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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 | } |
91a45470 | 157 | #else |
89b5fae5 JW |
158 | static bool global_reclaim(struct scan_control *sc) |
159 | { | |
160 | return true; | |
161 | } | |
91a45470 KH |
162 | #endif |
163 | ||
a1c3bfb2 | 164 | static unsigned long zone_reclaimable_pages(struct zone *zone) |
6e543d57 LD |
165 | { |
166 | int nr; | |
167 | ||
168 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
169 | zone_page_state(zone, NR_INACTIVE_FILE); | |
170 | ||
171 | if (get_nr_swap_pages() > 0) | |
172 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
173 | zone_page_state(zone, NR_INACTIVE_ANON); | |
174 | ||
175 | return nr; | |
176 | } | |
177 | ||
178 | bool zone_reclaimable(struct zone *zone) | |
179 | { | |
0d5d823a MG |
180 | return zone_page_state(zone, NR_PAGES_SCANNED) < |
181 | zone_reclaimable_pages(zone) * 6; | |
6e543d57 LD |
182 | } |
183 | ||
4d7dcca2 | 184 | static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru) |
c9f299d9 | 185 | { |
c3c787e8 | 186 | if (!mem_cgroup_disabled()) |
4d7dcca2 | 187 | return mem_cgroup_get_lru_size(lruvec, lru); |
a3d8e054 | 188 | |
074291fe | 189 | return zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru); |
c9f299d9 KM |
190 | } |
191 | ||
1da177e4 | 192 | /* |
1d3d4437 | 193 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 194 | */ |
1d3d4437 | 195 | int register_shrinker(struct shrinker *shrinker) |
1da177e4 | 196 | { |
1d3d4437 GC |
197 | size_t size = sizeof(*shrinker->nr_deferred); |
198 | ||
199 | /* | |
200 | * If we only have one possible node in the system anyway, save | |
201 | * ourselves the trouble and disable NUMA aware behavior. This way we | |
202 | * will save memory and some small loop time later. | |
203 | */ | |
204 | if (nr_node_ids == 1) | |
205 | shrinker->flags &= ~SHRINKER_NUMA_AWARE; | |
206 | ||
207 | if (shrinker->flags & SHRINKER_NUMA_AWARE) | |
208 | size *= nr_node_ids; | |
209 | ||
210 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
211 | if (!shrinker->nr_deferred) | |
212 | return -ENOMEM; | |
213 | ||
8e1f936b RR |
214 | down_write(&shrinker_rwsem); |
215 | list_add_tail(&shrinker->list, &shrinker_list); | |
216 | up_write(&shrinker_rwsem); | |
1d3d4437 | 217 | return 0; |
1da177e4 | 218 | } |
8e1f936b | 219 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
220 | |
221 | /* | |
222 | * Remove one | |
223 | */ | |
8e1f936b | 224 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
225 | { |
226 | down_write(&shrinker_rwsem); | |
227 | list_del(&shrinker->list); | |
228 | up_write(&shrinker_rwsem); | |
ae393321 | 229 | kfree(shrinker->nr_deferred); |
1da177e4 | 230 | } |
8e1f936b | 231 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
232 | |
233 | #define SHRINK_BATCH 128 | |
1d3d4437 | 234 | |
cb731d6c VD |
235 | static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, |
236 | struct shrinker *shrinker, | |
237 | unsigned long nr_scanned, | |
238 | unsigned long nr_eligible) | |
1d3d4437 GC |
239 | { |
240 | unsigned long freed = 0; | |
241 | unsigned long long delta; | |
242 | long total_scan; | |
d5bc5fd3 | 243 | long freeable; |
1d3d4437 GC |
244 | long nr; |
245 | long new_nr; | |
246 | int nid = shrinkctl->nid; | |
247 | long batch_size = shrinker->batch ? shrinker->batch | |
248 | : SHRINK_BATCH; | |
249 | ||
d5bc5fd3 VD |
250 | freeable = shrinker->count_objects(shrinker, shrinkctl); |
251 | if (freeable == 0) | |
1d3d4437 GC |
252 | return 0; |
253 | ||
254 | /* | |
255 | * copy the current shrinker scan count into a local variable | |
256 | * and zero it so that other concurrent shrinker invocations | |
257 | * don't also do this scanning work. | |
258 | */ | |
259 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
260 | ||
261 | total_scan = nr; | |
6b4f7799 | 262 | delta = (4 * nr_scanned) / shrinker->seeks; |
d5bc5fd3 | 263 | delta *= freeable; |
6b4f7799 | 264 | do_div(delta, nr_eligible + 1); |
1d3d4437 GC |
265 | total_scan += delta; |
266 | if (total_scan < 0) { | |
8612c663 | 267 | pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", |
a0b02131 | 268 | shrinker->scan_objects, total_scan); |
d5bc5fd3 | 269 | total_scan = freeable; |
1d3d4437 GC |
270 | } |
271 | ||
272 | /* | |
273 | * We need to avoid excessive windup on filesystem shrinkers | |
274 | * due to large numbers of GFP_NOFS allocations causing the | |
275 | * shrinkers to return -1 all the time. This results in a large | |
276 | * nr being built up so when a shrink that can do some work | |
277 | * comes along it empties the entire cache due to nr >>> | |
d5bc5fd3 | 278 | * freeable. This is bad for sustaining a working set in |
1d3d4437 GC |
279 | * memory. |
280 | * | |
281 | * Hence only allow the shrinker to scan the entire cache when | |
282 | * a large delta change is calculated directly. | |
283 | */ | |
d5bc5fd3 VD |
284 | if (delta < freeable / 4) |
285 | total_scan = min(total_scan, freeable / 2); | |
1d3d4437 GC |
286 | |
287 | /* | |
288 | * Avoid risking looping forever due to too large nr value: | |
289 | * never try to free more than twice the estimate number of | |
290 | * freeable entries. | |
291 | */ | |
d5bc5fd3 VD |
292 | if (total_scan > freeable * 2) |
293 | total_scan = freeable * 2; | |
1d3d4437 GC |
294 | |
295 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
6b4f7799 JW |
296 | nr_scanned, nr_eligible, |
297 | freeable, delta, total_scan); | |
1d3d4437 | 298 | |
0b1fb40a VD |
299 | /* |
300 | * Normally, we should not scan less than batch_size objects in one | |
301 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
302 | * than batch_size objects in total and we are really tight on memory, | |
303 | * we will try to reclaim all available objects, otherwise we can end | |
304 | * up failing allocations although there are plenty of reclaimable | |
305 | * objects spread over several slabs with usage less than the | |
306 | * batch_size. | |
307 | * | |
308 | * We detect the "tight on memory" situations by looking at the total | |
309 | * number of objects we want to scan (total_scan). If it is greater | |
d5bc5fd3 | 310 | * than the total number of objects on slab (freeable), we must be |
0b1fb40a VD |
311 | * scanning at high prio and therefore should try to reclaim as much as |
312 | * possible. | |
313 | */ | |
314 | while (total_scan >= batch_size || | |
d5bc5fd3 | 315 | total_scan >= freeable) { |
a0b02131 | 316 | unsigned long ret; |
0b1fb40a | 317 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 318 | |
0b1fb40a | 319 | shrinkctl->nr_to_scan = nr_to_scan; |
a0b02131 DC |
320 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
321 | if (ret == SHRINK_STOP) | |
322 | break; | |
323 | freed += ret; | |
1d3d4437 | 324 | |
0b1fb40a VD |
325 | count_vm_events(SLABS_SCANNED, nr_to_scan); |
326 | total_scan -= nr_to_scan; | |
1d3d4437 GC |
327 | |
328 | cond_resched(); | |
329 | } | |
330 | ||
331 | /* | |
332 | * move the unused scan count back into the shrinker in a | |
333 | * manner that handles concurrent updates. If we exhausted the | |
334 | * scan, there is no need to do an update. | |
335 | */ | |
336 | if (total_scan > 0) | |
337 | new_nr = atomic_long_add_return(total_scan, | |
338 | &shrinker->nr_deferred[nid]); | |
339 | else | |
340 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
341 | ||
df9024a8 | 342 | trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); |
1d3d4437 | 343 | return freed; |
1495f230 YH |
344 | } |
345 | ||
6b4f7799 | 346 | /** |
cb731d6c | 347 | * shrink_slab - shrink slab caches |
6b4f7799 JW |
348 | * @gfp_mask: allocation context |
349 | * @nid: node whose slab caches to target | |
cb731d6c | 350 | * @memcg: memory cgroup whose slab caches to target |
6b4f7799 JW |
351 | * @nr_scanned: pressure numerator |
352 | * @nr_eligible: pressure denominator | |
1da177e4 | 353 | * |
6b4f7799 | 354 | * Call the shrink functions to age shrinkable caches. |
1da177e4 | 355 | * |
6b4f7799 JW |
356 | * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, |
357 | * unaware shrinkers will receive a node id of 0 instead. | |
1da177e4 | 358 | * |
cb731d6c VD |
359 | * @memcg specifies the memory cgroup to target. If it is not NULL, |
360 | * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan | |
361 | * objects from the memory cgroup specified. Otherwise all shrinkers | |
362 | * are called, and memcg aware shrinkers are supposed to scan the | |
363 | * global list then. | |
364 | * | |
6b4f7799 JW |
365 | * @nr_scanned and @nr_eligible form a ratio that indicate how much of |
366 | * the available objects should be scanned. Page reclaim for example | |
367 | * passes the number of pages scanned and the number of pages on the | |
368 | * LRU lists that it considered on @nid, plus a bias in @nr_scanned | |
369 | * when it encountered mapped pages. The ratio is further biased by | |
370 | * the ->seeks setting of the shrink function, which indicates the | |
371 | * cost to recreate an object relative to that of an LRU page. | |
b15e0905 | 372 | * |
6b4f7799 | 373 | * Returns the number of reclaimed slab objects. |
1da177e4 | 374 | */ |
cb731d6c VD |
375 | static unsigned long shrink_slab(gfp_t gfp_mask, int nid, |
376 | struct mem_cgroup *memcg, | |
377 | unsigned long nr_scanned, | |
378 | unsigned long nr_eligible) | |
1da177e4 LT |
379 | { |
380 | struct shrinker *shrinker; | |
24f7c6b9 | 381 | unsigned long freed = 0; |
1da177e4 | 382 | |
cb731d6c VD |
383 | if (memcg && !memcg_kmem_is_active(memcg)) |
384 | return 0; | |
385 | ||
6b4f7799 JW |
386 | if (nr_scanned == 0) |
387 | nr_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 388 | |
f06590bd | 389 | if (!down_read_trylock(&shrinker_rwsem)) { |
24f7c6b9 DC |
390 | /* |
391 | * If we would return 0, our callers would understand that we | |
392 | * have nothing else to shrink and give up trying. By returning | |
393 | * 1 we keep it going and assume we'll be able to shrink next | |
394 | * time. | |
395 | */ | |
396 | freed = 1; | |
f06590bd MK |
397 | goto out; |
398 | } | |
1da177e4 LT |
399 | |
400 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
6b4f7799 JW |
401 | struct shrink_control sc = { |
402 | .gfp_mask = gfp_mask, | |
403 | .nid = nid, | |
cb731d6c | 404 | .memcg = memcg, |
6b4f7799 | 405 | }; |
ec97097b | 406 | |
cb731d6c VD |
407 | if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE)) |
408 | continue; | |
409 | ||
6b4f7799 JW |
410 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) |
411 | sc.nid = 0; | |
1da177e4 | 412 | |
cb731d6c | 413 | freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible); |
1da177e4 | 414 | } |
6b4f7799 | 415 | |
1da177e4 | 416 | up_read(&shrinker_rwsem); |
f06590bd MK |
417 | out: |
418 | cond_resched(); | |
24f7c6b9 | 419 | return freed; |
1da177e4 LT |
420 | } |
421 | ||
cb731d6c VD |
422 | void drop_slab_node(int nid) |
423 | { | |
424 | unsigned long freed; | |
425 | ||
426 | do { | |
427 | struct mem_cgroup *memcg = NULL; | |
428 | ||
429 | freed = 0; | |
430 | do { | |
431 | freed += shrink_slab(GFP_KERNEL, nid, memcg, | |
432 | 1000, 1000); | |
433 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); | |
434 | } while (freed > 10); | |
435 | } | |
436 | ||
437 | void drop_slab(void) | |
438 | { | |
439 | int nid; | |
440 | ||
441 | for_each_online_node(nid) | |
442 | drop_slab_node(nid); | |
443 | } | |
444 | ||
1da177e4 LT |
445 | static inline int is_page_cache_freeable(struct page *page) |
446 | { | |
ceddc3a5 JW |
447 | /* |
448 | * A freeable page cache page is referenced only by the caller | |
449 | * that isolated the page, the page cache radix tree and | |
450 | * optional buffer heads at page->private. | |
451 | */ | |
edcf4748 | 452 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
453 | } |
454 | ||
7d3579e8 KM |
455 | static int may_write_to_queue(struct backing_dev_info *bdi, |
456 | struct scan_control *sc) | |
1da177e4 | 457 | { |
930d9152 | 458 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
459 | return 1; |
460 | if (!bdi_write_congested(bdi)) | |
461 | return 1; | |
462 | if (bdi == current->backing_dev_info) | |
463 | return 1; | |
464 | return 0; | |
465 | } | |
466 | ||
467 | /* | |
468 | * We detected a synchronous write error writing a page out. Probably | |
469 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
470 | * fsync(), msync() or close(). | |
471 | * | |
472 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
473 | * prevents it from being freed up. But we have a ref on the page and once | |
474 | * that page is locked, the mapping is pinned. | |
475 | * | |
476 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
477 | * __GFP_FS. | |
478 | */ | |
479 | static void handle_write_error(struct address_space *mapping, | |
480 | struct page *page, int error) | |
481 | { | |
7eaceacc | 482 | lock_page(page); |
3e9f45bd GC |
483 | if (page_mapping(page) == mapping) |
484 | mapping_set_error(mapping, error); | |
1da177e4 LT |
485 | unlock_page(page); |
486 | } | |
487 | ||
04e62a29 CL |
488 | /* possible outcome of pageout() */ |
489 | typedef enum { | |
490 | /* failed to write page out, page is locked */ | |
491 | PAGE_KEEP, | |
492 | /* move page to the active list, page is locked */ | |
493 | PAGE_ACTIVATE, | |
494 | /* page has been sent to the disk successfully, page is unlocked */ | |
495 | PAGE_SUCCESS, | |
496 | /* page is clean and locked */ | |
497 | PAGE_CLEAN, | |
498 | } pageout_t; | |
499 | ||
1da177e4 | 500 | /* |
1742f19f AM |
501 | * pageout is called by shrink_page_list() for each dirty page. |
502 | * Calls ->writepage(). | |
1da177e4 | 503 | */ |
c661b078 | 504 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 505 | struct scan_control *sc) |
1da177e4 LT |
506 | { |
507 | /* | |
508 | * If the page is dirty, only perform writeback if that write | |
509 | * will be non-blocking. To prevent this allocation from being | |
510 | * stalled by pagecache activity. But note that there may be | |
511 | * stalls if we need to run get_block(). We could test | |
512 | * PagePrivate for that. | |
513 | * | |
8174202b | 514 | * If this process is currently in __generic_file_write_iter() against |
1da177e4 LT |
515 | * this page's queue, we can perform writeback even if that |
516 | * will block. | |
517 | * | |
518 | * If the page is swapcache, write it back even if that would | |
519 | * block, for some throttling. This happens by accident, because | |
520 | * swap_backing_dev_info is bust: it doesn't reflect the | |
521 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
522 | */ |
523 | if (!is_page_cache_freeable(page)) | |
524 | return PAGE_KEEP; | |
525 | if (!mapping) { | |
526 | /* | |
527 | * Some data journaling orphaned pages can have | |
528 | * page->mapping == NULL while being dirty with clean buffers. | |
529 | */ | |
266cf658 | 530 | if (page_has_private(page)) { |
1da177e4 LT |
531 | if (try_to_free_buffers(page)) { |
532 | ClearPageDirty(page); | |
b1de0d13 | 533 | pr_info("%s: orphaned page\n", __func__); |
1da177e4 LT |
534 | return PAGE_CLEAN; |
535 | } | |
536 | } | |
537 | return PAGE_KEEP; | |
538 | } | |
539 | if (mapping->a_ops->writepage == NULL) | |
540 | return PAGE_ACTIVATE; | |
de1414a6 | 541 | if (!may_write_to_queue(inode_to_bdi(mapping->host), sc)) |
1da177e4 LT |
542 | return PAGE_KEEP; |
543 | ||
544 | if (clear_page_dirty_for_io(page)) { | |
545 | int res; | |
546 | struct writeback_control wbc = { | |
547 | .sync_mode = WB_SYNC_NONE, | |
548 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
549 | .range_start = 0, |
550 | .range_end = LLONG_MAX, | |
1da177e4 LT |
551 | .for_reclaim = 1, |
552 | }; | |
553 | ||
554 | SetPageReclaim(page); | |
555 | res = mapping->a_ops->writepage(page, &wbc); | |
556 | if (res < 0) | |
557 | handle_write_error(mapping, page, res); | |
994fc28c | 558 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
559 | ClearPageReclaim(page); |
560 | return PAGE_ACTIVATE; | |
561 | } | |
c661b078 | 562 | |
1da177e4 LT |
563 | if (!PageWriteback(page)) { |
564 | /* synchronous write or broken a_ops? */ | |
565 | ClearPageReclaim(page); | |
566 | } | |
23b9da55 | 567 | trace_mm_vmscan_writepage(page, trace_reclaim_flags(page)); |
e129b5c2 | 568 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
569 | return PAGE_SUCCESS; |
570 | } | |
571 | ||
572 | return PAGE_CLEAN; | |
573 | } | |
574 | ||
a649fd92 | 575 | /* |
e286781d NP |
576 | * Same as remove_mapping, but if the page is removed from the mapping, it |
577 | * gets returned with a refcount of 0. | |
a649fd92 | 578 | */ |
a528910e JW |
579 | static int __remove_mapping(struct address_space *mapping, struct page *page, |
580 | bool reclaimed) | |
49d2e9cc | 581 | { |
28e4d965 NP |
582 | BUG_ON(!PageLocked(page)); |
583 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 584 | |
19fd6231 | 585 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 586 | /* |
0fd0e6b0 NP |
587 | * The non racy check for a busy page. |
588 | * | |
589 | * Must be careful with the order of the tests. When someone has | |
590 | * a ref to the page, it may be possible that they dirty it then | |
591 | * drop the reference. So if PageDirty is tested before page_count | |
592 | * here, then the following race may occur: | |
593 | * | |
594 | * get_user_pages(&page); | |
595 | * [user mapping goes away] | |
596 | * write_to(page); | |
597 | * !PageDirty(page) [good] | |
598 | * SetPageDirty(page); | |
599 | * put_page(page); | |
600 | * !page_count(page) [good, discard it] | |
601 | * | |
602 | * [oops, our write_to data is lost] | |
603 | * | |
604 | * Reversing the order of the tests ensures such a situation cannot | |
605 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
606 | * load is not satisfied before that of page->_count. | |
607 | * | |
608 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
609 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 610 | */ |
e286781d | 611 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 612 | goto cannot_free; |
e286781d NP |
613 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
614 | if (unlikely(PageDirty(page))) { | |
615 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 616 | goto cannot_free; |
e286781d | 617 | } |
49d2e9cc CL |
618 | |
619 | if (PageSwapCache(page)) { | |
620 | swp_entry_t swap = { .val = page_private(page) }; | |
0a31bc97 | 621 | mem_cgroup_swapout(page, swap); |
49d2e9cc | 622 | __delete_from_swap_cache(page); |
19fd6231 | 623 | spin_unlock_irq(&mapping->tree_lock); |
0a31bc97 | 624 | swapcache_free(swap); |
e286781d | 625 | } else { |
6072d13c | 626 | void (*freepage)(struct page *); |
a528910e | 627 | void *shadow = NULL; |
6072d13c LT |
628 | |
629 | freepage = mapping->a_ops->freepage; | |
a528910e JW |
630 | /* |
631 | * Remember a shadow entry for reclaimed file cache in | |
