Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
17 | #include <linux/kernel_stat.h> |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
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> |
929bea7c | 44 | #include <linux/oom.h> |
268bb0ce | 45 | #include <linux/prefetch.h> |
1da177e4 LT |
46 | |
47 | #include <asm/tlbflush.h> | |
48 | #include <asm/div64.h> | |
49 | ||
50 | #include <linux/swapops.h> | |
51 | ||
0f8053a5 NP |
52 | #include "internal.h" |
53 | ||
33906bc5 MG |
54 | #define CREATE_TRACE_POINTS |
55 | #include <trace/events/vmscan.h> | |
56 | ||
ee64fc93 | 57 | /* |
f3a310bc MG |
58 | * reclaim_mode determines how the inactive list is shrunk |
59 | * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages | |
60 | * RECLAIM_MODE_ASYNC: Do not block | |
61 | * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback | |
62 | * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference | |
ee64fc93 MG |
63 | * page from the LRU and reclaim all pages within a |
64 | * naturally aligned range | |
f3a310bc | 65 | * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of |
3e7d3449 | 66 | * order-0 pages and then compact the zone |
ee64fc93 | 67 | */ |
f3a310bc MG |
68 | typedef unsigned __bitwise__ reclaim_mode_t; |
69 | #define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u) | |
70 | #define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u) | |
71 | #define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u) | |
72 | #define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u) | |
73 | #define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u) | |
7d3579e8 | 74 | |
1da177e4 | 75 | struct scan_control { |
1da177e4 LT |
76 | /* Incremented by the number of inactive pages that were scanned */ |
77 | unsigned long nr_scanned; | |
78 | ||
a79311c1 RR |
79 | /* Number of pages freed so far during a call to shrink_zones() */ |
80 | unsigned long nr_reclaimed; | |
81 | ||
22fba335 KM |
82 | /* How many pages shrink_list() should reclaim */ |
83 | unsigned long nr_to_reclaim; | |
84 | ||
7b51755c KM |
85 | unsigned long hibernation_mode; |
86 | ||
1da177e4 | 87 | /* This context's GFP mask */ |
6daa0e28 | 88 | gfp_t gfp_mask; |
1da177e4 LT |
89 | |
90 | int may_writepage; | |
91 | ||
a6dc60f8 JW |
92 | /* Can mapped pages be reclaimed? */ |
93 | int may_unmap; | |
f1fd1067 | 94 | |
2e2e4259 KM |
95 | /* Can pages be swapped as part of reclaim? */ |
96 | int may_swap; | |
97 | ||
d6277db4 | 98 | int swappiness; |
408d8544 | 99 | |
5ad333eb | 100 | int order; |
66e1707b | 101 | |
5f53e762 | 102 | /* |
415b54e3 NK |
103 | * Intend to reclaim enough continuous memory rather than reclaim |
104 | * enough amount of memory. i.e, mode for high order allocation. | |
5f53e762 | 105 | */ |
f3a310bc | 106 | reclaim_mode_t reclaim_mode; |
5f53e762 | 107 | |
66e1707b BS |
108 | /* Which cgroup do we reclaim from */ |
109 | struct mem_cgroup *mem_cgroup; | |
110 | ||
327c0e96 KH |
111 | /* |
112 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
113 | * are scanned. | |
114 | */ | |
115 | nodemask_t *nodemask; | |
1da177e4 LT |
116 | }; |
117 | ||
1da177e4 LT |
118 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
119 | ||
120 | #ifdef ARCH_HAS_PREFETCH | |
121 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
122 | do { \ | |
123 | if ((_page)->lru.prev != _base) { \ | |
124 | struct page *prev; \ | |
125 | \ | |
126 | prev = lru_to_page(&(_page->lru)); \ | |
127 | prefetch(&prev->_field); \ | |
128 | } \ | |
129 | } while (0) | |
130 | #else | |
131 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
132 | #endif | |
133 | ||
134 | #ifdef ARCH_HAS_PREFETCHW | |
135 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
136 | do { \ | |
137 | if ((_page)->lru.prev != _base) { \ | |
138 | struct page *prev; \ | |
139 | \ | |
140 | prev = lru_to_page(&(_page->lru)); \ | |
141 | prefetchw(&prev->_field); \ | |
142 | } \ | |
143 | } while (0) | |
144 | #else | |
145 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
146 | #endif | |
147 | ||
148 | /* | |
149 | * From 0 .. 100. Higher means more swappy. | |
150 | */ | |
151 | int vm_swappiness = 60; | |
bd1e22b8 | 152 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
153 | |
154 | static LIST_HEAD(shrinker_list); | |
155 | static DECLARE_RWSEM(shrinker_rwsem); | |
156 | ||
00f0b825 | 157 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 158 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 159 | #else |
e72e2bd6 | 160 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
161 | #endif |
162 | ||
6e901571 KM |
163 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
164 | struct scan_control *sc) | |
165 | { | |
e72e2bd6 | 166 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
167 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
168 | ||
6e901571 KM |
169 | return &zone->reclaim_stat; |
170 | } | |
171 | ||
0b217676 VL |
172 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
173 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 174 | { |
e72e2bd6 | 175 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
176 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
177 | ||
c9f299d9 KM |
178 | return zone_page_state(zone, NR_LRU_BASE + lru); |
179 | } | |
180 | ||
181 | ||
1da177e4 LT |
182 | /* |
183 | * Add a shrinker callback to be called from the vm | |
184 | */ | |
8e1f936b | 185 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 186 | { |
8e1f936b RR |
187 | shrinker->nr = 0; |
188 | down_write(&shrinker_rwsem); | |
189 | list_add_tail(&shrinker->list, &shrinker_list); | |
190 | up_write(&shrinker_rwsem); | |
1da177e4 | 191 | } |
8e1f936b | 192 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
193 | |
194 | /* | |
195 | * Remove one | |
196 | */ | |
8e1f936b | 197 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
198 | { |
199 | down_write(&shrinker_rwsem); | |
200 | list_del(&shrinker->list); | |
201 | up_write(&shrinker_rwsem); | |
1da177e4 | 202 | } |
8e1f936b | 203 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
204 | |
205 | #define SHRINK_BATCH 128 | |
206 | /* | |
207 | * Call the shrink functions to age shrinkable caches | |
208 | * | |
209 | * Here we assume it costs one seek to replace a lru page and that it also | |
210 | * takes a seek to recreate a cache object. With this in mind we age equal | |
211 | * percentages of the lru and ageable caches. This should balance the seeks | |
212 | * generated by these structures. | |
213 | * | |
183ff22b | 214 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
215 | * slab to avoid swapping. |
216 | * | |
217 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
218 | * | |
219 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
220 | * are eligible for the caller's allocation attempt. It is used for balancing | |
221 | * slab reclaim versus page reclaim. | |
b15e0905 | 222 | * |
223 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 224 | */ |
69e05944 AM |
225 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
226 | unsigned long lru_pages) | |
1da177e4 LT |
227 | { |
228 | struct shrinker *shrinker; | |
69e05944 | 229 | unsigned long ret = 0; |
1da177e4 LT |
230 | |
231 | if (scanned == 0) | |
232 | scanned = SWAP_CLUSTER_MAX; | |
233 | ||
f06590bd MK |
234 | if (!down_read_trylock(&shrinker_rwsem)) { |
235 | /* Assume we'll be able to shrink next time */ | |
236 | ret = 1; | |
237 | goto out; | |
238 | } | |
1da177e4 LT |
239 | |
240 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
241 | unsigned long long delta; | |
242 | unsigned long total_scan; | |
7f8275d0 | 243 | unsigned long max_pass; |
1da177e4 | 244 | |
7f8275d0 | 245 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 246 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 247 | delta *= max_pass; |
1da177e4 LT |
248 | do_div(delta, lru_pages + 1); |
249 | shrinker->nr += delta; | |
ea164d73 | 250 | if (shrinker->nr < 0) { |
88c3bd70 DR |
251 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
252 | "delete nr=%ld\n", | |
253 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
254 | shrinker->nr = max_pass; |
255 | } | |
256 | ||
257 | /* | |
258 | * Avoid risking looping forever due to too large nr value: | |
259 | * never try to free more than twice the estimate number of | |
260 | * freeable entries. | |
261 | */ | |
262 | if (shrinker->nr > max_pass * 2) | |
263 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
264 | |
265 | total_scan = shrinker->nr; | |
266 | shrinker->nr = 0; | |
267 | ||
268 | while (total_scan >= SHRINK_BATCH) { | |
269 | long this_scan = SHRINK_BATCH; | |
270 | int shrink_ret; | |
b15e0905 | 271 | int nr_before; |
1da177e4 | 272 | |
7f8275d0 DC |
273 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
274 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
275 | gfp_mask); | |
1da177e4 LT |
276 | if (shrink_ret == -1) |
277 | break; | |
b15e0905 | 278 | if (shrink_ret < nr_before) |
279 | ret += nr_before - shrink_ret; | |
f8891e5e | 280 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
281 | total_scan -= this_scan; |
282 | ||
283 | cond_resched(); | |
284 | } | |
285 | ||
286 | shrinker->nr += total_scan; | |
287 | } | |
288 | up_read(&shrinker_rwsem); | |
f06590bd MK |
289 | out: |
290 | cond_resched(); | |
b15e0905 | 291 | return ret; |
1da177e4 LT |
292 | } |
293 | ||
f3a310bc | 294 | static void set_reclaim_mode(int priority, struct scan_control *sc, |
7d3579e8 KM |
295 | bool sync) |
296 | { | |
f3a310bc | 297 | reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
298 | |
299 | /* | |
3e7d3449 MG |
300 | * Initially assume we are entering either lumpy reclaim or |
301 | * reclaim/compaction.Depending on the order, we will either set the | |
302 | * sync mode or just reclaim order-0 pages later. | |
7d3579e8 | 303 | */ |
3e7d3449 | 304 | if (COMPACTION_BUILD) |
f3a310bc | 305 | sc->reclaim_mode = RECLAIM_MODE_COMPACTION; |
3e7d3449 | 306 | else |
f3a310bc | 307 | sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM; |
7d3579e8 KM |
308 | |
309 | /* | |
3e7d3449 MG |
310 | * Avoid using lumpy reclaim or reclaim/compaction if possible by |
311 | * restricting when its set to either costly allocations or when | |
312 | * under memory pressure | |
7d3579e8 KM |
313 | */ |
314 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
f3a310bc | 315 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 316 | else if (sc->order && priority < DEF_PRIORITY - 2) |
f3a310bc | 317 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 318 | else |
f3a310bc | 319 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
320 | } |
321 | ||
f3a310bc | 322 | static void reset_reclaim_mode(struct scan_control *sc) |
7d3579e8 | 323 | { |
f3a310bc | 324 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
325 | } |
326 | ||
1da177e4 LT |
327 | static inline int is_page_cache_freeable(struct page *page) |
328 | { | |
ceddc3a5 JW |
329 | /* |
330 | * A freeable page cache page is referenced only by the caller | |
331 | * that isolated the page, the page cache radix tree and | |
332 | * optional buffer heads at page->private. | |
333 | */ | |
edcf4748 | 334 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
335 | } |
336 | ||
7d3579e8 KM |
337 | static int may_write_to_queue(struct backing_dev_info *bdi, |
338 | struct scan_control *sc) | |
1da177e4 | 339 | { |
930d9152 | 340 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
341 | return 1; |
342 | if (!bdi_write_congested(bdi)) | |
343 | return 1; | |
344 | if (bdi == current->backing_dev_info) | |
345 | return 1; | |
7d3579e8 KM |
346 | |
347 | /* lumpy reclaim for hugepage often need a lot of write */ | |
348 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
349 | return 1; | |
1da177e4 LT |
350 | return 0; |
351 | } | |
352 | ||
353 | /* | |
354 | * We detected a synchronous write error writing a page out. Probably | |
355 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
356 | * fsync(), msync() or close(). | |
357 | * | |
358 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
359 | * prevents it from being freed up. But we have a ref on the page and once | |
360 | * that page is locked, the mapping is pinned. | |
361 | * | |
362 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
363 | * __GFP_FS. | |
364 | */ | |
365 | static void handle_write_error(struct address_space *mapping, | |
366 | struct page *page, int error) | |
367 | { | |
7eaceacc | 368 | lock_page(page); |
3e9f45bd GC |
369 | if (page_mapping(page) == mapping) |
370 | mapping_set_error(mapping, error); | |
1da177e4 LT |
371 | unlock_page(page); |
372 | } | |
373 | ||
04e62a29 CL |
374 | /* possible outcome of pageout() */ |
375 | typedef enum { | |
376 | /* failed to write page out, page is locked */ | |
377 | PAGE_KEEP, | |
378 | /* move page to the active list, page is locked */ | |
379 | PAGE_ACTIVATE, | |
380 | /* page has been sent to the disk successfully, page is unlocked */ | |
381 | PAGE_SUCCESS, | |
382 | /* page is clean and locked */ | |
383 | PAGE_CLEAN, | |
384 | } pageout_t; | |
385 | ||
1da177e4 | 386 | /* |
1742f19f AM |
387 | * pageout is called by shrink_page_list() for each dirty page. |
388 | * Calls ->writepage(). | |
1da177e4 | 389 | */ |
c661b078 | 390 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 391 | struct scan_control *sc) |
1da177e4 LT |
392 | { |
393 | /* | |
394 | * If the page is dirty, only perform writeback if that write | |
395 | * will be non-blocking. To prevent this allocation from being | |
396 | * stalled by pagecache activity. But note that there may be | |
397 | * stalls if we need to run get_block(). We could test | |
398 | * PagePrivate for that. | |
399 | * | |
6aceb53b | 400 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
401 | * this page's queue, we can perform writeback even if that |
402 | * will block. | |
403 | * | |
404 | * If the page is swapcache, write it back even if that would | |
405 | * block, for some throttling. This happens by accident, because | |
406 | * swap_backing_dev_info is bust: it doesn't reflect the | |
407 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
408 | */ |
409 | if (!is_page_cache_freeable(page)) | |
410 | return PAGE_KEEP; | |
411 | if (!mapping) { | |
412 | /* | |
413 | * Some data journaling orphaned pages can have | |
414 | * page->mapping == NULL while being dirty with clean buffers. | |
415 | */ | |
266cf658 | 416 | if (page_has_private(page)) { |
1da177e4 LT |
417 | if (try_to_free_buffers(page)) { |
418 | ClearPageDirty(page); | |
d40cee24 | 419 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
420 | return PAGE_CLEAN; |
421 | } | |
422 | } | |
423 | return PAGE_KEEP; | |
424 | } | |
425 | if (mapping->a_ops->writepage == NULL) | |
426 | return PAGE_ACTIVATE; | |
0e093d99 | 427 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
428 | return PAGE_KEEP; |
429 | ||
430 | if (clear_page_dirty_for_io(page)) { | |
431 | int res; | |
432 | struct writeback_control wbc = { | |
433 | .sync_mode = WB_SYNC_NONE, | |
434 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
435 | .range_start = 0, |
436 | .range_end = LLONG_MAX, | |
1da177e4 LT |
437 | .for_reclaim = 1, |
438 | }; | |
439 | ||
440 | SetPageReclaim(page); | |
441 | res = mapping->a_ops->writepage(page, &wbc); | |
442 | if (res < 0) | |
443 | handle_write_error(mapping, page, res); | |
994fc28c | 444 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
445 | ClearPageReclaim(page); |
446 | return PAGE_ACTIVATE; | |
447 | } | |
c661b078 AW |
448 | |
449 | /* | |
450 | * Wait on writeback if requested to. This happens when | |
451 | * direct reclaiming a large contiguous area and the | |
452 | * first attempt to free a range of pages fails. | |
453 | */ | |
7d3579e8 | 454 | if (PageWriteback(page) && |
f3a310bc | 455 | (sc->reclaim_mode & RECLAIM_MODE_SYNC)) |
c661b078 AW |
456 | wait_on_page_writeback(page); |
457 | ||
1da177e4 LT |
458 | if (!PageWriteback(page)) { |
