Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
17 | #include <linux/kernel_stat.h> |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
70ddf637 | 22 | #include <linux/vmpressure.h> |
e129b5c2 | 23 | #include <linux/vmstat.h> |
1da177e4 LT |
24 | #include <linux/file.h> |
25 | #include <linux/writeback.h> | |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
28 | buffer_heads_over_limit */ | |
29 | #include <linux/mm_inline.h> | |
1da177e4 LT |
30 | #include <linux/backing-dev.h> |
31 | #include <linux/rmap.h> | |
32 | #include <linux/topology.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cpuset.h> | |
3e7d3449 | 35 | #include <linux/compaction.h> |
1da177e4 LT |
36 | #include <linux/notifier.h> |
37 | #include <linux/rwsem.h> | |
248a0301 | 38 | #include <linux/delay.h> |
3218ae14 | 39 | #include <linux/kthread.h> |
7dfb7103 | 40 | #include <linux/freezer.h> |
66e1707b | 41 | #include <linux/memcontrol.h> |
873b4771 | 42 | #include <linux/delayacct.h> |
af936a16 | 43 | #include <linux/sysctl.h> |
929bea7c | 44 | #include <linux/oom.h> |
268bb0ce | 45 | #include <linux/prefetch.h> |
1da177e4 LT |
46 | |
47 | #include <asm/tlbflush.h> | |
48 | #include <asm/div64.h> | |
49 | ||
50 | #include <linux/swapops.h> | |
117aad1e | 51 | #include <linux/balloon_compaction.h> |
1da177e4 | 52 | |
0f8053a5 NP |
53 | #include "internal.h" |
54 | ||
33906bc5 MG |
55 | #define CREATE_TRACE_POINTS |
56 | #include <trace/events/vmscan.h> | |
57 | ||
1da177e4 | 58 | struct scan_control { |
1da177e4 LT |
59 | /* Incremented by the number of inactive pages that were scanned */ |
60 | unsigned long nr_scanned; | |
61 | ||
a79311c1 RR |
62 | /* Number of pages freed so far during a call to shrink_zones() */ |
63 | unsigned long nr_reclaimed; | |
64 | ||
22fba335 KM |
65 | /* How many pages shrink_list() should reclaim */ |
66 | unsigned long nr_to_reclaim; | |
67 | ||
7b51755c KM |
68 | unsigned long hibernation_mode; |
69 | ||
1da177e4 | 70 | /* This context's GFP mask */ |
6daa0e28 | 71 | gfp_t gfp_mask; |
1da177e4 LT |
72 | |
73 | int may_writepage; | |
74 | ||
a6dc60f8 JW |
75 | /* Can mapped pages be reclaimed? */ |
76 | int may_unmap; | |
f1fd1067 | 77 | |
2e2e4259 KM |
78 | /* Can pages be swapped as part of reclaim? */ |
79 | int may_swap; | |
80 | ||
5ad333eb | 81 | int order; |
66e1707b | 82 | |
9e3b2f8c KK |
83 | /* Scan (total_size >> priority) pages at once */ |
84 | int priority; | |
85 | ||
f16015fb JW |
86 | /* |
87 | * The memory cgroup that hit its limit and as a result is the | |
88 | * primary target of this reclaim invocation. | |
89 | */ | |
90 | struct mem_cgroup *target_mem_cgroup; | |
66e1707b | 91 | |
327c0e96 KH |
92 | /* |
93 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
94 | * are scanned. | |
95 | */ | |
96 | nodemask_t *nodemask; | |
1da177e4 LT |
97 | }; |
98 | ||
1da177e4 LT |
99 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
100 | ||
101 | #ifdef ARCH_HAS_PREFETCH | |
102 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
103 | do { \ | |
104 | if ((_page)->lru.prev != _base) { \ | |
105 | struct page *prev; \ | |
106 | \ | |
107 | prev = lru_to_page(&(_page->lru)); \ | |
108 | prefetch(&prev->_field); \ | |
109 | } \ | |
110 | } while (0) | |
111 | #else | |
112 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
113 | #endif | |
114 | ||
115 | #ifdef ARCH_HAS_PREFETCHW | |
116 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
117 | do { \ | |
118 | if ((_page)->lru.prev != _base) { \ | |
119 | struct page *prev; \ | |
120 | \ | |
121 | prev = lru_to_page(&(_page->lru)); \ | |
122 | prefetchw(&prev->_field); \ | |
123 | } \ | |
124 | } while (0) | |
125 | #else | |
126 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
127 | #endif | |
128 | ||
129 | /* | |
130 | * From 0 .. 100. Higher means more swappy. | |
131 | */ | |
132 | int vm_swappiness = 60; | |
b21e0b90 | 133 | unsigned long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
134 | |
135 | static LIST_HEAD(shrinker_list); | |
136 | static DECLARE_RWSEM(shrinker_rwsem); | |
137 | ||
c255a458 | 138 | #ifdef CONFIG_MEMCG |
89b5fae5 JW |
139 | static bool global_reclaim(struct scan_control *sc) |
140 | { | |
f16015fb | 141 | return !sc->target_mem_cgroup; |
89b5fae5 | 142 | } |
91a45470 | 143 | #else |
89b5fae5 JW |
144 | static bool global_reclaim(struct scan_control *sc) |
145 | { | |
146 | return true; | |
147 | } | |
91a45470 KH |
148 | #endif |
149 | ||
6e543d57 LD |
150 | unsigned long zone_reclaimable_pages(struct zone *zone) |
151 | { | |
152 | int nr; | |
153 | ||
154 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
155 | zone_page_state(zone, NR_INACTIVE_FILE); | |
156 | ||
157 | if (get_nr_swap_pages() > 0) | |
158 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
159 | zone_page_state(zone, NR_INACTIVE_ANON); | |
160 | ||
161 | return nr; | |
162 | } | |
163 | ||
164 | bool zone_reclaimable(struct zone *zone) | |
165 | { | |
166 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
167 | } | |
168 | ||
4d7dcca2 | 169 | static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru) |
c9f299d9 | 170 | { |
c3c787e8 | 171 | if (!mem_cgroup_disabled()) |
4d7dcca2 | 172 | return mem_cgroup_get_lru_size(lruvec, lru); |
a3d8e054 | 173 | |
074291fe | 174 | return zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru); |
c9f299d9 KM |
175 | } |
176 | ||
1da177e4 | 177 | /* |
1d3d4437 | 178 | * Add a shrinker callback to be called from the vm. |
1da177e4 | 179 | */ |
1d3d4437 | 180 | int register_shrinker(struct shrinker *shrinker) |
1da177e4 | 181 | { |
1d3d4437 GC |
182 | size_t size = sizeof(*shrinker->nr_deferred); |
183 | ||
184 | /* | |
185 | * If we only have one possible node in the system anyway, save | |
186 | * ourselves the trouble and disable NUMA aware behavior. This way we | |
187 | * will save memory and some small loop time later. | |
188 | */ | |
189 | if (nr_node_ids == 1) | |
190 | shrinker->flags &= ~SHRINKER_NUMA_AWARE; | |
191 | ||
192 | if (shrinker->flags & SHRINKER_NUMA_AWARE) | |
193 | size *= nr_node_ids; | |
194 | ||
195 | shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); | |
196 | if (!shrinker->nr_deferred) | |
197 | return -ENOMEM; | |
198 | ||
8e1f936b RR |
199 | down_write(&shrinker_rwsem); |
200 | list_add_tail(&shrinker->list, &shrinker_list); | |
201 | up_write(&shrinker_rwsem); | |
1d3d4437 | 202 | return 0; |
1da177e4 | 203 | } |
8e1f936b | 204 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
205 | |
206 | /* | |
207 | * Remove one | |
208 | */ | |
8e1f936b | 209 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
210 | { |
211 | down_write(&shrinker_rwsem); | |
212 | list_del(&shrinker->list); | |
213 | up_write(&shrinker_rwsem); | |
ae393321 | 214 | kfree(shrinker->nr_deferred); |
1da177e4 | 215 | } |
8e1f936b | 216 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
217 | |
218 | #define SHRINK_BATCH 128 | |
1d3d4437 GC |
219 | |
220 | static unsigned long | |
221 | shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker, | |
222 | unsigned long nr_pages_scanned, unsigned long lru_pages) | |
223 | { | |
224 | unsigned long freed = 0; | |
225 | unsigned long long delta; | |
226 | long total_scan; | |
227 | long max_pass; | |
228 | long nr; | |
229 | long new_nr; | |
230 | int nid = shrinkctl->nid; | |
231 | long batch_size = shrinker->batch ? shrinker->batch | |
232 | : SHRINK_BATCH; | |
233 | ||
a0b02131 | 234 | max_pass = shrinker->count_objects(shrinker, shrinkctl); |
1d3d4437 GC |
235 | if (max_pass == 0) |
236 | return 0; | |
237 | ||
238 | /* | |
239 | * copy the current shrinker scan count into a local variable | |
240 | * and zero it so that other concurrent shrinker invocations | |
241 | * don't also do this scanning work. | |
242 | */ | |
243 | nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); | |
244 | ||
245 | total_scan = nr; | |
246 | delta = (4 * nr_pages_scanned) / shrinker->seeks; | |
247 | delta *= max_pass; | |
248 | do_div(delta, lru_pages + 1); | |
249 | total_scan += delta; | |
250 | if (total_scan < 0) { | |
251 | printk(KERN_ERR | |
252 | "shrink_slab: %pF negative objects to delete nr=%ld\n", | |
a0b02131 | 253 | shrinker->scan_objects, total_scan); |
1d3d4437 GC |
254 | total_scan = max_pass; |
255 | } | |
256 | ||
257 | /* | |
258 | * We need to avoid excessive windup on filesystem shrinkers | |
259 | * due to large numbers of GFP_NOFS allocations causing the | |
260 | * shrinkers to return -1 all the time. This results in a large | |
261 | * nr being built up so when a shrink that can do some work | |
262 | * comes along it empties the entire cache due to nr >>> | |
263 | * max_pass. This is bad for sustaining a working set in | |
264 | * memory. | |
265 | * | |
266 | * Hence only allow the shrinker to scan the entire cache when | |
267 | * a large delta change is calculated directly. | |
268 | */ | |
269 | if (delta < max_pass / 4) | |
270 | total_scan = min(total_scan, max_pass / 2); | |
271 | ||
272 | /* | |
273 | * Avoid risking looping forever due to too large nr value: | |
274 | * never try to free more than twice the estimate number of | |
275 | * freeable entries. | |
276 | */ | |
277 | if (total_scan > max_pass * 2) | |
278 | total_scan = max_pass * 2; | |
279 | ||
280 | trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, | |
281 | nr_pages_scanned, lru_pages, | |
282 | max_pass, delta, total_scan); | |
283 | ||
0b1fb40a VD |
284 | /* |
285 | * Normally, we should not scan less than batch_size objects in one | |
286 | * pass to avoid too frequent shrinker calls, but if the slab has less | |
287 | * than batch_size objects in total and we are really tight on memory, | |
288 | * we will try to reclaim all available objects, otherwise we can end | |
289 | * up failing allocations although there are plenty of reclaimable | |
290 | * objects spread over several slabs with usage less than the | |
291 | * batch_size. | |
292 | * | |
293 | * We detect the "tight on memory" situations by looking at the total | |
294 | * number of objects we want to scan (total_scan). If it is greater | |
295 | * than the total number of objects on slab (max_pass), we must be | |
296 | * scanning at high prio and therefore should try to reclaim as much as | |
297 | * possible. | |
298 | */ | |
299 | while (total_scan >= batch_size || | |
300 | total_scan >= max_pass) { | |
a0b02131 | 301 | unsigned long ret; |
0b1fb40a | 302 | unsigned long nr_to_scan = min(batch_size, total_scan); |
1d3d4437 | 303 | |
0b1fb40a | 304 | shrinkctl->nr_to_scan = nr_to_scan; |
a0b02131 DC |
305 | ret = shrinker->scan_objects(shrinker, shrinkctl); |
306 | if (ret == SHRINK_STOP) | |
307 | break; | |
308 | freed += ret; | |
1d3d4437 | 309 | |
0b1fb40a VD |
310 | count_vm_events(SLABS_SCANNED, nr_to_scan); |
311 | total_scan -= nr_to_scan; | |
1d3d4437 GC |
312 | |
313 | cond_resched(); | |
314 | } | |
315 | ||
316 | /* | |
317 | * move the unused scan count back into the shrinker in a | |
318 | * manner that handles concurrent updates. If we exhausted the | |
319 | * scan, there is no need to do an update. | |
320 | */ | |
321 | if (total_scan > 0) | |
322 | new_nr = atomic_long_add_return(total_scan, | |
323 | &shrinker->nr_deferred[nid]); | |
324 | else | |
325 | new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); | |
326 | ||
327 | trace_mm_shrink_slab_end(shrinker, freed, nr, new_nr); | |
328 | return freed; | |
1495f230 YH |
329 | } |
330 | ||
1da177e4 LT |
331 | /* |
332 | * Call the shrink functions to age shrinkable caches | |
333 | * | |
334 | * Here we assume it costs one seek to replace a lru page and that it also | |
335 | * takes a seek to recreate a cache object. With this in mind we age equal | |
336 | * percentages of the lru and ageable caches. This should balance the seeks | |
337 | * generated by these structures. | |
338 | * | |
183ff22b | 339 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
340 | * slab to avoid swapping. |
341 | * | |
342 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
343 | * | |
344 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
345 | * are eligible for the caller's allocation attempt. It is used for balancing | |
346 | * slab reclaim versus page reclaim. | |
b15e0905 | 347 | * |
348 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 349 | */ |
24f7c6b9 | 350 | unsigned long shrink_slab(struct shrink_control *shrinkctl, |
1495f230 | 351 | unsigned long nr_pages_scanned, |
a09ed5e0 | 352 | unsigned long lru_pages) |
1da177e4 LT |
353 | { |
354 | struct shrinker *shrinker; | |
24f7c6b9 | 355 | unsigned long freed = 0; |
1da177e4 | 356 | |
1495f230 YH |
357 | if (nr_pages_scanned == 0) |
358 | nr_pages_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 359 | |
f06590bd | 360 | if (!down_read_trylock(&shrinker_rwsem)) { |
24f7c6b9 DC |
361 | /* |
362 | * If we would return 0, our callers would understand that we | |
363 | * have nothing else to shrink and give up trying. By returning | |
364 | * 1 we keep it going and assume we'll be able to shrink next | |
365 | * time. | |
366 | */ | |
367 | freed = 1; | |
f06590bd MK |
368 | goto out; |
369 | } | |
1da177e4 LT |
370 | |
371 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
1d3d4437 GC |
372 | for_each_node_mask(shrinkctl->nid, shrinkctl->nodes_to_scan) { |
373 | if (!node_online(shrinkctl->nid)) | |
374 | continue; | |
1da177e4 | 375 | |
1d3d4437 GC |
376 | if (!(shrinker->flags & SHRINKER_NUMA_AWARE) && |
377 | (shrinkctl->nid != 0)) | |
1da177e4 | 378 | break; |
1da177e4 | 379 | |
1d3d4437 GC |
380 | freed += shrink_slab_node(shrinkctl, shrinker, |
381 | nr_pages_scanned, lru_pages); | |
1da177e4 | 382 | |
1da177e4 | 383 | } |
1da177e4 LT |
384 | } |
385 | up_read(&shrinker_rwsem); | |
f06590bd MK |
386 | out: |
387 | cond_resched(); | |
24f7c6b9 | 388 | return freed; |
1da177e4 LT |
389 | } |
390 | ||
1da177e4 LT |
391 | static inline int is_page_cache_freeable(struct page *page) |
392 | { | |
ceddc3a5 JW |
393 | /* |
394 | * A freeable page cache page is referenced only by the caller | |
395 | * that isolated the page, the page cache radix tree and | |
396 | * optional buffer heads at page->private. | |
397 | */ | |
edcf4748 | 398 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
399 | } |
400 | ||
7d3579e8 KM |
401 | static int may_write_to_queue(struct backing_dev_info *bdi, |
402 | struct scan_control *sc) | |
1da177e4 | 403 | { |
930d9152 | 404 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
405 | return 1; |
406 | if (!bdi_write_congested(bdi)) | |
407 | return 1; | |
408 | if (bdi == current->backing_dev_info) | |
409 | return 1; | |
410 | return 0; | |
411 | } | |
412 | ||
413 | /* | |
414 | * We detected a synchronous write error writing a page out. Probably | |
415 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
416 | * fsync(), msync() or close(). | |
417 | * | |
418 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
419 | * prevents it from being freed up. But we have a ref on the page and once | |
420 | * that page is locked, the mapping is pinned. | |
421 | * | |
422 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
423 | * __GFP_FS. | |
424 | */ | |
425 | static void handle_write_error(struct address_space *mapping, | |
426 | struct page *page, int error) | |
427 | { | |
7eaceacc | 428 | lock_page(page); |
3e9f45bd GC |
429 | if (page_mapping(page) == mapping) |
430 | mapping_set_error(mapping, error); | |
1da177e4 LT |
431 | unlock_page(page); |
432 | } | |
433 | ||
04e62a29 CL |
434 | /* possible outcome of pageout() */ |
435 | typedef enum { | |
436 | /* failed to write page out, page is locked */ | |
437 | PAGE_KEEP, | |
438 | /* move page to the active list, page is locked */ | |
439 | PAGE_ACTIVATE, | |
440 | /* page has been sent to the disk successfully, page is unlocked */ | |
441 | PAGE_SUCCESS, | |
442 | /* page is clean and locked */ | |
443 | PAGE_CLEAN, | |
444 | } pageout_t; | |
445 | ||
1da177e4 | 446 | /* |
1742f19f AM |
447 | * pageout is called by shrink_page_list() for each dirty page. |
448 | * Calls ->writepage(). | |
1da177e4 | 449 | */ |
c661b078 | 450 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 451 | struct scan_control *sc) |
1da177e4 LT |
452 | { |
453 | /* | |
454 | * If the page is dirty, only perform writeback if that write | |
455 | * will be non-blocking. To prevent this allocation from being | |
456 | * stalled by pagecache activity. But note that there may be | |
457 | * stalls if we need to run get_block(). We could test | |
458 | * PagePrivate for that. | |
459 | * | |
6aceb53b | 460 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
461 | * this page's queue, we can perform writeback even if that |
462 | * will block. | |
463 | * | |
464 | * If the page is swapcache, write it back even if that would | |
465 | * block, for some throttling. This happens by accident, because | |
466 | * swap_backing_dev_info is bust: it doesn't reflect the | |
467 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
468 | */ |
469 | if (!is_page_cache_freeable(page)) | |
470 | return PAGE_KEEP; | |
471 | if (!mapping) { | |
472 | /* | |
473 | * Some data journaling orphaned pages can have | |
474 | * page->mapping == NULL while being dirty with clean buffers. | |
475 | */ | |
266cf658 | 476 | if (page_has_private(page)) { |
1da177e4 LT |
477 | if (try_to_free_buffers(page)) { |
478 | ClearPageDirty(page); | |
d40cee24 | 479 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
480 | return PAGE_CLEAN; |
481 | } | |
482 | } | |
483 | return PAGE_KEEP; | |
484 | } | |
485 | if (mapping->a_ops->writepage == NULL) | |
486 | return PAGE_ACTIVATE; | |
0e093d99 | 487 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
488 | return PAGE_KEEP; |
489 | ||
490 | if (clear_page_dirty_for_io(page)) { | |
491 | int res; | |
492 | struct writeback_control wbc = { | |
493 | .sync_mode = WB_SYNC_NONE, | |
494 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
495 | .range_start = 0, |
496 | .range_end = LLONG_MAX, | |
1da177e4 LT |
497 | .for_reclaim = 1, |
498 | }; | |
499 | ||
500 | SetPageReclaim(page); | |
501 | res = mapping->a_ops->writepage(page, &wbc); | |
502 | if (res < 0) | |
503 | handle_write_error(mapping, page, res); | |
994fc28c | 504 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
505 | ClearPageReclaim(page); |
506 | return PAGE_ACTIVATE; | |
507 | } | |
c661b078 | 508 | |
1da177e4 LT |
509 | if (!PageWriteback(page)) { |
510 | /* synchronous write or broken a_ops? */ | |
511 | ClearPageReclaim(page); | |
512 | } | |
23b9da55 | 513 | trace_mm_vmscan_writepage(page, trace_reclaim_flags(page)); |
e129b5c2 | 514 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
515 | return PAGE_SUCCESS; |
516 | } | |
517 | ||
518 | return PAGE_CLEAN; | |
519 | } | |
520 | ||
a649fd92 | 521 | /* |
e286781d NP |
522 | * Same as remove_mapping, but if the page is removed from the mapping, it |
523 | * gets returned with a refcount of 0. | |
a649fd92 | 524 | */ |
e286781d | 525 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 526 | { |
28e4d965 NP |
527 | BUG_ON(!PageLocked(page)); |
528 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 529 | |
19fd6231 | 530 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 531 | /* |
0fd0e6b0 NP |
