Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
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> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
27 | buffer_heads_over_limit */ | |
28 | #include <linux/mm_inline.h> | |
29 | #include <linux/pagevec.h> | |
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> |
1da177e4 LT |
44 | |
45 | #include <asm/tlbflush.h> | |
46 | #include <asm/div64.h> | |
47 | ||
48 | #include <linux/swapops.h> | |
49 | ||
0f8053a5 NP |
50 | #include "internal.h" |
51 | ||
33906bc5 MG |
52 | #define CREATE_TRACE_POINTS |
53 | #include <trace/events/vmscan.h> | |
54 | ||
ee64fc93 MG |
55 | /* |
56 | * lumpy_mode determines how the inactive list is shrunk | |
57 | * LUMPY_MODE_SINGLE: Reclaim only order-0 pages | |
58 | * LUMPY_MODE_ASYNC: Do not block | |
59 | * LUMPY_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback | |
60 | * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference | |
61 | * page from the LRU and reclaim all pages within a | |
62 | * naturally aligned range | |
3e7d3449 MG |
63 | * LUMPY_MODE_COMPACTION: For high-order allocations, reclaim a number of |
64 | * order-0 pages and then compact the zone | |
ee64fc93 MG |
65 | */ |
66 | typedef unsigned __bitwise__ lumpy_mode; | |
67 | #define LUMPY_MODE_SINGLE ((__force lumpy_mode)0x01u) | |
68 | #define LUMPY_MODE_ASYNC ((__force lumpy_mode)0x02u) | |
69 | #define LUMPY_MODE_SYNC ((__force lumpy_mode)0x04u) | |
70 | #define LUMPY_MODE_CONTIGRECLAIM ((__force lumpy_mode)0x08u) | |
3e7d3449 | 71 | #define LUMPY_MODE_COMPACTION ((__force lumpy_mode)0x10u) |
7d3579e8 | 72 | |
1da177e4 | 73 | struct scan_control { |
1da177e4 LT |
74 | /* Incremented by the number of inactive pages that were scanned */ |
75 | unsigned long nr_scanned; | |
76 | ||
a79311c1 RR |
77 | /* Number of pages freed so far during a call to shrink_zones() */ |
78 | unsigned long nr_reclaimed; | |
79 | ||
22fba335 KM |
80 | /* How many pages shrink_list() should reclaim */ |
81 | unsigned long nr_to_reclaim; | |
82 | ||
7b51755c KM |
83 | unsigned long hibernation_mode; |
84 | ||
1da177e4 | 85 | /* This context's GFP mask */ |
6daa0e28 | 86 | gfp_t gfp_mask; |
1da177e4 LT |
87 | |
88 | int may_writepage; | |
89 | ||
a6dc60f8 JW |
90 | /* Can mapped pages be reclaimed? */ |
91 | int may_unmap; | |
f1fd1067 | 92 | |
2e2e4259 KM |
93 | /* Can pages be swapped as part of reclaim? */ |
94 | int may_swap; | |
95 | ||
d6277db4 | 96 | int swappiness; |
408d8544 | 97 | |
5ad333eb | 98 | int order; |
66e1707b | 99 | |
5f53e762 | 100 | /* |
415b54e3 NK |
101 | * Intend to reclaim enough continuous memory rather than reclaim |
102 | * enough amount of memory. i.e, mode for high order allocation. | |
5f53e762 | 103 | */ |
ee64fc93 | 104 | lumpy_mode lumpy_reclaim_mode; |
5f53e762 | 105 | |
66e1707b BS |
106 | /* Which cgroup do we reclaim from */ |
107 | struct mem_cgroup *mem_cgroup; | |
108 | ||
327c0e96 KH |
109 | /* |
110 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
111 | * are scanned. | |
112 | */ | |
113 | nodemask_t *nodemask; | |
1da177e4 LT |
114 | }; |
115 | ||
1da177e4 LT |
116 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
117 | ||
118 | #ifdef ARCH_HAS_PREFETCH | |
119 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
120 | do { \ | |
121 | if ((_page)->lru.prev != _base) { \ | |
122 | struct page *prev; \ | |
123 | \ | |
124 | prev = lru_to_page(&(_page->lru)); \ | |
125 | prefetch(&prev->_field); \ | |
126 | } \ | |
127 | } while (0) | |
128 | #else | |
129 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
130 | #endif | |
131 | ||
132 | #ifdef ARCH_HAS_PREFETCHW | |
133 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
134 | do { \ | |
135 | if ((_page)->lru.prev != _base) { \ | |
136 | struct page *prev; \ | |
137 | \ | |
138 | prev = lru_to_page(&(_page->lru)); \ | |
139 | prefetchw(&prev->_field); \ | |
140 | } \ | |
141 | } while (0) | |
142 | #else | |
143 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
144 | #endif | |
145 | ||
146 | /* | |
147 | * From 0 .. 100. Higher means more swappy. | |
148 | */ | |
149 | int vm_swappiness = 60; | |
bd1e22b8 | 150 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
151 | |
152 | static LIST_HEAD(shrinker_list); | |
153 | static DECLARE_RWSEM(shrinker_rwsem); | |
154 | ||
00f0b825 | 155 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 156 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 157 | #else |
e72e2bd6 | 158 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
159 | #endif |
160 | ||
6e901571 KM |
161 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
162 | struct scan_control *sc) | |
163 | { | |
e72e2bd6 | 164 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
165 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
166 | ||
6e901571 KM |
167 | return &zone->reclaim_stat; |
168 | } | |
169 | ||
0b217676 VL |
170 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
171 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 172 | { |
e72e2bd6 | 173 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
174 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
175 | ||
c9f299d9 KM |
176 | return zone_page_state(zone, NR_LRU_BASE + lru); |
177 | } | |
178 | ||
179 | ||
1da177e4 LT |
180 | /* |
181 | * Add a shrinker callback to be called from the vm | |
182 | */ | |
8e1f936b | 183 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 184 | { |
8e1f936b RR |
185 | shrinker->nr = 0; |
186 | down_write(&shrinker_rwsem); | |
187 | list_add_tail(&shrinker->list, &shrinker_list); | |
188 | up_write(&shrinker_rwsem); | |
1da177e4 | 189 | } |
8e1f936b | 190 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
191 | |
192 | /* | |
193 | * Remove one | |
194 | */ | |
8e1f936b | 195 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
196 | { |
197 | down_write(&shrinker_rwsem); | |
198 | list_del(&shrinker->list); | |
199 | up_write(&shrinker_rwsem); | |
1da177e4 | 200 | } |
8e1f936b | 201 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
202 | |
203 | #define SHRINK_BATCH 128 | |
204 | /* | |
205 | * Call the shrink functions to age shrinkable caches | |
206 | * | |
207 | * Here we assume it costs one seek to replace a lru page and that it also | |
208 | * takes a seek to recreate a cache object. With this in mind we age equal | |
209 | * percentages of the lru and ageable caches. This should balance the seeks | |
210 | * generated by these structures. | |
211 | * | |
183ff22b | 212 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
213 | * slab to avoid swapping. |
214 | * | |
215 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
216 | * | |
217 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
218 | * are eligible for the caller's allocation attempt. It is used for balancing | |
219 | * slab reclaim versus page reclaim. | |
b15e0905 | 220 | * |
221 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 222 | */ |
69e05944 AM |
223 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
224 | unsigned long lru_pages) | |
1da177e4 LT |
225 | { |
226 | struct shrinker *shrinker; | |
69e05944 | 227 | unsigned long ret = 0; |
1da177e4 LT |
228 | |
229 | if (scanned == 0) | |
230 | scanned = SWAP_CLUSTER_MAX; | |
231 | ||
232 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 233 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
234 | |
235 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
236 | unsigned long long delta; | |
237 | unsigned long total_scan; | |
7f8275d0 | 238 | unsigned long max_pass; |
1da177e4 | 239 | |
7f8275d0 | 240 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 241 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 242 | delta *= max_pass; |
1da177e4 LT |
243 | do_div(delta, lru_pages + 1); |
244 | shrinker->nr += delta; | |
ea164d73 | 245 | if (shrinker->nr < 0) { |
88c3bd70 DR |
246 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
247 | "delete nr=%ld\n", | |
248 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
249 | shrinker->nr = max_pass; |
250 | } | |
251 | ||
252 | /* | |
253 | * Avoid risking looping forever due to too large nr value: | |
254 | * never try to free more than twice the estimate number of | |
255 | * freeable entries. | |
256 | */ | |
257 | if (shrinker->nr > max_pass * 2) | |
258 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
259 | |
260 | total_scan = shrinker->nr; | |
261 | shrinker->nr = 0; | |
262 | ||
263 | while (total_scan >= SHRINK_BATCH) { | |
264 | long this_scan = SHRINK_BATCH; | |
265 | int shrink_ret; | |
b15e0905 | 266 | int nr_before; |
1da177e4 | 267 | |
7f8275d0 DC |
268 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
269 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
270 | gfp_mask); | |
1da177e4 LT |
271 | if (shrink_ret == -1) |
272 | break; | |
b15e0905 | 273 | if (shrink_ret < nr_before) |
274 | ret += nr_before - shrink_ret; | |
f8891e5e | 275 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
276 | total_scan -= this_scan; |
277 | ||
278 | cond_resched(); | |
279 | } | |
280 | ||
281 | shrinker->nr += total_scan; | |
282 | } | |
283 | up_read(&shrinker_rwsem); | |
b15e0905 | 284 | return ret; |
1da177e4 LT |
285 | } |
286 | ||
7d3579e8 KM |
287 | static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc, |
288 | bool sync) | |
289 | { | |
ee64fc93 | 290 | lumpy_mode syncmode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC; |
7d3579e8 KM |
291 | |
292 | /* | |
3e7d3449 MG |
293 | * Initially assume we are entering either lumpy reclaim or |
294 | * reclaim/compaction.Depending on the order, we will either set the | |
295 | * sync mode or just reclaim order-0 pages later. | |
7d3579e8 | 296 | */ |
3e7d3449 MG |
297 | if (COMPACTION_BUILD) |
298 | sc->lumpy_reclaim_mode = LUMPY_MODE_COMPACTION; | |
299 | else | |
300 | sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM; | |
7d3579e8 KM |
301 | |
302 | /* | |
3e7d3449 MG |
303 | * Avoid using lumpy reclaim or reclaim/compaction if possible by |
304 | * restricting when its set to either costly allocations or when | |
305 | * under memory pressure | |
7d3579e8 KM |
306 | */ |
307 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
ee64fc93 | 308 | sc->lumpy_reclaim_mode |= syncmode; |
7d3579e8 | 309 | else if (sc->order && priority < DEF_PRIORITY - 2) |
ee64fc93 | 310 | sc->lumpy_reclaim_mode |= syncmode; |
7d3579e8 | 311 | else |
ee64fc93 | 312 | sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC; |
7d3579e8 KM |
313 | } |
314 | ||
315 | static void disable_lumpy_reclaim_mode(struct scan_control *sc) | |
316 | { | |
ee64fc93 | 317 | sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC; |
7d3579e8 KM |
318 | } |
319 | ||
1da177e4 LT |
320 | static inline int is_page_cache_freeable(struct page *page) |
321 | { | |
ceddc3a5 JW |
322 | /* |
323 | * A freeable page cache page is referenced only by the caller | |
324 | * that isolated the page, the page cache radix tree and | |
325 | * optional buffer heads at page->private. | |
326 | */ | |
edcf4748 | 327 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
328 | } |
329 | ||
7d3579e8 KM |
330 | static int may_write_to_queue(struct backing_dev_info *bdi, |
331 | struct scan_control *sc) | |
1da177e4 | 332 | { |
930d9152 | 333 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
334 | return 1; |
335 | if (!bdi_write_congested(bdi)) | |
336 | return 1; | |
337 | if (bdi == current->backing_dev_info) | |
338 | return 1; | |
7d3579e8 KM |
339 | |
340 | /* lumpy reclaim for hugepage often need a lot of write */ | |
341 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
342 | return 1; | |
1da177e4 LT |
343 | return 0; |
344 | } | |
345 | ||
346 | /* | |
347 | * We detected a synchronous write error writing a page out. Probably | |
348 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
349 | * fsync(), msync() or close(). | |
350 | * | |
351 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
352 | * prevents it from being freed up. But we have a ref on the page and once | |
353 | * that page is locked, the mapping is pinned. | |
354 | * | |
355 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
356 | * __GFP_FS. | |
357 | */ | |
358 | static void handle_write_error(struct address_space *mapping, | |
359 | struct page *page, int error) | |
360 | { | |
a6aa62a0 | 361 | lock_page_nosync(page); |
3e9f45bd GC |
362 | if (page_mapping(page) == mapping) |
363 | mapping_set_error(mapping, error); | |
1da177e4 LT |
364 | unlock_page(page); |
365 | } | |
366 | ||
04e62a29 CL |
367 | /* possible outcome of pageout() */ |
368 | typedef enum { | |
369 | /* failed to write page out, page is locked */ | |
370 | PAGE_KEEP, | |
371 | /* move page to the active list, page is locked */ | |
372 | PAGE_ACTIVATE, | |
373 | /* page has been sent to the disk successfully, page is unlocked */ | |
374 | PAGE_SUCCESS, | |
375 | /* page is clean and locked */ | |
376 | PAGE_CLEAN, | |
377 | } pageout_t; | |
378 | ||
1da177e4 | 379 | /* |
1742f19f AM |
380 | * pageout is called by shrink_page_list() for each dirty page. |
381 | * Calls ->writepage(). | |
1da177e4 | 382 | */ |
c661b078 | 383 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 384 | struct scan_control *sc) |
1da177e4 LT |
385 | { |
386 | /* | |
387 | * If the page is dirty, only perform writeback if that write | |
388 | * will be non-blocking. To prevent this allocation from being | |
389 | * stalled by pagecache activity. But note that there may be | |
390 | * stalls if we need to run get_block(). We could test | |
391 | * PagePrivate for that. | |
392 | * | |
6aceb53b | 393 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
394 | * this page's queue, we can perform writeback even if that |
395 | * will block. | |
396 | * | |
397 | * If the page is swapcache, write it back even if that would | |
398 | * block, for some throttling. This happens by accident, because | |
399 | * swap_backing_dev_info is bust: it doesn't reflect the | |
400 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
401 | */ |
402 | if (!is_page_cache_freeable(page)) | |
403 | return PAGE_KEEP; | |
404 | if (!mapping) { | |
405 | /* | |
406 | * Some data journaling orphaned pages can have | |
407 | * page->mapping == NULL while being dirty with clean buffers. | |
408 | */ | |
266cf658 | 409 | if (page_has_private(page)) { |
1da177e4 LT |
410 | if (try_to_free_buffers(page)) { |
411 | ClearPageDirty(page); | |
d40cee24 | 412 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
413 | return PAGE_CLEAN; |
414 | } | |
415 | } | |
416 | return PAGE_KEEP; | |
417 | } | |
418 | if (mapping->a_ops->writepage == NULL) | |
419 | return PAGE_ACTIVATE; | |
0e093d99 | 420 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
421 | return PAGE_KEEP; |
422 | ||
423 | if (clear_page_dirty_for_io(page)) { | |
424 | int res; | |
425 | struct writeback_control wbc = { | |
426 | .sync_mode = WB_SYNC_NONE, | |
427 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
428 | .range_start = 0, |
429 | .range_end = LLONG_MAX, | |
1da177e4 LT |
430 | .for_reclaim = 1, |
431 | }; | |
432 | ||
433 | SetPageReclaim(page); | |
