]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
b1de0d13 MH |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | ||
1da177e4 | 16 | #include <linux/mm.h> |
5b3cc15a | 17 | #include <linux/sched/mm.h> |
1da177e4 | 18 | #include <linux/module.h> |
5a0e3ad6 | 19 | #include <linux/gfp.h> |
1da177e4 LT |
20 | #include <linux/kernel_stat.h> |
21 | #include <linux/swap.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/highmem.h> | |
70ddf637 | 25 | #include <linux/vmpressure.h> |
e129b5c2 | 26 | #include <linux/vmstat.h> |
1da177e4 LT |
27 | #include <linux/file.h> |
28 | #include <linux/writeback.h> | |
29 | #include <linux/blkdev.h> | |
30 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
31 | buffer_heads_over_limit */ | |
32 | #include <linux/mm_inline.h> | |
1da177e4 LT |
33 | #include <linux/backing-dev.h> |
34 | #include <linux/rmap.h> | |
35 | #include <linux/topology.h> | |
36 | #include <linux/cpu.h> | |
37 | #include <linux/cpuset.h> | |
3e7d3449 | 38 | #include <linux/compaction.h> |
1da177e4 LT |
39 | #include <linux/notifier.h> |
40 | #include <linux/rwsem.h> | |
248a0301 | 41 | #include <linux/delay.h> |
3218ae14 | 42 | #include <linux/kthread.h> |
7dfb7103 | 43 | #include <linux/freezer.h> |
66e1707b | 44 | #include <linux/memcontrol.h> |
873b4771 | 45 | #include <linux/delayacct.h> |
af936a16 | 46 | #include <linux/sysctl.h> |
929bea7c | 47 | #include <linux/oom.h> |
268bb0ce | 48 | #include <linux/prefetch.h> |
b1de0d13 | 49 | #include <linux/printk.h> |
f9fe48be | 50 | #include <linux/dax.h> |
1da177e4 LT |
51 | |
52 | #include <asm/tlbflush.h> | |
53 | #include <asm/div64.h> | |
54 | ||
55 | #include <linux/swapops.h> | |
117aad1e | 56 | #include <linux/balloon_compaction.h> |
1da177e4 | 57 | |
0f8053a5 NP |
58 | #include "internal.h" |
59 | ||
33906bc5 MG |
60 | #define CREATE_TRACE_POINTS |
61 | #include <trace/events/vmscan.h> | |
62 | ||
1da177e4 | 63 | struct scan_control { |
22fba335 KM |
64 | /* How many pages shrink_list() should reclaim */ |
65 | unsigned long nr_to_reclaim; | |
66 | ||
1da177e4 | 67 | /* This context's GFP mask */ |
6daa0e28 | 68 | gfp_t gfp_mask; |
1da177e4 | 69 | |
ee814fe2 | 70 | /* Allocation order */ |
5ad333eb | 71 | int order; |
66e1707b | 72 | |
ee814fe2 JW |
73 | /* |
74 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
75 | * are scanned. | |
76 | */ | |
77 | nodemask_t *nodemask; | |
9e3b2f8c | 78 | |
f16015fb JW |
79 | /* |
80 | * The memory cgroup that hit its limit and as a result is the | |
81 | * primary target of this reclaim invocation. | |
82 | */ | |
83 | struct mem_cgroup *target_mem_cgroup; | |
66e1707b | 84 | |
ee814fe2 JW |
85 | /* Scan (total_size >> priority) pages at once */ |
86 | int priority; | |
87 | ||
b2e18757 MG |
88 | /* The highest zone to isolate pages for reclaim from */ |
89 | enum zone_type reclaim_idx; | |
90 | ||
1276ad68 | 91 | /* Writepage batching in laptop mode; RECLAIM_WRITE */ |
ee814fe2 JW |
92 | unsigned int may_writepage:1; |
93 | ||
94 | /* Can mapped pages be reclaimed? */ | |
95 | unsigned int may_unmap:1; | |
96 | ||
97 | /* Can pages be swapped as part of reclaim? */ | |
98 | unsigned int may_swap:1; | |
99 | ||
241994ed JW |
100 | /* Can cgroups be reclaimed below their normal consumption range? */ |
101 | unsigned int may_thrash:1; | |
102 | ||
ee814fe2 JW |
103 | unsigned int hibernation_mode:1; |
104 | ||
105 | /* One of the zones is ready for compaction */ | |
106 | unsigned int compaction_ready:1; | |
107 | ||
108 | /* Incremented by the number of inactive pages that were scanned */ | |
109 | unsigned long nr_scanned; | |
110 | ||
111 | /* Number of pages freed so far during a call to shrink_zones() */ | |
112 | unsigned long nr_reclaimed; | |
1da177e4 LT |
113 | }; |
114 | ||
1da177e4 LT |
115 | #ifdef ARCH_HAS_PREFETCH |
116 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
117 | do { \ | |
118 | if ((_page)->lru.prev != _base) { \ | |
119 | struct page *prev; \ | |
120 | \ | |
121 | prev = lru_to_page(&(_page->lru)); \ | |
122 | prefetch(&prev->_field); \ | |
123 | } \ | |
124 | } while (0) | |
125 | #else | |
126 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
127 | #endif | |
128 | ||
129 | #ifdef ARCH_HAS_PREFETCHW | |
130 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
131 | do { \ | |
132 | if ((_page)->lru.prev != _base) { \ | |
133 | struct page *prev; \ | |
134 | \ | |
135 | prev = lru_to_page(&(_page->lru)); \ | |
136 | prefetchw(&prev->_field); \ | |
137 | } \ | |
138 | } while (0) | |
139 | #else | |
140 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
141 | #endif | |
142 | ||
143 | /* | |
144 | * From 0 .. 100. Higher means more swappy. | |
145 | */ | |
146 | int vm_swappiness = 60; | |
d0480be4 WSH |
147 | /* |
148 | * The total number of pages which are beyond the high watermark within all | |
149 | * zones. | |
150 | */ | |
151 | unsigned long vm_total_pages; | |
1da177e4 LT |
152 | |
153 | static LIST_HEAD(shrinker_list); | |
154 | static DECLARE_RWSEM(shrinker_rwsem); | |
155 | ||
c255a458 | 156 | #ifdef CONFIG_MEMCG |
89b5fae5 JW |
157 | static bool global_reclaim(struct scan_control *sc) |
158 | { | |
f16015fb | 159 | return !sc->target_mem_cgroup; |
89b5fae5 | 160 | } |
97c9341f TH |
161 | |
162 | /** | |
163 | * sane_reclaim - is the usual dirty throttling mechanism operational? | |
164 | * @sc: scan_control in question | |
165 | * | |
166 | * The normal page dirty throttling mechanism in balance_dirty_pages() is | |
167 | * completely broken with the legacy memcg and direct stalling in | |
168 | * shrink_page_list() is used for throttling instead, which lacks all the | |
169 | * niceties such as fairness, adaptive pausing, bandwidth proportional | |
170 | * allocation and configurability. | |
171 | * | |
172 | * This function tests whether the vmscan currently in progress can assume | |
173 | * that the normal dirty throttling mechanism is operational. | |
174 | */ | |
175 | static bool sane_reclaim(struct scan_control *sc) | |
176 | { | |
177 | struct mem_cgroup *memcg = sc->target_mem_cgroup; | |
178 | ||
179 | if (!memcg) | |
180 | return true; | |
181 | #ifdef CONFIG_CGROUP_WRITEBACK | |
69234ace | 182 | if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) |
97c9341f TH |
183 | return true; |
184 | #endif | |
185 | return false; | |
186 | } | |
91a45470 | 187 | #else |
89b5fae5 JW |
188 | static bool global_reclaim(struct scan_control *sc) |
189 | { | |
190 | return true; | |
191 | } | |
97c9341f TH |
192 | |
193 | static bool sane_reclaim(struct scan_control *sc) | |
194 | { | |
195 | return true; | |
196 | } | |
91a45470 KH |
197 | #endif |
198 | ||
5a1c84b4 MG |
199 | /* |
200 | * This misses isolated pages which are not accounted for to save counters. | |
201 | * As the data only determines if reclaim or compaction continues, it is | |
202 | * not expected that isolated pages will be a dominating factor. | |
203 | */ | |
204 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
205 | { | |
206 | unsigned long nr; | |
207 | ||
208 | nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + | |
209 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); | |
210 | if (get_nr_swap_pages() > 0) | |
211 | nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + | |
212 | zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); | |
213 | ||
214 | return nr; | |
215 | } | |
216 | ||
599d0c95 MG |
217 | unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat) |
218 | { | |
219 | unsigned long nr; | |
220 | ||
221 | nr = node_page_state_snapshot(pgdat, NR_ACTIVE_FILE) + | |
222 | node_page_state_snapshot(pgdat, NR_INACTIVE_FILE) + | |
223 | node_page_state_snapshot(pgdat, NR_ISOLATED_FILE); | |
6e543d57 LD |
224 | |
225 | if (get_nr_swap_pages() > 0) | |
599d0c95 MG |
226 | nr += node_page_state_snapshot(pgdat, NR_ACTIVE_ANON) + |
227 | node_page_state_snapshot(pgdat, NR_INACTIVE_ANON) + | |
228 | node_page_state_snapshot(pgdat, NR_ISOLATED_ANON); | |
6e543d57 LD |
229 | |
230 | return nr; | |
231 | } | |
232 | ||
fd538803 MH |
233 | /** |
234 | * lruvec_lru_size - Returns the number of pages on the given LRU list. | |
235 | * @lruvec: lru vector | |
236 | * @lru: lru to use | |
237 | * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list) | |
238 | */ | |
239 | unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx) | |
c9f299d9 | 240 | { |
fd538803 MH |
241 | unsigned long lru_size; |
242 | int zid; | |
243 | ||
c3c787e8 | 244 | if (!mem_cgroup_disabled()) |
fd538803 MH |
245 | lru_size = mem_cgroup_get_lru_size(lruvec, lru); |
246 | else | |
247 | lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru); | |
a3d8e054 | 248 | |
fd538803 MH |
249 | for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) { |
250 | struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid]; | |
251 | unsigned long size; | |
c9f299d9 | 252 | |
fd538803 MH |
253 | if (!managed_zone(zone)) |
254 | continue; | |
255 | ||
256 | if (!mem_cgroup_disabled()) | |
257 | size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid); | |
258 | else | |
259 | size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid], | |
260 | NR_ZONE_LRU_BASE + lru); | |
261 | lru_size -= min(size, lru_size); | |
262 | } | |
263 | ||
264 | return lru_size; | |
b4536f0c | 265 | |
b4536f0c MH |
266 | } |
267 | ||
1da177e4 | 268 | /* |
1d3d4437 | 269 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 270 | */ |
1d3d4437 | 271 | int register_shrinker(struct shrinker *shrinker) |
1da177e4 | 272 | { |
1d3d4437 GC |
273 | size_t size = sizeof(*shrinker->nr_deferred); |
274 | ||
1d3d4437 GC |
275 | if (shrinker->flags & SHRINKER_NUMA_AWARE) |
276 | size *= nr_node_ids; | |
277 | ||
278 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
279 | if (!shrinker->nr_deferred) | |
280 | return -ENOMEM; | |
281 | ||
8e1f936b RR |
282 | down_write(&shrinker_rwsem); |
283 | list_add_tail(&shrinker->list, &shrinker_list); | |
284 | up_write(&shrinker_rwsem); | |
1d3d4437 | 285 | return 0; |
1da177e4 | 286 | } |
8e1f936b | 287 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
288 | |
289 | /* | |
290 | * Remove one | |
291 | */ | |
8e1f936b | 292 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
293 | { |
294 | down_write(&shrinker_rwsem); | |
295 | list_del(&shrinker->list); | |
296 | up_write(&shrinker_rwsem); | |
ae393321 | 297 | kfree(shrinker->nr_deferred); |
1da177e4 | 298 | } |
8e1f936b | 299 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
300 | |
301 | #define SHRINK_BATCH 128 | |
1d3d4437 | 302 | |
cb731d6c VD |
303 | static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, |
304 | struct shrinker *shrinker, | |
305 | unsigned long nr_scanned, | |
306 | unsigned long nr_eligible) | |
1d3d4437 GC |
307 | { |
308 | unsigned long freed = 0; | |
309 | unsigned long long delta; | |
310 | long total_scan; | |
d5bc5fd3 | 311 | long freeable; |
1d3d4437 GC |
312 | long nr; |
313 | long new_nr; | |
314 | int nid = shrinkctl->nid; | |
315 | long batch_size = shrinker->batch ? shrinker->batch | |
316 | : SHRINK_BATCH; | |
5f33a080 | 317 | long scanned = 0, next_deferred; |
1d3d4437 | 318 | |
d5bc5fd3 VD |
319 | freeable = shrinker->count_objects(shrinker, shrinkctl); |
320 | if (freeable == 0) | |
1d3d4437 GC |
321 | return 0; |
322 | ||
323 | /* | |
324 | * copy the current shrinker scan count into a local variable | |
325 | * and zero it so that other concurrent shrinker invocations | |
326 | * don't also do this scanning work. | |
327 | */ | |
328 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
329 | ||
330 | total_scan = nr; | |
6b4f7799 | 331 | delta = (4 * nr_scanned) / shrinker->seeks; |
d5bc5fd3 | 332 | delta *= freeable; |
6b4f7799 | 333 | do_div(delta, nr_eligible + 1); |
1d3d4437 GC |
334 | total_scan += delta; |
335 | if (total_scan < 0) { | |
8612c663 | 336 | pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", |
a0b02131 | 337 | shrinker->scan_objects, total_scan); |
d5bc5fd3 | 338 | total_scan = freeable; |
5f33a080 SL |
339 | next_deferred = nr; |
340 | } else | |
341 | next_deferred = total_scan; | |
1d3d4437 GC |
342 | |
343 | /* | |
344 | * We need to avoid excessive windup on filesystem shrinkers | |
345 | * due to large numbers of GFP_NOFS allocations causing the | |
346 | * shrinkers to return -1 all the time. This results in a large | |
347 | * nr being built up so when a shrink that can do some work | |
348 | * comes along it empties the entire cache due to nr >>> | |
d5bc5fd3 | 349 | * freeable. This is bad for sustaining a working set in |
1d3d4437 GC |
350 | * memory. |
351 | * | |
352 | * Hence only allow the shrinker to scan the entire cache when | |
353 | * a large delta change is calculated directly. | |
354 | */ | |
d5bc5fd3 VD |
355 | if (delta < freeable / 4) |
356 | total_scan = min(total_scan, freeable / 2); | |
1d3d4437 GC |
357 | |
358 | /* | |
359 | * Avoid risking looping forever due to too large nr value: | |
360 | * never try to free more than twice the estimate number of | |
361 | * freeable entries. | |
362 | */ | |
d5bc5fd3 VD |
363 | if (total_scan > freeable * 2) |
364 | total_scan = freeable * 2; | |
1d3d4437 GC |
365 | |
366 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
6b4f7799 JW |
367 | nr_scanned, nr_eligible, |
368 | freeable, delta, total_scan); | |
1d3d4437 | 369 | |
0b1fb40a VD |
370 | /* |
371 | * Normally, we should not scan less than batch_size objects in one | |
372 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
373 | * than batch_size objects in total and we are really tight on memory, | |
374 | * we will try to reclaim all available objects, otherwise we can end | |
375 | * up failing allocations although there are plenty of reclaimable | |
376 | * objects spread over several slabs with usage less than the | |
377 | * batch_size. | |
378 | * | |
379 | * We detect the "tight on memory" situations by looking at the total | |
380 | * number of objects we want to scan (total_scan). If it is greater | |
d5bc5fd3 | 381 | * than the total number of objects on slab (freeable), we must be |
0b1fb40a VD |
382 | * scanning at high prio and therefore should try to reclaim as much as |
383 | * possible. | |
384 | */ | |
385 | while (total_scan >= batch_size || | |
d5bc5fd3 | 386 | total_scan >= freeable) { |
a0b02131 | 387 | unsigned long ret; |
0b1fb40a | 388 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 389 | |
0b1fb40a | 390 | shrinkctl->nr_to_scan = nr_to_scan; |
a0b02131 DC |
391 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
392 | if (ret == SHRINK_STOP) | |
393 | break; | |
394 | freed += ret; | |
1d3d4437 | 395 | |
0b1fb40a VD |
396 | count_vm_events(SLABS_SCANNED, nr_to_scan); |
397 | total_scan -= nr_to_scan; | |
5f33a080 | 398 | scanned += nr_to_scan; |
1d3d4437 GC |
399 | |
400 | cond_resched(); | |
401 | } | |
402 | ||
5f33a080 SL |
403 | if (next_deferred >= scanned) |
404 | next_deferred -= scanned; | |
405 | else | |
406 | next_deferred = 0; | |
1d3d4437 GC |
407 | /* |
408 | * move the unused scan count back into the shrinker in a | |
409 | * manner that handles concurrent updates. If we exhausted the | |
410 | * scan, there is no need to do an update. | |
411 | */ | |
5f33a080 SL |
412 | if (next_deferred > 0) |
413 | new_nr = atomic_long_add_return(next_deferred, | |
1d3d4437 GC |
414 | &shrinker->nr_deferred[nid]); |
415 | else | |
416 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
417 | ||
df9024a8 | 418 | trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); |
1d3d4437 | 419 | return freed; |
1495f230 YH |
420 | } |
421 | ||
6b4f7799 | 422 | /** |
cb731d6c | 423 | * shrink_slab - shrink slab caches |
6b4f7799 JW |
424 | * @gfp_mask: allocation context |
425 | * @nid: node whose slab caches to target | |
cb731d6c | 426 | * @memcg: memory cgroup whose slab caches to target |
6b4f7799 JW |
427 | * @nr_scanned: pressure numerator |
428 | * @nr_eligible: pressure denominator | |
1da177e4 | 429 | * |
6b4f7799 | 430 | * Call the shrink functions to age shrinkable caches. |
1da177e4 | 431 | * |
6b4f7799 JW |
432 | * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, |
433 | * unaware shrinkers will receive a node id of 0 instead. | |
1da177e4 | 434 | * |
cb731d6c VD |
435 | * @memcg specifies the memory cgroup to target. If it is not NULL, |
436 | * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan | |
0fc9f58a VD |
437 | * objects from the memory cgroup specified. Otherwise, only unaware |
438 | * shrinkers are called. | |
cb731d6c | 439 | * |
6b4f7799 JW |
440 | * @nr_scanned and @nr_eligible form a ratio that indicate how much of |
441 | * the available objects should be scanned. Page reclaim for example | |
442 | * passes the number of pages scanned and the number of pages on the | |
443 | * LRU lists that it considered on @nid, plus a bias in @nr_scanned | |
444 | * when it encountered mapped pages. The ratio is further biased by | |
445 | * the ->seeks setting of the shrink function, which indicates the | |
446 | * cost to recreate an object relative to that of an LRU page. | |
b15e0905 | 447 | * |
6b4f7799 | 448 | * Returns the number of reclaimed slab objects. |
1da177e4 | 449 | */ |
cb731d6c VD |
450 | static unsigned long shrink_slab(gfp_t gfp_mask, int nid, |
451 | struct mem_cgroup *memcg, | |
452 | unsigned long nr_scanned, | |
453 | unsigned long nr_eligible) | |
1da177e4 LT |
454 | { |
455 | struct shrinker *shrinker; | |
24f7c6b9 | 456 | unsigned long freed = 0; |
1da177e4 | 457 | |
0fc9f58a | 458 | if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg))) |
cb731d6c VD |
459 | return 0; |
460 | ||
6b4f7799 JW |
461 | if (nr_scanned == 0) |
462 | nr_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 463 | |
f06590bd | 464 | if (!down_read_trylock(&shrinker_rwsem)) { |
24f7c6b9 DC |
465 | /* |
466 | * If we would return 0, our callers would understand that we | |
467 | * have nothing else to shrink and give up trying. By returning | |
468 | * 1 we keep it going and assume we'll be able to shrink next | |
469 | * time. | |
470 | */ | |
471 | freed = 1; | |
f06590bd MK |
472 | goto out; |
473 | } | |
1da177e4 LT |
474 | |
475 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
6b4f7799 JW |
476 | struct shrink_control sc = { |
477 | .gfp_mask = gfp_mask, | |
478 | .nid = nid, | |
cb731d6c | 479 | .memcg = memcg, |
6b4f7799 | 480 | }; |
ec97097b | 481 | |
0fc9f58a VD |
482 | /* |
483 | * If kernel memory accounting is disabled, we ignore | |
484 | * SHRINKER_MEMCG_AWARE flag and call all shrinkers | |
485 | * passing NULL for memcg. | |
486 | */ | |
487 | if (memcg_kmem_enabled() && | |
488 | !!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE)) | |
cb731d6c VD |
489 | continue; |
490 | ||
6b4f7799 JW |
491 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) |
492 | sc.nid = 0; | |
1da177e4 | 493 | |
cb731d6c | 494 | freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible); |
1da177e4 | 495 | } |
6b4f7799 | 496 | |
1da177e4 | 497 | up_read(&shrinker_rwsem); |
f06590bd MK |
498 | out: |
499 | cond_resched(); | |
24f7c6b9 | 500 | return freed; |
1da177e4 LT |
501 | } |
502 | ||
cb731d6c VD |
503 | void drop_slab_node(int nid) |
504 | { | |
505 | unsigned long freed; | |
506 | ||
507 | do { | |
508 | struct mem_cgroup *memcg = NULL; | |
509 | ||
510 | freed = 0; | |
511 | do { | |
512 | freed += shrink_slab(GFP_KERNEL, nid, memcg, | |
513 | 1000, 1000); | |
514 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); | |
515 | } while (freed > 10); | |
516 | } | |
517 | ||
518 | void drop_slab(void) | |
519 | { | |
520 | int nid; | |
521 | ||
522 | for_each_online_node(nid) | |
523 | drop_slab_node(nid); | |
524 | } | |
525 | ||
1da177e4 LT |
526 | static inline int is_page_cache_freeable(struct page *page) |
527 | { | |
ceddc3a5 JW |
528 | /* |
529 | * A freeable page cache page is referenced only by the caller | |
530 | * that isolated the page, the page cache radix tree and | |
531 | * optional buffer heads at page->private. | |
532 | */ | |
edcf4748 | 533 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
