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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/swap.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
183ff22b | 8 | * This file contains the default values for the operation of the |
1da177e4 LT |
9 | * Linux VM subsystem. Fine-tuning documentation can be found in |
10 | * Documentation/sysctl/vm.txt. | |
11 | * Started 18.12.91 | |
12 | * Swap aging added 23.2.95, Stephen Tweedie. | |
13 | * Buffermem limits added 12.3.98, Rik van Riel. | |
14 | */ | |
15 | ||
16 | #include <linux/mm.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/kernel_stat.h> | |
19 | #include <linux/swap.h> | |
20 | #include <linux/mman.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/pagevec.h> | |
23 | #include <linux/init.h> | |
b95f1b31 | 24 | #include <linux/export.h> |
1da177e4 | 25 | #include <linux/mm_inline.h> |
1da177e4 LT |
26 | #include <linux/percpu_counter.h> |
27 | #include <linux/percpu.h> | |
28 | #include <linux/cpu.h> | |
29 | #include <linux/notifier.h> | |
e0bf68dd | 30 | #include <linux/backing-dev.h> |
66e1707b | 31 | #include <linux/memcontrol.h> |
5a0e3ad6 | 32 | #include <linux/gfp.h> |
a27bb332 | 33 | #include <linux/uio.h> |
7cb2ef56 | 34 | #include <linux/hugetlb.h> |
1da177e4 | 35 | |
64d6519d LS |
36 | #include "internal.h" |
37 | ||
c6286c98 MG |
38 | #define CREATE_TRACE_POINTS |
39 | #include <trace/events/pagemap.h> | |
40 | ||
1da177e4 LT |
41 | /* How many pages do we try to swap or page in/out together? */ |
42 | int page_cluster; | |
43 | ||
13f7f789 | 44 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); |
f84f9504 | 45 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
31560180 | 46 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); |
902aaed0 | 47 | |
b221385b AB |
48 | /* |
49 | * This path almost never happens for VM activity - pages are normally | |
50 | * freed via pagevecs. But it gets used by networking. | |
51 | */ | |
920c7a5d | 52 | static void __page_cache_release(struct page *page) |
b221385b AB |
53 | { |
54 | if (PageLRU(page)) { | |
b221385b | 55 | struct zone *zone = page_zone(page); |
fa9add64 HD |
56 | struct lruvec *lruvec; |
57 | unsigned long flags; | |
b221385b AB |
58 | |
59 | spin_lock_irqsave(&zone->lru_lock, flags); | |
fa9add64 | 60 | lruvec = mem_cgroup_page_lruvec(page, zone); |
b221385b AB |
61 | VM_BUG_ON(!PageLRU(page)); |
62 | __ClearPageLRU(page); | |
fa9add64 | 63 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); |
b221385b AB |
64 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
65 | } | |
91807063 AA |
66 | } |
67 | ||
68 | static void __put_single_page(struct page *page) | |
69 | { | |
70 | __page_cache_release(page); | |
fc91668e | 71 | free_hot_cold_page(page, 0); |
b221385b AB |
72 | } |
73 | ||
91807063 | 74 | static void __put_compound_page(struct page *page) |
1da177e4 | 75 | { |
91807063 | 76 | compound_page_dtor *dtor; |
1da177e4 | 77 | |
91807063 AA |
78 | __page_cache_release(page); |
79 | dtor = get_compound_page_dtor(page); | |
80 | (*dtor)(page); | |
81 | } | |
82 | ||
83 | static void put_compound_page(struct page *page) | |
84 | { | |
85 | if (unlikely(PageTail(page))) { | |
86 | /* __split_huge_page_refcount can run under us */ | |
70b50f94 AA |
87 | struct page *page_head = compound_trans_head(page); |
88 | ||
ebf360f9 AA |
89 | /* |
90 | * THP can not break up slab pages so avoid taking | |
44518d2b AA |
91 | * compound_lock() and skip the tail page refcounting |
92 | * (in _mapcount) too. Slab performs non-atomic bit | |
93 | * ops on page->flags for better performance. In | |
ebf360f9 AA |
94 | * particular slab_unlock() in slub used to be a hot |
95 | * path. It is still hot on arches that do not support | |
96 | * this_cpu_cmpxchg_double(). | |
97 | * | |
98 | * If "page" is part of a slab or hugetlbfs page it | |
99 | * cannot be splitted and the head page cannot change | |
100 | * from under us. And if "page" is part of a THP page | |
101 | * under splitting, if the head page pointed by the | |
102 | * THP tail isn't a THP head anymore, we'll find | |
103 | * PageTail clear after smp_rmb() and we'll treat it | |
104 | * as a single page. | |
105 | */ | |
44518d2b | 106 | if (!__compound_tail_refcounted(page_head)) { |
ebf360f9 AA |
107 | /* |
108 | * If "page" is a THP tail, we must read the tail page | |
109 | * flags after the head page flags. The | |
110 | * split_huge_page side enforces write memory | |
111 | * barriers between clearing PageTail and before the | |
112 | * head page can be freed and reallocated. | |
113 | */ | |
114 | smp_rmb(); | |
115 | if (likely(PageTail(page))) { | |
116 | /* | |
117 | * __split_huge_page_refcount | |
118 | * cannot race here. | |
119 | */ | |
120 | VM_BUG_ON(!PageHead(page_head)); | |
44518d2b AA |
121 | VM_BUG_ON(page_mapcount(page) != 0); |
122 | if (put_page_testzero(page_head)) { | |
123 | /* | |