434 | res = mapping->a_ops->writepage(page, &wbc); | |
435 | if (res < 0) | |
436 | handle_write_error(mapping, page, res); | |
994fc28c | 437 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
438 | ClearPageReclaim(page); |
439 | return PAGE_ACTIVATE; | |
440 | } | |
c661b078 AW |
441 | |
442 | /* | |
443 | * Wait on writeback if requested to. This happens when | |
444 | * direct reclaiming a large contiguous area and the | |
445 | * first attempt to free a range of pages fails. | |
446 | */ | |
7d3579e8 | 447 | if (PageWriteback(page) && |
ee64fc93 | 448 | (sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC)) |
c661b078 AW |
449 | wait_on_page_writeback(page); |
450 | ||
1da177e4 LT |
451 | if (!PageWriteback(page)) { |
452 | /* synchronous write or broken a_ops? */ | |
453 | ClearPageReclaim(page); | |
454 | } | |
755f0225 | 455 | trace_mm_vmscan_writepage(page, |
7d3579e8 | 456 | trace_reclaim_flags(page, sc->lumpy_reclaim_mode)); |
e129b5c2 | 457 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
458 | return PAGE_SUCCESS; |
459 | } | |
460 | ||
461 | return PAGE_CLEAN; | |
462 | } | |
463 | ||
a649fd92 | 464 | /* |
e286781d NP |
465 | * Same as remove_mapping, but if the page is removed from the mapping, it |
466 | * gets returned with a refcount of 0. | |
a649fd92 | 467 | */ |
e286781d | 468 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 469 | { |
28e4d965 NP |
470 | BUG_ON(!PageLocked(page)); |
471 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 472 | |
19fd6231 | 473 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 474 | /* |
0fd0e6b0 NP |
475 | * The non racy check for a busy page. |
476 | * | |
477 | * Must be careful with the order of the tests. When someone has | |
478 | * a ref to the page, it may be possible that they dirty it then | |
479 | * drop the reference. So if PageDirty is tested before page_count | |
480 | * here, then the following race may occur: | |
481 | * | |
482 | * get_user_pages(&page); | |
483 | * [user mapping goes away] | |
484 | * write_to(page); | |
485 | * !PageDirty(page) [good] | |
486 | * SetPageDirty(page); | |
487 | * put_page(page); | |
488 | * !page_count(page) [good, discard it] | |
489 | * | |
490 | * [oops, our write_to data is lost] | |
491 | * | |
492 | * Reversing the order of the tests ensures such a situation cannot | |
493 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
494 | * load is not satisfied before that of page->_count. | |
495 | * | |
496 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
497 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 498 | */ |
e286781d | 499 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 500 | goto cannot_free; |
e286781d NP |
501 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
502 | if (unlikely(PageDirty(page))) { | |
503 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 504 | goto cannot_free; |
e286781d | 505 | } |
49d2e9cc CL |
506 | |
507 | if (PageSwapCache(page)) { | |
508 | swp_entry_t swap = { .val = page_private(page) }; | |
509 | __delete_from_swap_cache(page); | |
19fd6231 | 510 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 511 | swapcache_free(swap, page); |
e286781d | 512 | } else { |
6072d13c LT |
513 | void (*freepage)(struct page *); |
514 | ||
515 | freepage = mapping->a_ops->freepage; | |
516 | ||
e286781d | 517 | __remove_from_page_cache(page); |
19fd6231 | 518 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 519 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
520 | |
521 | if (freepage != NULL) | |
522 | freepage(page); | |
49d2e9cc CL |
523 | } |
524 | ||
49d2e9cc CL |
525 | return 1; |
526 | ||
527 | cannot_free: | |
19fd6231 | 528 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
529 | return 0; |
530 | } | |
531 | ||
e286781d NP |
532 | /* |
533 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
534 | * someone else has a ref on the page, abort and return 0. If it was | |
535 | * successfully detached, return 1. Assumes the caller has a single ref on | |
536 | * this page. | |
537 | */ | |
538 | int remove_mapping(struct address_space *mapping, struct page *page) | |
539 | { | |
540 | if (__remove_mapping(mapping, page)) { | |
541 | /* | |
542 | * Unfreezing the refcount with 1 rather than 2 effectively | |
543 | * drops the pagecache ref for us without requiring another | |
544 | * atomic operation. | |
545 | */ | |
546 | page_unfreeze_refs(page, 1); | |
547 | return 1; | |
548 | } | |
549 | return 0; | |
550 | } | |
551 | ||
894bc310 LS |
552 | /** |
553 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
554 | * @page: page to be put back to appropriate lru list | |
555 | * | |
556 | * Add previously isolated @page to appropriate LRU list. | |
557 | * Page may still be unevictable for other reasons. | |
558 | * | |
559 | * lru_lock must not be held, interrupts must be enabled. | |
560 | */ | |
894bc310 LS |
561 | void putback_lru_page(struct page *page) |
562 | { | |
563 | int lru; | |
564 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 565 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
566 | |
567 | VM_BUG_ON(PageLRU(page)); | |
568 | ||
569 | redo: | |
570 | ClearPageUnevictable(page); | |
571 | ||
572 | if (page_evictable(page, NULL)) { | |
573 | /* | |
574 | * For evictable pages, we can use the cache. | |
575 | * In event of a race, worst case is we end up with an | |
576 | * unevictable page on [in]active list. | |
577 | * We know how to handle that. | |
578 | */ | |
401a8e1c | 579 | lru = active + page_lru_base_type(page); |
894bc310 LS |
580 | lru_cache_add_lru(page, lru); |
581 | } else { | |
582 | /* | |
583 | * Put unevictable pages directly on zone's unevictable | |
584 | * list. | |
585 | */ | |
586 | lru = LRU_UNEVICTABLE; | |
587 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
588 | /* |
589 | * When racing with an mlock clearing (page is | |
590 | * unlocked), make sure that if the other thread does | |
591 | * not observe our setting of PG_lru and fails | |
592 | * isolation, we see PG_mlocked cleared below and move | |
593 | * the page back to the evictable list. | |
594 | * | |
595 | * The other side is TestClearPageMlocked(). | |
596 | */ | |
597 | smp_mb(); | |
894bc310 | 598 | } |
894bc310 LS |
599 | |
600 | /* | |
601 | * page's status can change while we move it among lru. If an evictable | |
602 | * page is on unevictable list, it never be freed. To avoid that, | |
603 | * check after we added it to the list, again. | |
604 | */ | |
605 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
606 | if (!isolate_lru_page(page)) { | |
607 | put_page(page); | |
608 | goto redo; | |
609 | } | |
610 | /* This means someone else dropped this page from LRU | |
611 | * So, it will be freed or putback to LRU again. There is | |
612 | * nothing to do here. | |
613 | */ | |
614 | } | |
615 | ||
bbfd28ee LS |
616 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
617 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
618 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
619 | count_vm_event(UNEVICTABLE_PGCULLED); | |
620 | ||
894bc310 LS |
621 | put_page(page); /* drop ref from isolate */ |
622 | } | |
623 | ||
dfc8d636 JW |
624 | enum page_references { |
625 | PAGEREF_RECLAIM, | |
626 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 627 | PAGEREF_KEEP, |
dfc8d636 JW |
628 | PAGEREF_ACTIVATE, |
629 | }; | |
630 | ||
631 | static enum page_references page_check_references(struct page *page, | |
632 | struct scan_control *sc) | |
633 | { | |
64574746 | 634 | int referenced_ptes, referenced_page; |
dfc8d636 | 635 | unsigned long vm_flags; |
dfc8d636 | 636 | |
64574746 JW |
637 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
638 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
639 | |
640 | /* Lumpy reclaim - ignore references */ | |
ee64fc93 | 641 | if (sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM) |
dfc8d636 JW |
642 | return PAGEREF_RECLAIM; |
643 | ||
644 | /* | |
645 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
646 | * move the page to the unevictable list. | |
647 | */ | |
648 | if (vm_flags & VM_LOCKED) | |
649 | return PAGEREF_RECLAIM; | |
650 | ||
64574746 JW |
651 | if (referenced_ptes) { |
652 | if (PageAnon(page)) | |
653 | return PAGEREF_ACTIVATE; | |
654 | /* | |
655 | * All mapped pages start out with page table | |
656 | * references from the instantiating fault, so we need | |
657 | * to look twice if a mapped file page is used more | |
658 | * than once. | |
659 | * | |
660 | * Mark it and spare it for another trip around the | |
661 | * inactive list. Another page table reference will | |
662 | * lead to its activation. | |
663 | * | |
664 | * Note: the mark is set for activated pages as well | |
665 | * so that recently deactivated but used pages are | |
666 | * quickly recovered. | |
667 | */ | |
668 | SetPageReferenced(page); | |
669 | ||
670 | if (referenced_page) | |
671 | return PAGEREF_ACTIVATE; | |
672 | ||
673 | return PAGEREF_KEEP; | |
674 | } | |
dfc8d636 JW |
675 | |
676 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 677 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
678 | return PAGEREF_RECLAIM_CLEAN; |
679 | ||
680 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
681 | } |
682 | ||
abe4c3b5 MG |
683 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
684 | { | |
685 | struct pagevec freed_pvec; | |
686 | struct page *page, *tmp; | |
687 | ||
688 | pagevec_init(&freed_pvec, 1); | |
689 | ||
690 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
691 | list_del(&page->lru); | |
692 | if (!pagevec_add(&freed_pvec, page)) { | |
693 | __pagevec_free(&freed_pvec); | |
694 | pagevec_reinit(&freed_pvec); | |
695 | } | |
696 | } | |
697 | ||
698 | pagevec_free(&freed_pvec); | |
699 | } | |
700 | ||
1da177e4 | 701 | /* |
1742f19f | 702 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 703 | */ |
1742f19f | 704 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 705 | struct zone *zone, |
7d3579e8 | 706 | struct scan_control *sc) |
1da177e4 LT |
707 | { |
708 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 709 | LIST_HEAD(free_pages); |
1da177e4 | 710 | int pgactivate = 0; |
0e093d99 MG |
711 | unsigned long nr_dirty = 0; |
712 | unsigned long nr_congested = 0; | |
05ff5137 | 713 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
714 | |
715 | cond_resched(); | |
716 | ||
1da177e4 | 717 | while (!list_empty(page_list)) { |
dfc8d636 | 718 | enum page_references references; |
1da177e4 LT |
719 | struct address_space *mapping; |
720 | struct page *page; | |
721 | int may_enter_fs; | |
1da177e4 LT |
722 | |
723 | cond_resched(); | |
724 | ||
725 | page = lru_to_page(page_list); | |
726 | list_del(&page->lru); | |
727 | ||
529ae9aa | 728 | if (!trylock_page(page)) |
1da177e4 LT |
729 | goto keep; |
730 | ||
725d704e | 731 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 732 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
733 | |
734 | sc->nr_scanned++; | |
80e43426 | 735 | |
b291f000 NP |
736 | if (unlikely(!page_evictable(page, NULL))) |
737 | goto cull_mlocked; | |
894bc310 | 738 | |
a6dc60f8 | 739 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
740 | goto keep_locked; |
741 | ||
1da177e4 LT |
742 | /* Double the slab pressure for mapped and swapcache pages */ |
743 | if (page_mapped(page) || PageSwapCache(page)) | |
744 | sc->nr_scanned++; | |
745 | ||
c661b078 AW |
746 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
747 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
748 | ||
749 | if (PageWriteback(page)) { | |
750 | /* | |
751 | * Synchronous reclaim is performed in two passes, | |
752 | * first an asynchronous pass over the list to | |
753 | * start parallel writeback, and a second synchronous | |
754 | * pass to wait for the IO to complete. Wait here | |
755 | * for any page for which writeback has already | |
756 | * started. | |
757 | */ | |
ee64fc93 | 758 | if ((sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC) && |
7d3579e8 | 759 | may_enter_fs) |
c661b078 | 760 | wait_on_page_writeback(page); |
7d3579e8 KM |
761 | else { |
762 | unlock_page(page); | |
763 | goto keep_lumpy; | |
764 | } | |
c661b078 | 765 | } |
1da177e4 | 766 | |
dfc8d636 JW |
767 | references = page_check_references(page, sc); |
768 | switch (references) { | |
769 | case PAGEREF_ACTIVATE: | |
1da177e4 | 770 | goto activate_locked; |
64574746 JW |
771 | case PAGEREF_KEEP: |
772 | goto keep_locked; | |
dfc8d636 JW |
773 | case PAGEREF_RECLAIM: |
774 | case PAGEREF_RECLAIM_CLEAN: | |
775 | ; /* try to reclaim the page below */ | |
776 | } | |
1da177e4 | 777 | |
1da177e4 LT |
778 | /* |
779 | * Anonymous process memory has backing store? | |
780 | * Try to allocate it some swap space here. | |
781 | */ | |
b291f000 | 782 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
783 | if (!(sc->gfp_mask & __GFP_IO)) |
784 | goto keep_locked; | |
ac47b003 | 785 | if (!add_to_swap(page)) |
1da177e4 | 786 | goto activate_locked; |
63eb6b93 | 787 | may_enter_fs = 1; |
b291f000 | 788 | } |
1da177e4 LT |
789 | |
790 | mapping = page_mapping(page); | |
1da177e4 LT |
791 | |
792 | /* | |
793 | * The page is mapped into the page tables of one or more | |
794 | * processes. Try to unmap it here. | |
795 | */ | |
796 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 797 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
798 | case SWAP_FAIL: |
799 | goto activate_locked; | |
800 | case SWAP_AGAIN: | |
801 | goto keep_locked; | |
b291f000 NP |
802 | case SWAP_MLOCK: |
803 | goto cull_mlocked; | |
1da177e4 LT |
804 | case SWAP_SUCCESS: |
805 | ; /* try to free the page below */ | |
806 | } | |
807 | } | |
808 | ||
809 | if (PageDirty(page)) { | |
0e093d99 MG |
810 | nr_dirty++; |
811 | ||
dfc8d636 | 812 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 813 | goto keep_locked; |
4dd4b920 | 814 | if (!may_enter_fs) |
1da177e4 | 815 | goto keep_locked; |
52a8363e | 816 | if (!sc->may_writepage) |
1da177e4 LT |
817 | goto keep_locked; |
818 | ||
819 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 820 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 821 | case PAGE_KEEP: |
0e093d99 | 822 | nr_congested++; |
1da177e4 LT |
823 | goto keep_locked; |
824 | case PAGE_ACTIVATE: | |
825 | goto activate_locked; | |
826 | case PAGE_SUCCESS: | |
7d3579e8 KM |
827 | if (PageWriteback(page)) |
828 | goto keep_lumpy; | |
829 | if (PageDirty(page)) | |
1da177e4 | 830 | goto keep; |
7d3579e8 | 831 | |
1da177e4 LT |
832 | /* |
833 | * A synchronous write - probably a ramdisk. Go | |
834 | * ahead and try to reclaim the page. | |
835 | */ | |
529ae9aa | 836 | if (!trylock_page(page)) |
1da177e4 LT |
837 | goto keep; |
838 | if (PageDirty(page) || PageWriteback(page)) | |
839 | goto keep_locked; | |
840 | mapping = page_mapping(page); | |
841 | case PAGE_CLEAN: | |
842 | ; /* try to free the page below */ | |
843 | } | |
844 | } | |
845 | ||
846 | /* | |
847 | * If the page has buffers, try to free the buffer mappings | |
848 | * associated with this page. If we succeed we try to free | |
849 | * the page as well. | |
850 | * | |
851 | * We do this even if the page is PageDirty(). | |