534 | } |
535 | ||
703c2708 | 536 | static int may_write_to_inode(struct inode *inode, struct scan_control *sc) |
1da177e4 | 537 | { |
930d9152 | 538 | if (current->flags & PF_SWAPWRITE) |
1da177e4 | 539 | return 1; |
703c2708 | 540 | if (!inode_write_congested(inode)) |
1da177e4 | 541 | return 1; |
703c2708 | 542 | if (inode_to_bdi(inode) == current->backing_dev_info) |
1da177e4 LT |
543 | return 1; |
544 | return 0; | |
545 | } | |
546 | ||
547 | /* | |
548 | * We detected a synchronous write error writing a page out. Probably | |
549 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
550 | * fsync(), msync() or close(). | |
551 | * | |
552 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
553 | * prevents it from being freed up. But we have a ref on the page and once | |
554 | * that page is locked, the mapping is pinned. | |
555 | * | |
556 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
557 | * __GFP_FS. | |
558 | */ | |
559 | static void handle_write_error(struct address_space *mapping, | |
560 | struct page *page, int error) | |
561 | { | |
7eaceacc | 562 | lock_page(page); |
3e9f45bd GC |
563 | if (page_mapping(page) == mapping) |
564 | mapping_set_error(mapping, error); | |
1da177e4 LT |
565 | unlock_page(page); |
566 | } | |
567 | ||
04e62a29 CL |
568 | /* possible outcome of pageout() */ |
569 | typedef enum { | |
570 | /* failed to write page out, page is locked */ | |
571 | PAGE_KEEP, | |
572 | /* move page to the active list, page is locked */ | |
573 | PAGE_ACTIVATE, | |
574 | /* page has been sent to the disk successfully, page is unlocked */ | |
575 | PAGE_SUCCESS, | |
576 | /* page is clean and locked */ | |
577 | PAGE_CLEAN, | |
578 | } pageout_t; | |
579 | ||
1da177e4 | 580 | /* |
1742f19f AM |
581 | * pageout is called by shrink_page_list() for each dirty page. |
582 | * Calls ->writepage(). | |
1da177e4 | 583 | */ |
c661b078 | 584 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 585 | struct scan_control *sc) |
1da177e4 LT |
586 | { |
587 | /* | |
588 | * If the page is dirty, only perform writeback if that write | |
589 | * will be non-blocking. To prevent this allocation from being | |
590 | * stalled by pagecache activity. But note that there may be | |
591 | * stalls if we need to run get_block(). We could test | |
592 | * PagePrivate for that. | |
593 | * | |
8174202b | 594 | * If this process is currently in __generic_file_write_iter() against |
1da177e4 LT |
595 | * this page's queue, we can perform writeback even if that |
596 | * will block. | |
597 | * | |
598 | * If the page is swapcache, write it back even if that would | |
599 | * block, for some throttling. This happens by accident, because | |
600 | * swap_backing_dev_info is bust: it doesn't reflect the | |
601 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
602 | */ |
603 | if (!is_page_cache_freeable(page)) | |
604 | return PAGE_KEEP; | |
605 | if (!mapping) { | |
606 | /* | |
607 | * Some data journaling orphaned pages can have | |
608 | * page->mapping == NULL while being dirty with clean buffers. | |
609 | */ | |
266cf658 | 610 | if (page_has_private(page)) { |
1da177e4 LT |
611 | if (try_to_free_buffers(page)) { |
612 | ClearPageDirty(page); | |
b1de0d13 | 613 | pr_info("%s: orphaned page\n", __func__); |
1da177e4 LT |
614 | return PAGE_CLEAN; |
615 | } | |
616 | } | |
617 | return PAGE_KEEP; | |
618 | } | |
619 | if (mapping->a_ops->writepage == NULL) | |
620 | return PAGE_ACTIVATE; | |
703c2708 | 621 | if (!may_write_to_inode(mapping->host, sc)) |
1da177e4 LT |
622 | return PAGE_KEEP; |
623 | ||
624 | if (clear_page_dirty_for_io(page)) { | |
625 | int res; | |
626 | struct writeback_control wbc = { | |
627 | .sync_mode = WB_SYNC_NONE, | |
628 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
629 | .range_start = 0, |
630 | .range_end = LLONG_MAX, | |
1da177e4 LT |
631 | .for_reclaim = 1, |
632 | }; | |
633 | ||
634 | SetPageReclaim(page); | |
635 | res = mapping->a_ops->writepage(page, &wbc); | |
636 | if (res < 0) | |
637 | handle_write_error(mapping, page, res); | |
994fc28c | 638 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
639 | ClearPageReclaim(page); |
640 | return PAGE_ACTIVATE; | |
641 | } | |
c661b078 | 642 | |
1da177e4 LT |
643 | if (!PageWriteback(page)) { |
644 | /* synchronous write or broken a_ops? */ | |
645 | ClearPageReclaim(page); | |
646 | } | |
3aa23851 | 647 | trace_mm_vmscan_writepage(page); |
c4a25635 | 648 | inc_node_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
649 | return PAGE_SUCCESS; |
650 | } | |
651 | ||
652 | return PAGE_CLEAN; | |
653 | } | |
654 | ||
a649fd92 | 655 | /* |
e286781d NP |
656 | * Same as remove_mapping, but if the page is removed from the mapping, it |
657 | * gets returned with a refcount of 0. | |
a649fd92 | 658 | */ |
a528910e JW |
659 | static int __remove_mapping(struct address_space *mapping, struct page *page, |
660 | bool reclaimed) | |
49d2e9cc | 661 | { |
c4843a75 | 662 | unsigned long flags; |
c4843a75 | 663 | |
28e4d965 NP |
664 | BUG_ON(!PageLocked(page)); |
665 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 666 | |
c4843a75 | 667 | spin_lock_irqsave(&mapping->tree_lock, flags); |
49d2e9cc | 668 | /* |
0fd0e6b0 NP |
669 | * The non racy check for a busy page. |
670 | * | |
671 | * Must be careful with the order of the tests. When someone has | |
672 | * a ref to the page, it may be possible that they dirty it then | |
673 | * drop the reference. So if PageDirty is tested before page_count | |
674 | * here, then the following race may occur: | |
675 | * | |
676 | * get_user_pages(&page); | |
677 | * [user mapping goes away] | |
678 | * write_to(page); | |
679 | * !PageDirty(page) [good] | |
680 | * SetPageDirty(page); | |
681 | * put_page(page); | |
682 | * !page_count(page) [good, discard it] | |
683 | * | |
684 | * [oops, our write_to data is lost] | |
685 | * | |
686 | * Reversing the order of the tests ensures such a situation cannot | |
687 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
0139aa7b | 688 | * load is not satisfied before that of page->_refcount. |
0fd0e6b0 NP |
689 | * |
690 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
691 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 692 | */ |
fe896d18 | 693 | if (!page_ref_freeze(page, 2)) |
49d2e9cc | 694 | goto cannot_free; |
e286781d NP |
695 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
696 | if (unlikely(PageDirty(page))) { | |
fe896d18 | 697 | page_ref_unfreeze(page, 2); |
49d2e9cc | 698 | goto cannot_free; |
e286781d | 699 | } |
49d2e9cc CL |
700 | |
701 | if (PageSwapCache(page)) { | |
702 | swp_entry_t swap = { .val = page_private(page) }; | |
0a31bc97 | 703 | mem_cgroup_swapout(page, swap); |
49d2e9cc | 704 | __delete_from_swap_cache(page); |
c4843a75 | 705 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
0a31bc97 | 706 | swapcache_free(swap); |
e286781d | 707 | } else { |
6072d13c | 708 | void (*freepage)(struct page *); |
a528910e | 709 | void *shadow = NULL; |
6072d13c LT |
710 | |
711 | freepage = mapping->a_ops->freepage; | |
a528910e JW |
712 | /* |
713 | * Remember a shadow entry for reclaimed file cache in | |
714 | * order to detect refaults, thus thrashing, later on. | |
715 | * | |
716 | * But don't store shadows in an address space that is | |
717 | * already exiting. This is not just an optizimation, | |
718 | * inode reclaim needs to empty out the radix tree or | |
719 | * the nodes are lost. Don't plant shadows behind its | |
720 | * back. | |
f9fe48be RZ |
721 | * |
722 | * We also don't store shadows for DAX mappings because the | |
723 | * only page cache pages found in these are zero pages | |
724 | * covering holes, and because we don't want to mix DAX | |
725 | * exceptional entries and shadow exceptional entries in the | |
726 | * same page_tree. | |
a528910e JW |
727 | */ |
728 | if (reclaimed && page_is_file_cache(page) && | |
f9fe48be | 729 | !mapping_exiting(mapping) && !dax_mapping(mapping)) |
a528910e | 730 | shadow = workingset_eviction(mapping, page); |
62cccb8c | 731 | __delete_from_page_cache(page, shadow); |
c4843a75 | 732 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
6072d13c LT |
733 | |
734 | if (freepage != NULL) | |
735 | freepage(page); | |
49d2e9cc CL |
736 | } |
737 | ||
49d2e9cc CL |
738 | return 1; |
739 | ||
740 | cannot_free: | |
c4843a75 | 741 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
49d2e9cc CL |
742 | return 0; |
743 | } | |
744 | ||
e286781d NP |
745 | /* |
746 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
747 | * someone else has a ref on the page, abort and return 0. If it was | |
748 | * successfully detached, return 1. Assumes the caller has a single ref on | |
749 | * this page. | |
750 | */ | |
751 | int remove_mapping(struct address_space *mapping, struct page *page) | |
752 | { | |
a528910e | 753 | if (__remove_mapping(mapping, page, false)) { |
e286781d NP |
754 | /* |
755 | * Unfreezing the refcount with 1 rather than 2 effectively | |
756 | * drops the pagecache ref for us without requiring another | |
757 | * atomic operation. | |
758 | */ | |
fe896d18 | 759 | page_ref_unfreeze(page, 1); |
e286781d NP |
760 | return 1; |
761 | } | |
762 | return 0; | |
763 | } | |
764 | ||
894bc310 LS |
765 | /** |
766 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
767 | * @page: page to be put back to appropriate lru list | |
768 | * | |
769 | * Add previously isolated @page to appropriate LRU list. | |
770 | * Page may still be unevictable for other reasons. | |
771 | * | |
772 | * lru_lock must not be held, interrupts must be enabled. | |
773 | */ | |
894bc310 LS |
774 | void putback_lru_page(struct page *page) |
775 | { | |
0ec3b74c | 776 | bool is_unevictable; |
bbfd28ee | 777 | int was_unevictable = PageUnevictable(page); |
894bc310 | 778 | |
309381fe | 779 | VM_BUG_ON_PAGE(PageLRU(page), page); |
894bc310 LS |
780 | |
781 | redo: | |
782 | ClearPageUnevictable(page); | |
783 | ||
39b5f29a | 784 | if (page_evictable(page)) { |
894bc310 LS |
785 | /* |
786 | * For evictable pages, we can use the cache. | |
787 | * In event of a race, worst case is we end up with an | |
788 | * unevictable page on [in]active list. | |
789 | * We know how to handle that. | |
790 | */ | |
0ec3b74c | 791 | is_unevictable = false; |
c53954a0 | 792 | lru_cache_add(page); |
894bc310 LS |
793 | } else { |
794 | /* | |
795 | * Put unevictable pages directly on zone's unevictable | |
796 | * list. | |
797 | */ | |
0ec3b74c | 798 | is_unevictable = true; |
894bc310 | 799 | add_page_to_unevictable_list(page); |
6a7b9548 | 800 | /* |
21ee9f39 MK |
801 | * When racing with an mlock or AS_UNEVICTABLE clearing |
802 | * (page is unlocked) make sure that if the other thread | |
803 | * does not observe our setting of PG_lru and fails | |
24513264 | 804 | * isolation/check_move_unevictable_pages, |
21ee9f39 | 805 | * we see PG_mlocked/AS_UNEVICTABLE cleared below and move |
6a7b9548 JW |
806 | * the page back to the evictable list. |
807 | * | |
21ee9f39 | 808 | * The other side is TestClearPageMlocked() or shmem_lock(). |
6a7b9548 JW |
809 | */ |
810 | smp_mb(); | |
894bc310 | 811 | } |
894bc310 LS |
812 | |
813 | /* | |
814 | * page's status can change while we move it among lru. If an evictable | |
815 | * page is on unevictable list, it never be freed. To avoid that, | |
816 | * check after we added it to the list, again. | |
817 | */ | |
0ec3b74c | 818 | if (is_unevictable && page_evictable(page)) { |
894bc310 LS |
819 | if (!isolate_lru_page(page)) { |
820 | put_page(page); | |
821 | goto redo; | |
822 | } | |
823 | /* This means someone else dropped this page from LRU | |
824 | * So, it will be freed or putback to LRU again. There is | |
825 | * nothing to do here. | |
826 | */ | |
827 | } | |
828 | ||
0ec3b74c | 829 | if (was_unevictable && !is_unevictable) |
bbfd28ee | 830 | count_vm_event(UNEVICTABLE_PGRESCUED); |
0ec3b74c | 831 | else if (!was_unevictable && is_unevictable) |
bbfd28ee LS |
832 | count_vm_event(UNEVICTABLE_PGCULLED); |
833 | ||
894bc310 LS |
834 | put_page(page); /* drop ref from isolate */ |
835 | } | |
836 | ||
dfc8d636 JW |
837 | enum page_references { |
838 | PAGEREF_RECLAIM, | |
839 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 840 | PAGEREF_KEEP, |
dfc8d636 JW |
841 | PAGEREF_ACTIVATE, |
842 | }; | |
843 | ||
844 | static enum page_references page_check_references(struct page *page, | |
845 | struct scan_control *sc) | |
846 | { | |
64574746 | 847 | int referenced_ptes, referenced_page; |
dfc8d636 | 848 | unsigned long vm_flags; |
dfc8d636 | 849 | |
c3ac9a8a JW |
850 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
851 | &vm_flags); | |
64574746 | 852 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 853 | |
dfc8d636 JW |
854 | /* |
855 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
856 | * move the page to the unevictable list. | |
857 | */ | |
858 | if (vm_flags & VM_LOCKED) | |
859 | return PAGEREF_RECLAIM; | |
860 | ||
64574746 | 861 | if (referenced_ptes) { |
e4898273 | 862 | if (PageSwapBacked(page)) |
64574746 JW |
863 | return PAGEREF_ACTIVATE; |
864 | /* | |
865 | * All mapped pages start out with page table | |
866 | * references from the instantiating fault, so we need | |
867 | * to look twice if a mapped file page is used more | |
868 | * than once. | |
869 | * | |
870 | * Mark it and spare it for another trip around the | |
871 | * inactive list. Another page table reference will | |
872 | * lead to its activation. | |
873 | * | |
874 | * Note: the mark is set for activated pages as well | |
875 | * so that recently deactivated but used pages are | |
876 | * quickly recovered. | |
877 | */ | |
878 | SetPageReferenced(page); | |
879 | ||
34dbc67a | 880 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
881 | return PAGEREF_ACTIVATE; |
882 | ||
c909e993 KK |
883 | /* |
884 | * Activate file-backed executable pages after first usage. | |
885 | */ | |
886 | if (vm_flags & VM_EXEC) | |
887 | return PAGEREF_ACTIVATE; | |
888 | ||
64574746 JW |
889 | return PAGEREF_KEEP; |
890 | } | |
dfc8d636 JW |
891 | |
892 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 893 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
894 | return PAGEREF_RECLAIM_CLEAN; |
895 | ||
896 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
897 | } |
898 | ||
e2be15f6 MG |
899 | /* Check if a page is dirty or under writeback */ |
900 | static void page_check_dirty_writeback(struct page *page, | |
901 | bool *dirty, bool *writeback) | |
902 | { | |
b4597226 MG |
903 | struct address_space *mapping; |
904 | ||
e2be15f6 MG |
905 | /* |
906 | * Anonymous pages are not handled by flushers and must be written | |
907 | * from reclaim context. Do not stall reclaim based on them | |
908 | */ | |
909 | if (!page_is_file_cache(page)) { | |
910 | *dirty = false; | |
911 | *writeback = false; | |
912 | return; | |
913 | } | |
914 | ||
915 | /* By default assume that the page flags are accurate */ | |
916 | *dirty = PageDirty(page); | |
917 | *writeback = PageWriteback(page); | |
b4597226 MG |
918 | |
919 | /* Verify dirty/writeback state if the filesystem supports it */ | |
920 | if (!page_has_private(page)) | |
921 | return; | |
922 | ||
923 | mapping = page_mapping(page); | |
924 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
925 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
926 | } |
927 | ||
3c710c1a MH |
928 | struct reclaim_stat { |
929 | unsigned nr_dirty; | |
930 | unsigned nr_unqueued_dirty; | |
931 | unsigned nr_congested; | |
932 | unsigned nr_writeback; | |
933 | unsigned nr_immediate; | |
5bccd166 MH |
934 | unsigned nr_activate; |
935 | unsigned nr_ref_keep; | |
936 | unsigned nr_unmap_fail; | |
3c710c1a MH |
937 | }; |
938 | ||
1da177e4 | 939 | /* |
1742f19f | 940 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 941 | */ |
1742f19f | 942 | static unsigned long shrink_page_list(struct list_head *page_list, |
599d0c95 | 943 | struct pglist_data *pgdat, |
f84f6e2b | 944 | struct scan_control *sc, |
02c6de8d | 945 | enum ttu_flags ttu_flags, |
3c710c1a | 946 | struct reclaim_stat *stat, |
02c6de8d | 947 | bool force_reclaim) |
1da177e4 LT |
948 | { |
949 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 950 | LIST_HEAD(free_pages); |
1da177e4 | 951 | int pgactivate = 0; |
3c710c1a MH |
952 | unsigned nr_unqueued_dirty = 0; |
953 | unsigned nr_dirty = 0; | |
954 | unsigned nr_congested = 0; | |
955 | unsigned nr_reclaimed = 0; | |
956 | unsigned nr_writeback = 0; | |
957 | unsigned nr_immediate = 0; | |
5bccd166 MH |
958 | unsigned nr_ref_keep = 0; |
959 | unsigned nr_unmap_fail = 0; | |
1da177e4 LT |
960 | |
961 | cond_resched(); | |
962 | ||
1da177e4 LT |
963 | while (!list_empty(page_list)) { |
964 | struct address_space *mapping; | |
965 | struct page *page; | |
966 | int may_enter_fs; | |
02c6de8d | 967 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 968 | bool dirty, writeback; |
854e9ed0 MK |
969 | bool lazyfree = false; |
970 | int ret = SWAP_SUCCESS; | |
1da177e4 LT |
971 | |
972 | cond_resched(); | |
973 | ||
974 | page = lru_to_page(page_list); | |
975 | list_del(&page->lru); | |
976 | ||
529ae9aa | 977 | if (!trylock_page(page)) |
1da177e4 LT |
978 | goto keep; |
979 | ||
309381fe | 980 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
981 | |
982 | sc->nr_scanned++; | |
80e43426 | 983 | |
39b5f29a | 984 | if (unlikely(!page_evictable(page))) |
b291f000 | 985 | goto cull_mlocked; |
894bc310 | 986 | |
a6dc60f8 | 987 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
988 | goto keep_locked; |
989 | ||
1da177e4 LT |
990 | /* Double the slab pressure for mapped and swapcache pages */ |
991 | if (page_mapped(page) || PageSwapCache(page)) | |
992 | sc->nr_scanned++; | |
993 | ||
c661b078 AW |
994 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
995 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
996 | ||
e2be15f6 MG |
997 | /* |
998 | * The number of dirty pages determines if a zone is marked | |
999 | * reclaim_congested which affects wait_iff_congested. kswapd | |
1000 | * will stall and start writing pages if the tail of the LRU | |
1001 | * is all dirty unqueued pages. | |
1002 | */ | |
1003 | page_check_dirty_writeback(page, &dirty, &writeback); | |
1004 | if (dirty || writeback) | |
1005 | nr_dirty++; | |
1006 | ||
1007 | if (dirty && !writeback) | |
1008 | nr_unqueued_dirty++; | |
1009 | ||
d04e8acd MG |
1010 | /* |
1011 | * Treat this page as congested if the underlying BDI is or if | |
1012 | * pages are cycling through the LRU so quickly that the | |
1013 | * pages marked for immediate reclaim are making it to the | |
1014 | * end of the LRU a second time. | |
1015 | */ | |
e2be15f6 | 1016 | mapping = page_mapping(page); |
1da58ee2 | 1017 | if (((dirty || writeback) && mapping && |
703c2708 | 1018 | inode_write_congested(mapping->host)) || |
d04e8acd | 1019 | (writeback && PageReclaim(page))) |
e2be15f6 MG |
1020 | nr_congested++; |
1021 | ||
283aba9f MG |
1022 | /* |
1023 | * If a page at the tail of the LRU is under writeback, there | |
1024 | * are three cases to consider. | |
1025 | * | |
1026 | * 1) If reclaim is encountering an excessive number of pages | |
1027 | * under writeback and this page is both under writeback and | |
1028 | * PageReclaim then it indicates that pages are being queued | |
1029 | * for IO but are being recycled through the LRU before the | |
1030 | * IO can complete. Waiting on the page itself risks an | |
1031 | * indefinite stall if it is impossible to writeback the | |
1032 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
1033 | * note that the LRU is being scanned too quickly and the |
1034 | * caller can stall after page list has been processed. | |
283aba9f | 1035 | * |
97c9341f | 1036 | * 2) Global or new memcg reclaim encounters a page that is |
ecf5fc6e MH |
1037 | * not marked for immediate reclaim, or the caller does not |
1038 | * have __GFP_FS (or __GFP_IO if it's simply going to swap, | |
1039 | * not to fs). In this case mark the page for immediate | |
