwapCache(page) ? |
738 | HPAGE_PMD_NR : 1; | |
739 | return page_count(page) - page_has_private(page) == 1 + radix_pins; | |
1da177e4 LT |
740 | } |
741 | ||
703c2708 | 742 | static int may_write_to_inode(struct inode *inode, struct scan_control *sc) |
1da177e4 | 743 | { |
930d9152 | 744 | if (current->flags & PF_SWAPWRITE) |
1da177e4 | 745 | return 1; |
703c2708 | 746 | if (!inode_write_congested(inode)) |
1da177e4 | 747 | return 1; |
703c2708 | 748 | if (inode_to_bdi(inode) == current->backing_dev_info) |
1da177e4 LT |
749 | return 1; |
750 | return 0; | |
751 | } | |
752 | ||
753 | /* | |
754 | * We detected a synchronous write error writing a page out. Probably | |
755 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
756 | * fsync(), msync() or close(). | |
757 | * | |
758 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
759 | * prevents it from being freed up. But we have a ref on the page and once | |
760 | * that page is locked, the mapping is pinned. | |
761 | * | |
762 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
763 | * __GFP_FS. | |
764 | */ | |
765 | static void handle_write_error(struct address_space *mapping, | |
766 | struct page *page, int error) | |
767 | { | |
7eaceacc | 768 | lock_page(page); |
3e9f45bd GC |
769 | if (page_mapping(page) == mapping) |
770 | mapping_set_error(mapping, error); | |
1da177e4 LT |
771 | unlock_page(page); |
772 | } | |
773 | ||
04e62a29 CL |
774 | /* possible outcome of pageout() */ |
775 | typedef enum { | |
776 | /* failed to write page out, page is locked */ | |
777 | PAGE_KEEP, | |
778 | /* move page to the active list, page is locked */ | |
779 | PAGE_ACTIVATE, | |
780 | /* page has been sent to the disk successfully, page is unlocked */ | |
781 | PAGE_SUCCESS, | |
782 | /* page is clean and locked */ | |
783 | PAGE_CLEAN, | |
784 | } pageout_t; | |
785 | ||
1da177e4 | 786 | /* |
1742f19f AM |
787 | * pageout is called by shrink_page_list() for each dirty page. |
788 | * Calls ->writepage(). | |
1da177e4 | 789 | */ |
c661b078 | 790 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 791 | struct scan_control *sc) |
1da177e4 LT |
792 | { |
793 | /* | |
794 | * If the page is dirty, only perform writeback if that write | |
795 | * will be non-blocking. To prevent this allocation from being | |
796 | * stalled by pagecache activity. But note that there may be | |
797 | * stalls if we need to run get_block(). We could test | |
798 | * PagePrivate for that. | |
799 | * | |
8174202b | 800 | * If this process is currently in __generic_file_write_iter() against |
1da177e4 LT |
801 | * this page's queue, we can perform writeback even if that |
802 | * will block. | |
803 | * | |
804 | * If the page is swapcache, write it back even if that would | |
805 | * block, for some throttling. This happens by accident, because | |
806 | * swap_backing_dev_info is bust: it doesn't reflect the | |
807 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
808 | */ |
809 | if (!is_page_cache_freeable(page)) | |
810 | return PAGE_KEEP; | |
811 | if (!mapping) { | |
812 | /* | |
813 | * Some data journaling orphaned pages can have | |
814 | * page->mapping == NULL while being dirty with clean buffers. | |
815 | */ | |
266cf658 | 816 | if (page_has_private(page)) { |
1da177e4 LT |
817 | if (try_to_free_buffers(page)) { |
818 | ClearPageDirty(page); | |
b1de0d13 | 819 | pr_info("%s: orphaned page\n", __func__); |
1da177e4 LT |
820 | return PAGE_CLEAN; |
821 | } | |
822 | } | |
823 | return PAGE_KEEP; | |
824 | } | |
825 | if (mapping->a_ops->writepage == NULL) | |
826 | return PAGE_ACTIVATE; | |
703c2708 | 827 | if (!may_write_to_inode(mapping->host, sc)) |
1da177e4 LT |
828 | return PAGE_KEEP; |
829 | ||
830 | if (clear_page_dirty_for_io(page)) { | |
831 | int res; | |
832 | struct writeback_control wbc = { | |
833 | .sync_mode = WB_SYNC_NONE, | |
834 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
835 | .range_start = 0, |
836 | .range_end = LLONG_MAX, | |
1da177e4 LT |
837 | .for_reclaim = 1, |
838 | }; | |
839 | ||
840 | SetPageReclaim(page); | |
841 | res = mapping->a_ops->writepage(page, &wbc); | |
842 | if (res < 0) | |
843 | handle_write_error(mapping, page, res); | |
994fc28c | 844 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
845 | ClearPageReclaim(page); |
846 | return PAGE_ACTIVATE; | |
847 | } | |
c661b078 | 848 | |
1da177e4 LT |
849 | if (!PageWriteback(page)) { |
850 | /* synchronous write or broken a_ops? */ | |
851 | ClearPageReclaim(page); | |
852 | } | |
3aa23851 | 853 | trace_mm_vmscan_writepage(page); |
c4a25635 | 854 | inc_node_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
855 | return PAGE_SUCCESS; |
856 | } | |
857 | ||
858 | return PAGE_CLEAN; | |
859 | } | |
860 | ||
a649fd92 | 861 | /* |
e286781d NP |
862 | * Same as remove_mapping, but if the page is removed from the mapping, it |
863 | * gets returned with a refcount of 0. | |
a649fd92 | 864 | */ |
a528910e JW |
865 | static int __remove_mapping(struct address_space *mapping, struct page *page, |
866 | bool reclaimed) | |
49d2e9cc | 867 | { |
c4843a75 | 868 | unsigned long flags; |
bd4c82c2 | 869 | int refcount; |
c4843a75 | 870 | |
28e4d965 NP |
871 | BUG_ON(!PageLocked(page)); |
872 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 873 | |
b93b0163 | 874 | xa_lock_irqsave(&mapping->i_pages, flags); |
49d2e9cc | 875 | /* |
0fd0e6b0 NP |
876 | * The non racy check for a busy page. |
877 | * | |
878 | * Must be careful with the order of the tests. When someone has | |
879 | * a ref to the page, it may be possible that they dirty it then | |
880 | * drop the reference. So if PageDirty is tested before page_count | |
881 | * here, then the following race may occur: | |
882 | * | |
883 | * get_user_pages(&page); | |
884 | * [user mapping goes away] | |
885 | * write_to(page); | |
886 | * !PageDirty(page) [good] | |
887 | * SetPageDirty(page); | |
888 | * put_page(page); | |
889 | * !page_count(page) [good, discard it] | |
890 | * | |
891 | * [oops, our write_to data is lost] | |
892 | * | |
893 | * Reversing the order of the tests ensures such a situation cannot | |
894 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
0139aa7b | 895 | * load is not satisfied before that of page->_refcount. |
0fd0e6b0 NP |
896 | * |
897 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
b93b0163 | 898 | * and thus under the i_pages lock, then this ordering is not required. |
49d2e9cc | 899 | */ |
bd4c82c2 HY |
900 | if (unlikely(PageTransHuge(page)) && PageSwapCache(page)) |
901 | refcount = 1 + HPAGE_PMD_NR; | |
902 | else | |
903 | refcount = 2; | |
904 | if (!page_ref_freeze(page, refcount)) | |
49d2e9cc | 905 | goto cannot_free; |
1c4c3b99 | 906 | /* note: atomic_cmpxchg in page_ref_freeze provides the smp_rmb */ |
e286781d | 907 | if (unlikely(PageDirty(page))) { |
bd4c82c2 | 908 | page_ref_unfreeze(page, refcount); |
49d2e9cc | 909 | goto cannot_free; |
e286781d | 910 | } |
49d2e9cc CL |
911 | |
912 | if (PageSwapCache(page)) { | |
913 | swp_entry_t swap = { .val = page_private(page) }; | |
0a31bc97 | 914 | mem_cgroup_swapout(page, swap); |
49d2e9cc | 915 | __delete_from_swap_cache(page); |
b93b0163 | 916 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
75f6d6d2 | 917 | put_swap_page(page, swap); |
e286781d | 918 | } else { |
6072d13c | 919 | void (*freepage)(struct page *); |
a528910e | 920 | void *shadow = NULL; |
6072d13c LT |
921 | |
922 | freepage = mapping->a_ops->freepage; | |
a528910e JW |
923 | /* |
924 | * Remember a shadow entry for reclaimed file cache in | |
925 | * order to detect refaults, thus thrashing, later on. | |
926 | * | |
927 | * But don't store shadows in an address space that is | |
928 | * already exiting. This is not just an optizimation, | |
929 | * inode reclaim needs to empty out the radix tree or | |
930 | * the nodes are lost. Don't plant shadows behind its | |
931 | * back. | |
f9fe48be RZ |
932 | * |
933 | * We also don't store shadows for DAX mappings because the | |
934 | * only page cache pages found in these are zero pages | |
935 | * covering holes, and because we don't want to mix DAX | |
936 | * exceptional entries and shadow exceptional entries in the | |
b93b0163 | 937 | * same address_space. |
a528910e JW |
938 | */ |
939 | if (reclaimed && page_is_file_cache(page) && | |
f9fe48be | 940 | !mapping_exiting(mapping) && !dax_mapping(mapping)) |
a528910e | 941 | shadow = workingset_eviction(mapping, page); |
62cccb8c | 942 | __delete_from_page_cache(page, shadow); |
b93b0163 | 943 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
6072d13c LT |
944 | |
945 | if (freepage != NULL) | |
946 | freepage(page); | |
49d2e9cc CL |
947 | } |
948 | ||
49d2e9cc CL |
949 | return 1; |
950 | ||
951 | cannot_free: | |
b93b0163 | 952 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
49d2e9cc CL |
953 | return 0; |
954 | } | |
955 | ||
e286781d NP |
956 | /* |
957 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
958 | * someone else has a ref on the page, abort and return 0. If it was | |
959 | * successfully detached, return 1. Assumes the caller has a single ref on | |
960 | * this page. | |
961 | */ | |
962 | int remove_mapping(struct address_space *mapping, struct page *page) | |
963 | { | |
a528910e | 964 | if (__remove_mapping(mapping, page, false)) { |
e286781d NP |
965 | /* |
966 | * Unfreezing the refcount with 1 rather than 2 effectively | |
967 | * drops the pagecache ref for us without requiring another | |
968 | * atomic operation. | |
969 | */ | |
fe896d18 | 970 | page_ref_unfreeze(page, 1); |
e286781d NP |
971 | return 1; |
972 | } | |
973 | return 0; | |
974 | } | |
975 | ||
894bc310 LS |
976 | /** |
977 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
978 | * @page: page to be put back to appropriate lru list | |
979 | * | |
980 | * Add previously isolated @page to appropriate LRU list. | |
981 | * Page may still be unevictable for other reasons. | |
982 | * | |
983 | * lru_lock must not be held, interrupts must be enabled. | |
984 | */ | |
894bc310 LS |
985 | void putback_lru_page(struct page *page) |
986 | { | |
9c4e6b1a | 987 | lru_cache_add(page); |
894bc310 LS |
988 | put_page(page); /* drop ref from isolate */ |
989 | } | |
990 | ||
dfc8d636 JW |
991 | enum page_references { |
992 | PAGEREF_RECLAIM, | |
993 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 994 | PAGEREF_KEEP, |
dfc8d636 JW |
995 | PAGEREF_ACTIVATE, |
996 | }; | |
997 | ||
998 | static enum page_references page_check_references(struct page *page, | |
999 | struct scan_control *sc) | |
1000 | { | |
64574746 | 1001 | int referenced_ptes, referenced_page; |
dfc8d636 | 1002 | unsigned long vm_flags; |
dfc8d636 | 1003 | |
c3ac9a8a JW |
1004 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
1005 | &vm_flags); | |
64574746 | 1006 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 1007 | |
dfc8d636 JW |
1008 | /* |
1009 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
1010 | * move the page to the unevictable list. | |
1011 | */ | |
1012 | if (vm_flags & VM_LOCKED) | |
1013 | return PAGEREF_RECLAIM; | |
1014 | ||
64574746 | 1015 | if (referenced_ptes) { |
e4898273 | 1016 | if (PageSwapBacked(page)) |
64574746 JW |
1017 | return PAGEREF_ACTIVATE; |
1018 | /* | |
1019 | * All mapped pages start out with page table | |
1020 | * references from the instantiating fault, so we need | |
1021 | * to look twice if a mapped file page is used more | |
1022 | * than once. | |
1023 | * | |
1024 | * Mark it and spare it for another trip around the | |
1025 | * inactive list. Another page table reference will | |
1026 | * lead to its activation. | |
1027 | * | |
1028 | * Note: the mark is set for activated pages as well | |
1029 | * so that recently deactivated but used pages are | |
1030 | * quickly recovered. | |
1031 | */ | |
1032 | SetPageReferenced(page); | |
1033 | ||
34dbc67a | 1034 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
1035 | return PAGEREF_ACTIVATE; |
1036 | ||
c909e993 KK |
1037 | /* |
1038 | * Activate file-backed executable pages after first usage. | |
1039 | */ | |
1040 | if (vm_flags & VM_EXEC) | |
1041 | return PAGEREF_ACTIVATE; | |
1042 | ||
64574746 JW |
1043 | return PAGEREF_KEEP; |
1044 | } | |
dfc8d636 JW |
1045 | |
1046 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 1047 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
1048 | return PAGEREF_RECLAIM_CLEAN; |
1049 | ||
1050 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
1051 | } |
1052 | ||
e2be15f6 MG |
1053 | /* Check if a page is dirty or under writeback */ |
1054 | static void page_check_dirty_writeback(struct page *page, | |
1055 | bool *dirty, bool *writeback) | |
1056 | { | |
b4597226 MG |
1057 | struct address_space *mapping; |
1058 | ||
e2be15f6 MG |
1059 | /* |
1060 | * Anonymous pages are not handled by flushers and must be written | |
1061 | * from reclaim context. Do not stall reclaim based on them | |
1062 | */ | |
802a3a92 SL |
1063 | if (!page_is_file_cache(page) || |
1064 | (PageAnon(page) && !PageSwapBacked(page))) { | |
e2be15f6 MG |
1065 | *dirty = false; |
1066 | *writeback = false; | |
1067 | return; | |
1068 | } | |
1069 | ||
1070 | /* By default assume that the page flags are accurate */ | |
1071 | *dirty = PageDirty(page); | |
1072 | *writeback = PageWriteback(page); | |
b4597226 MG |
1073 | |
1074 | /* Verify dirty/writeback state if the filesystem supports it */ | |
1075 | if (!page_has_private(page)) | |
1076 | return; | |
1077 | ||
1078 | mapping = page_mapping(page); | |
1079 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
1080 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
1081 | } |
1082 | ||
1da177e4 | 1083 | /* |
1742f19f | 1084 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 1085 | */ |
1742f19f | 1086 | static unsigned long shrink_page_list(struct list_head *page_list, |
599d0c95 | 1087 | struct pglist_data *pgdat, |
f84f6e2b | 1088 | struct scan_control *sc, |
02c6de8d | 1089 | enum ttu_flags ttu_flags, |
3c710c1a | 1090 | struct reclaim_stat *stat, |
02c6de8d | 1091 | bool force_reclaim) |
1da177e4 LT |
1092 | { |
1093 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 1094 | LIST_HEAD(free_pages); |
1da177e4 | 1095 | int pgactivate = 0; |
3c710c1a MH |
1096 | unsigned nr_unqueued_dirty = 0; |
1097 | unsigned nr_dirty = 0; | |
1098 | unsigned nr_congested = 0; | |
1099 | unsigned nr_reclaimed = 0; | |
1100 | unsigned nr_writeback = 0; | |
1101 | unsigned nr_immediate = 0; | |
5bccd166 MH |
1102 | unsigned nr_ref_keep = 0; |
1103 | unsigned nr_unmap_fail = 0; | |
1da177e4 LT |
1104 | |
1105 | cond_resched(); | |
1106 | ||
1da177e4 LT |
1107 | while (!list_empty(page_list)) { |
1108 | struct address_space *mapping; | |
1109 | struct page *page; | |
1110 | int may_enter_fs; | |
02c6de8d | 1111 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 1112 | bool dirty, writeback; |
1da177e4 LT |
1113 | |
1114 | cond_resched(); | |
1115 | ||
1116 | page = lru_to_page(page_list); | |
1117 | list_del(&page->lru); | |
1118 | ||
529ae9aa | 1119 | if (!trylock_page(page)) |
1da177e4 LT |
1120 | goto keep; |
1121 | ||
309381fe | 1122 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1123 | |
1124 | sc->nr_scanned++; | |
80e43426 | 1125 | |
39b5f29a | 1126 | if (unlikely(!page_evictable(page))) |
ad6b6704 | 1127 | goto activate_locked; |
894bc310 | 1128 | |
a6dc60f8 | 1129 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
1130 | goto keep_locked; |
1131 | ||
1da177e4 | 1132 | /* Double the slab pressure for mapped and swapcache pages */ |
802a3a92 SL |
1133 | if ((page_mapped(page) || PageSwapCache(page)) && |
1134 | !(PageAnon(page) && !PageSwapBacked(page))) | |
1da177e4 LT |
1135 | sc->nr_scanned++; |
1136 | ||
c661b078 AW |
1137 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
1138 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
1139 | ||
e2be15f6 | 1140 | /* |
894befec | 1141 | * The number of dirty pages determines if a node is marked |
e2be15f6 MG |
1142 | * reclaim_congested which affects wait_iff_congested. kswapd |
1143 | * will stall and start writing pages if the tail of the LRU | |
1144 | * is all dirty unqueued pages. | |
1145 | */ | |
1146 | page_check_dirty_writeback(page, &dirty, &writeback); | |
1147 | if (dirty || writeback) | |
1148 | nr_dirty++; | |
1149 | ||
1150 | if (dirty && !writeback) | |
1151 | nr_unqueued_dirty++; | |
1152 | ||
d04e8acd MG |
1153 | /* |
1154 | * Treat this page as congested if the underlying BDI is or if | |
1155 | * pages are cycling through the LRU so quickly that the | |
1156 | * pages marked for immediate reclaim are making it to the | |
1157 | * end of the LRU a second time. | |
1158 | */ | |
e2be15f6 | 1159 | mapping = page_mapping(page); |
1da58ee2 | 1160 | if (((dirty || writeback) && mapping && |
703c2708 | 1161 | inode_write_congested(mapping->host)) || |
d04e8acd | 1162 | (writeback && PageReclaim(page))) |
e2be15f6 MG |
1163 | nr_congested++; |
1164 | ||
283aba9f MG |
1165 | /* |
1166 | * If a page at the tail of the LRU is under writeback, there | |
1167 | * are three cases to consider. | |
1168 | * | |
1169 | * 1) If reclaim is encountering an excessive number of pages | |
1170 | * under writeback and this page is both under writeback and | |
1171 | * PageReclaim then it indicates that pages are being queued | |
1172 | * for IO but are being recycled through the LRU before the | |
1173 | * IO can complete. Waiting on the page itself risks an | |
1174 | * indefinite stall if it is impossible to writeback the | |
1175 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
1176 | * note that the LRU is being scanned too quickly and the |
1177 | * caller can stall after page list has been processed. | |
283aba9f | 1178 | * |
97c9341f | 1179 | * 2) Global or new memcg reclaim encounters a page that is |
ecf5fc6e MH |
1180 | * not marked for immediate reclaim, or the caller does not |
1181 | * have __GFP_FS (or __GFP_IO if it's simply going to swap, | |
1182 | * not to fs). In this case mark the page for immediate | |
97c9341f | 1183 | * reclaim and continue scanning. |
283aba9f | 1184 | * |
ecf5fc6e MH |
1185 | * Require may_enter_fs because we would wait on fs, which |
1186 | * may not have submitted IO yet. And the loop driver might | |
283aba9f MG |
1187 | * enter reclaim, and deadlock if it waits on a page for |
