Commit | Line | Data |
---|---|---|
748446bb MG |
1 | /* |
2 | * linux/mm/compaction.c | |
3 | * | |
4 | * Memory compaction for the reduction of external fragmentation. Note that | |
5 | * this heavily depends upon page migration to do all the real heavy | |
6 | * lifting | |
7 | * | |
8 | * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie> | |
9 | */ | |
10 | #include <linux/swap.h> | |
11 | #include <linux/migrate.h> | |
12 | #include <linux/compaction.h> | |
13 | #include <linux/mm_inline.h> | |
14 | #include <linux/backing-dev.h> | |
76ab0f53 | 15 | #include <linux/sysctl.h> |
ed4a6d7f | 16 | #include <linux/sysfs.h> |
748446bb MG |
17 | #include "internal.h" |
18 | ||
ff9543fd MN |
19 | #if defined CONFIG_COMPACTION || defined CONFIG_CMA |
20 | ||
b7aba698 MG |
21 | #define CREATE_TRACE_POINTS |
22 | #include <trace/events/compaction.h> | |
23 | ||
748446bb MG |
24 | static unsigned long release_freepages(struct list_head *freelist) |
25 | { | |
26 | struct page *page, *next; | |
27 | unsigned long count = 0; | |
28 | ||
29 | list_for_each_entry_safe(page, next, freelist, lru) { | |
30 | list_del(&page->lru); | |
31 | __free_page(page); | |
32 | count++; | |
33 | } | |
34 | ||
35 | return count; | |
36 | } | |
37 | ||
ff9543fd MN |
38 | static void map_pages(struct list_head *list) |
39 | { | |
40 | struct page *page; | |
41 | ||
42 | list_for_each_entry(page, list, lru) { | |
43 | arch_alloc_page(page, 0); | |
44 | kernel_map_pages(page, 1, 1); | |
45 | } | |
46 | } | |
47 | ||
47118af0 MN |
48 | static inline bool migrate_async_suitable(int migratetype) |
49 | { | |
50 | return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE; | |
51 | } | |
52 | ||
c67fe375 MG |
53 | /* |
54 | * Compaction requires the taking of some coarse locks that are potentially | |
55 | * very heavily contended. Check if the process needs to be scheduled or | |
56 | * if the lock is contended. For async compaction, back out in the event | |
57 | * if contention is severe. For sync compaction, schedule. | |
58 | * | |
59 | * Returns true if the lock is held. | |
60 | * Returns false if the lock is released and compaction should abort | |
61 | */ | |
62 | static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags, | |
63 | bool locked, struct compact_control *cc) | |
64 | { | |
65 | if (need_resched() || spin_is_contended(lock)) { | |
66 | if (locked) { | |
67 | spin_unlock_irqrestore(lock, *flags); | |
68 | locked = false; | |
69 | } | |
70 | ||
71 | /* async aborts if taking too long or contended */ | |
72 | if (!cc->sync) { | |
73 | if (cc->contended) | |
74 | *cc->contended = true; | |
75 | return false; | |
76 | } | |
77 | ||
78 | cond_resched(); | |
79 | if (fatal_signal_pending(current)) | |
80 | return false; | |
81 | } | |
82 | ||
83 | if (!locked) | |
84 | spin_lock_irqsave(lock, *flags); | |
85 | return true; | |
86 | } | |
87 | ||
88 | static inline bool compact_trylock_irqsave(spinlock_t *lock, | |
89 | unsigned long *flags, struct compact_control *cc) | |
90 | { | |
91 | return compact_checklock_irqsave(lock, flags, false, cc); | |
92 | } | |
93 | ||
85aa125f MN |
94 | /* |
95 | * Isolate free pages onto a private freelist. Caller must hold zone->lock. | |
96 | * If @strict is true, will abort returning 0 on any invalid PFNs or non-free | |
97 | * pages inside of the pageblock (even though it may still end up isolating | |
98 | * some pages). | |
99 | */ | |
100 | static unsigned long isolate_freepages_block(unsigned long blockpfn, | |
101 | unsigned long end_pfn, | |
102 | struct list_head *freelist, | |
103 | bool strict) | |
748446bb | 104 | { |
b7aba698 | 105 | int nr_scanned = 0, total_isolated = 0; |
748446bb MG |
106 | struct page *cursor; |
107 | ||
748446bb MG |
108 | cursor = pfn_to_page(blockpfn); |
109 | ||
110 | /* Isolate free pages. This assumes the block is valid */ | |
111 | for (; blockpfn < end_pfn; blockpfn++, cursor++) { | |
112 | int isolated, i; | |
113 | struct page *page = cursor; | |
114 | ||
85aa125f MN |
115 | if (!pfn_valid_within(blockpfn)) { |
116 | if (strict) | |
117 | return 0; | |
748446bb | 118 | continue; |
85aa125f | 119 | } |
b7aba698 | 120 | nr_scanned++; |
748446bb | 121 | |
85aa125f MN |
122 | if (!PageBuddy(page)) { |
123 | if (strict) | |
124 | return 0; | |
748446bb | 125 | continue; |
85aa125f | 126 | } |
748446bb MG |
127 | |
128 | /* Found a free page, break it into order-0 pages */ | |
129 | isolated = split_free_page(page); | |
85aa125f MN |
130 | if (!isolated && strict) |
131 | return 0; | |
748446bb MG |
132 | total_isolated += isolated; |
133 | for (i = 0; i < isolated; i++) { | |
134 | list_add(&page->lru, freelist); | |
135 | page++; | |
136 | } | |
137 | ||
138 | /* If a page was split, advance to the end of it */ | |
139 | if (isolated) { | |
140 | blockpfn += isolated - 1; | |
141 | cursor += isolated - 1; | |
142 | } | |
143 | } | |
