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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 | ||
1da177e4 | 68 | /* This context's GFP mask */ |
6daa0e28 | 69 | gfp_t gfp_mask; |
1da177e4 | 70 | |
ee814fe2 | 71 | /* Allocation order */ |
5ad333eb | 72 | int order; |
66e1707b | 73 | |
ee814fe2 JW |
74 | /* |
75 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
76 | * are scanned. | |
77 | */ | |
78 | nodemask_t *nodemask; | |
9e3b2f8c | 79 | |
f16015fb JW |
80 | /* |
81 | * The memory cgroup that hit its limit and as a result is the | |
82 | * primary target of this reclaim invocation. | |
83 | */ | |
84 | struct mem_cgroup *target_mem_cgroup; | |
66e1707b | 85 | |
ee814fe2 JW |
86 | /* Scan (total_size >> priority) pages at once */ |
87 | int priority; | |
88 | ||
b2e18757 MG |
89 | /* The highest zone to isolate pages for reclaim from */ |
90 | enum zone_type reclaim_idx; | |
91 | ||
1276ad68 | 92 | /* Writepage batching in laptop mode; RECLAIM_WRITE */ |
ee814fe2 JW |
93 | unsigned int may_writepage:1; |
94 | ||
95 | /* Can mapped pages be reclaimed? */ | |
96 | unsigned int may_unmap:1; | |
97 | ||
98 | /* Can pages be swapped as part of reclaim? */ | |
99 | unsigned int may_swap:1; | |
100 | ||
d6622f63 YX |
101 | /* |
102 | * Cgroups are not reclaimed below their configured memory.low, | |
103 | * unless we threaten to OOM. If any cgroups are skipped due to | |
104 | * memory.low and nothing was reclaimed, go back for memory.low. | |
105 | */ | |
106 | unsigned int memcg_low_reclaim:1; | |
107 | unsigned int memcg_low_skipped:1; | |
241994ed | 108 | |
ee814fe2 JW |
109 | unsigned int hibernation_mode:1; |
110 | ||
111 | /* One of the zones is ready for compaction */ | |
112 | unsigned int compaction_ready:1; | |
113 | ||
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; | |
1da177e4 LT |
119 | }; |
120 | ||
1da177e4 LT |
121 | #ifdef ARCH_HAS_PREFETCH |
122 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
123 | do { \ | |
124 | if ((_page)->lru.prev != _base) { \ | |
125 | struct page *prev; \ | |
126 | \ | |
127 | prev = lru_to_page(&(_page->lru)); \ | |
128 | prefetch(&prev->_field); \ | |
129 | } \ | |
130 | } while (0) | |
131 | #else | |
132 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
133 | #endif | |
134 | ||
135 | #ifdef ARCH_HAS_PREFETCHW | |
136 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
137 | do { \ | |
138 | if ((_page)->lru.prev != _base) { \ | |
139 | struct page *prev; \ | |
140 | \ | |
141 | prev = lru_to_page(&(_page->lru)); \ | |
142 | prefetchw(&prev->_field); \ | |
143 | } \ | |
144 | } while (0) | |
145 | #else | |
146 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
147 | #endif | |
148 | ||
149 | /* | |
150 | * From 0 .. 100. Higher means more swappy. | |
151 | */ | |
152 | int vm_swappiness = 60; | |
d0480be4 WSH |
153 | /* |
154 | * The total number of pages which are beyond the high watermark within all | |
155 | * zones. | |
156 | */ | |
157 | unsigned long vm_total_pages; | |
1da177e4 LT |
158 | |
159 | static LIST_HEAD(shrinker_list); | |
160 | static DECLARE_RWSEM(shrinker_rwsem); | |
161 | ||
c255a458 | 162 | #ifdef CONFIG_MEMCG |
89b5fae5 JW |
163 | static bool global_reclaim(struct scan_control *sc) |
164 | { | |
f16015fb | 165 | return !sc->target_mem_cgroup; |
89b5fae5 | 166 | } |
97c9341f TH |
167 | |
168 | /** | |
169 | * sane_reclaim - is the usual dirty throttling mechanism operational? | |
170 | * @sc: scan_control in question | |
171 | * | |
172 | * The normal page dirty throttling mechanism in balance_dirty_pages() is | |
173 | * completely broken with the legacy memcg and direct stalling in | |
174 | * shrink_page_list() is used for throttling instead, which lacks all the | |
175 | * niceties such as fairness, adaptive pausing, bandwidth proportional | |
176 | * allocation and configurability. | |
177 | * | |
178 | * This function tests whether the vmscan currently in progress can assume | |
179 | * that the normal dirty throttling mechanism is operational. | |
180 | */ | |
181 | static bool sane_reclaim(struct scan_control *sc) | |
182 | { | |
183 | struct mem_cgroup *memcg = sc->target_mem_cgroup; | |
184 | ||
185 | if (!memcg) | |
186 | return true; | |
187 | #ifdef CONFIG_CGROUP_WRITEBACK | |
69234ace | 188 | if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) |
97c9341f TH |
189 | return true; |
190 | #endif | |
191 | return false; | |
192 | } | |
91a45470 | 193 | #else |
89b5fae5 JW |
194 | static bool global_reclaim(struct scan_control *sc) |
195 | { | |
196 | return true; | |
197 | } | |
97c9341f TH |
198 | |
199 | static bool sane_reclaim(struct scan_control *sc) | |
200 | { | |
201 | return true; | |
202 | } | |
91a45470 KH |
203 | #endif |
204 | ||
5a1c84b4 MG |
205 | /* |
206 | * This misses isolated pages which are not accounted for to save counters. | |
207 | * As the data only determines if reclaim or compaction continues, it is | |
208 | * not expected that isolated pages will be a dominating factor. | |
209 | */ | |
210 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
211 | { | |
212 | unsigned long nr; | |
213 | ||
214 | nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + | |
215 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); | |
216 | if (get_nr_swap_pages() > 0) | |
217 | nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + | |
218 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); | |
219 | ||
220 | return nr; | |
221 | } | |
222 | ||
599d0c95 MG |
223 | unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat) |
224 | { | |
225 | unsigned long nr; | |
226 | ||
227 | nr = node_page_state_snapshot(pgdat, NR_ACTIVE_FILE) + | |
228 | node_page_state_snapshot(pgdat, NR_INACTIVE_FILE) + | |
229 | node_page_state_snapshot(pgdat, NR_ISOLATED_FILE); | |
6e543d57 LD |
230 | |
231 | if (get_nr_swap_pages() > 0) | |
599d0c95 MG |
232 | nr += node_page_state_snapshot(pgdat, NR_ACTIVE_ANON) + |
233 | node_page_state_snapshot(pgdat, NR_INACTIVE_ANON) + | |
234 | node_page_state_snapshot(pgdat, NR_ISOLATED_ANON); | |
6e543d57 LD |
235 | |
236 | return nr; | |
237 | } | |
238 | ||
fd538803 MH |
239 | /** |
240 | * lruvec_lru_size - Returns the number of pages on the given LRU list. | |
241 | * @lruvec: lru vector | |
242 | * @lru: lru to use | |
243 | * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list) | |
244 | */ | |
245 | unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx) | |
c9f299d9 | 246 | { |
fd538803 MH |
247 | unsigned long lru_size; |
248 | int zid; | |
249 | ||
c3c787e8 | 250 | if (!mem_cgroup_disabled()) |
fd538803 MH |
251 | lru_size = mem_cgroup_get_lru_size(lruvec, lru); |
252 | else | |
253 | lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru); | |
a3d8e054 | 254 | |
fd538803 MH |
255 | for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) { |
256 | struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid]; | |
257 | unsigned long size; | |
c9f299d9 | 258 | |
fd538803 MH |
259 | if (!managed_zone(zone)) |
260 | continue; | |
261 | ||
262 | if (!mem_cgroup_disabled()) | |
263 | size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid); | |
264 | else | |
265 | size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid], | |
266 | NR_ZONE_LRU_BASE + lru); | |
267 | lru_size -= min(size, lru_size); | |
268 | } | |
269 | ||
270 | return lru_size; | |
b4536f0c | 271 | |
b4536f0c MH |
272 | } |
273 | ||
1da177e4 | 274 | /* |
1d3d4437 | 275 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 276 | */ |
7632554f | 277 | int prealloc_shrinker(struct shrinker *shrinker) |
1da177e4 | 278 | { |
1d3d4437 GC |
279 | size_t size = sizeof(*shrinker->nr_deferred); |
280 | ||
1d3d4437 GC |
281 | if (shrinker->flags & SHRINKER_NUMA_AWARE) |
282 | size *= nr_node_ids; | |
283 | ||
284 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
285 | if (!shrinker->nr_deferred) | |
286 | return -ENOMEM; | |
7632554f TH |
287 | return 0; |
288 | } | |
289 | ||
290 | void free_prealloced_shrinker(struct shrinker *shrinker) | |
291 | { | |
292 | kfree(shrinker->nr_deferred); | |
293 | shrinker->nr_deferred = NULL; | |
294 | } | |
1d3d4437 | 295 | |
7632554f TH |
296 | void register_shrinker_prepared(struct shrinker *shrinker) |
297 | { | |
8e1f936b RR |
298 | down_write(&shrinker_rwsem); |
299 | list_add_tail(&shrinker->list, &shrinker_list); | |
300 | up_write(&shrinker_rwsem); | |
7632554f TH |
301 | } |
302 | ||
303 | int register_shrinker(struct shrinker *shrinker) | |
304 | { | |
305 | int err = prealloc_shrinker(shrinker); | |
306 | ||
307 | if (err) | |
308 | return err; | |
309 | register_shrinker_prepared(shrinker); | |
1d3d4437 | 310 | return 0; |
1da177e4 | 311 | } |
8e1f936b | 312 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
313 | |
314 | /* | |
315 | * Remove one | |
316 | */ | |
8e1f936b | 317 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 | 318 | { |
bb422a73 TH |
319 | if (!shrinker->nr_deferred) |
320 | return; | |
1da177e4 LT |
321 | down_write(&shrinker_rwsem); |
322 | list_del(&shrinker->list); | |
323 | up_write(&shrinker_rwsem); | |
ae393321 | 324 | kfree(shrinker->nr_deferred); |
bb422a73 | 325 | shrinker->nr_deferred = NULL; |
1da177e4 | 326 | } |
8e1f936b | 327 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
328 | |
329 | #define SHRINK_BATCH 128 | |
1d3d4437 | 330 | |
cb731d6c VD |
331 | static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, |
332 | struct shrinker *shrinker, | |
333 | unsigned long nr_scanned, | |
334 | unsigned long nr_eligible) | |
1d3d4437 GC |
335 | { |
336 | unsigned long freed = 0; | |
337 | unsigned long long delta; | |
338 | long total_scan; | |
d5bc5fd3 | 339 | long freeable; |
1d3d4437 GC |
340 | long nr; |
341 | long new_nr; | |
342 | int nid = shrinkctl->nid; | |
343 | long batch_size = shrinker->batch ? shrinker->batch | |
344 | : SHRINK_BATCH; | |
5f33a080 | 345 | long scanned = 0, next_deferred; |
1d3d4437 | 346 | |
d5bc5fd3 VD |
347 | freeable = shrinker->count_objects(shrinker, shrinkctl); |
348 | if (freeable == 0) | |
1d3d4437 GC |
349 | return 0; |
350 | ||
351 | /* | |
352 | * copy the current shrinker scan count into a local variable | |
353 | * and zero it so that other concurrent shrinker invocations | |
354 | * don't also do this scanning work. | |
355 | */ | |
356 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
357 | ||
358 | total_scan = nr; | |
6b4f7799 | 359 | delta = (4 * nr_scanned) / shrinker->seeks; |
d5bc5fd3 | 360 | delta *= freeable; |
6b4f7799 | 361 | do_div(delta, nr_eligible + 1); |
1d3d4437 GC |
362 | total_scan += delta; |
363 | if (total_scan < 0) { | |
8612c663 | 364 | pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", |
a0b02131 | 365 | shrinker->scan_objects, total_scan); |
d5bc5fd3 | 366 | total_scan = freeable; |
5f33a080 SL |
367 | next_deferred = nr; |
368 | } else | |
369 | next_deferred = total_scan; | |
1d3d4437 GC |
370 | |
371 | /* | |
372 | * We need to avoid excessive windup on filesystem shrinkers | |
373 | * due to large numbers of GFP_NOFS allocations causing the | |
374 | * shrinkers to return -1 all the time. This results in a large | |
375 | * nr being built up so when a shrink that can do some work | |
376 | * comes along it empties the entire cache due to nr >>> | |
d5bc5fd3 | 377 | * freeable. This is bad for sustaining a working set in |
1d3d4437 GC |
378 | * memory. |
379 | * | |
380 | * Hence only allow the shrinker to scan the entire cache when | |
381 | * a large delta change is calculated directly. | |
382 | */ | |
d5bc5fd3 VD |
383 | if (delta < freeable / 4) |
384 | total_scan = min(total_scan, freeable / 2); | |
1d3d4437 GC |
385 | |
386 | /* | |
387 | * Avoid risking looping forever due to too large nr value: | |
388 | * never try to free more than twice the estimate number of | |
389 | * freeable entries. | |
390 | */ | |
d5bc5fd3 VD |
391 | if (total_scan > freeable * 2) |
392 | total_scan = freeable * 2; | |
1d3d4437 GC |
393 | |
394 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
6b4f7799 JW |
395 | nr_scanned, nr_eligible, |
396 | freeable, delta, total_scan); | |
1d3d4437 | 397 | |
0b1fb40a VD |
398 | /* |
399 | * Normally, we should not scan less than batch_size objects in one | |
400 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
401 | * than batch_size objects in total and we are really tight on memory, | |
402 | * we will try to reclaim all available objects, otherwise we can end | |
403 | * up failing allocations although there are plenty of reclaimable | |
404 | * objects spread over several slabs with usage less than the | |
405 | * batch_size. | |
406 | * | |
407 | * We detect the "tight on memory" situations by looking at the total | |
408 | * number of objects we want to scan (total_scan). If it is greater | |
d5bc5fd3 | 409 | * than the total number of objects on slab (freeable), we must be |
0b1fb40a VD |
410 | * scanning at high prio and therefore should try to reclaim as much as |
411 | * possible. | |
412 | */ | |
413 | while (total_scan >= batch_size || | |
d5bc5fd3 | 414 | total_scan >= freeable) { |
a0b02131 | 415 | unsigned long ret; |
0b1fb40a | 416 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 417 | |
0b1fb40a | 418 | shrinkctl->nr_to_scan = nr_to_scan; |
d460acb5 | 419 | shrinkctl->nr_scanned = nr_to_scan; |
a0b02131 DC |
420 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
421 | if (ret == SHRINK_STOP) | |
422 | break; | |
423 | freed += ret; | |
1d3d4437 | 424 | |
d460acb5 CW |
425 | count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); |
426 | total_scan -= shrinkctl->nr_scanned; | |
427 | scanned += shrinkctl->nr_scanned; | |
1d3d4437 GC |
428 | |
429 | cond_resched(); | |
430 | } | |
431 | ||
5f33a080 SL |
432 | if (next_deferred >= scanned) |
433 | next_deferred -= scanned; | |
434 | else | |
435 | next_deferred = 0; | |
1d3d4437 GC |
436 | /* |
437 | * move the unused scan count back into the shrinker in a | |
438 | * manner that handles concurrent updates. If we exhausted the | |
439 | * scan, there is no need to do an update. | |
440 | */ | |
5f33a080 SL |
441 | if (next_deferred > 0) |
442 | new_nr = atomic_long_add_return(next_deferred, | |
1d3d4437 GC |
443 | &shrinker->nr_deferred[nid]); |
444 | else | |
445 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
446 | ||
df9024a8 | 447 | trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); |
1d3d4437 | 448 | return freed; |
1495f230 YH |
449 | } |
450 | ||
6b4f7799 | 451 | /** |
cb731d6c | 452 | * shrink_slab - shrink slab caches |
6b4f7799 JW |
453 | * @gfp_mask: allocation context |
454 | * @nid: node whose slab caches to target | |
cb731d6c | 455 | * @memcg: memory cgroup whose slab caches to target |
6b4f7799 JW |
456 | * @nr_scanned: pressure numerator |
457 | * @nr_eligible: pressure denominator | |
1da177e4 | 458 | * |
6b4f7799 | 459 | * Call the shrink functions to age shrinkable caches. |
1da177e4 | 460 | * |
6b4f7799 JW |
461 | * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, |
462 | * unaware shrinkers will receive a node id of 0 instead. | |
1da177e4 | 463 | * |
cb731d6c VD |
464 | * @memcg specifies the memory cgroup to target. If it is not NULL, |
465 | * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan | |
0fc9f58a VD |
466 | * objects from the memory cgroup specified. Otherwise, only unaware |
467 | * shrinkers are called. | |
cb731d6c | 468 | * |
6b4f7799 JW |
469 | * @nr_scanned and @nr_eligible form a ratio that indicate how much of |
470 | * the available objects should be scanned. Page reclaim for example | |
471 | * passes the number of pages scanned and the number of pages on the | |
472 | * LRU lists that it considered on @nid, plus a bias in @nr_scanned | |
473 | * when it encountered mapped pages. The ratio is further biased by | |
474 | * the ->seeks setting of the shrink function, which indicates the | |
475 | * cost to recreate an object relative to that of an LRU page. | |
b15e0905 | 476 | * |
6b4f7799 | 477 | * Returns the number of reclaimed slab objects. |
1da177e4 | 478 | */ |
cb731d6c VD |
479 | static unsigned long shrink_slab(gfp_t gfp_mask, int nid, |
480 | struct mem_cgroup *memcg, | |
481 | unsigned long nr_scanned, | |
482 | unsigned long nr_eligible) | |
1da177e4 LT |
483 | { |
484 | struct shrinker *shrinker; | |
24f7c6b9 | 485 | unsigned long freed = 0; |
1da177e4 | 486 | |
0fc9f58a | 487 | if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg))) |
cb731d6c VD |
488 | return 0; |
489 | ||
6b4f7799 JW |
490 | if (nr_scanned == 0) |
491 | nr_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 492 | |
f06590bd | 493 | if (!down_read_trylock(&shrinker_rwsem)) { |
24f7c6b9 DC |
494 | /* |
495 | * If we would return 0, our callers would understand that we | |
496 | * have nothing else to shrink and give up trying. By returning | |
497 | * 1 we keep it going and assume we'll be able to shrink next | |
498 | * time. | |
499 | */ | |
500 | freed = 1; | |
f06590bd MK |
501 | goto out; |
502 | } | |
1da177e4 LT |
503 | |
504 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
6b4f7799 JW |
505 | struct shrink_control sc = { |
506 | .gfp_mask = gfp_mask, | |
507 | .nid = nid, | |
cb731d6c | 508 | .memcg = memcg, |
6b4f7799 | 509 | }; |
ec97097b | 510 | |
0fc9f58a VD |
511 | /* |
512 | * If kernel memory accounting is disabled, we ignore | |
513 | * SHRINKER_MEMCG_AWARE flag and call all shrinkers | |
514 | * passing NULL for memcg. | |
515 | */ | |
516 | if (memcg_kmem_enabled() && | |
517 | !!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE)) | |
cb731d6c VD |
518 | continue; |
519 | ||
6b4f7799 JW |
520 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) |
521 | sc.nid = 0; | |
1da177e4 | 522 | |
cb731d6c | 523 | freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible); |
8daa5773 MK |
524 | /* |
525 | * Bail out if someone want to register a new shrinker to | |
526 | * prevent the regsitration from being stalled for long periods | |
527 | * by parallel ongoing shrinking. | |
528 | */ | |
529 | if (rwsem_is_contended(&shrinker_rwsem)) { | |
530 | freed = freed ? : 1; | |
531 | break; | |
532 | } | |
1da177e4 | 533 | } |
6b4f7799 | 534 | |
1da177e4 | 535 | up_read(&shrinker_rwsem); |
f06590bd MK |
536 | out: |
537 | cond_resched(); | |
24f7c6b9 | 538 | return freed; |
1da177e4 LT |
539 | } |
540 | ||
cb731d6c VD |
541 | void drop_slab_node(int nid) |
542 | { | |
543 | unsigned long freed; | |
544 | ||
545 | do { | |
546 | struct mem_cgroup *memcg = NULL; | |
547 | ||
548 | freed = 0; | |
549 | do { | |
550 | freed += shrink_slab(GFP_KERNEL, nid, memcg, | |
551 | 1000, 1000); | |
552 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); | |
553 | } while (freed > 10); | |
554 | } | |
555 | ||
556 | void drop_slab(void) | |
557 | { | |
558 | int nid; | |
559 | ||
560 | for_each_online_node(nid) | |
561 | drop_slab_node(nid); | |
562 | } | |
563 | ||
1da177e4 LT |
564 | static inline int is_page_cache_freeable(struct page *page) |
565 | { | |
ceddc3a5 JW |
566 | /* |
567 | * A freeable page cache page is referenced only by the caller | |
568 | * that isolated the page, the page cache radix tree and | |
569 | * optional buffer heads at page->private. | |
570 | */ | |
bd4c82c2 HY |
571 | int radix_pins = PageTransHuge(page) && PageSwapCache(page) ? |
572 | HPAGE_PMD_NR : 1; | |
573 | return page_count(page) - page_has_private(page) == 1 + radix_pins; | |
1da177e4 LT |
574 | } |
575 | ||
703c2708 | 576 | static int may_write_to_inode(struct inode *inode, struct scan_control *sc) |
1da177e4 | 577 | { |
930d9152 | 578 | if (current->flags & PF_SWAPWRITE) |
1da177e4 | 579 | return 1; |
703c2708 | 580 | if (!inode_write_congested(inode)) |
1da177e4 | 581 | return 1; |
703c2708 | 582 | if (inode_to_bdi(inode) == current->backing_dev_info) |
1da177e4 LT |
583 | return 1; |
584 | return 0; | |
585 | } | |
586 | ||
587 | /* | |
588 | * We detected a synchronous write error writing a page out. Probably | |
589 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
590 | * fsync(), msync() or close(). | |
591 | * | |
592 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
593 | * prevents it from being freed up. But we have a ref on the page and once | |
594 | * that page is locked, the mapping is pinned. | |
595 | * | |
596 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
597 | * __GFP_FS. | |
598 | */ | |
599 | static void handle_write_error(struct address_space *mapping, | |
600 | struct page *page, int error) | |
601 | { | |
7eaceacc | 602 | lock_page(page); |
3e9f45bd GC |
603 | if (page_mapping(page) == mapping) |
604 | mapping_set_error(mapping, error); | |
1da177e4 LT |
605 | unlock_page(page); |
606 | } | |
607 | ||
04e62a29 CL |
608 | /* possible outcome of pageout() */ |
609 | typedef enum { | |