532 | * The non racy check for a busy page. |
533 | * | |
534 | * Must be careful with the order of the tests. When someone has | |
535 | * a ref to the page, it may be possible that they dirty it then | |
536 | * drop the reference. So if PageDirty is tested before page_count | |
537 | * here, then the following race may occur: | |
538 | * | |
539 | * get_user_pages(&page); | |
540 | * [user mapping goes away] | |
541 | * write_to(page); | |
542 | * !PageDirty(page) [good] | |
543 | * SetPageDirty(page); | |
544 | * put_page(page); | |
545 | * !page_count(page) [good, discard it] | |
546 | * | |
547 | * [oops, our write_to data is lost] | |
548 | * | |
549 | * Reversing the order of the tests ensures such a situation cannot | |
550 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
551 | * load is not satisfied before that of page->_count. | |
552 | * | |
553 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
554 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 555 | */ |
e286781d | 556 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 557 | goto cannot_free; |
e286781d NP |
558 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
559 | if (unlikely(PageDirty(page))) { | |
560 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 561 | goto cannot_free; |
e286781d | 562 | } |
49d2e9cc CL |
563 | |
564 | if (PageSwapCache(page)) { | |
565 | swp_entry_t swap = { .val = page_private(page) }; | |
566 | __delete_from_swap_cache(page); | |
19fd6231 | 567 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 568 | swapcache_free(swap, page); |
e286781d | 569 | } else { |
6072d13c LT |
570 | void (*freepage)(struct page *); |
571 | ||
572 | freepage = mapping->a_ops->freepage; | |
573 | ||
e64a782f | 574 | __delete_from_page_cache(page); |
19fd6231 | 575 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 576 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
577 | |
578 | if (freepage != NULL) | |
579 | freepage(page); | |
49d2e9cc CL |
580 | } |
581 | ||
49d2e9cc CL |
582 | return 1; |
583 | ||
584 | cannot_free: | |
19fd6231 | 585 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
586 | return 0; |
587 | } | |
588 | ||
e286781d NP |
589 | /* |
590 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
591 | * someone else has a ref on the page, abort and return 0. If it was | |
592 | * successfully detached, return 1. Assumes the caller has a single ref on | |
593 | * this page. | |
594 | */ | |
595 | int remove_mapping(struct address_space *mapping, struct page *page) | |
596 | { | |
597 | if (__remove_mapping(mapping, page)) { | |
598 | /* | |
599 | * Unfreezing the refcount with 1 rather than 2 effectively | |
600 | * drops the pagecache ref for us without requiring another | |
601 | * atomic operation. | |
602 | */ | |
603 | page_unfreeze_refs(page, 1); | |
604 | return 1; | |
605 | } | |
606 | return 0; | |
607 | } | |
608 | ||
894bc310 LS |
609 | /** |
610 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
611 | * @page: page to be put back to appropriate lru list | |
612 | * | |
613 | * Add previously isolated @page to appropriate LRU list. | |
614 | * Page may still be unevictable for other reasons. | |
615 | * | |
616 | * lru_lock must not be held, interrupts must be enabled. | |
617 | */ | |
894bc310 LS |
618 | void putback_lru_page(struct page *page) |
619 | { | |
0ec3b74c | 620 | bool is_unevictable; |
bbfd28ee | 621 | int was_unevictable = PageUnevictable(page); |
894bc310 | 622 | |
309381fe | 623 | VM_BUG_ON_PAGE(PageLRU(page), page); |
894bc310 LS |
624 | |
625 | redo: | |
626 | ClearPageUnevictable(page); | |
627 | ||
39b5f29a | 628 | if (page_evictable(page)) { |
894bc310 LS |
629 | /* |
630 | * For evictable pages, we can use the cache. | |
631 | * In event of a race, worst case is we end up with an | |
632 | * unevictable page on [in]active list. | |
633 | * We know how to handle that. | |
634 | */ | |
0ec3b74c | 635 | is_unevictable = false; |
c53954a0 | 636 | lru_cache_add(page); |
894bc310 LS |
637 | } else { |
638 | /* | |
639 | * Put unevictable pages directly on zone's unevictable | |
640 | * list. | |
641 | */ | |
0ec3b74c | 642 | is_unevictable = true; |
894bc310 | 643 | add_page_to_unevictable_list(page); |
6a7b9548 | 644 | /* |
21ee9f39 MK |
645 | * When racing with an mlock or AS_UNEVICTABLE clearing |
646 | * (page is unlocked) make sure that if the other thread | |
647 | * does not observe our setting of PG_lru and fails | |
24513264 | 648 | * isolation/check_move_unevictable_pages, |
21ee9f39 | 649 | * we see PG_mlocked/AS_UNEVICTABLE cleared below and move |
6a7b9548 JW |
650 | * the page back to the evictable list. |
651 | * | |
21ee9f39 | 652 | * The other side is TestClearPageMlocked() or shmem_lock(). |
6a7b9548 JW |
653 | */ |
654 | smp_mb(); | |
894bc310 | 655 | } |
894bc310 LS |
656 | |
657 | /* | |
658 | * page's status can change while we move it among lru. If an evictable | |
659 | * page is on unevictable list, it never be freed. To avoid that, | |
660 | * check after we added it to the list, again. | |
661 | */ | |
0ec3b74c | 662 | if (is_unevictable && page_evictable(page)) { |
894bc310 LS |
663 | if (!isolate_lru_page(page)) { |
664 | put_page(page); | |
665 | goto redo; | |
666 | } | |
667 | /* This means someone else dropped this page from LRU | |
668 | * So, it will be freed or putback to LRU again. There is | |
669 | * nothing to do here. | |
670 | */ | |
671 | } | |
672 | ||
0ec3b74c | 673 | if (was_unevictable && !is_unevictable) |
bbfd28ee | 674 | count_vm_event(UNEVICTABLE_PGRESCUED); |
0ec3b74c | 675 | else if (!was_unevictable && is_unevictable) |
bbfd28ee LS |
676 | count_vm_event(UNEVICTABLE_PGCULLED); |
677 | ||
894bc310 LS |
678 | put_page(page); /* drop ref from isolate */ |
679 | } | |
680 | ||
dfc8d636 JW |
681 | enum page_references { |
682 | PAGEREF_RECLAIM, | |
683 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 684 | PAGEREF_KEEP, |
dfc8d636 JW |
685 | PAGEREF_ACTIVATE, |
686 | }; | |
687 | ||
688 | static enum page_references page_check_references(struct page *page, | |
689 | struct scan_control *sc) | |
690 | { | |
64574746 | 691 | int referenced_ptes, referenced_page; |
dfc8d636 | 692 | unsigned long vm_flags; |
dfc8d636 | 693 | |
c3ac9a8a JW |
694 | referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, |
695 | &vm_flags); | |
64574746 | 696 | referenced_page = TestClearPageReferenced(page); |
dfc8d636 | 697 | |
dfc8d636 JW |
698 | /* |
699 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
700 | * move the page to the unevictable list. | |
701 | */ | |
702 | if (vm_flags & VM_LOCKED) | |
703 | return PAGEREF_RECLAIM; | |
704 | ||
64574746 | 705 | if (referenced_ptes) { |
e4898273 | 706 | if (PageSwapBacked(page)) |
64574746 JW |
707 | return PAGEREF_ACTIVATE; |
708 | /* | |
709 | * All mapped pages start out with page table | |
710 | * references from the instantiating fault, so we need | |
711 | * to look twice if a mapped file page is used more | |
712 | * than once. | |
713 | * | |
714 | * Mark it and spare it for another trip around the | |
715 | * inactive list. Another page table reference will | |
716 | * lead to its activation. | |
717 | * | |
718 | * Note: the mark is set for activated pages as well | |
719 | * so that recently deactivated but used pages are | |
720 | * quickly recovered. | |
721 | */ | |
722 | SetPageReferenced(page); | |
723 | ||
34dbc67a | 724 | if (referenced_page || referenced_ptes > 1) |
64574746 JW |
725 | return PAGEREF_ACTIVATE; |
726 | ||
c909e993 KK |
727 | /* |
728 | * Activate file-backed executable pages after first usage. | |
729 | */ | |
730 | if (vm_flags & VM_EXEC) | |
731 | return PAGEREF_ACTIVATE; | |
732 | ||
64574746 JW |
733 | return PAGEREF_KEEP; |
734 | } | |
dfc8d636 JW |
735 | |
736 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 737 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
738 | return PAGEREF_RECLAIM_CLEAN; |
739 | ||
740 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
741 | } |
742 | ||
e2be15f6 MG |
743 | /* Check if a page is dirty or under writeback */ |
744 | static void page_check_dirty_writeback(struct page *page, | |
745 | bool *dirty, bool *writeback) | |
746 | { | |
b4597226 MG |
747 | struct address_space *mapping; |
748 | ||
e2be15f6 MG |
749 | /* |
750 | * Anonymous pages are not handled by flushers and must be written | |
751 | * from reclaim context. Do not stall reclaim based on them | |
752 | */ | |
753 | if (!page_is_file_cache(page)) { | |
754 | *dirty = false; | |
755 | *writeback = false; | |
756 | return; | |
757 | } | |
758 | ||
759 | /* By default assume that the page flags are accurate */ | |
760 | *dirty = PageDirty(page); | |
761 | *writeback = PageWriteback(page); | |
b4597226 MG |
762 | |
763 | /* Verify dirty/writeback state if the filesystem supports it */ | |
764 | if (!page_has_private(page)) | |
765 | return; | |
766 | ||
767 | mapping = page_mapping(page); | |
768 | if (mapping && mapping->a_ops->is_dirty_writeback) | |
769 | mapping->a_ops->is_dirty_writeback(page, dirty, writeback); | |
e2be15f6 MG |
770 | } |
771 | ||
1da177e4 | 772 | /* |
1742f19f | 773 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 774 | */ |
1742f19f | 775 | static unsigned long shrink_page_list(struct list_head *page_list, |
6a18adb3 | 776 | struct zone *zone, |
f84f6e2b | 777 | struct scan_control *sc, |
02c6de8d | 778 | enum ttu_flags ttu_flags, |
8e950282 | 779 | unsigned long *ret_nr_dirty, |
d43006d5 | 780 | unsigned long *ret_nr_unqueued_dirty, |
8e950282 | 781 | unsigned long *ret_nr_congested, |
02c6de8d | 782 | unsigned long *ret_nr_writeback, |
b1a6f21e | 783 | unsigned long *ret_nr_immediate, |
02c6de8d | 784 | bool force_reclaim) |
1da177e4 LT |
785 | { |
786 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 787 | LIST_HEAD(free_pages); |
1da177e4 | 788 | int pgactivate = 0; |
d43006d5 | 789 | unsigned long nr_unqueued_dirty = 0; |
0e093d99 MG |
790 | unsigned long nr_dirty = 0; |
791 | unsigned long nr_congested = 0; | |
05ff5137 | 792 | unsigned long nr_reclaimed = 0; |
92df3a72 | 793 | unsigned long nr_writeback = 0; |
b1a6f21e | 794 | unsigned long nr_immediate = 0; |
1da177e4 LT |
795 | |
796 | cond_resched(); | |
797 | ||
69980e31 | 798 | mem_cgroup_uncharge_start(); |
1da177e4 LT |
799 | while (!list_empty(page_list)) { |
800 | struct address_space *mapping; | |
801 | struct page *page; | |
802 | int may_enter_fs; | |
02c6de8d | 803 | enum page_references references = PAGEREF_RECLAIM_CLEAN; |
e2be15f6 | 804 | bool dirty, writeback; |
1da177e4 LT |
805 | |
806 | cond_resched(); | |
807 | ||
808 | page = lru_to_page(page_list); | |
809 | list_del(&page->lru); | |
810 | ||
529ae9aa | 811 | if (!trylock_page(page)) |
1da177e4 LT |
812 | goto keep; |
813 | ||
309381fe SL |
814 | VM_BUG_ON_PAGE(PageActive(page), page); |
815 | VM_BUG_ON_PAGE(page_zone(page) != zone, page); | |
1da177e4 LT |
816 | |
817 | sc->nr_scanned++; | |
80e43426 | 818 | |
39b5f29a | 819 | if (unlikely(!page_evictable(page))) |
b291f000 | 820 | goto cull_mlocked; |
894bc310 | 821 | |
a6dc60f8 | 822 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
823 | goto keep_locked; |
824 | ||
1da177e4 LT |
825 | /* Double the slab pressure for mapped and swapcache pages */ |
826 | if (page_mapped(page) || PageSwapCache(page)) | |
827 | sc->nr_scanned++; | |
828 | ||
c661b078 AW |
829 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
830 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
831 | ||
e2be15f6 MG |
832 | /* |
833 | * The number of dirty pages determines if a zone is marked | |
834 | * reclaim_congested which affects wait_iff_congested. kswapd | |
835 | * will stall and start writing pages if the tail of the LRU | |
836 | * is all dirty unqueued pages. | |
837 | */ | |
838 | page_check_dirty_writeback(page, &dirty, &writeback); | |
839 | if (dirty || writeback) | |
840 | nr_dirty++; | |
841 | ||
842 | if (dirty && !writeback) | |
843 | nr_unqueued_dirty++; | |
844 | ||
d04e8acd MG |
845 | /* |
846 | * Treat this page as congested if the underlying BDI is or if | |
847 | * pages are cycling through the LRU so quickly that the | |
848 | * pages marked for immediate reclaim are making it to the | |
849 | * end of the LRU a second time. | |
850 | */ | |
e2be15f6 | 851 | mapping = page_mapping(page); |
d04e8acd MG |
852 | if ((mapping && bdi_write_congested(mapping->backing_dev_info)) || |
853 | (writeback && PageReclaim(page))) | |
e2be15f6 MG |
854 | nr_congested++; |
855 | ||
283aba9f MG |
856 | /* |
857 | * If a page at the tail of the LRU is under writeback, there | |
858 | * are three cases to consider. | |
859 | * | |
860 | * 1) If reclaim is encountering an excessive number of pages | |
861 | * under writeback and this page is both under writeback and | |
862 | * PageReclaim then it indicates that pages are being queued | |
863 | * for IO but are being recycled through the LRU before the | |
864 | * IO can complete. Waiting on the page itself risks an | |
865 | * indefinite stall if it is impossible to writeback the | |
866 | * page due to IO error or disconnected storage so instead | |
b1a6f21e MG |
867 | * note that the LRU is being scanned too quickly and the |
868 | * caller can stall after page list has been processed. | |
283aba9f MG |
869 | * |
870 | * 2) Global reclaim encounters a page, memcg encounters a | |
871 | * page that is not marked for immediate reclaim or | |
872 | * the caller does not have __GFP_IO. In this case mark | |
873 | * the page for immediate reclaim and continue scanning. | |
874 | * | |
875 | * __GFP_IO is checked because a loop driver thread might | |
876 | * enter reclaim, and deadlock if it waits on a page for | |
877 | * which it is needed to do the write (loop masks off | |
878 | * __GFP_IO|__GFP_FS for this reason); but more thought | |
879 | * would probably show more reasons. | |
880 | * | |
881 | * Don't require __GFP_FS, since we're not going into the | |
882 | * FS, just waiting on its writeback completion. Worryingly, | |
883 | * ext4 gfs2 and xfs allocate pages with | |
884 | * grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so testing | |
885 | * may_enter_fs here is liable to OOM on them. | |
886 | * | |
887 | * 3) memcg encounters a page that is not already marked | |
888 | * PageReclaim. memcg does not have any dirty pages | |
889 | * throttling so we could easily OOM just because too many | |
890 | * pages are in writeback and there is nothing else to | |
891 | * reclaim. Wait for the writeback to complete. | |
892 | */ | |
c661b078 | 893 | if (PageWriteback(page)) { |
283aba9f MG |
894 | /* Case 1 above */ |
895 | if (current_is_kswapd() && | |
896 | PageReclaim(page) && | |
897 | zone_is_reclaim_writeback(zone)) { | |
b1a6f21e MG |
898 | nr_immediate++; |
899 | goto keep_locked; | |
283aba9f MG |
900 | |
901 | /* Case 2 above */ | |
902 | } else if (global_reclaim(sc) || | |
c3b94f44 HD |
903 | !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) { |
904 | /* | |
905 | * This is slightly racy - end_page_writeback() | |
906 | * might have just cleared PageReclaim, then | |
907 | * setting PageReclaim here end up interpreted | |
908 | * as PageReadahead - but that does not matter | |
909 | * enough to care. What we do want is for this | |
910 | * page to have PageReclaim set next time memcg | |
911 | * reclaim reaches the tests above, so it will | |
912 | * then wait_on_page_writeback() to avoid OOM; | |
913 | * and it's also appropriate in global reclaim. | |
914 | */ | |
915 | SetPageReclaim(page); | |
e62e384e | 916 | nr_writeback++; |
283aba9f | 917 | |
c3b94f44 | 918 | goto keep_locked; |
283aba9f MG |
919 | |
920 | /* Case 3 above */ | |
921 | } else { | |
922 | wait_on_page_writeback(page); | |
e62e384e | 923 | } |
c661b078 | 924 | } |
1da177e4 | 925 | |
02c6de8d MK |
926 | if (!force_reclaim) |
927 | references = page_check_references(page, sc); | |
928 | ||
dfc8d636 JW |
929 | switch (references) { |
930 | case PAGEREF_ACTIVATE: | |
1da177e4 | 931 | goto activate_locked; |
64574746 JW |
932 | case PAGEREF_KEEP: |
933 | goto keep_locked; | |
dfc8d636 JW |
934 | case PAGEREF_RECLAIM: |
935 | case PAGEREF_RECLAIM_CLEAN: | |
936 | ; /* try to reclaim the page below */ | |
937 | } | |
1da177e4 | 938 | |
1da177e4 LT |
939 | /* |
940 | * Anonymous process memory has backing store? | |
941 | * Try to allocate it some swap space here. | |
942 | */ | |
b291f000 | 943 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
944 | if (!(sc->gfp_mask & __GFP_IO)) |
945 | goto keep_locked; | |
5bc7b8ac | 946 | if (!add_to_swap(page, page_list)) |
1da177e4 | 947 | goto activate_locked; |
63eb6b93 | 948 | may_enter_fs = 1; |
1da177e4 | 949 | |
e2be15f6 MG |
950 | /* Adding to swap updated mapping */ |
951 | mapping = page_mapping(page); | |
952 | } | |
1da177e4 LT |
953 | |
954 | /* | |
955 | * The page is mapped into the page tables of one or more | |
956 | * processes. Try to unmap it here. | |
957 | */ | |
958 | if (page_mapped(page) && mapping) { | |
02c6de8d | 959 | switch (try_to_unmap(page, ttu_flags)) { |
1da177e4 LT |
960 | case SWAP_FAIL: |
961 | goto activate_locked; | |
962 | case SWAP_AGAIN: | |
963 | goto keep_locked; | |
b291f000 NP |
964 | case SWAP_MLOCK: |
965 | goto cull_mlocked; | |
1da177e4 LT |
966 | case SWAP_SUCCESS: |
967 | ; /* try to free the page below */ | |
968 | } | |
969 | } | |
970 | ||
971 | if (PageDirty(page)) { | |
ee72886d MG |
972 | /* |
973 | * Only kswapd can writeback filesystem pages to | |
d43006d5 MG |
974 | * avoid risk of stack overflow but only writeback |
975 | * if many dirty pages have been encountered. | |
ee72886d | 976 | */ |
f84f6e2b | 977 | if (page_is_file_cache(page) && |
9e3b2f8c | 978 | (!current_is_kswapd() || |
d43006d5 | 979 | !zone_is_reclaim_dirty(zone))) { |
49ea7eb6 MG |
980 | /* |
981 | * Immediately reclaim when written back. | |
982 | * Similar in principal to deactivate_page() | |
983 | * except we already have the page isolated | |
984 | * and know it's dirty | |
985 | */ | |
986 | inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE); | |
987 | SetPageReclaim(page); | |
988 | ||
ee72886d MG |
989 | goto keep_locked; |
990 | } | |
991 | ||
dfc8d636 | 992 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 993 | goto keep_locked; |
4dd4b920 | 994 | if (!may_enter_fs) |
1da177e4 | 995 | goto keep_locked; |
52a8363e | 996 | if (!sc->may_writepage) |
1da177e4 LT |
997 | goto keep_locked; |
998 | ||
999 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 1000 | switch (pageout(page, mapping, sc)) { |
1da177e4 LT |
1001 | case PAGE_KEEP: |
1002 | goto keep_locked; | |
1003 | case PAGE_ACTIVATE: | |
1004 | goto activate_locked; | |
1005 | case PAGE_SUCCESS: | |
7d3579e8 | 1006 | if (PageWriteback(page)) |
41ac1999 | 1007 | goto keep; |
7d3579e8 | 1008 | if (PageDirty(page)) |
1da177e4 | 1009 | goto keep; |
7d3579e8 | 1010 | |
1da177e4 LT |
1011 | /* |
1012 | * A synchronous write - probably a ramdisk. Go | |
1013 | * ahead and try to reclaim the page. | |
1014 | */ | |
529ae9aa | 1015 | if (!trylock_page(page)) |
1da177e4 LT |
1016 | goto keep; |
1017 | if (PageDirty(page) || PageWriteback(page)) | |
1018 | goto keep_locked; | |
1019 | mapping = page_mapping(page); | |
1020 | case PAGE_CLEAN: | |