632 | * order to detect refaults, thus thrashing, later on. | |
633 | * | |
634 | * But don't store shadows in an address space that is | |
635 | * already exiting. This is not just an optizimation, | |
636 | * inode reclaim needs to empty out the radix tree or | |
637 | * the nodes are lost. Don't plant shadows behind its | |
638 | * back. | |
639 | */ | |
640 | if (reclaimed && page_is_file_cache(page) && | |
641 | !mapping_exiting(mapping)) | |
642 | shadow = workingset_eviction(mapping, page); | |
643 | __delete_from_page_cache(page, shadow); | |
19fd6231 | 644 | spin_unlock_irq(&mapping->tree_lock); |
6072d13c LT |
645 | |
646 | if (freepage != NULL) | |
647 | freepage(page); | |
49d2e9cc CL |
648 | } |
649 | ||
49d2e9cc CL |
650 | return 1; |
651 | ||
652 | cannot_free: | |
19fd6231 | 653 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
654 | return 0; |
655 | } | |
656 | ||
e286781d NP |
657 | /* |
658 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
659 | * someone else has a ref on the page, abort and return 0. If it was | |
660 | * successfully detached, return 1. Assumes the caller has a single ref on | |
661 | * this page. | |
662 | */ | |
663 | int remove_mapping(struct address_space *mapping, struct page *page) | |
664 | { | |
a528910e | 665 | if (__remove_mapping(mapping, page, false)) { |
e286781d NP |
666 | /* |
667 | * Unfreezing the refcount with 1 rather than 2 effectively | |
668 | * drops the pagecache ref for us without requiring another | |
669 | * atomic operation. | |
670 | */ | |
671 | page_unfreeze_refs(page, 1); | |
672 | return 1; | |
673 | } | |
674 | return 0; | |
675 | } | |
676 | ||
894bc310 LS |
677 | /** |
678 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
679 | * @page: page to be put back to appropriate lru list | |
680 | * | |
681 | * Add previously isolated @page to appropriate LRU list. | |
682 | * Page may still be unevictable for other reasons. | |
683 | * | |
684 | * lru_lock must not be held, interrupts must be enabled. | |
685 | */ | |
894bc310 LS |
686 | void putback_lru_page(struct page *page) |
687 | { | |
0ec3b74c | 688 | bool is_unevictable; |
bbfd28ee | 689 | int was_unevictable = PageUnevictable(page); |
894bc310 | 690 | |
309381fe | 691 | VM_BUG_ON_PAGE(PageLRU(page), page); |
894bc310 LS |
692 | |
693 | redo: | |
694 | ClearPageUnevictable(page); | |
695 | ||
39b5f29a | 696 | if (page_evictable(page)) { |
894bc310 LS |
697 | /* |
698 | * For evictable pages, we can use the cache. | |
699 | * In event of a race, worst case is we end up with an | |
700 | * unevictable page on [in]active list. | |
701 | * We know how to handle that. | |
702 | */ | |
0ec3b74c | 703 | is_unevictable = false; |
c53954a0 | 704 | lru_cache_add(page); |
894bc310 LS |
705 | } else { |
706 | /* | |
707 | * Put unevictable pages directly on zone's unevictable | |
708 | * list. | |
709 | */ | |
0ec3b74c | 710 | is_unevictable = true; |
894bc310 | 711 | add_page_to_unevictable_list(page); |
6a7b9548 | 712 | /* |
21ee9f39 MK |
713 | * When racing with an mlock or AS_UNEVICTABLE clearing |
714 | * (page is unlocked) make sure that if the other thread | |
715 | * does not observe our setting of PG_lru and fails | |
24513264 | 716 | * isolation/check_move_unevictable_pages, |
21ee9f39 | 717 | * we see PG_mlocked/AS_UNEVICTABLE cleared below and move |
6a7b9548 JW |
718 | * the page back to the evictable list. |
719 | * | |
21ee9f39 | 720 | * The other side is TestClearPageMlocked() or shmem_lock(). |
6a7b9548 JW |
721 | */ |
722 | smp_mb(); | |
894bc310 | 723 | } |
894bc310 LS |
724 | |
725 | /* | |
726 | * page's status can change while we move it among lru. If an evictable | |
727 | * page is on unevictable list, it never be freed. To avoid that, | |
728 | * check after we added it to the list, again. | |
729 | */ | |
0ec3b74c | 730 | if (is_unevictable && page_evictable(page)) { |
894bc310 LS |
731 | if (!isolate_lru_page(page)) { |
732 | put_page(page); | |
733 | goto redo; | |
734 | } | |
735 | /* This means someone else dropped this page from LRU | |
736 | * So, it will be freed or putback to LRU again. There is | |
737 | * nothing to do here. | |
738 | */ | |
739 | } | |
740 | ||
0ec3b74c | 741 | if (was_unevictable && !is_unevictable) |
bbfd28ee | 742 | count_vm_event(UNEVICTABLE_PGRESCUED); |
0ec3b74c | 743 | else if (!was_unevictable && is_unevictable) |
bbfd28ee LS |
744 | count_vm_event(UNEVICTABLE_PGCULLED); |
745 | ||
894bc310 LS |
746 | put_page(page); /* drop ref from isolate */ |
747 | } | |
748 | ||
dfc8d636 JW |
749 | enum page_references { |
750 | PAGEREF_RECLAIM, | |
751 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 752 | PAGEREF_KEEP, |
dfc8d636 JW |
753 | PAGEREF_ACTIVATE, |
754 | }; | |
755 | ||
756 | static enum page_references page_check_references(struct page *page, | |
757 | struct scan_control *sc) | |
758 | { | |
64574746 | 759 | int referenced_ptes, referenced_page; |
dfc8d636 | 760 | unsigned long vm_flags; |
dfc8d636 | 761 | |
c3ac9a8a JW |
762 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
763 | &vm_flags); | |
64574746 | 764 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 765 | |
dfc8d636 JW |
766 | /* |
767 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
768 | * move the page to the unevictable list. | |
769 | */ | |
770 | if (vm_flags & VM_LOCKED) | |
771 | return PAGEREF_RECLAIM; | |
772 | ||
64574746 | 773 | if (referenced_ptes) { |
e4898273 | 774 | if (PageSwapBacked(page)) |
64574746 JW |
775 | return PAGEREF_ACTIVATE; |
776 | /* | |
777 | * All mapped pages start out with page table | |
778 | * references from the instantiating fault, so we need | |
779 | * to look twice if a mapped file page is used more | |
780 | * than once. | |
781 | * | |
782 | * Mark it and spare it for another trip around the | |
783 | * inactive list. Another page table reference will | |
784 | * lead to its activation. | |
785 | * | |
786 | * Note: the mark is set for activated pages as well | |
787 | * so that recently deactivated but used pages are | |
788 | * quickly recovered. | |
789 | */ | |
790 | SetPageReferenced(page); | |
791 | ||
34dbc67a | 792 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
793 | return PAGEREF_ACTIVATE; |
794 | ||
c909e993 KK |
795 | /* |
796 | * Activate file-backed executable pages after first usage. | |
797 | */ | |
798 | if (vm_flags & VM_EXEC) | |
799 | return PAGEREF_ACTIVATE; | |
800 | ||
64574746 JW |
801 | return PAGEREF_KEEP; |
802 | } | |
dfc8d636 JW |
803 | |
804 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 805 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
806 | return PAGEREF_RECLAIM_CLEAN; |
807 | ||
808 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
809 | } |
810 | ||
e2be15f6 MG |
811 | /* Check if a page is dirty or under writeback */ |
812 | static void page_check_dirty_writeback(struct page *page, | |
813 | bool *dirty, bool *writeback) | |
814 | { | |
b4597226 MG |
815 | struct address_space *mapping; |
816 | ||
e2be15f6 MG |
817 | /* |
818 | * Anonymous pages are not handled by flushers and must be written | |
819 | * from reclaim context. Do not stall reclaim based on them | |
820 | */ | |
821 | if (!page_is_file_cache(page)) { | |
822 | *dirty = false; | |
823 | *writeback = false; | |
824 | return; | |
825 | } | |
826 | ||
827 | /* By default assume that the page flags are accurate */ | |
828 | *dirty = PageDirty(page); | |
829 | *writeback = PageWriteback(page); | |
b4597226 MG |
830 | |
831 | /* Verify dirty/writeback state if the filesystem supports it */ | |
832 | if (!page_has_private(page)) | |
833 | return; | |
834 | ||
835 | mapping = page_mapping(page); | |
836 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
837 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
838 | } |
839 | ||
1da177e4 | 840 | /* |
1742f19f | 841 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 842 | */ |
1742f19f | 843 | static unsigned long shrink_page_list(struct list_head *page_list, |
6a18adb3 | 844 | struct zone *zone, |
f84f6e2b | 845 | struct scan_control *sc, |
02c6de8d | 846 | enum ttu_flags ttu_flags, |
8e950282 | 847 | unsigned long *ret_nr_dirty, |
d43006d5 | 848 | unsigned long *ret_nr_unqueued_dirty, |
8e950282 | 849 | unsigned long *ret_nr_congested, |
02c6de8d | 850 | unsigned long *ret_nr_writeback, |
b1a6f21e | 851 | unsigned long *ret_nr_immediate, |
02c6de8d | 852 | bool force_reclaim) |
1da177e4 LT |
853 | { |
854 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 855 | LIST_HEAD(free_pages); |
1da177e4 | 856 | int pgactivate = 0; |
d43006d5 | 857 | unsigned long nr_unqueued_dirty = 0; |
0e093d99 MG |
858 | unsigned long nr_dirty = 0; |
859 | unsigned long nr_congested = 0; | |
05ff5137 | 860 | unsigned long nr_reclaimed = 0; |
92df3a72 | 861 | unsigned long nr_writeback = 0; |
b1a6f21e | 862 | unsigned long nr_immediate = 0; |
1da177e4 LT |
863 | |
864 | cond_resched(); | |
865 | ||
1da177e4 LT |
866 | while (!list_empty(page_list)) { |
867 | struct address_space *mapping; | |
868 | struct page *page; | |
869 | int may_enter_fs; | |
02c6de8d | 870 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 871 | bool dirty, writeback; |
1da177e4 LT |
872 | |
873 | cond_resched(); | |
874 | ||
875 | page = lru_to_page(page_list); | |
876 | list_del(&page->lru); | |
877 | ||
529ae9aa | 878 | if (!trylock_page(page)) |
1da177e4 LT |
879 | goto keep; |
880 | ||
309381fe SL |
881 | VM_BUG_ON_PAGE(PageActive(page), page); |
882 | VM_BUG_ON_PAGE(page_zone(page) != zone, page); | |
1da177e4 LT |
883 | |
884 | sc->nr_scanned++; | |
80e43426 | 885 | |
39b5f29a | 886 | if (unlikely(!page_evictable(page))) |
b291f000 | 887 | goto cull_mlocked; |
894bc310 | 888 | |
a6dc60f8 | 889 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
890 | goto keep_locked; |
891 | ||
1da177e4 LT |
892 | /* Double the slab pressure for mapped and swapcache pages */ |
893 | if (page_mapped(page) || PageSwapCache(page)) | |
894 | sc->nr_scanned++; | |
895 | ||
c661b078 AW |
896 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
897 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
898 | ||
e2be15f6 MG |
899 | /* |
900 | * The number of dirty pages determines if a zone is marked | |
901 | * reclaim_congested which affects wait_iff_congested. kswapd | |
902 | * will stall and start writing pages if the tail of the LRU | |
903 | * is all dirty unqueued pages. | |
904 | */ | |
905 | page_check_dirty_writeback(page, &dirty, &writeback); | |
906 | if (dirty || writeback) | |
907 | nr_dirty++; | |
908 | ||
909 | if (dirty && !writeback) | |
910 | nr_unqueued_dirty++; | |
911 | ||
d04e8acd MG |
912 | /* |
913 | * Treat this page as congested if the underlying BDI is or if | |
914 | * pages are cycling through the LRU so quickly that the | |
915 | * pages marked for immediate reclaim are making it to the | |
916 | * end of the LRU a second time. | |
917 | */ | |
e2be15f6 | 918 | mapping = page_mapping(page); |
1da58ee2 | 919 | if (((dirty || writeback) && mapping && |
de1414a6 | 920 | bdi_write_congested(inode_to_bdi(mapping->host))) || |
d04e8acd | 921 | (writeback && PageReclaim(page))) |
e2be15f6 MG |
922 | nr_congested++; |
923 | ||
283aba9f MG |
924 | /* |
925 | * If a page at the tail of the LRU is under writeback, there | |
926 | * are three cases to consider. | |
927 | * | |
928 | * 1) If reclaim is encountering an excessive number of pages | |
929 | * under writeback and this page is both under writeback and | |
930 | * PageReclaim then it indicates that pages are being queued | |
931 | * for IO but are being recycled through the LRU before the | |
932 | * IO can complete. Waiting on the page itself risks an | |
933 | * indefinite stall if it is impossible to writeback the | |
934 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
935 | * note that the LRU is being scanned too quickly and the |
936 | * caller can stall after page list has been processed. | |
283aba9f MG |
937 | * |
938 | * 2) Global reclaim encounters a page, memcg encounters a | |
939 | * page that is not marked for immediate reclaim or | |
940 | * the caller does not have __GFP_IO. In this case mark | |
941 | * the page for immediate reclaim and continue scanning. | |
942 | * | |
943 | * __GFP_IO is checked because a loop driver thread might | |
944 | * enter reclaim, and deadlock if it waits on a page for | |
945 | * which it is needed to do the write (loop masks off | |
946 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
947 | * would probably show more reasons. | |
948 | * | |
949 | * Don't require __GFP_FS, since we're not going into the | |
950 | * FS, just waiting on its writeback completion. Worryingly, | |
951 | * ext4 gfs2 and xfs allocate pages with | |
952 | * grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so testing | |
953 | * may_enter_fs here is liable to OOM on them. | |
954 | * | |
955 | * 3) memcg encounters a page that is not already marked | |
956 | * PageReclaim. memcg does not have any dirty pages | |
957 | * throttling so we could easily OOM just because too many | |
958 | * pages are in writeback and there is nothing else to | |
959 | * reclaim. Wait for the writeback to complete. | |
960 | */ | |
c661b078 | 961 | if (PageWriteback(page)) { |
283aba9f MG |
962 | /* Case 1 above */ |
963 | if (current_is_kswapd() && | |
964 | PageReclaim(page) && | |
57054651 | 965 | test_bit(ZONE_WRITEBACK, &zone->flags)) { |
b1a6f21e MG |
966 | nr_immediate++; |
967 | goto keep_locked; | |
283aba9f MG |
968 | |
969 | /* Case 2 above */ | |
970 | } else if (global_reclaim(sc) || | |
c3b94f44 HD |
971 | !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) { |
972 | /* | |
973 | * This is slightly racy - end_page_writeback() | |
974 | * might have just cleared PageReclaim, then | |
975 | * setting PageReclaim here end up interpreted | |
976 | * as PageReadahead - but that does not matter | |
977 | * enough to care. What we do want is for this | |
978 | * page to have PageReclaim set next time memcg | |
979 | * reclaim reaches the tests above, so it will | |
980 | * then wait_on_page_writeback() to avoid OOM; | |
981 | * and it's also appropriate in global reclaim. | |
982 | */ | |
983 | SetPageReclaim(page); | |
e62e384e | 984 | nr_writeback++; |
283aba9f | 985 | |
c3b94f44 | 986 | goto keep_locked; |
283aba9f MG |
987 | |
988 | /* Case 3 above */ | |
989 | } else { | |
990 | wait_on_page_writeback(page); | |
e62e384e | 991 | } |
c661b078 | 992 | } |
1da177e4 | 993 | |
02c6de8d MK |
994 | if (!force_reclaim) |
995 | references = page_check_references(page, sc); | |
996 | ||
dfc8d636 JW |
997 | switch (references) { |
998 | case PAGEREF_ACTIVATE: | |
1da177e4 | 999 | goto activate_locked; |
64574746 JW |
1000 | case PAGEREF_KEEP: |
1001 | goto keep_locked; | |
dfc8d636 JW |
1002 | case PAGEREF_RECLAIM: |
1003 | case PAGEREF_RECLAIM_CLEAN: | |
1004 | ; /* try to reclaim the page below */ | |
1005 | } | |
1da177e4 | 1006 | |
1da177e4 LT |
1007 | /* |
1008 | * Anonymous process memory has backing store? | |
1009 | * Try to allocate it some swap space here. | |
1010 | */ | |
b291f000 | 1011 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
1012 | if (!(sc->gfp_mask & __GFP_IO)) |
1013 | goto keep_locked; | |
5bc7b8ac | 1014 | if (!add_to_swap(page, page_list)) |
1da177e4 | 1015 | goto activate_locked; |
63eb6b93 | 1016 | may_enter_fs = 1; |
1da177e4 | 1017 | |
e2be15f6 MG |
1018 | /* Adding to swap updated mapping */ |
1019 | mapping = page_mapping(page); | |
1020 | } | |
1da177e4 LT |
1021 | |
1022 | /* | |
1023 | * The page is mapped into the page tables of one or more | |
1024 | * processes. Try to unmap it here. | |
1025 | */ | |
1026 | if (page_mapped(page) && mapping) { | |
02c6de8d | 1027 | switch (try_to_unmap(page, ttu_flags)) { |
1da177e4 LT |
1028 | case SWAP_FAIL: |
1029 | goto activate_locked; | |
1030 | case SWAP_AGAIN: | |
1031 | goto keep_locked; | |
b291f000 NP |
1032 | case SWAP_MLOCK: |
1033 | goto cull_mlocked; | |
1da177e4 LT |
1034 | case SWAP_SUCCESS: |
1035 | ; /* try to free the page below */ | |
1036 | } | |
1037 | } | |
1038 | ||
1039 | if (PageDirty(page)) { | |
ee72886d MG |
1040 | /* |
1041 | * Only kswapd can writeback filesystem pages to | |
d43006d5 MG |
1042 | * avoid risk of stack overflow but only writeback |
1043 | * if many dirty pages have been encountered. | |
ee72886d | 1044 | */ |
f84f6e2b | 1045 | if (page_is_file_cache(page) && |
9e3b2f8c | 1046 | (!current_is_kswapd() || |
57054651 | 1047 | !test_bit(ZONE_DIRTY, &zone->flags))) { |
49ea7eb6 MG |
1048 | /* |
1049 | * Immediately reclaim when written back. | |
1050 | * Similar in principal to deactivate_page() | |
1051 | * except we already have the page isolated | |
1052 | * and know it's dirty | |
1053 | */ | |
1054 | inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE); | |
1055 | SetPageReclaim(page); | |
1056 | ||
ee72886d MG |
1057 | goto keep_locked; |
1058 | } | |
1059 | ||
dfc8d636 | 1060 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 1061 | goto keep_locked; |
4dd4b920 | 1062 | if (!may_enter_fs) |
1da177e4 | 1063 | goto keep_locked; |
52a8363e | 1064 | if (!sc->may_writepage) |
1da177e4 LT |
1065 | goto keep_locked; |
1066 | ||
1067 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 1068 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1069 | case PAGE_KEEP: |
1070 | goto keep_locked; | |
1071 | case PAGE_ACTIVATE: | |
1072 | goto activate_locked; | |
1073 | case PAGE_SUCCESS: | |
7d3579e8 | 1074 | if (PageWriteback(page)) |
41ac1999 | 1075 | goto keep; |
7d3579e8 | 1076 | if (PageDirty(page)) |
1da177e4 | 1077 | goto keep; |
7d3579e8 | 1078 | |
1da177e4 LT |
1079 | /* |
1080 | * A synchronous write - probably a ramdisk. Go | |
1081 | * ahead and try to reclaim the page. | |
1082 | */ | |
529ae9aa | 1083 | if (!trylock_page(page)) |
1da177e4 LT |
1084 | goto keep; |
1085 | if (PageDirty(page) || PageWriteback(page)) | |
1086 | goto keep_locked; | |
1087 | mapping = page_mapping(page); | |
1088 | case PAGE_CLEAN: | |
1089 | ; /* try to free the page below */ | |
1090 | } | |
1091 | } | |
1092 | ||
1093 | /* | |
1094 | * If the page has buffers, try to free the buffer mappings | |
1095 | * associated with this page. If we succeed we try to free | |
1096 | * the page as well. | |
1097 | * | |
1098 | * We do this even if the page is PageDirty(). | |
1099 | * try_to_release_page() does not perform I/O, but it is | |
1100 | * possible for a page to have PageDirty set, but it is actually | |
1101 | * clean (all its buffers are clean). This happens if the | |
1102 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1103 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1104 | * try_to_release_page() will discover that cleanness and will |
1105 | * drop the buffers and mark the page clean - it can be freed. | |
1106 | * | |