97c9341f | 1040 | * reclaim and continue scanning. |
283aba9f | 1041 | * |
ecf5fc6e MH |
1042 | * Require may_enter_fs because we would wait on fs, which |
1043 | * may not have submitted IO yet. And the loop driver might | |
283aba9f MG |
1044 | * enter reclaim, and deadlock if it waits on a page for |
1045 | * which it is needed to do the write (loop masks off | |
1046 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
1047 | * would probably show more reasons. | |
1048 | * | |
7fadc820 | 1049 | * 3) Legacy memcg encounters a page that is already marked |
283aba9f MG |
1050 | * PageReclaim. memcg does not have any dirty pages |
1051 | * throttling so we could easily OOM just because too many | |
1052 | * pages are in writeback and there is nothing else to | |
1053 | * reclaim. Wait for the writeback to complete. | |
c55e8d03 JW |
1054 | * |
1055 | * In cases 1) and 2) we activate the pages to get them out of | |
1056 | * the way while we continue scanning for clean pages on the | |
1057 | * inactive list and refilling from the active list. The | |
1058 | * observation here is that waiting for disk writes is more | |
1059 | * expensive than potentially causing reloads down the line. | |
1060 | * Since they're marked for immediate reclaim, they won't put | |
1061 | * memory pressure on the cache working set any longer than it | |
1062 | * takes to write them to disk. | |
283aba9f | 1063 | */ |
c661b078 | 1064 | if (PageWriteback(page)) { |
283aba9f MG |
1065 | /* Case 1 above */ |
1066 | if (current_is_kswapd() && | |
1067 | PageReclaim(page) && | |
599d0c95 | 1068 | test_bit(PGDAT_WRITEBACK, &pgdat->flags)) { |
b1a6f21e | 1069 | nr_immediate++; |
c55e8d03 | 1070 | goto activate_locked; |
283aba9f MG |
1071 | |
1072 | /* Case 2 above */ | |
97c9341f | 1073 | } else if (sane_reclaim(sc) || |
ecf5fc6e | 1074 | !PageReclaim(page) || !may_enter_fs) { |
c3b94f44 HD |
1075 | /* |
1076 | * This is slightly racy - end_page_writeback() | |
1077 | * might have just cleared PageReclaim, then | |
1078 | * setting PageReclaim here end up interpreted | |
1079 | * as PageReadahead - but that does not matter | |
1080 | * enough to care. What we do want is for this | |
1081 | * page to have PageReclaim set next time memcg | |
1082 | * reclaim reaches the tests above, so it will | |
1083 | * then wait_on_page_writeback() to avoid OOM; | |
1084 | * and it's also appropriate in global reclaim. | |
1085 | */ | |
1086 | SetPageReclaim(page); | |
e62e384e | 1087 | nr_writeback++; |
c55e8d03 | 1088 | goto activate_locked; |
283aba9f MG |
1089 | |
1090 | /* Case 3 above */ | |
1091 | } else { | |
7fadc820 | 1092 | unlock_page(page); |
283aba9f | 1093 | wait_on_page_writeback(page); |
7fadc820 HD |
1094 | /* then go back and try same page again */ |
1095 | list_add_tail(&page->lru, page_list); | |
1096 | continue; | |
e62e384e | 1097 | } |
c661b078 | 1098 | } |
1da177e4 | 1099 | |
02c6de8d MK |
1100 | if (!force_reclaim) |
1101 | references = page_check_references(page, sc); | |
1102 | ||
dfc8d636 JW |
1103 | switch (references) { |
1104 | case PAGEREF_ACTIVATE: | |
1da177e4 | 1105 | goto activate_locked; |
64574746 | 1106 | case PAGEREF_KEEP: |
5bccd166 | 1107 | nr_ref_keep++; |
64574746 | 1108 | goto keep_locked; |
dfc8d636 JW |
1109 | case PAGEREF_RECLAIM: |
1110 | case PAGEREF_RECLAIM_CLEAN: | |
1111 | ; /* try to reclaim the page below */ | |
1112 | } | |
1da177e4 | 1113 | |
1da177e4 LT |
1114 | /* |
1115 | * Anonymous process memory has backing store? | |
1116 | * Try to allocate it some swap space here. | |
1117 | */ | |
b291f000 | 1118 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
1119 | if (!(sc->gfp_mask & __GFP_IO)) |
1120 | goto keep_locked; | |
5bc7b8ac | 1121 | if (!add_to_swap(page, page_list)) |
1da177e4 | 1122 | goto activate_locked; |
854e9ed0 | 1123 | lazyfree = true; |
63eb6b93 | 1124 | may_enter_fs = 1; |
1da177e4 | 1125 | |
e2be15f6 MG |
1126 | /* Adding to swap updated mapping */ |
1127 | mapping = page_mapping(page); | |
7751b2da KS |
1128 | } else if (unlikely(PageTransHuge(page))) { |
1129 | /* Split file THP */ | |
1130 | if (split_huge_page_to_list(page, page_list)) | |
1131 | goto keep_locked; | |
e2be15f6 | 1132 | } |
1da177e4 | 1133 | |
7751b2da KS |
1134 | VM_BUG_ON_PAGE(PageTransHuge(page), page); |
1135 | ||
1da177e4 LT |
1136 | /* |
1137 | * The page is mapped into the page tables of one or more | |
1138 | * processes. Try to unmap it here. | |
1139 | */ | |
1140 | if (page_mapped(page) && mapping) { | |
854e9ed0 MK |
1141 | switch (ret = try_to_unmap(page, lazyfree ? |
1142 | (ttu_flags | TTU_BATCH_FLUSH | TTU_LZFREE) : | |
1143 | (ttu_flags | TTU_BATCH_FLUSH))) { | |
1da177e4 | 1144 | case SWAP_FAIL: |
5bccd166 | 1145 | nr_unmap_fail++; |
1da177e4 LT |
1146 | goto activate_locked; |
1147 | case SWAP_AGAIN: | |
1148 | goto keep_locked; | |
b291f000 NP |
1149 | case SWAP_MLOCK: |
1150 | goto cull_mlocked; | |
854e9ed0 MK |
1151 | case SWAP_LZFREE: |
1152 | goto lazyfree; | |
1da177e4 LT |
1153 | case SWAP_SUCCESS: |
1154 | ; /* try to free the page below */ | |
1155 | } | |
1156 | } | |
1157 | ||
1158 | if (PageDirty(page)) { | |
ee72886d | 1159 | /* |
4eda4823 JW |
1160 | * Only kswapd can writeback filesystem pages |
1161 | * to avoid risk of stack overflow. But avoid | |
1162 | * injecting inefficient single-page IO into | |
1163 | * flusher writeback as much as possible: only | |
1164 | * write pages when we've encountered many | |
1165 | * dirty pages, and when we've already scanned | |
1166 | * the rest of the LRU for clean pages and see | |
1167 | * the same dirty pages again (PageReclaim). | |
ee72886d | 1168 | */ |
f84f6e2b | 1169 | if (page_is_file_cache(page) && |
4eda4823 JW |
1170 | (!current_is_kswapd() || !PageReclaim(page) || |
1171 | !test_bit(PGDAT_DIRTY, &pgdat->flags))) { | |
49ea7eb6 MG |
1172 | /* |
1173 | * Immediately reclaim when written back. | |
1174 | * Similar in principal to deactivate_page() | |
1175 | * except we already have the page isolated | |
1176 | * and know it's dirty | |
1177 | */ | |
c4a25635 | 1178 | inc_node_page_state(page, NR_VMSCAN_IMMEDIATE); |
49ea7eb6 MG |
1179 | SetPageReclaim(page); |
1180 | ||
c55e8d03 | 1181 | goto activate_locked; |
ee72886d MG |
1182 | } |
1183 | ||
dfc8d636 | 1184 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 1185 | goto keep_locked; |
4dd4b920 | 1186 | if (!may_enter_fs) |
1da177e4 | 1187 | goto keep_locked; |
52a8363e | 1188 | if (!sc->may_writepage) |
1da177e4 LT |
1189 | goto keep_locked; |
1190 | ||
d950c947 MG |
1191 | /* |
1192 | * Page is dirty. Flush the TLB if a writable entry | |
1193 | * potentially exists to avoid CPU writes after IO | |
1194 | * starts and then write it out here. | |
1195 | */ | |
1196 | try_to_unmap_flush_dirty(); | |
7d3579e8 | 1197 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1198 | case PAGE_KEEP: |
1199 | goto keep_locked; | |
1200 | case PAGE_ACTIVATE: | |
1201 | goto activate_locked; | |
1202 | case PAGE_SUCCESS: | |
7d3579e8 | 1203 | if (PageWriteback(page)) |
41ac1999 | 1204 | goto keep; |
7d3579e8 | 1205 | if (PageDirty(page)) |
1da177e4 | 1206 | goto keep; |
7d3579e8 | 1207 | |
1da177e4 LT |
1208 | /* |
1209 | * A synchronous write - probably a ramdisk. Go | |
1210 | * ahead and try to reclaim the page. | |
1211 | */ | |
529ae9aa | 1212 | if (!trylock_page(page)) |
1da177e4 LT |
1213 | goto keep; |
1214 | if (PageDirty(page) || PageWriteback(page)) | |
1215 | goto keep_locked; | |
1216 | mapping = page_mapping(page); | |
1217 | case PAGE_CLEAN: | |
1218 | ; /* try to free the page below */ | |
1219 | } | |
1220 | } | |
1221 | ||
1222 | /* | |
1223 | * If the page has buffers, try to free the buffer mappings | |
1224 | * associated with this page. If we succeed we try to free | |
1225 | * the page as well. | |
1226 | * | |
1227 | * We do this even if the page is PageDirty(). | |
1228 | * try_to_release_page() does not perform I/O, but it is | |
1229 | * possible for a page to have PageDirty set, but it is actually | |
1230 | * clean (all its buffers are clean). This happens if the | |
1231 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1232 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1233 | * try_to_release_page() will discover that cleanness and will |
1234 | * drop the buffers and mark the page clean - it can be freed. | |
1235 | * | |
1236 | * Rarely, pages can have buffers and no ->mapping. These are | |
1237 | * the pages which were not successfully invalidated in | |
1238 | * truncate_complete_page(). We try to drop those buffers here | |
1239 | * and if that worked, and the page is no longer mapped into | |
1240 | * process address space (page_count == 1) it can be freed. | |
1241 | * Otherwise, leave the page on the LRU so it is swappable. | |
1242 | */ | |
266cf658 | 1243 | if (page_has_private(page)) { |
1da177e4 LT |
1244 | if (!try_to_release_page(page, sc->gfp_mask)) |
1245 | goto activate_locked; | |
e286781d NP |
1246 | if (!mapping && page_count(page) == 1) { |
1247 | unlock_page(page); | |
1248 | if (put_page_testzero(page)) | |
1249 | goto free_it; | |
1250 | else { | |
1251 | /* | |
1252 | * rare race with speculative reference. | |
1253 | * the speculative reference will free | |
1254 | * this page shortly, so we may | |
1255 | * increment nr_reclaimed here (and | |
1256 | * leave it off the LRU). | |
1257 | */ | |
1258 | nr_reclaimed++; | |
1259 | continue; | |
1260 | } | |
1261 | } | |
1da177e4 LT |
1262 | } |
1263 | ||
854e9ed0 | 1264 | lazyfree: |
a528910e | 1265 | if (!mapping || !__remove_mapping(mapping, page, true)) |
49d2e9cc | 1266 | goto keep_locked; |
1da177e4 | 1267 | |
a978d6f5 NP |
1268 | /* |
1269 | * At this point, we have no other references and there is | |
1270 | * no way to pick any more up (removed from LRU, removed | |
1271 | * from pagecache). Can use non-atomic bitops now (and | |
1272 | * we obviously don't have to worry about waking up a process | |
1273 | * waiting on the page lock, because there are no references. | |
1274 | */ | |
48c935ad | 1275 | __ClearPageLocked(page); |
e286781d | 1276 | free_it: |
854e9ed0 MK |
1277 | if (ret == SWAP_LZFREE) |
1278 | count_vm_event(PGLAZYFREED); | |
1279 | ||
05ff5137 | 1280 | nr_reclaimed++; |
abe4c3b5 MG |
1281 | |
1282 | /* | |
1283 | * Is there need to periodically free_page_list? It would | |
1284 | * appear not as the counts should be low | |
1285 | */ | |
1286 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1287 | continue; |
1288 | ||
b291f000 | 1289 | cull_mlocked: |
63d6c5ad HD |
1290 | if (PageSwapCache(page)) |
1291 | try_to_free_swap(page); | |
b291f000 | 1292 | unlock_page(page); |
c54839a7 | 1293 | list_add(&page->lru, &ret_pages); |
b291f000 NP |
1294 | continue; |
1295 | ||
1da177e4 | 1296 | activate_locked: |
68a22394 | 1297 | /* Not a candidate for swapping, so reclaim swap space. */ |
5ccc5aba | 1298 | if (PageSwapCache(page) && mem_cgroup_swap_full(page)) |
a2c43eed | 1299 | try_to_free_swap(page); |
309381fe | 1300 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1301 | SetPageActive(page); |
1302 | pgactivate++; | |
1303 | keep_locked: | |
1304 | unlock_page(page); | |
1305 | keep: | |
1306 | list_add(&page->lru, &ret_pages); | |
309381fe | 1307 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1308 | } |
abe4c3b5 | 1309 | |
747db954 | 1310 | mem_cgroup_uncharge_list(&free_pages); |
72b252ae | 1311 | try_to_unmap_flush(); |
b745bc85 | 1312 | free_hot_cold_page_list(&free_pages, true); |
abe4c3b5 | 1313 | |
1da177e4 | 1314 | list_splice(&ret_pages, page_list); |
f8891e5e | 1315 | count_vm_events(PGACTIVATE, pgactivate); |
0a31bc97 | 1316 | |
3c710c1a MH |
1317 | if (stat) { |
1318 | stat->nr_dirty = nr_dirty; | |
1319 | stat->nr_congested = nr_congested; | |
1320 | stat->nr_unqueued_dirty = nr_unqueued_dirty; | |
1321 | stat->nr_writeback = nr_writeback; | |
1322 | stat->nr_immediate = nr_immediate; | |
5bccd166 MH |
1323 | stat->nr_activate = pgactivate; |
1324 | stat->nr_ref_keep = nr_ref_keep; | |
1325 | stat->nr_unmap_fail = nr_unmap_fail; | |
3c710c1a | 1326 | } |
05ff5137 | 1327 | return nr_reclaimed; |
1da177e4 LT |
1328 | } |
1329 | ||
02c6de8d MK |
1330 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1331 | struct list_head *page_list) | |
1332 | { | |
1333 | struct scan_control sc = { | |
1334 | .gfp_mask = GFP_KERNEL, | |
1335 | .priority = DEF_PRIORITY, | |
1336 | .may_unmap = 1, | |
1337 | }; | |
3c710c1a | 1338 | unsigned long ret; |
02c6de8d MK |
1339 | struct page *page, *next; |
1340 | LIST_HEAD(clean_pages); | |
1341 | ||
1342 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e | 1343 | if (page_is_file_cache(page) && !PageDirty(page) && |
b1123ea6 | 1344 | !__PageMovable(page)) { |
02c6de8d MK |
1345 | ClearPageActive(page); |
1346 | list_move(&page->lru, &clean_pages); | |
1347 | } | |
1348 | } | |
1349 | ||
599d0c95 | 1350 | ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, |
3c710c1a | 1351 | TTU_UNMAP|TTU_IGNORE_ACCESS, NULL, true); |
02c6de8d | 1352 | list_splice(&clean_pages, page_list); |
599d0c95 | 1353 | mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); |
02c6de8d MK |
1354 | return ret; |
1355 | } | |
1356 | ||
5ad333eb AW |
1357 | /* |
1358 | * Attempt to remove the specified page from its LRU. Only take this page | |
1359 | * if it is of the appropriate PageActive status. Pages which are being | |
1360 | * freed elsewhere are also ignored. | |
1361 | * | |
1362 | * page: page to consider | |
1363 | * mode: one of the LRU isolation modes defined above | |
1364 | * | |
1365 | * returns 0 on success, -ve errno on failure. | |
1366 | */ | |
f3fd4a61 | 1367 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1368 | { |
1369 | int ret = -EINVAL; | |
1370 | ||
1371 | /* Only take pages on the LRU. */ | |
1372 | if (!PageLRU(page)) | |
1373 | return ret; | |
1374 | ||
e46a2879 MK |
1375 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1376 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1377 | return ret; |
1378 | ||
5ad333eb | 1379 | ret = -EBUSY; |
08e552c6 | 1380 | |
c8244935 MG |
1381 | /* |
1382 | * To minimise LRU disruption, the caller can indicate that it only | |
1383 | * wants to isolate pages it will be able to operate on without | |
1384 | * blocking - clean pages for the most part. | |
1385 | * | |
c8244935 MG |
1386 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages |
1387 | * that it is possible to migrate without blocking | |
1388 | */ | |
1276ad68 | 1389 | if (mode & ISOLATE_ASYNC_MIGRATE) { |
c8244935 MG |
1390 | /* All the caller can do on PageWriteback is block */ |
1391 | if (PageWriteback(page)) | |
1392 | return ret; | |
1393 | ||
1394 | if (PageDirty(page)) { | |
1395 | struct address_space *mapping; | |
1396 | ||
c8244935 MG |
1397 | /* |
1398 | * Only pages without mappings or that have a | |
1399 | * ->migratepage callback are possible to migrate | |
1400 | * without blocking | |
1401 | */ | |
1402 | mapping = page_mapping(page); | |
1403 | if (mapping && !mapping->a_ops->migratepage) | |
1404 | return ret; | |
1405 | } | |
1406 | } | |
39deaf85 | 1407 | |
f80c0673 MK |
1408 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1409 | return ret; | |
1410 | ||
5ad333eb AW |
1411 | if (likely(get_page_unless_zero(page))) { |
1412 | /* | |
1413 | * Be careful not to clear PageLRU until after we're | |
1414 | * sure the page is not being freed elsewhere -- the | |
1415 | * page release code relies on it. | |
1416 | */ | |
1417 | ClearPageLRU(page); | |
1418 | ret = 0; | |
1419 | } | |
1420 | ||
1421 | return ret; | |
1422 | } | |
1423 | ||
7ee36a14 MG |
1424 | |
1425 | /* | |
1426 | * Update LRU sizes after isolating pages. The LRU size updates must | |
1427 | * be complete before mem_cgroup_update_lru_size due to a santity check. | |
1428 | */ | |
1429 | static __always_inline void update_lru_sizes(struct lruvec *lruvec, | |
b4536f0c | 1430 | enum lru_list lru, unsigned long *nr_zone_taken) |
7ee36a14 | 1431 | { |
7ee36a14 MG |
1432 | int zid; |
1433 | ||
7ee36a14 MG |
1434 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1435 | if (!nr_zone_taken[zid]) | |
1436 | continue; | |
1437 | ||
1438 | __update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); | |
7ee36a14 | 1439 | #ifdef CONFIG_MEMCG |
b4536f0c | 1440 | mem_cgroup_update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); |
7ee36a14 | 1441 | #endif |
b4536f0c MH |
1442 | } |
1443 | ||
7ee36a14 MG |
1444 | } |
1445 | ||
1da177e4 | 1446 | /* |
a52633d8 | 1447 | * zone_lru_lock is heavily contended. Some of the functions that |
1da177e4 LT |
1448 | * shrink the lists perform better by taking out a batch of pages |
1449 | * and working on them outside the LRU lock. | |
1450 | * | |
1451 | * For pagecache intensive workloads, this function is the hottest | |
1452 | * spot in the kernel (apart from copy_*_user functions). | |
1453 | * | |
1454 | * Appropriate locks must be held before calling this function. | |
1455 | * | |
1456 | * @nr_to_scan: The number of pages to look through on the list. | |
5dc35979 | 1457 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1458 | * @dst: The temp list to put pages on to. |
f626012d | 1459 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1460 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1461 | * @mode: One of the LRU isolation modes |
3cb99451 | 1462 | * @lru: LRU list id for isolating |
1da177e4 LT |
1463 | * |
1464 | * returns how many pages were moved onto *@dst. | |
1465 | */ | |
69e05944 | 1466 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1467 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1468 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1469 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1470 | { |
75b00af7 | 1471 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1472 | unsigned long nr_taken = 0; |
599d0c95 | 1473 | unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; |
7cc30fcf | 1474 | unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; |
1265e3a6 | 1475 | unsigned long skipped = 0, total_skipped = 0; |
599d0c95 | 1476 | unsigned long scan, nr_pages; |
b2e18757 | 1477 | LIST_HEAD(pages_skipped); |
1da177e4 | 1478 | |
0b802f10 | 1479 | for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan && |
d7f05528 | 1480 | !list_empty(src);) { |
5ad333eb | 1481 | struct page *page; |
5ad333eb | 1482 | |
1da177e4 LT |
1483 | page = lru_to_page(src); |
1484 | prefetchw_prev_lru_page(page, src, flags); | |
1485 | ||
309381fe | 1486 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1487 | |
b2e18757 MG |
1488 | if (page_zonenum(page) > sc->reclaim_idx) { |
1489 | list_move(&page->lru, &pages_skipped); | |
7cc30fcf | 1490 | nr_skipped[page_zonenum(page)]++; |
b2e18757 MG |
1491 | continue; |
1492 | } | |
1493 | ||
d7f05528 MG |
1494 | /* |
1495 | * Account for scanned and skipped separetly to avoid the pgdat | |
1496 | * being prematurely marked unreclaimable by pgdat_reclaimable. | |
1497 | */ | |
1498 | scan++; | |
1499 | ||
f3fd4a61 | 1500 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1501 | case 0: |
599d0c95 MG |
1502 | nr_pages = hpage_nr_pages(page); |
1503 | nr_taken += nr_pages; | |
1504 | nr_zone_taken[page_zonenum(page)] += nr_pages; | |
5ad333eb | 1505 | list_move(&page->lru, dst); |
5ad333eb AW |
1506 | break; |
1507 | ||
1508 | case -EBUSY: | |
1509 | /* else it is being freed elsewhere */ | |
1510 | list_move(&page->lru, src); | |
1511 | continue; | |
46453a6e | 1512 | |
5ad333eb AW |
1513 | default: |
1514 | BUG(); | |
1515 | } | |
1da177e4 LT |
1516 | } |
1517 | ||
b2e18757 MG |
1518 | /* |
1519 | * Splice any skipped pages to the start of the LRU list. Note that | |
1520 | * this disrupts the LRU order when reclaiming for lower zones but | |
1521 | * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX | |
1522 | * scanning would soon rescan the same pages to skip and put the | |
1523 | * system at risk of premature OOM. | |
1524 | */ | |
7cc30fcf MG |
1525 | if (!list_empty(&pages_skipped)) { |
1526 | int zid; | |
1527 | ||
7cc30fcf MG |