124 | * If this is the tail of a | |
125 | * slab compound page, the | |
126 | * tail pin must not be the | |
127 | * last reference held on the | |
128 | * page, because the PG_slab | |
129 | * cannot be cleared before | |
130 | * all tail pins (which skips | |
131 | * the _mapcount tail | |
132 | * refcounting) have been | |
133 | * released. For hugetlbfs the | |
134 | * tail pin may be the last | |
135 | * reference on the page | |
136 | * instead, because | |
137 | * PageHeadHuge will not go | |
138 | * away until the compound | |
139 | * page enters the buddy | |
140 | * allocator. | |
141 | */ | |
142 | VM_BUG_ON(PageSlab(page_head)); | |
ebf360f9 | 143 | __put_compound_page(page_head); |
44518d2b | 144 | } |
ebf360f9 AA |
145 | return; |
146 | } else | |
147 | /* | |
148 | * __split_huge_page_refcount | |
149 | * run before us, "page" was a | |
150 | * THP tail. The split | |
151 | * page_head has been freed | |
152 | * and reallocated as slab or | |
153 | * hugetlbfs page of smaller | |
154 | * order (only possible if | |
155 | * reallocated as slab on | |
156 | * x86). | |
157 | */ | |
158 | goto out_put_single; | |
159 | } | |
160 | ||
70b50f94 AA |
161 | if (likely(page != page_head && |
162 | get_page_unless_zero(page_head))) { | |
91807063 | 163 | unsigned long flags; |
5bf5f03c | 164 | |
91807063 | 165 | /* |
70b50f94 AA |
166 | * page_head wasn't a dangling pointer but it |
167 | * may not be a head page anymore by the time | |
168 | * we obtain the lock. That is ok as long as it | |
169 | * can't be freed from under us. | |
91807063 | 170 | */ |
91807063 AA |
171 | flags = compound_lock_irqsave(page_head); |
172 | if (unlikely(!PageTail(page))) { | |
173 | /* __split_huge_page_refcount run before us */ | |
174 | compound_unlock_irqrestore(page_head, flags); | |
27c73ae7 AA |
175 | if (put_page_testzero(page_head)) { |
176 | /* | |
177 | * The head page may have been | |
178 | * freed and reallocated as a | |
179 | * compound page of smaller | |
180 | * order and then freed again. | |
181 | * All we know is that it | |
182 | * cannot have become: a THP | |
183 | * page, a compound page of | |
184 | * higher order, a tail page. | |
185 | * That is because we still | |
186 | * hold the refcount of the | |
187 | * split THP tail and | |
188 | * page_head was the THP head | |
189 | * before the split. | |
190 | */ | |
191 | if (PageHead(page_head)) | |
192 | __put_compound_page(page_head); | |
193 | else | |
194 | __put_single_page(page_head); | |
195 | } | |
5bf5f03c | 196 | out_put_single: |
91807063 AA |
197 | if (put_page_testzero(page)) |
198 | __put_single_page(page); | |
199 | return; | |
200 | } | |
201 | VM_BUG_ON(page_head != page->first_page); | |
202 | /* | |
203 | * We can release the refcount taken by | |
70b50f94 AA |
204 | * get_page_unless_zero() now that |
205 | * __split_huge_page_refcount() is blocked on | |
206 | * the compound_lock. | |
91807063 AA |
207 | */ |
208 | if (put_page_testzero(page_head)) | |
209 | VM_BUG_ON(1); | |
210 | /* __split_huge_page_refcount will wait now */ | |
70b50f94 AA |
211 | VM_BUG_ON(page_mapcount(page) <= 0); |
212 | atomic_dec(&page->_mapcount); | |
91807063 | 213 | VM_BUG_ON(atomic_read(&page_head->_count) <= 0); |
70b50f94 | 214 | VM_BUG_ON(atomic_read(&page->_count) != 0); |
91807063 | 215 | compound_unlock_irqrestore(page_head, flags); |
5bf5f03c | 216 | |
a95a82e9 AA |
217 | if (put_page_testzero(page_head)) { |
218 | if (PageHead(page_head)) | |
219 | __put_compound_page(page_head); | |
220 | else | |
221 | __put_single_page(page_head); | |
222 | } | |
91807063 AA |
223 | } else { |
224 | /* page_head is a dangling pointer */ | |
225 | VM_BUG_ON(PageTail(page)); | |
226 | goto out_put_single; | |
227 | } | |
228 | } else if (put_page_testzero(page)) { | |
229 | if (PageHead(page)) | |
230 | __put_compound_page(page); | |
231 | else | |
232 | __put_single_page(page); | |
1da177e4 | 233 | } |
8519fb30 NP |
234 | } |
235 | ||
236 | void put_page(struct page *page) | |
237 | { | |
238 | if (unlikely(PageCompound(page))) | |
239 | put_compound_page(page); | |
240 | else if (put_page_testzero(page)) | |
91807063 | 241 | __put_single_page(page); |
1da177e4 LT |
242 | } |
243 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 244 | |
70b50f94 AA |
245 | /* |
246 | * This function is exported but must not be called by anything other | |
247 | * than get_page(). It implements the slow path of get_page(). | |
248 | */ | |
249 | bool __get_page_tail(struct page *page) | |
250 | { | |
251 | /* | |
252 | * This takes care of get_page() if run on a tail page | |
253 | * returned by one of the get_user_pages/follow_page variants. | |
254 | * get_user_pages/follow_page itself doesn't need the compound | |
255 | * lock because it runs __get_page_tail_foll() under the | |
256 | * proper PT lock that already serializes against | |
257 | * split_huge_page(). | |
258 | */ | |