1021 | ; /* try to free the page below */ | |
1022 | } | |
1023 | } | |
1024 | ||
1025 | /* | |
1026 | * If the page has buffers, try to free the buffer mappings | |
1027 | * associated with this page. If we succeed we try to free | |
1028 | * the page as well. | |
1029 | * | |
1030 | * We do this even if the page is PageDirty(). | |
1031 | * try_to_release_page() does not perform I/O, but it is | |
1032 | * possible for a page to have PageDirty set, but it is actually | |
1033 | * clean (all its buffers are clean). This happens if the | |
1034 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 1035 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
1036 | * try_to_release_page() will discover that cleanness and will |
1037 | * drop the buffers and mark the page clean - it can be freed. | |
1038 | * | |
1039 | * Rarely, pages can have buffers and no ->mapping. These are | |
1040 | * the pages which were not successfully invalidated in | |
1041 | * truncate_complete_page(). We try to drop those buffers here | |
1042 | * and if that worked, and the page is no longer mapped into | |
1043 | * process address space (page_count == 1) it can be freed. | |
1044 | * Otherwise, leave the page on the LRU so it is swappable. | |
1045 | */ | |
266cf658 | 1046 | if (page_has_private(page)) { |
1da177e4 LT |
1047 | if (!try_to_release_page(page, sc->gfp_mask)) |
1048 | goto activate_locked; | |
e286781d NP |
1049 | if (!mapping && page_count(page) == 1) { |
1050 | unlock_page(page); | |
1051 | if (put_page_testzero(page)) | |
1052 | goto free_it; | |
1053 | else { | |
1054 | /* | |
1055 | * rare race with speculative reference. | |
1056 | * the speculative reference will free | |
1057 | * this page shortly, so we may | |
1058 | * increment nr_reclaimed here (and | |
1059 | * leave it off the LRU). | |
1060 | */ | |
1061 | nr_reclaimed++; | |
1062 | continue; | |
1063 | } | |
1064 | } | |
1da177e4 LT |
1065 | } |
1066 | ||
e286781d | 1067 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 1068 | goto keep_locked; |
1da177e4 | 1069 | |
a978d6f5 NP |
1070 | /* |
1071 | * At this point, we have no other references and there is | |
1072 | * no way to pick any more up (removed from LRU, removed | |
1073 | * from pagecache). Can use non-atomic bitops now (and | |
1074 | * we obviously don't have to worry about waking up a process | |
1075 | * waiting on the page lock, because there are no references. | |
1076 | */ | |
1077 | __clear_page_locked(page); | |
e286781d | 1078 | free_it: |
05ff5137 | 1079 | nr_reclaimed++; |
abe4c3b5 MG |
1080 | |
1081 | /* | |
1082 | * Is there need to periodically free_page_list? It would | |
1083 | * appear not as the counts should be low | |
1084 | */ | |
1085 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
1086 | continue; |
1087 | ||
b291f000 | 1088 | cull_mlocked: |
63d6c5ad HD |
1089 | if (PageSwapCache(page)) |
1090 | try_to_free_swap(page); | |
b291f000 NP |
1091 | unlock_page(page); |
1092 | putback_lru_page(page); | |
1093 | continue; | |
1094 | ||
1da177e4 | 1095 | activate_locked: |
68a22394 RR |
1096 | /* Not a candidate for swapping, so reclaim swap space. */ |
1097 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 1098 | try_to_free_swap(page); |
309381fe | 1099 | VM_BUG_ON_PAGE(PageActive(page), page); |
1da177e4 LT |
1100 | SetPageActive(page); |
1101 | pgactivate++; | |
1102 | keep_locked: | |
1103 | unlock_page(page); | |
1104 | keep: | |
1105 | list_add(&page->lru, &ret_pages); | |
309381fe | 1106 | VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); |
1da177e4 | 1107 | } |
abe4c3b5 | 1108 | |
cc59850e | 1109 | free_hot_cold_page_list(&free_pages, 1); |
abe4c3b5 | 1110 | |
1da177e4 | 1111 | list_splice(&ret_pages, page_list); |
f8891e5e | 1112 | count_vm_events(PGACTIVATE, pgactivate); |
69980e31 | 1113 | mem_cgroup_uncharge_end(); |
8e950282 MG |
1114 | *ret_nr_dirty += nr_dirty; |
1115 | *ret_nr_congested += nr_congested; | |
d43006d5 | 1116 | *ret_nr_unqueued_dirty += nr_unqueued_dirty; |
92df3a72 | 1117 | *ret_nr_writeback += nr_writeback; |
b1a6f21e | 1118 | *ret_nr_immediate += nr_immediate; |
05ff5137 | 1119 | return nr_reclaimed; |
1da177e4 LT |
1120 | } |
1121 | ||
02c6de8d MK |
1122 | unsigned long reclaim_clean_pages_from_list(struct zone *zone, |
1123 | struct list_head *page_list) | |
1124 | { | |
1125 | struct scan_control sc = { | |
1126 | .gfp_mask = GFP_KERNEL, | |
1127 | .priority = DEF_PRIORITY, | |
1128 | .may_unmap = 1, | |
1129 | }; | |
8e950282 | 1130 | unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5; |
02c6de8d MK |
1131 | struct page *page, *next; |
1132 | LIST_HEAD(clean_pages); | |
1133 | ||
1134 | list_for_each_entry_safe(page, next, page_list, lru) { | |
117aad1e RA |
1135 | if (page_is_file_cache(page) && !PageDirty(page) && |
1136 | !isolated_balloon_page(page)) { | |
02c6de8d MK |
1137 | ClearPageActive(page); |
1138 | list_move(&page->lru, &clean_pages); | |
1139 | } | |
1140 | } | |
1141 | ||
1142 | ret = shrink_page_list(&clean_pages, zone, &sc, | |
8e950282 MG |
1143 | TTU_UNMAP|TTU_IGNORE_ACCESS, |
1144 | &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true); | |
02c6de8d MK |
1145 | list_splice(&clean_pages, page_list); |
1146 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret); | |
1147 | return ret; | |
1148 | } | |
1149 | ||
5ad333eb AW |
1150 | /* |
1151 | * Attempt to remove the specified page from its LRU. Only take this page | |
1152 | * if it is of the appropriate PageActive status. Pages which are being | |
1153 | * freed elsewhere are also ignored. | |
1154 | * | |
1155 | * page: page to consider | |
1156 | * mode: one of the LRU isolation modes defined above | |
1157 | * | |
1158 | * returns 0 on success, -ve errno on failure. | |
1159 | */ | |
f3fd4a61 | 1160 | int __isolate_lru_page(struct page *page, isolate_mode_t mode) |
5ad333eb AW |
1161 | { |
1162 | int ret = -EINVAL; | |
1163 | ||
1164 | /* Only take pages on the LRU. */ | |
1165 | if (!PageLRU(page)) | |
1166 | return ret; | |
1167 | ||
e46a2879 MK |
1168 | /* Compaction should not handle unevictable pages but CMA can do so */ |
1169 | if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) | |
894bc310 LS |
1170 | return ret; |
1171 | ||
5ad333eb | 1172 | ret = -EBUSY; |
08e552c6 | 1173 | |
c8244935 MG |
1174 | /* |
1175 | * To minimise LRU disruption, the caller can indicate that it only | |
1176 | * wants to isolate pages it will be able to operate on without | |
1177 | * blocking - clean pages for the most part. | |
1178 | * | |
1179 | * ISOLATE_CLEAN means that only clean pages should be isolated. This | |
1180 | * is used by reclaim when it is cannot write to backing storage | |
1181 | * | |
1182 | * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages | |
1183 | * that it is possible to migrate without blocking | |
1184 | */ | |
1185 | if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) { | |
1186 | /* All the caller can do on PageWriteback is block */ | |
1187 | if (PageWriteback(page)) | |
1188 | return ret; | |
1189 | ||
1190 | if (PageDirty(page)) { | |
1191 | struct address_space *mapping; | |
1192 | ||
1193 | /* ISOLATE_CLEAN means only clean pages */ | |
1194 | if (mode & ISOLATE_CLEAN) | |
1195 | return ret; | |
1196 | ||
1197 | /* | |
1198 | * Only pages without mappings or that have a | |
1199 | * ->migratepage callback are possible to migrate | |
1200 | * without blocking | |
1201 | */ | |
1202 | mapping = page_mapping(page); | |
1203 | if (mapping && !mapping->a_ops->migratepage) | |
1204 | return ret; | |
1205 | } | |
1206 | } | |
39deaf85 | 1207 | |
f80c0673 MK |
1208 | if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) |
1209 | return ret; | |
1210 | ||
5ad333eb AW |
1211 | if (likely(get_page_unless_zero(page))) { |
1212 | /* | |
1213 | * Be careful not to clear PageLRU until after we're | |
1214 | * sure the page is not being freed elsewhere -- the | |
1215 | * page release code relies on it. | |
1216 | */ | |
1217 | ClearPageLRU(page); | |
1218 | ret = 0; | |
1219 | } | |
1220 | ||
1221 | return ret; | |
1222 | } | |
1223 | ||
1da177e4 LT |
1224 | /* |
1225 | * zone->lru_lock is heavily contended. Some of the functions that | |
1226 | * shrink the lists perform better by taking out a batch of pages | |
1227 | * and working on them outside the LRU lock. | |
1228 | * | |
1229 | * For pagecache intensive workloads, this function is the hottest | |
1230 | * spot in the kernel (apart from copy_*_user functions). | |
1231 | * | |
1232 | * Appropriate locks must be held before calling this function. | |
1233 | * | |
1234 | * @nr_to_scan: The number of pages to look through on the list. | |
5dc35979 | 1235 | * @lruvec: The LRU vector to pull pages from. |
1da177e4 | 1236 | * @dst: The temp list to put pages on to. |
f626012d | 1237 | * @nr_scanned: The number of pages that were scanned. |
fe2c2a10 | 1238 | * @sc: The scan_control struct for this reclaim session |
5ad333eb | 1239 | * @mode: One of the LRU isolation modes |
3cb99451 | 1240 | * @lru: LRU list id for isolating |
1da177e4 LT |
1241 | * |
1242 | * returns how many pages were moved onto *@dst. | |
1243 | */ | |
69e05944 | 1244 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
5dc35979 | 1245 | struct lruvec *lruvec, struct list_head *dst, |
fe2c2a10 | 1246 | unsigned long *nr_scanned, struct scan_control *sc, |
3cb99451 | 1247 | isolate_mode_t mode, enum lru_list lru) |
1da177e4 | 1248 | { |
75b00af7 | 1249 | struct list_head *src = &lruvec->lists[lru]; |
69e05944 | 1250 | unsigned long nr_taken = 0; |
c9b02d97 | 1251 | unsigned long scan; |
1da177e4 | 1252 | |
c9b02d97 | 1253 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb | 1254 | struct page *page; |
fa9add64 | 1255 | int nr_pages; |
5ad333eb | 1256 | |
1da177e4 LT |
1257 | page = lru_to_page(src); |
1258 | prefetchw_prev_lru_page(page, src, flags); | |
1259 | ||
309381fe | 1260 | VM_BUG_ON_PAGE(!PageLRU(page), page); |
8d438f96 | 1261 | |
f3fd4a61 | 1262 | switch (__isolate_lru_page(page, mode)) { |
5ad333eb | 1263 | case 0: |
fa9add64 HD |
1264 | nr_pages = hpage_nr_pages(page); |
1265 | mem_cgroup_update_lru_size(lruvec, lru, -nr_pages); | |
5ad333eb | 1266 | list_move(&page->lru, dst); |
fa9add64 | 1267 | nr_taken += nr_pages; |
5ad333eb AW |
1268 | break; |
1269 | ||
1270 | case -EBUSY: | |
1271 | /* else it is being freed elsewhere */ | |
1272 | list_move(&page->lru, src); | |
1273 | continue; | |
46453a6e | 1274 | |
5ad333eb AW |
1275 | default: |
1276 | BUG(); | |
1277 | } | |
1da177e4 LT |
1278 | } |
1279 | ||
f626012d | 1280 | *nr_scanned = scan; |
75b00af7 HD |
1281 | trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan, |
1282 | nr_taken, mode, is_file_lru(lru)); | |
1da177e4 LT |
1283 | return nr_taken; |
1284 | } | |
1285 | ||
62695a84 NP |
1286 | /** |
1287 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1288 | * @page: page to isolate from its LRU list | |
1289 | * | |
1290 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1291 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1292 | * | |
1293 | * Returns 0 if the page was removed from an LRU list. | |
1294 | * Returns -EBUSY if the page was not on an LRU list. | |
1295 | * | |
1296 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1297 | * the active list, it will have PageActive set. If it was found on |
1298 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1299 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1300 | * |
1301 | * The vmstat statistic corresponding to the list on which the page was | |
1302 | * found will be decremented. | |
1303 | * | |
1304 | * Restrictions: | |
1305 | * (1) Must be called with an elevated refcount on the page. This is a | |
1306 | * fundamentnal difference from isolate_lru_pages (which is called | |
1307 | * without a stable reference). | |
1308 | * (2) the lru_lock must not be held. | |
1309 | * (3) interrupts must be enabled. | |
1310 | */ | |
1311 | int isolate_lru_page(struct page *page) | |
1312 | { | |
1313 | int ret = -EBUSY; | |
1314 | ||
309381fe | 1315 | VM_BUG_ON_PAGE(!page_count(page), page); |
0c917313 | 1316 | |
62695a84 NP |
1317 | if (PageLRU(page)) { |
1318 | struct zone *zone = page_zone(page); | |
fa9add64 | 1319 | struct lruvec *lruvec; |
62695a84 NP |
1320 | |
1321 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 | 1322 | lruvec = mem_cgroup_page_lruvec(page, zone); |
0c917313 | 1323 | if (PageLRU(page)) { |
894bc310 | 1324 | int lru = page_lru(page); |
0c917313 | 1325 | get_page(page); |
62695a84 | 1326 | ClearPageLRU(page); |
fa9add64 HD |
1327 | del_page_from_lru_list(page, lruvec, lru); |
1328 | ret = 0; | |
62695a84 NP |
1329 | } |
1330 | spin_unlock_irq(&zone->lru_lock); | |
1331 | } | |
1332 | return ret; | |
1333 | } | |
1334 | ||
35cd7815 | 1335 | /* |
d37dd5dc FW |
1336 | * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and |
1337 | * then get resheduled. When there are massive number of tasks doing page | |
1338 | * allocation, such sleeping direct reclaimers may keep piling up on each CPU, | |
1339 | * the LRU list will go small and be scanned faster than necessary, leading to | |
1340 | * unnecessary swapping, thrashing and OOM. | |
35cd7815 RR |
1341 | */ |
1342 | static int too_many_isolated(struct zone *zone, int file, | |
1343 | struct scan_control *sc) | |
1344 | { | |
1345 | unsigned long inactive, isolated; | |
1346 | ||
1347 | if (current_is_kswapd()) | |
1348 | return 0; | |
1349 | ||
89b5fae5 | 1350 | if (!global_reclaim(sc)) |
35cd7815 RR |
1351 | return 0; |
1352 | ||
1353 | if (file) { | |
1354 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1355 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1356 | } else { | |
1357 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1358 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1359 | } | |
1360 | ||
3cf23841 FW |
1361 | /* |
1362 | * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they | |
1363 | * won't get blocked by normal direct-reclaimers, forming a circular | |
1364 | * deadlock. | |
1365 | */ | |
1366 | if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS) | |
1367 | inactive >>= 3; | |
1368 | ||
35cd7815 RR |
1369 | return isolated > inactive; |
1370 | } | |
1371 | ||
66635629 | 1372 | static noinline_for_stack void |
75b00af7 | 1373 | putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) |
66635629 | 1374 | { |
27ac81d8 KK |
1375 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1376 | struct zone *zone = lruvec_zone(lruvec); | |
3f79768f | 1377 | LIST_HEAD(pages_to_free); |
66635629 | 1378 | |
66635629 MG |
1379 | /* |
1380 | * Put back any unfreeable pages. | |
1381 | */ | |
66635629 | 1382 | while (!list_empty(page_list)) { |
3f79768f | 1383 | struct page *page = lru_to_page(page_list); |
66635629 | 1384 | int lru; |
3f79768f | 1385 | |
309381fe | 1386 | VM_BUG_ON_PAGE(PageLRU(page), page); |
66635629 | 1387 | list_del(&page->lru); |
39b5f29a | 1388 | if (unlikely(!page_evictable(page))) { |
66635629 MG |
1389 | spin_unlock_irq(&zone->lru_lock); |
1390 | putback_lru_page(page); | |
1391 | spin_lock_irq(&zone->lru_lock); | |
1392 | continue; | |
1393 | } | |
fa9add64 HD |
1394 | |
1395 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
1396 | ||
7a608572 | 1397 | SetPageLRU(page); |
66635629 | 1398 | lru = page_lru(page); |
fa9add64 HD |
1399 | add_page_to_lru_list(page, lruvec, lru); |
1400 | ||
66635629 MG |
1401 | if (is_active_lru(lru)) { |
1402 | int file = is_file_lru(lru); | |
9992af10 RR |
1403 | int numpages = hpage_nr_pages(page); |
1404 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 | 1405 | } |
2bcf8879 HD |
1406 | if (put_page_testzero(page)) { |
1407 | __ClearPageLRU(page); | |
1408 | __ClearPageActive(page); | |
fa9add64 | 1409 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1410 | |
1411 | if (unlikely(PageCompound(page))) { | |
1412 | spin_unlock_irq(&zone->lru_lock); | |
1413 | (*get_compound_page_dtor(page))(page); | |
1414 | spin_lock_irq(&zone->lru_lock); | |
1415 | } else | |
1416 | list_add(&page->lru, &pages_to_free); | |
66635629 MG |
1417 | } |
1418 | } | |
66635629 | 1419 | |
3f79768f HD |
1420 | /* |
1421 | * To save our caller's stack, now use input list for pages to free. | |
1422 | */ | |
1423 | list_splice(&pages_to_free, page_list); | |
66635629 MG |
1424 | } |
1425 | ||
1da177e4 | 1426 | /* |
1742f19f AM |
1427 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1428 | * of reclaimed pages | |
1da177e4 | 1429 | */ |
66635629 | 1430 | static noinline_for_stack unsigned long |
1a93be0e | 1431 | shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, |
9e3b2f8c | 1432 | struct scan_control *sc, enum lru_list lru) |
1da177e4 LT |
1433 | { |
1434 | LIST_HEAD(page_list); | |
e247dbce | 1435 | unsigned long nr_scanned; |
05ff5137 | 1436 | unsigned long nr_reclaimed = 0; |
e247dbce | 1437 | unsigned long nr_taken; |
8e950282 MG |
1438 | unsigned long nr_dirty = 0; |
1439 | unsigned long nr_congested = 0; | |
e2be15f6 | 1440 | unsigned long nr_unqueued_dirty = 0; |
92df3a72 | 1441 | unsigned long nr_writeback = 0; |
b1a6f21e | 1442 | unsigned long nr_immediate = 0; |
f3fd4a61 | 1443 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1444 | int file = is_file_lru(lru); |
1a93be0e KK |
1445 | struct zone *zone = lruvec_zone(lruvec); |
1446 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; | |
78dc583d | 1447 | |
35cd7815 | 1448 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1449 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1450 | |
1451 | /* We are about to die and free our memory. Return now. */ | |
1452 | if (fatal_signal_pending(current)) | |
1453 | return SWAP_CLUSTER_MAX; | |
1454 | } | |
1455 | ||
1da177e4 | 1456 | lru_add_drain(); |
f80c0673 MK |
1457 | |
1458 | if (!sc->may_unmap) | |
61317289 | 1459 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1460 | if (!sc->may_writepage) |
61317289 | 1461 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1462 | |
1da177e4 | 1463 | spin_lock_irq(&zone->lru_lock); |
b35ea17b | 1464 | |
5dc35979 KK |
1465 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, |
1466 | &nr_scanned, sc, isolate_mode, lru); | |
95d918fc KK |
1467 | |
1468 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); | |
1469 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); | |
1470 | ||
89b5fae5 | 1471 | if (global_reclaim(sc)) { |
e247dbce KM |
1472 | zone->pages_scanned += nr_scanned; |
1473 | if (current_is_kswapd()) | |
75b00af7 | 1474 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned); |
e247dbce | 1475 | else |
75b00af7 | 1476 | __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned); |
e247dbce | 1477 | } |
d563c050 | 1478 | spin_unlock_irq(&zone->lru_lock); |
b35ea17b | 1479 | |
d563c050 | 1480 | if (nr_taken == 0) |
66635629 | 1481 | return 0; |
5ad333eb | 1482 | |
02c6de8d | 1483 | nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP, |
8e950282 MG |
1484 | &nr_dirty, &nr_unqueued_dirty, &nr_congested, |
1485 | &nr_writeback, &nr_immediate, | |
1486 | false); | |
c661b078 | 1487 | |
3f79768f HD |
1488 | spin_lock_irq(&zone->lru_lock); |
1489 | ||
95d918fc | 1490 | reclaim_stat->recent_scanned[file] += nr_taken; |
d563c050 | 1491 | |
904249aa YH |
1492 | if (global_reclaim(sc)) { |
1493 | if (current_is_kswapd()) | |
