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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
b1de0d13 MH |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | ||
1da177e4 LT |
16 | #include <linux/mm.h> |
17 | #include <linux/module.h> | |
5a0e3ad6 | 18 | #include <linux/gfp.h> |
1da177e4 LT |
19 | #include <linux/kernel_stat.h> |
20 | #include <linux/swap.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/highmem.h> | |
70ddf637 | 24 | #include <linux/vmpressure.h> |
e129b5c2 | 25 | #include <linux/vmstat.h> |
1da177e4 LT |
26 | #include <linux/file.h> |
27 | #include <linux/writeback.h> | |
28 | #include <linux/blkdev.h> | |
29 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
30 | buffer_heads_over_limit */ | |
31 | #include <linux/mm_inline.h> | |
1da177e4 LT |
32 | #include <linux/backing-dev.h> |
33 | #include <linux/rmap.h> | |
34 | #include <linux/topology.h> | |
35 | #include <linux/cpu.h> | |
36 | #include <linux/cpuset.h> | |
3e7d3449 | 37 | #include <linux/compaction.h> |
1da177e4 LT |
38 | #include <linux/notifier.h> |
39 | #include <linux/rwsem.h> | |
248a0301 | 40 | #include <linux/delay.h> |
3218ae14 | 41 | #include <linux/kthread.h> |
7dfb7103 | 42 | #include <linux/freezer.h> |
66e1707b | 43 | #include <linux/memcontrol.h> |
873b4771 | 44 | #include <linux/delayacct.h> |
af936a16 | 45 | #include <linux/sysctl.h> |
929bea7c | 46 | #include <linux/oom.h> |
268bb0ce | 47 | #include <linux/prefetch.h> |
b1de0d13 | 48 | #include <linux/printk.h> |
1da177e4 LT |
49 | |
50 | #include <asm/tlbflush.h> | |
51 | #include <asm/div64.h> | |
52 | ||
53 | #include <linux/swapops.h> | |
117aad1e | 54 | #include <linux/balloon_compaction.h> |
1da177e4 | 55 | |
0f8053a5 NP |
56 | #include "internal.h" |
57 | ||
33906bc5 MG |
58 | #define CREATE_TRACE_POINTS |
59 | #include <trace/events/vmscan.h> | |
60 | ||
1da177e4 | 61 | struct scan_control { |
22fba335 KM |
62 | /* How many pages shrink_list() should reclaim */ |
63 | unsigned long nr_to_reclaim; | |
64 | ||
1da177e4 | 65 | /* This context's GFP mask */ |
6daa0e28 | 66 | gfp_t gfp_mask; |
1da177e4 | 67 | |
ee814fe2 | 68 | /* Allocation order */ |
5ad333eb | 69 | int order; |
66e1707b | 70 | |
ee814fe2 JW |
71 | /* |
72 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
73 | * are scanned. | |
74 | */ | |
75 | nodemask_t *nodemask; | |
9e3b2f8c | 76 | |
f16015fb JW |
77 | /* |
78 | * The memory cgroup that hit its limit and as a result is the | |
79 | * primary target of this reclaim invocation. | |
80 | */ | |
81 | struct mem_cgroup *target_mem_cgroup; | |
66e1707b | 82 | |
ee814fe2 JW |
83 | /* Scan (total_size >> priority) pages at once */ |
84 | int priority; | |
85 | ||
86 | unsigned int may_writepage:1; | |
87 | ||
88 | /* Can mapped pages be reclaimed? */ | |
89 | unsigned int may_unmap:1; | |
90 | ||
91 | /* Can pages be swapped as part of reclaim? */ | |
92 | unsigned int may_swap:1; | |
93 | ||
241994ed JW |
94 | /* Can cgroups be reclaimed below their normal consumption range? */ |
95 | unsigned int may_thrash:1; | |
96 | ||
ee814fe2 JW |
97 | unsigned int hibernation_mode:1; |
98 | ||
99 | /* One of the zones is ready for compaction */ | |
100 | unsigned int compaction_ready:1; | |
101 | ||
102 | /* Incremented by the number of inactive pages that were scanned */ | |
103 | unsigned long nr_scanned; | |
104 | ||
105 | /* Number of pages freed so far during a call to shrink_zones() */ | |
106 | unsigned long nr_reclaimed; | |
1da177e4 LT |
107 | }; |
108 | ||
1da177e4 LT |
109 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
110 | ||
111 | #ifdef ARCH_HAS_PREFETCH | |
112 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
113 | do { \ | |
114 | if ((_page)->lru.prev != _base) { \ | |
115 | struct page *prev; \ | |
116 | \ | |
117 | prev = lru_to_page(&(_page->lru)); \ | |
118 | prefetch(&prev->_field); \ | |
119 | } \ | |
120 | } while (0) | |
121 | #else | |
122 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
123 | #endif | |
124 | ||
125 | #ifdef ARCH_HAS_PREFETCHW | |
126 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
127 | do { \ | |
128 | if ((_page)->lru.prev != _base) { \ | |
129 | struct page *prev; \ | |
130 | \ | |
131 | prev = lru_to_page(&(_page->lru)); \ | |
132 | prefetchw(&prev->_field); \ | |
133 | } \ | |
134 | } while (0) | |
135 | #else | |
136 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
137 | #endif | |
138 | ||
139 | /* | |
140 | * From 0 .. 100. Higher means more swappy. | |
141 | */ | |
142 | int vm_swappiness = 60; | |
d0480be4 WSH |
143 | /* |
144 | * The total number of pages which are beyond the high watermark within all | |
145 | * zones. | |
146 | */ | |
147 | unsigned long vm_total_pages; | |
1da177e4 LT |
148 | |
149 | static LIST_HEAD(shrinker_list); | |
150 | static DECLARE_RWSEM(shrinker_rwsem); | |
151 | ||
c255a458 | 152 | #ifdef CONFIG_MEMCG |
89b5fae5 JW |
153 | static bool global_reclaim(struct scan_control *sc) |
154 | { | |
f16015fb | 155 | return !sc->target_mem_cgroup; |
89b5fae5 | 156 | } |
97c9341f TH |
157 | |
158 | /** | |
159 | * sane_reclaim - is the usual dirty throttling mechanism operational? | |
160 | * @sc: scan_control in question | |
161 | * | |
162 | * The normal page dirty throttling mechanism in balance_dirty_pages() is | |
163 | * completely broken with the legacy memcg and direct stalling in | |
164 | * shrink_page_list() is used for throttling instead, which lacks all the | |
165 | * niceties such as fairness, adaptive pausing, bandwidth proportional | |
166 | * allocation and configurability. | |
167 | * | |
168 | * This function tests whether the vmscan currently in progress can assume | |
169 | * that the normal dirty throttling mechanism is operational. | |
170 | */ | |
171 | static bool sane_reclaim(struct scan_control *sc) | |
172 | { | |
173 | struct mem_cgroup *memcg = sc->target_mem_cgroup; | |
174 | ||
175 | if (!memcg) | |
176 | return true; | |
177 | #ifdef CONFIG_CGROUP_WRITEBACK | |
178 | if (cgroup_on_dfl(mem_cgroup_css(memcg)->cgroup)) | |
179 | return true; | |
180 | #endif | |
181 | return false; | |
182 | } | |
91a45470 | 183 | #else |
89b5fae5 JW |
184 | static bool global_reclaim(struct scan_control *sc) |
185 | { | |
186 | return true; | |
187 | } | |
97c9341f TH |
188 | |
189 | static bool sane_reclaim(struct scan_control *sc) | |
190 | { | |
191 | return true; | |
192 | } | |
91a45470 KH |
193 | #endif |
194 | ||
a1c3bfb2 | 195 | static unsigned long zone_reclaimable_pages(struct zone *zone) |
6e543d57 LD |
196 | { |
197 | int nr; | |
198 | ||
199 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
200 | zone_page_state(zone, NR_INACTIVE_FILE); | |
201 | ||
202 | if (get_nr_swap_pages() > 0) | |
203 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
204 | zone_page_state(zone, NR_INACTIVE_ANON); | |
205 | ||
206 | return nr; | |
207 | } | |
208 | ||
209 | bool zone_reclaimable(struct zone *zone) | |
210 | { | |
0d5d823a MG |
211 | return zone_page_state(zone, NR_PAGES_SCANNED) < |
212 | zone_reclaimable_pages(zone) * 6; | |
6e543d57 LD |
213 | } |
214 | ||
4d7dcca2 | 215 | static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru) |
c9f299d9 | 216 | { |
c3c787e8 | 217 | if (!mem_cgroup_disabled()) |
4d7dcca2 | 218 | return mem_cgroup_get_lru_size(lruvec, lru); |
a3d8e054 | 219 | |
074291fe | 220 | return zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru); |
c9f299d9 KM |
221 | } |
222 | ||
1da177e4 | 223 | /* |
1d3d4437 | 224 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 225 | */ |
1d3d4437 | 226 | int register_shrinker(struct shrinker *shrinker) |
1da177e4 | 227 | { |
1d3d4437 GC |
228 | size_t size = sizeof(*shrinker->nr_deferred); |
229 | ||
230 | /* | |
231 | * If we only have one possible node in the system anyway, save | |
232 | * ourselves the trouble and disable NUMA aware behavior. This way we | |
233 | * will save memory and some small loop time later. | |
234 | */ | |
235 | if (nr_node_ids == 1) | |
236 | shrinker->flags &= ~SHRINKER_NUMA_AWARE; | |
237 | ||
238 | if (shrinker->flags & SHRINKER_NUMA_AWARE) | |
239 | size *= nr_node_ids; | |
240 | ||
241 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
242 | if (!shrinker->nr_deferred) | |
243 | return -ENOMEM; | |
244 | ||
8e1f936b RR |
245 | down_write(&shrinker_rwsem); |
246 | list_add_tail(&shrinker->list, &shrinker_list); | |
247 | up_write(&shrinker_rwsem); | |
1d3d4437 | 248 | return 0; |
1da177e4 | 249 | } |
8e1f936b | 250 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
251 | |
252 | /* | |
253 | * Remove one | |
254 | */ | |
8e1f936b | 255 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
256 | { |
257 | down_write(&shrinker_rwsem); | |
258 | list_del(&shrinker->list); | |
259 | up_write(&shrinker_rwsem); | |
ae393321 | 260 | kfree(shrinker->nr_deferred); |
1da177e4 | 261 | } |
8e1f936b | 262 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
263 | |
264 | #define SHRINK_BATCH 128 | |
1d3d4437 | 265 | |
cb731d6c VD |
266 | static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, |
267 | struct shrinker *shrinker, | |
268 | unsigned long nr_scanned, | |
269 | unsigned long nr_eligible) | |
1d3d4437 GC |
270 | { |
271 | unsigned long freed = 0; | |
272 | unsigned long long delta; | |
273 | long total_scan; | |
d5bc5fd3 | 274 | long freeable; |
1d3d4437 GC |
275 | long nr; |
276 | long new_nr; | |
277 | int nid = shrinkctl->nid; | |
278 | long batch_size = shrinker->batch ? shrinker->batch | |
279 | : SHRINK_BATCH; | |
280 | ||
d5bc5fd3 VD |
281 | freeable = shrinker->count_objects(shrinker, shrinkctl); |
282 | if (freeable == 0) | |
1d3d4437 GC |
283 | return 0; |
284 | ||
285 | /* | |
286 | * copy the current shrinker scan count into a local variable | |
287 | * and zero it so that other concurrent shrinker invocations | |
288 | * don't also do this scanning work. | |
289 | */ | |
290 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
291 | ||
292 | total_scan = nr; | |
6b4f7799 | 293 | delta = (4 * nr_scanned) / shrinker->seeks; |
d5bc5fd3 | 294 | delta *= freeable; |
6b4f7799 | 295 | do_div(delta, nr_eligible + 1); |
1d3d4437 GC |
296 | total_scan += delta; |
297 | if (total_scan < 0) { | |
8612c663 | 298 | pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", |
a0b02131 | 299 | shrinker->scan_objects, total_scan); |
d5bc5fd3 | 300 | total_scan = freeable; |
1d3d4437 GC |
301 | } |
302 | ||
303 | /* | |
304 | * We need to avoid excessive windup on filesystem shrinkers | |
305 | * due to large numbers of GFP_NOFS allocations causing the | |
306 | * shrinkers to return -1 all the time. This results in a large | |
307 | * nr being built up so when a shrink that can do some work | |
308 | * comes along it empties the entire cache due to nr >>> | |
d5bc5fd3 | 309 | * freeable. This is bad for sustaining a working set in |
1d3d4437 GC |
310 | * memory. |
311 | * | |
312 | * Hence only allow the shrinker to scan the entire cache when | |
313 | * a large delta change is calculated directly. | |
314 | */ | |
d5bc5fd3 VD |
315 | if (delta < freeable / 4) |
316 | total_scan = min(total_scan, freeable / 2); | |
1d3d4437 GC |
317 | |
318 | /* | |
319 | * Avoid risking looping forever due to too large nr value: | |
320 | * never try to free more than twice the estimate number of | |
321 | * freeable entries. | |
322 | */ | |
d5bc5fd3 VD |
323 | if (total_scan > freeable * 2) |
324 | total_scan = freeable * 2; | |
1d3d4437 GC |
325 | |
326 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
6b4f7799 JW |
327 | nr_scanned, nr_eligible, |
328 | freeable, delta, total_scan); | |
1d3d4437 | 329 | |
0b1fb40a VD |
330 | /* |
331 | * Normally, we should not scan less than batch_size objects in one | |
332 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
333 | * than batch_size objects in total and we are really tight on memory, | |
334 | * we will try to reclaim all available objects, otherwise we can end | |
335 | * up failing allocations although there are plenty of reclaimable | |
336 | * objects spread over several slabs with usage less than the | |
337 | * batch_size. | |
338 | * | |
339 | * We detect the "tight on memory" situations by looking at the total | |
340 | * number of objects we want to scan (total_scan). If it is greater | |
d5bc5fd3 | 341 | * than the total number of objects on slab (freeable), we must be |
0b1fb40a VD |
342 | * scanning at high prio and therefore should try to reclaim as much as |
343 | * possible. | |
344 | */ | |
345 | while (total_scan >= batch_size || | |
d5bc5fd3 | 346 | total_scan >= freeable) { |
a0b02131 | 347 | unsigned long ret; |
0b1fb40a | 348 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 349 | |
0b1fb40a | 350 | shrinkctl->nr_to_scan = nr_to_scan; |
a0b02131 DC |
351 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
352 | if (ret == SHRINK_STOP) | |
353 | break; | |
354 | freed += ret; | |
1d3d4437 | 355 | |
0b1fb40a VD |
356 | count_vm_events(SLABS_SCANNED, nr_to_scan); |
357 | total_scan -= nr_to_scan; | |
1d3d4437 GC |
358 | |
359 | cond_resched(); | |
360 | } | |
361 | ||
362 | /* | |
363 | * move the unused scan count back into the shrinker in a | |
364 | * manner that handles concurrent updates. If we exhausted the | |
365 | * scan, there is no need to do an update. | |
366 | */ | |
367 | if (total_scan > 0) | |
368 | new_nr = atomic_long_add_return(total_scan, | |
369 | &shrinker->nr_deferred[nid]); | |
370 | else | |
371 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
372 | ||
df9024a8 | 373 | trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); |
1d3d4437 | 374 | return freed; |
1495f230 YH |
375 | } |
376 | ||
6b4f7799 | 377 | /** |
cb731d6c | 378 | * shrink_slab - shrink slab caches |
6b4f7799 JW |
379 | * @gfp_mask: allocation context |
380 | * @nid: node whose slab caches to target | |
cb731d6c | 381 | * @memcg: memory cgroup whose slab caches to target |
6b4f7799 JW |
382 | * @nr_scanned: pressure numerator |
383 | * @nr_eligible: pressure denominator | |
1da177e4 | 384 | * |
6b4f7799 | 385 | * Call the shrink functions to age shrinkable caches. |
1da177e4 | 386 | * |
6b4f7799 JW |
387 | * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, |
388 | * unaware shrinkers will receive a node id of 0 instead. | |
1da177e4 | 389 | * |
cb731d6c VD |
390 | * @memcg specifies the memory cgroup to target. If it is not NULL, |
391 | * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan | |
392 | * objects from the memory cgroup specified. Otherwise all shrinkers | |
393 | * are called, and memcg aware shrinkers are supposed to scan the | |
394 | * global list then. | |
395 | * | |
6b4f7799 JW |
396 | * @nr_scanned and @nr_eligible form a ratio that indicate how much of |
397 | * the available objects should be scanned. Page reclaim for example | |
398 | * passes the number of pages scanned and the number of pages on the | |
399 | * LRU lists that it considered on @nid, plus a bias in @nr_scanned | |
400 | * when it encountered mapped pages. The ratio is further biased by | |
401 | * the ->seeks setting of the shrink function, which indicates the | |
402 | * cost to recreate an object relative to that of an LRU page. | |
b15e0905 | 403 | * |
6b4f7799 | 404 | * Returns the number of reclaimed slab objects. |
1da177e4 | 405 | */ |
cb731d6c VD |
406 | static unsigned long shrink_slab(gfp_t gfp_mask, int nid, |
407 | struct mem_cgroup *memcg, | |
408 | unsigned long nr_scanned, | |
409 | unsigned long nr_eligible) | |
1da177e4 LT |
410 | { |
411 | struct shrinker *shrinker; | |
24f7c6b9 | 412 | unsigned long freed = 0; |
1da177e4 | 413 | |
cb731d6c VD |
414 | if (memcg && !memcg_kmem_is_active(memcg)) |
415 | return 0; | |
416 | ||
6b4f7799 JW |
417 | if (nr_scanned == 0) |
418 | nr_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 419 | |
f06590bd | 420 | if (!down_read_trylock(&shrinker_rwsem)) { |
24f7c6b9 DC |
421 | /* |
422 | * If we would return 0, our callers would understand that we | |
423 | * have nothing else to shrink and give up trying. By returning | |
424 | * 1 we keep it going and assume we'll be able to shrink next | |
425 | * time. | |
426 | */ | |
427 | freed = 1; | |
f06590bd MK |
428 | goto out; |
429 | } | |
1da177e4 LT |
430 | |
431 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
6b4f7799 JW |
432 | struct shrink_control sc = { |
433 | .gfp_mask = gfp_mask, | |
434 | .nid = nid, | |
cb731d6c | 435 | .memcg = memcg, |
6b4f7799 | 436 | }; |
ec97097b | 437 | |
cb731d6c VD |
438 | if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE)) |
439 | continue; | |
440 | ||
6b4f7799 JW |
441 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) |
442 | sc.nid = 0; | |
1da177e4 | 443 | |
cb731d6c | 444 | freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible); |
1da177e4 | 445 | } |
6b4f7799 | 446 | |
1da177e4 | 447 | up_read(&shrinker_rwsem); |
f06590bd MK |
448 | out: |
449 | cond_resched(); | |
24f7c6b9 | 450 | return freed; |
1da177e4 LT |
451 | } |
452 | ||
cb731d6c VD |
453 | void drop_slab_node(int nid) |
454 | { | |
455 | unsigned long freed; | |
456 | ||
457 | do { | |
458 | struct mem_cgroup *memcg = NULL; | |
459 | ||
460 | freed = 0; | |
461 | do { | |
462 | freed += shrink_slab(GFP_KERNEL, nid, memcg, | |
463 | 1000, 1000); | |
464 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); | |
465 | } while (freed > 10); | |
466 | } | |
467 | ||
468 | void drop_slab(void) | |
469 | { | |
470 | int nid; | |
471 | ||
472 | for_each_online_node(nid) | |
473 | drop_slab_node(nid); | |
474 | } | |
475 | ||
1da177e4 LT |
476 | static inline int is_page_cache_freeable(struct page *page) |
477 | { | |
ceddc3a5 JW |
478 | /* |
479 | * A freeable page cache page is referenced only by the caller | |
480 | * that isolated the page, the page cache radix tree and | |
481 | * optional buffer heads at page->private. | |
482 | */ | |
edcf4748 | 483 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
484 | } |
485 | ||
703c2708 | 486 | static int may_write_to_inode(struct inode *inode, struct scan_control *sc) |
1da177e4 | 487 | { |
930d9152 | 488 | if (current->flags & PF_SWAPWRITE) |
1da177e4 | 489 | return 1; |
703c2708 | 490 | if (!inode_write_congested(inode)) |
1da177e4 | 491 | return 1; |
703c2708 | 492 | if (inode_to_bdi(inode) == current->backing_dev_info) |
1da177e4 LT |
493 | return 1; |
494 | return 0; | |
495 | } | |
496 | ||
497 | /* | |
498 | * We detected a synchronous write error writing a page out. Probably | |
499 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
500 | * fsync(), msync() or close(). | |
501 | * | |
502 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
503 | * prevents it from being freed up. But we have a ref on the page and once | |
504 | * that page is locked, the mapping is pinned. | |
505 | * | |
506 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
507 | * __GFP_FS. | |
508 | */ | |
509 | static void handle_write_error(struct address_space *mapping, | |
510 | struct page *page, int error) | |
511 | { | |
7eaceacc | 512 | lock_page(page); |
3e9f45bd GC |
513 | if (page_mapping(page) == mapping) |
514 | mapping_set_error(mapping, error); | |
1da177e4 LT |
515 | unlock_page(page); |
516 | } | |
517 | ||
04e62a29 CL |
518 | /* possible outcome of pageout() */ |
519 | typedef enum { | |
520 | /* failed to write page out, page is locked */ | |
521 | PAGE_KEEP, | |
522 | /* move page to the active list, page is locked */ | |
523 | PAGE_ACTIVATE, | |
524 | /* page has been sent to the disk successfully, page is unlocked */ | |
525 | PAGE_SUCCESS, | |
526 | /* page is clean and locked */ | |