27c73ae7 | 259 | unsigned long flags; |
ebf360f9 | 260 | bool got; |
27c73ae7 | 261 | struct page *page_head = compound_trans_head(page); |
70b50f94 | 262 | |
ebf360f9 AA |
263 | /* Ref to put_compound_page() comment. */ |
264 | if (PageSlab(page_head) || PageHeadHuge(page_head)) { | |
265 | smp_rmb(); | |
266 | if (likely(PageTail(page))) { | |
267 | /* | |
268 | * This is a hugetlbfs page or a slab | |
269 | * page. __split_huge_page_refcount | |
270 | * cannot race here. | |
271 | */ | |
272 | VM_BUG_ON(!PageHead(page_head)); | |
273 | __get_page_tail_foll(page, true); | |
274 | return true; | |
275 | } else { | |
276 | /* | |
277 | * __split_huge_page_refcount run | |
278 | * before us, "page" was a THP | |
279 | * tail. The split page_head has been | |
280 | * freed and reallocated as slab or | |
281 | * hugetlbfs page of smaller order | |
282 | * (only possible if reallocated as | |
283 | * slab on x86). | |
284 | */ | |
285 | return false; | |
27c73ae7 | 286 | } |
ebf360f9 | 287 | } |
27c73ae7 | 288 | |
ebf360f9 AA |
289 | got = false; |
290 | if (likely(page != page_head && get_page_unless_zero(page_head))) { | |
27c73ae7 AA |
291 | /* |
292 | * page_head wasn't a dangling pointer but it | |
293 | * may not be a head page anymore by the time | |
294 | * we obtain the lock. That is ok as long as it | |
295 | * can't be freed from under us. | |
296 | */ | |
297 | flags = compound_lock_irqsave(page_head); | |
298 | /* here __split_huge_page_refcount won't run anymore */ | |
299 | if (likely(PageTail(page))) { | |
300 | __get_page_tail_foll(page, false); | |
301 | got = true; | |
5bf5f03c | 302 | } |
27c73ae7 AA |
303 | compound_unlock_irqrestore(page_head, flags); |
304 | if (unlikely(!got)) | |
305 | put_page(page_head); | |
70b50f94 AA |
306 | } |
307 | return got; | |
308 | } | |
309 | EXPORT_SYMBOL(__get_page_tail); | |
310 | ||
1d7ea732 | 311 | /** |
7682486b RD |
312 | * put_pages_list() - release a list of pages |
313 | * @pages: list of pages threaded on page->lru | |
1d7ea732 AZ |
314 | * |
315 | * Release a list of pages which are strung together on page.lru. Currently | |
316 | * used by read_cache_pages() and related error recovery code. | |
1d7ea732 AZ |
317 | */ |
318 | void put_pages_list(struct list_head *pages) | |
319 | { | |
320 | while (!list_empty(pages)) { | |
321 | struct page *victim; | |
322 | ||
323 | victim = list_entry(pages->prev, struct page, lru); | |
324 | list_del(&victim->lru); | |
325 | page_cache_release(victim); | |
326 | } | |
327 | } | |
328 | EXPORT_SYMBOL(put_pages_list); | |
329 | ||
18022c5d MG |
330 | /* |
331 | * get_kernel_pages() - pin kernel pages in memory | |
332 | * @kiov: An array of struct kvec structures | |
333 | * @nr_segs: number of segments to pin | |
334 | * @write: pinning for read/write, currently ignored | |
335 | * @pages: array that receives pointers to the pages pinned. | |
336 | * Should be at least nr_segs long. | |
337 | * | |
338 | * Returns number of pages pinned. This may be fewer than the number | |
339 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
340 | * were pinned, returns -errno. Each page returned must be released | |
341 | * with a put_page() call when it is finished with. | |
342 | */ | |
343 | int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, | |
344 | struct page **pages) | |
345 | { | |
346 | int seg; | |
347 | ||
348 | for (seg = 0; seg < nr_segs; seg++) { | |
349 | if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) | |
350 | return seg; | |
351 | ||
5a178119 | 352 | pages[seg] = kmap_to_page(kiov[seg].iov_base); |
18022c5d MG |
353 | page_cache_get(pages[seg]); |
354 | } | |
355 | ||
356 | return seg; | |
357 | } | |
358 | EXPORT_SYMBOL_GPL(get_kernel_pages); | |
359 | ||
360 | /* | |
361 | * get_kernel_page() - pin a kernel page in memory | |
362 | * @start: starting kernel address | |
363 | * @write: pinning for read/write, currently ignored | |
364 | * @pages: array that receives pointer to the page pinned. | |
365 | * Must be at least nr_segs long. | |
366 | * | |
367 | * Returns 1 if page is pinned. If the page was not pinned, returns | |
368 | * -errno. The page returned must be released with a put_page() call | |
369 | * when it is finished with. | |
370 | */ | |
371 | int get_kernel_page(unsigned long start, int write, struct page **pages) | |
372 | { | |
373 | const struct kvec kiov = { | |
374 | .iov_base = (void *)start, | |
375 | .iov_len = PAGE_SIZE | |
376 | }; | |
377 | ||
378 | return get_kernel_pages(&kiov, 1, write, pages); | |
379 | } | |
380 | EXPORT_SYMBOL_GPL(get_kernel_page); | |
381 | ||
3dd7ae8e | 382 | static void pagevec_lru_move_fn(struct pagevec *pvec, |
fa9add64 HD |
383 | void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg), |
384 | void *arg) | |
902aaed0 HH |
385 | { |
386 | int i; | |
902aaed0 | 387 | struct zone *zone = NULL; |
fa9add64 | 388 | struct lruvec *lruvec; |