1188 | * which it is needed to do the write (loop masks off | |
1189 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
1190 | * would probably show more reasons. | |
1191 | * | |
7fadc820 | 1192 | * 3) Legacy memcg encounters a page that is already marked |
283aba9f MG |
1193 | * PageReclaim. memcg does not have any dirty pages |
1194 | * throttling so we could easily OOM just because too many | |
1195 | * pages are in writeback and there is nothing else to | |
1196 | * reclaim. Wait for the writeback to complete. | |
c55e8d03 JW |
1197 | * |
1198 | * In cases 1) and 2) we activate the pages to get them out of | |
1199 | * the way while we continue scanning for clean pages on the | |
1200 | * inactive list and refilling from the active list. The | |
1201 | * observation here is that waiting for disk writes is more | |
1202 | * expensive than potentially causing reloads down the line. | |
1203 | * Since they're marked for immediate reclaim, they won't put | |
1204 | * memory pressure on the cache working set any longer than it | |
1205 | * takes to write them to disk. | |
283aba9f | 1206 | */ |
c661b078 | 1207 | if (PageWriteback(page)) { |
283aba9f MG |
1208 | /* Case 1 above */ |
1209 | if (current_is_kswapd() && | |
1210 | PageReclaim(page) && | |
599d0c95 | 1211 | test_bit(PGDAT_WRITEBACK, &pgdat->flags)) { |
b1a6f21e | 1212 | nr_immediate++; |
c55e8d03 | 1213 | goto activate_locked; |
283aba9f MG |
1214 | |
1215 | /* Case 2 above */ | |
97c9341f | 1216 | } else if (sane_reclaim(sc) || |
ecf5fc6e | 1217 | !PageReclaim(page) || !may_enter_fs) { |
c3b94f44 HD |
1218 | /* |
1219 | * This is slightly racy - end_page_writeback() | |
1220 | * might have just cleared PageReclaim, then | |
1221 | * setting PageReclaim here end up interpreted | |
1222 | * as PageReadahead - but that does not matter | |
1223 | * enough to care. What we do want is for this | |
1224 | * page to have PageReclaim set next time memcg | |
1225 | * reclaim reaches the tests above, so it will | |
1226 | * then wait_on_page_writeback() to avoid OOM; | |
1227 | * and it's also appropriate in global reclaim. | |
1228 | */ | |
1229 | SetPageReclaim(page); | |
e62e384e | 1230 | nr_writeback++; |
c55e8d03 | 1231 | goto activate_locked; |
283aba9f MG |
1232 | |
1233 | /* Case 3 above */ | |
1234 | } else { | |
7fadc820 | 1235 | unlock_page(page); |
283aba9f | 1236 | wait_on_page_writeback(page); |
7fadc820 HD |
1237 | /* then go back and try same page again */ |
1238 | list_add_tail(&page->lru, page_list); | |
1239 | continue; | |
e62e384e | 1240 | } |
c661b078 | 1241 | } |
1da177e4 | 1242 | |
02c6de8d MK |
1243 | if (!force_reclaim) |
1244 | references = page_check_references(page, sc); | |
1245 | ||
dfc8d636 JW |
1246 | switch (references) { |
1247 | case PAGEREF_ACTIVATE: | |
1da177e4 | 1248 | goto activate_locked; |
64574746 | 1249 | case PAGEREF_KEEP: |
5bccd166 | 1250 | nr_ref_keep++; |
64574746 | 1251 | goto keep_locked; |
dfc8d636 JW |
1252 | case PAGEREF_RECLAIM: |
1253 | case PAGEREF_RECLAIM_CLEAN: | |
1254 | ; /* try to reclaim the page below */ | |
1255 | } | |
1da177e4 | 1256 | |
1da177e4 LT |
1257 | /* |
1258 | * Anonymous process memory has backing store? | |
1259 | * Try to allocate it some swap space here. | |
802a3a92 | 1260 | * Lazyfree page could be freed directly |
1da177e4 | 1261 | */ |
bd4c82c2 HY |
1262 | if (PageAnon(page) && PageSwapBacked(page)) { |
1263 | if (!PageSwapCache(page)) { | |
1264 | if (!(sc->gfp_mask & __GFP_IO)) | |
1265 | goto keep_locked; | |
1266 | if (PageTransHuge(page)) { | |
1267 | /* cannot split THP, skip it */ | |
1268 | if (!can_split_huge_page(page, NULL)) | |
1269 | goto activate_locked; | |
1270 | /* | |
1271 | * Split pages without a PMD map right | |
1272 | * away. Chances are some or all of the | |
1273 | * tail pages can be freed without IO. | |
1274 | */ | |
1275 | if (!compound_mapcount(page) && | |
1276 | split_huge_page_to_list(page, | |
1277 | page_list)) | |
1278 | goto activate_locked; | |
1279 | } | |
1280 | if (!add_to_swap(page)) { | |
1281 | if (!PageTransHuge(page)) | |
1282 | goto activate_locked; | |
1283 | /* Fallback to swap normal pages */ | |
1284 | if (split_huge_page_to_list(page, | |
1285 | page_list)) | |
1286 | goto activate_locked; | |
fe490cc0 HY |
1287 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
1288 | count_vm_event(THP_SWPOUT_FALLBACK); | |
1289 | #endif | |
bd4c82c2 HY |
1290 | if (!add_to_swap(page)) |
1291 | goto activate_locked; | |
1292 | } | |
0f074658 | 1293 | |
bd4c82c2 | 1294 | may_enter_fs = 1; |
1da177e4 | 1295 | |
bd4c82c2 HY |
1296 | /* Adding to swap updated mapping */ |
1297 | mapping = page_mapping(page); | |
1298 | } | |
7751b2da KS |
1299 | } else if (unlikely(PageTransHuge(page))) { |
1300 | /* Split file THP */ | |
1301 | if (split_huge_page_to_list(page, page_list)) | |
1302 | goto keep_locked; | |
e2be15f6 | 1303 | } |
1da177e4 LT |
1304 | |
1305 | /* | |
1306 | * The page is mapped into the page tables of one or more | |
1307 | * processes. Try to unmap it here. | |
1308 | */ | |
802a3a92 | 1309 | if (page_mapped(page)) { |
bd4c82c2 HY |
1310 | enum ttu_flags flags = ttu_flags | TTU_BATCH_FLUSH; |
1311 | ||
1312 | if (unlikely(PageTransHuge(page))) | |
1313 | flags |= TTU_SPLIT_HUGE_PMD; | |
1314 | if (!try_to_unmap(page, flags)) { | |
5bccd166 | 1315 | nr_unmap_fail++; |
1da177e4 | 1316 | goto activate_locked; |
1da177e4 LT |
1317 | } |
1318 | } | |
1319 | ||
1320 | if (PageDirty(page)) { | |
ee72886d | 1321 | /* |
4eda4823 JW |
1322 | * Only kswapd can writeback filesystem pages |
1323 | * to avoid risk of stack overflow. But avoid | |
1324 | * injecting inefficient single-page IO into | |
1325 | * flusher writeback as much as possible: only | |
1326 | * write pages when we've encountered many | |
1327 | * dirty pages, and when we've already scanned | |
1328 | * the rest of the LRU for clean pages and see | |
1329 | * the same dirty pages again (PageReclaim). | |
ee72886d | 1330 | */ |
f84f6e2b | 1331 | if (page_is_file_cache(page) && |
4eda4823 JW |
1332 | (!current_is_kswapd() || !PageReclaim(page) || |
1333 | !test_bit(PGDAT_DIRTY, &pgdat->flags))) { | |
49ea7eb6 MG |
1334 | /* |
1335 | * Immediately reclaim when written back. | |
1336 | * Similar in principal to deactivate_page() | |
1337 | * except we already have the page isolated | |
1338 | * and know it's dirty | |
1339 | */ | |
c4a25635 | 1340 | inc_node_page_state(page, NR_VMSCAN_IMMEDIATE); |
49ea7eb6 MG |
1341 | SetPageReclaim(page); |
1342 | ||
c55e8d03 | 1343 | goto activate_locked; |
ee72886d MG |
1344 | } |
1345 | ||
dfc8d636 | 1346 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 1347 | goto keep_locked; |
4dd4b920 | 1348 | if (!may_enter_fs) |
1da177e4 | 1349 | goto keep_locked; |
52a8363e | 1350 | if (!sc->may_writepage) |
1da177e4 LT |
1351 | goto keep_locked; |
1352 | ||
d950c947 MG |
1353 | /* |
1354 | * Page is dirty. Flush the TLB if a writable entry | |
1355 | * potentially exists to avoid CPU writes after IO | |
1356 | * starts and then write it out here. | |
1357 | */ | |
1358 | try_to_unmap_flush_dirty(); | |
7d3579e8 | 1359 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1360 | case PAGE_KEEP: |
1361 | goto keep_locked; | |
1362 | case PAGE_ACTIVATE: | |
1363 | goto activate_locked; | |
1364 | case PAGE_SUCCESS: | |
7d3579e8 | 1365 | if (PageWriteback(page)) |
41ac1999 | 1366 | goto keep; |
7d3579e8 | 1367 | if (PageDirty(page)) |
1da177e4 | 1368 | goto keep; |
7d3579e8 | 1369 | |
1da177e4 LT |
1370 | /* |
1371 | * A synchronous write - probably a ramdisk. Go | |
1372 | * ahead and try to reclaim the page. | |
1373 | */ | |
529ae9aa | 1374 | if (!trylock_page(page)) |
1da177e4 LT |
1375 | goto keep; |
1376 | if (PageDirty(page) || PageWriteback(page)) | |
1377 | goto keep_locked; | |
1378 | mapping = page_mapping(page); | |
1379 | case PAGE_CLEAN: | |
1380 | ; /* try to free the page below */ | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | /* | |
1385 | * If the page has buffers, try to free the buffer mappings | |
1386 | * associated with this page. If we succeed we try to free | |
1387 | * the page as well. | |
1388 | * | |
1389 | * We do this even if the page is PageDirty(). | |
1390 | * try_to_release_page() does not perform I/O, but it is | |
1391 | * possible for a page to have PageDirty set, but it is actually | |
1392 | * clean (all its buffers are clean). This happens if the | |
1393 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1394 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1395 | * try_to_release_page() will discover that cleanness and will |
1396 | * drop the buffers and mark the page clean - it can be freed. | |
1397 | * | |
1398 | * Rarely, pages can have buffers and no ->mapping. These are | |
1399 | * the pages which were not successfully invalidated in | |
1400 | * truncate_complete_page(). We try to drop those buffers here | |
1401 | * and if that worked, and the page is no longer mapped into | |
1402 | * process address space (page_count == 1) it can be freed. | |
1403 | * Otherwise, leave the page on the LRU so it is swappable. | |
1404 | */ | |
266cf658 | 1405 | if (page_has_private(page)) { |
1da177e4 LT |
1406 | if (!try_to_release_page(page, sc->gfp_mask)) |
1407 | goto activate_locked; | |
e286781d NP |
1408 | if (!mapping && page_count(page) == 1) { |
1409 | unlock_page(page); | |
1410 | if (put_page_testzero(page)) | |
1411 | goto free_it; | |
1412 | else { | |
1413 | /* | |
1414 | * rare race with speculative reference. | |
1415 | * the speculative reference will free | |
1416 | * this page shortly, so we may | |
1417 | * increment nr_reclaimed here (and | |
1418 | * leave it off the LRU). | |
1419 | */ | |
1420 | nr_reclaimed++; | |
1421 | continue; | |
1422 | } | |
1423 | } | |
1da177e4 LT |
1424 | } |
1425 | ||
802a3a92 SL |
1426 | if (PageAnon(page) && !PageSwapBacked(page)) { |
1427 | /* follow __remove_mapping for reference */ | |
1428 | if (!page_ref_freeze(page, 1)) | |
1429 | goto keep_locked; | |
1430 | if (PageDirty(page)) { | |
1431 | page_ref_unfreeze(page, 1); | |
1432 | goto keep_locked; | |
1433 | } | |
1da177e4 | 1434 | |
802a3a92 | 1435 | count_vm_event(PGLAZYFREED); |
2262185c | 1436 | count_memcg_page_event(page, PGLAZYFREED); |
802a3a92 SL |
1437 | } else if (!mapping || !__remove_mapping(mapping, page, true)) |
1438 | goto keep_locked; | |
a978d6f5 NP |
1439 | /* |
1440 | * At this point, we have no other references and there is | |
1441 | * no way to pick any more up (removed from LRU, removed | |
1442 | * from pagecache). Can use non-atomic bitops now (and | |
1443 | * we obviously don't have to worry about waking up a process | |
1444 | * waiting on the page lock, because there are no references. | |
1445 | */ | |
48c935ad | 1446 | __ClearPageLocked(page); |
e286781d | 1447 | free_it: |
05ff5137 | 1448 | nr_reclaimed++; |
abe4c3b5 MG |
1449 | |
1450 | /* | |
1451 | * Is there need to periodically free_page_list? It would | |
1452 | * appear not as the counts should be low | |
1453 | */ | |
bd4c82c2 HY |
1454 | if (unlikely(PageTransHuge(page))) { |
1455 | mem_cgroup_uncharge(page); | |
1456 | (*get_compound_page_dtor(page))(page); | |
1457 | } else | |
1458 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1459 | continue; |
1460 | ||
1461 | activate_locked: | |
68a22394 | 1462 | /* Not a candidate for swapping, so reclaim swap space. */ |
ad6b6704 MK |
1463 | if (PageSwapCache(page) && (mem_cgroup_swap_full(page) || |
1464 | PageMlocked(page))) | |
a2c43eed | 1465 | try_to_free_swap(page); |
309381fe | 1466 | VM_BUG_ON_PAGE(PageActive(page), page); |
ad6b6704 MK |
1467 | if (!PageMlocked(page)) { |
1468 | SetPageActive(page); | |
1469 | pgactivate++; | |
2262185c | 1470 | count_memcg_page_event(page, PGACTIVATE); |
ad6b6704 | 1471 | } |
1da177e4 LT |
1472 | keep_locked: |
1473 | unlock_page(page); | |
1474 | keep: | |
1475 | list_add(&page->lru, &ret_pages); | |
309381fe | 1476 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1477 | } |
abe4c3b5 | 1478 | |
747db954 | 1479 | mem_cgroup_uncharge_list(&free_pages); |
72b252ae | 1480 | try_to_unmap_flush(); |
2d4894b5 | 1481 | free_unref_page_list(&free_pages); |
abe4c3b5 | 1482 | |
1da177e4 | 1483 | list_splice(&ret_pages, page_list); |
f8891e5e | 1484 | count_vm_events(PGACTIVATE, pgactivate); |
0a31bc97 | 1485 | |
3c710c1a MH |
1486 | if (stat) { |
1487 | stat->nr_dirty = nr_dirty; | |
1488 | stat->nr_congested = nr_congested; | |
1489 | stat->nr_unqueued_dirty = nr_unqueued_dirty; | |
1490 | stat->nr_writeback = nr_writeback; | |
1491 | stat->nr_immediate = nr_immediate; | |
5bccd166 MH |
1492 | stat->nr_activate = pgactivate; |
1493 | stat->nr_ref_keep = nr_ref_keep; | |
1494 | stat->nr_unmap_fail = nr_unmap_fail; | |
3c710c1a | 1495 | } |
05ff5137 | 1496 | return nr_reclaimed; |
1da177e4 LT |
1497 | } |
1498 | ||
02c6de8d MK |
1499 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1500 | struct list_head *page_list) | |
1501 | { | |
1502 | struct scan_control sc = { | |
1503 | .gfp_mask = GFP_KERNEL, | |
1504 | .priority = DEF_PRIORITY, | |
1505 | .may_unmap = 1, | |
1506 | }; | |
3c710c1a | 1507 | unsigned long ret; |
02c6de8d MK |
1508 | struct page *page, *next; |
1509 | LIST_HEAD(clean_pages); | |
1510 | ||
1511 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e | 1512 | if (page_is_file_cache(page) && !PageDirty(page) && |
b1123ea6 | 1513 | !__PageMovable(page)) { |
02c6de8d MK |
1514 | ClearPageActive(page); |
1515 | list_move(&page->lru, &clean_pages); | |
1516 | } | |
1517 | } | |
1518 | ||
599d0c95 | 1519 | ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, |
a128ca71 | 1520 | TTU_IGNORE_ACCESS, NULL, true); |
02c6de8d | 1521 | list_splice(&clean_pages, page_list); |
599d0c95 | 1522 | mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); |
02c6de8d MK |
1523 | return ret; |
1524 | } | |
1525 | ||
5ad333eb AW |
1526 | /* |
1527 | * Attempt to remove the specified page from its LRU. Only take this page | |
1528 | * if it is of the appropriate PageActive status. Pages which are being | |
1529 | * freed elsewhere are also ignored. | |
1530 | * | |
1531 | * page: page to consider | |
1532 | * mode: one of the LRU isolation modes defined above | |
1533 | * | |
1534 | * returns 0 on success, -ve errno on failure. | |
1535 | */ | |
f3fd4a61 | 1536 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1537 | { |
1538 | int ret = -EINVAL; | |
1539 | ||
1540 | /* Only take pages on the LRU. */ | |
1541 | if (!PageLRU(page)) | |
1542 | return ret; | |
1543 | ||
e46a2879 MK |
1544 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1545 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1546 | return ret; |
1547 | ||
5ad333eb | 1548 | ret = -EBUSY; |
08e552c6 | 1549 | |
c8244935 MG |
1550 | /* |
1551 | * To minimise LRU disruption, the caller can indicate that it only | |
1552 | * wants to isolate pages it will be able to operate on without | |
1553 | * blocking - clean pages for the most part. | |
1554 | * | |
c8244935 MG |
1555 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages |
1556 | * that it is possible to migrate without blocking | |
1557 | */ | |
1276ad68 | 1558 | if (mode & ISOLATE_ASYNC_MIGRATE) { |
c8244935 MG |
1559 | /* All the caller can do on PageWriteback is block */ |
1560 | if (PageWriteback(page)) | |
1561 | return ret; | |
1562 | ||
1563 | if (PageDirty(page)) { | |
1564 | struct address_space *mapping; | |
69d763fc | 1565 | bool migrate_dirty; |
c8244935 | 1566 | |
c8244935 MG |
1567 | /* |
1568 | * Only pages without mappings or that have a | |
1569 | * ->migratepage callback are possible to migrate | |
69d763fc MG |
1570 | * without blocking. However, we can be racing with |
1571 | * truncation so it's necessary to lock the page | |
1572 | * to stabilise the mapping as truncation holds | |
1573 | * the page lock until after the page is removed | |
1574 | * from the page cache. | |
c8244935 | 1575 | */ |
69d763fc MG |
1576 | if (!trylock_page(page)) |
1577 | return ret; | |
1578 | ||
c8244935 | 1579 | mapping = page_mapping(page); |
145e1a71 | 1580 | migrate_dirty = !mapping || mapping->a_ops->migratepage; |
69d763fc MG |
1581 | unlock_page(page); |
1582 | if (!migrate_dirty) | |
c8244935 MG |
1583 | return ret; |
1584 | } | |
1585 | } | |
39deaf85 | 1586 | |
f80c0673 MK |
1587 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1588 | return ret; | |
1589 | ||
5ad333eb AW |
1590 | if (likely(get_page_unless_zero(page))) { |
1591 | /* | |
1592 | * Be careful not to clear PageLRU until after we're | |
1593 | * sure the page is not being freed elsewhere -- the | |
1594 | * page release code relies on it. | |
1595 | */ | |
1596 | ClearPageLRU(page); | |
1597 | ret = 0; | |
1598 | } | |
1599 | ||
1600 | return ret; | |
1601 | } | |
1602 | ||
7ee36a14 MG |
1603 | |
1604 | /* | |
1605 | * Update LRU sizes after isolating pages. The LRU size updates must | |
1606 | * be complete before mem_cgroup_update_lru_size due to a santity check. | |
1607 | */ | |
1608 | static __always_inline void update_lru_sizes(struct lruvec *lruvec, | |
b4536f0c | 1609 | enum lru_list lru, unsigned long *nr_zone_taken) |
7ee36a14 | 1610 | { |
7ee36a14 MG |
1611 | int zid; |
1612 | ||
7ee36a14 MG |
1613 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1614 | if (!nr_zone_taken[zid]) | |
1615 | continue; | |
1616 | ||
1617 | __update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); | |
7ee36a14 | 1618 | #ifdef CONFIG_MEMCG |
b4536f0c | 1619 | mem_cgroup_update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); |
7ee36a14 | 1620 | #endif |
b4536f0c MH |
1621 | } |
1622 | ||
7ee36a14 MG |
1623 | } |
1624 | ||
1da177e4 | 1625 | /* |
a52633d8 | 1626 | * zone_lru_lock is heavily contended. Some of the functions that |
1da177e4 LT |
1627 | * shrink the lists perform better by taking out a batch of pages |
1628 | * and working on them outside the LRU lock. | |
1629 | * | |
1630 | * For pagecache intensive workloads, this function is the hottest | |
1631 | * spot in the kernel (apart from copy_*_user functions). | |
1632 | * | |
1633 | * Appropriate locks must be held before calling this function. | |
1634 | * | |
791b48b6 | 1635 | * @nr_to_scan: The number of eligible pages to look through on the list. |
5dc35979 | 1636 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1637 | * @dst: The temp list to put pages on to. |