527 | PAGE_CLEAN, | |
528 | } pageout_t; | |
529 | ||
1da177e4 | 530 | /* |
1742f19f AM |
531 | * pageout is called by shrink_page_list() for each dirty page. |
532 | * Calls ->writepage(). | |
1da177e4 | 533 | */ |
c661b078 | 534 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 535 | struct scan_control *sc) |
1da177e4 LT |
536 | { |
537 | /* | |
538 | * If the page is dirty, only perform writeback if that write | |
539 | * will be non-blocking. To prevent this allocation from being | |
540 | * stalled by pagecache activity. But note that there may be | |
541 | * stalls if we need to run get_block(). We could test | |
542 | * PagePrivate for that. | |
543 | * | |
8174202b | 544 | * If this process is currently in __generic_file_write_iter() against |
1da177e4 LT |
545 | * this page's queue, we can perform writeback even if that |
546 | * will block. | |
547 | * | |
548 | * If the page is swapcache, write it back even if that would | |
549 | * block, for some throttling. This happens by accident, because | |
550 | * swap_backing_dev_info is bust: it doesn't reflect the | |
551 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
552 | */ |
553 | if (!is_page_cache_freeable(page)) | |
554 | return PAGE_KEEP; | |
555 | if (!mapping) { | |
556 | /* | |
557 | * Some data journaling orphaned pages can have | |
558 | * page->mapping == NULL while being dirty with clean buffers. | |
559 | */ | |
266cf658 | 560 | if (page_has_private(page)) { |
1da177e4 LT |
561 | if (try_to_free_buffers(page)) { |
562 | ClearPageDirty(page); | |
b1de0d13 | 563 | pr_info("%s: orphaned page\n", __func__); |
1da177e4 LT |
564 | return PAGE_CLEAN; |
565 | } | |
566 | } | |
567 | return PAGE_KEEP; | |
568 | } | |
569 | if (mapping->a_ops->writepage == NULL) | |
570 | return PAGE_ACTIVATE; | |
703c2708 | 571 | if (!may_write_to_inode(mapping->host, sc)) |
1da177e4 LT |
572 | return PAGE_KEEP; |
573 | ||
574 | if (clear_page_dirty_for_io(page)) { | |
575 | int res; | |
576 | struct writeback_control wbc = { | |
577 | .sync_mode = WB_SYNC_NONE, | |
578 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
579 | .range_start = 0, |
580 | .range_end = LLONG_MAX, | |
1da177e4 LT |
581 | .for_reclaim = 1, |
582 | }; | |
583 | ||
584 | SetPageReclaim(page); | |
585 | res = mapping->a_ops->writepage(page, &wbc); | |
586 | if (res < 0) | |
587 | handle_write_error(mapping, page, res); | |
994fc28c | 588 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
589 | ClearPageReclaim(page); |
590 | return PAGE_ACTIVATE; | |
591 | } | |
c661b078 | 592 | |
1da177e4 LT |
593 | if (!PageWriteback(page)) { |
594 | /* synchronous write or broken a_ops? */ | |
595 | ClearPageReclaim(page); | |
596 | } | |
23b9da55 | 597 | trace_mm_vmscan_writepage(page, trace_reclaim_flags(page)); |
e129b5c2 | 598 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
599 | return PAGE_SUCCESS; |
600 | } | |
601 | ||
602 | return PAGE_CLEAN; | |
603 | } | |
604 | ||
a649fd92 | 605 | /* |
e286781d NP |
606 | * Same as remove_mapping, but if the page is removed from the mapping, it |
607 | * gets returned with a refcount of 0. | |
a649fd92 | 608 | */ |
a528910e JW |
609 | static int __remove_mapping(struct address_space *mapping, struct page *page, |
610 | bool reclaimed) | |
49d2e9cc | 611 | { |
c4843a75 GT |
612 | unsigned long flags; |
613 | struct mem_cgroup *memcg; | |
614 | ||
28e4d965 NP |
615 | BUG_ON(!PageLocked(page)); |
616 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 617 | |
c4843a75 GT |
618 | memcg = mem_cgroup_begin_page_stat(page); |
619 | spin_lock_irqsave(&mapping->tree_lock, flags); | |
49d2e9cc | 620 | /* |
0fd0e6b0 NP |
621 | * The non racy check for a busy page. |
622 | * | |
623 | * Must be careful with the order of the tests. When someone has | |
624 | * a ref to the page, it may be possible that they dirty it then | |
625 | * drop the reference. So if PageDirty is tested before page_count | |
626 | * here, then the following race may occur: | |
627 | * | |
628 | * get_user_pages(&page); | |
629 | * [user mapping goes away] | |
630 | * write_to(page); | |
631 | * !PageDirty(page) [good] | |
632 | * SetPageDirty(page); | |
633 | * put_page(page); | |
634 | * !page_count(page) [good, discard it] | |
635 | * | |
636 | * [oops, our write_to data is lost] | |
637 | * | |
638 | * Reversing the order of the tests ensures such a situation cannot | |
639 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
640 | * load is not satisfied before that of page->_count. | |
641 | * | |
642 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
643 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 644 | */ |
e286781d | 645 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 646 | goto cannot_free; |
e286781d NP |
647 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
648 | if (unlikely(PageDirty(page))) { | |
649 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 650 | goto cannot_free; |
e286781d | 651 | } |
49d2e9cc CL |
652 | |
653 | if (PageSwapCache(page)) { | |
654 | swp_entry_t swap = { .val = page_private(page) }; | |
0a31bc97 | 655 | mem_cgroup_swapout(page, swap); |
49d2e9cc | 656 | __delete_from_swap_cache(page); |
c4843a75 GT |
657 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
658 | mem_cgroup_end_page_stat(memcg); | |
0a31bc97 | 659 | swapcache_free(swap); |
e286781d | 660 | } else { |
6072d13c | 661 | void (*freepage)(struct page *); |
a528910e | 662 | void *shadow = NULL; |
6072d13c LT |
663 | |
664 | freepage = mapping->a_ops->freepage; | |
a528910e JW |
665 | /* |
666 | * Remember a shadow entry for reclaimed file cache in | |
667 | * order to detect refaults, thus thrashing, later on. | |
668 | * | |
669 | * But don't store shadows in an address space that is | |
670 | * already exiting. This is not just an optizimation, | |
671 | * inode reclaim needs to empty out the radix tree or | |
672 | * the nodes are lost. Don't plant shadows behind its | |
673 | * back. | |
674 | */ | |
675 | if (reclaimed && page_is_file_cache(page) && | |
676 | !mapping_exiting(mapping)) | |
677 | shadow = workingset_eviction(mapping, page); | |
c4843a75 GT |
678 | __delete_from_page_cache(page, shadow, memcg); |
679 | spin_unlock_irqrestore(&mapping->tree_lock, flags); | |
680 | mem_cgroup_end_page_stat(memcg); | |
6072d13c LT |
681 | |
682 | if (freepage != NULL) | |
683 | freepage(page); | |
49d2e9cc CL |
684 | } |
685 | ||
49d2e9cc CL |
686 | return 1; |
687 | ||
688 | cannot_free: | |
c4843a75 GT |
689 | spin_unlock_irqrestore(&mapping->tree_lock, flags); |
690 | mem_cgroup_end_page_stat(memcg); | |
49d2e9cc CL |
691 | return 0; |
692 | } | |
693 | ||
e286781d NP |
694 | /* |
695 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
696 | * someone else has a ref on the page, abort and return 0. If it was | |
697 | * successfully detached, return 1. Assumes the caller has a single ref on | |
698 | * this page. | |
699 | */ | |
700 | int remove_mapping(struct address_space *mapping, struct page *page) | |
701 | { | |
a528910e | 702 | if (__remove_mapping(mapping, page, false)) { |
e286781d NP |
703 | /* |
704 | * Unfreezing the refcount with 1 rather than 2 effectively | |
705 | * drops the pagecache ref for us without requiring another | |
706 | * atomic operation. | |
707 | */ | |
708 | page_unfreeze_refs(page, 1); | |
709 | return 1; | |
710 | } | |
711 | return 0; | |
712 | } | |
713 | ||
894bc310 LS |
714 | /** |
715 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
716 | * @page: page to be put back to appropriate lru list | |
717 | * | |
718 | * Add previously isolated @page to appropriate LRU list. | |
719 | * Page may still be unevictable for other reasons. | |
720 | * | |
721 | * lru_lock must not be held, interrupts must be enabled. | |
722 | */ | |
894bc310 LS |
723 | void putback_lru_page(struct page *page) |
724 | { | |
0ec3b74c | 725 | bool is_unevictable; |
bbfd28ee | 726 | int was_unevictable = PageUnevictable(page); |
894bc310 | 727 | |
309381fe | 728 | VM_BUG_ON_PAGE(PageLRU(page), page); |
894bc310 LS |
729 | |
730 | redo: | |
731 | ClearPageUnevictable(page); | |
732 | ||
39b5f29a | 733 | if (page_evictable(page)) { |
894bc310 LS |
734 | /* |
735 | * For evictable pages, we can use the cache. | |
736 | * In event of a race, worst case is we end up with an | |
737 | * unevictable page on [in]active list. | |
738 | * We know how to handle that. | |
739 | */ | |
0ec3b74c | 740 | is_unevictable = false; |
c53954a0 | 741 | lru_cache_add(page); |
894bc310 LS |
742 | } else { |
743 | /* | |
744 | * Put unevictable pages directly on zone's unevictable | |
745 | * list. | |
746 | */ | |
0ec3b74c | 747 | is_unevictable = true; |
894bc310 | 748 | add_page_to_unevictable_list(page); |
6a7b9548 | 749 | /* |
21ee9f39 MK |
750 | * When racing with an mlock or AS_UNEVICTABLE clearing |
751 | * (page is unlocked) make sure that if the other thread | |
752 | * does not observe our setting of PG_lru and fails | |
24513264 | 753 | * isolation/check_move_unevictable_pages, |
21ee9f39 | 754 | * we see PG_mlocked/AS_UNEVICTABLE cleared below and move |
6a7b9548 JW |
755 | * the page back to the evictable list. |
756 | * | |
21ee9f39 | 757 | * The other side is TestClearPageMlocked() or shmem_lock(). |
6a7b9548 JW |
758 | */ |
759 | smp_mb(); | |
894bc310 | 760 | } |
894bc310 LS |
761 | |
762 | /* | |
763 | * page's status can change while we move it among lru. If an evictable | |
764 | * page is on unevictable list, it never be freed. To avoid that, | |
765 | * check after we added it to the list, again. | |
766 | */ | |
0ec3b74c | 767 | if (is_unevictable && page_evictable(page)) { |
894bc310 LS |
768 | if (!isolate_lru_page(page)) { |
769 | put_page(page); | |
770 | goto redo; | |
771 | } | |
772 | /* This means someone else dropped this page from LRU | |
773 | * So, it will be freed or putback to LRU again. There is | |
774 | * nothing to do here. | |
775 | */ | |
776 | } | |
777 | ||
0ec3b74c | 778 | if (was_unevictable && !is_unevictable) |
bbfd28ee | 779 | count_vm_event(UNEVICTABLE_PGRESCUED); |
0ec3b74c | 780 | else if (!was_unevictable && is_unevictable) |
bbfd28ee LS |
781 | count_vm_event(UNEVICTABLE_PGCULLED); |
782 | ||
894bc310 LS |
783 | put_page(page); /* drop ref from isolate */ |
784 | } | |
785 | ||
dfc8d636 JW |
786 | enum page_references { |
787 | PAGEREF_RECLAIM, | |
788 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 789 | PAGEREF_KEEP, |
dfc8d636 JW |
790 | PAGEREF_ACTIVATE, |
791 | }; | |
792 | ||
793 | static enum page_references page_check_references(struct page *page, | |
794 | struct scan_control *sc) | |
795 | { | |
64574746 | 796 | int referenced_ptes, referenced_page; |
dfc8d636 | 797 | unsigned long vm_flags; |
dfc8d636 | 798 | |
c3ac9a8a JW |
799 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
800 | &vm_flags); | |
64574746 | 801 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 802 | |
dfc8d636 JW |
803 | /* |
804 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
805 | * move the page to the unevictable list. | |
806 | */ | |
807 | if (vm_flags & VM_LOCKED) | |
808 | return PAGEREF_RECLAIM; | |
809 | ||
64574746 | 810 | if (referenced_ptes) { |
e4898273 | 811 | if (PageSwapBacked(page)) |
64574746 JW |
812 | return PAGEREF_ACTIVATE; |
813 | /* | |
814 | * All mapped pages start out with page table | |
815 | * references from the instantiating fault, so we need | |
816 | * to look twice if a mapped file page is used more | |
817 | * than once. | |
818 | * | |
819 | * Mark it and spare it for another trip around the | |
820 | * inactive list. Another page table reference will | |
821 | * lead to its activation. | |
822 | * | |
823 | * Note: the mark is set for activated pages as well | |
824 | * so that recently deactivated but used pages are | |
825 | * quickly recovered. | |
826 | */ | |
827 | SetPageReferenced(page); | |
828 | ||
34dbc67a | 829 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
830 | return PAGEREF_ACTIVATE; |
831 | ||
c909e993 KK |
832 | /* |
833 | * Activate file-backed executable pages after first usage. | |
834 | */ | |
835 | if (vm_flags & VM_EXEC) | |
836 | return PAGEREF_ACTIVATE; | |
837 | ||
64574746 JW |
838 | return PAGEREF_KEEP; |
839 | } | |
dfc8d636 JW |
840 | |
841 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 842 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
843 | return PAGEREF_RECLAIM_CLEAN; |
844 | ||
845 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
846 | } |
847 | ||
e2be15f6 MG |
848 | /* Check if a page is dirty or under writeback */ |
849 | static void page_check_dirty_writeback(struct page *page, | |
850 | bool *dirty, bool *writeback) | |
851 | { | |
b4597226 MG |
852 | struct address_space *mapping; |
853 | ||
e2be15f6 MG |
854 | /* |
855 | * Anonymous pages are not handled by flushers and must be written | |
856 | * from reclaim context. Do not stall reclaim based on them | |
857 | */ | |
858 | if (!page_is_file_cache(page)) { | |
859 | *dirty = false; | |
860 | *writeback = false; | |
861 | return; | |
862 | } | |
863 | ||
864 | /* By default assume that the page flags are accurate */ | |
865 | *dirty = PageDirty(page); | |
866 | *writeback = PageWriteback(page); | |
b4597226 MG |
867 | |
868 | /* Verify dirty/writeback state if the filesystem supports it */ | |
869 | if (!page_has_private(page)) | |
870 | return; | |
871 | ||
872 | mapping = page_mapping(page); | |
873 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
874 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
875 | } |
876 | ||
1da177e4 | 877 | /* |
1742f19f | 878 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 879 | */ |
1742f19f | 880 | static unsigned long shrink_page_list(struct list_head *page_list, |
6a18adb3 | 881 | struct zone *zone, |
f84f6e2b | 882 | struct scan_control *sc, |
02c6de8d | 883 | enum ttu_flags ttu_flags, |
8e950282 | 884 | unsigned long *ret_nr_dirty, |
d43006d5 | 885 | unsigned long *ret_nr_unqueued_dirty, |
8e950282 | 886 | unsigned long *ret_nr_congested, |
02c6de8d | 887 | unsigned long *ret_nr_writeback, |
b1a6f21e | 888 | unsigned long *ret_nr_immediate, |
02c6de8d | 889 | bool force_reclaim) |
1da177e4 LT |
890 | { |
891 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 892 | LIST_HEAD(free_pages); |
1da177e4 | 893 | int pgactivate = 0; |
d43006d5 | 894 | unsigned long nr_unqueued_dirty = 0; |
0e093d99 MG |
895 | unsigned long nr_dirty = 0; |
896 | unsigned long nr_congested = 0; | |
05ff5137 | 897 | unsigned long nr_reclaimed = 0; |
92df3a72 | 898 | unsigned long nr_writeback = 0; |
b1a6f21e | 899 | unsigned long nr_immediate = 0; |
1da177e4 LT |
900 | |
901 | cond_resched(); | |
902 | ||
1da177e4 LT |
903 | while (!list_empty(page_list)) { |
904 | struct address_space *mapping; | |
905 | struct page *page; | |
906 | int may_enter_fs; | |
02c6de8d | 907 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 908 | bool dirty, writeback; |
1da177e4 LT |
909 | |
910 | cond_resched(); | |
911 | ||
912 | page = lru_to_page(page_list); | |
913 | list_del(&page->lru); | |
914 | ||
529ae9aa | 915 | if (!trylock_page(page)) |
1da177e4 LT |
916 | goto keep; |
917 | ||
309381fe SL |
918 | VM_BUG_ON_PAGE(PageActive(page), page); |
919 | VM_BUG_ON_PAGE(page_zone(page) != zone, page); | |
1da177e4 LT |
920 | |
921 | sc->nr_scanned++; | |
80e43426 | 922 | |
39b5f29a | 923 | if (unlikely(!page_evictable(page))) |
b291f000 | 924 | goto cull_mlocked; |
894bc310 | 925 | |
a6dc60f8 | 926 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
927 | goto keep_locked; |
928 | ||
1da177e4 LT |
929 | /* Double the slab pressure for mapped and swapcache pages */ |
930 | if (page_mapped(page) || PageSwapCache(page)) | |
931 | sc->nr_scanned++; | |
932 | ||
c661b078 AW |
933 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
934 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
935 | ||
e2be15f6 MG |
936 | /* |
937 | * The number of dirty pages determines if a zone is marked | |
938 | * reclaim_congested which affects wait_iff_congested. kswapd | |
939 | * will stall and start writing pages if the tail of the LRU | |
940 | * is all dirty unqueued pages. | |
941 | */ | |
942 | page_check_dirty_writeback(page, &dirty, &writeback); | |
943 | if (dirty || writeback) | |
944 | nr_dirty++; | |
945 | ||
946 | if (dirty && !writeback) | |
947 | nr_unqueued_dirty++; | |
948 | ||
d04e8acd MG |
949 | /* |
950 | * Treat this page as congested if the underlying BDI is or if | |
951 | * pages are cycling through the LRU so quickly that the | |
952 | * pages marked for immediate reclaim are making it to the | |
953 | * end of the LRU a second time. | |
954 | */ | |
e2be15f6 | 955 | mapping = page_mapping(page); |
1da58ee2 | 956 | if (((dirty || writeback) && mapping && |
703c2708 | 957 | inode_write_congested(mapping->host)) || |
d04e8acd | 958 | (writeback && PageReclaim(page))) |
e2be15f6 MG |
959 | nr_congested++; |
960 | ||
283aba9f MG |
961 | /* |
962 | * If a page at the tail of the LRU is under writeback, there | |
963 | * are three cases to consider. | |
964 | * | |
965 | * 1) If reclaim is encountering an excessive number of pages | |
966 | * under writeback and this page is both under writeback and | |
967 | * PageReclaim then it indicates that pages are being queued | |
968 | * for IO but are being recycled through the LRU before the | |
969 | * IO can complete. Waiting on the page itself risks an | |
970 | * indefinite stall if it is impossible to writeback the | |
971 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
972 | * note that the LRU is being scanned too quickly and the |
973 | * caller can stall after page list has been processed. | |
283aba9f | 974 | * |
97c9341f | 975 | * 2) Global or new memcg reclaim encounters a page that is |
ecf5fc6e MH |
976 | * not marked for immediate reclaim, or the caller does not |
977 | * have __GFP_FS (or __GFP_IO if it's simply going to swap, | |
978 | * not to fs). In this case mark the page for immediate | |
97c9341f | 979 | * reclaim and continue scanning. |
283aba9f | 980 | * |
ecf5fc6e MH |
981 | * Require may_enter_fs because we would wait on fs, which |
982 | * may not have submitted IO yet. And the loop driver might | |
283aba9f MG |
983 | * enter reclaim, and deadlock if it waits on a page for |
984 | * which it is needed to do the write (loop masks off | |
985 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
986 | * would probably show more reasons. | |
987 | * | |
97c9341f | 988 | * 3) Legacy memcg encounters a page that is not already marked |
283aba9f MG |
989 | * PageReclaim. memcg does not have any dirty pages |
990 | * throttling so we could easily OOM just because too many | |
991 | * pages are in writeback and there is nothing else to | |
992 | * reclaim. Wait for the writeback to complete. | |
993 | */ | |
c661b078 | 994 | if (PageWriteback(page)) { |
283aba9f MG |
995 | /* Case 1 above */ |
996 | if (current_is_kswapd() && | |
997 | PageReclaim(page) && | |
57054651 | 998 | test_bit(ZONE_WRITEBACK, &zone->flags)) { |
b1a6f21e MG |
999 | nr_immediate++; |
1000 | goto keep_locked; | |
283aba9f MG |
1001 | |
1002 | /* Case 2 above */ | |
97c9341f | 1003 | } else if (sane_reclaim(sc) || |
ecf5fc6e | 1004 | !PageReclaim(page) || !may_enter_fs) { |
c3b94f44 HD |
1005 | /* |
1006 | * This is slightly racy - end_page_writeback() | |
1007 | * might have just cleared PageReclaim, then | |
1008 | * setting PageReclaim here end up interpreted | |
1009 | * as PageReadahead - but that does not matter | |
1010 | * enough to care. What we do want is for this | |