3dd7ae8e | 389 | unsigned long flags = 0; |
902aaed0 HH |
390 | |
391 | for (i = 0; i < pagevec_count(pvec); i++) { | |
392 | struct page *page = pvec->pages[i]; | |
393 | struct zone *pagezone = page_zone(page); | |
394 | ||
395 | if (pagezone != zone) { | |
396 | if (zone) | |
3dd7ae8e | 397 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
902aaed0 | 398 | zone = pagezone; |
3dd7ae8e | 399 | spin_lock_irqsave(&zone->lru_lock, flags); |
902aaed0 | 400 | } |
3dd7ae8e | 401 | |
fa9add64 HD |
402 | lruvec = mem_cgroup_page_lruvec(page, zone); |
403 | (*move_fn)(page, lruvec, arg); | |
902aaed0 HH |
404 | } |
405 | if (zone) | |
3dd7ae8e | 406 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
83896fb5 LT |
407 | release_pages(pvec->pages, pvec->nr, pvec->cold); |
408 | pagevec_reinit(pvec); | |
d8505dee SL |
409 | } |
410 | ||
fa9add64 HD |
411 | static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec, |
412 | void *arg) | |
3dd7ae8e SL |
413 | { |
414 | int *pgmoved = arg; | |
3dd7ae8e SL |
415 | |
416 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
417 | enum lru_list lru = page_lru_base_type(page); | |
925b7673 | 418 | list_move_tail(&page->lru, &lruvec->lists[lru]); |
3dd7ae8e SL |
419 | (*pgmoved)++; |
420 | } | |
421 | } | |
422 | ||
423 | /* | |
424 | * pagevec_move_tail() must be called with IRQ disabled. | |
425 | * Otherwise this may cause nasty races. | |
426 | */ | |
427 | static void pagevec_move_tail(struct pagevec *pvec) | |
428 | { | |
429 | int pgmoved = 0; | |
430 | ||
431 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); | |
432 | __count_vm_events(PGROTATED, pgmoved); | |
433 | } | |
434 | ||
1da177e4 LT |
435 | /* |
436 | * Writeback is about to end against a page which has been marked for immediate | |
437 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
902aaed0 | 438 | * inactive list. |
1da177e4 | 439 | */ |
3dd7ae8e | 440 | void rotate_reclaimable_page(struct page *page) |
1da177e4 | 441 | { |
ac6aadb2 | 442 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
894bc310 | 443 | !PageUnevictable(page) && PageLRU(page)) { |
ac6aadb2 MS |
444 | struct pagevec *pvec; |
445 | unsigned long flags; | |
446 | ||
447 | page_cache_get(page); | |
448 | local_irq_save(flags); | |
449 | pvec = &__get_cpu_var(lru_rotate_pvecs); | |
450 | if (!pagevec_add(pvec, page)) | |
451 | pagevec_move_tail(pvec); | |
452 | local_irq_restore(flags); | |
453 | } | |
1da177e4 LT |
454 | } |
455 | ||
fa9add64 | 456 | static void update_page_reclaim_stat(struct lruvec *lruvec, |
3e2f41f1 KM |
457 | int file, int rotated) |
458 | { | |
fa9add64 | 459 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; |
3e2f41f1 KM |
460 | |
461 | reclaim_stat->recent_scanned[file]++; | |
462 | if (rotated) | |
463 | reclaim_stat->recent_rotated[file]++; | |
3e2f41f1 KM |
464 | } |
465 | ||
fa9add64 HD |
466 | static void __activate_page(struct page *page, struct lruvec *lruvec, |
467 | void *arg) | |
1da177e4 | 468 | { |
744ed144 | 469 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
7a608572 LT |
470 | int file = page_is_file_cache(page); |
471 | int lru = page_lru_base_type(page); | |
744ed144 | 472 | |
fa9add64 | 473 | del_page_from_lru_list(page, lruvec, lru); |
7a608572 LT |
474 | SetPageActive(page); |
475 | lru += LRU_ACTIVE; | |
fa9add64 | 476 | add_page_to_lru_list(page, lruvec, lru); |
c6286c98 | 477 | trace_mm_lru_activate(page, page_to_pfn(page)); |
4f98a2fe | 478 | |
fa9add64 HD |
479 | __count_vm_event(PGACTIVATE); |
480 | update_page_reclaim_stat(lruvec, file, 1); | |
1da177e4 | 481 | } |
eb709b0d SL |
482 | } |
483 | ||
484 | #ifdef CONFIG_SMP | |
485 | static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); | |
486 | ||
487 | static void activate_page_drain(int cpu) | |
488 | { | |
489 | struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); | |
490 | ||
491 | if (pagevec_count(pvec)) | |
492 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
493 | } | |
494 | ||
5fbc4616 CM |
495 | static bool need_activate_page_drain(int cpu) |
496 | { | |
497 | return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0; | |
498 | } | |
499 | ||
eb709b0d SL |
500 | void activate_page(struct page *page) |
501 | { | |
502 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
503 | struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); | |
504 | ||
505 | page_cache_get(page); | |
506 | if (!pagevec_add(pvec, page)) | |
507 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
508 | put_cpu_var(activate_page_pvecs); | |
509 | } | |
510 | } | |
511 | ||
512 | #else | |
513 | static inline void activate_page_drain(int cpu) | |
514 | { | |
515 | } | |
516 | ||
5fbc4616 CM |
517 | static bool need_activate_page_drain(int cpu) |
518 | { | |
519 | return false; | |
520 | } | |
521 | ||
eb709b0d SL |
522 | void activate_page(struct page *page) |
523 | { | |
524 | struct zone *zone = page_zone(page); | |
