blob: 6b807e46649703909d0662a44f88d7c4b2057635 [file] [log] [blame]
Mel Gorman748446b2010-05-24 14:32:27 -07001/*
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>
Mel Gorman76ab0f52010-05-24 14:32:28 -070015#include <linux/sysctl.h>
Mel Gormaned4a6d72010-05-24 14:32:29 -070016#include <linux/sysfs.h>
Rafael Aquinibf6bddf2012-12-11 16:02:42 -080017#include <linux/balloon_compaction.h>
Mel Gorman748446b2010-05-24 14:32:27 -070018#include "internal.h"
19
Minchan Kim010fc292012-12-20 15:05:06 -080020#ifdef CONFIG_COMPACTION
21static inline void count_compact_event(enum vm_event_item item)
22{
23 count_vm_event(item);
24}
25
26static inline void count_compact_events(enum vm_event_item item, long delta)
27{
28 count_vm_events(item, delta);
29}
30#else
31#define count_compact_event(item) do { } while (0)
32#define count_compact_events(item, delta) do { } while (0)
33#endif
34
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010035#if defined CONFIG_COMPACTION || defined CONFIG_CMA
36
Mel Gormanb7aba692011-01-13 15:45:54 -080037#define CREATE_TRACE_POINTS
38#include <trace/events/compaction.h>
39
Mel Gorman748446b2010-05-24 14:32:27 -070040static unsigned long release_freepages(struct list_head *freelist)
41{
42 struct page *page, *next;
43 unsigned long count = 0;
44
45 list_for_each_entry_safe(page, next, freelist, lru) {
46 list_del(&page->lru);
47 __free_page(page);
48 count++;
49 }
50
51 return count;
52}
53
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010054static void map_pages(struct list_head *list)
55{
56 struct page *page;
57
58 list_for_each_entry(page, list, lru) {
59 arch_alloc_page(page, 0);
60 kernel_map_pages(page, 1, 1);
61 }
62}
63
Michal Nazarewicz47118af2011-12-29 13:09:50 +010064static inline bool migrate_async_suitable(int migratetype)
65{
66 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
67}
68
Mel Gormanbb13ffe2012-10-08 16:32:41 -070069#ifdef CONFIG_COMPACTION
70/* Returns true if the pageblock should be scanned for pages to isolate. */
71static inline bool isolation_suitable(struct compact_control *cc,
72 struct page *page)
73{
74 if (cc->ignore_skip_hint)
75 return true;
76
77 return !get_pageblock_skip(page);
78}
79
80/*
81 * This function is called to clear all cached information on pageblocks that
82 * should be skipped for page isolation when the migrate and free page scanner
83 * meet.
84 */
Mel Gorman62997022012-10-08 16:32:47 -070085static void __reset_isolation_suitable(struct zone *zone)
Mel Gormanbb13ffe2012-10-08 16:32:41 -070086{
87 unsigned long start_pfn = zone->zone_start_pfn;
88 unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
89 unsigned long pfn;
90
Mel Gormanc89511a2012-10-08 16:32:45 -070091 zone->compact_cached_migrate_pfn = start_pfn;
92 zone->compact_cached_free_pfn = end_pfn;
Mel Gorman62997022012-10-08 16:32:47 -070093 zone->compact_blockskip_flush = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -070094
95 /* Walk the zone and mark every pageblock as suitable for isolation */
96 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
97 struct page *page;
98
99 cond_resched();
100
101 if (!pfn_valid(pfn))
102 continue;
103
104 page = pfn_to_page(pfn);
105 if (zone != page_zone(page))
106 continue;
107
108 clear_pageblock_skip(page);
109 }
110}
111
Mel Gorman62997022012-10-08 16:32:47 -0700112void reset_isolation_suitable(pg_data_t *pgdat)
113{
114 int zoneid;
115
116 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
117 struct zone *zone = &pgdat->node_zones[zoneid];
118 if (!populated_zone(zone))
119 continue;
120
121 /* Only flush if a full compaction finished recently */
122 if (zone->compact_blockskip_flush)
123 __reset_isolation_suitable(zone);
124 }
125}
126
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700127/*
128 * If no pages were isolated then mark this pageblock to be skipped in the
Mel Gorman62997022012-10-08 16:32:47 -0700129 * future. The information is later cleared by __reset_isolation_suitable().