459 | /* synchronous write or broken a_ops? */ | |
460 | ClearPageReclaim(page); | |
461 | } | |
755f0225 | 462 | trace_mm_vmscan_writepage(page, |
f3a310bc | 463 | trace_reclaim_flags(page, sc->reclaim_mode)); |
e129b5c2 | 464 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
465 | return PAGE_SUCCESS; |
466 | } | |
467 | ||
468 | return PAGE_CLEAN; | |
469 | } | |
470 | ||
a649fd92 | 471 | /* |
e286781d NP |
472 | * Same as remove_mapping, but if the page is removed from the mapping, it |
473 | * gets returned with a refcount of 0. | |
a649fd92 | 474 | */ |
e286781d | 475 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 476 | { |
28e4d965 NP |
477 | BUG_ON(!PageLocked(page)); |
478 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 479 | |
19fd6231 | 480 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 481 | /* |
0fd0e6b0 NP |
482 | * The non racy check for a busy page. |
483 | * | |
484 | * Must be careful with the order of the tests. When someone has | |
485 | * a ref to the page, it may be possible that they dirty it then | |
486 | * drop the reference. So if PageDirty is tested before page_count | |
487 | * here, then the following race may occur: | |
488 | * | |
489 | * get_user_pages(&page); | |
490 | * [user mapping goes away] | |
491 | * write_to(page); | |
492 | * !PageDirty(page) [good] | |
493 | * SetPageDirty(page); | |
494 | * put_page(page); | |
495 | * !page_count(page) [good, discard it] | |
496 | * | |
497 | * [oops, our write_to data is lost] | |
498 | * | |
499 | * Reversing the order of the tests ensures such a situation cannot | |
500 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
501 | * load is not satisfied before that of page->_count. | |
502 | * | |
503 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
504 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 505 | */ |
e286781d | 506 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 507 | goto cannot_free; |
e286781d NP |
508 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
509 | if (unlikely(PageDirty(page))) { | |
510 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 511 | goto cannot_free; |
e286781d | 512 | } |
49d2e9cc CL |
513 | |
514 | if (PageSwapCache(page)) { | |
515 | swp_entry_t swap = { .val = page_private(page) }; | |
516 | __delete_from_swap_cache(page); | |
19fd6231 | 517 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 518 | swapcache_free(swap, page); |
e286781d | 519 | } else { |
6072d13c LT |
520 | void (*freepage)(struct page *); |
521 | ||
522 | freepage = mapping->a_ops->freepage; | |
523 | ||
e64a782f | 524 | __delete_from_page_cache(page); |
19fd6231 | 525 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 526 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
527 | |
528 | if (freepage != NULL) | |
529 | freepage(page); | |
49d2e9cc CL |
530 | } |
531 | ||
49d2e9cc CL |
532 | return 1; |
533 | ||
534 | cannot_free: | |
19fd6231 | 535 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
536 | return 0; |
537 | } | |
538 | ||
e286781d NP |
539 | /* |
540 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
541 | * someone else has a ref on the page, abort and return 0. If it was | |
542 | * successfully detached, return 1. Assumes the caller has a single ref on | |
543 | * this page. | |
544 | */ | |
545 | int remove_mapping(struct address_space *mapping, struct page *page) | |
546 | { | |
547 | if (__remove_mapping(mapping, page)) { | |
548 | /* | |
549 | * Unfreezing the refcount with 1 rather than 2 effectively | |
550 | * drops the pagecache ref for us without requiring another | |
551 | * atomic operation. | |
552 | */ | |
553 | page_unfreeze_refs(page, 1); | |
554 | return 1; | |
555 | } | |
556 | return 0; | |
557 | } | |
558 | ||
894bc310 LS |
559 | /** |
560 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
561 | * @page: page to be put back to appropriate lru list | |
562 | * | |
563 | * Add previously isolated @page to appropriate LRU list. | |
564 | * Page may still be unevictable for other reasons. | |
565 | * | |
566 | * lru_lock must not be held, interrupts must be enabled. | |
567 | */ | |
894bc310 LS |
568 | void putback_lru_page(struct page *page) |
569 | { | |
570 | int lru; | |
571 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 572 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
573 | |
574 | VM_BUG_ON(PageLRU(page)); | |
575 | ||
576 | redo: | |
577 | ClearPageUnevictable(page); | |
578 | ||
579 | if (page_evictable(page, NULL)) { | |
580 | /* | |
581 | * For evictable pages, we can use the cache. | |
582 | * In event of a race, worst case is we end up with an | |
583 | * unevictable page on [in]active list. | |
584 | * We know how to handle that. | |
585 | */ | |
401a8e1c | 586 | lru = active + page_lru_base_type(page); |
894bc310 LS |
587 | lru_cache_add_lru(page, lru); |
588 | } else { | |
589 | /* | |
590 | * Put unevictable pages directly on zone's unevictable | |
591 | * list. | |
592 | */ | |
593 | lru = LRU_UNEVICTABLE; | |
594 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
595 | /* |
596 | * When racing with an mlock clearing (page is | |
597 | * unlocked), make sure that if the other thread does | |
598 | * not observe our setting of PG_lru and fails | |
599 | * isolation, we see PG_mlocked cleared below and move | |
600 | * the page back to the evictable list. | |
601 | * | |
602 | * The other side is TestClearPageMlocked(). | |
603 | */ | |
604 | smp_mb(); | |
894bc310 | 605 | } |
894bc310 LS |
606 | |
607 | /* | |
608 | * page's status can change while we move it among lru. If an evictable | |
609 | * page is on unevictable list, it never be freed. To avoid that, | |
610 | * check after we added it to the list, again. | |
611 | */ | |
612 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
613 | if (!isolate_lru_page(page)) { | |
614 | put_page(page); | |
615 | goto redo; | |
616 | } | |
617 | /* This means someone else dropped this page from LRU | |
618 | * So, it will be freed or putback to LRU again. There is | |
619 | * nothing to do here. | |
620 | */ | |
621 | } | |
622 | ||
bbfd28ee LS |
623 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
624 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
625 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
626 | count_vm_event(UNEVICTABLE_PGCULLED); | |
627 | ||
894bc310 LS |
628 | put_page(page); /* drop ref from isolate */ |
629 | } | |
630 | ||
dfc8d636 JW |
631 | enum page_references { |
632 | PAGEREF_RECLAIM, | |
633 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 634 | PAGEREF_KEEP, |
dfc8d636 JW |
635 | PAGEREF_ACTIVATE, |
636 | }; | |
637 | ||
638 | static enum page_references page_check_references(struct page *page, | |
639 | struct scan_control *sc) | |
640 | { | |
64574746 | 641 | int referenced_ptes, referenced_page; |
dfc8d636 | 642 | unsigned long vm_flags; |
dfc8d636 | 643 | |
64574746 JW |
644 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
645 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
646 | |
647 | /* Lumpy reclaim - ignore references */ | |
f3a310bc | 648 | if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) |
dfc8d636 JW |
649 | return PAGEREF_RECLAIM; |
650 | ||
651 | /* | |
652 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
653 | * move the page to the unevictable list. | |
654 | */ | |
655 | if (vm_flags & VM_LOCKED) | |
656 | return PAGEREF_RECLAIM; | |
657 | ||
64574746 JW |
658 | if (referenced_ptes) { |
659 | if (PageAnon(page)) | |
660 | return PAGEREF_ACTIVATE; | |
661 | /* | |
662 | * All mapped pages start out with page table | |
663 | * references from the instantiating fault, so we need | |
664 | * to look twice if a mapped file page is used more | |
665 | * than once. | |
666 | * | |
667 | * Mark it and spare it for another trip around the | |
668 | * inactive list. Another page table reference will | |
669 | * lead to its activation. | |
670 | * | |
671 | * Note: the mark is set for activated pages as well | |
672 | * so that recently deactivated but used pages are | |
673 | * quickly recovered. | |
674 | */ | |
675 | SetPageReferenced(page); | |
676 | ||
677 | if (referenced_page) | |
678 | return PAGEREF_ACTIVATE; | |
679 | ||
680 | return PAGEREF_KEEP; | |
681 | } | |
dfc8d636 JW |
682 | |
683 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 684 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
685 | return PAGEREF_RECLAIM_CLEAN; |
686 | ||
687 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
688 | } |
689 | ||
abe4c3b5 MG |
690 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
691 | { | |
692 | struct pagevec freed_pvec; | |
693 | struct page *page, *tmp; | |
694 | ||
695 | pagevec_init(&freed_pvec, 1); | |
696 | ||
697 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
698 | list_del(&page->lru); | |
699 | if (!pagevec_add(&freed_pvec, page)) { | |
700 | __pagevec_free(&freed_pvec); | |
701 | pagevec_reinit(&freed_pvec); | |
702 | } | |
703 | } | |
704 | ||
705 | pagevec_free(&freed_pvec); | |
706 | } | |
707 | ||
1da177e4 | 708 | /* |
1742f19f | 709 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 710 | */ |
1742f19f | 711 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 712 | struct zone *zone, |
7d3579e8 | 713 | struct scan_control *sc) |
1da177e4 LT |
714 | { |
715 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 716 | LIST_HEAD(free_pages); |
1da177e4 | 717 | int pgactivate = 0; |
0e093d99 MG |
718 | unsigned long nr_dirty = 0; |
719 | unsigned long nr_congested = 0; | |
05ff5137 | 720 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
721 | |
722 | cond_resched(); | |
723 | ||
1da177e4 | 724 | while (!list_empty(page_list)) { |
dfc8d636 | 725 | enum page_references references; |
1da177e4 LT |
726 | struct address_space *mapping; |
727 | struct page *page; | |
728 | int may_enter_fs; | |
1da177e4 LT |
729 | |
730 | cond_resched(); | |
731 | ||
732 | page = lru_to_page(page_list); | |
733 | list_del(&page->lru); | |
734 | ||
529ae9aa | 735 | if (!trylock_page(page)) |
1da177e4 LT |
736 | goto keep; |
737 | ||
725d704e | 738 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 739 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
740 | |
741 | sc->nr_scanned++; | |
80e43426 | 742 | |
b291f000 NP |
743 | if (unlikely(!page_evictable(page, NULL))) |
744 | goto cull_mlocked; | |
894bc310 | 745 | |
a6dc60f8 | 746 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
747 | goto keep_locked; |
748 | ||
1da177e4 LT |
749 | /* Double the slab pressure for mapped and swapcache pages */ |
750 | if (page_mapped(page) || PageSwapCache(page)) | |
751 | sc->nr_scanned++; | |
752 | ||
c661b078 AW |
753 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
754 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
755 | ||
756 | if (PageWriteback(page)) { | |
757 | /* | |
758 | * Synchronous reclaim is performed in two passes, | |
759 | * first an asynchronous pass over the list to | |
760 | * start parallel writeback, and a second synchronous | |
761 | * pass to wait for the IO to complete. Wait here | |
762 | * for any page for which writeback has already | |
763 | * started. | |
764 | */ | |
f3a310bc | 765 | if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && |
7d3579e8 | 766 | may_enter_fs) |
c661b078 | 767 | wait_on_page_writeback(page); |
7d3579e8 KM |
768 | else { |
769 | unlock_page(page); | |
770 | goto keep_lumpy; | |
771 | } | |
c661b078 | 772 | } |
1da177e4 | 773 | |
dfc8d636 JW |
774 | references = page_check_references(page, sc); |
775 | switch (references) { | |
776 | case PAGEREF_ACTIVATE: | |
1da177e4 | 777 | goto activate_locked; |
64574746 JW |
778 | case PAGEREF_KEEP: |
779 | goto keep_locked; | |
dfc8d636 JW |
780 | case PAGEREF_RECLAIM: |
781 | case PAGEREF_RECLAIM_CLEAN: | |
782 | ; /* try to reclaim the page below */ | |
783 | } | |
1da177e4 | 784 | |
1da177e4 LT |
785 | /* |
786 | * Anonymous process memory has backing store? | |
787 | * Try to allocate it some swap space here. | |
788 | */ | |
b291f000 | 789 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
790 | if (!(sc->gfp_mask & __GFP_IO)) |
791 | goto keep_locked; | |
ac47b003 | 792 | if (!add_to_swap(page)) |
1da177e4 | 793 | goto activate_locked; |
63eb6b93 | 794 | may_enter_fs = 1; |
b291f000 | 795 | } |
1da177e4 LT |
796 | |
797 | mapping = page_mapping(page); | |
1da177e4 LT |
798 | |
799 | /* | |
800 | * The page is mapped into the page tables of one or more | |
801 | * processes. Try to unmap it here. | |
802 | */ | |
803 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 804 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
805 | case SWAP_FAIL: |
806 | goto activate_locked; | |
807 | case SWAP_AGAIN: | |
808 | goto keep_locked; | |
b291f000 NP |
809 | case SWAP_MLOCK: |
810 | goto cull_mlocked; | |
1da177e4 LT |
811 | case SWAP_SUCCESS: |
812 | ; /* try to free the page below */ | |
813 | } | |
814 | } | |
815 | ||
816 | if (PageDirty(page)) { | |
0e093d99 MG |
817 | nr_dirty++; |
818 | ||
dfc8d636 | 819 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 820 | goto keep_locked; |
4dd4b920 | 821 | if (!may_enter_fs) |
1da177e4 | 822 | goto keep_locked; |
52a8363e | 823 | if (!sc->may_writepage) |
1da177e4 LT |
824 | goto keep_locked; |
825 | ||
826 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 827 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 828 | case PAGE_KEEP: |
0e093d99 | 829 | nr_congested++; |
1da177e4 LT |
830 | goto keep_locked; |
831 | case PAGE_ACTIVATE: | |
832 | goto activate_locked; | |
833 | case PAGE_SUCCESS: | |
7d3579e8 KM |
834 | if (PageWriteback(page)) |
835 | goto keep_lumpy; | |
836 | if (PageDirty(page)) | |
1da177e4 | 837 | goto keep; |
7d3579e8 | 838 | |
1da177e4 LT |
839 | /* |
840 | * A synchronous write - probably a ramdisk. Go | |
841 | * ahead and try to reclaim the page. | |
842 | */ | |
529ae9aa | 843 | if (!trylock_page(page)) |
1da177e4 LT |
844 | goto keep; |
845 | if (PageDirty(page) || PageWriteback(page)) | |
846 | goto keep_locked; | |
847 | mapping = page_mapping(page); | |
848 | case PAGE_CLEAN: | |
849 | ; /* try to free the page below */ | |
850 | } | |
851 | } | |
852 | ||
853 | /* | |
854 | * If the page has buffers, try to free the buffer mappings | |
855 | * associated with this page. If we succeed we try to free | |
856 | * the page as well. | |
857 | * | |
858 | * We do this even if the page is PageDirty(). | |
859 | * try_to_release_page() does not perform I/O, but it is | |
860 | * possible for a page to have PageDirty set, but it is actually | |
861 | * clean (all its buffers are clean). This happens if the | |
862 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 863 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
864 | * try_to_release_page() will discover that cleanness and will |
865 | * drop the buffers and mark the page clean - it can be freed. | |
866 | * | |
867 | * Rarely, pages can have buffers and no ->mapping. These are | |
868 | * the pages which were not successfully invalidated in | |
869 | * truncate_complete_page(). We try to drop those buffers here | |
870 | * and if that worked, and the page is no longer mapped into | |
871 | * process address space (page_count == 1) it can be freed. | |
872 | * Otherwise, leave the page on the LRU so it is swappable. | |
873 | */ | |
266cf658 | 874 | if (page_has_private(page)) { |
1da177e4 LT |
875 | if (!try_to_release_page(page, sc->gfp_mask)) |
876 | goto activate_locked; | |
e286781d NP |
877 | if (!mapping && page_count(page) == 1) { |
878 | unlock_page(page); | |
879 | if (put_page_testzero(page)) | |
880 | goto free_it; | |
881 | else { | |
882 | /* | |
883 | * rare race with speculative reference. | |
884 | * the speculative reference will free | |
885 | * this page shortly, so we may | |
886 | * increment nr_reclaimed here (and | |
887 | * leave it off the LRU). | |
888 | */ | |
889 | nr_reclaimed++; | |
890 | continue; | |