f626012d | 1638 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1639 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1640 | * @mode: One of the LRU isolation modes |
3cb99451 | 1641 | * @lru: LRU list id for isolating |
1da177e4 LT |
1642 | * |
1643 | * returns how many pages were moved onto *@dst. | |
1644 | */ | |
69e05944 | 1645 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1646 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1647 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1648 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1649 | { |
75b00af7 | 1650 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1651 | unsigned long nr_taken = 0; |
599d0c95 | 1652 | unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; |
7cc30fcf | 1653 | unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; |
3db65812 | 1654 | unsigned long skipped = 0; |
791b48b6 | 1655 | unsigned long scan, total_scan, nr_pages; |
b2e18757 | 1656 | LIST_HEAD(pages_skipped); |
1da177e4 | 1657 | |
791b48b6 MK |
1658 | scan = 0; |
1659 | for (total_scan = 0; | |
1660 | scan < nr_to_scan && nr_taken < nr_to_scan && !list_empty(src); | |
1661 | total_scan++) { | |
5ad333eb | 1662 | struct page *page; |
5ad333eb | 1663 | |
1da177e4 LT |
1664 | page = lru_to_page(src); |
1665 | prefetchw_prev_lru_page(page, src, flags); | |
1666 | ||
309381fe | 1667 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1668 | |
b2e18757 MG |
1669 | if (page_zonenum(page) > sc->reclaim_idx) { |
1670 | list_move(&page->lru, &pages_skipped); | |
7cc30fcf | 1671 | nr_skipped[page_zonenum(page)]++; |
b2e18757 MG |
1672 | continue; |
1673 | } | |
1674 | ||
791b48b6 MK |
1675 | /* |
1676 | * Do not count skipped pages because that makes the function | |
1677 | * return with no isolated pages if the LRU mostly contains | |
1678 | * ineligible pages. This causes the VM to not reclaim any | |
1679 | * pages, triggering a premature OOM. | |
1680 | */ | |
1681 | scan++; | |
f3fd4a61 | 1682 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1683 | case 0: |
599d0c95 MG |
1684 | nr_pages = hpage_nr_pages(page); |
1685 | nr_taken += nr_pages; | |
1686 | nr_zone_taken[page_zonenum(page)] += nr_pages; | |
5ad333eb | 1687 | list_move(&page->lru, dst); |
5ad333eb AW |
1688 | break; |
1689 | ||
1690 | case -EBUSY: | |
1691 | /* else it is being freed elsewhere */ | |
1692 | list_move(&page->lru, src); | |
1693 | continue; | |
46453a6e | 1694 | |
5ad333eb AW |
1695 | default: |
1696 | BUG(); | |
1697 | } | |
1da177e4 LT |
1698 | } |
1699 | ||
b2e18757 MG |
1700 | /* |
1701 | * Splice any skipped pages to the start of the LRU list. Note that | |
1702 | * this disrupts the LRU order when reclaiming for lower zones but | |
1703 | * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX | |
1704 | * scanning would soon rescan the same pages to skip and put the | |
1705 | * system at risk of premature OOM. | |
1706 | */ | |
7cc30fcf MG |
1707 | if (!list_empty(&pages_skipped)) { |
1708 | int zid; | |
1709 | ||
3db65812 | 1710 | list_splice(&pages_skipped, src); |
7cc30fcf MG |
1711 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1712 | if (!nr_skipped[zid]) | |
1713 | continue; | |
1714 | ||
1715 | __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); | |
1265e3a6 | 1716 | skipped += nr_skipped[zid]; |
7cc30fcf MG |
1717 | } |
1718 | } | |
791b48b6 | 1719 | *nr_scanned = total_scan; |
1265e3a6 | 1720 | trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, |
791b48b6 | 1721 | total_scan, skipped, nr_taken, mode, lru); |
b4536f0c | 1722 | update_lru_sizes(lruvec, lru, nr_zone_taken); |
1da177e4 LT |
1723 | return nr_taken; |
1724 | } | |
1725 | ||
62695a84 NP |
1726 | /** |
1727 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1728 | * @page: page to isolate from its LRU list | |
1729 | * | |
1730 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1731 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1732 | * | |
1733 | * Returns 0 if the page was removed from an LRU list. | |
1734 | * Returns -EBUSY if the page was not on an LRU list. | |
1735 | * | |
1736 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1737 | * the active list, it will have PageActive set. If it was found on |
1738 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1739 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1740 | * |
1741 | * The vmstat statistic corresponding to the list on which the page was | |
1742 | * found will be decremented. | |
1743 | * | |
1744 | * Restrictions: | |
a5d09bed | 1745 | * |
62695a84 NP |
1746 | * (1) Must be called with an elevated refcount on the page. This is a |
1747 | * fundamentnal difference from isolate_lru_pages (which is called | |
1748 | * without a stable reference). | |
1749 | * (2) the lru_lock must not be held. | |
1750 | * (3) interrupts must be enabled. | |
1751 | */ | |
1752 | int isolate_lru_page(struct page *page) | |
1753 | { | |
1754 | int ret = -EBUSY; | |
1755 | ||
309381fe | 1756 | VM_BUG_ON_PAGE(!page_count(page), page); |
cf2a82ee | 1757 | WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); |
0c917313 | 1758 | |
62695a84 NP |
1759 | if (PageLRU(page)) { |
1760 | struct zone *zone = page_zone(page); | |
fa9add64 | 1761 | struct lruvec *lruvec; |
62695a84 | 1762 | |
a52633d8 | 1763 | spin_lock_irq(zone_lru_lock(zone)); |
599d0c95 | 1764 | lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); |
0c917313 | 1765 | if (PageLRU(page)) { |
894bc310 | 1766 | int lru = page_lru(page); |
0c917313 | 1767 | get_page(page); |
62695a84 | 1768 | ClearPageLRU(page); |
fa9add64 HD |
1769 | del_page_from_lru_list(page, lruvec, lru); |
1770 | ret = 0; | |
62695a84 | 1771 | } |
a52633d8 | 1772 | spin_unlock_irq(zone_lru_lock(zone)); |
62695a84 NP |
1773 | } |
1774 | return ret; | |
1775 | } | |
1776 | ||
35cd7815 | 1777 | /* |
d37dd5dc FW |
1778 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1779 | * then get resheduled. When there are massive number of tasks doing page | |
1780 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1781 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1782 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 | 1783 | */ |
599d0c95 | 1784 | static int too_many_isolated(struct pglist_data *pgdat, int file, |
35cd7815 RR |
1785 | struct scan_control *sc) |
1786 | { | |
1787 | unsigned long inactive, isolated; | |
1788 | ||
1789 | if (current_is_kswapd()) | |
1790 | return 0; | |
1791 | ||
97c9341f | 1792 | if (!sane_reclaim(sc)) |
35cd7815 RR |
1793 | return 0; |
1794 | ||
1795 | if (file) { | |
599d0c95 MG |
1796 | inactive = node_page_state(pgdat, NR_INACTIVE_FILE); |
1797 | isolated = node_page_state(pgdat, NR_ISOLATED_FILE); | |
35cd7815 | 1798 | } else { |
599d0c95 MG |
1799 | inactive = node_page_state(pgdat, NR_INACTIVE_ANON); |
1800 | isolated = node_page_state(pgdat, NR_ISOLATED_ANON); | |
35cd7815 RR |
1801 | } |
1802 | ||
3cf23841 FW |
1803 | /* |
1804 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1805 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1806 | * deadlock. | |
1807 | */ | |
d0164adc | 1808 | if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS)) |
3cf23841 FW |
1809 | inactive >>= 3; |
1810 | ||
35cd7815 RR |
1811 | return isolated > inactive; |
1812 | } | |
1813 | ||
66635629 | 1814 | static noinline_for_stack void |
75b00af7 | 1815 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1816 | { |
27ac81d8 | 1817 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
599d0c95 | 1818 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3f79768f | 1819 | LIST_HEAD(pages_to_free); |
66635629 | 1820 | |
66635629 MG |
1821 | /* |
1822 | * Put back any unfreeable pages. | |
1823 | */ | |
66635629 | 1824 | while (!list_empty(page_list)) { |
3f79768f | 1825 | struct page *page = lru_to_page(page_list); |
66635629 | 1826 | int lru; |
3f79768f | 1827 | |
309381fe | 1828 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1829 | list_del(&page->lru); |
39b5f29a | 1830 | if (unlikely(!page_evictable(page))) { |
599d0c95 | 1831 | spin_unlock_irq(&pgdat->lru_lock); |
66635629 | 1832 | putback_lru_page(page); |
599d0c95 | 1833 | spin_lock_irq(&pgdat->lru_lock); |
66635629 MG |
1834 | continue; |
1835 | } | |
fa9add64 | 1836 | |
599d0c95 | 1837 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
fa9add64 | 1838 | |
7a608572 | 1839 | SetPageLRU(page); |
66635629 | 1840 | lru = page_lru(page); |
fa9add64 HD |
1841 | add_page_to_lru_list(page, lruvec, lru); |
1842 | ||
66635629 MG |
1843 | if (is_active_lru(lru)) { |
1844 | int file = is_file_lru(lru); | |
9992af10 RR |
1845 | int numpages = hpage_nr_pages(page); |
1846 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1847 | } |
2bcf8879 HD |
1848 | if (put_page_testzero(page)) { |
1849 | __ClearPageLRU(page); | |
1850 | __ClearPageActive(page); | |
fa9add64 | 1851 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1852 | |
1853 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 1854 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 1855 | mem_cgroup_uncharge(page); |
2bcf8879 | 1856 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 1857 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
1858 | } else |
1859 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1860 | } |
1861 | } | |
66635629 | 1862 | |
3f79768f HD |
1863 | /* |
1864 | * To save our caller's stack, now use input list for pages to free. | |
1865 | */ | |
1866 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1867 | } |
1868 | ||
399ba0b9 N |
1869 | /* |
1870 | * If a kernel thread (such as nfsd for loop-back mounts) services | |
1871 | * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. | |
1872 | * In that case we should only throttle if the backing device it is | |
1873 | * writing to is congested. In other cases it is safe to throttle. | |
1874 | */ | |
1875 | static int current_may_throttle(void) | |
1876 | { | |
1877 | return !(current->flags & PF_LESS_THROTTLE) || | |
1878 | current->backing_dev_info == NULL || | |
1879 | bdi_write_congested(current->backing_dev_info); | |
1880 | } | |
1881 | ||
1da177e4 | 1882 | /* |
b2e18757 | 1883 | * shrink_inactive_list() is a helper for shrink_node(). It returns the number |
1742f19f | 1884 | * of reclaimed pages |
1da177e4 | 1885 | */ |
66635629 | 1886 | static noinline_for_stack unsigned long |
1a93be0e | 1887 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1888 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1889 | { |
1890 | LIST_HEAD(page_list); | |
e247dbce | 1891 | unsigned long nr_scanned; |
05ff5137 | 1892 | unsigned long nr_reclaimed = 0; |
e247dbce | 1893 | unsigned long nr_taken; |
3c710c1a | 1894 | struct reclaim_stat stat = {}; |
f3fd4a61 | 1895 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1896 | int file = is_file_lru(lru); |
599d0c95 | 1897 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1a93be0e | 1898 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
db73ee0d | 1899 | bool stalled = false; |
78dc583d | 1900 | |
599d0c95 | 1901 | while (unlikely(too_many_isolated(pgdat, file, sc))) { |
db73ee0d MH |
1902 | if (stalled) |
1903 | return 0; | |
1904 | ||
1905 | /* wait a bit for the reclaimer. */ | |
1906 | msleep(100); | |
1907 | stalled = true; | |
35cd7815 RR |
1908 | |
1909 | /* We are about to die and free our memory. Return now. */ | |
1910 | if (fatal_signal_pending(current)) | |
1911 | return SWAP_CLUSTER_MAX; | |
1912 | } | |
1913 | ||
1da177e4 | 1914 | lru_add_drain(); |
f80c0673 MK |
1915 | |
1916 | if (!sc->may_unmap) | |
61317289 | 1917 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1918 | |
599d0c95 | 1919 | spin_lock_irq(&pgdat->lru_lock); |
b35ea17b | 1920 | |
5dc35979 KK |
1921 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1922 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc | 1923 | |
599d0c95 | 1924 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
9d5e6a9f | 1925 | reclaim_stat->recent_scanned[file] += nr_taken; |
95d918fc | 1926 | |
2262185c RG |
1927 | if (current_is_kswapd()) { |
1928 | if (global_reclaim(sc)) | |
599d0c95 | 1929 | __count_vm_events(PGSCAN_KSWAPD, nr_scanned); |
2262185c RG |
1930 | count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD, |
1931 | nr_scanned); | |
1932 | } else { | |
1933 | if (global_reclaim(sc)) | |
599d0c95 | 1934 | __count_vm_events(PGSCAN_DIRECT, nr_scanned); |
2262185c RG |
1935 | count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT, |
1936 | nr_scanned); | |
e247dbce | 1937 | } |
599d0c95 | 1938 | spin_unlock_irq(&pgdat->lru_lock); |
b35ea17b | 1939 | |
d563c050 | 1940 | if (nr_taken == 0) |
66635629 | 1941 | return 0; |
5ad333eb | 1942 | |
a128ca71 | 1943 | nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, 0, |
3c710c1a | 1944 | &stat, false); |
c661b078 | 1945 | |
599d0c95 | 1946 | spin_lock_irq(&pgdat->lru_lock); |
3f79768f | 1947 | |
2262185c RG |
1948 | if (current_is_kswapd()) { |
1949 | if (global_reclaim(sc)) | |
599d0c95 | 1950 | __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); |
2262185c RG |
1951 | count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD, |
1952 | nr_reclaimed); | |
1953 | } else { | |
1954 | if (global_reclaim(sc)) | |
599d0c95 | 1955 | __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); |
2262185c RG |
1956 | count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT, |
1957 | nr_reclaimed); | |
904249aa | 1958 | } |
a74609fa | 1959 | |
27ac81d8 | 1960 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1961 | |
599d0c95 | 1962 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f | 1963 | |
599d0c95 | 1964 | spin_unlock_irq(&pgdat->lru_lock); |
3f79768f | 1965 | |
747db954 | 1966 | mem_cgroup_uncharge_list(&page_list); |
2d4894b5 | 1967 | free_unref_page_list(&page_list); |
e11da5b4 | 1968 | |
1c610d5f AR |
1969 | /* |
1970 | * If dirty pages are scanned that are not queued for IO, it | |
1971 | * implies that flushers are not doing their job. This can | |
1972 | * happen when memory pressure pushes dirty pages to the end of | |
1973 | * the LRU before the dirty limits are breached and the dirty | |
1974 | * data has expired. It can also happen when the proportion of | |
1975 | * dirty pages grows not through writes but through memory | |
1976 | * pressure reclaiming all the clean cache. And in some cases, | |
1977 | * the flushers simply cannot keep up with the allocation | |
1978 | * rate. Nudge the flusher threads in case they are asleep. | |
1979 | */ | |
1980 | if (stat.nr_unqueued_dirty == nr_taken) | |
1981 | wakeup_flusher_threads(WB_REASON_VMSCAN); | |
1982 | ||
d108c772 AR |
1983 | sc->nr.dirty += stat.nr_dirty; |
1984 | sc->nr.congested += stat.nr_congested; | |
1985 | sc->nr.unqueued_dirty += stat.nr_unqueued_dirty; | |
1986 | sc->nr.writeback += stat.nr_writeback; | |
1987 | sc->nr.immediate += stat.nr_immediate; | |
1988 | sc->nr.taken += nr_taken; | |
1989 | if (file) | |
1990 | sc->nr.file_taken += nr_taken; | |
8e950282 | 1991 | |
599d0c95 | 1992 | trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, |
d51d1e64 | 1993 | nr_scanned, nr_reclaimed, &stat, sc->priority, file); |
05ff5137 | 1994 | return nr_reclaimed; |
1da177e4 LT |
1995 | } |
1996 | ||
1997 | /* | |
1998 | * This moves pages from the active list to the inactive list. | |
1999 | * | |
2000 | * We move them the other way if the page is referenced by one or more | |
2001 | * processes, from rmap. | |
2002 | * | |
2003 | * If the pages are mostly unmapped, the processing is fast and it is | |
a52633d8 | 2004 | * appropriate to hold zone_lru_lock across the whole operation. But if |
1da177e4 | 2005 | * the pages are mapped, the processing is slow (page_referenced()) so we |
a52633d8 | 2006 | * should drop zone_lru_lock around each page. It's impossible to balance |
1da177e4 LT |
2007 | * this, so instead we remove the pages from the LRU while processing them. |
2008 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
2009 | * nobody will play with that bit on a non-LRU page. | |
2010 | * | |
0139aa7b | 2011 | * The downside is that we have to touch page->_refcount against each page. |
1da177e4 | 2012 | * But we had to alter page->flags anyway. |
9d998b4f MH |
2013 | * |
2014 | * Returns the number of pages moved to the given lru. | |
1da177e4 | 2015 | */ |
1cfb419b | 2016 | |
9d998b4f | 2017 | static unsigned move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 2018 | struct list_head *list, |
2bcf8879 | 2019 | struct list_head *pages_to_free, |
3eb4140f WF |
2020 | enum lru_list lru) |
2021 | { | |
599d0c95 | 2022 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3eb4140f | 2023 | struct page *page; |
fa9add64 | 2024 | int nr_pages; |
9d998b4f | 2025 | int nr_moved = 0; |
3eb4140f | 2026 | |
3eb4140f WF |
2027 | while (!list_empty(list)) { |
2028 | page = lru_to_page(list); | |
599d0c95 | 2029 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
3eb4140f | 2030 | |
309381fe | 2031 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
2032 | SetPageLRU(page); |
2033 | ||
fa9add64 | 2034 | nr_pages = hpage_nr_pages(page); |
599d0c95 | 2035 | update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); |
925b7673 | 2036 | list_move(&page->lru, &lruvec->lists[lru]); |
3eb4140f | 2037 | |
2bcf8879 HD |
2038 | if (put_page_testzero(page)) { |
2039 | __ClearPageLRU(page); | |
2040 | __ClearPageActive(page); | |
fa9add64 | 2041 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
2042 | |
2043 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 2044 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 2045 | mem_cgroup_uncharge(page); |
2bcf8879 | 2046 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 2047 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
2048 | } else |
2049 | list_add(&page->lru, pages_to_free); | |
9d998b4f MH |
2050 | } else { |
2051 | nr_moved += nr_pages; | |
3eb4140f WF |
2052 | } |
2053 | } | |
9d5e6a9f | 2054 | |
2262185c | 2055 | if (!is_active_lru(lru)) { |
f0958906 | 2056 | __count_vm_events(PGDEACTIVATE, nr_moved); |
2262185c RG |
2057 | count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, |
2058 | nr_moved); | |
2059 | } | |
9d998b4f MH |
2060 | |
2061 | return nr_moved; | |
3eb4140f | 2062 | } |
1cfb419b | 2063 | |
f626012d | 2064 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 2065 | struct lruvec *lruvec, |