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700130 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700131static void update_pageblock_skip(struct compact_control *cc,
132 struct page *page, unsigned long nr_isolated,
133 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700134{
Mel Gormanc89511a2012-10-08 16:32:45 -0700135 struct zone *zone = cc->zone;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700136 if (!page)
137 return;
138
Mel Gormanc89511a2012-10-08 16:32:45 -0700139 if (!nr_isolated) {
140 unsigned long pfn = page_to_pfn(page);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700141 set_pageblock_skip(page);
Mel Gormanc89511a2012-10-08 16:32:45 -0700142
143 /* Update where compaction should restart */
144 if (migrate_scanner) {
145 if (!cc->finished_update_migrate &&
146 pfn > zone->compact_cached_migrate_pfn)
147 zone->compact_cached_migrate_pfn = pfn;
148 } else {
149 if (!cc->finished_update_free &&
150 pfn < zone->compact_cached_free_pfn)
151 zone->compact_cached_free_pfn = pfn;
152 }
153 }
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700154}
155#else
156static inline bool isolation_suitable(struct compact_control *cc,
157 struct page *page)
158{
159 return true;
160}
161
Mel Gormanc89511a2012-10-08 16:32:45 -0700162static void update_pageblock_skip(struct compact_control *cc,
163 struct page *page, unsigned long nr_isolated,
164 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700165{
166}
167#endif /* CONFIG_COMPACTION */
168
Mel Gorman2a1402a2012-10-08 16:32:33 -0700169static inline bool should_release_lock(spinlock_t *lock)
170{
171 return need_resched() || spin_is_contended(lock);
172}
173
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100174/*
Mel Gormanc67fe372012-08-21 16:16:17 -0700175 * Compaction requires the taking of some coarse locks that are potentially
176 * very heavily contended. Check if the process needs to be scheduled or
177 * if the lock is contended. For async compaction, back out in the event
178 * if contention is severe. For sync compaction, schedule.
179 *
180 * Returns true if the lock is held.
181 * Returns false if the lock is released and compaction should abort
182 */
183static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
184 bool locked, struct compact_control *cc)
185{
Mel Gorman2a1402a2012-10-08 16:32:33 -0700186 if (should_release_lock(lock)) {
Mel Gormanc67fe372012-08-21 16:16:17 -0700187 if (locked) {
188 spin_unlock_irqrestore(lock, *flags);
189 locked = false;
190 }
191
192 /* async aborts if taking too long or contended */
193 if (!cc->sync) {
Shaohua Lie64c5232012-10-08 16:32:27 -0700194 cc->contended = true;
Mel Gormanc67fe372012-08-21 16:16:17 -0700195 return false;
196 }
197
198 cond_resched();
Mel Gormanc67fe372012-08-21 16:16:17 -0700199 }
200
201 if (!locked)
202 spin_lock_irqsave(lock, *flags);
203 return true;
204}
205
206static inline bool compact_trylock_irqsave(spinlock_t *lock,
207 unsigned long *flags, struct compact_control *cc)
208{
209 return compact_checklock_irqsave(lock, flags, false, cc);
210}
211
Mel Gormanf40d1e42012-10-08 16:32:36 -0700212/* Returns true if the page is within a block suitable for migration to */
213static bool suitable_migration_target(struct page *page)
214{
215 int migratetype = get_pageblock_migratetype(page);
216
217 /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
218 if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
219 return false;
220
221 /* If the page is a large free page, then allow migration */
222 if (PageBuddy(page) && page_order(page) >= pageblock_order)
223 return true;
224
225 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
226 if (migrate_async_suitable(migratetype))
227 return true;
228
229 /* Otherwise skip the block */
230 return false;
231}
232
Mel Gormanc67fe372012-08-21 16:16:17 -0700233/*
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100234 * Isolate free pages onto a private freelist. Caller must hold zone->lock.
235 * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
236 * pages inside of the pageblock (even though it may still end up isolating
237 * some pages).