1494 | __count_zone_vm_events(PGSTEAL_KSWAPD, zone, | |
1495 | nr_reclaimed); | |
1496 | else | |
1497 | __count_zone_vm_events(PGSTEAL_DIRECT, zone, | |
1498 | nr_reclaimed); | |
1499 | } | |
a74609fa | 1500 | |
27ac81d8 | 1501 | putback_inactive_pages(lruvec, &page_list); |
3f79768f | 1502 | |
95d918fc | 1503 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
3f79768f HD |
1504 | |
1505 | spin_unlock_irq(&zone->lru_lock); | |
1506 | ||
1507 | free_hot_cold_page_list(&page_list, 1); | |
e11da5b4 | 1508 | |
92df3a72 MG |
1509 | /* |
1510 | * If reclaim is isolating dirty pages under writeback, it implies | |
1511 | * that the long-lived page allocation rate is exceeding the page | |
1512 | * laundering rate. Either the global limits are not being effective | |
1513 | * at throttling processes due to the page distribution throughout | |
1514 | * zones or there is heavy usage of a slow backing device. The | |
1515 | * only option is to throttle from reclaim context which is not ideal | |
1516 | * as there is no guarantee the dirtying process is throttled in the | |
1517 | * same way balance_dirty_pages() manages. | |
1518 | * | |
8e950282 MG |
1519 | * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number |
1520 | * of pages under pages flagged for immediate reclaim and stall if any | |
1521 | * are encountered in the nr_immediate check below. | |
92df3a72 | 1522 | */ |
918fc718 | 1523 | if (nr_writeback && nr_writeback == nr_taken) |
283aba9f | 1524 | zone_set_flag(zone, ZONE_WRITEBACK); |
92df3a72 | 1525 | |
d43006d5 | 1526 | /* |
b1a6f21e MG |
1527 | * memcg will stall in page writeback so only consider forcibly |
1528 | * stalling for global reclaim | |
d43006d5 | 1529 | */ |
b1a6f21e | 1530 | if (global_reclaim(sc)) { |
8e950282 MG |
1531 | /* |
1532 | * Tag a zone as congested if all the dirty pages scanned were | |
1533 | * backed by a congested BDI and wait_iff_congested will stall. | |
1534 | */ | |
1535 | if (nr_dirty && nr_dirty == nr_congested) | |
1536 | zone_set_flag(zone, ZONE_CONGESTED); | |
1537 | ||
b1a6f21e MG |
1538 | /* |
1539 | * If dirty pages are scanned that are not queued for IO, it | |
1540 | * implies that flushers are not keeping up. In this case, flag | |
1541 | * the zone ZONE_TAIL_LRU_DIRTY and kswapd will start writing | |
1542 | * pages from reclaim context. It will forcibly stall in the | |
1543 | * next check. | |
1544 | */ | |
1545 | if (nr_unqueued_dirty == nr_taken) | |
1546 | zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY); | |
1547 | ||
1548 | /* | |
1549 | * In addition, if kswapd scans pages marked marked for | |
1550 | * immediate reclaim and under writeback (nr_immediate), it | |
1551 | * implies that pages are cycling through the LRU faster than | |
1552 | * they are written so also forcibly stall. | |
1553 | */ | |
1554 | if (nr_unqueued_dirty == nr_taken || nr_immediate) | |
1555 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
e2be15f6 | 1556 | } |
d43006d5 | 1557 | |
8e950282 MG |
1558 | /* |
1559 | * Stall direct reclaim for IO completions if underlying BDIs or zone | |
1560 | * is congested. Allow kswapd to continue until it starts encountering | |
1561 | * unqueued dirty pages or cycling through the LRU too quickly. | |
1562 | */ | |
1563 | if (!sc->hibernation_mode && !current_is_kswapd()) | |
1564 | wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); | |
1565 | ||
e11da5b4 MG |
1566 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, |
1567 | zone_idx(zone), | |
1568 | nr_scanned, nr_reclaimed, | |
9e3b2f8c | 1569 | sc->priority, |
23b9da55 | 1570 | trace_shrink_flags(file)); |
05ff5137 | 1571 | return nr_reclaimed; |
1da177e4 LT |
1572 | } |
1573 | ||
1574 | /* | |
1575 | * This moves pages from the active list to the inactive list. | |
1576 | * | |
1577 | * We move them the other way if the page is referenced by one or more | |
1578 | * processes, from rmap. | |
1579 | * | |
1580 | * If the pages are mostly unmapped, the processing is fast and it is | |
1581 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1582 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1583 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1584 | * this, so instead we remove the pages from the LRU while processing them. | |
1585 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1586 | * nobody will play with that bit on a non-LRU page. | |
1587 | * | |
1588 | * The downside is that we have to touch page->_count against each page. | |
1589 | * But we had to alter page->flags anyway. | |
1590 | */ | |
1cfb419b | 1591 | |
fa9add64 | 1592 | static void move_active_pages_to_lru(struct lruvec *lruvec, |
3eb4140f | 1593 | struct list_head *list, |
2bcf8879 | 1594 | struct list_head *pages_to_free, |
3eb4140f WF |
1595 | enum lru_list lru) |
1596 | { | |
fa9add64 | 1597 | struct zone *zone = lruvec_zone(lruvec); |
3eb4140f | 1598 | unsigned long pgmoved = 0; |
3eb4140f | 1599 | struct page *page; |
fa9add64 | 1600 | int nr_pages; |
3eb4140f | 1601 | |
3eb4140f WF |
1602 | while (!list_empty(list)) { |
1603 | page = lru_to_page(list); | |
fa9add64 | 1604 | lruvec = mem_cgroup_page_lruvec(page, zone); |
3eb4140f | 1605 | |
309381fe | 1606 | VM_BUG_ON_PAGE(PageLRU(page), page); |
3eb4140f WF |
1607 | SetPageLRU(page); |
1608 | ||
fa9add64 HD |
1609 | nr_pages = hpage_nr_pages(page); |
1610 | mem_cgroup_update_lru_size(lruvec, lru, nr_pages); | |
925b7673 | 1611 | list_move(&page->lru, &lruvec->lists[lru]); |
fa9add64 | 1612 | pgmoved += nr_pages; |
3eb4140f | 1613 | |
2bcf8879 HD |
1614 | if (put_page_testzero(page)) { |
1615 | __ClearPageLRU(page); | |
1616 | __ClearPageActive(page); | |
fa9add64 | 1617 | del_page_from_lru_list(page, lruvec, lru); |
2bcf8879 HD |
1618 | |
1619 | if (unlikely(PageCompound(page))) { | |
1620 | spin_unlock_irq(&zone->lru_lock); | |
1621 | (*get_compound_page_dtor(page))(page); | |
1622 | spin_lock_irq(&zone->lru_lock); | |
1623 | } else | |
1624 | list_add(&page->lru, pages_to_free); | |
3eb4140f WF |
1625 | } |
1626 | } | |
1627 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1628 | if (!is_active_lru(lru)) | |
1629 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1630 | } | |
1cfb419b | 1631 | |
f626012d | 1632 | static void shrink_active_list(unsigned long nr_to_scan, |
1a93be0e | 1633 | struct lruvec *lruvec, |
f16015fb | 1634 | struct scan_control *sc, |
9e3b2f8c | 1635 | enum lru_list lru) |
1da177e4 | 1636 | { |
44c241f1 | 1637 | unsigned long nr_taken; |
f626012d | 1638 | unsigned long nr_scanned; |
6fe6b7e3 | 1639 | unsigned long vm_flags; |
1da177e4 | 1640 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1641 | LIST_HEAD(l_active); |
b69408e8 | 1642 | LIST_HEAD(l_inactive); |
1da177e4 | 1643 | struct page *page; |
1a93be0e | 1644 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
44c241f1 | 1645 | unsigned long nr_rotated = 0; |
f3fd4a61 | 1646 | isolate_mode_t isolate_mode = 0; |
3cb99451 | 1647 | int file = is_file_lru(lru); |
1a93be0e | 1648 | struct zone *zone = lruvec_zone(lruvec); |
1da177e4 LT |
1649 | |
1650 | lru_add_drain(); | |
f80c0673 MK |
1651 | |
1652 | if (!sc->may_unmap) | |
61317289 | 1653 | isolate_mode |= ISOLATE_UNMAPPED; |
f80c0673 | 1654 | if (!sc->may_writepage) |
61317289 | 1655 | isolate_mode |= ISOLATE_CLEAN; |
f80c0673 | 1656 | |
1da177e4 | 1657 | spin_lock_irq(&zone->lru_lock); |
925b7673 | 1658 | |
5dc35979 KK |
1659 | nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, |
1660 | &nr_scanned, sc, isolate_mode, lru); | |
89b5fae5 | 1661 | if (global_reclaim(sc)) |
f626012d | 1662 | zone->pages_scanned += nr_scanned; |
89b5fae5 | 1663 | |
b7c46d15 | 1664 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1665 | |
f626012d | 1666 | __count_zone_vm_events(PGREFILL, zone, nr_scanned); |
3cb99451 | 1667 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken); |
a731286d | 1668 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1669 | spin_unlock_irq(&zone->lru_lock); |
1670 | ||
1da177e4 LT |
1671 | while (!list_empty(&l_hold)) { |
1672 | cond_resched(); | |
1673 | page = lru_to_page(&l_hold); | |
1674 | list_del(&page->lru); | |
7e9cd484 | 1675 | |
39b5f29a | 1676 | if (unlikely(!page_evictable(page))) { |
894bc310 LS |
1677 | putback_lru_page(page); |
1678 | continue; | |
1679 | } | |
1680 | ||
cc715d99 MG |
1681 | if (unlikely(buffer_heads_over_limit)) { |
1682 | if (page_has_private(page) && trylock_page(page)) { | |
1683 | if (page_has_private(page)) | |
1684 | try_to_release_page(page, 0); | |
1685 | unlock_page(page); | |
1686 | } | |
1687 | } | |
1688 | ||
c3ac9a8a JW |
1689 | if (page_referenced(page, 0, sc->target_mem_cgroup, |
1690 | &vm_flags)) { | |
9992af10 | 1691 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1692 | /* |
1693 | * Identify referenced, file-backed active pages and | |
1694 | * give them one more trip around the active list. So | |
1695 | * that executable code get better chances to stay in | |
1696 | * memory under moderate memory pressure. Anon pages | |
1697 | * are not likely to be evicted by use-once streaming | |
1698 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1699 | * so we ignore them here. | |
1700 | */ | |
41e20983 | 1701 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1702 | list_add(&page->lru, &l_active); |
1703 | continue; | |
1704 | } | |
1705 | } | |
7e9cd484 | 1706 | |
5205e56e | 1707 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1708 | list_add(&page->lru, &l_inactive); |
1709 | } | |
1710 | ||
b555749a | 1711 | /* |
8cab4754 | 1712 | * Move pages back to the lru list. |
b555749a | 1713 | */ |
2a1dc509 | 1714 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1715 | /* |
8cab4754 WF |
1716 | * Count referenced pages from currently used mappings as rotated, |
1717 | * even though only some of them are actually re-activated. This | |
1718 | * helps balance scan pressure between file and anonymous pages in | |
1719 | * get_scan_ratio. | |
7e9cd484 | 1720 | */ |
b7c46d15 | 1721 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1722 | |
fa9add64 HD |
1723 | move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); |
1724 | move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); | |
a731286d | 1725 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1726 | spin_unlock_irq(&zone->lru_lock); |
2bcf8879 HD |
1727 | |
1728 | free_hot_cold_page_list(&l_hold, 1); | |
1da177e4 LT |
1729 | } |
1730 | ||
74e3f3c3 | 1731 | #ifdef CONFIG_SWAP |
14797e23 | 1732 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1733 | { |
1734 | unsigned long active, inactive; | |
1735 | ||
1736 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1737 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1738 | ||
1739 | if (inactive * zone->inactive_ratio < active) | |
1740 | return 1; | |
1741 | ||
1742 | return 0; | |
1743 | } | |
1744 | ||
14797e23 KM |
1745 | /** |
1746 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
c56d5c7d | 1747 | * @lruvec: LRU vector to check |
14797e23 KM |
1748 | * |
1749 | * Returns true if the zone does not have enough inactive anon pages, | |
1750 | * meaning some active anon pages need to be deactivated. | |
1751 | */ | |
c56d5c7d | 1752 | static int inactive_anon_is_low(struct lruvec *lruvec) |
14797e23 | 1753 | { |
74e3f3c3 MK |
1754 | /* |
1755 | * If we don't have swap space, anonymous page deactivation | |
1756 | * is pointless. | |
1757 | */ | |
1758 | if (!total_swap_pages) | |
1759 | return 0; | |
1760 | ||
c3c787e8 | 1761 | if (!mem_cgroup_disabled()) |
c56d5c7d | 1762 | return mem_cgroup_inactive_anon_is_low(lruvec); |
f16015fb | 1763 | |
c56d5c7d | 1764 | return inactive_anon_is_low_global(lruvec_zone(lruvec)); |
14797e23 | 1765 | } |
74e3f3c3 | 1766 | #else |
c56d5c7d | 1767 | static inline int inactive_anon_is_low(struct lruvec *lruvec) |
74e3f3c3 MK |
1768 | { |
1769 | return 0; | |
1770 | } | |
1771 | #endif | |
14797e23 | 1772 | |
56e49d21 RR |
1773 | /** |
1774 | * inactive_file_is_low - check if file pages need to be deactivated | |
c56d5c7d | 1775 | * @lruvec: LRU vector to check |
56e49d21 RR |
1776 | * |
1777 | * When the system is doing streaming IO, memory pressure here | |
1778 | * ensures that active file pages get deactivated, until more | |
1779 | * than half of the file pages are on the inactive list. | |
1780 | * | |
1781 | * Once we get to that situation, protect the system's working | |
1782 | * set from being evicted by disabling active file page aging. | |
1783 | * | |
1784 | * This uses a different ratio than the anonymous pages, because | |
1785 | * the page cache uses a use-once replacement algorithm. | |
1786 | */ | |
c56d5c7d | 1787 | static int inactive_file_is_low(struct lruvec *lruvec) |
56e49d21 | 1788 | { |
e3790144 JW |
1789 | unsigned long inactive; |
1790 | unsigned long active; | |
1791 | ||
1792 | inactive = get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
1793 | active = get_lru_size(lruvec, LRU_ACTIVE_FILE); | |
56e49d21 | 1794 | |
e3790144 | 1795 | return active > inactive; |
56e49d21 RR |
1796 | } |
1797 | ||
75b00af7 | 1798 | static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru) |
b39415b2 | 1799 | { |
75b00af7 | 1800 | if (is_file_lru(lru)) |
c56d5c7d | 1801 | return inactive_file_is_low(lruvec); |
b39415b2 | 1802 | else |
c56d5c7d | 1803 | return inactive_anon_is_low(lruvec); |
b39415b2 RR |
1804 | } |
1805 | ||
4f98a2fe | 1806 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
1a93be0e | 1807 | struct lruvec *lruvec, struct scan_control *sc) |
b69408e8 | 1808 | { |
b39415b2 | 1809 | if (is_active_lru(lru)) { |
75b00af7 | 1810 | if (inactive_list_is_low(lruvec, lru)) |
1a93be0e | 1811 | shrink_active_list(nr_to_scan, lruvec, sc, lru); |
556adecb RR |
1812 | return 0; |
1813 | } | |
1814 | ||
1a93be0e | 1815 | return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); |
4f98a2fe RR |
1816 | } |
1817 | ||
3d58ab5c | 1818 | static int vmscan_swappiness(struct scan_control *sc) |
1f4c025b | 1819 | { |
89b5fae5 | 1820 | if (global_reclaim(sc)) |
1f4c025b | 1821 | return vm_swappiness; |
3d58ab5c | 1822 | return mem_cgroup_swappiness(sc->target_mem_cgroup); |
1f4c025b KH |
1823 | } |
1824 | ||
9a265114 JW |
1825 | enum scan_balance { |
1826 | SCAN_EQUAL, | |
1827 | SCAN_FRACT, | |
1828 | SCAN_ANON, | |
1829 | SCAN_FILE, | |
1830 | }; | |
1831 | ||
4f98a2fe RR |
1832 | /* |
1833 | * Determine how aggressively the anon and file LRU lists should be | |
1834 | * scanned. The relative value of each set of LRU lists is determined | |
1835 | * by looking at the fraction of the pages scanned we did rotate back | |
1836 | * onto the active list instead of evict. | |
1837 | * | |
be7bd59d WL |
1838 | * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan |
1839 | * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan | |
4f98a2fe | 1840 | */ |
90126375 | 1841 | static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, |
9e3b2f8c | 1842 | unsigned long *nr) |
4f98a2fe | 1843 | { |
9a265114 JW |
1844 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
1845 | u64 fraction[2]; | |
1846 | u64 denominator = 0; /* gcc */ | |
1847 | struct zone *zone = lruvec_zone(lruvec); | |
4f98a2fe | 1848 | unsigned long anon_prio, file_prio; |
9a265114 JW |
1849 | enum scan_balance scan_balance; |
1850 | unsigned long anon, file, free; | |
1851 | bool force_scan = false; | |
4f98a2fe | 1852 | unsigned long ap, fp; |
4111304d | 1853 | enum lru_list lru; |
246e87a9 | 1854 | |
f11c0ca5 JW |
1855 | /* |
1856 | * If the zone or memcg is small, nr[l] can be 0. This | |
1857 | * results in no scanning on this priority and a potential | |
1858 | * priority drop. Global direct reclaim can go to the next | |
1859 | * zone and tends to have no problems. Global kswapd is for | |
1860 | * zone balancing and it needs to scan a minimum amount. When | |
1861 | * reclaiming for a memcg, a priority drop can cause high | |
1862 | * latencies, so it's better to scan a minimum amount there as | |
1863 | * well. | |
1864 | */ | |
6e543d57 | 1865 | if (current_is_kswapd() && !zone_reclaimable(zone)) |
a4d3e9e7 | 1866 | force_scan = true; |
89b5fae5 | 1867 | if (!global_reclaim(sc)) |
a4d3e9e7 | 1868 | force_scan = true; |
76a33fc3 SL |
1869 | |
1870 | /* If we have no swap space, do not bother scanning anon pages. */ | |
ec8acf20 | 1871 | if (!sc->may_swap || (get_nr_swap_pages() <= 0)) { |
9a265114 | 1872 | scan_balance = SCAN_FILE; |
76a33fc3 SL |
1873 | goto out; |
1874 | } | |
4f98a2fe | 1875 | |
10316b31 JW |
1876 | /* |
1877 | * Global reclaim will swap to prevent OOM even with no | |
1878 | * swappiness, but memcg users want to use this knob to | |
1879 | * disable swapping for individual groups completely when | |
1880 | * using the memory controller's swap limit feature would be | |
1881 | * too expensive. | |
1882 | */ | |
1883 | if (!global_reclaim(sc) && !vmscan_swappiness(sc)) { | |
9a265114 | 1884 | scan_balance = SCAN_FILE; |
10316b31 JW |
1885 | goto out; |
1886 | } | |
1887 | ||
1888 | /* | |
1889 | * Do not apply any pressure balancing cleverness when the | |
1890 | * system is close to OOM, scan both anon and file equally | |
1891 | * (unless the swappiness setting disagrees with swapping). | |
1892 | */ | |
1893 | if (!sc->priority && vmscan_swappiness(sc)) { | |
9a265114 | 1894 | scan_balance = SCAN_EQUAL; |
10316b31 JW |
1895 | goto out; |
1896 | } | |
1897 | ||
4d7dcca2 HD |
1898 | anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) + |
1899 | get_lru_size(lruvec, LRU_INACTIVE_ANON); | |
1900 | file = get_lru_size(lruvec, LRU_ACTIVE_FILE) + | |
1901 | get_lru_size(lruvec, LRU_INACTIVE_FILE); | |
a4d3e9e7 | 1902 | |
11d16c25 JW |
1903 | /* |
1904 | * If it's foreseeable that reclaiming the file cache won't be | |
1905 | * enough to get the zone back into a desirable shape, we have | |
1906 | * to swap. Better start now and leave the - probably heavily | |
1907 | * thrashing - remaining file pages alone. | |
1908 | */ | |
89b5fae5 | 1909 | if (global_reclaim(sc)) { |
11d16c25 | 1910 | free = zone_page_state(zone, NR_FREE_PAGES); |
90126375 | 1911 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
9a265114 | 1912 | scan_balance = SCAN_ANON; |
76a33fc3 | 1913 | goto out; |
eeee9a8c | 1914 | } |
4f98a2fe RR |
1915 | } |
1916 | ||
7c5bd705 JW |
1917 | /* |
1918 | * There is enough inactive page cache, do not reclaim | |
1919 | * anything from the anonymous working set right now. | |
1920 | */ | |
1921 | if (!inactive_file_is_low(lruvec)) { | |
9a265114 | 1922 | scan_balance = SCAN_FILE; |
7c5bd705 JW |
1923 | goto out; |
1924 | } | |
1925 | ||
9a265114 JW |
1926 | scan_balance = SCAN_FRACT; |
1927 | ||
58c37f6e KM |
1928 | /* |
1929 | * With swappiness at 100, anonymous and file have the same priority. | |
1930 | * This scanning priority is essentially the inverse of IO cost. | |
1931 | */ | |
3d58ab5c | 1932 | anon_prio = vmscan_swappiness(sc); |
75b00af7 | 1933 | file_prio = 200 - anon_prio; |
58c37f6e | 1934 | |
4f98a2fe RR |
1935 | /* |
1936 | * OK, so we have swap space and a fair amount of page cache | |
1937 | * pages. We use the recently rotated / recently scanned | |
1938 | * ratios to determine how valuable each cache is. | |
1939 | * | |
1940 | * Because workloads change over time (and to avoid overflow) | |