f16015fb | 2066 | struct scan_control *sc, |
9e3b2f8c | 2067 | enum lru_list lru) |
1da177e4 | 2068 | { |
44c241f1 | 2069 | unsigned long nr_taken; |
f626012d | 2070 | unsigned long nr_scanned; |
6fe6b7e3 | 2071 | unsigned long vm_flags; |
1da177e4 | 2072 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 2073 | LIST_HEAD(l_active); |
b69408e8 | 2074 | LIST_HEAD(l_inactive); |
1da177e4 | 2075 | struct page *page; |
1a93be0e | 2076 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
9d998b4f MH |
2077 | unsigned nr_deactivate, nr_activate; |
2078 | unsigned nr_rotated = 0; | |
f3fd4a61 | 2079 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 2080 | int file = is_file_lru(lru); |
599d0c95 | 2081 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1da177e4 LT |
2082 | |
2083 | lru_add_drain(); | |
f80c0673 MK |
2084 | |
2085 | if (!sc->may_unmap) | |
61317289 | 2086 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 2087 | |
599d0c95 | 2088 | spin_lock_irq(&pgdat->lru_lock); |
925b7673 | 2089 | |
5dc35979 KK |
2090 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
2091 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 2092 | |
599d0c95 | 2093 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
b7c46d15 | 2094 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 2095 | |
599d0c95 | 2096 | __count_vm_events(PGREFILL, nr_scanned); |
2262185c | 2097 | count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned); |
9d5e6a9f | 2098 | |
599d0c95 | 2099 | spin_unlock_irq(&pgdat->lru_lock); |
1da177e4 | 2100 | |
1da177e4 LT |
2101 | while (!list_empty(&l_hold)) { |
2102 | cond_resched(); | |
2103 | page = lru_to_page(&l_hold); | |
2104 | list_del(&page->lru); | |
7e9cd484 | 2105 | |
39b5f29a | 2106 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
2107 | putback_lru_page(page); |
2108 | continue; | |
2109 | } | |
2110 | ||
cc715d99 MG |
2111 | if (unlikely(buffer_heads_over_limit)) { |
2112 | if (page_has_private(page) && trylock_page(page)) { | |
2113 | if (page_has_private(page)) | |
2114 | try_to_release_page(page, 0); | |
2115 | unlock_page(page); | |
2116 | } | |
2117 | } | |
2118 | ||
c3ac9a8a JW |
2119 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
2120 | &vm_flags)) { | |
9992af10 | 2121 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
2122 | /* |
2123 | * Identify referenced, file-backed active pages and | |
2124 | * give them one more trip around the active list. So | |
2125 | * that executable code get better chances to stay in | |
2126 | * memory under moderate memory pressure. Anon pages | |
2127 | * are not likely to be evicted by use-once streaming | |
2128 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
2129 | * so we ignore them here. | |
2130 | */ | |
41e20983 | 2131 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
2132 | list_add(&page->lru, &l_active); |
2133 | continue; | |
2134 | } | |
2135 | } | |
7e9cd484 | 2136 | |
5205e56e | 2137 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
2138 | list_add(&page->lru, &l_inactive); |
2139 | } | |
2140 | ||
b555749a | 2141 | /* |
8cab4754 | 2142 | * Move pages back to the lru list. |
b555749a | 2143 | */ |
599d0c95 | 2144 | spin_lock_irq(&pgdat->lru_lock); |
556adecb | 2145 | /* |
8cab4754 WF |
2146 | * Count referenced pages from currently used mappings as rotated, |
2147 | * even though only some of them are actually re-activated. This | |
2148 | * helps balance scan pressure between file and anonymous pages in | |
7c0db9e9 | 2149 | * get_scan_count. |
7e9cd484 | 2150 | */ |
b7c46d15 | 2151 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 2152 | |
9d998b4f MH |
2153 | nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
2154 | nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
599d0c95 MG |
2155 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
2156 | spin_unlock_irq(&pgdat->lru_lock); | |
2bcf8879 | 2157 | |
747db954 | 2158 | mem_cgroup_uncharge_list(&l_hold); |
2d4894b5 | 2159 | free_unref_page_list(&l_hold); |
9d998b4f MH |
2160 | trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate, |
2161 | nr_deactivate, nr_rotated, sc->priority, file); | |
1da177e4 LT |
2162 | } |
2163 | ||
59dc76b0 RR |
2164 | /* |
2165 | * The inactive anon list should be small enough that the VM never has | |
2166 | * to do too much work. | |
14797e23 | 2167 | * |
59dc76b0 RR |
2168 | * The inactive file list should be small enough to leave most memory |
2169 | * to the established workingset on the scan-resistant active list, | |
2170 | * but large enough to avoid thrashing the aggregate readahead window. | |
56e49d21 | 2171 | * |
59dc76b0 RR |
2172 | * Both inactive lists should also be large enough that each inactive |
2173 | * page has a chance to be referenced again before it is reclaimed. | |
56e49d21 | 2174 | * |
2a2e4885 JW |
2175 | * If that fails and refaulting is observed, the inactive list grows. |
2176 | * | |
59dc76b0 | 2177 | * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages |
3a50d14d | 2178 | * on this LRU, maintained by the pageout code. An inactive_ratio |
59dc76b0 | 2179 | * of 3 means 3:1 or 25% of the pages are kept on the inactive list. |
56e49d21 | 2180 | * |
59dc76b0 RR |
2181 | * total target max |
2182 | * memory ratio inactive | |
2183 | * ------------------------------------- | |
2184 | * 10MB 1 5MB | |
2185 | * 100MB 1 50MB | |
2186 | * 1GB 3 250MB | |
2187 | * 10GB 10 0.9GB | |
2188 | * 100GB 31 3GB | |
2189 | * 1TB 101 10GB | |
2190 | * 10TB 320 32GB | |
56e49d21 | 2191 | */ |
f8d1a311 | 2192 | static bool inactive_list_is_low(struct lruvec *lruvec, bool file, |
2a2e4885 JW |
2193 | struct mem_cgroup *memcg, |
2194 | struct scan_control *sc, bool actual_reclaim) | |
56e49d21 | 2195 | { |
fd538803 | 2196 | enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE; |
2a2e4885 JW |
2197 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
2198 | enum lru_list inactive_lru = file * LRU_FILE; | |
2199 | unsigned long inactive, active; | |
2200 | unsigned long inactive_ratio; | |
2201 | unsigned long refaults; | |
59dc76b0 | 2202 | unsigned long gb; |
e3790144 | 2203 | |
59dc76b0 RR |
2204 | /* |
2205 | * If we don't have swap space, anonymous page deactivation | |
2206 | * is pointless. | |
2207 | */ | |
2208 | if (!file && !total_swap_pages) | |
2209 | return false; | |
56e49d21 | 2210 | |
fd538803 MH |
2211 | inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx); |
2212 | active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx); | |
f8d1a311 | 2213 | |
2a2e4885 | 2214 | if (memcg) |
ccda7f43 | 2215 | refaults = memcg_page_state(memcg, WORKINGSET_ACTIVATE); |
b39415b2 | 2216 | else |
2a2e4885 JW |
2217 | refaults = node_page_state(pgdat, WORKINGSET_ACTIVATE); |
2218 | ||
2219 | /* | |
2220 | * When refaults are being observed, it means a new workingset | |
2221 | * is being established. Disable active list protection to get | |
2222 | * rid of the stale workingset quickly. | |
2223 | */ | |
2224 | if (file && actual_reclaim && lruvec->refaults != refaults) { | |
2225 | inactive_ratio = 0; | |
2226 | } else { | |
2227 | gb = (inactive + active) >> (30 - PAGE_SHIFT); | |
2228 | if (gb) | |
2229 | inactive_ratio = int_sqrt(10 * gb); | |
2230 | else | |
2231 | inactive_ratio = 1; | |
2232 | } | |
59dc76b0 | 2233 | |
2a2e4885 JW |
2234 | if (actual_reclaim) |
2235 | trace_mm_vmscan_inactive_list_is_low(pgdat->node_id, sc->reclaim_idx, | |
2236 | lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive, | |
2237 | lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active, | |
2238 | inactive_ratio, file); | |
fd538803 | 2239 | |
59dc76b0 | 2240 | return inactive * inactive_ratio < active; |
b39415b2 RR |
2241 | } |
2242 | ||
4f98a2fe | 2243 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
2a2e4885 JW |
2244 | struct lruvec *lruvec, struct mem_cgroup *memcg, |
2245 | struct scan_control *sc) | |
b69408e8 | 2246 | { |
b39415b2 | 2247 | if (is_active_lru(lru)) { |
2a2e4885 JW |
2248 | if (inactive_list_is_low(lruvec, is_file_lru(lru), |
2249 | memcg, sc, true)) | |
1a93be0e | 2250 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
2251 | return 0; |
2252 | } | |
2253 | ||
1a93be0e | 2254 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
2255 | } |
2256 | ||
9a265114 JW |
2257 | enum scan_balance { |
2258 | SCAN_EQUAL, | |
2259 | SCAN_FRACT, | |
2260 | SCAN_ANON, | |
2261 | SCAN_FILE, | |
2262 | }; | |
2263 | ||
4f98a2fe RR |
2264 | /* |
2265 | * Determine how aggressively the anon and file LRU lists should be | |
2266 | * scanned. The relative value of each set of LRU lists is determined | |
2267 | * by looking at the fraction of the pages scanned we did rotate back | |
2268 | * onto the active list instead of evict. | |
2269 | * | |
be7bd59d WL |
2270 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
2271 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 2272 | */ |
33377678 | 2273 | static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, |
6b4f7799 JW |
2274 | struct scan_control *sc, unsigned long *nr, |
2275 | unsigned long *lru_pages) | |
4f98a2fe | 2276 | { |
33377678 | 2277 | int swappiness = mem_cgroup_swappiness(memcg); |
9a265114 JW |
2278 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
2279 | u64 fraction[2]; | |
2280 | u64 denominator = 0; /* gcc */ | |
599d0c95 | 2281 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
4f98a2fe | 2282 | unsigned long anon_prio, file_prio; |
9a265114 | 2283 | enum scan_balance scan_balance; |
0bf1457f | 2284 | unsigned long anon, file; |
4f98a2fe | 2285 | unsigned long ap, fp; |
4111304d | 2286 | enum lru_list lru; |
76a33fc3 SL |
2287 | |
2288 | /* If we have no swap space, do not bother scanning anon pages. */ | |
d8b38438 | 2289 | if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { |
9a265114 | 2290 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
2291 | goto out; |
2292 | } | |
4f98a2fe | 2293 | |
10316b31 JW |
2294 | /* |
2295 | * Global reclaim will swap to prevent OOM even with no | |
2296 | * swappiness, but memcg users want to use this knob to | |
2297 | * disable swapping for individual groups completely when | |
2298 | * using the memory controller's swap limit feature would be | |
2299 | * too expensive. | |
2300 | */ | |
02695175 | 2301 | if (!global_reclaim(sc) && !swappiness) { |
9a265114 | 2302 | scan_balance = SCAN_FILE; |
10316b31 JW |
2303 | goto out; |
2304 | } | |
2305 | ||
2306 | /* | |
2307 | * Do not apply any pressure balancing cleverness when the | |
2308 | * system is close to OOM, scan both anon and file equally | |
2309 | * (unless the swappiness setting disagrees with swapping). | |
2310 | */ | |
02695175 | 2311 | if (!sc->priority && swappiness) { |
9a265114 | 2312 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
2313 | goto out; |
2314 | } | |
2315 | ||
62376251 JW |
2316 | /* |
2317 | * Prevent the reclaimer from falling into the cache trap: as | |
2318 | * cache pages start out inactive, every cache fault will tip | |
2319 | * the scan balance towards the file LRU. And as the file LRU | |
2320 | * shrinks, so does the window for rotation from references. | |
2321 | * This means we have a runaway feedback loop where a tiny | |
2322 | * thrashing file LRU becomes infinitely more attractive than | |
2323 | * anon pages. Try to detect this based on file LRU size. | |
2324 | */ | |
2325 | if (global_reclaim(sc)) { | |
599d0c95 MG |
2326 | unsigned long pgdatfile; |
2327 | unsigned long pgdatfree; | |
2328 | int z; | |
2329 | unsigned long total_high_wmark = 0; | |
2ab051e1 | 2330 | |
599d0c95 MG |
2331 | pgdatfree = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); |
2332 | pgdatfile = node_page_state(pgdat, NR_ACTIVE_FILE) + | |
2333 | node_page_state(pgdat, NR_INACTIVE_FILE); | |
2334 | ||
2335 | for (z = 0; z < MAX_NR_ZONES; z++) { | |
2336 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2337 | if (!managed_zone(zone)) |
599d0c95 MG |
2338 | continue; |
2339 | ||
2340 | total_high_wmark += high_wmark_pages(zone); | |
2341 | } | |
62376251 | 2342 | |
599d0c95 | 2343 | if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) { |
06226226 DR |
2344 | /* |
2345 | * Force SCAN_ANON if there are enough inactive | |
2346 | * anonymous pages on the LRU in eligible zones. | |
2347 | * Otherwise, the small LRU gets thrashed. | |
2348 | */ | |
2349 | if (!inactive_list_is_low(lruvec, false, memcg, sc, false) && | |
2350 | lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, sc->reclaim_idx) | |
2351 | >> sc->priority) { | |
2352 | scan_balance = SCAN_ANON; | |
2353 | goto out; | |
2354 | } | |
62376251 JW |
2355 | } |
2356 | } | |
2357 | ||
7c5bd705 | 2358 | /* |
316bda0e VD |
2359 | * If there is enough inactive page cache, i.e. if the size of the |
2360 | * inactive list is greater than that of the active list *and* the | |
2361 | * inactive list actually has some pages to scan on this priority, we | |
2362 | * do not reclaim anything from the anonymous working set right now. | |
2363 | * Without the second condition we could end up never scanning an | |
2364 | * lruvec even if it has plenty of old anonymous pages unless the | |
2365 | * system is under heavy pressure. | |
7c5bd705 | 2366 | */ |
2a2e4885 | 2367 | if (!inactive_list_is_low(lruvec, true, memcg, sc, false) && |
71ab6cfe | 2368 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) { |
9a265114 | 2369 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
2370 | goto out; |
2371 | } | |
2372 | ||
9a265114 JW |
2373 | scan_balance = SCAN_FRACT; |
2374 | ||
58c37f6e KM |
2375 | /* |
2376 | * With swappiness at 100, anonymous and file have the same priority. | |
2377 | * This scanning priority is essentially the inverse of IO cost. | |
2378 | */ | |
02695175 | 2379 | anon_prio = swappiness; |
75b00af7 | 2380 | file_prio = 200 - anon_prio; |
58c37f6e | 2381 | |
4f98a2fe RR |
2382 | /* |
2383 | * OK, so we have swap space and a fair amount of page cache | |
2384 | * pages. We use the recently rotated / recently scanned | |
2385 | * ratios to determine how valuable each cache is. | |
2386 | * | |
2387 | * Because workloads change over time (and to avoid overflow) | |
2388 | * we keep these statistics as a floating average, which ends | |
2389 | * up weighing recent references more than old ones. | |
2390 | * | |
2391 | * anon in [0], file in [1] | |
2392 | */ | |
2ab051e1 | 2393 | |
fd538803 MH |
2394 | anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) + |
2395 | lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES); | |
2396 | file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + | |
2397 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); | |
2ab051e1 | 2398 | |
599d0c95 | 2399 | spin_lock_irq(&pgdat->lru_lock); |
6e901571 | 2400 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
2401 | reclaim_stat->recent_scanned[0] /= 2; |
2402 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
2403 | } |
2404 | ||
6e901571 | 2405 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
2406 | reclaim_stat->recent_scanned[1] /= 2; |
2407 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
2408 | } |
2409 | ||
4f98a2fe | 2410 | /* |
00d8089c RR |
2411 | * The amount of pressure on anon vs file pages is inversely |
2412 | * proportional to the fraction of recently scanned pages on | |
2413 | * each list that were recently referenced and in active use. | |
4f98a2fe | 2414 | */ |
fe35004f | 2415 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 2416 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 2417 | |
fe35004f | 2418 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 2419 | fp /= reclaim_stat->recent_rotated[1] + 1; |
599d0c95 | 2420 | spin_unlock_irq(&pgdat->lru_lock); |
4f98a2fe | 2421 | |
76a33fc3 SL |
2422 | fraction[0] = ap; |
2423 | fraction[1] = fp; | |
2424 | denominator = ap + fp + 1; | |
2425 | out: | |
688035f7 JW |
2426 | *lru_pages = 0; |
2427 | for_each_evictable_lru(lru) { | |
2428 | int file = is_file_lru(lru); | |
2429 | unsigned long size; | |
2430 | unsigned long scan; | |
6b4f7799 | 2431 | |
688035f7 JW |
2432 | size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); |
2433 | scan = size >> sc->priority; | |
2434 | /* | |
2435 | * If the cgroup's already been deleted, make sure to | |
2436 | * scrape out the remaining cache. | |
2437 | */ | |
2438 | if (!scan && !mem_cgroup_online(memcg)) | |
2439 | scan = min(size, SWAP_CLUSTER_MAX); | |
6b4f7799 | 2440 | |
688035f7 JW |
2441 | switch (scan_balance) { |
2442 | case SCAN_EQUAL: | |
2443 | /* Scan lists relative to size */ | |
2444 | break; | |
2445 | case SCAN_FRACT: | |
9a265114 | 2446 | /* |
688035f7 JW |
2447 | * Scan types proportional to swappiness and |
2448 | * their relative recent reclaim efficiency. | |
9a265114 | 2449 | */ |
688035f7 JW |
2450 | scan = div64_u64(scan * fraction[file], |
2451 | denominator); | |
2452 | break; | |
2453 | case SCAN_FILE: | |
2454 | case SCAN_ANON: | |
2455 | /* Scan one type exclusively */ | |
2456 | if ((scan_balance == SCAN_FILE) != file) { | |
2457 | size = 0; | |
2458 | scan = 0; | |
2459 | } | |
2460 | break; | |
2461 | default: | |
2462 | /* Look ma, no brain */ | |
2463 | BUG(); | |
9a265114 | 2464 | } |
688035f7 JW |
2465 | |
2466 | *lru_pages += size; | |
2467 | nr[lru] = scan; | |
76a33fc3 | 2468 | } |
6e08a369 | 2469 | } |
4f98a2fe | 2470 | |
9b4f98cd | 2471 | /* |
a9dd0a83 | 2472 | * This is a basic per-node page freer. Used by both kswapd and direct reclaim. |
9b4f98cd | 2473 | */ |
a9dd0a83 | 2474 | static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, |
33377678 | 2475 | struct scan_control *sc, unsigned long *lru_pages) |
9b4f98cd | 2476 | { |
ef8f2327 | 2477 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
9b4f98cd | 2478 | unsigned long nr[NR_LRU_LISTS]; |
e82e0561 | 2479 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2480 | unsigned long nr_to_scan; |
2481 | enum lru_list lru; | |
2482 | unsigned long nr_reclaimed = 0; | |
2483 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2484 | struct blk_plug plug; | |
1a501907 | 2485 | bool scan_adjusted; |
9b4f98cd | 2486 | |
33377678 | 2487 | get_scan_count(lruvec, memcg, sc, nr, lru_pages); |
9b4f98cd | 2488 | |
e82e0561 MG |
2489 | /* Record the original scan target for proportional adjustments later */ |