238 */
Mel Gormanf40d1e42012-10-08 16:32:36 -0700239static unsigned long isolate_freepages_block(struct compact_control *cc,
240 unsigned long blockpfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100241 unsigned long end_pfn,
242 struct list_head *freelist,
243 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -0700244{
Mel Gormanb7aba692011-01-13 15:45:54 -0800245 int nr_scanned = 0, total_isolated = 0;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700246 struct page *cursor, *valid_page = NULL;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700247 unsigned long nr_strict_required = end_pfn - blockpfn;
248 unsigned long flags;
249 bool locked = false;
Mel Gorman748446b2010-05-24 14:32:27 -0700250
Mel Gorman748446b2010-05-24 14:32:27 -0700251 cursor = pfn_to_page(blockpfn);
252
Mel Gormanf40d1e42012-10-08 16:32:36 -0700253 /* Isolate free pages. */
Mel Gorman748446b2010-05-24 14:32:27 -0700254 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
255 int isolated, i;
256 struct page *page = cursor;
257
Mel Gormanb7aba692011-01-13 15:45:54 -0800258 nr_scanned++;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700259 if (!pfn_valid_within(blockpfn))
Mel Gorman748446b2010-05-24 14:32:27 -0700260 continue;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700261 if (!valid_page)
262 valid_page = page;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700263 if (!PageBuddy(page))
264 continue;
265
266 /*
267 * The zone lock must be held to isolate freepages.
268 * Unfortunately this is a very coarse lock and can be
269 * heavily contended if there are parallel allocations
270 * or parallel compactions. For async compaction do not
271 * spin on the lock and we acquire the lock as late as
272 * possible.
273 */
274 locked = compact_checklock_irqsave(&cc->zone->lock, &flags,
275 locked, cc);
276 if (!locked)
277 break;
278
279 /* Recheck this is a suitable migration target under lock */
280 if (!strict && !suitable_migration_target(page))
281 break;
282
283 /* Recheck this is a buddy page under lock */
284 if (!PageBuddy(page))
285 continue;
Mel Gorman748446b2010-05-24 14:32:27 -0700286
287 /* Found a free page, break it into order-0 pages */
288 isolated = split_free_page(page);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100289 if (!isolated && strict)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700290 break;
Mel Gorman748446b2010-05-24 14:32:27 -0700291 total_isolated += isolated;
292 for (i = 0; i < isolated; i++) {
293 list_add(&page->lru, freelist);
294 page++;
295 }
296
297 /* If a page was split, advance to the end of it */
298 if (isolated) {
299 blockpfn += isolated - 1;
300 cursor += isolated - 1;
301 }
302 }
303
Mel Gormanb7aba692011-01-13 15:45:54 -0800304 trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
Mel Gormanf40d1e42012-10-08 16:32:36 -0700305
306 /*
307 * If strict isolation is requested by CMA then check that all the
308 * pages requested were isolated. If there were any failures, 0 is
309 * returned and CMA will fail.
310 */
Mel Gorman0db63d72012-10-19 13:56:57 -0700311 if (strict && nr_strict_required > total_isolated)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700312 total_isolated = 0;
313
314 if (locked)
315 spin_unlock_irqrestore(&cc->zone->lock, flags);
316
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700317 /* Update the pageblock-skip if the whole pageblock was scanned */
318 if (blockpfn == end_pfn)
Mel Gormanc89511a2012-10-08 16:32:45 -0700319 update_pageblock_skip(cc, valid_page, total_isolated, false);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700320
Minchan Kim010fc292012-12-20 15:05:06 -0800321 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100322 if (total_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800323 count_compact_events(COMPACTISOLATED, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700324 return total_isolated;
325}
326
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100327/**
328 * isolate_freepages_range() - isolate free pages.
329 * @start_pfn: The first PFN to start isolating.
330 * @end_pfn: The one-past-last PFN.
331 *
332 * Non-free pages, invalid PFNs, or zone boundaries within the
333 * [start_pfn, end_pfn) range are considered errors, cause function to
334 * undo its actions and return zero.
335 *
336 * Otherwise, function returns one-past-the-last PFN of isolated page
337 * (which may be greater then end_pfn if end fell in a middle of
338 * a free page).
339 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100340unsigned long
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700341isolate_freepages_range(struct compact_control *cc,
342 unsigned long start_pfn, unsigned long end_pfn)
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100343{
Mel Gormanf40d1e42012-10-08 16:32:36 -0700344 unsigned long isolated, pfn, block_end_pfn;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100345 LIST_HEAD(freelist);
346
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100347 for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700348 if (!pfn_valid(pfn) || cc->zone != page_zone(pfn_to_page(pfn)))
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100349 break;
350
351 /*
352 * On subsequent iterations ALIGN() is actually not needed,
353 * but we keep it that we not to complicate the code.