852 | * try_to_release_page() does not perform I/O, but it is | |
853 | * possible for a page to have PageDirty set, but it is actually | |
854 | * clean (all its buffers are clean). This happens if the | |
855 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 856 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
857 | * try_to_release_page() will discover that cleanness and will |
858 | * drop the buffers and mark the page clean - it can be freed. | |
859 | * | |
860 | * Rarely, pages can have buffers and no ->mapping. These are | |
861 | * the pages which were not successfully invalidated in | |
862 | * truncate_complete_page(). We try to drop those buffers here | |
863 | * and if that worked, and the page is no longer mapped into | |
864 | * process address space (page_count == 1) it can be freed. | |
865 | * Otherwise, leave the page on the LRU so it is swappable. | |
866 | */ | |
266cf658 | 867 | if (page_has_private(page)) { |
1da177e4 LT |
868 | if (!try_to_release_page(page, sc->gfp_mask)) |
869 | goto activate_locked; | |
e286781d NP |
870 | if (!mapping && page_count(page) == 1) { |
871 | unlock_page(page); | |
872 | if (put_page_testzero(page)) | |
873 | goto free_it; | |
874 | else { | |
875 | /* | |
876 | * rare race with speculative reference. | |
877 | * the speculative reference will free | |
878 | * this page shortly, so we may | |
879 | * increment nr_reclaimed here (and | |
880 | * leave it off the LRU). | |
881 | */ | |
882 | nr_reclaimed++; | |
883 | continue; | |
884 | } | |
885 | } | |
1da177e4 LT |
886 | } |
887 | ||
e286781d | 888 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 889 | goto keep_locked; |
1da177e4 | 890 | |
a978d6f5 NP |
891 | /* |
892 | * At this point, we have no other references and there is | |
893 | * no way to pick any more up (removed from LRU, removed | |
894 | * from pagecache). Can use non-atomic bitops now (and | |
895 | * we obviously don't have to worry about waking up a process | |
896 | * waiting on the page lock, because there are no references. | |
897 | */ | |
898 | __clear_page_locked(page); | |
e286781d | 899 | free_it: |
05ff5137 | 900 | nr_reclaimed++; |
abe4c3b5 MG |
901 | |
902 | /* | |
903 | * Is there need to periodically free_page_list? It would | |
904 | * appear not as the counts should be low | |
905 | */ | |
906 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
907 | continue; |
908 | ||
b291f000 | 909 | cull_mlocked: |
63d6c5ad HD |
910 | if (PageSwapCache(page)) |
911 | try_to_free_swap(page); | |
b291f000 NP |
912 | unlock_page(page); |
913 | putback_lru_page(page); | |
7d3579e8 | 914 | disable_lumpy_reclaim_mode(sc); |
b291f000 NP |
915 | continue; |
916 | ||
1da177e4 | 917 | activate_locked: |
68a22394 RR |
918 | /* Not a candidate for swapping, so reclaim swap space. */ |
919 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 920 | try_to_free_swap(page); |
894bc310 | 921 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
922 | SetPageActive(page); |
923 | pgactivate++; | |
924 | keep_locked: | |
925 | unlock_page(page); | |
926 | keep: | |
7d3579e8 KM |
927 | disable_lumpy_reclaim_mode(sc); |
928 | keep_lumpy: | |
1da177e4 | 929 | list_add(&page->lru, &ret_pages); |
b291f000 | 930 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 931 | } |
abe4c3b5 | 932 | |
0e093d99 MG |
933 | /* |
934 | * Tag a zone as congested if all the dirty pages encountered were | |
935 | * backed by a congested BDI. In this case, reclaimers should just | |
936 | * back off and wait for congestion to clear because further reclaim | |
937 | * will encounter the same problem | |
938 | */ | |
1dce071e | 939 | if (nr_dirty == nr_congested && nr_dirty != 0) |
0e093d99 MG |
940 | zone_set_flag(zone, ZONE_CONGESTED); |
941 | ||
abe4c3b5 MG |
942 | free_page_list(&free_pages); |
943 | ||
1da177e4 | 944 | list_splice(&ret_pages, page_list); |
f8891e5e | 945 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 946 | return nr_reclaimed; |
1da177e4 LT |
947 | } |
948 | ||
5ad333eb AW |
949 | /* |
950 | * Attempt to remove the specified page from its LRU. Only take this page | |
951 | * if it is of the appropriate PageActive status. Pages which are being | |
952 | * freed elsewhere are also ignored. | |
953 | * | |
954 | * page: page to consider | |
955 | * mode: one of the LRU isolation modes defined above | |
956 | * | |
957 | * returns 0 on success, -ve errno on failure. | |
958 | */ | |
4f98a2fe | 959 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
960 | { |
961 | int ret = -EINVAL; | |
962 | ||
963 | /* Only take pages on the LRU. */ | |
964 | if (!PageLRU(page)) | |
965 | return ret; | |
966 | ||
967 | /* | |
968 | * When checking the active state, we need to be sure we are | |
969 | * dealing with comparible boolean values. Take the logical not | |
970 | * of each. | |
971 | */ | |
972 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
973 | return ret; | |
974 | ||
6c0b1351 | 975 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
976 | return ret; |
977 | ||
894bc310 LS |
978 | /* |
979 | * When this function is being called for lumpy reclaim, we | |
980 | * initially look into all LRU pages, active, inactive and | |
981 | * unevictable; only give shrink_page_list evictable pages. | |
982 | */ | |
983 | if (PageUnevictable(page)) | |
984 | return ret; | |
985 | ||
5ad333eb | 986 | ret = -EBUSY; |
08e552c6 | 987 | |
5ad333eb AW |
988 | if (likely(get_page_unless_zero(page))) { |
989 | /* | |
990 | * Be careful not to clear PageLRU until after we're | |
991 | * sure the page is not being freed elsewhere -- the | |
992 | * page release code relies on it. | |
993 | */ | |
994 | ClearPageLRU(page); | |
995 | ret = 0; | |
996 | } | |
997 | ||
998 | return ret; | |
999 | } | |
1000 | ||
1da177e4 LT |
1001 | /* |
1002 | * zone->lru_lock is heavily contended. Some of the functions that | |
1003 | * shrink the lists perform better by taking out a batch of pages | |
1004 | * and working on them outside the LRU lock. | |
1005 | * | |
1006 | * For pagecache intensive workloads, this function is the hottest | |
1007 | * spot in the kernel (apart from copy_*_user functions). | |
1008 | * | |
1009 | * Appropriate locks must be held before calling this function. | |
1010 | * | |
1011 | * @nr_to_scan: The number of pages to look through on the list. | |
1012 | * @src: The LRU list to pull pages off. | |
1013 | * @dst: The temp list to put pages on to. | |
1014 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
1015 | * @order: The caller's attempted allocation order |
1016 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 1017 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
1018 | * |
1019 | * returns how many pages were moved onto *@dst. | |
1020 | */ | |
69e05944 AM |
1021 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
1022 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1023 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1024 | { |
69e05944 | 1025 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1026 | unsigned long nr_lumpy_taken = 0; |
1027 | unsigned long nr_lumpy_dirty = 0; | |
1028 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1029 | unsigned long scan; |
1da177e4 | 1030 | |
c9b02d97 | 1031 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1032 | struct page *page; |
1033 | unsigned long pfn; | |
1034 | unsigned long end_pfn; | |
1035 | unsigned long page_pfn; | |
1036 | int zone_id; | |
1037 | ||
1da177e4 LT |
1038 | page = lru_to_page(src); |
1039 | prefetchw_prev_lru_page(page, src, flags); | |
1040 | ||
725d704e | 1041 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1042 | |
4f98a2fe | 1043 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1044 | case 0: |
1045 | list_move(&page->lru, dst); | |
2ffebca6 | 1046 | mem_cgroup_del_lru(page); |
7c8ee9a8 | 1047 | nr_taken++; |
5ad333eb AW |
1048 | break; |
1049 | ||
1050 | case -EBUSY: | |
1051 | /* else it is being freed elsewhere */ | |
1052 | list_move(&page->lru, src); | |
2ffebca6 | 1053 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1054 | continue; |
46453a6e | 1055 | |
5ad333eb AW |
1056 | default: |
1057 | BUG(); | |
1058 | } | |
1059 | ||
1060 | if (!order) | |
1061 | continue; | |
1062 | ||
1063 | /* | |
1064 | * Attempt to take all pages in the order aligned region | |
1065 | * surrounding the tag page. Only take those pages of | |
1066 | * the same active state as that tag page. We may safely | |
1067 | * round the target page pfn down to the requested order | |
1068 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
1069 | * where that page is in a different zone we will detect | |
1070 | * it from its zone id and abort this block scan. | |
1071 | */ | |
1072 | zone_id = page_zone_id(page); | |
1073 | page_pfn = page_to_pfn(page); | |
1074 | pfn = page_pfn & ~((1 << order) - 1); | |
1075 | end_pfn = pfn + (1 << order); | |
1076 | for (; pfn < end_pfn; pfn++) { | |
1077 | struct page *cursor_page; | |
1078 | ||
1079 | /* The target page is in the block, ignore it. */ | |
1080 | if (unlikely(pfn == page_pfn)) | |
1081 | continue; | |
1082 | ||
1083 | /* Avoid holes within the zone. */ | |
1084 | if (unlikely(!pfn_valid_within(pfn))) | |
1085 | break; | |
1086 | ||
1087 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1088 | |
5ad333eb AW |
1089 | /* Check that we have not crossed a zone boundary. */ |
1090 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1091 | break; |
de2e7567 MK |
1092 | |
1093 | /* | |
1094 | * If we don't have enough swap space, reclaiming of | |
1095 | * anon page which don't already have a swap slot is | |
1096 | * pointless. | |
1097 | */ | |
1098 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1099 | !PageSwapCache(cursor_page)) |
1100 | break; | |
de2e7567 | 1101 | |
ee993b13 | 1102 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1103 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1104 | mem_cgroup_del_lru(cursor_page); |
5ad333eb | 1105 | nr_taken++; |
a8a94d15 MG |
1106 | nr_lumpy_taken++; |
1107 | if (PageDirty(cursor_page)) | |
1108 | nr_lumpy_dirty++; | |
5ad333eb | 1109 | scan++; |
a8a94d15 | 1110 | } else { |
08fc468f KM |
1111 | /* the page is freed already. */ |
1112 | if (!page_count(cursor_page)) | |
1113 | continue; | |
1114 | break; | |
5ad333eb AW |
1115 | } |
1116 | } | |
08fc468f KM |
1117 | |
1118 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1119 | if (pfn < end_pfn) | |
1120 | nr_lumpy_failed++; | |
1da177e4 LT |
1121 | } |
1122 | ||
1123 | *scanned = scan; | |
a8a94d15 MG |
1124 | |
1125 | trace_mm_vmscan_lru_isolate(order, | |
1126 | nr_to_scan, scan, | |
1127 | nr_taken, | |
1128 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1129 | mode); | |
1da177e4 LT |
1130 | return nr_taken; |
1131 | } | |
1132 | ||
66e1707b BS |
1133 | static unsigned long isolate_pages_global(unsigned long nr, |
1134 | struct list_head *dst, | |
1135 | unsigned long *scanned, int order, | |
1136 | int mode, struct zone *z, | |
4f98a2fe | 1137 | int active, int file) |
66e1707b | 1138 | { |
4f98a2fe | 1139 | int lru = LRU_BASE; |
66e1707b | 1140 | if (active) |
4f98a2fe RR |
1141 | lru += LRU_ACTIVE; |
1142 | if (file) | |
1143 | lru += LRU_FILE; | |
1144 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1145 | mode, file); |
66e1707b BS |
1146 | } |
1147 | ||
5ad333eb AW |
1148 | /* |
1149 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1150 | * any active bits from the pages in the list. | |
1151 | */ | |
4f98a2fe RR |
1152 | static unsigned long clear_active_flags(struct list_head *page_list, |
1153 | unsigned int *count) | |
5ad333eb AW |
1154 | { |
1155 | int nr_active = 0; | |
4f98a2fe | 1156 | int lru; |
5ad333eb AW |
1157 | struct page *page; |
1158 | ||
4f98a2fe | 1159 | list_for_each_entry(page, page_list, lru) { |
401a8e1c | 1160 | lru = page_lru_base_type(page); |
5ad333eb | 1161 | if (PageActive(page)) { |
4f98a2fe | 1162 | lru += LRU_ACTIVE; |
5ad333eb AW |
1163 | ClearPageActive(page); |
1164 | nr_active++; | |
1165 | } | |
1489fa14 MG |
1166 | if (count) |
1167 | count[lru]++; | |
4f98a2fe | 1168 | } |
5ad333eb AW |
1169 | |
1170 | return nr_active; | |
1171 | } | |
1172 | ||
62695a84 NP |
1173 | /** |
1174 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1175 | * @page: page to isolate from its LRU list | |
1176 | * | |
1177 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1178 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1179 | * | |
1180 | * Returns 0 if the page was removed from an LRU list. | |
1181 | * Returns -EBUSY if the page was not on an LRU list. | |
1182 | * | |
1183 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1184 | * the active list, it will have PageActive set. If it was found on |
1185 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1186 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1187 | * |
1188 | * The vmstat statistic corresponding to the list on which the page was | |
1189 | * found will be decremented. | |
1190 | * | |
1191 | * Restrictions: | |
1192 | * (1) Must be called with an elevated refcount on the page. This is a | |
1193 | * fundamentnal difference from isolate_lru_pages (which is called | |
1194 | * without a stable reference). | |
1195 | * (2) the lru_lock must not be held. | |
1196 | * (3) interrupts must be enabled. | |
1197 | */ | |
1198 | int isolate_lru_page(struct page *page) | |
1199 | { | |
1200 | int ret = -EBUSY; | |
1201 | ||
1202 | if (PageLRU(page)) { | |
1203 | struct zone *zone = page_zone(page); | |
1204 | ||
1205 | spin_lock_irq(&zone->lru_lock); | |
1206 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1207 | int lru = page_lru(page); |
62695a84 NP |
1208 | ret = 0; |
1209 | ClearPageLRU(page); | |
4f98a2fe | 1210 | |
4f98a2fe | 1211 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1212 | } |
1213 | spin_unlock_irq(&zone->lru_lock); | |
1214 | } | |
1215 | return ret; | |
1216 | } | |
1217 | ||
35cd7815 RR |
1218 | /* |
1219 | * Are there way too many processes in the direct reclaim path already? | |
1220 | */ | |
1221 | static int too_many_isolated(struct zone *zone, int file, | |
1222 | struct scan_control *sc) | |
1223 | { | |
1224 | unsigned long inactive, isolated; | |
1225 | ||
1226 | if (current_is_kswapd()) | |
1227 | return 0; | |
1228 | ||
1229 | if (!scanning_global_lru(sc)) | |
1230 | return 0; | |
1231 | ||
1232 | if (file) { | |
1233 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1234 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1235 | } else { | |
1236 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1237 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1238 | } | |
1239 | ||
1240 | return isolated > inactive; | |
1241 | } | |
1242 | ||
66635629 MG |
1243 | /* |
1244 | * TODO: Try merging with migrations version of putback_lru_pages | |
1245 | */ | |
1246 | static noinline_for_stack void | |
1489fa14 | 1247 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1248 | unsigned long nr_anon, unsigned long nr_file, |
1249 | struct list_head *page_list) | |
1250 | { | |
1251 | struct page *page; | |
1252 | struct pagevec pvec; | |