144 | ||
b7aba698 | 145 | trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated); |
748446bb MG |
146 | return total_isolated; |
147 | } | |
148 | ||
85aa125f MN |
149 | /** |
150 | * isolate_freepages_range() - isolate free pages. | |
151 | * @start_pfn: The first PFN to start isolating. | |
152 | * @end_pfn: The one-past-last PFN. | |
153 | * | |
154 | * Non-free pages, invalid PFNs, or zone boundaries within the | |
155 | * [start_pfn, end_pfn) range are considered errors, cause function to | |
156 | * undo its actions and return zero. | |
157 | * | |
158 | * Otherwise, function returns one-past-the-last PFN of isolated page | |
159 | * (which may be greater then end_pfn if end fell in a middle of | |
160 | * a free page). | |
161 | */ | |
ff9543fd | 162 | unsigned long |
85aa125f MN |
163 | isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn) |
164 | { | |
165 | unsigned long isolated, pfn, block_end_pfn, flags; | |
166 | struct zone *zone = NULL; | |
167 | LIST_HEAD(freelist); | |
168 | ||
169 | if (pfn_valid(start_pfn)) | |
170 | zone = page_zone(pfn_to_page(start_pfn)); | |
171 | ||
172 | for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) { | |
173 | if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn))) | |
174 | break; | |
175 | ||
176 | /* | |
177 | * On subsequent iterations ALIGN() is actually not needed, | |
178 | * but we keep it that we not to complicate the code. | |
179 | */ | |
180 | block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); | |
181 | block_end_pfn = min(block_end_pfn, end_pfn); | |
182 | ||
183 | spin_lock_irqsave(&zone->lock, flags); | |
184 | isolated = isolate_freepages_block(pfn, block_end_pfn, | |
185 | &freelist, true); | |
186 | spin_unlock_irqrestore(&zone->lock, flags); | |
187 | ||
188 | /* | |
189 | * In strict mode, isolate_freepages_block() returns 0 if | |
190 | * there are any holes in the block (ie. invalid PFNs or | |
191 | * non-free pages). | |
192 | */ | |
193 | if (!isolated) | |
194 | break; | |
195 | ||
196 | /* | |
197 | * If we managed to isolate pages, it is always (1 << n) * | |
198 | * pageblock_nr_pages for some non-negative n. (Max order | |
199 | * page may span two pageblocks). | |
200 | */ | |
201 | } | |
202 | ||
203 | /* split_free_page does not map the pages */ | |
204 | map_pages(&freelist); | |
205 | ||
206 | if (pfn < end_pfn) { | |
207 | /* Loop terminated early, cleanup. */ | |
208 | release_freepages(&freelist); | |
209 | return 0; | |
210 | } | |
211 | ||
212 | /* We don't use freelists for anything. */ | |
213 | return pfn; | |
214 | } | |
215 | ||
748446bb | 216 | /* Update the number of anon and file isolated pages in the zone */ |
c67fe375 | 217 | static void acct_isolated(struct zone *zone, bool locked, struct compact_control *cc) |
748446bb MG |
218 | { |
219 | struct page *page; | |
b9e84ac1 | 220 | unsigned int count[2] = { 0, }; |
748446bb | 221 | |
b9e84ac1 MK |
222 | list_for_each_entry(page, &cc->migratepages, lru) |
223 | count[!!page_is_file_cache(page)]++; | |
748446bb | 224 | |
c67fe375 MG |
225 | /* If locked we can use the interrupt unsafe versions */ |
226 | if (locked) { | |
227 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); | |
228 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); | |
229 | } else { | |
230 | mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); | |
231 | mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); | |
232 | } | |
748446bb MG |
233 | } |
234 | ||
235 | /* Similar to reclaim, but different enough that they don't share logic */ | |
236 | static bool too_many_isolated(struct zone *zone) | |
237 | { | |
bc693045 | 238 | unsigned long active, inactive, isolated; |
748446bb MG |
239 | |
240 | inactive = zone_page_state(zone, NR_INACTIVE_FILE) + | |
241 | zone_page_state(zone, NR_INACTIVE_ANON); | |
bc693045 MK |
242 | active = zone_page_state(zone, NR_ACTIVE_FILE) + |
243 | zone_page_state(zone, NR_ACTIVE_ANON); | |
748446bb MG |
244 | isolated = zone_page_state(zone, NR_ISOLATED_FILE) + |
245 | zone_page_state(zone, NR_ISOLATED_ANON); | |
246 | ||
bc693045 | 247 | return isolated > (inactive + active) / 2; |
748446bb MG |
248 | } |
249 | ||
2fe86e00 MN |
250 | /** |
251 | * isolate_migratepages_range() - isolate all migrate-able pages in range. | |
252 | * @zone: Zone pages are in. | |
253 | * @cc: Compaction control structure. | |
254 | * @low_pfn: The first PFN of the range. | |
255 | * @end_pfn: The one-past-the-last PFN of the range. | |
256 | * | |
257 | * Isolate all pages that can be migrated from the range specified by | |
258 | * [low_pfn, end_pfn). Returns zero if there is a fatal signal | |
259 | * pending), otherwise PFN of the first page that was not scanned | |
260 | * (which may be both less, equal to or more then end_pfn). | |
261 | * | |
262 | * Assumes that cc->migratepages is empty and cc->nr_migratepages is | |