891 | } | |
892 | } | |
1da177e4 LT |
893 | } |
894 | ||
e286781d | 895 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 896 | goto keep_locked; |
1da177e4 | 897 | |
a978d6f5 NP |
898 | /* |
899 | * At this point, we have no other references and there is | |
900 | * no way to pick any more up (removed from LRU, removed | |
901 | * from pagecache). Can use non-atomic bitops now (and | |
902 | * we obviously don't have to worry about waking up a process | |
903 | * waiting on the page lock, because there are no references. | |
904 | */ | |
905 | __clear_page_locked(page); | |
e286781d | 906 | free_it: |
05ff5137 | 907 | nr_reclaimed++; |
abe4c3b5 MG |
908 | |
909 | /* | |
910 | * Is there need to periodically free_page_list? It would | |
911 | * appear not as the counts should be low | |
912 | */ | |
913 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
914 | continue; |
915 | ||
b291f000 | 916 | cull_mlocked: |
63d6c5ad HD |
917 | if (PageSwapCache(page)) |
918 | try_to_free_swap(page); | |
b291f000 NP |
919 | unlock_page(page); |
920 | putback_lru_page(page); | |
f3a310bc | 921 | reset_reclaim_mode(sc); |
b291f000 NP |
922 | continue; |
923 | ||
1da177e4 | 924 | activate_locked: |
68a22394 RR |
925 | /* Not a candidate for swapping, so reclaim swap space. */ |
926 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 927 | try_to_free_swap(page); |
894bc310 | 928 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
929 | SetPageActive(page); |
930 | pgactivate++; | |
931 | keep_locked: | |
932 | unlock_page(page); | |
933 | keep: | |
f3a310bc | 934 | reset_reclaim_mode(sc); |
7d3579e8 | 935 | keep_lumpy: |
1da177e4 | 936 | list_add(&page->lru, &ret_pages); |
b291f000 | 937 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 938 | } |
abe4c3b5 | 939 | |
0e093d99 MG |
940 | /* |
941 | * Tag a zone as congested if all the dirty pages encountered were | |
942 | * backed by a congested BDI. In this case, reclaimers should just | |
943 | * back off and wait for congestion to clear because further reclaim | |
944 | * will encounter the same problem | |
945 | */ | |
d6c438b6 | 946 | if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc)) |
0e093d99 MG |
947 | zone_set_flag(zone, ZONE_CONGESTED); |
948 | ||
abe4c3b5 MG |
949 | free_page_list(&free_pages); |
950 | ||
1da177e4 | 951 | list_splice(&ret_pages, page_list); |
f8891e5e | 952 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 953 | return nr_reclaimed; |
1da177e4 LT |
954 | } |
955 | ||
5ad333eb AW |
956 | /* |
957 | * Attempt to remove the specified page from its LRU. Only take this page | |
958 | * if it is of the appropriate PageActive status. Pages which are being | |
959 | * freed elsewhere are also ignored. | |
960 | * | |
961 | * page: page to consider | |
962 | * mode: one of the LRU isolation modes defined above | |
963 | * | |
964 | * returns 0 on success, -ve errno on failure. | |
965 | */ | |
4f98a2fe | 966 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
967 | { |
968 | int ret = -EINVAL; | |
969 | ||
970 | /* Only take pages on the LRU. */ | |
971 | if (!PageLRU(page)) | |
972 | return ret; | |
973 | ||
974 | /* | |
975 | * When checking the active state, we need to be sure we are | |
976 | * dealing with comparible boolean values. Take the logical not | |
977 | * of each. | |
978 | */ | |
979 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
980 | return ret; | |
981 | ||
6c0b1351 | 982 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
983 | return ret; |
984 | ||
894bc310 LS |
985 | /* |
986 | * When this function is being called for lumpy reclaim, we | |
987 | * initially look into all LRU pages, active, inactive and | |
988 | * unevictable; only give shrink_page_list evictable pages. | |
989 | */ | |
990 | if (PageUnevictable(page)) | |
991 | return ret; | |
992 | ||
5ad333eb | 993 | ret = -EBUSY; |
08e552c6 | 994 | |
5ad333eb AW |
995 | if (likely(get_page_unless_zero(page))) { |
996 | /* | |
997 | * Be careful not to clear PageLRU until after we're | |
998 | * sure the page is not being freed elsewhere -- the | |
999 | * page release code relies on it. | |
1000 | */ | |
1001 | ClearPageLRU(page); | |
1002 | ret = 0; | |
1003 | } | |
1004 | ||
1005 | return ret; | |
1006 | } | |
1007 | ||
1da177e4 LT |
1008 | /* |
1009 | * zone->lru_lock is heavily contended. Some of the functions that | |
1010 | * shrink the lists perform better by taking out a batch of pages | |
1011 | * and working on them outside the LRU lock. | |
1012 | * | |
1013 | * For pagecache intensive workloads, this function is the hottest | |
1014 | * spot in the kernel (apart from copy_*_user functions). | |
1015 | * | |
1016 | * Appropriate locks must be held before calling this function. | |
1017 | * | |
1018 | * @nr_to_scan: The number of pages to look through on the list. | |
1019 | * @src: The LRU list to pull pages off. | |
1020 | * @dst: The temp list to put pages on to. | |
1021 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
1022 | * @order: The caller's attempted allocation order |
1023 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 1024 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
1025 | * |
1026 | * returns how many pages were moved onto *@dst. | |
1027 | */ | |
69e05944 AM |
1028 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
1029 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1030 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1031 | { |
69e05944 | 1032 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1033 | unsigned long nr_lumpy_taken = 0; |
1034 | unsigned long nr_lumpy_dirty = 0; | |
1035 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1036 | unsigned long scan; |
1da177e4 | 1037 | |
c9b02d97 | 1038 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1039 | struct page *page; |
1040 | unsigned long pfn; | |
1041 | unsigned long end_pfn; | |
1042 | unsigned long page_pfn; | |
1043 | int zone_id; | |
1044 | ||
1da177e4 LT |
1045 | page = lru_to_page(src); |
1046 | prefetchw_prev_lru_page(page, src, flags); | |
1047 | ||
725d704e | 1048 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1049 | |
4f98a2fe | 1050 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1051 | case 0: |
1052 | list_move(&page->lru, dst); | |
2ffebca6 | 1053 | mem_cgroup_del_lru(page); |
2c888cfb | 1054 | nr_taken += hpage_nr_pages(page); |
5ad333eb AW |
1055 | break; |
1056 | ||
1057 | case -EBUSY: | |
1058 | /* else it is being freed elsewhere */ | |
1059 | list_move(&page->lru, src); | |
2ffebca6 | 1060 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1061 | continue; |
46453a6e | 1062 | |
5ad333eb AW |
1063 | default: |
1064 | BUG(); | |
1065 | } | |
1066 | ||
1067 | if (!order) | |
1068 | continue; | |
1069 | ||
1070 | /* | |
1071 | * Attempt to take all pages in the order aligned region | |
1072 | * surrounding the tag page. Only take those pages of | |
1073 | * the same active state as that tag page. We may safely | |
1074 | * round the target page pfn down to the requested order | |
25985edc | 1075 | * as the mem_map is guaranteed valid out to MAX_ORDER, |
5ad333eb AW |
1076 | * where that page is in a different zone we will detect |
1077 | * it from its zone id and abort this block scan. | |
1078 | */ | |
1079 | zone_id = page_zone_id(page); | |
1080 | page_pfn = page_to_pfn(page); | |
1081 | pfn = page_pfn & ~((1 << order) - 1); | |
1082 | end_pfn = pfn + (1 << order); | |
1083 | for (; pfn < end_pfn; pfn++) { | |
1084 | struct page *cursor_page; | |
1085 | ||
1086 | /* The target page is in the block, ignore it. */ | |
1087 | if (unlikely(pfn == page_pfn)) | |
1088 | continue; | |
1089 | ||
1090 | /* Avoid holes within the zone. */ | |
1091 | if (unlikely(!pfn_valid_within(pfn))) | |
1092 | break; | |
1093 | ||
1094 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1095 | |
5ad333eb AW |
1096 | /* Check that we have not crossed a zone boundary. */ |
1097 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1098 | break; |
de2e7567 MK |
1099 | |
1100 | /* | |
1101 | * If we don't have enough swap space, reclaiming of | |
1102 | * anon page which don't already have a swap slot is | |
1103 | * pointless. | |
1104 | */ | |
1105 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1106 | !PageSwapCache(cursor_page)) |
1107 | break; | |
de2e7567 | 1108 | |
ee993b13 | 1109 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1110 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1111 | mem_cgroup_del_lru(cursor_page); |
2c888cfb | 1112 | nr_taken += hpage_nr_pages(page); |
a8a94d15 MG |
1113 | nr_lumpy_taken++; |
1114 | if (PageDirty(cursor_page)) | |
1115 | nr_lumpy_dirty++; | |
5ad333eb | 1116 | scan++; |
a8a94d15 | 1117 | } else { |
08fc468f KM |
1118 | /* the page is freed already. */ |
1119 | if (!page_count(cursor_page)) | |
1120 | continue; | |
1121 | break; | |
5ad333eb AW |
1122 | } |
1123 | } | |
08fc468f KM |
1124 | |
1125 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1126 | if (pfn < end_pfn) | |
1127 | nr_lumpy_failed++; | |
1da177e4 LT |
1128 | } |
1129 | ||
1130 | *scanned = scan; | |
a8a94d15 MG |
1131 | |
1132 | trace_mm_vmscan_lru_isolate(order, | |
1133 | nr_to_scan, scan, | |
1134 | nr_taken, | |
1135 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1136 | mode); | |
1da177e4 LT |
1137 | return nr_taken; |
1138 | } | |
1139 | ||
66e1707b BS |
1140 | static unsigned long isolate_pages_global(unsigned long nr, |
1141 | struct list_head *dst, | |
1142 | unsigned long *scanned, int order, | |
1143 | int mode, struct zone *z, | |
4f98a2fe | 1144 | int active, int file) |
66e1707b | 1145 | { |
4f98a2fe | 1146 | int lru = LRU_BASE; |
66e1707b | 1147 | if (active) |
4f98a2fe RR |
1148 | lru += LRU_ACTIVE; |
1149 | if (file) | |
1150 | lru += LRU_FILE; | |
1151 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1152 | mode, file); |
66e1707b BS |
1153 | } |
1154 | ||
5ad333eb AW |
1155 | /* |
1156 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1157 | * any active bits from the pages in the list. | |
1158 | */ | |
4f98a2fe RR |
1159 | static unsigned long clear_active_flags(struct list_head *page_list, |
1160 | unsigned int *count) | |
5ad333eb AW |
1161 | { |
1162 | int nr_active = 0; | |
4f98a2fe | 1163 | int lru; |
5ad333eb AW |
1164 | struct page *page; |
1165 | ||
4f98a2fe | 1166 | list_for_each_entry(page, page_list, lru) { |
2c888cfb | 1167 | int numpages = hpage_nr_pages(page); |
401a8e1c | 1168 | lru = page_lru_base_type(page); |
5ad333eb | 1169 | if (PageActive(page)) { |
4f98a2fe | 1170 | lru += LRU_ACTIVE; |
5ad333eb | 1171 | ClearPageActive(page); |
2c888cfb | 1172 | nr_active += numpages; |
5ad333eb | 1173 | } |
1489fa14 | 1174 | if (count) |
2c888cfb | 1175 | count[lru] += numpages; |
4f98a2fe | 1176 | } |
5ad333eb AW |
1177 | |
1178 | return nr_active; | |
1179 | } | |
1180 | ||
62695a84 NP |
1181 | /** |
1182 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1183 | * @page: page to isolate from its LRU list | |
1184 | * | |
1185 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1186 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1187 | * | |
1188 | * Returns 0 if the page was removed from an LRU list. | |
1189 | * Returns -EBUSY if the page was not on an LRU list. | |
1190 | * | |
1191 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1192 | * the active list, it will have PageActive set. If it was found on |
1193 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1194 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1195 | * |
1196 | * The vmstat statistic corresponding to the list on which the page was | |
1197 | * found will be decremented. | |
1198 | * | |
1199 | * Restrictions: | |
1200 | * (1) Must be called with an elevated refcount on the page. This is a | |
1201 | * fundamentnal difference from isolate_lru_pages (which is called | |
1202 | * without a stable reference). | |
1203 | * (2) the lru_lock must not be held. | |
1204 | * (3) interrupts must be enabled. | |
1205 | */ | |
1206 | int isolate_lru_page(struct page *page) | |
1207 | { | |
1208 | int ret = -EBUSY; | |
1209 | ||
1210 | if (PageLRU(page)) { | |
1211 | struct zone *zone = page_zone(page); | |
1212 | ||
1213 | spin_lock_irq(&zone->lru_lock); | |
1214 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1215 | int lru = page_lru(page); |
62695a84 NP |
1216 | ret = 0; |
1217 | ClearPageLRU(page); | |
4f98a2fe | 1218 | |
4f98a2fe | 1219 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1220 | } |
1221 | spin_unlock_irq(&zone->lru_lock); | |
1222 | } | |
1223 | return ret; | |
1224 | } | |
1225 | ||
35cd7815 RR |
1226 | /* |
1227 | * Are there way too many processes in the direct reclaim path already? | |
1228 | */ | |
1229 | static int too_many_isolated(struct zone *zone, int file, | |
1230 | struct scan_control *sc) | |
1231 | { | |
1232 | unsigned long inactive, isolated; | |
1233 | ||
1234 | if (current_is_kswapd()) | |
1235 | return 0; | |
1236 | ||
1237 | if (!scanning_global_lru(sc)) | |
1238 | return 0; | |
1239 | ||
1240 | if (file) { | |
1241 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1242 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1243 | } else { | |
1244 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1245 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1246 | } | |
1247 | ||
1248 | return isolated > inactive; | |
1249 | } | |
1250 | ||
66635629 MG |
1251 | /* |
1252 | * TODO: Try merging with migrations version of putback_lru_pages | |
1253 | */ | |
1254 | static noinline_for_stack void | |
1489fa14 | 1255 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1256 | unsigned long nr_anon, unsigned long nr_file, |
1257 | struct list_head *page_list) | |
1258 | { | |
1259 | struct page *page; | |
1260 | struct pagevec pvec; | |
1489fa14 | 1261 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1262 | |
1263 | pagevec_init(&pvec, 1); | |
1264 | ||
1265 | /* | |
1266 | * Put back any unfreeable pages. | |
1267 | */ | |
1268 | spin_lock(&zone->lru_lock); | |
1269 | while (!list_empty(page_list)) { | |
1270 | int lru; | |
1271 | page = lru_to_page(page_list); | |
1272 | VM_BUG_ON(PageLRU(page)); | |
1273 | list_del(&page->lru); | |
1274 | if (unlikely(!page_evictable(page, NULL))) { | |
1275 | spin_unlock_irq(&zone->lru_lock); | |
1276 | putback_lru_page(page); | |
1277 | spin_lock_irq(&zone->lru_lock); | |
1278 | continue; | |
1279 | } | |
7a608572 | 1280 | SetPageLRU(page); |
66635629 | 1281 | lru = page_lru(page); |
7a608572 | 1282 | add_page_to_lru_list(zone, page, lru); |
66635629 MG |
1283 | if (is_active_lru(lru)) { |
1284 | int file = is_file_lru(lru); | |
9992af10 RR |
1285 | int numpages = hpage_nr_pages(page); |
1286 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 MG |
1287 | } |
1288 | if (!pagevec_add(&pvec, page)) { | |
1289 | spin_unlock_irq(&zone->lru_lock); | |
1290 | __pagevec_release(&pvec); | |
1291 | spin_lock_irq(&zone->lru_lock); | |
1292 | } | |
1293 | } | |
1294 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1295 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1296 | ||
1297 | spin_unlock_irq(&zone->lru_lock); | |
1298 | pagevec_release(&pvec); | |
1299 | } | |
1300 | ||
1489fa14 MG |
1301 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1302 | struct scan_control *sc, | |
1303 | unsigned long *nr_anon, | |
1304 | unsigned long *nr_file, | |
1305 | struct list_head *isolated_list) | |
1306 | { | |
1307 | unsigned long nr_active; | |
1308 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1309 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1310 | ||
1311 | nr_active = clear_active_flags(isolated_list, count); | |
1312 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1313 | ||
1314 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1315 | -count[LRU_ACTIVE_FILE]); | |
1316 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1317 | -count[LRU_INACTIVE_FILE]); | |