1489fa14 | 1253 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1254 | |
1255 | pagevec_init(&pvec, 1); | |
1256 | ||
1257 | /* | |
1258 | * Put back any unfreeable pages. | |
1259 | */ | |
1260 | spin_lock(&zone->lru_lock); | |
1261 | while (!list_empty(page_list)) { | |
1262 | int lru; | |
1263 | page = lru_to_page(page_list); | |
1264 | VM_BUG_ON(PageLRU(page)); | |
1265 | list_del(&page->lru); | |
1266 | if (unlikely(!page_evictable(page, NULL))) { | |
1267 | spin_unlock_irq(&zone->lru_lock); | |
1268 | putback_lru_page(page); | |
1269 | spin_lock_irq(&zone->lru_lock); | |
1270 | continue; | |
1271 | } | |
1272 | SetPageLRU(page); | |
1273 | lru = page_lru(page); | |
1274 | add_page_to_lru_list(zone, page, lru); | |
1275 | if (is_active_lru(lru)) { | |
1276 | int file = is_file_lru(lru); | |
1277 | reclaim_stat->recent_rotated[file]++; | |
1278 | } | |
1279 | if (!pagevec_add(&pvec, page)) { | |
1280 | spin_unlock_irq(&zone->lru_lock); | |
1281 | __pagevec_release(&pvec); | |
1282 | spin_lock_irq(&zone->lru_lock); | |
1283 | } | |
1284 | } | |
1285 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1286 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1287 | ||
1288 | spin_unlock_irq(&zone->lru_lock); | |
1289 | pagevec_release(&pvec); | |
1290 | } | |
1291 | ||
1489fa14 MG |
1292 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1293 | struct scan_control *sc, | |
1294 | unsigned long *nr_anon, | |
1295 | unsigned long *nr_file, | |
1296 | struct list_head *isolated_list) | |
1297 | { | |
1298 | unsigned long nr_active; | |
1299 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1300 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1301 | ||
1302 | nr_active = clear_active_flags(isolated_list, count); | |
1303 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1304 | ||
1305 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1306 | -count[LRU_ACTIVE_FILE]); | |
1307 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1308 | -count[LRU_INACTIVE_FILE]); | |
1309 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1310 | -count[LRU_ACTIVE_ANON]); | |
1311 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1312 | -count[LRU_INACTIVE_ANON]); | |
1313 | ||
1314 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1315 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1316 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1317 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1318 | ||
1319 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1320 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1321 | } | |
1322 | ||
e31f3698 WF |
1323 | /* |
1324 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1325 | * | |
1326 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1327 | * everything in the list, try again and wait for writeback IO to complete. | |
1328 | * This will stall high-order allocations noticeably. Only do that when really | |
1329 | * need to free the pages under high memory pressure. | |
1330 | */ | |
1331 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1332 | unsigned long nr_freed, | |
1333 | int priority, | |
1334 | struct scan_control *sc) | |
1335 | { | |
1336 | int lumpy_stall_priority; | |
1337 | ||
1338 | /* kswapd should not stall on sync IO */ | |
1339 | if (current_is_kswapd()) | |
1340 | return false; | |
1341 | ||
1342 | /* Only stall on lumpy reclaim */ | |
ee64fc93 | 1343 | if (sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE) |
e31f3698 WF |
1344 | return false; |
1345 | ||
1346 | /* If we have relaimed everything on the isolated list, no stall */ | |
1347 | if (nr_freed == nr_taken) | |
1348 | return false; | |
1349 | ||
1350 | /* | |
1351 | * For high-order allocations, there are two stall thresholds. | |
1352 | * High-cost allocations stall immediately where as lower | |
1353 | * order allocations such as stacks require the scanning | |
1354 | * priority to be much higher before stalling. | |
1355 | */ | |
1356 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1357 | lumpy_stall_priority = DEF_PRIORITY; | |
1358 | else | |
1359 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1360 | ||
1361 | return priority <= lumpy_stall_priority; | |
1362 | } | |
1363 | ||
1da177e4 | 1364 | /* |
1742f19f AM |
1365 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1366 | * of reclaimed pages | |
1da177e4 | 1367 | */ |
66635629 MG |
1368 | static noinline_for_stack unsigned long |
1369 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1370 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1371 | { |
1372 | LIST_HEAD(page_list); | |
e247dbce | 1373 | unsigned long nr_scanned; |
05ff5137 | 1374 | unsigned long nr_reclaimed = 0; |
e247dbce | 1375 | unsigned long nr_taken; |
e247dbce KM |
1376 | unsigned long nr_anon; |
1377 | unsigned long nr_file; | |
78dc583d | 1378 | |
35cd7815 | 1379 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1380 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1381 | |
1382 | /* We are about to die and free our memory. Return now. */ | |
1383 | if (fatal_signal_pending(current)) | |
1384 | return SWAP_CLUSTER_MAX; | |
1385 | } | |
1386 | ||
7d3579e8 | 1387 | set_lumpy_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1388 | lru_add_drain(); |
1389 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1390 | |
e247dbce KM |
1391 | if (scanning_global_lru(sc)) { |
1392 | nr_taken = isolate_pages_global(nr_to_scan, | |
1393 | &page_list, &nr_scanned, sc->order, | |
3e7d3449 MG |
1394 | sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ? |
1395 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
e247dbce KM |
1396 | zone, 0, file); |
1397 | zone->pages_scanned += nr_scanned; | |
1398 | if (current_is_kswapd()) | |
1399 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1400 | nr_scanned); | |
1401 | else | |
1402 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1403 | nr_scanned); | |
1404 | } else { | |
1405 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1406 | &page_list, &nr_scanned, sc->order, | |
3e7d3449 MG |
1407 | sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ? |
1408 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
e247dbce KM |
1409 | zone, sc->mem_cgroup, |
1410 | 0, file); | |
1411 | /* | |
1412 | * mem_cgroup_isolate_pages() keeps track of | |
1413 | * scanned pages on its own. | |
1414 | */ | |
1415 | } | |
b35ea17b | 1416 | |
66635629 MG |
1417 | if (nr_taken == 0) { |
1418 | spin_unlock_irq(&zone->lru_lock); | |
1419 | return 0; | |
1420 | } | |
5ad333eb | 1421 | |
1489fa14 | 1422 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1423 | |
e247dbce | 1424 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1425 | |
0e093d99 | 1426 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1427 | |
e31f3698 WF |
1428 | /* Check if we should syncronously wait for writeback */ |
1429 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
7d3579e8 | 1430 | set_lumpy_reclaim_mode(priority, sc, true); |
0e093d99 | 1431 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1432 | } |
b35ea17b | 1433 | |
e247dbce KM |
1434 | local_irq_disable(); |
1435 | if (current_is_kswapd()) | |
1436 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1437 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1438 | |
1489fa14 | 1439 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1440 | |
1441 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1442 | zone_idx(zone), | |
1443 | nr_scanned, nr_reclaimed, | |
1444 | priority, | |
1445 | trace_shrink_flags(file, sc->lumpy_reclaim_mode)); | |
05ff5137 | 1446 | return nr_reclaimed; |
1da177e4 LT |
1447 | } |
1448 | ||
1449 | /* | |
1450 | * This moves pages from the active list to the inactive list. | |
1451 | * | |
1452 | * We move them the other way if the page is referenced by one or more | |
1453 | * processes, from rmap. | |
1454 | * | |
1455 | * If the pages are mostly unmapped, the processing is fast and it is | |
1456 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1457 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1458 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1459 | * this, so instead we remove the pages from the LRU while processing them. | |
1460 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1461 | * nobody will play with that bit on a non-LRU page. | |
1462 | * | |
1463 | * The downside is that we have to touch page->_count against each page. | |
1464 | * But we had to alter page->flags anyway. | |
1465 | */ | |
1cfb419b | 1466 | |
3eb4140f WF |
1467 | static void move_active_pages_to_lru(struct zone *zone, |
1468 | struct list_head *list, | |
1469 | enum lru_list lru) | |
1470 | { | |
1471 | unsigned long pgmoved = 0; | |
1472 | struct pagevec pvec; | |
1473 | struct page *page; | |
1474 | ||
1475 | pagevec_init(&pvec, 1); | |
1476 | ||
1477 | while (!list_empty(list)) { | |
1478 | page = lru_to_page(list); | |
3eb4140f WF |
1479 | |
1480 | VM_BUG_ON(PageLRU(page)); | |
1481 | SetPageLRU(page); | |
1482 | ||
3eb4140f WF |
1483 | list_move(&page->lru, &zone->lru[lru].list); |
1484 | mem_cgroup_add_lru_list(page, lru); | |
1485 | pgmoved++; | |
1486 | ||
1487 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1488 | spin_unlock_irq(&zone->lru_lock); | |
1489 | if (buffer_heads_over_limit) | |
1490 | pagevec_strip(&pvec); | |
1491 | __pagevec_release(&pvec); | |
1492 | spin_lock_irq(&zone->lru_lock); | |
1493 | } | |
1494 | } | |
1495 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1496 | if (!is_active_lru(lru)) | |
1497 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1498 | } | |
1cfb419b | 1499 | |
1742f19f | 1500 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1501 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1502 | { |
44c241f1 | 1503 | unsigned long nr_taken; |
69e05944 | 1504 | unsigned long pgscanned; |
6fe6b7e3 | 1505 | unsigned long vm_flags; |
1da177e4 | 1506 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1507 | LIST_HEAD(l_active); |
b69408e8 | 1508 | LIST_HEAD(l_inactive); |
1da177e4 | 1509 | struct page *page; |
6e901571 | 1510 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1511 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1512 | |
1513 | lru_add_drain(); | |
1514 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1515 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1516 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1517 | &pgscanned, sc->order, | |
1518 | ISOLATE_ACTIVE, zone, | |
1519 | 1, file); | |
1cfb419b | 1520 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1521 | } else { |
1522 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1523 | &pgscanned, sc->order, | |
1524 | ISOLATE_ACTIVE, zone, | |
1525 | sc->mem_cgroup, 1, file); | |
1526 | /* | |
1527 | * mem_cgroup_isolate_pages() keeps track of | |
1528 | * scanned pages on its own. | |
1529 | */ | |
4f98a2fe | 1530 | } |
8b25c6d2 | 1531 | |
b7c46d15 | 1532 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1533 | |
3eb4140f | 1534 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1535 | if (file) |
44c241f1 | 1536 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1537 | else |
44c241f1 | 1538 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1539 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1540 | spin_unlock_irq(&zone->lru_lock); |
1541 | ||
1da177e4 LT |
1542 | while (!list_empty(&l_hold)) { |
1543 | cond_resched(); | |
1544 | page = lru_to_page(&l_hold); | |
1545 | list_del(&page->lru); | |
7e9cd484 | 1546 | |
894bc310 LS |
1547 | if (unlikely(!page_evictable(page, NULL))) { |
1548 | putback_lru_page(page); | |
1549 | continue; | |
1550 | } | |
1551 | ||
64574746 | 1552 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
44c241f1 | 1553 | nr_rotated++; |
8cab4754 WF |
1554 | /* |
1555 | * Identify referenced, file-backed active pages and | |
1556 | * give them one more trip around the active list. So | |
1557 | * that executable code get better chances to stay in | |
1558 | * memory under moderate memory pressure. Anon pages | |
1559 | * are not likely to be evicted by use-once streaming | |
1560 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1561 | * so we ignore them here. | |
1562 | */ | |
41e20983 | 1563 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1564 | list_add(&page->lru, &l_active); |
1565 | continue; | |
1566 | } | |
1567 | } | |
7e9cd484 | 1568 | |
5205e56e | 1569 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1570 | list_add(&page->lru, &l_inactive); |
1571 | } | |
1572 | ||
b555749a | 1573 | /* |
8cab4754 | 1574 | * Move pages back to the lru list. |
b555749a | 1575 | */ |
2a1dc509 | 1576 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1577 | /* |
8cab4754 WF |
1578 | * Count referenced pages from currently used mappings as rotated, |
1579 | * even though only some of them are actually re-activated. This | |
1580 | * helps balance scan pressure between file and anonymous pages in | |
1581 | * get_scan_ratio. | |
7e9cd484 | 1582 | */ |
b7c46d15 | 1583 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1584 | |
3eb4140f WF |
1585 | move_active_pages_to_lru(zone, &l_active, |
1586 | LRU_ACTIVE + file * LRU_FILE); | |
1587 | move_active_pages_to_lru(zone, &l_inactive, | |
1588 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1589 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1590 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1591 | } |
1592 | ||
74e3f3c3 | 1593 | #ifdef CONFIG_SWAP |
14797e23 | 1594 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1595 | { |
1596 | unsigned long active, inactive; | |
1597 | ||
1598 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1599 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1600 | ||
1601 | if (inactive * zone->inactive_ratio < active) | |
1602 | return 1; | |
1603 | ||
1604 | return 0; | |
1605 | } | |
1606 | ||
14797e23 KM |
1607 | /** |
1608 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1609 | * @zone: zone to check | |
1610 | * @sc: scan control of this context | |
1611 | * | |
1612 | * Returns true if the zone does not have enough inactive anon pages, | |
1613 | * meaning some active anon pages need to be deactivated. | |
1614 | */ | |
1615 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1616 | { | |
1617 | int low; | |
1618 | ||
74e3f3c3 MK |
1619 | /* |
1620 | * If we don't have swap space, anonymous page deactivation | |
1621 | * is pointless. | |
1622 | */ | |
1623 | if (!total_swap_pages) | |
1624 | return 0; | |
1625 | ||
e72e2bd6 | 1626 | if (scanning_global_lru(sc)) |
14797e23 KM |
1627 | low = inactive_anon_is_low_global(zone); |
1628 | else | |
c772be93 | 1629 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1630 | return low; |
1631 | } | |
74e3f3c3 MK |
1632 | #else |
1633 | static inline int inactive_anon_is_low(struct zone *zone, | |
1634 | struct scan_control *sc) | |
1635 | { | |
1636 | return 0; | |
1637 | } | |
1638 | #endif | |
14797e23 | 1639 | |
56e49d21 RR |
1640 | static int inactive_file_is_low_global(struct zone *zone) |
1641 | { | |
1642 | unsigned long active, inactive; | |
1643 | ||