354 */
355 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
356 block_end_pfn = min(block_end_pfn, end_pfn);
357
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700358 isolated = isolate_freepages_block(cc, pfn, block_end_pfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100359 &freelist, true);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100360
361 /*
362 * In strict mode, isolate_freepages_block() returns 0 if
363 * there are any holes in the block (ie. invalid PFNs or
364 * non-free pages).
365 */
366 if (!isolated)
367 break;
368
369 /*
370 * If we managed to isolate pages, it is always (1 << n) *
371 * pageblock_nr_pages for some non-negative n. (Max order
372 * page may span two pageblocks).
373 */
374 }
375
376 /* split_free_page does not map the pages */
377 map_pages(&freelist);
378
379 if (pfn < end_pfn) {
380 /* Loop terminated early, cleanup. */
381 release_freepages(&freelist);
382 return 0;
383 }
384
385 /* We don't use freelists for anything. */
386 return pfn;
387}
388
Mel Gorman748446b2010-05-24 14:32:27 -0700389/* Update the number of anon and file isolated pages in the zone */
Mel Gormanc67fe372012-08-21 16:16:17 -0700390static void acct_isolated(struct zone *zone, bool locked, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700391{
392 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700393 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700394
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700395 list_for_each_entry(page, &cc->migratepages, lru)
396 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700397
Mel Gormanc67fe372012-08-21 16:16:17 -0700398 /* If locked we can use the interrupt unsafe versions */
399 if (locked) {
400 __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
401 __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
402 } else {
403 mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
404 mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
405 }
Mel Gorman748446b2010-05-24 14:32:27 -0700406}
407
408/* Similar to reclaim, but different enough that they don't share logic */
409static bool too_many_isolated(struct zone *zone)
410{
Minchan Kimbc693042010-09-09 16:38:00 -0700411 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700412
413 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
414 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700415 active = zone_page_state(zone, NR_ACTIVE_FILE) +
416 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700417 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
418 zone_page_state(zone, NR_ISOLATED_ANON);
419
Minchan Kimbc693042010-09-09 16:38:00 -0700420 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700421}
422
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100423/**
424 * isolate_migratepages_range() - isolate all migrate-able pages in range.
425 * @zone: Zone pages are in.
426 * @cc: Compaction control structure.
427 * @low_pfn: The first PFN of the range.
428 * @end_pfn: The one-past-the-last PFN of the range.
Minchan Kime46a2872012-10-08 16:33:48 -0700429 * @unevictable: true if it allows to isolate unevictable pages
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100430 *
431 * Isolate all pages that can be migrated from the range specified by
432 * [low_pfn, end_pfn). Returns zero if there is a fatal signal
433 * pending), otherwise PFN of the first page that was not scanned
434 * (which may be both less, equal to or more then end_pfn).
435 *
436 * Assumes that cc->migratepages is empty and cc->nr_migratepages is
437 * zero.
438 *
439 * Apart from cc->migratepages and cc->nr_migratetypes this function
440 * does not modify any cc's fields, in particular it does not modify
441 * (or read for that matter) cc->migrate_pfn.
Mel Gorman748446b2010-05-24 14:32:27 -0700442 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100443unsigned long
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100444isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
Minchan Kime46a2872012-10-08 16:33:48 -0700445 unsigned long low_pfn, unsigned long end_pfn, bool unevictable)
Mel Gorman748446b2010-05-24 14:32:27 -0700446{
Mel Gorman9927af742011-01-13 15:45:59 -0800447 unsigned long last_pageblock_nr = 0, pageblock_nr;
Mel Gormanb7aba692011-01-13 15:45:54 -0800448 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700449 struct list_head *migratelist = &cc->migratepages;
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -0700450 isolate_mode_t mode = 0;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700451 struct lruvec *lruvec;
Mel Gormanc67fe372012-08-21 16:16:17 -0700452 unsigned long flags;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700453 bool locked = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700454 struct page *page = NULL, *valid_page = NULL;
Mel Gorman748446b2010-05-24 14:32:27 -0700455