1107 | * Rarely, pages can have buffers and no ->mapping. These are | |
1108 | * the pages which were not successfully invalidated in | |
1109 | * truncate_complete_page(). We try to drop those buffers here | |
1110 | * and if that worked, and the page is no longer mapped into | |
1111 | * process address space (page_count == 1) it can be freed. | |
1112 | * Otherwise, leave the page on the LRU so it is swappable. | |
1113 | */ | |
266cf658 | 1114 | if (page_has_private(page)) { |
1da177e4 LT |
1115 | if (!try_to_release_page(page, sc->gfp_mask)) |
1116 | goto activate_locked; | |
e286781d NP |
1117 | if (!mapping && page_count(page) == 1) { |
1118 | unlock_page(page); | |
1119 | if (put_page_testzero(page)) | |
1120 | goto free_it; | |
1121 | else { | |
1122 | /* | |
1123 | * rare race with speculative reference. | |
1124 | * the speculative reference will free | |
1125 | * this page shortly, so we may | |
1126 | * increment nr_reclaimed here (and | |
1127 | * leave it off the LRU). | |
1128 | */ | |
1129 | nr_reclaimed++; | |
1130 | continue; | |
1131 | } | |
1132 | } | |
1da177e4 LT |
1133 | } |
1134 | ||
a528910e | 1135 | if (!mapping || !__remove_mapping(mapping, page, true)) |
49d2e9cc | 1136 | goto keep_locked; |
1da177e4 | 1137 | |
a978d6f5 NP |
1138 | /* |
1139 | * At this point, we have no other references and there is | |
1140 | * no way to pick any more up (removed from LRU, removed | |
1141 | * from pagecache). Can use non-atomic bitops now (and | |
1142 | * we obviously don't have to worry about waking up a process | |
1143 | * waiting on the page lock, because there are no references. | |
1144 | */ | |
1145 | __clear_page_locked(page); | |
e286781d | 1146 | free_it: |
05ff5137 | 1147 | nr_reclaimed++; |
abe4c3b5 MG |
1148 | |
1149 | /* | |
1150 | * Is there need to periodically free_page_list? It would | |
1151 | * appear not as the counts should be low | |
1152 | */ | |
1153 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1154 | continue; |
1155 | ||
b291f000 | 1156 | cull_mlocked: |
63d6c5ad HD |
1157 | if (PageSwapCache(page)) |
1158 | try_to_free_swap(page); | |
b291f000 NP |
1159 | unlock_page(page); |
1160 | putback_lru_page(page); | |
1161 | continue; | |
1162 | ||
1da177e4 | 1163 | activate_locked: |
68a22394 RR |
1164 | /* Not a candidate for swapping, so reclaim swap space. */ |
1165 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 1166 | try_to_free_swap(page); |
309381fe | 1167 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1168 | SetPageActive(page); |
1169 | pgactivate++; | |
1170 | keep_locked: | |
1171 | unlock_page(page); | |
1172 | keep: | |
1173 | list_add(&page->lru, &ret_pages); | |
309381fe | 1174 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1175 | } |
abe4c3b5 | 1176 | |
747db954 | 1177 | mem_cgroup_uncharge_list(&free_pages); |
b745bc85 | 1178 | free_hot_cold_page_list(&free_pages, true); |
abe4c3b5 | 1179 | |
1da177e4 | 1180 | list_splice(&ret_pages, page_list); |
f8891e5e | 1181 | count_vm_events(PGACTIVATE, pgactivate); |
0a31bc97 | 1182 | |
8e950282 MG |
1183 | *ret_nr_dirty += nr_dirty; |
1184 | *ret_nr_congested += nr_congested; | |
d43006d5 | 1185 | *ret_nr_unqueued_dirty += nr_unqueued_dirty; |
92df3a72 | 1186 | *ret_nr_writeback += nr_writeback; |
b1a6f21e | 1187 | *ret_nr_immediate += nr_immediate; |
05ff5137 | 1188 | return nr_reclaimed; |
1da177e4 LT |
1189 | } |
1190 | ||
02c6de8d MK |
1191 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1192 | struct list_head *page_list) | |
1193 | { | |
1194 | struct scan_control sc = { | |
1195 | .gfp_mask = GFP_KERNEL, | |
1196 | .priority = DEF_PRIORITY, | |
1197 | .may_unmap = 1, | |
1198 | }; | |
8e950282 | 1199 | unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5; |
02c6de8d MK |
1200 | struct page *page, *next; |
1201 | LIST_HEAD(clean_pages); | |
1202 | ||
1203 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e RA |
1204 | if (page_is_file_cache(page) && !PageDirty(page) && |
1205 | !isolated_balloon_page(page)) { | |
02c6de8d MK |
1206 | ClearPageActive(page); |
1207 | list_move(&page->lru, &clean_pages); | |
1208 | } | |
1209 | } | |
1210 | ||
1211 | ret = shrink_page_list(&clean_pages, zone, &sc, | |
8e950282 MG |
1212 | TTU_UNMAP|TTU_IGNORE_ACCESS, |
1213 | &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true); | |
02c6de8d | 1214 | list_splice(&clean_pages, page_list); |
83da7510 | 1215 | mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret); |
02c6de8d MK |
1216 | return ret; |
1217 | } | |
1218 | ||
5ad333eb AW |
1219 | /* |
1220 | * Attempt to remove the specified page from its LRU. Only take this page | |
1221 | * if it is of the appropriate PageActive status. Pages which are being | |
1222 | * freed elsewhere are also ignored. | |
1223 | * | |
1224 | * page: page to consider | |
1225 | * mode: one of the LRU isolation modes defined above | |
1226 | * | |
1227 | * returns 0 on success, -ve errno on failure. | |
1228 | */ | |
f3fd4a61 | 1229 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1230 | { |
1231 | int ret = -EINVAL; | |
1232 | ||
1233 | /* Only take pages on the LRU. */ | |
1234 | if (!PageLRU(page)) | |
1235 | return ret; | |
1236 | ||
e46a2879 MK |
1237 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1238 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1239 | return ret; |
1240 | ||
5ad333eb | 1241 | ret = -EBUSY; |
08e552c6 | 1242 | |
c8244935 MG |
1243 | /* |
1244 | * To minimise LRU disruption, the caller can indicate that it only | |
1245 | * wants to isolate pages it will be able to operate on without | |
1246 | * blocking - clean pages for the most part. | |
1247 | * | |
1248 | * ISOLATE_CLEAN means that only clean pages should be isolated. This | |
1249 | * is used by reclaim when it is cannot write to backing storage | |
1250 | * | |
1251 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages | |
1252 | * that it is possible to migrate without blocking | |
1253 | */ | |
1254 | if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) { | |
1255 | /* All the caller can do on PageWriteback is block */ | |
1256 | if (PageWriteback(page)) | |
1257 | return ret; | |
1258 | ||
1259 | if (PageDirty(page)) { | |
1260 | struct address_space *mapping; | |
1261 | ||
1262 | /* ISOLATE_CLEAN means only clean pages */ | |
1263 | if (mode & ISOLATE_CLEAN) | |
1264 | return ret; | |
1265 | ||
1266 | /* | |
1267 | * Only pages without mappings or that have a | |
1268 | * ->migratepage callback are possible to migrate | |
1269 | * without blocking | |
1270 | */ | |
1271 | mapping = page_mapping(page); | |
1272 | if (mapping && !mapping->a_ops->migratepage) | |
1273 | return ret; | |
1274 | } | |
1275 | } | |
39deaf85 | 1276 | |
f80c0673 MK |
1277 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1278 | return ret; | |
1279 | ||
5ad333eb AW |
1280 | if (likely(get_page_unless_zero(page))) { |
1281 | /* | |
1282 | * Be careful not to clear PageLRU until after we're | |
1283 | * sure the page is not being freed elsewhere -- the | |
1284 | * page release code relies on it. | |
1285 | */ | |
1286 | ClearPageLRU(page); | |
1287 | ret = 0; | |
1288 | } | |
1289 | ||
1290 | return ret; | |
1291 | } | |
1292 | ||
1da177e4 LT |
1293 | /* |
1294 | * zone->lru_lock is heavily contended. Some of the functions that | |
1295 | * shrink the lists perform better by taking out a batch of pages | |
1296 | * and working on them outside the LRU lock. | |
1297 | * | |
1298 | * For pagecache intensive workloads, this function is the hottest | |
1299 | * spot in the kernel (apart from copy_*_user functions). | |
1300 | * | |
1301 | * Appropriate locks must be held before calling this function. | |
1302 | * | |
1303 | * @nr_to_scan: The number of pages to look through on the list. | |
5dc35979 | 1304 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1305 | * @dst: The temp list to put pages on to. |
f626012d | 1306 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1307 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1308 | * @mode: One of the LRU isolation modes |
3cb99451 | 1309 | * @lru: LRU list id for isolating |
1da177e4 LT |
1310 | * |
1311 | * returns how many pages were moved onto *@dst. | |
1312 | */ | |
69e05944 | 1313 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1314 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1315 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1316 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1317 | { |
75b00af7 | 1318 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1319 | unsigned long nr_taken = 0; |
c9b02d97 | 1320 | unsigned long scan; |
1da177e4 | 1321 | |
c9b02d97 | 1322 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb | 1323 | struct page *page; |
fa9add64 | 1324 | int nr_pages; |
5ad333eb | 1325 | |
1da177e4 LT |
1326 | page = lru_to_page(src); |
1327 | prefetchw_prev_lru_page(page, src, flags); | |
1328 | ||
309381fe | 1329 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1330 | |
f3fd4a61 | 1331 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1332 | case 0: |
fa9add64 HD |
1333 | nr_pages = hpage_nr_pages(page); |
1334 | mem_cgroup_update_lru_size(lruvec, lru, -nr_pages); | |
5ad333eb | 1335 | list_move(&page->lru, dst); |
fa9add64 | 1336 | nr_taken += nr_pages; |
5ad333eb AW |
1337 | break; |
1338 | ||
1339 | case -EBUSY: | |
1340 | /* else it is being freed elsewhere */ | |
1341 | list_move(&page->lru, src); | |
1342 | continue; | |
46453a6e | 1343 | |
5ad333eb AW |
1344 | default: |
1345 | BUG(); | |
1346 | } | |
1da177e4 LT |
1347 | } |
1348 | ||
f626012d | 1349 | *nr_scanned = scan; |
75b00af7 HD |
1350 | trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan, |
1351 | nr_taken, mode, is_file_lru(lru)); | |
1da177e4 LT |
1352 | return nr_taken; |
1353 | } | |
1354 | ||
62695a84 NP |
1355 | /** |
1356 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1357 | * @page: page to isolate from its LRU list | |
1358 | * | |
1359 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1360 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1361 | * | |
1362 | * Returns 0 if the page was removed from an LRU list. | |
1363 | * Returns -EBUSY if the page was not on an LRU list. | |
1364 | * | |
1365 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1366 | * the active list, it will have PageActive set. If it was found on |
1367 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1368 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1369 | * |
1370 | * The vmstat statistic corresponding to the list on which the page was | |
1371 | * found will be decremented. | |
1372 | * | |
1373 | * Restrictions: | |
1374 | * (1) Must be called with an elevated refcount on the page. This is a | |
1375 | * fundamentnal difference from isolate_lru_pages (which is called | |
1376 | * without a stable reference). | |
1377 | * (2) the lru_lock must not be held. | |
1378 | * (3) interrupts must be enabled. | |
1379 | */ | |
1380 | int isolate_lru_page(struct page *page) | |
1381 | { | |
1382 | int ret = -EBUSY; | |
1383 | ||
309381fe | 1384 | VM_BUG_ON_PAGE(!page_count(page), page); |
0c917313 | 1385 | |
62695a84 NP |
1386 | if (PageLRU(page)) { |
1387 | struct zone *zone = page_zone(page); | |
fa9add64 | 1388 | struct lruvec *lruvec; |
62695a84 NP |
1389 | |
1390 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 | 1391 | lruvec = mem_cgroup_page_lruvec(page, zone); |
0c917313 | 1392 | if (PageLRU(page)) { |
894bc310 | 1393 | int lru = page_lru(page); |
0c917313 | 1394 | get_page(page); |
62695a84 | 1395 | ClearPageLRU(page); |
fa9add64 HD |
1396 | del_page_from_lru_list(page, lruvec, lru); |
1397 | ret = 0; | |
62695a84 NP |
1398 | } |
1399 | spin_unlock_irq(&zone->lru_lock); | |
1400 | } | |
1401 | return ret; | |
1402 | } | |
1403 | ||
35cd7815 | 1404 | /* |
d37dd5dc FW |
1405 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1406 | * then get resheduled. When there are massive number of tasks doing page | |
1407 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1408 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1409 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 RR |
1410 | */ |
1411 | static int too_many_isolated(struct zone *zone, int file, | |
1412 | struct scan_control *sc) | |
1413 | { | |
1414 | unsigned long inactive, isolated; | |
1415 | ||
1416 | if (current_is_kswapd()) | |
1417 | return 0; | |
1418 | ||
89b5fae5 | 1419 | if (!global_reclaim(sc)) |
35cd7815 RR |
1420 | return 0; |
1421 | ||
1422 | if (file) { | |
1423 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1424 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1425 | } else { | |
1426 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1427 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1428 | } | |
1429 | ||
3cf23841 FW |
1430 | /* |
1431 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1432 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1433 | * deadlock. | |
1434 | */ | |
1435 | if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS) | |
1436 | inactive >>= 3; | |
1437 | ||
35cd7815 RR |
1438 | return isolated > inactive; |
1439 | } | |
1440 | ||
66635629 | 1441 | static noinline_for_stack void |
75b00af7 | 1442 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1443 | { |
27ac81d8 KK |
1444 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1445 | struct zone *zone = lruvec_zone(lruvec); | |
3f79768f | 1446 | LIST_HEAD(pages_to_free); |
66635629 | 1447 | |
66635629 MG |
1448 | /* |
1449 | * Put back any unfreeable pages. | |
1450 | */ | |
66635629 | 1451 | while (!list_empty(page_list)) { |
3f79768f | 1452 | struct page *page = lru_to_page(page_list); |
66635629 | 1453 | int lru; |
3f79768f | 1454 | |
309381fe | 1455 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1456 | list_del(&page->lru); |
39b5f29a | 1457 | if (unlikely(!page_evictable(page))) { |
66635629 MG |
1458 | spin_unlock_irq(&zone->lru_lock); |
1459 | putback_lru_page(page); | |
1460 | spin_lock_irq(&zone->lru_lock); | |
1461 | continue; | |
1462 | } | |
fa9add64 HD |
1463 | |
1464 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
1465 | ||
7a608572 | 1466 | SetPageLRU(page); |
66635629 | 1467 | lru = page_lru(page); |
fa9add64 HD |
1468 | add_page_to_lru_list(page, lruvec, lru); |
1469 | ||
66635629 MG |
1470 | if (is_active_lru(lru)) { |
1471 | int file = is_file_lru(lru); | |
9992af10 RR |
1472 | int numpages = hpage_nr_pages(page); |
1473 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1474 | } |
2bcf8879 HD |
1475 | if (put_page_testzero(page)) { |
1476 | __ClearPageLRU(page); | |
1477 | __ClearPageActive(page); | |
fa9add64 | 1478 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1479 | |
1480 | if (unlikely(PageCompound(page))) { | |
1481 | spin_unlock_irq(&zone->lru_lock); | |
747db954 | 1482 | mem_cgroup_uncharge(page); |
2bcf8879 HD |
1483 | (*get_compound_page_dtor(page))(page); |
1484 | spin_lock_irq(&zone->lru_lock); | |
1485 | } else | |
1486 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1487 | } |
1488 | } | |
66635629 | 1489 | |
3f79768f HD |
1490 | /* |
1491 | * To save our caller's stack, now use input list for pages to free. | |
1492 | */ | |
1493 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1494 | } |
1495 | ||
399ba0b9 N |
1496 | /* |
1497 | * If a kernel thread (such as nfsd for loop-back mounts) services | |
1498 | * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. | |
1499 | * In that case we should only throttle if the backing device it is | |
1500 | * writing to is congested. In other cases it is safe to throttle. | |
1501 | */ | |
1502 | static int current_may_throttle(void) | |
1503 | { | |
1504 | return !(current->flags & PF_LESS_THROTTLE) || | |
1505 | current->backing_dev_info == NULL || | |
1506 | bdi_write_congested(current->backing_dev_info); | |
1507 | } | |
1508 | ||
1da177e4 | 1509 | /* |
1742f19f AM |
1510 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1511 | * of reclaimed pages | |
1da177e4 | 1512 | */ |
66635629 | 1513 | static noinline_for_stack unsigned long |
1a93be0e | 1514 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1515 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1516 | { |
1517 | LIST_HEAD(page_list); | |
e247dbce | 1518 | unsigned long nr_scanned; |
05ff5137 | 1519 | unsigned long nr_reclaimed = 0; |
e247dbce | 1520 | unsigned long nr_taken; |
8e950282 MG |
1521 | unsigned long nr_dirty = 0; |
1522 | unsigned long nr_congested = 0; | |
e2be15f6 | 1523 | unsigned long nr_unqueued_dirty = 0; |
92df3a72 | 1524 | unsigned long nr_writeback = 0; |
b1a6f21e | 1525 | unsigned long nr_immediate = 0; |
f3fd4a61 | 1526 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1527 | int file = is_file_lru(lru); |
1a93be0e KK |
1528 | struct zone *zone = lruvec_zone(lruvec); |
1529 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; | |
78dc583d | 1530 | |
35cd7815 | 1531 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1532 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1533 | |
1534 | /* We are about to die and free our memory. Return now. */ | |
1535 | if (fatal_signal_pending(current)) | |
1536 | return SWAP_CLUSTER_MAX; | |
1537 | } | |
1538 | ||
1da177e4 | 1539 | lru_add_drain(); |
f80c0673 MK |
1540 | |
1541 | if (!sc->may_unmap) | |
61317289 | 1542 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1543 | if (!sc->may_writepage) |
61317289 | 1544 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1545 | |
1da177e4 | 1546 | spin_lock_irq(&zone->lru_lock); |
b35ea17b | 1547 | |
5dc35979 KK |
1548 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1549 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc KK |
1550 | |
1551 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); | |
1552 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); | |
1553 | ||
89b5fae5 | 1554 | if (global_reclaim(sc)) { |
0d5d823a | 1555 | __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned); |
e247dbce | 1556 | if (current_is_kswapd()) |
75b00af7 | 1557 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned); |
e247dbce | 1558 | else |
75b00af7 | 1559 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned); |
e247dbce | 1560 | } |
d563c050 | 1561 | spin_unlock_irq(&zone->lru_lock); |
b35ea17b | 1562 | |
d563c050 | 1563 | if (nr_taken == 0) |
66635629 | 1564 | return 0; |
5ad333eb | 1565 | |
02c6de8d | 1566 | nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP, |
8e950282 MG |
1567 | &nr_dirty, &nr_unqueued_dirty, &nr_congested, |
1568 | &nr_writeback, &nr_immediate, | |
1569 | false); | |
c661b078 | 1570 | |
3f79768f HD |
1571 | spin_lock_irq(&zone->lru_lock); |
1572 | ||
95d918fc | 1573 | reclaim_stat->recent_scanned[file] += nr_taken; |
d563c050 | 1574 | |
904249aa YH |
1575 | if (global_reclaim(sc)) { |
1576 | if (current_is_kswapd()) | |
1577 | __count_zone_vm_events(PGSTEAL_KSWAPD, zone, | |