2490 | memcpy(targets, nr, sizeof(nr)); | |
2491 | ||
1a501907 MG |
2492 | /* |
2493 | * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal | |
2494 | * event that can occur when there is little memory pressure e.g. | |
2495 | * multiple streaming readers/writers. Hence, we do not abort scanning | |
2496 | * when the requested number of pages are reclaimed when scanning at | |
2497 | * DEF_PRIORITY on the assumption that the fact we are direct | |
2498 | * reclaiming implies that kswapd is not keeping up and it is best to | |
2499 | * do a batch of work at once. For memcg reclaim one check is made to | |
2500 | * abort proportional reclaim if either the file or anon lru has already | |
2501 | * dropped to zero at the first pass. | |
2502 | */ | |
2503 | scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && | |
2504 | sc->priority == DEF_PRIORITY); | |
2505 | ||
9b4f98cd JW |
2506 | blk_start_plug(&plug); |
2507 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2508 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2509 | unsigned long nr_anon, nr_file, percentage; |
2510 | unsigned long nr_scanned; | |
2511 | ||
9b4f98cd JW |
2512 | for_each_evictable_lru(lru) { |
2513 | if (nr[lru]) { | |
2514 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2515 | nr[lru] -= nr_to_scan; | |
2516 | ||
2517 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
2a2e4885 | 2518 | lruvec, memcg, sc); |
9b4f98cd JW |
2519 | } |
2520 | } | |
e82e0561 | 2521 | |
bd041733 MH |
2522 | cond_resched(); |
2523 | ||
e82e0561 MG |
2524 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) |
2525 | continue; | |
2526 | ||
e82e0561 MG |
2527 | /* |
2528 | * For kswapd and memcg, reclaim at least the number of pages | |
1a501907 | 2529 | * requested. Ensure that the anon and file LRUs are scanned |
e82e0561 MG |
2530 | * proportionally what was requested by get_scan_count(). We |
2531 | * stop reclaiming one LRU and reduce the amount scanning | |
2532 | * proportional to the original scan target. | |
2533 | */ | |
2534 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2535 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2536 | ||
1a501907 MG |
2537 | /* |
2538 | * It's just vindictive to attack the larger once the smaller | |
2539 | * has gone to zero. And given the way we stop scanning the | |
2540 | * smaller below, this makes sure that we only make one nudge | |
2541 | * towards proportionality once we've got nr_to_reclaim. | |
2542 | */ | |
2543 | if (!nr_file || !nr_anon) | |
2544 | break; | |
2545 | ||
e82e0561 MG |
2546 | if (nr_file > nr_anon) { |
2547 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2548 | targets[LRU_ACTIVE_ANON] + 1; | |
2549 | lru = LRU_BASE; | |
2550 | percentage = nr_anon * 100 / scan_target; | |
2551 | } else { | |
2552 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2553 | targets[LRU_ACTIVE_FILE] + 1; | |
2554 | lru = LRU_FILE; | |
2555 | percentage = nr_file * 100 / scan_target; | |
2556 | } | |
2557 | ||
2558 | /* Stop scanning the smaller of the LRU */ | |
2559 | nr[lru] = 0; | |
2560 | nr[lru + LRU_ACTIVE] = 0; | |
2561 | ||
2562 | /* | |
2563 | * Recalculate the other LRU scan count based on its original | |
2564 | * scan target and the percentage scanning already complete | |
2565 | */ | |
2566 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2567 | nr_scanned = targets[lru] - nr[lru]; | |
2568 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2569 | nr[lru] -= min(nr[lru], nr_scanned); | |
2570 | ||
2571 | lru += LRU_ACTIVE; | |
2572 | nr_scanned = targets[lru] - nr[lru]; | |
2573 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2574 | nr[lru] -= min(nr[lru], nr_scanned); | |
2575 | ||
2576 | scan_adjusted = true; | |
9b4f98cd JW |
2577 | } |
2578 | blk_finish_plug(&plug); | |
2579 | sc->nr_reclaimed += nr_reclaimed; | |
2580 | ||
2581 | /* | |
2582 | * Even if we did not try to evict anon pages at all, we want to | |
2583 | * rebalance the anon lru active/inactive ratio. | |
2584 | */ | |
2a2e4885 | 2585 | if (inactive_list_is_low(lruvec, false, memcg, sc, true)) |
9b4f98cd JW |
2586 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
2587 | sc, LRU_ACTIVE_ANON); | |
9b4f98cd JW |
2588 | } |
2589 | ||
23b9da55 | 2590 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2591 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2592 | { |
d84da3f9 | 2593 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2594 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2595 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2596 | return true; |
2597 | ||
2598 | return false; | |
2599 | } | |
2600 | ||
3e7d3449 | 2601 | /* |
23b9da55 MG |
2602 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2603 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2604 | * true if more pages should be reclaimed such that when the page allocator | |
2605 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2606 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2607 | */ |
a9dd0a83 | 2608 | static inline bool should_continue_reclaim(struct pglist_data *pgdat, |
3e7d3449 MG |
2609 | unsigned long nr_reclaimed, |
2610 | unsigned long nr_scanned, | |
2611 | struct scan_control *sc) | |
2612 | { | |
2613 | unsigned long pages_for_compaction; | |
2614 | unsigned long inactive_lru_pages; | |
a9dd0a83 | 2615 | int z; |
3e7d3449 MG |
2616 | |
2617 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2618 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2619 | return false; |
2620 | ||
2876592f | 2621 | /* Consider stopping depending on scan and reclaim activity */ |
dcda9b04 | 2622 | if (sc->gfp_mask & __GFP_RETRY_MAYFAIL) { |
2876592f | 2623 | /* |
dcda9b04 | 2624 | * For __GFP_RETRY_MAYFAIL allocations, stop reclaiming if the |
2876592f MG |
2625 | * full LRU list has been scanned and we are still failing |
2626 | * to reclaim pages. This full LRU scan is potentially | |
dcda9b04 | 2627 | * expensive but a __GFP_RETRY_MAYFAIL caller really wants to succeed |
2876592f MG |
2628 | */ |
2629 | if (!nr_reclaimed && !nr_scanned) | |
2630 | return false; | |
2631 | } else { | |
2632 | /* | |
dcda9b04 | 2633 | * For non-__GFP_RETRY_MAYFAIL allocations which can presumably |
2876592f MG |
2634 | * fail without consequence, stop if we failed to reclaim |
2635 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2636 | * pages that were scanned. This will return to the | |
2637 | * caller faster at the risk reclaim/compaction and | |
2638 | * the resulting allocation attempt fails | |
2639 | */ | |
2640 | if (!nr_reclaimed) | |
2641 | return false; | |
2642 | } | |
3e7d3449 MG |
2643 | |
2644 | /* | |
2645 | * If we have not reclaimed enough pages for compaction and the | |
2646 | * inactive lists are large enough, continue reclaiming | |
2647 | */ | |
9861a62c | 2648 | pages_for_compaction = compact_gap(sc->order); |
a9dd0a83 | 2649 | inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); |
ec8acf20 | 2650 | if (get_nr_swap_pages() > 0) |
a9dd0a83 | 2651 | inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); |
3e7d3449 MG |
2652 | if (sc->nr_reclaimed < pages_for_compaction && |
2653 | inactive_lru_pages > pages_for_compaction) | |
2654 | return true; | |
2655 | ||
2656 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
a9dd0a83 MG |
2657 | for (z = 0; z <= sc->reclaim_idx; z++) { |
2658 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2659 | if (!managed_zone(zone)) |
a9dd0a83 MG |
2660 | continue; |
2661 | ||
2662 | switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) { | |
cf378319 | 2663 | case COMPACT_SUCCESS: |
a9dd0a83 MG |
2664 | case COMPACT_CONTINUE: |
2665 | return false; | |
2666 | default: | |
2667 | /* check next zone */ | |
2668 | ; | |
2669 | } | |
3e7d3449 | 2670 | } |
a9dd0a83 | 2671 | return true; |
3e7d3449 MG |
2672 | } |
2673 | ||
e3c1ac58 AR |
2674 | static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) |
2675 | { | |
2676 | return test_bit(PGDAT_CONGESTED, &pgdat->flags) || | |
2677 | (memcg && memcg_congested(pgdat, memcg)); | |
2678 | } | |
2679 | ||
970a39a3 | 2680 | static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) |
1da177e4 | 2681 | { |
cb731d6c | 2682 | struct reclaim_state *reclaim_state = current->reclaim_state; |
f0fdc5e8 | 2683 | unsigned long nr_reclaimed, nr_scanned; |
2344d7e4 | 2684 | bool reclaimable = false; |
1da177e4 | 2685 | |
9b4f98cd JW |
2686 | do { |
2687 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2688 | struct mem_cgroup_reclaim_cookie reclaim = { | |
ef8f2327 | 2689 | .pgdat = pgdat, |
9b4f98cd JW |
2690 | .priority = sc->priority, |
2691 | }; | |
a9dd0a83 | 2692 | unsigned long node_lru_pages = 0; |
694fbc0f | 2693 | struct mem_cgroup *memcg; |
3e7d3449 | 2694 | |
d108c772 AR |
2695 | memset(&sc->nr, 0, sizeof(sc->nr)); |
2696 | ||
9b4f98cd JW |
2697 | nr_reclaimed = sc->nr_reclaimed; |
2698 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2699 | |
694fbc0f AM |
2700 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2701 | do { | |
6b4f7799 | 2702 | unsigned long lru_pages; |
8e8ae645 | 2703 | unsigned long reclaimed; |
cb731d6c | 2704 | unsigned long scanned; |
5660048c | 2705 | |
bf8d5d52 RG |
2706 | switch (mem_cgroup_protected(root, memcg)) { |
2707 | case MEMCG_PROT_MIN: | |
2708 | /* | |
2709 | * Hard protection. | |
2710 | * If there is no reclaimable memory, OOM. | |
2711 | */ | |
2712 | continue; | |
2713 | case MEMCG_PROT_LOW: | |
2714 | /* | |
2715 | * Soft protection. | |
2716 | * Respect the protection only as long as | |
2717 | * there is an unprotected supply | |
2718 | * of reclaimable memory from other cgroups. | |
2719 | */ | |
d6622f63 YX |
2720 | if (!sc->memcg_low_reclaim) { |
2721 | sc->memcg_low_skipped = 1; | |
241994ed | 2722 | continue; |
d6622f63 | 2723 | } |
e27be240 | 2724 | memcg_memory_event(memcg, MEMCG_LOW); |
bf8d5d52 RG |
2725 | break; |
2726 | case MEMCG_PROT_NONE: | |
2727 | break; | |
241994ed JW |
2728 | } |
2729 | ||
8e8ae645 | 2730 | reclaimed = sc->nr_reclaimed; |
cb731d6c | 2731 | scanned = sc->nr_scanned; |
a9dd0a83 MG |
2732 | shrink_node_memcg(pgdat, memcg, sc, &lru_pages); |
2733 | node_lru_pages += lru_pages; | |
f16015fb | 2734 | |
aeed1d32 VD |
2735 | shrink_slab(sc->gfp_mask, pgdat->node_id, |
2736 | memcg, sc->priority); | |
cb731d6c | 2737 | |
8e8ae645 JW |
2738 | /* Record the group's reclaim efficiency */ |
2739 | vmpressure(sc->gfp_mask, memcg, false, | |
2740 | sc->nr_scanned - scanned, | |
2741 | sc->nr_reclaimed - reclaimed); | |
2742 | ||
9b4f98cd | 2743 | /* |
a394cb8e MH |
2744 | * Direct reclaim and kswapd have to scan all memory |
2745 | * cgroups to fulfill the overall scan target for the | |
a9dd0a83 | 2746 | * node. |
a394cb8e MH |
2747 | * |
2748 | * Limit reclaim, on the other hand, only cares about | |
2749 | * nr_to_reclaim pages to be reclaimed and it will | |
2750 | * retry with decreasing priority if one round over the | |
2751 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2752 | */ |
a394cb8e MH |
2753 | if (!global_reclaim(sc) && |
2754 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2755 | mem_cgroup_iter_break(root, memcg); |
2756 | break; | |
2757 | } | |
241994ed | 2758 | } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); |
70ddf637 | 2759 | |
cb731d6c VD |
2760 | if (reclaim_state) { |
2761 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; | |
2762 | reclaim_state->reclaimed_slab = 0; | |
6b4f7799 JW |
2763 | } |
2764 | ||
8e8ae645 JW |
2765 | /* Record the subtree's reclaim efficiency */ |
2766 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, | |
70ddf637 AV |
2767 | sc->nr_scanned - nr_scanned, |
2768 | sc->nr_reclaimed - nr_reclaimed); | |
2769 | ||
2344d7e4 JW |
2770 | if (sc->nr_reclaimed - nr_reclaimed) |
2771 | reclaimable = true; | |
2772 | ||
e3c1ac58 AR |
2773 | if (current_is_kswapd()) { |
2774 | /* | |
2775 | * If reclaim is isolating dirty pages under writeback, | |
2776 | * it implies that the long-lived page allocation rate | |
2777 | * is exceeding the page laundering rate. Either the | |
2778 | * global limits are not being effective at throttling | |
2779 | * processes due to the page distribution throughout | |
2780 | * zones or there is heavy usage of a slow backing | |
2781 | * device. The only option is to throttle from reclaim | |
2782 | * context which is not ideal as there is no guarantee | |
2783 | * the dirtying process is throttled in the same way | |
2784 | * balance_dirty_pages() manages. | |
2785 | * | |
2786 | * Once a node is flagged PGDAT_WRITEBACK, kswapd will | |
2787 | * count the number of pages under pages flagged for | |
2788 | * immediate reclaim and stall if any are encountered | |
2789 | * in the nr_immediate check below. | |
2790 | */ | |
2791 | if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) | |
2792 | set_bit(PGDAT_WRITEBACK, &pgdat->flags); | |
d108c772 | 2793 | |
d108c772 AR |
2794 | /* |
2795 | * Tag a node as congested if all the dirty pages | |
2796 | * scanned were backed by a congested BDI and | |
2797 | * wait_iff_congested will stall. | |
2798 | */ | |
2799 | if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) | |
2800 | set_bit(PGDAT_CONGESTED, &pgdat->flags); | |
2801 | ||
2802 | /* Allow kswapd to start writing pages during reclaim.*/ | |
2803 | if (sc->nr.unqueued_dirty == sc->nr.file_taken) | |
2804 | set_bit(PGDAT_DIRTY, &pgdat->flags); | |
2805 | ||
2806 | /* | |
2807 | * If kswapd scans pages marked marked for immediate | |
2808 | * reclaim and under writeback (nr_immediate), it | |
2809 | * implies that pages are cycling through the LRU | |
2810 | * faster than they are written so also forcibly stall. | |
2811 | */ | |
2812 | if (sc->nr.immediate) | |
2813 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2814 | } | |
2815 | ||
e3c1ac58 AR |
2816 | /* |
2817 | * Legacy memcg will stall in page writeback so avoid forcibly | |
2818 | * stalling in wait_iff_congested(). | |
2819 | */ | |
2820 | if (!global_reclaim(sc) && sane_reclaim(sc) && | |
2821 | sc->nr.dirty && sc->nr.dirty == sc->nr.congested) | |
2822 | set_memcg_congestion(pgdat, root, true); | |
2823 | ||
d108c772 AR |
2824 | /* |
2825 | * Stall direct reclaim for IO completions if underlying BDIs | |
2826 | * and node is congested. Allow kswapd to continue until it | |
2827 | * starts encountering unqueued dirty pages or cycling through | |
2828 | * the LRU too quickly. | |
2829 | */ | |
2830 | if (!sc->hibernation_mode && !current_is_kswapd() && | |
e3c1ac58 AR |
2831 | current_may_throttle() && pgdat_memcg_congested(pgdat, root)) |
2832 | wait_iff_congested(BLK_RW_ASYNC, HZ/10); | |
d108c772 | 2833 | |
a9dd0a83 | 2834 | } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, |
9b4f98cd | 2835 | sc->nr_scanned - nr_scanned, sc)); |
2344d7e4 | 2836 | |
c73322d0 JW |
2837 | /* |
2838 | * Kswapd gives up on balancing particular nodes after too | |
2839 | * many failures to reclaim anything from them and goes to | |
2840 | * sleep. On reclaim progress, reset the failure counter. A | |
2841 | * successful direct reclaim run will revive a dormant kswapd. | |
2842 | */ | |
2843 | if (reclaimable) | |
2844 | pgdat->kswapd_failures = 0; | |
2845 | ||
2344d7e4 | 2846 | return reclaimable; |
f16015fb JW |
2847 | } |
2848 | ||
53853e2d | 2849 | /* |
fdd4c614 VB |
2850 | * Returns true if compaction should go ahead for a costly-order request, or |
2851 | * the allocation would already succeed without compaction. Return false if we | |
2852 | * should reclaim first. | |
53853e2d | 2853 | */ |
4f588331 | 2854 | static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) |
fe4b1b24 | 2855 | { |
31483b6a | 2856 | unsigned long watermark; |
fdd4c614 | 2857 | enum compact_result suitable; |
fe4b1b24 | 2858 | |
fdd4c614 VB |
2859 | suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); |
2860 | if (suitable == COMPACT_SUCCESS) | |
2861 | /* Allocation should succeed already. Don't reclaim. */ | |
2862 | return true; | |
2863 | if (suitable == COMPACT_SKIPPED) | |
2864 | /* Compaction cannot yet proceed. Do reclaim. */ | |
2865 | return false; | |
fe4b1b24 | 2866 | |
53853e2d | 2867 | /* |
fdd4c614 VB |
2868 | * Compaction is already possible, but it takes time to run and there |
2869 | * are potentially other callers using the pages just freed. So proceed | |
2870 | * with reclaim to make a buffer of free pages available to give | |
2871 | * compaction a reasonable chance of completing and allocating the page. | |
2872 | * Note that we won't actually reclaim the whole buffer in one attempt | |
2873 | * as the target watermark in should_continue_reclaim() is lower. But if | |
2874 | * we are already above the high+gap watermark, don't reclaim at all. | |
53853e2d | 2875 | */ |
fdd4c614 | 2876 | watermark = high_wmark_pages(zone) + compact_gap(sc->order); |
fe4b1b24 | 2877 | |
fdd4c614 | 2878 | return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); |
fe4b1b24 MG |
2879 | } |
2880 | ||
1da177e4 LT |
2881 | /* |
2882 | * This is the direct reclaim path, for page-allocating processes. We only | |
2883 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2884 | * request. | |
2885 | * | |
1da177e4 LT |
2886 | * If a zone is deemed to be full of pinned pages then just give it a light |
2887 | * scan then give up on it. | |
2888 | */ | |
0a0337e0 | 2889 | static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2890 | { |
dd1a239f | 2891 | struct zoneref *z; |
54a6eb5c | 2892 | struct zone *zone; |
0608f43d AM |
2893 | unsigned long nr_soft_reclaimed; |
2894 | unsigned long nr_soft_scanned; | |
619d0d76 | 2895 | gfp_t orig_mask; |
79dafcdc | 2896 | pg_data_t *last_pgdat = NULL; |
1cfb419b | 2897 | |
cc715d99 MG |
2898 | /* |
2899 | * If the number of buffer_heads in the machine exceeds the maximum | |
2900 | * allowed level, force direct reclaim to scan the highmem zone as | |
2901 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2902 | */ | |
619d0d76 | 2903 | orig_mask = sc->gfp_mask; |
b2e18757 | 2904 | if (buffer_heads_over_limit) { |
cc715d99 | 2905 | sc->gfp_mask |= __GFP_HIGHMEM; |
4f588331 | 2906 | sc->reclaim_idx = gfp_zone(sc->gfp_mask); |
b2e18757 | 2907 | } |
cc715d99 | 2908 | |
d4debc66 | 2909 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
b2e18757 | 2910 | sc->reclaim_idx, sc->nodemask) { |
1cfb419b KH |
2911 | /* |