525 | ||
526 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 | 527 | __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL); |
1da177e4 LT |
528 | spin_unlock_irq(&zone->lru_lock); |
529 | } | |
eb709b0d | 530 | #endif |
1da177e4 | 531 | |
059285a2 MG |
532 | static void __lru_cache_activate_page(struct page *page) |
533 | { | |
534 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); | |
535 | int i; | |
536 | ||
537 | /* | |
538 | * Search backwards on the optimistic assumption that the page being | |
539 | * activated has just been added to this pagevec. Note that only | |
540 | * the local pagevec is examined as a !PageLRU page could be in the | |
541 | * process of being released, reclaimed, migrated or on a remote | |
542 | * pagevec that is currently being drained. Furthermore, marking | |
543 | * a remote pagevec's page PageActive potentially hits a race where | |
544 | * a page is marked PageActive just after it is added to the inactive | |
545 | * list causing accounting errors and BUG_ON checks to trigger. | |
546 | */ | |
547 | for (i = pagevec_count(pvec) - 1; i >= 0; i--) { | |
548 | struct page *pagevec_page = pvec->pages[i]; | |
549 | ||
550 | if (pagevec_page == page) { | |
551 | SetPageActive(page); | |
552 | break; | |
553 | } | |
554 | } | |
555 | ||
556 | put_cpu_var(lru_add_pvec); | |
557 | } | |
558 | ||
1da177e4 LT |
559 | /* |
560 | * Mark a page as having seen activity. | |
561 | * | |
562 | * inactive,unreferenced -> inactive,referenced | |
563 | * inactive,referenced -> active,unreferenced | |
564 | * active,unreferenced -> active,referenced | |
565 | */ | |
920c7a5d | 566 | void mark_page_accessed(struct page *page) |
1da177e4 | 567 | { |
894bc310 | 568 | if (!PageActive(page) && !PageUnevictable(page) && |
059285a2 MG |
569 | PageReferenced(page)) { |
570 | ||
571 | /* | |
572 | * If the page is on the LRU, queue it for activation via | |
573 | * activate_page_pvecs. Otherwise, assume the page is on a | |
574 | * pagevec, mark it active and it'll be moved to the active | |
575 | * LRU on the next drain. | |
576 | */ | |
577 | if (PageLRU(page)) | |
578 | activate_page(page); | |
579 | else | |
580 | __lru_cache_activate_page(page); | |
1da177e4 LT |
581 | ClearPageReferenced(page); |
582 | } else if (!PageReferenced(page)) { | |
583 | SetPageReferenced(page); | |
584 | } | |
585 | } | |
1da177e4 LT |
586 | EXPORT_SYMBOL(mark_page_accessed); |
587 | ||
d741c9cd | 588 | /* |
13f7f789 MG |
589 | * Queue the page for addition to the LRU via pagevec. The decision on whether |
590 | * to add the page to the [in]active [file|anon] list is deferred until the | |
591 | * pagevec is drained. This gives a chance for the caller of __lru_cache_add() | |
592 | * have the page added to the active list using mark_page_accessed(). | |
d741c9cd | 593 | */ |
c53954a0 | 594 | void __lru_cache_add(struct page *page) |
1da177e4 | 595 | { |
13f7f789 MG |
596 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); |
597 | ||
1da177e4 | 598 | page_cache_get(page); |
d741c9cd | 599 | if (!pagevec_space(pvec)) |
a0b8cab3 | 600 | __pagevec_lru_add(pvec); |
d741c9cd | 601 | pagevec_add(pvec, page); |
13f7f789 | 602 | put_cpu_var(lru_add_pvec); |
1da177e4 | 603 | } |
47846b06 | 604 | EXPORT_SYMBOL(__lru_cache_add); |
1da177e4 | 605 | |
f04e9ebb | 606 | /** |
c53954a0 | 607 | * lru_cache_add - add a page to a page list |
f04e9ebb | 608 | * @page: the page to be added to the LRU. |
f04e9ebb | 609 | */ |
c53954a0 | 610 | void lru_cache_add(struct page *page) |
1da177e4 | 611 | { |
ef2a2cbd | 612 | VM_BUG_ON(PageActive(page) && PageUnevictable(page)); |
13f7f789 | 613 | VM_BUG_ON(PageLRU(page)); |
c53954a0 | 614 | __lru_cache_add(page); |
1da177e4 LT |
615 | } |
616 | ||
894bc310 LS |
617 | /** |
618 | * add_page_to_unevictable_list - add a page to the unevictable list | |
619 | * @page: the page to be added to the unevictable list | |
620 | * | |
621 | * Add page directly to its zone's unevictable list. To avoid races with | |
622 | * tasks that might be making the page evictable, through eg. munlock, | |
623 | * munmap or exit, while it's not on the lru, we want to add the page | |
624 | * while it's locked or otherwise "invisible" to other tasks. This is | |
625 | * difficult to do when using the pagevec cache, so bypass that. | |
626 | */ | |
627 | void add_page_to_unevictable_list(struct page *page) | |
628 | { | |
629 | struct zone *zone = page_zone(page); | |
fa9add64 | 630 | struct lruvec *lruvec; |
894bc310 LS |
631 | |
632 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 | 633 | lruvec = mem_cgroup_page_lruvec(page, zone); |
ef2a2cbd | 634 | ClearPageActive(page); |
894bc310 LS |
635 | SetPageUnevictable(page); |
636 | SetPageLRU(page); | |
fa9add64 | 637 | add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE); |
894bc310 LS |
638 | spin_unlock_irq(&zone->lru_lock); |
639 | } | |