610 | /* failed to write page out, page is locked */ | |
611 | PAGE_KEEP, | |
612 | /* move page to the active list, page is locked */ | |
613 | PAGE_ACTIVATE, | |
614 | /* page has been sent to the disk successfully, page is unlocked */ | |
615 | PAGE_SUCCESS, | |
616 | /* page is clean and locked */ | |
617 | PAGE_CLEAN, | |
618 | } pageout_t; | |
619 | ||
1da177e4 | 620 | /* |
1742f19f AM |
621 | * pageout is called by shrink_page_list() for each dirty page. |
622 | * Calls ->writepage(). | |
1da177e4 | 623 | */ |
c661b078 | 624 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 625 | struct scan_control *sc) |
1da177e4 LT |
626 | { |
627 | /* | |
628 | * If the page is dirty, only perform writeback if that write | |
629 | * will be non-blocking. To prevent this allocation from being | |
630 | * stalled by pagecache activity. But note that there may be | |
631 | * stalls if we need to run get_block(). We could test | |
632 | * PagePrivate for that. | |
633 | * | |
8174202b | 634 | * If this process is currently in __generic_file_write_iter() against |
1da177e4 LT |
635 | * this page's queue, we can perform writeback even if that |
636 | * will block. | |
637 | * | |
638 | * If the page is swapcache, write it back even if that would | |
639 | * block, for some throttling. This happens by accident, because | |
640 | * swap_backing_dev_info is bust: it doesn't reflect the | |
641 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
642 | */ |
643 | if (!is_page_cache_freeable(page)) | |
644 | return PAGE_KEEP; | |
645 | if (!mapping) { | |
646 | /* | |
647 | * Some data journaling orphaned pages can have | |
648 | * page->mapping == NULL while being dirty with clean buffers. | |
649 | */ | |
266cf658 | 650 | if (page_has_private(page)) { |
1da177e4 LT |
651 | if (try_to_free_buffers(page)) { |
652 | ClearPageDirty(page); | |
b1de0d13 | 653 | pr_info("%s: orphaned page\n", __func__); |
1da177e4 LT |
654 | return PAGE_CLEAN; |
655 | } | |
656 | } | |
657 | return PAGE_KEEP; | |
658 | } | |
659 | if (mapping->a_ops->writepage == NULL) | |
660 | return PAGE_ACTIVATE; | |
703c2708 | 661 | if (!may_write_to_inode(mapping->host, sc)) |
1da177e4 LT |
662 | return PAGE_KEEP; |
663 | ||
664 | if (clear_page_dirty_for_io(page)) { | |
665 | int res; | |
666 | struct writeback_control wbc = { | |
667 | .sync_mode = WB_SYNC_NONE, | |
668 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
669 | .range_start = 0, |
670 | .range_end = LLONG_MAX, | |
1da177e4 LT |
671 | .for_reclaim = 1, |
672 | }; | |
673 | ||
674 | SetPageReclaim(page); | |
675 | res = mapping->a_ops->writepage(page, &wbc); | |
676 | if (res < 0) | |
677 | handle_write_error(mapping, page, res); | |
994fc28c | 678 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
679 | ClearPageReclaim(page); |
680 | return PAGE_ACTIVATE; | |
681 | } | |
c661b078 | 682 | |
1da177e4 LT |
683 | if (!PageWriteback(page)) { |
684 | /* synchronous write or broken a_ops? */ | |
685 | ClearPageReclaim(page); | |
686 | } | |
3aa23851 | 687 | trace_mm_vmscan_writepage(page); |
c4a25635 | 688 | inc_node_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
689 | return PAGE_SUCCESS; |
690 | } | |
691 | ||
692 | return PAGE_CLEAN; | |
693 | } | |
694 | ||
a649fd92 | 695 | /* |
e286781d NP |
696 | * Same as remove_mapping, but if the page is removed from the mapping, it |
697 | * gets returned with a refcount of 0. | |
a649fd92 | 698 | */ |
a528910e JW |
699 | static int __remove_mapping(struct address_space *mapping, struct page *page, |
700 | bool reclaimed) | |
49d2e9cc | 701 | { |
c4843a75 | 702 | unsigned long flags; |
bd4c82c2 | 703 | int refcount; |
c4843a75 | 704 | |
28e4d965 NP |
705 | BUG_ON(!PageLocked(page)); |
706 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 707 | |
c4843a75 | 708 | spin_lock_irqsave(&mapping->tree_lock, flags); |
49d2e9cc | 709 | /* |
0fd0e6b0 NP |
710 | * The non racy check for a busy page. |
711 | * | |
712 | * Must be careful with the order of the tests. When someone has | |
713 | * a ref to the page, it may be possible that they dirty it then | |
714 | * drop the reference. So if PageDirty is tested before page_count | |
715 | * here, then the following race may occur: | |
716 | * | |
717 | * get_user_pages(&page); | |
718 | * [user mapping goes away] | |
719 | * write_to(page); | |
720 | * !PageDirty(page) [good] | |
721 | * SetPageDirty(page); | |
722 | * put_page(page); | |
723 | * !page_count(page) [good, discard it] | |
724 | * | |
725 | * [oops, our write_to data is lost] | |
726 | * | |
727 | * Reversing the order of the tests ensures such a situation cannot | |
728 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
0139aa7b | 729 | * load is not satisfied before that of page->_refcount. |
0fd0e6b0 NP |
730 | * |
731 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
732 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 733 | */ |
bd4c82c2 HY |
734 | if (unlikely(PageTransHuge(page)) && PageSwapCache(page)) |
735 | refcount = 1 + HPAGE_PMD_NR; | |
736 | else | |
737 | refcount = 2; | |
738 | if (!page_ref_freeze(page, refcount)) | |
49d2e9cc | 739 | goto cannot_free; |
e286781d NP |
740 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
741 | if (unlikely(PageDirty(page))) { | |
bd4c82c2 | 742 | page_ref_unfreeze(page, refcount); |
49d2e9cc | 743 | goto cannot_free; |
e286781d | 744 | } |
49d2e9cc CL |
745 | |
746 | if (PageSwapCache(page)) { | |
747 | swp_entry_t swap = { .val = page_private(page) }; | |
0a31bc97 | 748 | mem_cgroup_swapout(page, swap); |
49d2e9cc | 749 | __delete_from_swap_cache(page); |
c4843a75 | 750 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
75f6d6d2 | 751 | put_swap_page(page, swap); |
e286781d | 752 | } else { |
6072d13c | 753 | void (*freepage)(struct page *); |
a528910e | 754 | void *shadow = NULL; |
6072d13c LT |
755 | |
756 | freepage = mapping->a_ops->freepage; | |
a528910e JW |
757 | /* |
758 | * Remember a shadow entry for reclaimed file cache in | |
759 | * order to detect refaults, thus thrashing, later on. | |
760 | * | |
761 | * But don't store shadows in an address space that is | |
762 | * already exiting. This is not just an optizimation, | |
763 | * inode reclaim needs to empty out the radix tree or | |
764 | * the nodes are lost. Don't plant shadows behind its | |
765 | * back. | |
f9fe48be RZ |
766 | * |
767 | * We also don't store shadows for DAX mappings because the | |
768 | * only page cache pages found in these are zero pages | |
769 | * covering holes, and because we don't want to mix DAX | |
770 | * exceptional entries and shadow exceptional entries in the | |
771 | * same page_tree. | |
a528910e JW |
772 | */ |
773 | if (reclaimed && page_is_file_cache(page) && | |
f9fe48be | 774 | !mapping_exiting(mapping) && !dax_mapping(mapping)) |
a528910e | 775 | shadow = workingset_eviction(mapping, page); |
62cccb8c | 776 | __delete_from_page_cache(page, shadow); |
c4843a75 | 777 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
6072d13c LT |
778 | |
779 | if (freepage != NULL) | |
780 | freepage(page); | |
49d2e9cc CL |
781 | } |
782 | ||
49d2e9cc CL |
783 | return 1; |
784 | ||
785 | cannot_free: | |
c4843a75 | 786 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
49d2e9cc CL |
787 | return 0; |
788 | } | |
789 | ||
e286781d NP |
790 | /* |
791 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
792 | * someone else has a ref on the page, abort and return 0. If it was | |
793 | * successfully detached, return 1. Assumes the caller has a single ref on | |
794 | * this page. | |
795 | */ | |
796 | int remove_mapping(struct address_space *mapping, struct page *page) | |
797 | { | |
a528910e | 798 | if (__remove_mapping(mapping, page, false)) { |
e286781d NP |
799 | /* |
800 | * Unfreezing the refcount with 1 rather than 2 effectively | |
801 | * drops the pagecache ref for us without requiring another | |
802 | * atomic operation. | |
803 | */ | |
fe896d18 | 804 | page_ref_unfreeze(page, 1); |
e286781d NP |
805 | return 1; |
806 | } | |
807 | return 0; | |
808 | } | |
809 | ||
894bc310 LS |
810 | /** |
811 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
812 | * @page: page to be put back to appropriate lru list | |
813 | * | |
814 | * Add previously isolated @page to appropriate LRU list. | |
815 | * Page may still be unevictable for other reasons. | |
816 | * | |
817 | * lru_lock must not be held, interrupts must be enabled. | |
818 | */ | |
894bc310 LS |
819 | void putback_lru_page(struct page *page) |
820 | { | |
0ec3b74c | 821 | bool is_unevictable; |
bbfd28ee | 822 | int was_unevictable = PageUnevictable(page); |
894bc310 | 823 | |
309381fe | 824 | VM_BUG_ON_PAGE(PageLRU(page), page); |
894bc310 LS |
825 | |
826 | redo: | |
827 | ClearPageUnevictable(page); | |
828 | ||
39b5f29a | 829 | if (page_evictable(page)) { |
894bc310 LS |
830 | /* |
831 | * For evictable pages, we can use the cache. | |
832 | * In event of a race, worst case is we end up with an | |
833 | * unevictable page on [in]active list. | |
834 | * We know how to handle that. | |
835 | */ | |
0ec3b74c | 836 | is_unevictable = false; |
c53954a0 | 837 | lru_cache_add(page); |
894bc310 LS |
838 | } else { |
839 | /* | |
840 | * Put unevictable pages directly on zone's unevictable | |
841 | * list. | |
842 | */ | |
0ec3b74c | 843 | is_unevictable = true; |
894bc310 | 844 | add_page_to_unevictable_list(page); |
6a7b9548 | 845 | /* |
21ee9f39 MK |
846 | * When racing with an mlock or AS_UNEVICTABLE clearing |
847 | * (page is unlocked) make sure that if the other thread | |
848 | * does not observe our setting of PG_lru and fails | |
24513264 | 849 | * isolation/check_move_unevictable_pages, |
21ee9f39 | 850 | * we see PG_mlocked/AS_UNEVICTABLE cleared below and move |
6a7b9548 JW |
851 | * the page back to the evictable list. |
852 | * | |
21ee9f39 | 853 | * The other side is TestClearPageMlocked() or shmem_lock(). |
6a7b9548 JW |
854 | */ |
855 | smp_mb(); | |
894bc310 | 856 | } |
894bc310 LS |
857 | |
858 | /* | |
859 | * page's status can change while we move it among lru. If an evictable | |
860 | * page is on unevictable list, it never be freed. To avoid that, | |
861 | * check after we added it to the list, again. | |
862 | */ | |
0ec3b74c | 863 | if (is_unevictable && page_evictable(page)) { |
894bc310 LS |
864 | if (!isolate_lru_page(page)) { |
865 | put_page(page); | |
866 | goto redo; | |
867 | } | |
868 | /* This means someone else dropped this page from LRU | |
869 | * So, it will be freed or putback to LRU again. There is | |
870 | * nothing to do here. | |
871 | */ | |
872 | } | |
873 | ||
0ec3b74c | 874 | if (was_unevictable && !is_unevictable) |
bbfd28ee | 875 | count_vm_event(UNEVICTABLE_PGRESCUED); |
0ec3b74c | 876 | else if (!was_unevictable && is_unevictable) |
bbfd28ee LS |
877 | count_vm_event(UNEVICTABLE_PGCULLED); |
878 | ||
894bc310 LS |
879 | put_page(page); /* drop ref from isolate */ |
880 | } | |
881 | ||
dfc8d636 JW |
882 | enum page_references { |
883 | PAGEREF_RECLAIM, | |
884 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 885 | PAGEREF_KEEP, |
dfc8d636 JW |
886 | PAGEREF_ACTIVATE, |
887 | }; | |
888 | ||
889 | static enum page_references page_check_references(struct page *page, | |
890 | struct scan_control *sc) | |
891 | { | |
64574746 | 892 | int referenced_ptes, referenced_page; |
dfc8d636 | 893 | unsigned long vm_flags; |
dfc8d636 | 894 | |
c3ac9a8a JW |
895 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
896 | &vm_flags); | |
64574746 | 897 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 898 | |
dfc8d636 JW |
899 | /* |
900 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
901 | * move the page to the unevictable list. | |
902 | */ | |
903 | if (vm_flags & VM_LOCKED) | |
904 | return PAGEREF_RECLAIM; | |
905 | ||
64574746 | 906 | if (referenced_ptes) { |
e4898273 | 907 | if (PageSwapBacked(page)) |
64574746 JW |
908 | return PAGEREF_ACTIVATE; |
909 | /* | |
910 | * All mapped pages start out with page table | |
911 | * references from the instantiating fault, so we need | |
912 | * to look twice if a mapped file page is used more | |
913 | * than once. | |
914 | * | |
915 | * Mark it and spare it for another trip around the | |
916 | * inactive list. Another page table reference will | |
917 | * lead to its activation. | |
918 | * | |
919 | * Note: the mark is set for activated pages as well | |
920 | * so that recently deactivated but used pages are | |
921 | * quickly recovered. | |
922 | */ | |
923 | SetPageReferenced(page); | |
924 | ||
34dbc67a | 925 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
926 | return PAGEREF_ACTIVATE; |
927 | ||
c909e993 KK |
928 | /* |
929 | * Activate file-backed executable pages after first usage. | |
930 | */ | |
931 | if (vm_flags & VM_EXEC) | |
932 | return PAGEREF_ACTIVATE; | |
933 | ||
64574746 JW |
934 | return PAGEREF_KEEP; |
935 | } | |
dfc8d636 JW |
936 | |
937 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 938 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
939 | return PAGEREF_RECLAIM_CLEAN; |
940 | ||
941 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
942 | } |
943 | ||
e2be15f6 MG |
944 | /* Check if a page is dirty or under writeback */ |
945 | static void page_check_dirty_writeback(struct page *page, | |
946 | bool *dirty, bool *writeback) | |
947 | { | |
b4597226 MG |
948 | struct address_space *mapping; |
949 | ||
e2be15f6 MG |
950 | /* |
951 | * Anonymous pages are not handled by flushers and must be written | |
952 | * from reclaim context. Do not stall reclaim based on them | |
953 | */ | |
802a3a92 SL |
954 | if (!page_is_file_cache(page) || |
955 | (PageAnon(page) && !PageSwapBacked(page))) { | |
e2be15f6 MG |
956 | *dirty = false; |
957 | *writeback = false; | |
958 | return; | |
959 | } | |
960 | ||
961 | /* By default assume that the page flags are accurate */ | |
962 | *dirty = PageDirty(page); | |
963 | *writeback = PageWriteback(page); | |
b4597226 MG |
964 | |
965 | /* Verify dirty/writeback state if the filesystem supports it */ | |
966 | if (!page_has_private(page)) | |
967 | return; | |
968 | ||
969 | mapping = page_mapping(page); | |
970 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
971 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
972 | } |
973 | ||
3c710c1a MH |
974 | struct reclaim_stat { |
975 | unsigned nr_dirty; | |
976 | unsigned nr_unqueued_dirty; | |
977 | unsigned nr_congested; | |
978 | unsigned nr_writeback; | |
979 | unsigned nr_immediate; | |
5bccd166 MH |
980 | unsigned nr_activate; |
981 | unsigned nr_ref_keep; | |
982 | unsigned nr_unmap_fail; | |
3c710c1a MH |
983 | }; |
984 | ||
1da177e4 | 985 | /* |
1742f19f | 986 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 987 | */ |
1742f19f | 988 | static unsigned long shrink_page_list(struct list_head *page_list, |
599d0c95 | 989 | struct pglist_data *pgdat, |
f84f6e2b | 990 | struct scan_control *sc, |
02c6de8d | 991 | enum ttu_flags ttu_flags, |
3c710c1a | 992 | struct reclaim_stat *stat, |
02c6de8d | 993 | bool force_reclaim) |
1da177e4 LT |
994 | { |
995 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 996 | LIST_HEAD(free_pages); |
1da177e4 | 997 | int pgactivate = 0; |
3c710c1a MH |
998 | unsigned nr_unqueued_dirty = 0; |
999 | unsigned nr_dirty = 0; | |
1000 | unsigned nr_congested = 0; | |
1001 | unsigned nr_reclaimed = 0; | |
1002 | unsigned nr_writeback = 0; | |
1003 | unsigned nr_immediate = 0; | |
5bccd166 MH |
1004 | unsigned nr_ref_keep = 0; |
1005 | unsigned nr_unmap_fail = 0; | |
1da177e4 LT |
1006 | |
1007 | cond_resched(); | |
1008 | ||
1da177e4 LT |
1009 | while (!list_empty(page_list)) { |
1010 | struct address_space *mapping; | |
1011 | struct page *page; | |
1012 | int may_enter_fs; | |
02c6de8d | 1013 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 1014 | bool dirty, writeback; |
1da177e4 LT |
1015 | |
1016 | cond_resched(); | |
1017 | ||
1018 | page = lru_to_page(page_list); | |
1019 | list_del(&page->lru); | |
1020 | ||
529ae9aa | 1021 | if (!trylock_page(page)) |
1da177e4 LT |
1022 | goto keep; |
1023 | ||
309381fe | 1024 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1025 | |
1026 | sc->nr_scanned++; | |
80e43426 | 1027 | |
39b5f29a | 1028 | if (unlikely(!page_evictable(page))) |
ad6b6704 | 1029 | goto activate_locked; |
894bc310 | 1030 | |
a6dc60f8 | 1031 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
1032 | goto keep_locked; |
1033 | ||
1da177e4 | 1034 | /* Double the slab pressure for mapped and swapcache pages */ |
802a3a92 SL |
1035 | if ((page_mapped(page) || PageSwapCache(page)) && |
1036 | !(PageAnon(page) && !PageSwapBacked(page))) | |
1da177e4 LT |
1037 | sc->nr_scanned++; |
1038 | ||
c661b078 AW |
1039 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
1040 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
1041 | ||
e2be15f6 MG |
1042 | /* |
1043 | * The number of dirty pages determines if a zone is marked | |
1044 | * reclaim_congested which affects wait_iff_congested. kswapd | |
1045 | * will stall and start writing pages if the tail of the LRU | |
1046 | * is all dirty unqueued pages. | |
1047 | */ | |
1048 | page_check_dirty_writeback(page, &dirty, &writeback); | |
1049 | if (dirty || writeback) | |
1050 | nr_dirty++; | |
1051 | ||
1052 | if (dirty && !writeback) | |
1053 | nr_unqueued_dirty++; | |
1054 | ||
d04e8acd MG |
1055 | /* |
1056 | * Treat this page as congested if the underlying BDI is or if | |
1057 | * pages are cycling through the LRU so quickly that the | |
1058 | * pages marked for immediate reclaim are making it to the | |
1059 | * end of the LRU a second time. | |
1060 | */ | |
e2be15f6 | 1061 | mapping = page_mapping(page); |
1da58ee2 | 1062 | if (((dirty || writeback) && mapping && |
703c2708 | 1063 | inode_write_congested(mapping->host)) || |
d04e8acd | 1064 | (writeback && PageReclaim(page))) |
e2be15f6 MG |
1065 | nr_congested++; |
1066 | ||
283aba9f MG |
1067 | /* |
1068 | * If a page at the tail of the LRU is under writeback, there | |
1069 | * are three cases to consider. | |
1070 | * | |
1071 | * 1) If reclaim is encountering an excessive number of pages | |
1072 | * under writeback and this page is both under writeback and | |
1073 | * PageReclaim then it indicates that pages are being queued | |
1074 | * for IO but are being recycled through the LRU before the | |
1075 | * IO can complete. Waiting on the page itself risks an | |
1076 | * indefinite stall if it is impossible to writeback the | |
1077 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
1078 | * note that the LRU is being scanned too quickly and the |
1079 | * caller can stall after page list has been processed. | |
283aba9f | 1080 | * |
97c9341f | 1081 | * 2) Global or new memcg reclaim encounters a page that is |
ecf5fc6e MH |
1082 | * not marked for immediate reclaim, or the caller does not |
1083 | * have __GFP_FS (or __GFP_IO if it's simply going to swap, | |
1084 | * not to fs). In this case mark the page for immediate | |
97c9341f | 1085 | * reclaim and continue scanning. |
283aba9f | 1086 | * |
ecf5fc6e MH |
1087 | * Require may_enter_fs because we would wait on fs, which |
1088 | * may not have submitted IO yet. And the loop driver might | |
283aba9f MG |
1089 | * enter reclaim, and deadlock if it waits on a page for |
1090 | * which it is needed to do the write (loop masks off | |
1091 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
1092 | * would probably show more reasons. | |
1093 | * | |
7fadc820 | 1094 | * 3) Legacy memcg encounters a page that is already marked |
283aba9f MG |
1095 | * PageReclaim. memcg does not have any dirty pages |
1096 | * throttling so we could easily OOM just because too many | |
1097 | * pages are in writeback and there is nothing else to | |
1098 | * reclaim. Wait for the writeback to complete. | |
c55e8d03 JW |
1099 | * |
1100 | * In cases 1) and 2) we activate the pages to get them out of | |
1101 | * the way while we continue scanning for clean pages on the | |
1102 | * inactive list and refilling from the active list. The | |
1103 | * observation here is that waiting for disk writes is more | |
1104 | * expensive than potentially causing reloads down the line. | |
1105 | * Since they're marked for immediate reclaim, they won't put | |
1106 | * memory pressure on the cache working set any longer than it | |
1107 | * takes to write them to disk. | |
283aba9f | 1108 | */ |
c661b078 | 1109 | if (PageWriteback(page)) { |
283aba9f MG |
1110 | /* Case 1 above */ |
1111 | if (current_is_kswapd() && | |
1112 | PageReclaim(page) && | |
599d0c95 | 1113 | test_bit(PGDAT_WRITEBACK, &pgdat->flags)) { |
b1a6f21e | 1114 | nr_immediate++; |
c55e8d03 | 1115 | goto activate_locked; |
283aba9f MG |
1116 | |
1117 | /* Case 2 above */ | |
97c9341f | 1118 | } else if (sane_reclaim(sc) || |