1644 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1645 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1646 | ||
1647 | return (active > inactive); | |
1648 | } | |
1649 | ||
1650 | /** | |
1651 | * inactive_file_is_low - check if file pages need to be deactivated | |
1652 | * @zone: zone to check | |
1653 | * @sc: scan control of this context | |
1654 | * | |
1655 | * When the system is doing streaming IO, memory pressure here | |
1656 | * ensures that active file pages get deactivated, until more | |
1657 | * than half of the file pages are on the inactive list. | |
1658 | * | |
1659 | * Once we get to that situation, protect the system's working | |
1660 | * set from being evicted by disabling active file page aging. | |
1661 | * | |
1662 | * This uses a different ratio than the anonymous pages, because | |
1663 | * the page cache uses a use-once replacement algorithm. | |
1664 | */ | |
1665 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1666 | { | |
1667 | int low; | |
1668 | ||
1669 | if (scanning_global_lru(sc)) | |
1670 | low = inactive_file_is_low_global(zone); | |
1671 | else | |
1672 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1673 | return low; | |
1674 | } | |
1675 | ||
b39415b2 RR |
1676 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1677 | int file) | |
1678 | { | |
1679 | if (file) | |
1680 | return inactive_file_is_low(zone, sc); | |
1681 | else | |
1682 | return inactive_anon_is_low(zone, sc); | |
1683 | } | |
1684 | ||
4f98a2fe | 1685 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1686 | struct zone *zone, struct scan_control *sc, int priority) |
1687 | { | |
4f98a2fe RR |
1688 | int file = is_file_lru(lru); |
1689 | ||
b39415b2 RR |
1690 | if (is_active_lru(lru)) { |
1691 | if (inactive_list_is_low(zone, sc, file)) | |
1692 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1693 | return 0; |
1694 | } | |
1695 | ||
33c120ed | 1696 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1697 | } |
1698 | ||
76a33fc3 SL |
1699 | /* |
1700 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1701 | * until we collected @swap_cluster_max pages to scan. | |
1702 | */ | |
1703 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1704 | unsigned long *nr_saved_scan) | |
1705 | { | |
1706 | unsigned long nr; | |
1707 | ||
1708 | *nr_saved_scan += nr_to_scan; | |
1709 | nr = *nr_saved_scan; | |
1710 | ||
1711 | if (nr >= SWAP_CLUSTER_MAX) | |
1712 | *nr_saved_scan = 0; | |
1713 | else | |
1714 | nr = 0; | |
1715 | ||
1716 | return nr; | |
1717 | } | |
1718 | ||
4f98a2fe RR |
1719 | /* |
1720 | * Determine how aggressively the anon and file LRU lists should be | |
1721 | * scanned. The relative value of each set of LRU lists is determined | |
1722 | * by looking at the fraction of the pages scanned we did rotate back | |
1723 | * onto the active list instead of evict. | |
1724 | * | |
76a33fc3 | 1725 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1726 | */ |
76a33fc3 SL |
1727 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1728 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1729 | { |
1730 | unsigned long anon, file, free; | |
1731 | unsigned long anon_prio, file_prio; | |
1732 | unsigned long ap, fp; | |
6e901571 | 1733 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1734 | u64 fraction[2], denominator; |
1735 | enum lru_list l; | |
1736 | int noswap = 0; | |
1737 | ||
1738 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1739 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1740 | noswap = 1; | |
1741 | fraction[0] = 0; | |
1742 | fraction[1] = 1; | |
1743 | denominator = 1; | |
1744 | goto out; | |
1745 | } | |
4f98a2fe | 1746 | |
0b217676 VL |
1747 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1748 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1749 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1750 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1751 | |
e72e2bd6 | 1752 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1753 | free = zone_page_state(zone, NR_FREE_PAGES); |
1754 | /* If we have very few page cache pages, | |
1755 | force-scan anon pages. */ | |
41858966 | 1756 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1757 | fraction[0] = 1; |
1758 | fraction[1] = 0; | |
1759 | denominator = 1; | |
1760 | goto out; | |
eeee9a8c | 1761 | } |
4f98a2fe RR |
1762 | } |
1763 | ||
58c37f6e KM |
1764 | /* |
1765 | * With swappiness at 100, anonymous and file have the same priority. | |
1766 | * This scanning priority is essentially the inverse of IO cost. | |
1767 | */ | |
1768 | anon_prio = sc->swappiness; | |
1769 | file_prio = 200 - sc->swappiness; | |
1770 | ||
4f98a2fe RR |
1771 | /* |
1772 | * OK, so we have swap space and a fair amount of page cache | |
1773 | * pages. We use the recently rotated / recently scanned | |
1774 | * ratios to determine how valuable each cache is. | |
1775 | * | |
1776 | * Because workloads change over time (and to avoid overflow) | |
1777 | * we keep these statistics as a floating average, which ends | |
1778 | * up weighing recent references more than old ones. | |
1779 | * | |
1780 | * anon in [0], file in [1] | |
1781 | */ | |
58c37f6e | 1782 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1783 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1784 | reclaim_stat->recent_scanned[0] /= 2; |
1785 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1786 | } |
1787 | ||
6e901571 | 1788 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1789 | reclaim_stat->recent_scanned[1] /= 2; |
1790 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1791 | } |
1792 | ||
4f98a2fe | 1793 | /* |
00d8089c RR |
1794 | * The amount of pressure on anon vs file pages is inversely |
1795 | * proportional to the fraction of recently scanned pages on | |
1796 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1797 | */ |
6e901571 KM |
1798 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1799 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1800 | |
6e901571 KM |
1801 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1802 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1803 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1804 | |
76a33fc3 SL |
1805 | fraction[0] = ap; |
1806 | fraction[1] = fp; | |
1807 | denominator = ap + fp + 1; | |
1808 | out: | |
1809 | for_each_evictable_lru(l) { | |
1810 | int file = is_file_lru(l); | |
1811 | unsigned long scan; | |
6e08a369 | 1812 | |
76a33fc3 SL |
1813 | scan = zone_nr_lru_pages(zone, sc, l); |
1814 | if (priority || noswap) { | |
1815 | scan >>= priority; | |
1816 | scan = div64_u64(scan * fraction[file], denominator); | |
1817 | } | |
1818 | nr[l] = nr_scan_try_batch(scan, | |
1819 | &reclaim_stat->nr_saved_scan[l]); | |
1820 | } | |
6e08a369 | 1821 | } |
4f98a2fe | 1822 | |
3e7d3449 MG |
1823 | /* |
1824 | * Reclaim/compaction depends on a number of pages being freed. To avoid | |
1825 | * disruption to the system, a small number of order-0 pages continue to be | |
1826 | * rotated and reclaimed in the normal fashion. However, by the time we get | |
1827 | * back to the allocator and call try_to_compact_zone(), we ensure that | |
1828 | * there are enough free pages for it to be likely successful | |
1829 | */ | |
1830 | static inline bool should_continue_reclaim(struct zone *zone, | |
1831 | unsigned long nr_reclaimed, | |
1832 | unsigned long nr_scanned, | |
1833 | struct scan_control *sc) | |
1834 | { | |
1835 | unsigned long pages_for_compaction; | |
1836 | unsigned long inactive_lru_pages; | |
1837 | ||
1838 | /* If not in reclaim/compaction mode, stop */ | |
1839 | if (!(sc->lumpy_reclaim_mode & LUMPY_MODE_COMPACTION)) | |
1840 | return false; | |
1841 | ||
1842 | /* | |
1843 | * If we failed to reclaim and have scanned the full list, stop. | |
1844 | * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far | |
1845 | * faster but obviously would be less likely to succeed | |
1846 | * allocation. If this is desirable, use GFP_REPEAT to decide | |
1847 | * if both reclaimed and scanned should be checked or just | |
1848 | * reclaimed | |
1849 | */ | |
1850 | if (!nr_reclaimed && !nr_scanned) | |
1851 | return false; | |
1852 | ||
1853 | /* | |
1854 | * If we have not reclaimed enough pages for compaction and the | |
1855 | * inactive lists are large enough, continue reclaiming | |
1856 | */ | |
1857 | pages_for_compaction = (2UL << sc->order); | |
1858 | inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + | |
1859 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1860 | if (sc->nr_reclaimed < pages_for_compaction && | |
1861 | inactive_lru_pages > pages_for_compaction) | |
1862 | return true; | |
1863 | ||
1864 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
1865 | switch (compaction_suitable(zone, sc->order)) { | |
1866 | case COMPACT_PARTIAL: | |
1867 | case COMPACT_CONTINUE: | |
1868 | return false; | |
1869 | default: | |
1870 | return true; | |
1871 | } | |
1872 | } | |
1873 | ||
1da177e4 LT |
1874 | /* |
1875 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1876 | */ | |
a79311c1 | 1877 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1878 | struct scan_control *sc) |
1da177e4 | 1879 | { |
b69408e8 | 1880 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1881 | unsigned long nr_to_scan; |
b69408e8 | 1882 | enum lru_list l; |
3e7d3449 | 1883 | unsigned long nr_reclaimed; |
22fba335 | 1884 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
3e7d3449 | 1885 | unsigned long nr_scanned = sc->nr_scanned; |
e0f79b8f | 1886 | |
3e7d3449 MG |
1887 | restart: |
1888 | nr_reclaimed = 0; | |
76a33fc3 | 1889 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1890 | |
556adecb RR |
1891 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1892 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1893 | for_each_evictable_lru(l) { |
b69408e8 | 1894 | if (nr[l]) { |
ece74b2e KM |
1895 | nr_to_scan = min_t(unsigned long, |
1896 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1897 | nr[l] -= nr_to_scan; |
1da177e4 | 1898 | |
01dbe5c9 KM |
1899 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1900 | zone, sc, priority); | |
b69408e8 | 1901 | } |
1da177e4 | 1902 | } |
a79311c1 RR |
1903 | /* |
1904 | * On large memory systems, scan >> priority can become | |
1905 | * really large. This is fine for the starting priority; | |
1906 | * we want to put equal scanning pressure on each zone. | |
1907 | * However, if the VM has a harder time of freeing pages, | |
1908 | * with multiple processes reclaiming pages, the total | |
1909 | * freeing target can get unreasonably large. | |
1910 | */ | |
338fde90 | 1911 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1912 | break; |
1da177e4 | 1913 | } |
3e7d3449 | 1914 | sc->nr_reclaimed += nr_reclaimed; |
01dbe5c9 | 1915 | |
556adecb RR |
1916 | /* |
1917 | * Even if we did not try to evict anon pages at all, we want to | |
1918 | * rebalance the anon lru active/inactive ratio. | |
1919 | */ | |
74e3f3c3 | 1920 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1921 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1922 | ||
3e7d3449 MG |
1923 | /* reclaim/compaction might need reclaim to continue */ |
1924 | if (should_continue_reclaim(zone, nr_reclaimed, | |
1925 | sc->nr_scanned - nr_scanned, sc)) | |
1926 | goto restart; | |
1927 | ||
232ea4d6 | 1928 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1929 | } |
1930 | ||
1931 | /* | |
1932 | * This is the direct reclaim path, for page-allocating processes. We only | |
1933 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1934 | * request. | |
1935 | * | |
41858966 MG |
1936 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1937 | * Because: | |
1da177e4 LT |
1938 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1939 | * allocation or | |
41858966 MG |
1940 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1941 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1942 | * zone defense algorithm. | |
1da177e4 | 1943 | * |
1da177e4 LT |
1944 | * If a zone is deemed to be full of pinned pages then just give it a light |
1945 | * scan then give up on it. | |
1946 | */ | |
d1908362 | 1947 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1948 | struct scan_control *sc) |
1da177e4 | 1949 | { |
dd1a239f | 1950 | struct zoneref *z; |
54a6eb5c | 1951 | struct zone *zone; |
1cfb419b | 1952 | |
d4debc66 MG |
1953 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1954 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1955 | if (!populated_zone(zone)) |
1da177e4 | 1956 | continue; |
1cfb419b KH |
1957 | /* |
1958 | * Take care memory controller reclaiming has small influence | |
1959 | * to global LRU. | |
1960 | */ | |
e72e2bd6 | 1961 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1962 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1963 | continue; | |
93e4a89a | 1964 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1965 | continue; /* Let kswapd poll it */ |
1cfb419b | 1966 | } |
408d8544 | 1967 | |
a79311c1 | 1968 | shrink_zone(priority, zone, sc); |
1da177e4 | 1969 | } |
d1908362 MK |
1970 | } |
1971 | ||
1972 | static bool zone_reclaimable(struct zone *zone) | |
1973 | { | |
1974 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
1975 | } | |
1976 | ||
1977 | /* | |
1978 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
1979 | * the zone into all_unreclaimable. It can't handle OOM during hibernation. | |
1980 | * So let's check zone's unreclaimable in direct reclaim as well as kswapd. | |
1981 | */ | |
1982 | static bool all_unreclaimable(struct zonelist *zonelist, | |
1983 | struct scan_control *sc) | |
1984 | { | |
1985 | struct zoneref *z; | |
1986 | struct zone *zone; | |
1987 | bool all_unreclaimable = true; | |
1988 | ||
1989 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
1990 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
1991 | if (!populated_zone(zone)) | |
1992 | continue; | |
1993 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1994 | continue; | |
1995 | if (zone_reclaimable(zone)) { | |
1996 | all_unreclaimable = false; | |
1997 | break; | |
1998 | } | |
1999 | } | |
2000 | ||
bb21c7ce | 2001 | return all_unreclaimable; |
1da177e4 | 2002 | } |
4f98a2fe | 2003 | |
1da177e4 LT |
2004 | /* |
2005 | * This is the main entry point to direct page reclaim. | |
2006 | * | |
2007 | * If a full scan of the inactive list fails to free enough memory then we | |
2008 | * are "out of memory" and something needs to be killed. | |
2009 | * | |
2010 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2011 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2012 | * caller can't do much about. We kick the writeback threads and take explicit |
2013 | * naps in the hope that some of these pages can be written. But if the | |
2014 | * allocating task holds filesystem locks which prevent writeout this might not | |
2015 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2016 | * |
2017 | * returns: 0, if no pages reclaimed | |
2018 | * else, the number of pages reclaimed | |
1da177e4 | 2019 | */ |
dac1d27b | 2020 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 2021 | struct scan_control *sc) |
1da177e4 LT |
2022 | { |
2023 | int priority; | |