1528 | for (zid = 0; zid < MAX_NR_ZONES; zid++) { |
1529 | if (!nr_skipped[zid]) | |
1530 | continue; | |
1531 | ||
1532 | __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); | |
1265e3a6 | 1533 | skipped += nr_skipped[zid]; |
7cc30fcf | 1534 | } |
d7f05528 MG |
1535 | |
1536 | /* | |
1537 | * Account skipped pages as a partial scan as the pgdat may be | |
1538 | * close to unreclaimable. If the LRU list is empty, account | |
1539 | * skipped pages as a full scan. | |
1540 | */ | |
1265e3a6 | 1541 | total_skipped = list_empty(src) ? skipped : skipped >> 2; |
d7f05528 MG |
1542 | |
1543 | list_splice(&pages_skipped, src); | |
7cc30fcf | 1544 | } |
1265e3a6 MH |
1545 | *nr_scanned = scan + total_skipped; |
1546 | trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, | |
32b3f297 | 1547 | scan, skipped, nr_taken, mode, lru); |
b4536f0c | 1548 | update_lru_sizes(lruvec, lru, nr_zone_taken); |
1da177e4 LT |
1549 | return nr_taken; |
1550 | } | |
1551 | ||
62695a84 NP |
1552 | /** |
1553 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1554 | * @page: page to isolate from its LRU list | |
1555 | * | |
1556 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1557 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1558 | * | |
1559 | * Returns 0 if the page was removed from an LRU list. | |
1560 | * Returns -EBUSY if the page was not on an LRU list. | |
1561 | * | |
1562 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1563 | * the active list, it will have PageActive set. If it was found on |
1564 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1565 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1566 | * |
1567 | * The vmstat statistic corresponding to the list on which the page was | |
1568 | * found will be decremented. | |
1569 | * | |
1570 | * Restrictions: | |
1571 | * (1) Must be called with an elevated refcount on the page. This is a | |
1572 | * fundamentnal difference from isolate_lru_pages (which is called | |
1573 | * without a stable reference). | |
1574 | * (2) the lru_lock must not be held. | |
1575 | * (3) interrupts must be enabled. | |
1576 | */ | |
1577 | int isolate_lru_page(struct page *page) | |
1578 | { | |
1579 | int ret = -EBUSY; | |
1580 | ||
309381fe | 1581 | VM_BUG_ON_PAGE(!page_count(page), page); |
cf2a82ee | 1582 | WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); |
0c917313 | 1583 | |
62695a84 NP |
1584 | if (PageLRU(page)) { |
1585 | struct zone *zone = page_zone(page); | |
fa9add64 | 1586 | struct lruvec *lruvec; |
62695a84 | 1587 | |
a52633d8 | 1588 | spin_lock_irq(zone_lru_lock(zone)); |
599d0c95 | 1589 | lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); |
0c917313 | 1590 | if (PageLRU(page)) { |
894bc310 | 1591 | int lru = page_lru(page); |
0c917313 | 1592 | get_page(page); |
62695a84 | 1593 | ClearPageLRU(page); |
fa9add64 HD |
1594 | del_page_from_lru_list(page, lruvec, lru); |
1595 | ret = 0; | |
62695a84 | 1596 | } |
a52633d8 | 1597 | spin_unlock_irq(zone_lru_lock(zone)); |
62695a84 NP |
1598 | } |
1599 | return ret; | |
1600 | } | |
1601 | ||
35cd7815 | 1602 | /* |
d37dd5dc FW |
1603 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1604 | * then get resheduled. When there are massive number of tasks doing page | |
1605 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1606 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1607 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 | 1608 | */ |
599d0c95 | 1609 | static int too_many_isolated(struct pglist_data *pgdat, int file, |
35cd7815 RR |
1610 | struct scan_control *sc) |
1611 | { | |
1612 | unsigned long inactive, isolated; | |
1613 | ||
1614 | if (current_is_kswapd()) | |
1615 | return 0; | |
1616 | ||
97c9341f | 1617 | if (!sane_reclaim(sc)) |
35cd7815 RR |
1618 | return 0; |
1619 | ||
1620 | if (file) { | |
599d0c95 MG |
1621 | inactive = node_page_state(pgdat, NR_INACTIVE_FILE); |
1622 | isolated = node_page_state(pgdat, NR_ISOLATED_FILE); | |
35cd7815 | 1623 | } else { |
599d0c95 MG |
1624 | inactive = node_page_state(pgdat, NR_INACTIVE_ANON); |
1625 | isolated = node_page_state(pgdat, NR_ISOLATED_ANON); | |
35cd7815 RR |
1626 | } |
1627 | ||
3cf23841 FW |
1628 | /* |
1629 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1630 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1631 | * deadlock. | |
1632 | */ | |
d0164adc | 1633 | if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS)) |
3cf23841 FW |
1634 | inactive >>= 3; |
1635 | ||
35cd7815 RR |
1636 | return isolated > inactive; |
1637 | } | |
1638 | ||
66635629 | 1639 | static noinline_for_stack void |
75b00af7 | 1640 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1641 | { |
27ac81d8 | 1642 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
599d0c95 | 1643 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3f79768f | 1644 | LIST_HEAD(pages_to_free); |
66635629 | 1645 | |
66635629 MG |
1646 | /* |
1647 | * Put back any unfreeable pages. | |
1648 | */ | |
66635629 | 1649 | while (!list_empty(page_list)) { |
3f79768f | 1650 | struct page *page = lru_to_page(page_list); |
66635629 | 1651 | int lru; |
3f79768f | 1652 | |
309381fe | 1653 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1654 | list_del(&page->lru); |
39b5f29a | 1655 | if (unlikely(!page_evictable(page))) { |
599d0c95 | 1656 | spin_unlock_irq(&pgdat->lru_lock); |
66635629 | 1657 | putback_lru_page(page); |
599d0c95 | 1658 | spin_lock_irq(&pgdat->lru_lock); |
66635629 MG |
1659 | continue; |
1660 | } | |
fa9add64 | 1661 | |
599d0c95 | 1662 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
fa9add64 | 1663 | |
7a608572 | 1664 | SetPageLRU(page); |
66635629 | 1665 | lru = page_lru(page); |
fa9add64 HD |
1666 | add_page_to_lru_list(page, lruvec, lru); |
1667 | ||
66635629 MG |
1668 | if (is_active_lru(lru)) { |
1669 | int file = is_file_lru(lru); | |
9992af10 RR |
1670 | int numpages = hpage_nr_pages(page); |
1671 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1672 | } |
2bcf8879 HD |
1673 | if (put_page_testzero(page)) { |
1674 | __ClearPageLRU(page); | |
1675 | __ClearPageActive(page); | |
fa9add64 | 1676 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1677 | |
1678 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 1679 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 1680 | mem_cgroup_uncharge(page); |
2bcf8879 | 1681 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 1682 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
1683 | } else |
1684 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1685 | } |
1686 | } | |
66635629 | 1687 | |
3f79768f HD |
1688 | /* |
1689 | * To save our caller's stack, now use input list for pages to free. | |
1690 | */ | |
1691 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1692 | } |
1693 | ||
399ba0b9 N |
1694 | /* |
1695 | * If a kernel thread (such as nfsd for loop-back mounts) services | |
1696 | * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. | |
1697 | * In that case we should only throttle if the backing device it is | |
1698 | * writing to is congested. In other cases it is safe to throttle. | |
1699 | */ | |
1700 | static int current_may_throttle(void) | |
1701 | { | |
1702 | return !(current->flags & PF_LESS_THROTTLE) || | |
1703 | current->backing_dev_info == NULL || | |
1704 | bdi_write_congested(current->backing_dev_info); | |
1705 | } | |
1706 | ||
1da177e4 | 1707 | /* |
b2e18757 | 1708 | * shrink_inactive_list() is a helper for shrink_node(). It returns the number |
1742f19f | 1709 | * of reclaimed pages |
1da177e4 | 1710 | */ |
66635629 | 1711 | static noinline_for_stack unsigned long |
1a93be0e | 1712 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1713 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1714 | { |
1715 | LIST_HEAD(page_list); | |
e247dbce | 1716 | unsigned long nr_scanned; |
05ff5137 | 1717 | unsigned long nr_reclaimed = 0; |
e247dbce | 1718 | unsigned long nr_taken; |
3c710c1a | 1719 | struct reclaim_stat stat = {}; |
f3fd4a61 | 1720 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1721 | int file = is_file_lru(lru); |
599d0c95 | 1722 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1a93be0e | 1723 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
78dc583d | 1724 | |
599d0c95 | 1725 | while (unlikely(too_many_isolated(pgdat, file, sc))) { |
58355c78 | 1726 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1727 | |
1728 | /* We are about to die and free our memory. Return now. */ | |
1729 | if (fatal_signal_pending(current)) | |
1730 | return SWAP_CLUSTER_MAX; | |
1731 | } | |
1732 | ||
1da177e4 | 1733 | lru_add_drain(); |
f80c0673 MK |
1734 | |
1735 | if (!sc->may_unmap) | |
61317289 | 1736 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1737 | |
599d0c95 | 1738 | spin_lock_irq(&pgdat->lru_lock); |
b35ea17b | 1739 | |
5dc35979 KK |
1740 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1741 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc | 1742 | |
599d0c95 | 1743 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
9d5e6a9f | 1744 | reclaim_stat->recent_scanned[file] += nr_taken; |
95d918fc | 1745 | |
89b5fae5 | 1746 | if (global_reclaim(sc)) { |
e247dbce | 1747 | if (current_is_kswapd()) |
599d0c95 | 1748 | __count_vm_events(PGSCAN_KSWAPD, nr_scanned); |
e247dbce | 1749 | else |
599d0c95 | 1750 | __count_vm_events(PGSCAN_DIRECT, nr_scanned); |
e247dbce | 1751 | } |
599d0c95 | 1752 | spin_unlock_irq(&pgdat->lru_lock); |
b35ea17b | 1753 | |
d563c050 | 1754 | if (nr_taken == 0) |
66635629 | 1755 | return 0; |
5ad333eb | 1756 | |
599d0c95 | 1757 | nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, TTU_UNMAP, |
3c710c1a | 1758 | &stat, false); |
c661b078 | 1759 | |
599d0c95 | 1760 | spin_lock_irq(&pgdat->lru_lock); |
3f79768f | 1761 | |
904249aa YH |
1762 | if (global_reclaim(sc)) { |
1763 | if (current_is_kswapd()) | |
599d0c95 | 1764 | __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); |
904249aa | 1765 | else |
599d0c95 | 1766 | __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); |
904249aa | 1767 | } |
a74609fa | 1768 | |
27ac81d8 | 1769 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1770 | |
599d0c95 | 1771 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f | 1772 | |
599d0c95 | 1773 | spin_unlock_irq(&pgdat->lru_lock); |
3f79768f | 1774 | |
747db954 | 1775 | mem_cgroup_uncharge_list(&page_list); |
b745bc85 | 1776 | free_hot_cold_page_list(&page_list, true); |
e11da5b4 | 1777 | |
92df3a72 MG |
1778 | /* |
1779 | * If reclaim is isolating dirty pages under writeback, it implies | |
1780 | * that the long-lived page allocation rate is exceeding the page | |
1781 | * laundering rate. Either the global limits are not being effective | |
1782 | * at throttling processes due to the page distribution throughout | |
1783 | * zones or there is heavy usage of a slow backing device. The | |
1784 | * only option is to throttle from reclaim context which is not ideal | |
1785 | * as there is no guarantee the dirtying process is throttled in the | |
1786 | * same way balance_dirty_pages() manages. | |
1787 | * | |
8e950282 MG |
1788 | * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number |
1789 | * of pages under pages flagged for immediate reclaim and stall if any | |
1790 | * are encountered in the nr_immediate check below. | |
92df3a72 | 1791 | */ |
3c710c1a | 1792 | if (stat.nr_writeback && stat.nr_writeback == nr_taken) |
599d0c95 | 1793 | set_bit(PGDAT_WRITEBACK, &pgdat->flags); |
92df3a72 | 1794 | |
d43006d5 | 1795 | /* |
97c9341f TH |
1796 | * Legacy memcg will stall in page writeback so avoid forcibly |
1797 | * stalling here. | |
d43006d5 | 1798 | */ |
97c9341f | 1799 | if (sane_reclaim(sc)) { |
8e950282 MG |
1800 | /* |
1801 | * Tag a zone as congested if all the dirty pages scanned were | |
1802 | * backed by a congested BDI and wait_iff_congested will stall. | |
1803 | */ | |
3c710c1a | 1804 | if (stat.nr_dirty && stat.nr_dirty == stat.nr_congested) |
599d0c95 | 1805 | set_bit(PGDAT_CONGESTED, &pgdat->flags); |
8e950282 | 1806 | |
b1a6f21e MG |
1807 | /* |
1808 | * If dirty pages are scanned that are not queued for IO, it | |
726d061f JW |
1809 | * implies that flushers are not doing their job. This can |
1810 | * happen when memory pressure pushes dirty pages to the end of | |
1811 | * the LRU before the dirty limits are breached and the dirty | |
1812 | * data has expired. It can also happen when the proportion of | |
1813 | * dirty pages grows not through writes but through memory | |
1814 | * pressure reclaiming all the clean cache. And in some cases, | |
1815 | * the flushers simply cannot keep up with the allocation | |
1816 | * rate. Nudge the flusher threads in case they are asleep, but | |
1817 | * also allow kswapd to start writing pages during reclaim. | |
b1a6f21e | 1818 | */ |
726d061f JW |
1819 | if (stat.nr_unqueued_dirty == nr_taken) { |
1820 | wakeup_flusher_threads(0, WB_REASON_VMSCAN); | |
599d0c95 | 1821 | set_bit(PGDAT_DIRTY, &pgdat->flags); |
726d061f | 1822 | } |
b1a6f21e MG |
1823 | |
1824 | /* | |
b738d764 LT |
1825 | * If kswapd scans pages marked marked for immediate |
1826 | * reclaim and under writeback (nr_immediate), it implies | |
1827 | * that pages are cycling through the LRU faster than | |
b1a6f21e MG |
1828 | * they are written so also forcibly stall. |
1829 | */ | |
3c710c1a | 1830 | if (stat.nr_immediate && current_may_throttle()) |
b1a6f21e | 1831 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
e2be15f6 | 1832 | } |
d43006d5 | 1833 | |
8e950282 MG |
1834 | /* |
1835 | * Stall direct reclaim for IO completions if underlying BDIs or zone | |
1836 | * is congested. Allow kswapd to continue until it starts encountering | |
1837 | * unqueued dirty pages or cycling through the LRU too quickly. | |
1838 | */ | |
399ba0b9 N |
1839 | if (!sc->hibernation_mode && !current_is_kswapd() && |
1840 | current_may_throttle()) | |
599d0c95 | 1841 | wait_iff_congested(pgdat, BLK_RW_ASYNC, HZ/10); |
8e950282 | 1842 | |
599d0c95 MG |
1843 | trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, |
1844 | nr_scanned, nr_reclaimed, | |
5bccd166 MH |
1845 | stat.nr_dirty, stat.nr_writeback, |
1846 | stat.nr_congested, stat.nr_immediate, | |
1847 | stat.nr_activate, stat.nr_ref_keep, | |
1848 | stat.nr_unmap_fail, | |
ba5e9579 | 1849 | sc->priority, file); |
05ff5137 | 1850 | return nr_reclaimed; |
1da177e4 LT |
1851 | } |
1852 | ||
1853 | /* | |
1854 | * This moves pages from the active list to the inactive list. | |
1855 | * | |
1856 | * We move them the other way if the page is referenced by one or more | |
1857 | * processes, from rmap. | |
1858 | * | |
1859 | * If the pages are mostly unmapped, the processing is fast and it is | |
a52633d8 | 1860 | * appropriate to hold zone_lru_lock across the whole operation. But if |
1da177e4 | 1861 | * the pages are mapped, the processing is slow (page_referenced()) so we |
a52633d8 | 1862 | * should drop zone_lru_lock around each page. It's impossible to balance |
1da177e4 LT |
1863 | * this, so instead we remove the pages from the LRU while processing them. |
1864 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1865 | * nobody will play with that bit on a non-LRU page. | |
1866 | * | |
0139aa7b | 1867 | * The downside is that we have to touch page->_refcount against each page. |
1da177e4 | 1868 | * But we had to alter page->flags anyway. |
9d998b4f MH |
1869 | * |
1870 | * Returns the number of pages moved to the given lru. | |
1da177e4 | 1871 | */ |
1cfb419b | 1872 | |
9d998b4f | 1873 | static unsigned move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 1874 | struct list_head *list, |
2bcf8879 | 1875 | struct list_head *pages_to_free, |
3eb4140f WF |
1876 | enum lru_list lru) |
1877 | { | |
599d0c95 | 1878 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
3eb4140f | 1879 | struct page *page; |
fa9add64 | 1880 | int nr_pages; |
9d998b4f | 1881 | int nr_moved = 0; |
3eb4140f | 1882 | |
3eb4140f WF |
1883 | while (!list_empty(list)) { |
1884 | page = lru_to_page(list); | |
599d0c95 | 1885 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
3eb4140f | 1886 | |
309381fe | 1887 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
1888 | SetPageLRU(page); |
1889 | ||
fa9add64 | 1890 | nr_pages = hpage_nr_pages(page); |
599d0c95 | 1891 | update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); |
925b7673 | 1892 | list_move(&page->lru, &lruvec->lists[lru]); |
3eb4140f | 1893 | |
2bcf8879 HD |
1894 | if (put_page_testzero(page)) { |
1895 | __ClearPageLRU(page); | |
1896 | __ClearPageActive(page); | |
fa9add64 | 1897 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1898 | |
1899 | if (unlikely(PageCompound(page))) { | |
599d0c95 | 1900 | spin_unlock_irq(&pgdat->lru_lock); |
747db954 | 1901 | mem_cgroup_uncharge(page); |
2bcf8879 | 1902 | (*get_compound_page_dtor(page))(page); |
599d0c95 | 1903 | spin_lock_irq(&pgdat->lru_lock); |
2bcf8879 HD |
1904 | } else |
1905 | list_add(&page->lru, pages_to_free); | |
9d998b4f MH |
1906 | } else { |
1907 | nr_moved += nr_pages; | |
3eb4140f WF |
1908 | } |
1909 | } | |
9d5e6a9f | 1910 | |
3eb4140f | 1911 | if (!is_active_lru(lru)) |
f0958906 | 1912 | __count_vm_events(PGDEACTIVATE, nr_moved); |
9d998b4f MH |
1913 | |
1914 | return nr_moved; | |
3eb4140f | 1915 | } |
1cfb419b | 1916 | |
f626012d | 1917 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 1918 | struct lruvec *lruvec, |
f16015fb | 1919 | struct scan_control *sc, |
9e3b2f8c | 1920 | enum lru_list lru) |
1da177e4 | 1921 | { |
44c241f1 | 1922 | unsigned long nr_taken; |
f626012d | 1923 | unsigned long nr_scanned; |
6fe6b7e3 | 1924 | unsigned long vm_flags; |
1da177e4 | 1925 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1926 | LIST_HEAD(l_active); |
b69408e8 | 1927 | LIST_HEAD(l_inactive); |
1da177e4 | 1928 | struct page *page; |
1a93be0e | 1929 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
9d998b4f MH |
1930 | unsigned nr_deactivate, nr_activate; |
1931 | unsigned nr_rotated = 0; | |
f3fd4a61 | 1932 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1933 | int file = is_file_lru(lru); |
599d0c95 | 1934 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
1da177e4 LT |
1935 | |
1936 | lru_add_drain(); | |
f80c0673 MK |
1937 | |
1938 | if (!sc->may_unmap) | |
61317289 | 1939 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1940 | |
599d0c95 | 1941 | spin_lock_irq(&pgdat->lru_lock); |
925b7673 | 1942 | |
5dc35979 KK |
1943 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
1944 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 1945 | |
599d0c95 | 1946 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); |
b7c46d15 | 1947 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1948 | |
599d0c95 | 1949 | __count_vm_events(PGREFILL, nr_scanned); |
9d5e6a9f | 1950 | |
599d0c95 | 1951 | spin_unlock_irq(&pgdat->lru_lock); |
1da177e4 | 1952 | |
1da177e4 LT |
1953 | while (!list_empty(&l_hold)) { |
1954 | cond_resched(); | |
1955 | page = lru_to_page(&l_hold); | |
1956 | list_del(&page->lru); | |
7e9cd484 | 1957 | |
39b5f29a | 1958 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
1959 | putback_lru_page(page); |
1960 | continue; | |
1961 | } | |
1962 | ||
cc715d99 MG |
1963 | if (unlikely(buffer_heads_over_limit)) { |
1964 | if (page_has_private(page) && trylock_page(page)) { | |
1965 | if (page_has_private(page)) | |
1966 | try_to_release_page(page, 0); | |
1967 | unlock_page(page); | |
1968 | } | |
1969 | } | |
1970 | ||
c3ac9a8a JW |
1971 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
1972 | &vm_flags)) { | |
9992af10 | 1973 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1974 | /* |
1975 | * Identify referenced, file-backed active pages and | |
1976 | * give them one more trip around the active list. So | |
1977 | * that executable code get better chances to stay in | |
1978 | * memory under moderate memory pressure. Anon pages | |
1979 | * are not likely to be evicted by use-once streaming | |
1980 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1981 | * so we ignore them here. | |