ecf5fc6e | 1119 | !PageReclaim(page) || !may_enter_fs) { |
c3b94f44 HD |
1120 | /* |
1121 | * This is slightly racy - end_page_writeback() | |
1122 | * might have just cleared PageReclaim, then | |
1123 | * setting PageReclaim here end up interpreted | |
1124 | * as PageReadahead - but that does not matter | |
1125 | * enough to care. What we do want is for this | |
1126 | * page to have PageReclaim set next time memcg | |
1127 | * reclaim reaches the tests above, so it will | |
1128 | * then wait_on_page_writeback() to avoid OOM; | |
1129 | * and it's also appropriate in global reclaim. | |
1130 | */ | |
1131 | SetPageReclaim(page); | |
e62e384e | 1132 | nr_writeback++; |
c55e8d03 | 1133 | goto activate_locked; |
283aba9f MG |
1134 | |
1135 | /* Case 3 above */ | |
1136 | } else { | |
7fadc820 | 1137 | unlock_page(page); |
283aba9f | 1138 | wait_on_page_writeback(page); |
7fadc820 HD |
1139 | /* then go back and try same page again */ |
1140 | list_add_tail(&page->lru, page_list); | |
1141 | continue; | |
e62e384e | 1142 | } |
c661b078 | 1143 | } |
1da177e4 | 1144 | |
02c6de8d MK |
1145 | if (!force_reclaim) |
1146 | references = page_check_references(page, sc); | |
1147 | ||
dfc8d636 JW |
1148 | switch (references) { |
1149 | case PAGEREF_ACTIVATE: | |
1da177e4 | 1150 | goto activate_locked; |
64574746 | 1151 | case PAGEREF_KEEP: |
5bccd166 | 1152 | nr_ref_keep++; |
64574746 | 1153 | goto keep_locked; |
dfc8d636 JW |
1154 | case PAGEREF_RECLAIM: |
1155 | case PAGEREF_RECLAIM_CLEAN: | |
1156 | ; /* try to reclaim the page below */ | |
1157 | } | |
1da177e4 | 1158 | |
1da177e4 LT |
1159 | /* |
1160 | * Anonymous process memory has backing store? | |
1161 | * Try to allocate it some swap space here. | |
802a3a92 | 1162 | * Lazyfree page could be freed directly |
1da177e4 | 1163 | */ |
bd4c82c2 HY |
1164 | if (PageAnon(page) && PageSwapBacked(page)) { |
1165 | if (!PageSwapCache(page)) { | |
1166 | if (!(sc->gfp_mask & __GFP_IO)) | |
1167 | goto keep_locked; | |
1168 | if (PageTransHuge(page)) { | |
1169 | /* cannot split THP, skip it */ | |
1170 | if (!can_split_huge_page(page, NULL)) | |
1171 | goto activate_locked; | |
1172 | /* | |
1173 | * Split pages without a PMD map right | |
1174 | * away. Chances are some or all of the | |
1175 | * tail pages can be freed without IO. | |
1176 | */ | |
1177 | if (!compound_mapcount(page) && | |
1178 | split_huge_page_to_list(page, | |
1179 | page_list)) | |
1180 | goto activate_locked; | |
1181 | } | |
1182 | if (!add_to_swap(page)) { | |
1183 | if (!PageTransHuge(page)) | |
1184 | goto activate_locked; | |
1185 | /* Fallback to swap normal pages */ | |
1186 | if (split_huge_page_to_list(page, | |
1187 | page_list)) | |
1188 | goto activate_locked; | |
fe490cc0 HY |
1189 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
1190 | count_vm_event(THP_SWPOUT_FALLBACK); | |
1191 | #endif | |
bd4c82c2 HY |
1192 | if (!add_to_swap(page)) |
1193 | goto activate_locked; | |
1194 | } | |
0f074658 | 1195 | |
bd4c82c2 | 1196 | may_enter_fs = 1; |
1da177e4 | 1197 | |
bd4c82c2 HY |
1198 | /* Adding to swap updated mapping */ |
1199 | mapping = page_mapping(page); | |
1200 | } | |
7751b2da KS |
1201 | } else if (unlikely(PageTransHuge(page))) { |
1202 | /* Split file THP */ | |
1203 | if (split_huge_page_to_list(page, page_list)) | |
1204 | goto keep_locked; | |
e2be15f6 | 1205 | } |
1da177e4 LT |
1206 | |
1207 | /* | |
1208 | * The page is mapped into the page tables of one or more | |
1209 | * processes. Try to unmap it here. | |
1210 | */ | |
802a3a92 | 1211 | if (page_mapped(page)) { |
bd4c82c2 HY |
1212 | enum ttu_flags flags = ttu_flags | TTU_BATCH_FLUSH; |
1213 | ||
1214 | if (unlikely(PageTransHuge(page))) | |
1215 | flags |= TTU_SPLIT_HUGE_PMD; | |
1216 | if (!try_to_unmap(page, flags)) { | |
5bccd166 | 1217 | nr_unmap_fail++; |
1da177e4 | 1218 | goto activate_locked; |
1da177e4 LT |
1219 | } |
1220 | } | |
1221 | ||
1222 | if (PageDirty(page)) { | |
ee72886d | 1223 | /* |
4eda4823 JW |
1224 | * Only kswapd can writeback filesystem pages |
1225 | * to avoid risk of stack overflow. But avoid | |
1226 | * injecting inefficient single-page IO into | |
1227 | * flusher writeback as much as possible: only | |
1228 | * write pages when we've encountered many | |
1229 | * dirty pages, and when we've already scanned | |
1230 | * the rest of the LRU for clean pages and see | |
1231 | * the same dirty pages again (PageReclaim). | |
ee72886d | 1232 | */ |
f84f6e2b | 1233 | if (page_is_file_cache(page) && |
4eda4823 JW |
1234 | (!current_is_kswapd() || !PageReclaim(page) || |
1235 | !test_bit(PGDAT_DIRTY, &pgdat->flags))) { | |
49ea7eb6 MG |
1236 | /* |
1237 | * Immediately reclaim when written back. | |
1238 | * Similar in principal to deactivate_page() | |
1239 | * except we already have the page isolated | |
1240 | * and know it's dirty | |
1241 | */ | |
c4a25635 | 1242 | inc_node_page_state(page, NR_VMSCAN_IMMEDIATE); |
49ea7eb6 MG |
1243 | SetPageReclaim(page); |
1244 | ||
c55e8d03 | 1245 | goto activate_locked; |
ee72886d MG |
1246 | } |
1247 | ||
dfc8d636 | 1248 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 1249 | goto keep_locked; |
4dd4b920 | 1250 | if (!may_enter_fs) |
1da177e4 | 1251 | goto keep_locked; |
52a8363e | 1252 | if (!sc->may_writepage) |
1da177e4 LT |
1253 | goto keep_locked; |
1254 | ||
d950c947 MG |
1255 | /* |
1256 | * Page is dirty. Flush the TLB if a writable entry | |
1257 | * potentially exists to avoid CPU writes after IO | |
1258 | * starts and then write it out here. | |
1259 | */ | |
1260 | try_to_unmap_flush_dirty(); | |
7d3579e8 | 1261 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1262 | case PAGE_KEEP: |
1263 | goto keep_locked; | |
1264 | case PAGE_ACTIVATE: | |
1265 | goto activate_locked; | |
1266 | case PAGE_SUCCESS: | |
7d3579e8 | 1267 | if (PageWriteback(page)) |
41ac1999 | 1268 | goto keep; |
7d3579e8 | 1269 | if (PageDirty(page)) |
1da177e4 | 1270 | goto keep; |
7d3579e8 | 1271 | |
1da177e4 LT |
1272 | /* |
1273 | * A synchronous write - probably a ramdisk. Go | |
1274 | * ahead and try to reclaim the page. | |
1275 | */ | |
529ae9aa | 1276 | if (!trylock_page(page)) |
1da177e4 LT |
1277 | goto keep; |
1278 | if (PageDirty(page) || PageWriteback(page)) | |
1279 | goto keep_locked; | |
1280 | mapping = page_mapping(page); | |
1281 | case PAGE_CLEAN: | |
1282 | ; /* try to free the page below */ | |
1283 | } | |
1284 | } | |
1285 | ||
1286 | /* | |
1287 | * If the page has buffers, try to free the buffer mappings | |
1288 | * associated with this page. If we succeed we try to free | |
1289 | * the page as well. | |
1290 | * | |
1291 | * We do this even if the page is PageDirty(). | |
1292 | * try_to_release_page() does not perform I/O, but it is | |
1293 | * possible for a page to have PageDirty set, but it is actually | |
1294 | * clean (all its buffers are clean). This happens if the | |
1295 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1296 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1297 | * try_to_release_page() will discover that cleanness and will |
1298 | * drop the buffers and mark the page clean - it can be freed. | |
1299 | * | |
1300 | * Rarely, pages can have buffers and no ->mapping. These are | |
1301 | * the pages which were not successfully invalidated in | |
1302 | * truncate_complete_page(). We try to drop those buffers here | |
1303 | * and if that worked, and the page is no longer mapped into | |
1304 | * process address space (page_count == 1) it can be freed. | |
1305 | * Otherwise, leave the page on the LRU so it is swappable. | |
1306 | */ | |
266cf658 | 1307 | if (page_has_private(page)) { |
1da177e4 LT |
1308 | if (!try_to_release_page(page, sc->gfp_mask)) |
1309 | goto activate_locked; | |
e286781d NP |
1310 | if (!mapping && page_count(page) == 1) { |
1311 | unlock_page(page); | |
1312 | if (put_page_testzero(page)) | |
1313 | goto free_it; | |
1314 | else { | |
1315 | /* | |
1316 | * rare race with speculative reference. | |
1317 | * the speculative reference will free | |
1318 | * this page shortly, so we may | |
1319 | * increment nr_reclaimed here (and | |
1320 | * leave it off the LRU). | |
1321 | */ | |
1322 | nr_reclaimed++; | |
1323 | continue; | |
1324 | } | |
1325 | } | |
1da177e4 LT |
1326 | } |
1327 | ||
802a3a92 SL |
1328 | if (PageAnon(page) && !PageSwapBacked(page)) { |
1329 | /* follow __remove_mapping for reference */ | |
1330 | if (!page_ref_freeze(page, 1)) | |
1331 | goto keep_locked; | |
1332 | if (PageDirty(page)) { | |
1333 | page_ref_unfreeze(page, 1); | |
1334 | goto keep_locked; | |
1335 | } | |
1da177e4 | 1336 | |
802a3a92 | 1337 | count_vm_event(PGLAZYFREED); |
2262185c | 1338 | count_memcg_page_event(page, PGLAZYFREED); |
802a3a92 SL |
1339 | } else if (!mapping || !__remove_mapping(mapping, page, true)) |
1340 | goto keep_locked; | |
a978d6f5 NP |
1341 | /* |
1342 | * At this point, we have no other references and there is | |
1343 | * no way to pick any more up (removed from LRU, removed | |
1344 | * from pagecache). Can use non-atomic bitops now (and | |
1345 | * we obviously don't have to worry about waking up a process | |
1346 | * waiting on the page lock, because there are no references. | |
1347 | */ | |
48c935ad | 1348 | __ClearPageLocked(page); |
e286781d | 1349 | free_it: |
05ff5137 | 1350 | nr_reclaimed++; |
abe4c3b5 MG |
1351 | |
1352 | /* | |
1353 | * Is there need to periodically free_page_list? It would | |
1354 | * appear not as the counts should be low | |
1355 | */ | |
bd4c82c2 HY |
1356 | if (unlikely(PageTransHuge(page))) { |
1357 | mem_cgroup_uncharge(page); | |
1358 | (*get_compound_page_dtor(page))(page); | |
1359 | } else | |
1360 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1361 | continue; |
1362 | ||
1363 | activate_locked: | |
68a22394 | 1364 | /* Not a candidate for swapping, so reclaim swap space. */ |
ad6b6704 MK |
1365 | if (PageSwapCache(page) && (mem_cgroup_swap_full(page) || |
1366 | PageMlocked(page))) | |
a2c43eed | 1367 | try_to_free_swap(page); |
309381fe | 1368 | VM_BUG_ON_PAGE(PageActive(page), page); |
ad6b6704 MK |
1369 | if (!PageMlocked(page)) { |
1370 | SetPageActive(page); | |
1371 | pgactivate++; | |
2262185c | 1372 | count_memcg_page_event(page, PGACTIVATE); |
ad6b6704 | 1373 | } |
1da177e4 LT |
1374 | keep_locked: |
1375 | unlock_page(page); | |
1376 | keep: | |
1377 | list_add(&page->lru, &ret_pages); | |
309381fe | 1378 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1379 | } |
abe4c3b5 | 1380 | |
747db954 | 1381 | mem_cgroup_uncharge_list(&free_pages); |
72b252ae | 1382 | try_to_unmap_flush(); |
2d4894b5 | 1383 | free_unref_page_list(&free_pages); |
abe4c3b5 | 1384 | |
1da177e4 | 1385 | list_splice(&ret_pages, page_list); |
f8891e5e | 1386 | count_vm_events(PGACTIVATE, pgactivate); |
0a31bc97 | 1387 | |
3c710c1a MH |
1388 | if (stat) { |
1389 | stat->nr_dirty = nr_dirty; | |
1390 | stat->nr_congested = nr_congested; | |
1391 | stat->nr_unqueued_dirty = nr_unqueued_dirty; | |
1392 | stat->nr_writeback = nr_writeback; | |
1393 | stat->nr_immediate = nr_immediate; | |
5bccd166 MH |
1394 | stat->nr_activate = pgactivate; |
1395 | stat->nr_ref_keep = nr_ref_keep; | |
1396 | stat->nr_unmap_fail = nr_unmap_fail; | |
3c710c1a | 1397 | } |
05ff5137 | 1398 | return nr_reclaimed; |
1da177e4 LT |
1399 | } |
1400 | ||
02c6de8d MK |
1401 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1402 | struct list_head *page_list) | |
1403 | { | |
1404 | struct scan_control sc = { | |
1405 | .gfp_mask = GFP_KERNEL, | |
1406 | .priority = DEF_PRIORITY, | |
1407 | .may_unmap = 1, | |
1408 | }; | |
3c710c1a | 1409 | unsigned long ret; |
02c6de8d MK |
1410 | struct page *page, *next; |
1411 | LIST_HEAD(clean_pages); | |
1412 | ||
1413 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e | 1414 | if (page_is_file_cache(page) && !PageDirty(page) && |
7a2853cc | 1415 | !__PageMovable(page) && !PageUnevictable(page)) { |
02c6de8d MK |
1416 | ClearPageActive(page); |
1417 | list_move(&page->lru, &clean_pages); | |
1418 | } | |
1419 | } | |
1420 | ||
599d0c95 | 1421 | ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, |
a128ca71 | 1422 | TTU_IGNORE_ACCESS, NULL, true); |
02c6de8d | 1423 | list_splice(&clean_pages, page_list); |
599d0c95 | 1424 | mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); |
02c6de8d MK |
1425 | return ret; |
1426 | } | |
1427 | ||
5ad333eb AW |
1428 | /* |
1429 | * Attempt to remove the specified page from its LRU. Only take this page | |
1430 | * if it is of the appropriate PageActive status. Pages which are being | |
1431 | * freed elsewhere are also ignored. | |
1432 | * | |
1433 | * page: page to consider | |
1434 | * mode: one of the LRU isolation modes defined above | |
1435 | * | |
1436 | * returns 0 on success, -ve errno on failure. | |
1437 | */ | |
f3fd4a61 | 1438 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1439 | { |
1440 | int ret = -EINVAL; | |
1441 | ||
1442 | /* Only take pages on the LRU. */ | |
1443 | if (!PageLRU(page)) | |
1444 | return ret; | |
1445 | ||
e46a2879 MK |
1446 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1447 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1448 | return ret; |
1449 | ||
5ad333eb | 1450 | ret = -EBUSY; |
08e552c6 | 1451 | |
c8244935 MG |
1452 | /* |
1453 | * To minimise LRU disruption, the caller can indicate that it only | |
1454 | * wants to isolate pages it will be able to operate on without | |
1455 | * blocking - clean pages for the most part. | |
1456 | * | |
c8244935 MG |
1457 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages |
1458 | * that it is possible to migrate without blocking | |
1459 | */ | |
1276ad68 | 1460 | if (mode & ISOLATE_ASYNC_MIGRATE) { |
c8244935 MG |
1461 | /* All the caller can do on PageWriteback is block */ |
1462 | if (PageWriteback(page)) | |
1463 | return ret; | |
1464 | ||
1465 | if (PageDirty(page)) { | |
1466 | struct address_space *mapping; | |
de82176c | 1467 | bool migrate_dirty; |
c8244935 | 1468 | |
c8244935 MG |
1469 | /* |
1470 | * Only pages without mappings or that have a | |
1471 | * ->migratepage callback are possible to migrate | |
de82176c MG |
1472 | * without blocking. However, we can be racing with |
1473 | * truncation so it's necessary to lock the page | |
1474 | * to stabilise the mapping as truncation holds | |
1475 | * the page lock until after the page is removed | |
1476 | * from the page cache. | |
c8244935 | 1477 | */ |
de82176c MG |
1478 | if (!trylock_page(page)) |
1479 | return ret; | |
1480 | ||
c8244935 | 1481 | mapping = page_mapping(page); |
6018a9e3 | 1482 | migrate_dirty = !mapping || mapping->a_ops->migratepage; |
de82176c MG |
1483 | unlock_page(page); |
1484 | if (!migrate_dirty) | |
c8244935 MG |
1485 | return ret; |
1486 | } | |
1487 | } | |
39deaf85 | 1488 | |
f80c0673 MK |
1489 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1490 | return ret; | |
1491 | ||
5ad333eb AW |
1492 | if (likely(get_page_unless_zero(page))) { |
1493 | /* | |
1494 | * Be careful not to clear PageLRU until after we're | |
1495 | * sure the page is not being freed elsewhere -- the | |
1496 | * page release code relies on it. | |
1497 | */ | |
1498 | ClearPageLRU(page); | |
1499 | ret = 0; | |
1500 | } | |
1501 | ||
1502 | return ret; | |
1503 | } | |
1504 | ||
7ee36a14 MG |
1505 | |
1506 | /* | |
1507 | * Update LRU sizes after isolating pages. The LRU size updates must | |
1508 | * be complete before mem_cgroup_update_lru_size due to a santity check. | |
1509 | */ | |
1510 | static __always_inline void update_lru_sizes(struct lruvec *lruvec, | |
b4536f0c | 1511 | enum lru_list lru, unsigned long *nr_zone_taken) |
7ee36a14 | 1512 | { |
7ee36a14 MG |
1513 | int zid; |
1514 | ||
7ee36a14 MG |
1515 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1516 | if (!nr_zone_taken[zid]) | |
1517 | continue; | |
1518 | ||
1519 | __update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); | |
7ee36a14 | 1520 | #ifdef CONFIG_MEMCG |
b4536f0c | 1521 | mem_cgroup_update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); |
7ee36a14 | 1522 | #endif |
b4536f0c MH |
1523 | } |
1524 | ||
7ee36a14 MG |
1525 | } |
1526 | ||
1da177e4 | 1527 | /* |
a52633d8 | 1528 | * zone_lru_lock is heavily contended. Some of the functions that |
1da177e4 LT |
1529 | * shrink the lists perform better by taking out a batch of pages |
1530 | * and working on them outside the LRU lock. | |
1531 | * | |
1532 | * For pagecache intensive workloads, this function is the hottest | |
1533 | * spot in the kernel (apart from copy_*_user functions). | |
1534 | * | |
1535 | * Appropriate locks must be held before calling this function. | |
1536 | * | |
791b48b6 | 1537 | * @nr_to_scan: The number of eligible pages to look through on the list. |
5dc35979 | 1538 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1539 | * @dst: The temp list to put pages on to. |
f626012d | 1540 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1541 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1542 | * @mode: One of the LRU isolation modes |
3cb99451 | 1543 | * @lru: LRU list id for isolating |
1da177e4 LT |
1544 | * |
1545 | * returns how many pages were moved onto *@dst. | |
1546 | */ | |
69e05944 | 1547 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1548 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1549 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1550 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1551 | { |
75b00af7 | 1552 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1553 | unsigned long nr_taken = 0; |
599d0c95 | 1554 | unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; |
7cc30fcf | 1555 | unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; |
3db65812 | 1556 | unsigned long skipped = 0; |
791b48b6 | 1557 | unsigned long scan, total_scan, nr_pages; |
b2e18757 | 1558 | LIST_HEAD(pages_skipped); |
1da177e4 | 1559 | |
791b48b6 MK |
1560 | scan = 0; |
1561 | for (total_scan = 0; | |
1562 | scan < nr_to_scan && nr_taken < nr_to_scan && !list_empty(src); | |
1563 | total_scan++) { | |
5ad333eb | 1564 | struct page *page; |
5ad333eb | 1565 | |
1da177e4 LT |
1566 | page = lru_to_page(src); |
1567 | prefetchw_prev_lru_page(page, src, flags); | |
1568 | ||
309381fe | 1569 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1570 | |
b2e18757 MG |
1571 | if (page_zonenum(page) > sc->reclaim_idx) { |
1572 | list_move(&page->lru, &pages_skipped); | |
7cc30fcf | 1573 | nr_skipped[page_zonenum(page)]++; |
b2e18757 MG |
1574 | continue; |
1575 | } | |
1576 | ||
791b48b6 MK |
1577 | /* |
1578 | * Do not count skipped pages because that makes the function | |
1579 | * return with no isolated pages if the LRU mostly contains | |
1580 | * ineligible pages. This causes the VM to not reclaim any | |
1581 | * pages, triggering a premature OOM. | |
1582 | */ | |
1583 | scan++; | |
f3fd4a61 | 1584 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1585 | case 0: |
599d0c95 MG |
1586 | nr_pages = hpage_nr_pages(page); |
1587 | nr_taken += nr_pages; | |
1588 | nr_zone_taken[page_zonenum(page)] += nr_pages; | |
5ad333eb | 1589 | list_move(&page->lru, dst); |
5ad333eb AW |
1590 | break; |
1591 | ||
1592 | case -EBUSY: | |
1593 | /* else it is being freed elsewhere */ | |
1594 | list_move(&page->lru, src); | |
1595 | continue; | |
46453a6e | 1596 | |
5ad333eb AW |
1597 | default: |
1598 | BUG(); | |
1599 | } | |
1da177e4 LT |
1600 | } |
1601 | ||
b2e18757 MG |
1602 | /* |
1603 | * Splice any skipped pages to the start of the LRU list. Note that | |
1604 | * this disrupts the LRU order when reclaiming for lower zones but | |
1605 | * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX | |
1606 | * scanning would soon rescan the same pages to skip and put the | |
1607 | * system at risk of premature OOM. | |
1608 | */ | |
7cc30fcf MG |
1609 | if (!list_empty(&pages_skipped)) { |
1610 | int zid; | |
1611 | ||
3db65812 | 1612 | list_splice(&pages_skipped, src); |
7cc30fcf MG |
1613 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1614 | if (!nr_skipped[zid]) | |
1615 | continue; | |
1616 | ||
1617 | __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); | |
1265e3a6 | 1618 | skipped += nr_skipped[zid]; |
7cc30fcf MG |
1619 | } |
1620 | } | |
791b48b6 | 1621 | *nr_scanned = total_scan; |
1265e3a6 | 1622 | trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, |
791b48b6 | 1623 | total_scan, skipped, nr_taken, mode, lru); |
b4536f0c | 1624 | update_lru_sizes(lruvec, lru, nr_zone_taken); |
1da177e4 LT |
1625 | return nr_taken; |
1626 | } | |
1627 | ||
62695a84 NP |
1628 | /** |
1629 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1630 | * @page: page to isolate from its LRU list | |
1631 | * | |
1632 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1633 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1634 | * | |