69e05944 | 2024 | unsigned long total_scanned = 0; |
1da177e4 | 2025 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2026 | struct zoneref *z; |
54a6eb5c | 2027 | struct zone *zone; |
22fba335 | 2028 | unsigned long writeback_threshold; |
1da177e4 | 2029 | |
c0ff7453 | 2030 | get_mems_allowed(); |
873b4771 KK |
2031 | delayacct_freepages_start(); |
2032 | ||
e72e2bd6 | 2033 | if (scanning_global_lru(sc)) |
1cfb419b | 2034 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
2035 | |
2036 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 2037 | sc->nr_scanned = 0; |
f7b7fd8f RR |
2038 | if (!priority) |
2039 | disable_swap_token(); | |
d1908362 | 2040 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
2041 | /* |
2042 | * Don't shrink slabs when reclaiming memory from | |
2043 | * over limit cgroups | |
2044 | */ | |
e72e2bd6 | 2045 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 2046 | unsigned long lru_pages = 0; |
d4debc66 MG |
2047 | for_each_zone_zonelist(zone, z, zonelist, |
2048 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2049 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2050 | continue; | |
2051 | ||
2052 | lru_pages += zone_reclaimable_pages(zone); | |
2053 | } | |
2054 | ||
dd1a239f | 2055 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 2056 | if (reclaim_state) { |
a79311c1 | 2057 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2058 | reclaim_state->reclaimed_slab = 0; |
2059 | } | |
1da177e4 | 2060 | } |
66e1707b | 2061 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2062 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2063 | goto out; |
1da177e4 LT |
2064 | |
2065 | /* | |
2066 | * Try to write back as many pages as we just scanned. This | |
2067 | * tends to cause slow streaming writers to write data to the | |
2068 | * disk smoothly, at the dirtying rate, which is nice. But | |
2069 | * that's undesirable in laptop mode, where we *want* lumpy | |
2070 | * writeout. So in laptop mode, write out the whole world. | |
2071 | */ | |
22fba335 KM |
2072 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2073 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 2074 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 2075 | sc->may_writepage = 1; |
1da177e4 LT |
2076 | } |
2077 | ||
2078 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 2079 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
2080 | priority < DEF_PRIORITY - 2) { |
2081 | struct zone *preferred_zone; | |
2082 | ||
2083 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
2084 | NULL, &preferred_zone); | |
2085 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); | |
2086 | } | |
1da177e4 | 2087 | } |
bb21c7ce | 2088 | |
1da177e4 | 2089 | out: |
873b4771 | 2090 | delayacct_freepages_end(); |
c0ff7453 | 2091 | put_mems_allowed(); |
873b4771 | 2092 | |
bb21c7ce KM |
2093 | if (sc->nr_reclaimed) |
2094 | return sc->nr_reclaimed; | |
2095 | ||
2096 | /* top priority shrink_zones still had more to do? don't OOM, then */ | |
d1908362 | 2097 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2098 | return 1; |
2099 | ||
2100 | return 0; | |
1da177e4 LT |
2101 | } |
2102 | ||
dac1d27b | 2103 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2104 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2105 | { |
33906bc5 | 2106 | unsigned long nr_reclaimed; |
66e1707b BS |
2107 | struct scan_control sc = { |
2108 | .gfp_mask = gfp_mask, | |
2109 | .may_writepage = !laptop_mode, | |
22fba335 | 2110 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2111 | .may_unmap = 1, |
2e2e4259 | 2112 | .may_swap = 1, |
66e1707b BS |
2113 | .swappiness = vm_swappiness, |
2114 | .order = order, | |
2115 | .mem_cgroup = NULL, | |
327c0e96 | 2116 | .nodemask = nodemask, |
66e1707b BS |
2117 | }; |
2118 | ||
33906bc5 MG |
2119 | trace_mm_vmscan_direct_reclaim_begin(order, |
2120 | sc.may_writepage, | |
2121 | gfp_mask); | |
2122 | ||
2123 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2124 | ||
2125 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2126 | ||
2127 | return nr_reclaimed; | |
66e1707b BS |
2128 | } |
2129 | ||
00f0b825 | 2130 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2131 | |
4e416953 BS |
2132 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2133 | gfp_t gfp_mask, bool noswap, | |
2134 | unsigned int swappiness, | |
14fec796 | 2135 | struct zone *zone) |
4e416953 BS |
2136 | { |
2137 | struct scan_control sc = { | |
b8f5c566 | 2138 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2139 | .may_writepage = !laptop_mode, |
2140 | .may_unmap = 1, | |
2141 | .may_swap = !noswap, | |
4e416953 BS |
2142 | .swappiness = swappiness, |
2143 | .order = 0, | |
2144 | .mem_cgroup = mem, | |
4e416953 | 2145 | }; |
4e416953 BS |
2146 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2147 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2148 | |
2149 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2150 | sc.may_writepage, | |
2151 | sc.gfp_mask); | |
2152 | ||
4e416953 BS |
2153 | /* |
2154 | * NOTE: Although we can get the priority field, using it | |
2155 | * here is not a good idea, since it limits the pages we can scan. | |
2156 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2157 | * will pick up pages from other mem cgroup's as well. We hack | |
2158 | * the priority and make it zero. | |
2159 | */ | |
2160 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2161 | |
2162 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2163 | ||
4e416953 BS |
2164 | return sc.nr_reclaimed; |
2165 | } | |
2166 | ||
e1a1cd59 | 2167 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2168 | gfp_t gfp_mask, |
2169 | bool noswap, | |
2170 | unsigned int swappiness) | |
66e1707b | 2171 | { |
4e416953 | 2172 | struct zonelist *zonelist; |
bdce6d9e | 2173 | unsigned long nr_reclaimed; |
66e1707b | 2174 | struct scan_control sc = { |
66e1707b | 2175 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2176 | .may_unmap = 1, |
2e2e4259 | 2177 | .may_swap = !noswap, |
22fba335 | 2178 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2179 | .swappiness = swappiness, |
66e1707b BS |
2180 | .order = 0, |
2181 | .mem_cgroup = mem_cont, | |
327c0e96 | 2182 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 2183 | }; |
66e1707b | 2184 | |
dd1a239f MG |
2185 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2186 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
2187 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
bdce6d9e KM |
2188 | |
2189 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2190 | sc.may_writepage, | |
2191 | sc.gfp_mask); | |
2192 | ||
2193 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2194 | ||
2195 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2196 | ||
2197 | return nr_reclaimed; | |
66e1707b BS |
2198 | } |
2199 | #endif | |
2200 | ||
f50de2d3 | 2201 | /* is kswapd sleeping prematurely? */ |
bb3ab596 | 2202 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
f50de2d3 | 2203 | { |
bb3ab596 | 2204 | int i; |
f50de2d3 MG |
2205 | |
2206 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2207 | if (remaining) | |
2208 | return 1; | |
2209 | ||
2210 | /* If after HZ/10, a zone is below the high mark, it's premature */ | |
bb3ab596 KM |
2211 | for (i = 0; i < pgdat->nr_zones; i++) { |
2212 | struct zone *zone = pgdat->node_zones + i; | |
2213 | ||
2214 | if (!populated_zone(zone)) | |
2215 | continue; | |
2216 | ||
93e4a89a | 2217 | if (zone->all_unreclaimable) |
de3fab39 KM |
2218 | continue; |
2219 | ||
88f5acf8 | 2220 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), |
f50de2d3 MG |
2221 | 0, 0)) |
2222 | return 1; | |
bb3ab596 | 2223 | } |
f50de2d3 MG |
2224 | |
2225 | return 0; | |
2226 | } | |
2227 | ||
1da177e4 LT |
2228 | /* |
2229 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2230 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2231 | * |
1da177e4 LT |
2232 | * Returns the number of pages which were actually freed. |
2233 | * | |
2234 | * There is special handling here for zones which are full of pinned pages. | |
2235 | * This can happen if the pages are all mlocked, or if they are all used by | |
2236 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2237 | * What we do is to detect the case where all pages in the zone have been | |
2238 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2239 | * dead and from now on, only perform a short scan. Basically we're polling | |
2240 | * the zone for when the problem goes away. | |
2241 | * | |
2242 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2243 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2244 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2245 | * lower zones regardless of the number of free pages in the lower zones. This | |
2246 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2247 | * of pages is balanced across the zones. | |
1da177e4 | 2248 | */ |
d6277db4 | 2249 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 2250 | { |
1da177e4 LT |
2251 | int all_zones_ok; |
2252 | int priority; | |
2253 | int i; | |
69e05944 | 2254 | unsigned long total_scanned; |
1da177e4 | 2255 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2256 | struct scan_control sc = { |
2257 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2258 | .may_unmap = 1, |
2e2e4259 | 2259 | .may_swap = 1, |
22fba335 KM |
2260 | /* |
2261 | * kswapd doesn't want to be bailed out while reclaim. because | |
2262 | * we want to put equal scanning pressure on each zone. | |
2263 | */ | |
2264 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2265 | .swappiness = vm_swappiness, |
5ad333eb | 2266 | .order = order, |
66e1707b | 2267 | .mem_cgroup = NULL, |
179e9639 | 2268 | }; |
1da177e4 LT |
2269 | loop_again: |
2270 | total_scanned = 0; | |
a79311c1 | 2271 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2272 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2273 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2274 | |
1da177e4 LT |
2275 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
2276 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
2277 | unsigned long lru_pages = 0; | |
bb3ab596 | 2278 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2279 | |
f7b7fd8f RR |
2280 | /* The swap token gets in the way of swapout... */ |
2281 | if (!priority) | |
2282 | disable_swap_token(); | |
2283 | ||
1da177e4 LT |
2284 | all_zones_ok = 1; |
2285 | ||
d6277db4 RW |
2286 | /* |
2287 | * Scan in the highmem->dma direction for the highest | |
2288 | * zone which needs scanning | |
2289 | */ | |
2290 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2291 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2292 | |
d6277db4 RW |
2293 | if (!populated_zone(zone)) |
2294 | continue; | |
1da177e4 | 2295 | |
93e4a89a | 2296 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2297 | continue; |
1da177e4 | 2298 | |
556adecb RR |
2299 | /* |
2300 | * Do some background aging of the anon list, to give | |
2301 | * pages a chance to be referenced before reclaiming. | |
2302 | */ | |
14797e23 | 2303 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2304 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2305 | &sc, priority, 0); | |
2306 | ||
88f5acf8 | 2307 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2308 | high_wmark_pages(zone), 0, 0)) { |
d6277db4 | 2309 | end_zone = i; |
e1dbeda6 | 2310 | break; |
1da177e4 | 2311 | } |
1da177e4 | 2312 | } |
e1dbeda6 AM |
2313 | if (i < 0) |
2314 | goto out; | |
2315 | ||
1da177e4 LT |
2316 | for (i = 0; i <= end_zone; i++) { |
2317 | struct zone *zone = pgdat->node_zones + i; | |
2318 | ||
adea02a1 | 2319 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2320 | } |
2321 | ||
2322 | /* | |
2323 | * Now scan the zone in the dma->highmem direction, stopping | |
2324 | * at the last zone which needs scanning. | |
2325 | * | |
2326 | * We do this because the page allocator works in the opposite | |
2327 | * direction. This prevents the page allocator from allocating | |
2328 | * pages behind kswapd's direction of progress, which would | |
2329 | * cause too much scanning of the lower zones. | |
2330 | */ | |
2331 | for (i = 0; i <= end_zone; i++) { | |
2332 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2333 | int nr_slab; |
1da177e4 | 2334 | |
f3fe6512 | 2335 | if (!populated_zone(zone)) |
1da177e4 LT |
2336 | continue; |
2337 | ||
93e4a89a | 2338 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2339 | continue; |
2340 | ||
1da177e4 | 2341 | sc.nr_scanned = 0; |
4e416953 | 2342 | |
4e416953 BS |
2343 | /* |
2344 | * Call soft limit reclaim before calling shrink_zone. | |
2345 | * For now we ignore the return value | |
2346 | */ | |
00918b6a KM |
2347 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask); |
2348 | ||
32a4330d RR |
2349 | /* |
2350 | * We put equal pressure on every zone, unless one | |
2351 | * zone has way too many pages free already. | |
2352 | */ | |
88f5acf8 | 2353 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2354 | 8*high_wmark_pages(zone), end_zone, 0)) |
a79311c1 | 2355 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2356 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2357 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2358 | lru_pages); | |
a79311c1 | 2359 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2360 | total_scanned += sc.nr_scanned; |
93e4a89a | 2361 | if (zone->all_unreclaimable) |
1da177e4 | 2362 | continue; |
d1908362 | 2363 | if (nr_slab == 0 && !zone_reclaimable(zone)) |
93e4a89a | 2364 | zone->all_unreclaimable = 1; |
1da177e4 LT |
2365 | /* |
2366 | * If we've done a decent amount of scanning and | |
2367 | * the reclaim ratio is low, start doing writepage | |
2368 | * even in laptop mode | |
2369 | */ | |
2370 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2371 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2372 | sc.may_writepage = 1; |
bb3ab596 | 2373 | |
3e7d3449 MG |
2374 | /* |
2375 | * Compact the zone for higher orders to reduce | |
2376 | * latencies for higher-order allocations that | |
2377 | * would ordinarily call try_to_compact_pages() | |
2378 | */ | |
2379 | if (sc.order > PAGE_ALLOC_COSTLY_ORDER) | |
77f1fe6b MG |
2380 | compact_zone_order(zone, sc.order, sc.gfp_mask, |
2381 | false); | |
3e7d3449 | 2382 | |
88f5acf8 | 2383 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2384 | high_wmark_pages(zone), end_zone, 0)) { |
2385 | all_zones_ok = 0; | |
2386 | /* | |
2387 | * We are still under min water mark. This | |
2388 | * means that we have a GFP_ATOMIC allocation | |
2389 | * failure risk. Hurry up! | |
2390 | */ | |
88f5acf8 | 2391 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2392 | min_wmark_pages(zone), end_zone, 0)) |
2393 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2394 | } else { |
2395 | /* | |
2396 | * If a zone reaches its high watermark, | |
2397 | * consider it to be no longer congested. It's | |
2398 | * possible there are dirty pages backed by | |
2399 | * congested BDIs but as pressure is relieved, | |
2400 | * spectulatively avoid congestion waits | |
2401 | */ | |