263 | * zero. | |
264 | * | |
265 | * Apart from cc->migratepages and cc->nr_migratetypes this function | |
266 | * does not modify any cc's fields, in particular it does not modify | |
267 | * (or read for that matter) cc->migrate_pfn. | |
748446bb | 268 | */ |
ff9543fd | 269 | unsigned long |
2fe86e00 MN |
270 | isolate_migratepages_range(struct zone *zone, struct compact_control *cc, |
271 | unsigned long low_pfn, unsigned long end_pfn) | |
748446bb | 272 | { |
9927af74 | 273 | unsigned long last_pageblock_nr = 0, pageblock_nr; |
b7aba698 | 274 | unsigned long nr_scanned = 0, nr_isolated = 0; |
748446bb | 275 | struct list_head *migratelist = &cc->migratepages; |
f3fd4a61 | 276 | isolate_mode_t mode = 0; |
fa9add64 | 277 | struct lruvec *lruvec; |
c67fe375 MG |
278 | unsigned long flags; |
279 | bool locked; | |
748446bb | 280 | |
748446bb MG |
281 | /* |
282 | * Ensure that there are not too many pages isolated from the LRU | |
283 | * list by either parallel reclaimers or compaction. If there are, | |
284 | * delay for some time until fewer pages are isolated | |
285 | */ | |
286 | while (unlikely(too_many_isolated(zone))) { | |
f9e35b3b | 287 | /* async migration should just abort */ |
68e3e926 | 288 | if (!cc->sync) |
2fe86e00 | 289 | return 0; |
f9e35b3b | 290 | |
748446bb MG |
291 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
292 | ||
293 | if (fatal_signal_pending(current)) | |
2fe86e00 | 294 | return 0; |
748446bb MG |
295 | } |
296 | ||
297 | /* Time to isolate some pages for migration */ | |
b2eef8c0 | 298 | cond_resched(); |
c67fe375 MG |
299 | spin_lock_irqsave(&zone->lru_lock, flags); |
300 | locked = true; | |
748446bb MG |
301 | for (; low_pfn < end_pfn; low_pfn++) { |
302 | struct page *page; | |
b2eef8c0 AA |
303 | |
304 | /* give a chance to irqs before checking need_resched() */ | |
305 | if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) { | |
c67fe375 | 306 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
b2eef8c0 AA |
307 | locked = false; |
308 | } | |
c67fe375 MG |
309 | |
310 | /* Check if it is ok to still hold the lock */ | |
311 | locked = compact_checklock_irqsave(&zone->lru_lock, &flags, | |
312 | locked, cc); | |
313 | if (!locked) | |
314 | break; | |
b2eef8c0 | 315 | |
0bf380bc MG |
316 | /* |
317 | * migrate_pfn does not necessarily start aligned to a | |
318 | * pageblock. Ensure that pfn_valid is called when moving | |
319 | * into a new MAX_ORDER_NR_PAGES range in case of large | |
320 | * memory holes within the zone | |
321 | */ | |
322 | if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) { | |
323 | if (!pfn_valid(low_pfn)) { | |
324 | low_pfn += MAX_ORDER_NR_PAGES - 1; | |
325 | continue; | |
326 | } | |
327 | } | |
328 | ||
748446bb MG |
329 | if (!pfn_valid_within(low_pfn)) |
330 | continue; | |
b7aba698 | 331 | nr_scanned++; |
748446bb | 332 | |
dc908600 MG |
333 | /* |
334 | * Get the page and ensure the page is within the same zone. | |
335 | * See the comment in isolate_freepages about overlapping | |
336 | * nodes. It is deliberate that the new zone lock is not taken | |
337 | * as memory compaction should not move pages between nodes. | |
338 | */ | |
748446bb | 339 | page = pfn_to_page(low_pfn); |
dc908600 MG |
340 | if (page_zone(page) != zone) |
341 | continue; | |
342 | ||
343 | /* Skip if free */ | |
748446bb MG |
344 | if (PageBuddy(page)) |
345 | continue; | |
346 | ||
9927af74 MG |
347 | /* |
348 | * For async migration, also only scan in MOVABLE blocks. Async | |
349 | * migration is optimistic to see if the minimum amount of work | |
350 | * satisfies the allocation | |
351 | */ | |
352 | pageblock_nr = low_pfn >> pageblock_order; | |
68e3e926 | 353 | if (!cc->sync && last_pageblock_nr != pageblock_nr && |
47118af0 | 354 | !migrate_async_suitable(get_pageblock_migratetype(page))) { |
9927af74 MG |
355 | low_pfn += pageblock_nr_pages; |
356 | low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1; | |
357 | last_pageblock_nr = pageblock_nr; | |
358 | continue; | |
359 | } | |
360 | ||
bc835011 AA |
361 | if (!PageLRU(page)) |
362 | continue; | |
363 | ||
364 | /* | |
365 | * PageLRU is set, and lru_lock excludes isolation, | |
366 | * splitting and collapsing (collapsing has already | |
367 | * happened if PageLRU is set). | |
368 | */ | |
369 | if (PageTransHuge(page)) { | |
370 | low_pfn += (1 << compound_order(page)) - 1; | |
371 | continue; | |
372 | } | |
373 | ||
68e3e926 | 374 | if (!cc->sync) |
c8244935 MG |
375 | mode |= ISOLATE_ASYNC_MIGRATE; |
376 | ||
fa9add64 HD |
377 | lruvec = mem_cgroup_page_lruvec(page, zone); |
378 | ||
748446bb | 379 | /* Try isolate the page */ |
f3fd4a61 | 380 | if (__isolate_lru_page(page, mode) != 0) |
748446bb MG |
381 | continue; |
382 | ||
bc835011 AA |
383 | VM_BUG_ON(PageTransCompound(page)); |
384 | ||
748446bb | 385 | /* Successfully isolated */ |