1635 | * Returns 0 if the page was removed from an LRU list. | |
1636 | * Returns -EBUSY if the page was not on an LRU list. | |
1637 | * | |
1638 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1639 | * the active list, it will have PageActive set. If it was found on |
1640 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1641 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1642 | * |
1643 | * The vmstat statistic corresponding to the list on which the page was | |
1644 | * found will be decremented. | |
1645 | * | |
1646 | * Restrictions: | |
1647 | * (1) Must be called with an elevated refcount on the page. This is a | |
1648 | * fundamentnal difference from isolate_lru_pages (which is called | |
1649 | * without a stable reference). | |
1650 | * (2) the lru_lock must not be held. | |
1651 | * (3) interrupts must be enabled. | |
1652 | */ | |
1653 | int isolate_lru_page(struct page *page) | |
1654 | { | |
1655 | int ret = -EBUSY; | |
1656 | ||
309381fe | 1657 | VM_BUG_ON_PAGE(!page_count(page), page); |
cf2a82ee | 1658 | WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); |
0c917313 | 1659 | |
62695a84 NP |
1660 | if (PageLRU(page)) { |
1661 | struct zone *zone = page_zone(page); | |
fa9add64 | 1662 | struct lruvec *lruvec; |
62695a84 | 1663 | |
a52633d8 | 1664 | spin_lock_irq(zone_lru_lock(zone)); |
599d0c95 | 1665 | lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); |
0c917313 | 1666 | if (PageLRU(page)) { |
894bc310 | 1667 | int lru = page_lru(page); |
0c917313 | 1668 | get_page(page); |
62695a84 | 1669 | ClearPageLRU(page); |
fa9add64 HD |
1670 | del_page_from_lru_list(page, lruvec, lru); |
1671 | ret = 0; | |
62695a84 | 1672 | } |
a52633d8 | 1673 | spin_unlock_irq(zone_lru_lock(zone)); |
62695a84 NP |
1674 | } |
1675 | return ret; | |
1676 | } | |
1677 | ||
35cd7815 | 1678 | /* |
d37dd5dc FW |
1679 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1680 | * then get resheduled. When there are massive number of tasks doing page | |
1681 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1682 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1683 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 | 1684 | */ |
599d0c95 | 1685 | static int too_many_isolated(struct pglist_data *pgdat, int file, |
35cd7815 RR |
1686 | struct scan_control *sc) |
1687 | { | |
1688 | unsigned long inactive, isolated; | |
1689 | ||
1690 | if (current_is_kswapd()) | |
1691 | return 0; | |
1692 | ||
97c9341f | 1693 | if (!sane_reclaim(sc)) |
35cd7815 RR |
1694 | return 0; |
1695 | ||
1696 | if (file) { | |
599d0c95 MG |
1697 | inactive = node_page_state(pgdat, NR_INACTIVE_FILE); |
1698 | isolated = node_page_state(pgdat, NR_ISOLATED_FILE); | |
35cd7815 | 1699 | } else { |
599d0c95 MG |
1700 | inactive = node_page_state(pgdat, NR_INACTIVE_ANON); |
1701 | isolated = node_page_state(pgdat, NR_ISOLATED_ANON); | |
35cd7815 RR |
1702 | } |
1703 | ||
3cf23841 FW |
1704 | /* |
1705 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1706 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1707 | * deadlock. | |
1708 | */ | |
d0164adc | 1709 | if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS)) |
3cf23841 FW |
1710 | inactive >>= 3; |
1711 | ||
35cd7815 RR |
1712 | return isolated > inactive; |
1713 | } | |
1714 | ||
66635629 | 1715 | static noinline_for_stack void |
75b00af7 | 1716 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1717 | { |
27ac81d8 | 1718 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
599d0c95 | 1719 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3f79768f | 1720 | LIST_HEAD(pages_to_free); |
66635629 | 1721 | |
66635629 MG |
1722 | /* |
1723 | * Put back any unfreeable pages. | |
1724 | */ | |
66635629 | 1725 | while (!list_empty(page_list)) { |
3f79768f | 1726 | struct page *page = lru_to_page(page_list); |
66635629 | 1727 | int lru; |
3f79768f | 1728 | |
309381fe | 1729 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1730 | list_del(&page->lru); |
39b5f29a | 1731 | if (unlikely(!page_evictable(page))) { |
599d0c95 | 1732 | spin_unlock_irq(&pgdat->lru_lock); |
66635629 | 1733 | putback_lru_page(page); |
599d0c95 | 1734 | spin_lock_irq(&pgdat->lru_lock); |
66635629 MG |
1735 | continue; |
1736 | } | |
fa9add64 | 1737 | |
599d0c95 | 1738 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
fa9add64 | 1739 | |
7a608572 | 1740 | SetPageLRU(page); |
66635629 | 1741 | lru = page_lru(page); |
fa9add64 HD |
1742 | add_page_to_lru_list(page, lruvec, lru); |
1743 | ||
66635629 MG |
1744 | if (is_active_lru(lru)) { |
1745 | int file = is_file_lru(lru); | |
9992af10 RR |
1746 | int numpages = hpage_nr_pages(page); |
1747 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1748 | } |
2bcf8879 HD |
1749 | if (put_page_testzero(page)) { |
1750 | __ClearPageLRU(page); | |
1751 | __ClearPageActive(page); | |
fa9add64 | 1752 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1753 | |
1754 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 1755 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 1756 | mem_cgroup_uncharge(page); |
2bcf8879 | 1757 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 1758 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
1759 | } else |
1760 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1761 | } |
1762 | } | |
66635629 | 1763 | |
3f79768f HD |
1764 | /* |
1765 | * To save our caller's stack, now use input list for pages to free. | |
1766 | */ | |
1767 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1768 | } |
1769 | ||
399ba0b9 N |
1770 | /* |
1771 | * If a kernel thread (such as nfsd for loop-back mounts) services | |
1772 | * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. | |
1773 | * In that case we should only throttle if the backing device it is | |
1774 | * writing to is congested. In other cases it is safe to throttle. | |
1775 | */ | |
1776 | static int current_may_throttle(void) | |
1777 | { | |
1778 | return !(current->flags & PF_LESS_THROTTLE) || | |
1779 | current->backing_dev_info == NULL || | |
1780 | bdi_write_congested(current->backing_dev_info); | |
1781 | } | |
1782 | ||
1da177e4 | 1783 | /* |
b2e18757 | 1784 | * shrink_inactive_list() is a helper for shrink_node(). It returns the number |
1742f19f | 1785 | * of reclaimed pages |
1da177e4 | 1786 | */ |
66635629 | 1787 | static noinline_for_stack unsigned long |
1a93be0e | 1788 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1789 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1790 | { |
1791 | LIST_HEAD(page_list); | |
e247dbce | 1792 | unsigned long nr_scanned; |
05ff5137 | 1793 | unsigned long nr_reclaimed = 0; |
e247dbce | 1794 | unsigned long nr_taken; |
3c710c1a | 1795 | struct reclaim_stat stat = {}; |
f3fd4a61 | 1796 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1797 | int file = is_file_lru(lru); |
599d0c95 | 1798 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1a93be0e | 1799 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
db73ee0d | 1800 | bool stalled = false; |
78dc583d | 1801 | |
599d0c95 | 1802 | while (unlikely(too_many_isolated(pgdat, file, sc))) { |
db73ee0d MH |
1803 | if (stalled) |
1804 | return 0; | |
1805 | ||
1806 | /* wait a bit for the reclaimer. */ | |
1807 | msleep(100); | |
1808 | stalled = true; | |
35cd7815 RR |
1809 | |
1810 | /* We are about to die and free our memory. Return now. */ | |
1811 | if (fatal_signal_pending(current)) | |
1812 | return SWAP_CLUSTER_MAX; | |
1813 | } | |
1814 | ||
1da177e4 | 1815 | lru_add_drain(); |
f80c0673 MK |
1816 | |
1817 | if (!sc->may_unmap) | |
61317289 | 1818 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1819 | |
599d0c95 | 1820 | spin_lock_irq(&pgdat->lru_lock); |
b35ea17b | 1821 | |
5dc35979 KK |
1822 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1823 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc | 1824 | |
599d0c95 | 1825 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
9d5e6a9f | 1826 | reclaim_stat->recent_scanned[file] += nr_taken; |
95d918fc | 1827 | |
2262185c RG |
1828 | if (current_is_kswapd()) { |
1829 | if (global_reclaim(sc)) | |
599d0c95 | 1830 | __count_vm_events(PGSCAN_KSWAPD, nr_scanned); |
2262185c RG |
1831 | count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD, |
1832 | nr_scanned); | |
1833 | } else { | |
1834 | if (global_reclaim(sc)) | |
599d0c95 | 1835 | __count_vm_events(PGSCAN_DIRECT, nr_scanned); |
2262185c RG |
1836 | count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT, |
1837 | nr_scanned); | |
e247dbce | 1838 | } |
599d0c95 | 1839 | spin_unlock_irq(&pgdat->lru_lock); |
b35ea17b | 1840 | |
d563c050 | 1841 | if (nr_taken == 0) |
66635629 | 1842 | return 0; |
5ad333eb | 1843 | |
a128ca71 | 1844 | nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, 0, |
3c710c1a | 1845 | &stat, false); |
c661b078 | 1846 | |
599d0c95 | 1847 | spin_lock_irq(&pgdat->lru_lock); |
3f79768f | 1848 | |
2262185c RG |
1849 | if (current_is_kswapd()) { |
1850 | if (global_reclaim(sc)) | |
599d0c95 | 1851 | __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); |
2262185c RG |
1852 | count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD, |
1853 | nr_reclaimed); | |
1854 | } else { | |
1855 | if (global_reclaim(sc)) | |
599d0c95 | 1856 | __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); |
2262185c RG |
1857 | count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT, |
1858 | nr_reclaimed); | |
904249aa | 1859 | } |
a74609fa | 1860 | |
27ac81d8 | 1861 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1862 | |
599d0c95 | 1863 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f | 1864 | |
599d0c95 | 1865 | spin_unlock_irq(&pgdat->lru_lock); |
3f79768f | 1866 | |
747db954 | 1867 | mem_cgroup_uncharge_list(&page_list); |
2d4894b5 | 1868 | free_unref_page_list(&page_list); |
e11da5b4 | 1869 | |
92df3a72 MG |
1870 | /* |
1871 | * If reclaim is isolating dirty pages under writeback, it implies | |
1872 | * that the long-lived page allocation rate is exceeding the page | |
1873 | * laundering rate. Either the global limits are not being effective | |
1874 | * at throttling processes due to the page distribution throughout | |
1875 | * zones or there is heavy usage of a slow backing device. The | |
1876 | * only option is to throttle from reclaim context which is not ideal | |
1877 | * as there is no guarantee the dirtying process is throttled in the | |
1878 | * same way balance_dirty_pages() manages. | |
1879 | * | |
8e950282 MG |
1880 | * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number |
1881 | * of pages under pages flagged for immediate reclaim and stall if any | |
1882 | * are encountered in the nr_immediate check below. | |
92df3a72 | 1883 | */ |
3c710c1a | 1884 | if (stat.nr_writeback && stat.nr_writeback == nr_taken) |
599d0c95 | 1885 | set_bit(PGDAT_WRITEBACK, &pgdat->flags); |
92df3a72 | 1886 | |
a8aa42fd AR |
1887 | /* |
1888 | * If dirty pages are scanned that are not queued for IO, it | |
1889 | * implies that flushers are not doing their job. This can | |
1890 | * happen when memory pressure pushes dirty pages to the end of | |
1891 | * the LRU before the dirty limits are breached and the dirty | |
1892 | * data has expired. It can also happen when the proportion of | |
1893 | * dirty pages grows not through writes but through memory | |
1894 | * pressure reclaiming all the clean cache. And in some cases, | |
1895 | * the flushers simply cannot keep up with the allocation | |
1896 | * rate. Nudge the flusher threads in case they are asleep. | |
1897 | */ | |
1898 | if (stat.nr_unqueued_dirty == nr_taken) | |
1899 | wakeup_flusher_threads(WB_REASON_VMSCAN); | |
1900 | ||
d43006d5 | 1901 | /* |
97c9341f TH |
1902 | * Legacy memcg will stall in page writeback so avoid forcibly |
1903 | * stalling here. | |
d43006d5 | 1904 | */ |
97c9341f | 1905 | if (sane_reclaim(sc)) { |
8e950282 MG |
1906 | /* |
1907 | * Tag a zone as congested if all the dirty pages scanned were | |
1908 | * backed by a congested BDI and wait_iff_congested will stall. | |
1909 | */ | |
3c710c1a | 1910 | if (stat.nr_dirty && stat.nr_dirty == stat.nr_congested) |
599d0c95 | 1911 | set_bit(PGDAT_CONGESTED, &pgdat->flags); |
8e950282 | 1912 | |
a8aa42fd AR |
1913 | /* Allow kswapd to start writing pages during reclaim. */ |
1914 | if (stat.nr_unqueued_dirty == nr_taken) | |
599d0c95 | 1915 | set_bit(PGDAT_DIRTY, &pgdat->flags); |
b1a6f21e MG |
1916 | |
1917 | /* | |
b738d764 LT |
1918 | * If kswapd scans pages marked marked for immediate |
1919 | * reclaim and under writeback (nr_immediate), it implies | |
1920 | * that pages are cycling through the LRU faster than | |
b1a6f21e MG |
1921 | * they are written so also forcibly stall. |
1922 | */ | |
3c710c1a | 1923 | if (stat.nr_immediate && current_may_throttle()) |
b1a6f21e | 1924 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
e2be15f6 | 1925 | } |
d43006d5 | 1926 | |
8e950282 MG |
1927 | /* |
1928 | * Stall direct reclaim for IO completions if underlying BDIs or zone | |
1929 | * is congested. Allow kswapd to continue until it starts encountering | |
1930 | * unqueued dirty pages or cycling through the LRU too quickly. | |
1931 | */ | |
399ba0b9 N |
1932 | if (!sc->hibernation_mode && !current_is_kswapd() && |
1933 | current_may_throttle()) | |
599d0c95 | 1934 | wait_iff_congested(pgdat, BLK_RW_ASYNC, HZ/10); |
8e950282 | 1935 | |
599d0c95 MG |
1936 | trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, |
1937 | nr_scanned, nr_reclaimed, | |
5bccd166 MH |
1938 | stat.nr_dirty, stat.nr_writeback, |
1939 | stat.nr_congested, stat.nr_immediate, | |
1940 | stat.nr_activate, stat.nr_ref_keep, | |
1941 | stat.nr_unmap_fail, | |
ba5e9579 | 1942 | sc->priority, file); |
05ff5137 | 1943 | return nr_reclaimed; |
1da177e4 LT |
1944 | } |
1945 | ||
1946 | /* | |
1947 | * This moves pages from the active list to the inactive list. | |
1948 | * | |
1949 | * We move them the other way if the page is referenced by one or more | |
1950 | * processes, from rmap. | |
1951 | * | |
1952 | * If the pages are mostly unmapped, the processing is fast and it is | |
a52633d8 | 1953 | * appropriate to hold zone_lru_lock across the whole operation. But if |
1da177e4 | 1954 | * the pages are mapped, the processing is slow (page_referenced()) so we |
a52633d8 | 1955 | * should drop zone_lru_lock around each page. It's impossible to balance |
1da177e4 LT |
1956 | * this, so instead we remove the pages from the LRU while processing them. |
1957 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1958 | * nobody will play with that bit on a non-LRU page. | |
1959 | * | |
0139aa7b | 1960 | * The downside is that we have to touch page->_refcount against each page. |
1da177e4 | 1961 | * But we had to alter page->flags anyway. |
9d998b4f MH |
1962 | * |
1963 | * Returns the number of pages moved to the given lru. | |
1da177e4 | 1964 | */ |
1cfb419b | 1965 | |
9d998b4f | 1966 | static unsigned move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 1967 | struct list_head *list, |
2bcf8879 | 1968 | struct list_head *pages_to_free, |
3eb4140f WF |
1969 | enum lru_list lru) |
1970 | { | |
599d0c95 | 1971 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3eb4140f | 1972 | struct page *page; |
fa9add64 | 1973 | int nr_pages; |
9d998b4f | 1974 | int nr_moved = 0; |
3eb4140f | 1975 | |
3eb4140f WF |
1976 | while (!list_empty(list)) { |
1977 | page = lru_to_page(list); | |
599d0c95 | 1978 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
3eb4140f | 1979 | |
309381fe | 1980 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
1981 | SetPageLRU(page); |
1982 | ||
fa9add64 | 1983 | nr_pages = hpage_nr_pages(page); |
599d0c95 | 1984 | update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); |
925b7673 | 1985 | list_move(&page->lru, &lruvec->lists[lru]); |
3eb4140f | 1986 | |
2bcf8879 HD |
1987 | if (put_page_testzero(page)) { |
1988 | __ClearPageLRU(page); | |
1989 | __ClearPageActive(page); | |
fa9add64 | 1990 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1991 | |
1992 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 1993 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 1994 | mem_cgroup_uncharge(page); |
2bcf8879 | 1995 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 1996 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
1997 | } else |
1998 | list_add(&page->lru, pages_to_free); | |
9d998b4f MH |
1999 | } else { |
2000 | nr_moved += nr_pages; | |
3eb4140f WF |
2001 | } |
2002 | } | |
9d5e6a9f | 2003 | |
2262185c | 2004 | if (!is_active_lru(lru)) { |
f0958906 | 2005 | __count_vm_events(PGDEACTIVATE, nr_moved); |
2262185c RG |
2006 | count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, |
2007 | nr_moved); | |
2008 | } | |
9d998b4f MH |
2009 | |
2010 | return nr_moved; | |
3eb4140f | 2011 | } |
1cfb419b | 2012 | |
f626012d | 2013 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 2014 | struct lruvec *lruvec, |
f16015fb | 2015 | struct scan_control *sc, |
9e3b2f8c | 2016 | enum lru_list lru) |
1da177e4 | 2017 | { |
44c241f1 | 2018 | unsigned long nr_taken; |
f626012d | 2019 | unsigned long nr_scanned; |
6fe6b7e3 | 2020 | unsigned long vm_flags; |
1da177e4 | 2021 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 2022 | LIST_HEAD(l_active); |
b69408e8 | 2023 | LIST_HEAD(l_inactive); |
1da177e4 | 2024 | struct page *page; |
1a93be0e | 2025 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
9d998b4f MH |
2026 | unsigned nr_deactivate, nr_activate; |
2027 | unsigned nr_rotated = 0; | |
f3fd4a61 | 2028 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 2029 | int file = is_file_lru(lru); |
599d0c95 | 2030 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1da177e4 LT |
2031 | |
2032 | lru_add_drain(); | |
f80c0673 MK |
2033 | |
2034 | if (!sc->may_unmap) | |
61317289 | 2035 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 2036 | |
599d0c95 | 2037 | spin_lock_irq(&pgdat->lru_lock); |
925b7673 | 2038 | |
5dc35979 KK |
2039 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
2040 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 2041 | |
599d0c95 | 2042 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
b7c46d15 | 2043 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 2044 | |
599d0c95 | 2045 | __count_vm_events(PGREFILL, nr_scanned); |
2262185c | 2046 | count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned); |
9d5e6a9f | 2047 | |
599d0c95 | 2048 | spin_unlock_irq(&pgdat->lru_lock); |
1da177e4 | 2049 | |
1da177e4 LT |
2050 | while (!list_empty(&l_hold)) { |
2051 | cond_resched(); | |
2052 | page = lru_to_page(&l_hold); | |
2053 | list_del(&page->lru); | |
7e9cd484 | 2054 | |
39b5f29a | 2055 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
2056 | putback_lru_page(page); |
2057 | continue; | |
2058 | } | |
2059 | ||
cc715d99 MG |
2060 | if (unlikely(buffer_heads_over_limit)) { |
2061 | if (page_has_private(page) && trylock_page(page)) { | |
2062 | if (page_has_private(page)) | |
2063 | try_to_release_page(page, 0); | |
2064 | unlock_page(page); | |
2065 | } | |
2066 | } | |
2067 | ||
c3ac9a8a JW |
2068 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
2069 | &vm_flags)) { | |
9992af10 | 2070 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
2071 | /* |
2072 | * Identify referenced, file-backed active pages and | |
2073 | * give them one more trip around the active list. So | |
2074 | * that executable code get better chances to stay in | |
2075 | * memory under moderate memory pressure. Anon pages | |
2076 | * are not likely to be evicted by use-once streaming | |
2077 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
2078 | * so we ignore them here. | |
2079 | */ | |
41e20983 | 2080 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
2081 | list_add(&page->lru, &l_active); |
2082 | continue; | |
2083 | } | |
2084 | } | |
7e9cd484 | 2085 | |
5205e56e | 2086 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
2087 | list_add(&page->lru, &l_inactive); |
2088 | } | |
2089 | ||
b555749a | 2090 | /* |
8cab4754 | 2091 | * Move pages back to the lru list. |
b555749a | 2092 | */ |
599d0c95 | 2093 | spin_lock_irq(&pgdat->lru_lock); |
556adecb | 2094 | /* |
8cab4754 WF |
2095 | * Count referenced pages from currently used mappings as rotated, |
2096 | * even though only some of them are actually re-activated. This | |
2097 | * helps balance scan pressure between file and anonymous pages in | |
7c0db9e9 | 2098 | * get_scan_count. |
7e9cd484 | 2099 | */ |
b7c46d15 | 2100 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 2101 | |
9d998b4f MH |
2102 | nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
2103 | nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
599d0c95 MG |
2104 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
2105 | spin_unlock_irq(&pgdat->lru_lock); | |
