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1 | /* | |
2 | * linux/mm/swap.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file contains the default values for the operation of the | |
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> | |
24 | #include <linux/export.h> | |
25 | #include <linux/mm_inline.h> | |
26 | #include <linux/percpu_counter.h> | |
27 | #include <linux/memremap.h> | |
28 | #include <linux/percpu.h> | |
29 | #include <linux/cpu.h> | |
30 | #include <linux/notifier.h> | |
31 | #include <linux/backing-dev.h> | |
32 | #include <linux/memcontrol.h> | |
33 | #include <linux/gfp.h> | |
34 | #include <linux/uio.h> | |
35 | #include <linux/hugetlb.h> | |
36 | #include <linux/page_idle.h> | |
37 | ||
38 | #include "internal.h" | |
39 | ||
40 | #define CREATE_TRACE_POINTS | |
41 | #include <trace/events/pagemap.h> | |
42 | ||
43 | /* How many pages do we try to swap or page in/out together? */ | |
44 | int page_cluster; | |
45 | ||
46 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); | |
47 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); | |
48 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs); | |
49 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); | |
50 | #ifdef CONFIG_SMP | |
51 | static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); | |
52 | #endif | |
53 | ||
54 | /* | |
55 | * This path almost never happens for VM activity - pages are normally | |
56 | * freed via pagevecs. But it gets used by networking. | |
57 | */ | |
58 | static void __page_cache_release(struct page *page) | |
59 | { | |
60 | if (PageLRU(page)) { | |
61 | struct zone *zone = page_zone(page); | |
62 | struct lruvec *lruvec; | |
63 | unsigned long flags; | |
64 | ||
65 | spin_lock_irqsave(zone_lru_lock(zone), flags); | |
66 | lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); | |
67 | VM_BUG_ON_PAGE(!PageLRU(page), page); | |
68 | __ClearPageLRU(page); | |
69 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); | |
70 | spin_unlock_irqrestore(zone_lru_lock(zone), flags); | |
71 | } | |
72 | __ClearPageWaiters(page); | |
73 | mem_cgroup_uncharge(page); | |
74 | } | |
75 | ||
76 | static void __put_single_page(struct page *page) | |
77 | { | |
78 | __page_cache_release(page); | |
79 | free_hot_cold_page(page, false); | |
80 | } | |
81 | ||
82 | static void __put_compound_page(struct page *page) | |
83 | { | |
84 | compound_page_dtor *dtor; | |
85 | ||
86 | /* | |
87 | * __page_cache_release() is supposed to be called for thp, not for | |
88 | * hugetlb. This is because hugetlb page does never have PageLRU set | |
89 | * (it's never listed to any LRU lists) and no memcg routines should | |
90 | * be called for hugetlb (it has a separate hugetlb_cgroup.) | |
91 | */ | |
92 | if (!PageHuge(page)) | |
93 | __page_cache_release(page); | |
94 | dtor = get_compound_page_dtor(page); | |
95 | (*dtor)(page); | |
96 | } | |
97 | ||
98 | void __put_page(struct page *page) | |
99 | { | |
100 | if (unlikely(PageCompound(page))) | |
101 | __put_compound_page(page); | |
102 | else | |
103 | __put_single_page(page); | |
104 | } | |
105 | EXPORT_SYMBOL(__put_page); | |
106 | ||
107 | /** | |
108 | * put_pages_list() - release a list of pages | |
109 | * @pages: list of pages threaded on page->lru | |
110 | * | |
111 | * Release a list of pages which are strung together on page.lru. Currently | |
112 | * used by read_cache_pages() and related error recovery code. | |
113 | */ | |
114 | void put_pages_list(struct list_head *pages) | |
115 | { | |
116 | while (!list_empty(pages)) { | |
117 | struct page *victim; | |
118 | ||
119 | victim = list_entry(pages->prev, struct page, lru); | |
120 | list_del(&victim->lru); | |
121 | put_page(victim); | |
122 | } | |
123 | } | |
124 | EXPORT_SYMBOL(put_pages_list); | |
125 | ||
126 | /* | |
127 | * get_kernel_pages() - pin kernel pages in memory | |
128 | * @kiov: An array of struct kvec structures | |
129 | * @nr_segs: number of segments to pin | |
130 | * @write: pinning for read/write, currently ignored | |
131 | * @pages: array that receives pointers to the pages pinned. | |
132 | * Should be at least nr_segs long. | |
133 | * | |
134 | * Returns number of pages pinned. This may be fewer than the number | |
135 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
136 | * were pinned, returns -errno. Each page returned must be released | |