1011 | * page to have PageReclaim set next time memcg | |
1012 | * reclaim reaches the tests above, so it will | |
1013 | * then wait_on_page_writeback() to avoid OOM; | |
1014 | * and it's also appropriate in global reclaim. | |
1015 | */ | |
1016 | SetPageReclaim(page); | |
e62e384e | 1017 | nr_writeback++; |
283aba9f | 1018 | |
c3b94f44 | 1019 | goto keep_locked; |
283aba9f MG |
1020 | |
1021 | /* Case 3 above */ | |
1022 | } else { | |
1023 | wait_on_page_writeback(page); | |
e62e384e | 1024 | } |
c661b078 | 1025 | } |
1da177e4 | 1026 | |
02c6de8d MK |
1027 | if (!force_reclaim) |
1028 | references = page_check_references(page, sc); | |
1029 | ||
dfc8d636 JW |
1030 | switch (references) { |
1031 | case PAGEREF_ACTIVATE: | |
1da177e4 | 1032 | goto activate_locked; |
64574746 JW |
1033 | case PAGEREF_KEEP: |
1034 | goto keep_locked; | |
dfc8d636 JW |
1035 | case PAGEREF_RECLAIM: |
1036 | case PAGEREF_RECLAIM_CLEAN: | |
1037 | ; /* try to reclaim the page below */ | |
1038 | } | |
1da177e4 | 1039 | |
1da177e4 LT |
1040 | /* |
1041 | * Anonymous process memory has backing store? | |
1042 | * Try to allocate it some swap space here. | |
1043 | */ | |
b291f000 | 1044 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
1045 | if (!(sc->gfp_mask & __GFP_IO)) |
1046 | goto keep_locked; | |
5bc7b8ac | 1047 | if (!add_to_swap(page, page_list)) |
1da177e4 | 1048 | goto activate_locked; |
63eb6b93 | 1049 | may_enter_fs = 1; |
1da177e4 | 1050 | |
e2be15f6 MG |
1051 | /* Adding to swap updated mapping */ |
1052 | mapping = page_mapping(page); | |
1053 | } | |
1da177e4 LT |
1054 | |
1055 | /* | |
1056 | * The page is mapped into the page tables of one or more | |
1057 | * processes. Try to unmap it here. | |
1058 | */ | |
1059 | if (page_mapped(page) && mapping) { | |
02c6de8d | 1060 | switch (try_to_unmap(page, ttu_flags)) { |
1da177e4 LT |
1061 | case SWAP_FAIL: |
1062 | goto activate_locked; | |
1063 | case SWAP_AGAIN: | |
1064 | goto keep_locked; | |
b291f000 NP |
1065 | case SWAP_MLOCK: |
1066 | goto cull_mlocked; | |
1da177e4 LT |
1067 | case SWAP_SUCCESS: |
1068 | ; /* try to free the page below */ | |
1069 | } | |
1070 | } | |
1071 | ||
1072 | if (PageDirty(page)) { | |
ee72886d MG |
1073 | /* |
1074 | * Only kswapd can writeback filesystem pages to | |
d43006d5 MG |
1075 | * avoid risk of stack overflow but only writeback |
1076 | * if many dirty pages have been encountered. | |
ee72886d | 1077 | */ |
f84f6e2b | 1078 | if (page_is_file_cache(page) && |
9e3b2f8c | 1079 | (!current_is_kswapd() || |
57054651 | 1080 | !test_bit(ZONE_DIRTY, &zone->flags))) { |
49ea7eb6 MG |
1081 | /* |
1082 | * Immediately reclaim when written back. | |
1083 | * Similar in principal to deactivate_page() | |
1084 | * except we already have the page isolated | |
1085 | * and know it's dirty | |
1086 | */ | |
1087 | inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE); | |
1088 | SetPageReclaim(page); | |
1089 | ||
ee72886d MG |
1090 | goto keep_locked; |
1091 | } | |
1092 | ||
dfc8d636 | 1093 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 1094 | goto keep_locked; |
4dd4b920 | 1095 | if (!may_enter_fs) |
1da177e4 | 1096 | goto keep_locked; |
52a8363e | 1097 | if (!sc->may_writepage) |
1da177e4 LT |
1098 | goto keep_locked; |
1099 | ||
1100 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 1101 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1102 | case PAGE_KEEP: |
1103 | goto keep_locked; | |
1104 | case PAGE_ACTIVATE: | |
1105 | goto activate_locked; | |
1106 | case PAGE_SUCCESS: | |
7d3579e8 | 1107 | if (PageWriteback(page)) |
41ac1999 | 1108 | goto keep; |
7d3579e8 | 1109 | if (PageDirty(page)) |
1da177e4 | 1110 | goto keep; |
7d3579e8 | 1111 | |
1da177e4 LT |
1112 | /* |
1113 | * A synchronous write - probably a ramdisk. Go | |
1114 | * ahead and try to reclaim the page. | |
1115 | */ | |
529ae9aa | 1116 | if (!trylock_page(page)) |
1da177e4 LT |
1117 | goto keep; |
1118 | if (PageDirty(page) || PageWriteback(page)) | |
1119 | goto keep_locked; | |
1120 | mapping = page_mapping(page); | |
1121 | case PAGE_CLEAN: | |
1122 | ; /* try to free the page below */ | |
1123 | } | |
1124 | } | |
1125 | ||
1126 | /* | |
1127 | * If the page has buffers, try to free the buffer mappings | |
1128 | * associated with this page. If we succeed we try to free | |
1129 | * the page as well. | |
1130 | * | |
1131 | * We do this even if the page is PageDirty(). | |
1132 | * try_to_release_page() does not perform I/O, but it is | |
1133 | * possible for a page to have PageDirty set, but it is actually | |
1134 | * clean (all its buffers are clean). This happens if the | |
1135 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1136 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1137 | * try_to_release_page() will discover that cleanness and will |
1138 | * drop the buffers and mark the page clean - it can be freed. | |
1139 | * | |
1140 | * Rarely, pages can have buffers and no ->mapping. These are | |
1141 | * the pages which were not successfully invalidated in | |
1142 | * truncate_complete_page(). We try to drop those buffers here | |
1143 | * and if that worked, and the page is no longer mapped into | |
1144 | * process address space (page_count == 1) it can be freed. | |
1145 | * Otherwise, leave the page on the LRU so it is swappable. | |
1146 | */ | |
266cf658 | 1147 | if (page_has_private(page)) { |
1da177e4 LT |
1148 | if (!try_to_release_page(page, sc->gfp_mask)) |
1149 | goto activate_locked; | |
e286781d NP |
1150 | if (!mapping && page_count(page) == 1) { |
1151 | unlock_page(page); | |
1152 | if (put_page_testzero(page)) | |
1153 | goto free_it; | |
1154 | else { | |
1155 | /* | |
1156 | * rare race with speculative reference. | |
1157 | * the speculative reference will free | |
1158 | * this page shortly, so we may | |
1159 | * increment nr_reclaimed here (and | |
1160 | * leave it off the LRU). | |
1161 | */ | |
1162 | nr_reclaimed++; | |
1163 | continue; | |
1164 | } | |
1165 | } | |
1da177e4 LT |
1166 | } |
1167 | ||
a528910e | 1168 | if (!mapping || !__remove_mapping(mapping, page, true)) |
49d2e9cc | 1169 | goto keep_locked; |
1da177e4 | 1170 | |
a978d6f5 NP |
1171 | /* |
1172 | * At this point, we have no other references and there is | |
1173 | * no way to pick any more up (removed from LRU, removed | |
1174 | * from pagecache). Can use non-atomic bitops now (and | |
1175 | * we obviously don't have to worry about waking up a process | |
1176 | * waiting on the page lock, because there are no references. | |
1177 | */ | |
1178 | __clear_page_locked(page); | |
e286781d | 1179 | free_it: |
05ff5137 | 1180 | nr_reclaimed++; |
abe4c3b5 MG |
1181 | |
1182 | /* | |
1183 | * Is there need to periodically free_page_list? It would | |
1184 | * appear not as the counts should be low | |
1185 | */ | |
1186 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1187 | continue; |
1188 | ||
b291f000 | 1189 | cull_mlocked: |
63d6c5ad HD |
1190 | if (PageSwapCache(page)) |
1191 | try_to_free_swap(page); | |
b291f000 NP |
1192 | unlock_page(page); |
1193 | putback_lru_page(page); | |
1194 | continue; | |
1195 | ||
1da177e4 | 1196 | activate_locked: |
68a22394 RR |
1197 | /* Not a candidate for swapping, so reclaim swap space. */ |
1198 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 1199 | try_to_free_swap(page); |
309381fe | 1200 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1201 | SetPageActive(page); |
1202 | pgactivate++; | |
1203 | keep_locked: | |
1204 | unlock_page(page); | |
1205 | keep: | |
1206 | list_add(&page->lru, &ret_pages); | |
309381fe | 1207 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1208 | } |
abe4c3b5 | 1209 | |
747db954 | 1210 | mem_cgroup_uncharge_list(&free_pages); |
b745bc85 | 1211 | free_hot_cold_page_list(&free_pages, true); |
abe4c3b5 | 1212 | |
1da177e4 | 1213 | list_splice(&ret_pages, page_list); |
f8891e5e | 1214 | count_vm_events(PGACTIVATE, pgactivate); |
0a31bc97 | 1215 | |
8e950282 MG |
1216 | *ret_nr_dirty += nr_dirty; |
1217 | *ret_nr_congested += nr_congested; | |
d43006d5 | 1218 | *ret_nr_unqueued_dirty += nr_unqueued_dirty; |
92df3a72 | 1219 | *ret_nr_writeback += nr_writeback; |
b1a6f21e | 1220 | *ret_nr_immediate += nr_immediate; |
05ff5137 | 1221 | return nr_reclaimed; |
1da177e4 LT |
1222 | } |
1223 | ||
02c6de8d MK |
1224 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1225 | struct list_head *page_list) | |
1226 | { | |
1227 | struct scan_control sc = { | |
1228 | .gfp_mask = GFP_KERNEL, | |
1229 | .priority = DEF_PRIORITY, | |
1230 | .may_unmap = 1, | |
1231 | }; | |
8e950282 | 1232 | unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5; |
02c6de8d MK |
1233 | struct page *page, *next; |
1234 | LIST_HEAD(clean_pages); | |
1235 | ||
1236 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e RA |
1237 | if (page_is_file_cache(page) && !PageDirty(page) && |
1238 | !isolated_balloon_page(page)) { | |
02c6de8d MK |
1239 | ClearPageActive(page); |
1240 | list_move(&page->lru, &clean_pages); | |
1241 | } | |
1242 | } | |
1243 | ||
1244 | ret = shrink_page_list(&clean_pages, zone, &sc, | |
8e950282 MG |
1245 | TTU_UNMAP|TTU_IGNORE_ACCESS, |
1246 | &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true); | |
02c6de8d | 1247 | list_splice(&clean_pages, page_list); |
83da7510 | 1248 | mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret); |
02c6de8d MK |
1249 | return ret; |
1250 | } | |
1251 | ||
5ad333eb AW |
1252 | /* |
1253 | * Attempt to remove the specified page from its LRU. Only take this page | |
1254 | * if it is of the appropriate PageActive status. Pages which are being | |
1255 | * freed elsewhere are also ignored. | |
1256 | * | |
1257 | * page: page to consider | |
1258 | * mode: one of the LRU isolation modes defined above | |
1259 | * | |
1260 | * returns 0 on success, -ve errno on failure. | |
1261 | */ | |
f3fd4a61 | 1262 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1263 | { |
1264 | int ret = -EINVAL; | |
1265 | ||
1266 | /* Only take pages on the LRU. */ | |
1267 | if (!PageLRU(page)) | |
1268 | return ret; | |
1269 | ||
e46a2879 MK |
1270 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1271 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1272 | return ret; |
1273 | ||
5ad333eb | 1274 | ret = -EBUSY; |
08e552c6 | 1275 | |
c8244935 MG |
1276 | /* |
1277 | * To minimise LRU disruption, the caller can indicate that it only | |
1278 | * wants to isolate pages it will be able to operate on without | |
1279 | * blocking - clean pages for the most part. | |
1280 | * | |
1281 | * ISOLATE_CLEAN means that only clean pages should be isolated. This | |
1282 | * is used by reclaim when it is cannot write to backing storage | |
1283 | * | |
1284 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages | |
1285 | * that it is possible to migrate without blocking | |
1286 | */ | |
1287 | if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) { | |
1288 | /* All the caller can do on PageWriteback is block */ | |
1289 | if (PageWriteback(page)) | |
1290 | return ret; | |
1291 | ||
1292 | if (PageDirty(page)) { | |
1293 | struct address_space *mapping; | |
1294 | ||
1295 | /* ISOLATE_CLEAN means only clean pages */ | |
1296 | if (mode & ISOLATE_CLEAN) | |
1297 | return ret; | |
1298 | ||
1299 | /* | |
1300 | * Only pages without mappings or that have a | |
1301 | * ->migratepage callback are possible to migrate | |
1302 | * without blocking | |
1303 | */ | |
1304 | mapping = page_mapping(page); | |
1305 | if (mapping && !mapping->a_ops->migratepage) | |
1306 | return ret; | |
1307 | } | |
1308 | } | |
39deaf85 | 1309 | |
f80c0673 MK |
1310 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1311 | return ret; | |
1312 | ||
5ad333eb AW |
1313 | if (likely(get_page_unless_zero(page))) { |
1314 | /* | |
1315 | * Be careful not to clear PageLRU until after we're | |
1316 | * sure the page is not being freed elsewhere -- the | |
1317 | * page release code relies on it. | |
1318 | */ | |
1319 | ClearPageLRU(page); | |
1320 | ret = 0; | |
1321 | } | |
1322 | ||
1323 | return ret; | |
1324 | } | |
1325 | ||
1da177e4 LT |
1326 | /* |
1327 | * zone->lru_lock is heavily contended. Some of the functions that | |
1328 | * shrink the lists perform better by taking out a batch of pages | |
1329 | * and working on them outside the LRU lock. | |
1330 | * | |
1331 | * For pagecache intensive workloads, this function is the hottest | |
1332 | * spot in the kernel (apart from copy_*_user functions). | |
1333 | * | |
1334 | * Appropriate locks must be held before calling this function. | |
1335 | * | |
1336 | * @nr_to_scan: The number of pages to look through on the list. | |
5dc35979 | 1337 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1338 | * @dst: The temp list to put pages on to. |
f626012d | 1339 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1340 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1341 | * @mode: One of the LRU isolation modes |
3cb99451 | 1342 | * @lru: LRU list id for isolating |
1da177e4 LT |
1343 | * |
1344 | * returns how many pages were moved onto *@dst. | |
1345 | */ | |
69e05944 | 1346 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1347 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1348 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1349 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1350 | { |
75b00af7 | 1351 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1352 | unsigned long nr_taken = 0; |
c9b02d97 | 1353 | unsigned long scan; |
1da177e4 | 1354 | |
c9b02d97 | 1355 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb | 1356 | struct page *page; |
fa9add64 | 1357 | int nr_pages; |
5ad333eb | 1358 | |
1da177e4 LT |
1359 | page = lru_to_page(src); |
1360 | prefetchw_prev_lru_page(page, src, flags); | |
1361 | ||
309381fe | 1362 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1363 | |
f3fd4a61 | 1364 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1365 | case 0: |
fa9add64 HD |
1366 | nr_pages = hpage_nr_pages(page); |
1367 | mem_cgroup_update_lru_size(lruvec, lru, -nr_pages); | |
5ad333eb | 1368 | list_move(&page->lru, dst); |
fa9add64 | 1369 | nr_taken += nr_pages; |
5ad333eb AW |
1370 | break; |
1371 | ||
1372 | case -EBUSY: | |
1373 | /* else it is being freed elsewhere */ | |
1374 | list_move(&page->lru, src); | |
1375 | continue; | |
46453a6e | 1376 | |
5ad333eb AW |
1377 | default: |
1378 | BUG(); | |
1379 | } | |
1da177e4 LT |
1380 | } |
1381 | ||
f626012d | 1382 | *nr_scanned = scan; |
75b00af7 HD |
1383 | trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan, |
1384 | nr_taken, mode, is_file_lru(lru)); | |
1da177e4 LT |
1385 | return nr_taken; |
1386 | } | |
1387 | ||
62695a84 NP |
1388 | /** |
1389 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1390 | * @page: page to isolate from its LRU list | |
1391 | * | |
1392 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1393 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1394 | * | |
1395 | * Returns 0 if the page was removed from an LRU list. | |
1396 | * Returns -EBUSY if the page was not on an LRU list. | |
1397 | * | |
1398 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1399 | * the active list, it will have PageActive set. If it was found on |
1400 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1401 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1402 | * |
1403 | * The vmstat statistic corresponding to the list on which the page was | |
1404 | * found will be decremented. | |
1405 | * | |
1406 | * Restrictions: | |
1407 | * (1) Must be called with an elevated refcount on the page. This is a | |
1408 | * fundamentnal difference from isolate_lru_pages (which is called | |
1409 | * without a stable reference). | |
1410 | * (2) the lru_lock must not be held. | |
1411 | * (3) interrupts must be enabled. | |
1412 | */ | |
1413 | int isolate_lru_page(struct page *page) | |
1414 | { | |
1415 | int ret = -EBUSY; | |
1416 | ||
309381fe | 1417 | VM_BUG_ON_PAGE(!page_count(page), page); |
0c917313 | 1418 | |
62695a84 NP |
1419 | if (PageLRU(page)) { |
1420 | struct zone *zone = page_zone(page); | |
fa9add64 | 1421 | struct lruvec *lruvec; |
62695a84 NP |
1422 | |
1423 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 | 1424 | lruvec = mem_cgroup_page_lruvec(page, zone); |
0c917313 | 1425 | if (PageLRU(page)) { |
894bc310 | 1426 | int lru = page_lru(page); |
0c917313 | 1427 | get_page(page); |
62695a84 | 1428 | ClearPageLRU(page); |
fa9add64 HD |
1429 | del_page_from_lru_list(page, lruvec, lru); |
1430 | ret = 0; | |
62695a84 NP |
1431 | } |
1432 | spin_unlock_irq(&zone->lru_lock); | |
1433 | } | |
1434 | return ret; | |
1435 | } | |
1436 | ||
35cd7815 | 1437 | /* |
d37dd5dc FW |
1438 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1439 | * then get resheduled. When there are massive number of tasks doing page | |
1440 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1441 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1442 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 RR |
1443 | */ |
1444 | static int too_many_isolated(struct zone *zone, int file, | |
1445 | struct scan_control *sc) | |
1446 | { | |
1447 | unsigned long inactive, isolated; | |
1448 | ||
1449 | if (current_is_kswapd()) | |
1450 | return 0; | |
1451 | ||
97c9341f | 1452 | if (!sane_reclaim(sc)) |
35cd7815 RR |
1453 | return 0; |
1454 | ||
1455 | if (file) { | |
1456 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1457 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1458 | } else { | |
1459 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1460 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1461 | } | |
1462 | ||
3cf23841 FW |
1463 | /* |
1464 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1465 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1466 | * deadlock. | |
1467 | */ | |
1468 | if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS) | |
1469 | inactive >>= 3; | |
1470 | ||
35cd7815 RR |
1471 | return isolated > inactive; |
1472 | } | |
1473 | ||
66635629 | 1474 | static noinline_for_stack void |
75b00af7 | 1475 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1476 | { |
27ac81d8 KK |
1477 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1478 | struct zone *zone = lruvec_zone(lruvec); | |
3f79768f | 1479 | LIST_HEAD(pages_to_free); |
66635629 | 1480 | |
66635629 MG |
1481 | /* |
1482 | * Put back any unfreeable pages. | |
1483 | */ | |
66635629 | 1484 | while (!list_empty(page_list)) { |
3f79768f | 1485 | struct page *page = lru_to_page(page_list); |
66635629 | 1486 | int lru; |
3f79768f | 1487 | |
309381fe | 1488 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1489 | list_del(&page->lru); |
39b5f29a | 1490 | if (unlikely(!page_evictable(page))) { |
66635629 MG |
1491 | spin_unlock_irq(&zone->lru_lock); |
1492 | putback_lru_page(page); | |
1493 | spin_lock_irq(&zone->lru_lock); | |
1494 | continue; | |
1495 | } | |
fa9add64 HD |
1496 | |
1497 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
1498 | ||
7a608572 | 1499 | SetPageLRU(page); |
66635629 | 1500 | lru = page_lru(page); |
fa9add64 HD |
1501 | add_page_to_lru_list(page, lruvec, lru); |
1502 | ||
66635629 MG |
1503 | if (is_active_lru(lru)) { |
1504 | int file = is_file_lru(lru); | |
9992af10 RR |
1505 | int numpages = hpage_nr_pages(page); |
1506 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1507 | } |
2bcf8879 HD |
1508 | if (put_page_testzero(page)) { |
1509 | __ClearPageLRU(page); | |
1510 | __ClearPageActive(page); | |
fa9add64 | 1511 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1512 | |