1982 | */ | |
41e20983 | 1983 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1984 | list_add(&page->lru, &l_active); |
1985 | continue; | |
1986 | } | |
1987 | } | |
7e9cd484 | 1988 | |
5205e56e | 1989 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1990 | list_add(&page->lru, &l_inactive); |
1991 | } | |
1992 | ||
b555749a | 1993 | /* |
8cab4754 | 1994 | * Move pages back to the lru list. |
b555749a | 1995 | */ |
599d0c95 | 1996 | spin_lock_irq(&pgdat->lru_lock); |
556adecb | 1997 | /* |
8cab4754 WF |
1998 | * Count referenced pages from currently used mappings as rotated, |
1999 | * even though only some of them are actually re-activated. This | |
2000 | * helps balance scan pressure between file and anonymous pages in | |
7c0db9e9 | 2001 | * get_scan_count. |
7e9cd484 | 2002 | */ |
b7c46d15 | 2003 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 2004 | |
9d998b4f MH |
2005 | nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
2006 | nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
599d0c95 MG |
2007 | __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); |
2008 | spin_unlock_irq(&pgdat->lru_lock); | |
2bcf8879 | 2009 | |
747db954 | 2010 | mem_cgroup_uncharge_list(&l_hold); |
b745bc85 | 2011 | free_hot_cold_page_list(&l_hold, true); |
9d998b4f MH |
2012 | trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate, |
2013 | nr_deactivate, nr_rotated, sc->priority, file); | |
1da177e4 LT |
2014 | } |
2015 | ||
59dc76b0 RR |
2016 | /* |
2017 | * The inactive anon list should be small enough that the VM never has | |
2018 | * to do too much work. | |
14797e23 | 2019 | * |
59dc76b0 RR |
2020 | * The inactive file list should be small enough to leave most memory |
2021 | * to the established workingset on the scan-resistant active list, | |
2022 | * but large enough to avoid thrashing the aggregate readahead window. | |
56e49d21 | 2023 | * |
59dc76b0 RR |
2024 | * Both inactive lists should also be large enough that each inactive |
2025 | * page has a chance to be referenced again before it is reclaimed. | |
56e49d21 | 2026 | * |
59dc76b0 RR |
2027 | * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages |
2028 | * on this LRU, maintained by the pageout code. A zone->inactive_ratio | |
2029 | * of 3 means 3:1 or 25% of the pages are kept on the inactive list. | |
56e49d21 | 2030 | * |
59dc76b0 RR |
2031 | * total target max |
2032 | * memory ratio inactive | |
2033 | * ------------------------------------- | |
2034 | * 10MB 1 5MB | |
2035 | * 100MB 1 50MB | |
2036 | * 1GB 3 250MB | |
2037 | * 10GB 10 0.9GB | |
2038 | * 100GB 31 3GB | |
2039 | * 1TB 101 10GB | |
2040 | * 10TB 320 32GB | |
56e49d21 | 2041 | */ |
f8d1a311 | 2042 | static bool inactive_list_is_low(struct lruvec *lruvec, bool file, |
dcec0b60 | 2043 | struct scan_control *sc, bool trace) |
56e49d21 | 2044 | { |
59dc76b0 | 2045 | unsigned long inactive_ratio; |
fd538803 MH |
2046 | unsigned long inactive, active; |
2047 | enum lru_list inactive_lru = file * LRU_FILE; | |
2048 | enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE; | |
59dc76b0 | 2049 | unsigned long gb; |
e3790144 | 2050 | |
59dc76b0 RR |
2051 | /* |
2052 | * If we don't have swap space, anonymous page deactivation | |
2053 | * is pointless. | |
2054 | */ | |
2055 | if (!file && !total_swap_pages) | |
2056 | return false; | |
56e49d21 | 2057 | |
fd538803 MH |
2058 | inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx); |
2059 | active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx); | |
f8d1a311 | 2060 | |
59dc76b0 RR |
2061 | gb = (inactive + active) >> (30 - PAGE_SHIFT); |
2062 | if (gb) | |
2063 | inactive_ratio = int_sqrt(10 * gb); | |
b39415b2 | 2064 | else |
59dc76b0 RR |
2065 | inactive_ratio = 1; |
2066 | ||
dcec0b60 | 2067 | if (trace) |
fd538803 | 2068 | trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id, |
dcec0b60 | 2069 | sc->reclaim_idx, |
fd538803 MH |
2070 | lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive, |
2071 | lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active, | |
2072 | inactive_ratio, file); | |
2073 | ||
59dc76b0 | 2074 | return inactive * inactive_ratio < active; |
b39415b2 RR |
2075 | } |
2076 | ||
4f98a2fe | 2077 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
1a93be0e | 2078 | struct lruvec *lruvec, struct scan_control *sc) |
b69408e8 | 2079 | { |
b39415b2 | 2080 | if (is_active_lru(lru)) { |
dcec0b60 | 2081 | if (inactive_list_is_low(lruvec, is_file_lru(lru), sc, true)) |
1a93be0e | 2082 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
2083 | return 0; |
2084 | } | |
2085 | ||
1a93be0e | 2086 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
2087 | } |
2088 | ||
9a265114 JW |
2089 | enum scan_balance { |
2090 | SCAN_EQUAL, | |
2091 | SCAN_FRACT, | |
2092 | SCAN_ANON, | |
2093 | SCAN_FILE, | |
2094 | }; | |
2095 | ||
4f98a2fe RR |
2096 | /* |
2097 | * Determine how aggressively the anon and file LRU lists should be | |
2098 | * scanned. The relative value of each set of LRU lists is determined | |
2099 | * by looking at the fraction of the pages scanned we did rotate back | |
2100 | * onto the active list instead of evict. | |
2101 | * | |
be7bd59d WL |
2102 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
2103 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 2104 | */ |
33377678 | 2105 | static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, |
6b4f7799 JW |
2106 | struct scan_control *sc, unsigned long *nr, |
2107 | unsigned long *lru_pages) | |
4f98a2fe | 2108 | { |
33377678 | 2109 | int swappiness = mem_cgroup_swappiness(memcg); |
9a265114 JW |
2110 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
2111 | u64 fraction[2]; | |
2112 | u64 denominator = 0; /* gcc */ | |
599d0c95 | 2113 | struct pglist_data *pgdat = lruvec_pgdat(lruvec); |
4f98a2fe | 2114 | unsigned long anon_prio, file_prio; |
9a265114 | 2115 | enum scan_balance scan_balance; |
0bf1457f | 2116 | unsigned long anon, file; |
4f98a2fe | 2117 | unsigned long ap, fp; |
4111304d | 2118 | enum lru_list lru; |
76a33fc3 SL |
2119 | |
2120 | /* If we have no swap space, do not bother scanning anon pages. */ | |
d8b38438 | 2121 | if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { |
9a265114 | 2122 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
2123 | goto out; |
2124 | } | |
4f98a2fe | 2125 | |
10316b31 JW |
2126 | /* |
2127 | * Global reclaim will swap to prevent OOM even with no | |
2128 | * swappiness, but memcg users want to use this knob to | |
2129 | * disable swapping for individual groups completely when | |
2130 | * using the memory controller's swap limit feature would be | |
2131 | * too expensive. | |
2132 | */ | |
02695175 | 2133 | if (!global_reclaim(sc) && !swappiness) { |
9a265114 | 2134 | scan_balance = SCAN_FILE; |
10316b31 JW |
2135 | goto out; |
2136 | } | |
2137 | ||
2138 | /* | |
2139 | * Do not apply any pressure balancing cleverness when the | |
2140 | * system is close to OOM, scan both anon and file equally | |
2141 | * (unless the swappiness setting disagrees with swapping). | |
2142 | */ | |
02695175 | 2143 | if (!sc->priority && swappiness) { |
9a265114 | 2144 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
2145 | goto out; |
2146 | } | |
2147 | ||
62376251 JW |
2148 | /* |
2149 | * Prevent the reclaimer from falling into the cache trap: as | |
2150 | * cache pages start out inactive, every cache fault will tip | |
2151 | * the scan balance towards the file LRU. And as the file LRU | |
2152 | * shrinks, so does the window for rotation from references. | |
2153 | * This means we have a runaway feedback loop where a tiny | |
2154 | * thrashing file LRU becomes infinitely more attractive than | |
2155 | * anon pages. Try to detect this based on file LRU size. | |
2156 | */ | |
2157 | if (global_reclaim(sc)) { | |
599d0c95 MG |
2158 | unsigned long pgdatfile; |
2159 | unsigned long pgdatfree; | |
2160 | int z; | |
2161 | unsigned long total_high_wmark = 0; | |
2ab051e1 | 2162 | |
599d0c95 MG |
2163 | pgdatfree = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); |
2164 | pgdatfile = node_page_state(pgdat, NR_ACTIVE_FILE) + | |
2165 | node_page_state(pgdat, NR_INACTIVE_FILE); | |
2166 | ||
2167 | for (z = 0; z < MAX_NR_ZONES; z++) { | |
2168 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2169 | if (!managed_zone(zone)) |
599d0c95 MG |
2170 | continue; |
2171 | ||
2172 | total_high_wmark += high_wmark_pages(zone); | |
2173 | } | |
62376251 | 2174 | |
599d0c95 | 2175 | if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) { |
62376251 JW |
2176 | scan_balance = SCAN_ANON; |
2177 | goto out; | |
2178 | } | |
2179 | } | |
2180 | ||
7c5bd705 | 2181 | /* |
316bda0e VD |
2182 | * If there is enough inactive page cache, i.e. if the size of the |
2183 | * inactive list is greater than that of the active list *and* the | |
2184 | * inactive list actually has some pages to scan on this priority, we | |
2185 | * do not reclaim anything from the anonymous working set right now. | |
2186 | * Without the second condition we could end up never scanning an | |
2187 | * lruvec even if it has plenty of old anonymous pages unless the | |
2188 | * system is under heavy pressure. | |
7c5bd705 | 2189 | */ |
dcec0b60 | 2190 | if (!inactive_list_is_low(lruvec, true, sc, false) && |
71ab6cfe | 2191 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) { |
9a265114 | 2192 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
2193 | goto out; |
2194 | } | |
2195 | ||
9a265114 JW |
2196 | scan_balance = SCAN_FRACT; |
2197 | ||
58c37f6e KM |
2198 | /* |
2199 | * With swappiness at 100, anonymous and file have the same priority. | |
2200 | * This scanning priority is essentially the inverse of IO cost. | |
2201 | */ | |
02695175 | 2202 | anon_prio = swappiness; |
75b00af7 | 2203 | file_prio = 200 - anon_prio; |
58c37f6e | 2204 | |
4f98a2fe RR |
2205 | /* |
2206 | * OK, so we have swap space and a fair amount of page cache | |
2207 | * pages. We use the recently rotated / recently scanned | |
2208 | * ratios to determine how valuable each cache is. | |
2209 | * | |
2210 | * Because workloads change over time (and to avoid overflow) | |
2211 | * we keep these statistics as a floating average, which ends | |
2212 | * up weighing recent references more than old ones. | |
2213 | * | |
2214 | * anon in [0], file in [1] | |
2215 | */ | |
2ab051e1 | 2216 | |
fd538803 MH |
2217 | anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) + |
2218 | lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES); | |
2219 | file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + | |
2220 | lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); | |
2ab051e1 | 2221 | |
599d0c95 | 2222 | spin_lock_irq(&pgdat->lru_lock); |
6e901571 | 2223 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
2224 | reclaim_stat->recent_scanned[0] /= 2; |
2225 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
2226 | } |
2227 | ||
6e901571 | 2228 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
2229 | reclaim_stat->recent_scanned[1] /= 2; |
2230 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
2231 | } |
2232 | ||
4f98a2fe | 2233 | /* |
00d8089c RR |
2234 | * The amount of pressure on anon vs file pages is inversely |
2235 | * proportional to the fraction of recently scanned pages on | |
2236 | * each list that were recently referenced and in active use. | |
4f98a2fe | 2237 | */ |
fe35004f | 2238 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 2239 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 2240 | |
fe35004f | 2241 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 2242 | fp /= reclaim_stat->recent_rotated[1] + 1; |
599d0c95 | 2243 | spin_unlock_irq(&pgdat->lru_lock); |
4f98a2fe | 2244 | |
76a33fc3 SL |
2245 | fraction[0] = ap; |
2246 | fraction[1] = fp; | |
2247 | denominator = ap + fp + 1; | |
2248 | out: | |
688035f7 JW |
2249 | *lru_pages = 0; |
2250 | for_each_evictable_lru(lru) { | |
2251 | int file = is_file_lru(lru); | |
2252 | unsigned long size; | |
2253 | unsigned long scan; | |
6b4f7799 | 2254 | |
688035f7 JW |
2255 | size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); |
2256 | scan = size >> sc->priority; | |
2257 | /* | |
2258 | * If the cgroup's already been deleted, make sure to | |
2259 | * scrape out the remaining cache. | |
2260 | */ | |
2261 | if (!scan && !mem_cgroup_online(memcg)) | |
2262 | scan = min(size, SWAP_CLUSTER_MAX); | |
6b4f7799 | 2263 | |
688035f7 JW |
2264 | switch (scan_balance) { |
2265 | case SCAN_EQUAL: | |
2266 | /* Scan lists relative to size */ | |
2267 | break; | |
2268 | case SCAN_FRACT: | |
9a265114 | 2269 | /* |
688035f7 JW |
2270 | * Scan types proportional to swappiness and |
2271 | * their relative recent reclaim efficiency. | |
9a265114 | 2272 | */ |
688035f7 JW |
2273 | scan = div64_u64(scan * fraction[file], |
2274 | denominator); | |
2275 | break; | |
2276 | case SCAN_FILE: | |
2277 | case SCAN_ANON: | |
2278 | /* Scan one type exclusively */ | |
2279 | if ((scan_balance == SCAN_FILE) != file) { | |
2280 | size = 0; | |
2281 | scan = 0; | |
2282 | } | |
2283 | break; | |
2284 | default: | |
2285 | /* Look ma, no brain */ | |
2286 | BUG(); | |
9a265114 | 2287 | } |
688035f7 JW |
2288 | |
2289 | *lru_pages += size; | |
2290 | nr[lru] = scan; | |
76a33fc3 | 2291 | } |
6e08a369 | 2292 | } |
4f98a2fe | 2293 | |
9b4f98cd | 2294 | /* |
a9dd0a83 | 2295 | * This is a basic per-node page freer. Used by both kswapd and direct reclaim. |
9b4f98cd | 2296 | */ |
a9dd0a83 | 2297 | static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, |
33377678 | 2298 | struct scan_control *sc, unsigned long *lru_pages) |
9b4f98cd | 2299 | { |
ef8f2327 | 2300 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
9b4f98cd | 2301 | unsigned long nr[NR_LRU_LISTS]; |
e82e0561 | 2302 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2303 | unsigned long nr_to_scan; |
2304 | enum lru_list lru; | |
2305 | unsigned long nr_reclaimed = 0; | |
2306 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2307 | struct blk_plug plug; | |
1a501907 | 2308 | bool scan_adjusted; |
9b4f98cd | 2309 | |
33377678 | 2310 | get_scan_count(lruvec, memcg, sc, nr, lru_pages); |
9b4f98cd | 2311 | |
e82e0561 MG |
2312 | /* Record the original scan target for proportional adjustments later */ |
2313 | memcpy(targets, nr, sizeof(nr)); | |
2314 | ||
1a501907 MG |
2315 | /* |
2316 | * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal | |
2317 | * event that can occur when there is little memory pressure e.g. | |
2318 | * multiple streaming readers/writers. Hence, we do not abort scanning | |
2319 | * when the requested number of pages are reclaimed when scanning at | |
2320 | * DEF_PRIORITY on the assumption that the fact we are direct | |
2321 | * reclaiming implies that kswapd is not keeping up and it is best to | |
2322 | * do a batch of work at once. For memcg reclaim one check is made to | |
2323 | * abort proportional reclaim if either the file or anon lru has already | |
2324 | * dropped to zero at the first pass. | |
2325 | */ | |
2326 | scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && | |
2327 | sc->priority == DEF_PRIORITY); | |
2328 | ||
9b4f98cd JW |
2329 | blk_start_plug(&plug); |
2330 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2331 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2332 | unsigned long nr_anon, nr_file, percentage; |
2333 | unsigned long nr_scanned; | |
2334 | ||
9b4f98cd JW |
2335 | for_each_evictable_lru(lru) { |
2336 | if (nr[lru]) { | |
2337 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2338 | nr[lru] -= nr_to_scan; | |
2339 | ||
2340 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
2341 | lruvec, sc); | |
2342 | } | |
2343 | } | |
e82e0561 | 2344 | |
bd041733 MH |
2345 | cond_resched(); |
2346 | ||
e82e0561 MG |
2347 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) |
2348 | continue; | |
2349 | ||
e82e0561 MG |
2350 | /* |
2351 | * For kswapd and memcg, reclaim at least the number of pages | |
1a501907 | 2352 | * requested. Ensure that the anon and file LRUs are scanned |
e82e0561 MG |
2353 | * proportionally what was requested by get_scan_count(). We |
2354 | * stop reclaiming one LRU and reduce the amount scanning | |
2355 | * proportional to the original scan target. | |
2356 | */ | |
2357 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2358 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2359 | ||
1a501907 MG |
2360 | /* |
2361 | * It's just vindictive to attack the larger once the smaller | |
2362 | * has gone to zero. And given the way we stop scanning the | |
2363 | * smaller below, this makes sure that we only make one nudge | |
2364 | * towards proportionality once we've got nr_to_reclaim. | |
2365 | */ | |
2366 | if (!nr_file || !nr_anon) | |
2367 | break; | |
2368 | ||
e82e0561 MG |
2369 | if (nr_file > nr_anon) { |
2370 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2371 | targets[LRU_ACTIVE_ANON] + 1; | |
2372 | lru = LRU_BASE; | |
2373 | percentage = nr_anon * 100 / scan_target; | |
2374 | } else { | |
2375 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2376 | targets[LRU_ACTIVE_FILE] + 1; | |
2377 | lru = LRU_FILE; | |
2378 | percentage = nr_file * 100 / scan_target; | |
2379 | } | |
2380 | ||
2381 | /* Stop scanning the smaller of the LRU */ | |
2382 | nr[lru] = 0; | |
2383 | nr[lru + LRU_ACTIVE] = 0; | |
2384 | ||
2385 | /* | |
2386 | * Recalculate the other LRU scan count based on its original | |
2387 | * scan target and the percentage scanning already complete | |
2388 | */ | |
2389 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2390 | nr_scanned = targets[lru] - nr[lru]; | |
2391 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2392 | nr[lru] -= min(nr[lru], nr_scanned); | |
2393 | ||
2394 | lru += LRU_ACTIVE; | |
2395 | nr_scanned = targets[lru] - nr[lru]; | |
2396 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2397 | nr[lru] -= min(nr[lru], nr_scanned); | |
2398 | ||
2399 | scan_adjusted = true; | |
9b4f98cd JW |
2400 | } |
2401 | blk_finish_plug(&plug); | |
2402 | sc->nr_reclaimed += nr_reclaimed; | |
2403 | ||
2404 | /* | |
2405 | * Even if we did not try to evict anon pages at all, we want to | |
2406 | * rebalance the anon lru active/inactive ratio. | |
2407 | */ | |
dcec0b60 | 2408 | if (inactive_list_is_low(lruvec, false, sc, true)) |
9b4f98cd JW |
2409 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
2410 | sc, LRU_ACTIVE_ANON); | |
9b4f98cd JW |
2411 | } |
2412 | ||
23b9da55 | 2413 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2414 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2415 | { |
d84da3f9 | 2416 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2417 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2418 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2419 | return true; |
2420 | ||
2421 | return false; | |
2422 | } | |
2423 | ||
3e7d3449 | 2424 | /* |
23b9da55 MG |
2425 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2426 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2427 | * true if more pages should be reclaimed such that when the page allocator | |
2428 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2429 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2430 | */ |
a9dd0a83 | 2431 | static inline bool should_continue_reclaim(struct pglist_data *pgdat, |
3e7d3449 MG |
2432 | unsigned long nr_reclaimed, |
2433 | unsigned long nr_scanned, | |
2434 | struct scan_control *sc) | |
2435 | { | |
2436 | unsigned long pages_for_compaction; | |
2437 | unsigned long inactive_lru_pages; | |
a9dd0a83 | 2438 | int z; |
3e7d3449 MG |
2439 | |
2440 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2441 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2442 | return false; |
2443 | ||
2876592f MG |
2444 | /* Consider stopping depending on scan and reclaim activity */ |
2445 | if (sc->gfp_mask & __GFP_REPEAT) { | |
2446 | /* | |
2447 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
2448 | * full LRU list has been scanned and we are still failing | |