fa9add64 | 386 | del_page_from_lru_list(page, lruvec, page_lru(page)); |
748446bb | 387 | list_add(&page->lru, migratelist); |
748446bb | 388 | cc->nr_migratepages++; |
b7aba698 | 389 | nr_isolated++; |
748446bb MG |
390 | |
391 | /* Avoid isolating too much */ | |
31b8384a HD |
392 | if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) { |
393 | ++low_pfn; | |
748446bb | 394 | break; |
31b8384a | 395 | } |
748446bb MG |
396 | } |
397 | ||
c67fe375 | 398 | acct_isolated(zone, locked, cc); |
748446bb | 399 | |
c67fe375 MG |
400 | if (locked) |
401 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
748446bb | 402 | |
b7aba698 MG |
403 | trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); |
404 | ||
2fe86e00 MN |
405 | return low_pfn; |
406 | } | |
407 | ||
ff9543fd MN |
408 | #endif /* CONFIG_COMPACTION || CONFIG_CMA */ |
409 | #ifdef CONFIG_COMPACTION | |
410 | ||
68e3e926 LT |
411 | /* Returns true if the page is within a block suitable for migration to */ |
412 | static bool suitable_migration_target(struct page *page) | |
ff9543fd MN |
413 | { |
414 | ||
415 | int migratetype = get_pageblock_migratetype(page); | |
416 | ||
417 | /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */ | |
418 | if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE) | |
68e3e926 | 419 | return false; |
ff9543fd MN |
420 | |
421 | /* If the page is a large free page, then allow migration */ | |
422 | if (PageBuddy(page) && page_order(page) >= pageblock_order) | |
68e3e926 | 423 | return true; |
ff9543fd | 424 | |
47118af0 | 425 | /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */ |
68e3e926 LT |
426 | if (migrate_async_suitable(migratetype)) |
427 | return true; | |
ff9543fd MN |
428 | |
429 | /* Otherwise skip the block */ | |
68e3e926 | 430 | return false; |
ff9543fd MN |
431 | } |
432 | ||
de74f1cc MG |
433 | /* |
434 | * Returns the start pfn of the last page block in a zone. This is the starting | |
435 | * point for full compaction of a zone. Compaction searches for free pages from | |
436 | * the end of each zone, while isolate_freepages_block scans forward inside each | |
437 | * page block. | |
438 | */ | |
439 | static unsigned long start_free_pfn(struct zone *zone) | |
440 | { | |
441 | unsigned long free_pfn; | |
442 | free_pfn = zone->zone_start_pfn + zone->spanned_pages; | |
443 | free_pfn &= ~(pageblock_nr_pages-1); | |
444 | return free_pfn; | |
445 | } | |
446 | ||
2fe86e00 | 447 | /* |
ff9543fd MN |
448 | * Based on information in the current compact_control, find blocks |
449 | * suitable for isolating free pages from and then isolate them. | |
2fe86e00 | 450 | */ |
ff9543fd MN |
451 | static void isolate_freepages(struct zone *zone, |
452 | struct compact_control *cc) | |
2fe86e00 | 453 | { |
ff9543fd MN |
454 | struct page *page; |
455 | unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn; | |
456 | unsigned long flags; | |
457 | int nr_freepages = cc->nr_freepages; | |
458 | struct list_head *freelist = &cc->freepages; | |
2fe86e00 | 459 | |
ff9543fd MN |
460 | /* |
461 | * Initialise the free scanner. The starting point is where we last | |
462 | * scanned from (or the end of the zone if starting). The low point | |
463 | * is the end of the pageblock the migration scanner is using. | |
464 | */ | |
465 | pfn = cc->free_pfn; | |
466 | low_pfn = cc->migrate_pfn + pageblock_nr_pages; | |
2fe86e00 | 467 | |
ff9543fd MN |
468 | /* |
469 | * Take care that if the migration scanner is at the end of the zone | |
470 | * that the free scanner does not accidentally move to the next zone | |
471 | * in the next isolation cycle. | |
472 | */ | |
473 | high_pfn = min(low_pfn, pfn); | |
2fe86e00 | 474 | |
ff9543fd | 475 | zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; |
2fe86e00 | 476 | |
ff9543fd MN |
477 | /* |
478 | * Isolate free pages until enough are available to migrate the | |
479 | * pages on cc->migratepages. We stop searching if the migrate | |
480 | * and free page scanners meet or enough free pages are isolated. | |
481 | */ | |
482 | for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages; | |
483 | pfn -= pageblock_nr_pages) { | |
484 | unsigned long isolated; | |
2fe86e00 | 485 | |
ff9543fd MN |
486 | if (!pfn_valid(pfn)) |
487 | continue; | |
2fe86e00 | 488 | |
ff9543fd MN |
489 | /* |
490 | * Check for overlapping nodes/zones. It's possible on some | |
491 | * configurations to have a setup like | |
492 | * node0 node1 node0 | |
493 | * i.e. it's possible that all pages within a zones range of | |
494 | * pages do not belong to a single zone. | |
495 | */ | |
496 | page = pfn_to_page(pfn); | |
497 | if (page_zone(page) != zone) | |
498 | continue; | |
499 | ||
500 | /* Check the block is suitable for migration */ | |
68e3e926 | 501 | if (!suitable_migration_target(page)) |
ff9543fd | 502 | continue; |
68e3e926 | 503 | |
ff9543fd MN |
504 | /* |