1318 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1319 | -count[LRU_ACTIVE_ANON]); | |
1320 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1321 | -count[LRU_INACTIVE_ANON]); | |
1322 | ||
1323 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1324 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1325 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1326 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1327 | ||
1328 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1329 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1330 | } | |
1331 | ||
e31f3698 WF |
1332 | /* |
1333 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1334 | * | |
1335 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1336 | * everything in the list, try again and wait for writeback IO to complete. | |
1337 | * This will stall high-order allocations noticeably. Only do that when really | |
1338 | * need to free the pages under high memory pressure. | |
1339 | */ | |
1340 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1341 | unsigned long nr_freed, | |
1342 | int priority, | |
1343 | struct scan_control *sc) | |
1344 | { | |
1345 | int lumpy_stall_priority; | |
1346 | ||
1347 | /* kswapd should not stall on sync IO */ | |
1348 | if (current_is_kswapd()) | |
1349 | return false; | |
1350 | ||
1351 | /* Only stall on lumpy reclaim */ | |
f3a310bc | 1352 | if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) |
e31f3698 WF |
1353 | return false; |
1354 | ||
1355 | /* If we have relaimed everything on the isolated list, no stall */ | |
1356 | if (nr_freed == nr_taken) | |
1357 | return false; | |
1358 | ||
1359 | /* | |
1360 | * For high-order allocations, there are two stall thresholds. | |
1361 | * High-cost allocations stall immediately where as lower | |
1362 | * order allocations such as stacks require the scanning | |
1363 | * priority to be much higher before stalling. | |
1364 | */ | |
1365 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1366 | lumpy_stall_priority = DEF_PRIORITY; | |
1367 | else | |
1368 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1369 | ||
1370 | return priority <= lumpy_stall_priority; | |
1371 | } | |
1372 | ||
1da177e4 | 1373 | /* |
1742f19f AM |
1374 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1375 | * of reclaimed pages | |
1da177e4 | 1376 | */ |
66635629 MG |
1377 | static noinline_for_stack unsigned long |
1378 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1379 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1380 | { |
1381 | LIST_HEAD(page_list); | |
e247dbce | 1382 | unsigned long nr_scanned; |
05ff5137 | 1383 | unsigned long nr_reclaimed = 0; |
e247dbce | 1384 | unsigned long nr_taken; |
e247dbce KM |
1385 | unsigned long nr_anon; |
1386 | unsigned long nr_file; | |
78dc583d | 1387 | |
35cd7815 | 1388 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1389 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1390 | |
1391 | /* We are about to die and free our memory. Return now. */ | |
1392 | if (fatal_signal_pending(current)) | |
1393 | return SWAP_CLUSTER_MAX; | |
1394 | } | |
1395 | ||
f3a310bc | 1396 | set_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1397 | lru_add_drain(); |
1398 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1399 | |
e247dbce KM |
1400 | if (scanning_global_lru(sc)) { |
1401 | nr_taken = isolate_pages_global(nr_to_scan, | |
1402 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1403 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1404 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1405 | zone, 0, file); |
1406 | zone->pages_scanned += nr_scanned; | |
1407 | if (current_is_kswapd()) | |
1408 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1409 | nr_scanned); | |
1410 | else | |
1411 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1412 | nr_scanned); | |
1413 | } else { | |
1414 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1415 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1416 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1417 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1418 | zone, sc->mem_cgroup, |
1419 | 0, file); | |
1420 | /* | |
1421 | * mem_cgroup_isolate_pages() keeps track of | |
1422 | * scanned pages on its own. | |
1423 | */ | |
1424 | } | |
b35ea17b | 1425 | |
66635629 MG |
1426 | if (nr_taken == 0) { |
1427 | spin_unlock_irq(&zone->lru_lock); | |
1428 | return 0; | |
1429 | } | |
5ad333eb | 1430 | |
1489fa14 | 1431 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1432 | |
e247dbce | 1433 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1434 | |
0e093d99 | 1435 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1436 | |
e31f3698 WF |
1437 | /* Check if we should syncronously wait for writeback */ |
1438 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
f3a310bc | 1439 | set_reclaim_mode(priority, sc, true); |
0e093d99 | 1440 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1441 | } |
b35ea17b | 1442 | |
e247dbce KM |
1443 | local_irq_disable(); |
1444 | if (current_is_kswapd()) | |
1445 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1446 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1447 | |
1489fa14 | 1448 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1449 | |
1450 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1451 | zone_idx(zone), | |
1452 | nr_scanned, nr_reclaimed, | |
1453 | priority, | |
f3a310bc | 1454 | trace_shrink_flags(file, sc->reclaim_mode)); |
05ff5137 | 1455 | return nr_reclaimed; |
1da177e4 LT |
1456 | } |
1457 | ||
1458 | /* | |
1459 | * This moves pages from the active list to the inactive list. | |
1460 | * | |
1461 | * We move them the other way if the page is referenced by one or more | |
1462 | * processes, from rmap. | |
1463 | * | |
1464 | * If the pages are mostly unmapped, the processing is fast and it is | |
1465 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1466 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1467 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1468 | * this, so instead we remove the pages from the LRU while processing them. | |
1469 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1470 | * nobody will play with that bit on a non-LRU page. | |
1471 | * | |
1472 | * The downside is that we have to touch page->_count against each page. | |
1473 | * But we had to alter page->flags anyway. | |
1474 | */ | |
1cfb419b | 1475 | |
3eb4140f WF |
1476 | static void move_active_pages_to_lru(struct zone *zone, |
1477 | struct list_head *list, | |
1478 | enum lru_list lru) | |
1479 | { | |
1480 | unsigned long pgmoved = 0; | |
1481 | struct pagevec pvec; | |
1482 | struct page *page; | |
1483 | ||
1484 | pagevec_init(&pvec, 1); | |
1485 | ||
1486 | while (!list_empty(list)) { | |
1487 | page = lru_to_page(list); | |
3eb4140f WF |
1488 | |
1489 | VM_BUG_ON(PageLRU(page)); | |
1490 | SetPageLRU(page); | |
1491 | ||
3eb4140f WF |
1492 | list_move(&page->lru, &zone->lru[lru].list); |
1493 | mem_cgroup_add_lru_list(page, lru); | |
2c888cfb | 1494 | pgmoved += hpage_nr_pages(page); |
3eb4140f WF |
1495 | |
1496 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1497 | spin_unlock_irq(&zone->lru_lock); | |
1498 | if (buffer_heads_over_limit) | |
1499 | pagevec_strip(&pvec); | |
1500 | __pagevec_release(&pvec); | |
1501 | spin_lock_irq(&zone->lru_lock); | |
1502 | } | |
1503 | } | |
1504 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1505 | if (!is_active_lru(lru)) | |
1506 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1507 | } | |
1cfb419b | 1508 | |
1742f19f | 1509 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1510 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1511 | { |
44c241f1 | 1512 | unsigned long nr_taken; |
69e05944 | 1513 | unsigned long pgscanned; |
6fe6b7e3 | 1514 | unsigned long vm_flags; |
1da177e4 | 1515 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1516 | LIST_HEAD(l_active); |
b69408e8 | 1517 | LIST_HEAD(l_inactive); |
1da177e4 | 1518 | struct page *page; |
6e901571 | 1519 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1520 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1521 | |
1522 | lru_add_drain(); | |
1523 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1524 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1525 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1526 | &pgscanned, sc->order, | |
1527 | ISOLATE_ACTIVE, zone, | |
1528 | 1, file); | |
1cfb419b | 1529 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1530 | } else { |
1531 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1532 | &pgscanned, sc->order, | |
1533 | ISOLATE_ACTIVE, zone, | |
1534 | sc->mem_cgroup, 1, file); | |
1535 | /* | |
1536 | * mem_cgroup_isolate_pages() keeps track of | |
1537 | * scanned pages on its own. | |
1538 | */ | |
4f98a2fe | 1539 | } |
8b25c6d2 | 1540 | |
b7c46d15 | 1541 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1542 | |
3eb4140f | 1543 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1544 | if (file) |
44c241f1 | 1545 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1546 | else |
44c241f1 | 1547 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1548 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1549 | spin_unlock_irq(&zone->lru_lock); |
1550 | ||
1da177e4 LT |
1551 | while (!list_empty(&l_hold)) { |
1552 | cond_resched(); | |
1553 | page = lru_to_page(&l_hold); | |
1554 | list_del(&page->lru); | |
7e9cd484 | 1555 | |
894bc310 LS |
1556 | if (unlikely(!page_evictable(page, NULL))) { |
1557 | putback_lru_page(page); | |
1558 | continue; | |
1559 | } | |
1560 | ||
64574746 | 1561 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
9992af10 | 1562 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1563 | /* |
1564 | * Identify referenced, file-backed active pages and | |
1565 | * give them one more trip around the active list. So | |
1566 | * that executable code get better chances to stay in | |
1567 | * memory under moderate memory pressure. Anon pages | |
1568 | * are not likely to be evicted by use-once streaming | |
1569 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1570 | * so we ignore them here. | |
1571 | */ | |
41e20983 | 1572 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1573 | list_add(&page->lru, &l_active); |
1574 | continue; | |
1575 | } | |
1576 | } | |
7e9cd484 | 1577 | |
5205e56e | 1578 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1579 | list_add(&page->lru, &l_inactive); |
1580 | } | |
1581 | ||
b555749a | 1582 | /* |
8cab4754 | 1583 | * Move pages back to the lru list. |
b555749a | 1584 | */ |
2a1dc509 | 1585 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1586 | /* |
8cab4754 WF |
1587 | * Count referenced pages from currently used mappings as rotated, |
1588 | * even though only some of them are actually re-activated. This | |
1589 | * helps balance scan pressure between file and anonymous pages in | |
1590 | * get_scan_ratio. | |
7e9cd484 | 1591 | */ |
b7c46d15 | 1592 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1593 | |
3eb4140f WF |
1594 | move_active_pages_to_lru(zone, &l_active, |
1595 | LRU_ACTIVE + file * LRU_FILE); | |
1596 | move_active_pages_to_lru(zone, &l_inactive, | |
1597 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1598 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1599 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1600 | } |
1601 | ||
74e3f3c3 | 1602 | #ifdef CONFIG_SWAP |
14797e23 | 1603 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1604 | { |
1605 | unsigned long active, inactive; | |
1606 | ||
1607 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1608 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1609 | ||
1610 | if (inactive * zone->inactive_ratio < active) | |
1611 | return 1; | |
1612 | ||
1613 | return 0; | |
1614 | } | |
1615 | ||
14797e23 KM |
1616 | /** |
1617 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1618 | * @zone: zone to check | |
1619 | * @sc: scan control of this context | |
1620 | * | |
1621 | * Returns true if the zone does not have enough inactive anon pages, | |
1622 | * meaning some active anon pages need to be deactivated. | |
1623 | */ | |
1624 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1625 | { | |
1626 | int low; | |
1627 | ||
74e3f3c3 MK |
1628 | /* |
1629 | * If we don't have swap space, anonymous page deactivation | |
1630 | * is pointless. | |
1631 | */ | |
1632 | if (!total_swap_pages) | |
1633 | return 0; | |
1634 | ||
e72e2bd6 | 1635 | if (scanning_global_lru(sc)) |
14797e23 KM |
1636 | low = inactive_anon_is_low_global(zone); |
1637 | else | |
c772be93 | 1638 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1639 | return low; |
1640 | } | |
74e3f3c3 MK |
1641 | #else |
1642 | static inline int inactive_anon_is_low(struct zone *zone, | |
1643 | struct scan_control *sc) | |
1644 | { | |
1645 | return 0; | |
1646 | } | |
1647 | #endif | |
14797e23 | 1648 | |
56e49d21 RR |
1649 | static int inactive_file_is_low_global(struct zone *zone) |
1650 | { | |
1651 | unsigned long active, inactive; | |
1652 | ||
1653 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1654 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1655 | ||
1656 | return (active > inactive); | |
1657 | } | |
1658 | ||
1659 | /** | |
1660 | * inactive_file_is_low - check if file pages need to be deactivated | |
1661 | * @zone: zone to check | |
1662 | * @sc: scan control of this context | |
1663 | * | |
1664 | * When the system is doing streaming IO, memory pressure here | |
1665 | * ensures that active file pages get deactivated, until more | |
1666 | * than half of the file pages are on the inactive list. | |
1667 | * | |
1668 | * Once we get to that situation, protect the system's working | |
1669 | * set from being evicted by disabling active file page aging. | |
1670 | * | |
1671 | * This uses a different ratio than the anonymous pages, because | |
1672 | * the page cache uses a use-once replacement algorithm. | |
1673 | */ | |
1674 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1675 | { | |
1676 | int low; | |
1677 | ||
1678 | if (scanning_global_lru(sc)) | |
1679 | low = inactive_file_is_low_global(zone); | |
1680 | else | |
1681 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1682 | return low; | |
1683 | } | |
1684 | ||
b39415b2 RR |
1685 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1686 | int file) | |
1687 | { | |
1688 | if (file) | |
1689 | return inactive_file_is_low(zone, sc); | |
1690 | else | |
1691 | return inactive_anon_is_low(zone, sc); | |
1692 | } | |
1693 | ||
4f98a2fe | 1694 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1695 | struct zone *zone, struct scan_control *sc, int priority) |
1696 | { | |
4f98a2fe RR |
1697 | int file = is_file_lru(lru); |
1698 | ||
b39415b2 RR |
1699 | if (is_active_lru(lru)) { |
1700 | if (inactive_list_is_low(zone, sc, file)) | |
1701 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1702 | return 0; |
1703 | } | |
1704 | ||
33c120ed | 1705 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1706 | } |
1707 | ||
76a33fc3 SL |
1708 | /* |
1709 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1710 | * until we collected @swap_cluster_max pages to scan. | |
1711 | */ | |
1712 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1713 | unsigned long *nr_saved_scan) | |
1714 | { | |
1715 | unsigned long nr; | |
1716 | ||
1717 | *nr_saved_scan += nr_to_scan; | |
1718 | nr = *nr_saved_scan; | |
1719 | ||
1720 | if (nr >= SWAP_CLUSTER_MAX) | |
1721 | *nr_saved_scan = 0; | |
1722 | else | |
1723 | nr = 0; | |
1724 | ||
1725 | return nr; | |
1726 | } | |
1727 | ||
4f98a2fe RR |
1728 | /* |
1729 | * Determine how aggressively the anon and file LRU lists should be | |
1730 | * scanned. The relative value of each set of LRU lists is determined | |
1731 | * by looking at the fraction of the pages scanned we did rotate back | |
1732 | * onto the active list instead of evict. | |
1733 | * | |