2912 | * Take care memory controller reclaiming has small influence | |
2913 | * to global LRU. | |
2914 | */ | |
89b5fae5 | 2915 | if (global_reclaim(sc)) { |
344736f2 VD |
2916 | if (!cpuset_zone_allowed(zone, |
2917 | GFP_KERNEL | __GFP_HARDWALL)) | |
1cfb419b | 2918 | continue; |
65ec02cb | 2919 | |
0b06496a JW |
2920 | /* |
2921 | * If we already have plenty of memory free for | |
2922 | * compaction in this zone, don't free any more. | |
2923 | * Even though compaction is invoked for any | |
2924 | * non-zero order, only frequent costly order | |
2925 | * reclamation is disruptive enough to become a | |
2926 | * noticeable problem, like transparent huge | |
2927 | * page allocations. | |
2928 | */ | |
2929 | if (IS_ENABLED(CONFIG_COMPACTION) && | |
2930 | sc->order > PAGE_ALLOC_COSTLY_ORDER && | |
4f588331 | 2931 | compaction_ready(zone, sc)) { |
0b06496a JW |
2932 | sc->compaction_ready = true; |
2933 | continue; | |
e0887c19 | 2934 | } |
0b06496a | 2935 | |
79dafcdc MG |
2936 | /* |
2937 | * Shrink each node in the zonelist once. If the | |
2938 | * zonelist is ordered by zone (not the default) then a | |
2939 | * node may be shrunk multiple times but in that case | |
2940 | * the user prefers lower zones being preserved. | |
2941 | */ | |
2942 | if (zone->zone_pgdat == last_pgdat) | |
2943 | continue; | |
2944 | ||
0608f43d AM |
2945 | /* |
2946 | * This steals pages from memory cgroups over softlimit | |
2947 | * and returns the number of reclaimed pages and | |
2948 | * scanned pages. This works for global memory pressure | |
2949 | * and balancing, not for a memcg's limit. | |
2950 | */ | |
2951 | nr_soft_scanned = 0; | |
ef8f2327 | 2952 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat, |
0608f43d AM |
2953 | sc->order, sc->gfp_mask, |
2954 | &nr_soft_scanned); | |
2955 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2956 | sc->nr_scanned += nr_soft_scanned; | |
ac34a1a3 | 2957 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2958 | } |
408d8544 | 2959 | |
79dafcdc MG |
2960 | /* See comment about same check for global reclaim above */ |
2961 | if (zone->zone_pgdat == last_pgdat) | |
2962 | continue; | |
2963 | last_pgdat = zone->zone_pgdat; | |
970a39a3 | 2964 | shrink_node(zone->zone_pgdat, sc); |
1da177e4 | 2965 | } |
e0c23279 | 2966 | |
619d0d76 WY |
2967 | /* |
2968 | * Restore to original mask to avoid the impact on the caller if we | |
2969 | * promoted it to __GFP_HIGHMEM. | |
2970 | */ | |
2971 | sc->gfp_mask = orig_mask; | |
1da177e4 | 2972 | } |
4f98a2fe | 2973 | |
2a2e4885 JW |
2974 | static void snapshot_refaults(struct mem_cgroup *root_memcg, pg_data_t *pgdat) |
2975 | { | |
2976 | struct mem_cgroup *memcg; | |
2977 | ||
2978 | memcg = mem_cgroup_iter(root_memcg, NULL, NULL); | |
2979 | do { | |
2980 | unsigned long refaults; | |
2981 | struct lruvec *lruvec; | |
2982 | ||
2983 | if (memcg) | |
ccda7f43 | 2984 | refaults = memcg_page_state(memcg, WORKINGSET_ACTIVATE); |
2a2e4885 JW |
2985 | else |
2986 | refaults = node_page_state(pgdat, WORKINGSET_ACTIVATE); | |
2987 | ||
2988 | lruvec = mem_cgroup_lruvec(pgdat, memcg); | |
2989 | lruvec->refaults = refaults; | |
2990 | } while ((memcg = mem_cgroup_iter(root_memcg, memcg, NULL))); | |
2991 | } | |
2992 | ||
1da177e4 LT |
2993 | /* |
2994 | * This is the main entry point to direct page reclaim. | |
2995 | * | |
2996 | * If a full scan of the inactive list fails to free enough memory then we | |
2997 | * are "out of memory" and something needs to be killed. | |
2998 | * | |
2999 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
3000 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
3001 | * caller can't do much about. We kick the writeback threads and take explicit |
3002 | * naps in the hope that some of these pages can be written. But if the | |
3003 | * allocating task holds filesystem locks which prevent writeout this might not | |
3004 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
3005 | * |
3006 | * returns: 0, if no pages reclaimed | |
3007 | * else, the number of pages reclaimed | |
1da177e4 | 3008 | */ |
dac1d27b | 3009 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
3115cd91 | 3010 | struct scan_control *sc) |
1da177e4 | 3011 | { |
241994ed | 3012 | int initial_priority = sc->priority; |
2a2e4885 JW |
3013 | pg_data_t *last_pgdat; |
3014 | struct zoneref *z; | |
3015 | struct zone *zone; | |
241994ed | 3016 | retry: |
873b4771 KK |
3017 | delayacct_freepages_start(); |
3018 | ||
89b5fae5 | 3019 | if (global_reclaim(sc)) |
7cc30fcf | 3020 | __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); |
1da177e4 | 3021 | |
9e3b2f8c | 3022 | do { |
70ddf637 AV |
3023 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
3024 | sc->priority); | |
66e1707b | 3025 | sc->nr_scanned = 0; |
0a0337e0 | 3026 | shrink_zones(zonelist, sc); |
c6a8a8c5 | 3027 | |
bb21c7ce | 3028 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
0b06496a JW |
3029 | break; |
3030 | ||
3031 | if (sc->compaction_ready) | |
3032 | break; | |
1da177e4 | 3033 | |
0e50ce3b MK |
3034 | /* |
3035 | * If we're getting trouble reclaiming, start doing | |
3036 | * writepage even in laptop mode. | |
3037 | */ | |
3038 | if (sc->priority < DEF_PRIORITY - 2) | |
3039 | sc->may_writepage = 1; | |
0b06496a | 3040 | } while (--sc->priority >= 0); |
bb21c7ce | 3041 | |
2a2e4885 JW |
3042 | last_pgdat = NULL; |
3043 | for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx, | |
3044 | sc->nodemask) { | |
3045 | if (zone->zone_pgdat == last_pgdat) | |
3046 | continue; | |
3047 | last_pgdat = zone->zone_pgdat; | |
3048 | snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat); | |
e3c1ac58 | 3049 | set_memcg_congestion(last_pgdat, sc->target_mem_cgroup, false); |
2a2e4885 JW |
3050 | } |
3051 | ||
873b4771 KK |
3052 | delayacct_freepages_end(); |
3053 | ||
bb21c7ce KM |
3054 | if (sc->nr_reclaimed) |
3055 | return sc->nr_reclaimed; | |
3056 | ||
0cee34fd | 3057 | /* Aborted reclaim to try compaction? don't OOM, then */ |
0b06496a | 3058 | if (sc->compaction_ready) |
7335084d MG |
3059 | return 1; |
3060 | ||
241994ed | 3061 | /* Untapped cgroup reserves? Don't OOM, retry. */ |
d6622f63 | 3062 | if (sc->memcg_low_skipped) { |
241994ed | 3063 | sc->priority = initial_priority; |
d6622f63 YX |
3064 | sc->memcg_low_reclaim = 1; |
3065 | sc->memcg_low_skipped = 0; | |
241994ed JW |
3066 | goto retry; |
3067 | } | |
3068 | ||
bb21c7ce | 3069 | return 0; |
1da177e4 LT |
3070 | } |
3071 | ||
c73322d0 | 3072 | static bool allow_direct_reclaim(pg_data_t *pgdat) |
5515061d MG |
3073 | { |
3074 | struct zone *zone; | |
3075 | unsigned long pfmemalloc_reserve = 0; | |
3076 | unsigned long free_pages = 0; | |
3077 | int i; | |
3078 | bool wmark_ok; | |
3079 | ||
c73322d0 JW |
3080 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) |
3081 | return true; | |
3082 | ||
5515061d MG |
3083 | for (i = 0; i <= ZONE_NORMAL; i++) { |
3084 | zone = &pgdat->node_zones[i]; | |
d450abd8 JW |
3085 | if (!managed_zone(zone)) |
3086 | continue; | |
3087 | ||
3088 | if (!zone_reclaimable_pages(zone)) | |
675becce MG |
3089 | continue; |
3090 | ||
5515061d MG |
3091 | pfmemalloc_reserve += min_wmark_pages(zone); |
3092 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
3093 | } | |
3094 | ||
675becce MG |
3095 | /* If there are no reserves (unexpected config) then do not throttle */ |
3096 | if (!pfmemalloc_reserve) | |
3097 | return true; | |
3098 | ||
5515061d MG |
3099 | wmark_ok = free_pages > pfmemalloc_reserve / 2; |
3100 | ||
3101 | /* kswapd must be awake if processes are being throttled */ | |
3102 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
38087d9b | 3103 | pgdat->kswapd_classzone_idx = min(pgdat->kswapd_classzone_idx, |
5515061d MG |
3104 | (enum zone_type)ZONE_NORMAL); |
3105 | wake_up_interruptible(&pgdat->kswapd_wait); | |
3106 | } | |
3107 | ||
3108 | return wmark_ok; | |
3109 | } | |
3110 | ||
3111 | /* | |
3112 | * Throttle direct reclaimers if backing storage is backed by the network | |
3113 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
3114 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
3115 | * when the low watermark is reached. |
3116 | * | |
3117 | * Returns true if a fatal signal was delivered during throttling. If this | |
3118 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 3119 | */ |
50694c28 | 3120 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
3121 | nodemask_t *nodemask) |
3122 | { | |
675becce | 3123 | struct zoneref *z; |
5515061d | 3124 | struct zone *zone; |
675becce | 3125 | pg_data_t *pgdat = NULL; |
5515061d MG |
3126 | |
3127 | /* | |
3128 | * Kernel threads should not be throttled as they may be indirectly | |
3129 | * responsible for cleaning pages necessary for reclaim to make forward | |
3130 | * progress. kjournald for example may enter direct reclaim while | |
3131 | * committing a transaction where throttling it could forcing other | |
3132 | * processes to block on log_wait_commit(). | |
3133 | */ | |
3134 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
3135 | goto out; |
3136 | ||
3137 | /* | |
3138 | * If a fatal signal is pending, this process should not throttle. | |
3139 | * It should return quickly so it can exit and free its memory | |
3140 | */ | |
3141 | if (fatal_signal_pending(current)) | |
3142 | goto out; | |
5515061d | 3143 | |
675becce MG |
3144 | /* |
3145 | * Check if the pfmemalloc reserves are ok by finding the first node | |
3146 | * with a usable ZONE_NORMAL or lower zone. The expectation is that | |
3147 | * GFP_KERNEL will be required for allocating network buffers when | |
3148 | * swapping over the network so ZONE_HIGHMEM is unusable. | |
3149 | * | |
3150 | * Throttling is based on the first usable node and throttled processes | |
3151 | * wait on a queue until kswapd makes progress and wakes them. There | |
3152 | * is an affinity then between processes waking up and where reclaim | |
3153 | * progress has been made assuming the process wakes on the same node. | |
3154 | * More importantly, processes running on remote nodes will not compete | |
3155 | * for remote pfmemalloc reserves and processes on different nodes | |
3156 | * should make reasonable progress. | |
3157 | */ | |
3158 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
17636faa | 3159 | gfp_zone(gfp_mask), nodemask) { |
675becce MG |
3160 | if (zone_idx(zone) > ZONE_NORMAL) |
3161 | continue; | |
3162 | ||
3163 | /* Throttle based on the first usable node */ | |
3164 | pgdat = zone->zone_pgdat; | |
c73322d0 | 3165 | if (allow_direct_reclaim(pgdat)) |
675becce MG |
3166 | goto out; |
3167 | break; | |
3168 | } | |
3169 | ||
3170 | /* If no zone was usable by the allocation flags then do not throttle */ | |
3171 | if (!pgdat) | |
50694c28 | 3172 | goto out; |
5515061d | 3173 | |
68243e76 MG |
3174 | /* Account for the throttling */ |
3175 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
3176 | ||
5515061d MG |
3177 | /* |
3178 | * If the caller cannot enter the filesystem, it's possible that it | |
3179 | * is due to the caller holding an FS lock or performing a journal | |
3180 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
3181 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
3182 | * blocked waiting on the same lock. Instead, throttle for up to a | |
3183 | * second before continuing. | |
3184 | */ | |
3185 | if (!(gfp_mask & __GFP_FS)) { | |
3186 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
c73322d0 | 3187 | allow_direct_reclaim(pgdat), HZ); |
50694c28 MG |
3188 | |
3189 | goto check_pending; | |
5515061d MG |
3190 | } |
3191 | ||
3192 | /* Throttle until kswapd wakes the process */ | |
3193 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
c73322d0 | 3194 | allow_direct_reclaim(pgdat)); |
50694c28 MG |
3195 | |
3196 | check_pending: | |
3197 | if (fatal_signal_pending(current)) | |
3198 | return true; | |
3199 | ||
3200 | out: | |
3201 | return false; | |
5515061d MG |
3202 | } |
3203 | ||
dac1d27b | 3204 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 3205 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 3206 | { |
33906bc5 | 3207 | unsigned long nr_reclaimed; |
66e1707b | 3208 | struct scan_control sc = { |
ee814fe2 | 3209 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
f2f43e56 | 3210 | .gfp_mask = current_gfp_context(gfp_mask), |
b2e18757 | 3211 | .reclaim_idx = gfp_zone(gfp_mask), |
ee814fe2 JW |
3212 | .order = order, |
3213 | .nodemask = nodemask, | |
3214 | .priority = DEF_PRIORITY, | |
66e1707b | 3215 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3216 | .may_unmap = 1, |
2e2e4259 | 3217 | .may_swap = 1, |
66e1707b BS |
3218 | }; |
3219 | ||
bb451fdf GT |
3220 | /* |
3221 | * scan_control uses s8 fields for order, priority, and reclaim_idx. | |
3222 | * Confirm they are large enough for max values. | |
3223 | */ | |
3224 | BUILD_BUG_ON(MAX_ORDER > S8_MAX); | |
3225 | BUILD_BUG_ON(DEF_PRIORITY > S8_MAX); | |
3226 | BUILD_BUG_ON(MAX_NR_ZONES > S8_MAX); | |
3227 | ||
5515061d | 3228 | /* |
50694c28 MG |
3229 | * Do not enter reclaim if fatal signal was delivered while throttled. |
3230 | * 1 is returned so that the page allocator does not OOM kill at this | |
3231 | * point. | |
5515061d | 3232 | */ |
f2f43e56 | 3233 | if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask)) |
5515061d MG |
3234 | return 1; |
3235 | ||
33906bc5 MG |
3236 | trace_mm_vmscan_direct_reclaim_begin(order, |
3237 | sc.may_writepage, | |
f2f43e56 | 3238 | sc.gfp_mask, |
e5146b12 | 3239 | sc.reclaim_idx); |
33906bc5 | 3240 | |
3115cd91 | 3241 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
33906bc5 MG |
3242 | |
3243 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
3244 | ||
3245 | return nr_reclaimed; | |
66e1707b BS |
3246 | } |
3247 | ||
c255a458 | 3248 | #ifdef CONFIG_MEMCG |
66e1707b | 3249 | |
a9dd0a83 | 3250 | unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, |
4e416953 | 3251 | gfp_t gfp_mask, bool noswap, |
ef8f2327 | 3252 | pg_data_t *pgdat, |
0ae5e89c | 3253 | unsigned long *nr_scanned) |
4e416953 BS |
3254 | { |
3255 | struct scan_control sc = { | |
b8f5c566 | 3256 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
ee814fe2 | 3257 | .target_mem_cgroup = memcg, |
4e416953 BS |
3258 | .may_writepage = !laptop_mode, |
3259 | .may_unmap = 1, | |
b2e18757 | 3260 | .reclaim_idx = MAX_NR_ZONES - 1, |
4e416953 | 3261 | .may_swap = !noswap, |
4e416953 | 3262 | }; |
6b4f7799 | 3263 | unsigned long lru_pages; |
0ae5e89c | 3264 | |
4e416953 BS |
3265 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
3266 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 3267 | |
9e3b2f8c | 3268 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e | 3269 | sc.may_writepage, |
e5146b12 MG |
3270 | sc.gfp_mask, |
3271 | sc.reclaim_idx); | |
bdce6d9e | 3272 | |
4e416953 BS |
3273 | /* |
3274 | * NOTE: Although we can get the priority field, using it | |
3275 | * here is not a good idea, since it limits the pages we can scan. | |
a9dd0a83 | 3276 | * if we don't reclaim here, the shrink_node from balance_pgdat |
4e416953 BS |
3277 | * will pick up pages from other mem cgroup's as well. We hack |
3278 | * the priority and make it zero. | |
3279 | */ | |
ef8f2327 | 3280 | shrink_node_memcg(pgdat, memcg, &sc, &lru_pages); |
bdce6d9e KM |
3281 | |
3282 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
3283 | ||
0ae5e89c | 3284 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
3285 | return sc.nr_reclaimed; |
3286 | } | |
3287 | ||
72835c86 | 3288 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
b70a2a21 | 3289 | unsigned long nr_pages, |
a7885eb8 | 3290 | gfp_t gfp_mask, |
b70a2a21 | 3291 | bool may_swap) |
66e1707b | 3292 | { |
4e416953 | 3293 | struct zonelist *zonelist; |
bdce6d9e | 3294 | unsigned long nr_reclaimed; |
889976db | 3295 | int nid; |
499118e9 | 3296 | unsigned int noreclaim_flag; |
66e1707b | 3297 | struct scan_control sc = { |
b70a2a21 | 3298 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
7dea19f9 | 3299 | .gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) | |
a09ed5e0 | 3300 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), |
b2e18757 | 3301 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 JW |
3302 | .target_mem_cgroup = memcg, |
3303 | .priority = DEF_PRIORITY, | |
3304 | .may_writepage = !laptop_mode, | |
3305 | .may_unmap = 1, | |
b70a2a21 | 3306 | .may_swap = may_swap, |
a09ed5e0 | 3307 | }; |
66e1707b | 3308 | |
889976db YH |
3309 | /* |
3310 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
3311 | * take care of from where we get pages. So the node where we start the | |
3312 | * scan does not need to be the current node. | |
3313 | */ | |
72835c86 | 3314 | nid = mem_cgroup_select_victim_node(memcg); |
889976db | 3315 | |
c9634cf0 | 3316 | zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK]; |
bdce6d9e KM |
3317 | |
3318 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
3319 | sc.may_writepage, | |
e5146b12 MG |
3320 | sc.gfp_mask, |
3321 | sc.reclaim_idx); | |
bdce6d9e | 3322 | |
499118e9 | 3323 | noreclaim_flag = memalloc_noreclaim_save(); |
3115cd91 | 3324 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
499118e9 | 3325 | memalloc_noreclaim_restore(noreclaim_flag); |
bdce6d9e KM |
3326 | |
3327 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
3328 | ||
3329 | return nr_reclaimed; | |
66e1707b BS |
3330 | } |
3331 | #endif | |
3332 | ||
1d82de61 | 3333 | static void age_active_anon(struct pglist_data *pgdat, |
ef8f2327 | 3334 | struct scan_control *sc) |
f16015fb | 3335 | { |
b95a2f2d | 3336 | struct mem_cgroup *memcg; |
f16015fb | 3337 | |
b95a2f2d JW |
3338 | if (!total_swap_pages) |
3339 | return; | |
3340 | ||
3341 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
3342 | do { | |
ef8f2327 | 3343 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
b95a2f2d | 3344 | |
2a2e4885 | 3345 | if (inactive_list_is_low(lruvec, false, memcg, sc, true)) |
1a93be0e | 3346 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 3347 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
3348 | |
3349 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
3350 | } while (memcg); | |
f16015fb JW |
3351 | } |
3352 | ||
e716f2eb MG |
3353 | /* |
3354 | * Returns true if there is an eligible zone balanced for the request order | |
3355 | * and classzone_idx | |
3356 | */ | |