1941 | * we keep these statistics as a floating average, which ends | |
1942 | * up weighing recent references more than old ones. | |
1943 | * | |
1944 | * anon in [0], file in [1] | |
1945 | */ | |
90126375 | 1946 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1947 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1948 | reclaim_stat->recent_scanned[0] /= 2; |
1949 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1950 | } |
1951 | ||
6e901571 | 1952 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1953 | reclaim_stat->recent_scanned[1] /= 2; |
1954 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1955 | } |
1956 | ||
4f98a2fe | 1957 | /* |
00d8089c RR |
1958 | * The amount of pressure on anon vs file pages is inversely |
1959 | * proportional to the fraction of recently scanned pages on | |
1960 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1961 | */ |
fe35004f | 1962 | ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); |
6e901571 | 1963 | ap /= reclaim_stat->recent_rotated[0] + 1; |
4f98a2fe | 1964 | |
fe35004f | 1965 | fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); |
6e901571 | 1966 | fp /= reclaim_stat->recent_rotated[1] + 1; |
90126375 | 1967 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1968 | |
76a33fc3 SL |
1969 | fraction[0] = ap; |
1970 | fraction[1] = fp; | |
1971 | denominator = ap + fp + 1; | |
1972 | out: | |
4111304d HD |
1973 | for_each_evictable_lru(lru) { |
1974 | int file = is_file_lru(lru); | |
d778df51 | 1975 | unsigned long size; |
76a33fc3 | 1976 | unsigned long scan; |
6e08a369 | 1977 | |
d778df51 | 1978 | size = get_lru_size(lruvec, lru); |
10316b31 | 1979 | scan = size >> sc->priority; |
9a265114 | 1980 | |
10316b31 JW |
1981 | if (!scan && force_scan) |
1982 | scan = min(size, SWAP_CLUSTER_MAX); | |
9a265114 JW |
1983 | |
1984 | switch (scan_balance) { | |
1985 | case SCAN_EQUAL: | |
1986 | /* Scan lists relative to size */ | |
1987 | break; | |
1988 | case SCAN_FRACT: | |
1989 | /* | |
1990 | * Scan types proportional to swappiness and | |
1991 | * their relative recent reclaim efficiency. | |
1992 | */ | |
1993 | scan = div64_u64(scan * fraction[file], denominator); | |
1994 | break; | |
1995 | case SCAN_FILE: | |
1996 | case SCAN_ANON: | |
1997 | /* Scan one type exclusively */ | |
1998 | if ((scan_balance == SCAN_FILE) != file) | |
1999 | scan = 0; | |
2000 | break; | |
2001 | default: | |
2002 | /* Look ma, no brain */ | |
2003 | BUG(); | |
2004 | } | |
4111304d | 2005 | nr[lru] = scan; |
76a33fc3 | 2006 | } |
6e08a369 | 2007 | } |
4f98a2fe | 2008 | |
9b4f98cd JW |
2009 | /* |
2010 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
2011 | */ | |
2012 | static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) | |
2013 | { | |
2014 | unsigned long nr[NR_LRU_LISTS]; | |
e82e0561 | 2015 | unsigned long targets[NR_LRU_LISTS]; |
9b4f98cd JW |
2016 | unsigned long nr_to_scan; |
2017 | enum lru_list lru; | |
2018 | unsigned long nr_reclaimed = 0; | |
2019 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; | |
2020 | struct blk_plug plug; | |
e82e0561 | 2021 | bool scan_adjusted = false; |
9b4f98cd JW |
2022 | |
2023 | get_scan_count(lruvec, sc, nr); | |
2024 | ||
e82e0561 MG |
2025 | /* Record the original scan target for proportional adjustments later */ |
2026 | memcpy(targets, nr, sizeof(nr)); | |
2027 | ||
9b4f98cd JW |
2028 | blk_start_plug(&plug); |
2029 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || | |
2030 | nr[LRU_INACTIVE_FILE]) { | |
e82e0561 MG |
2031 | unsigned long nr_anon, nr_file, percentage; |
2032 | unsigned long nr_scanned; | |
2033 | ||
9b4f98cd JW |
2034 | for_each_evictable_lru(lru) { |
2035 | if (nr[lru]) { | |
2036 | nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); | |
2037 | nr[lru] -= nr_to_scan; | |
2038 | ||
2039 | nr_reclaimed += shrink_list(lru, nr_to_scan, | |
2040 | lruvec, sc); | |
2041 | } | |
2042 | } | |
e82e0561 MG |
2043 | |
2044 | if (nr_reclaimed < nr_to_reclaim || scan_adjusted) | |
2045 | continue; | |
2046 | ||
9b4f98cd | 2047 | /* |
e82e0561 MG |
2048 | * For global direct reclaim, reclaim only the number of pages |
2049 | * requested. Less care is taken to scan proportionally as it | |
2050 | * is more important to minimise direct reclaim stall latency | |
2051 | * than it is to properly age the LRU lists. | |
9b4f98cd | 2052 | */ |
e82e0561 | 2053 | if (global_reclaim(sc) && !current_is_kswapd()) |
9b4f98cd | 2054 | break; |
e82e0561 MG |
2055 | |
2056 | /* | |
2057 | * For kswapd and memcg, reclaim at least the number of pages | |
2058 | * requested. Ensure that the anon and file LRUs shrink | |
2059 | * proportionally what was requested by get_scan_count(). We | |
2060 | * stop reclaiming one LRU and reduce the amount scanning | |
2061 | * proportional to the original scan target. | |
2062 | */ | |
2063 | nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; | |
2064 | nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; | |
2065 | ||
2066 | if (nr_file > nr_anon) { | |
2067 | unsigned long scan_target = targets[LRU_INACTIVE_ANON] + | |
2068 | targets[LRU_ACTIVE_ANON] + 1; | |
2069 | lru = LRU_BASE; | |
2070 | percentage = nr_anon * 100 / scan_target; | |
2071 | } else { | |
2072 | unsigned long scan_target = targets[LRU_INACTIVE_FILE] + | |
2073 | targets[LRU_ACTIVE_FILE] + 1; | |
2074 | lru = LRU_FILE; | |
2075 | percentage = nr_file * 100 / scan_target; | |
2076 | } | |
2077 | ||
2078 | /* Stop scanning the smaller of the LRU */ | |
2079 | nr[lru] = 0; | |
2080 | nr[lru + LRU_ACTIVE] = 0; | |
2081 | ||
2082 | /* | |
2083 | * Recalculate the other LRU scan count based on its original | |
2084 | * scan target and the percentage scanning already complete | |
2085 | */ | |
2086 | lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; | |
2087 | nr_scanned = targets[lru] - nr[lru]; | |
2088 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2089 | nr[lru] -= min(nr[lru], nr_scanned); | |
2090 | ||
2091 | lru += LRU_ACTIVE; | |
2092 | nr_scanned = targets[lru] - nr[lru]; | |
2093 | nr[lru] = targets[lru] * (100 - percentage) / 100; | |
2094 | nr[lru] -= min(nr[lru], nr_scanned); | |
2095 | ||
2096 | scan_adjusted = true; | |
9b4f98cd JW |
2097 | } |
2098 | blk_finish_plug(&plug); | |
2099 | sc->nr_reclaimed += nr_reclaimed; | |
2100 | ||
2101 | /* | |
2102 | * Even if we did not try to evict anon pages at all, we want to | |
2103 | * rebalance the anon lru active/inactive ratio. | |
2104 | */ | |
2105 | if (inactive_anon_is_low(lruvec)) | |
2106 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, | |
2107 | sc, LRU_ACTIVE_ANON); | |
2108 | ||
2109 | throttle_vm_writeout(sc->gfp_mask); | |
2110 | } | |
2111 | ||
23b9da55 | 2112 | /* Use reclaim/compaction for costly allocs or under memory pressure */ |
9e3b2f8c | 2113 | static bool in_reclaim_compaction(struct scan_control *sc) |
23b9da55 | 2114 | { |
d84da3f9 | 2115 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && |
23b9da55 | 2116 | (sc->order > PAGE_ALLOC_COSTLY_ORDER || |
9e3b2f8c | 2117 | sc->priority < DEF_PRIORITY - 2)) |
23b9da55 MG |
2118 | return true; |
2119 | ||
2120 | return false; | |
2121 | } | |
2122 | ||
3e7d3449 | 2123 | /* |
23b9da55 MG |
2124 | * Reclaim/compaction is used for high-order allocation requests. It reclaims |
2125 | * order-0 pages before compacting the zone. should_continue_reclaim() returns | |
2126 | * true if more pages should be reclaimed such that when the page allocator | |
2127 | * calls try_to_compact_zone() that it will have enough free pages to succeed. | |
2128 | * It will give up earlier than that if there is difficulty reclaiming pages. | |
3e7d3449 | 2129 | */ |
9b4f98cd | 2130 | static inline bool should_continue_reclaim(struct zone *zone, |
3e7d3449 MG |
2131 | unsigned long nr_reclaimed, |
2132 | unsigned long nr_scanned, | |
2133 | struct scan_control *sc) | |
2134 | { | |
2135 | unsigned long pages_for_compaction; | |
2136 | unsigned long inactive_lru_pages; | |
2137 | ||
2138 | /* If not in reclaim/compaction mode, stop */ | |
9e3b2f8c | 2139 | if (!in_reclaim_compaction(sc)) |
3e7d3449 MG |
2140 | return false; |
2141 | ||
2876592f MG |
2142 | /* Consider stopping depending on scan and reclaim activity */ |
2143 | if (sc->gfp_mask & __GFP_REPEAT) { | |
2144 | /* | |
2145 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
2146 | * full LRU list has been scanned and we are still failing | |
2147 | * to reclaim pages. This full LRU scan is potentially | |
2148 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
2149 | */ | |
2150 | if (!nr_reclaimed && !nr_scanned) | |
2151 | return false; | |
2152 | } else { | |
2153 | /* | |
2154 | * For non-__GFP_REPEAT allocations which can presumably | |
2155 | * fail without consequence, stop if we failed to reclaim | |
2156 | * any pages from the last SWAP_CLUSTER_MAX number of | |
2157 | * pages that were scanned. This will return to the | |
2158 | * caller faster at the risk reclaim/compaction and | |
2159 | * the resulting allocation attempt fails | |
2160 | */ | |
2161 | if (!nr_reclaimed) | |
2162 | return false; | |
2163 | } | |
3e7d3449 MG |
2164 | |
2165 | /* | |
2166 | * If we have not reclaimed enough pages for compaction and the | |
2167 | * inactive lists are large enough, continue reclaiming | |
2168 | */ | |
2169 | pages_for_compaction = (2UL << sc->order); | |
9b4f98cd | 2170 | inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE); |
ec8acf20 | 2171 | if (get_nr_swap_pages() > 0) |
9b4f98cd | 2172 | inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON); |
3e7d3449 MG |
2173 | if (sc->nr_reclaimed < pages_for_compaction && |
2174 | inactive_lru_pages > pages_for_compaction) | |
2175 | return true; | |
2176 | ||
2177 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
9b4f98cd | 2178 | switch (compaction_suitable(zone, sc->order)) { |
3e7d3449 MG |
2179 | case COMPACT_PARTIAL: |
2180 | case COMPACT_CONTINUE: | |
2181 | return false; | |
2182 | default: | |
2183 | return true; | |
2184 | } | |
2185 | } | |
2186 | ||
0608f43d | 2187 | static void shrink_zone(struct zone *zone, struct scan_control *sc) |
1da177e4 | 2188 | { |
f0fdc5e8 | 2189 | unsigned long nr_reclaimed, nr_scanned; |
1da177e4 | 2190 | |
9b4f98cd JW |
2191 | do { |
2192 | struct mem_cgroup *root = sc->target_mem_cgroup; | |
2193 | struct mem_cgroup_reclaim_cookie reclaim = { | |
2194 | .zone = zone, | |
2195 | .priority = sc->priority, | |
2196 | }; | |
694fbc0f | 2197 | struct mem_cgroup *memcg; |
3e7d3449 | 2198 | |
9b4f98cd JW |
2199 | nr_reclaimed = sc->nr_reclaimed; |
2200 | nr_scanned = sc->nr_scanned; | |
1da177e4 | 2201 | |
694fbc0f AM |
2202 | memcg = mem_cgroup_iter(root, NULL, &reclaim); |
2203 | do { | |
9b4f98cd | 2204 | struct lruvec *lruvec; |
5660048c | 2205 | |
9b4f98cd | 2206 | lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
f9be23d6 | 2207 | |
9b4f98cd | 2208 | shrink_lruvec(lruvec, sc); |
f16015fb | 2209 | |
9b4f98cd | 2210 | /* |
a394cb8e MH |
2211 | * Direct reclaim and kswapd have to scan all memory |
2212 | * cgroups to fulfill the overall scan target for the | |
9b4f98cd | 2213 | * zone. |
a394cb8e MH |
2214 | * |
2215 | * Limit reclaim, on the other hand, only cares about | |
2216 | * nr_to_reclaim pages to be reclaimed and it will | |
2217 | * retry with decreasing priority if one round over the | |
2218 | * whole hierarchy is not sufficient. | |
9b4f98cd | 2219 | */ |
a394cb8e MH |
2220 | if (!global_reclaim(sc) && |
2221 | sc->nr_reclaimed >= sc->nr_to_reclaim) { | |
9b4f98cd JW |
2222 | mem_cgroup_iter_break(root, memcg); |
2223 | break; | |
2224 | } | |
694fbc0f AM |
2225 | memcg = mem_cgroup_iter(root, memcg, &reclaim); |
2226 | } while (memcg); | |
70ddf637 AV |
2227 | |
2228 | vmpressure(sc->gfp_mask, sc->target_mem_cgroup, | |
2229 | sc->nr_scanned - nr_scanned, | |
2230 | sc->nr_reclaimed - nr_reclaimed); | |
2231 | ||
9b4f98cd JW |
2232 | } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed, |
2233 | sc->nr_scanned - nr_scanned, sc)); | |
f16015fb JW |
2234 | } |
2235 | ||
fe4b1b24 MG |
2236 | /* Returns true if compaction should go ahead for a high-order request */ |
2237 | static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) | |
2238 | { | |
2239 | unsigned long balance_gap, watermark; | |
2240 | bool watermark_ok; | |
2241 | ||
2242 | /* Do not consider compaction for orders reclaim is meant to satisfy */ | |
2243 | if (sc->order <= PAGE_ALLOC_COSTLY_ORDER) | |
2244 | return false; | |
2245 | ||
2246 | /* | |
2247 | * Compaction takes time to run and there are potentially other | |
2248 | * callers using the pages just freed. Continue reclaiming until | |
2249 | * there is a buffer of free pages available to give compaction | |
2250 | * a reasonable chance of completing and allocating the page | |
2251 | */ | |
2252 | balance_gap = min(low_wmark_pages(zone), | |
b40da049 | 2253 | (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / |
fe4b1b24 MG |
2254 | KSWAPD_ZONE_BALANCE_GAP_RATIO); |
2255 | watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order); | |
2256 | watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0); | |
2257 | ||
2258 | /* | |
2259 | * If compaction is deferred, reclaim up to a point where | |
2260 | * compaction will have a chance of success when re-enabled | |
2261 | */ | |
aff62249 | 2262 | if (compaction_deferred(zone, sc->order)) |
fe4b1b24 MG |
2263 | return watermark_ok; |
2264 | ||
2265 | /* If compaction is not ready to start, keep reclaiming */ | |
2266 | if (!compaction_suitable(zone, sc->order)) | |
2267 | return false; | |
2268 | ||
2269 | return watermark_ok; | |
2270 | } | |
2271 | ||
1da177e4 LT |
2272 | /* |
2273 | * This is the direct reclaim path, for page-allocating processes. We only | |
2274 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2275 | * request. | |
2276 | * | |
41858966 MG |
2277 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
2278 | * Because: | |
1da177e4 LT |
2279 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
2280 | * allocation or | |
41858966 MG |
2281 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
2282 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
2283 | * zone defense algorithm. | |
1da177e4 | 2284 | * |
1da177e4 LT |
2285 | * If a zone is deemed to be full of pinned pages then just give it a light |
2286 | * scan then give up on it. | |
e0c23279 MG |
2287 | * |
2288 | * This function returns true if a zone is being reclaimed for a costly | |
fe4b1b24 | 2289 | * high-order allocation and compaction is ready to begin. This indicates to |
0cee34fd MG |
2290 | * the caller that it should consider retrying the allocation instead of |
2291 | * further reclaim. | |
1da177e4 | 2292 | */ |
9e3b2f8c | 2293 | static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) |
1da177e4 | 2294 | { |
dd1a239f | 2295 | struct zoneref *z; |
54a6eb5c | 2296 | struct zone *zone; |
0608f43d AM |
2297 | unsigned long nr_soft_reclaimed; |
2298 | unsigned long nr_soft_scanned; | |
0cee34fd | 2299 | bool aborted_reclaim = false; |
1cfb419b | 2300 | |
cc715d99 MG |
2301 | /* |
2302 | * If the number of buffer_heads in the machine exceeds the maximum | |
2303 | * allowed level, force direct reclaim to scan the highmem zone as | |
2304 | * highmem pages could be pinning lowmem pages storing buffer_heads | |
2305 | */ | |
2306 | if (buffer_heads_over_limit) | |
2307 | sc->gfp_mask |= __GFP_HIGHMEM; | |
2308 | ||
d4debc66 MG |
2309 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
2310 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 2311 | if (!populated_zone(zone)) |
1da177e4 | 2312 | continue; |
1cfb419b KH |
2313 | /* |
2314 | * Take care memory controller reclaiming has small influence | |
2315 | * to global LRU. | |
2316 | */ | |
89b5fae5 | 2317 | if (global_reclaim(sc)) { |
1cfb419b KH |
2318 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2319 | continue; | |
6e543d57 LD |
2320 | if (sc->priority != DEF_PRIORITY && |
2321 | !zone_reclaimable(zone)) | |
1cfb419b | 2322 | continue; /* Let kswapd poll it */ |
d84da3f9 | 2323 | if (IS_ENABLED(CONFIG_COMPACTION)) { |
e0887c19 | 2324 | /* |
e0c23279 MG |
2325 | * If we already have plenty of memory free for |
2326 | * compaction in this zone, don't free any more. | |
2327 | * Even though compaction is invoked for any | |
2328 | * non-zero order, only frequent costly order | |
2329 | * reclamation is disruptive enough to become a | |
c7cfa37b CA |
2330 | * noticeable problem, like transparent huge |
2331 | * page allocations. | |
e0887c19 | 2332 | */ |
fe4b1b24 | 2333 | if (compaction_ready(zone, sc)) { |
0cee34fd | 2334 | aborted_reclaim = true; |
e0887c19 | 2335 | continue; |
e0c23279 | 2336 | } |
e0887c19 | 2337 | } |
0608f43d AM |
2338 | /* |
2339 | * This steals pages from memory cgroups over softlimit | |
2340 | * and returns the number of reclaimed pages and | |
2341 | * scanned pages. This works for global memory pressure | |
2342 | * and balancing, not for a memcg's limit. | |
2343 | */ | |
2344 | nr_soft_scanned = 0; | |
2345 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
2346 | sc->order, sc->gfp_mask, | |
2347 | &nr_soft_scanned); | |
2348 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2349 | sc->nr_scanned += nr_soft_scanned; | |
ac34a1a3 | 2350 | /* need some check for avoid more shrink_zone() */ |
1cfb419b | 2351 | } |
408d8544 | 2352 | |
9e3b2f8c | 2353 | shrink_zone(zone, sc); |
1da177e4 | 2354 | } |
e0c23279 | 2355 | |
0cee34fd | 2356 | return aborted_reclaim; |
d1908362 MK |
2357 | } |
2358 | ||
929bea7c | 2359 | /* All zones in zonelist are unreclaimable? */ |
d1908362 MK |
2360 | static bool all_unreclaimable(struct zonelist *zonelist, |
2361 | struct scan_control *sc) | |
2362 | { | |
2363 | struct zoneref *z; | |
2364 | struct zone *zone; | |
d1908362 MK |
2365 | |
2366 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
2367 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
2368 | if (!populated_zone(zone)) | |
2369 | continue; | |
2370 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
2371 | continue; | |
6e543d57 | 2372 | if (zone_reclaimable(zone)) |
929bea7c | 2373 | return false; |
d1908362 MK |
2374 | } |
2375 | ||
929bea7c | 2376 | return true; |
1da177e4 | 2377 | } |
4f98a2fe | 2378 | |
1da177e4 LT |
2379 | /* |
2380 | * This is the main entry point to direct page reclaim. | |
2381 | * | |
2382 | * If a full scan of the inactive list fails to free enough memory then we | |
2383 | * are "out of memory" and something needs to be killed. | |
2384 | * | |
2385 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2386 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2387 | * caller can't do much about. We kick the writeback threads and take explicit |
2388 | * naps in the hope that some of these pages can be written. But if the | |
2389 | * allocating task holds filesystem locks which prevent writeout this might not | |
2390 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2391 | * |
2392 | * returns: 0, if no pages reclaimed | |
2393 | * else, the number of pages reclaimed | |
1da177e4 | 2394 | */ |
dac1d27b | 2395 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
a09ed5e0 YH |
2396 | struct scan_control *sc, |
2397 | struct shrink_control *shrink) | |
1da177e4 | 2398 | { |