2bcf8879 | 2106 | |
747db954 | 2107 | mem_cgroup_uncharge_list(&l_hold); |
2d4894b5 | 2108 | free_unref_page_list(&l_hold); |
9d998b4f MH |
2109 | trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate, |
2110 | nr_deactivate, nr_rotated, sc->priority, file); | |
1da177e4 LT |
2111 | } |
2112 | ||
59dc76b0 RR |
2113 | /* |
2114 | * The inactive anon list should be small enough that the VM never has | |
2115 | * to do too much work. | |
14797e23 | 2116 | * |
59dc76b0 RR |
2117 | * The inactive file list should be small enough to leave most memory |
2118 | * to the established workingset on the scan-resistant active list, | |
2119 | * but large enough to avoid thrashing the aggregate readahead window. | |
56e49d21 | 2120 | * |
59dc76b0 RR |
2121 | * Both inactive lists should also be large enough that each inactive |
2122 | * page has a chance to be referenced again before it is reclaimed. | |
56e49d21 | 2123 | * |
2a2e4885 JW |
2124 | * If that fails and refaulting is observed, the inactive list grows. |
2125 | * | |
59dc76b0 | 2126 | * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages |
3a50d14d | 2127 | * on this LRU, maintained by the pageout code. An inactive_ratio |
59dc76b0 | 2128 | * of 3 means 3:1 or 25% of the pages are kept on the inactive list. |
56e49d21 | 2129 | * |
59dc76b0 RR |
2130 | * total target max |
2131 | * memory ratio inactive | |
2132 | * ------------------------------------- | |
2133 | * 10MB 1 5MB | |
2134 | * 100MB 1 50MB | |
2135 | * 1GB 3 250MB | |
2136 | * 10GB 10 0.9GB | |
2137 | * 100GB 31 3GB | |
2138 | * 1TB 101 10GB | |
2139 | * 10TB 320 32GB | |
56e49d21 | 2140 | */ |
f8d1a311 | 2141 | static bool inactive_list_is_low(struct lruvec *lruvec, bool file, |
b13b8376 | 2142 | struct scan_control *sc, bool trace) |
56e49d21 | 2143 | { |
fd538803 | 2144 | enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE; |
2a2e4885 JW |
2145 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
2146 | enum lru_list inactive_lru = file * LRU_FILE; | |
2147 | unsigned long inactive, active; | |
2148 | unsigned long inactive_ratio; | |
2149 | unsigned long refaults; | |
59dc76b0 | 2150 | unsigned long gb; |
e3790144 | 2151 | |
59dc76b0 RR |
2152 | /* |
2153 | * If we don't have swap space, anonymous page deactivation | |
2154 | * is pointless. | |
2155 | */ | |
2156 | if (!file && !total_swap_pages) | |
2157 | return false; | |
56e49d21 | 2158 | |
fd538803 MH |
2159 | inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx); |
2160 | active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx); | |
f8d1a311 | 2161 | |
2a2e4885 JW |
2162 | /* |
2163 | * When refaults are being observed, it means a new workingset | |
2164 | * is being established. Disable active list protection to get | |
2165 | * rid of the stale workingset quickly. | |
2166 | */ | |
ccfc2495 | 2167 | refaults = lruvec_page_state(lruvec, WORKINGSET_ACTIVATE); |
b13b8376 | 2168 | if (file && lruvec->refaults != refaults) { |
2a2e4885 JW |
2169 | inactive_ratio = 0; |
2170 | } else { | |
2171 | gb = (inactive + active) >> (30 - PAGE_SHIFT); | |
2172 | if (gb) | |
2173 | inactive_ratio = int_sqrt(10 * gb); | |
2174 | else | |
2175 | inactive_ratio = 1; | |
2176 | } | |
59dc76b0 | 2177 | |
b13b8376 | 2178 | if (trace) |
2a2e4885 JW |
2179 | trace_mm_vmscan_inactive_list_is_low(pgdat->node_id, sc->reclaim_idx, |
2180 | lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive, | |
2181 | lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active, | |
2182 | inactive_ratio, file); | |
fd538803 | 2183 | |
59dc76b0 | 2184 | return inactive * inactive_ratio < active; |
b39415b2 RR |
2185 | } |
2186 | ||
4f98a2fe | 2187 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
ccfc2495 | 2188 | struct lruvec *lruvec, struct scan_control *sc) |
b69408e8 | 2189 | { |
b39415b2 | 2190 | if (is_active_lru(lru)) { |
ccfc2495 | 2191 | if (inactive_list_is_low(lruvec, is_file_lru(lru), sc, true)) |
1a93be0e | 2192 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
2193 | return 0; |
2194 | } | |
2195 | ||
1a93be0e | 2196 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
2197 | } |
2198 | ||
9a265114 JW |
2199 | enum scan_balance { |
2200 | SCAN_EQUAL, | |
2201 | SCAN_FRACT, | |
2202 | SCAN_ANON, | |
2203 | SCAN_FILE, | |
2204 | }; | |
2205 | ||
4f98a2fe RR |
2206 | /* |
2207 | * Determine how aggressively the anon and file LRU lists should be | |
2208 | * scanned. The relative value of each set of LRU lists is determined | |
2209 | * by looking at the fraction of the pages scanned we did rotate back | |
2210 | * onto the active list instead of evict. | |
2211 | * | |
be7bd59d WL |
2212 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
2213 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 2214 | */ |
33377678 | 2215 | static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, |
6b4f7799 JW |
2216 | struct scan_control *sc, unsigned long *nr, |
2217 | unsigned long *lru_pages) | |
4f98a2fe | 2218 | { |
33377678 | 2219 | int swappiness = mem_cgroup_swappiness(memcg); |
9a265114 JW |
2220 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
2221 | u64 fraction[2]; | |
2222 | u64 denominator = 0; /* gcc */ | |
599d0c95 | 2223 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
4f98a2fe | 2224 | unsigned long anon_prio, file_prio; |
9a265114 | 2225 | enum scan_balance scan_balance; |
0bf1457f | 2226 | unsigned long anon, file; |
4f98a2fe | 2227 | unsigned long ap, fp; |
4111304d | 2228 | enum lru_list lru; |
76a33fc3 SL |
2229 | |
2230 | /* If we have no swap space, do not bother scanning anon pages. */ | |
d8b38438 | 2231 | if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { |
9a265114 | 2232 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
2233 | goto out; |
2234 | } | |
4f98a2fe | 2235 | |
10316b31 JW |
2236 | /* |
2237 | * Global reclaim will swap to prevent OOM even with no | |
2238 | * swappiness, but memcg users want to use this knob to | |
2239 | * disable swapping for individual groups completely when | |
2240 | * using the memory controller's swap limit feature would be | |
2241 | * too expensive. | |
2242 | */ | |
02695175 | 2243 | if (!global_reclaim(sc) && !swappiness) { |
9a265114 | 2244 | scan_balance = SCAN_FILE; |
10316b31 JW |
2245 | goto out; |
2246 | } | |
2247 | ||
2248 | /* | |
2249 | * Do not apply any pressure balancing cleverness when the | |
2250 | * system is close to OOM, scan both anon and file equally | |
2251 | * (unless the swappiness setting disagrees with swapping). | |
2252 | */ | |
02695175 | 2253 | if (!sc->priority && swappiness) { |
9a265114 | 2254 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
2255 | goto out; |
2256 | } | |
2257 | ||
62376251 JW |
2258 | /* |
2259 | * Prevent the reclaimer from falling into the cache trap: as | |
2260 | * cache pages start out inactive, every cache fault will tip | |
2261 | * the scan balance towards the file LRU. And as the file LRU | |
2262 | * shrinks, so does the window for rotation from references. | |
2263 | * This means we have a runaway feedback loop where a tiny | |
2264 | * thrashing file LRU becomes infinitely more attractive than | |
2265 | * anon pages. Try to detect this based on file LRU size. | |
2266 | */ | |
2267 | if (global_reclaim(sc)) { | |
599d0c95 MG |
2268 | unsigned long pgdatfile; |
2269 | unsigned long pgdatfree; | |
2270 | int z; | |
2271 | unsigned long total_high_wmark = 0; | |
2ab051e1 | 2272 | |
599d0c95 MG |
2273 | pgdatfree = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); |
2274 | pgdatfile = node_page_state(pgdat, NR_ACTIVE_FILE) + | |
2275 | node_page_state(pgdat, NR_INACTIVE_FILE); | |
2276 | ||
2277 | for (z = 0; z < MAX_NR_ZONES; z++) { | |
2278 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2279 | if (!managed_zone(zone)) |
599d0c95 MG |
2280 | continue; |
2281 | ||
2282 | total_high_wmark += high_wmark_pages(zone); | |
2283 | } | |
62376251 | 2284 | |
599d0c95 | 2285 | if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) { |
06226226 DR |
2286 | /* |
2287 | * Force SCAN_ANON if there are enough inactive | |
2288 | * anonymous pages on the LRU in eligible zones. | |
2289 | * Otherwise, the small LRU gets thrashed. | |
2290 | */ | |
ccfc2495 | 2291 | if (!inactive_list_is_low(lruvec, false, sc, false) && |
06226226 DR |
2292 | lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, sc->reclaim_idx) |
2293 | >> sc->priority) { | |
2294 | scan_balance = SCAN_ANON; | |
2295 | goto out; | |
2296 | } | |
62376251 JW |
2297 | } |
2298 | } | |
2299 | ||
7c5bd705 | 2300 | /* |
316bda0e VD |
2301 | * If there is enough inactive page cache, i.e. if the size of the |
2302 | * inactive list is greater than that of the active list *and* the | |
2303 | * inactive list actually has some pages to scan on this priority, we | |
2304 | * do not reclaim anything from the anonymous working set right now. | |
2305 | * Without the second condition we could end up never scanning an | |
2306 | * lruvec even if it has plenty of old anonymous pages unless the | |
2307 | * system is under heavy pressure. | |
7c5bd705 | 2308 | */ |
ccfc2495 | 2309 | if (!inactive_list_is_low(lruvec, true, sc, false) && |
71ab6cfe | 2310 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) { |
9a265114 | 2311 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
2312 | goto out; |
2313 | } | |
2314 | ||
9a265114 JW |
2315 | scan_balance = SCAN_FRACT; |
2316 | ||
58c37f6e KM |
2317 | /* |
2318 | * With swappiness at 100, anonymous and file have the same priority. | |
2319 | * This scanning priority is essentially the inverse of IO cost. | |
2320 | */ | |
02695175 | 2321 | anon_prio = swappiness; |
75b00af7 | 2322 | file_prio = 200 - anon_prio; |
58c37f6e | 2323 | |
4f98a2fe RR |
2324 | /* |
2325 | * OK, so we have swap space and a fair amount of page cache | |
2326 | * pages. We use the recently rotated / recently scanned | |
2327 | * ratios to determine how valuable each cache is. | |
2328 | * | |
2329 | * Because workloads change over time (and to avoid overflow) | |
2330 | * we keep these statistics as a floating average, which ends | |
2331 | * up weighing recent references more than old ones. | |
2332 | * | |
2333 | * anon in [0], file in [1] | |
2334 | */ | |
2ab051e1 | 2335 | |
fd538803 MH |
2336 | anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) + |
2337 | lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES); | |
2338 | file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + | |
2339 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); | |
2ab051e1 | 2340 | |
599d0c95 | 2341 | spin_lock_irq(&pgdat->lru_lock); |
6e901571 | 2342 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
2343 | reclaim_stat->recent_scanned[0] /= 2; |
2344 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
2345 | } |
2346 | ||
6e901571 | 2347 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
2348 | reclaim_stat->recent_scanned[1] /= 2; |
2349 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
2350 | } |
2351 | ||
4f98a2fe | 2352 | /* |
00d8089c RR |
2353 | * The amount of pressure on anon vs file pages is inversely |
2354 | * proportional to the fraction of recently scanned pages on | |
2355 | * each list that were recently referenced and in active use. | |
4f98a2fe | 2356 | */ |
fe35004f | 2357 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 2358 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 2359 | |
fe35004f | 2360 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 2361 | fp /= reclaim_stat->recent_rotated[1] + 1; |
599d0c95 | 2362 | spin_unlock_irq(&pgdat->lru_lock); |
4f98a2fe | 2363 | |
76a33fc3 SL |
2364 | fraction[0] = ap; |
2365 | fraction[1] = fp; | |
2366 | denominator = ap + fp + 1; | |
2367 | out: | |
688035f7 JW |
2368 | *lru_pages = 0; |
2369 | for_each_evictable_lru(lru) { | |
2370 | int file = is_file_lru(lru); | |
2371 | unsigned long size; | |
2372 | unsigned long scan; | |
6b4f7799 | 2373 | |
688035f7 JW |
2374 | size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); |
2375 | scan = size >> sc->priority; | |
2376 | /* | |
2377 | * If the cgroup's already been deleted, make sure to | |
2378 | * scrape out the remaining cache. | |
2379 | */ | |
2380 | if (!scan && !mem_cgroup_online(memcg)) | |
2381 | scan = min(size, SWAP_CLUSTER_MAX); | |
6b4f7799 | 2382 | |
688035f7 JW |
2383 | switch (scan_balance) { |
2384 | case SCAN_EQUAL: | |
2385 | /* Scan lists relative to size */ | |
2386 | break; | |
2387 | case SCAN_FRACT: | |
9a265114 | 2388 | /* |
688035f7 JW |
2389 | * Scan types proportional to swappiness and |
2390 | * their relative recent reclaim efficiency. | |
aea35b21 RG |
2391 | * Make sure we don't miss the last page |
2392 | * because of a round-off error. | |
9a265114 | 2393 | */ |
aea35b21 RG |
2394 | scan = DIV64_U64_ROUND_UP(scan * fraction[file], |
2395 | denominator); | |
688035f7 JW |
2396 | break; |
2397 | case SCAN_FILE: | |
2398 | case SCAN_ANON: | |
2399 | /* Scan one type exclusively */ | |
2400 | if ((scan_balance == SCAN_FILE) != file) { | |
2401 | size = 0; | |
2402 | scan = 0; | |
2403 | } | |
2404 | break; | |
2405 | default: | |
2406 | /* Look ma, no brain */ | |
2407 | BUG(); | |
9a265114 | 2408 | } |
688035f7 JW |
2409 | |
2410 | *lru_pages += size; | |
2411 | nr[lru] = scan; | |
76a33fc3 | 2412 | } |
6e08a369 | 2413 | } |
4f98a2fe | 2414 | |
9b4f98cd | 2415 | /* |
a9dd0a83 | 2416 | * This is a basic per-node page freer. Used by both kswapd and direct reclaim. |
9b4f98cd | 2417 | */ |
a9dd0a83 | 2418 | static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, |
33377678 | 2419 | struct scan_control *sc, unsigned long *lru_pages) |
9b4f98cd | 2420 | { |
ef8f2327 | 2421 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
9b4f98cd | 2422 | unsigned long nr[NR_LRU_LISTS]; |
e82e0561 | 2423 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2424 | unsigned long nr_to_scan; |
2425 | enum lru_list lru; | |
2426 | unsigned long nr_reclaimed = 0; | |
2427 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2428 | struct blk_plug plug; | |
1a501907 | 2429 | bool scan_adjusted; |
9b4f98cd | 2430 | |
33377678 | 2431 | get_scan_count(lruvec, memcg, sc, nr, lru_pages); |
9b4f98cd | 2432 | |
e82e0561 MG |
2433 | /* Record the original scan target for proportional adjustments later */ |
2434 | memcpy(targets, nr, sizeof(nr)); | |
2435 | ||
1a501907 MG |
2436 | /* |
2437 | * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal | |
2438 | * event that can occur when there is little memory pressure e.g. | |
2439 | * multiple streaming readers/writers. Hence, we do not abort scanning | |
2440 | * when the requested number of pages are reclaimed when scanning at | |
2441 | * DEF_PRIORITY on the assumption that the fact we are direct | |
2442 | * reclaiming implies that kswapd is not keeping up and it is best to | |
2443 | * do a batch of work at once. For memcg reclaim one check is made to | |
2444 | * abort proportional reclaim if either the file or anon lru has already | |
2445 | * dropped to zero at the first pass. | |
2446 | */ | |
2447 | scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && | |
2448 | sc->priority == DEF_PRIORITY); | |
2449 | ||
9b4f98cd JW |
2450 | blk_start_plug(&plug); |
2451 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2452 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2453 | unsigned long nr_anon, nr_file, percentage; |
2454 | unsigned long nr_scanned; | |
2455 | ||
9b4f98cd JW |
2456 | for_each_evictable_lru(lru) { |
2457 | if (nr[lru]) { | |
2458 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2459 | nr[lru] -= nr_to_scan; | |
2460 | ||
2461 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
ccfc2495 | 2462 | lruvec, sc); |
9b4f98cd JW |
2463 | } |
2464 | } | |
e82e0561 | 2465 | |
bd041733 MH |
2466 | cond_resched(); |
2467 | ||
e82e0561 MG |
2468 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) |
2469 | continue; | |
2470 | ||
e82e0561 MG |
2471 | /* |
2472 | * For kswapd and memcg, reclaim at least the number of pages | |
1a501907 | 2473 | * requested. Ensure that the anon and file LRUs are scanned |
e82e0561 MG |
2474 | * proportionally what was requested by get_scan_count(). We |
2475 | * stop reclaiming one LRU and reduce the amount scanning | |
2476 | * proportional to the original scan target. | |
2477 | */ | |
2478 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2479 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2480 | ||
1a501907 MG |
2481 | /* |
2482 | * It's just vindictive to attack the larger once the smaller | |
2483 | * has gone to zero. And given the way we stop scanning the | |
2484 | * smaller below, this makes sure that we only make one nudge | |
2485 | * towards proportionality once we've got nr_to_reclaim. | |
2486 | */ | |
2487 | if (!nr_file || !nr_anon) | |
2488 | break; | |
2489 | ||
e82e0561 MG |
2490 | if (nr_file > nr_anon) { |
2491 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2492 | targets[LRU_ACTIVE_ANON] + 1; | |
2493 | lru = LRU_BASE; | |
2494 | percentage = nr_anon * 100 / scan_target; | |
2495 | } else { | |
2496 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2497 | targets[LRU_ACTIVE_FILE] + 1; | |
2498 | lru = LRU_FILE; | |
2499 | percentage = nr_file * 100 / scan_target; | |
2500 | } | |
2501 | ||
2502 | /* Stop scanning the smaller of the LRU */ | |
2503 | nr[lru] = 0; | |
2504 | nr[lru + LRU_ACTIVE] = 0; | |
2505 | ||
2506 | /* | |
2507 | * Recalculate the other LRU scan count based on its original | |
2508 | * scan target and the percentage scanning already complete | |
2509 | */ | |
2510 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2511 | nr_scanned = targets[lru] - nr[lru]; | |
2512 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2513 | nr[lru] -= min(nr[lru], nr_scanned); | |
2514 | ||
2515 | lru += LRU_ACTIVE; | |
2516 | nr_scanned = targets[lru] - nr[lru]; | |
2517 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2518 | nr[lru] -= min(nr[lru], nr_scanned); | |
2519 | ||
2520 | scan_adjusted = true; | |
9b4f98cd JW |
2521 | } |
2522 | blk_finish_plug(&plug); | |
2523 | sc->nr_reclaimed += nr_reclaimed; | |
2524 | ||
2525 | /* | |
2526 | * Even if we did not try to evict anon pages at all, we want to | |
2527 | * rebalance the anon lru active/inactive ratio. | |
2528 | */ | |
ccfc2495 | 2529 | if (inactive_list_is_low(lruvec, false, sc, true)) |
9b4f98cd JW |
2530 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
2531 | sc, LRU_ACTIVE_ANON); | |
9b4f98cd JW |
2532 | } |
2533 | ||
23b9da55 | 2534 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2535 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2536 | { |
d84da3f9 | 2537 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2538 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2539 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2540 | return true; |
2541 | ||
2542 | return false; | |
2543 | } | |
2544 | ||
3e7d3449 | 2545 | /* |
23b9da55 MG |
2546 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2547 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2548 | * true if more pages should be reclaimed such that when the page allocator | |
2549 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2550 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2551 | */ |
a9dd0a83 | 2552 | static inline bool should_continue_reclaim(struct pglist_data *pgdat, |
3e7d3449 MG |
2553 | unsigned long nr_reclaimed, |
2554 | unsigned long nr_scanned, | |
2555 | struct scan_control *sc) | |
2556 | { | |
2557 | unsigned long pages_for_compaction; | |
2558 | unsigned long inactive_lru_pages; | |
a9dd0a83 | 2559 | int z; |
3e7d3449 MG |
2560 | |
2561 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2562 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2563 | return false; |
2564 | ||
2876592f | 2565 | /* Consider stopping depending on scan and reclaim activity */ |
dcda9b04 | 2566 | if (sc->gfp_mask & __GFP_RETRY_MAYFAIL) { |
2876592f | 2567 | /* |
dcda9b04 | 2568 | * For __GFP_RETRY_MAYFAIL allocations, stop reclaiming if the |
2876592f MG |
2569 | * full LRU list has been scanned and we are still failing |
2570 | * to reclaim pages. This full LRU scan is potentially | |
dcda9b04 | 2571 | * expensive but a __GFP_RETRY_MAYFAIL caller really wants to succeed |
2876592f MG |
2572 | */ |
2573 | if (!nr_reclaimed && !nr_scanned) | |
2574 | return false; | |
2575 | } else { | |
2576 | /* | |
dcda9b04 | 2577 | * For non-__GFP_RETRY_MAYFAIL allocations which can presumably |
2876592f MG |
2578 | * fail without consequence, stop if we failed to reclaim |
2579 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2580 | * pages that were scanned. This will return to the | |
2581 | * caller faster at the risk reclaim/compaction and | |