137 | * with a put_page() call when it is finished with. | |
138 | */ | |
139 | int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, | |
140 | struct page **pages) | |
141 | { | |
142 | int seg; | |
143 | ||
144 | for (seg = 0; seg < nr_segs; seg++) { | |
145 | if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) | |
146 | return seg; | |
147 | ||
148 | pages[seg] = kmap_to_page(kiov[seg].iov_base); | |
149 | get_page(pages[seg]); | |
150 | } | |
151 | ||
152 | return seg; | |
153 | } | |
154 | EXPORT_SYMBOL_GPL(get_kernel_pages); | |
155 | ||
156 | /* | |
157 | * get_kernel_page() - pin a kernel page in memory | |
158 | * @start: starting kernel address | |
159 | * @write: pinning for read/write, currently ignored | |
160 | * @pages: array that receives pointer to the page pinned. | |
161 | * Must be at least nr_segs long. | |
162 | * | |
163 | * Returns 1 if page is pinned. If the page was not pinned, returns | |
164 | * -errno. The page returned must be released with a put_page() call | |
165 | * when it is finished with. | |
166 | */ | |
167 | int get_kernel_page(unsigned long start, int write, struct page **pages) | |
168 | { | |
169 | const struct kvec kiov = { | |
170 | .iov_base = (void *)start, | |
171 | .iov_len = PAGE_SIZE | |
172 | }; | |
173 | ||
174 | return get_kernel_pages(&kiov, 1, write, pages); | |
175 | } | |
176 | EXPORT_SYMBOL_GPL(get_kernel_page); | |
177 | ||
178 | static void pagevec_lru_move_fn(struct pagevec *pvec, | |
179 | void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg), | |
180 | void *arg) | |
181 | { | |
182 | int i; | |
183 | struct pglist_data *pgdat = NULL; | |
184 | struct lruvec *lruvec; | |
185 | unsigned long flags = 0; | |
186 | ||
187 | for (i = 0; i < pagevec_count(pvec); i++) { | |
188 | struct page *page = pvec->pages[i]; | |
189 | struct pglist_data *pagepgdat = page_pgdat(page); | |
190 | ||
191 | if (pagepgdat != pgdat) { | |
192 | if (pgdat) | |
193 | spin_unlock_irqrestore(&pgdat->lru_lock, flags); | |
194 | pgdat = pagepgdat; | |
195 | spin_lock_irqsave(&pgdat->lru_lock, flags); | |
196 | } | |
197 | ||
198 | lruvec = mem_cgroup_page_lruvec(page, pgdat); | |
199 | (*move_fn)(page, lruvec, arg); | |
200 | } | |
201 | if (pgdat) | |
202 | spin_unlock_irqrestore(&pgdat->lru_lock, flags); | |
203 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
204 | pagevec_reinit(pvec); | |
205 | } | |
206 | ||
207 | static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec, | |
208 | void *arg) | |
209 | { | |
210 | int *pgmoved = arg; | |
211 | ||
212 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
213 | enum lru_list lru = page_lru_base_type(page); | |
214 | list_move_tail(&page->lru, &lruvec->lists[lru]); | |
215 | (*pgmoved)++; | |
216 | } | |
217 | } | |
218 | ||
219 | /* | |
220 | * pagevec_move_tail() must be called with IRQ disabled. | |
221 | * Otherwise this may cause nasty races. | |
222 | */ | |
223 | static void pagevec_move_tail(struct pagevec *pvec) | |
224 | { | |
225 | int pgmoved = 0; | |
226 | ||
227 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); | |
228 | __count_vm_events(PGROTATED, pgmoved); | |
229 | } | |
230 | ||
231 | /* | |
232 | * Writeback is about to end against a page which has been marked for immediate | |
233 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
234 | * inactive list. | |
235 | */ | |
236 | void rotate_reclaimable_page(struct page *page) | |
237 | { | |
238 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && | |
239 | !PageUnevictable(page) && PageLRU(page)) { | |
240 | struct pagevec *pvec; | |
241 | unsigned long flags; | |
242 | ||
243 | get_page(page); | |
244 | local_irq_save(flags); | |
245 | pvec = this_cpu_ptr(&lru_rotate_pvecs); | |
246 | if (!pagevec_add(pvec, page) || PageCompound(page)) | |
247 | pagevec_move_tail(pvec); | |
248 | local_irq_restore(flags); | |
249 | } | |
250 | } | |
251 | ||
252 | static void update_page_reclaim_stat(struct lruvec *lruvec, | |
253 | int file, int rotated) | |
254 | { | |
255 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; | |
256 | ||
257 | reclaim_stat->recent_scanned[file]++; | |
258 | if (rotated) | |
259 | reclaim_stat->recent_rotated[file]++; | |
260 | } | |
261 | ||
262 | static void __activate_page(struct page *page, struct lruvec *lruvec, | |
263 | void *arg) | |
264 | { | |
265 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