69e05944 | 2399 | unsigned long total_scanned = 0; |
1da177e4 | 2400 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2401 | struct zoneref *z; |
54a6eb5c | 2402 | struct zone *zone; |
22fba335 | 2403 | unsigned long writeback_threshold; |
0cee34fd | 2404 | bool aborted_reclaim; |
1da177e4 | 2405 | |
873b4771 KK |
2406 | delayacct_freepages_start(); |
2407 | ||
89b5fae5 | 2408 | if (global_reclaim(sc)) |
1cfb419b | 2409 | count_vm_event(ALLOCSTALL); |
1da177e4 | 2410 | |
9e3b2f8c | 2411 | do { |
70ddf637 AV |
2412 | vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, |
2413 | sc->priority); | |
66e1707b | 2414 | sc->nr_scanned = 0; |
9e3b2f8c | 2415 | aborted_reclaim = shrink_zones(zonelist, sc); |
e0c23279 | 2416 | |
66e1707b | 2417 | /* |
5a1c9cbc MG |
2418 | * Don't shrink slabs when reclaiming memory from over limit |
2419 | * cgroups but do shrink slab at least once when aborting | |
2420 | * reclaim for compaction to avoid unevenly scanning file/anon | |
2421 | * LRU pages over slab pages. | |
66e1707b | 2422 | */ |
89b5fae5 | 2423 | if (global_reclaim(sc)) { |
c6a8a8c5 | 2424 | unsigned long lru_pages = 0; |
0ce3d744 DC |
2425 | |
2426 | nodes_clear(shrink->nodes_to_scan); | |
d4debc66 MG |
2427 | for_each_zone_zonelist(zone, z, zonelist, |
2428 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2429 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2430 | continue; | |
2431 | ||
2432 | lru_pages += zone_reclaimable_pages(zone); | |
0ce3d744 DC |
2433 | node_set(zone_to_nid(zone), |
2434 | shrink->nodes_to_scan); | |
c6a8a8c5 KM |
2435 | } |
2436 | ||
1495f230 | 2437 | shrink_slab(shrink, sc->nr_scanned, lru_pages); |
91a45470 | 2438 | if (reclaim_state) { |
a79311c1 | 2439 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2440 | reclaim_state->reclaimed_slab = 0; |
2441 | } | |
1da177e4 | 2442 | } |
66e1707b | 2443 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2444 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2445 | goto out; |
1da177e4 | 2446 | |
0e50ce3b MK |
2447 | /* |
2448 | * If we're getting trouble reclaiming, start doing | |
2449 | * writepage even in laptop mode. | |
2450 | */ | |
2451 | if (sc->priority < DEF_PRIORITY - 2) | |
2452 | sc->may_writepage = 1; | |
2453 | ||
1da177e4 LT |
2454 | /* |
2455 | * Try to write back as many pages as we just scanned. This | |
2456 | * tends to cause slow streaming writers to write data to the | |
2457 | * disk smoothly, at the dirtying rate, which is nice. But | |
2458 | * that's undesirable in laptop mode, where we *want* lumpy | |
2459 | * writeout. So in laptop mode, write out the whole world. | |
2460 | */ | |
22fba335 KM |
2461 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2462 | if (total_scanned > writeback_threshold) { | |
0e175a18 CW |
2463 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned, |
2464 | WB_REASON_TRY_TO_FREE_PAGES); | |
66e1707b | 2465 | sc->may_writepage = 1; |
1da177e4 | 2466 | } |
5a1c9cbc | 2467 | } while (--sc->priority >= 0 && !aborted_reclaim); |
bb21c7ce | 2468 | |
1da177e4 | 2469 | out: |
873b4771 KK |
2470 | delayacct_freepages_end(); |
2471 | ||
bb21c7ce KM |
2472 | if (sc->nr_reclaimed) |
2473 | return sc->nr_reclaimed; | |
2474 | ||
929bea7c KM |
2475 | /* |
2476 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
2477 | * the zone into all_unreclaimable. Thus bypassing all_unreclaimable | |
2478 | * check. | |
2479 | */ | |
2480 | if (oom_killer_disabled) | |
2481 | return 0; | |
2482 | ||
0cee34fd MG |
2483 | /* Aborted reclaim to try compaction? don't OOM, then */ |
2484 | if (aborted_reclaim) | |
7335084d MG |
2485 | return 1; |
2486 | ||
bb21c7ce | 2487 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
89b5fae5 | 2488 | if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2489 | return 1; |
2490 | ||
2491 | return 0; | |
1da177e4 LT |
2492 | } |
2493 | ||
5515061d MG |
2494 | static bool pfmemalloc_watermark_ok(pg_data_t *pgdat) |
2495 | { | |
2496 | struct zone *zone; | |
2497 | unsigned long pfmemalloc_reserve = 0; | |
2498 | unsigned long free_pages = 0; | |
2499 | int i; | |
2500 | bool wmark_ok; | |
2501 | ||
2502 | for (i = 0; i <= ZONE_NORMAL; i++) { | |
2503 | zone = &pgdat->node_zones[i]; | |
2504 | pfmemalloc_reserve += min_wmark_pages(zone); | |
2505 | free_pages += zone_page_state(zone, NR_FREE_PAGES); | |
2506 | } | |
2507 | ||
2508 | wmark_ok = free_pages > pfmemalloc_reserve / 2; | |
2509 | ||
2510 | /* kswapd must be awake if processes are being throttled */ | |
2511 | if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { | |
2512 | pgdat->classzone_idx = min(pgdat->classzone_idx, | |
2513 | (enum zone_type)ZONE_NORMAL); | |
2514 | wake_up_interruptible(&pgdat->kswapd_wait); | |
2515 | } | |
2516 | ||
2517 | return wmark_ok; | |
2518 | } | |
2519 | ||
2520 | /* | |
2521 | * Throttle direct reclaimers if backing storage is backed by the network | |
2522 | * and the PFMEMALLOC reserve for the preferred node is getting dangerously | |
2523 | * depleted. kswapd will continue to make progress and wake the processes | |
50694c28 MG |
2524 | * when the low watermark is reached. |
2525 | * | |
2526 | * Returns true if a fatal signal was delivered during throttling. If this | |
2527 | * happens, the page allocator should not consider triggering the OOM killer. | |
5515061d | 2528 | */ |
50694c28 | 2529 | static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, |
5515061d MG |
2530 | nodemask_t *nodemask) |
2531 | { | |
2532 | struct zone *zone; | |
2533 | int high_zoneidx = gfp_zone(gfp_mask); | |
2534 | pg_data_t *pgdat; | |
2535 | ||
2536 | /* | |
2537 | * Kernel threads should not be throttled as they may be indirectly | |
2538 | * responsible for cleaning pages necessary for reclaim to make forward | |
2539 | * progress. kjournald for example may enter direct reclaim while | |
2540 | * committing a transaction where throttling it could forcing other | |
2541 | * processes to block on log_wait_commit(). | |
2542 | */ | |
2543 | if (current->flags & PF_KTHREAD) | |
50694c28 MG |
2544 | goto out; |
2545 | ||
2546 | /* | |
2547 | * If a fatal signal is pending, this process should not throttle. | |
2548 | * It should return quickly so it can exit and free its memory | |
2549 | */ | |
2550 | if (fatal_signal_pending(current)) | |
2551 | goto out; | |
5515061d MG |
2552 | |
2553 | /* Check if the pfmemalloc reserves are ok */ | |
2554 | first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone); | |
2555 | pgdat = zone->zone_pgdat; | |
2556 | if (pfmemalloc_watermark_ok(pgdat)) | |
50694c28 | 2557 | goto out; |
5515061d | 2558 | |
68243e76 MG |
2559 | /* Account for the throttling */ |
2560 | count_vm_event(PGSCAN_DIRECT_THROTTLE); | |
2561 | ||
5515061d MG |
2562 | /* |
2563 | * If the caller cannot enter the filesystem, it's possible that it | |
2564 | * is due to the caller holding an FS lock or performing a journal | |
2565 | * transaction in the case of a filesystem like ext[3|4]. In this case, | |
2566 | * it is not safe to block on pfmemalloc_wait as kswapd could be | |
2567 | * blocked waiting on the same lock. Instead, throttle for up to a | |
2568 | * second before continuing. | |
2569 | */ | |
2570 | if (!(gfp_mask & __GFP_FS)) { | |
2571 | wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, | |
2572 | pfmemalloc_watermark_ok(pgdat), HZ); | |
50694c28 MG |
2573 | |
2574 | goto check_pending; | |
5515061d MG |
2575 | } |
2576 | ||
2577 | /* Throttle until kswapd wakes the process */ | |
2578 | wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, | |
2579 | pfmemalloc_watermark_ok(pgdat)); | |
50694c28 MG |
2580 | |
2581 | check_pending: | |
2582 | if (fatal_signal_pending(current)) | |
2583 | return true; | |
2584 | ||
2585 | out: | |
2586 | return false; | |
5515061d MG |
2587 | } |
2588 | ||
dac1d27b | 2589 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2590 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2591 | { |
33906bc5 | 2592 | unsigned long nr_reclaimed; |
66e1707b | 2593 | struct scan_control sc = { |
21caf2fc | 2594 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
66e1707b | 2595 | .may_writepage = !laptop_mode, |
22fba335 | 2596 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2597 | .may_unmap = 1, |
2e2e4259 | 2598 | .may_swap = 1, |
66e1707b | 2599 | .order = order, |
9e3b2f8c | 2600 | .priority = DEF_PRIORITY, |
f16015fb | 2601 | .target_mem_cgroup = NULL, |
327c0e96 | 2602 | .nodemask = nodemask, |
66e1707b | 2603 | }; |
a09ed5e0 YH |
2604 | struct shrink_control shrink = { |
2605 | .gfp_mask = sc.gfp_mask, | |
2606 | }; | |
66e1707b | 2607 | |
5515061d | 2608 | /* |
50694c28 MG |
2609 | * Do not enter reclaim if fatal signal was delivered while throttled. |
2610 | * 1 is returned so that the page allocator does not OOM kill at this | |
2611 | * point. | |
5515061d | 2612 | */ |
50694c28 | 2613 | if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) |
5515061d MG |
2614 | return 1; |
2615 | ||
33906bc5 MG |
2616 | trace_mm_vmscan_direct_reclaim_begin(order, |
2617 | sc.may_writepage, | |
2618 | gfp_mask); | |
2619 | ||
a09ed5e0 | 2620 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
33906bc5 MG |
2621 | |
2622 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2623 | ||
2624 | return nr_reclaimed; | |
66e1707b BS |
2625 | } |
2626 | ||
c255a458 | 2627 | #ifdef CONFIG_MEMCG |
66e1707b | 2628 | |
72835c86 | 2629 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg, |
4e416953 | 2630 | gfp_t gfp_mask, bool noswap, |
0ae5e89c YH |
2631 | struct zone *zone, |
2632 | unsigned long *nr_scanned) | |
4e416953 BS |
2633 | { |
2634 | struct scan_control sc = { | |
0ae5e89c | 2635 | .nr_scanned = 0, |
b8f5c566 | 2636 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2637 | .may_writepage = !laptop_mode, |
2638 | .may_unmap = 1, | |
2639 | .may_swap = !noswap, | |
4e416953 | 2640 | .order = 0, |
9e3b2f8c | 2641 | .priority = 0, |
72835c86 | 2642 | .target_mem_cgroup = memcg, |
4e416953 | 2643 | }; |
f9be23d6 | 2644 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
0ae5e89c | 2645 | |
4e416953 BS |
2646 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2647 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e | 2648 | |
9e3b2f8c | 2649 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, |
bdce6d9e KM |
2650 | sc.may_writepage, |
2651 | sc.gfp_mask); | |
2652 | ||
4e416953 BS |
2653 | /* |
2654 | * NOTE: Although we can get the priority field, using it | |
2655 | * here is not a good idea, since it limits the pages we can scan. | |
2656 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2657 | * will pick up pages from other mem cgroup's as well. We hack | |
2658 | * the priority and make it zero. | |
2659 | */ | |
f9be23d6 | 2660 | shrink_lruvec(lruvec, &sc); |
bdce6d9e KM |
2661 | |
2662 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2663 | ||
0ae5e89c | 2664 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2665 | return sc.nr_reclaimed; |
2666 | } | |
2667 | ||
72835c86 | 2668 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, |
a7885eb8 | 2669 | gfp_t gfp_mask, |
185efc0f | 2670 | bool noswap) |
66e1707b | 2671 | { |
4e416953 | 2672 | struct zonelist *zonelist; |
bdce6d9e | 2673 | unsigned long nr_reclaimed; |
889976db | 2674 | int nid; |
66e1707b | 2675 | struct scan_control sc = { |
66e1707b | 2676 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2677 | .may_unmap = 1, |
2e2e4259 | 2678 | .may_swap = !noswap, |
22fba335 | 2679 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
66e1707b | 2680 | .order = 0, |
9e3b2f8c | 2681 | .priority = DEF_PRIORITY, |
72835c86 | 2682 | .target_mem_cgroup = memcg, |
327c0e96 | 2683 | .nodemask = NULL, /* we don't care the placement */ |
a09ed5e0 YH |
2684 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2685 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
2686 | }; | |
2687 | struct shrink_control shrink = { | |
2688 | .gfp_mask = sc.gfp_mask, | |
66e1707b | 2689 | }; |
66e1707b | 2690 | |
889976db YH |
2691 | /* |
2692 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
2693 | * take care of from where we get pages. So the node where we start the | |
2694 | * scan does not need to be the current node. | |
2695 | */ | |
72835c86 | 2696 | nid = mem_cgroup_select_victim_node(memcg); |
889976db YH |
2697 | |
2698 | zonelist = NODE_DATA(nid)->node_zonelists; | |
bdce6d9e KM |
2699 | |
2700 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2701 | sc.may_writepage, | |
2702 | sc.gfp_mask); | |
2703 | ||
a09ed5e0 | 2704 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
bdce6d9e KM |
2705 | |
2706 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2707 | ||
2708 | return nr_reclaimed; | |
66e1707b BS |
2709 | } |
2710 | #endif | |
2711 | ||
9e3b2f8c | 2712 | static void age_active_anon(struct zone *zone, struct scan_control *sc) |
f16015fb | 2713 | { |
b95a2f2d | 2714 | struct mem_cgroup *memcg; |
f16015fb | 2715 | |
b95a2f2d JW |
2716 | if (!total_swap_pages) |
2717 | return; | |
2718 | ||
2719 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | |
2720 | do { | |
c56d5c7d | 2721 | struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg); |
b95a2f2d | 2722 | |
c56d5c7d | 2723 | if (inactive_anon_is_low(lruvec)) |
1a93be0e | 2724 | shrink_active_list(SWAP_CLUSTER_MAX, lruvec, |
9e3b2f8c | 2725 | sc, LRU_ACTIVE_ANON); |
b95a2f2d JW |
2726 | |
2727 | memcg = mem_cgroup_iter(NULL, memcg, NULL); | |
2728 | } while (memcg); | |
f16015fb JW |
2729 | } |
2730 | ||
60cefed4 JW |
2731 | static bool zone_balanced(struct zone *zone, int order, |
2732 | unsigned long balance_gap, int classzone_idx) | |
2733 | { | |
2734 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) + | |
2735 | balance_gap, classzone_idx, 0)) | |
2736 | return false; | |
2737 | ||
d84da3f9 KS |
2738 | if (IS_ENABLED(CONFIG_COMPACTION) && order && |
2739 | !compaction_suitable(zone, order)) | |
60cefed4 JW |
2740 | return false; |
2741 | ||
2742 | return true; | |
2743 | } | |
2744 | ||
1741c877 | 2745 | /* |
4ae0a48b ZC |
2746 | * pgdat_balanced() is used when checking if a node is balanced. |
2747 | * | |
2748 | * For order-0, all zones must be balanced! | |
2749 | * | |
2750 | * For high-order allocations only zones that meet watermarks and are in a | |
2751 | * zone allowed by the callers classzone_idx are added to balanced_pages. The | |
2752 | * total of balanced pages must be at least 25% of the zones allowed by | |
2753 | * classzone_idx for the node to be considered balanced. Forcing all zones to | |
2754 | * be balanced for high orders can cause excessive reclaim when there are | |
2755 | * imbalanced zones. | |
1741c877 MG |
2756 | * The choice of 25% is due to |
2757 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2758 | * reasonable sized machine | |
2759 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2760 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2761 | * would need to be at least 256M for it to be balance a whole node. |
2762 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2763 | * to balance a node on its own. These seemed like reasonable ratios. | |
2764 | */ | |
4ae0a48b | 2765 | static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) |
1741c877 | 2766 | { |
b40da049 | 2767 | unsigned long managed_pages = 0; |
4ae0a48b | 2768 | unsigned long balanced_pages = 0; |
1741c877 MG |
2769 | int i; |
2770 | ||
4ae0a48b ZC |
2771 | /* Check the watermark levels */ |
2772 | for (i = 0; i <= classzone_idx; i++) { | |
2773 | struct zone *zone = pgdat->node_zones + i; | |
1741c877 | 2774 | |
4ae0a48b ZC |
2775 | if (!populated_zone(zone)) |
2776 | continue; | |
2777 | ||
b40da049 | 2778 | managed_pages += zone->managed_pages; |
4ae0a48b ZC |
2779 | |
2780 | /* | |
2781 | * A special case here: | |
2782 | * | |
2783 | * balance_pgdat() skips over all_unreclaimable after | |
2784 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2785 | * they must be considered balanced here as well! | |
2786 | */ | |
6e543d57 | 2787 | if (!zone_reclaimable(zone)) { |
b40da049 | 2788 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2789 | continue; |
2790 | } | |
2791 | ||
2792 | if (zone_balanced(zone, order, 0, i)) | |
b40da049 | 2793 | balanced_pages += zone->managed_pages; |
4ae0a48b ZC |
2794 | else if (!order) |
2795 | return false; | |
2796 | } | |
2797 | ||
2798 | if (order) | |
b40da049 | 2799 | return balanced_pages >= (managed_pages >> 2); |
4ae0a48b ZC |
2800 | else |
2801 | return true; | |
1741c877 MG |
2802 | } |
2803 | ||
5515061d MG |
2804 | /* |
2805 | * Prepare kswapd for sleeping. This verifies that there are no processes | |
2806 | * waiting in throttle_direct_reclaim() and that watermarks have been met. | |
2807 | * | |
2808 | * Returns true if kswapd is ready to sleep | |
2809 | */ | |
2810 | static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, | |
dc83edd9 | 2811 | int classzone_idx) |
f50de2d3 | 2812 | { |
f50de2d3 MG |
2813 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ |
2814 | if (remaining) | |
5515061d MG |
2815 | return false; |
2816 | ||
2817 | /* | |
2818 | * There is a potential race between when kswapd checks its watermarks | |
2819 | * and a process gets throttled. There is also a potential race if | |
2820 | * processes get throttled, kswapd wakes, a large process exits therby | |
2821 | * balancing the zones that causes kswapd to miss a wakeup. If kswapd | |
2822 | * is going to sleep, no process should be sleeping on pfmemalloc_wait | |
2823 | * so wake them now if necessary. If necessary, processes will wake | |
2824 | * kswapd and get throttled again | |
2825 | */ | |
2826 | if (waitqueue_active(&pgdat->pfmemalloc_wait)) { | |
2827 | wake_up(&pgdat->pfmemalloc_wait); | |
2828 | return false; | |
2829 | } | |
f50de2d3 | 2830 | |
4ae0a48b | 2831 | return pgdat_balanced(pgdat, order, classzone_idx); |
f50de2d3 MG |
2832 | } |
2833 | ||
75485363 MG |
2834 | /* |
2835 | * kswapd shrinks the zone by the number of pages required to reach | |
2836 | * the high watermark. | |
b8e83b94 MG |
2837 | * |
2838 | * Returns true if kswapd scanned at least the requested number of pages to | |
283aba9f MG |
2839 | * reclaim or if the lack of progress was due to pages under writeback. |
2840 | * This is used to determine if the scanning priority needs to be raised. | |
75485363 | 2841 | */ |
b8e83b94 | 2842 | static bool kswapd_shrink_zone(struct zone *zone, |
7c954f6d | 2843 | int classzone_idx, |
75485363 | 2844 | struct scan_control *sc, |
2ab44f43 MG |
2845 | unsigned long lru_pages, |
2846 | unsigned long *nr_attempted) | |
75485363 | 2847 | { |
7c954f6d MG |
2848 | int testorder = sc->order; |
2849 | unsigned long balance_gap; | |
75485363 MG |
2850 | struct reclaim_state *reclaim_state = current->reclaim_state; |
2851 | struct shrink_control shrink = { | |
2852 | .gfp_mask = sc->gfp_mask, | |
2853 | }; | |
7c954f6d | 2854 | bool lowmem_pressure; |
75485363 MG |
2855 | |
2856 | /* Reclaim above the high watermark. */ | |
2857 | sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); | |
7c954f6d MG |
2858 | |
2859 | /* | |
2860 | * Kswapd reclaims only single pages with compaction enabled. Trying | |
2861 | * too hard to reclaim until contiguous free pages have become | |
