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