2449 | * to reclaim pages. This full LRU scan is potentially | |
2450 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
2451 | */ | |
2452 | if (!nr_reclaimed && !nr_scanned) | |
2453 | return false; | |
2454 | } else { | |
2455 | /* | |
2456 | * For non-__GFP_REPEAT allocations which can presumably | |
2457 | * fail without consequence, stop if we failed to reclaim | |
2458 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2459 | * pages that were scanned. This will return to the | |
2460 | * caller faster at the risk reclaim/compaction and | |
2461 | * the resulting allocation attempt fails | |
2462 | */ | |
2463 | if (!nr_reclaimed) | |
2464 | return false; | |
2465 | } | |
3e7d3449 MG |
2466 | |
2467 | /* | |
2468 | * If we have not reclaimed enough pages for compaction and the | |
2469 | * inactive lists are large enough, continue reclaiming | |
2470 | */ | |
9861a62c | 2471 | pages_for_compaction = compact_gap(sc->order); |
a9dd0a83 | 2472 | inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); |
ec8acf20 | 2473 | if (get_nr_swap_pages() > 0) |
a9dd0a83 | 2474 | inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); |
3e7d3449 MG |
2475 | if (sc->nr_reclaimed < pages_for_compaction && |
2476 | inactive_lru_pages > pages_for_compaction) | |
2477 | return true; | |
2478 | ||
2479 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
a9dd0a83 MG |
2480 | for (z = 0; z <= sc->reclaim_idx; z++) { |
2481 | struct zone *zone = &pgdat->node_zones[z]; | |
6aa303de | 2482 | if (!managed_zone(zone)) |
a9dd0a83 MG |
2483 | continue; |
2484 | ||
2485 | switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) { | |
cf378319 | 2486 | case COMPACT_SUCCESS: |
a9dd0a83 MG |
2487 | case COMPACT_CONTINUE: |
2488 | return false; | |
2489 | default: | |
2490 | /* check next zone */ | |
2491 | ; | |
2492 | } | |
3e7d3449 | 2493 | } |
a9dd0a83 | 2494 | return true; |
3e7d3449 MG |
2495 | } |
2496 | ||
970a39a3 | 2497 | static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) |
1da177e4 | 2498 | { |
cb731d6c | 2499 | struct reclaim_state *reclaim_state = current->reclaim_state; |
f0fdc5e8 | 2500 | unsigned long nr_reclaimed, nr_scanned; |
2344d7e4 | 2501 | bool reclaimable = false; |
1da177e4 | 2502 | |
9b4f98cd JW |
2503 | do { |
2504 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2505 | struct mem_cgroup_reclaim_cookie reclaim = { | |
ef8f2327 | 2506 | .pgdat = pgdat, |
9b4f98cd JW |
2507 | .priority = sc->priority, |
2508 | }; | |
a9dd0a83 | 2509 | unsigned long node_lru_pages = 0; |
694fbc0f | 2510 | struct mem_cgroup *memcg; |
3e7d3449 | 2511 | |
9b4f98cd JW |
2512 | nr_reclaimed = sc->nr_reclaimed; |
2513 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2514 | |
694fbc0f AM |
2515 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2516 | do { | |
6b4f7799 | 2517 | unsigned long lru_pages; |
8e8ae645 | 2518 | unsigned long reclaimed; |
cb731d6c | 2519 | unsigned long scanned; |
5660048c | 2520 | |
241994ed JW |
2521 | if (mem_cgroup_low(root, memcg)) { |
2522 | if (!sc->may_thrash) | |
2523 | continue; | |
2524 | mem_cgroup_events(memcg, MEMCG_LOW, 1); | |
2525 | } | |
2526 | ||
8e8ae645 | 2527 | reclaimed = sc->nr_reclaimed; |
cb731d6c | 2528 | scanned = sc->nr_scanned; |
f9be23d6 | 2529 | |
a9dd0a83 MG |
2530 | shrink_node_memcg(pgdat, memcg, sc, &lru_pages); |
2531 | node_lru_pages += lru_pages; | |
f16015fb | 2532 | |
b5afba29 | 2533 | if (memcg) |
a9dd0a83 | 2534 | shrink_slab(sc->gfp_mask, pgdat->node_id, |
cb731d6c VD |
2535 | memcg, sc->nr_scanned - scanned, |
2536 | lru_pages); | |
2537 | ||
8e8ae645 JW |
2538 | /* Record the group's reclaim efficiency */ |
2539 | vmpressure(sc->gfp_mask, memcg, false, | |
2540 | sc->nr_scanned - scanned, | |
2541 | sc->nr_reclaimed - reclaimed); | |
2542 | ||
9b4f98cd | 2543 | /* |
a394cb8e MH |
2544 | * Direct reclaim and kswapd have to scan all memory |
2545 | * cgroups to fulfill the overall scan target for the | |
a9dd0a83 | 2546 | * node. |
a394cb8e MH |
2547 | * |
2548 | * Limit reclaim, on the other hand, only cares about | |
2549 | * nr_to_reclaim pages to be reclaimed and it will | |
2550 | * retry with decreasing priority if one round over the | |
2551 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2552 | */ |
a394cb8e MH |
2553 | if (!global_reclaim(sc) && |
2554 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2555 | mem_cgroup_iter_break(root, memcg); |
2556 | break; | |
2557 | } | |
241994ed | 2558 | } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); |
70ddf637 | 2559 | |
6b4f7799 JW |
2560 | /* |
2561 | * Shrink the slab caches in the same proportion that | |
2562 | * the eligible LRU pages were scanned. | |
2563 | */ | |
b2e18757 | 2564 | if (global_reclaim(sc)) |
a9dd0a83 | 2565 | shrink_slab(sc->gfp_mask, pgdat->node_id, NULL, |
cb731d6c | 2566 | sc->nr_scanned - nr_scanned, |
a9dd0a83 | 2567 | node_lru_pages); |
cb731d6c VD |
2568 | |
2569 | if (reclaim_state) { | |
2570 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; | |
2571 | reclaim_state->reclaimed_slab = 0; | |
6b4f7799 JW |
2572 | } |
2573 | ||
8e8ae645 JW |
2574 | /* Record the subtree's reclaim efficiency */ |
2575 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, | |
70ddf637 AV |
2576 | sc->nr_scanned - nr_scanned, |
2577 | sc->nr_reclaimed - nr_reclaimed); | |
2578 | ||
2344d7e4 JW |
2579 | if (sc->nr_reclaimed - nr_reclaimed) |
2580 | reclaimable = true; | |
2581 | ||
a9dd0a83 | 2582 | } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, |
9b4f98cd | 2583 | sc->nr_scanned - nr_scanned, sc)); |
2344d7e4 | 2584 | |
c73322d0 JW |
2585 | /* |
2586 | * Kswapd gives up on balancing particular nodes after too | |
2587 | * many failures to reclaim anything from them and goes to | |
2588 | * sleep. On reclaim progress, reset the failure counter. A | |
2589 | * successful direct reclaim run will revive a dormant kswapd. | |
2590 | */ | |
2591 | if (reclaimable) | |
2592 | pgdat->kswapd_failures = 0; | |
2593 | ||
2344d7e4 | 2594 | return reclaimable; |
f16015fb JW |
2595 | } |
2596 | ||
53853e2d | 2597 | /* |
fdd4c614 VB |
2598 | * Returns true if compaction should go ahead for a costly-order request, or |
2599 | * the allocation would already succeed without compaction. Return false if we | |
2600 | * should reclaim first. | |
53853e2d | 2601 | */ |
4f588331 | 2602 | static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) |
fe4b1b24 | 2603 | { |
31483b6a | 2604 | unsigned long watermark; |
fdd4c614 | 2605 | enum compact_result suitable; |
fe4b1b24 | 2606 | |
fdd4c614 VB |
2607 | suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); |
2608 | if (suitable == COMPACT_SUCCESS) | |
2609 | /* Allocation should succeed already. Don't reclaim. */ | |
2610 | return true; | |
2611 | if (suitable == COMPACT_SKIPPED) | |
2612 | /* Compaction cannot yet proceed. Do reclaim. */ | |
2613 | return false; | |
fe4b1b24 | 2614 | |
53853e2d | 2615 | /* |
fdd4c614 VB |
2616 | * Compaction is already possible, but it takes time to run and there |
2617 | * are potentially other callers using the pages just freed. So proceed | |
2618 | * with reclaim to make a buffer of free pages available to give | |
2619 | * compaction a reasonable chance of completing and allocating the page. | |
2620 | * Note that we won't actually reclaim the whole buffer in one attempt | |
2621 | * as the target watermark in should_continue_reclaim() is lower. But if | |
2622 | * we are already above the high+gap watermark, don't reclaim at all. | |
53853e2d | 2623 | */ |
fdd4c614 | 2624 | watermark = high_wmark_pages(zone) + compact_gap(sc->order); |
fe4b1b24 | 2625 | |
fdd4c614 | 2626 | return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); |
fe4b1b24 MG |
2627 | } |
2628 | ||
1da177e4 LT |
2629 | /* |
2630 | * This is the direct reclaim path, for page-allocating processes. We only | |
2631 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2632 | * request. | |
2633 | * | |
1da177e4 LT |
2634 | * If a zone is deemed to be full of pinned pages then just give it a light |
2635 | * scan then give up on it. | |
2636 | */ | |
0a0337e0 | 2637 | static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2638 | { |
dd1a239f | 2639 | struct zoneref *z; |
54a6eb5c | 2640 | struct zone *zone; |
0608f43d AM |
2641 | unsigned long nr_soft_reclaimed; |
2642 | unsigned long nr_soft_scanned; | |
619d0d76 | 2643 | gfp_t orig_mask; |
79dafcdc | 2644 | pg_data_t *last_pgdat = NULL; |
1cfb419b | 2645 | |
cc715d99 MG |
2646 | /* |
2647 | * If the number of buffer_heads in the machine exceeds the maximum | |
2648 | * allowed level, force direct reclaim to scan the highmem zone as | |
2649 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2650 | */ | |
619d0d76 | 2651 | orig_mask = sc->gfp_mask; |
b2e18757 | 2652 | if (buffer_heads_over_limit) { |
cc715d99 | 2653 | sc->gfp_mask |= __GFP_HIGHMEM; |
4f588331 | 2654 | sc->reclaim_idx = gfp_zone(sc->gfp_mask); |
b2e18757 | 2655 | } |
cc715d99 | 2656 | |
d4debc66 | 2657 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
b2e18757 | 2658 | sc->reclaim_idx, sc->nodemask) { |
1cfb419b KH |
2659 | /* |
2660 | * Take care memory controller reclaiming has small influence | |
2661 | * to global LRU. | |
2662 | */ | |
89b5fae5 | 2663 | if (global_reclaim(sc)) { |
344736f2 VD |
2664 | if (!cpuset_zone_allowed(zone, |
2665 | GFP_KERNEL | __GFP_HARDWALL)) | |
1cfb419b | 2666 | continue; |
65ec02cb | 2667 | |
0b06496a JW |
2668 | /* |
2669 | * If we already have plenty of memory free for | |
2670 | * compaction in this zone, don't free any more. | |
2671 | * Even though compaction is invoked for any | |
2672 | * non-zero order, only frequent costly order | |
2673 | * reclamation is disruptive enough to become a | |
2674 | * noticeable problem, like transparent huge | |
2675 | * page allocations. | |
2676 | */ | |
2677 | if (IS_ENABLED(CONFIG_COMPACTION) && | |
2678 | sc->order > PAGE_ALLOC_COSTLY_ORDER && | |
4f588331 | 2679 | compaction_ready(zone, sc)) { |
0b06496a JW |
2680 | sc->compaction_ready = true; |
2681 | continue; | |
e0887c19 | 2682 | } |
0b06496a | 2683 | |
79dafcdc MG |
2684 | /* |
2685 | * Shrink each node in the zonelist once. If the | |
2686 | * zonelist is ordered by zone (not the default) then a | |
2687 | * node may be shrunk multiple times but in that case | |
2688 | * the user prefers lower zones being preserved. | |
2689 | */ | |
2690 | if (zone->zone_pgdat == last_pgdat) | |
2691 | continue; | |
2692 | ||
0608f43d AM |
2693 | /* |
2694 | * This steals pages from memory cgroups over softlimit | |
2695 | * and returns the number of reclaimed pages and | |
2696 | * scanned pages. This works for global memory pressure | |
2697 | * and balancing, not for a memcg's limit. | |
2698 | */ | |
2699 | nr_soft_scanned = 0; | |
ef8f2327 | 2700 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat, |
0608f43d AM |
2701 | sc->order, sc->gfp_mask, |
2702 | &nr_soft_scanned); | |
2703 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2704 | sc->nr_scanned += nr_soft_scanned; | |
ac34a1a3 | 2705 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2706 | } |
408d8544 | 2707 | |
79dafcdc MG |
2708 | /* See comment about same check for global reclaim above */ |
2709 | if (zone->zone_pgdat == last_pgdat) | |
2710 | continue; | |
2711 | last_pgdat = zone->zone_pgdat; | |
970a39a3 | 2712 | shrink_node(zone->zone_pgdat, sc); |
1da177e4 | 2713 | } |
e0c23279 | 2714 | |
619d0d76 WY |
2715 | /* |
2716 | * Restore to original mask to avoid the impact on the caller if we | |
2717 | * promoted it to __GFP_HIGHMEM. | |
2718 | */ | |
2719 | sc->gfp_mask = orig_mask; | |
1da177e4 | 2720 | } |
4f98a2fe | 2721 | |
1da177e4 LT |
2722 | /* |
2723 | * This is the main entry point to direct page reclaim. | |
2724 | * | |
2725 | * If a full scan of the inactive list fails to free enough memory then we | |
2726 | * are "out of memory" and something needs to be killed. | |
2727 | * | |
2728 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2729 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2730 | * caller can't do much about. We kick the writeback threads and take explicit |
2731 | * naps in the hope that some of these pages can be written. But if the | |
2732 | * allocating task holds filesystem locks which prevent writeout this might not | |
2733 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2734 | * |
2735 | * returns: 0, if no pages reclaimed | |
2736 | * else, the number of pages reclaimed | |
1da177e4 | 2737 | */ |
dac1d27b | 2738 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
3115cd91 | 2739 | struct scan_control *sc) |
1da177e4 | 2740 | { |
241994ed | 2741 | int initial_priority = sc->priority; |
241994ed | 2742 | retry: |
873b4771 KK |
2743 | delayacct_freepages_start(); |
2744 | ||
89b5fae5 | 2745 | if (global_reclaim(sc)) |
7cc30fcf | 2746 | __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); |
1da177e4 | 2747 | |
9e3b2f8c | 2748 | do { |
70ddf637 AV |
2749 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
2750 | sc->priority); | |
66e1707b | 2751 | sc->nr_scanned = 0; |
0a0337e0 | 2752 | shrink_zones(zonelist, sc); |
c6a8a8c5 | 2753 | |
bb21c7ce | 2754 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
0b06496a JW |
2755 | break; |
2756 | ||
2757 | if (sc->compaction_ready) | |
2758 | break; | |
1da177e4 | 2759 | |
0e50ce3b MK |
2760 | /* |
2761 | * If we're getting trouble reclaiming, start doing | |
2762 | * writepage even in laptop mode. | |
2763 | */ | |
2764 | if (sc->priority < DEF_PRIORITY - 2) | |
2765 | sc->may_writepage = 1; | |
0b06496a | 2766 | } while (--sc->priority >= 0); |
bb21c7ce | 2767 | |
873b4771 KK |
2768 | delayacct_freepages_end(); |
2769 | ||
bb21c7ce KM |
2770 | if (sc->nr_reclaimed) |
2771 | return sc->nr_reclaimed; | |
2772 | ||
0cee34fd | 2773 | /* Aborted reclaim to try compaction? don't OOM, then */ |
0b06496a | 2774 | if (sc->compaction_ready) |
7335084d MG |
2775 | return 1; |
2776 | ||
241994ed JW |
2777 | /* Untapped cgroup reserves? Don't OOM, retry. */ |
2778 | if (!sc->may_thrash) { | |
2779 | sc->priority = initial_priority; | |
2780 | sc->may_thrash = 1; | |
2781 | goto retry; | |
2782 | } | |
2783 | ||
bb21c7ce | 2784 | return 0; |
1da177e4 LT |
2785 | } |
2786 | ||
c73322d0 | 2787 | static bool allow_direct_reclaim(pg_data_t *pgdat) |
5515061d MG |
2788 | { |
2789 | struct zone *zone; | |
2790 | unsigned long pfmemalloc_reserve = 0; | |
2791 | unsigned long free_pages = 0; | |
2792 | int i; | |
2793 | bool wmark_ok; | |
2794 | ||
c73322d0 JW |
2795 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) |
2796 | return true; | |
2797 | ||
5515061d MG |
2798 | for (i = 0; i <= ZONE_NORMAL; i++) { |
2799 | zone = &pgdat->node_zones[i]; | |
d450abd8 JW |
2800 | if (!managed_zone(zone)) |
2801 | continue; | |
2802 | ||
2803 | if (!zone_reclaimable_pages(zone)) | |
675becce MG |
2804 | continue; |
2805 | ||
5515061d MG |
2806 | pfmemalloc_reserve += min_wmark_pages(zone); |
2807 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
2808 | } | |
2809 | ||
675becce MG |
2810 | /* If there are no reserves (unexpected config) then do not throttle */ |
2811 | if (!pfmemalloc_reserve) | |
2812 | return true; | |
2813 | ||
5515061d MG |
2814 | wmark_ok = free_pages > pfmemalloc_reserve / 2; |
2815 | ||
2816 | /* kswapd must be awake if processes are being throttled */ | |
2817 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
38087d9b | 2818 | pgdat->kswapd_classzone_idx = min(pgdat->kswapd_classzone_idx, |
5515061d MG |
2819 | (enum zone_type)ZONE_NORMAL); |
2820 | wake_up_interruptible(&pgdat->kswapd_wait); | |
2821 | } | |
2822 | ||
2823 | return wmark_ok; | |
2824 | } | |
2825 | ||
2826 | /* | |
2827 | * Throttle direct reclaimers if backing storage is backed by the network | |
2828 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
2829 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
2830 | * when the low watermark is reached. |
2831 | * | |
2832 | * Returns true if a fatal signal was delivered during throttling. If this | |
2833 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 2834 | */ |
50694c28 | 2835 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
2836 | nodemask_t *nodemask) |
2837 | { | |
675becce | 2838 | struct zoneref *z; |
5515061d | 2839 | struct zone *zone; |
675becce | 2840 | pg_data_t *pgdat = NULL; |
5515061d MG |
2841 | |
2842 | /* | |
2843 | * Kernel threads should not be throttled as they may be indirectly | |
2844 | * responsible for cleaning pages necessary for reclaim to make forward | |
2845 | * progress. kjournald for example may enter direct reclaim while | |
2846 | * committing a transaction where throttling it could forcing other | |
2847 | * processes to block on log_wait_commit(). | |
2848 | */ | |
2849 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
2850 | goto out; |
2851 | ||
2852 | /* | |
2853 | * If a fatal signal is pending, this process should not throttle. | |
2854 | * It should return quickly so it can exit and free its memory | |
2855 | */ | |
2856 | if (fatal_signal_pending(current)) | |
2857 | goto out; | |
5515061d | 2858 | |
675becce MG |
2859 | /* |
2860 | * Check if the pfmemalloc reserves are ok by finding the first node | |
2861 | * with a usable ZONE_NORMAL or lower zone. The expectation is that | |
2862 | * GFP_KERNEL will be required for allocating network buffers when | |
2863 | * swapping over the network so ZONE_HIGHMEM is unusable. | |
2864 | * | |
2865 | * Throttling is based on the first usable node and throttled processes | |
2866 | * wait on a queue until kswapd makes progress and wakes them. There | |
2867 | * is an affinity then between processes waking up and where reclaim | |
2868 | * progress has been made assuming the process wakes on the same node. | |
2869 | * More importantly, processes running on remote nodes will not compete | |
2870 | * for remote pfmemalloc reserves and processes on different nodes | |
2871 | * should make reasonable progress. | |
2872 | */ | |
2873 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
17636faa | 2874 | gfp_zone(gfp_mask), nodemask) { |
675becce MG |
2875 | if (zone_idx(zone) > ZONE_NORMAL) |
2876 | continue; | |
2877 | ||
2878 | /* Throttle based on the first usable node */ | |
2879 | pgdat = zone->zone_pgdat; | |
c73322d0 | 2880 | if (allow_direct_reclaim(pgdat)) |
675becce MG |
2881 | goto out; |
2882 | break; | |
2883 | } | |
2884 | ||
2885 | /* If no zone was usable by the allocation flags then do not throttle */ | |
2886 | if (!pgdat) | |
50694c28 | 2887 | goto out; |
5515061d | 2888 | |
68243e76 MG |
2889 | /* Account for the throttling */ |
2890 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
2891 | ||
5515061d MG |
2892 | /* |
2893 | * If the caller cannot enter the filesystem, it's possible that it | |
2894 | * is due to the caller holding an FS lock or performing a journal | |
2895 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
2896 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
2897 | * blocked waiting on the same lock. Instead, throttle for up to a | |
2898 | * second before continuing. | |
2899 | */ | |
2900 | if (!(gfp_mask & __GFP_FS)) { | |
2901 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
c73322d0 | 2902 | allow_direct_reclaim(pgdat), HZ); |
50694c28 MG |
2903 | |
2904 | goto check_pending; | |
5515061d MG |
2905 | } |
2906 | ||
2907 | /* Throttle until kswapd wakes the process */ | |
2908 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
c73322d0 | 2909 | allow_direct_reclaim(pgdat)); |
50694c28 MG |
2910 | |
2911 | check_pending: | |
2912 | if (fatal_signal_pending(current)) | |
2913 | return true; | |
2914 | ||
2915 | out: | |
2916 | return false; | |
5515061d MG |
2917 | } |
2918 | ||
dac1d27b | 2919 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2920 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2921 | { |
33906bc5 | 2922 | unsigned long nr_reclaimed; |
66e1707b | 2923 | struct scan_control sc = { |
ee814fe2 | 2924 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