1578 | nr_reclaimed); | |
1579 | else | |
1580 | __count_zone_vm_events(PGSTEAL_DIRECT, zone, | |
1581 | nr_reclaimed); | |
1582 | } | |
a74609fa | 1583 | |
27ac81d8 | 1584 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1585 | |
95d918fc | 1586 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f HD |
1587 | |
1588 | spin_unlock_irq(&zone->lru_lock); | |
1589 | ||
747db954 | 1590 | mem_cgroup_uncharge_list(&page_list); |
b745bc85 | 1591 | free_hot_cold_page_list(&page_list, true); |
e11da5b4 | 1592 | |
92df3a72 MG |
1593 | /* |
1594 | * If reclaim is isolating dirty pages under writeback, it implies | |
1595 | * that the long-lived page allocation rate is exceeding the page | |
1596 | * laundering rate. Either the global limits are not being effective | |
1597 | * at throttling processes due to the page distribution throughout | |
1598 | * zones or there is heavy usage of a slow backing device. The | |
1599 | * only option is to throttle from reclaim context which is not ideal | |
1600 | * as there is no guarantee the dirtying process is throttled in the | |
1601 | * same way balance_dirty_pages() manages. | |
1602 | * | |
8e950282 MG |
1603 | * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number |
1604 | * of pages under pages flagged for immediate reclaim and stall if any | |
1605 | * are encountered in the nr_immediate check below. | |
92df3a72 | 1606 | */ |
918fc718 | 1607 | if (nr_writeback && nr_writeback == nr_taken) |
57054651 | 1608 | set_bit(ZONE_WRITEBACK, &zone->flags); |
92df3a72 | 1609 | |
d43006d5 | 1610 | /* |
b1a6f21e MG |
1611 | * memcg will stall in page writeback so only consider forcibly |
1612 | * stalling for global reclaim | |
d43006d5 | 1613 | */ |
b1a6f21e | 1614 | if (global_reclaim(sc)) { |
8e950282 MG |
1615 | /* |
1616 | * Tag a zone as congested if all the dirty pages scanned were | |
1617 | * backed by a congested BDI and wait_iff_congested will stall. | |
1618 | */ | |
1619 | if (nr_dirty && nr_dirty == nr_congested) | |
57054651 | 1620 | set_bit(ZONE_CONGESTED, &zone->flags); |
8e950282 | 1621 | |
b1a6f21e MG |
1622 | /* |
1623 | * If dirty pages are scanned that are not queued for IO, it | |
1624 | * implies that flushers are not keeping up. In this case, flag | |
57054651 JW |
1625 | * the zone ZONE_DIRTY and kswapd will start writing pages from |
1626 | * reclaim context. | |
b1a6f21e MG |
1627 | */ |
1628 | if (nr_unqueued_dirty == nr_taken) | |
57054651 | 1629 | set_bit(ZONE_DIRTY, &zone->flags); |
b1a6f21e MG |
1630 | |
1631 | /* | |
b738d764 LT |
1632 | * If kswapd scans pages marked marked for immediate |
1633 | * reclaim and under writeback (nr_immediate), it implies | |
1634 | * that pages are cycling through the LRU faster than | |
b1a6f21e MG |
1635 | * they are written so also forcibly stall. |
1636 | */ | |
b738d764 | 1637 | if (nr_immediate && current_may_throttle()) |
b1a6f21e | 1638 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
e2be15f6 | 1639 | } |
d43006d5 | 1640 | |
8e950282 MG |
1641 | /* |
1642 | * Stall direct reclaim for IO completions if underlying BDIs or zone | |
1643 | * is congested. Allow kswapd to continue until it starts encountering | |
1644 | * unqueued dirty pages or cycling through the LRU too quickly. | |
1645 | */ | |
399ba0b9 N |
1646 | if (!sc->hibernation_mode && !current_is_kswapd() && |
1647 | current_may_throttle()) | |
8e950282 MG |
1648 | wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); |
1649 | ||
e11da5b4 MG |
1650 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, |
1651 | zone_idx(zone), | |
1652 | nr_scanned, nr_reclaimed, | |
9e3b2f8c | 1653 | sc->priority, |
23b9da55 | 1654 | trace_shrink_flags(file)); |
05ff5137 | 1655 | return nr_reclaimed; |
1da177e4 LT |
1656 | } |
1657 | ||
1658 | /* | |
1659 | * This moves pages from the active list to the inactive list. | |
1660 | * | |
1661 | * We move them the other way if the page is referenced by one or more | |
1662 | * processes, from rmap. | |
1663 | * | |
1664 | * If the pages are mostly unmapped, the processing is fast and it is | |
1665 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1666 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1667 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1668 | * this, so instead we remove the pages from the LRU while processing them. | |
1669 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1670 | * nobody will play with that bit on a non-LRU page. | |
1671 | * | |
1672 | * The downside is that we have to touch page->_count against each page. | |
1673 | * But we had to alter page->flags anyway. | |
1674 | */ | |
1cfb419b | 1675 | |
fa9add64 | 1676 | static void move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 1677 | struct list_head *list, |
2bcf8879 | 1678 | struct list_head *pages_to_free, |
3eb4140f WF |
1679 | enum lru_list lru) |
1680 | { | |
fa9add64 | 1681 | struct zone *zone = lruvec_zone(lruvec); |
3eb4140f | 1682 | unsigned long pgmoved = 0; |
3eb4140f | 1683 | struct page *page; |
fa9add64 | 1684 | int nr_pages; |
3eb4140f | 1685 | |
3eb4140f WF |
1686 | while (!list_empty(list)) { |
1687 | page = lru_to_page(list); | |
fa9add64 | 1688 | lruvec = mem_cgroup_page_lruvec(page, zone); |
3eb4140f | 1689 | |
309381fe | 1690 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
1691 | SetPageLRU(page); |
1692 | ||
fa9add64 HD |
1693 | nr_pages = hpage_nr_pages(page); |
1694 | mem_cgroup_update_lru_size(lruvec, lru, nr_pages); | |
925b7673 | 1695 | list_move(&page->lru, &lruvec->lists[lru]); |
fa9add64 | 1696 | pgmoved += nr_pages; |
3eb4140f | 1697 | |
2bcf8879 HD |
1698 | if (put_page_testzero(page)) { |
1699 | __ClearPageLRU(page); | |
1700 | __ClearPageActive(page); | |
fa9add64 | 1701 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1702 | |
1703 | if (unlikely(PageCompound(page))) { | |
1704 | spin_unlock_irq(&zone->lru_lock); | |
747db954 | 1705 | mem_cgroup_uncharge(page); |
2bcf8879 HD |
1706 | (*get_compound_page_dtor(page))(page); |
1707 | spin_lock_irq(&zone->lru_lock); | |
1708 | } else | |
1709 | list_add(&page->lru, pages_to_free); | |
3eb4140f WF |
1710 | } |
1711 | } | |
1712 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1713 | if (!is_active_lru(lru)) | |
1714 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1715 | } | |
1cfb419b | 1716 | |
f626012d | 1717 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 1718 | struct lruvec *lruvec, |
f16015fb | 1719 | struct scan_control *sc, |
9e3b2f8c | 1720 | enum lru_list lru) |
1da177e4 | 1721 | { |
44c241f1 | 1722 | unsigned long nr_taken; |
f626012d | 1723 | unsigned long nr_scanned; |
6fe6b7e3 | 1724 | unsigned long vm_flags; |
1da177e4 | 1725 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1726 | LIST_HEAD(l_active); |
b69408e8 | 1727 | LIST_HEAD(l_inactive); |
1da177e4 | 1728 | struct page *page; |
1a93be0e | 1729 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
44c241f1 | 1730 | unsigned long nr_rotated = 0; |
f3fd4a61 | 1731 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1732 | int file = is_file_lru(lru); |
1a93be0e | 1733 | struct zone *zone = lruvec_zone(lruvec); |
1da177e4 LT |
1734 | |
1735 | lru_add_drain(); | |
f80c0673 MK |
1736 | |
1737 | if (!sc->may_unmap) | |
61317289 | 1738 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1739 | if (!sc->may_writepage) |
61317289 | 1740 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1741 | |
1da177e4 | 1742 | spin_lock_irq(&zone->lru_lock); |
925b7673 | 1743 | |
5dc35979 KK |
1744 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
1745 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 1746 | if (global_reclaim(sc)) |
0d5d823a | 1747 | __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned); |
89b5fae5 | 1748 | |
b7c46d15 | 1749 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1750 | |
f626012d | 1751 | __count_zone_vm_events(PGREFILL, zone, nr_scanned); |
3cb99451 | 1752 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); |
a731286d | 1753 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1754 | spin_unlock_irq(&zone->lru_lock); |
1755 | ||
1da177e4 LT |
1756 | while (!list_empty(&l_hold)) { |
1757 | cond_resched(); | |
1758 | page = lru_to_page(&l_hold); | |
1759 | list_del(&page->lru); | |
7e9cd484 | 1760 | |
39b5f29a | 1761 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
1762 | putback_lru_page(page); |
1763 | continue; | |
1764 | } | |
1765 | ||
cc715d99 MG |
1766 | if (unlikely(buffer_heads_over_limit)) { |
1767 | if (page_has_private(page) && trylock_page(page)) { | |
1768 | if (page_has_private(page)) | |
1769 | try_to_release_page(page, 0); | |
1770 | unlock_page(page); | |
1771 | } | |
1772 | } | |
1773 | ||
c3ac9a8a JW |
1774 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
1775 | &vm_flags)) { | |
9992af10 | 1776 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1777 | /* |
1778 | * Identify referenced, file-backed active pages and | |
1779 | * give them one more trip around the active list. So | |
1780 | * that executable code get better chances to stay in | |
1781 | * memory under moderate memory pressure. Anon pages | |
1782 | * are not likely to be evicted by use-once streaming | |
1783 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1784 | * so we ignore them here. | |
1785 | */ | |
41e20983 | 1786 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1787 | list_add(&page->lru, &l_active); |
1788 | continue; | |
1789 | } | |
1790 | } | |
7e9cd484 | 1791 | |
5205e56e | 1792 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1793 | list_add(&page->lru, &l_inactive); |
1794 | } | |
1795 | ||
b555749a | 1796 | /* |
8cab4754 | 1797 | * Move pages back to the lru list. |
b555749a | 1798 | */ |
2a1dc509 | 1799 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1800 | /* |
8cab4754 WF |
1801 | * Count referenced pages from currently used mappings as rotated, |
1802 | * even though only some of them are actually re-activated. This | |
1803 | * helps balance scan pressure between file and anonymous pages in | |
7c0db9e9 | 1804 | * get_scan_count. |
7e9cd484 | 1805 | */ |
b7c46d15 | 1806 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1807 | |
fa9add64 HD |
1808 | move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
1809 | move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
a731286d | 1810 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1811 | spin_unlock_irq(&zone->lru_lock); |
2bcf8879 | 1812 | |
747db954 | 1813 | mem_cgroup_uncharge_list(&l_hold); |
b745bc85 | 1814 | free_hot_cold_page_list(&l_hold, true); |
1da177e4 LT |
1815 | } |
1816 | ||
74e3f3c3 | 1817 | #ifdef CONFIG_SWAP |
14797e23 | 1818 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1819 | { |
1820 | unsigned long active, inactive; | |
1821 | ||
1822 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1823 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1824 | ||
1825 | if (inactive * zone->inactive_ratio < active) | |
1826 | return 1; | |
1827 | ||
1828 | return 0; | |
1829 | } | |
1830 | ||
14797e23 KM |
1831 | /** |
1832 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
c56d5c7d | 1833 | * @lruvec: LRU vector to check |
14797e23 KM |
1834 | * |
1835 | * Returns true if the zone does not have enough inactive anon pages, | |
1836 | * meaning some active anon pages need to be deactivated. | |
1837 | */ | |
c56d5c7d | 1838 | static int inactive_anon_is_low(struct lruvec *lruvec) |
14797e23 | 1839 | { |
74e3f3c3 MK |
1840 | /* |
1841 | * If we don't have swap space, anonymous page deactivation | |
1842 | * is pointless. | |
1843 | */ | |
1844 | if (!total_swap_pages) | |
1845 | return 0; | |
1846 | ||
c3c787e8 | 1847 | if (!mem_cgroup_disabled()) |
c56d5c7d | 1848 | return mem_cgroup_inactive_anon_is_low(lruvec); |
f16015fb | 1849 | |
c56d5c7d | 1850 | return inactive_anon_is_low_global(lruvec_zone(lruvec)); |
14797e23 | 1851 | } |
74e3f3c3 | 1852 | #else |
c56d5c7d | 1853 | static inline int inactive_anon_is_low(struct lruvec *lruvec) |
74e3f3c3 MK |
1854 | { |
1855 | return 0; | |
1856 | } | |
1857 | #endif | |
14797e23 | 1858 | |
56e49d21 RR |
1859 | /** |
1860 | * inactive_file_is_low - check if file pages need to be deactivated | |
c56d5c7d | 1861 | * @lruvec: LRU vector to check |
56e49d21 RR |
1862 | * |
1863 | * When the system is doing streaming IO, memory pressure here | |
1864 | * ensures that active file pages get deactivated, until more | |
1865 | * than half of the file pages are on the inactive list. | |
1866 | * | |
1867 | * Once we get to that situation, protect the system's working | |
1868 | * set from being evicted by disabling active file page aging. | |
1869 | * | |
1870 | * This uses a different ratio than the anonymous pages, because | |
1871 | * the page cache uses a use-once replacement algorithm. | |
1872 | */ | |
c56d5c7d | 1873 | static int inactive_file_is_low(struct lruvec *lruvec) |
56e49d21 | 1874 | { |
e3790144 JW |
1875 | unsigned long inactive; |
1876 | unsigned long active; | |
1877 | ||
1878 | inactive = get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
1879 | active = get_lru_size(lruvec, LRU_ACTIVE_FILE); | |
56e49d21 | 1880 | |
e3790144 | 1881 | return active > inactive; |
56e49d21 RR |
1882 | } |
1883 | ||
75b00af7 | 1884 | static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru) |
b39415b2 | 1885 | { |
75b00af7 | 1886 | if (is_file_lru(lru)) |
c56d5c7d | 1887 | return inactive_file_is_low(lruvec); |
b39415b2 | 1888 | else |
c56d5c7d | 1889 | return inactive_anon_is_low(lruvec); |
b39415b2 RR |
1890 | } |
1891 | ||
4f98a2fe | 1892 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
1a93be0e | 1893 | struct lruvec *lruvec, struct scan_control *sc) |
b69408e8 | 1894 | { |
b39415b2 | 1895 | if (is_active_lru(lru)) { |
75b00af7 | 1896 | if (inactive_list_is_low(lruvec, lru)) |
1a93be0e | 1897 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
1898 | return 0; |
1899 | } | |
1900 | ||
1a93be0e | 1901 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
1902 | } |
1903 | ||
9a265114 JW |
1904 | enum scan_balance { |
1905 | SCAN_EQUAL, | |
1906 | SCAN_FRACT, | |
1907 | SCAN_ANON, | |
1908 | SCAN_FILE, | |
1909 | }; | |
1910 | ||
4f98a2fe RR |
1911 | /* |
1912 | * Determine how aggressively the anon and file LRU lists should be | |
1913 | * scanned. The relative value of each set of LRU lists is determined | |
1914 | * by looking at the fraction of the pages scanned we did rotate back | |
1915 | * onto the active list instead of evict. | |
1916 | * | |
be7bd59d WL |
1917 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
1918 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 1919 | */ |
02695175 | 1920 | static void get_scan_count(struct lruvec *lruvec, int swappiness, |
6b4f7799 JW |
1921 | struct scan_control *sc, unsigned long *nr, |
1922 | unsigned long *lru_pages) | |
4f98a2fe | 1923 | { |
9a265114 JW |
1924 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1925 | u64 fraction[2]; | |
1926 | u64 denominator = 0; /* gcc */ | |
1927 | struct zone *zone = lruvec_zone(lruvec); | |
4f98a2fe | 1928 | unsigned long anon_prio, file_prio; |
9a265114 | 1929 | enum scan_balance scan_balance; |
0bf1457f | 1930 | unsigned long anon, file; |
9a265114 | 1931 | bool force_scan = false; |
4f98a2fe | 1932 | unsigned long ap, fp; |
4111304d | 1933 | enum lru_list lru; |
6f04f48d SS |
1934 | bool some_scanned; |
1935 | int pass; | |
246e87a9 | 1936 | |
f11c0ca5 JW |
1937 | /* |
1938 | * If the zone or memcg is small, nr[l] can be 0. This | |
1939 | * results in no scanning on this priority and a potential | |
1940 | * priority drop. Global direct reclaim can go to the next | |
1941 | * zone and tends to have no problems. Global kswapd is for | |
1942 | * zone balancing and it needs to scan a minimum amount. When | |
1943 | * reclaiming for a memcg, a priority drop can cause high | |
1944 | * latencies, so it's better to scan a minimum amount there as | |
1945 | * well. | |
1946 | */ | |
90cbc250 VD |
1947 | if (current_is_kswapd()) { |
1948 | if (!zone_reclaimable(zone)) | |
1949 | force_scan = true; | |
1950 | if (!mem_cgroup_lruvec_online(lruvec)) | |
1951 | force_scan = true; | |
1952 | } | |
89b5fae5 | 1953 | if (!global_reclaim(sc)) |
a4d3e9e7 | 1954 | force_scan = true; |
76a33fc3 SL |
1955 | |
1956 | /* If we have no swap space, do not bother scanning anon pages. */ | |
ec8acf20 | 1957 | if (!sc->may_swap || (get_nr_swap_pages() <= 0)) { |
9a265114 | 1958 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
1959 | goto out; |
1960 | } | |
4f98a2fe | 1961 | |
10316b31 JW |
1962 | /* |
1963 | * Global reclaim will swap to prevent OOM even with no | |
1964 | * swappiness, but memcg users want to use this knob to | |
1965 | * disable swapping for individual groups completely when | |
1966 | * using the memory controller's swap limit feature would be | |
1967 | * too expensive. | |
1968 | */ | |
02695175 | 1969 | if (!global_reclaim(sc) && !swappiness) { |
9a265114 | 1970 | scan_balance = SCAN_FILE; |
10316b31 JW |
1971 | goto out; |
1972 | } | |
1973 | ||
1974 | /* | |
1975 | * Do not apply any pressure balancing cleverness when the | |
1976 | * system is close to OOM, scan both anon and file equally | |
1977 | * (unless the swappiness setting disagrees with swapping). | |
1978 | */ | |
02695175 | 1979 | if (!sc->priority && swappiness) { |
9a265114 | 1980 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
1981 | goto out; |
1982 | } | |
1983 | ||
62376251 JW |
1984 | /* |
1985 | * Prevent the reclaimer from falling into the cache trap: as | |
1986 | * cache pages start out inactive, every cache fault will tip | |
1987 | * the scan balance towards the file LRU. And as the file LRU | |
1988 | * shrinks, so does the window for rotation from references. | |
1989 | * This means we have a runaway feedback loop where a tiny | |
1990 | * thrashing file LRU becomes infinitely more attractive than | |
1991 | * anon pages. Try to detect this based on file LRU size. | |
1992 | */ | |
1993 | if (global_reclaim(sc)) { | |
2ab051e1 JM |
1994 | unsigned long zonefile; |
1995 | unsigned long zonefree; | |
1996 | ||
1997 | zonefree = zone_page_state(zone, NR_FREE_PAGES); | |
1998 | zonefile = zone_page_state(zone, NR_ACTIVE_FILE) + | |
1999 | zone_page_state(zone, NR_INACTIVE_FILE); | |
62376251 | 2000 | |
2ab051e1 | 2001 | if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) { |
62376251 JW |
2002 | scan_balance = SCAN_ANON; |
2003 | goto out; | |
2004 | } | |
2005 | } | |
2006 | ||
7c5bd705 JW |
2007 | /* |
2008 | * There is enough inactive page cache, do not reclaim | |
2009 | * anything from the anonymous working set right now. | |
2010 | */ | |
2011 | if (!inactive_file_is_low(lruvec)) { | |
9a265114 | 2012 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
2013 | goto out; |
2014 | } | |
2015 | ||
9a265114 JW |