640 | ||
31560180 MK |
641 | /* |
642 | * If the page can not be invalidated, it is moved to the | |
643 | * inactive list to speed up its reclaim. It is moved to the | |
644 | * head of the list, rather than the tail, to give the flusher | |
645 | * threads some time to write it out, as this is much more | |
646 | * effective than the single-page writeout from reclaim. | |
278df9f4 MK |
647 | * |
648 | * If the page isn't page_mapped and dirty/writeback, the page | |
649 | * could reclaim asap using PG_reclaim. | |
650 | * | |
651 | * 1. active, mapped page -> none | |
652 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim | |
653 | * 3. inactive, mapped page -> none | |
654 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim | |
655 | * 5. inactive, clean -> inactive, tail | |
656 | * 6. Others -> none | |
657 | * | |
658 | * In 4, why it moves inactive's head, the VM expects the page would | |
659 | * be write it out by flusher threads as this is much more effective | |
660 | * than the single-page writeout from reclaim. | |
31560180 | 661 | */ |
fa9add64 HD |
662 | static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, |
663 | void *arg) | |
31560180 MK |
664 | { |
665 | int lru, file; | |
278df9f4 | 666 | bool active; |
31560180 | 667 | |
278df9f4 | 668 | if (!PageLRU(page)) |
31560180 MK |
669 | return; |
670 | ||
bad49d9c MK |
671 | if (PageUnevictable(page)) |
672 | return; | |
673 | ||
31560180 MK |
674 | /* Some processes are using the page */ |
675 | if (page_mapped(page)) | |
676 | return; | |
677 | ||
278df9f4 | 678 | active = PageActive(page); |
31560180 MK |
679 | file = page_is_file_cache(page); |
680 | lru = page_lru_base_type(page); | |
fa9add64 HD |
681 | |
682 | del_page_from_lru_list(page, lruvec, lru + active); | |
31560180 MK |
683 | ClearPageActive(page); |
684 | ClearPageReferenced(page); | |
fa9add64 | 685 | add_page_to_lru_list(page, lruvec, lru); |
31560180 | 686 | |
278df9f4 MK |
687 | if (PageWriteback(page) || PageDirty(page)) { |
688 | /* | |
689 | * PG_reclaim could be raced with end_page_writeback | |
690 | * It can make readahead confusing. But race window | |
691 | * is _really_ small and it's non-critical problem. | |
692 | */ | |
693 | SetPageReclaim(page); | |
694 | } else { | |
695 | /* | |
696 | * The page's writeback ends up during pagevec | |
697 | * We moves tha page into tail of inactive. | |
698 | */ | |
925b7673 | 699 | list_move_tail(&page->lru, &lruvec->lists[lru]); |
278df9f4 MK |
700 | __count_vm_event(PGROTATED); |
701 | } | |
702 | ||
703 | if (active) | |
704 | __count_vm_event(PGDEACTIVATE); | |
fa9add64 | 705 | update_page_reclaim_stat(lruvec, file, 0); |
31560180 MK |
706 | } |
707 | ||
902aaed0 HH |
708 | /* |
709 | * Drain pages out of the cpu's pagevecs. | |
710 | * Either "cpu" is the current CPU, and preemption has already been | |
711 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
712 | */ | |
f0cb3c76 | 713 | void lru_add_drain_cpu(int cpu) |
1da177e4 | 714 | { |
13f7f789 | 715 | struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu); |
1da177e4 | 716 | |
13f7f789 | 717 | if (pagevec_count(pvec)) |
a0b8cab3 | 718 | __pagevec_lru_add(pvec); |
902aaed0 HH |
719 | |
720 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
721 | if (pagevec_count(pvec)) { | |
722 | unsigned long flags; | |
723 | ||
724 | /* No harm done if a racing interrupt already did this */ | |
725 | local_irq_save(flags); | |
726 | pagevec_move_tail(pvec); | |
727 | local_irq_restore(flags); | |
728 | } | |
31560180 MK |
729 | |
730 | pvec = &per_cpu(lru_deactivate_pvecs, cpu); | |
731 | if (pagevec_count(pvec)) | |
3dd7ae8e | 732 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
eb709b0d SL |
733 | |
734 | activate_page_drain(cpu); | |
31560180 MK |
735 | } |
736 | ||
737 | /** | |
738 | * deactivate_page - forcefully deactivate a page | |
739 | * @page: page to deactivate | |
740 | * | |
741 | * This function hints the VM that @page is a good reclaim candidate, | |
742 | * for example if its invalidation fails due to the page being dirty | |
743 | * or under writeback. | |
744 | */ | |
745 | void deactivate_page(struct page *page) | |
746 | { | |
821ed6bb MK |
747 | /* |
748 | * In a workload with many unevictable page such as mprotect, unevictable | |
749 | * page deactivation for accelerating reclaim is pointless. | |
750 | */ | |
751 | if (PageUnevictable(page)) | |
752 | return; | |
753 | ||
31560180 MK |
754 | if (likely(get_page_unless_zero(page))) { |
755 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); | |
756 | ||
757 | if (!pagevec_add(pvec, page)) | |
3dd7ae8e | 758 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
31560180 MK |
759 | put_cpu_var(lru_deactivate_pvecs); |
760 | } | |
80bfed90 AM |
761 | } |
762 | ||
763 | void lru_add_drain(void) | |
764 | { | |
f0cb3c76 | 765 | lru_add_drain_cpu(get_cpu()); |
80bfed90 | 766 | put_cpu(); |