Mel Gorman748446b2010-05-24 14:32:27 -0700456 /*
457 * Ensure that there are not too many pages isolated from the LRU
458 * list by either parallel reclaimers or compaction. If there are,
459 * delay for some time until fewer pages are isolated
460 */
461 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700462 /* async migration should just abort */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700463 if (!cc->sync)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100464 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700465
Mel Gorman748446b2010-05-24 14:32:27 -0700466 congestion_wait(BLK_RW_ASYNC, HZ/10);
467
468 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100469 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700470 }
471
472 /* Time to isolate some pages for migration */
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700473 cond_resched();
Mel Gorman748446b2010-05-24 14:32:27 -0700474 for (; low_pfn < end_pfn; low_pfn++) {
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700475 /* give a chance to irqs before checking need_resched() */
Mel Gorman2a1402a2012-10-08 16:32:33 -0700476 if (locked && !((low_pfn+1) % SWAP_CLUSTER_MAX)) {
477 if (should_release_lock(&zone->lru_lock)) {
478 spin_unlock_irqrestore(&zone->lru_lock, flags);
479 locked = false;
480 }
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700481 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700482
Mel Gorman0bf380b2012-02-03 15:37:18 -0800483 /*
484 * migrate_pfn does not necessarily start aligned to a
485 * pageblock. Ensure that pfn_valid is called when moving
486 * into a new MAX_ORDER_NR_PAGES range in case of large
487 * memory holes within the zone
488 */
489 if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
490 if (!pfn_valid(low_pfn)) {
491 low_pfn += MAX_ORDER_NR_PAGES - 1;
492 continue;
493 }
494 }
495
Mel Gorman748446b2010-05-24 14:32:27 -0700496 if (!pfn_valid_within(low_pfn))
497 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800498 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700499
Mel Gormandc908602012-02-08 17:13:38 -0800500 /*
501 * Get the page and ensure the page is within the same zone.
502 * See the comment in isolate_freepages about overlapping
503 * nodes. It is deliberate that the new zone lock is not taken
504 * as memory compaction should not move pages between nodes.
505 */
Mel Gorman748446b2010-05-24 14:32:27 -0700506 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800507 if (page_zone(page) != zone)
508 continue;
509
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700510 if (!valid_page)
511 valid_page = page;
512
513 /* If isolation recently failed, do not retry */
514 pageblock_nr = low_pfn >> pageblock_order;
515 if (!isolation_suitable(cc, page))
516 goto next_pageblock;
517
Mel Gormandc908602012-02-08 17:13:38 -0800518 /* Skip if free */
Mel Gorman748446b2010-05-24 14:32:27 -0700519 if (PageBuddy(page))
520 continue;
521
Mel Gorman9927af742011-01-13 15:45:59 -0800522 /*
523 * For async migration, also only scan in MOVABLE blocks. Async
524 * migration is optimistic to see if the minimum amount of work
525 * satisfies the allocation
526 */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700527 if (!cc->sync && last_pageblock_nr != pageblock_nr &&
Michal Nazarewicz47118af2011-12-29 13:09:50 +0100528 !migrate_async_suitable(get_pageblock_migratetype(page))) {
Mel Gormanc89511a2012-10-08 16:32:45 -0700529 cc->finished_update_migrate = true;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700530 goto next_pageblock;
Mel Gorman9927af742011-01-13 15:45:59 -0800531 }
532
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800533 /*
534 * Check may be lockless but that's ok as we recheck later.
535 * It's possible to migrate LRU pages and balloon pages
536 * Skip any other type of page
537 */
538 if (!PageLRU(page)) {
539 if (unlikely(balloon_page_movable(page))) {
540 if (locked && balloon_page_isolate(page)) {
541 /* Successfully isolated */
542 cc->finished_update_migrate = true;
543 list_add(&page->lru, migratelist);
544 cc->nr_migratepages++;
545 nr_isolated++;
546 goto check_compact_cluster;
547 }
548 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800549 continue;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800550 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800551
552 /*
Mel Gorman2a1402a2012-10-08 16:32:33 -0700553 * PageLRU is set. lru_lock normally excludes isolation
554 * splitting and collapsing (collapsing has already happened
555 * if PageLRU is set) but the lock is not necessarily taken
556 * here and it is wasteful to take it just to check transhuge.
557 * Check TransHuge without lock and skip the whole pageblock if
558 * it's either a transhuge or hugetlbfs page, as calling
559 * compound_order() without preventing THP from splitting the
560 * page underneath us may return surprising results.