3357 | static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) | |
60cefed4 | 3358 | { |
e716f2eb MG |
3359 | int i; |
3360 | unsigned long mark = -1; | |
3361 | struct zone *zone; | |
60cefed4 | 3362 | |
e716f2eb MG |
3363 | for (i = 0; i <= classzone_idx; i++) { |
3364 | zone = pgdat->node_zones + i; | |
6256c6b4 | 3365 | |
e716f2eb MG |
3366 | if (!managed_zone(zone)) |
3367 | continue; | |
3368 | ||
3369 | mark = high_wmark_pages(zone); | |
3370 | if (zone_watermark_ok_safe(zone, order, mark, classzone_idx)) | |
3371 | return true; | |
3372 | } | |
3373 | ||
3374 | /* | |
3375 | * If a node has no populated zone within classzone_idx, it does not | |
3376 | * need balancing by definition. This can happen if a zone-restricted | |
3377 | * allocation tries to wake a remote kswapd. | |
3378 | */ | |
3379 | if (mark == -1) | |
3380 | return true; | |
3381 | ||
3382 | return false; | |
60cefed4 JW |
3383 | } |
3384 | ||
631b6e08 MG |
3385 | /* Clear pgdat state for congested, dirty or under writeback. */ |
3386 | static void clear_pgdat_congested(pg_data_t *pgdat) | |
3387 | { | |
3388 | clear_bit(PGDAT_CONGESTED, &pgdat->flags); | |
3389 | clear_bit(PGDAT_DIRTY, &pgdat->flags); | |
3390 | clear_bit(PGDAT_WRITEBACK, &pgdat->flags); | |
3391 | } | |
3392 | ||
5515061d MG |
3393 | /* |
3394 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
3395 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
3396 | * | |
3397 | * Returns true if kswapd is ready to sleep | |
3398 | */ | |
d9f21d42 | 3399 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f50de2d3 | 3400 | { |
5515061d | 3401 | /* |
9e5e3661 | 3402 | * The throttled processes are normally woken up in balance_pgdat() as |
c73322d0 | 3403 | * soon as allow_direct_reclaim() is true. But there is a potential |
9e5e3661 VB |
3404 | * race between when kswapd checks the watermarks and a process gets |
3405 | * throttled. There is also a potential race if processes get | |
3406 | * throttled, kswapd wakes, a large process exits thereby balancing the | |
3407 | * zones, which causes kswapd to exit balance_pgdat() before reaching | |
3408 | * the wake up checks. If kswapd is going to sleep, no process should | |
3409 | * be sleeping on pfmemalloc_wait, so wake them now if necessary. If | |
3410 | * the wake up is premature, processes will wake kswapd and get | |
3411 | * throttled again. The difference from wake ups in balance_pgdat() is | |
3412 | * that here we are under prepare_to_wait(). | |
5515061d | 3413 | */ |
9e5e3661 VB |
3414 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) |
3415 | wake_up_all(&pgdat->pfmemalloc_wait); | |
f50de2d3 | 3416 | |
c73322d0 JW |
3417 | /* Hopeless node, leave it to direct reclaim */ |
3418 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) | |
3419 | return true; | |
3420 | ||
e716f2eb MG |
3421 | if (pgdat_balanced(pgdat, order, classzone_idx)) { |
3422 | clear_pgdat_congested(pgdat); | |
3423 | return true; | |
1d82de61 MG |
3424 | } |
3425 | ||
333b0a45 | 3426 | return false; |
f50de2d3 MG |
3427 | } |
3428 | ||
75485363 | 3429 | /* |
1d82de61 MG |
3430 | * kswapd shrinks a node of pages that are at or below the highest usable |
3431 | * zone that is currently unbalanced. | |
b8e83b94 MG |
3432 | * |
3433 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
3434 | * reclaim or if the lack of progress was due to pages under writeback. |
3435 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 3436 | */ |
1d82de61 | 3437 | static bool kswapd_shrink_node(pg_data_t *pgdat, |
accf6242 | 3438 | struct scan_control *sc) |
75485363 | 3439 | { |
1d82de61 MG |
3440 | struct zone *zone; |
3441 | int z; | |
75485363 | 3442 | |
1d82de61 MG |
3443 | /* Reclaim a number of pages proportional to the number of zones */ |
3444 | sc->nr_to_reclaim = 0; | |
970a39a3 | 3445 | for (z = 0; z <= sc->reclaim_idx; z++) { |
1d82de61 | 3446 | zone = pgdat->node_zones + z; |
6aa303de | 3447 | if (!managed_zone(zone)) |
1d82de61 | 3448 | continue; |
7c954f6d | 3449 | |
1d82de61 MG |
3450 | sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX); |
3451 | } | |
7c954f6d MG |
3452 | |
3453 | /* | |
1d82de61 MG |
3454 | * Historically care was taken to put equal pressure on all zones but |
3455 | * now pressure is applied based on node LRU order. | |
7c954f6d | 3456 | */ |
970a39a3 | 3457 | shrink_node(pgdat, sc); |
283aba9f | 3458 | |
7c954f6d | 3459 | /* |
1d82de61 MG |
3460 | * Fragmentation may mean that the system cannot be rebalanced for |
3461 | * high-order allocations. If twice the allocation size has been | |
3462 | * reclaimed then recheck watermarks only at order-0 to prevent | |
3463 | * excessive reclaim. Assume that a process requested a high-order | |
3464 | * can direct reclaim/compact. | |
7c954f6d | 3465 | */ |
9861a62c | 3466 | if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) |
1d82de61 | 3467 | sc->order = 0; |
7c954f6d | 3468 | |
b8e83b94 | 3469 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
3470 | } |
3471 | ||
1da177e4 | 3472 | /* |
1d82de61 MG |
3473 | * For kswapd, balance_pgdat() will reclaim pages across a node from zones |
3474 | * that are eligible for use by the caller until at least one zone is | |
3475 | * balanced. | |
1da177e4 | 3476 | * |
1d82de61 | 3477 | * Returns the order kswapd finished reclaiming at. |
1da177e4 LT |
3478 | * |
3479 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 | 3480 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
1d82de61 MG |
3481 | * found to have free_pages <= high_wmark_pages(zone), any page is that zone |
3482 | * or lower is eligible for reclaim until at least one usable zone is | |
3483 | * balanced. | |
1da177e4 | 3484 | */ |
accf6242 | 3485 | static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) |
1da177e4 | 3486 | { |
1da177e4 | 3487 | int i; |
0608f43d AM |
3488 | unsigned long nr_soft_reclaimed; |
3489 | unsigned long nr_soft_scanned; | |
1d82de61 | 3490 | struct zone *zone; |
179e9639 AM |
3491 | struct scan_control sc = { |
3492 | .gfp_mask = GFP_KERNEL, | |
ee814fe2 | 3493 | .order = order, |
b8e83b94 | 3494 | .priority = DEF_PRIORITY, |
ee814fe2 | 3495 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3496 | .may_unmap = 1, |
2e2e4259 | 3497 | .may_swap = 1, |
179e9639 | 3498 | }; |
93781325 OS |
3499 | |
3500 | __fs_reclaim_acquire(); | |
3501 | ||
f8891e5e | 3502 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 3503 | |
9e3b2f8c | 3504 | do { |
c73322d0 | 3505 | unsigned long nr_reclaimed = sc.nr_reclaimed; |
b8e83b94 | 3506 | bool raise_priority = true; |
93781325 | 3507 | bool ret; |
b8e83b94 | 3508 | |
84c7a777 | 3509 | sc.reclaim_idx = classzone_idx; |
1da177e4 | 3510 | |
86c79f6b | 3511 | /* |
84c7a777 MG |
3512 | * If the number of buffer_heads exceeds the maximum allowed |
3513 | * then consider reclaiming from all zones. This has a dual | |
3514 | * purpose -- on 64-bit systems it is expected that | |
3515 | * buffer_heads are stripped during active rotation. On 32-bit | |
3516 | * systems, highmem pages can pin lowmem memory and shrinking | |
3517 | * buffers can relieve lowmem pressure. Reclaim may still not | |
3518 | * go ahead if all eligible zones for the original allocation | |
3519 | * request are balanced to avoid excessive reclaim from kswapd. | |
86c79f6b MG |
3520 | */ |
3521 | if (buffer_heads_over_limit) { | |
3522 | for (i = MAX_NR_ZONES - 1; i >= 0; i--) { | |
3523 | zone = pgdat->node_zones + i; | |
6aa303de | 3524 | if (!managed_zone(zone)) |
86c79f6b | 3525 | continue; |
cc715d99 | 3526 | |
970a39a3 | 3527 | sc.reclaim_idx = i; |
e1dbeda6 | 3528 | break; |
1da177e4 | 3529 | } |
1da177e4 | 3530 | } |
dafcb73e | 3531 | |
86c79f6b | 3532 | /* |
e716f2eb MG |
3533 | * Only reclaim if there are no eligible zones. Note that |
3534 | * sc.reclaim_idx is not used as buffer_heads_over_limit may | |
3535 | * have adjusted it. | |
86c79f6b | 3536 | */ |
e716f2eb MG |
3537 | if (pgdat_balanced(pgdat, sc.order, classzone_idx)) |
3538 | goto out; | |
e1dbeda6 | 3539 | |
1d82de61 MG |
3540 | /* |
3541 | * Do some background aging of the anon list, to give | |
3542 | * pages a chance to be referenced before reclaiming. All | |
3543 | * pages are rotated regardless of classzone as this is | |
3544 | * about consistent aging. | |
3545 | */ | |
ef8f2327 | 3546 | age_active_anon(pgdat, &sc); |
1d82de61 | 3547 | |
b7ea3c41 MG |
3548 | /* |
3549 | * If we're getting trouble reclaiming, start doing writepage | |
3550 | * even in laptop mode. | |
3551 | */ | |
047d72c3 | 3552 | if (sc.priority < DEF_PRIORITY - 2) |
b7ea3c41 MG |
3553 | sc.may_writepage = 1; |
3554 | ||
1d82de61 MG |
3555 | /* Call soft limit reclaim before calling shrink_node. */ |
3556 | sc.nr_scanned = 0; | |
3557 | nr_soft_scanned = 0; | |
ef8f2327 | 3558 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order, |
1d82de61 MG |
3559 | sc.gfp_mask, &nr_soft_scanned); |
3560 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3561 | ||
1da177e4 | 3562 | /* |
1d82de61 MG |
3563 | * There should be no need to raise the scanning priority if |
3564 | * enough pages are already being scanned that that high | |
3565 | * watermark would be met at 100% efficiency. | |
1da177e4 | 3566 | */ |
970a39a3 | 3567 | if (kswapd_shrink_node(pgdat, &sc)) |
1d82de61 | 3568 | raise_priority = false; |
5515061d MG |
3569 | |
3570 | /* | |
3571 | * If the low watermark is met there is no need for processes | |
3572 | * to be throttled on pfmemalloc_wait as they should not be | |
3573 | * able to safely make forward progress. Wake them | |
3574 | */ | |
3575 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
c73322d0 | 3576 | allow_direct_reclaim(pgdat)) |
cfc51155 | 3577 | wake_up_all(&pgdat->pfmemalloc_wait); |
5515061d | 3578 | |
b8e83b94 | 3579 | /* Check if kswapd should be suspending */ |
93781325 OS |
3580 | __fs_reclaim_release(); |
3581 | ret = try_to_freeze(); | |
3582 | __fs_reclaim_acquire(); | |
3583 | if (ret || kthread_should_stop()) | |
b8e83b94 | 3584 | break; |
8357376d | 3585 | |
73ce02e9 | 3586 | /* |
b8e83b94 MG |
3587 | * Raise priority if scanning rate is too low or there was no |
3588 | * progress in reclaiming pages | |
73ce02e9 | 3589 | */ |
c73322d0 JW |
3590 | nr_reclaimed = sc.nr_reclaimed - nr_reclaimed; |
3591 | if (raise_priority || !nr_reclaimed) | |
b8e83b94 | 3592 | sc.priority--; |
1d82de61 | 3593 | } while (sc.priority >= 1); |
1da177e4 | 3594 | |
c73322d0 JW |
3595 | if (!sc.nr_reclaimed) |
3596 | pgdat->kswapd_failures++; | |
3597 | ||
b8e83b94 | 3598 | out: |
2a2e4885 | 3599 | snapshot_refaults(NULL, pgdat); |
93781325 | 3600 | __fs_reclaim_release(); |
0abdee2b | 3601 | /* |
1d82de61 MG |
3602 | * Return the order kswapd stopped reclaiming at as |
3603 | * prepare_kswapd_sleep() takes it into account. If another caller | |
3604 | * entered the allocator slow path while kswapd was awake, order will | |
3605 | * remain at the higher level. | |
0abdee2b | 3606 | */ |
1d82de61 | 3607 | return sc.order; |
1da177e4 LT |
3608 | } |
3609 | ||
e716f2eb MG |
3610 | /* |
3611 | * pgdat->kswapd_classzone_idx is the highest zone index that a recent | |
3612 | * allocation request woke kswapd for. When kswapd has not woken recently, | |
3613 | * the value is MAX_NR_ZONES which is not a valid index. This compares a | |
3614 | * given classzone and returns it or the highest classzone index kswapd | |
3615 | * was recently woke for. | |
3616 | */ | |
3617 | static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat, | |
3618 | enum zone_type classzone_idx) | |
3619 | { | |
3620 | if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES) | |
3621 | return classzone_idx; | |
3622 | ||
3623 | return max(pgdat->kswapd_classzone_idx, classzone_idx); | |
3624 | } | |
3625 | ||
38087d9b MG |
3626 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, |
3627 | unsigned int classzone_idx) | |
f0bc0a60 KM |
3628 | { |
3629 | long remaining = 0; | |
3630 | DEFINE_WAIT(wait); | |
3631 | ||
3632 | if (freezing(current) || kthread_should_stop()) | |
3633 | return; | |
3634 | ||
3635 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3636 | ||
333b0a45 SG |
3637 | /* |
3638 | * Try to sleep for a short interval. Note that kcompactd will only be | |
3639 | * woken if it is possible to sleep for a short interval. This is | |
3640 | * deliberate on the assumption that if reclaim cannot keep an | |
3641 | * eligible zone balanced that it's also unlikely that compaction will | |
3642 | * succeed. | |
3643 | */ | |
d9f21d42 | 3644 | if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { |
fd901c95 VB |
3645 | /* |
3646 | * Compaction records what page blocks it recently failed to | |
3647 | * isolate pages from and skips them in the future scanning. | |
3648 | * When kswapd is going to sleep, it is reasonable to assume | |
3649 | * that pages and compaction may succeed so reset the cache. | |
3650 | */ | |
3651 | reset_isolation_suitable(pgdat); | |
3652 | ||
3653 | /* | |
3654 | * We have freed the memory, now we should compact it to make | |
3655 | * allocation of the requested order possible. | |
3656 | */ | |
38087d9b | 3657 | wakeup_kcompactd(pgdat, alloc_order, classzone_idx); |
fd901c95 | 3658 | |
f0bc0a60 | 3659 | remaining = schedule_timeout(HZ/10); |
38087d9b MG |
3660 | |
3661 | /* | |
3662 | * If woken prematurely then reset kswapd_classzone_idx and | |
3663 | * order. The values will either be from a wakeup request or | |
3664 | * the previous request that slept prematurely. | |
3665 | */ | |
3666 | if (remaining) { | |
e716f2eb | 3667 | pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); |
38087d9b MG |
3668 | pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order); |
3669 | } | |
3670 | ||
f0bc0a60 KM |
3671 | finish_wait(&pgdat->kswapd_wait, &wait); |
3672 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3673 | } | |
3674 | ||
3675 | /* | |
3676 | * After a short sleep, check if it was a premature sleep. If not, then | |
3677 | * go fully to sleep until explicitly woken up. | |
3678 | */ | |
d9f21d42 MG |
3679 | if (!remaining && |
3680 | prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { | |
f0bc0a60 KM |
3681 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3682 | ||
3683 | /* | |
3684 | * vmstat counters are not perfectly accurate and the estimated | |
3685 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3686 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3687 | * watermarks being breached while under pressure, we reduce the | |
3688 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3689 | * them before going back to sleep. | |
3690 | */ | |
3691 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c AK |
3692 | |
3693 | if (!kthread_should_stop()) | |
3694 | schedule(); | |
3695 | ||
f0bc0a60 KM |
3696 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3697 | } else { | |
3698 | if (remaining) | |
3699 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3700 | else | |
3701 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3702 | } | |
3703 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3704 | } | |
3705 | ||
1da177e4 LT |
3706 | /* |
3707 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3708 | * from the init process. |
1da177e4 LT |
3709 | * |
3710 | * This basically trickles out pages so that we have _some_ | |
3711 | * free memory available even if there is no other activity | |
3712 | * that frees anything up. This is needed for things like routing | |
3713 | * etc, where we otherwise might have all activity going on in | |
3714 | * asynchronous contexts that cannot page things out. | |
3715 | * | |
3716 | * If there are applications that are active memory-allocators | |
3717 | * (most normal use), this basically shouldn't matter. | |
3718 | */ | |
3719 | static int kswapd(void *p) | |
3720 | { | |
e716f2eb MG |
3721 | unsigned int alloc_order, reclaim_order; |
3722 | unsigned int classzone_idx = MAX_NR_ZONES - 1; | |
1da177e4 LT |
3723 | pg_data_t *pgdat = (pg_data_t*)p; |
3724 | struct task_struct *tsk = current; | |
f0bc0a60 | 3725 | |
1da177e4 LT |
3726 | struct reclaim_state reclaim_state = { |
3727 | .reclaimed_slab = 0, | |
3728 | }; | |
a70f7302 | 3729 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3730 | |
174596a0 | 3731 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3732 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3733 | current->reclaim_state = &reclaim_state; |
3734 | ||
3735 | /* | |
3736 | * Tell the memory management that we're a "memory allocator", | |
3737 | * and that if we need more memory we should get access to it | |
3738 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3739 | * never get caught in the normal page freeing logic. | |
3740 | * | |
3741 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3742 | * you need a small amount of memory in order to be able to | |
3743 | * page out something else, and this flag essentially protects | |
3744 | * us from recursively trying to free more memory as we're | |
3745 | * trying to free the first piece of memory in the first place). | |
3746 | */ | |
930d9152 | 3747 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3748 | set_freezable(); |
1da177e4 | 3749 | |
e716f2eb MG |
3750 | pgdat->kswapd_order = 0; |
3751 | pgdat->kswapd_classzone_idx = MAX_NR_ZONES; | |
1da177e4 | 3752 | for ( ; ; ) { |
6f6313d4 | 3753 | bool ret; |
3e1d1d28 | 3754 | |
e716f2eb MG |
3755 | alloc_order = reclaim_order = pgdat->kswapd_order; |
3756 | classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); | |
3757 | ||
38087d9b MG |
3758 | kswapd_try_sleep: |
3759 | kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, | |
3760 | classzone_idx); | |
215ddd66 | 3761 | |
38087d9b MG |
3762 | /* Read the new order and classzone_idx */ |
3763 | alloc_order = reclaim_order = pgdat->kswapd_order; | |
e716f2eb | 3764 | classzone_idx = kswapd_classzone_idx(pgdat, 0); |
38087d9b | 3765 | pgdat->kswapd_order = 0; |
e716f2eb | 3766 | pgdat->kswapd_classzone_idx = MAX_NR_ZONES; |
1da177e4 | 3767 | |
8fe23e05 DR |
3768 | ret = try_to_freeze(); |
3769 | if (kthread_should_stop()) | |
3770 | break; | |
3771 | ||
3772 | /* | |
3773 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3774 | * after returning from the refrigerator | |
3775 | */ | |
38087d9b MG |
3776 | if (ret) |
3777 | continue; | |
3778 | ||