76a33fc3 | 1734 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1735 | */ |
76a33fc3 SL |
1736 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1737 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1738 | { |
1739 | unsigned long anon, file, free; | |
1740 | unsigned long anon_prio, file_prio; | |
1741 | unsigned long ap, fp; | |
6e901571 | 1742 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1743 | u64 fraction[2], denominator; |
1744 | enum lru_list l; | |
1745 | int noswap = 0; | |
1746 | ||
1747 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1748 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1749 | noswap = 1; | |
1750 | fraction[0] = 0; | |
1751 | fraction[1] = 1; | |
1752 | denominator = 1; | |
1753 | goto out; | |
1754 | } | |
4f98a2fe | 1755 | |
0b217676 VL |
1756 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1757 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1758 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1759 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1760 | |
e72e2bd6 | 1761 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1762 | free = zone_page_state(zone, NR_FREE_PAGES); |
1763 | /* If we have very few page cache pages, | |
1764 | force-scan anon pages. */ | |
41858966 | 1765 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1766 | fraction[0] = 1; |
1767 | fraction[1] = 0; | |
1768 | denominator = 1; | |
1769 | goto out; | |
eeee9a8c | 1770 | } |
4f98a2fe RR |
1771 | } |
1772 | ||
58c37f6e KM |
1773 | /* |
1774 | * With swappiness at 100, anonymous and file have the same priority. | |
1775 | * This scanning priority is essentially the inverse of IO cost. | |
1776 | */ | |
1777 | anon_prio = sc->swappiness; | |
1778 | file_prio = 200 - sc->swappiness; | |
1779 | ||
4f98a2fe RR |
1780 | /* |
1781 | * OK, so we have swap space and a fair amount of page cache | |
1782 | * pages. We use the recently rotated / recently scanned | |
1783 | * ratios to determine how valuable each cache is. | |
1784 | * | |
1785 | * Because workloads change over time (and to avoid overflow) | |
1786 | * we keep these statistics as a floating average, which ends | |
1787 | * up weighing recent references more than old ones. | |
1788 | * | |
1789 | * anon in [0], file in [1] | |
1790 | */ | |
58c37f6e | 1791 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1792 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1793 | reclaim_stat->recent_scanned[0] /= 2; |
1794 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1795 | } |
1796 | ||
6e901571 | 1797 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1798 | reclaim_stat->recent_scanned[1] /= 2; |
1799 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1800 | } |
1801 | ||
4f98a2fe | 1802 | /* |
00d8089c RR |
1803 | * The amount of pressure on anon vs file pages is inversely |
1804 | * proportional to the fraction of recently scanned pages on | |
1805 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1806 | */ |
6e901571 KM |
1807 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1808 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1809 | |
6e901571 KM |
1810 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1811 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1812 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1813 | |
76a33fc3 SL |
1814 | fraction[0] = ap; |
1815 | fraction[1] = fp; | |
1816 | denominator = ap + fp + 1; | |
1817 | out: | |
1818 | for_each_evictable_lru(l) { | |
1819 | int file = is_file_lru(l); | |
1820 | unsigned long scan; | |
6e08a369 | 1821 | |
76a33fc3 SL |
1822 | scan = zone_nr_lru_pages(zone, sc, l); |
1823 | if (priority || noswap) { | |
1824 | scan >>= priority; | |
1825 | scan = div64_u64(scan * fraction[file], denominator); | |
1826 | } | |
1827 | nr[l] = nr_scan_try_batch(scan, | |
1828 | &reclaim_stat->nr_saved_scan[l]); | |
1829 | } | |
6e08a369 | 1830 | } |
4f98a2fe | 1831 | |
3e7d3449 MG |
1832 | /* |
1833 | * Reclaim/compaction depends on a number of pages being freed. To avoid | |
1834 | * disruption to the system, a small number of order-0 pages continue to be | |
1835 | * rotated and reclaimed in the normal fashion. However, by the time we get | |
1836 | * back to the allocator and call try_to_compact_zone(), we ensure that | |
1837 | * there are enough free pages for it to be likely successful | |
1838 | */ | |
1839 | static inline bool should_continue_reclaim(struct zone *zone, | |
1840 | unsigned long nr_reclaimed, | |
1841 | unsigned long nr_scanned, | |
1842 | struct scan_control *sc) | |
1843 | { | |
1844 | unsigned long pages_for_compaction; | |
1845 | unsigned long inactive_lru_pages; | |
1846 | ||
1847 | /* If not in reclaim/compaction mode, stop */ | |
f3a310bc | 1848 | if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION)) |
3e7d3449 MG |
1849 | return false; |
1850 | ||
2876592f MG |
1851 | /* Consider stopping depending on scan and reclaim activity */ |
1852 | if (sc->gfp_mask & __GFP_REPEAT) { | |
1853 | /* | |
1854 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
1855 | * full LRU list has been scanned and we are still failing | |
1856 | * to reclaim pages. This full LRU scan is potentially | |
1857 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
1858 | */ | |
1859 | if (!nr_reclaimed && !nr_scanned) | |
1860 | return false; | |
1861 | } else { | |
1862 | /* | |
1863 | * For non-__GFP_REPEAT allocations which can presumably | |
1864 | * fail without consequence, stop if we failed to reclaim | |
1865 | * any pages from the last SWAP_CLUSTER_MAX number of | |
1866 | * pages that were scanned. This will return to the | |
1867 | * caller faster at the risk reclaim/compaction and | |
1868 | * the resulting allocation attempt fails | |
1869 | */ | |
1870 | if (!nr_reclaimed) | |
1871 | return false; | |
1872 | } | |
3e7d3449 MG |
1873 | |
1874 | /* | |
1875 | * If we have not reclaimed enough pages for compaction and the | |
1876 | * inactive lists are large enough, continue reclaiming | |
1877 | */ | |
1878 | pages_for_compaction = (2UL << sc->order); | |
1879 | inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + | |
1880 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1881 | if (sc->nr_reclaimed < pages_for_compaction && | |
1882 | inactive_lru_pages > pages_for_compaction) | |
1883 | return true; | |
1884 | ||
1885 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
1886 | switch (compaction_suitable(zone, sc->order)) { | |
1887 | case COMPACT_PARTIAL: | |
1888 | case COMPACT_CONTINUE: | |
1889 | return false; | |
1890 | default: | |
1891 | return true; | |
1892 | } | |
1893 | } | |
1894 | ||
1da177e4 LT |
1895 | /* |
1896 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1897 | */ | |
a79311c1 | 1898 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1899 | struct scan_control *sc) |
1da177e4 | 1900 | { |
b69408e8 | 1901 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1902 | unsigned long nr_to_scan; |
b69408e8 | 1903 | enum lru_list l; |
f0fdc5e8 | 1904 | unsigned long nr_reclaimed, nr_scanned; |
22fba335 | 1905 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1906 | |
3e7d3449 MG |
1907 | restart: |
1908 | nr_reclaimed = 0; | |
f0fdc5e8 | 1909 | nr_scanned = sc->nr_scanned; |
76a33fc3 | 1910 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1911 | |
556adecb RR |
1912 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1913 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1914 | for_each_evictable_lru(l) { |
b69408e8 | 1915 | if (nr[l]) { |
ece74b2e KM |
1916 | nr_to_scan = min_t(unsigned long, |
1917 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1918 | nr[l] -= nr_to_scan; |
1da177e4 | 1919 | |
01dbe5c9 KM |
1920 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1921 | zone, sc, priority); | |
b69408e8 | 1922 | } |
1da177e4 | 1923 | } |
a79311c1 RR |
1924 | /* |
1925 | * On large memory systems, scan >> priority can become | |
1926 | * really large. This is fine for the starting priority; | |
1927 | * we want to put equal scanning pressure on each zone. | |
1928 | * However, if the VM has a harder time of freeing pages, | |
1929 | * with multiple processes reclaiming pages, the total | |
1930 | * freeing target can get unreasonably large. | |
1931 | */ | |
338fde90 | 1932 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1933 | break; |
1da177e4 | 1934 | } |
3e7d3449 | 1935 | sc->nr_reclaimed += nr_reclaimed; |
01dbe5c9 | 1936 | |
556adecb RR |
1937 | /* |
1938 | * Even if we did not try to evict anon pages at all, we want to | |
1939 | * rebalance the anon lru active/inactive ratio. | |
1940 | */ | |
74e3f3c3 | 1941 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1942 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1943 | ||
3e7d3449 MG |
1944 | /* reclaim/compaction might need reclaim to continue */ |
1945 | if (should_continue_reclaim(zone, nr_reclaimed, | |
1946 | sc->nr_scanned - nr_scanned, sc)) | |
1947 | goto restart; | |
1948 | ||
232ea4d6 | 1949 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1950 | } |
1951 | ||
1952 | /* | |
1953 | * This is the direct reclaim path, for page-allocating processes. We only | |
1954 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1955 | * request. | |
1956 | * | |
41858966 MG |
1957 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1958 | * Because: | |
1da177e4 LT |
1959 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1960 | * allocation or | |
41858966 MG |
1961 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1962 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1963 | * zone defense algorithm. | |
1da177e4 | 1964 | * |
1da177e4 LT |
1965 | * If a zone is deemed to be full of pinned pages then just give it a light |
1966 | * scan then give up on it. | |
1967 | */ | |
d1908362 | 1968 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1969 | struct scan_control *sc) |
1da177e4 | 1970 | { |
dd1a239f | 1971 | struct zoneref *z; |
54a6eb5c | 1972 | struct zone *zone; |
1cfb419b | 1973 | |
d4debc66 MG |
1974 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1975 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1976 | if (!populated_zone(zone)) |
1da177e4 | 1977 | continue; |
1cfb419b KH |
1978 | /* |
1979 | * Take care memory controller reclaiming has small influence | |
1980 | * to global LRU. | |
1981 | */ | |
e72e2bd6 | 1982 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1983 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1984 | continue; | |
93e4a89a | 1985 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1986 | continue; /* Let kswapd poll it */ |
1cfb419b | 1987 | } |
408d8544 | 1988 | |
a79311c1 | 1989 | shrink_zone(priority, zone, sc); |
1da177e4 | 1990 | } |
d1908362 MK |
1991 | } |
1992 | ||
1993 | static bool zone_reclaimable(struct zone *zone) | |
1994 | { | |
1995 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
1996 | } | |
1997 | ||
929bea7c | 1998 | /* All zones in zonelist are unreclaimable? */ |
d1908362 MK |
1999 | static bool all_unreclaimable(struct zonelist *zonelist, |
2000 | struct scan_control *sc) | |
2001 | { | |
2002 | struct zoneref *z; | |
2003 | struct zone *zone; | |
d1908362 MK |
2004 | |
2005 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
2006 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
2007 | if (!populated_zone(zone)) | |
2008 | continue; | |
2009 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
2010 | continue; | |
929bea7c KM |
2011 | if (!zone->all_unreclaimable) |
2012 | return false; | |
d1908362 MK |
2013 | } |
2014 | ||
929bea7c | 2015 | return true; |
1da177e4 | 2016 | } |
4f98a2fe | 2017 | |
1da177e4 LT |
2018 | /* |
2019 | * This is the main entry point to direct page reclaim. | |
2020 | * | |
2021 | * If a full scan of the inactive list fails to free enough memory then we | |
2022 | * are "out of memory" and something needs to be killed. | |
2023 | * | |
2024 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2025 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2026 | * caller can't do much about. We kick the writeback threads and take explicit |
2027 | * naps in the hope that some of these pages can be written. But if the | |
2028 | * allocating task holds filesystem locks which prevent writeout this might not | |
2029 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2030 | * |
2031 | * returns: 0, if no pages reclaimed | |
2032 | * else, the number of pages reclaimed | |
1da177e4 | 2033 | */ |
dac1d27b | 2034 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 2035 | struct scan_control *sc) |
1da177e4 LT |
2036 | { |
2037 | int priority; | |
69e05944 | 2038 | unsigned long total_scanned = 0; |
1da177e4 | 2039 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2040 | struct zoneref *z; |
54a6eb5c | 2041 | struct zone *zone; |
22fba335 | 2042 | unsigned long writeback_threshold; |
1da177e4 | 2043 | |
c0ff7453 | 2044 | get_mems_allowed(); |
873b4771 KK |
2045 | delayacct_freepages_start(); |
2046 | ||
e72e2bd6 | 2047 | if (scanning_global_lru(sc)) |
1cfb419b | 2048 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
2049 | |
2050 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 2051 | sc->nr_scanned = 0; |
f7b7fd8f RR |
2052 | if (!priority) |
2053 | disable_swap_token(); | |
d1908362 | 2054 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
2055 | /* |
2056 | * Don't shrink slabs when reclaiming memory from | |
2057 | * over limit cgroups | |
2058 | */ | |
e72e2bd6 | 2059 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 2060 | unsigned long lru_pages = 0; |
d4debc66 MG |
2061 | for_each_zone_zonelist(zone, z, zonelist, |
2062 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2063 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2064 | continue; | |
2065 | ||
2066 | lru_pages += zone_reclaimable_pages(zone); | |
2067 | } | |
2068 | ||
dd1a239f | 2069 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 2070 | if (reclaim_state) { |
a79311c1 | 2071 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2072 | reclaim_state->reclaimed_slab = 0; |
2073 | } | |
1da177e4 | 2074 | } |
66e1707b | 2075 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2076 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2077 | goto out; |
1da177e4 LT |
2078 | |
2079 | /* | |
2080 | * Try to write back as many pages as we just scanned. This | |
2081 | * tends to cause slow streaming writers to write data to the | |
2082 | * disk smoothly, at the dirtying rate, which is nice. But | |
2083 | * that's undesirable in laptop mode, where we *want* lumpy | |
2084 | * writeout. So in laptop mode, write out the whole world. | |
2085 | */ | |
22fba335 KM |
2086 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2087 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 2088 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 2089 | sc->may_writepage = 1; |
1da177e4 LT |
2090 | } |
2091 | ||
2092 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 2093 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
2094 | priority < DEF_PRIORITY - 2) { |
2095 | struct zone *preferred_zone; | |
2096 | ||
2097 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
f33261d7 DR |
2098 | &cpuset_current_mems_allowed, |
2099 | &preferred_zone); | |
0e093d99 MG |
2100 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); |
2101 | } | |
1da177e4 | 2102 | } |
bb21c7ce | 2103 | |
1da177e4 | 2104 | out: |
873b4771 | 2105 | delayacct_freepages_end(); |
c0ff7453 | 2106 | put_mems_allowed(); |
873b4771 | 2107 | |
bb21c7ce KM |
2108 | if (sc->nr_reclaimed) |
2109 | return sc->nr_reclaimed; | |
2110 | ||
929bea7c KM |
2111 | /* |
2112 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
2113 | * the zone into all_unreclaimable. Thus bypassing all_unreclaimable | |
2114 | * check. | |
2115 | */ | |
2116 | if (oom_killer_disabled) | |
2117 | return 0; | |
2118 | ||
bb21c7ce | 2119 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