505 | * Found a block suitable for isolating free pages from. Now | |
506 | * we disabled interrupts, double check things are ok and | |
507 | * isolate the pages. This is to minimise the time IRQs | |
508 | * are disabled | |
509 | */ | |
510 | isolated = 0; | |
c67fe375 MG |
511 | |
512 | /* | |
513 | * The zone lock must be held to isolate freepages. This | |
514 | * unfortunately this is a very coarse lock and can be | |
515 | * heavily contended if there are parallel allocations | |
516 | * or parallel compactions. For async compaction do not | |
517 | * spin on the lock | |
518 | */ | |
519 | if (!compact_trylock_irqsave(&zone->lock, &flags, cc)) | |
520 | break; | |
68e3e926 | 521 | if (suitable_migration_target(page)) { |
ff9543fd MN |
522 | end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn); |
523 | isolated = isolate_freepages_block(pfn, end_pfn, | |
524 | freelist, false); | |
525 | nr_freepages += isolated; | |
68e3e926 | 526 | } |
ff9543fd MN |
527 | spin_unlock_irqrestore(&zone->lock, flags); |
528 | ||
529 | /* | |
530 | * Record the highest PFN we isolated pages from. When next | |
531 | * looking for free pages, the search will restart here as | |
532 | * page migration may have returned some pages to the allocator | |
533 | */ | |
7db8889a | 534 | if (isolated) { |
ff9543fd | 535 | high_pfn = max(high_pfn, pfn); |
de74f1cc MG |
536 | |
537 | /* | |
538 | * If the free scanner has wrapped, update | |
539 | * compact_cached_free_pfn to point to the highest | |
540 | * pageblock with free pages. This reduces excessive | |
541 | * scanning of full pageblocks near the end of the | |
542 | * zone | |
543 | */ | |
544 | if (cc->order > 0 && cc->wrapped) | |
7db8889a RR |
545 | zone->compact_cached_free_pfn = high_pfn; |
546 | } | |
ff9543fd MN |
547 | } |
548 | ||
549 | /* split_free_page does not map the pages */ | |
550 | map_pages(freelist); | |
551 | ||
552 | cc->free_pfn = high_pfn; | |
553 | cc->nr_freepages = nr_freepages; | |
de74f1cc MG |
554 | |
555 | /* If compact_cached_free_pfn is reset then set it now */ | |
556 | if (cc->order > 0 && !cc->wrapped && | |
557 | zone->compact_cached_free_pfn == start_free_pfn(zone)) | |
558 | zone->compact_cached_free_pfn = high_pfn; | |
748446bb MG |
559 | } |
560 | ||
561 | /* | |
562 | * This is a migrate-callback that "allocates" freepages by taking pages | |
563 | * from the isolated freelists in the block we are migrating to. | |
564 | */ | |
565 | static struct page *compaction_alloc(struct page *migratepage, | |
566 | unsigned long data, | |
567 | int **result) | |
568 | { | |
569 | struct compact_control *cc = (struct compact_control *)data; | |
570 | struct page *freepage; | |
571 | ||
572 | /* Isolate free pages if necessary */ | |
573 | if (list_empty(&cc->freepages)) { | |
574 | isolate_freepages(cc->zone, cc); | |
575 | ||
576 | if (list_empty(&cc->freepages)) | |
577 | return NULL; | |
578 | } | |
579 | ||
580 | freepage = list_entry(cc->freepages.next, struct page, lru); | |
581 | list_del(&freepage->lru); | |
582 | cc->nr_freepages--; | |
583 | ||
584 | return freepage; | |
585 | } | |
586 | ||
587 | /* | |
588 | * We cannot control nr_migratepages and nr_freepages fully when migration is | |
589 | * running as migrate_pages() has no knowledge of compact_control. When | |
590 | * migration is complete, we count the number of pages on the lists by hand. | |
591 | */ | |
592 | static void update_nr_listpages(struct compact_control *cc) | |
593 | { | |
594 | int nr_migratepages = 0; | |
595 | int nr_freepages = 0; | |
596 | struct page *page; | |
597 | ||
598 | list_for_each_entry(page, &cc->migratepages, lru) | |
599 | nr_migratepages++; | |
600 | list_for_each_entry(page, &cc->freepages, lru) | |
601 | nr_freepages++; | |
602 | ||
603 | cc->nr_migratepages = nr_migratepages; | |
604 | cc->nr_freepages = nr_freepages; | |
605 | } | |
606 | ||
ff9543fd MN |
607 | /* possible outcome of isolate_migratepages */ |
608 | typedef enum { | |
609 | ISOLATE_ABORT, /* Abort compaction now */ | |
610 | ISOLATE_NONE, /* No pages isolated, continue scanning */ | |
611 | ISOLATE_SUCCESS, /* Pages isolated, migrate */ | |
612 | } isolate_migrate_t; | |
613 | ||
614 | /* | |
615 | * Isolate all pages that can be migrated from the block pointed to by | |
616 | * the migrate scanner within compact_control. | |
617 | */ | |
618 | static isolate_migrate_t isolate_migratepages(struct zone *zone, | |
619 | struct compact_control *cc) | |
620 | { | |
621 | unsigned long low_pfn, end_pfn; | |
622 | ||
623 | /* Do not scan outside zone boundaries */ | |
624 | low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn); | |
625 | ||
626 | /* Only scan within a pageblock boundary */ | |
627 | end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages); | |
628 | ||
629 | /* Do not cross the free scanner or scan within a memory hole */ | |