2582 | * the resulting allocation attempt fails | |
2583 | */ | |
2584 | if (!nr_reclaimed) | |
2585 | return false; | |
2586 | } | |
3e7d3449 MG |
2587 | |
2588 | /* | |
2589 | * If we have not reclaimed enough pages for compaction and the | |
2590 | * inactive lists are large enough, continue reclaiming | |
2591 | */ | |
9861a62c | 2592 | pages_for_compaction = compact_gap(sc->order); |
a9dd0a83 | 2593 | inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); |
ec8acf20 | 2594 | if (get_nr_swap_pages() > 0) |
a9dd0a83 | 2595 | inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); |
3e7d3449 MG |
2596 | if (sc->nr_reclaimed < pages_for_compaction && |
2597 | inactive_lru_pages > pages_for_compaction) | |
2598 | return true; | |
2599 | ||
2600 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
a9dd0a83 MG |
2601 | for (z = 0; z <= sc->reclaim_idx; z++) { |
2602 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2603 | if (!managed_zone(zone)) |
a9dd0a83 MG |
2604 | continue; |
2605 | ||
2606 | switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) { | |
cf378319 | 2607 | case COMPACT_SUCCESS: |
a9dd0a83 MG |
2608 | case COMPACT_CONTINUE: |
2609 | return false; | |
2610 | default: | |
2611 | /* check next zone */ | |
2612 | ; | |
2613 | } | |
3e7d3449 | 2614 | } |
a9dd0a83 | 2615 | return true; |
3e7d3449 MG |
2616 | } |
2617 | ||
970a39a3 | 2618 | static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) |
1da177e4 | 2619 | { |
cb731d6c | 2620 | struct reclaim_state *reclaim_state = current->reclaim_state; |
f0fdc5e8 | 2621 | unsigned long nr_reclaimed, nr_scanned; |
2344d7e4 | 2622 | bool reclaimable = false; |
1da177e4 | 2623 | |
9b4f98cd JW |
2624 | do { |
2625 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2626 | struct mem_cgroup_reclaim_cookie reclaim = { | |
ef8f2327 | 2627 | .pgdat = pgdat, |
9b4f98cd JW |
2628 | .priority = sc->priority, |
2629 | }; | |
a9dd0a83 | 2630 | unsigned long node_lru_pages = 0; |
694fbc0f | 2631 | struct mem_cgroup *memcg; |
3e7d3449 | 2632 | |
9b4f98cd JW |
2633 | nr_reclaimed = sc->nr_reclaimed; |
2634 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2635 | |
694fbc0f AM |
2636 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2637 | do { | |
6b4f7799 | 2638 | unsigned long lru_pages; |
8e8ae645 | 2639 | unsigned long reclaimed; |
cb731d6c | 2640 | unsigned long scanned; |
5660048c | 2641 | |
241994ed | 2642 | if (mem_cgroup_low(root, memcg)) { |
d6622f63 YX |
2643 | if (!sc->memcg_low_reclaim) { |
2644 | sc->memcg_low_skipped = 1; | |
241994ed | 2645 | continue; |
d6622f63 | 2646 | } |
31176c78 | 2647 | mem_cgroup_event(memcg, MEMCG_LOW); |
241994ed JW |
2648 | } |
2649 | ||
8e8ae645 | 2650 | reclaimed = sc->nr_reclaimed; |
cb731d6c | 2651 | scanned = sc->nr_scanned; |
f9be23d6 | 2652 | |
a9dd0a83 MG |
2653 | shrink_node_memcg(pgdat, memcg, sc, &lru_pages); |
2654 | node_lru_pages += lru_pages; | |
f16015fb | 2655 | |
b5afba29 | 2656 | if (memcg) |
a9dd0a83 | 2657 | shrink_slab(sc->gfp_mask, pgdat->node_id, |
cb731d6c VD |
2658 | memcg, sc->nr_scanned - scanned, |
2659 | lru_pages); | |
2660 | ||
8e8ae645 JW |
2661 | /* Record the group's reclaim efficiency */ |
2662 | vmpressure(sc->gfp_mask, memcg, false, | |
2663 | sc->nr_scanned - scanned, | |
2664 | sc->nr_reclaimed - reclaimed); | |
2665 | ||
9b4f98cd | 2666 | /* |
a394cb8e MH |
2667 | * Direct reclaim and kswapd have to scan all memory |
2668 | * cgroups to fulfill the overall scan target for the | |
a9dd0a83 | 2669 | * node. |
a394cb8e MH |
2670 | * |
2671 | * Limit reclaim, on the other hand, only cares about | |
2672 | * nr_to_reclaim pages to be reclaimed and it will | |
2673 | * retry with decreasing priority if one round over the | |
2674 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2675 | */ |
a394cb8e MH |
2676 | if (!global_reclaim(sc) && |
2677 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2678 | mem_cgroup_iter_break(root, memcg); |
2679 | break; | |
2680 | } | |
241994ed | 2681 | } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); |
70ddf637 | 2682 | |
6b4f7799 JW |
2683 | /* |
2684 | * Shrink the slab caches in the same proportion that | |
2685 | * the eligible LRU pages were scanned. | |
2686 | */ | |
b2e18757 | 2687 | if (global_reclaim(sc)) |
a9dd0a83 | 2688 | shrink_slab(sc->gfp_mask, pgdat->node_id, NULL, |
cb731d6c | 2689 | sc->nr_scanned - nr_scanned, |
a9dd0a83 | 2690 | node_lru_pages); |
cb731d6c VD |
2691 | |
2692 | if (reclaim_state) { | |
2693 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; | |
2694 | reclaim_state->reclaimed_slab = 0; | |
6b4f7799 JW |
2695 | } |
2696 | ||
8e8ae645 JW |
2697 | /* Record the subtree's reclaim efficiency */ |
2698 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, | |
70ddf637 AV |
2699 | sc->nr_scanned - nr_scanned, |
2700 | sc->nr_reclaimed - nr_reclaimed); | |
2701 | ||
2344d7e4 JW |
2702 | if (sc->nr_reclaimed - nr_reclaimed) |
2703 | reclaimable = true; | |
2704 | ||
a9dd0a83 | 2705 | } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, |
9b4f98cd | 2706 | sc->nr_scanned - nr_scanned, sc)); |
2344d7e4 | 2707 | |
c73322d0 JW |
2708 | /* |
2709 | * Kswapd gives up on balancing particular nodes after too | |
2710 | * many failures to reclaim anything from them and goes to | |
2711 | * sleep. On reclaim progress, reset the failure counter. A | |
2712 | * successful direct reclaim run will revive a dormant kswapd. | |
2713 | */ | |
2714 | if (reclaimable) | |
2715 | pgdat->kswapd_failures = 0; | |
2716 | ||
2344d7e4 | 2717 | return reclaimable; |
f16015fb JW |
2718 | } |
2719 | ||
53853e2d | 2720 | /* |
fdd4c614 VB |
2721 | * Returns true if compaction should go ahead for a costly-order request, or |
2722 | * the allocation would already succeed without compaction. Return false if we | |
2723 | * should reclaim first. | |
53853e2d | 2724 | */ |
4f588331 | 2725 | static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) |
fe4b1b24 | 2726 | { |
31483b6a | 2727 | unsigned long watermark; |
fdd4c614 | 2728 | enum compact_result suitable; |
fe4b1b24 | 2729 | |
fdd4c614 VB |
2730 | suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); |
2731 | if (suitable == COMPACT_SUCCESS) | |
2732 | /* Allocation should succeed already. Don't reclaim. */ | |
2733 | return true; | |
2734 | if (suitable == COMPACT_SKIPPED) | |
2735 | /* Compaction cannot yet proceed. Do reclaim. */ | |
2736 | return false; | |
fe4b1b24 | 2737 | |
53853e2d | 2738 | /* |
fdd4c614 VB |
2739 | * Compaction is already possible, but it takes time to run and there |
2740 | * are potentially other callers using the pages just freed. So proceed | |
2741 | * with reclaim to make a buffer of free pages available to give | |
2742 | * compaction a reasonable chance of completing and allocating the page. | |
2743 | * Note that we won't actually reclaim the whole buffer in one attempt | |
2744 | * as the target watermark in should_continue_reclaim() is lower. But if | |
2745 | * we are already above the high+gap watermark, don't reclaim at all. | |
53853e2d | 2746 | */ |
fdd4c614 | 2747 | watermark = high_wmark_pages(zone) + compact_gap(sc->order); |
fe4b1b24 | 2748 | |
fdd4c614 | 2749 | return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); |
fe4b1b24 MG |
2750 | } |
2751 | ||
1da177e4 LT |
2752 | /* |
2753 | * This is the direct reclaim path, for page-allocating processes. We only | |
2754 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2755 | * request. | |
2756 | * | |
1da177e4 LT |
2757 | * If a zone is deemed to be full of pinned pages then just give it a light |
2758 | * scan then give up on it. | |
2759 | */ | |
0a0337e0 | 2760 | static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2761 | { |
dd1a239f | 2762 | struct zoneref *z; |
54a6eb5c | 2763 | struct zone *zone; |
0608f43d AM |
2764 | unsigned long nr_soft_reclaimed; |
2765 | unsigned long nr_soft_scanned; | |
619d0d76 | 2766 | gfp_t orig_mask; |
79dafcdc | 2767 | pg_data_t *last_pgdat = NULL; |
1cfb419b | 2768 | |
cc715d99 MG |
2769 | /* |
2770 | * If the number of buffer_heads in the machine exceeds the maximum | |
2771 | * allowed level, force direct reclaim to scan the highmem zone as | |
2772 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2773 | */ | |
619d0d76 | 2774 | orig_mask = sc->gfp_mask; |
b2e18757 | 2775 | if (buffer_heads_over_limit) { |
cc715d99 | 2776 | sc->gfp_mask |= __GFP_HIGHMEM; |
4f588331 | 2777 | sc->reclaim_idx = gfp_zone(sc->gfp_mask); |
b2e18757 | 2778 | } |
cc715d99 | 2779 | |
d4debc66 | 2780 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
b2e18757 | 2781 | sc->reclaim_idx, sc->nodemask) { |
1cfb419b KH |
2782 | /* |
2783 | * Take care memory controller reclaiming has small influence | |
2784 | * to global LRU. | |
2785 | */ | |
89b5fae5 | 2786 | if (global_reclaim(sc)) { |
344736f2 VD |
2787 | if (!cpuset_zone_allowed(zone, |
2788 | GFP_KERNEL | __GFP_HARDWALL)) | |
1cfb419b | 2789 | continue; |
65ec02cb | 2790 | |
0b06496a JW |
2791 | /* |
2792 | * If we already have plenty of memory free for | |
2793 | * compaction in this zone, don't free any more. | |
2794 | * Even though compaction is invoked for any | |
2795 | * non-zero order, only frequent costly order | |
2796 | * reclamation is disruptive enough to become a | |
2797 | * noticeable problem, like transparent huge | |
2798 | * page allocations. | |
2799 | */ | |
2800 | if (IS_ENABLED(CONFIG_COMPACTION) && | |
2801 | sc->order > PAGE_ALLOC_COSTLY_ORDER && | |
4f588331 | 2802 | compaction_ready(zone, sc)) { |
0b06496a JW |
2803 | sc->compaction_ready = true; |
2804 | continue; | |
e0887c19 | 2805 | } |
0b06496a | 2806 | |
79dafcdc MG |
2807 | /* |
2808 | * Shrink each node in the zonelist once. If the | |
2809 | * zonelist is ordered by zone (not the default) then a | |
2810 | * node may be shrunk multiple times but in that case | |
2811 | * the user prefers lower zones being preserved. | |
2812 | */ | |
2813 | if (zone->zone_pgdat == last_pgdat) | |
2814 | continue; | |
2815 | ||
0608f43d AM |
2816 | /* |
2817 | * This steals pages from memory cgroups over softlimit | |
2818 | * and returns the number of reclaimed pages and | |
2819 | * scanned pages. This works for global memory pressure | |
2820 | * and balancing, not for a memcg's limit. | |
2821 | */ | |
2822 | nr_soft_scanned = 0; | |
ef8f2327 | 2823 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat, |
0608f43d AM |
2824 | sc->order, sc->gfp_mask, |
2825 | &nr_soft_scanned); | |
2826 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2827 | sc->nr_scanned += nr_soft_scanned; | |
ac34a1a3 | 2828 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2829 | } |
408d8544 | 2830 | |
79dafcdc MG |
2831 | /* See comment about same check for global reclaim above */ |
2832 | if (zone->zone_pgdat == last_pgdat) | |
2833 | continue; | |
2834 | last_pgdat = zone->zone_pgdat; | |
970a39a3 | 2835 | shrink_node(zone->zone_pgdat, sc); |
1da177e4 | 2836 | } |
e0c23279 | 2837 | |
619d0d76 WY |
2838 | /* |
2839 | * Restore to original mask to avoid the impact on the caller if we | |
2840 | * promoted it to __GFP_HIGHMEM. | |
2841 | */ | |
2842 | sc->gfp_mask = orig_mask; | |
1da177e4 | 2843 | } |
4f98a2fe | 2844 | |
2a2e4885 JW |
2845 | static void snapshot_refaults(struct mem_cgroup *root_memcg, pg_data_t *pgdat) |
2846 | { | |
2847 | struct mem_cgroup *memcg; | |
2848 | ||
2849 | memcg = mem_cgroup_iter(root_memcg, NULL, NULL); | |
2850 | do { | |
2851 | unsigned long refaults; | |
2852 | struct lruvec *lruvec; | |
2853 | ||
2a2e4885 | 2854 | lruvec = mem_cgroup_lruvec(pgdat, memcg); |
ccfc2495 | 2855 | refaults = lruvec_page_state(lruvec, WORKINGSET_ACTIVATE); |
2a2e4885 JW |
2856 | lruvec->refaults = refaults; |
2857 | } while ((memcg = mem_cgroup_iter(root_memcg, memcg, NULL))); | |
2858 | } | |
2859 | ||
1da177e4 LT |
2860 | /* |
2861 | * This is the main entry point to direct page reclaim. | |
2862 | * | |
2863 | * If a full scan of the inactive list fails to free enough memory then we | |
2864 | * are "out of memory" and something needs to be killed. | |
2865 | * | |
2866 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2867 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2868 | * caller can't do much about. We kick the writeback threads and take explicit |
2869 | * naps in the hope that some of these pages can be written. But if the | |
2870 | * allocating task holds filesystem locks which prevent writeout this might not | |
2871 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2872 | * |
2873 | * returns: 0, if no pages reclaimed | |
2874 | * else, the number of pages reclaimed | |
1da177e4 | 2875 | */ |
dac1d27b | 2876 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
3115cd91 | 2877 | struct scan_control *sc) |
1da177e4 | 2878 | { |
241994ed | 2879 | int initial_priority = sc->priority; |
2a2e4885 JW |
2880 | pg_data_t *last_pgdat; |
2881 | struct zoneref *z; | |
2882 | struct zone *zone; | |
241994ed | 2883 | retry: |
873b4771 KK |
2884 | delayacct_freepages_start(); |
2885 | ||
89b5fae5 | 2886 | if (global_reclaim(sc)) |
7cc30fcf | 2887 | __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); |
1da177e4 | 2888 | |
9e3b2f8c | 2889 | do { |
70ddf637 AV |
2890 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
2891 | sc->priority); | |
66e1707b | 2892 | sc->nr_scanned = 0; |
0a0337e0 | 2893 | shrink_zones(zonelist, sc); |
c6a8a8c5 | 2894 | |
bb21c7ce | 2895 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
0b06496a JW |
2896 | break; |
2897 | ||
2898 | if (sc->compaction_ready) | |
2899 | break; | |
1da177e4 | 2900 | |
0e50ce3b MK |
2901 | /* |
2902 | * If we're getting trouble reclaiming, start doing | |
2903 | * writepage even in laptop mode. | |
2904 | */ | |
2905 | if (sc->priority < DEF_PRIORITY - 2) | |
2906 | sc->may_writepage = 1; | |
0b06496a | 2907 | } while (--sc->priority >= 0); |
bb21c7ce | 2908 | |
2a2e4885 JW |
2909 | last_pgdat = NULL; |
2910 | for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx, | |
2911 | sc->nodemask) { | |
2912 | if (zone->zone_pgdat == last_pgdat) | |
2913 | continue; | |
2914 | last_pgdat = zone->zone_pgdat; | |
2915 | snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat); | |
2916 | } | |
2917 | ||
873b4771 KK |
2918 | delayacct_freepages_end(); |
2919 | ||
bb21c7ce KM |
2920 | if (sc->nr_reclaimed) |
2921 | return sc->nr_reclaimed; | |
2922 | ||
0cee34fd | 2923 | /* Aborted reclaim to try compaction? don't OOM, then */ |
0b06496a | 2924 | if (sc->compaction_ready) |
7335084d MG |
2925 | return 1; |
2926 | ||
241994ed | 2927 | /* Untapped cgroup reserves? Don't OOM, retry. */ |
d6622f63 | 2928 | if (sc->memcg_low_skipped) { |
241994ed | 2929 | sc->priority = initial_priority; |
d6622f63 YX |
2930 | sc->memcg_low_reclaim = 1; |
2931 | sc->memcg_low_skipped = 0; | |
241994ed JW |
2932 | goto retry; |
2933 | } | |
2934 | ||
bb21c7ce | 2935 | return 0; |
1da177e4 LT |
2936 | } |
2937 | ||
c73322d0 | 2938 | static bool allow_direct_reclaim(pg_data_t *pgdat) |
5515061d MG |
2939 | { |
2940 | struct zone *zone; | |
2941 | unsigned long pfmemalloc_reserve = 0; | |
2942 | unsigned long free_pages = 0; | |
2943 | int i; | |
2944 | bool wmark_ok; | |
2945 | ||
c73322d0 JW |
2946 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) |
2947 | return true; | |
2948 | ||
5515061d MG |
2949 | for (i = 0; i <= ZONE_NORMAL; i++) { |
2950 | zone = &pgdat->node_zones[i]; | |
d450abd8 JW |
2951 | if (!managed_zone(zone)) |
2952 | continue; | |
2953 | ||
2954 | if (!zone_reclaimable_pages(zone)) | |
675becce MG |
2955 | continue; |
2956 | ||
5515061d MG |
2957 | pfmemalloc_reserve += min_wmark_pages(zone); |
2958 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
2959 | } | |
2960 | ||
675becce MG |
2961 | /* If there are no reserves (unexpected config) then do not throttle */ |
2962 | if (!pfmemalloc_reserve) | |
2963 | return true; | |
2964 | ||
5515061d MG |
2965 | wmark_ok = free_pages > pfmemalloc_reserve / 2; |
2966 | ||
2967 | /* kswapd must be awake if processes are being throttled */ | |
2968 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
38087d9b | 2969 | pgdat->kswapd_classzone_idx = min(pgdat->kswapd_classzone_idx, |
5515061d MG |
2970 | (enum zone_type)ZONE_NORMAL); |
2971 | wake_up_interruptible(&pgdat->kswapd_wait); | |
2972 | } | |
2973 | ||
2974 | return wmark_ok; | |
2975 | } | |
2976 | ||
2977 | /* | |
2978 | * Throttle direct reclaimers if backing storage is backed by the network | |
2979 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
2980 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
2981 | * when the low watermark is reached. |
2982 | * | |
2983 | * Returns true if a fatal signal was delivered during throttling. If this | |
2984 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 2985 | */ |
50694c28 | 2986 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
2987 | nodemask_t *nodemask) |
2988 | { | |
675becce | 2989 | struct zoneref *z; |
5515061d | 2990 | struct zone *zone; |
675becce | 2991 | pg_data_t *pgdat = NULL; |
5515061d MG |
2992 | |
2993 | /* | |
2994 | * Kernel threads should not be throttled as they may be indirectly | |
2995 | * responsible for cleaning pages necessary for reclaim to make forward | |
2996 | * progress. kjournald for example may enter direct reclaim while | |
2997 | * committing a transaction where throttling it could forcing other | |
2998 | * processes to block on log_wait_commit(). | |
2999 | */ | |
3000 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
3001 | goto out; |
3002 | ||
3003 | /* | |
3004 | * If a fatal signal is pending, this process should not throttle. | |
3005 | * It should return quickly so it can exit and free its memory | |
3006 | */ | |
3007 | if (fatal_signal_pending(current)) | |
3008 | goto out; | |
5515061d | 3009 | |
675becce MG |
3010 | /* |
3011 | * Check if the pfmemalloc reserves are ok by finding the first node | |
3012 | * with a usable ZONE_NORMAL or lower zone. The expectation is that | |
3013 | * GFP_KERNEL will be required for allocating network buffers when | |
3014 | * swapping over the network so ZONE_HIGHMEM is unusable. | |
3015 | * | |
3016 | * Throttling is based on the first usable node and throttled processes | |
3017 | * wait on a queue until kswapd makes progress and wakes them. There | |
3018 | * is an affinity then between processes waking up and where reclaim | |
3019 | * progress has been made assuming the process wakes on the same node. | |
3020 | * More importantly, processes running on remote nodes will not compete | |
3021 | * for remote pfmemalloc reserves and processes on different nodes | |
3022 | * should make reasonable progress. | |
3023 | */ | |
3024 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
17636faa | 3025 | gfp_zone(gfp_mask), nodemask) { |
675becce MG |
3026 | if (zone_idx(zone) > ZONE_NORMAL) |
3027 | continue; | |
3028 | ||
3029 | /* Throttle based on the first usable node */ | |
3030 | pgdat = zone->zone_pgdat; | |
c73322d0 | 3031 | if (allow_direct_reclaim(pgdat)) |
675becce MG |
3032 | goto out; |
3033 | break; | |
3034 | } | |
3035 | ||
3036 | /* If no zone was usable by the allocation flags then do not throttle */ | |
3037 | if (!pgdat) | |
50694c28 | 3038 | goto out; |
5515061d | 3039 | |
68243e76 MG |
3040 | /* Account for the throttling */ |
3041 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
3042 | ||
5515061d MG |
3043 | /* |
3044 | * If the caller cannot enter the filesystem, it's possible that it | |
3045 | * is due to the caller holding an FS lock or performing a journal | |
3046 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
3047 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
3048 | * blocked waiting on the same lock. Instead, throttle for up to a | |
3049 | * second before continuing. | |
3050 | */ | |
3051 | if (!(gfp_mask & __GFP_FS)) { | |
3052 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
c73322d0 | 3053 | allow_direct_reclaim(pgdat), HZ); |
50694c28 MG |
3054 | |
3055 | goto check_pending; | |
5515061d MG |
3056 | } |
3057 | ||
3058 | /* Throttle until kswapd wakes the process */ | |
3059 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
c73322d0 | 3060 | allow_direct_reclaim(pgdat)); |
50694c28 MG |
3061 | |
3062 | check_pending: | |
3063 | if (fatal_signal_pending(current)) | |
3064 | return true; | |
3065 | ||
3066 | out: | |
3067 | return false; | |
5515061d MG |
3068 | } |
3069 | ||
dac1d27b | 3070 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 3071 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 3072 | { |
33906bc5 | 3073 | unsigned long nr_reclaimed; |
66e1707b | 3074 | struct scan_control sc = { |
ee814fe2 | 3075 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
f2f43e56 | 3076 | .gfp_mask = current_gfp_context(gfp_mask), |