266 | int file = page_is_file_cache(page); | |
267 | int lru = page_lru_base_type(page); | |
268 | ||
269 | del_page_from_lru_list(page, lruvec, lru); | |
270 | SetPageActive(page); | |
271 | lru += LRU_ACTIVE; | |
272 | add_page_to_lru_list(page, lruvec, lru); | |
273 | trace_mm_lru_activate(page); | |
274 | ||
275 | __count_vm_event(PGACTIVATE); | |
276 | update_page_reclaim_stat(lruvec, file, 1); | |
277 | } | |
278 | } | |
279 | ||
280 | #ifdef CONFIG_SMP | |
281 | static void activate_page_drain(int cpu) | |
282 | { | |
283 | struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); | |
284 | ||
285 | if (pagevec_count(pvec)) | |
286 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
287 | } | |
288 | ||
289 | static bool need_activate_page_drain(int cpu) | |
290 | { | |
291 | return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0; | |
292 | } | |
293 | ||
294 | void activate_page(struct page *page) | |
295 | { | |
296 | page = compound_head(page); | |
297 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
298 | struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); | |
299 | ||
300 | get_page(page); | |
301 | if (!pagevec_add(pvec, page) || PageCompound(page)) | |
302 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
303 | put_cpu_var(activate_page_pvecs); | |
304 | } | |
305 | } | |
306 | ||
307 | #else | |
308 | static inline void activate_page_drain(int cpu) | |
309 | { | |
310 | } | |
311 | ||
312 | static bool need_activate_page_drain(int cpu) | |
313 | { | |
314 | return false; | |
315 | } | |
316 | ||
317 | void activate_page(struct page *page) | |
318 | { | |
319 | struct zone *zone = page_zone(page); | |
320 | ||
321 | page = compound_head(page); | |
322 | spin_lock_irq(zone_lru_lock(zone)); | |
323 | __activate_page(page, mem_cgroup_page_lruvec(page, zone->zone_pgdat), NULL); | |
324 | spin_unlock_irq(zone_lru_lock(zone)); | |
325 | } | |
326 | #endif | |
327 | ||
328 | static void __lru_cache_activate_page(struct page *page) | |
329 | { | |
330 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); | |
331 | int i; | |
332 | ||
333 | /* | |
334 | * Search backwards on the optimistic assumption that the page being | |
335 | * activated has just been added to this pagevec. Note that only | |
336 | * the local pagevec is examined as a !PageLRU page could be in the | |
337 | * process of being released, reclaimed, migrated or on a remote | |
338 | * pagevec that is currently being drained. Furthermore, marking | |
339 | * a remote pagevec's page PageActive potentially hits a race where | |
340 | * a page is marked PageActive just after it is added to the inactive | |
341 | * list causing accounting errors and BUG_ON checks to trigger. | |
342 | */ | |
343 | for (i = pagevec_count(pvec) - 1; i >= 0; i--) { | |
344 | struct page *pagevec_page = pvec->pages[i]; | |
345 | ||
346 | if (pagevec_page == page) { | |
347 | SetPageActive(page); | |
348 | break; | |
349 | } | |
350 | } | |
351 | ||
352 | put_cpu_var(lru_add_pvec); | |
353 | } | |
354 | ||
355 | /* | |
356 | * Mark a page as having seen activity. | |
357 | * | |
358 | * inactive,unreferenced -> inactive,referenced | |
359 | * inactive,referenced -> active,unreferenced | |
360 | * active,unreferenced -> active,referenced | |
361 | * | |
362 | * When a newly allocated page is not yet visible, so safe for non-atomic ops, | |
363 | * __SetPageReferenced(page) may be substituted for mark_page_accessed(page). | |
364 | */ | |
365 | void mark_page_accessed(struct page *page) | |
366 | { | |
367 | page = compound_head(page); | |
368 | if (!PageActive(page) && !PageUnevictable(page) && | |
369 | PageReferenced(page)) { | |
370 | ||
371 | /* | |
372 | * If the page is on the LRU, queue it for activation via | |
373 | * activate_page_pvecs. Otherwise, assume the page is on a | |
374 | * pagevec, mark it active and it'll be moved to the active | |
375 | * LRU on the next drain. | |
376 | */ | |
377 | if (PageLRU(page)) | |
378 | activate_page(page); | |
379 | else | |
380 | __lru_cache_activate_page(page); | |
381 | ClearPageReferenced(page); | |
382 | if (page_is_file_cache(page)) | |
383 | workingset_activation(page); | |
384 | } else if (!PageReferenced(page)) { | |
385 | SetPageReferenced(page); | |
386 | } | |
387 | if (page_is_idle(page)) | |
388 | clear_page_idle(page); | |
389 | } | |
390 | EXPORT_SYMBOL(mark_page_accessed); | |
391 | ||