Andrea Arcangelibc835012011-01-13 15:47:08 -0800561 */
562 if (PageTransHuge(page)) {
Mel Gorman2a1402a2012-10-08 16:32:33 -0700563 if (!locked)
564 goto next_pageblock;
565 low_pfn += (1 << compound_order(page)) - 1;
566 continue;
567 }
568
569 /* Check if it is ok to still hold the lock */
570 locked = compact_checklock_irqsave(&zone->lru_lock, &flags,
571 locked, cc);
572 if (!locked || fatal_signal_pending(current))
573 break;
574
575 /* Recheck PageLRU and PageTransHuge under lock */
576 if (!PageLRU(page))
577 continue;
578 if (PageTransHuge(page)) {
Andrea Arcangelibc835012011-01-13 15:47:08 -0800579 low_pfn += (1 << compound_order(page)) - 1;
580 continue;
581 }
582
Linus Torvalds68e3e922012-06-03 20:05:57 -0700583 if (!cc->sync)
Mel Gormanc8244932012-01-12 17:19:38 -0800584 mode |= ISOLATE_ASYNC_MIGRATE;
585
Minchan Kime46a2872012-10-08 16:33:48 -0700586 if (unevictable)
587 mode |= ISOLATE_UNEVICTABLE;
588
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700589 lruvec = mem_cgroup_page_lruvec(page, zone);
590
Mel Gorman748446b2010-05-24 14:32:27 -0700591 /* Try isolate the page */
Konstantin Khlebnikovf3fd4a62012-05-29 15:06:54 -0700592 if (__isolate_lru_page(page, mode) != 0)
Mel Gorman748446b2010-05-24 14:32:27 -0700593 continue;
594
Andrea Arcangelibc835012011-01-13 15:47:08 -0800595 VM_BUG_ON(PageTransCompound(page));
596
Mel Gorman748446b2010-05-24 14:32:27 -0700597 /* Successfully isolated */
Mel Gormanc89511a2012-10-08 16:32:45 -0700598 cc->finished_update_migrate = true;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700599 del_page_from_lru_list(page, lruvec, page_lru(page));
Mel Gorman748446b2010-05-24 14:32:27 -0700600 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700601 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800602 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700603
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800604check_compact_cluster:
Mel Gorman748446b2010-05-24 14:32:27 -0700605 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800606 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
607 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700608 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800609 }
Mel Gorman2a1402a2012-10-08 16:32:33 -0700610
611 continue;
612
613next_pageblock:
614 low_pfn += pageblock_nr_pages;
615 low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
616 last_pageblock_nr = pageblock_nr;
Mel Gorman748446b2010-05-24 14:32:27 -0700617 }
618
Mel Gormanc67fe372012-08-21 16:16:17 -0700619 acct_isolated(zone, locked, cc);
Mel Gorman748446b2010-05-24 14:32:27 -0700620
Mel Gormanc67fe372012-08-21 16:16:17 -0700621 if (locked)
622 spin_unlock_irqrestore(&zone->lru_lock, flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700623
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700624 /* Update the pageblock-skip if the whole pageblock was scanned */
625 if (low_pfn == end_pfn)
Mel Gormanc89511a2012-10-08 16:32:45 -0700626 update_pageblock_skip(cc, valid_page, nr_isolated, true);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700627
Mel Gormanb7aba692011-01-13 15:45:54 -0800628 trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
629
Minchan Kim010fc292012-12-20 15:05:06 -0800630 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100631 if (nr_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800632 count_compact_events(COMPACTISOLATED, nr_isolated);
Mel Gorman397487d2012-10-19 12:00:10 +0100633
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100634 return low_pfn;
635}
636
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100637#endif /* CONFIG_COMPACTION || CONFIG_CMA */
638#ifdef CONFIG_COMPACTION
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100639/*
640 * Based on information in the current compact_control, find blocks
641 * suitable for isolating free pages from and then isolate them.
642 */
643static void isolate_freepages(struct zone *zone,
644 struct compact_control *cc)
645{
646 struct page *page;
647 unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100648 int nr_freepages = cc->nr_freepages;
649 struct list_head *freelist = &cc->freepages;
650
651 /*
652 * Initialise the free scanner. The starting point is where we last
653 * scanned from (or the end of the zone if starting). The low point
654 * is the end of the pageblock the migration scanner is using.
655 */
656 pfn = cc->free_pfn;
657 low_pfn = cc->migrate_pfn + pageblock_nr_pages;
658
659 /*
660 * Take care that if the migration scanner is at the end of the zone
661 * that the free scanner does not accidentally move to the next zone
662 * in the next isolation cycle.