b2e18757 | 3077 | .reclaim_idx = gfp_zone(gfp_mask), |
ee814fe2 JW |
3078 | .order = order, |
3079 | .nodemask = nodemask, | |
3080 | .priority = DEF_PRIORITY, | |
66e1707b | 3081 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3082 | .may_unmap = 1, |
2e2e4259 | 3083 | .may_swap = 1, |
66e1707b BS |
3084 | }; |
3085 | ||
5515061d | 3086 | /* |
50694c28 MG |
3087 | * Do not enter reclaim if fatal signal was delivered while throttled. |
3088 | * 1 is returned so that the page allocator does not OOM kill at this | |
3089 | * point. | |
5515061d | 3090 | */ |
f2f43e56 | 3091 | if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask)) |
5515061d MG |
3092 | return 1; |
3093 | ||
33906bc5 MG |
3094 | trace_mm_vmscan_direct_reclaim_begin(order, |
3095 | sc.may_writepage, | |
f2f43e56 | 3096 | sc.gfp_mask, |
e5146b12 | 3097 | sc.reclaim_idx); |
33906bc5 | 3098 | |
3115cd91 | 3099 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
33906bc5 MG |
3100 | |
3101 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
3102 | ||
3103 | return nr_reclaimed; | |
66e1707b BS |
3104 | } |
3105 | ||
c255a458 | 3106 | #ifdef CONFIG_MEMCG |
66e1707b | 3107 | |
a9dd0a83 | 3108 | unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, |
4e416953 | 3109 | gfp_t gfp_mask, bool noswap, |
ef8f2327 | 3110 | pg_data_t *pgdat, |
0ae5e89c | 3111 | unsigned long *nr_scanned) |
4e416953 BS |
3112 | { |
3113 | struct scan_control sc = { | |
b8f5c566 | 3114 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
ee814fe2 | 3115 | .target_mem_cgroup = memcg, |
4e416953 BS |
3116 | .may_writepage = !laptop_mode, |
3117 | .may_unmap = 1, | |
b2e18757 | 3118 | .reclaim_idx = MAX_NR_ZONES - 1, |
4e416953 | 3119 | .may_swap = !noswap, |
4e416953 | 3120 | }; |
6b4f7799 | 3121 | unsigned long lru_pages; |
0ae5e89c | 3122 | |
4e416953 BS |
3123 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
3124 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 3125 | |
9e3b2f8c | 3126 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e | 3127 | sc.may_writepage, |
e5146b12 MG |
3128 | sc.gfp_mask, |
3129 | sc.reclaim_idx); | |
bdce6d9e | 3130 | |
4e416953 BS |
3131 | /* |
3132 | * NOTE: Although we can get the priority field, using it | |
3133 | * here is not a good idea, since it limits the pages we can scan. | |
a9dd0a83 | 3134 | * if we don't reclaim here, the shrink_node from balance_pgdat |
4e416953 BS |
3135 | * will pick up pages from other mem cgroup's as well. We hack |
3136 | * the priority and make it zero. | |
3137 | */ | |
ef8f2327 | 3138 | shrink_node_memcg(pgdat, memcg, &sc, &lru_pages); |
bdce6d9e KM |
3139 | |
3140 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
3141 | ||
0ae5e89c | 3142 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
3143 | return sc.nr_reclaimed; |
3144 | } | |
3145 | ||
72835c86 | 3146 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
b70a2a21 | 3147 | unsigned long nr_pages, |
a7885eb8 | 3148 | gfp_t gfp_mask, |
b70a2a21 | 3149 | bool may_swap) |
66e1707b | 3150 | { |
4e416953 | 3151 | struct zonelist *zonelist; |
bdce6d9e | 3152 | unsigned long nr_reclaimed; |
889976db | 3153 | int nid; |
499118e9 | 3154 | unsigned int noreclaim_flag; |
66e1707b | 3155 | struct scan_control sc = { |
b70a2a21 | 3156 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
7dea19f9 | 3157 | .gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) | |
a09ed5e0 | 3158 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), |
b2e18757 | 3159 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 JW |
3160 | .target_mem_cgroup = memcg, |
3161 | .priority = DEF_PRIORITY, | |
3162 | .may_writepage = !laptop_mode, | |
3163 | .may_unmap = 1, | |
b70a2a21 | 3164 | .may_swap = may_swap, |
a09ed5e0 | 3165 | }; |
66e1707b | 3166 | |
889976db YH |
3167 | /* |
3168 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
3169 | * take care of from where we get pages. So the node where we start the | |
3170 | * scan does not need to be the current node. | |
3171 | */ | |
72835c86 | 3172 | nid = mem_cgroup_select_victim_node(memcg); |
889976db | 3173 | |
c9634cf0 | 3174 | zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK]; |
bdce6d9e KM |
3175 | |
3176 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
3177 | sc.may_writepage, | |
e5146b12 MG |
3178 | sc.gfp_mask, |
3179 | sc.reclaim_idx); | |
bdce6d9e | 3180 | |
499118e9 | 3181 | noreclaim_flag = memalloc_noreclaim_save(); |
3115cd91 | 3182 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
499118e9 | 3183 | memalloc_noreclaim_restore(noreclaim_flag); |
bdce6d9e KM |
3184 | |
3185 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
3186 | ||
3187 | return nr_reclaimed; | |
66e1707b BS |
3188 | } |
3189 | #endif | |
3190 | ||
1d82de61 | 3191 | static void age_active_anon(struct pglist_data *pgdat, |
ef8f2327 | 3192 | struct scan_control *sc) |
f16015fb | 3193 | { |
b95a2f2d | 3194 | struct mem_cgroup *memcg; |
f16015fb | 3195 | |
b95a2f2d JW |
3196 | if (!total_swap_pages) |
3197 | return; | |
3198 | ||
3199 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
3200 | do { | |
ef8f2327 | 3201 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
b95a2f2d | 3202 | |
ccfc2495 | 3203 | if (inactive_list_is_low(lruvec, false, sc, true)) |
1a93be0e | 3204 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 3205 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
3206 | |
3207 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
3208 | } while (memcg); | |
f16015fb JW |
3209 | } |
3210 | ||
e716f2eb MG |
3211 | /* |
3212 | * Returns true if there is an eligible zone balanced for the request order | |
3213 | * and classzone_idx | |
3214 | */ | |
3215 | static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) | |
60cefed4 | 3216 | { |
e716f2eb MG |
3217 | int i; |
3218 | unsigned long mark = -1; | |
3219 | struct zone *zone; | |
60cefed4 | 3220 | |
e716f2eb MG |
3221 | for (i = 0; i <= classzone_idx; i++) { |
3222 | zone = pgdat->node_zones + i; | |
6256c6b4 | 3223 | |
e716f2eb MG |
3224 | if (!managed_zone(zone)) |
3225 | continue; | |
3226 | ||
3227 | mark = high_wmark_pages(zone); | |
3228 | if (zone_watermark_ok_safe(zone, order, mark, classzone_idx)) | |
3229 | return true; | |
3230 | } | |
3231 | ||
3232 | /* | |
3233 | * If a node has no populated zone within classzone_idx, it does not | |
3234 | * need balancing by definition. This can happen if a zone-restricted | |
3235 | * allocation tries to wake a remote kswapd. | |
3236 | */ | |
3237 | if (mark == -1) | |
3238 | return true; | |
3239 | ||
3240 | return false; | |
60cefed4 JW |
3241 | } |
3242 | ||
631b6e08 MG |
3243 | /* Clear pgdat state for congested, dirty or under writeback. */ |
3244 | static void clear_pgdat_congested(pg_data_t *pgdat) | |
3245 | { | |
3246 | clear_bit(PGDAT_CONGESTED, &pgdat->flags); | |
3247 | clear_bit(PGDAT_DIRTY, &pgdat->flags); | |
3248 | clear_bit(PGDAT_WRITEBACK, &pgdat->flags); | |
3249 | } | |
3250 | ||
5515061d MG |
3251 | /* |
3252 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
3253 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
3254 | * | |
3255 | * Returns true if kswapd is ready to sleep | |
3256 | */ | |
d9f21d42 | 3257 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f50de2d3 | 3258 | { |
5515061d | 3259 | /* |
9e5e3661 | 3260 | * The throttled processes are normally woken up in balance_pgdat() as |
c73322d0 | 3261 | * soon as allow_direct_reclaim() is true. But there is a potential |
9e5e3661 VB |
3262 | * race between when kswapd checks the watermarks and a process gets |
3263 | * throttled. There is also a potential race if processes get | |
3264 | * throttled, kswapd wakes, a large process exits thereby balancing the | |
3265 | * zones, which causes kswapd to exit balance_pgdat() before reaching | |
3266 | * the wake up checks. If kswapd is going to sleep, no process should | |
3267 | * be sleeping on pfmemalloc_wait, so wake them now if necessary. If | |
3268 | * the wake up is premature, processes will wake kswapd and get | |
3269 | * throttled again. The difference from wake ups in balance_pgdat() is | |
3270 | * that here we are under prepare_to_wait(). | |
5515061d | 3271 | */ |
9e5e3661 VB |
3272 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) |
3273 | wake_up_all(&pgdat->pfmemalloc_wait); | |
f50de2d3 | 3274 | |
c73322d0 JW |
3275 | /* Hopeless node, leave it to direct reclaim */ |
3276 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) | |
3277 | return true; | |
3278 | ||
e716f2eb MG |
3279 | if (pgdat_balanced(pgdat, order, classzone_idx)) { |
3280 | clear_pgdat_congested(pgdat); | |
3281 | return true; | |
1d82de61 MG |
3282 | } |
3283 | ||
333b0a45 | 3284 | return false; |
f50de2d3 MG |
3285 | } |
3286 | ||
75485363 | 3287 | /* |
1d82de61 MG |
3288 | * kswapd shrinks a node of pages that are at or below the highest usable |
3289 | * zone that is currently unbalanced. | |
b8e83b94 MG |
3290 | * |
3291 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
3292 | * reclaim or if the lack of progress was due to pages under writeback. |
3293 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 3294 | */ |
1d82de61 | 3295 | static bool kswapd_shrink_node(pg_data_t *pgdat, |
accf6242 | 3296 | struct scan_control *sc) |
75485363 | 3297 | { |
1d82de61 MG |
3298 | struct zone *zone; |
3299 | int z; | |
75485363 | 3300 | |
1d82de61 MG |
3301 | /* Reclaim a number of pages proportional to the number of zones */ |
3302 | sc->nr_to_reclaim = 0; | |
970a39a3 | 3303 | for (z = 0; z <= sc->reclaim_idx; z++) { |
1d82de61 | 3304 | zone = pgdat->node_zones + z; |
6aa303de | 3305 | if (!managed_zone(zone)) |
1d82de61 | 3306 | continue; |
7c954f6d | 3307 | |
1d82de61 MG |
3308 | sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX); |
3309 | } | |
7c954f6d MG |
3310 | |
3311 | /* | |
1d82de61 MG |
3312 | * Historically care was taken to put equal pressure on all zones but |
3313 | * now pressure is applied based on node LRU order. | |
7c954f6d | 3314 | */ |
970a39a3 | 3315 | shrink_node(pgdat, sc); |
283aba9f | 3316 | |
7c954f6d | 3317 | /* |
1d82de61 MG |
3318 | * Fragmentation may mean that the system cannot be rebalanced for |
3319 | * high-order allocations. If twice the allocation size has been | |
3320 | * reclaimed then recheck watermarks only at order-0 to prevent | |
3321 | * excessive reclaim. Assume that a process requested a high-order | |
3322 | * can direct reclaim/compact. | |
7c954f6d | 3323 | */ |
9861a62c | 3324 | if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) |
1d82de61 | 3325 | sc->order = 0; |
7c954f6d | 3326 | |
b8e83b94 | 3327 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
3328 | } |
3329 | ||
1da177e4 | 3330 | /* |
1d82de61 MG |
3331 | * For kswapd, balance_pgdat() will reclaim pages across a node from zones |
3332 | * that are eligible for use by the caller until at least one zone is | |
3333 | * balanced. | |
1da177e4 | 3334 | * |
1d82de61 | 3335 | * Returns the order kswapd finished reclaiming at. |
1da177e4 LT |
3336 | * |
3337 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 | 3338 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
1d82de61 MG |
3339 | * found to have free_pages <= high_wmark_pages(zone), any page is that zone |
3340 | * or lower is eligible for reclaim until at least one usable zone is | |
3341 | * balanced. | |
1da177e4 | 3342 | */ |
accf6242 | 3343 | static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) |
1da177e4 | 3344 | { |
1da177e4 | 3345 | int i; |
0608f43d AM |
3346 | unsigned long nr_soft_reclaimed; |
3347 | unsigned long nr_soft_scanned; | |
1d82de61 | 3348 | struct zone *zone; |
179e9639 AM |
3349 | struct scan_control sc = { |
3350 | .gfp_mask = GFP_KERNEL, | |
ee814fe2 | 3351 | .order = order, |
b8e83b94 | 3352 | .priority = DEF_PRIORITY, |
ee814fe2 | 3353 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3354 | .may_unmap = 1, |
2e2e4259 | 3355 | .may_swap = 1, |
179e9639 | 3356 | }; |
f8891e5e | 3357 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 3358 | |
9e3b2f8c | 3359 | do { |
c73322d0 | 3360 | unsigned long nr_reclaimed = sc.nr_reclaimed; |
b8e83b94 MG |
3361 | bool raise_priority = true; |
3362 | ||
84c7a777 | 3363 | sc.reclaim_idx = classzone_idx; |
1da177e4 | 3364 | |
86c79f6b | 3365 | /* |
84c7a777 MG |
3366 | * If the number of buffer_heads exceeds the maximum allowed |
3367 | * then consider reclaiming from all zones. This has a dual | |
3368 | * purpose -- on 64-bit systems it is expected that | |
3369 | * buffer_heads are stripped during active rotation. On 32-bit | |
3370 | * systems, highmem pages can pin lowmem memory and shrinking | |
3371 | * buffers can relieve lowmem pressure. Reclaim may still not | |
3372 | * go ahead if all eligible zones for the original allocation | |
3373 | * request are balanced to avoid excessive reclaim from kswapd. | |
86c79f6b MG |
3374 | */ |
3375 | if (buffer_heads_over_limit) { | |
3376 | for (i = MAX_NR_ZONES - 1; i >= 0; i--) { | |
3377 | zone = pgdat->node_zones + i; | |
6aa303de | 3378 | if (!managed_zone(zone)) |
86c79f6b | 3379 | continue; |
cc715d99 | 3380 | |
970a39a3 | 3381 | sc.reclaim_idx = i; |
e1dbeda6 | 3382 | break; |
1da177e4 | 3383 | } |
1da177e4 | 3384 | } |
dafcb73e | 3385 | |
86c79f6b | 3386 | /* |
e716f2eb MG |
3387 | * Only reclaim if there are no eligible zones. Note that |
3388 | * sc.reclaim_idx is not used as buffer_heads_over_limit may | |
3389 | * have adjusted it. | |
86c79f6b | 3390 | */ |
e716f2eb MG |
3391 | if (pgdat_balanced(pgdat, sc.order, classzone_idx)) |
3392 | goto out; | |
e1dbeda6 | 3393 | |
1d82de61 MG |
3394 | /* |
3395 | * Do some background aging of the anon list, to give | |
3396 | * pages a chance to be referenced before reclaiming. All | |
3397 | * pages are rotated regardless of classzone as this is | |
3398 | * about consistent aging. | |
3399 | */ | |
ef8f2327 | 3400 | age_active_anon(pgdat, &sc); |
1d82de61 | 3401 | |
b7ea3c41 MG |
3402 | /* |
3403 | * If we're getting trouble reclaiming, start doing writepage | |
3404 | * even in laptop mode. | |
3405 | */ | |
047d72c3 | 3406 | if (sc.priority < DEF_PRIORITY - 2) |
b7ea3c41 MG |
3407 | sc.may_writepage = 1; |
3408 | ||
1d82de61 MG |
3409 | /* Call soft limit reclaim before calling shrink_node. */ |
3410 | sc.nr_scanned = 0; | |
3411 | nr_soft_scanned = 0; | |
ef8f2327 | 3412 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order, |
1d82de61 MG |
3413 | sc.gfp_mask, &nr_soft_scanned); |
3414 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3415 | ||
1da177e4 | 3416 | /* |
1d82de61 MG |
3417 | * There should be no need to raise the scanning priority if |
3418 | * enough pages are already being scanned that that high | |
3419 | * watermark would be met at 100% efficiency. | |
1da177e4 | 3420 | */ |
970a39a3 | 3421 | if (kswapd_shrink_node(pgdat, &sc)) |
1d82de61 | 3422 | raise_priority = false; |
5515061d MG |
3423 | |
3424 | /* | |
3425 | * If the low watermark is met there is no need for processes | |
3426 | * to be throttled on pfmemalloc_wait as they should not be | |
3427 | * able to safely make forward progress. Wake them | |
3428 | */ | |
3429 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
c73322d0 | 3430 | allow_direct_reclaim(pgdat)) |
cfc51155 | 3431 | wake_up_all(&pgdat->pfmemalloc_wait); |
5515061d | 3432 | |
b8e83b94 MG |
3433 | /* Check if kswapd should be suspending */ |
3434 | if (try_to_freeze() || kthread_should_stop()) | |
3435 | break; | |
8357376d | 3436 | |
73ce02e9 | 3437 | /* |
b8e83b94 MG |
3438 | * Raise priority if scanning rate is too low or there was no |
3439 | * progress in reclaiming pages | |
73ce02e9 | 3440 | */ |
c73322d0 JW |
3441 | nr_reclaimed = sc.nr_reclaimed - nr_reclaimed; |
3442 | if (raise_priority || !nr_reclaimed) | |
b8e83b94 | 3443 | sc.priority--; |
1d82de61 | 3444 | } while (sc.priority >= 1); |
1da177e4 | 3445 | |
c73322d0 JW |
3446 | if (!sc.nr_reclaimed) |
3447 | pgdat->kswapd_failures++; | |
3448 | ||
b8e83b94 | 3449 | out: |
2a2e4885 | 3450 | snapshot_refaults(NULL, pgdat); |
0abdee2b | 3451 | /* |
1d82de61 MG |
3452 | * Return the order kswapd stopped reclaiming at as |
3453 | * prepare_kswapd_sleep() takes it into account. If another caller | |
3454 | * entered the allocator slow path while kswapd was awake, order will | |
3455 | * remain at the higher level. | |
0abdee2b | 3456 | */ |
1d82de61 | 3457 | return sc.order; |
1da177e4 LT |
3458 | } |
3459 | ||
e716f2eb | 3460 | /* |
64ca5015 SB |
3461 | * The pgdat->kswapd_classzone_idx is used to pass the highest zone index to be |
3462 | * reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is not | |
3463 | * a valid index then either kswapd runs for first time or kswapd couldn't sleep | |
3464 | * after previous reclaim attempt (node is still unbalanced). In that case | |
3465 | * return the zone index of the previous kswapd reclaim cycle. | |
e716f2eb MG |
3466 | */ |
3467 | static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat, | |
64ca5015 | 3468 | enum zone_type prev_classzone_idx) |
e716f2eb MG |
3469 | { |
3470 | if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES) | |
64ca5015 SB |
3471 | return prev_classzone_idx; |
3472 | return pgdat->kswapd_classzone_idx; | |
e716f2eb MG |
3473 | } |
3474 | ||
38087d9b MG |
3475 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, |
3476 | unsigned int classzone_idx) | |
f0bc0a60 KM |
3477 | { |
3478 | long remaining = 0; | |
3479 | DEFINE_WAIT(wait); | |
3480 | ||
3481 | if (freezing(current) || kthread_should_stop()) | |
3482 | return; | |
3483 | ||
3484 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3485 | ||
333b0a45 SG |
3486 | /* |
3487 | * Try to sleep for a short interval. Note that kcompactd will only be | |
3488 | * woken if it is possible to sleep for a short interval. This is | |
3489 | * deliberate on the assumption that if reclaim cannot keep an | |
3490 | * eligible zone balanced that it's also unlikely that compaction will | |
3491 | * succeed. | |
3492 | */ | |
d9f21d42 | 3493 | if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { |
fd901c95 VB |
3494 | /* |
3495 | * Compaction records what page blocks it recently failed to | |
3496 | * isolate pages from and skips them in the future scanning. | |
3497 | * When kswapd is going to sleep, it is reasonable to assume | |
3498 | * that pages and compaction may succeed so reset the cache. | |
3499 | */ | |
3500 | reset_isolation_suitable(pgdat); | |
3501 | ||
3502 | /* | |
3503 | * We have freed the memory, now we should compact it to make | |
3504 | * allocation of the requested order possible. | |
3505 | */ | |
38087d9b | 3506 | wakeup_kcompactd(pgdat, alloc_order, classzone_idx); |
fd901c95 | 3507 | |
f0bc0a60 | 3508 | remaining = schedule_timeout(HZ/10); |
38087d9b MG |
3509 | |
3510 | /* | |
3511 | * If woken prematurely then reset kswapd_classzone_idx and | |
3512 | * order. The values will either be from a wakeup request or | |
3513 | * the previous request that slept prematurely. | |
3514 | */ | |
3515 | if (remaining) { | |
e716f2eb | 3516 | pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); |
38087d9b MG |
3517 | pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order); |
3518 | } | |
3519 | ||
f0bc0a60 KM |
3520 | finish_wait(&pgdat->kswapd_wait, &wait); |
3521 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3522 | } | |
3523 | ||
3524 | /* | |
3525 | * After a short sleep, check if it was a premature sleep. If not, then | |
3526 | * go fully to sleep until explicitly woken up. | |
3527 | */ | |
d9f21d42 MG |
3528 | if (!remaining && |
3529 | prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { | |
f0bc0a60 KM |
3530 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3531 | ||
3532 | /* | |
3533 | * vmstat counters are not perfectly accurate and the estimated | |
3534 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3535 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3536 | * watermarks being breached while under pressure, we reduce the | |
3537 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3538 | * them before going back to sleep. | |
3539 | */ | |
3540 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c AK |
3541 | |
3542 | if (!kthread_should_stop()) | |
3543 | schedule(); | |
3544 | ||
f0bc0a60 KM |
3545 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3546 | } else { | |
3547 | if (remaining) | |
3548 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3549 | else | |
3550 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3551 | } | |
3552 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3553 | } | |
3554 | ||
1da177e4 LT |
3555 | /* |
3556 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3557 | * from the init process. |
1da177e4 LT |
3558 | * |
3559 | * This basically trickles out pages so that we have _some_ | |