630 | if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) { | |
631 | cc->migrate_pfn = end_pfn; | |
632 | return ISOLATE_NONE; | |
633 | } | |
634 | ||
635 | /* Perform the isolation */ | |
636 | low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn); | |
637 | if (!low_pfn) | |
638 | return ISOLATE_ABORT; | |
639 | ||
640 | cc->migrate_pfn = low_pfn; | |
641 | ||
642 | return ISOLATE_SUCCESS; | |
643 | } | |
644 | ||
748446bb | 645 | static int compact_finished(struct zone *zone, |
5a03b051 | 646 | struct compact_control *cc) |
748446bb | 647 | { |
56de7263 | 648 | unsigned int order; |
5a03b051 | 649 | unsigned long watermark; |
56de7263 | 650 | |
748446bb MG |
651 | if (fatal_signal_pending(current)) |
652 | return COMPACT_PARTIAL; | |
653 | ||
7db8889a RR |
654 | /* |
655 | * A full (order == -1) compaction run starts at the beginning and | |
656 | * end of a zone; it completes when the migrate and free scanner meet. | |
657 | * A partial (order > 0) compaction can start with the free scanner | |
658 | * at a random point in the zone, and may have to restart. | |
659 | */ | |
660 | if (cc->free_pfn <= cc->migrate_pfn) { | |
661 | if (cc->order > 0 && !cc->wrapped) { | |
662 | /* We started partway through; restart at the end. */ | |
663 | unsigned long free_pfn = start_free_pfn(zone); | |
664 | zone->compact_cached_free_pfn = free_pfn; | |
665 | cc->free_pfn = free_pfn; | |
666 | cc->wrapped = 1; | |
667 | return COMPACT_CONTINUE; | |
668 | } | |
669 | return COMPACT_COMPLETE; | |
670 | } | |
671 | ||
672 | /* We wrapped around and ended up where we started. */ | |
673 | if (cc->wrapped && cc->free_pfn <= cc->start_free_pfn) | |
748446bb MG |
674 | return COMPACT_COMPLETE; |
675 | ||
82478fb7 JW |
676 | /* |
677 | * order == -1 is expected when compacting via | |
678 | * /proc/sys/vm/compact_memory | |
679 | */ | |
56de7263 MG |
680 | if (cc->order == -1) |
681 | return COMPACT_CONTINUE; | |
682 | ||
3957c776 MH |
683 | /* Compaction run is not finished if the watermark is not met */ |
684 | watermark = low_wmark_pages(zone); | |
685 | watermark += (1 << cc->order); | |
686 | ||
687 | if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0)) | |
688 | return COMPACT_CONTINUE; | |
689 | ||
56de7263 MG |
690 | /* Direct compactor: Is a suitable page free? */ |
691 | for (order = cc->order; order < MAX_ORDER; order++) { | |
692 | /* Job done if page is free of the right migratetype */ | |
693 | if (!list_empty(&zone->free_area[order].free_list[cc->migratetype])) | |
694 | return COMPACT_PARTIAL; | |
695 | ||
696 | /* Job done if allocation would set block type */ | |
697 | if (order >= pageblock_order && zone->free_area[order].nr_free) | |
698 | return COMPACT_PARTIAL; | |
699 | } | |
700 | ||
748446bb MG |
701 | return COMPACT_CONTINUE; |
702 | } | |
703 | ||
3e7d3449 MG |
704 | /* |
705 | * compaction_suitable: Is this suitable to run compaction on this zone now? | |
706 | * Returns | |
707 | * COMPACT_SKIPPED - If there are too few free pages for compaction | |
708 | * COMPACT_PARTIAL - If the allocation would succeed without compaction | |
709 | * COMPACT_CONTINUE - If compaction should run now | |
710 | */ | |
711 | unsigned long compaction_suitable(struct zone *zone, int order) | |
712 | { | |
713 | int fragindex; | |
714 | unsigned long watermark; | |
715 | ||
3957c776 MH |
716 | /* |
717 | * order == -1 is expected when compacting via | |
718 | * /proc/sys/vm/compact_memory | |
719 | */ | |
720 | if (order == -1) | |
721 | return COMPACT_CONTINUE; | |
722 | ||
3e7d3449 MG |
723 | /* |
724 | * Watermarks for order-0 must be met for compaction. Note the 2UL. | |
725 | * This is because during migration, copies of pages need to be | |
726 | * allocated and for a short time, the footprint is higher | |
727 | */ | |
728 | watermark = low_wmark_pages(zone) + (2UL << order); | |
729 | if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) | |
730 | return COMPACT_SKIPPED; | |
731 | ||
732 | /* | |
733 | * fragmentation index determines if allocation failures are due to | |
734 | * low memory or external fragmentation | |
735 | * | |
a582a738 SL |
736 | * index of -1000 implies allocations might succeed depending on |
737 | * watermarks | |
3e7d3449 MG |
738 | * index towards 0 implies failure is due to lack of memory |
739 | * index towards 1000 implies failure is due to fragmentation | |
740 | * | |
741 | * Only compact if a failure would be due to fragmentation. | |
742 | */ | |
743 | fragindex = fragmentation_index(zone, order); | |
744 | if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) | |
745 | return COMPACT_SKIPPED; | |
746 | ||
a582a738 SL |
747 | if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark, |
748 | 0, 0)) | |
3e7d3449 MG |
749 | return COMPACT_PARTIAL; |
750 | ||
751 | return COMPACT_CONTINUE; | |
752 | } | |
753 | ||
748446bb MG |
754 | static int compact_zone(struct zone *zone, struct compact_control *cc) |