392 | static void __lru_cache_add(struct page *page) | |
393 | { | |
394 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); | |
395 | ||
396 | get_page(page); | |
397 | if (!pagevec_add(pvec, page) || PageCompound(page)) | |
398 | __pagevec_lru_add(pvec); | |
399 | put_cpu_var(lru_add_pvec); | |
400 | } | |
401 | ||
402 | /** | |
403 | * lru_cache_add: add a page to the page lists | |
404 | * @page: the page to add | |
405 | */ | |
406 | void lru_cache_add_anon(struct page *page) | |
407 | { | |
408 | if (PageActive(page)) | |
409 | ClearPageActive(page); | |
410 | __lru_cache_add(page); | |
411 | } | |
412 | ||
413 | void lru_cache_add_file(struct page *page) | |
414 | { | |
415 | if (PageActive(page)) | |
416 | ClearPageActive(page); | |
417 | __lru_cache_add(page); | |
418 | } | |
419 | EXPORT_SYMBOL(lru_cache_add_file); | |
420 | ||
421 | /** | |
422 | * lru_cache_add - add a page to a page list | |
423 | * @page: the page to be added to the LRU. | |
424 | * | |
425 | * Queue the page for addition to the LRU via pagevec. The decision on whether | |
426 | * to add the page to the [in]active [file|anon] list is deferred until the | |
427 | * pagevec is drained. This gives a chance for the caller of lru_cache_add() | |
428 | * have the page added to the active list using mark_page_accessed(). | |
429 | */ | |
430 | void lru_cache_add(struct page *page) | |
431 | { | |
432 | VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page); | |
433 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
434 | __lru_cache_add(page); | |
435 | } | |
436 | ||
437 | /** | |
438 | * add_page_to_unevictable_list - add a page to the unevictable list | |
439 | * @page: the page to be added to the unevictable list | |
440 | * | |
441 | * Add page directly to its zone's unevictable list. To avoid races with | |
442 | * tasks that might be making the page evictable, through eg. munlock, | |
443 | * munmap or exit, while it's not on the lru, we want to add the page | |
444 | * while it's locked or otherwise "invisible" to other tasks. This is | |
445 | * difficult to do when using the pagevec cache, so bypass that. | |
446 | */ | |
447 | void add_page_to_unevictable_list(struct page *page) | |
448 | { | |
449 | struct pglist_data *pgdat = page_pgdat(page); | |
450 | struct lruvec *lruvec; | |
451 | ||
452 | spin_lock_irq(&pgdat->lru_lock); | |
453 | lruvec = mem_cgroup_page_lruvec(page, pgdat); | |
454 | ClearPageActive(page); | |
455 | SetPageUnevictable(page); | |
456 | SetPageLRU(page); | |
457 | add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE); | |
458 | spin_unlock_irq(&pgdat->lru_lock); | |
459 | } | |
460 | ||
461 | /** | |
462 | * lru_cache_add_active_or_unevictable | |
463 | * @page: the page to be added to LRU | |
464 | * @vma: vma in which page is mapped for determining reclaimability | |
465 | * | |
466 | * Place @page on the active or unevictable LRU list, depending on its | |
467 | * evictability. Note that if the page is not evictable, it goes | |
468 | * directly back onto it's zone's unevictable list, it does NOT use a | |
469 | * per cpu pagevec. | |
470 | */ | |
471 | void lru_cache_add_active_or_unevictable(struct page *page, | |
472 | struct vm_area_struct *vma) | |
473 | { | |
474 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
475 | ||
476 | if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) { | |
477 | SetPageActive(page); | |
478 | lru_cache_add(page); | |
479 | return; | |
480 | } | |
481 | ||
482 | if (!TestSetPageMlocked(page)) { | |
483 | /* | |
484 | * We use the irq-unsafe __mod_zone_page_stat because this | |
485 | * counter is not modified from interrupt context, and the pte | |
486 | * lock is held(spinlock), which implies preemption disabled. | |
487 | */ | |
488 | __mod_zone_page_state(page_zone(page), NR_MLOCK, | |
489 | hpage_nr_pages(page)); | |
490 | count_vm_event(UNEVICTABLE_PGMLOCKED); | |
491 | } | |
492 | add_page_to_unevictable_list(page); | |
493 | } | |
494 | ||
495 | /* | |
496 | * If the page can not be invalidated, it is moved to the | |
497 | * inactive list to speed up its reclaim. It is moved to the | |
498 | * head of the list, rather than the tail, to give the flusher | |
499 | * threads some time to write it out, as this is much more | |
500 | * effective than the single-page writeout from reclaim. | |
501 | * | |
502 | * If the page isn't page_mapped and dirty/writeback, the page | |