3560 | * free memory available even if there is no other activity | |
3561 | * that frees anything up. This is needed for things like routing | |
3562 | * etc, where we otherwise might have all activity going on in | |
3563 | * asynchronous contexts that cannot page things out. | |
3564 | * | |
3565 | * If there are applications that are active memory-allocators | |
3566 | * (most normal use), this basically shouldn't matter. | |
3567 | */ | |
3568 | static int kswapd(void *p) | |
3569 | { | |
e716f2eb MG |
3570 | unsigned int alloc_order, reclaim_order; |
3571 | unsigned int classzone_idx = MAX_NR_ZONES - 1; | |
1da177e4 LT |
3572 | pg_data_t *pgdat = (pg_data_t*)p; |
3573 | struct task_struct *tsk = current; | |
f0bc0a60 | 3574 | |
1da177e4 LT |
3575 | struct reclaim_state reclaim_state = { |
3576 | .reclaimed_slab = 0, | |
3577 | }; | |
a70f7302 | 3578 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3579 | |
174596a0 | 3580 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3581 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3582 | current->reclaim_state = &reclaim_state; |
3583 | ||
3584 | /* | |
3585 | * Tell the memory management that we're a "memory allocator", | |
3586 | * and that if we need more memory we should get access to it | |
3587 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3588 | * never get caught in the normal page freeing logic. | |
3589 | * | |
3590 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3591 | * you need a small amount of memory in order to be able to | |
3592 | * page out something else, and this flag essentially protects | |
3593 | * us from recursively trying to free more memory as we're | |
3594 | * trying to free the first piece of memory in the first place). | |
3595 | */ | |
930d9152 | 3596 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3597 | set_freezable(); |
1da177e4 | 3598 | |
e716f2eb MG |
3599 | pgdat->kswapd_order = 0; |
3600 | pgdat->kswapd_classzone_idx = MAX_NR_ZONES; | |
1da177e4 | 3601 | for ( ; ; ) { |
6f6313d4 | 3602 | bool ret; |
3e1d1d28 | 3603 | |
e716f2eb MG |
3604 | alloc_order = reclaim_order = pgdat->kswapd_order; |
3605 | classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); | |
3606 | ||
38087d9b MG |
3607 | kswapd_try_sleep: |
3608 | kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, | |
3609 | classzone_idx); | |
215ddd66 | 3610 | |
38087d9b MG |
3611 | /* Read the new order and classzone_idx */ |
3612 | alloc_order = reclaim_order = pgdat->kswapd_order; | |
64ca5015 | 3613 | classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); |
38087d9b | 3614 | pgdat->kswapd_order = 0; |
e716f2eb | 3615 | pgdat->kswapd_classzone_idx = MAX_NR_ZONES; |
1da177e4 | 3616 | |
8fe23e05 DR |
3617 | ret = try_to_freeze(); |
3618 | if (kthread_should_stop()) | |
3619 | break; | |
3620 | ||
3621 | /* | |
3622 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3623 | * after returning from the refrigerator | |
3624 | */ | |
38087d9b MG |
3625 | if (ret) |
3626 | continue; | |
3627 | ||
3628 | /* | |
3629 | * Reclaim begins at the requested order but if a high-order | |
3630 | * reclaim fails then kswapd falls back to reclaiming for | |
3631 | * order-0. If that happens, kswapd will consider sleeping | |
3632 | * for the order it finished reclaiming at (reclaim_order) | |
3633 | * but kcompactd is woken to compact for the original | |
3634 | * request (alloc_order). | |
3635 | */ | |
e5146b12 MG |
3636 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx, |
3637 | alloc_order); | |
d92a8cfc | 3638 | fs_reclaim_acquire(GFP_KERNEL); |
38087d9b | 3639 | reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); |
d92a8cfc | 3640 | fs_reclaim_release(GFP_KERNEL); |
38087d9b MG |
3641 | if (reclaim_order < alloc_order) |
3642 | goto kswapd_try_sleep; | |
1da177e4 | 3643 | } |
b0a8cc58 | 3644 | |
71abdc15 | 3645 | tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); |
b0a8cc58 | 3646 | current->reclaim_state = NULL; |
71abdc15 | 3647 | |
1da177e4 LT |
3648 | return 0; |
3649 | } | |
3650 | ||
3651 | /* | |
3652 | * A zone is low on free memory, so wake its kswapd task to service it. | |
3653 | */ | |
99504748 | 3654 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
3655 | { |
3656 | pg_data_t *pgdat; | |
3657 | ||
6aa303de | 3658 | if (!managed_zone(zone)) |
1da177e4 LT |
3659 | return; |
3660 | ||
344736f2 | 3661 | if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) |
1da177e4 | 3662 | return; |
88f5acf8 | 3663 | pgdat = zone->zone_pgdat; |
64ca5015 SB |
3664 | |
3665 | if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES) | |
3666 | pgdat->kswapd_classzone_idx = classzone_idx; | |
3667 | else | |
3668 | pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, | |
3669 | classzone_idx); | |
38087d9b | 3670 | pgdat->kswapd_order = max(pgdat->kswapd_order, order); |
8d0986e2 | 3671 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3672 | return; |
e1a55637 | 3673 | |
c73322d0 JW |
3674 | /* Hopeless node, leave it to direct reclaim */ |
3675 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) | |
3676 | return; | |
3677 | ||
e716f2eb MG |
3678 | if (pgdat_balanced(pgdat, order, classzone_idx)) |
3679 | return; | |
88f5acf8 | 3680 | |
e716f2eb | 3681 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order); |
8d0986e2 | 3682 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3683 | } |
3684 | ||
c6f37f12 | 3685 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3686 | /* |
7b51755c | 3687 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3688 | * freed pages. |
3689 | * | |
3690 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3691 | * LRU order by reclaiming preferentially | |
3692 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3693 | */ |
7b51755c | 3694 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3695 | { |
d6277db4 | 3696 | struct reclaim_state reclaim_state; |
d6277db4 | 3697 | struct scan_control sc = { |
ee814fe2 | 3698 | .nr_to_reclaim = nr_to_reclaim, |
7b51755c | 3699 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
b2e18757 | 3700 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 | 3701 | .priority = DEF_PRIORITY, |
d6277db4 | 3702 | .may_writepage = 1, |
ee814fe2 JW |
3703 | .may_unmap = 1, |
3704 | .may_swap = 1, | |
7b51755c | 3705 | .hibernation_mode = 1, |
1da177e4 | 3706 | }; |
a09ed5e0 | 3707 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
7b51755c KM |
3708 | struct task_struct *p = current; |
3709 | unsigned long nr_reclaimed; | |
499118e9 | 3710 | unsigned int noreclaim_flag; |
1da177e4 | 3711 | |
499118e9 | 3712 | noreclaim_flag = memalloc_noreclaim_save(); |
d92a8cfc | 3713 | fs_reclaim_acquire(sc.gfp_mask); |
7b51755c KM |
3714 | reclaim_state.reclaimed_slab = 0; |
3715 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3716 | |
3115cd91 | 3717 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 3718 | |
7b51755c | 3719 | p->reclaim_state = NULL; |
d92a8cfc | 3720 | fs_reclaim_release(sc.gfp_mask); |
499118e9 | 3721 | memalloc_noreclaim_restore(noreclaim_flag); |
d6277db4 | 3722 | |
7b51755c | 3723 | return nr_reclaimed; |
1da177e4 | 3724 | } |
c6f37f12 | 3725 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3726 | |
1da177e4 LT |
3727 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3728 | not required for correctness. So if the last cpu in a node goes | |
3729 | away, we get changed to run anywhere: as the first one comes back, | |
3730 | restore their cpu bindings. */ | |
517bbed9 | 3731 | static int kswapd_cpu_online(unsigned int cpu) |
1da177e4 | 3732 | { |
58c0a4a7 | 3733 | int nid; |
1da177e4 | 3734 | |
517bbed9 SAS |
3735 | for_each_node_state(nid, N_MEMORY) { |
3736 | pg_data_t *pgdat = NODE_DATA(nid); | |
3737 | const struct cpumask *mask; | |
a70f7302 | 3738 | |
517bbed9 | 3739 | mask = cpumask_of_node(pgdat->node_id); |
c5f59f08 | 3740 | |
517bbed9 SAS |
3741 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
3742 | /* One of our CPUs online: restore mask */ | |
3743 | set_cpus_allowed_ptr(pgdat->kswapd, mask); | |
1da177e4 | 3744 | } |
517bbed9 | 3745 | return 0; |
1da177e4 | 3746 | } |
1da177e4 | 3747 | |
3218ae14 YG |
3748 | /* |
3749 | * This kswapd start function will be called by init and node-hot-add. | |
3750 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3751 | */ | |
3752 | int kswapd_run(int nid) | |
3753 | { | |
3754 | pg_data_t *pgdat = NODE_DATA(nid); | |
3755 | int ret = 0; | |
3756 | ||
3757 | if (pgdat->kswapd) | |
3758 | return 0; | |
3759 | ||
3760 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3761 | if (IS_ERR(pgdat->kswapd)) { | |
3762 | /* failure at boot is fatal */ | |
c6202adf | 3763 | BUG_ON(system_state < SYSTEM_RUNNING); |
d5dc0ad9 GS |
3764 | pr_err("Failed to start kswapd on node %d\n", nid); |
3765 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3766 | pgdat->kswapd = NULL; |
3218ae14 YG |
3767 | } |
3768 | return ret; | |
3769 | } | |
3770 | ||
8fe23e05 | 3771 | /* |
d8adde17 | 3772 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
bfc8c901 | 3773 | * hold mem_hotplug_begin/end(). |
8fe23e05 DR |
3774 | */ |
3775 | void kswapd_stop(int nid) | |
3776 | { | |
3777 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3778 | ||
d8adde17 | 3779 | if (kswapd) { |
8fe23e05 | 3780 | kthread_stop(kswapd); |
d8adde17 JL |
3781 | NODE_DATA(nid)->kswapd = NULL; |
3782 | } | |
8fe23e05 DR |
3783 | } |
3784 | ||
1da177e4 LT |
3785 | static int __init kswapd_init(void) |
3786 | { | |
517bbed9 | 3787 | int nid, ret; |
69e05944 | 3788 | |
1da177e4 | 3789 | swap_setup(); |
48fb2e24 | 3790 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3791 | kswapd_run(nid); |
517bbed9 SAS |
3792 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, |
3793 | "mm/vmscan:online", kswapd_cpu_online, | |
3794 | NULL); | |
3795 | WARN_ON(ret < 0); | |
1da177e4 LT |
3796 | return 0; |
3797 | } | |
3798 | ||
3799 | module_init(kswapd_init) | |
9eeff239 CL |
3800 | |
3801 | #ifdef CONFIG_NUMA | |
3802 | /* | |
a5f5f91d | 3803 | * Node reclaim mode |
9eeff239 | 3804 | * |
a5f5f91d | 3805 | * If non-zero call node_reclaim when the number of free pages falls below |
9eeff239 | 3806 | * the watermarks. |
9eeff239 | 3807 | */ |
a5f5f91d | 3808 | int node_reclaim_mode __read_mostly; |
9eeff239 | 3809 | |
1b2ffb78 | 3810 | #define RECLAIM_OFF 0 |
7d03431c | 3811 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 | 3812 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
95bbc0c7 | 3813 | #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ |
1b2ffb78 | 3814 | |
a92f7126 | 3815 | /* |
a5f5f91d | 3816 | * Priority for NODE_RECLAIM. This determines the fraction of pages |
a92f7126 CL |
3817 | * of a node considered for each zone_reclaim. 4 scans 1/16th of |
3818 | * a zone. | |
3819 | */ | |
a5f5f91d | 3820 | #define NODE_RECLAIM_PRIORITY 4 |
a92f7126 | 3821 | |
9614634f | 3822 | /* |
a5f5f91d | 3823 | * Percentage of pages in a zone that must be unmapped for node_reclaim to |
9614634f CL |
3824 | * occur. |
3825 | */ | |
3826 | int sysctl_min_unmapped_ratio = 1; | |
3827 | ||
0ff38490 CL |
3828 | /* |
3829 | * If the number of slab pages in a zone grows beyond this percentage then | |
3830 | * slab reclaim needs to occur. | |
3831 | */ | |
3832 | int sysctl_min_slab_ratio = 5; | |
3833 | ||
11fb9989 | 3834 | static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat) |
90afa5de | 3835 | { |
11fb9989 MG |
3836 | unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED); |
3837 | unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) + | |
3838 | node_page_state(pgdat, NR_ACTIVE_FILE); | |
90afa5de MG |
3839 | |
3840 | /* | |
3841 | * It's possible for there to be more file mapped pages than | |
3842 | * accounted for by the pages on the file LRU lists because | |
3843 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3844 | */ | |
3845 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3846 | } | |
3847 | ||
3848 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
a5f5f91d | 3849 | static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) |
90afa5de | 3850 | { |
d031a157 AM |
3851 | unsigned long nr_pagecache_reclaimable; |
3852 | unsigned long delta = 0; | |
90afa5de MG |
3853 | |
3854 | /* | |
95bbc0c7 | 3855 | * If RECLAIM_UNMAP is set, then all file pages are considered |
90afa5de | 3856 | * potentially reclaimable. Otherwise, we have to worry about |
11fb9989 | 3857 | * pages like swapcache and node_unmapped_file_pages() provides |
90afa5de MG |
3858 | * a better estimate |
3859 | */ | |
a5f5f91d MG |
3860 | if (node_reclaim_mode & RECLAIM_UNMAP) |
3861 | nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES); | |
90afa5de | 3862 | else |
a5f5f91d | 3863 | nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat); |
90afa5de MG |
3864 | |
3865 | /* If we can't clean pages, remove dirty pages from consideration */ | |
a5f5f91d MG |
3866 | if (!(node_reclaim_mode & RECLAIM_WRITE)) |
3867 | delta += node_page_state(pgdat, NR_FILE_DIRTY); | |
90afa5de MG |
3868 | |
3869 | /* Watch for any possible underflows due to delta */ | |
3870 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3871 | delta = nr_pagecache_reclaimable; | |
3872 | ||
3873 | return nr_pagecache_reclaimable - delta; | |
3874 | } | |
3875 | ||
9eeff239 | 3876 | /* |
a5f5f91d | 3877 | * Try to free up some pages from this node through reclaim. |
9eeff239 | 3878 | */ |
a5f5f91d | 3879 | static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3880 | { |
7fb2d46d | 3881 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3882 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3883 | struct task_struct *p = current; |
3884 | struct reclaim_state reclaim_state; | |
499118e9 | 3885 | unsigned int noreclaim_flag; |
179e9639 | 3886 | struct scan_control sc = { |
62b726c1 | 3887 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
f2f43e56 | 3888 | .gfp_mask = current_gfp_context(gfp_mask), |
bd2f6199 | 3889 | .order = order, |
a5f5f91d MG |
3890 | .priority = NODE_RECLAIM_PRIORITY, |
3891 | .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), | |
3892 | .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), | |
ee814fe2 | 3893 | .may_swap = 1, |
f2f43e56 | 3894 | .reclaim_idx = gfp_zone(gfp_mask), |
179e9639 | 3895 | }; |
9eeff239 | 3896 | |
9eeff239 | 3897 | cond_resched(); |
d4f7796e | 3898 | /* |
95bbc0c7 | 3899 | * We need to be able to allocate from the reserves for RECLAIM_UNMAP |
d4f7796e | 3900 | * and we also need to be able to write out pages for RECLAIM_WRITE |
95bbc0c7 | 3901 | * and RECLAIM_UNMAP. |
d4f7796e | 3902 | */ |
499118e9 VB |
3903 | noreclaim_flag = memalloc_noreclaim_save(); |
3904 | p->flags |= PF_SWAPWRITE; | |
d92a8cfc | 3905 | fs_reclaim_acquire(sc.gfp_mask); |
9eeff239 CL |
3906 | reclaim_state.reclaimed_slab = 0; |
3907 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3908 | |
a5f5f91d | 3909 | if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) { |
0ff38490 CL |
3910 | /* |
3911 | * Free memory by calling shrink zone with increasing | |
3912 | * priorities until we have enough memory freed. | |
3913 | */ | |
0ff38490 | 3914 | do { |
970a39a3 | 3915 | shrink_node(pgdat, &sc); |
9e3b2f8c | 3916 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); |
0ff38490 | 3917 | } |
c84db23c | 3918 | |
9eeff239 | 3919 | p->reclaim_state = NULL; |
d92a8cfc | 3920 | fs_reclaim_release(gfp_mask); |
499118e9 VB |
3921 | current->flags &= ~PF_SWAPWRITE; |
3922 | memalloc_noreclaim_restore(noreclaim_flag); | |
a79311c1 | 3923 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3924 | } |
179e9639 | 3925 | |
a5f5f91d | 3926 | int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
179e9639 | 3927 | { |
d773ed6b | 3928 | int ret; |
179e9639 AM |
3929 | |
3930 | /* | |
a5f5f91d | 3931 | * Node reclaim reclaims unmapped file backed pages and |
0ff38490 | 3932 | * slab pages if we are over the defined limits. |
34aa1330 | 3933 | * |
9614634f CL |
3934 | * A small portion of unmapped file backed pages is needed for |
3935 | * file I/O otherwise pages read by file I/O will be immediately | |
a5f5f91d MG |
3936 | * thrown out if the node is overallocated. So we do not reclaim |
3937 | * if less than a specified percentage of the node is used by | |
9614634f | 3938 | * unmapped file backed pages. |
179e9639 | 3939 | */ |
a5f5f91d | 3940 | if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && |
385386cf | 3941 | node_page_state(pgdat, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages) |
a5f5f91d | 3942 | return NODE_RECLAIM_FULL; |
179e9639 AM |
3943 | |
3944 | /* | |
d773ed6b | 3945 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3946 | */ |
d0164adc | 3947 | if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) |
a5f5f91d | 3948 | return NODE_RECLAIM_NOSCAN; |
179e9639 AM |
3949 | |
3950 | /* | |
a5f5f91d | 3951 | * Only run node reclaim on the local node or on nodes that do not |
179e9639 AM |
3952 | * have associated processors. This will favor the local processor |
3953 | * over remote processors and spread off node memory allocations | |
3954 | * as wide as possible. | |
3955 | */ | |
a5f5f91d MG |
3956 | if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) |
3957 | return NODE_RECLAIM_NOSCAN; | |
d773ed6b | 3958 | |
a5f5f91d MG |
3959 | if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) |
3960 | return NODE_RECLAIM_NOSCAN; | |
fa5e084e | 3961 | |
a5f5f91d MG |
3962 | ret = __node_reclaim(pgdat, gfp_mask, order); |
3963 | clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags); | |
d773ed6b | 3964 | |
24cf7251 MG |
3965 | if (!ret) |
3966 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3967 | ||
d773ed6b | 3968 | return ret; |
179e9639 | 3969 | } |
9eeff239 | 3970 | #endif |
894bc310 | 3971 | |
894bc310 LS |
3972 | /* |
3973 | * page_evictable - test whether a page is evictable | |
3974 | * @page: the page to test | |
894bc310 LS |
3975 | * |
3976 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 3977 | * lists vs unevictable list. |
894bc310 LS |
3978 | * |
3979 | * Reasons page might not be evictable: | |
ba9ddf49 | 3980 | * (1) page's mapping marked unevictable |
b291f000 | 3981 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3982 | * |
894bc310 | 3983 | */ |
39b5f29a | 3984 | int page_evictable(struct page *page) |
894bc310 | 3985 | { |
f63ea7fc HY |
3986 | int ret; |
3987 | ||
3988 | /* Prevent address_space of inode and swap cache from being freed */ | |
3989 | rcu_read_lock(); | |
3990 | ret = !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); | |
3991 | rcu_read_unlock(); | |
3992 | return ret; | |
894bc310 | 3993 | } |
89e004ea | 3994 | |
85046579 | 3995 | #ifdef CONFIG_SHMEM |
89e004ea | 3996 | /** |
24513264 HD |
3997 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
3998 | * @pages: array of pages to check | |
3999 | * @nr_pages: number of pages to check | |
89e004ea | 4000 | * |
24513264 | 4001 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
4002 | * |
4003 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 4004 | */ |
24513264 | 4005 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 4006 | { |
925b7673 | 4007 | struct lruvec *lruvec; |
785b99fe | 4008 | struct pglist_data *pgdat = NULL; |
24513264 HD |
4009 | int pgscanned = 0; |
4010 | int pgrescued = 0; | |
4011 | int i; | |
89e004ea | 4012 | |
24513264 HD |
4013 | for (i = 0; i < nr_pages; i++) { |
4014 | struct page *page = pages[i]; | |
785b99fe | 4015 | struct pglist_data *pagepgdat = page_pgdat(page); |
89e004ea | 4016 | |
24513264 | 4017 | pgscanned++; |
785b99fe MG |
4018 | if (pagepgdat != pgdat) { |
4019 | if (pgdat) | |
4020 | spin_unlock_irq(&pgdat->lru_lock); | |
4021 | pgdat = pagepgdat; | |
4022 | spin_lock_irq(&pgdat->lru_lock); | |
24513264 | 4023 | } |
785b99fe | 4024 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
89e004ea | 4025 | |
24513264 HD |
4026 | if (!PageLRU(page) || !PageUnevictable(page)) |
4027 | continue; | |
89e004ea | 4028 | |
39b5f29a | 4029 | if (page_evictable(page)) { |
24513264 HD |
4030 | enum lru_list lru = page_lru_base_type(page); |
4031 | ||
309381fe | 4032 | VM_BUG_ON_PAGE(PageActive(page), page); |
24513264 | 4033 | ClearPageUnevictable(page); |
fa9add64 HD |
4034 | del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); |
4035 | add_page_to_lru_list(page, lruvec, lru); | |
24513264 | 4036 | pgrescued++; |
89e004ea | 4037 | } |
24513264 | 4038 | } |
89e004ea | 4039 | |
785b99fe | 4040 | if (pgdat) { |
24513264 HD |
4041 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); |
4042 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
785b99fe | 4043 | spin_unlock_irq(&pgdat->lru_lock); |
89e004ea | 4044 | } |
89e004ea | 4045 | } |
85046579 | 4046 | #endif /* CONFIG_SHMEM */ |