1513 | if (unlikely(PageCompound(page))) { | |
1514 | spin_unlock_irq(&zone->lru_lock); | |
747db954 | 1515 | mem_cgroup_uncharge(page); |
2bcf8879 HD |
1516 | (*get_compound_page_dtor(page))(page); |
1517 | spin_lock_irq(&zone->lru_lock); | |
1518 | } else | |
1519 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1520 | } |
1521 | } | |
66635629 | 1522 | |
3f79768f HD |
1523 | /* |
1524 | * To save our caller's stack, now use input list for pages to free. | |
1525 | */ | |
1526 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1527 | } |
1528 | ||
399ba0b9 N |
1529 | /* |
1530 | * If a kernel thread (such as nfsd for loop-back mounts) services | |
1531 | * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. | |
1532 | * In that case we should only throttle if the backing device it is | |
1533 | * writing to is congested. In other cases it is safe to throttle. | |
1534 | */ | |
1535 | static int current_may_throttle(void) | |
1536 | { | |
1537 | return !(current->flags & PF_LESS_THROTTLE) || | |
1538 | current->backing_dev_info == NULL || | |
1539 | bdi_write_congested(current->backing_dev_info); | |
1540 | } | |
1541 | ||
1da177e4 | 1542 | /* |
1742f19f AM |
1543 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1544 | * of reclaimed pages | |
1da177e4 | 1545 | */ |
66635629 | 1546 | static noinline_for_stack unsigned long |
1a93be0e | 1547 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1548 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1549 | { |
1550 | LIST_HEAD(page_list); | |
e247dbce | 1551 | unsigned long nr_scanned; |
05ff5137 | 1552 | unsigned long nr_reclaimed = 0; |
e247dbce | 1553 | unsigned long nr_taken; |
8e950282 MG |
1554 | unsigned long nr_dirty = 0; |
1555 | unsigned long nr_congested = 0; | |
e2be15f6 | 1556 | unsigned long nr_unqueued_dirty = 0; |
92df3a72 | 1557 | unsigned long nr_writeback = 0; |
b1a6f21e | 1558 | unsigned long nr_immediate = 0; |
f3fd4a61 | 1559 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1560 | int file = is_file_lru(lru); |
1a93be0e KK |
1561 | struct zone *zone = lruvec_zone(lruvec); |
1562 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; | |
78dc583d | 1563 | |
35cd7815 | 1564 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1565 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1566 | |
1567 | /* We are about to die and free our memory. Return now. */ | |
1568 | if (fatal_signal_pending(current)) | |
1569 | return SWAP_CLUSTER_MAX; | |
1570 | } | |
1571 | ||
1da177e4 | 1572 | lru_add_drain(); |
f80c0673 MK |
1573 | |
1574 | if (!sc->may_unmap) | |
61317289 | 1575 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1576 | if (!sc->may_writepage) |
61317289 | 1577 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1578 | |
1da177e4 | 1579 | spin_lock_irq(&zone->lru_lock); |
b35ea17b | 1580 | |
5dc35979 KK |
1581 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1582 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc KK |
1583 | |
1584 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); | |
1585 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); | |
1586 | ||
89b5fae5 | 1587 | if (global_reclaim(sc)) { |
0d5d823a | 1588 | __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned); |
e247dbce | 1589 | if (current_is_kswapd()) |
75b00af7 | 1590 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned); |
e247dbce | 1591 | else |
75b00af7 | 1592 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned); |
e247dbce | 1593 | } |
d563c050 | 1594 | spin_unlock_irq(&zone->lru_lock); |
b35ea17b | 1595 | |
d563c050 | 1596 | if (nr_taken == 0) |
66635629 | 1597 | return 0; |
5ad333eb | 1598 | |
02c6de8d | 1599 | nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP, |
8e950282 MG |
1600 | &nr_dirty, &nr_unqueued_dirty, &nr_congested, |
1601 | &nr_writeback, &nr_immediate, | |
1602 | false); | |
c661b078 | 1603 | |
3f79768f HD |
1604 | spin_lock_irq(&zone->lru_lock); |
1605 | ||
95d918fc | 1606 | reclaim_stat->recent_scanned[file] += nr_taken; |
d563c050 | 1607 | |
904249aa YH |
1608 | if (global_reclaim(sc)) { |
1609 | if (current_is_kswapd()) | |
1610 | __count_zone_vm_events(PGSTEAL_KSWAPD, zone, | |
1611 | nr_reclaimed); | |
1612 | else | |
1613 | __count_zone_vm_events(PGSTEAL_DIRECT, zone, | |
1614 | nr_reclaimed); | |
1615 | } | |
a74609fa | 1616 | |
27ac81d8 | 1617 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1618 | |
95d918fc | 1619 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f HD |
1620 | |
1621 | spin_unlock_irq(&zone->lru_lock); | |
1622 | ||
747db954 | 1623 | mem_cgroup_uncharge_list(&page_list); |
b745bc85 | 1624 | free_hot_cold_page_list(&page_list, true); |
e11da5b4 | 1625 | |
92df3a72 MG |
1626 | /* |
1627 | * If reclaim is isolating dirty pages under writeback, it implies | |
1628 | * that the long-lived page allocation rate is exceeding the page | |
1629 | * laundering rate. Either the global limits are not being effective | |
1630 | * at throttling processes due to the page distribution throughout | |
1631 | * zones or there is heavy usage of a slow backing device. The | |
1632 | * only option is to throttle from reclaim context which is not ideal | |
1633 | * as there is no guarantee the dirtying process is throttled in the | |
1634 | * same way balance_dirty_pages() manages. | |
1635 | * | |
8e950282 MG |
1636 | * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number |
1637 | * of pages under pages flagged for immediate reclaim and stall if any | |
1638 | * are encountered in the nr_immediate check below. | |
92df3a72 | 1639 | */ |
918fc718 | 1640 | if (nr_writeback && nr_writeback == nr_taken) |
57054651 | 1641 | set_bit(ZONE_WRITEBACK, &zone->flags); |
92df3a72 | 1642 | |
d43006d5 | 1643 | /* |
97c9341f TH |
1644 | * Legacy memcg will stall in page writeback so avoid forcibly |
1645 | * stalling here. | |
d43006d5 | 1646 | */ |
97c9341f | 1647 | if (sane_reclaim(sc)) { |
8e950282 MG |
1648 | /* |
1649 | * Tag a zone as congested if all the dirty pages scanned were | |
1650 | * backed by a congested BDI and wait_iff_congested will stall. | |
1651 | */ | |
1652 | if (nr_dirty && nr_dirty == nr_congested) | |
57054651 | 1653 | set_bit(ZONE_CONGESTED, &zone->flags); |
8e950282 | 1654 | |
b1a6f21e MG |
1655 | /* |
1656 | * If dirty pages are scanned that are not queued for IO, it | |
1657 | * implies that flushers are not keeping up. In this case, flag | |
57054651 JW |
1658 | * the zone ZONE_DIRTY and kswapd will start writing pages from |
1659 | * reclaim context. | |
b1a6f21e MG |
1660 | */ |
1661 | if (nr_unqueued_dirty == nr_taken) | |
57054651 | 1662 | set_bit(ZONE_DIRTY, &zone->flags); |
b1a6f21e MG |
1663 | |
1664 | /* | |
b738d764 LT |
1665 | * If kswapd scans pages marked marked for immediate |
1666 | * reclaim and under writeback (nr_immediate), it implies | |
1667 | * that pages are cycling through the LRU faster than | |
b1a6f21e MG |
1668 | * they are written so also forcibly stall. |
1669 | */ | |
b738d764 | 1670 | if (nr_immediate && current_may_throttle()) |
b1a6f21e | 1671 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
e2be15f6 | 1672 | } |
d43006d5 | 1673 | |
8e950282 MG |
1674 | /* |
1675 | * Stall direct reclaim for IO completions if underlying BDIs or zone | |
1676 | * is congested. Allow kswapd to continue until it starts encountering | |
1677 | * unqueued dirty pages or cycling through the LRU too quickly. | |
1678 | */ | |
399ba0b9 N |
1679 | if (!sc->hibernation_mode && !current_is_kswapd() && |
1680 | current_may_throttle()) | |
8e950282 MG |
1681 | wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); |
1682 | ||
e11da5b4 MG |
1683 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, |
1684 | zone_idx(zone), | |
1685 | nr_scanned, nr_reclaimed, | |
9e3b2f8c | 1686 | sc->priority, |
23b9da55 | 1687 | trace_shrink_flags(file)); |
05ff5137 | 1688 | return nr_reclaimed; |
1da177e4 LT |
1689 | } |
1690 | ||
1691 | /* | |
1692 | * This moves pages from the active list to the inactive list. | |
1693 | * | |
1694 | * We move them the other way if the page is referenced by one or more | |
1695 | * processes, from rmap. | |
1696 | * | |
1697 | * If the pages are mostly unmapped, the processing is fast and it is | |
1698 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1699 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1700 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1701 | * this, so instead we remove the pages from the LRU while processing them. | |
1702 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1703 | * nobody will play with that bit on a non-LRU page. | |
1704 | * | |
1705 | * The downside is that we have to touch page->_count against each page. | |
1706 | * But we had to alter page->flags anyway. | |
1707 | */ | |
1cfb419b | 1708 | |
fa9add64 | 1709 | static void move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 1710 | struct list_head *list, |
2bcf8879 | 1711 | struct list_head *pages_to_free, |
3eb4140f WF |
1712 | enum lru_list lru) |
1713 | { | |
fa9add64 | 1714 | struct zone *zone = lruvec_zone(lruvec); |
3eb4140f | 1715 | unsigned long pgmoved = 0; |
3eb4140f | 1716 | struct page *page; |
fa9add64 | 1717 | int nr_pages; |
3eb4140f | 1718 | |
3eb4140f WF |
1719 | while (!list_empty(list)) { |
1720 | page = lru_to_page(list); | |
fa9add64 | 1721 | lruvec = mem_cgroup_page_lruvec(page, zone); |
3eb4140f | 1722 | |
309381fe | 1723 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
1724 | SetPageLRU(page); |
1725 | ||
fa9add64 HD |
1726 | nr_pages = hpage_nr_pages(page); |
1727 | mem_cgroup_update_lru_size(lruvec, lru, nr_pages); | |
925b7673 | 1728 | list_move(&page->lru, &lruvec->lists[lru]); |
fa9add64 | 1729 | pgmoved += nr_pages; |
3eb4140f | 1730 | |
2bcf8879 HD |
1731 | if (put_page_testzero(page)) { |
1732 | __ClearPageLRU(page); | |
1733 | __ClearPageActive(page); | |
fa9add64 | 1734 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1735 | |
1736 | if (unlikely(PageCompound(page))) { | |
1737 | spin_unlock_irq(&zone->lru_lock); | |
747db954 | 1738 | mem_cgroup_uncharge(page); |
2bcf8879 HD |
1739 | (*get_compound_page_dtor(page))(page); |
1740 | spin_lock_irq(&zone->lru_lock); | |
1741 | } else | |
1742 | list_add(&page->lru, pages_to_free); | |
3eb4140f WF |
1743 | } |
1744 | } | |
1745 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1746 | if (!is_active_lru(lru)) | |
1747 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1748 | } | |
1cfb419b | 1749 | |
f626012d | 1750 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 1751 | struct lruvec *lruvec, |
f16015fb | 1752 | struct scan_control *sc, |
9e3b2f8c | 1753 | enum lru_list lru) |
1da177e4 | 1754 | { |
44c241f1 | 1755 | unsigned long nr_taken; |
f626012d | 1756 | unsigned long nr_scanned; |
6fe6b7e3 | 1757 | unsigned long vm_flags; |
1da177e4 | 1758 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1759 | LIST_HEAD(l_active); |
b69408e8 | 1760 | LIST_HEAD(l_inactive); |
1da177e4 | 1761 | struct page *page; |
1a93be0e | 1762 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
44c241f1 | 1763 | unsigned long nr_rotated = 0; |
f3fd4a61 | 1764 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1765 | int file = is_file_lru(lru); |
1a93be0e | 1766 | struct zone *zone = lruvec_zone(lruvec); |
1da177e4 LT |
1767 | |
1768 | lru_add_drain(); | |
f80c0673 MK |
1769 | |
1770 | if (!sc->may_unmap) | |
61317289 | 1771 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1772 | if (!sc->may_writepage) |
61317289 | 1773 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1774 | |
1da177e4 | 1775 | spin_lock_irq(&zone->lru_lock); |
925b7673 | 1776 | |
5dc35979 KK |
1777 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
1778 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 1779 | if (global_reclaim(sc)) |
0d5d823a | 1780 | __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned); |
89b5fae5 | 1781 | |
b7c46d15 | 1782 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1783 | |
f626012d | 1784 | __count_zone_vm_events(PGREFILL, zone, nr_scanned); |
3cb99451 | 1785 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); |
a731286d | 1786 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1787 | spin_unlock_irq(&zone->lru_lock); |
1788 | ||
1da177e4 LT |
1789 | while (!list_empty(&l_hold)) { |
1790 | cond_resched(); | |
1791 | page = lru_to_page(&l_hold); | |
1792 | list_del(&page->lru); | |
7e9cd484 | 1793 | |
39b5f29a | 1794 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
1795 | putback_lru_page(page); |
1796 | continue; | |
1797 | } | |
1798 | ||
cc715d99 MG |
1799 | if (unlikely(buffer_heads_over_limit)) { |
1800 | if (page_has_private(page) && trylock_page(page)) { | |
1801 | if (page_has_private(page)) | |
1802 | try_to_release_page(page, 0); | |
1803 | unlock_page(page); | |
1804 | } | |
1805 | } | |
1806 | ||
c3ac9a8a JW |
1807 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
1808 | &vm_flags)) { | |
9992af10 | 1809 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1810 | /* |
1811 | * Identify referenced, file-backed active pages and | |
1812 | * give them one more trip around the active list. So | |
1813 | * that executable code get better chances to stay in | |
1814 | * memory under moderate memory pressure. Anon pages | |
1815 | * are not likely to be evicted by use-once streaming | |
1816 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1817 | * so we ignore them here. | |
1818 | */ | |
41e20983 | 1819 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1820 | list_add(&page->lru, &l_active); |
1821 | continue; | |
1822 | } | |
1823 | } | |
7e9cd484 | 1824 | |
5205e56e | 1825 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1826 | list_add(&page->lru, &l_inactive); |
1827 | } | |
1828 | ||
b555749a | 1829 | /* |
8cab4754 | 1830 | * Move pages back to the lru list. |
b555749a | 1831 | */ |
2a1dc509 | 1832 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1833 | /* |
8cab4754 WF |
1834 | * Count referenced pages from currently used mappings as rotated, |
1835 | * even though only some of them are actually re-activated. This | |
1836 | * helps balance scan pressure between file and anonymous pages in | |
7c0db9e9 | 1837 | * get_scan_count. |
7e9cd484 | 1838 | */ |
b7c46d15 | 1839 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1840 | |
fa9add64 HD |
1841 | move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
1842 | move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
a731286d | 1843 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1844 | spin_unlock_irq(&zone->lru_lock); |
2bcf8879 | 1845 | |
747db954 | 1846 | mem_cgroup_uncharge_list(&l_hold); |
b745bc85 | 1847 | free_hot_cold_page_list(&l_hold, true); |
1da177e4 LT |
1848 | } |
1849 | ||
74e3f3c3 | 1850 | #ifdef CONFIG_SWAP |
14797e23 | 1851 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1852 | { |
1853 | unsigned long active, inactive; | |
1854 | ||
1855 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1856 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1857 | ||
1858 | if (inactive * zone->inactive_ratio < active) | |
1859 | return 1; | |
1860 | ||
1861 | return 0; | |
1862 | } | |
1863 | ||
14797e23 KM |
1864 | /** |
1865 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
c56d5c7d | 1866 | * @lruvec: LRU vector to check |
14797e23 KM |
1867 | * |
1868 | * Returns true if the zone does not have enough inactive anon pages, | |
1869 | * meaning some active anon pages need to be deactivated. | |
1870 | */ | |
c56d5c7d | 1871 | static int inactive_anon_is_low(struct lruvec *lruvec) |
14797e23 | 1872 | { |
74e3f3c3 MK |
1873 | /* |
1874 | * If we don't have swap space, anonymous page deactivation | |
1875 | * is pointless. | |
1876 | */ | |
1877 | if (!total_swap_pages) | |
1878 | return 0; | |
1879 | ||
c3c787e8 | 1880 | if (!mem_cgroup_disabled()) |
c56d5c7d | 1881 | return mem_cgroup_inactive_anon_is_low(lruvec); |
f16015fb | 1882 | |
c56d5c7d | 1883 | return inactive_anon_is_low_global(lruvec_zone(lruvec)); |
14797e23 | 1884 | } |
74e3f3c3 | 1885 | #else |
c56d5c7d | 1886 | static inline int inactive_anon_is_low(struct lruvec *lruvec) |
74e3f3c3 MK |
1887 | { |
1888 | return 0; | |
1889 | } | |
1890 | #endif | |
14797e23 | 1891 | |
56e49d21 RR |
1892 | /** |
1893 | * inactive_file_is_low - check if file pages need to be deactivated | |
c56d5c7d | 1894 | * @lruvec: LRU vector to check |
56e49d21 RR |
1895 | * |
1896 | * When the system is doing streaming IO, memory pressure here | |
1897 | * ensures that active file pages get deactivated, until more | |
1898 | * than half of the file pages are on the inactive list. | |
1899 | * | |
1900 | * Once we get to that situation, protect the system's working | |
1901 | * set from being evicted by disabling active file page aging. | |
1902 | * | |
1903 | * This uses a different ratio than the anonymous pages, because | |
1904 | * the page cache uses a use-once replacement algorithm. | |
1905 | */ | |
c56d5c7d | 1906 | static int inactive_file_is_low(struct lruvec *lruvec) |
56e49d21 | 1907 | { |
e3790144 JW |
1908 | unsigned long inactive; |
1909 | unsigned long active; | |
1910 | ||
1911 | inactive = get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
1912 | active = get_lru_size(lruvec, LRU_ACTIVE_FILE); | |
56e49d21 | 1913 | |
e3790144 | 1914 | return active > inactive; |
56e49d21 RR |
1915 | } |
1916 | ||
75b00af7 | 1917 | static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru) |
b39415b2 | 1918 | { |
75b00af7 | 1919 | if (is_file_lru(lru)) |
c56d5c7d | 1920 | return inactive_file_is_low(lruvec); |
b39415b2 | 1921 | else |
c56d5c7d | 1922 | return inactive_anon_is_low(lruvec); |
b39415b2 RR |
1923 | } |
1924 | ||
4f98a2fe | 1925 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
1a93be0e | 1926 | struct lruvec *lruvec, struct scan_control *sc) |
b69408e8 | 1927 | { |
b39415b2 | 1928 | if (is_active_lru(lru)) { |
75b00af7 | 1929 | if (inactive_list_is_low(lruvec, lru)) |
1a93be0e | 1930 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
1931 | return 0; |
1932 | } | |
1933 | ||
1a93be0e | 1934 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
1935 | } |
1936 | ||
9a265114 JW |
1937 | enum scan_balance { |
1938 | SCAN_EQUAL, | |
1939 | SCAN_FRACT, | |
1940 | SCAN_ANON, | |
1941 | SCAN_FILE, | |
1942 | }; | |
1943 | ||
4f98a2fe RR |
1944 | /* |
1945 | * Determine how aggressively the anon and file LRU lists should be | |
1946 | * scanned. The relative value of each set of LRU lists is determined | |
1947 | * by looking at the fraction of the pages scanned we did rotate back | |
1948 | * onto the active list instead of evict. | |
1949 | * | |
be7bd59d WL |
1950 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
1951 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 1952 | */ |
02695175 | 1953 | static void get_scan_count(struct lruvec *lruvec, int swappiness, |
6b4f7799 JW |
1954 | struct scan_control *sc, unsigned long *nr, |
1955 | unsigned long *lru_pages) | |
4f98a2fe | 1956 | { |
9a265114 JW |
1957 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1958 | u64 fraction[2]; | |
1959 | u64 denominator = 0; /* gcc */ | |
1960 | struct zone *zone = lruvec_zone(lruvec); | |
4f98a2fe | 1961 | unsigned long anon_prio, file_prio; |
9a265114 | 1962 | enum scan_balance scan_balance; |
0bf1457f | 1963 | unsigned long anon, file; |
9a265114 | 1964 | bool force_scan = false; |
4f98a2fe | 1965 | unsigned long ap, fp; |
4111304d | 1966 | enum lru_list lru; |
6f04f48d SS |
1967 | bool some_scanned; |
1968 | int pass; | |