503 | * could reclaim asap using PG_reclaim. | |
504 | * | |
505 | * 1. active, mapped page -> none | |
506 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim | |
507 | * 3. inactive, mapped page -> none | |
508 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim | |
509 | * 5. inactive, clean -> inactive, tail | |
510 | * 6. Others -> none | |
511 | * | |
512 | * In 4, why it moves inactive's head, the VM expects the page would | |
513 | * be write it out by flusher threads as this is much more effective | |
514 | * than the single-page writeout from reclaim. | |
515 | */ | |
516 | static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec, | |
517 | void *arg) | |
518 | { | |
519 | int lru, file; | |
520 | bool active; | |
521 | ||
522 | if (!PageLRU(page)) | |
523 | return; | |
524 | ||
525 | if (PageUnevictable(page)) | |
526 | return; | |
527 | ||
528 | /* Some processes are using the page */ | |
529 | if (page_mapped(page)) | |
530 | return; | |
531 | ||
532 | active = PageActive(page); | |
533 | file = page_is_file_cache(page); | |
534 | lru = page_lru_base_type(page); | |
535 | ||
536 | del_page_from_lru_list(page, lruvec, lru + active); | |
537 | ClearPageActive(page); | |
538 | ClearPageReferenced(page); | |
539 | add_page_to_lru_list(page, lruvec, lru); | |
540 | ||
541 | if (PageWriteback(page) || PageDirty(page)) { | |
542 | /* | |
543 | * PG_reclaim could be raced with end_page_writeback | |
544 | * It can make readahead confusing. But race window | |
545 | * is _really_ small and it's non-critical problem. | |
546 | */ | |
547 | SetPageReclaim(page); | |
548 | } else { | |
549 | /* | |
550 | * The page's writeback ends up during pagevec | |
551 | * We moves tha page into tail of inactive. | |
552 | */ | |
553 | list_move_tail(&page->lru, &lruvec->lists[lru]); | |
554 | __count_vm_event(PGROTATED); | |
555 | } | |
556 | ||
557 | if (active) | |
558 | __count_vm_event(PGDEACTIVATE); | |
559 | update_page_reclaim_stat(lruvec, file, 0); | |
560 | } | |
561 | ||
562 | ||
563 | static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, | |
564 | void *arg) | |
565 | { | |
566 | if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { | |
567 | int file = page_is_file_cache(page); | |
568 | int lru = page_lru_base_type(page); | |
569 | ||
570 | del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE); | |
571 | ClearPageActive(page); | |
572 | ClearPageReferenced(page); | |
573 | add_page_to_lru_list(page, lruvec, lru); | |
574 | ||
575 | __count_vm_event(PGDEACTIVATE); | |
576 | update_page_reclaim_stat(lruvec, file, 0); | |
577 | } | |
578 | } | |
579 | ||
580 | /* | |
581 | * Drain pages out of the cpu's pagevecs. | |
582 | * Either "cpu" is the current CPU, and preemption has already been | |
583 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
584 | */ | |
585 | void lru_add_drain_cpu(int cpu) | |
586 | { | |
587 | struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu); | |
588 | ||
589 | if (pagevec_count(pvec)) | |
590 | __pagevec_lru_add(pvec); | |
591 | ||
592 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
593 | if (pagevec_count(pvec)) { | |
594 | unsigned long flags; | |
595 | ||
596 | /* No harm done if a racing interrupt already did this */ | |
597 | local_irq_save(flags); | |
598 | pagevec_move_tail(pvec); | |
599 | local_irq_restore(flags); | |
600 | } | |
601 | ||
602 | pvec = &per_cpu(lru_deactivate_file_pvecs, cpu); | |
603 | if (pagevec_count(pvec)) | |
604 | pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); | |
605 | ||
606 | pvec = &per_cpu(lru_deactivate_pvecs, cpu); | |
607 | if (pagevec_count(pvec)) | |
608 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); | |
609 | ||
610 | activate_page_drain(cpu); | |
611 | } | |
612 | ||
613 | /** | |
614 | * deactivate_file_page - forcefully deactivate a file page | |
615 | * @page: page to deactivate | |
616 | * | |
617 | * This function hints the VM that @page is a good reclaim candidate, | |
618 | * for example if its invalidation fails due to the page being dirty | |
619 | * or under writeback. | |
620 | */ | |
621 | void deactivate_file_page(struct page *page) | |
622 | { | |
623 | /* | |
624 | * In a workload with many unevictable page such as mprotect, | |
625 | * unevictable page deactivation for accelerating reclaim is pointless. | |
626 | */ | |
627 | if (PageUnevictable(page)) | |