3779 | /* | |
3780 | * Reclaim begins at the requested order but if a high-order | |
3781 | * reclaim fails then kswapd falls back to reclaiming for | |
3782 | * order-0. If that happens, kswapd will consider sleeping | |
3783 | * for the order it finished reclaiming at (reclaim_order) | |
3784 | * but kcompactd is woken to compact for the original | |
3785 | * request (alloc_order). | |
3786 | */ | |
e5146b12 MG |
3787 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx, |
3788 | alloc_order); | |
38087d9b MG |
3789 | reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); |
3790 | if (reclaim_order < alloc_order) | |
3791 | goto kswapd_try_sleep; | |
1da177e4 | 3792 | } |
b0a8cc58 | 3793 | |
71abdc15 | 3794 | tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); |
b0a8cc58 | 3795 | current->reclaim_state = NULL; |
71abdc15 | 3796 | |
1da177e4 LT |
3797 | return 0; |
3798 | } | |
3799 | ||
3800 | /* | |
5ecd9d40 DR |
3801 | * A zone is low on free memory or too fragmented for high-order memory. If |
3802 | * kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's | |
3803 | * pgdat. It will wake up kcompactd after reclaiming memory. If kswapd reclaim | |
3804 | * has failed or is not needed, still wake up kcompactd if only compaction is | |
3805 | * needed. | |
1da177e4 | 3806 | */ |
5ecd9d40 DR |
3807 | void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order, |
3808 | enum zone_type classzone_idx) | |
1da177e4 LT |
3809 | { |
3810 | pg_data_t *pgdat; | |
3811 | ||
6aa303de | 3812 | if (!managed_zone(zone)) |
1da177e4 LT |
3813 | return; |
3814 | ||
5ecd9d40 | 3815 | if (!cpuset_zone_allowed(zone, gfp_flags)) |
1da177e4 | 3816 | return; |
88f5acf8 | 3817 | pgdat = zone->zone_pgdat; |
e716f2eb MG |
3818 | pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat, |
3819 | classzone_idx); | |
38087d9b | 3820 | pgdat->kswapd_order = max(pgdat->kswapd_order, order); |
8d0986e2 | 3821 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3822 | return; |
e1a55637 | 3823 | |
5ecd9d40 DR |
3824 | /* Hopeless node, leave it to direct reclaim if possible */ |
3825 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES || | |
3826 | pgdat_balanced(pgdat, order, classzone_idx)) { | |
3827 | /* | |
3828 | * There may be plenty of free memory available, but it's too | |
3829 | * fragmented for high-order allocations. Wake up kcompactd | |
3830 | * and rely on compaction_suitable() to determine if it's | |
3831 | * needed. If it fails, it will defer subsequent attempts to | |
3832 | * ratelimit its work. | |
3833 | */ | |
3834 | if (!(gfp_flags & __GFP_DIRECT_RECLAIM)) | |
3835 | wakeup_kcompactd(pgdat, order, classzone_idx); | |
e716f2eb | 3836 | return; |
5ecd9d40 | 3837 | } |
88f5acf8 | 3838 | |
5ecd9d40 DR |
3839 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order, |
3840 | gfp_flags); | |
8d0986e2 | 3841 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3842 | } |
3843 | ||
c6f37f12 | 3844 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3845 | /* |
7b51755c | 3846 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3847 | * freed pages. |
3848 | * | |
3849 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3850 | * LRU order by reclaiming preferentially | |
3851 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3852 | */ |
7b51755c | 3853 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3854 | { |
d6277db4 | 3855 | struct reclaim_state reclaim_state; |
d6277db4 | 3856 | struct scan_control sc = { |
ee814fe2 | 3857 | .nr_to_reclaim = nr_to_reclaim, |
7b51755c | 3858 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
b2e18757 | 3859 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 | 3860 | .priority = DEF_PRIORITY, |
d6277db4 | 3861 | .may_writepage = 1, |
ee814fe2 JW |
3862 | .may_unmap = 1, |
3863 | .may_swap = 1, | |
7b51755c | 3864 | .hibernation_mode = 1, |
1da177e4 | 3865 | }; |
a09ed5e0 | 3866 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
7b51755c KM |
3867 | struct task_struct *p = current; |
3868 | unsigned long nr_reclaimed; | |
499118e9 | 3869 | unsigned int noreclaim_flag; |
1da177e4 | 3870 | |
d92a8cfc | 3871 | fs_reclaim_acquire(sc.gfp_mask); |
93781325 | 3872 | noreclaim_flag = memalloc_noreclaim_save(); |
7b51755c KM |
3873 | reclaim_state.reclaimed_slab = 0; |
3874 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3875 | |
3115cd91 | 3876 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 3877 | |
7b51755c | 3878 | p->reclaim_state = NULL; |
499118e9 | 3879 | memalloc_noreclaim_restore(noreclaim_flag); |
93781325 | 3880 | fs_reclaim_release(sc.gfp_mask); |
d6277db4 | 3881 | |
7b51755c | 3882 | return nr_reclaimed; |
1da177e4 | 3883 | } |
c6f37f12 | 3884 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3885 | |
1da177e4 LT |
3886 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3887 | not required for correctness. So if the last cpu in a node goes | |
3888 | away, we get changed to run anywhere: as the first one comes back, | |
3889 | restore their cpu bindings. */ | |
517bbed9 | 3890 | static int kswapd_cpu_online(unsigned int cpu) |
1da177e4 | 3891 | { |
58c0a4a7 | 3892 | int nid; |
1da177e4 | 3893 | |
517bbed9 SAS |
3894 | for_each_node_state(nid, N_MEMORY) { |
3895 | pg_data_t *pgdat = NODE_DATA(nid); | |
3896 | const struct cpumask *mask; | |
a70f7302 | 3897 | |
517bbed9 | 3898 | mask = cpumask_of_node(pgdat->node_id); |
c5f59f08 | 3899 | |
517bbed9 SAS |
3900 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
3901 | /* One of our CPUs online: restore mask */ | |
3902 | set_cpus_allowed_ptr(pgdat->kswapd, mask); | |
1da177e4 | 3903 | } |
517bbed9 | 3904 | return 0; |
1da177e4 | 3905 | } |
1da177e4 | 3906 | |
3218ae14 YG |
3907 | /* |
3908 | * This kswapd start function will be called by init and node-hot-add. | |
3909 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3910 | */ | |
3911 | int kswapd_run(int nid) | |
3912 | { | |
3913 | pg_data_t *pgdat = NODE_DATA(nid); | |
3914 | int ret = 0; | |
3915 | ||
3916 | if (pgdat->kswapd) | |
3917 | return 0; | |
3918 | ||
3919 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3920 | if (IS_ERR(pgdat->kswapd)) { | |
3921 | /* failure at boot is fatal */ | |
c6202adf | 3922 | BUG_ON(system_state < SYSTEM_RUNNING); |
d5dc0ad9 GS |
3923 | pr_err("Failed to start kswapd on node %d\n", nid); |
3924 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3925 | pgdat->kswapd = NULL; |
3218ae14 YG |
3926 | } |
3927 | return ret; | |
3928 | } | |
3929 | ||
8fe23e05 | 3930 | /* |
d8adde17 | 3931 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
bfc8c901 | 3932 | * hold mem_hotplug_begin/end(). |
8fe23e05 DR |
3933 | */ |
3934 | void kswapd_stop(int nid) | |
3935 | { | |
3936 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3937 | ||
d8adde17 | 3938 | if (kswapd) { |
8fe23e05 | 3939 | kthread_stop(kswapd); |
d8adde17 JL |
3940 | NODE_DATA(nid)->kswapd = NULL; |
3941 | } | |
8fe23e05 DR |
3942 | } |
3943 | ||
1da177e4 LT |
3944 | static int __init kswapd_init(void) |
3945 | { | |
517bbed9 | 3946 | int nid, ret; |
69e05944 | 3947 | |
1da177e4 | 3948 | swap_setup(); |
48fb2e24 | 3949 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3950 | kswapd_run(nid); |
517bbed9 SAS |
3951 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, |
3952 | "mm/vmscan:online", kswapd_cpu_online, | |
3953 | NULL); | |
3954 | WARN_ON(ret < 0); | |
1da177e4 LT |
3955 | return 0; |
3956 | } | |
3957 | ||
3958 | module_init(kswapd_init) | |
9eeff239 CL |
3959 | |
3960 | #ifdef CONFIG_NUMA | |
3961 | /* | |
a5f5f91d | 3962 | * Node reclaim mode |
9eeff239 | 3963 | * |
a5f5f91d | 3964 | * If non-zero call node_reclaim when the number of free pages falls below |
9eeff239 | 3965 | * the watermarks. |
9eeff239 | 3966 | */ |
a5f5f91d | 3967 | int node_reclaim_mode __read_mostly; |
9eeff239 | 3968 | |
1b2ffb78 | 3969 | #define RECLAIM_OFF 0 |
7d03431c | 3970 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 | 3971 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
95bbc0c7 | 3972 | #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ |
1b2ffb78 | 3973 | |
a92f7126 | 3974 | /* |
a5f5f91d | 3975 | * Priority for NODE_RECLAIM. This determines the fraction of pages |
a92f7126 CL |
3976 | * of a node considered for each zone_reclaim. 4 scans 1/16th of |
3977 | * a zone. | |
3978 | */ | |
a5f5f91d | 3979 | #define NODE_RECLAIM_PRIORITY 4 |
a92f7126 | 3980 | |
9614634f | 3981 | /* |
a5f5f91d | 3982 | * Percentage of pages in a zone that must be unmapped for node_reclaim to |
9614634f CL |
3983 | * occur. |
3984 | */ | |
3985 | int sysctl_min_unmapped_ratio = 1; | |
3986 | ||
0ff38490 CL |
3987 | /* |
3988 | * If the number of slab pages in a zone grows beyond this percentage then | |
3989 | * slab reclaim needs to occur. | |
3990 | */ | |
3991 | int sysctl_min_slab_ratio = 5; | |
3992 | ||
11fb9989 | 3993 | static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat) |
90afa5de | 3994 | { |
11fb9989 MG |
3995 | unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED); |
3996 | unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) + | |
3997 | node_page_state(pgdat, NR_ACTIVE_FILE); | |
90afa5de MG |
3998 | |
3999 | /* | |
4000 | * It's possible for there to be more file mapped pages than | |
4001 | * accounted for by the pages on the file LRU lists because | |
4002 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
4003 | */ | |
4004 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
4005 | } | |
4006 | ||
4007 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
a5f5f91d | 4008 | static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) |
90afa5de | 4009 | { |
d031a157 AM |
4010 | unsigned long nr_pagecache_reclaimable; |
4011 | unsigned long delta = 0; | |
90afa5de MG |
4012 | |
4013 | /* | |
95bbc0c7 | 4014 | * If RECLAIM_UNMAP is set, then all file pages are considered |
90afa5de | 4015 | * potentially reclaimable. Otherwise, we have to worry about |
11fb9989 | 4016 | * pages like swapcache and node_unmapped_file_pages() provides |
90afa5de MG |
4017 | * a better estimate |
4018 | */ | |
a5f5f91d MG |
4019 | if (node_reclaim_mode & RECLAIM_UNMAP) |
4020 | nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES); | |
90afa5de | 4021 | else |
a5f5f91d | 4022 | nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat); |
90afa5de MG |
4023 | |
4024 | /* If we can't clean pages, remove dirty pages from consideration */ | |
a5f5f91d MG |
4025 | if (!(node_reclaim_mode & RECLAIM_WRITE)) |
4026 | delta += node_page_state(pgdat, NR_FILE_DIRTY); | |
90afa5de MG |
4027 | |
4028 | /* Watch for any possible underflows due to delta */ | |
4029 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
4030 | delta = nr_pagecache_reclaimable; | |
4031 | ||
4032 | return nr_pagecache_reclaimable - delta; | |
4033 | } | |
4034 | ||
9eeff239 | 4035 | /* |
a5f5f91d | 4036 | * Try to free up some pages from this node through reclaim. |
9eeff239 | 4037 | */ |
a5f5f91d | 4038 | static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 4039 | { |
7fb2d46d | 4040 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 4041 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
4042 | struct task_struct *p = current; |
4043 | struct reclaim_state reclaim_state; | |
499118e9 | 4044 | unsigned int noreclaim_flag; |
179e9639 | 4045 | struct scan_control sc = { |
62b726c1 | 4046 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
f2f43e56 | 4047 | .gfp_mask = current_gfp_context(gfp_mask), |
bd2f6199 | 4048 | .order = order, |
a5f5f91d MG |
4049 | .priority = NODE_RECLAIM_PRIORITY, |
4050 | .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), | |
4051 | .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), | |
ee814fe2 | 4052 | .may_swap = 1, |
f2f43e56 | 4053 | .reclaim_idx = gfp_zone(gfp_mask), |
179e9639 | 4054 | }; |
9eeff239 | 4055 | |
9eeff239 | 4056 | cond_resched(); |
93781325 | 4057 | fs_reclaim_acquire(sc.gfp_mask); |
d4f7796e | 4058 | /* |
95bbc0c7 | 4059 | * We need to be able to allocate from the reserves for RECLAIM_UNMAP |
d4f7796e | 4060 | * and we also need to be able to write out pages for RECLAIM_WRITE |
95bbc0c7 | 4061 | * and RECLAIM_UNMAP. |
d4f7796e | 4062 | */ |
499118e9 VB |
4063 | noreclaim_flag = memalloc_noreclaim_save(); |
4064 | p->flags |= PF_SWAPWRITE; | |
9eeff239 CL |
4065 | reclaim_state.reclaimed_slab = 0; |
4066 | p->reclaim_state = &reclaim_state; | |
c84db23c | 4067 | |
a5f5f91d | 4068 | if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) { |
0ff38490 | 4069 | /* |
894befec | 4070 | * Free memory by calling shrink node with increasing |
0ff38490 CL |
4071 | * priorities until we have enough memory freed. |
4072 | */ | |
0ff38490 | 4073 | do { |
970a39a3 | 4074 | shrink_node(pgdat, &sc); |
9e3b2f8c | 4075 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); |
0ff38490 | 4076 | } |
c84db23c | 4077 | |
9eeff239 | 4078 | p->reclaim_state = NULL; |
499118e9 VB |
4079 | current->flags &= ~PF_SWAPWRITE; |
4080 | memalloc_noreclaim_restore(noreclaim_flag); | |
93781325 | 4081 | fs_reclaim_release(sc.gfp_mask); |
a79311c1 | 4082 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 4083 | } |
179e9639 | 4084 | |
a5f5f91d | 4085 | int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
179e9639 | 4086 | { |
d773ed6b | 4087 | int ret; |
179e9639 AM |
4088 | |
4089 | /* | |
a5f5f91d | 4090 | * Node reclaim reclaims unmapped file backed pages and |
0ff38490 | 4091 | * slab pages if we are over the defined limits. |
34aa1330 | 4092 | * |
9614634f CL |
4093 | * A small portion of unmapped file backed pages is needed for |
4094 | * file I/O otherwise pages read by file I/O will be immediately | |
a5f5f91d MG |
4095 | * thrown out if the node is overallocated. So we do not reclaim |
4096 | * if less than a specified percentage of the node is used by | |
9614634f | 4097 | * unmapped file backed pages. |
179e9639 | 4098 | */ |
a5f5f91d | 4099 | if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && |
385386cf | 4100 | node_page_state(pgdat, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages) |
a5f5f91d | 4101 | return NODE_RECLAIM_FULL; |
179e9639 AM |
4102 | |
4103 | /* | |
d773ed6b | 4104 | * Do not scan if the allocation should not be delayed. |
179e9639 | 4105 | */ |
d0164adc | 4106 | if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) |
a5f5f91d | 4107 | return NODE_RECLAIM_NOSCAN; |
179e9639 AM |
4108 | |
4109 | /* | |
a5f5f91d | 4110 | * Only run node reclaim on the local node or on nodes that do not |
179e9639 AM |
4111 | * have associated processors. This will favor the local processor |
4112 | * over remote processors and spread off node memory allocations | |
4113 | * as wide as possible. | |
4114 | */ | |
a5f5f91d MG |
4115 | if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) |
4116 | return NODE_RECLAIM_NOSCAN; | |
d773ed6b | 4117 | |
a5f5f91d MG |
4118 | if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) |
4119 | return NODE_RECLAIM_NOSCAN; | |
fa5e084e | 4120 | |
a5f5f91d MG |
4121 | ret = __node_reclaim(pgdat, gfp_mask, order); |
4122 | clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags); | |
d773ed6b | 4123 | |
24cf7251 MG |
4124 | if (!ret) |
4125 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
4126 | ||
d773ed6b | 4127 | return ret; |
179e9639 | 4128 | } |
9eeff239 | 4129 | #endif |
894bc310 | 4130 | |
894bc310 LS |
4131 | /* |
4132 | * page_evictable - test whether a page is evictable | |
4133 | * @page: the page to test | |
894bc310 LS |
4134 | * |
4135 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 4136 | * lists vs unevictable list. |
894bc310 LS |
4137 | * |
4138 | * Reasons page might not be evictable: | |
ba9ddf49 | 4139 | * (1) page's mapping marked unevictable |
b291f000 | 4140 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 4141 | * |
894bc310 | 4142 | */ |
39b5f29a | 4143 | int page_evictable(struct page *page) |
894bc310 | 4144 | { |
e92bb4dd HY |
4145 | int ret; |
4146 | ||
4147 | /* Prevent address_space of inode and swap cache from being freed */ | |
4148 | rcu_read_lock(); | |
4149 | ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); | |
4150 | rcu_read_unlock(); | |
4151 | return ret; | |
894bc310 | 4152 | } |
89e004ea | 4153 | |
85046579 | 4154 | #ifdef CONFIG_SHMEM |
89e004ea | 4155 | /** |
24513264 HD |
4156 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
4157 | * @pages: array of pages to check | |
4158 | * @nr_pages: number of pages to check | |
89e004ea | 4159 | * |
24513264 | 4160 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
4161 | * |
4162 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 4163 | */ |
24513264 | 4164 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 4165 | { |
925b7673 | 4166 | struct lruvec *lruvec; |
785b99fe | 4167 | struct pglist_data *pgdat = NULL; |
24513264 HD |
4168 | int pgscanned = 0; |
4169 | int pgrescued = 0; | |
4170 | int i; | |
89e004ea | 4171 | |
24513264 HD |
4172 | for (i = 0; i < nr_pages; i++) { |
4173 | struct page *page = pages[i]; | |
785b99fe | 4174 | struct pglist_data *pagepgdat = page_pgdat(page); |
89e004ea | 4175 | |
24513264 | 4176 | pgscanned++; |
785b99fe MG |
4177 | if (pagepgdat != pgdat) { |
4178 | if (pgdat) | |
4179 | spin_unlock_irq(&pgdat->lru_lock); | |
4180 | pgdat = pagepgdat; | |
4181 | spin_lock_irq(&pgdat->lru_lock); | |
24513264 | 4182 | } |
785b99fe | 4183 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
89e004ea | 4184 | |
24513264 HD |
4185 | if (!PageLRU(page) || !PageUnevictable(page)) |
4186 | continue; | |
89e004ea | 4187 | |
39b5f29a | 4188 | if (page_evictable(page)) { |
24513264 HD |
4189 | enum lru_list lru = page_lru_base_type(page); |
4190 | ||
309381fe | 4191 | VM_BUG_ON_PAGE(PageActive(page), page); |
24513264 | 4192 | ClearPageUnevictable(page); |
fa9add64 HD |
4193 | del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); |
4194 | add_page_to_lru_list(page, lruvec, lru); | |
24513264 | 4195 | pgrescued++; |
89e004ea | 4196 | } |
24513264 | 4197 | } |
89e004ea | 4198 | |
785b99fe | 4199 | if (pgdat) { |
24513264 HD |
4200 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); |
4201 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
785b99fe | 4202 | spin_unlock_irq(&pgdat->lru_lock); |
89e004ea | 4203 | } |
89e004ea | 4204 | } |
85046579 | 4205 | #endif /* CONFIG_SHMEM */ |