246e87a9 | 1969 | |
f11c0ca5 JW |
1970 | /* |
1971 | * If the zone or memcg is small, nr[l] can be 0. This | |
1972 | * results in no scanning on this priority and a potential | |
1973 | * priority drop. Global direct reclaim can go to the next | |
1974 | * zone and tends to have no problems. Global kswapd is for | |
1975 | * zone balancing and it needs to scan a minimum amount. When | |
1976 | * reclaiming for a memcg, a priority drop can cause high | |
1977 | * latencies, so it's better to scan a minimum amount there as | |
1978 | * well. | |
1979 | */ | |
90cbc250 VD |
1980 | if (current_is_kswapd()) { |
1981 | if (!zone_reclaimable(zone)) | |
1982 | force_scan = true; | |
1983 | if (!mem_cgroup_lruvec_online(lruvec)) | |
1984 | force_scan = true; | |
1985 | } | |
89b5fae5 | 1986 | if (!global_reclaim(sc)) |
a4d3e9e7 | 1987 | force_scan = true; |
76a33fc3 SL |
1988 | |
1989 | /* If we have no swap space, do not bother scanning anon pages. */ | |
ec8acf20 | 1990 | if (!sc->may_swap || (get_nr_swap_pages() <= 0)) { |
9a265114 | 1991 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
1992 | goto out; |
1993 | } | |
4f98a2fe | 1994 | |
10316b31 JW |
1995 | /* |
1996 | * Global reclaim will swap to prevent OOM even with no | |
1997 | * swappiness, but memcg users want to use this knob to | |
1998 | * disable swapping for individual groups completely when | |
1999 | * using the memory controller's swap limit feature would be | |
2000 | * too expensive. | |
2001 | */ | |
02695175 | 2002 | if (!global_reclaim(sc) && !swappiness) { |
9a265114 | 2003 | scan_balance = SCAN_FILE; |
10316b31 JW |
2004 | goto out; |
2005 | } | |
2006 | ||
2007 | /* | |
2008 | * Do not apply any pressure balancing cleverness when the | |
2009 | * system is close to OOM, scan both anon and file equally | |
2010 | * (unless the swappiness setting disagrees with swapping). | |
2011 | */ | |
02695175 | 2012 | if (!sc->priority && swappiness) { |
9a265114 | 2013 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
2014 | goto out; |
2015 | } | |
2016 | ||
62376251 JW |
2017 | /* |
2018 | * Prevent the reclaimer from falling into the cache trap: as | |
2019 | * cache pages start out inactive, every cache fault will tip | |
2020 | * the scan balance towards the file LRU. And as the file LRU | |
2021 | * shrinks, so does the window for rotation from references. | |
2022 | * This means we have a runaway feedback loop where a tiny | |
2023 | * thrashing file LRU becomes infinitely more attractive than | |
2024 | * anon pages. Try to detect this based on file LRU size. | |
2025 | */ | |
2026 | if (global_reclaim(sc)) { | |
2ab051e1 JM |
2027 | unsigned long zonefile; |
2028 | unsigned long zonefree; | |
2029 | ||
2030 | zonefree = zone_page_state(zone, NR_FREE_PAGES); | |
2031 | zonefile = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2032 | zone_page_state(zone, NR_INACTIVE_FILE); | |
62376251 | 2033 | |
2ab051e1 | 2034 | if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) { |
62376251 JW |
2035 | scan_balance = SCAN_ANON; |
2036 | goto out; | |
2037 | } | |
2038 | } | |
2039 | ||
7c5bd705 JW |
2040 | /* |
2041 | * There is enough inactive page cache, do not reclaim | |
2042 | * anything from the anonymous working set right now. | |
2043 | */ | |
2044 | if (!inactive_file_is_low(lruvec)) { | |
9a265114 | 2045 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
2046 | goto out; |
2047 | } | |
2048 | ||
9a265114 JW |
2049 | scan_balance = SCAN_FRACT; |
2050 | ||
58c37f6e KM |
2051 | /* |
2052 | * With swappiness at 100, anonymous and file have the same priority. | |
2053 | * This scanning priority is essentially the inverse of IO cost. | |
2054 | */ | |
02695175 | 2055 | anon_prio = swappiness; |
75b00af7 | 2056 | file_prio = 200 - anon_prio; |
58c37f6e | 2057 | |
4f98a2fe RR |
2058 | /* |
2059 | * OK, so we have swap space and a fair amount of page cache | |
2060 | * pages. We use the recently rotated / recently scanned | |
2061 | * ratios to determine how valuable each cache is. | |
2062 | * | |
2063 | * Because workloads change over time (and to avoid overflow) | |
2064 | * we keep these statistics as a floating average, which ends | |
2065 | * up weighing recent references more than old ones. | |
2066 | * | |
2067 | * anon in [0], file in [1] | |
2068 | */ | |
2ab051e1 JM |
2069 | |
2070 | anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) + | |
2071 | get_lru_size(lruvec, LRU_INACTIVE_ANON); | |
2072 | file = get_lru_size(lruvec, LRU_ACTIVE_FILE) + | |
2073 | get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
2074 | ||
90126375 | 2075 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 2076 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
2077 | reclaim_stat->recent_scanned[0] /= 2; |
2078 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
2079 | } |
2080 | ||
6e901571 | 2081 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
2082 | reclaim_stat->recent_scanned[1] /= 2; |
2083 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
2084 | } |
2085 | ||
4f98a2fe | 2086 | /* |
00d8089c RR |
2087 | * The amount of pressure on anon vs file pages is inversely |
2088 | * proportional to the fraction of recently scanned pages on | |
2089 | * each list that were recently referenced and in active use. | |
4f98a2fe | 2090 | */ |
fe35004f | 2091 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 2092 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 2093 | |
fe35004f | 2094 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 2095 | fp /= reclaim_stat->recent_rotated[1] + 1; |
90126375 | 2096 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 2097 | |
76a33fc3 SL |
2098 | fraction[0] = ap; |
2099 | fraction[1] = fp; | |
2100 | denominator = ap + fp + 1; | |
2101 | out: | |
6f04f48d SS |
2102 | some_scanned = false; |
2103 | /* Only use force_scan on second pass. */ | |
2104 | for (pass = 0; !some_scanned && pass < 2; pass++) { | |
6b4f7799 | 2105 | *lru_pages = 0; |
6f04f48d SS |
2106 | for_each_evictable_lru(lru) { |
2107 | int file = is_file_lru(lru); | |
2108 | unsigned long size; | |
2109 | unsigned long scan; | |
6e08a369 | 2110 | |
6f04f48d SS |
2111 | size = get_lru_size(lruvec, lru); |
2112 | scan = size >> sc->priority; | |
9a265114 | 2113 | |
6f04f48d SS |
2114 | if (!scan && pass && force_scan) |
2115 | scan = min(size, SWAP_CLUSTER_MAX); | |
9a265114 | 2116 | |
6f04f48d SS |
2117 | switch (scan_balance) { |
2118 | case SCAN_EQUAL: | |
2119 | /* Scan lists relative to size */ | |
2120 | break; | |
2121 | case SCAN_FRACT: | |
2122 | /* | |
2123 | * Scan types proportional to swappiness and | |
2124 | * their relative recent reclaim efficiency. | |
2125 | */ | |
2126 | scan = div64_u64(scan * fraction[file], | |
2127 | denominator); | |
2128 | break; | |
2129 | case SCAN_FILE: | |
2130 | case SCAN_ANON: | |
2131 | /* Scan one type exclusively */ | |
6b4f7799 JW |
2132 | if ((scan_balance == SCAN_FILE) != file) { |
2133 | size = 0; | |
6f04f48d | 2134 | scan = 0; |
6b4f7799 | 2135 | } |
6f04f48d SS |
2136 | break; |
2137 | default: | |
2138 | /* Look ma, no brain */ | |
2139 | BUG(); | |
2140 | } | |
6b4f7799 JW |
2141 | |
2142 | *lru_pages += size; | |
6f04f48d | 2143 | nr[lru] = scan; |
6b4f7799 | 2144 | |
9a265114 | 2145 | /* |
6f04f48d SS |
2146 | * Skip the second pass and don't force_scan, |
2147 | * if we found something to scan. | |
9a265114 | 2148 | */ |
6f04f48d | 2149 | some_scanned |= !!scan; |
9a265114 | 2150 | } |
76a33fc3 | 2151 | } |
6e08a369 | 2152 | } |
4f98a2fe | 2153 | |
9b4f98cd JW |
2154 | /* |
2155 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
2156 | */ | |
02695175 | 2157 | static void shrink_lruvec(struct lruvec *lruvec, int swappiness, |
6b4f7799 | 2158 | struct scan_control *sc, unsigned long *lru_pages) |
9b4f98cd JW |
2159 | { |
2160 | unsigned long nr[NR_LRU_LISTS]; | |
e82e0561 | 2161 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2162 | unsigned long nr_to_scan; |
2163 | enum lru_list lru; | |
2164 | unsigned long nr_reclaimed = 0; | |
2165 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2166 | struct blk_plug plug; | |
1a501907 | 2167 | bool scan_adjusted; |
9b4f98cd | 2168 | |
6b4f7799 | 2169 | get_scan_count(lruvec, swappiness, sc, nr, lru_pages); |
9b4f98cd | 2170 | |
e82e0561 MG |
2171 | /* Record the original scan target for proportional adjustments later */ |
2172 | memcpy(targets, nr, sizeof(nr)); | |
2173 | ||
1a501907 MG |
2174 | /* |
2175 | * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal | |
2176 | * event that can occur when there is little memory pressure e.g. | |
2177 | * multiple streaming readers/writers. Hence, we do not abort scanning | |
2178 | * when the requested number of pages are reclaimed when scanning at | |
2179 | * DEF_PRIORITY on the assumption that the fact we are direct | |
2180 | * reclaiming implies that kswapd is not keeping up and it is best to | |
2181 | * do a batch of work at once. For memcg reclaim one check is made to | |
2182 | * abort proportional reclaim if either the file or anon lru has already | |
2183 | * dropped to zero at the first pass. | |
2184 | */ | |
2185 | scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && | |
2186 | sc->priority == DEF_PRIORITY); | |
2187 | ||
9b4f98cd JW |
2188 | blk_start_plug(&plug); |
2189 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2190 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2191 | unsigned long nr_anon, nr_file, percentage; |
2192 | unsigned long nr_scanned; | |
2193 | ||
9b4f98cd JW |
2194 | for_each_evictable_lru(lru) { |
2195 | if (nr[lru]) { | |
2196 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2197 | nr[lru] -= nr_to_scan; | |
2198 | ||
2199 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
2200 | lruvec, sc); | |
2201 | } | |
2202 | } | |
e82e0561 MG |
2203 | |
2204 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) | |
2205 | continue; | |
2206 | ||
e82e0561 MG |
2207 | /* |
2208 | * For kswapd and memcg, reclaim at least the number of pages | |
1a501907 | 2209 | * requested. Ensure that the anon and file LRUs are scanned |
e82e0561 MG |
2210 | * proportionally what was requested by get_scan_count(). We |
2211 | * stop reclaiming one LRU and reduce the amount scanning | |
2212 | * proportional to the original scan target. | |
2213 | */ | |
2214 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2215 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2216 | ||
1a501907 MG |
2217 | /* |
2218 | * It's just vindictive to attack the larger once the smaller | |
2219 | * has gone to zero. And given the way we stop scanning the | |
2220 | * smaller below, this makes sure that we only make one nudge | |
2221 | * towards proportionality once we've got nr_to_reclaim. | |
2222 | */ | |
2223 | if (!nr_file || !nr_anon) | |
2224 | break; | |
2225 | ||
e82e0561 MG |
2226 | if (nr_file > nr_anon) { |
2227 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2228 | targets[LRU_ACTIVE_ANON] + 1; | |
2229 | lru = LRU_BASE; | |
2230 | percentage = nr_anon * 100 / scan_target; | |
2231 | } else { | |
2232 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2233 | targets[LRU_ACTIVE_FILE] + 1; | |
2234 | lru = LRU_FILE; | |
2235 | percentage = nr_file * 100 / scan_target; | |
2236 | } | |
2237 | ||
2238 | /* Stop scanning the smaller of the LRU */ | |
2239 | nr[lru] = 0; | |
2240 | nr[lru + LRU_ACTIVE] = 0; | |
2241 | ||
2242 | /* | |
2243 | * Recalculate the other LRU scan count based on its original | |
2244 | * scan target and the percentage scanning already complete | |
2245 | */ | |
2246 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2247 | nr_scanned = targets[lru] - nr[lru]; | |
2248 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2249 | nr[lru] -= min(nr[lru], nr_scanned); | |
2250 | ||
2251 | lru += LRU_ACTIVE; | |
2252 | nr_scanned = targets[lru] - nr[lru]; | |
2253 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2254 | nr[lru] -= min(nr[lru], nr_scanned); | |
2255 | ||
2256 | scan_adjusted = true; | |
9b4f98cd JW |
2257 | } |
2258 | blk_finish_plug(&plug); | |
2259 | sc->nr_reclaimed += nr_reclaimed; | |
2260 | ||
2261 | /* | |
2262 | * Even if we did not try to evict anon pages at all, we want to | |
2263 | * rebalance the anon lru active/inactive ratio. | |
2264 | */ | |
2265 | if (inactive_anon_is_low(lruvec)) | |
2266 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, | |
2267 | sc, LRU_ACTIVE_ANON); | |
2268 | ||
2269 | throttle_vm_writeout(sc->gfp_mask); | |
2270 | } | |
2271 | ||
23b9da55 | 2272 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2273 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2274 | { |
d84da3f9 | 2275 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2276 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2277 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2278 | return true; |
2279 | ||
2280 | return false; | |
2281 | } | |
2282 | ||
3e7d3449 | 2283 | /* |
23b9da55 MG |
2284 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2285 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2286 | * true if more pages should be reclaimed such that when the page allocator | |
2287 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2288 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2289 | */ |
9b4f98cd | 2290 | static inline bool should_continue_reclaim(struct zone *zone, |
3e7d3449 MG |
2291 | unsigned long nr_reclaimed, |
2292 | unsigned long nr_scanned, | |
2293 | struct scan_control *sc) | |
2294 | { | |
2295 | unsigned long pages_for_compaction; | |
2296 | unsigned long inactive_lru_pages; | |
2297 | ||
2298 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2299 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2300 | return false; |
2301 | ||
2876592f MG |
2302 | /* Consider stopping depending on scan and reclaim activity */ |
2303 | if (sc->gfp_mask & __GFP_REPEAT) { | |
2304 | /* | |
2305 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
2306 | * full LRU list has been scanned and we are still failing | |
2307 | * to reclaim pages. This full LRU scan is potentially | |
2308 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
2309 | */ | |
2310 | if (!nr_reclaimed && !nr_scanned) | |
2311 | return false; | |
2312 | } else { | |
2313 | /* | |
2314 | * For non-__GFP_REPEAT allocations which can presumably | |
2315 | * fail without consequence, stop if we failed to reclaim | |
2316 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2317 | * pages that were scanned. This will return to the | |
2318 | * caller faster at the risk reclaim/compaction and | |
2319 | * the resulting allocation attempt fails | |
2320 | */ | |
2321 | if (!nr_reclaimed) | |
2322 | return false; | |
2323 | } | |
3e7d3449 MG |
2324 | |
2325 | /* | |
2326 | * If we have not reclaimed enough pages for compaction and the | |
2327 | * inactive lists are large enough, continue reclaiming | |
2328 | */ | |
2329 | pages_for_compaction = (2UL << sc->order); | |
9b4f98cd | 2330 | inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE); |
ec8acf20 | 2331 | if (get_nr_swap_pages() > 0) |
9b4f98cd | 2332 | inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON); |
3e7d3449 MG |
2333 | if (sc->nr_reclaimed < pages_for_compaction && |
2334 | inactive_lru_pages > pages_for_compaction) | |
2335 | return true; | |
2336 | ||
2337 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
ebff3980 | 2338 | switch (compaction_suitable(zone, sc->order, 0, 0)) { |
3e7d3449 MG |
2339 | case COMPACT_PARTIAL: |
2340 | case COMPACT_CONTINUE: | |
2341 | return false; | |
2342 | default: | |
2343 | return true; | |
2344 | } | |
2345 | } | |
2346 | ||
6b4f7799 JW |
2347 | static bool shrink_zone(struct zone *zone, struct scan_control *sc, |
2348 | bool is_classzone) | |
1da177e4 | 2349 | { |
cb731d6c | 2350 | struct reclaim_state *reclaim_state = current->reclaim_state; |
f0fdc5e8 | 2351 | unsigned long nr_reclaimed, nr_scanned; |
2344d7e4 | 2352 | bool reclaimable = false; |
1da177e4 | 2353 | |
9b4f98cd JW |
2354 | do { |
2355 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2356 | struct mem_cgroup_reclaim_cookie reclaim = { | |
2357 | .zone = zone, | |
2358 | .priority = sc->priority, | |
2359 | }; | |
6b4f7799 | 2360 | unsigned long zone_lru_pages = 0; |
694fbc0f | 2361 | struct mem_cgroup *memcg; |
3e7d3449 | 2362 | |
9b4f98cd JW |
2363 | nr_reclaimed = sc->nr_reclaimed; |
2364 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2365 | |
694fbc0f AM |
2366 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2367 | do { | |
6b4f7799 | 2368 | unsigned long lru_pages; |
cb731d6c | 2369 | unsigned long scanned; |
9b4f98cd | 2370 | struct lruvec *lruvec; |
02695175 | 2371 | int swappiness; |
5660048c | 2372 | |
241994ed JW |
2373 | if (mem_cgroup_low(root, memcg)) { |
2374 | if (!sc->may_thrash) | |
2375 | continue; | |
2376 | mem_cgroup_events(memcg, MEMCG_LOW, 1); | |
2377 | } | |
2378 | ||
9b4f98cd | 2379 | lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
02695175 | 2380 | swappiness = mem_cgroup_swappiness(memcg); |
cb731d6c | 2381 | scanned = sc->nr_scanned; |
f9be23d6 | 2382 | |
6b4f7799 JW |
2383 | shrink_lruvec(lruvec, swappiness, sc, &lru_pages); |
2384 | zone_lru_pages += lru_pages; | |
f16015fb | 2385 | |
cb731d6c VD |
2386 | if (memcg && is_classzone) |
2387 | shrink_slab(sc->gfp_mask, zone_to_nid(zone), | |
2388 | memcg, sc->nr_scanned - scanned, | |
2389 | lru_pages); | |
2390 | ||
9b4f98cd | 2391 | /* |
a394cb8e MH |
2392 | * Direct reclaim and kswapd have to scan all memory |
2393 | * cgroups to fulfill the overall scan target for the | |
9b4f98cd | 2394 | * zone. |
a394cb8e MH |
2395 | * |
2396 | * Limit reclaim, on the other hand, only cares about | |
2397 | * nr_to_reclaim pages to be reclaimed and it will | |
2398 | * retry with decreasing priority if one round over the | |
2399 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2400 | */ |
a394cb8e MH |
2401 | if (!global_reclaim(sc) && |
2402 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2403 | mem_cgroup_iter_break(root, memcg); |
2404 | break; | |
2405 | } | |
241994ed | 2406 | } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); |
70ddf637 | 2407 | |
6b4f7799 JW |
2408 | /* |
2409 | * Shrink the slab caches in the same proportion that | |
2410 | * the eligible LRU pages were scanned. | |
2411 | */ | |
cb731d6c VD |
2412 | if (global_reclaim(sc) && is_classzone) |
2413 | shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL, | |
2414 | sc->nr_scanned - nr_scanned, | |
2415 | zone_lru_pages); | |
2416 | ||
2417 | if (reclaim_state) { | |
2418 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; | |
2419 | reclaim_state->reclaimed_slab = 0; | |
6b4f7799 JW |
2420 | } |
2421 | ||
70ddf637 AV |
2422 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, |
2423 | sc->nr_scanned - nr_scanned, | |
2424 | sc->nr_reclaimed - nr_reclaimed); | |
2425 | ||
2344d7e4 JW |
2426 | if (sc->nr_reclaimed - nr_reclaimed) |
2427 | reclaimable = true; | |
2428 | ||
9b4f98cd JW |
2429 | } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed, |
2430 | sc->nr_scanned - nr_scanned, sc)); | |
2344d7e4 JW |
2431 | |
2432 | return reclaimable; | |
f16015fb JW |
2433 | } |
2434 | ||
53853e2d VB |
2435 | /* |
2436 | * Returns true if compaction should go ahead for a high-order request, or | |
2437 | * the high-order allocation would succeed without compaction. | |
2438 | */ | |
0b06496a | 2439 | static inline bool compaction_ready(struct zone *zone, int order) |
fe4b1b24 MG |
2440 | { |
2441 | unsigned long balance_gap, watermark; | |