663 */
664 high_pfn = min(low_pfn, pfn);
665
666 zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
667
668 /*
669 * Isolate free pages until enough are available to migrate the
670 * pages on cc->migratepages. We stop searching if the migrate
671 * and free page scanners meet or enough free pages are isolated.
672 */
673 for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
674 pfn -= pageblock_nr_pages) {
675 unsigned long isolated;
676
677 if (!pfn_valid(pfn))
678 continue;
679
680 /*
681 * Check for overlapping nodes/zones. It's possible on some
682 * configurations to have a setup like
683 * node0 node1 node0
684 * i.e. it's possible that all pages within a zones range of
685 * pages do not belong to a single zone.
686 */
687 page = pfn_to_page(pfn);
688 if (page_zone(page) != zone)
689 continue;
690
691 /* Check the block is suitable for migration */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700692 if (!suitable_migration_target(page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100693 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -0700694
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700695 /* If isolation recently failed, do not retry */
696 if (!isolation_suitable(cc, page))
697 continue;
698
Mel Gormanf40d1e42012-10-08 16:32:36 -0700699 /* Found a block suitable for isolating free pages from */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100700 isolated = 0;
Mel Gorman60177d32012-12-06 19:01:14 +0000701
702 /*
703 * As pfn may not start aligned, pfn+pageblock_nr_page
704 * may cross a MAX_ORDER_NR_PAGES boundary and miss
705 * a pfn_valid check. Ensure isolate_freepages_block()
706 * only scans within a pageblock
707 */
708 end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
709 end_pfn = min(end_pfn, zone_end_pfn);
Mel Gormanf40d1e42012-10-08 16:32:36 -0700710 isolated = isolate_freepages_block(cc, pfn, end_pfn,
711 freelist, false);
712 nr_freepages += isolated;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100713
714 /*
715 * Record the highest PFN we isolated pages from. When next
716 * looking for free pages, the search will restart here as
717 * page migration may have returned some pages to the allocator
718 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700719 if (isolated) {
720 cc->finished_update_free = true;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100721 high_pfn = max(high_pfn, pfn);
Mel Gormanc89511a2012-10-08 16:32:45 -0700722 }
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100723 }
724
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100725 /* split_free_page does not map the pages */
726 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100727
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100728 cc->free_pfn = high_pfn;
729 cc->nr_freepages = nr_freepages;
Mel Gorman748446b2010-05-24 14:32:27 -0700730}
731
732/*
733 * This is a migrate-callback that "allocates" freepages by taking pages
734 * from the isolated freelists in the block we are migrating to.
735 */
736static struct page *compaction_alloc(struct page *migratepage,
737 unsigned long data,
738 int **result)
739{
740 struct compact_control *cc = (struct compact_control *)data;
741 struct page *freepage;
742
743 /* Isolate free pages if necessary */
744 if (list_empty(&cc->freepages)) {
745 isolate_freepages(cc->zone, cc);
746
747 if (list_empty(&cc->freepages))
748 return NULL;
749 }
750
751 freepage = list_entry(cc->freepages.next, struct page, lru);
752 list_del(&freepage->lru);
753 cc->nr_freepages--;
754
755 return freepage;
756}
757
758/*
759 * We cannot control nr_migratepages and nr_freepages fully when migration is
760 * running as migrate_pages() has no knowledge of compact_control. When
761 * migration is complete, we count the number of pages on the lists by hand.
762 */
763static void update_nr_listpages(struct compact_control *cc)
764{
765 int nr_migratepages = 0;
766 int nr_freepages = 0;
767 struct page *page;
768
769 list_for_each_entry(page, &cc->migratepages, lru)
770 nr_migratepages++;
771 list_for_each_entry(page, &cc->freepages, lru)
772 nr_freepages++;
773
774 cc->nr_migratepages = nr_migratepages;
775 cc->nr_freepages = nr_freepages;
776}
777
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100778/* possible outcome of isolate_migratepages */
779typedef enum {
780 ISOLATE_ABORT, /* Abort compaction now */
781 ISOLATE_NONE, /* No pages isolated, continue scanning */
782 ISOLATE_SUCCESS, /* Pages isolated, migrate */
783} isolate_migrate_t;
784
785/*
786 * Isolate all pages that can be migrated from the block pointed to by
787 * the migrate scanner within compact_control.