21caf2fc | 2925 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
b2e18757 | 2926 | .reclaim_idx = gfp_zone(gfp_mask), |
ee814fe2 JW |
2927 | .order = order, |
2928 | .nodemask = nodemask, | |
2929 | .priority = DEF_PRIORITY, | |
66e1707b | 2930 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2931 | .may_unmap = 1, |
2e2e4259 | 2932 | .may_swap = 1, |
66e1707b BS |
2933 | }; |
2934 | ||
5515061d | 2935 | /* |
50694c28 MG |
2936 | * Do not enter reclaim if fatal signal was delivered while throttled. |
2937 | * 1 is returned so that the page allocator does not OOM kill at this | |
2938 | * point. | |
5515061d | 2939 | */ |
50694c28 | 2940 | if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) |
5515061d MG |
2941 | return 1; |
2942 | ||
33906bc5 MG |
2943 | trace_mm_vmscan_direct_reclaim_begin(order, |
2944 | sc.may_writepage, | |
e5146b12 MG |
2945 | gfp_mask, |
2946 | sc.reclaim_idx); | |
33906bc5 | 2947 | |
3115cd91 | 2948 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
33906bc5 MG |
2949 | |
2950 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2951 | ||
2952 | return nr_reclaimed; | |
66e1707b BS |
2953 | } |
2954 | ||
c255a458 | 2955 | #ifdef CONFIG_MEMCG |
66e1707b | 2956 | |
a9dd0a83 | 2957 | unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, |
4e416953 | 2958 | gfp_t gfp_mask, bool noswap, |
ef8f2327 | 2959 | pg_data_t *pgdat, |
0ae5e89c | 2960 | unsigned long *nr_scanned) |
4e416953 BS |
2961 | { |
2962 | struct scan_control sc = { | |
b8f5c566 | 2963 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
ee814fe2 | 2964 | .target_mem_cgroup = memcg, |
4e416953 BS |
2965 | .may_writepage = !laptop_mode, |
2966 | .may_unmap = 1, | |
b2e18757 | 2967 | .reclaim_idx = MAX_NR_ZONES - 1, |
4e416953 | 2968 | .may_swap = !noswap, |
4e416953 | 2969 | }; |
6b4f7799 | 2970 | unsigned long lru_pages; |
0ae5e89c | 2971 | |
4e416953 BS |
2972 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2973 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 2974 | |
9e3b2f8c | 2975 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e | 2976 | sc.may_writepage, |
e5146b12 MG |
2977 | sc.gfp_mask, |
2978 | sc.reclaim_idx); | |
bdce6d9e | 2979 | |
4e416953 BS |
2980 | /* |
2981 | * NOTE: Although we can get the priority field, using it | |
2982 | * here is not a good idea, since it limits the pages we can scan. | |
a9dd0a83 | 2983 | * if we don't reclaim here, the shrink_node from balance_pgdat |
4e416953 BS |
2984 | * will pick up pages from other mem cgroup's as well. We hack |
2985 | * the priority and make it zero. | |
2986 | */ | |
ef8f2327 | 2987 | shrink_node_memcg(pgdat, memcg, &sc, &lru_pages); |
bdce6d9e KM |
2988 | |
2989 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2990 | ||
0ae5e89c | 2991 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2992 | return sc.nr_reclaimed; |
2993 | } | |
2994 | ||
72835c86 | 2995 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
b70a2a21 | 2996 | unsigned long nr_pages, |
a7885eb8 | 2997 | gfp_t gfp_mask, |
b70a2a21 | 2998 | bool may_swap) |
66e1707b | 2999 | { |
4e416953 | 3000 | struct zonelist *zonelist; |
bdce6d9e | 3001 | unsigned long nr_reclaimed; |
889976db | 3002 | int nid; |
66e1707b | 3003 | struct scan_control sc = { |
b70a2a21 | 3004 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
a09ed5e0 YH |
3005 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
3006 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
b2e18757 | 3007 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 JW |
3008 | .target_mem_cgroup = memcg, |
3009 | .priority = DEF_PRIORITY, | |
3010 | .may_writepage = !laptop_mode, | |
3011 | .may_unmap = 1, | |
b70a2a21 | 3012 | .may_swap = may_swap, |
a09ed5e0 | 3013 | }; |
66e1707b | 3014 | |
889976db YH |
3015 | /* |
3016 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
3017 | * take care of from where we get pages. So the node where we start the | |
3018 | * scan does not need to be the current node. | |
3019 | */ | |
72835c86 | 3020 | nid = mem_cgroup_select_victim_node(memcg); |
889976db | 3021 | |
c9634cf0 | 3022 | zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK]; |
bdce6d9e KM |
3023 | |
3024 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
3025 | sc.may_writepage, | |
e5146b12 MG |
3026 | sc.gfp_mask, |
3027 | sc.reclaim_idx); | |
bdce6d9e | 3028 | |
89a28483 | 3029 | current->flags |= PF_MEMALLOC; |
3115cd91 | 3030 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
89a28483 | 3031 | current->flags &= ~PF_MEMALLOC; |
bdce6d9e KM |
3032 | |
3033 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
3034 | ||
3035 | return nr_reclaimed; | |
66e1707b BS |
3036 | } |
3037 | #endif | |
3038 | ||
1d82de61 | 3039 | static void age_active_anon(struct pglist_data *pgdat, |
ef8f2327 | 3040 | struct scan_control *sc) |
f16015fb | 3041 | { |
b95a2f2d | 3042 | struct mem_cgroup *memcg; |
f16015fb | 3043 | |
b95a2f2d JW |
3044 | if (!total_swap_pages) |
3045 | return; | |
3046 | ||
3047 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
3048 | do { | |
ef8f2327 | 3049 | struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); |
b95a2f2d | 3050 | |
dcec0b60 | 3051 | if (inactive_list_is_low(lruvec, false, sc, true)) |
1a93be0e | 3052 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 3053 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
3054 | |
3055 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
3056 | } while (memcg); | |
f16015fb JW |
3057 | } |
3058 | ||
31483b6a | 3059 | static bool zone_balanced(struct zone *zone, int order, int classzone_idx) |
60cefed4 | 3060 | { |
31483b6a | 3061 | unsigned long mark = high_wmark_pages(zone); |
60cefed4 | 3062 | |
6256c6b4 MG |
3063 | if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx)) |
3064 | return false; | |
3065 | ||
3066 | /* | |
3067 | * If any eligible zone is balanced then the node is not considered | |
3068 | * to be congested or dirty | |
3069 | */ | |
3070 | clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags); | |
3071 | clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags); | |
c2f83143 | 3072 | clear_bit(PGDAT_WRITEBACK, &zone->zone_pgdat->flags); |
6256c6b4 MG |
3073 | |
3074 | return true; | |
60cefed4 JW |
3075 | } |
3076 | ||
5515061d MG |
3077 | /* |
3078 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
3079 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
3080 | * | |
3081 | * Returns true if kswapd is ready to sleep | |
3082 | */ | |
d9f21d42 | 3083 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f50de2d3 | 3084 | { |
1d82de61 MG |
3085 | int i; |
3086 | ||
5515061d | 3087 | /* |
9e5e3661 | 3088 | * The throttled processes are normally woken up in balance_pgdat() as |
c73322d0 | 3089 | * soon as allow_direct_reclaim() is true. But there is a potential |
9e5e3661 VB |
3090 | * race between when kswapd checks the watermarks and a process gets |
3091 | * throttled. There is also a potential race if processes get | |
3092 | * throttled, kswapd wakes, a large process exits thereby balancing the | |
3093 | * zones, which causes kswapd to exit balance_pgdat() before reaching | |
3094 | * the wake up checks. If kswapd is going to sleep, no process should | |
3095 | * be sleeping on pfmemalloc_wait, so wake them now if necessary. If | |
3096 | * the wake up is premature, processes will wake kswapd and get | |
3097 | * throttled again. The difference from wake ups in balance_pgdat() is | |
3098 | * that here we are under prepare_to_wait(). | |
5515061d | 3099 | */ |
9e5e3661 VB |
3100 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) |
3101 | wake_up_all(&pgdat->pfmemalloc_wait); | |
f50de2d3 | 3102 | |
c73322d0 JW |
3103 | /* Hopeless node, leave it to direct reclaim */ |
3104 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) | |
3105 | return true; | |
3106 | ||
1d82de61 MG |
3107 | for (i = 0; i <= classzone_idx; i++) { |
3108 | struct zone *zone = pgdat->node_zones + i; | |
3109 | ||
6aa303de | 3110 | if (!managed_zone(zone)) |
1d82de61 MG |
3111 | continue; |
3112 | ||
38087d9b MG |
3113 | if (!zone_balanced(zone, order, classzone_idx)) |
3114 | return false; | |
1d82de61 MG |
3115 | } |
3116 | ||
38087d9b | 3117 | return true; |
f50de2d3 MG |
3118 | } |
3119 | ||
75485363 | 3120 | /* |
1d82de61 MG |
3121 | * kswapd shrinks a node of pages that are at or below the highest usable |
3122 | * zone that is currently unbalanced. | |
b8e83b94 MG |
3123 | * |
3124 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
3125 | * reclaim or if the lack of progress was due to pages under writeback. |
3126 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 3127 | */ |
1d82de61 | 3128 | static bool kswapd_shrink_node(pg_data_t *pgdat, |
accf6242 | 3129 | struct scan_control *sc) |
75485363 | 3130 | { |
1d82de61 MG |
3131 | struct zone *zone; |
3132 | int z; | |
75485363 | 3133 | |
1d82de61 MG |
3134 | /* Reclaim a number of pages proportional to the number of zones */ |
3135 | sc->nr_to_reclaim = 0; | |
970a39a3 | 3136 | for (z = 0; z <= sc->reclaim_idx; z++) { |
1d82de61 | 3137 | zone = pgdat->node_zones + z; |
6aa303de | 3138 | if (!managed_zone(zone)) |
1d82de61 | 3139 | continue; |
7c954f6d | 3140 | |
1d82de61 MG |
3141 | sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX); |
3142 | } | |
7c954f6d MG |
3143 | |
3144 | /* | |
1d82de61 MG |
3145 | * Historically care was taken to put equal pressure on all zones but |
3146 | * now pressure is applied based on node LRU order. | |
7c954f6d | 3147 | */ |
970a39a3 | 3148 | shrink_node(pgdat, sc); |
283aba9f | 3149 | |
7c954f6d | 3150 | /* |
1d82de61 MG |
3151 | * Fragmentation may mean that the system cannot be rebalanced for |
3152 | * high-order allocations. If twice the allocation size has been | |
3153 | * reclaimed then recheck watermarks only at order-0 to prevent | |
3154 | * excessive reclaim. Assume that a process requested a high-order | |
3155 | * can direct reclaim/compact. | |
7c954f6d | 3156 | */ |
9861a62c | 3157 | if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) |
1d82de61 | 3158 | sc->order = 0; |
7c954f6d | 3159 | |
b8e83b94 | 3160 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
3161 | } |
3162 | ||
1da177e4 | 3163 | /* |
1d82de61 MG |
3164 | * For kswapd, balance_pgdat() will reclaim pages across a node from zones |
3165 | * that are eligible for use by the caller until at least one zone is | |
3166 | * balanced. | |
1da177e4 | 3167 | * |
1d82de61 | 3168 | * Returns the order kswapd finished reclaiming at. |
1da177e4 LT |
3169 | * |
3170 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 | 3171 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
1d82de61 MG |
3172 | * found to have free_pages <= high_wmark_pages(zone), any page is that zone |
3173 | * or lower is eligible for reclaim until at least one usable zone is | |
3174 | * balanced. | |
1da177e4 | 3175 | */ |
accf6242 | 3176 | static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) |
1da177e4 | 3177 | { |
1da177e4 | 3178 | int i; |
0608f43d AM |
3179 | unsigned long nr_soft_reclaimed; |
3180 | unsigned long nr_soft_scanned; | |
1d82de61 | 3181 | struct zone *zone; |
179e9639 AM |
3182 | struct scan_control sc = { |
3183 | .gfp_mask = GFP_KERNEL, | |
ee814fe2 | 3184 | .order = order, |
b8e83b94 | 3185 | .priority = DEF_PRIORITY, |
ee814fe2 | 3186 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3187 | .may_unmap = 1, |
2e2e4259 | 3188 | .may_swap = 1, |
179e9639 | 3189 | }; |
f8891e5e | 3190 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 3191 | |
9e3b2f8c | 3192 | do { |
c73322d0 | 3193 | unsigned long nr_reclaimed = sc.nr_reclaimed; |
b8e83b94 MG |
3194 | bool raise_priority = true; |
3195 | ||
84c7a777 | 3196 | sc.reclaim_idx = classzone_idx; |
1da177e4 | 3197 | |
86c79f6b | 3198 | /* |
84c7a777 MG |
3199 | * If the number of buffer_heads exceeds the maximum allowed |
3200 | * then consider reclaiming from all zones. This has a dual | |
3201 | * purpose -- on 64-bit systems it is expected that | |
3202 | * buffer_heads are stripped during active rotation. On 32-bit | |
3203 | * systems, highmem pages can pin lowmem memory and shrinking | |
3204 | * buffers can relieve lowmem pressure. Reclaim may still not | |
3205 | * go ahead if all eligible zones for the original allocation | |
3206 | * request are balanced to avoid excessive reclaim from kswapd. | |
86c79f6b MG |
3207 | */ |
3208 | if (buffer_heads_over_limit) { | |
3209 | for (i = MAX_NR_ZONES - 1; i >= 0; i--) { | |
3210 | zone = pgdat->node_zones + i; | |
6aa303de | 3211 | if (!managed_zone(zone)) |
86c79f6b | 3212 | continue; |
cc715d99 | 3213 | |
970a39a3 | 3214 | sc.reclaim_idx = i; |
e1dbeda6 | 3215 | break; |
1da177e4 | 3216 | } |
1da177e4 | 3217 | } |
dafcb73e | 3218 | |
86c79f6b MG |
3219 | /* |
3220 | * Only reclaim if there are no eligible zones. Check from | |
3221 | * high to low zone as allocations prefer higher zones. | |
3222 | * Scanning from low to high zone would allow congestion to be | |
3223 | * cleared during a very small window when a small low | |
3224 | * zone was balanced even under extreme pressure when the | |
84c7a777 MG |
3225 | * overall node may be congested. Note that sc.reclaim_idx |
3226 | * is not used as buffer_heads_over_limit may have adjusted | |
3227 | * it. | |
86c79f6b | 3228 | */ |
84c7a777 | 3229 | for (i = classzone_idx; i >= 0; i--) { |
86c79f6b | 3230 | zone = pgdat->node_zones + i; |
6aa303de | 3231 | if (!managed_zone(zone)) |
86c79f6b MG |
3232 | continue; |
3233 | ||
84c7a777 | 3234 | if (zone_balanced(zone, sc.order, classzone_idx)) |
86c79f6b MG |
3235 | goto out; |
3236 | } | |
e1dbeda6 | 3237 | |
1d82de61 MG |
3238 | /* |
3239 | * Do some background aging of the anon list, to give | |
3240 | * pages a chance to be referenced before reclaiming. All | |
3241 | * pages are rotated regardless of classzone as this is | |
3242 | * about consistent aging. | |
3243 | */ | |
ef8f2327 | 3244 | age_active_anon(pgdat, &sc); |
1d82de61 | 3245 | |
b7ea3c41 MG |
3246 | /* |
3247 | * If we're getting trouble reclaiming, start doing writepage | |
3248 | * even in laptop mode. | |
3249 | */ | |
047d72c3 | 3250 | if (sc.priority < DEF_PRIORITY - 2) |
b7ea3c41 MG |
3251 | sc.may_writepage = 1; |
3252 | ||
1d82de61 MG |
3253 | /* Call soft limit reclaim before calling shrink_node. */ |
3254 | sc.nr_scanned = 0; | |
3255 | nr_soft_scanned = 0; | |
ef8f2327 | 3256 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order, |
1d82de61 MG |
3257 | sc.gfp_mask, &nr_soft_scanned); |
3258 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3259 | ||
1da177e4 | 3260 | /* |
1d82de61 MG |
3261 | * There should be no need to raise the scanning priority if |
3262 | * enough pages are already being scanned that that high | |
3263 | * watermark would be met at 100% efficiency. | |
1da177e4 | 3264 | */ |
970a39a3 | 3265 | if (kswapd_shrink_node(pgdat, &sc)) |
1d82de61 | 3266 | raise_priority = false; |
5515061d MG |
3267 | |
3268 | /* | |
3269 | * If the low watermark is met there is no need for processes | |
3270 | * to be throttled on pfmemalloc_wait as they should not be | |
3271 | * able to safely make forward progress. Wake them | |
3272 | */ | |
3273 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
c73322d0 | 3274 | allow_direct_reclaim(pgdat)) |
cfc51155 | 3275 | wake_up_all(&pgdat->pfmemalloc_wait); |
5515061d | 3276 | |
b8e83b94 MG |
3277 | /* Check if kswapd should be suspending */ |
3278 | if (try_to_freeze() || kthread_should_stop()) | |
3279 | break; | |
8357376d | 3280 | |
73ce02e9 | 3281 | /* |
b8e83b94 MG |
3282 | * Raise priority if scanning rate is too low or there was no |
3283 | * progress in reclaiming pages | |
73ce02e9 | 3284 | */ |
c73322d0 JW |
3285 | nr_reclaimed = sc.nr_reclaimed - nr_reclaimed; |
3286 | if (raise_priority || !nr_reclaimed) | |
b8e83b94 | 3287 | sc.priority--; |
1d82de61 | 3288 | } while (sc.priority >= 1); |
1da177e4 | 3289 | |
c73322d0 JW |
3290 | if (!sc.nr_reclaimed) |
3291 | pgdat->kswapd_failures++; | |
3292 | ||
b8e83b94 | 3293 | out: |
0abdee2b | 3294 | /* |
1d82de61 MG |
3295 | * Return the order kswapd stopped reclaiming at as |
3296 | * prepare_kswapd_sleep() takes it into account. If another caller | |
3297 | * entered the allocator slow path while kswapd was awake, order will | |
3298 | * remain at the higher level. | |
0abdee2b | 3299 | */ |
1d82de61 | 3300 | return sc.order; |
1da177e4 LT |
3301 | } |
3302 | ||
38087d9b MG |
3303 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, |
3304 | unsigned int classzone_idx) | |
f0bc0a60 KM |
3305 | { |
3306 | long remaining = 0; | |
3307 | DEFINE_WAIT(wait); | |
3308 | ||
3309 | if (freezing(current) || kthread_should_stop()) | |
3310 | return; | |
3311 | ||
3312 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3313 | ||
3314 | /* Try to sleep for a short interval */ | |
d9f21d42 | 3315 | if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { |
fd901c95 VB |
3316 | /* |
3317 | * Compaction records what page blocks it recently failed to | |
3318 | * isolate pages from and skips them in the future scanning. | |
3319 | * When kswapd is going to sleep, it is reasonable to assume | |
3320 | * that pages and compaction may succeed so reset the cache. | |
3321 | */ | |
3322 | reset_isolation_suitable(pgdat); | |
3323 | ||
3324 | /* | |
3325 | * We have freed the memory, now we should compact it to make | |
3326 | * allocation of the requested order possible. | |
3327 | */ | |
38087d9b | 3328 | wakeup_kcompactd(pgdat, alloc_order, classzone_idx); |
fd901c95 | 3329 | |
f0bc0a60 | 3330 | remaining = schedule_timeout(HZ/10); |
38087d9b MG |
3331 | |
3332 | /* | |
3333 | * If woken prematurely then reset kswapd_classzone_idx and | |
3334 | * order. The values will either be from a wakeup request or | |
3335 | * the previous request that slept prematurely. | |
3336 | */ | |
3337 | if (remaining) { | |
3338 | pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); | |
3339 | pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order); | |
3340 | } | |
3341 | ||
f0bc0a60 KM |
3342 | finish_wait(&pgdat->kswapd_wait, &wait); |
3343 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3344 | } | |
3345 | ||
3346 | /* | |
3347 | * After a short sleep, check if it was a premature sleep. If not, then | |
3348 | * go fully to sleep until explicitly woken up. | |
3349 | */ | |
d9f21d42 MG |
3350 | if (!remaining && |
3351 | prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { | |
f0bc0a60 KM |
3352 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3353 | ||
3354 | /* | |
3355 | * vmstat counters are not perfectly accurate and the estimated | |
3356 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3357 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3358 | * watermarks being breached while under pressure, we reduce the | |
3359 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3360 | * them before going back to sleep. | |
3361 | */ | |
3362 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c AK |
3363 | |
3364 | if (!kthread_should_stop()) | |
3365 | schedule(); | |
3366 | ||
f0bc0a60 KM |
3367 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3368 | } else { | |
3369 | if (remaining) | |
3370 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3371 | else | |
3372 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3373 | } | |
3374 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3375 | } | |
3376 | ||
1da177e4 LT |
3377 | /* |
3378 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3379 | * from the init process. |
1da177e4 LT |
3380 | * |
3381 | * This basically trickles out pages so that we have _some_ | |
3382 | * free memory available even if there is no other activity | |
3383 | * that frees anything up. This is needed for things like routing | |
3384 | * etc, where we otherwise might have all activity going on in | |
3385 | * asynchronous contexts that cannot page things out. | |
3386 | * | |
3387 | * If there are applications that are active memory-allocators | |