755 | { | |
756 | int ret; | |
757 | ||
3e7d3449 MG |
758 | ret = compaction_suitable(zone, cc->order); |
759 | switch (ret) { | |
760 | case COMPACT_PARTIAL: | |
761 | case COMPACT_SKIPPED: | |
762 | /* Compaction is likely to fail */ | |
763 | return ret; | |
764 | case COMPACT_CONTINUE: | |
765 | /* Fall through to compaction */ | |
766 | ; | |
767 | } | |
768 | ||
748446bb MG |
769 | /* Setup to move all movable pages to the end of the zone */ |
770 | cc->migrate_pfn = zone->zone_start_pfn; | |
7db8889a RR |
771 | |
772 | if (cc->order > 0) { | |
773 | /* Incremental compaction. Start where the last one stopped. */ | |
774 | cc->free_pfn = zone->compact_cached_free_pfn; | |
775 | cc->start_free_pfn = cc->free_pfn; | |
776 | } else { | |
777 | /* Order == -1 starts at the end of the zone. */ | |
778 | cc->free_pfn = start_free_pfn(zone); | |
779 | } | |
748446bb MG |
780 | |
781 | migrate_prep_local(); | |
782 | ||
783 | while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) { | |
784 | unsigned long nr_migrate, nr_remaining; | |
9d502c1c | 785 | int err; |
748446bb | 786 | |
f9e35b3b MG |
787 | switch (isolate_migratepages(zone, cc)) { |
788 | case ISOLATE_ABORT: | |
789 | ret = COMPACT_PARTIAL; | |
790 | goto out; | |
791 | case ISOLATE_NONE: | |
748446bb | 792 | continue; |
f9e35b3b MG |
793 | case ISOLATE_SUCCESS: |
794 | ; | |
795 | } | |
748446bb MG |
796 | |
797 | nr_migrate = cc->nr_migratepages; | |
9d502c1c | 798 | err = migrate_pages(&cc->migratepages, compaction_alloc, |
68e3e926 LT |
799 | (unsigned long)cc, false, |
800 | cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC); | |
748446bb MG |
801 | update_nr_listpages(cc); |
802 | nr_remaining = cc->nr_migratepages; | |
803 | ||
804 | count_vm_event(COMPACTBLOCKS); | |
805 | count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining); | |
806 | if (nr_remaining) | |
807 | count_vm_events(COMPACTPAGEFAILED, nr_remaining); | |
b7aba698 MG |
808 | trace_mm_compaction_migratepages(nr_migrate - nr_remaining, |
809 | nr_remaining); | |
748446bb MG |
810 | |
811 | /* Release LRU pages not migrated */ | |
9d502c1c | 812 | if (err) { |
748446bb MG |
813 | putback_lru_pages(&cc->migratepages); |
814 | cc->nr_migratepages = 0; | |
4bf2bba3 DR |
815 | if (err == -ENOMEM) { |
816 | ret = COMPACT_PARTIAL; | |
817 | goto out; | |
818 | } | |
748446bb | 819 | } |
748446bb MG |
820 | } |
821 | ||
f9e35b3b | 822 | out: |
748446bb MG |
823 | /* Release free pages and check accounting */ |
824 | cc->nr_freepages -= release_freepages(&cc->freepages); | |
825 | VM_BUG_ON(cc->nr_freepages != 0); | |
826 | ||
827 | return ret; | |
828 | } | |
76ab0f53 | 829 | |
d43a87e6 | 830 | static unsigned long compact_zone_order(struct zone *zone, |
5a03b051 | 831 | int order, gfp_t gfp_mask, |
c67fe375 | 832 | bool sync, bool *contended) |
56de7263 MG |
833 | { |
834 | struct compact_control cc = { | |
835 | .nr_freepages = 0, | |
836 | .nr_migratepages = 0, | |
837 | .order = order, | |
838 | .migratetype = allocflags_to_migratetype(gfp_mask), | |
839 | .zone = zone, | |
68e3e926 | 840 | .sync = sync, |
c67fe375 | 841 | .contended = contended, |
56de7263 MG |
842 | }; |
843 | INIT_LIST_HEAD(&cc.freepages); | |
844 | INIT_LIST_HEAD(&cc.migratepages); | |
845 | ||
68e3e926 | 846 | return compact_zone(zone, &cc); |
56de7263 MG |
847 | } |
848 | ||
5e771905 MG |
849 | int sysctl_extfrag_threshold = 500; |
850 | ||
56de7263 MG |
851 | /** |
852 | * try_to_compact_pages - Direct compact to satisfy a high-order allocation | |
853 | * @zonelist: The zonelist used for the current allocation | |
854 | * @order: The order of the current allocation | |
855 | * @gfp_mask: The GFP mask of the current allocation | |
856 | * @nodemask: The allowed nodes to allocate from | |
77f1fe6b | 857 | * @sync: Whether migration is synchronous or not |
56de7263 MG |
858 | * |
859 | * This is the main entry point for direct page compaction. | |
860 | */ | |
861 | unsigned long try_to_compact_pages(struct zonelist *zonelist, | |
77f1fe6b | 862 | int order, gfp_t gfp_mask, nodemask_t *nodemask, |
c67fe375 | 863 | bool sync, bool *contended) |
56de7263 MG |
864 | { |
865 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); | |
866 | int may_enter_fs = gfp_mask & __GFP_FS; | |
867 | int may_perform_io = gfp_mask & __GFP_IO; | |
56de7263 MG |
868 | struct zoneref *z; |
869 | struct zone *zone; | |
870 | int rc = COMPACT_SKIPPED; | |
871 | ||
872 | /* | |
873 | * Check whether it is worth even starting compaction. The order check is | |
874 | * made because an assumption is made that the page allocator can satisfy | |
875 | * the "cheaper" orders without taking special steps | |
876 | */ | |
c5a73c3d | 877 | if (!order || !may_enter_fs || !may_perform_io) |
56de7263 MG |
878 | return rc; |
879 | ||
880 | count_vm_event(COMPACTSTALL); | |
881 | ||