2016 | scan_balance = SCAN_FRACT; |
2017 | ||
58c37f6e KM |
2018 | /* |
2019 | * With swappiness at 100, anonymous and file have the same priority. | |
2020 | * This scanning priority is essentially the inverse of IO cost. | |
2021 | */ | |
02695175 | 2022 | anon_prio = swappiness; |
75b00af7 | 2023 | file_prio = 200 - anon_prio; |
58c37f6e | 2024 | |
4f98a2fe RR |
2025 | /* |
2026 | * OK, so we have swap space and a fair amount of page cache | |
2027 | * pages. We use the recently rotated / recently scanned | |
2028 | * ratios to determine how valuable each cache is. | |
2029 | * | |
2030 | * Because workloads change over time (and to avoid overflow) | |
2031 | * we keep these statistics as a floating average, which ends | |
2032 | * up weighing recent references more than old ones. | |
2033 | * | |
2034 | * anon in [0], file in [1] | |
2035 | */ | |
2ab051e1 JM |
2036 | |
2037 | anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) + | |
2038 | get_lru_size(lruvec, LRU_INACTIVE_ANON); | |
2039 | file = get_lru_size(lruvec, LRU_ACTIVE_FILE) + | |
2040 | get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
2041 | ||
90126375 | 2042 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 2043 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
2044 | reclaim_stat->recent_scanned[0] /= 2; |
2045 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
2046 | } |
2047 | ||
6e901571 | 2048 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
2049 | reclaim_stat->recent_scanned[1] /= 2; |
2050 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
2051 | } |
2052 | ||
4f98a2fe | 2053 | /* |
00d8089c RR |
2054 | * The amount of pressure on anon vs file pages is inversely |
2055 | * proportional to the fraction of recently scanned pages on | |
2056 | * each list that were recently referenced and in active use. | |
4f98a2fe | 2057 | */ |
fe35004f | 2058 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 2059 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 2060 | |
fe35004f | 2061 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 2062 | fp /= reclaim_stat->recent_rotated[1] + 1; |
90126375 | 2063 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 2064 | |
76a33fc3 SL |
2065 | fraction[0] = ap; |
2066 | fraction[1] = fp; | |
2067 | denominator = ap + fp + 1; | |
2068 | out: | |
6f04f48d SS |
2069 | some_scanned = false; |
2070 | /* Only use force_scan on second pass. */ | |
2071 | for (pass = 0; !some_scanned && pass < 2; pass++) { | |
6b4f7799 | 2072 | *lru_pages = 0; |
6f04f48d SS |
2073 | for_each_evictable_lru(lru) { |
2074 | int file = is_file_lru(lru); | |
2075 | unsigned long size; | |
2076 | unsigned long scan; | |
6e08a369 | 2077 | |
6f04f48d SS |
2078 | size = get_lru_size(lruvec, lru); |
2079 | scan = size >> sc->priority; | |
9a265114 | 2080 | |
6f04f48d SS |
2081 | if (!scan && pass && force_scan) |
2082 | scan = min(size, SWAP_CLUSTER_MAX); | |
9a265114 | 2083 | |
6f04f48d SS |
2084 | switch (scan_balance) { |
2085 | case SCAN_EQUAL: | |
2086 | /* Scan lists relative to size */ | |
2087 | break; | |
2088 | case SCAN_FRACT: | |
2089 | /* | |
2090 | * Scan types proportional to swappiness and | |
2091 | * their relative recent reclaim efficiency. | |
2092 | */ | |
2093 | scan = div64_u64(scan * fraction[file], | |
2094 | denominator); | |
2095 | break; | |
2096 | case SCAN_FILE: | |
2097 | case SCAN_ANON: | |
2098 | /* Scan one type exclusively */ | |
6b4f7799 JW |
2099 | if ((scan_balance == SCAN_FILE) != file) { |
2100 | size = 0; | |
6f04f48d | 2101 | scan = 0; |
6b4f7799 | 2102 | } |
6f04f48d SS |
2103 | break; |
2104 | default: | |
2105 | /* Look ma, no brain */ | |
2106 | BUG(); | |
2107 | } | |
6b4f7799 JW |
2108 | |
2109 | *lru_pages += size; | |
6f04f48d | 2110 | nr[lru] = scan; |
6b4f7799 | 2111 | |
9a265114 | 2112 | /* |
6f04f48d SS |
2113 | * Skip the second pass and don't force_scan, |
2114 | * if we found something to scan. | |
9a265114 | 2115 | */ |
6f04f48d | 2116 | some_scanned |= !!scan; |
9a265114 | 2117 | } |
76a33fc3 | 2118 | } |
6e08a369 | 2119 | } |
4f98a2fe | 2120 | |
9b4f98cd JW |
2121 | /* |
2122 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
2123 | */ | |
02695175 | 2124 | static void shrink_lruvec(struct lruvec *lruvec, int swappiness, |
6b4f7799 | 2125 | struct scan_control *sc, unsigned long *lru_pages) |
9b4f98cd JW |
2126 | { |
2127 | unsigned long nr[NR_LRU_LISTS]; | |
e82e0561 | 2128 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2129 | unsigned long nr_to_scan; |
2130 | enum lru_list lru; | |
2131 | unsigned long nr_reclaimed = 0; | |
2132 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2133 | struct blk_plug plug; | |
1a501907 | 2134 | bool scan_adjusted; |
9b4f98cd | 2135 | |
6b4f7799 | 2136 | get_scan_count(lruvec, swappiness, sc, nr, lru_pages); |
9b4f98cd | 2137 | |
e82e0561 MG |
2138 | /* Record the original scan target for proportional adjustments later */ |
2139 | memcpy(targets, nr, sizeof(nr)); | |
2140 | ||
1a501907 MG |
2141 | /* |
2142 | * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal | |
2143 | * event that can occur when there is little memory pressure e.g. | |
2144 | * multiple streaming readers/writers. Hence, we do not abort scanning | |
2145 | * when the requested number of pages are reclaimed when scanning at | |
2146 | * DEF_PRIORITY on the assumption that the fact we are direct | |
2147 | * reclaiming implies that kswapd is not keeping up and it is best to | |
2148 | * do a batch of work at once. For memcg reclaim one check is made to | |
2149 | * abort proportional reclaim if either the file or anon lru has already | |
2150 | * dropped to zero at the first pass. | |
2151 | */ | |
2152 | scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && | |
2153 | sc->priority == DEF_PRIORITY); | |
2154 | ||
9b4f98cd JW |
2155 | blk_start_plug(&plug); |
2156 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2157 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2158 | unsigned long nr_anon, nr_file, percentage; |
2159 | unsigned long nr_scanned; | |
2160 | ||
9b4f98cd JW |
2161 | for_each_evictable_lru(lru) { |
2162 | if (nr[lru]) { | |
2163 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2164 | nr[lru] -= nr_to_scan; | |
2165 | ||
2166 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
2167 | lruvec, sc); | |
2168 | } | |
2169 | } | |
e82e0561 MG |
2170 | |
2171 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) | |
2172 | continue; | |
2173 | ||
e82e0561 MG |
2174 | /* |
2175 | * For kswapd and memcg, reclaim at least the number of pages | |
1a501907 | 2176 | * requested. Ensure that the anon and file LRUs are scanned |
e82e0561 MG |
2177 | * proportionally what was requested by get_scan_count(). We |
2178 | * stop reclaiming one LRU and reduce the amount scanning | |
2179 | * proportional to the original scan target. | |
2180 | */ | |
2181 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2182 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2183 | ||
1a501907 MG |
2184 | /* |
2185 | * It's just vindictive to attack the larger once the smaller | |
2186 | * has gone to zero. And given the way we stop scanning the | |
2187 | * smaller below, this makes sure that we only make one nudge | |
2188 | * towards proportionality once we've got nr_to_reclaim. | |
2189 | */ | |
2190 | if (!nr_file || !nr_anon) | |
2191 | break; | |
2192 | ||
e82e0561 MG |
2193 | if (nr_file > nr_anon) { |
2194 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2195 | targets[LRU_ACTIVE_ANON] + 1; | |
2196 | lru = LRU_BASE; | |
2197 | percentage = nr_anon * 100 / scan_target; | |
2198 | } else { | |
2199 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2200 | targets[LRU_ACTIVE_FILE] + 1; | |
2201 | lru = LRU_FILE; | |
2202 | percentage = nr_file * 100 / scan_target; | |
2203 | } | |
2204 | ||
2205 | /* Stop scanning the smaller of the LRU */ | |
2206 | nr[lru] = 0; | |
2207 | nr[lru + LRU_ACTIVE] = 0; | |
2208 | ||
2209 | /* | |
2210 | * Recalculate the other LRU scan count based on its original | |
2211 | * scan target and the percentage scanning already complete | |
2212 | */ | |
2213 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2214 | nr_scanned = targets[lru] - nr[lru]; | |
2215 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2216 | nr[lru] -= min(nr[lru], nr_scanned); | |
2217 | ||
2218 | lru += LRU_ACTIVE; | |
2219 | nr_scanned = targets[lru] - nr[lru]; | |
2220 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2221 | nr[lru] -= min(nr[lru], nr_scanned); | |
2222 | ||
2223 | scan_adjusted = true; | |
9b4f98cd JW |
2224 | } |
2225 | blk_finish_plug(&plug); | |
2226 | sc->nr_reclaimed += nr_reclaimed; | |
2227 | ||
2228 | /* | |
2229 | * Even if we did not try to evict anon pages at all, we want to | |
2230 | * rebalance the anon lru active/inactive ratio. | |
2231 | */ | |
2232 | if (inactive_anon_is_low(lruvec)) | |
2233 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, | |
2234 | sc, LRU_ACTIVE_ANON); | |
2235 | ||
2236 | throttle_vm_writeout(sc->gfp_mask); | |
2237 | } | |
2238 | ||
23b9da55 | 2239 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2240 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2241 | { |
d84da3f9 | 2242 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2243 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2244 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2245 | return true; |
2246 | ||
2247 | return false; | |
2248 | } | |
2249 | ||
3e7d3449 | 2250 | /* |
23b9da55 MG |
2251 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2252 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2253 | * true if more pages should be reclaimed such that when the page allocator | |
2254 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2255 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2256 | */ |
9b4f98cd | 2257 | static inline bool should_continue_reclaim(struct zone *zone, |
3e7d3449 MG |
2258 | unsigned long nr_reclaimed, |
2259 | unsigned long nr_scanned, | |
2260 | struct scan_control *sc) | |
2261 | { | |
2262 | unsigned long pages_for_compaction; | |
2263 | unsigned long inactive_lru_pages; | |
2264 | ||
2265 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2266 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2267 | return false; |
2268 | ||
2876592f MG |
2269 | /* Consider stopping depending on scan and reclaim activity */ |
2270 | if (sc->gfp_mask & __GFP_REPEAT) { | |
2271 | /* | |
2272 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
2273 | * full LRU list has been scanned and we are still failing | |
2274 | * to reclaim pages. This full LRU scan is potentially | |
2275 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
2276 | */ | |
2277 | if (!nr_reclaimed && !nr_scanned) | |
2278 | return false; | |
2279 | } else { | |
2280 | /* | |
2281 | * For non-__GFP_REPEAT allocations which can presumably | |
2282 | * fail without consequence, stop if we failed to reclaim | |
2283 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2284 | * pages that were scanned. This will return to the | |
2285 | * caller faster at the risk reclaim/compaction and | |
2286 | * the resulting allocation attempt fails | |
2287 | */ | |
2288 | if (!nr_reclaimed) | |
2289 | return false; | |
2290 | } | |
3e7d3449 MG |
2291 | |
2292 | /* | |
2293 | * If we have not reclaimed enough pages for compaction and the | |
2294 | * inactive lists are large enough, continue reclaiming | |
2295 | */ | |
2296 | pages_for_compaction = (2UL << sc->order); | |
9b4f98cd | 2297 | inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE); |
ec8acf20 | 2298 | if (get_nr_swap_pages() > 0) |
9b4f98cd | 2299 | inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON); |
3e7d3449 MG |
2300 | if (sc->nr_reclaimed < pages_for_compaction && |
2301 | inactive_lru_pages > pages_for_compaction) | |
2302 | return true; | |
2303 | ||
2304 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
ebff3980 | 2305 | switch (compaction_suitable(zone, sc->order, 0, 0)) { |
3e7d3449 MG |
2306 | case COMPACT_PARTIAL: |
2307 | case COMPACT_CONTINUE: | |
2308 | return false; | |
2309 | default: | |
2310 | return true; | |
2311 | } | |
2312 | } | |
2313 | ||
6b4f7799 JW |
2314 | static bool shrink_zone(struct zone *zone, struct scan_control *sc, |
2315 | bool is_classzone) | |
1da177e4 | 2316 | { |
cb731d6c | 2317 | struct reclaim_state *reclaim_state = current->reclaim_state; |
f0fdc5e8 | 2318 | unsigned long nr_reclaimed, nr_scanned; |
2344d7e4 | 2319 | bool reclaimable = false; |
1da177e4 | 2320 | |
9b4f98cd JW |
2321 | do { |
2322 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2323 | struct mem_cgroup_reclaim_cookie reclaim = { | |
2324 | .zone = zone, | |
2325 | .priority = sc->priority, | |
2326 | }; | |
6b4f7799 | 2327 | unsigned long zone_lru_pages = 0; |
694fbc0f | 2328 | struct mem_cgroup *memcg; |
3e7d3449 | 2329 | |
9b4f98cd JW |
2330 | nr_reclaimed = sc->nr_reclaimed; |
2331 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2332 | |
694fbc0f AM |
2333 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2334 | do { | |
6b4f7799 | 2335 | unsigned long lru_pages; |
cb731d6c | 2336 | unsigned long scanned; |
9b4f98cd | 2337 | struct lruvec *lruvec; |
02695175 | 2338 | int swappiness; |
5660048c | 2339 | |
241994ed JW |
2340 | if (mem_cgroup_low(root, memcg)) { |
2341 | if (!sc->may_thrash) | |
2342 | continue; | |
2343 | mem_cgroup_events(memcg, MEMCG_LOW, 1); | |
2344 | } | |
2345 | ||
9b4f98cd | 2346 | lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
02695175 | 2347 | swappiness = mem_cgroup_swappiness(memcg); |
cb731d6c | 2348 | scanned = sc->nr_scanned; |
f9be23d6 | 2349 | |
6b4f7799 JW |
2350 | shrink_lruvec(lruvec, swappiness, sc, &lru_pages); |
2351 | zone_lru_pages += lru_pages; | |
f16015fb | 2352 | |
cb731d6c VD |
2353 | if (memcg && is_classzone) |
2354 | shrink_slab(sc->gfp_mask, zone_to_nid(zone), | |
2355 | memcg, sc->nr_scanned - scanned, | |
2356 | lru_pages); | |
2357 | ||
9b4f98cd | 2358 | /* |
a394cb8e MH |
2359 | * Direct reclaim and kswapd have to scan all memory |
2360 | * cgroups to fulfill the overall scan target for the | |
9b4f98cd | 2361 | * zone. |
a394cb8e MH |
2362 | * |
2363 | * Limit reclaim, on the other hand, only cares about | |
2364 | * nr_to_reclaim pages to be reclaimed and it will | |
2365 | * retry with decreasing priority if one round over the | |
2366 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2367 | */ |
a394cb8e MH |
2368 | if (!global_reclaim(sc) && |
2369 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2370 | mem_cgroup_iter_break(root, memcg); |
2371 | break; | |
2372 | } | |
241994ed | 2373 | } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); |
70ddf637 | 2374 | |
6b4f7799 JW |
2375 | /* |
2376 | * Shrink the slab caches in the same proportion that | |
2377 | * the eligible LRU pages were scanned. | |
2378 | */ | |
cb731d6c VD |
2379 | if (global_reclaim(sc) && is_classzone) |
2380 | shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL, | |
2381 | sc->nr_scanned - nr_scanned, | |
2382 | zone_lru_pages); | |
2383 | ||
2384 | if (reclaim_state) { | |
2385 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; | |
2386 | reclaim_state->reclaimed_slab = 0; | |
6b4f7799 JW |
2387 | } |
2388 | ||
70ddf637 AV |
2389 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, |
2390 | sc->nr_scanned - nr_scanned, | |
2391 | sc->nr_reclaimed - nr_reclaimed); | |
2392 | ||
2344d7e4 JW |
2393 | if (sc->nr_reclaimed - nr_reclaimed) |
2394 | reclaimable = true; | |
2395 | ||
9b4f98cd JW |
2396 | } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed, |
2397 | sc->nr_scanned - nr_scanned, sc)); | |
2344d7e4 JW |
2398 | |
2399 | return reclaimable; | |
f16015fb JW |
2400 | } |
2401 | ||
53853e2d VB |
2402 | /* |
2403 | * Returns true if compaction should go ahead for a high-order request, or | |
2404 | * the high-order allocation would succeed without compaction. | |
2405 | */ | |
0b06496a | 2406 | static inline bool compaction_ready(struct zone *zone, int order) |
fe4b1b24 MG |
2407 | { |
2408 | unsigned long balance_gap, watermark; | |
2409 | bool watermark_ok; | |
2410 | ||
fe4b1b24 MG |
2411 | /* |
2412 | * Compaction takes time to run and there are potentially other | |
2413 | * callers using the pages just freed. Continue reclaiming until | |
2414 | * there is a buffer of free pages available to give compaction | |
2415 | * a reasonable chance of completing and allocating the page | |
2416 | */ | |
4be89a34 JZ |
2417 | balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP( |
2418 | zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO)); | |
0b06496a | 2419 | watermark = high_wmark_pages(zone) + balance_gap + (2UL << order); |
fe4b1b24 MG |
2420 | watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0); |
2421 | ||
2422 | /* | |
2423 | * If compaction is deferred, reclaim up to a point where | |
2424 | * compaction will have a chance of success when re-enabled | |
2425 | */ | |
0b06496a | 2426 | if (compaction_deferred(zone, order)) |
fe4b1b24 MG |
2427 | return watermark_ok; |
2428 | ||
53853e2d VB |
2429 | /* |
2430 | * If compaction is not ready to start and allocation is not likely | |
2431 | * to succeed without it, then keep reclaiming. | |
2432 | */ | |
ebff3980 | 2433 | if (compaction_suitable(zone, order, 0, 0) == COMPACT_SKIPPED) |
fe4b1b24 MG |
2434 | return false; |
2435 | ||
2436 | return watermark_ok; | |
2437 | } | |
2438 | ||
1da177e4 LT |
2439 | /* |
2440 | * This is the direct reclaim path, for page-allocating processes. We only | |
2441 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2442 | * request. | |
2443 | * | |
41858966 MG |
2444 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
2445 | * Because: | |
1da177e4 LT |
2446 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
2447 | * allocation or | |
41858966 MG |
2448 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
2449 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
2450 | * zone defense algorithm. | |
1da177e4 | 2451 | * |
1da177e4 LT |
2452 | * If a zone is deemed to be full of pinned pages then just give it a light |
2453 | * scan then give up on it. | |
2344d7e4 JW |
2454 | * |
2455 | * Returns true if a zone was reclaimable. | |
1da177e4 | 2456 | */ |
2344d7e4 | 2457 | static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2458 | { |
dd1a239f | 2459 | struct zoneref *z; |
54a6eb5c | 2460 | struct zone *zone; |
0608f43d AM |
2461 | unsigned long nr_soft_reclaimed; |
2462 | unsigned long nr_soft_scanned; | |
619d0d76 | 2463 | gfp_t orig_mask; |
9bbc04ee | 2464 | enum zone_type requested_highidx = gfp_zone(sc->gfp_mask); |
2344d7e4 | 2465 | bool reclaimable = false; |
1cfb419b | 2466 | |
cc715d99 MG |
2467 | /* |
2468 | * If the number of buffer_heads in the machine exceeds the maximum | |