2402 | zone_clear_flag(zone, ZONE_CONGESTED); | |
45973d74 | 2403 | } |
bb3ab596 | 2404 | |
1da177e4 | 2405 | } |
1da177e4 LT |
2406 | if (all_zones_ok) |
2407 | break; /* kswapd: all done */ | |
2408 | /* | |
2409 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2410 | * another pass across the zones. | |
2411 | */ | |
bb3ab596 KM |
2412 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2413 | if (has_under_min_watermark_zone) | |
2414 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2415 | else | |
2416 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2417 | } | |
1da177e4 LT |
2418 | |
2419 | /* | |
2420 | * We do this so kswapd doesn't build up large priorities for | |
2421 | * example when it is freeing in parallel with allocators. It | |
2422 | * matches the direct reclaim path behaviour in terms of impact | |
2423 | * on zone->*_priority. | |
2424 | */ | |
a79311c1 | 2425 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2426 | break; |
2427 | } | |
2428 | out: | |
1da177e4 LT |
2429 | if (!all_zones_ok) { |
2430 | cond_resched(); | |
8357376d RW |
2431 | |
2432 | try_to_freeze(); | |
2433 | ||
73ce02e9 KM |
2434 | /* |
2435 | * Fragmentation may mean that the system cannot be | |
2436 | * rebalanced for high-order allocations in all zones. | |
2437 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2438 | * it means the zones have been fully scanned and are still | |
2439 | * not balanced. For high-order allocations, there is | |
2440 | * little point trying all over again as kswapd may | |
2441 | * infinite loop. | |
2442 | * | |
2443 | * Instead, recheck all watermarks at order-0 as they | |
2444 | * are the most important. If watermarks are ok, kswapd will go | |
2445 | * back to sleep. High-order users can still perform direct | |
2446 | * reclaim if they wish. | |
2447 | */ | |
2448 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2449 | order = sc.order = 0; | |
2450 | ||
1da177e4 LT |
2451 | goto loop_again; |
2452 | } | |
2453 | ||
a79311c1 | 2454 | return sc.nr_reclaimed; |
1da177e4 LT |
2455 | } |
2456 | ||
f0bc0a60 KM |
2457 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) |
2458 | { | |
2459 | long remaining = 0; | |
2460 | DEFINE_WAIT(wait); | |
2461 | ||
2462 | if (freezing(current) || kthread_should_stop()) | |
2463 | return; | |
2464 | ||
2465 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2466 | ||
2467 | /* Try to sleep for a short interval */ | |
2468 | if (!sleeping_prematurely(pgdat, order, remaining)) { | |
2469 | remaining = schedule_timeout(HZ/10); | |
2470 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2471 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2472 | } | |
2473 | ||
2474 | /* | |
2475 | * After a short sleep, check if it was a premature sleep. If not, then | |
2476 | * go fully to sleep until explicitly woken up. | |
2477 | */ | |
2478 | if (!sleeping_prematurely(pgdat, order, remaining)) { | |
2479 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); | |
2480 | ||
2481 | /* | |
2482 | * vmstat counters are not perfectly accurate and the estimated | |
2483 | * value for counters such as NR_FREE_PAGES can deviate from the | |
2484 | * true value by nr_online_cpus * threshold. To avoid the zone | |
2485 | * watermarks being breached while under pressure, we reduce the | |
2486 | * per-cpu vmstat threshold while kswapd is awake and restore | |
2487 | * them before going back to sleep. | |
2488 | */ | |
2489 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
2490 | schedule(); | |
2491 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); | |
2492 | } else { | |
2493 | if (remaining) | |
2494 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
2495 | else | |
2496 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
2497 | } | |
2498 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2499 | } | |
2500 | ||
1da177e4 LT |
2501 | /* |
2502 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2503 | * from the init process. |
1da177e4 LT |
2504 | * |
2505 | * This basically trickles out pages so that we have _some_ | |
2506 | * free memory available even if there is no other activity | |
2507 | * that frees anything up. This is needed for things like routing | |
2508 | * etc, where we otherwise might have all activity going on in | |
2509 | * asynchronous contexts that cannot page things out. | |
2510 | * | |
2511 | * If there are applications that are active memory-allocators | |
2512 | * (most normal use), this basically shouldn't matter. | |
2513 | */ | |
2514 | static int kswapd(void *p) | |
2515 | { | |
2516 | unsigned long order; | |
2517 | pg_data_t *pgdat = (pg_data_t*)p; | |
2518 | struct task_struct *tsk = current; | |
f0bc0a60 | 2519 | |
1da177e4 LT |
2520 | struct reclaim_state reclaim_state = { |
2521 | .reclaimed_slab = 0, | |
2522 | }; | |
a70f7302 | 2523 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2524 | |
cf40bd16 NP |
2525 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2526 | ||
174596a0 | 2527 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2528 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2529 | current->reclaim_state = &reclaim_state; |
2530 | ||
2531 | /* | |
2532 | * Tell the memory management that we're a "memory allocator", | |
2533 | * and that if we need more memory we should get access to it | |
2534 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2535 | * never get caught in the normal page freeing logic. | |
2536 | * | |
2537 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2538 | * you need a small amount of memory in order to be able to | |
2539 | * page out something else, and this flag essentially protects | |
2540 | * us from recursively trying to free more memory as we're | |
2541 | * trying to free the first piece of memory in the first place). | |
2542 | */ | |
930d9152 | 2543 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2544 | set_freezable(); |
1da177e4 LT |
2545 | |
2546 | order = 0; | |
2547 | for ( ; ; ) { | |
2548 | unsigned long new_order; | |
8fe23e05 | 2549 | int ret; |
3e1d1d28 | 2550 | |
1da177e4 LT |
2551 | new_order = pgdat->kswapd_max_order; |
2552 | pgdat->kswapd_max_order = 0; | |
2553 | if (order < new_order) { | |
2554 | /* | |
2555 | * Don't sleep if someone wants a larger 'order' | |
2556 | * allocation | |
2557 | */ | |
2558 | order = new_order; | |
2559 | } else { | |
f0bc0a60 | 2560 | kswapd_try_to_sleep(pgdat, order); |
1da177e4 LT |
2561 | order = pgdat->kswapd_max_order; |
2562 | } | |
1da177e4 | 2563 | |
8fe23e05 DR |
2564 | ret = try_to_freeze(); |
2565 | if (kthread_should_stop()) | |
2566 | break; | |
2567 | ||
2568 | /* | |
2569 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2570 | * after returning from the refrigerator | |
2571 | */ | |
33906bc5 MG |
2572 | if (!ret) { |
2573 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
b1296cc4 | 2574 | balance_pgdat(pgdat, order); |
33906bc5 | 2575 | } |
1da177e4 LT |
2576 | } |
2577 | return 0; | |
2578 | } | |
2579 | ||
2580 | /* | |
2581 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2582 | */ | |
2583 | void wakeup_kswapd(struct zone *zone, int order) | |
2584 | { | |
2585 | pg_data_t *pgdat; | |
2586 | ||
f3fe6512 | 2587 | if (!populated_zone(zone)) |
1da177e4 LT |
2588 | return; |
2589 | ||
88f5acf8 | 2590 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2591 | return; |
88f5acf8 | 2592 | pgdat = zone->zone_pgdat; |
1da177e4 LT |
2593 | if (pgdat->kswapd_max_order < order) |
2594 | pgdat->kswapd_max_order = order; | |
8d0986e2 | 2595 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2596 | return; |
88f5acf8 MG |
2597 | if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0)) |
2598 | return; | |
2599 | ||
2600 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 2601 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2602 | } |
2603 | ||
adea02a1 WF |
2604 | /* |
2605 | * The reclaimable count would be mostly accurate. | |
2606 | * The less reclaimable pages may be | |
2607 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2608 | * - mapped pages, which may require several travels to be reclaimed | |
2609 | * - dirty pages, which is not "instantly" reclaimable | |
2610 | */ | |
2611 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2612 | { |
adea02a1 WF |
2613 | int nr; |
2614 | ||
2615 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2616 | global_page_state(NR_INACTIVE_FILE); | |
2617 | ||
2618 | if (nr_swap_pages > 0) | |
2619 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2620 | global_page_state(NR_INACTIVE_ANON); | |
2621 | ||
2622 | return nr; | |
2623 | } | |
2624 | ||
2625 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2626 | { | |
2627 | int nr; | |
2628 | ||
2629 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2630 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2631 | ||
2632 | if (nr_swap_pages > 0) | |
2633 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2634 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2635 | ||
2636 | return nr; | |
4f98a2fe RR |
2637 | } |
2638 | ||
c6f37f12 | 2639 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2640 | /* |
7b51755c | 2641 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2642 | * freed pages. |
2643 | * | |
2644 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2645 | * LRU order by reclaiming preferentially | |
2646 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2647 | */ |
7b51755c | 2648 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2649 | { |
d6277db4 | 2650 | struct reclaim_state reclaim_state; |
d6277db4 | 2651 | struct scan_control sc = { |
7b51755c KM |
2652 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2653 | .may_swap = 1, | |
2654 | .may_unmap = 1, | |
d6277db4 | 2655 | .may_writepage = 1, |
7b51755c KM |
2656 | .nr_to_reclaim = nr_to_reclaim, |
2657 | .hibernation_mode = 1, | |
2658 | .swappiness = vm_swappiness, | |
2659 | .order = 0, | |
1da177e4 | 2660 | }; |
7b51755c KM |
2661 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2662 | struct task_struct *p = current; | |
2663 | unsigned long nr_reclaimed; | |
1da177e4 | 2664 | |
7b51755c KM |
2665 | p->flags |= PF_MEMALLOC; |
2666 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2667 | reclaim_state.reclaimed_slab = 0; | |
2668 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2669 | |
7b51755c | 2670 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2671 | |
7b51755c KM |
2672 | p->reclaim_state = NULL; |
2673 | lockdep_clear_current_reclaim_state(); | |
2674 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2675 | |
7b51755c | 2676 | return nr_reclaimed; |
1da177e4 | 2677 | } |
c6f37f12 | 2678 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2679 | |
1da177e4 LT |
2680 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2681 | not required for correctness. So if the last cpu in a node goes | |
2682 | away, we get changed to run anywhere: as the first one comes back, | |
2683 | restore their cpu bindings. */ | |
9c7b216d | 2684 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2685 | unsigned long action, void *hcpu) |
1da177e4 | 2686 | { |
58c0a4a7 | 2687 | int nid; |
1da177e4 | 2688 | |
8bb78442 | 2689 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2690 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2691 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2692 | const struct cpumask *mask; |
2693 | ||
2694 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2695 | |
3e597945 | 2696 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2697 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2698 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2699 | } |
2700 | } | |
2701 | return NOTIFY_OK; | |
2702 | } | |
1da177e4 | 2703 | |
3218ae14 YG |
2704 | /* |
2705 | * This kswapd start function will be called by init and node-hot-add. | |
2706 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2707 | */ | |
2708 | int kswapd_run(int nid) | |
2709 | { | |
2710 | pg_data_t *pgdat = NODE_DATA(nid); | |
2711 | int ret = 0; | |
2712 | ||
2713 | if (pgdat->kswapd) | |
2714 | return 0; | |
2715 | ||
2716 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2717 | if (IS_ERR(pgdat->kswapd)) { | |
2718 | /* failure at boot is fatal */ | |
2719 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2720 | printk("Failed to start kswapd on node %d\n",nid); | |
2721 | ret = -1; | |
2722 | } | |
2723 | return ret; | |
2724 | } | |
2725 | ||
8fe23e05 DR |
2726 | /* |
2727 | * Called by memory hotplug when all memory in a node is offlined. | |
2728 | */ | |
2729 | void kswapd_stop(int nid) | |
2730 | { | |
2731 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2732 | ||
2733 | if (kswapd) | |
2734 | kthread_stop(kswapd); | |
2735 | } | |
2736 | ||
1da177e4 LT |
2737 | static int __init kswapd_init(void) |
2738 | { | |
3218ae14 | 2739 | int nid; |
69e05944 | 2740 | |
1da177e4 | 2741 | swap_setup(); |
9422ffba | 2742 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2743 | kswapd_run(nid); |
1da177e4 LT |
2744 | hotcpu_notifier(cpu_callback, 0); |
2745 | return 0; | |
2746 | } | |
2747 | ||
2748 | module_init(kswapd_init) | |
9eeff239 CL |
2749 | |
2750 | #ifdef CONFIG_NUMA | |
2751 | /* | |
2752 | * Zone reclaim mode | |
2753 | * | |
2754 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2755 | * the watermarks. | |
9eeff239 CL |
2756 | */ |
2757 | int zone_reclaim_mode __read_mostly; | |
2758 | ||
1b2ffb78 | 2759 | #define RECLAIM_OFF 0 |
7d03431c | 2760 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2761 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2762 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2763 | ||
a92f7126 CL |
2764 | /* |
2765 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2766 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2767 | * a zone. | |
2768 | */ | |
2769 | #define ZONE_RECLAIM_PRIORITY 4 | |
2770 | ||
9614634f CL |
2771 | /* |
2772 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2773 | * occur. | |
2774 | */ | |
2775 | int sysctl_min_unmapped_ratio = 1; | |
2776 | ||
0ff38490 CL |
2777 | /* |
2778 | * If the number of slab pages in a zone grows beyond this percentage then | |
2779 | * slab reclaim needs to occur. | |
2780 | */ | |
2781 | int sysctl_min_slab_ratio = 5; | |
2782 | ||
90afa5de MG |
2783 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2784 | { | |
2785 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2786 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2787 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2788 | ||
2789 | /* | |
2790 | * It's possible for there to be more file mapped pages than | |
2791 | * accounted for by the pages on the file LRU lists because | |
2792 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2793 | */ | |
2794 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2795 | } | |
2796 | ||
2797 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2798 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2799 | { | |
2800 | long nr_pagecache_reclaimable; | |
2801 | long delta = 0; | |
2802 | ||
2803 | /* | |