628 | return; | |
629 | ||
630 | if (likely(get_page_unless_zero(page))) { | |
631 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs); | |
632 | ||
633 | if (!pagevec_add(pvec, page) || PageCompound(page)) | |
634 | pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); | |
635 | put_cpu_var(lru_deactivate_file_pvecs); | |
636 | } | |
637 | } | |
638 | ||
639 | /** | |
640 | * deactivate_page - deactivate a page | |
641 | * @page: page to deactivate | |
642 | * | |
643 | * deactivate_page() moves @page to the inactive list if @page was on the active | |
644 | * list and was not an unevictable page. This is done to accelerate the reclaim | |
645 | * of @page. | |
646 | */ | |
647 | void deactivate_page(struct page *page) | |
648 | { | |
649 | if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { | |
650 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); | |
651 | ||
652 | get_page(page); | |
653 | if (!pagevec_add(pvec, page) || PageCompound(page)) | |
654 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); | |
655 | put_cpu_var(lru_deactivate_pvecs); | |
656 | } | |
657 | } | |
658 | ||
659 | void lru_add_drain(void) | |
660 | { | |
661 | lru_add_drain_cpu(get_cpu()); | |
662 | put_cpu(); | |
663 | } | |
664 | ||
665 | static void lru_add_drain_per_cpu(struct work_struct *dummy) | |
666 | { | |
667 | lru_add_drain(); | |
668 | } | |
669 | ||
670 | static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); | |
671 | ||
672 | /* | |
673 | * lru_add_drain_wq is used to do lru_add_drain_all() from a WQ_MEM_RECLAIM | |
674 | * workqueue, aiding in getting memory freed. | |
675 | */ | |
676 | static struct workqueue_struct *lru_add_drain_wq; | |
677 | ||
678 | static int __init lru_init(void) | |
679 | { | |
680 | lru_add_drain_wq = alloc_workqueue("lru-add-drain", WQ_MEM_RECLAIM, 0); | |
681 | ||
682 | if (WARN(!lru_add_drain_wq, | |
683 | "Failed to create workqueue lru_add_drain_wq")) | |
684 | return -ENOMEM; | |
685 | ||
686 | return 0; | |
687 | } | |
688 | early_initcall(lru_init); | |
689 | ||
690 | void lru_add_drain_all(void) | |
691 | { | |
692 | static DEFINE_MUTEX(lock); | |
693 | static struct cpumask has_work; | |
694 | int cpu; | |
695 | ||
696 | mutex_lock(&lock); | |
697 | get_online_cpus(); | |
698 | cpumask_clear(&has_work); | |
699 | ||
700 | for_each_online_cpu(cpu) { | |
701 | struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); | |
702 | ||
703 | if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || | |
704 | pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || | |
705 | pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) || | |
706 | pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || | |
707 | need_activate_page_drain(cpu)) { | |
708 | INIT_WORK(work, lru_add_drain_per_cpu); | |
709 | queue_work_on(cpu, lru_add_drain_wq, work); | |
710 | cpumask_set_cpu(cpu, &has_work); | |
711 | } | |
712 | } | |
713 | ||
714 | for_each_cpu(cpu, &has_work) | |
715 | flush_work(&per_cpu(lru_add_drain_work, cpu)); | |
716 | ||
717 | put_online_cpus(); | |
718 | mutex_unlock(&lock); | |
719 | } | |
720 | ||
721 | /** | |
722 | * release_pages - batched put_page() | |
723 | * @pages: array of pages to release | |
724 | * @nr: number of pages | |
725 | * @cold: whether the pages are cache cold | |
726 | * | |
727 | * Decrement the reference count on all the pages in @pages. If it | |
728 | * fell to zero, remove the page from the LRU and free it. | |
729 | */ | |
730 | void release_pages(struct page **pages, int nr, bool cold) | |
731 | { | |
732 | int i; | |
733 | LIST_HEAD(pages_to_free); | |
734 | struct pglist_data *locked_pgdat = NULL; | |
735 | struct lruvec *lruvec; | |
736 | unsigned long uninitialized_var(flags); | |
737 | unsigned int uninitialized_var(lock_batch); | |
738 | ||
739 | for (i = 0; i < nr; i++) { | |
740 | struct page *page = pages[i]; | |
741 | ||
742 | /* | |
743 | * Make sure the IRQ-safe lock-holding time does not get | |
744 | * excessive with a continuous string of pages from the | |
745 | * same pgdat. The lock is held only if pgdat != NULL. | |
746 | */ | |
747 | if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) { | |
748 | spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); | |
749 | locked_pgdat = NULL; | |
750 | } | |
751 | ||
752 | if (is_huge_zero_page(page)) | |
753 | continue; | |
754 | ||
755 | page = compound_head(page); | |