2469 | * allowed level, force direct reclaim to scan the highmem zone as | |
2470 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2471 | */ | |
619d0d76 | 2472 | orig_mask = sc->gfp_mask; |
cc715d99 MG |
2473 | if (buffer_heads_over_limit) |
2474 | sc->gfp_mask |= __GFP_HIGHMEM; | |
2475 | ||
d4debc66 | 2476 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
6b4f7799 JW |
2477 | requested_highidx, sc->nodemask) { |
2478 | enum zone_type classzone_idx; | |
2479 | ||
f3fe6512 | 2480 | if (!populated_zone(zone)) |
1da177e4 | 2481 | continue; |
6b4f7799 JW |
2482 | |
2483 | classzone_idx = requested_highidx; | |
2484 | while (!populated_zone(zone->zone_pgdat->node_zones + | |
2485 | classzone_idx)) | |
2486 | classzone_idx--; | |
2487 | ||
1cfb419b KH |
2488 | /* |
2489 | * Take care memory controller reclaiming has small influence | |
2490 | * to global LRU. | |
2491 | */ | |
89b5fae5 | 2492 | if (global_reclaim(sc)) { |
344736f2 VD |
2493 | if (!cpuset_zone_allowed(zone, |
2494 | GFP_KERNEL | __GFP_HARDWALL)) | |
1cfb419b | 2495 | continue; |
65ec02cb | 2496 | |
6e543d57 LD |
2497 | if (sc->priority != DEF_PRIORITY && |
2498 | !zone_reclaimable(zone)) | |
1cfb419b | 2499 | continue; /* Let kswapd poll it */ |
0b06496a JW |
2500 | |
2501 | /* | |
2502 | * If we already have plenty of memory free for | |
2503 | * compaction in this zone, don't free any more. | |
2504 | * Even though compaction is invoked for any | |
2505 | * non-zero order, only frequent costly order | |
2506 | * reclamation is disruptive enough to become a | |
2507 | * noticeable problem, like transparent huge | |
2508 | * page allocations. | |
2509 | */ | |
2510 | if (IS_ENABLED(CONFIG_COMPACTION) && | |
2511 | sc->order > PAGE_ALLOC_COSTLY_ORDER && | |
2512 | zonelist_zone_idx(z) <= requested_highidx && | |
2513 | compaction_ready(zone, sc->order)) { | |
2514 | sc->compaction_ready = true; | |
2515 | continue; | |
e0887c19 | 2516 | } |
0b06496a | 2517 | |
0608f43d AM |
2518 | /* |
2519 | * This steals pages from memory cgroups over softlimit | |
2520 | * and returns the number of reclaimed pages and | |
2521 | * scanned pages. This works for global memory pressure | |
2522 | * and balancing, not for a memcg's limit. | |
2523 | */ | |
2524 | nr_soft_scanned = 0; | |
2525 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
2526 | sc->order, sc->gfp_mask, | |
2527 | &nr_soft_scanned); | |
2528 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2529 | sc->nr_scanned += nr_soft_scanned; | |
2344d7e4 JW |
2530 | if (nr_soft_reclaimed) |
2531 | reclaimable = true; | |
ac34a1a3 | 2532 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2533 | } |
408d8544 | 2534 | |
6b4f7799 | 2535 | if (shrink_zone(zone, sc, zone_idx(zone) == classzone_idx)) |
2344d7e4 JW |
2536 | reclaimable = true; |
2537 | ||
2538 | if (global_reclaim(sc) && | |
2539 | !reclaimable && zone_reclaimable(zone)) | |
2540 | reclaimable = true; | |
1da177e4 | 2541 | } |
e0c23279 | 2542 | |
619d0d76 WY |
2543 | /* |
2544 | * Restore to original mask to avoid the impact on the caller if we | |
2545 | * promoted it to __GFP_HIGHMEM. | |
2546 | */ | |
2547 | sc->gfp_mask = orig_mask; | |
d1908362 | 2548 | |
2344d7e4 | 2549 | return reclaimable; |
1da177e4 | 2550 | } |
4f98a2fe | 2551 | |
1da177e4 LT |
2552 | /* |
2553 | * This is the main entry point to direct page reclaim. | |
2554 | * | |
2555 | * If a full scan of the inactive list fails to free enough memory then we | |
2556 | * are "out of memory" and something needs to be killed. | |
2557 | * | |
2558 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2559 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2560 | * caller can't do much about. We kick the writeback threads and take explicit |
2561 | * naps in the hope that some of these pages can be written. But if the | |
2562 | * allocating task holds filesystem locks which prevent writeout this might not | |
2563 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2564 | * |
2565 | * returns: 0, if no pages reclaimed | |
2566 | * else, the number of pages reclaimed | |
1da177e4 | 2567 | */ |
dac1d27b | 2568 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
3115cd91 | 2569 | struct scan_control *sc) |
1da177e4 | 2570 | { |
241994ed | 2571 | int initial_priority = sc->priority; |
69e05944 | 2572 | unsigned long total_scanned = 0; |
22fba335 | 2573 | unsigned long writeback_threshold; |
2344d7e4 | 2574 | bool zones_reclaimable; |
241994ed | 2575 | retry: |
873b4771 KK |
2576 | delayacct_freepages_start(); |
2577 | ||
89b5fae5 | 2578 | if (global_reclaim(sc)) |
1cfb419b | 2579 | count_vm_event(ALLOCSTALL); |
1da177e4 | 2580 | |
9e3b2f8c | 2581 | do { |
70ddf637 AV |
2582 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
2583 | sc->priority); | |
66e1707b | 2584 | sc->nr_scanned = 0; |
2344d7e4 | 2585 | zones_reclaimable = shrink_zones(zonelist, sc); |
c6a8a8c5 | 2586 | |
66e1707b | 2587 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2588 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
0b06496a JW |
2589 | break; |
2590 | ||
2591 | if (sc->compaction_ready) | |
2592 | break; | |
1da177e4 | 2593 | |
0e50ce3b MK |
2594 | /* |
2595 | * If we're getting trouble reclaiming, start doing | |
2596 | * writepage even in laptop mode. | |
2597 | */ | |
2598 | if (sc->priority < DEF_PRIORITY - 2) | |
2599 | sc->may_writepage = 1; | |
2600 | ||
1da177e4 LT |
2601 | /* |
2602 | * Try to write back as many pages as we just scanned. This | |
2603 | * tends to cause slow streaming writers to write data to the | |
2604 | * disk smoothly, at the dirtying rate, which is nice. But | |
2605 | * that's undesirable in laptop mode, where we *want* lumpy | |
2606 | * writeout. So in laptop mode, write out the whole world. | |
2607 | */ | |
22fba335 KM |
2608 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2609 | if (total_scanned > writeback_threshold) { | |
0e175a18 CW |
2610 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned, |
2611 | WB_REASON_TRY_TO_FREE_PAGES); | |
66e1707b | 2612 | sc->may_writepage = 1; |
1da177e4 | 2613 | } |
0b06496a | 2614 | } while (--sc->priority >= 0); |
bb21c7ce | 2615 | |
873b4771 KK |
2616 | delayacct_freepages_end(); |
2617 | ||
bb21c7ce KM |
2618 | if (sc->nr_reclaimed) |
2619 | return sc->nr_reclaimed; | |
2620 | ||
0cee34fd | 2621 | /* Aborted reclaim to try compaction? don't OOM, then */ |
0b06496a | 2622 | if (sc->compaction_ready) |
7335084d MG |
2623 | return 1; |
2624 | ||
241994ed JW |
2625 | /* Untapped cgroup reserves? Don't OOM, retry. */ |
2626 | if (!sc->may_thrash) { | |
2627 | sc->priority = initial_priority; | |
2628 | sc->may_thrash = 1; | |
2629 | goto retry; | |
2630 | } | |
2631 | ||
2344d7e4 JW |
2632 | /* Any of the zones still reclaimable? Don't OOM. */ |
2633 | if (zones_reclaimable) | |
bb21c7ce KM |
2634 | return 1; |
2635 | ||
2636 | return 0; | |
1da177e4 LT |
2637 | } |
2638 | ||
5515061d MG |
2639 | static bool pfmemalloc_watermark_ok(pg_data_t *pgdat) |
2640 | { | |
2641 | struct zone *zone; | |
2642 | unsigned long pfmemalloc_reserve = 0; | |
2643 | unsigned long free_pages = 0; | |
2644 | int i; | |
2645 | bool wmark_ok; | |
2646 | ||
2647 | for (i = 0; i <= ZONE_NORMAL; i++) { | |
2648 | zone = &pgdat->node_zones[i]; | |
f012a84a NA |
2649 | if (!populated_zone(zone) || |
2650 | zone_reclaimable_pages(zone) == 0) | |
675becce MG |
2651 | continue; |
2652 | ||
5515061d MG |
2653 | pfmemalloc_reserve += min_wmark_pages(zone); |
2654 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
2655 | } | |
2656 | ||
675becce MG |
2657 | /* If there are no reserves (unexpected config) then do not throttle */ |
2658 | if (!pfmemalloc_reserve) | |
2659 | return true; | |
2660 | ||
5515061d MG |
2661 | wmark_ok = free_pages > pfmemalloc_reserve / 2; |
2662 | ||
2663 | /* kswapd must be awake if processes are being throttled */ | |
2664 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
2665 | pgdat->classzone_idx = min(pgdat->classzone_idx, | |
2666 | (enum zone_type)ZONE_NORMAL); | |
2667 | wake_up_interruptible(&pgdat->kswapd_wait); | |
2668 | } | |
2669 | ||
2670 | return wmark_ok; | |
2671 | } | |
2672 | ||
2673 | /* | |
2674 | * Throttle direct reclaimers if backing storage is backed by the network | |
2675 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
2676 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
2677 | * when the low watermark is reached. |
2678 | * | |
2679 | * Returns true if a fatal signal was delivered during throttling. If this | |
2680 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 2681 | */ |
50694c28 | 2682 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
2683 | nodemask_t *nodemask) |
2684 | { | |
675becce | 2685 | struct zoneref *z; |
5515061d | 2686 | struct zone *zone; |
675becce | 2687 | pg_data_t *pgdat = NULL; |
5515061d MG |
2688 | |
2689 | /* | |
2690 | * Kernel threads should not be throttled as they may be indirectly | |
2691 | * responsible for cleaning pages necessary for reclaim to make forward | |
2692 | * progress. kjournald for example may enter direct reclaim while | |
2693 | * committing a transaction where throttling it could forcing other | |
2694 | * processes to block on log_wait_commit(). | |
2695 | */ | |
2696 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
2697 | goto out; |
2698 | ||
2699 | /* | |
2700 | * If a fatal signal is pending, this process should not throttle. | |
2701 | * It should return quickly so it can exit and free its memory | |
2702 | */ | |
2703 | if (fatal_signal_pending(current)) | |
2704 | goto out; | |
5515061d | 2705 | |
675becce MG |
2706 | /* |
2707 | * Check if the pfmemalloc reserves are ok by finding the first node | |
2708 | * with a usable ZONE_NORMAL or lower zone. The expectation is that | |
2709 | * GFP_KERNEL will be required for allocating network buffers when | |
2710 | * swapping over the network so ZONE_HIGHMEM is unusable. | |
2711 | * | |
2712 | * Throttling is based on the first usable node and throttled processes | |
2713 | * wait on a queue until kswapd makes progress and wakes them. There | |
2714 | * is an affinity then between processes waking up and where reclaim | |
2715 | * progress has been made assuming the process wakes on the same node. | |
2716 | * More importantly, processes running on remote nodes will not compete | |
2717 | * for remote pfmemalloc reserves and processes on different nodes | |
2718 | * should make reasonable progress. | |
2719 | */ | |
2720 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
17636faa | 2721 | gfp_zone(gfp_mask), nodemask) { |
675becce MG |
2722 | if (zone_idx(zone) > ZONE_NORMAL) |
2723 | continue; | |
2724 | ||
2725 | /* Throttle based on the first usable node */ | |
2726 | pgdat = zone->zone_pgdat; | |
2727 | if (pfmemalloc_watermark_ok(pgdat)) | |
2728 | goto out; | |
2729 | break; | |
2730 | } | |
2731 | ||
2732 | /* If no zone was usable by the allocation flags then do not throttle */ | |
2733 | if (!pgdat) | |
50694c28 | 2734 | goto out; |
5515061d | 2735 | |
68243e76 MG |
2736 | /* Account for the throttling */ |
2737 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
2738 | ||
5515061d MG |
2739 | /* |
2740 | * If the caller cannot enter the filesystem, it's possible that it | |
2741 | * is due to the caller holding an FS lock or performing a journal | |
2742 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
2743 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
2744 | * blocked waiting on the same lock. Instead, throttle for up to a | |
2745 | * second before continuing. | |
2746 | */ | |
2747 | if (!(gfp_mask & __GFP_FS)) { | |
2748 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
2749 | pfmemalloc_watermark_ok(pgdat), HZ); | |
50694c28 MG |
2750 | |
2751 | goto check_pending; | |
5515061d MG |
2752 | } |
2753 | ||
2754 | /* Throttle until kswapd wakes the process */ | |
2755 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
2756 | pfmemalloc_watermark_ok(pgdat)); | |
50694c28 MG |
2757 | |
2758 | check_pending: | |
2759 | if (fatal_signal_pending(current)) | |
2760 | return true; | |
2761 | ||
2762 | out: | |
2763 | return false; | |
5515061d MG |
2764 | } |
2765 | ||
dac1d27b | 2766 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2767 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2768 | { |
33906bc5 | 2769 | unsigned long nr_reclaimed; |
66e1707b | 2770 | struct scan_control sc = { |
ee814fe2 | 2771 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
21caf2fc | 2772 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
ee814fe2 JW |
2773 | .order = order, |
2774 | .nodemask = nodemask, | |
2775 | .priority = DEF_PRIORITY, | |
66e1707b | 2776 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2777 | .may_unmap = 1, |
2e2e4259 | 2778 | .may_swap = 1, |
66e1707b BS |
2779 | }; |
2780 | ||
5515061d | 2781 | /* |
50694c28 MG |
2782 | * Do not enter reclaim if fatal signal was delivered while throttled. |
2783 | * 1 is returned so that the page allocator does not OOM kill at this | |
2784 | * point. | |
5515061d | 2785 | */ |
50694c28 | 2786 | if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) |
5515061d MG |
2787 | return 1; |
2788 | ||
33906bc5 MG |
2789 | trace_mm_vmscan_direct_reclaim_begin(order, |
2790 | sc.may_writepage, | |
2791 | gfp_mask); | |
2792 | ||
3115cd91 | 2793 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
33906bc5 MG |
2794 | |
2795 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2796 | ||
2797 | return nr_reclaimed; | |
66e1707b BS |
2798 | } |
2799 | ||
c255a458 | 2800 | #ifdef CONFIG_MEMCG |
66e1707b | 2801 | |
72835c86 | 2802 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg, |
4e416953 | 2803 | gfp_t gfp_mask, bool noswap, |
0ae5e89c YH |
2804 | struct zone *zone, |
2805 | unsigned long *nr_scanned) | |
4e416953 BS |
2806 | { |
2807 | struct scan_control sc = { | |
b8f5c566 | 2808 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
ee814fe2 | 2809 | .target_mem_cgroup = memcg, |
4e416953 BS |
2810 | .may_writepage = !laptop_mode, |
2811 | .may_unmap = 1, | |
2812 | .may_swap = !noswap, | |
4e416953 | 2813 | }; |
f9be23d6 | 2814 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
02695175 | 2815 | int swappiness = mem_cgroup_swappiness(memcg); |
6b4f7799 | 2816 | unsigned long lru_pages; |
0ae5e89c | 2817 | |
4e416953 BS |
2818 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2819 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 2820 | |
9e3b2f8c | 2821 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e KM |
2822 | sc.may_writepage, |
2823 | sc.gfp_mask); | |
2824 | ||
4e416953 BS |
2825 | /* |
2826 | * NOTE: Although we can get the priority field, using it | |
2827 | * here is not a good idea, since it limits the pages we can scan. | |
2828 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2829 | * will pick up pages from other mem cgroup's as well. We hack | |
2830 | * the priority and make it zero. | |
2831 | */ | |
6b4f7799 | 2832 | shrink_lruvec(lruvec, swappiness, &sc, &lru_pages); |
bdce6d9e KM |
2833 | |
2834 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2835 | ||
0ae5e89c | 2836 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2837 | return sc.nr_reclaimed; |
2838 | } | |
2839 | ||
72835c86 | 2840 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
b70a2a21 | 2841 | unsigned long nr_pages, |
a7885eb8 | 2842 | gfp_t gfp_mask, |
b70a2a21 | 2843 | bool may_swap) |
66e1707b | 2844 | { |
4e416953 | 2845 | struct zonelist *zonelist; |
bdce6d9e | 2846 | unsigned long nr_reclaimed; |
889976db | 2847 | int nid; |
66e1707b | 2848 | struct scan_control sc = { |
b70a2a21 | 2849 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
a09ed5e0 YH |
2850 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2851 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
ee814fe2 JW |
2852 | .target_mem_cgroup = memcg, |
2853 | .priority = DEF_PRIORITY, | |
2854 | .may_writepage = !laptop_mode, | |
2855 | .may_unmap = 1, | |
b70a2a21 | 2856 | .may_swap = may_swap, |
a09ed5e0 | 2857 | }; |
66e1707b | 2858 | |
889976db YH |
2859 | /* |
2860 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
2861 | * take care of from where we get pages. So the node where we start the | |
2862 | * scan does not need to be the current node. | |
2863 | */ | |
72835c86 | 2864 | nid = mem_cgroup_select_victim_node(memcg); |
889976db YH |
2865 | |
2866 | zonelist = NODE_DATA(nid)->node_zonelists; | |
bdce6d9e KM |
2867 | |
2868 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2869 | sc.may_writepage, | |
2870 | sc.gfp_mask); | |
2871 | ||
3115cd91 | 2872 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
bdce6d9e KM |
2873 | |
2874 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2875 | ||
2876 | return nr_reclaimed; | |
66e1707b BS |
2877 | } |
2878 | #endif | |
2879 | ||
9e3b2f8c | 2880 | static void age_active_anon(struct zone *zone, struct scan_control *sc) |
f16015fb | 2881 | { |
b95a2f2d | 2882 | struct mem_cgroup *memcg; |
f16015fb | 2883 | |
b95a2f2d JW |
2884 | if (!total_swap_pages) |
2885 | return; | |
2886 | ||
2887 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
2888 | do { | |
c56d5c7d | 2889 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
b95a2f2d | 2890 | |
c56d5c7d | 2891 | if (inactive_anon_is_low(lruvec)) |
1a93be0e | 2892 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 2893 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
2894 | |
2895 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
2896 | } while (memcg); | |
f16015fb JW |
2897 | } |
2898 | ||
60cefed4 JW |
2899 | static bool zone_balanced(struct zone *zone, int order, |
2900 | unsigned long balance_gap, int classzone_idx) | |
2901 | { | |
2902 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) + | |
2903 | balance_gap, classzone_idx, 0)) | |
2904 | return false; | |
2905 | ||
ebff3980 VB |
2906 | if (IS_ENABLED(CONFIG_COMPACTION) && order && compaction_suitable(zone, |
2907 | order, 0, classzone_idx) == COMPACT_SKIPPED) | |
60cefed4 JW |
2908 | return false; |
2909 | ||
2910 | return true; | |
2911 | } | |
2912 | ||
1741c877 | 2913 | /* |
4ae0a48b ZC |
2914 | * pgdat_balanced() is used when checking if a node is balanced. |
2915 | * | |
2916 | * For order-0, all zones must be balanced! | |
2917 | * | |
2918 | * For high-order allocations only zones that meet watermarks and are in a | |
2919 | * zone allowed by the callers classzone_idx are added to balanced_pages. The | |
2920 | * total of balanced pages must be at least 25% of the zones allowed by | |
2921 | * classzone_idx for the node to be considered balanced. Forcing all zones to | |
2922 | * be balanced for high orders can cause excessive reclaim when there are | |
2923 | * imbalanced zones. | |
1741c877 MG |
2924 | * The choice of 25% is due to |