d1908362 | 2120 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2121 | return 1; |
2122 | ||
2123 | return 0; | |
1da177e4 LT |
2124 | } |
2125 | ||
dac1d27b | 2126 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2127 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2128 | { |
33906bc5 | 2129 | unsigned long nr_reclaimed; |
66e1707b BS |
2130 | struct scan_control sc = { |
2131 | .gfp_mask = gfp_mask, | |
2132 | .may_writepage = !laptop_mode, | |
22fba335 | 2133 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2134 | .may_unmap = 1, |
2e2e4259 | 2135 | .may_swap = 1, |
66e1707b BS |
2136 | .swappiness = vm_swappiness, |
2137 | .order = order, | |
2138 | .mem_cgroup = NULL, | |
327c0e96 | 2139 | .nodemask = nodemask, |
66e1707b BS |
2140 | }; |
2141 | ||
33906bc5 MG |
2142 | trace_mm_vmscan_direct_reclaim_begin(order, |
2143 | sc.may_writepage, | |
2144 | gfp_mask); | |
2145 | ||
2146 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2147 | ||
2148 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2149 | ||
2150 | return nr_reclaimed; | |
66e1707b BS |
2151 | } |
2152 | ||
00f0b825 | 2153 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2154 | |
4e416953 BS |
2155 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2156 | gfp_t gfp_mask, bool noswap, | |
2157 | unsigned int swappiness, | |
14fec796 | 2158 | struct zone *zone) |
4e416953 BS |
2159 | { |
2160 | struct scan_control sc = { | |
b8f5c566 | 2161 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2162 | .may_writepage = !laptop_mode, |
2163 | .may_unmap = 1, | |
2164 | .may_swap = !noswap, | |
4e416953 BS |
2165 | .swappiness = swappiness, |
2166 | .order = 0, | |
2167 | .mem_cgroup = mem, | |
4e416953 | 2168 | }; |
4e416953 BS |
2169 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2170 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2171 | |
2172 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2173 | sc.may_writepage, | |
2174 | sc.gfp_mask); | |
2175 | ||
4e416953 BS |
2176 | /* |
2177 | * NOTE: Although we can get the priority field, using it | |
2178 | * here is not a good idea, since it limits the pages we can scan. | |
2179 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2180 | * will pick up pages from other mem cgroup's as well. We hack | |
2181 | * the priority and make it zero. | |
2182 | */ | |
2183 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2184 | |
2185 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2186 | ||
4e416953 BS |
2187 | return sc.nr_reclaimed; |
2188 | } | |
2189 | ||
e1a1cd59 | 2190 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2191 | gfp_t gfp_mask, |
2192 | bool noswap, | |
2193 | unsigned int swappiness) | |
66e1707b | 2194 | { |
4e416953 | 2195 | struct zonelist *zonelist; |
bdce6d9e | 2196 | unsigned long nr_reclaimed; |
66e1707b | 2197 | struct scan_control sc = { |
66e1707b | 2198 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2199 | .may_unmap = 1, |
2e2e4259 | 2200 | .may_swap = !noswap, |
22fba335 | 2201 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2202 | .swappiness = swappiness, |
66e1707b BS |
2203 | .order = 0, |
2204 | .mem_cgroup = mem_cont, | |
327c0e96 | 2205 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 2206 | }; |
66e1707b | 2207 | |
dd1a239f MG |
2208 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2209 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
2210 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
bdce6d9e KM |
2211 | |
2212 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2213 | sc.may_writepage, | |
2214 | sc.gfp_mask); | |
2215 | ||
2216 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2217 | ||
2218 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2219 | ||
2220 | return nr_reclaimed; | |
66e1707b BS |
2221 | } |
2222 | #endif | |
2223 | ||
1741c877 MG |
2224 | /* |
2225 | * pgdat_balanced is used when checking if a node is balanced for high-order | |
2226 | * allocations. Only zones that meet watermarks and are in a zone allowed | |
2227 | * by the callers classzone_idx are added to balanced_pages. The total of | |
2228 | * balanced pages must be at least 25% of the zones allowed by classzone_idx | |
2229 | * for the node to be considered balanced. Forcing all zones to be balanced | |
2230 | * for high orders can cause excessive reclaim when there are imbalanced zones. | |
2231 | * The choice of 25% is due to | |
2232 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2233 | * reasonable sized machine | |
2234 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2235 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2236 | * would need to be at least 256M for it to be balance a whole node. |
2237 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2238 | * to balance a node on its own. These seemed like reasonable ratios. | |
2239 | */ | |
2240 | static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, | |
2241 | int classzone_idx) | |
2242 | { | |
2243 | unsigned long present_pages = 0; | |
2244 | int i; | |
2245 | ||
2246 | for (i = 0; i <= classzone_idx; i++) | |
2247 | present_pages += pgdat->node_zones[i].present_pages; | |
2248 | ||
2249 | return balanced_pages > (present_pages >> 2); | |
2250 | } | |
2251 | ||
f50de2d3 | 2252 | /* is kswapd sleeping prematurely? */ |
dc83edd9 MG |
2253 | static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, |
2254 | int classzone_idx) | |
f50de2d3 | 2255 | { |
bb3ab596 | 2256 | int i; |
1741c877 MG |
2257 | unsigned long balanced = 0; |
2258 | bool all_zones_ok = true; | |
f50de2d3 MG |
2259 | |
2260 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2261 | if (remaining) | |
dc83edd9 | 2262 | return true; |
f50de2d3 | 2263 | |
0abdee2b | 2264 | /* Check the watermark levels */ |
bb3ab596 KM |
2265 | for (i = 0; i < pgdat->nr_zones; i++) { |
2266 | struct zone *zone = pgdat->node_zones + i; | |
2267 | ||
2268 | if (!populated_zone(zone)) | |
2269 | continue; | |
2270 | ||
355b09c4 MG |
2271 | /* |
2272 | * balance_pgdat() skips over all_unreclaimable after | |
2273 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2274 | * they must be considered balanced here as well if kswapd | |
2275 | * is to sleep | |
2276 | */ | |
2277 | if (zone->all_unreclaimable) { | |
2278 | balanced += zone->present_pages; | |
de3fab39 | 2279 | continue; |
355b09c4 | 2280 | } |
de3fab39 | 2281 | |
88f5acf8 | 2282 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), |
dc83edd9 | 2283 | classzone_idx, 0)) |
1741c877 MG |
2284 | all_zones_ok = false; |
2285 | else | |
2286 | balanced += zone->present_pages; | |
bb3ab596 | 2287 | } |
f50de2d3 | 2288 | |
1741c877 MG |
2289 | /* |
2290 | * For high-order requests, the balanced zones must contain at least | |
2291 | * 25% of the nodes pages for kswapd to sleep. For order-0, all zones | |
2292 | * must be balanced | |
2293 | */ | |
2294 | if (order) | |
afc7e326 | 2295 | return !pgdat_balanced(pgdat, balanced, classzone_idx); |
1741c877 MG |
2296 | else |
2297 | return !all_zones_ok; | |
f50de2d3 MG |
2298 | } |
2299 | ||
1da177e4 LT |
2300 | /* |
2301 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2302 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2303 | * |
0abdee2b | 2304 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
2305 | * |
2306 | * There is special handling here for zones which are full of pinned pages. | |
2307 | * This can happen if the pages are all mlocked, or if they are all used by | |
2308 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2309 | * What we do is to detect the case where all pages in the zone have been | |
2310 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2311 | * dead and from now on, only perform a short scan. Basically we're polling | |
2312 | * the zone for when the problem goes away. | |
2313 | * | |
2314 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2315 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2316 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2317 | * lower zones regardless of the number of free pages in the lower zones. This | |
2318 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2319 | * of pages is balanced across the zones. | |
1da177e4 | 2320 | */ |
99504748 | 2321 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 2322 | int *classzone_idx) |
1da177e4 | 2323 | { |
1da177e4 | 2324 | int all_zones_ok; |
1741c877 | 2325 | unsigned long balanced; |
1da177e4 LT |
2326 | int priority; |
2327 | int i; | |
99504748 | 2328 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
69e05944 | 2329 | unsigned long total_scanned; |
1da177e4 | 2330 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2331 | struct scan_control sc = { |
2332 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2333 | .may_unmap = 1, |
2e2e4259 | 2334 | .may_swap = 1, |
22fba335 KM |
2335 | /* |
2336 | * kswapd doesn't want to be bailed out while reclaim. because | |
2337 | * we want to put equal scanning pressure on each zone. | |
2338 | */ | |
2339 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2340 | .swappiness = vm_swappiness, |
5ad333eb | 2341 | .order = order, |
66e1707b | 2342 | .mem_cgroup = NULL, |
179e9639 | 2343 | }; |
1da177e4 LT |
2344 | loop_again: |
2345 | total_scanned = 0; | |
a79311c1 | 2346 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2347 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2348 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2349 | |
1da177e4 | 2350 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
1da177e4 | 2351 | unsigned long lru_pages = 0; |
bb3ab596 | 2352 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2353 | |
f7b7fd8f RR |
2354 | /* The swap token gets in the way of swapout... */ |
2355 | if (!priority) | |
2356 | disable_swap_token(); | |
2357 | ||
1da177e4 | 2358 | all_zones_ok = 1; |
1741c877 | 2359 | balanced = 0; |
1da177e4 | 2360 | |
d6277db4 RW |
2361 | /* |
2362 | * Scan in the highmem->dma direction for the highest | |
2363 | * zone which needs scanning | |
2364 | */ | |
2365 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2366 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2367 | |
d6277db4 RW |
2368 | if (!populated_zone(zone)) |
2369 | continue; | |
1da177e4 | 2370 | |
93e4a89a | 2371 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2372 | continue; |
1da177e4 | 2373 | |
556adecb RR |
2374 | /* |
2375 | * Do some background aging of the anon list, to give | |
2376 | * pages a chance to be referenced before reclaiming. | |
2377 | */ | |
14797e23 | 2378 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2379 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2380 | &sc, priority, 0); | |
2381 | ||
88f5acf8 | 2382 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2383 | high_wmark_pages(zone), 0, 0)) { |
d6277db4 | 2384 | end_zone = i; |
dc83edd9 | 2385 | *classzone_idx = i; |
e1dbeda6 | 2386 | break; |
1da177e4 | 2387 | } |
1da177e4 | 2388 | } |
e1dbeda6 AM |
2389 | if (i < 0) |
2390 | goto out; | |
2391 | ||
1da177e4 LT |
2392 | for (i = 0; i <= end_zone; i++) { |
2393 | struct zone *zone = pgdat->node_zones + i; | |
2394 | ||
adea02a1 | 2395 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2396 | } |
2397 | ||
2398 | /* | |
2399 | * Now scan the zone in the dma->highmem direction, stopping | |
2400 | * at the last zone which needs scanning. | |
2401 | * | |
2402 | * We do this because the page allocator works in the opposite | |
2403 | * direction. This prevents the page allocator from allocating | |
2404 | * pages behind kswapd's direction of progress, which would | |
2405 | * cause too much scanning of the lower zones. | |
2406 | */ | |
2407 | for (i = 0; i <= end_zone; i++) { | |
2408 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2409 | int nr_slab; |
8afdcece | 2410 | unsigned long balance_gap; |
1da177e4 | 2411 | |
f3fe6512 | 2412 | if (!populated_zone(zone)) |
1da177e4 LT |
2413 | continue; |
2414 | ||
93e4a89a | 2415 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2416 | continue; |
2417 | ||
1da177e4 | 2418 | sc.nr_scanned = 0; |
4e416953 | 2419 | |
4e416953 BS |
2420 | /* |
2421 | * Call soft limit reclaim before calling shrink_zone. | |
2422 | * For now we ignore the return value | |
2423 | */ | |
00918b6a KM |
2424 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask); |
2425 | ||
32a4330d | 2426 | /* |
8afdcece MG |
2427 | * We put equal pressure on every zone, unless |
2428 | * one zone has way too many pages free | |
2429 | * already. The "too many pages" is defined | |
2430 | * as the high wmark plus a "gap" where the | |
2431 | * gap is either the low watermark or 1% | |
2432 | * of the zone, whichever is smaller. | |
32a4330d | 2433 | */ |
8afdcece MG |
2434 | balance_gap = min(low_wmark_pages(zone), |
2435 | (zone->present_pages + | |
2436 | KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / | |
2437 | KSWAPD_ZONE_BALANCE_GAP_RATIO); | |
88f5acf8 | 2438 | if (!zone_watermark_ok_safe(zone, order, |
8afdcece MG |
2439 | high_wmark_pages(zone) + balance_gap, |
2440 | end_zone, 0)) | |
a79311c1 | 2441 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2442 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2443 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2444 | lru_pages); | |
a79311c1 | 2445 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2446 | total_scanned += sc.nr_scanned; |
5a03b051 | 2447 | |
93e4a89a | 2448 | if (zone->all_unreclaimable) |
1da177e4 | 2449 | continue; |
d527caf2 | 2450 | if (nr_slab == 0 && |
5a03b051 | 2451 | !zone_reclaimable(zone)) |
93e4a89a | 2452 | zone->all_unreclaimable = 1; |
1da177e4 LT |
2453 | /* |
2454 | * If we've done a decent amount of scanning and | |
2455 | * the reclaim ratio is low, start doing writepage | |
2456 | * even in laptop mode | |
2457 | */ | |
2458 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2459 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2460 | sc.may_writepage = 1; |
bb3ab596 | 2461 | |
88f5acf8 | 2462 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2463 | high_wmark_pages(zone), end_zone, 0)) { |
2464 | all_zones_ok = 0; | |
2465 | /* | |
2466 | * We are still under min water mark. This | |
2467 | * means that we have a GFP_ATOMIC allocation | |
2468 | * failure risk. Hurry up! | |
2469 | */ | |
88f5acf8 | 2470 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2471 | min_wmark_pages(zone), end_zone, 0)) |
2472 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2473 | } else { |
2474 | /* | |
2475 | * If a zone reaches its high watermark, | |
2476 | * consider it to be no longer congested. It's | |
2477 | * possible there are dirty pages backed by | |
2478 | * congested BDIs but as pressure is relieved, | |
2479 | * spectulatively avoid congestion waits | |
2480 | */ | |
2481 | zone_clear_flag(zone, ZONE_CONGESTED); | |
dc83edd9 | 2482 | if (i <= *classzone_idx) |
1741c877 | 2483 | balanced += zone->present_pages; |
45973d74 | 2484 | } |
bb3ab596 | 2485 | |
1da177e4 | 2486 | } |
dc83edd9 | 2487 | if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) |
1da177e4 LT |
2488 | break; /* kswapd: all done */ |
2489 | /* | |
2490 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2491 | * another pass across the zones. | |
2492 | */ | |
bb3ab596 KM |
2493 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2494 | if (has_under_min_watermark_zone) | |
2495 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2496 | else | |
2497 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2498 | } | |
1da177e4 LT |
2499 | |
2500 | /* | |
2501 | * We do this so kswapd doesn't build up large priorities for | |
2502 | * example when it is freeing in parallel with allocators. It | |
2503 | * matches the direct reclaim path behaviour in terms of impact | |
2504 | * on zone->*_priority. | |
2505 | */ | |
a79311c1 | 2506 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2507 | break; |
2508 | } | |
2509 | out: | |
99504748 MG |
2510 | |