756 | if (!put_page_testzero(page)) | |
757 | continue; | |
758 | ||
759 | if (PageCompound(page)) { | |
760 | if (locked_pgdat) { | |
761 | spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); | |
762 | locked_pgdat = NULL; | |
763 | } | |
764 | __put_compound_page(page); | |
765 | continue; | |
766 | } | |
767 | ||
768 | if (PageLRU(page)) { | |
769 | struct pglist_data *pgdat = page_pgdat(page); | |
770 | ||
771 | if (pgdat != locked_pgdat) { | |
772 | if (locked_pgdat) | |
773 | spin_unlock_irqrestore(&locked_pgdat->lru_lock, | |
774 | flags); | |
775 | lock_batch = 0; | |
776 | locked_pgdat = pgdat; | |
777 | spin_lock_irqsave(&locked_pgdat->lru_lock, flags); | |
778 | } | |
779 | ||
780 | lruvec = mem_cgroup_page_lruvec(page, locked_pgdat); | |
781 | VM_BUG_ON_PAGE(!PageLRU(page), page); | |
782 | __ClearPageLRU(page); | |
783 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); | |
784 | } | |
785 | ||
786 | /* Clear Active bit in case of parallel mark_page_accessed */ | |
787 | __ClearPageActive(page); | |
788 | __ClearPageWaiters(page); | |
789 | ||
790 | list_add(&page->lru, &pages_to_free); | |
791 | } | |
792 | if (locked_pgdat) | |
793 | spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); | |
794 | ||
795 | mem_cgroup_uncharge_list(&pages_to_free); | |
796 | free_hot_cold_page_list(&pages_to_free, cold); | |
797 | } | |
798 | EXPORT_SYMBOL(release_pages); | |
799 | ||
800 | /* | |
801 | * The pages which we're about to release may be in the deferred lru-addition | |
802 | * queues. That would prevent them from really being freed right now. That's | |
803 | * OK from a correctness point of view but is inefficient - those pages may be | |
804 | * cache-warm and we want to give them back to the page allocator ASAP. | |
805 | * | |
806 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
807 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
808 | * mutual recursion. | |
809 | */ | |
810 | void __pagevec_release(struct pagevec *pvec) | |
811 | { | |
812 | lru_add_drain(); | |
813 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
814 | pagevec_reinit(pvec); | |
815 | } | |
816 | EXPORT_SYMBOL(__pagevec_release); | |
817 | ||
818 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
819 | /* used by __split_huge_page_refcount() */ | |
820 | void lru_add_page_tail(struct page *page, struct page *page_tail, | |
821 | struct lruvec *lruvec, struct list_head *list) | |
822 | { | |
823 | const int file = 0; | |
824 | ||
825 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
826 | VM_BUG_ON_PAGE(PageCompound(page_tail), page); | |
827 | VM_BUG_ON_PAGE(PageLRU(page_tail), page); | |
828 | VM_BUG_ON(NR_CPUS != 1 && | |
829 | !spin_is_locked(&lruvec_pgdat(lruvec)->lru_lock)); | |
830 | ||
831 | if (!list) | |
832 | SetPageLRU(page_tail); | |
833 | ||
834 | if (likely(PageLRU(page))) | |
835 | list_add_tail(&page_tail->lru, &page->lru); | |
836 | else if (list) { | |
837 | /* page reclaim is reclaiming a huge page */ | |
838 | get_page(page_tail); | |
839 | list_add_tail(&page_tail->lru, list); | |
840 | } else { | |
841 | struct list_head *list_head; | |
842 | /* | |
843 | * Head page has not yet been counted, as an hpage, | |
844 | * so we must account for each subpage individually. | |
845 | * | |
846 | * Use the standard add function to put page_tail on the list, | |
847 | * but then correct its position so they all end up in order. | |
848 | */ | |
849 | add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail)); | |
850 | list_head = page_tail->lru.prev; | |
851 | list_move_tail(&page_tail->lru, list_head); | |
852 | } | |
853 | ||
854 | if (!PageUnevictable(page)) | |
855 | update_page_reclaim_stat(lruvec, file, PageActive(page_tail)); | |
856 | } | |
857 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | |
858 | ||
859 | static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, | |
860 | void *arg) | |
861 | { | |
862 | int file = page_is_file_cache(page); | |
863 | int active = PageActive(page); | |
864 | enum lru_list lru = page_lru(page); | |
865 | ||
866 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
867 | ||
868 | SetPageLRU(page); | |
869 | add_page_to_lru_list(page, lruvec, lru); | |
870 | update_page_reclaim_stat(lruvec, file, active); | |
871 | trace_mm_lru_insertion(page, lru); | |
872 | } | |
873 | ||
874 | /* | |