2925 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2926 | * reasonable sized machine | |
2927 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2928 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2929 | * would need to be at least 256M for it to be balance a whole node. |
2930 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2931 | * to balance a node on its own. These seemed like reasonable ratios. | |
2932 | */ | |
4ae0a48b | 2933 | static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) |
1741c877 | 2934 | { |
b40da049 | 2935 | unsigned long managed_pages = 0; |
4ae0a48b | 2936 | unsigned long balanced_pages = 0; |
1741c877 MG |
2937 | int i; |
2938 | ||
4ae0a48b ZC |
2939 | /* Check the watermark levels */ |
2940 | for (i = 0; i <= classzone_idx; i++) { | |
2941 | struct zone *zone = pgdat->node_zones + i; | |
1741c877 | 2942 | |
4ae0a48b ZC |
2943 | if (!populated_zone(zone)) |
2944 | continue; | |
2945 | ||
b40da049 | 2946 | managed_pages += zone->managed_pages; |
4ae0a48b ZC |
2947 | |
2948 | /* | |
2949 | * A special case here: | |
2950 | * | |
2951 | * balance_pgdat() skips over all_unreclaimable after | |
2952 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2953 | * they must be considered balanced here as well! | |
2954 | */ | |
6e543d57 | 2955 | if (!zone_reclaimable(zone)) { |
b40da049 | 2956 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2957 | continue; |
2958 | } | |
2959 | ||
2960 | if (zone_balanced(zone, order, 0, i)) | |
b40da049 | 2961 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2962 | else if (!order) |
2963 | return false; | |
2964 | } | |
2965 | ||
2966 | if (order) | |
b40da049 | 2967 | return balanced_pages >= (managed_pages >> 2); |
4ae0a48b ZC |
2968 | else |
2969 | return true; | |
1741c877 MG |
2970 | } |
2971 | ||
5515061d MG |
2972 | /* |
2973 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
2974 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
2975 | * | |
2976 | * Returns true if kswapd is ready to sleep | |
2977 | */ | |
2978 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, | |
dc83edd9 | 2979 | int classzone_idx) |
f50de2d3 | 2980 | { |
f50de2d3 MG |
2981 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ |
2982 | if (remaining) | |
5515061d MG |
2983 | return false; |
2984 | ||
2985 | /* | |
9e5e3661 VB |
2986 | * The throttled processes are normally woken up in balance_pgdat() as |
2987 | * soon as pfmemalloc_watermark_ok() is true. But there is a potential | |
2988 | * race between when kswapd checks the watermarks and a process gets | |
2989 | * throttled. There is also a potential race if processes get | |
2990 | * throttled, kswapd wakes, a large process exits thereby balancing the | |
2991 | * zones, which causes kswapd to exit balance_pgdat() before reaching | |
2992 | * the wake up checks. If kswapd is going to sleep, no process should | |
2993 | * be sleeping on pfmemalloc_wait, so wake them now if necessary. If | |
2994 | * the wake up is premature, processes will wake kswapd and get | |
2995 | * throttled again. The difference from wake ups in balance_pgdat() is | |
2996 | * that here we are under prepare_to_wait(). | |
5515061d | 2997 | */ |
9e5e3661 VB |
2998 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) |
2999 | wake_up_all(&pgdat->pfmemalloc_wait); | |
f50de2d3 | 3000 | |
4ae0a48b | 3001 | return pgdat_balanced(pgdat, order, classzone_idx); |
f50de2d3 MG |
3002 | } |
3003 | ||
75485363 MG |
3004 | /* |
3005 | * kswapd shrinks the zone by the number of pages required to reach | |
3006 | * the high watermark. | |
b8e83b94 MG |
3007 | * |
3008 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
3009 | * reclaim or if the lack of progress was due to pages under writeback. |
3010 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 3011 | */ |
b8e83b94 | 3012 | static bool kswapd_shrink_zone(struct zone *zone, |
7c954f6d | 3013 | int classzone_idx, |
75485363 | 3014 | struct scan_control *sc, |
2ab44f43 | 3015 | unsigned long *nr_attempted) |
75485363 | 3016 | { |
7c954f6d MG |
3017 | int testorder = sc->order; |
3018 | unsigned long balance_gap; | |
7c954f6d | 3019 | bool lowmem_pressure; |
75485363 MG |
3020 | |
3021 | /* Reclaim above the high watermark. */ | |
3022 | sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); | |
7c954f6d MG |
3023 | |
3024 | /* | |
3025 | * Kswapd reclaims only single pages with compaction enabled. Trying | |
3026 | * too hard to reclaim until contiguous free pages have become | |
3027 | * available can hurt performance by evicting too much useful data | |
3028 | * from memory. Do not reclaim more than needed for compaction. | |
3029 | */ | |
3030 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && | |
ebff3980 VB |
3031 | compaction_suitable(zone, sc->order, 0, classzone_idx) |
3032 | != COMPACT_SKIPPED) | |
7c954f6d MG |
3033 | testorder = 0; |
3034 | ||
3035 | /* | |
3036 | * We put equal pressure on every zone, unless one zone has way too | |
3037 | * many pages free already. The "too many pages" is defined as the | |
3038 | * high wmark plus a "gap" where the gap is either the low | |
3039 | * watermark or 1% of the zone, whichever is smaller. | |
3040 | */ | |
4be89a34 JZ |
3041 | balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP( |
3042 | zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO)); | |
7c954f6d MG |
3043 | |
3044 | /* | |
3045 | * If there is no low memory pressure or the zone is balanced then no | |
3046 | * reclaim is necessary | |
3047 | */ | |
3048 | lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone)); | |
3049 | if (!lowmem_pressure && zone_balanced(zone, testorder, | |
3050 | balance_gap, classzone_idx)) | |
3051 | return true; | |
3052 | ||
6b4f7799 | 3053 | shrink_zone(zone, sc, zone_idx(zone) == classzone_idx); |
75485363 | 3054 | |
2ab44f43 MG |
3055 | /* Account for the number of pages attempted to reclaim */ |
3056 | *nr_attempted += sc->nr_to_reclaim; | |
3057 | ||
57054651 | 3058 | clear_bit(ZONE_WRITEBACK, &zone->flags); |
283aba9f | 3059 | |
7c954f6d MG |
3060 | /* |
3061 | * If a zone reaches its high watermark, consider it to be no longer | |
3062 | * congested. It's possible there are dirty pages backed by congested | |
3063 | * BDIs but as pressure is relieved, speculatively avoid congestion | |
3064 | * waits. | |
3065 | */ | |
6e543d57 | 3066 | if (zone_reclaimable(zone) && |
7c954f6d | 3067 | zone_balanced(zone, testorder, 0, classzone_idx)) { |
57054651 JW |
3068 | clear_bit(ZONE_CONGESTED, &zone->flags); |
3069 | clear_bit(ZONE_DIRTY, &zone->flags); | |
7c954f6d MG |
3070 | } |
3071 | ||
b8e83b94 | 3072 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
3073 | } |
3074 | ||
1da177e4 LT |
3075 | /* |
3076 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 3077 | * they are all at high_wmark_pages(zone). |
1da177e4 | 3078 | * |
0abdee2b | 3079 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
3080 | * |
3081 | * There is special handling here for zones which are full of pinned pages. | |
3082 | * This can happen if the pages are all mlocked, or if they are all used by | |
3083 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
3084 | * What we do is to detect the case where all pages in the zone have been | |
3085 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
3086 | * dead and from now on, only perform a short scan. Basically we're polling | |
3087 | * the zone for when the problem goes away. | |
3088 | * | |
3089 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
3090 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
3091 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
3092 | * lower zones regardless of the number of free pages in the lower zones. This | |
3093 | * interoperates with the page allocator fallback scheme to ensure that aging | |
3094 | * of pages is balanced across the zones. | |
1da177e4 | 3095 | */ |
99504748 | 3096 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 3097 | int *classzone_idx) |
1da177e4 | 3098 | { |
1da177e4 | 3099 | int i; |
99504748 | 3100 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
0608f43d AM |
3101 | unsigned long nr_soft_reclaimed; |
3102 | unsigned long nr_soft_scanned; | |
179e9639 AM |
3103 | struct scan_control sc = { |
3104 | .gfp_mask = GFP_KERNEL, | |
ee814fe2 | 3105 | .order = order, |
b8e83b94 | 3106 | .priority = DEF_PRIORITY, |
ee814fe2 | 3107 | .may_writepage = !laptop_mode, |
a6dc60f8 | 3108 | .may_unmap = 1, |
2e2e4259 | 3109 | .may_swap = 1, |
179e9639 | 3110 | }; |
f8891e5e | 3111 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 3112 | |
9e3b2f8c | 3113 | do { |
2ab44f43 | 3114 | unsigned long nr_attempted = 0; |
b8e83b94 | 3115 | bool raise_priority = true; |
2ab44f43 | 3116 | bool pgdat_needs_compaction = (order > 0); |
b8e83b94 MG |
3117 | |
3118 | sc.nr_reclaimed = 0; | |
1da177e4 | 3119 | |
d6277db4 RW |
3120 | /* |
3121 | * Scan in the highmem->dma direction for the highest | |
3122 | * zone which needs scanning | |
3123 | */ | |
3124 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
3125 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 3126 | |
d6277db4 RW |
3127 | if (!populated_zone(zone)) |
3128 | continue; | |
1da177e4 | 3129 | |
6e543d57 LD |
3130 | if (sc.priority != DEF_PRIORITY && |
3131 | !zone_reclaimable(zone)) | |
d6277db4 | 3132 | continue; |
1da177e4 | 3133 | |
556adecb RR |
3134 | /* |
3135 | * Do some background aging of the anon list, to give | |
3136 | * pages a chance to be referenced before reclaiming. | |
3137 | */ | |
9e3b2f8c | 3138 | age_active_anon(zone, &sc); |
556adecb | 3139 | |
cc715d99 MG |
3140 | /* |
3141 | * If the number of buffer_heads in the machine | |
3142 | * exceeds the maximum allowed level and this node | |
3143 | * has a highmem zone, force kswapd to reclaim from | |
3144 | * it to relieve lowmem pressure. | |
3145 | */ | |
3146 | if (buffer_heads_over_limit && is_highmem_idx(i)) { | |
3147 | end_zone = i; | |
3148 | break; | |
3149 | } | |
3150 | ||
60cefed4 | 3151 | if (!zone_balanced(zone, order, 0, 0)) { |
d6277db4 | 3152 | end_zone = i; |
e1dbeda6 | 3153 | break; |
439423f6 | 3154 | } else { |
d43006d5 MG |
3155 | /* |
3156 | * If balanced, clear the dirty and congested | |
3157 | * flags | |
3158 | */ | |
57054651 JW |
3159 | clear_bit(ZONE_CONGESTED, &zone->flags); |
3160 | clear_bit(ZONE_DIRTY, &zone->flags); | |
1da177e4 | 3161 | } |
1da177e4 | 3162 | } |
dafcb73e | 3163 | |
b8e83b94 | 3164 | if (i < 0) |
e1dbeda6 AM |
3165 | goto out; |
3166 | ||
1da177e4 LT |
3167 | for (i = 0; i <= end_zone; i++) { |
3168 | struct zone *zone = pgdat->node_zones + i; | |
3169 | ||
2ab44f43 MG |
3170 | if (!populated_zone(zone)) |
3171 | continue; | |
3172 | ||
2ab44f43 MG |
3173 | /* |
3174 | * If any zone is currently balanced then kswapd will | |
3175 | * not call compaction as it is expected that the | |
3176 | * necessary pages are already available. | |
3177 | */ | |
3178 | if (pgdat_needs_compaction && | |
3179 | zone_watermark_ok(zone, order, | |
3180 | low_wmark_pages(zone), | |
3181 | *classzone_idx, 0)) | |
3182 | pgdat_needs_compaction = false; | |
1da177e4 LT |
3183 | } |
3184 | ||
b7ea3c41 MG |
3185 | /* |
3186 | * If we're getting trouble reclaiming, start doing writepage | |
3187 | * even in laptop mode. | |
3188 | */ | |
3189 | if (sc.priority < DEF_PRIORITY - 2) | |
3190 | sc.may_writepage = 1; | |
3191 | ||
1da177e4 LT |
3192 | /* |
3193 | * Now scan the zone in the dma->highmem direction, stopping | |
3194 | * at the last zone which needs scanning. | |
3195 | * | |
3196 | * We do this because the page allocator works in the opposite | |
3197 | * direction. This prevents the page allocator from allocating | |
3198 | * pages behind kswapd's direction of progress, which would | |
3199 | * cause too much scanning of the lower zones. | |
3200 | */ | |
3201 | for (i = 0; i <= end_zone; i++) { | |
3202 | struct zone *zone = pgdat->node_zones + i; | |
3203 | ||
f3fe6512 | 3204 | if (!populated_zone(zone)) |
1da177e4 LT |
3205 | continue; |
3206 | ||
6e543d57 LD |
3207 | if (sc.priority != DEF_PRIORITY && |
3208 | !zone_reclaimable(zone)) | |
1da177e4 LT |
3209 | continue; |
3210 | ||
1da177e4 | 3211 | sc.nr_scanned = 0; |
4e416953 | 3212 | |
0608f43d AM |
3213 | nr_soft_scanned = 0; |
3214 | /* | |
3215 | * Call soft limit reclaim before calling shrink_zone. | |
3216 | */ | |
3217 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
3218 | order, sc.gfp_mask, | |
3219 | &nr_soft_scanned); | |
3220 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3221 | ||
32a4330d | 3222 | /* |
7c954f6d MG |
3223 | * There should be no need to raise the scanning |
3224 | * priority if enough pages are already being scanned | |
3225 | * that that high watermark would be met at 100% | |
3226 | * efficiency. | |
fe2c2a10 | 3227 | */ |
6b4f7799 JW |
3228 | if (kswapd_shrink_zone(zone, end_zone, |
3229 | &sc, &nr_attempted)) | |
7c954f6d | 3230 | raise_priority = false; |
1da177e4 | 3231 | } |
5515061d MG |
3232 | |
3233 | /* | |
3234 | * If the low watermark is met there is no need for processes | |
3235 | * to be throttled on pfmemalloc_wait as they should not be | |
3236 | * able to safely make forward progress. Wake them | |
3237 | */ | |
3238 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
3239 | pfmemalloc_watermark_ok(pgdat)) | |
cfc51155 | 3240 | wake_up_all(&pgdat->pfmemalloc_wait); |
5515061d | 3241 | |
1da177e4 | 3242 | /* |
b8e83b94 MG |
3243 | * Fragmentation may mean that the system cannot be rebalanced |
3244 | * for high-order allocations in all zones. If twice the | |
3245 | * allocation size has been reclaimed and the zones are still | |
3246 | * not balanced then recheck the watermarks at order-0 to | |
3247 | * prevent kswapd reclaiming excessively. Assume that a | |
3248 | * process requested a high-order can direct reclaim/compact. | |
1da177e4 | 3249 | */ |
b8e83b94 MG |
3250 | if (order && sc.nr_reclaimed >= 2UL << order) |
3251 | order = sc.order = 0; | |
8357376d | 3252 | |
b8e83b94 MG |
3253 | /* Check if kswapd should be suspending */ |
3254 | if (try_to_freeze() || kthread_should_stop()) | |
3255 | break; | |
8357376d | 3256 | |
2ab44f43 MG |
3257 | /* |
3258 | * Compact if necessary and kswapd is reclaiming at least the | |
3259 | * high watermark number of pages as requsted | |
3260 | */ | |
3261 | if (pgdat_needs_compaction && sc.nr_reclaimed > nr_attempted) | |
3262 | compact_pgdat(pgdat, order); | |
3263 | ||
73ce02e9 | 3264 | /* |
b8e83b94 MG |
3265 | * Raise priority if scanning rate is too low or there was no |
3266 | * progress in reclaiming pages | |
73ce02e9 | 3267 | */ |
b8e83b94 MG |
3268 | if (raise_priority || !sc.nr_reclaimed) |
3269 | sc.priority--; | |
9aa41348 | 3270 | } while (sc.priority >= 1 && |
b8e83b94 | 3271 | !pgdat_balanced(pgdat, order, *classzone_idx)); |
1da177e4 | 3272 | |
b8e83b94 | 3273 | out: |
0abdee2b | 3274 | /* |
5515061d | 3275 | * Return the order we were reclaiming at so prepare_kswapd_sleep() |
0abdee2b MG |
3276 | * makes a decision on the order we were last reclaiming at. However, |
3277 | * if another caller entered the allocator slow path while kswapd | |
3278 | * was awake, order will remain at the higher level | |
3279 | */ | |
dc83edd9 | 3280 | *classzone_idx = end_zone; |
0abdee2b | 3281 | return order; |
1da177e4 LT |
3282 | } |
3283 | ||
dc83edd9 | 3284 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
3285 | { |
3286 | long remaining = 0; | |
3287 | DEFINE_WAIT(wait); | |
3288 | ||
3289 | if (freezing(current) || kthread_should_stop()) | |
3290 | return; | |
3291 | ||
3292 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3293 | ||
3294 | /* Try to sleep for a short interval */ | |
5515061d | 3295 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3296 | remaining = schedule_timeout(HZ/10); |
3297 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3298 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3299 | } | |
3300 | ||
3301 | /* | |
3302 | * After a short sleep, check if it was a premature sleep. If not, then | |
3303 | * go fully to sleep until explicitly woken up. | |
3304 | */ | |
5515061d | 3305 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3306 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3307 | ||
3308 | /* | |
3309 | * vmstat counters are not perfectly accurate and the estimated | |
3310 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3311 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3312 | * watermarks being breached while under pressure, we reduce the | |
3313 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3314 | * them before going back to sleep. | |
3315 | */ | |
3316 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c | 3317 | |
62997027 MG |
3318 | /* |
3319 | * Compaction records what page blocks it recently failed to | |
3320 | * isolate pages from and skips them in the future scanning. | |
3321 | * When kswapd is going to sleep, it is reasonable to assume | |
3322 | * that pages and compaction may succeed so reset the cache. | |
3323 | */ | |
3324 | reset_isolation_suitable(pgdat); | |
3325 | ||
1c7e7f6c AK |
3326 | if (!kthread_should_stop()) |
3327 | schedule(); | |
3328 | ||
f0bc0a60 KM |
3329 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3330 | } else { | |
3331 | if (remaining) | |
3332 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3333 | else | |
3334 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3335 | } | |
3336 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3337 | } | |
3338 | ||
1da177e4 LT |
3339 | /* |
3340 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3341 | * from the init process. |
1da177e4 LT |
3342 | * |
3343 | * This basically trickles out pages so that we have _some_ | |
3344 | * free memory available even if there is no other activity | |
3345 | * that frees anything up. This is needed for things like routing | |
3346 | * etc, where we otherwise might have all activity going on in | |
3347 | * asynchronous contexts that cannot page things out. | |
3348 | * | |
3349 | * If there are applications that are active memory-allocators | |
3350 | * (most normal use), this basically shouldn't matter. | |
3351 | */ | |
3352 | static int kswapd(void *p) | |
3353 | { | |
215ddd66 | 3354 | unsigned long order, new_order; |
d2ebd0f6 | 3355 | unsigned balanced_order; |
215ddd66 | 3356 | int classzone_idx, new_classzone_idx; |
d2ebd0f6 | 3357 | int balanced_classzone_idx; |
1da177e4 LT |
3358 | pg_data_t *pgdat = (pg_data_t*)p; |
3359 | struct task_struct *tsk = current; | |
f0bc0a60 | 3360 | |
1da177e4 LT |
3361 | struct reclaim_state reclaim_state = { |
3362 | .reclaimed_slab = 0, | |
3363 | }; | |
a70f7302 | 3364 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3365 | |
cf40bd16 NP |
3366 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
3367 | ||