2862 | * available can hurt performance by evicting too much useful data | |
2863 | * from memory. Do not reclaim more than needed for compaction. | |
2864 | */ | |
2865 | if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && | |
2866 | compaction_suitable(zone, sc->order) != | |
2867 | COMPACT_SKIPPED) | |
2868 | testorder = 0; | |
2869 | ||
2870 | /* | |
2871 | * We put equal pressure on every zone, unless one zone has way too | |
2872 | * many pages free already. The "too many pages" is defined as the | |
2873 | * high wmark plus a "gap" where the gap is either the low | |
2874 | * watermark or 1% of the zone, whichever is smaller. | |
2875 | */ | |
2876 | balance_gap = min(low_wmark_pages(zone), | |
2877 | (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / | |
2878 | KSWAPD_ZONE_BALANCE_GAP_RATIO); | |
2879 | ||
2880 | /* | |
2881 | * If there is no low memory pressure or the zone is balanced then no | |
2882 | * reclaim is necessary | |
2883 | */ | |
2884 | lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone)); | |
2885 | if (!lowmem_pressure && zone_balanced(zone, testorder, | |
2886 | balance_gap, classzone_idx)) | |
2887 | return true; | |
2888 | ||
75485363 | 2889 | shrink_zone(zone, sc); |
0ce3d744 DC |
2890 | nodes_clear(shrink.nodes_to_scan); |
2891 | node_set(zone_to_nid(zone), shrink.nodes_to_scan); | |
75485363 MG |
2892 | |
2893 | reclaim_state->reclaimed_slab = 0; | |
6e543d57 | 2894 | shrink_slab(&shrink, sc->nr_scanned, lru_pages); |
75485363 MG |
2895 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
2896 | ||
2ab44f43 MG |
2897 | /* Account for the number of pages attempted to reclaim */ |
2898 | *nr_attempted += sc->nr_to_reclaim; | |
2899 | ||
283aba9f MG |
2900 | zone_clear_flag(zone, ZONE_WRITEBACK); |
2901 | ||
7c954f6d MG |
2902 | /* |
2903 | * If a zone reaches its high watermark, consider it to be no longer | |
2904 | * congested. It's possible there are dirty pages backed by congested | |
2905 | * BDIs but as pressure is relieved, speculatively avoid congestion | |
2906 | * waits. | |
2907 | */ | |
6e543d57 | 2908 | if (zone_reclaimable(zone) && |
7c954f6d MG |
2909 | zone_balanced(zone, testorder, 0, classzone_idx)) { |
2910 | zone_clear_flag(zone, ZONE_CONGESTED); | |
2911 | zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY); | |
2912 | } | |
2913 | ||
b8e83b94 | 2914 | return sc->nr_scanned >= sc->nr_to_reclaim; |
75485363 MG |
2915 | } |
2916 | ||
1da177e4 LT |
2917 | /* |
2918 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2919 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2920 | * |
0abdee2b | 2921 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
2922 | * |
2923 | * There is special handling here for zones which are full of pinned pages. | |
2924 | * This can happen if the pages are all mlocked, or if they are all used by | |
2925 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2926 | * What we do is to detect the case where all pages in the zone have been | |
2927 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2928 | * dead and from now on, only perform a short scan. Basically we're polling | |
2929 | * the zone for when the problem goes away. | |
2930 | * | |
2931 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2932 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2933 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2934 | * lower zones regardless of the number of free pages in the lower zones. This | |
2935 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2936 | * of pages is balanced across the zones. | |
1da177e4 | 2937 | */ |
99504748 | 2938 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 2939 | int *classzone_idx) |
1da177e4 | 2940 | { |
1da177e4 | 2941 | int i; |
99504748 | 2942 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
0608f43d AM |
2943 | unsigned long nr_soft_reclaimed; |
2944 | unsigned long nr_soft_scanned; | |
179e9639 AM |
2945 | struct scan_control sc = { |
2946 | .gfp_mask = GFP_KERNEL, | |
b8e83b94 | 2947 | .priority = DEF_PRIORITY, |
a6dc60f8 | 2948 | .may_unmap = 1, |
2e2e4259 | 2949 | .may_swap = 1, |
b8e83b94 | 2950 | .may_writepage = !laptop_mode, |
5ad333eb | 2951 | .order = order, |
f16015fb | 2952 | .target_mem_cgroup = NULL, |
179e9639 | 2953 | }; |
f8891e5e | 2954 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2955 | |
9e3b2f8c | 2956 | do { |
1da177e4 | 2957 | unsigned long lru_pages = 0; |
2ab44f43 | 2958 | unsigned long nr_attempted = 0; |
b8e83b94 | 2959 | bool raise_priority = true; |
2ab44f43 | 2960 | bool pgdat_needs_compaction = (order > 0); |
b8e83b94 MG |
2961 | |
2962 | sc.nr_reclaimed = 0; | |
1da177e4 | 2963 | |
d6277db4 RW |
2964 | /* |
2965 | * Scan in the highmem->dma direction for the highest | |
2966 | * zone which needs scanning | |
2967 | */ | |
2968 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2969 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2970 | |
d6277db4 RW |
2971 | if (!populated_zone(zone)) |
2972 | continue; | |
1da177e4 | 2973 | |
6e543d57 LD |
2974 | if (sc.priority != DEF_PRIORITY && |
2975 | !zone_reclaimable(zone)) | |
d6277db4 | 2976 | continue; |
1da177e4 | 2977 | |
556adecb RR |
2978 | /* |
2979 | * Do some background aging of the anon list, to give | |
2980 | * pages a chance to be referenced before reclaiming. | |
2981 | */ | |
9e3b2f8c | 2982 | age_active_anon(zone, &sc); |
556adecb | 2983 | |
cc715d99 MG |
2984 | /* |
2985 | * If the number of buffer_heads in the machine | |
2986 | * exceeds the maximum allowed level and this node | |
2987 | * has a highmem zone, force kswapd to reclaim from | |
2988 | * it to relieve lowmem pressure. | |
2989 | */ | |
2990 | if (buffer_heads_over_limit && is_highmem_idx(i)) { | |
2991 | end_zone = i; | |
2992 | break; | |
2993 | } | |
2994 | ||
60cefed4 | 2995 | if (!zone_balanced(zone, order, 0, 0)) { |
d6277db4 | 2996 | end_zone = i; |
e1dbeda6 | 2997 | break; |
439423f6 | 2998 | } else { |
d43006d5 MG |
2999 | /* |
3000 | * If balanced, clear the dirty and congested | |
3001 | * flags | |
3002 | */ | |
439423f6 | 3003 | zone_clear_flag(zone, ZONE_CONGESTED); |
d43006d5 | 3004 | zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY); |
1da177e4 | 3005 | } |
1da177e4 | 3006 | } |
dafcb73e | 3007 | |
b8e83b94 | 3008 | if (i < 0) |
e1dbeda6 AM |
3009 | goto out; |
3010 | ||
1da177e4 LT |
3011 | for (i = 0; i <= end_zone; i++) { |
3012 | struct zone *zone = pgdat->node_zones + i; | |
3013 | ||
2ab44f43 MG |
3014 | if (!populated_zone(zone)) |
3015 | continue; | |
3016 | ||
adea02a1 | 3017 | lru_pages += zone_reclaimable_pages(zone); |
2ab44f43 MG |
3018 | |
3019 | /* | |
3020 | * If any zone is currently balanced then kswapd will | |
3021 | * not call compaction as it is expected that the | |
3022 | * necessary pages are already available. | |
3023 | */ | |
3024 | if (pgdat_needs_compaction && | |
3025 | zone_watermark_ok(zone, order, | |
3026 | low_wmark_pages(zone), | |
3027 | *classzone_idx, 0)) | |
3028 | pgdat_needs_compaction = false; | |
1da177e4 LT |
3029 | } |
3030 | ||
b7ea3c41 MG |
3031 | /* |
3032 | * If we're getting trouble reclaiming, start doing writepage | |
3033 | * even in laptop mode. | |
3034 | */ | |
3035 | if (sc.priority < DEF_PRIORITY - 2) | |
3036 | sc.may_writepage = 1; | |
3037 | ||
1da177e4 LT |
3038 | /* |
3039 | * Now scan the zone in the dma->highmem direction, stopping | |
3040 | * at the last zone which needs scanning. | |
3041 | * | |
3042 | * We do this because the page allocator works in the opposite | |
3043 | * direction. This prevents the page allocator from allocating | |
3044 | * pages behind kswapd's direction of progress, which would | |
3045 | * cause too much scanning of the lower zones. | |
3046 | */ | |
3047 | for (i = 0; i <= end_zone; i++) { | |
3048 | struct zone *zone = pgdat->node_zones + i; | |
3049 | ||
f3fe6512 | 3050 | if (!populated_zone(zone)) |
1da177e4 LT |
3051 | continue; |
3052 | ||
6e543d57 LD |
3053 | if (sc.priority != DEF_PRIORITY && |
3054 | !zone_reclaimable(zone)) | |
1da177e4 LT |
3055 | continue; |
3056 | ||
1da177e4 | 3057 | sc.nr_scanned = 0; |
4e416953 | 3058 | |
0608f43d AM |
3059 | nr_soft_scanned = 0; |
3060 | /* | |
3061 | * Call soft limit reclaim before calling shrink_zone. | |
3062 | */ | |
3063 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
3064 | order, sc.gfp_mask, | |
3065 | &nr_soft_scanned); | |
3066 | sc.nr_reclaimed += nr_soft_reclaimed; | |
3067 | ||
32a4330d | 3068 | /* |
7c954f6d MG |
3069 | * There should be no need to raise the scanning |
3070 | * priority if enough pages are already being scanned | |
3071 | * that that high watermark would be met at 100% | |
3072 | * efficiency. | |
fe2c2a10 | 3073 | */ |
7c954f6d MG |
3074 | if (kswapd_shrink_zone(zone, end_zone, &sc, |
3075 | lru_pages, &nr_attempted)) | |
3076 | raise_priority = false; | |
1da177e4 | 3077 | } |
5515061d MG |
3078 | |
3079 | /* | |
3080 | * If the low watermark is met there is no need for processes | |
3081 | * to be throttled on pfmemalloc_wait as they should not be | |
3082 | * able to safely make forward progress. Wake them | |
3083 | */ | |
3084 | if (waitqueue_active(&pgdat->pfmemalloc_wait) && | |
3085 | pfmemalloc_watermark_ok(pgdat)) | |
3086 | wake_up(&pgdat->pfmemalloc_wait); | |
3087 | ||
1da177e4 | 3088 | /* |
b8e83b94 MG |
3089 | * Fragmentation may mean that the system cannot be rebalanced |
3090 | * for high-order allocations in all zones. If twice the | |
3091 | * allocation size has been reclaimed and the zones are still | |
3092 | * not balanced then recheck the watermarks at order-0 to | |
3093 | * prevent kswapd reclaiming excessively. Assume that a | |
3094 | * process requested a high-order can direct reclaim/compact. | |
1da177e4 | 3095 | */ |
b8e83b94 MG |
3096 | if (order && sc.nr_reclaimed >= 2UL << order) |
3097 | order = sc.order = 0; | |
8357376d | 3098 | |
b8e83b94 MG |
3099 | /* Check if kswapd should be suspending */ |
3100 | if (try_to_freeze() || kthread_should_stop()) | |
3101 | break; | |
8357376d | 3102 | |
2ab44f43 MG |
3103 | /* |
3104 | * Compact if necessary and kswapd is reclaiming at least the | |
3105 | * high watermark number of pages as requsted | |
3106 | */ | |
3107 | if (pgdat_needs_compaction && sc.nr_reclaimed > nr_attempted) | |
3108 | compact_pgdat(pgdat, order); | |
3109 | ||
73ce02e9 | 3110 | /* |
b8e83b94 MG |
3111 | * Raise priority if scanning rate is too low or there was no |
3112 | * progress in reclaiming pages | |
73ce02e9 | 3113 | */ |
b8e83b94 MG |
3114 | if (raise_priority || !sc.nr_reclaimed) |
3115 | sc.priority--; | |
9aa41348 | 3116 | } while (sc.priority >= 1 && |
b8e83b94 | 3117 | !pgdat_balanced(pgdat, order, *classzone_idx)); |
1da177e4 | 3118 | |
b8e83b94 | 3119 | out: |
0abdee2b | 3120 | /* |
5515061d | 3121 | * Return the order we were reclaiming at so prepare_kswapd_sleep() |
0abdee2b MG |
3122 | * makes a decision on the order we were last reclaiming at. However, |
3123 | * if another caller entered the allocator slow path while kswapd | |
3124 | * was awake, order will remain at the higher level | |
3125 | */ | |
dc83edd9 | 3126 | *classzone_idx = end_zone; |
0abdee2b | 3127 | return order; |
1da177e4 LT |
3128 | } |
3129 | ||
dc83edd9 | 3130 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
3131 | { |
3132 | long remaining = 0; | |
3133 | DEFINE_WAIT(wait); | |
3134 | ||
3135 | if (freezing(current) || kthread_should_stop()) | |
3136 | return; | |
3137 | ||
3138 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3139 | ||
3140 | /* Try to sleep for a short interval */ | |
5515061d | 3141 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3142 | remaining = schedule_timeout(HZ/10); |
3143 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3144 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
3145 | } | |
3146 | ||
3147 | /* | |
3148 | * After a short sleep, check if it was a premature sleep. If not, then | |
3149 | * go fully to sleep until explicitly woken up. | |
3150 | */ | |
5515061d | 3151 | if (prepare_kswapd_sleep(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
3152 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
3153 | ||
3154 | /* | |
3155 | * vmstat counters are not perfectly accurate and the estimated | |
3156 | * value for counters such as NR_FREE_PAGES can deviate from the | |
3157 | * true value by nr_online_cpus * threshold. To avoid the zone | |
3158 | * watermarks being breached while under pressure, we reduce the | |
3159 | * per-cpu vmstat threshold while kswapd is awake and restore | |
3160 | * them before going back to sleep. | |
3161 | */ | |
3162 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
1c7e7f6c | 3163 | |
62997027 MG |
3164 | /* |
3165 | * Compaction records what page blocks it recently failed to | |
3166 | * isolate pages from and skips them in the future scanning. | |
3167 | * When kswapd is going to sleep, it is reasonable to assume | |
3168 | * that pages and compaction may succeed so reset the cache. | |
3169 | */ | |
3170 | reset_isolation_suitable(pgdat); | |
3171 | ||
1c7e7f6c AK |
3172 | if (!kthread_should_stop()) |
3173 | schedule(); | |
3174 | ||
f0bc0a60 KM |
3175 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); |
3176 | } else { | |
3177 | if (remaining) | |
3178 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
3179 | else | |
3180 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
3181 | } | |
3182 | finish_wait(&pgdat->kswapd_wait, &wait); | |
3183 | } | |
3184 | ||
1da177e4 LT |
3185 | /* |
3186 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 3187 | * from the init process. |
1da177e4 LT |
3188 | * |
3189 | * This basically trickles out pages so that we have _some_ | |
3190 | * free memory available even if there is no other activity | |
3191 | * that frees anything up. This is needed for things like routing | |
3192 | * etc, where we otherwise might have all activity going on in | |
3193 | * asynchronous contexts that cannot page things out. | |
3194 | * | |
3195 | * If there are applications that are active memory-allocators | |
3196 | * (most normal use), this basically shouldn't matter. | |
3197 | */ | |
3198 | static int kswapd(void *p) | |
3199 | { | |
215ddd66 | 3200 | unsigned long order, new_order; |
d2ebd0f6 | 3201 | unsigned balanced_order; |
215ddd66 | 3202 | int classzone_idx, new_classzone_idx; |
d2ebd0f6 | 3203 | int balanced_classzone_idx; |
1da177e4 LT |
3204 | pg_data_t *pgdat = (pg_data_t*)p; |
3205 | struct task_struct *tsk = current; | |
f0bc0a60 | 3206 | |
1da177e4 LT |
3207 | struct reclaim_state reclaim_state = { |
3208 | .reclaimed_slab = 0, | |
3209 | }; | |
a70f7302 | 3210 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 3211 | |
cf40bd16 NP |
3212 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
3213 | ||
174596a0 | 3214 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 3215 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
3216 | current->reclaim_state = &reclaim_state; |
3217 | ||
3218 | /* | |
3219 | * Tell the memory management that we're a "memory allocator", | |
3220 | * and that if we need more memory we should get access to it | |
3221 | * regardless (see "__alloc_pages()"). "kswapd" should | |
3222 | * never get caught in the normal page freeing logic. | |
3223 | * | |
3224 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
3225 | * you need a small amount of memory in order to be able to | |
3226 | * page out something else, and this flag essentially protects | |
3227 | * us from recursively trying to free more memory as we're | |
3228 | * trying to free the first piece of memory in the first place). | |
3229 | */ | |
930d9152 | 3230 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 3231 | set_freezable(); |
1da177e4 | 3232 | |
215ddd66 | 3233 | order = new_order = 0; |
d2ebd0f6 | 3234 | balanced_order = 0; |
215ddd66 | 3235 | classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; |
d2ebd0f6 | 3236 | balanced_classzone_idx = classzone_idx; |
1da177e4 | 3237 | for ( ; ; ) { |
6f6313d4 | 3238 | bool ret; |
3e1d1d28 | 3239 | |
215ddd66 MG |
3240 | /* |
3241 | * If the last balance_pgdat was unsuccessful it's unlikely a | |
3242 | * new request of a similar or harder type will succeed soon | |
3243 | * so consider going to sleep on the basis we reclaimed at | |
3244 | */ | |
d2ebd0f6 AS |
3245 | if (balanced_classzone_idx >= new_classzone_idx && |
3246 | balanced_order == new_order) { | |
215ddd66 MG |
3247 | new_order = pgdat->kswapd_max_order; |
3248 | new_classzone_idx = pgdat->classzone_idx; | |
3249 | pgdat->kswapd_max_order = 0; | |
3250 | pgdat->classzone_idx = pgdat->nr_zones - 1; | |
3251 | } | |
3252 | ||
99504748 | 3253 | if (order < new_order || classzone_idx > new_classzone_idx) { |
1da177e4 LT |
3254 | /* |
3255 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 3256 | * allocation or has tigher zone constraints |
1da177e4 LT |
3257 | */ |
3258 | order = new_order; | |
99504748 | 3259 | classzone_idx = new_classzone_idx; |
1da177e4 | 3260 | } else { |
d2ebd0f6 AS |
3261 | kswapd_try_to_sleep(pgdat, balanced_order, |
3262 | balanced_classzone_idx); | |
1da177e4 | 3263 | order = pgdat->kswapd_max_order; |
99504748 | 3264 | classzone_idx = pgdat->classzone_idx; |
f0dfcde0 AS |
3265 | new_order = order; |
3266 | new_classzone_idx = classzone_idx; | |
4d40502e | 3267 | pgdat->kswapd_max_order = 0; |
215ddd66 | 3268 | pgdat->classzone_idx = pgdat->nr_zones - 1; |
1da177e4 | 3269 | } |
1da177e4 | 3270 | |
8fe23e05 DR |
3271 | ret = try_to_freeze(); |
3272 | if (kthread_should_stop()) | |
3273 | break; | |
3274 | ||
3275 | /* | |
3276 | * We can speed up thawing tasks if we don't call balance_pgdat | |
3277 | * after returning from the refrigerator | |
3278 | */ | |
33906bc5 MG |
3279 | if (!ret) { |
3280 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
d2ebd0f6 AS |
3281 | balanced_classzone_idx = classzone_idx; |
3282 | balanced_order = balance_pgdat(pgdat, order, | |
3283 | &balanced_classzone_idx); | |
33906bc5 | 3284 | } |
1da177e4 | 3285 | } |
b0a8cc58 TY |
3286 | |
3287 | current->reclaim_state = NULL; | |
1da177e4 LT |
3288 | return 0; |
3289 | } | |
3290 | ||
3291 | /* | |
3292 | * A zone is low on free memory, so wake its kswapd task to service it. | |
3293 | */ | |
99504748 | 3294 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
3295 | { |
3296 | pg_data_t *pgdat; | |
3297 | ||
f3fe6512 | 3298 | if (!populated_zone(zone)) |
1da177e4 LT |
3299 | return; |
3300 | ||
88f5acf8 | 3301 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 3302 | return; |
88f5acf8 | 3303 | pgdat = zone->zone_pgdat; |
99504748 | 3304 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 3305 | pgdat->kswapd_max_order = order; |
99504748 MG |
3306 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
3307 | } | |
8d0986e2 | 3308 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 3309 | return; |
892f795d | 3310 | if (zone_balanced(zone, order, 0, 0)) |
88f5acf8 MG |
3311 | return; |
3312 | ||
3313 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 3314 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
3315 | } |
3316 | ||
adea02a1 WF |
3317 | /* |
3318 | * The reclaimable count would be mostly accurate. | |
3319 | * The less reclaimable pages may be | |