875 | * Add the passed pages to the LRU, then drop the caller's refcount | |
876 | * on them. Reinitialises the caller's pagevec. | |
877 | */ | |
878 | void __pagevec_lru_add(struct pagevec *pvec) | |
879 | { | |
880 | pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL); | |
881 | } | |
882 | EXPORT_SYMBOL(__pagevec_lru_add); | |
883 | ||
884 | /** | |
885 | * pagevec_lookup_entries - gang pagecache lookup | |
886 | * @pvec: Where the resulting entries are placed | |
887 | * @mapping: The address_space to search | |
888 | * @start: The starting entry index | |
889 | * @nr_entries: The maximum number of entries | |
890 | * @indices: The cache indices corresponding to the entries in @pvec | |
891 | * | |
892 | * pagevec_lookup_entries() will search for and return a group of up | |
893 | * to @nr_entries pages and shadow entries in the mapping. All | |
894 | * entries are placed in @pvec. pagevec_lookup_entries() takes a | |
895 | * reference against actual pages in @pvec. | |
896 | * | |
897 | * The search returns a group of mapping-contiguous entries with | |
898 | * ascending indexes. There may be holes in the indices due to | |
899 | * not-present entries. | |
900 | * | |
901 | * pagevec_lookup_entries() returns the number of entries which were | |
902 | * found. | |
903 | */ | |
904 | unsigned pagevec_lookup_entries(struct pagevec *pvec, | |
905 | struct address_space *mapping, | |
906 | pgoff_t start, unsigned nr_pages, | |
907 | pgoff_t *indices) | |
908 | { | |
909 | pvec->nr = find_get_entries(mapping, start, nr_pages, | |
910 | pvec->pages, indices); | |
911 | return pagevec_count(pvec); | |
912 | } | |
913 | ||
914 | /** | |
915 | * pagevec_remove_exceptionals - pagevec exceptionals pruning | |
916 | * @pvec: The pagevec to prune | |
917 | * | |
918 | * pagevec_lookup_entries() fills both pages and exceptional radix | |
919 | * tree entries into the pagevec. This function prunes all | |
920 | * exceptionals from @pvec without leaving holes, so that it can be | |
921 | * passed on to page-only pagevec operations. | |
922 | */ | |
923 | void pagevec_remove_exceptionals(struct pagevec *pvec) | |
924 | { | |
925 | int i, j; | |
926 | ||
927 | for (i = 0, j = 0; i < pagevec_count(pvec); i++) { | |
928 | struct page *page = pvec->pages[i]; | |
929 | if (!radix_tree_exceptional_entry(page)) | |
930 | pvec->pages[j++] = page; | |
931 | } | |
932 | pvec->nr = j; | |
933 | } | |
934 | ||
935 | /** | |
936 | * pagevec_lookup - gang pagecache lookup | |
937 | * @pvec: Where the resulting pages are placed | |
938 | * @mapping: The address_space to search | |
939 | * @start: The starting page index | |
940 | * @nr_pages: The maximum number of pages | |
941 | * | |
942 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
943 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
944 | * reference against the pages in @pvec. | |
945 | * | |
946 | * The search returns a group of mapping-contiguous pages with ascending | |
947 | * indexes. There may be holes in the indices due to not-present pages. | |
948 | * | |
949 | * pagevec_lookup() returns the number of pages which were found. | |
950 | */ | |
951 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
952 | pgoff_t start, unsigned nr_pages) | |
953 | { | |
954 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
955 | return pagevec_count(pvec); | |
956 | } | |
957 | EXPORT_SYMBOL(pagevec_lookup); | |
958 | ||
959 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, | |
960 | pgoff_t *index, int tag, unsigned nr_pages) | |
961 | { | |
962 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
963 | nr_pages, pvec->pages); | |
964 | return pagevec_count(pvec); | |
965 | } | |
966 | EXPORT_SYMBOL(pagevec_lookup_tag); | |
967 | ||
968 | /* | |
969 | * Perform any setup for the swap system | |
970 | */ | |
971 | void __init swap_setup(void) | |
972 | { | |
973 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); | |
974 | #ifdef CONFIG_SWAP | |
975 | int i; | |
976 | ||
977 | for (i = 0; i < MAX_SWAPFILES; i++) | |
978 | spin_lock_init(&swapper_spaces[i].tree_lock); | |
979 | #endif | |
980 | ||
981 | /* Use a smaller cluster for small-memory machines */ | |
982 | if (megs < 16) | |
983 | page_cluster = 2; | |
984 | else | |
985 | page_cluster = 3; | |
986 | /* | |
987 | * Right now other parts of the system means that we | |
988 | * _really_ don't want to cluster much more | |
989 | */ | |
990 | } |