174596a0 | 3368 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3369 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3370 | current->reclaim_state = &reclaim_state; |
3371 | ||
3372 | /* | |
3373 | * Tell the memory management that we're a "memory allocator", | |
3374 | * and that if we need more memory we should get access to it | |
3375 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3376 | * never get caught in the normal page freeing logic. | |
3377 | * | |
3378 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3379 | * you need a small amount of memory in order to be able to | |
3380 | * page out something else, and this flag essentially protects | |
3381 | * us from recursively trying to free more memory as we're | |
3382 | * trying to free the first piece of memory in the first place). | |
3383 | */ | |
930d9152 | 3384 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3385 | set_freezable(); |
1da177e4 | 3386 | |
215ddd66 | 3387 | order = new_order = 0; |
d2ebd0f6 | 3388 | balanced_order = 0; |
215ddd66 | 3389 | classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; |
d2ebd0f6 | 3390 | balanced_classzone_idx = classzone_idx; |
1da177e4 | 3391 | for ( ; ; ) { |
6f6313d4 | 3392 | bool ret; |
3e1d1d28 | 3393 | |
215ddd66 MG |
3394 | /* |
3395 | * If the last balance_pgdat was unsuccessful it's unlikely a | |
3396 | * new request of a similar or harder type will succeed soon | |
3397 | * so consider going to sleep on the basis we reclaimed at | |
3398 | */ | |
d2ebd0f6 AS |
3399 | if (balanced_classzone_idx >= new_classzone_idx && |
3400 | balanced_order == new_order) { | |
215ddd66 MG |
3401 | new_order = pgdat->kswapd_max_order; |
3402 | new_classzone_idx = pgdat->classzone_idx; | |
3403 | pgdat->kswapd_max_order = 0; | |
3404 | pgdat->classzone_idx = pgdat->nr_zones - 1; | |
3405 | } | |
3406 | ||
99504748 | 3407 | if (order < new_order || classzone_idx > new_classzone_idx) { |
1da177e4 LT |
3408 | /* |
3409 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 3410 | * allocation or has tigher zone constraints |
1da177e4 LT |
3411 | */ |
3412 | order = new_order; | |
99504748 | 3413 | classzone_idx = new_classzone_idx; |
1da177e4 | 3414 | } else { |
d2ebd0f6 AS |
3415 | kswapd_try_to_sleep(pgdat, balanced_order, |
3416 | balanced_classzone_idx); | |
1da177e4 | 3417 | order = pgdat->kswapd_max_order; |
99504748 | 3418 | classzone_idx = pgdat->classzone_idx; |
f0dfcde0 AS |
3419 | new_order = order; |
3420 | new_classzone_idx = classzone_idx; | |
4d40502e | 3421 | pgdat->kswapd_max_order = 0; |
215ddd66 | 3422 | pgdat->classzone_idx = pgdat->nr_zones - 1; |
1da177e4 | 3423 | } |
1da177e4 | 3424 | |
8fe23e05 DR |
3425 | ret = try_to_freeze(); |
3426 | if (kthread_should_stop()) | |
3427 | break; | |
3428 | ||
3429 | /* | |
3430 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3431 | * after returning from the refrigerator | |
3432 | */ | |
33906bc5 MG |
3433 | if (!ret) { |
3434 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
d2ebd0f6 AS |
3435 | balanced_classzone_idx = classzone_idx; |
3436 | balanced_order = balance_pgdat(pgdat, order, | |
3437 | &balanced_classzone_idx); | |
33906bc5 | 3438 | } |
1da177e4 | 3439 | } |
b0a8cc58 | 3440 | |
71abdc15 | 3441 | tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); |
b0a8cc58 | 3442 | current->reclaim_state = NULL; |
71abdc15 JW |
3443 | lockdep_clear_current_reclaim_state(); |
3444 | ||
1da177e4 LT |
3445 | return 0; |
3446 | } | |
3447 | ||
3448 | /* | |
3449 | * A zone is low on free memory, so wake its kswapd task to service it. | |
3450 | */ | |
99504748 | 3451 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
3452 | { |
3453 | pg_data_t *pgdat; | |
3454 | ||
f3fe6512 | 3455 | if (!populated_zone(zone)) |
1da177e4 LT |
3456 | return; |
3457 | ||
344736f2 | 3458 | if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) |
1da177e4 | 3459 | return; |
88f5acf8 | 3460 | pgdat = zone->zone_pgdat; |
99504748 | 3461 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 3462 | pgdat->kswapd_max_order = order; |
99504748 MG |
3463 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
3464 | } | |
8d0986e2 | 3465 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3466 | return; |
892f795d | 3467 | if (zone_balanced(zone, order, 0, 0)) |
88f5acf8 MG |
3468 | return; |
3469 | ||
3470 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 3471 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3472 | } |
3473 | ||
c6f37f12 | 3474 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3475 | /* |
7b51755c | 3476 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3477 | * freed pages. |
3478 | * | |
3479 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3480 | * LRU order by reclaiming preferentially | |
3481 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3482 | */ |
7b51755c | 3483 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3484 | { |
d6277db4 | 3485 | struct reclaim_state reclaim_state; |
d6277db4 | 3486 | struct scan_control sc = { |
ee814fe2 | 3487 | .nr_to_reclaim = nr_to_reclaim, |
7b51755c | 3488 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
ee814fe2 | 3489 | .priority = DEF_PRIORITY, |
d6277db4 | 3490 | .may_writepage = 1, |
ee814fe2 JW |
3491 | .may_unmap = 1, |
3492 | .may_swap = 1, | |
7b51755c | 3493 | .hibernation_mode = 1, |
1da177e4 | 3494 | }; |
a09ed5e0 | 3495 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
7b51755c KM |
3496 | struct task_struct *p = current; |
3497 | unsigned long nr_reclaimed; | |
1da177e4 | 3498 | |
7b51755c KM |
3499 | p->flags |= PF_MEMALLOC; |
3500 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
3501 | reclaim_state.reclaimed_slab = 0; | |
3502 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3503 | |
3115cd91 | 3504 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 3505 | |
7b51755c KM |
3506 | p->reclaim_state = NULL; |
3507 | lockdep_clear_current_reclaim_state(); | |
3508 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 3509 | |
7b51755c | 3510 | return nr_reclaimed; |
1da177e4 | 3511 | } |
c6f37f12 | 3512 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3513 | |
1da177e4 LT |
3514 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3515 | not required for correctness. So if the last cpu in a node goes | |
3516 | away, we get changed to run anywhere: as the first one comes back, | |
3517 | restore their cpu bindings. */ | |
fcb35a9b GKH |
3518 | static int cpu_callback(struct notifier_block *nfb, unsigned long action, |
3519 | void *hcpu) | |
1da177e4 | 3520 | { |
58c0a4a7 | 3521 | int nid; |
1da177e4 | 3522 | |
8bb78442 | 3523 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
48fb2e24 | 3524 | for_each_node_state(nid, N_MEMORY) { |
c5f59f08 | 3525 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
3526 | const struct cpumask *mask; |
3527 | ||
3528 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 3529 | |
3e597945 | 3530 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 3531 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 3532 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
3533 | } |
3534 | } | |
3535 | return NOTIFY_OK; | |
3536 | } | |
1da177e4 | 3537 | |
3218ae14 YG |
3538 | /* |
3539 | * This kswapd start function will be called by init and node-hot-add. | |
3540 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3541 | */ | |
3542 | int kswapd_run(int nid) | |
3543 | { | |
3544 | pg_data_t *pgdat = NODE_DATA(nid); | |
3545 | int ret = 0; | |
3546 | ||
3547 | if (pgdat->kswapd) | |
3548 | return 0; | |
3549 | ||
3550 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3551 | if (IS_ERR(pgdat->kswapd)) { | |
3552 | /* failure at boot is fatal */ | |
3553 | BUG_ON(system_state == SYSTEM_BOOTING); | |
d5dc0ad9 GS |
3554 | pr_err("Failed to start kswapd on node %d\n", nid); |
3555 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3556 | pgdat->kswapd = NULL; |
3218ae14 YG |
3557 | } |
3558 | return ret; | |
3559 | } | |
3560 | ||
8fe23e05 | 3561 | /* |
d8adde17 | 3562 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
bfc8c901 | 3563 | * hold mem_hotplug_begin/end(). |
8fe23e05 DR |
3564 | */ |
3565 | void kswapd_stop(int nid) | |
3566 | { | |
3567 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3568 | ||
d8adde17 | 3569 | if (kswapd) { |
8fe23e05 | 3570 | kthread_stop(kswapd); |
d8adde17 JL |
3571 | NODE_DATA(nid)->kswapd = NULL; |
3572 | } | |
8fe23e05 DR |
3573 | } |
3574 | ||
1da177e4 LT |
3575 | static int __init kswapd_init(void) |
3576 | { | |
3218ae14 | 3577 | int nid; |
69e05944 | 3578 | |
1da177e4 | 3579 | swap_setup(); |
48fb2e24 | 3580 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3581 | kswapd_run(nid); |
1da177e4 LT |
3582 | hotcpu_notifier(cpu_callback, 0); |
3583 | return 0; | |
3584 | } | |
3585 | ||
3586 | module_init(kswapd_init) | |
9eeff239 CL |
3587 | |
3588 | #ifdef CONFIG_NUMA | |
3589 | /* | |
3590 | * Zone reclaim mode | |
3591 | * | |
3592 | * If non-zero call zone_reclaim when the number of free pages falls below | |
3593 | * the watermarks. | |
9eeff239 CL |
3594 | */ |
3595 | int zone_reclaim_mode __read_mostly; | |
3596 | ||
1b2ffb78 | 3597 | #define RECLAIM_OFF 0 |
7d03431c | 3598 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 | 3599 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
95bbc0c7 | 3600 | #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ |
1b2ffb78 | 3601 | |
a92f7126 CL |
3602 | /* |
3603 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
3604 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
3605 | * a zone. | |
3606 | */ | |
3607 | #define ZONE_RECLAIM_PRIORITY 4 | |
3608 | ||
9614634f CL |
3609 | /* |
3610 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
3611 | * occur. | |
3612 | */ | |
3613 | int sysctl_min_unmapped_ratio = 1; | |
3614 | ||
0ff38490 CL |
3615 | /* |
3616 | * If the number of slab pages in a zone grows beyond this percentage then | |
3617 | * slab reclaim needs to occur. | |
3618 | */ | |
3619 | int sysctl_min_slab_ratio = 5; | |
3620 | ||
90afa5de MG |
3621 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
3622 | { | |
3623 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
3624 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
3625 | zone_page_state(zone, NR_ACTIVE_FILE); | |
3626 | ||
3627 | /* | |
3628 | * It's possible for there to be more file mapped pages than | |
3629 | * accounted for by the pages on the file LRU lists because | |
3630 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3631 | */ | |
3632 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3633 | } | |
3634 | ||
3635 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
3636 | static long zone_pagecache_reclaimable(struct zone *zone) | |
3637 | { | |
3638 | long nr_pagecache_reclaimable; | |
3639 | long delta = 0; | |
3640 | ||
3641 | /* | |
95bbc0c7 | 3642 | * If RECLAIM_UNMAP is set, then all file pages are considered |
90afa5de MG |
3643 | * potentially reclaimable. Otherwise, we have to worry about |
3644 | * pages like swapcache and zone_unmapped_file_pages() provides | |
3645 | * a better estimate | |
3646 | */ | |
95bbc0c7 | 3647 | if (zone_reclaim_mode & RECLAIM_UNMAP) |
90afa5de MG |
3648 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); |
3649 | else | |
3650 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
3651 | ||
3652 | /* If we can't clean pages, remove dirty pages from consideration */ | |
3653 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
3654 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
3655 | ||
3656 | /* Watch for any possible underflows due to delta */ | |
3657 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3658 | delta = nr_pagecache_reclaimable; | |
3659 | ||
3660 | return nr_pagecache_reclaimable - delta; | |
3661 | } | |
3662 | ||
9eeff239 CL |
3663 | /* |
3664 | * Try to free up some pages from this zone through reclaim. | |
3665 | */ | |
179e9639 | 3666 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3667 | { |
7fb2d46d | 3668 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3669 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3670 | struct task_struct *p = current; |
3671 | struct reclaim_state reclaim_state; | |
179e9639 | 3672 | struct scan_control sc = { |
62b726c1 | 3673 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
21caf2fc | 3674 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
bd2f6199 | 3675 | .order = order, |
9e3b2f8c | 3676 | .priority = ZONE_RECLAIM_PRIORITY, |
ee814fe2 | 3677 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), |
95bbc0c7 | 3678 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP), |
ee814fe2 | 3679 | .may_swap = 1, |
179e9639 | 3680 | }; |
9eeff239 | 3681 | |
9eeff239 | 3682 | cond_resched(); |
d4f7796e | 3683 | /* |
95bbc0c7 | 3684 | * We need to be able to allocate from the reserves for RECLAIM_UNMAP |
d4f7796e | 3685 | * and we also need to be able to write out pages for RECLAIM_WRITE |
95bbc0c7 | 3686 | * and RECLAIM_UNMAP. |
d4f7796e CL |
3687 | */ |
3688 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3689 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3690 | reclaim_state.reclaimed_slab = 0; |
3691 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3692 | |
90afa5de | 3693 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3694 | /* |
3695 | * Free memory by calling shrink zone with increasing | |
3696 | * priorities until we have enough memory freed. | |
3697 | */ | |
0ff38490 | 3698 | do { |
6b4f7799 | 3699 | shrink_zone(zone, &sc, true); |
9e3b2f8c | 3700 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); |
0ff38490 | 3701 | } |
c84db23c | 3702 | |
9eeff239 | 3703 | p->reclaim_state = NULL; |
d4f7796e | 3704 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3705 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3706 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3707 | } |
179e9639 AM |
3708 | |
3709 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3710 | { | |
179e9639 | 3711 | int node_id; |
d773ed6b | 3712 | int ret; |
179e9639 AM |
3713 | |
3714 | /* | |
0ff38490 CL |
3715 | * Zone reclaim reclaims unmapped file backed pages and |
3716 | * slab pages if we are over the defined limits. | |
34aa1330 | 3717 | * |
9614634f CL |
3718 | * A small portion of unmapped file backed pages is needed for |
3719 | * file I/O otherwise pages read by file I/O will be immediately | |
3720 | * thrown out if the zone is overallocated. So we do not reclaim | |
3721 | * if less than a specified percentage of the zone is used by | |
3722 | * unmapped file backed pages. | |
179e9639 | 3723 | */ |
90afa5de MG |
3724 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3725 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3726 | return ZONE_RECLAIM_FULL; |
179e9639 | 3727 | |
6e543d57 | 3728 | if (!zone_reclaimable(zone)) |
fa5e084e | 3729 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3730 | |
179e9639 | 3731 | /* |
d773ed6b | 3732 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3733 | */ |
d773ed6b | 3734 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3735 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3736 | |
3737 | /* | |
3738 | * Only run zone reclaim on the local zone or on zones that do not | |
3739 | * have associated processors. This will favor the local processor | |
3740 | * over remote processors and spread off node memory allocations | |
3741 | * as wide as possible. | |
3742 | */ | |
89fa3024 | 3743 | node_id = zone_to_nid(zone); |
37c0708d | 3744 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3745 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b | 3746 | |
57054651 | 3747 | if (test_and_set_bit(ZONE_RECLAIM_LOCKED, &zone->flags)) |
fa5e084e MG |
3748 | return ZONE_RECLAIM_NOSCAN; |
3749 | ||
d773ed6b | 3750 | ret = __zone_reclaim(zone, gfp_mask, order); |
57054651 | 3751 | clear_bit(ZONE_RECLAIM_LOCKED, &zone->flags); |
d773ed6b | 3752 | |
24cf7251 MG |
3753 | if (!ret) |
3754 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3755 | ||
d773ed6b | 3756 | return ret; |
179e9639 | 3757 | } |
9eeff239 | 3758 | #endif |
894bc310 | 3759 | |
894bc310 LS |
3760 | /* |
3761 | * page_evictable - test whether a page is evictable | |
3762 | * @page: the page to test | |
894bc310 LS |
3763 | * |
3764 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 3765 | * lists vs unevictable list. |
894bc310 LS |
3766 | * |
3767 | * Reasons page might not be evictable: | |
ba9ddf49 | 3768 | * (1) page's mapping marked unevictable |
b291f000 | 3769 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3770 | * |
894bc310 | 3771 | */ |
39b5f29a | 3772 | int page_evictable(struct page *page) |
894bc310 | 3773 | { |
39b5f29a | 3774 | return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); |
894bc310 | 3775 | } |
89e004ea | 3776 | |
85046579 | 3777 | #ifdef CONFIG_SHMEM |
89e004ea | 3778 | /** |
24513264 HD |
3779 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
3780 | * @pages: array of pages to check | |
3781 | * @nr_pages: number of pages to check | |
89e004ea | 3782 | * |
24513264 | 3783 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
3784 | * |
3785 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 3786 | */ |
24513264 | 3787 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 3788 | { |
925b7673 | 3789 | struct lruvec *lruvec; |
24513264 HD |
3790 | struct zone *zone = NULL; |
3791 | int pgscanned = 0; | |
3792 | int pgrescued = 0; | |
3793 | int i; | |
89e004ea | 3794 | |
24513264 HD |
3795 | for (i = 0; i < nr_pages; i++) { |
3796 | struct page *page = pages[i]; | |
3797 | struct zone *pagezone; | |
89e004ea | 3798 | |
24513264 HD |
3799 | pgscanned++; |
3800 | pagezone = page_zone(page); | |
3801 | if (pagezone != zone) { | |
3802 | if (zone) | |
3803 | spin_unlock_irq(&zone->lru_lock); | |
3804 | zone = pagezone; | |
3805 | spin_lock_irq(&zone->lru_lock); | |
3806 | } | |
fa9add64 | 3807 | lruvec = mem_cgroup_page_lruvec(page, zone); |
89e004ea | 3808 | |
24513264 HD |
3809 | if (!PageLRU(page) || !PageUnevictable(page)) |
3810 | continue; | |
89e004ea | 3811 | |
39b5f29a | 3812 | if (page_evictable(page)) { |
24513264 HD |
3813 | enum lru_list lru = page_lru_base_type(page); |
3814 | ||
309381fe | 3815 | VM_BUG_ON_PAGE(PageActive(page), page); |
24513264 | 3816 | ClearPageUnevictable(page); |
fa9add64 HD |
3817 | del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); |
3818 | add_page_to_lru_list(page, lruvec, lru); | |
24513264 | 3819 | pgrescued++; |
89e004ea | 3820 | } |
24513264 | 3821 | } |
89e004ea | 3822 | |
24513264 HD |
3823 | if (zone) { |
3824 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); | |
3825 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
3826 | spin_unlock_irq(&zone->lru_lock); | |
89e004ea | 3827 | } |
89e004ea | 3828 | } |
85046579 | 3829 | #endif /* CONFIG_SHMEM */ |