3320 | * - mlocked pages, which will be moved to unevictable list when encountered | |
3321 | * - mapped pages, which may require several travels to be reclaimed | |
3322 | * - dirty pages, which is not "instantly" reclaimable | |
3323 | */ | |
3324 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 3325 | { |
adea02a1 WF |
3326 | int nr; |
3327 | ||
3328 | nr = global_page_state(NR_ACTIVE_FILE) + | |
3329 | global_page_state(NR_INACTIVE_FILE); | |
3330 | ||
ec8acf20 | 3331 | if (get_nr_swap_pages() > 0) |
adea02a1 WF |
3332 | nr += global_page_state(NR_ACTIVE_ANON) + |
3333 | global_page_state(NR_INACTIVE_ANON); | |
3334 | ||
3335 | return nr; | |
3336 | } | |
3337 | ||
c6f37f12 | 3338 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 3339 | /* |
7b51755c | 3340 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
3341 | * freed pages. |
3342 | * | |
3343 | * Rather than trying to age LRUs the aim is to preserve the overall | |
3344 | * LRU order by reclaiming preferentially | |
3345 | * inactive > active > active referenced > active mapped | |
1da177e4 | 3346 | */ |
7b51755c | 3347 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 3348 | { |
d6277db4 | 3349 | struct reclaim_state reclaim_state; |
d6277db4 | 3350 | struct scan_control sc = { |
7b51755c KM |
3351 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
3352 | .may_swap = 1, | |
3353 | .may_unmap = 1, | |
d6277db4 | 3354 | .may_writepage = 1, |
7b51755c KM |
3355 | .nr_to_reclaim = nr_to_reclaim, |
3356 | .hibernation_mode = 1, | |
7b51755c | 3357 | .order = 0, |
9e3b2f8c | 3358 | .priority = DEF_PRIORITY, |
1da177e4 | 3359 | }; |
a09ed5e0 YH |
3360 | struct shrink_control shrink = { |
3361 | .gfp_mask = sc.gfp_mask, | |
3362 | }; | |
3363 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); | |
7b51755c KM |
3364 | struct task_struct *p = current; |
3365 | unsigned long nr_reclaimed; | |
1da177e4 | 3366 | |
7b51755c KM |
3367 | p->flags |= PF_MEMALLOC; |
3368 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
3369 | reclaim_state.reclaimed_slab = 0; | |
3370 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 3371 | |
a09ed5e0 | 3372 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
d979677c | 3373 | |
7b51755c KM |
3374 | p->reclaim_state = NULL; |
3375 | lockdep_clear_current_reclaim_state(); | |
3376 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 3377 | |
7b51755c | 3378 | return nr_reclaimed; |
1da177e4 | 3379 | } |
c6f37f12 | 3380 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 3381 | |
1da177e4 LT |
3382 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
3383 | not required for correctness. So if the last cpu in a node goes | |
3384 | away, we get changed to run anywhere: as the first one comes back, | |
3385 | restore their cpu bindings. */ | |
fcb35a9b GKH |
3386 | static int cpu_callback(struct notifier_block *nfb, unsigned long action, |
3387 | void *hcpu) | |
1da177e4 | 3388 | { |
58c0a4a7 | 3389 | int nid; |
1da177e4 | 3390 | |
8bb78442 | 3391 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
48fb2e24 | 3392 | for_each_node_state(nid, N_MEMORY) { |
c5f59f08 | 3393 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
3394 | const struct cpumask *mask; |
3395 | ||
3396 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 3397 | |
3e597945 | 3398 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 3399 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 3400 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
3401 | } |
3402 | } | |
3403 | return NOTIFY_OK; | |
3404 | } | |
1da177e4 | 3405 | |
3218ae14 YG |
3406 | /* |
3407 | * This kswapd start function will be called by init and node-hot-add. | |
3408 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
3409 | */ | |
3410 | int kswapd_run(int nid) | |
3411 | { | |
3412 | pg_data_t *pgdat = NODE_DATA(nid); | |
3413 | int ret = 0; | |
3414 | ||
3415 | if (pgdat->kswapd) | |
3416 | return 0; | |
3417 | ||
3418 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
3419 | if (IS_ERR(pgdat->kswapd)) { | |
3420 | /* failure at boot is fatal */ | |
3421 | BUG_ON(system_state == SYSTEM_BOOTING); | |
d5dc0ad9 GS |
3422 | pr_err("Failed to start kswapd on node %d\n", nid); |
3423 | ret = PTR_ERR(pgdat->kswapd); | |
d72515b8 | 3424 | pgdat->kswapd = NULL; |
3218ae14 YG |
3425 | } |
3426 | return ret; | |
3427 | } | |
3428 | ||
8fe23e05 | 3429 | /* |
d8adde17 JL |
3430 | * Called by memory hotplug when all memory in a node is offlined. Caller must |
3431 | * hold lock_memory_hotplug(). | |
8fe23e05 DR |
3432 | */ |
3433 | void kswapd_stop(int nid) | |
3434 | { | |
3435 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
3436 | ||
d8adde17 | 3437 | if (kswapd) { |
8fe23e05 | 3438 | kthread_stop(kswapd); |
d8adde17 JL |
3439 | NODE_DATA(nid)->kswapd = NULL; |
3440 | } | |
8fe23e05 DR |
3441 | } |
3442 | ||
1da177e4 LT |
3443 | static int __init kswapd_init(void) |
3444 | { | |
3218ae14 | 3445 | int nid; |
69e05944 | 3446 | |
1da177e4 | 3447 | swap_setup(); |
48fb2e24 | 3448 | for_each_node_state(nid, N_MEMORY) |
3218ae14 | 3449 | kswapd_run(nid); |
1da177e4 LT |
3450 | hotcpu_notifier(cpu_callback, 0); |
3451 | return 0; | |
3452 | } | |
3453 | ||
3454 | module_init(kswapd_init) | |
9eeff239 CL |
3455 | |
3456 | #ifdef CONFIG_NUMA | |
3457 | /* | |
3458 | * Zone reclaim mode | |
3459 | * | |
3460 | * If non-zero call zone_reclaim when the number of free pages falls below | |
3461 | * the watermarks. | |
9eeff239 CL |
3462 | */ |
3463 | int zone_reclaim_mode __read_mostly; | |
3464 | ||
1b2ffb78 | 3465 | #define RECLAIM_OFF 0 |
7d03431c | 3466 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
3467 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
3468 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
3469 | ||
a92f7126 CL |
3470 | /* |
3471 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
3472 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
3473 | * a zone. | |
3474 | */ | |
3475 | #define ZONE_RECLAIM_PRIORITY 4 | |
3476 | ||
9614634f CL |
3477 | /* |
3478 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
3479 | * occur. | |
3480 | */ | |
3481 | int sysctl_min_unmapped_ratio = 1; | |
3482 | ||
0ff38490 CL |
3483 | /* |
3484 | * If the number of slab pages in a zone grows beyond this percentage then | |
3485 | * slab reclaim needs to occur. | |
3486 | */ | |
3487 | int sysctl_min_slab_ratio = 5; | |
3488 | ||
90afa5de MG |
3489 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
3490 | { | |
3491 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
3492 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
3493 | zone_page_state(zone, NR_ACTIVE_FILE); | |
3494 | ||
3495 | /* | |
3496 | * It's possible for there to be more file mapped pages than | |
3497 | * accounted for by the pages on the file LRU lists because | |
3498 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3499 | */ | |
3500 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3501 | } | |
3502 | ||
3503 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
3504 | static long zone_pagecache_reclaimable(struct zone *zone) | |
3505 | { | |
3506 | long nr_pagecache_reclaimable; | |
3507 | long delta = 0; | |
3508 | ||
3509 | /* | |
3510 | * If RECLAIM_SWAP is set, then all file pages are considered | |
3511 | * potentially reclaimable. Otherwise, we have to worry about | |
3512 | * pages like swapcache and zone_unmapped_file_pages() provides | |
3513 | * a better estimate | |
3514 | */ | |
3515 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
3516 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
3517 | else | |
3518 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
3519 | ||
3520 | /* If we can't clean pages, remove dirty pages from consideration */ | |
3521 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
3522 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
3523 | ||
3524 | /* Watch for any possible underflows due to delta */ | |
3525 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3526 | delta = nr_pagecache_reclaimable; | |
3527 | ||
3528 | return nr_pagecache_reclaimable - delta; | |
3529 | } | |
3530 | ||
9eeff239 CL |
3531 | /* |
3532 | * Try to free up some pages from this zone through reclaim. | |
3533 | */ | |
179e9639 | 3534 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3535 | { |
7fb2d46d | 3536 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3537 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3538 | struct task_struct *p = current; |
3539 | struct reclaim_state reclaim_state; | |
179e9639 AM |
3540 | struct scan_control sc = { |
3541 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 3542 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 3543 | .may_swap = 1, |
62b726c1 | 3544 | .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), |
21caf2fc | 3545 | .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), |
bd2f6199 | 3546 | .order = order, |
9e3b2f8c | 3547 | .priority = ZONE_RECLAIM_PRIORITY, |
179e9639 | 3548 | }; |
a09ed5e0 YH |
3549 | struct shrink_control shrink = { |
3550 | .gfp_mask = sc.gfp_mask, | |
3551 | }; | |
15748048 | 3552 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 3553 | |
9eeff239 | 3554 | cond_resched(); |
d4f7796e CL |
3555 | /* |
3556 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
3557 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
3558 | * and RECLAIM_SWAP. | |
3559 | */ | |
3560 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3561 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3562 | reclaim_state.reclaimed_slab = 0; |
3563 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3564 | |
90afa5de | 3565 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3566 | /* |
3567 | * Free memory by calling shrink zone with increasing | |
3568 | * priorities until we have enough memory freed. | |
3569 | */ | |
0ff38490 | 3570 | do { |
9e3b2f8c KK |
3571 | shrink_zone(zone, &sc); |
3572 | } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); | |
0ff38490 | 3573 | } |
c84db23c | 3574 | |
15748048 KM |
3575 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3576 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 3577 | /* |
7fb2d46d | 3578 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
3579 | * many pages were freed in this zone. So we take the current |
3580 | * number of slab pages and shake the slab until it is reduced | |
3581 | * by the same nr_pages that we used for reclaiming unmapped | |
3582 | * pages. | |
2a16e3f4 | 3583 | */ |
0ce3d744 DC |
3584 | nodes_clear(shrink.nodes_to_scan); |
3585 | node_set(zone_to_nid(zone), shrink.nodes_to_scan); | |
4dc4b3d9 KM |
3586 | for (;;) { |
3587 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
3588 | ||
3589 | /* No reclaimable slab or very low memory pressure */ | |
1495f230 | 3590 | if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages)) |
4dc4b3d9 KM |
3591 | break; |
3592 | ||
3593 | /* Freed enough memory */ | |
3594 | nr_slab_pages1 = zone_page_state(zone, | |
3595 | NR_SLAB_RECLAIMABLE); | |
3596 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
3597 | break; | |
3598 | } | |
83e33a47 CL |
3599 | |
3600 | /* | |
3601 | * Update nr_reclaimed by the number of slab pages we | |
3602 | * reclaimed from this zone. | |
3603 | */ | |
15748048 KM |
3604 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3605 | if (nr_slab_pages1 < nr_slab_pages0) | |
3606 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
3607 | } |
3608 | ||
9eeff239 | 3609 | p->reclaim_state = NULL; |
d4f7796e | 3610 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3611 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3612 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3613 | } |
179e9639 AM |
3614 | |
3615 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3616 | { | |
179e9639 | 3617 | int node_id; |
d773ed6b | 3618 | int ret; |
179e9639 AM |
3619 | |
3620 | /* | |
0ff38490 CL |
3621 | * Zone reclaim reclaims unmapped file backed pages and |
3622 | * slab pages if we are over the defined limits. | |
34aa1330 | 3623 | * |
9614634f CL |
3624 | * A small portion of unmapped file backed pages is needed for |
3625 | * file I/O otherwise pages read by file I/O will be immediately | |
3626 | * thrown out if the zone is overallocated. So we do not reclaim | |
3627 | * if less than a specified percentage of the zone is used by | |
3628 | * unmapped file backed pages. | |
179e9639 | 3629 | */ |
90afa5de MG |
3630 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3631 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3632 | return ZONE_RECLAIM_FULL; |
179e9639 | 3633 | |
6e543d57 | 3634 | if (!zone_reclaimable(zone)) |
fa5e084e | 3635 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3636 | |
179e9639 | 3637 | /* |
d773ed6b | 3638 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3639 | */ |
d773ed6b | 3640 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3641 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3642 | |
3643 | /* | |
3644 | * Only run zone reclaim on the local zone or on zones that do not | |
3645 | * have associated processors. This will favor the local processor | |
3646 | * over remote processors and spread off node memory allocations | |
3647 | * as wide as possible. | |
3648 | */ | |
89fa3024 | 3649 | node_id = zone_to_nid(zone); |
37c0708d | 3650 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3651 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
3652 | |
3653 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
3654 | return ZONE_RECLAIM_NOSCAN; |
3655 | ||
d773ed6b DR |
3656 | ret = __zone_reclaim(zone, gfp_mask, order); |
3657 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
3658 | ||
24cf7251 MG |
3659 | if (!ret) |
3660 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3661 | ||
d773ed6b | 3662 | return ret; |
179e9639 | 3663 | } |
9eeff239 | 3664 | #endif |
894bc310 | 3665 | |
894bc310 LS |
3666 | /* |
3667 | * page_evictable - test whether a page is evictable | |
3668 | * @page: the page to test | |
894bc310 LS |
3669 | * |
3670 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
39b5f29a | 3671 | * lists vs unevictable list. |
894bc310 LS |
3672 | * |
3673 | * Reasons page might not be evictable: | |
ba9ddf49 | 3674 | * (1) page's mapping marked unevictable |
b291f000 | 3675 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3676 | * |
894bc310 | 3677 | */ |
39b5f29a | 3678 | int page_evictable(struct page *page) |
894bc310 | 3679 | { |
39b5f29a | 3680 | return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); |
894bc310 | 3681 | } |
89e004ea | 3682 | |
85046579 | 3683 | #ifdef CONFIG_SHMEM |
89e004ea | 3684 | /** |
24513264 HD |
3685 | * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list |
3686 | * @pages: array of pages to check | |
3687 | * @nr_pages: number of pages to check | |
89e004ea | 3688 | * |
24513264 | 3689 | * Checks pages for evictability and moves them to the appropriate lru list. |
85046579 HD |
3690 | * |
3691 | * This function is only used for SysV IPC SHM_UNLOCK. | |
89e004ea | 3692 | */ |
24513264 | 3693 | void check_move_unevictable_pages(struct page **pages, int nr_pages) |
89e004ea | 3694 | { |
925b7673 | 3695 | struct lruvec *lruvec; |
24513264 HD |
3696 | struct zone *zone = NULL; |
3697 | int pgscanned = 0; | |
3698 | int pgrescued = 0; | |
3699 | int i; | |
89e004ea | 3700 | |
24513264 HD |
3701 | for (i = 0; i < nr_pages; i++) { |
3702 | struct page *page = pages[i]; | |
3703 | struct zone *pagezone; | |
89e004ea | 3704 | |
24513264 HD |
3705 | pgscanned++; |
3706 | pagezone = page_zone(page); | |
3707 | if (pagezone != zone) { | |
3708 | if (zone) | |
3709 | spin_unlock_irq(&zone->lru_lock); | |
3710 | zone = pagezone; | |
3711 | spin_lock_irq(&zone->lru_lock); | |
3712 | } | |
fa9add64 | 3713 | lruvec = mem_cgroup_page_lruvec(page, zone); |
89e004ea | 3714 | |
24513264 HD |
3715 | if (!PageLRU(page) || !PageUnevictable(page)) |
3716 | continue; | |
89e004ea | 3717 | |
39b5f29a | 3718 | if (page_evictable(page)) { |
24513264 HD |
3719 | enum lru_list lru = page_lru_base_type(page); |
3720 | ||
309381fe | 3721 | VM_BUG_ON_PAGE(PageActive(page), page); |
24513264 | 3722 | ClearPageUnevictable(page); |
fa9add64 HD |
3723 | del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); |
3724 | add_page_to_lru_list(page, lruvec, lru); | |
24513264 | 3725 | pgrescued++; |
89e004ea | 3726 | } |
24513264 | 3727 | } |
89e004ea | 3728 | |
24513264 HD |
3729 | if (zone) { |
3730 | __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); | |
3731 | __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); | |
3732 | spin_unlock_irq(&zone->lru_lock); | |
89e004ea | 3733 | } |
89e004ea | 3734 | } |
85046579 | 3735 | #endif /* CONFIG_SHMEM */ |
af936a16 | 3736 | |
264e56d8 | 3737 | static void warn_scan_unevictable_pages(void) |
af936a16 | 3738 | { |
264e56d8 | 3739 | printk_once(KERN_WARNING |
25bd91bd | 3740 | "%s: The scan_unevictable_pages sysctl/node-interface has been " |
264e56d8 | 3741 | "disabled for lack of a legitimate use case. If you have " |
25bd91bd KM |
3742 | "one, please send an email to linux-mm@kvack.org.\n", |
3743 | current->comm); | |
af936a16 LS |
3744 | } |
3745 | ||
3746 | /* | |
3747 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3748 | * all nodes' unevictable lists for evictable pages | |
3749 | */ | |
3750 | unsigned long scan_unevictable_pages; | |
3751 | ||
3752 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3753 | void __user *buffer, |
af936a16 LS |
3754 | size_t *length, loff_t *ppos) |
3755 | { | |
264e56d8 | 3756 | warn_scan_unevictable_pages(); |
8d65af78 | 3757 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3758 | scan_unevictable_pages = 0; |
3759 | return 0; | |
3760 | } | |
3761 | ||
e4455abb | 3762 | #ifdef CONFIG_NUMA |
af936a16 LS |
3763 | /* |
3764 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3765 | * a specified node's per zone unevictable lists for evictable pages. | |
3766 | */ | |
3767 | ||
10fbcf4c KS |
3768 | static ssize_t read_scan_unevictable_node(struct device *dev, |
3769 | struct device_attribute *attr, | |
af936a16 LS |
3770 | char *buf) |
3771 | { | |
264e56d8 | 3772 | warn_scan_unevictable_pages(); |
af936a16 LS |
3773 | return sprintf(buf, "0\n"); /* always zero; should fit... */ |
3774 | } | |
3775 | ||
10fbcf4c KS |
3776 | static ssize_t write_scan_unevictable_node(struct device *dev, |
3777 | struct device_attribute *attr, | |
af936a16 LS |
3778 | const char *buf, size_t count) |
3779 | { | |
264e56d8 | 3780 | warn_scan_unevictable_pages(); |
af936a16 LS |
3781 | return 1; |
3782 | } | |
3783 | ||
3784 | ||
10fbcf4c | 3785 | static DEVICE_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, |
af936a16 LS |
3786 | read_scan_unevictable_node, |
3787 | write_scan_unevictable_node); | |
3788 | ||
3789 | int scan_unevictable_register_node(struct node *node) | |
3790 | { | |
10fbcf4c | 3791 | return device_create_file(&node->dev, &dev_attr_scan_unevictable_pages); |
af936a16 LS |
3792 | } |
3793 | ||
3794 | void scan_unevictable_unregister_node(struct node *node) | |
3795 | { | |
10fbcf4c | 3796 | device_remove_file(&node->dev, &dev_attr_scan_unevictable_pages); |
af936a16 | 3797 | } |
e4455abb | 3798 | #endif |