2511 | /* | |
2512 | * order-0: All zones must meet high watermark for a balanced node | |
1741c877 MG |
2513 | * high-order: Balanced zones must make up at least 25% of the node |
2514 | * for the node to be balanced | |
99504748 | 2515 | */ |
dc83edd9 | 2516 | if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { |
1da177e4 | 2517 | cond_resched(); |
8357376d RW |
2518 | |
2519 | try_to_freeze(); | |
2520 | ||
73ce02e9 KM |
2521 | /* |
2522 | * Fragmentation may mean that the system cannot be | |
2523 | * rebalanced for high-order allocations in all zones. | |
2524 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2525 | * it means the zones have been fully scanned and are still | |
2526 | * not balanced. For high-order allocations, there is | |
2527 | * little point trying all over again as kswapd may | |
2528 | * infinite loop. | |
2529 | * | |
2530 | * Instead, recheck all watermarks at order-0 as they | |
2531 | * are the most important. If watermarks are ok, kswapd will go | |
2532 | * back to sleep. High-order users can still perform direct | |
2533 | * reclaim if they wish. | |
2534 | */ | |
2535 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2536 | order = sc.order = 0; | |
2537 | ||
1da177e4 LT |
2538 | goto loop_again; |
2539 | } | |
2540 | ||
99504748 MG |
2541 | /* |
2542 | * If kswapd was reclaiming at a higher order, it has the option of | |
2543 | * sleeping without all zones being balanced. Before it does, it must | |
2544 | * ensure that the watermarks for order-0 on *all* zones are met and | |
2545 | * that the congestion flags are cleared. The congestion flag must | |
2546 | * be cleared as kswapd is the only mechanism that clears the flag | |
2547 | * and it is potentially going to sleep here. | |
2548 | */ | |
2549 | if (order) { | |
2550 | for (i = 0; i <= end_zone; i++) { | |
2551 | struct zone *zone = pgdat->node_zones + i; | |
2552 | ||
2553 | if (!populated_zone(zone)) | |
2554 | continue; | |
2555 | ||
2556 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
2557 | continue; | |
2558 | ||
2559 | /* Confirm the zone is balanced for order-0 */ | |
2560 | if (!zone_watermark_ok(zone, 0, | |
2561 | high_wmark_pages(zone), 0, 0)) { | |
2562 | order = sc.order = 0; | |
2563 | goto loop_again; | |
2564 | } | |
2565 | ||
2566 | /* If balanced, clear the congested flag */ | |
2567 | zone_clear_flag(zone, ZONE_CONGESTED); | |
2568 | } | |
2569 | } | |
2570 | ||
0abdee2b MG |
2571 | /* |
2572 | * Return the order we were reclaiming at so sleeping_prematurely() | |
2573 | * makes a decision on the order we were last reclaiming at. However, | |
2574 | * if another caller entered the allocator slow path while kswapd | |
2575 | * was awake, order will remain at the higher level | |
2576 | */ | |
dc83edd9 | 2577 | *classzone_idx = end_zone; |
0abdee2b | 2578 | return order; |
1da177e4 LT |
2579 | } |
2580 | ||
dc83edd9 | 2581 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
2582 | { |
2583 | long remaining = 0; | |
2584 | DEFINE_WAIT(wait); | |
2585 | ||
2586 | if (freezing(current) || kthread_should_stop()) | |
2587 | return; | |
2588 | ||
2589 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2590 | ||
2591 | /* Try to sleep for a short interval */ | |
dc83edd9 | 2592 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2593 | remaining = schedule_timeout(HZ/10); |
2594 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2595 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2596 | } | |
2597 | ||
2598 | /* | |
2599 | * After a short sleep, check if it was a premature sleep. If not, then | |
2600 | * go fully to sleep until explicitly woken up. | |
2601 | */ | |
dc83edd9 | 2602 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2603 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
2604 | ||
2605 | /* | |
2606 | * vmstat counters are not perfectly accurate and the estimated | |
2607 | * value for counters such as NR_FREE_PAGES can deviate from the | |
2608 | * true value by nr_online_cpus * threshold. To avoid the zone | |
2609 | * watermarks being breached while under pressure, we reduce the | |
2610 | * per-cpu vmstat threshold while kswapd is awake and restore | |
2611 | * them before going back to sleep. | |
2612 | */ | |
2613 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
2614 | schedule(); | |
2615 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); | |
2616 | } else { | |
2617 | if (remaining) | |
2618 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
2619 | else | |
2620 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
2621 | } | |
2622 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2623 | } | |
2624 | ||
1da177e4 LT |
2625 | /* |
2626 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2627 | * from the init process. |
1da177e4 LT |
2628 | * |
2629 | * This basically trickles out pages so that we have _some_ | |
2630 | * free memory available even if there is no other activity | |
2631 | * that frees anything up. This is needed for things like routing | |
2632 | * etc, where we otherwise might have all activity going on in | |
2633 | * asynchronous contexts that cannot page things out. | |
2634 | * | |
2635 | * If there are applications that are active memory-allocators | |
2636 | * (most normal use), this basically shouldn't matter. | |
2637 | */ | |
2638 | static int kswapd(void *p) | |
2639 | { | |
2640 | unsigned long order; | |
99504748 | 2641 | int classzone_idx; |
1da177e4 LT |
2642 | pg_data_t *pgdat = (pg_data_t*)p; |
2643 | struct task_struct *tsk = current; | |
f0bc0a60 | 2644 | |
1da177e4 LT |
2645 | struct reclaim_state reclaim_state = { |
2646 | .reclaimed_slab = 0, | |
2647 | }; | |
a70f7302 | 2648 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2649 | |
cf40bd16 NP |
2650 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2651 | ||
174596a0 | 2652 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2653 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2654 | current->reclaim_state = &reclaim_state; |
2655 | ||
2656 | /* | |
2657 | * Tell the memory management that we're a "memory allocator", | |
2658 | * and that if we need more memory we should get access to it | |
2659 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2660 | * never get caught in the normal page freeing logic. | |
2661 | * | |
2662 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2663 | * you need a small amount of memory in order to be able to | |
2664 | * page out something else, and this flag essentially protects | |
2665 | * us from recursively trying to free more memory as we're | |
2666 | * trying to free the first piece of memory in the first place). | |
2667 | */ | |
930d9152 | 2668 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2669 | set_freezable(); |
1da177e4 LT |
2670 | |
2671 | order = 0; | |
99504748 | 2672 | classzone_idx = MAX_NR_ZONES - 1; |
1da177e4 LT |
2673 | for ( ; ; ) { |
2674 | unsigned long new_order; | |
99504748 | 2675 | int new_classzone_idx; |
8fe23e05 | 2676 | int ret; |
3e1d1d28 | 2677 | |
1da177e4 | 2678 | new_order = pgdat->kswapd_max_order; |
99504748 | 2679 | new_classzone_idx = pgdat->classzone_idx; |
1da177e4 | 2680 | pgdat->kswapd_max_order = 0; |
99504748 MG |
2681 | pgdat->classzone_idx = MAX_NR_ZONES - 1; |
2682 | if (order < new_order || classzone_idx > new_classzone_idx) { | |
1da177e4 LT |
2683 | /* |
2684 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 2685 | * allocation or has tigher zone constraints |
1da177e4 LT |
2686 | */ |
2687 | order = new_order; | |
99504748 | 2688 | classzone_idx = new_classzone_idx; |
1da177e4 | 2689 | } else { |
dc83edd9 | 2690 | kswapd_try_to_sleep(pgdat, order, classzone_idx); |
1da177e4 | 2691 | order = pgdat->kswapd_max_order; |
99504748 | 2692 | classzone_idx = pgdat->classzone_idx; |
4d40502e MG |
2693 | pgdat->kswapd_max_order = 0; |
2694 | pgdat->classzone_idx = MAX_NR_ZONES - 1; | |
1da177e4 | 2695 | } |
1da177e4 | 2696 | |
8fe23e05 DR |
2697 | ret = try_to_freeze(); |
2698 | if (kthread_should_stop()) | |
2699 | break; | |
2700 | ||
2701 | /* | |
2702 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2703 | * after returning from the refrigerator | |
2704 | */ | |
33906bc5 MG |
2705 | if (!ret) { |
2706 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
dc83edd9 | 2707 | order = balance_pgdat(pgdat, order, &classzone_idx); |
33906bc5 | 2708 | } |
1da177e4 LT |
2709 | } |
2710 | return 0; | |
2711 | } | |
2712 | ||
2713 | /* | |
2714 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2715 | */ | |
99504748 | 2716 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
2717 | { |
2718 | pg_data_t *pgdat; | |
2719 | ||
f3fe6512 | 2720 | if (!populated_zone(zone)) |
1da177e4 LT |
2721 | return; |
2722 | ||
88f5acf8 | 2723 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2724 | return; |
88f5acf8 | 2725 | pgdat = zone->zone_pgdat; |
99504748 | 2726 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 2727 | pgdat->kswapd_max_order = order; |
99504748 MG |
2728 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
2729 | } | |
8d0986e2 | 2730 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2731 | return; |
88f5acf8 MG |
2732 | if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0)) |
2733 | return; | |
2734 | ||
2735 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 2736 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2737 | } |
2738 | ||
adea02a1 WF |
2739 | /* |
2740 | * The reclaimable count would be mostly accurate. | |
2741 | * The less reclaimable pages may be | |
2742 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2743 | * - mapped pages, which may require several travels to be reclaimed | |
2744 | * - dirty pages, which is not "instantly" reclaimable | |
2745 | */ | |
2746 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2747 | { |
adea02a1 WF |
2748 | int nr; |
2749 | ||
2750 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2751 | global_page_state(NR_INACTIVE_FILE); | |
2752 | ||
2753 | if (nr_swap_pages > 0) | |
2754 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2755 | global_page_state(NR_INACTIVE_ANON); | |
2756 | ||
2757 | return nr; | |
2758 | } | |
2759 | ||
2760 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2761 | { | |
2762 | int nr; | |
2763 | ||
2764 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2765 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2766 | ||
2767 | if (nr_swap_pages > 0) | |
2768 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2769 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2770 | ||
2771 | return nr; | |
4f98a2fe RR |
2772 | } |
2773 | ||
c6f37f12 | 2774 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2775 | /* |
7b51755c | 2776 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2777 | * freed pages. |
2778 | * | |
2779 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2780 | * LRU order by reclaiming preferentially | |
2781 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2782 | */ |
7b51755c | 2783 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2784 | { |
d6277db4 | 2785 | struct reclaim_state reclaim_state; |
d6277db4 | 2786 | struct scan_control sc = { |
7b51755c KM |
2787 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2788 | .may_swap = 1, | |
2789 | .may_unmap = 1, | |
d6277db4 | 2790 | .may_writepage = 1, |
7b51755c KM |
2791 | .nr_to_reclaim = nr_to_reclaim, |
2792 | .hibernation_mode = 1, | |
2793 | .swappiness = vm_swappiness, | |
2794 | .order = 0, | |
1da177e4 | 2795 | }; |
7b51755c KM |
2796 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2797 | struct task_struct *p = current; | |
2798 | unsigned long nr_reclaimed; | |
1da177e4 | 2799 | |
7b51755c KM |
2800 | p->flags |= PF_MEMALLOC; |
2801 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2802 | reclaim_state.reclaimed_slab = 0; | |
2803 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2804 | |
7b51755c | 2805 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2806 | |
7b51755c KM |
2807 | p->reclaim_state = NULL; |
2808 | lockdep_clear_current_reclaim_state(); | |
2809 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2810 | |
7b51755c | 2811 | return nr_reclaimed; |
1da177e4 | 2812 | } |
c6f37f12 | 2813 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2814 | |
1da177e4 LT |
2815 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2816 | not required for correctness. So if the last cpu in a node goes | |
2817 | away, we get changed to run anywhere: as the first one comes back, | |
2818 | restore their cpu bindings. */ | |
9c7b216d | 2819 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2820 | unsigned long action, void *hcpu) |
1da177e4 | 2821 | { |
58c0a4a7 | 2822 | int nid; |
1da177e4 | 2823 | |
8bb78442 | 2824 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2825 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2826 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2827 | const struct cpumask *mask; |
2828 | ||
2829 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2830 | |
3e597945 | 2831 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2832 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2833 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2834 | } |
2835 | } | |
2836 | return NOTIFY_OK; | |
2837 | } | |
1da177e4 | 2838 | |
3218ae14 YG |
2839 | /* |
2840 | * This kswapd start function will be called by init and node-hot-add. | |
2841 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2842 | */ | |
2843 | int kswapd_run(int nid) | |
2844 | { | |
2845 | pg_data_t *pgdat = NODE_DATA(nid); | |
2846 | int ret = 0; | |
2847 | ||
2848 | if (pgdat->kswapd) | |
2849 | return 0; | |
2850 | ||
2851 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2852 | if (IS_ERR(pgdat->kswapd)) { | |
2853 | /* failure at boot is fatal */ | |
2854 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2855 | printk("Failed to start kswapd on node %d\n",nid); | |
2856 | ret = -1; | |
2857 | } | |
2858 | return ret; | |
2859 | } | |
2860 | ||
8fe23e05 DR |
2861 | /* |
2862 | * Called by memory hotplug when all memory in a node is offlined. | |
2863 | */ | |
2864 | void kswapd_stop(int nid) | |
2865 | { | |
2866 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2867 | ||
2868 | if (kswapd) | |
2869 | kthread_stop(kswapd); | |
2870 | } | |
2871 | ||
1da177e4 LT |
2872 | static int __init kswapd_init(void) |
2873 | { | |
3218ae14 | 2874 | int nid; |
69e05944 | 2875 | |
1da177e4 | 2876 | swap_setup(); |
9422ffba | 2877 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2878 | kswapd_run(nid); |
1da177e4 LT |
2879 | hotcpu_notifier(cpu_callback, 0); |
2880 | return 0; | |
2881 | } | |
2882 | ||
2883 | module_init(kswapd_init) | |
9eeff239 CL |
2884 | |
2885 | #ifdef CONFIG_NUMA | |
2886 | /* | |
2887 | * Zone reclaim mode | |
2888 | * | |
2889 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2890 | * the watermarks. | |
9eeff239 CL |
2891 | */ |
2892 | int zone_reclaim_mode __read_mostly; | |
2893 | ||
1b2ffb78 | 2894 | #define RECLAIM_OFF 0 |
7d03431c | 2895 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2896 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2897 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2898 | ||
a92f7126 CL |
2899 | /* |
2900 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2901 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2902 | * a zone. | |
2903 | */ | |
2904 | #define ZONE_RECLAIM_PRIORITY 4 | |
2905 | ||
9614634f CL |
2906 | /* |
2907 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2908 | * occur. | |
2909 | */ | |
2910 | int sysctl_min_unmapped_ratio = 1; | |
2911 | ||
0ff38490 CL |
2912 | /* |
2913 | * If the number of slab pages in a zone grows beyond this percentage then | |
2914 | * slab reclaim needs to occur. | |
2915 | */ | |
2916 | int sysctl_min_slab_ratio = 5; | |
2917 | ||
90afa5de MG |
2918 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2919 | { | |