1da177e4 LT |
767 | } |
768 | ||
c4028958 | 769 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
053837fc NP |
770 | { |
771 | lru_add_drain(); | |
772 | } | |
773 | ||
5fbc4616 CM |
774 | static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); |
775 | ||
776 | void lru_add_drain_all(void) | |
053837fc | 777 | { |
5fbc4616 CM |
778 | static DEFINE_MUTEX(lock); |
779 | static struct cpumask has_work; | |
780 | int cpu; | |
781 | ||
782 | mutex_lock(&lock); | |
783 | get_online_cpus(); | |
784 | cpumask_clear(&has_work); | |
785 | ||
786 | for_each_online_cpu(cpu) { | |
787 | struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); | |
788 | ||
789 | if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || | |
790 | pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || | |
791 | pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || | |
792 | need_activate_page_drain(cpu)) { | |
793 | INIT_WORK(work, lru_add_drain_per_cpu); | |
794 | schedule_work_on(cpu, work); | |
795 | cpumask_set_cpu(cpu, &has_work); | |
796 | } | |
797 | } | |
798 | ||
799 | for_each_cpu(cpu, &has_work) | |
800 | flush_work(&per_cpu(lru_add_drain_work, cpu)); | |
801 | ||
802 | put_online_cpus(); | |
803 | mutex_unlock(&lock); | |
053837fc NP |
804 | } |
805 | ||
1da177e4 LT |
806 | /* |
807 | * Batched page_cache_release(). Decrement the reference count on all the | |
808 | * passed pages. If it fell to zero then remove the page from the LRU and | |
809 | * free it. | |
810 | * | |
811 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
812 | * for the remainder of the operation. | |
813 | * | |
ab33dc09 FLVC |
814 | * The locking in this function is against shrink_inactive_list(): we recheck |
815 | * the page count inside the lock to see whether shrink_inactive_list() | |
816 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() | |
817 | * will free it. | |
1da177e4 LT |
818 | */ |
819 | void release_pages(struct page **pages, int nr, int cold) | |
820 | { | |
821 | int i; | |
cc59850e | 822 | LIST_HEAD(pages_to_free); |
1da177e4 | 823 | struct zone *zone = NULL; |
fa9add64 | 824 | struct lruvec *lruvec; |
902aaed0 | 825 | unsigned long uninitialized_var(flags); |
1da177e4 | 826 | |
1da177e4 LT |
827 | for (i = 0; i < nr; i++) { |
828 | struct page *page = pages[i]; | |
1da177e4 | 829 | |
8519fb30 NP |
830 | if (unlikely(PageCompound(page))) { |
831 | if (zone) { | |
902aaed0 | 832 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
8519fb30 NP |
833 | zone = NULL; |
834 | } | |
835 | put_compound_page(page); | |
836 | continue; | |
837 | } | |
838 | ||
b5810039 | 839 | if (!put_page_testzero(page)) |
1da177e4 LT |
840 | continue; |
841 | ||
46453a6e NP |
842 | if (PageLRU(page)) { |
843 | struct zone *pagezone = page_zone(page); | |
894bc310 | 844 | |
46453a6e NP |
845 | if (pagezone != zone) { |
846 | if (zone) | |
902aaed0 HH |
847 | spin_unlock_irqrestore(&zone->lru_lock, |
848 | flags); | |
46453a6e | 849 | zone = pagezone; |
902aaed0 | 850 | spin_lock_irqsave(&zone->lru_lock, flags); |
46453a6e | 851 | } |
fa9add64 HD |
852 | |
853 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
725d704e | 854 | VM_BUG_ON(!PageLRU(page)); |
67453911 | 855 | __ClearPageLRU(page); |
fa9add64 | 856 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); |
46453a6e NP |
857 | } |
858 | ||
c53954a0 MG |
859 | /* Clear Active bit in case of parallel mark_page_accessed */ |
860 | ClearPageActive(page); | |
861 | ||
cc59850e | 862 | list_add(&page->lru, &pages_to_free); |
1da177e4 LT |
863 | } |
864 | if (zone) | |
902aaed0 | 865 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
1da177e4 | 866 | |
cc59850e | 867 | free_hot_cold_page_list(&pages_to_free, cold); |
1da177e4 | 868 | } |
0be8557b | 869 | EXPORT_SYMBOL(release_pages); |
1da177e4 LT |
870 | |
871 | /* | |
872 | * The pages which we're about to release may be in the deferred lru-addition | |
873 | * queues. That would prevent them from really being freed right now. That's | |
874 | * OK from a correctness point of view but is inefficient - those pages may be | |
875 | * cache-warm and we want to give them back to the page allocator ASAP. | |
876 | * | |
877 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
878 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
879 | * mutual recursion. | |
880 | */ | |
881 | void __pagevec_release(struct pagevec *pvec) | |
882 | { | |
883 | lru_add_drain(); | |
884 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
885 | pagevec_reinit(pvec); | |
886 | } | |
7f285701 SF |
887 | EXPORT_SYMBOL(__pagevec_release); |
888 | ||
12d27107 | 889 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
71e3aac0 | 890 | /* used by __split_huge_page_refcount() */ |
fa9add64 | 891 | void lru_add_page_tail(struct page *page, struct page *page_tail, |
5bc7b8ac | 892 | struct lruvec *lruvec, struct list_head *list) |
71e3aac0 | 893 | { |