2442 | bool watermark_ok; | |
2443 | ||
fe4b1b24 MG |
2444 | /* |
2445 | * Compaction takes time to run and there are potentially other | |
2446 | * callers using the pages just freed. Continue reclaiming until | |
2447 | * there is a buffer of free pages available to give compaction | |
2448 | * a reasonable chance of completing and allocating the page | |
2449 | */ | |
4be89a34 JZ |
2450 | balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP( |
2451 | zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO)); | |
0b06496a | 2452 | watermark = high_wmark_pages(zone) + balance_gap + (2UL << order); |
fe4b1b24 MG |
2453 | watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0); |
2454 | ||
2455 | /* | |
2456 | * If compaction is deferred, reclaim up to a point where | |
2457 | * compaction will have a chance of success when re-enabled | |
2458 | */ | |
0b06496a | 2459 | if (compaction_deferred(zone, order)) |
fe4b1b24 MG |
2460 | return watermark_ok; |
2461 | ||
53853e2d VB |
2462 | /* |
2463 | * If compaction is not ready to start and allocation is not likely | |
2464 | * to succeed without it, then keep reclaiming. | |
2465 | */ | |
ebff3980 | 2466 | if (compaction_suitable(zone, order, 0, 0) == COMPACT_SKIPPED) |
fe4b1b24 MG |
2467 | return false; |
2468 | ||
2469 | return watermark_ok; | |
2470 | } | |
2471 | ||
1da177e4 LT |
2472 | /* |
2473 | * This is the direct reclaim path, for page-allocating processes. We only | |
2474 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2475 | * request. | |
2476 | * | |
41858966 MG |
2477 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
2478 | * Because: | |
1da177e4 LT |
2479 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
2480 | * allocation or | |
41858966 MG |
2481 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
2482 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
2483 | * zone defense algorithm. | |
1da177e4 | 2484 | * |
1da177e4 LT |
2485 | * If a zone is deemed to be full of pinned pages then just give it a light |
2486 | * scan then give up on it. | |
2344d7e4 JW |
2487 | * |
2488 | * Returns true if a zone was reclaimable. | |
1da177e4 | 2489 | */ |
2344d7e4 | 2490 | static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2491 | { |
dd1a239f | 2492 | struct zoneref *z; |
54a6eb5c | 2493 | struct zone *zone; |
0608f43d AM |
2494 | unsigned long nr_soft_reclaimed; |
2495 | unsigned long nr_soft_scanned; | |
619d0d76 | 2496 | gfp_t orig_mask; |
9bbc04ee | 2497 | enum zone_type requested_highidx = gfp_zone(sc->gfp_mask); |
2344d7e4 | 2498 | bool reclaimable = false; |
1cfb419b | 2499 | |
cc715d99 MG |
2500 | /* |
2501 | * If the number of buffer_heads in the machine exceeds the maximum | |
2502 | * allowed level, force direct reclaim to scan the highmem zone as | |
2503 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2504 | */ | |
619d0d76 | 2505 | orig_mask = sc->gfp_mask; |
cc715d99 MG |
2506 | if (buffer_heads_over_limit) |
2507 | sc->gfp_mask |= __GFP_HIGHMEM; | |
2508 | ||
d4debc66 | 2509 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
6b4f7799 JW |
2510 | requested_highidx, sc->nodemask) { |
2511 | enum zone_type classzone_idx; | |
2512 | ||
f3fe6512 | 2513 | if (!populated_zone(zone)) |
1da177e4 | 2514 | continue; |
6b4f7799 JW |
2515 | |
2516 | classzone_idx = requested_highidx; | |
2517 | while (!populated_zone(zone->zone_pgdat->node_zones + | |
2518 | classzone_idx)) | |
2519 | classzone_idx--; | |
2520 | ||
1cfb419b KH |
2521 | /* |
2522 | * Take care memory controller reclaiming has small influence | |
2523 | * to global LRU. | |
2524 | */ | |
89b5fae5 | 2525 | if (global_reclaim(sc)) { |
344736f2 VD |
2526 | if (!cpuset_zone_allowed(zone, |
2527 | GFP_KERNEL | __GFP_HARDWALL)) | |
1cfb419b | 2528 | continue; |
65ec02cb | 2529 | |
6e543d57 LD |
2530 | if (sc->priority != DEF_PRIORITY && |
2531 | !zone_reclaimable(zone)) | |
1cfb419b | 2532 | continue; /* Let kswapd poll it */ |
0b06496a JW |
2533 | |
2534 | /* | |
2535 | * If we already have plenty of memory free for | |
2536 | * compaction in this zone, don't free any more. | |
2537 | * Even though compaction is invoked for any | |
2538 | * non-zero order, only frequent costly order | |
2539 | * reclamation is disruptive enough to become a | |
2540 | * noticeable problem, like transparent huge | |
2541 | * page allocations. | |
2542 | */ | |
2543 | if (IS_ENABLED(CONFIG_COMPACTION) && | |
2544 | sc->order > PAGE_ALLOC_COSTLY_ORDER && | |
2545 | zonelist_zone_idx(z) <= requested_highidx && | |
2546 | compaction_ready(zone, sc->order)) { | |
2547 | sc->compaction_ready = true; | |
2548 | continue; | |
e0887c19 | 2549 | } |
0b06496a | 2550 | |
0608f43d AM |
2551 | /* |
2552 | * This steals pages from memory cgroups over softlimit | |
2553 | * and returns the number of reclaimed pages and | |
2554 | * scanned pages. This works for global memory pressure | |
2555 | * and balancing, not for a memcg's limit. | |
2556 | */ | |
2557 | nr_soft_scanned = 0; | |
2558 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
2559 | sc->order, sc->gfp_mask, | |
2560 | &nr_soft_scanned); | |
2561 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2562 | sc->nr_scanned += nr_soft_scanned; | |
2344d7e4 JW |
2563 | if (nr_soft_reclaimed) |
2564 | reclaimable = true; | |
ac34a1a3 | 2565 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2566 | } |
408d8544 | 2567 | |
6b4f7799 | 2568 | if (shrink_zone(zone, sc, zone_idx(zone) == classzone_idx)) |
2344d7e4 JW |
2569 | reclaimable = true; |
2570 | ||
2571 | if (global_reclaim(sc) && | |
2572 | !reclaimable && zone_reclaimable(zone)) | |
2573 | reclaimable = true; | |
1da177e4 | 2574 | } |
e0c23279 | 2575 | |
619d0d76 WY |
2576 | /* |
2577 | * Restore to original mask to avoid the impact on the caller if we | |
2578 | * promoted it to __GFP_HIGHMEM. | |
2579 | */ | |
2580 | sc->gfp_mask = orig_mask; | |
d1908362 | 2581 | |
2344d7e4 | 2582 | return reclaimable; |
1da177e4 | 2583 | } |
4f98a2fe | 2584 | |
1da177e4 LT |
2585 | /* |
2586 | * This is the main entry point to direct page reclaim. | |
2587 | * | |
2588 | * If a full scan of the inactive list fails to free enough memory then we | |
2589 | * are "out of memory" and something needs to be killed. | |
2590 | * | |
2591 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2592 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2593 | * caller can't do much about. We kick the writeback threads and take explicit |
2594 | * naps in the hope that some of these pages can be written. But if the | |
2595 | * allocating task holds filesystem locks which prevent writeout this might not | |
2596 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2597 | * |
2598 | * returns: 0, if no pages reclaimed | |
2599 | * else, the number of pages reclaimed | |
1da177e4 | 2600 | */ |
dac1d27b | 2601 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
3115cd91 | 2602 | struct scan_control *sc) |
1da177e4 | 2603 | { |
241994ed | 2604 | int initial_priority = sc->priority; |
69e05944 | 2605 | unsigned long total_scanned = 0; |
22fba335 | 2606 | unsigned long writeback_threshold; |
2344d7e4 | 2607 | bool zones_reclaimable; |
241994ed | 2608 | retry: |
873b4771 KK |
2609 | delayacct_freepages_start(); |
2610 | ||
89b5fae5 | 2611 | if (global_reclaim(sc)) |
1cfb419b | 2612 | count_vm_event(ALLOCSTALL); |
1da177e4 | 2613 | |
9e3b2f8c | 2614 | do { |
70ddf637 AV |
2615 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
2616 | sc->priority); | |
66e1707b | 2617 | sc->nr_scanned = 0; |
2344d7e4 | 2618 | zones_reclaimable = shrink_zones(zonelist, sc); |
c6a8a8c5 | 2619 | |
66e1707b | 2620 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2621 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
0b06496a JW |
2622 | break; |
2623 | ||
2624 | if (sc->compaction_ready) | |
2625 | break; | |
1da177e4 | 2626 | |
0e50ce3b MK |
2627 | /* |
2628 | * If we're getting trouble reclaiming, start doing | |
2629 | * writepage even in laptop mode. | |
2630 | */ | |
2631 | if (sc->priority < DEF_PRIORITY - 2) | |
2632 | sc->may_writepage = 1; | |
2633 | ||
1da177e4 LT |
2634 | /* |
2635 | * Try to write back as many pages as we just scanned. This | |
2636 | * tends to cause slow streaming writers to write data to the | |
2637 | * disk smoothly, at the dirtying rate, which is nice. But | |
2638 | * that's undesirable in laptop mode, where we *want* lumpy | |
2639 | * writeout. So in laptop mode, write out the whole world. | |
2640 | */ | |
22fba335 KM |
2641 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2642 | if (total_scanned > writeback_threshold) { | |
0e175a18 CW |
2643 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned, |
2644 | WB_REASON_TRY_TO_FREE_PAGES); | |
66e1707b | 2645 | sc->may_writepage = 1; |
1da177e4 | 2646 | } |
0b06496a | 2647 | } while (--sc->priority >= 0); |
bb21c7ce | 2648 | |
873b4771 KK |
2649 | delayacct_freepages_end(); |
2650 | ||
bb21c7ce KM |
2651 | if (sc->nr_reclaimed) |
2652 | return sc->nr_reclaimed; | |
2653 | ||
0cee34fd | 2654 | /* Aborted reclaim to try compaction? don't OOM, then */ |
0b06496a | 2655 | if (sc->compaction_ready) |
7335084d MG |
2656 | return 1; |
2657 | ||
241994ed JW |
2658 | /* Untapped cgroup reserves? Don't OOM, retry. */ |
2659 | if (!sc->may_thrash) { | |
2660 | sc->priority = initial_priority; | |
2661 | sc->may_thrash = 1; | |
2662 | goto retry; | |
2663 | } | |
2664 | ||
2344d7e4 JW |
2665 | /* Any of the zones still reclaimable? Don't OOM. */ |
2666 | if (zones_reclaimable) | |
bb21c7ce KM |
2667 | return 1; |
2668 | ||
2669 | return 0; | |
1da177e4 LT |
2670 | } |
2671 | ||
5515061d MG |
2672 | static bool pfmemalloc_watermark_ok(pg_data_t *pgdat) |
2673 | { | |
2674 | struct zone *zone; | |
2675 | unsigned long pfmemalloc_reserve = 0; | |
2676 | unsigned long free_pages = 0; | |
2677 | int i; | |
2678 | bool wmark_ok; | |
2679 | ||
2680 | for (i = 0; i <= ZONE_NORMAL; i++) { | |
2681 | zone = &pgdat->node_zones[i]; | |
f012a84a NA |
2682 | if (!populated_zone(zone) || |
2683 | zone_reclaimable_pages(zone) == 0) | |
675becce MG |
2684 | continue; |
2685 | ||
5515061d MG |
2686 | pfmemalloc_reserve += min_wmark_pages(zone); |
2687 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
2688 | } | |
2689 | ||
675becce MG |
2690 | /* If there are no reserves (unexpected config) then do not throttle */ |
2691 | if (!pfmemalloc_reserve) | |
2692 | return true; | |
2693 | ||
5515061d MG |
2694 | wmark_ok = free_pages > pfmemalloc_reserve / 2; |
2695 | ||
2696 | /* kswapd must be awake if processes are being throttled */ | |
2697 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
2698 | pgdat->classzone_idx = min(pgdat->classzone_idx, | |
2699 | (enum zone_type)ZONE_NORMAL); | |
2700 | wake_up_interruptible(&pgdat->kswapd_wait); | |
2701 | } | |
2702 | ||
2703 | return wmark_ok; | |
2704 | } | |
2705 | ||
2706 | /* | |
2707 | * Throttle direct reclaimers if backing storage is backed by the network | |
2708 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
2709 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
2710 | * when the low watermark is reached. |
2711 | * | |
2712 | * Returns true if a fatal signal was delivered during throttling. If this | |
2713 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 2714 | */ |
50694c28 | 2715 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
2716 | nodemask_t *nodemask) |
2717 | { | |
675becce | 2718 | struct zoneref *z; |
5515061d | 2719 | struct zone *zone; |
675becce | 2720 | pg_data_t *pgdat = NULL; |
5515061d MG |
2721 | |
2722 | /* | |
2723 | * Kernel threads should not be throttled as they may be indirectly | |
2724 | * responsible for cleaning pages necessary for reclaim to make forward | |
2725 | * progress. kjournald for example may enter direct reclaim while | |
2726 | * committing a transaction where throttling it could forcing other | |
2727 | * processes to block on log_wait_commit(). | |
2728 | */ | |
2729 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
2730 | goto out; |
2731 | ||
2732 | /* | |
2733 | * If a fatal signal is pending, this process should not throttle. | |
2734 | * It should return quickly so it can exit and free its memory | |
2735 | */ | |
2736 | if (fatal_signal_pending(current)) | |
2737 | goto out; | |
5515061d | 2738 | |
675becce MG |
2739 | /* |
2740 | * Check if the pfmemalloc reserves are ok by finding the first node | |
2741 | * with a usable ZONE_NORMAL or lower zone. The expectation is that | |
2742 | * GFP_KERNEL will be required for allocating network buffers when | |
2743 | * swapping over the network so ZONE_HIGHMEM is unusable. | |
2744 | * | |
2745 | * Throttling is based on the first usable node and throttled processes | |
2746 | * wait on a queue until kswapd makes progress and wakes them. There | |
2747 | * is an affinity then between processes waking up and where reclaim | |
2748 | * progress has been made assuming the process wakes on the same node. | |
2749 | * More importantly, processes running on remote nodes will not compete | |
2750 | * for remote pfmemalloc reserves and processes on different nodes | |
2751 | * should make reasonable progress. | |
2752 | */ | |
2753 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
17636faa | 2754 | gfp_zone(gfp_mask), nodemask) { |
675becce MG |
2755 | if (zone_idx(zone) > ZONE_NORMAL) |
2756 | continue; | |
2757 | ||
2758 | /* Throttle based on the first usable node */ | |
2759 | pgdat = zone->zone_pgdat; | |
2760 | if (pfmemalloc_watermark_ok(pgdat)) | |
2761 | goto out; | |
2762 | break; | |
2763 | } | |
2764 | ||
2765 | /* If no zone was usable by the allocation flags then do not throttle */ | |
2766 | if (!pgdat) | |
50694c28 | 2767 | goto out; |
5515061d | 2768 | |
68243e76 MG |
2769 | /* Account for the throttling */ |
2770 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
2771 | ||
5515061d MG |
2772 | /* |
2773 | * If the caller cannot enter the filesystem, it's possible that it | |
2774 | * is due to the caller holding an FS lock or performing a journal | |
2775 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
2776 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
2777 | * blocked waiting on the same lock. Instead, throttle for up to a | |
2778 | * second before continuing. | |
2779 | */ | |
2780 | if (!(gfp_mask & __GFP_FS)) { | |
2781 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
2782 | pfmemalloc_watermark_ok(pgdat), HZ); | |
50694c28 MG |
2783 | |
2784 | goto check_pending; | |
5515061d MG |
2785 | } |
2786 | ||
2787 | /* Throttle until kswapd wakes the process */ | |
2788 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
2789 | pfmemalloc_watermark_ok(pgdat)); | |
50694c28 MG |
2790 | |
2791 | check_pending: | |
2792 | if (fatal_signal_pending(current)) | |
2793 | return true; | |
2794 | ||
2795 | out: | |
2796 | return false; | |
5515061d MG |
2797 | } |
2798 | ||
dac1d27b | 2799 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2800 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2801 | { |
33906bc5 | 2802 | unsigned long nr_reclaimed; |
66e1707b | 2803 | struct scan_control sc = { |
ee814fe2 | 2804 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
21caf2fc | 2805 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
ee814fe2 JW |
2806 | .order = order, |
2807 | .nodemask = nodemask, | |
2808 | .priority = DEF_PRIORITY, | |
66e1707b | 2809 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2810 | .may_unmap = 1, |
2e2e4259 | 2811 | .may_swap = 1, |
66e1707b BS |
2812 | }; |
2813 | ||
5515061d | 2814 | /* |
50694c28 MG |
2815 | * Do not enter reclaim if fatal signal was delivered while throttled. |
2816 | * 1 is returned so that the page allocator does not OOM kill at this | |
2817 | * point. | |
5515061d | 2818 | */ |
50694c28 | 2819 | if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) |
5515061d MG |
2820 | return 1; |
2821 | ||
33906bc5 MG |
2822 | trace_mm_vmscan_direct_reclaim_begin(order, |
2823 | sc.may_writepage, | |
2824 | gfp_mask); | |
2825 | ||
3115cd91 | 2826 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
33906bc5 MG |
2827 | |
2828 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2829 | ||
2830 | return nr_reclaimed; | |
66e1707b BS |
2831 | } |
2832 | ||
c255a458 | 2833 | #ifdef CONFIG_MEMCG |
66e1707b | 2834 | |
72835c86 | 2835 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg, |
4e416953 | 2836 | gfp_t gfp_mask, bool noswap, |
0ae5e89c YH |
2837 | struct zone *zone, |
2838 | unsigned long *nr_scanned) | |
4e416953 BS |
2839 | { |
2840 | struct scan_control sc = { | |
b8f5c566 | 2841 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
ee814fe2 | 2842 | .target_mem_cgroup = memcg, |
4e416953 BS |
2843 | .may_writepage = !laptop_mode, |
2844 | .may_unmap = 1, | |
2845 | .may_swap = !noswap, | |
4e416953 | 2846 | }; |
f9be23d6 | 2847 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
02695175 | 2848 | int swappiness = mem_cgroup_swappiness(memcg); |
6b4f7799 | 2849 | unsigned long lru_pages; |
0ae5e89c | 2850 | |
4e416953 BS |
2851 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2852 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 2853 | |
9e3b2f8c | 2854 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e KM |
2855 | sc.may_writepage, |
2856 | sc.gfp_mask); | |
2857 | ||
4e416953 BS |
2858 | /* |
2859 | * NOTE: Although we can get the priority field, using it | |
2860 | * here is not a good idea, since it limits the pages we can scan. | |
2861 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2862 | * will pick up pages from other mem cgroup's as well. We hack | |
2863 | * the priority and make it zero. | |
2864 | */ | |
6b4f7799 | 2865 | shrink_lruvec(lruvec, swappiness, &sc, &lru_pages); |
bdce6d9e KM |
2866 | |
2867 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2868 | ||
0ae5e89c | 2869 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2870 | return sc.nr_reclaimed; |
2871 | } | |
2872 | ||
72835c86 | 2873 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
b70a2a21 | 2874 | unsigned long nr_pages, |
a7885eb8 | 2875 | gfp_t gfp_mask, |
b70a2a21 | 2876 | bool may_swap) |
66e1707b | 2877 | { |
4e416953 | 2878 | struct zonelist *zonelist; |
bdce6d9e | 2879 | unsigned long nr_reclaimed; |
889976db | 2880 | int nid; |
66e1707b | 2881 | struct scan_control sc = { |
b70a2a21 | 2882 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
a09ed5e0 YH |
2883 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2884 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
ee814fe2 JW |
2885 | .target_mem_cgroup = memcg, |
2886 | .priority = DEF_PRIORITY, | |
2887 | .may_writepage = !laptop_mode, | |
2888 | .may_unmap = 1, | |
b70a2a21 | 2889 | .may_swap = may_swap, |
a09ed5e0 | 2890 | }; |
66e1707b | 2891 | |
889976db YH |
2892 | /* |
2893 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
2894 | * take care of from where we get pages. So the node where we start the | |
2895 | * scan does not need to be the current node. | |
2896 | */ | |
72835c86 | 2897 | nid = mem_cgroup_select_victim_node(memcg); |
889976db YH |
2898 | |
2899 | zonelist = NODE_DATA(nid)->node_zonelists; | |
bdce6d9e KM |
2900 | |
2901 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2902 | sc.may_writepage, | |
2903 | sc.gfp_mask); | |
2904 | ||
3115cd91 | 2905 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
bdce6d9e KM |
2906 | |
2907 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2908 | ||
2909 | return nr_reclaimed; | |
66e1707b BS |
2910 | } |
2911 | #endif | |
2912 | ||