2920 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2921 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2922 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2923 | ||
2924 | /* | |
2925 | * It's possible for there to be more file mapped pages than | |
2926 | * accounted for by the pages on the file LRU lists because | |
2927 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2928 | */ | |
2929 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2930 | } | |
2931 | ||
2932 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2933 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2934 | { | |
2935 | long nr_pagecache_reclaimable; | |
2936 | long delta = 0; | |
2937 | ||
2938 | /* | |
2939 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2940 | * potentially reclaimable. Otherwise, we have to worry about | |
2941 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2942 | * a better estimate | |
2943 | */ | |
2944 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2945 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2946 | else | |
2947 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2948 | ||
2949 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2950 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2951 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2952 | ||
2953 | /* Watch for any possible underflows due to delta */ | |
2954 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2955 | delta = nr_pagecache_reclaimable; | |
2956 | ||
2957 | return nr_pagecache_reclaimable - delta; | |
2958 | } | |
2959 | ||
9eeff239 CL |
2960 | /* |
2961 | * Try to free up some pages from this zone through reclaim. | |
2962 | */ | |
179e9639 | 2963 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2964 | { |
7fb2d46d | 2965 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2966 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2967 | struct task_struct *p = current; |
2968 | struct reclaim_state reclaim_state; | |
8695949a | 2969 | int priority; |
179e9639 AM |
2970 | struct scan_control sc = { |
2971 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2972 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2973 | .may_swap = 1, |
22fba335 KM |
2974 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2975 | SWAP_CLUSTER_MAX), | |
179e9639 | 2976 | .gfp_mask = gfp_mask, |
d6277db4 | 2977 | .swappiness = vm_swappiness, |
bd2f6199 | 2978 | .order = order, |
179e9639 | 2979 | }; |
15748048 | 2980 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 2981 | |
9eeff239 | 2982 | cond_resched(); |
d4f7796e CL |
2983 | /* |
2984 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2985 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2986 | * and RECLAIM_SWAP. | |
2987 | */ | |
2988 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2989 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2990 | reclaim_state.reclaimed_slab = 0; |
2991 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2992 | |
90afa5de | 2993 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2994 | /* |
2995 | * Free memory by calling shrink zone with increasing | |
2996 | * priorities until we have enough memory freed. | |
2997 | */ | |
2998 | priority = ZONE_RECLAIM_PRIORITY; | |
2999 | do { | |
a79311c1 | 3000 | shrink_zone(priority, zone, &sc); |
0ff38490 | 3001 | priority--; |
a79311c1 | 3002 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 3003 | } |
c84db23c | 3004 | |
15748048 KM |
3005 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3006 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 3007 | /* |
7fb2d46d | 3008 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
3009 | * many pages were freed in this zone. So we take the current |
3010 | * number of slab pages and shake the slab until it is reduced | |
3011 | * by the same nr_pages that we used for reclaiming unmapped | |
3012 | * pages. | |
2a16e3f4 | 3013 | * |
0ff38490 CL |
3014 | * Note that shrink_slab will free memory on all zones and may |
3015 | * take a long time. | |
2a16e3f4 | 3016 | */ |
4dc4b3d9 KM |
3017 | for (;;) { |
3018 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
3019 | ||
3020 | /* No reclaimable slab or very low memory pressure */ | |
3021 | if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages)) | |
3022 | break; | |
3023 | ||
3024 | /* Freed enough memory */ | |
3025 | nr_slab_pages1 = zone_page_state(zone, | |
3026 | NR_SLAB_RECLAIMABLE); | |
3027 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
3028 | break; | |
3029 | } | |
83e33a47 CL |
3030 | |
3031 | /* | |
3032 | * Update nr_reclaimed by the number of slab pages we | |
3033 | * reclaimed from this zone. | |
3034 | */ | |
15748048 KM |
3035 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3036 | if (nr_slab_pages1 < nr_slab_pages0) | |
3037 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
3038 | } |
3039 | ||
9eeff239 | 3040 | p->reclaim_state = NULL; |
d4f7796e | 3041 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3042 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3043 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3044 | } |
179e9639 AM |
3045 | |
3046 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3047 | { | |
179e9639 | 3048 | int node_id; |
d773ed6b | 3049 | int ret; |
179e9639 AM |
3050 | |
3051 | /* | |
0ff38490 CL |
3052 | * Zone reclaim reclaims unmapped file backed pages and |
3053 | * slab pages if we are over the defined limits. | |
34aa1330 | 3054 | * |
9614634f CL |
3055 | * A small portion of unmapped file backed pages is needed for |
3056 | * file I/O otherwise pages read by file I/O will be immediately | |
3057 | * thrown out if the zone is overallocated. So we do not reclaim | |
3058 | * if less than a specified percentage of the zone is used by | |
3059 | * unmapped file backed pages. | |
179e9639 | 3060 | */ |
90afa5de MG |
3061 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3062 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3063 | return ZONE_RECLAIM_FULL; |
179e9639 | 3064 | |
93e4a89a | 3065 | if (zone->all_unreclaimable) |
fa5e084e | 3066 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3067 | |
179e9639 | 3068 | /* |
d773ed6b | 3069 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3070 | */ |
d773ed6b | 3071 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3072 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3073 | |
3074 | /* | |
3075 | * Only run zone reclaim on the local zone or on zones that do not | |
3076 | * have associated processors. This will favor the local processor | |
3077 | * over remote processors and spread off node memory allocations | |
3078 | * as wide as possible. | |
3079 | */ | |
89fa3024 | 3080 | node_id = zone_to_nid(zone); |
37c0708d | 3081 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3082 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
3083 | |
3084 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
3085 | return ZONE_RECLAIM_NOSCAN; |
3086 | ||
d773ed6b DR |
3087 | ret = __zone_reclaim(zone, gfp_mask, order); |
3088 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
3089 | ||
24cf7251 MG |
3090 | if (!ret) |
3091 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3092 | ||
d773ed6b | 3093 | return ret; |
179e9639 | 3094 | } |
9eeff239 | 3095 | #endif |
894bc310 | 3096 | |
894bc310 LS |
3097 | /* |
3098 | * page_evictable - test whether a page is evictable | |
3099 | * @page: the page to test | |
3100 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
3101 | * | |
3102 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
3103 | * lists vs unevictable list. The vma argument is !NULL when called from the |
3104 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
3105 | * |
3106 | * Reasons page might not be evictable: | |
ba9ddf49 | 3107 | * (1) page's mapping marked unevictable |
b291f000 | 3108 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3109 | * |
894bc310 LS |
3110 | */ |
3111 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
3112 | { | |
3113 | ||
ba9ddf49 LS |
3114 | if (mapping_unevictable(page_mapping(page))) |
3115 | return 0; | |
3116 | ||
b291f000 NP |
3117 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
3118 | return 0; | |
894bc310 LS |
3119 | |
3120 | return 1; | |
3121 | } | |
89e004ea LS |
3122 | |
3123 | /** | |
3124 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
3125 | * @page: page to check evictability and move to appropriate lru list | |
3126 | * @zone: zone page is in | |
3127 | * | |
3128 | * Checks a page for evictability and moves the page to the appropriate | |
3129 | * zone lru list. | |
3130 | * | |
3131 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
3132 | * have PageUnevictable set. | |
3133 | */ | |
3134 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
3135 | { | |
3136 | VM_BUG_ON(PageActive(page)); | |
3137 | ||
3138 | retry: | |
3139 | ClearPageUnevictable(page); | |
3140 | if (page_evictable(page, NULL)) { | |
401a8e1c | 3141 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 3142 | |
89e004ea LS |
3143 | __dec_zone_state(zone, NR_UNEVICTABLE); |
3144 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 3145 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
3146 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
3147 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
3148 | } else { | |
3149 | /* | |
3150 | * rotate unevictable list | |
3151 | */ | |
3152 | SetPageUnevictable(page); | |
3153 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 3154 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
3155 | if (page_evictable(page, NULL)) |
3156 | goto retry; | |
3157 | } | |
3158 | } | |
3159 | ||
3160 | /** | |
3161 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
3162 | * @mapping: struct address_space to scan for evictable pages | |
3163 | * | |
3164 | * Scan all pages in mapping. Check unevictable pages for | |
3165 | * evictability and move them to the appropriate zone lru list. | |
3166 | */ | |
3167 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
3168 | { | |
3169 | pgoff_t next = 0; | |
3170 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
3171 | PAGE_CACHE_SHIFT; | |
3172 | struct zone *zone; | |
3173 | struct pagevec pvec; | |
3174 | ||
3175 | if (mapping->nrpages == 0) | |
3176 | return; | |
3177 | ||
3178 | pagevec_init(&pvec, 0); | |
3179 | while (next < end && | |
3180 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
3181 | int i; | |
3182 | int pg_scanned = 0; | |
3183 | ||
3184 | zone = NULL; | |
3185 | ||
3186 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
3187 | struct page *page = pvec.pages[i]; | |
3188 | pgoff_t page_index = page->index; | |
3189 | struct zone *pagezone = page_zone(page); | |
3190 | ||
3191 | pg_scanned++; | |
3192 | if (page_index > next) | |
3193 | next = page_index; | |
3194 | next++; | |
3195 | ||
3196 | if (pagezone != zone) { | |
3197 | if (zone) | |
3198 | spin_unlock_irq(&zone->lru_lock); | |
3199 | zone = pagezone; | |
3200 | spin_lock_irq(&zone->lru_lock); | |
3201 | } | |
3202 | ||
3203 | if (PageLRU(page) && PageUnevictable(page)) | |
3204 | check_move_unevictable_page(page, zone); | |
3205 | } | |
3206 | if (zone) | |
3207 | spin_unlock_irq(&zone->lru_lock); | |
3208 | pagevec_release(&pvec); | |
3209 | ||
3210 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
3211 | } | |
3212 | ||
3213 | } | |
af936a16 LS |
3214 | |
3215 | /** | |
3216 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
3217 | * @zone - zone of which to scan the unevictable list | |
3218 | * | |
3219 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
3220 | * evictable. Move those that have to @zone's inactive list where they | |
3221 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
3222 | * to reactivate them. Pages that are still unevictable are rotated | |
3223 | * back onto @zone's unevictable list. | |
3224 | */ | |
3225 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 3226 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
3227 | { |
3228 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
3229 | unsigned long scan; | |
3230 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
3231 | ||
3232 | while (nr_to_scan > 0) { | |
3233 | unsigned long batch_size = min(nr_to_scan, | |
3234 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
3235 | ||
3236 | spin_lock_irq(&zone->lru_lock); | |
3237 | for (scan = 0; scan < batch_size; scan++) { | |
3238 | struct page *page = lru_to_page(l_unevictable); | |
3239 | ||
3240 | if (!trylock_page(page)) | |
3241 | continue; | |
3242 | ||
3243 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3244 | ||
3245 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3246 | check_move_unevictable_page(page, zone); | |
3247 | ||
3248 | unlock_page(page); | |
3249 | } | |
3250 | spin_unlock_irq(&zone->lru_lock); | |
3251 | ||
3252 | nr_to_scan -= batch_size; | |
3253 | } | |
3254 | } | |
3255 | ||
3256 | ||
3257 | /** | |
3258 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3259 | * | |
3260 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3261 | * pages that have become evictable. Move those back to the zones' | |
3262 | * inactive list where they become candidates for reclaim. | |
3263 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3264 | * and we add swap to the system. As such, it runs in the context of a task | |
3265 | * that has possibly/probably made some previously unevictable pages | |
3266 | * evictable. | |
3267 | */ | |
ff30153b | 3268 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3269 | { |
3270 | struct zone *zone; | |
3271 | ||
3272 | for_each_zone(zone) { | |
3273 | scan_zone_unevictable_pages(zone); | |
3274 | } | |
3275 | } | |
3276 | ||
3277 | /* | |
3278 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3279 | * all nodes' unevictable lists for evictable pages | |
3280 | */ | |
3281 | unsigned long scan_unevictable_pages; | |
3282 | ||
3283 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3284 | void __user *buffer, |
af936a16 LS |
3285 | size_t *length, loff_t *ppos) |
3286 | { | |
8d65af78 | 3287 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3288 | |
3289 | if (write && *(unsigned long *)table->data) | |
3290 | scan_all_zones_unevictable_pages(); | |
3291 | ||
3292 | scan_unevictable_pages = 0; | |
3293 | return 0; | |
3294 | } | |
3295 | ||
e4455abb | 3296 | #ifdef CONFIG_NUMA |
af936a16 LS |
3297 | /* |
3298 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3299 | * a specified node's per zone unevictable lists for evictable pages. | |
3300 | */ | |
3301 | ||
3302 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3303 | struct sysdev_attribute *attr, | |
3304 | char *buf) | |
3305 | { | |
3306 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3307 | } | |
3308 | ||
3309 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3310 | struct sysdev_attribute *attr, | |
3311 | const char *buf, size_t count) | |
3312 | { | |
3313 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3314 | struct zone *zone; | |
3315 | unsigned long res; | |
3316 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3317 | ||
3318 | if (!req) | |
3319 | return 1; /* zero is no-op */ | |
3320 | ||
3321 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3322 | if (!populated_zone(zone)) | |
3323 | continue; | |
3324 | scan_zone_unevictable_pages(zone); | |
3325 | } | |
3326 | return 1; | |
3327 | } | |
3328 | ||
3329 | ||
3330 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3331 | read_scan_unevictable_node, | |
3332 | write_scan_unevictable_node); | |
3333 | ||
3334 | int scan_unevictable_register_node(struct node *node) | |
3335 | { | |
3336 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3337 | } | |
3338 | ||
3339 | void scan_unevictable_unregister_node(struct node *node) | |
3340 | { | |
3341 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3342 | } | |
e4455abb | 3343 | #endif |