2804 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2805 | * potentially reclaimable. Otherwise, we have to worry about | |
2806 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2807 | * a better estimate | |
2808 | */ | |
2809 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2810 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2811 | else | |
2812 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2813 | ||
2814 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2815 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2816 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2817 | ||
2818 | /* Watch for any possible underflows due to delta */ | |
2819 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2820 | delta = nr_pagecache_reclaimable; | |
2821 | ||
2822 | return nr_pagecache_reclaimable - delta; | |
2823 | } | |
2824 | ||
9eeff239 CL |
2825 | /* |
2826 | * Try to free up some pages from this zone through reclaim. | |
2827 | */ | |
179e9639 | 2828 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2829 | { |
7fb2d46d | 2830 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2831 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2832 | struct task_struct *p = current; |
2833 | struct reclaim_state reclaim_state; | |
8695949a | 2834 | int priority; |
179e9639 AM |
2835 | struct scan_control sc = { |
2836 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2837 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2838 | .may_swap = 1, |
22fba335 KM |
2839 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2840 | SWAP_CLUSTER_MAX), | |
179e9639 | 2841 | .gfp_mask = gfp_mask, |
d6277db4 | 2842 | .swappiness = vm_swappiness, |
bd2f6199 | 2843 | .order = order, |
179e9639 | 2844 | }; |
15748048 | 2845 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 2846 | |
9eeff239 | 2847 | cond_resched(); |
d4f7796e CL |
2848 | /* |
2849 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2850 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2851 | * and RECLAIM_SWAP. | |
2852 | */ | |
2853 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2854 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2855 | reclaim_state.reclaimed_slab = 0; |
2856 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2857 | |
90afa5de | 2858 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2859 | /* |
2860 | * Free memory by calling shrink zone with increasing | |
2861 | * priorities until we have enough memory freed. | |
2862 | */ | |
2863 | priority = ZONE_RECLAIM_PRIORITY; | |
2864 | do { | |
a79311c1 | 2865 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2866 | priority--; |
a79311c1 | 2867 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2868 | } |
c84db23c | 2869 | |
15748048 KM |
2870 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2871 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 2872 | /* |
7fb2d46d | 2873 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2874 | * many pages were freed in this zone. So we take the current |
2875 | * number of slab pages and shake the slab until it is reduced | |
2876 | * by the same nr_pages that we used for reclaiming unmapped | |
2877 | * pages. | |
2a16e3f4 | 2878 | * |
0ff38490 CL |
2879 | * Note that shrink_slab will free memory on all zones and may |
2880 | * take a long time. | |
2a16e3f4 | 2881 | */ |
4dc4b3d9 KM |
2882 | for (;;) { |
2883 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
2884 | ||
2885 | /* No reclaimable slab or very low memory pressure */ | |
2886 | if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages)) | |
2887 | break; | |
2888 | ||
2889 | /* Freed enough memory */ | |
2890 | nr_slab_pages1 = zone_page_state(zone, | |
2891 | NR_SLAB_RECLAIMABLE); | |
2892 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
2893 | break; | |
2894 | } | |
83e33a47 CL |
2895 | |
2896 | /* | |
2897 | * Update nr_reclaimed by the number of slab pages we | |
2898 | * reclaimed from this zone. | |
2899 | */ | |
15748048 KM |
2900 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2901 | if (nr_slab_pages1 < nr_slab_pages0) | |
2902 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
2903 | } |
2904 | ||
9eeff239 | 2905 | p->reclaim_state = NULL; |
d4f7796e | 2906 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 2907 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 2908 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2909 | } |
179e9639 AM |
2910 | |
2911 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2912 | { | |
179e9639 | 2913 | int node_id; |
d773ed6b | 2914 | int ret; |
179e9639 AM |
2915 | |
2916 | /* | |
0ff38490 CL |
2917 | * Zone reclaim reclaims unmapped file backed pages and |
2918 | * slab pages if we are over the defined limits. | |
34aa1330 | 2919 | * |
9614634f CL |
2920 | * A small portion of unmapped file backed pages is needed for |
2921 | * file I/O otherwise pages read by file I/O will be immediately | |
2922 | * thrown out if the zone is overallocated. So we do not reclaim | |
2923 | * if less than a specified percentage of the zone is used by | |
2924 | * unmapped file backed pages. | |
179e9639 | 2925 | */ |
90afa5de MG |
2926 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2927 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 2928 | return ZONE_RECLAIM_FULL; |
179e9639 | 2929 | |
93e4a89a | 2930 | if (zone->all_unreclaimable) |
fa5e084e | 2931 | return ZONE_RECLAIM_FULL; |
d773ed6b | 2932 | |
179e9639 | 2933 | /* |
d773ed6b | 2934 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2935 | */ |
d773ed6b | 2936 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 2937 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
2938 | |
2939 | /* | |
2940 | * Only run zone reclaim on the local zone or on zones that do not | |
2941 | * have associated processors. This will favor the local processor | |
2942 | * over remote processors and spread off node memory allocations | |
2943 | * as wide as possible. | |
2944 | */ | |
89fa3024 | 2945 | node_id = zone_to_nid(zone); |
37c0708d | 2946 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 2947 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
2948 | |
2949 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
2950 | return ZONE_RECLAIM_NOSCAN; |
2951 | ||
d773ed6b DR |
2952 | ret = __zone_reclaim(zone, gfp_mask, order); |
2953 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2954 | ||
24cf7251 MG |
2955 | if (!ret) |
2956 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
2957 | ||
d773ed6b | 2958 | return ret; |
179e9639 | 2959 | } |
9eeff239 | 2960 | #endif |
894bc310 | 2961 | |
894bc310 LS |
2962 | /* |
2963 | * page_evictable - test whether a page is evictable | |
2964 | * @page: the page to test | |
2965 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2966 | * | |
2967 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2968 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2969 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2970 | * |
2971 | * Reasons page might not be evictable: | |
ba9ddf49 | 2972 | * (1) page's mapping marked unevictable |
b291f000 | 2973 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2974 | * |
894bc310 LS |
2975 | */ |
2976 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2977 | { | |
2978 | ||
ba9ddf49 LS |
2979 | if (mapping_unevictable(page_mapping(page))) |
2980 | return 0; | |
2981 | ||
b291f000 NP |
2982 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2983 | return 0; | |
894bc310 LS |
2984 | |
2985 | return 1; | |
2986 | } | |
89e004ea LS |
2987 | |
2988 | /** | |
2989 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2990 | * @page: page to check evictability and move to appropriate lru list | |
2991 | * @zone: zone page is in | |
2992 | * | |
2993 | * Checks a page for evictability and moves the page to the appropriate | |
2994 | * zone lru list. | |
2995 | * | |
2996 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2997 | * have PageUnevictable set. | |
2998 | */ | |
2999 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
3000 | { | |
3001 | VM_BUG_ON(PageActive(page)); | |
3002 | ||
3003 | retry: | |
3004 | ClearPageUnevictable(page); | |
3005 | if (page_evictable(page, NULL)) { | |
401a8e1c | 3006 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 3007 | |
89e004ea LS |
3008 | __dec_zone_state(zone, NR_UNEVICTABLE); |
3009 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 3010 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
3011 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
3012 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
3013 | } else { | |
3014 | /* | |
3015 | * rotate unevictable list | |
3016 | */ | |
3017 | SetPageUnevictable(page); | |
3018 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 3019 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
3020 | if (page_evictable(page, NULL)) |
3021 | goto retry; | |
3022 | } | |
3023 | } | |
3024 | ||
3025 | /** | |
3026 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
3027 | * @mapping: struct address_space to scan for evictable pages | |
3028 | * | |
3029 | * Scan all pages in mapping. Check unevictable pages for | |
3030 | * evictability and move them to the appropriate zone lru list. | |
3031 | */ | |
3032 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
3033 | { | |
3034 | pgoff_t next = 0; | |
3035 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
3036 | PAGE_CACHE_SHIFT; | |
3037 | struct zone *zone; | |
3038 | struct pagevec pvec; | |
3039 | ||
3040 | if (mapping->nrpages == 0) | |
3041 | return; | |
3042 | ||
3043 | pagevec_init(&pvec, 0); | |
3044 | while (next < end && | |
3045 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
3046 | int i; | |
3047 | int pg_scanned = 0; | |
3048 | ||
3049 | zone = NULL; | |
3050 | ||
3051 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
3052 | struct page *page = pvec.pages[i]; | |
3053 | pgoff_t page_index = page->index; | |
3054 | struct zone *pagezone = page_zone(page); | |
3055 | ||
3056 | pg_scanned++; | |
3057 | if (page_index > next) | |
3058 | next = page_index; | |
3059 | next++; | |
3060 | ||
3061 | if (pagezone != zone) { | |
3062 | if (zone) | |
3063 | spin_unlock_irq(&zone->lru_lock); | |
3064 | zone = pagezone; | |
3065 | spin_lock_irq(&zone->lru_lock); | |
3066 | } | |
3067 | ||
3068 | if (PageLRU(page) && PageUnevictable(page)) | |
3069 | check_move_unevictable_page(page, zone); | |
3070 | } | |
3071 | if (zone) | |
3072 | spin_unlock_irq(&zone->lru_lock); | |
3073 | pagevec_release(&pvec); | |
3074 | ||
3075 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
3076 | } | |
3077 | ||
3078 | } | |
af936a16 LS |
3079 | |
3080 | /** | |
3081 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
3082 | * @zone - zone of which to scan the unevictable list | |
3083 | * | |
3084 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
3085 | * evictable. Move those that have to @zone's inactive list where they | |
3086 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
3087 | * to reactivate them. Pages that are still unevictable are rotated | |
3088 | * back onto @zone's unevictable list. | |
3089 | */ | |
3090 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 3091 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
3092 | { |
3093 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
3094 | unsigned long scan; | |
3095 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
3096 | ||
3097 | while (nr_to_scan > 0) { | |
3098 | unsigned long batch_size = min(nr_to_scan, | |
3099 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
3100 | ||
3101 | spin_lock_irq(&zone->lru_lock); | |
3102 | for (scan = 0; scan < batch_size; scan++) { | |
3103 | struct page *page = lru_to_page(l_unevictable); | |
3104 | ||
3105 | if (!trylock_page(page)) | |
3106 | continue; | |
3107 | ||
3108 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3109 | ||
3110 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3111 | check_move_unevictable_page(page, zone); | |
3112 | ||
3113 | unlock_page(page); | |
3114 | } | |
3115 | spin_unlock_irq(&zone->lru_lock); | |
3116 | ||
3117 | nr_to_scan -= batch_size; | |
3118 | } | |
3119 | } | |
3120 | ||
3121 | ||
3122 | /** | |
3123 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3124 | * | |
3125 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3126 | * pages that have become evictable. Move those back to the zones' | |
3127 | * inactive list where they become candidates for reclaim. | |
3128 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3129 | * and we add swap to the system. As such, it runs in the context of a task | |
3130 | * that has possibly/probably made some previously unevictable pages | |
3131 | * evictable. | |
3132 | */ | |
ff30153b | 3133 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3134 | { |
3135 | struct zone *zone; | |
3136 | ||
3137 | for_each_zone(zone) { | |
3138 | scan_zone_unevictable_pages(zone); | |
3139 | } | |
3140 | } | |
3141 | ||
3142 | /* | |
3143 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3144 | * all nodes' unevictable lists for evictable pages | |
3145 | */ | |
3146 | unsigned long scan_unevictable_pages; | |
3147 | ||
3148 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3149 | void __user *buffer, |
af936a16 LS |
3150 | size_t *length, loff_t *ppos) |
3151 | { | |
8d65af78 | 3152 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3153 | |
3154 | if (write && *(unsigned long *)table->data) | |
3155 | scan_all_zones_unevictable_pages(); | |
3156 | ||
3157 | scan_unevictable_pages = 0; | |
3158 | return 0; | |
3159 | } | |
3160 | ||
e4455abb | 3161 | #ifdef CONFIG_NUMA |
af936a16 LS |
3162 | /* |
3163 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3164 | * a specified node's per zone unevictable lists for evictable pages. | |
3165 | */ | |
3166 | ||
3167 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3168 | struct sysdev_attribute *attr, | |
3169 | char *buf) | |
3170 | { | |
3171 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3172 | } | |
3173 | ||
3174 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3175 | struct sysdev_attribute *attr, | |
3176 | const char *buf, size_t count) | |
3177 | { | |
3178 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3179 | struct zone *zone; | |
3180 | unsigned long res; | |
3181 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3182 | ||
3183 | if (!req) | |
3184 | return 1; /* zero is no-op */ | |
3185 | ||
3186 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3187 | if (!populated_zone(zone)) | |
3188 | continue; | |
3189 | scan_zone_unevictable_pages(zone); | |
3190 | } | |
3191 | return 1; | |
3192 | } | |
3193 | ||
3194 | ||
3195 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3196 | read_scan_unevictable_node, | |
3197 | write_scan_unevictable_node); | |
3198 | ||
3199 | int scan_unevictable_register_node(struct node *node) | |
3200 | { | |
3201 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3202 | } | |
3203 | ||
3204 | void scan_unevictable_unregister_node(struct node *node) | |
3205 | { | |
3206 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3207 | } | |
e4455abb | 3208 | #endif |