9e3b2f8c | 2913 | static void age_active_anon(struct zone *zone, struct scan_control *sc) |
f16015fb | 2914 | { |
b95a2f2d | 2915 | struct mem_cgroup *memcg; |
f16015fb | 2916 | |
b95a2f2d JW |
2917 | if (!total_swap_pages) |
2918 | return; | |
2919 | ||
2920 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
2921 | do { | |
c56d5c7d | 2922 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
b95a2f2d | 2923 | |
c56d5c7d | 2924 | if (inactive_anon_is_low(lruvec)) |
1a93be0e | 2925 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 2926 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
2927 | |
2928 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
2929 | } while (memcg); | |
f16015fb JW |
2930 | } |
2931 | ||
60cefed4 JW |
2932 | static bool zone_balanced(struct zone *zone, int order, |
2933 | unsigned long balance_gap, int classzone_idx) | |
2934 | { | |
2935 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) + | |
2936 | balance_gap, classzone_idx, 0)) | |
2937 | return false; | |
2938 | ||
ebff3980 VB |
2939 | if (IS_ENABLED(CONFIG_COMPACTION) && order && compaction_suitable(zone, |
2940 | order, 0, classzone_idx) == COMPACT_SKIPPED) | |
60cefed4 JW |
2941 | return false; |
2942 | ||
2943 | return true; | |
2944 | } | |
2945 | ||
1741c877 | 2946 | /* |
4ae0a48b ZC |
2947 | * pgdat_balanced() is used when checking if a node is balanced. |
2948 | * | |
2949 | * For order-0, all zones must be balanced! | |
2950 | * | |
2951 | * For high-order allocations only zones that meet watermarks and are in a | |
2952 | * zone allowed by the callers classzone_idx are added to balanced_pages. The | |
2953 | * total of balanced pages must be at least 25% of the zones allowed by | |
2954 | * classzone_idx for the node to be considered balanced. Forcing all zones to | |
2955 | * be balanced for high orders can cause excessive reclaim when there are | |
2956 | * imbalanced zones. | |
1741c877 MG |
2957 | * The choice of 25% is due to |
2958 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2959 | * reasonable sized machine | |
2960 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2961 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2962 | * would need to be at least 256M for it to be balance a whole node. |
2963 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2964 | * to balance a node on its own. These seemed like reasonable ratios. | |
2965 | */ | |
4ae0a48b | 2966 | static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) |
1741c877 | 2967 | { |
b40da049 | 2968 | unsigned long managed_pages = 0; |
4ae0a48b | 2969 | unsigned long balanced_pages = 0; |
1741c877 MG |
2970 | int i; |
2971 | ||
4ae0a48b ZC |
2972 | /* Check the watermark levels */ |
2973 | for (i = 0; i <= classzone_idx; i++) { | |
2974 | struct zone *zone = pgdat->node_zones + i; | |
1741c877 | 2975 | |
4ae0a48b ZC |
2976 | if (!populated_zone(zone)) |
2977 | continue; | |
2978 | ||
b40da049 | 2979 | managed_pages += zone->managed_pages; |
4ae0a48b ZC |
2980 | |
2981 | /* | |
2982 | * A special case here: | |
2983 | * | |
2984 | * balance_pgdat() skips over all_unreclaimable after | |
2985 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2986 | * they must be considered balanced here as well! | |
2987 | */ | |
6e543d57 | 2988 | if (!zone_reclaimable(zone)) { |
b40da049 | 2989 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2990 | continue; |
2991 | } | |
2992 | ||
2993 | if (zone_balanced(zone, order, 0, i)) | |
b40da049 | 2994 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2995 | else if (!order) |
2996 | return false; | |
2997 | } | |
2998 | ||
2999 | if (order) | |
b40da049 | 3000 | return balanced_pages >= (managed_pages >> 2); |
4ae0a48b ZC |
3001 | else |
3002 | return true; | |
1741c877 MG |
3003 | } |
3004 | ||
5515061d MG |
3005 | /* |
3006 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
3007 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
3008 | * | |
3009 | * Returns true if kswapd is ready to sleep | |
3010 | */ | |
3011 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, | |
dc83edd9 | 3012 | int classzone_idx) |
f50de2d3 | 3013 | { |
f50de2d3 MG |
3014 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ |
3015 | if (remaining) | |
5515061d MG |
3016 | return false; |
3017 | ||
3018 | /* | |
9e5e3661 VB |
3019 | * The throttled processes are normally woken up in balance_pgdat() as |
3020 | * soon as pfmemalloc_watermark_ok() is true. But there is a potential | |
3021 | * race between when kswapd checks the watermarks and a process gets | |
3022 | * throttled. There is also a potential race if processes get | |
3023 | * throttled, kswapd wakes, a large process exits thereby balancing the | |
3024 | * zones, which causes kswapd to exit balance_pgdat() before reaching | |
3025 | * the wake up checks. If kswapd is going to sleep, no process should | |
3026 | * be sleeping on pfmemalloc_wait, so wake them now if necessary. If | |
3027 | * the wake up is premature, processes will wake kswapd and get | |
3028 | * throttled again. The difference from wake ups in balance_pgdat() is | |
3029 | * that here we are under prepare_to_wait(). | |
5515061d | 3030 | */ |
9e5e3661 VB |
3031 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) |
3032 | wake_up_all(&pgdat->pfmemalloc_wait); | |
f50de2d3 | 3033 | |
4ae0a48b | 3034 | return pgdat_balanced(pgdat, order, classzone_idx); |
f50de2d3 MG |
3035 | } |
3036 | ||
75485363 MG |
3037 | /* |
3038 | * kswapd shrinks the zone by the number of pages required to reach | |
3039 | * the high watermark. | |
b8e83b94 MG |
3040 | * |
3041 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
3042 | * reclaim or if the lack of progress was due to pages under writeback. |
3043 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 3044 | */ |
b8e83b94 | 3045 | static bool kswapd_shrink_zone(struct zone *zone, |
7c954f6d | 3046 | int classzone_idx, |
75485363 | 3047 | struct scan_control *sc, |
2ab44f43 | 3048 | unsigned long *nr_attempted) |
75485363 | 3049 | { |
7c954f6d MG |
3050 | int testorder = sc->order; |
3051 | unsigned long balance_gap; | |
7c954f6d | 3052 | bool lowmem_pressure; |
75485363 MG |
3053 | |
3054 | /* Reclaim above the high watermark. */ | |
3055 | sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); | |
7c954f6d MG |
3056 | |
3057 | /* | |
3058 | * Kswapd reclaims only single pages with compaction enabled. Trying | |
3059 | * too hard to reclaim until contiguous free pages have become | |
3060 | * available can hurt performance by evicting too much useful data | |
3061 | * from memory. Do not reclaim more than needed for compaction. | |
3062 | */ | |
3063 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && | |
ebff3980 VB |
3064 | compaction_suitable(zone, sc->order, 0, classzone_idx) |
3065 | != COMPACT_SKIPPED) | |
7c954f6d MG |
3066 | testorder = 0; |
3067 | ||
3068 | /* | |
3069 | * We put equal pressure on every zone, unless one zone has way too | |
3070 | * many pages free already. The "too many pages" is defined as the | |
3071 | * high wmark plus a "gap" where the gap is either the low | |
3072 | * watermark or 1% of the zone, whichever is smaller. | |
3073 | */ | |
4be89a34 JZ |
3074 | balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP( |
3075 | zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO)); | |
7c954f6d MG |
3076 | |
3077 | /* | |
3078 | * If there is no low memory pressure or the zone is balanced then no | |
3079 | * reclaim is necessary | |
3080 | */ | |
3081 | lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone)); | |
3082 | if (!lowmem_pressure && zone_balanced(zone, testorder, | |
3083 | balance_gap, classzone_idx)) | |
3084 | return true; | |
3085 | ||
6b4f7799 | 3086 | shrink_zone(zone, sc, zone_idx(zone) == classzone_idx); |
75485363 | 3087 | |
2ab44f43 MG |
3088 | /* Account for the number of pages attempted to reclaim */ |
3089 | *nr_attempted += sc->nr_to_reclaim; | |
3090 | ||
57054651 | 3091 | clear_bit(ZONE_WRITEBACK, &zone->flags); |
283aba9f | 3092 | |
7c954f6d MG |
3093 | /* |
3094 | * If a zone reaches its high watermark, consider it to be no longer | |
3095 | * congested. It's possible there are dirty pages backed by congested | |
3096 | * BDIs but as pressure is relieved, speculatively avoid congestion | |
3097 | * waits. | |
3098 | */ | |
6e543d57 | 3099 | if (zone_reclaimable(zone) && |
7c954f6d | 3100 | zone_balanced(zone, testorder, 0, classzone_idx)) { |
57054651 JW |
3101 | clear_bit(ZONE_CONGESTED, &zone->flags); |
3102 | clear_bit(ZONE_DIRTY, &zone->flags); | |
7c954f6d MG |
3103 | } |
3104 | ||
b8e83b94 | 3105 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
3106 | } |
3107 | ||
1da177e4 LT |
3108 | /* |
3109 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 3110 | * they are all at high_wmark_pages(zone). |
1da177e4 | 3111 | * |
0abdee2b | 3112 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
3113 | * |
3114 | * There is special handling here for zones which are full of pinned pages. | |
3115 | * This can happen if the pages are all mlocked, or if they are all used by | |
3116 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
3117 | * What we do is to detect the case where all pages in the zone have been | |
3118 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
3119 | * dead and from now on, only perform a short scan. Basically we're polling | |
3120 | * the zone for when the problem goes away. | |
3121 | * | |
3122 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
3123 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
3124 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
3125 | * lower zones regardless of the number of free pages in the lower zones. This | |
3126 | * interoperates with the page allocator fallback scheme to ensure that aging | |
3127 | * of pages is balanced across the zones. | |
1da177e4 | 3128 | */ |
99504748 | 3129 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 3130 | int *classzone_idx) |
1da177e4 | 3131 | { |
1da177e4 | 3132 | int i; |
99504748 | 3133 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
0608f43d AM |
3134 | unsigned long nr_soft_reclaimed; |
3135 | unsigned long nr_soft_scanned; | |
179e9639 AM |
3136 | struct scan_control sc = { |
3137 | .gfp_mask = GFP_KERNEL, | |
ee814fe2 | 3138 | .order = order, |
b8e83b94 | 3139 | .priority = DEF_PRIORITY, |
ee814fe2 | 3140 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3141 | .may_unmap = 1, |
2e2e4259 | 3142 | .may_swap = 1, |
179e9639 | 3143 | }; |
f8891e5e | 3144 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 3145 | |
9e3b2f8c | 3146 | do { |
2ab44f43 | 3147 | unsigned long nr_attempted = 0; |
b8e83b94 | 3148 | bool raise_priority = true; |
2ab44f43 | 3149 | bool pgdat_needs_compaction = (order > 0); |
b8e83b94 MG |
3150 | |
3151 | sc.nr_reclaimed = 0; | |
1da177e4 | 3152 | |
d6277db4 RW |
3153 | /* |
3154 | * Scan in the highmem->dma direction for the highest | |
3155 | * zone which needs scanning | |
3156 | */ | |
3157 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
3158 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 3159 | |
d6277db4 RW |
3160 | if (!populated_zone(zone)) |
3161 | continue; | |
1da177e4 | 3162 | |
6e543d57 LD |
3163 | if (sc.priority != DEF_PRIORITY && |
3164 | !zone_reclaimable(zone)) | |
d6277db4 | 3165 | continue; |
1da177e4 | 3166 | |
556adecb RR |
3167 | /* |
3168 | * Do some background aging of the anon list, to give | |
3169 | * pages a chance to be referenced before reclaiming. | |
3170 | */ | |
9e3b2f8c | 3171 | age_active_anon(zone, &sc); |
556adecb | 3172 | |
cc715d99 MG |
3173 | /* |
3174 | * If the number of buffer_heads in the machine | |
3175 | * exceeds the maximum allowed level and this node | |
3176 | * has a highmem zone, force kswapd to reclaim from | |
3177 | * it to relieve lowmem pressure. | |
3178 | */ | |
3179 | if (buffer_heads_over_limit && is_highmem_idx(i)) { | |
3180 | end_zone = i; | |
3181 | break; | |
3182 | } | |
3183 | ||
60cefed4 | 3184 | if (!zone_balanced(zone, order, 0, 0)) { |
d6277db4 | 3185 | end_zone = i; |
e1dbeda6 | 3186 | break; |
439423f6 | 3187 | } else { |
d43006d5 MG |
3188 | /* |
3189 | * If balanced, clear the dirty and congested | |
3190 | * flags | |
3191 | */ | |
57054651 JW |
3192 | clear_bit(ZONE_CONGESTED, &zone->flags); |
3193 | clear_bit(ZONE_DIRTY, &zone->flags); | |
1da177e4 | 3194 | } |
1da177e4 | 3195 | } |
dafcb73e | 3196 | |
b8e83b94 | 3197 | if (i < 0) |
e1dbeda6 AM |
3198 | goto out; |
3199 | ||
1da177e4 LT |
3200 | for (i = 0; i <= end_zone; i++) { |
3201 | struct zone *zone = pgdat->node_zones + i; | |
3202 | ||
2ab44f43 MG |
3203 | if (!populated_zone(zone)) |
3204 | continue; | |
3205 | ||
2ab44f43 MG |
3206 | /* |
3207 | * If any zone is currently balanced then kswapd will | |
3208 | * not call compaction as it is expected that the | |
3209 | * necessary pages are already available. | |
3210 | */ | |
3211 | if (pgdat_needs_compaction && | |
3212 | zone_watermark_ok(zone, order, | |
3213 | low_wmark_pages(zone), | |
3214 | *classzone_idx, 0)) | |
3215 | pgdat_needs_compaction = false; | |
1da177e4 LT |
3216 | } |
3217 | ||
b7ea3c41 MG |
3218 | /* |
3219 | * If we're getting trouble reclaiming, start doing writepage | |
3220 | * even in laptop mode. | |
3221 | */ | |
3222 | if (sc.priority < DEF_PRIORITY - 2) | |
3223 | sc.may_writepage = 1; | |
3224 | ||
1da177e4 LT |
3225 | /* |
3226 | * Now scan the zone in the dma->highmem direction, stopping | |
3227 | * at the last zone which needs scanning. | |
3228 | * | |
3229 | * We do this because the page allocator works in the opposite | |
3230 | * direction. This prevents the page allocator from allocating | |
3231 | * pages behind kswapd's direction of progress, which would | |
3232 | * cause too much scanning of the lower zones. | |
3233 | */ | |
3234 | for (i = 0; i <= end_zone; i++) { | |
3235 | struct zone *zone = pgdat->node_zones + i; | |
3236 | ||
f3fe6512 | 3237 | if (!populated_zone(zone)) |
1da177e4 LT |
3238 | continue; |
3239 | ||
6e543d57 LD |
3240 | if (sc.priority != DEF_PRIORITY && |
3241 | !zone_reclaimable(zone)) | |
1da177e4 LT |
3242 | continue; |
3243 | ||
1da177e4 | 3244 | sc.nr_scanned = 0; |
4e416953 | 3245 | |
0608f43d AM |
3246 | nr_soft_scanned = 0; |
3247 | /* | |
3248 | * Call soft limit reclaim before calling shrink_zone. | |
3249 | */ | |
3250 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
3251 | order, sc.gfp_mask, | |
3252 | &nr_soft_scanned); | |
3253 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3254 | ||
32a4330d | 3255 | /* |
7c954f6d MG |
3256 | * There should be no need to raise the scanning |
3257 | * priority if enough pages are already being scanned | |
3258 | * that that high watermark would be met at 100% | |
3259 | * efficiency. | |
fe2c2a10 | 3260 | */ |
6b4f7799 JW |
3261 | if (kswapd_shrink_zone(zone, end_zone, |
3262 | &sc, &nr_attempted)) | |
7c954f6d | 3263 | raise_priority = false; |
1da177e4 | 3264 | } |
5515061d MG |
3265 | |
3266 | /* | |
3267 | * If the low watermark is met there is no need for processes | |
3268 | * to be throttled on pfmemalloc_wait as they should not be | |
3269 | * able to safely make forward progress. Wake them | |
3270 | */ | |
3271 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
3272 | pfmemalloc_watermark_ok(pgdat)) | |
cfc51155 | 3273 | wake_up_all(&pgdat->pfmemalloc_wait); |
5515061d | 3274 | |
1da177e4 | 3275 | /* |
b8e83b94 MG |
3276 | * Fragmentation may mean that the system cannot be rebalanced |
3277 | * for high-order allocations in all zones. If twice the | |
3278 | * allocation size has been reclaimed and the zones are still | |
3279 | * not balanced then recheck the watermarks at order-0 to | |
3280 | * prevent kswapd reclaiming excessively. Assume that a | |
3281 | * process requested a high-order can direct reclaim/compact. | |
1da177e4 | 3282 | */ |
b8e83b94 MG |
3283 | if (order && sc.nr_reclaimed >= 2UL << order) |
3284 | order = sc.order = 0; | |
8357376d | 3285 | |
b8e83b94 MG |
3286 | /* Check if kswapd should be suspending */ |
3287 | if (try_to_freeze() || kthread_should_stop()) | |
3288 | break; | |
8357376d | 3289 | |
2ab44f43 MG |
3290 | /* |
3291 | * Compact if necessary and kswapd is reclaiming at least the | |
3292 | * high watermark number of pages as requsted | |
3293 | */ | |
3294 | if (pgdat_needs_compaction && sc.nr_reclaimed > nr_attempted) | |
3295 | compact_pgdat(pgdat, order); | |
3296 | ||
73ce02e9 | 3297 | /* |
b8e83b94 MG |
3298 | * Raise priority if scanning rate is too low or there was no |
3299 | * progress in reclaiming pages | |
73ce02e9 | 3300 | */ |
b8e83b94 MG |
3301 | if (raise_priority || !sc.nr_reclaimed) |
3302 | sc.priority--; | |
9aa41348 | 3303 | } while (sc.priority >= 1 && |
b8e83b94 | 3304 | !pgdat_balanced(pgdat, order, *classzone_idx)); |
1da177e4 | 3305 | |
b8e83b94 | 3306 | out: |
0abdee2b | 3307 | /* |
5515061d | 3308 | * Return the order we were reclaiming at so prepare_kswapd_sleep() |
0abdee2b MG |
3309 | * makes a decision on the order we were last reclaiming at. However, |
3310 | * if another caller entered the allocator slow path while kswapd | |
3311 | * was awake, order will remain at the higher level | |
3312 | */ | |
dc83edd9 | 3313 | *classzone_idx = end_zone; |
0abdee2b | 3314 | return order; |
1da177e4 LT |
3315 | } |
3316 | ||
dc83edd9 | 3317 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
3318 | { |
3319 | long remaining = 0; | |
3320 | DEFINE_WAIT(wait); | |
3321 | ||
3322 | if (freezing(current) || kthread_should_stop()) | |
3323 | return; | |
3324 | ||
3325 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3326 | ||
3327 | /* Try to sleep for a short interval */ | |
5515061d | 3328 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3329 | remaining = schedule_timeout(HZ/10); |
3330 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3331 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3332 | } | |
3333 | ||
3334 | /* | |
3335 | * After a short sleep, check if it was a premature sleep. If not, then | |
3336 | * go fully to sleep until explicitly woken up. | |
3337 | */ | |
5515061d | 3338 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3339 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3340 | ||
3341 | /* | |
3342 | * vmstat counters are not perfectly accurate and the estimated | |
3343 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3344 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3345 | * watermarks being breached while under pressure, we reduce the | |
3346 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3347 | * them before going back to sleep. | |
3348 | */ | |
3349 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c | 3350 | |
62997027 MG |
3351 | /* |
3352 | * Compaction records what page blocks it recently failed to | |
3353 | * isolate pages from and skips them in the future scanning. | |
3354 | * When kswapd is going to sleep, it is reasonable to assume | |
3355 | * that pages and compaction may succeed so reset the cache. | |
3356 | */ | |
3357 | reset_isolation_suitable(pgdat); | |
3358 | ||
1c7e7f6c AK |
3359 | if (!kthread_should_stop()) |
3360 | schedule(); | |
3361 | ||
f0bc0a60 KM |
3362 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3363 | } else { | |
3364 | if (remaining) | |
3365 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3366 | else | |
3367 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3368 | } | |
3369 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3370 | } | |
3371 | ||
1da177e4 LT |
3372 | /* |