71e3aac0 | 894 | const int file = 0; |
71e3aac0 AA |
895 | |
896 | VM_BUG_ON(!PageHead(page)); | |
897 | VM_BUG_ON(PageCompound(page_tail)); | |
898 | VM_BUG_ON(PageLRU(page_tail)); | |
fa9add64 HD |
899 | VM_BUG_ON(NR_CPUS != 1 && |
900 | !spin_is_locked(&lruvec_zone(lruvec)->lru_lock)); | |
71e3aac0 | 901 | |
5bc7b8ac SL |
902 | if (!list) |
903 | SetPageLRU(page_tail); | |
71e3aac0 | 904 | |
12d27107 HD |
905 | if (likely(PageLRU(page))) |
906 | list_add_tail(&page_tail->lru, &page->lru); | |
5bc7b8ac SL |
907 | else if (list) { |
908 | /* page reclaim is reclaiming a huge page */ | |
909 | get_page(page_tail); | |
910 | list_add_tail(&page_tail->lru, list); | |
911 | } else { | |
12d27107 HD |
912 | struct list_head *list_head; |
913 | /* | |
914 | * Head page has not yet been counted, as an hpage, | |
915 | * so we must account for each subpage individually. | |
916 | * | |
917 | * Use the standard add function to put page_tail on the list, | |
918 | * but then correct its position so they all end up in order. | |
919 | */ | |
e180cf80 | 920 | add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail)); |
12d27107 HD |
921 | list_head = page_tail->lru.prev; |
922 | list_move_tail(&page_tail->lru, list_head); | |
71e3aac0 | 923 | } |
7512102c HD |
924 | |
925 | if (!PageUnevictable(page)) | |
e180cf80 | 926 | update_page_reclaim_stat(lruvec, file, PageActive(page_tail)); |
71e3aac0 | 927 | } |
12d27107 | 928 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
71e3aac0 | 929 | |
fa9add64 HD |
930 | static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, |
931 | void *arg) | |
3dd7ae8e | 932 | { |
13f7f789 MG |
933 | int file = page_is_file_cache(page); |
934 | int active = PageActive(page); | |
935 | enum lru_list lru = page_lru(page); | |
3dd7ae8e | 936 | |
3dd7ae8e SL |
937 | VM_BUG_ON(PageLRU(page)); |
938 | ||
939 | SetPageLRU(page); | |
fa9add64 HD |
940 | add_page_to_lru_list(page, lruvec, lru); |
941 | update_page_reclaim_stat(lruvec, file, active); | |
c6286c98 | 942 | trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page)); |
3dd7ae8e SL |
943 | } |
944 | ||
1da177e4 LT |
945 | /* |
946 | * Add the passed pages to the LRU, then drop the caller's refcount | |
947 | * on them. Reinitialises the caller's pagevec. | |
948 | */ | |
a0b8cab3 | 949 | void __pagevec_lru_add(struct pagevec *pvec) |
1da177e4 | 950 | { |
a0b8cab3 | 951 | pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL); |
1da177e4 | 952 | } |
5095ae83 | 953 | EXPORT_SYMBOL(__pagevec_lru_add); |
1da177e4 | 954 | |
1da177e4 LT |
955 | /** |
956 | * pagevec_lookup - gang pagecache lookup | |
957 | * @pvec: Where the resulting pages are placed | |
958 | * @mapping: The address_space to search | |
959 | * @start: The starting page index | |
960 | * @nr_pages: The maximum number of pages | |
961 | * | |
962 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
963 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
964 | * reference against the pages in @pvec. | |
965 | * | |
966 | * The search returns a group of mapping-contiguous pages with ascending | |
967 | * indexes. There may be holes in the indices due to not-present pages. | |
968 | * | |
969 | * pagevec_lookup() returns the number of pages which were found. | |
970 | */ | |
971 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
972 | pgoff_t start, unsigned nr_pages) | |
973 | { | |
974 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
975 | return pagevec_count(pvec); | |
976 | } | |
78539fdf CH |
977 | EXPORT_SYMBOL(pagevec_lookup); |
978 | ||
1da177e4 LT |
979 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
980 | pgoff_t *index, int tag, unsigned nr_pages) | |
981 | { | |
982 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
983 | nr_pages, pvec->pages); | |
984 | return pagevec_count(pvec); | |
985 | } | |
7f285701 | 986 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 | 987 | |
1da177e4 LT |
988 | /* |
989 | * Perform any setup for the swap system | |
990 | */ | |
991 | void __init swap_setup(void) | |
992 | { | |
4481374c | 993 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); |
e0bf68dd | 994 | #ifdef CONFIG_SWAP |
33806f06 SL |
995 | int i; |
996 | ||
8077c0d9 MP |
997 | if (bdi_init(swapper_spaces[0].backing_dev_info)) |
998 | panic("Failed to init swap bdi"); | |
33806f06 SL |
999 | for (i = 0; i < MAX_SWAPFILES; i++) { |
1000 | spin_lock_init(&swapper_spaces[i].tree_lock); | |
1001 | INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear); | |
1002 | } | |
e0bf68dd PZ |
1003 | #endif |
1004 | ||
1da177e4 LT |
1005 | /* Use a smaller cluster for small-memory machines */ |
1006 | if (megs < 16) | |
1007 | page_cluster = 2; | |
1008 | else | |
1009 | page_cluster = 3; | |
1010 | /* | |
1011 | * Right now other parts of the system means that we | |
1012 | * _really_ don't want to cluster much more | |
1013 | */ | |
1da177e4 | 1014 | } |