882 | /* Compact each zone in the list */ | |
883 | for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, | |
884 | nodemask) { | |
56de7263 MG |
885 | int status; |
886 | ||
c67fe375 MG |
887 | status = compact_zone_order(zone, order, gfp_mask, sync, |
888 | contended); | |
56de7263 MG |
889 | rc = max(status, rc); |
890 | ||
3e7d3449 MG |
891 | /* If a normal allocation would succeed, stop compacting */ |
892 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) | |
56de7263 MG |
893 | break; |
894 | } | |
895 | ||
896 | return rc; | |
897 | } | |
898 | ||
899 | ||
76ab0f53 | 900 | /* Compact all zones within a node */ |
7be62de9 | 901 | static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc) |
76ab0f53 MG |
902 | { |
903 | int zoneid; | |
76ab0f53 MG |
904 | struct zone *zone; |
905 | ||
76ab0f53 | 906 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { |
76ab0f53 MG |
907 | |
908 | zone = &pgdat->node_zones[zoneid]; | |
909 | if (!populated_zone(zone)) | |
910 | continue; | |
911 | ||
7be62de9 RR |
912 | cc->nr_freepages = 0; |
913 | cc->nr_migratepages = 0; | |
914 | cc->zone = zone; | |
915 | INIT_LIST_HEAD(&cc->freepages); | |
916 | INIT_LIST_HEAD(&cc->migratepages); | |
76ab0f53 | 917 | |
aad6ec37 | 918 | if (cc->order == -1 || !compaction_deferred(zone, cc->order)) |
7be62de9 | 919 | compact_zone(zone, cc); |
76ab0f53 | 920 | |
aff62249 RR |
921 | if (cc->order > 0) { |
922 | int ok = zone_watermark_ok(zone, cc->order, | |
923 | low_wmark_pages(zone), 0, 0); | |
c81758fb | 924 | if (ok && cc->order >= zone->compact_order_failed) |
aff62249 RR |
925 | zone->compact_order_failed = cc->order + 1; |
926 | /* Currently async compaction is never deferred. */ | |
68e3e926 | 927 | else if (!ok && cc->sync) |
aff62249 RR |
928 | defer_compaction(zone, cc->order); |
929 | } | |
930 | ||
7be62de9 RR |
931 | VM_BUG_ON(!list_empty(&cc->freepages)); |
932 | VM_BUG_ON(!list_empty(&cc->migratepages)); | |
76ab0f53 MG |
933 | } |
934 | ||
935 | return 0; | |
936 | } | |
937 | ||
7be62de9 RR |
938 | int compact_pgdat(pg_data_t *pgdat, int order) |
939 | { | |
940 | struct compact_control cc = { | |
941 | .order = order, | |
68e3e926 | 942 | .sync = false, |
7be62de9 RR |
943 | }; |
944 | ||
945 | return __compact_pgdat(pgdat, &cc); | |
946 | } | |
947 | ||
948 | static int compact_node(int nid) | |
949 | { | |
7be62de9 RR |
950 | struct compact_control cc = { |
951 | .order = -1, | |
68e3e926 | 952 | .sync = true, |
7be62de9 RR |
953 | }; |
954 | ||
8575ec29 | 955 | return __compact_pgdat(NODE_DATA(nid), &cc); |
7be62de9 RR |
956 | } |
957 | ||
76ab0f53 MG |
958 | /* Compact all nodes in the system */ |
959 | static int compact_nodes(void) | |
960 | { | |
961 | int nid; | |
962 | ||
8575ec29 HD |
963 | /* Flush pending updates to the LRU lists */ |
964 | lru_add_drain_all(); | |
965 | ||
76ab0f53 MG |
966 | for_each_online_node(nid) |
967 | compact_node(nid); | |
968 | ||
969 | return COMPACT_COMPLETE; | |
970 | } | |
971 | ||
972 | /* The written value is actually unused, all memory is compacted */ | |
973 | int sysctl_compact_memory; | |
974 | ||
975 | /* This is the entry point for compacting all nodes via /proc/sys/vm */ | |
976 | int sysctl_compaction_handler(struct ctl_table *table, int write, | |
977 | void __user *buffer, size_t *length, loff_t *ppos) | |
978 | { | |
979 | if (write) | |
980 | return compact_nodes(); | |
981 | ||
982 | return 0; | |
983 | } | |
ed4a6d7f | 984 | |
5e771905 MG |
985 | int sysctl_extfrag_handler(struct ctl_table *table, int write, |
986 | void __user *buffer, size_t *length, loff_t *ppos) | |
987 | { | |
988 | proc_dointvec_minmax(table, write, buffer, length, ppos); | |
989 | ||
990 | return 0; | |
991 | } | |
992 | ||
ed4a6d7f | 993 | #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) |
10fbcf4c KS |
994 | ssize_t sysfs_compact_node(struct device *dev, |
995 | struct device_attribute *attr, | |
ed4a6d7f MG |
996 | const char *buf, size_t count) |
997 | { | |
8575ec29 HD |
998 | int nid = dev->id; |
999 | ||
1000 | if (nid >= 0 && nid < nr_node_ids && node_online(nid)) { | |
1001 | /* Flush pending updates to the LRU lists */ | |
1002 | lru_add_drain_all(); | |
1003 | ||
1004 | compact_node(nid); | |
1005 | } | |
ed4a6d7f MG |
1006 | |
1007 | return count; | |
1008 | } | |
10fbcf4c | 1009 | static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node); |
ed4a6d7f MG |
1010 | |
1011 | int compaction_register_node(struct node *node) | |
1012 | { | |
10fbcf4c | 1013 | return device_create_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
1014 | } |
1015 | ||
1016 | void compaction_unregister_node(struct node *node) | |
1017 | { | |
10fbcf4c | 1018 | return device_remove_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
1019 | } |
1020 | #endif /* CONFIG_SYSFS && CONFIG_NUMA */ | |
ff9543fd MN |
1021 | |
1022 | #endif /* CONFIG_COMPACTION */ |