3373 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3374 | * from the init process. |
1da177e4 LT |
3375 | * |
3376 | * This basically trickles out pages so that we have _some_ | |
3377 | * free memory available even if there is no other activity | |
3378 | * that frees anything up. This is needed for things like routing | |
3379 | * etc, where we otherwise might have all activity going on in | |
3380 | * asynchronous contexts that cannot page things out. | |
3381 | * | |
3382 | * If there are applications that are active memory-allocators | |
3383 | * (most normal use), this basically shouldn't matter. | |
3384 | */ | |
3385 | static int kswapd(void *p) | |
3386 | { | |
215ddd66 | 3387 | unsigned long order, new_order; |
d2ebd0f6 | 3388 | unsigned balanced_order; |
215ddd66 | 3389 | int classzone_idx, new_classzone_idx; |
d2ebd0f6 | 3390 | int balanced_classzone_idx; |
1da177e4 LT |
3391 | pg_data_t *pgdat = (pg_data_t*)p; |
3392 | struct task_struct *tsk = current; | |
f0bc0a60 | 3393 | |
1da177e4 LT |
3394 | struct reclaim_state reclaim_state = { |
3395 | .reclaimed_slab = 0, | |
3396 | }; | |
a70f7302 | 3397 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3398 | |
cf40bd16 NP |
3399 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
3400 | ||
174596a0 | 3401 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3402 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3403 | current->reclaim_state = &reclaim_state; |
3404 | ||
3405 | /* | |
3406 | * Tell the memory management that we're a "memory allocator", | |
3407 | * and that if we need more memory we should get access to it | |
3408 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3409 | * never get caught in the normal page freeing logic. | |
3410 | * | |
3411 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3412 | * you need a small amount of memory in order to be able to | |
3413 | * page out something else, and this flag essentially protects | |
3414 | * us from recursively trying to free more memory as we're | |
3415 | * trying to free the first piece of memory in the first place). | |
3416 | */ | |
930d9152 | 3417 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3418 | set_freezable(); |
1da177e4 | 3419 | |
215ddd66 | 3420 | order = new_order = 0; |
d2ebd0f6 | 3421 | balanced_order = 0; |
215ddd66 | 3422 | classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; |
d2ebd0f6 | 3423 | balanced_classzone_idx = classzone_idx; |
1da177e4 | 3424 | for ( ; ; ) { |
6f6313d4 | 3425 | bool ret; |
3e1d1d28 | 3426 | |
215ddd66 MG |
3427 | /* |
3428 | * If the last balance_pgdat was unsuccessful it's unlikely a | |
3429 | * new request of a similar or harder type will succeed soon | |
3430 | * so consider going to sleep on the basis we reclaimed at | |
3431 | */ | |
d2ebd0f6 AS |
3432 | if (balanced_classzone_idx >= new_classzone_idx && |
3433 | balanced_order == new_order) { | |
215ddd66 MG |
3434 | new_order = pgdat->kswapd_max_order; |
3435 | new_classzone_idx = pgdat->classzone_idx; | |
3436 | pgdat->kswapd_max_order = 0; | |
3437 | pgdat->classzone_idx = pgdat->nr_zones - 1; | |
3438 | } | |
3439 | ||
99504748 | 3440 | if (order < new_order || classzone_idx > new_classzone_idx) { |
1da177e4 LT |
3441 | /* |
3442 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 3443 | * allocation or has tigher zone constraints |
1da177e4 LT |
3444 | */ |
3445 | order = new_order; | |
99504748 | 3446 | classzone_idx = new_classzone_idx; |
1da177e4 | 3447 | } else { |
d2ebd0f6 AS |
3448 | kswapd_try_to_sleep(pgdat, balanced_order, |
3449 | balanced_classzone_idx); | |
1da177e4 | 3450 | order = pgdat->kswapd_max_order; |
99504748 | 3451 | classzone_idx = pgdat->classzone_idx; |
f0dfcde0 AS |
3452 | new_order = order; |
3453 | new_classzone_idx = classzone_idx; | |
4d40502e | 3454 | pgdat->kswapd_max_order = 0; |
215ddd66 | 3455 | pgdat->classzone_idx = pgdat->nr_zones - 1; |
1da177e4 | 3456 | } |
1da177e4 | 3457 | |
8fe23e05 DR |
3458 | ret = try_to_freeze(); |
3459 | if (kthread_should_stop()) | |
3460 | break; | |
3461 | ||
3462 | /* | |
3463 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3464 | * after returning from the refrigerator | |
3465 | */ | |
33906bc5 MG |
3466 | if (!ret) { |
3467 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
d2ebd0f6 AS |
3468 | balanced_classzone_idx = classzone_idx; |
3469 | balanced_order = balance_pgdat(pgdat, order, | |
3470 | &balanced_classzone_idx); | |
33906bc5 | 3471 | } |
1da177e4 | 3472 | } |
b0a8cc58 | 3473 | |
71abdc15 | 3474 | tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); |
b0a8cc58 | 3475 | current->reclaim_state = NULL; |
71abdc15 JW |
3476 | lockdep_clear_current_reclaim_state(); |
3477 | ||
1da177e4 LT |
3478 | return 0; |
3479 | } | |
3480 | ||
3481 | /* | |
3482 | * A zone is low on free memory, so wake its kswapd task to service it. | |
3483 | */ | |
99504748 | 3484 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
3485 | { |
3486 | pg_data_t *pgdat; | |
3487 | ||
f3fe6512 | 3488 | if (!populated_zone(zone)) |
1da177e4 LT |
3489 | return; |
3490 | ||
344736f2 | 3491 | if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) |
1da177e4 | 3492 | return; |
88f5acf8 | 3493 | pgdat = zone->zone_pgdat; |
99504748 | 3494 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 3495 | pgdat->kswapd_max_order = order; |
99504748 MG |
3496 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
3497 | } | |
8d0986e2 | 3498 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3499 | return; |
892f795d | 3500 | if (zone_balanced(zone, order, 0, 0)) |
88f5acf8 MG |
3501 | return; |
3502 | ||
3503 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 3504 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3505 | } |
3506 | ||
c6f37f12 | 3507 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3508 | /* |
7b51755c | 3509 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3510 | * freed pages. |
3511 | * | |
3512 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3513 | * LRU order by reclaiming preferentially | |
3514 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3515 | */ |
7b51755c | 3516 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3517 | { |
d6277db4 | 3518 | struct reclaim_state reclaim_state; |
d6277db4 | 3519 | struct scan_control sc = { |
ee814fe2 | 3520 | .nr_to_reclaim = nr_to_reclaim, |
7b51755c | 3521 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
ee814fe2 | 3522 | .priority = DEF_PRIORITY, |
d6277db4 | 3523 | .may_writepage = 1, |
ee814fe2 JW |
3524 | .may_unmap = 1, |
3525 | .may_swap = 1, | |
7b51755c | 3526 | .hibernation_mode = 1, |
1da177e4 | 3527 | }; |
a09ed5e0 | 3528 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
7b51755c KM |
3529 | struct task_struct *p = current; |
3530 | unsigned long nr_reclaimed; | |
1da177e4 | 3531 | |
7b51755c KM |
3532 | p->flags |= PF_MEMALLOC; |
3533 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
3534 | reclaim_state.reclaimed_slab = 0; | |
3535 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3536 | |
3115cd91 | 3537 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 3538 | |
7b51755c KM |
3539 | p->reclaim_state = NULL; |
3540 | lockdep_clear_current_reclaim_state(); | |
3541 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 3542 | |
7b51755c | 3543 | return nr_reclaimed; |
1da177e4 | 3544 | } |
c6f37f12 | 3545 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3546 | |
1da177e4 LT |
3547 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3548 | not required for correctness. So if the last cpu in a node goes | |
3549 | away, we get changed to run anywhere: as the first one comes back, | |
3550 | restore their cpu bindings. */ | |
fcb35a9b GKH |
3551 | static int cpu_callback(struct notifier_block *nfb, unsigned long action, |
3552 | void *hcpu) | |
1da177e4 | 3553 | { |
58c0a4a7 | 3554 | int nid; |
1da177e4 | 3555 | |
8bb78442 | 3556 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
48fb2e24 | 3557 | for_each_node_state(nid, N_MEMORY) { |
c5f59f08 | 3558 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
3559 | const struct cpumask *mask; |
3560 | ||
3561 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 3562 | |
3e597945 | 3563 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 3564 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 3565 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
3566 | } |
3567 | } | |
3568 | return NOTIFY_OK; | |
3569 | } | |
1da177e4 | 3570 | |
3218ae14 YG |
3571 | /* |
3572 | * This kswapd start function will be called by init and node-hot-add. | |
3573 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3574 | */ | |
3575 | int kswapd_run(int nid) | |
3576 | { | |
3577 | pg_data_t *pgdat = NODE_DATA(nid); | |
3578 | int ret = 0; | |
3579 | ||
3580 | if (pgdat->kswapd) | |
3581 | return 0; | |
3582 | ||
3583 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3584 | if (IS_ERR(pgdat->kswapd)) { | |
3585 | /* failure at boot is fatal */ | |
3586 | BUG_ON(system_state == SYSTEM_BOOTING); | |
d5dc0ad9 GS |
3587 | pr_err("Failed to start kswapd on node %d\n", nid); |
3588 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3589 | pgdat->kswapd = NULL; |
3218ae14 YG |
3590 | } |
3591 | return ret; | |
3592 | } | |
3593 | ||
8fe23e05 | 3594 | /* |
d8adde17 | 3595 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
bfc8c901 | 3596 | * hold mem_hotplug_begin/end(). |
8fe23e05 DR |
3597 | */ |
3598 | void kswapd_stop(int nid) | |
3599 | { | |
3600 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3601 | ||
d8adde17 | 3602 | if (kswapd) { |
8fe23e05 | 3603 | kthread_stop(kswapd); |
d8adde17 JL |
3604 | NODE_DATA(nid)->kswapd = NULL; |
3605 | } | |
8fe23e05 DR |
3606 | } |
3607 | ||
1da177e4 LT |
3608 | static int __init kswapd_init(void) |
3609 | { | |
3218ae14 | 3610 | int nid; |
69e05944 | 3611 | |
1da177e4 | 3612 | swap_setup(); |
48fb2e24 | 3613 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3614 | kswapd_run(nid); |
1da177e4 LT |
3615 | hotcpu_notifier(cpu_callback, 0); |
3616 | return 0; | |
3617 | } | |
3618 | ||
3619 | module_init(kswapd_init) | |
9eeff239 CL |
3620 | |
3621 | #ifdef CONFIG_NUMA | |
3622 | /* | |
3623 | * Zone reclaim mode | |
3624 | * | |
3625 | * If non-zero call zone_reclaim when the number of free pages falls below | |
3626 | * the watermarks. | |
9eeff239 CL |
3627 | */ |
3628 | int zone_reclaim_mode __read_mostly; | |
3629 | ||
1b2ffb78 | 3630 | #define RECLAIM_OFF 0 |
7d03431c | 3631 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 | 3632 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
95bbc0c7 | 3633 | #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ |
1b2ffb78 | 3634 | |
a92f7126 CL |
3635 | /* |
3636 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
3637 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
3638 | * a zone. | |
3639 | */ | |
3640 | #define ZONE_RECLAIM_PRIORITY 4 | |
3641 | ||
9614634f CL |
3642 | /* |
3643 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
3644 | * occur. | |
3645 | */ | |
3646 | int sysctl_min_unmapped_ratio = 1; | |
3647 | ||
0ff38490 CL |
3648 | /* |
3649 | * If the number of slab pages in a zone grows beyond this percentage then | |
3650 | * slab reclaim needs to occur. | |
3651 | */ | |
3652 | int sysctl_min_slab_ratio = 5; | |
3653 | ||
90afa5de MG |
3654 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
3655 | { | |
3656 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
3657 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
3658 | zone_page_state(zone, NR_ACTIVE_FILE); | |
3659 | ||
3660 | /* | |
3661 | * It's possible for there to be more file mapped pages than | |
3662 | * accounted for by the pages on the file LRU lists because | |
3663 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3664 | */ | |
3665 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3666 | } | |
3667 | ||
3668 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
3669 | static long zone_pagecache_reclaimable(struct zone *zone) | |
3670 | { | |
3671 | long nr_pagecache_reclaimable; | |
3672 | long delta = 0; | |
3673 | ||
3674 | /* | |
95bbc0c7 | 3675 | * If RECLAIM_UNMAP is set, then all file pages are considered |
90afa5de MG |
3676 | * potentially reclaimable. Otherwise, we have to worry about |
3677 | * pages like swapcache and zone_unmapped_file_pages() provides | |
3678 | * a better estimate | |
3679 | */ | |
95bbc0c7 | 3680 | if (zone_reclaim_mode & RECLAIM_UNMAP) |
90afa5de MG |
3681 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); |
3682 | else | |
3683 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
3684 | ||
3685 | /* If we can't clean pages, remove dirty pages from consideration */ | |
3686 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
3687 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
3688 | ||
3689 | /* Watch for any possible underflows due to delta */ | |
3690 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3691 | delta = nr_pagecache_reclaimable; | |
3692 | ||
3693 | return nr_pagecache_reclaimable - delta; | |
3694 | } | |
3695 | ||
9eeff239 CL |
3696 | /* |
3697 | * Try to free up some pages from this zone through reclaim. | |
3698 | */ | |
179e9639 | 3699 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3700 | { |
7fb2d46d | 3701 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3702 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3703 | struct task_struct *p = current; |
3704 | struct reclaim_state reclaim_state; | |
179e9639 | 3705 | struct scan_control sc = { |
62b726c1 | 3706 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
21caf2fc | 3707 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
bd2f6199 | 3708 | .order = order, |
9e3b2f8c | 3709 | .priority = ZONE_RECLAIM_PRIORITY, |
ee814fe2 | 3710 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), |
95bbc0c7 | 3711 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP), |
ee814fe2 | 3712 | .may_swap = 1, |
179e9639 | 3713 | }; |
9eeff239 | 3714 | |
9eeff239 | 3715 | cond_resched(); |
d4f7796e | 3716 | /* |
95bbc0c7 | 3717 | * We need to be able to allocate from the reserves for RECLAIM_UNMAP |
d4f7796e | 3718 | * and we also need to be able to write out pages for RECLAIM_WRITE |
95bbc0c7 | 3719 | * and RECLAIM_UNMAP. |
d4f7796e CL |
3720 | */ |
3721 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3722 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3723 | reclaim_state.reclaimed_slab = 0; |
3724 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3725 | |
90afa5de | 3726 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3727 | /* |
3728 | * Free memory by calling shrink zone with increasing | |
3729 | * priorities until we have enough memory freed. | |
3730 | */ | |
0ff38490 | 3731 | do { |
6b4f7799 | 3732 | shrink_zone(zone, &sc, true); |
9e3b2f8c | 3733 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); |
0ff38490 | 3734 | } |
c84db23c | 3735 | |
9eeff239 | 3736 | p->reclaim_state = NULL; |
d4f7796e | 3737 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3738 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3739 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3740 | } |
179e9639 AM |
3741 | |
3742 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3743 | { | |
179e9639 | 3744 | int node_id; |
d773ed6b | 3745 | int ret; |
179e9639 AM |
3746 | |
3747 | /* | |
0ff38490 CL |
3748 | * Zone reclaim reclaims unmapped file backed pages and |
3749 | * slab pages if we are over the defined limits. | |
34aa1330 | 3750 | * |
9614634f CL |
3751 | * A small portion of unmapped file backed pages is needed for |
3752 | * file I/O otherwise pages read by file I/O will be immediately | |
3753 | * thrown out if the zone is overallocated. So we do not reclaim | |
3754 | * if less than a specified percentage of the zone is used by | |
3755 | * unmapped file backed pages. | |
179e9639 | 3756 | */ |
90afa5de MG |
3757 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3758 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3759 | return ZONE_RECLAIM_FULL; |
179e9639 | 3760 | |
6e543d57 | 3761 | if (!zone_reclaimable(zone)) |
fa5e084e | 3762 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3763 | |
179e9639 | 3764 | /* |
d773ed6b | 3765 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3766 | */ |
d773ed6b | 3767 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3768 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3769 | |
3770 | /* | |
3771 | * Only run zone reclaim on the local zone or on zones that do not | |
3772 | * have associated processors. This will favor the local processor | |
3773 | * over remote processors and spread off node memory allocations | |
3774 | * as wide as possible. | |
3775 | */ | |
89fa3024 | 3776 | node_id = zone_to_nid(zone); |
37c0708d | 3777 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3778 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b | 3779 | |
57054651 | 3780 | if (test_and_set_bit(ZONE_RECLAIM_LOCKED, &zone->flags)) |
fa5e084e MG |
3781 | return ZONE_RECLAIM_NOSCAN; |
3782 | ||
d773ed6b | 3783 | ret = __zone_reclaim(zone, gfp_mask, order); |
57054651 | 3784 | clear_bit(ZONE_RECLAIM_LOCKED, &zone->flags); |
d773ed6b | 3785 | |
24cf7251 MG |
3786 | if (!ret) |
3787 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3788 | ||
d773ed6b | 3789 | return ret; |
179e9639 | 3790 | } |
9eeff239 | 3791 | #endif |
894bc310 | 3792 | |
894bc310 LS |
3793 | /* |
3794 | * page_evictable - test whether a page is evictable | |
3795 | * @page: the page to test | |
894bc310 LS |
3796 | * |
3797 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 3798 | * lists vs unevictable list. |
894bc310 LS |
3799 | * |
3800 | * Reasons page might not be evictable: | |
ba9ddf49 | 3801 | * (1) page's mapping marked unevictable |
b291f000 | 3802 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3803 | * |
894bc310 | 3804 | */ |
39b5f29a | 3805 | int page_evictable(struct page *page) |
894bc310 | 3806 | { |
39b5f29a | 3807 | return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); |
894bc310 | 3808 | } |
89e004ea | 3809 | |
85046579 | 3810 | #ifdef CONFIG_SHMEM |
89e004ea | 3811 | /** |
24513264 HD |
3812 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
3813 | * @pages: array of pages to check | |
3814 | * @nr_pages: number of pages to check | |
89e004ea | 3815 | * |
24513264 | 3816 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
3817 | * |
3818 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 3819 | */ |
24513264 | 3820 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 3821 | { |
925b7673 | 3822 | struct lruvec *lruvec; |
24513264 HD |
3823 | struct zone *zone = NULL; |
3824 | int pgscanned = 0; | |
3825 | int pgrescued = 0; | |
3826 | int i; | |
89e004ea | 3827 | |
24513264 HD |
3828 | for (i = 0; i < nr_pages; i++) { |
3829 | struct page *page = pages[i]; | |
3830 | struct zone *pagezone; | |
89e004ea | 3831 | |
24513264 HD |
3832 | pgscanned++; |
3833 | pagezone = page_zone(page); | |
3834 | if (pagezone != zone) { | |
3835 | if (zone) | |
3836 | spin_unlock_irq(&zone->lru_lock); | |
3837 | zone = pagezone; | |
3838 | spin_lock_irq(&zone->lru_lock); | |
3839 | } | |
fa9add64 | 3840 | lruvec = mem_cgroup_page_lruvec(page, zone); |
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 | |
24513264 HD |
3856 | if (zone) { |
3857 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); | |
3858 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
3859 | spin_unlock_irq(&zone->lru_lock); | |
89e004ea | 3860 | } |
89e004ea | 3861 | } |
85046579 | 3862 | #endif /* CONFIG_SHMEM */ |