3388 | * (most normal use), this basically shouldn't matter. | |
3389 | */ | |
3390 | static int kswapd(void *p) | |
3391 | { | |
38087d9b | 3392 | unsigned int alloc_order, reclaim_order, classzone_idx; |
1da177e4 LT |
3393 | pg_data_t *pgdat = (pg_data_t*)p; |
3394 | struct task_struct *tsk = current; | |
f0bc0a60 | 3395 | |
1da177e4 LT |
3396 | struct reclaim_state reclaim_state = { |
3397 | .reclaimed_slab = 0, | |
3398 | }; | |
a70f7302 | 3399 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3400 | |
cf40bd16 NP |
3401 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
3402 | ||
174596a0 | 3403 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3404 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3405 | current->reclaim_state = &reclaim_state; |
3406 | ||
3407 | /* | |
3408 | * Tell the memory management that we're a "memory allocator", | |
3409 | * and that if we need more memory we should get access to it | |
3410 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3411 | * never get caught in the normal page freeing logic. | |
3412 | * | |
3413 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3414 | * you need a small amount of memory in order to be able to | |
3415 | * page out something else, and this flag essentially protects | |
3416 | * us from recursively trying to free more memory as we're | |
3417 | * trying to free the first piece of memory in the first place). | |
3418 | */ | |
930d9152 | 3419 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3420 | set_freezable(); |
1da177e4 | 3421 | |
38087d9b MG |
3422 | pgdat->kswapd_order = alloc_order = reclaim_order = 0; |
3423 | pgdat->kswapd_classzone_idx = classzone_idx = 0; | |
1da177e4 | 3424 | for ( ; ; ) { |
6f6313d4 | 3425 | bool ret; |
3e1d1d28 | 3426 | |
38087d9b MG |
3427 | kswapd_try_sleep: |
3428 | kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, | |
3429 | classzone_idx); | |
215ddd66 | 3430 | |
38087d9b MG |
3431 | /* Read the new order and classzone_idx */ |
3432 | alloc_order = reclaim_order = pgdat->kswapd_order; | |
3433 | classzone_idx = pgdat->kswapd_classzone_idx; | |
3434 | pgdat->kswapd_order = 0; | |
3435 | pgdat->kswapd_classzone_idx = 0; | |
1da177e4 | 3436 | |
8fe23e05 DR |
3437 | ret = try_to_freeze(); |
3438 | if (kthread_should_stop()) | |
3439 | break; | |
3440 | ||
3441 | /* | |
3442 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3443 | * after returning from the refrigerator | |
3444 | */ | |
38087d9b MG |
3445 | if (ret) |
3446 | continue; | |
3447 | ||
3448 | /* | |
3449 | * Reclaim begins at the requested order but if a high-order | |
3450 | * reclaim fails then kswapd falls back to reclaiming for | |
3451 | * order-0. If that happens, kswapd will consider sleeping | |
3452 | * for the order it finished reclaiming at (reclaim_order) | |
3453 | * but kcompactd is woken to compact for the original | |
3454 | * request (alloc_order). | |
3455 | */ | |
e5146b12 MG |
3456 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx, |
3457 | alloc_order); | |
38087d9b MG |
3458 | reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); |
3459 | if (reclaim_order < alloc_order) | |
3460 | goto kswapd_try_sleep; | |
1d82de61 | 3461 | |
38087d9b MG |
3462 | alloc_order = reclaim_order = pgdat->kswapd_order; |
3463 | classzone_idx = pgdat->kswapd_classzone_idx; | |
1da177e4 | 3464 | } |
b0a8cc58 | 3465 | |
71abdc15 | 3466 | tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); |
b0a8cc58 | 3467 | current->reclaim_state = NULL; |
71abdc15 JW |
3468 | lockdep_clear_current_reclaim_state(); |
3469 | ||
1da177e4 LT |
3470 | return 0; |
3471 | } | |
3472 | ||
3473 | /* | |
3474 | * A zone is low on free memory, so wake its kswapd task to service it. | |
3475 | */ | |
99504748 | 3476 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
3477 | { |
3478 | pg_data_t *pgdat; | |
e1a55637 | 3479 | int z; |
1da177e4 | 3480 | |
6aa303de | 3481 | if (!managed_zone(zone)) |
1da177e4 LT |
3482 | return; |
3483 | ||
344736f2 | 3484 | if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) |
1da177e4 | 3485 | return; |
88f5acf8 | 3486 | pgdat = zone->zone_pgdat; |
38087d9b MG |
3487 | pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); |
3488 | pgdat->kswapd_order = max(pgdat->kswapd_order, order); | |
8d0986e2 | 3489 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3490 | return; |
e1a55637 | 3491 | |
c73322d0 JW |
3492 | /* Hopeless node, leave it to direct reclaim */ |
3493 | if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) | |
3494 | return; | |
3495 | ||
e1a55637 MG |
3496 | /* Only wake kswapd if all zones are unbalanced */ |
3497 | for (z = 0; z <= classzone_idx; z++) { | |
3498 | zone = pgdat->node_zones + z; | |
6aa303de | 3499 | if (!managed_zone(zone)) |
e1a55637 MG |
3500 | continue; |
3501 | ||
3502 | if (zone_balanced(zone, order, classzone_idx)) | |
3503 | return; | |
3504 | } | |
88f5acf8 MG |
3505 | |
3506 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 3507 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3508 | } |
3509 | ||
c6f37f12 | 3510 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3511 | /* |
7b51755c | 3512 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3513 | * freed pages. |
3514 | * | |
3515 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3516 | * LRU order by reclaiming preferentially | |
3517 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3518 | */ |
7b51755c | 3519 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3520 | { |
d6277db4 | 3521 | struct reclaim_state reclaim_state; |
d6277db4 | 3522 | struct scan_control sc = { |
ee814fe2 | 3523 | .nr_to_reclaim = nr_to_reclaim, |
7b51755c | 3524 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
b2e18757 | 3525 | .reclaim_idx = MAX_NR_ZONES - 1, |
ee814fe2 | 3526 | .priority = DEF_PRIORITY, |
d6277db4 | 3527 | .may_writepage = 1, |
ee814fe2 JW |
3528 | .may_unmap = 1, |
3529 | .may_swap = 1, | |
7b51755c | 3530 | .hibernation_mode = 1, |
1da177e4 | 3531 | }; |
a09ed5e0 | 3532 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
7b51755c KM |
3533 | struct task_struct *p = current; |
3534 | unsigned long nr_reclaimed; | |
1da177e4 | 3535 | |
7b51755c KM |
3536 | p->flags |= PF_MEMALLOC; |
3537 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
3538 | reclaim_state.reclaimed_slab = 0; | |
3539 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3540 | |
3115cd91 | 3541 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 3542 | |
7b51755c KM |
3543 | p->reclaim_state = NULL; |
3544 | lockdep_clear_current_reclaim_state(); | |
3545 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 3546 | |
7b51755c | 3547 | return nr_reclaimed; |
1da177e4 | 3548 | } |
c6f37f12 | 3549 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3550 | |
1da177e4 LT |
3551 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3552 | not required for correctness. So if the last cpu in a node goes | |
3553 | away, we get changed to run anywhere: as the first one comes back, | |
3554 | restore their cpu bindings. */ | |
517bbed9 | 3555 | static int kswapd_cpu_online(unsigned int cpu) |
1da177e4 | 3556 | { |
58c0a4a7 | 3557 | int nid; |
1da177e4 | 3558 | |
517bbed9 SAS |
3559 | for_each_node_state(nid, N_MEMORY) { |
3560 | pg_data_t *pgdat = NODE_DATA(nid); | |
3561 | const struct cpumask *mask; | |
a70f7302 | 3562 | |
517bbed9 | 3563 | mask = cpumask_of_node(pgdat->node_id); |
c5f59f08 | 3564 | |
517bbed9 SAS |
3565 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
3566 | /* One of our CPUs online: restore mask */ | |
3567 | set_cpus_allowed_ptr(pgdat->kswapd, mask); | |
1da177e4 | 3568 | } |
517bbed9 | 3569 | return 0; |
1da177e4 | 3570 | } |
1da177e4 | 3571 | |
3218ae14 YG |
3572 | /* |
3573 | * This kswapd start function will be called by init and node-hot-add. | |
3574 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3575 | */ | |
3576 | int kswapd_run(int nid) | |
3577 | { | |
3578 | pg_data_t *pgdat = NODE_DATA(nid); | |
3579 | int ret = 0; | |
3580 | ||
3581 | if (pgdat->kswapd) | |
3582 | return 0; | |
3583 | ||
3584 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3585 | if (IS_ERR(pgdat->kswapd)) { | |
3586 | /* failure at boot is fatal */ | |
3587 | BUG_ON(system_state == SYSTEM_BOOTING); | |
d5dc0ad9 GS |
3588 | pr_err("Failed to start kswapd on node %d\n", nid); |
3589 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3590 | pgdat->kswapd = NULL; |
3218ae14 YG |
3591 | } |
3592 | return ret; | |
3593 | } | |
3594 | ||
8fe23e05 | 3595 | /* |
d8adde17 | 3596 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
bfc8c901 | 3597 | * hold mem_hotplug_begin/end(). |
8fe23e05 DR |
3598 | */ |
3599 | void kswapd_stop(int nid) | |
3600 | { | |
3601 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3602 | ||
d8adde17 | 3603 | if (kswapd) { |
8fe23e05 | 3604 | kthread_stop(kswapd); |
d8adde17 JL |
3605 | NODE_DATA(nid)->kswapd = NULL; |
3606 | } | |
8fe23e05 DR |
3607 | } |
3608 | ||
1da177e4 LT |
3609 | static int __init kswapd_init(void) |
3610 | { | |
517bbed9 | 3611 | int nid, ret; |
69e05944 | 3612 | |
1da177e4 | 3613 | swap_setup(); |
48fb2e24 | 3614 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3615 | kswapd_run(nid); |
517bbed9 SAS |
3616 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, |
3617 | "mm/vmscan:online", kswapd_cpu_online, | |
3618 | NULL); | |
3619 | WARN_ON(ret < 0); | |
1da177e4 LT |
3620 | return 0; |
3621 | } | |
3622 | ||
3623 | module_init(kswapd_init) | |
9eeff239 CL |
3624 | |
3625 | #ifdef CONFIG_NUMA | |
3626 | /* | |
a5f5f91d | 3627 | * Node reclaim mode |
9eeff239 | 3628 | * |
a5f5f91d | 3629 | * If non-zero call node_reclaim when the number of free pages falls below |
9eeff239 | 3630 | * the watermarks. |
9eeff239 | 3631 | */ |
a5f5f91d | 3632 | int node_reclaim_mode __read_mostly; |
9eeff239 | 3633 | |
1b2ffb78 | 3634 | #define RECLAIM_OFF 0 |
7d03431c | 3635 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 | 3636 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
95bbc0c7 | 3637 | #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ |
1b2ffb78 | 3638 | |
a92f7126 | 3639 | /* |
a5f5f91d | 3640 | * Priority for NODE_RECLAIM. This determines the fraction of pages |
a92f7126 CL |
3641 | * of a node considered for each zone_reclaim. 4 scans 1/16th of |
3642 | * a zone. | |
3643 | */ | |
a5f5f91d | 3644 | #define NODE_RECLAIM_PRIORITY 4 |
a92f7126 | 3645 | |
9614634f | 3646 | /* |
a5f5f91d | 3647 | * Percentage of pages in a zone that must be unmapped for node_reclaim to |
9614634f CL |
3648 | * occur. |
3649 | */ | |
3650 | int sysctl_min_unmapped_ratio = 1; | |
3651 | ||
0ff38490 CL |
3652 | /* |
3653 | * If the number of slab pages in a zone grows beyond this percentage then | |
3654 | * slab reclaim needs to occur. | |
3655 | */ | |
3656 | int sysctl_min_slab_ratio = 5; | |
3657 | ||
11fb9989 | 3658 | static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat) |
90afa5de | 3659 | { |
11fb9989 MG |
3660 | unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED); |
3661 | unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) + | |
3662 | node_page_state(pgdat, NR_ACTIVE_FILE); | |
90afa5de MG |
3663 | |
3664 | /* | |
3665 | * It's possible for there to be more file mapped pages than | |
3666 | * accounted for by the pages on the file LRU lists because | |
3667 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3668 | */ | |
3669 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3670 | } | |
3671 | ||
3672 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
a5f5f91d | 3673 | static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) |
90afa5de | 3674 | { |
d031a157 AM |
3675 | unsigned long nr_pagecache_reclaimable; |
3676 | unsigned long delta = 0; | |
90afa5de MG |
3677 | |
3678 | /* | |
95bbc0c7 | 3679 | * If RECLAIM_UNMAP is set, then all file pages are considered |
90afa5de | 3680 | * potentially reclaimable. Otherwise, we have to worry about |
11fb9989 | 3681 | * pages like swapcache and node_unmapped_file_pages() provides |
90afa5de MG |
3682 | * a better estimate |
3683 | */ | |
a5f5f91d MG |
3684 | if (node_reclaim_mode & RECLAIM_UNMAP) |
3685 | nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES); | |
90afa5de | 3686 | else |
a5f5f91d | 3687 | nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat); |
90afa5de MG |
3688 | |
3689 | /* If we can't clean pages, remove dirty pages from consideration */ | |
a5f5f91d MG |
3690 | if (!(node_reclaim_mode & RECLAIM_WRITE)) |
3691 | delta += node_page_state(pgdat, NR_FILE_DIRTY); | |
90afa5de MG |
3692 | |
3693 | /* Watch for any possible underflows due to delta */ | |
3694 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3695 | delta = nr_pagecache_reclaimable; | |
3696 | ||
3697 | return nr_pagecache_reclaimable - delta; | |
3698 | } | |
3699 | ||
9eeff239 | 3700 | /* |
a5f5f91d | 3701 | * Try to free up some pages from this node through reclaim. |
9eeff239 | 3702 | */ |
a5f5f91d | 3703 | static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3704 | { |
7fb2d46d | 3705 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3706 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3707 | struct task_struct *p = current; |
3708 | struct reclaim_state reclaim_state; | |
a5f5f91d | 3709 | int classzone_idx = gfp_zone(gfp_mask); |
179e9639 | 3710 | struct scan_control sc = { |
62b726c1 | 3711 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
21caf2fc | 3712 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
bd2f6199 | 3713 | .order = order, |
a5f5f91d MG |
3714 | .priority = NODE_RECLAIM_PRIORITY, |
3715 | .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), | |
3716 | .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), | |
ee814fe2 | 3717 | .may_swap = 1, |
a5f5f91d | 3718 | .reclaim_idx = classzone_idx, |
179e9639 | 3719 | }; |
9eeff239 | 3720 | |
9eeff239 | 3721 | cond_resched(); |
d4f7796e | 3722 | /* |
95bbc0c7 | 3723 | * We need to be able to allocate from the reserves for RECLAIM_UNMAP |
d4f7796e | 3724 | * and we also need to be able to write out pages for RECLAIM_WRITE |
95bbc0c7 | 3725 | * and RECLAIM_UNMAP. |
d4f7796e CL |
3726 | */ |
3727 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3728 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3729 | reclaim_state.reclaimed_slab = 0; |
3730 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3731 | |
a5f5f91d | 3732 | if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) { |
0ff38490 CL |
3733 | /* |
3734 | * Free memory by calling shrink zone with increasing | |
3735 | * priorities until we have enough memory freed. | |
3736 | */ | |
0ff38490 | 3737 | do { |
970a39a3 | 3738 | shrink_node(pgdat, &sc); |
9e3b2f8c | 3739 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); |
0ff38490 | 3740 | } |
c84db23c | 3741 | |
9eeff239 | 3742 | p->reclaim_state = NULL; |
d4f7796e | 3743 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3744 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3745 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3746 | } |
179e9639 | 3747 | |
a5f5f91d | 3748 | int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) |
179e9639 | 3749 | { |
d773ed6b | 3750 | int ret; |
179e9639 AM |
3751 | |
3752 | /* | |
a5f5f91d | 3753 | * Node reclaim reclaims unmapped file backed pages and |
0ff38490 | 3754 | * slab pages if we are over the defined limits. |
34aa1330 | 3755 | * |
9614634f CL |
3756 | * A small portion of unmapped file backed pages is needed for |
3757 | * file I/O otherwise pages read by file I/O will be immediately | |
a5f5f91d MG |
3758 | * thrown out if the node is overallocated. So we do not reclaim |
3759 | * if less than a specified percentage of the node is used by | |
9614634f | 3760 | * unmapped file backed pages. |
179e9639 | 3761 | */ |
a5f5f91d MG |
3762 | if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && |
3763 | sum_zone_node_page_state(pgdat->node_id, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages) | |
3764 | return NODE_RECLAIM_FULL; | |
179e9639 AM |
3765 | |
3766 | /* | |
d773ed6b | 3767 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3768 | */ |
d0164adc | 3769 | if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) |
a5f5f91d | 3770 | return NODE_RECLAIM_NOSCAN; |
179e9639 AM |
3771 | |
3772 | /* | |
a5f5f91d | 3773 | * Only run node reclaim on the local node or on nodes that do not |
179e9639 AM |
3774 | * have associated processors. This will favor the local processor |
3775 | * over remote processors and spread off node memory allocations | |
3776 | * as wide as possible. | |
3777 | */ | |
a5f5f91d MG |
3778 | if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) |
3779 | return NODE_RECLAIM_NOSCAN; | |
d773ed6b | 3780 | |
a5f5f91d MG |
3781 | if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) |
3782 | return NODE_RECLAIM_NOSCAN; | |
fa5e084e | 3783 | |
a5f5f91d MG |
3784 | ret = __node_reclaim(pgdat, gfp_mask, order); |
3785 | clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags); | |
d773ed6b | 3786 | |
24cf7251 MG |
3787 | if (!ret) |
3788 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3789 | ||
d773ed6b | 3790 | return ret; |
179e9639 | 3791 | } |
9eeff239 | 3792 | #endif |
894bc310 | 3793 | |
894bc310 LS |
3794 | /* |
3795 | * page_evictable - test whether a page is evictable | |
3796 | * @page: the page to test | |
894bc310 LS |
3797 | * |
3798 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 3799 | * lists vs unevictable list. |
894bc310 LS |
3800 | * |
3801 | * Reasons page might not be evictable: | |
ba9ddf49 | 3802 | * (1) page's mapping marked unevictable |
b291f000 | 3803 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3804 | * |
894bc310 | 3805 | */ |
39b5f29a | 3806 | int page_evictable(struct page *page) |
894bc310 | 3807 | { |
39b5f29a | 3808 | return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); |
894bc310 | 3809 | } |
89e004ea | 3810 | |
85046579 | 3811 | #ifdef CONFIG_SHMEM |
89e004ea | 3812 | /** |
24513264 HD |
3813 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
3814 | * @pages: array of pages to check | |
3815 | * @nr_pages: number of pages to check | |
89e004ea | 3816 | * |
24513264 | 3817 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
3818 | * |
3819 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 3820 | */ |
24513264 | 3821 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 3822 | { |
925b7673 | 3823 | struct lruvec *lruvec; |
785b99fe | 3824 | struct pglist_data *pgdat = NULL; |
24513264 HD |
3825 | int pgscanned = 0; |
3826 | int pgrescued = 0; | |
3827 | int i; | |
89e004ea | 3828 | |
24513264 HD |
3829 | for (i = 0; i < nr_pages; i++) { |
3830 | struct page *page = pages[i]; | |
785b99fe | 3831 | struct pglist_data *pagepgdat = page_pgdat(page); |
89e004ea | 3832 | |
24513264 | 3833 | pgscanned++; |
785b99fe MG |
3834 | if (pagepgdat != pgdat) { |
3835 | if (pgdat) | |
3836 | spin_unlock_irq(&pgdat->lru_lock); | |
3837 | pgdat = pagepgdat; | |
3838 | spin_lock_irq(&pgdat->lru_lock); | |
24513264 | 3839 | } |
785b99fe | 3840 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
89e004ea | 3841 | |
24513264 HD |
3842 | if (!PageLRU(page) || !PageUnevictable(page)) |
3843 | continue; | |
89e004ea | 3844 | |
39b5f29a | 3845 | if (page_evictable(page)) { |
24513264 HD |
3846 | enum lru_list lru = page_lru_base_type(page); |
3847 | ||
309381fe | 3848 | VM_BUG_ON_PAGE(PageActive(page), page); |
24513264 | 3849 | ClearPageUnevictable(page); |
fa9add64 HD |
3850 | del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); |
3851 | add_page_to_lru_list(page, lruvec, lru); | |
24513264 | 3852 | pgrescued++; |
89e004ea | 3853 | } |
24513264 | 3854 | } |
89e004ea | 3855 | |
785b99fe | 3856 | if (pgdat) { |
24513264 HD |
3857 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); |
3858 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
785b99fe | 3859 | spin_unlock_irq(&pgdat->lru_lock); |
89e004ea | 3860 | } |
89e004ea | 3861 | } |
85046579 | 3862 | #endif /* CONFIG_SHMEM */ |