788 */
789static isolate_migrate_t isolate_migratepages(struct zone *zone,
790 struct compact_control *cc)
791{
792 unsigned long low_pfn, end_pfn;
793
794 /* Do not scan outside zone boundaries */
795 low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
796
797 /* Only scan within a pageblock boundary */
798 end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
799
800 /* Do not cross the free scanner or scan within a memory hole */
801 if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
802 cc->migrate_pfn = end_pfn;
803 return ISOLATE_NONE;
804 }
805
806 /* Perform the isolation */
Minchan Kime46a2872012-10-08 16:33:48 -0700807 low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn, false);
Shaohua Lie64c5232012-10-08 16:32:27 -0700808 if (!low_pfn || cc->contended)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100809 return ISOLATE_ABORT;
810
811 cc->migrate_pfn = low_pfn;
812
813 return ISOLATE_SUCCESS;
814}
815
Mel Gorman748446b2010-05-24 14:32:27 -0700816static int compact_finished(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800817 struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700818{
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800819 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -0700820
Mel Gorman748446b2010-05-24 14:32:27 -0700821 if (fatal_signal_pending(current))
822 return COMPACT_PARTIAL;
823
Mel Gorman753341a2012-10-08 16:32:40 -0700824 /* Compaction run completes if the migrate and free scanner meet */
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700825 if (cc->free_pfn <= cc->migrate_pfn) {
Mel Gorman62997022012-10-08 16:32:47 -0700826 /*
827 * Mark that the PG_migrate_skip information should be cleared
828 * by kswapd when it goes to sleep. kswapd does not set the
829 * flag itself as the decision to be clear should be directly
830 * based on an allocation request.
831 */
832 if (!current_is_kswapd())
833 zone->compact_blockskip_flush = true;
834
Mel Gorman748446b2010-05-24 14:32:27 -0700835 return COMPACT_COMPLETE;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700836 }
Mel Gorman748446b2010-05-24 14:32:27 -0700837
Johannes Weiner82478fb2011-01-20 14:44:21 -0800838 /*
839 * order == -1 is expected when compacting via
840 * /proc/sys/vm/compact_memory
841 */
Mel Gorman56de7262010-05-24 14:32:30 -0700842 if (cc->order == -1)
843 return COMPACT_CONTINUE;
844
Michal Hocko3957c772011-06-15 15:08:25 -0700845 /* Compaction run is not finished if the watermark is not met */
846 watermark = low_wmark_pages(zone);
847 watermark += (1 << cc->order);
848
849 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
850 return COMPACT_CONTINUE;
851
Mel Gorman56de7262010-05-24 14:32:30 -0700852 /* Direct compactor: Is a suitable page free? */
Mel Gorman1fb3f8c2012-10-08 16:29:12 -0700853 if (cc->page) {
854 /* Was a suitable page captured? */
855 if (*cc->page)
Mel Gorman56de7262010-05-24 14:32:30 -0700856 return COMPACT_PARTIAL;
Mel Gorman1fb3f8c2012-10-08 16:29:12 -0700857 } else {
858 unsigned int order;
859 for (order = cc->order; order < MAX_ORDER; order++) {
860 struct free_area *area = &zone->free_area[cc->order];
861 /* Job done if page is free of the right migratetype */
862 if (!list_empty(&area->free_list[cc->migratetype]))
863 return COMPACT_PARTIAL;
Mel Gorman56de7262010-05-24 14:32:30 -0700864
Mel Gorman1fb3f8c2012-10-08 16:29:12 -0700865 /* Job done if allocation would set block type */
866 if (cc->order >= pageblock_order && area->nr_free)
867 return COMPACT_PARTIAL;
868 }
Mel Gorman56de7262010-05-24 14:32:30 -0700869 }
870
Mel Gorman748446b2010-05-24 14:32:27 -0700871 return COMPACT_CONTINUE;
872}
873
Mel Gorman3e7d3442011-01-13 15:45:56 -0800874/*
875 * compaction_suitable: Is this suitable to run compaction on this zone now?
876 * Returns
877 * COMPACT_SKIPPED - If there are too few free pages for compaction
878 * COMPACT_PARTIAL - If the allocation would succeed without compaction
879 * COMPACT_CONTINUE - If compaction should run now
880 */
881unsigned long compaction_suitable(struct zone *zone, int order)
882{
883 int fragindex;
884 unsigned long watermark;
885
886 /*
Michal Hocko3957c772011-06-15 15:08:25 -0700887 * order == -1 is expected when compacting via
888 * /proc/sys/vm/compact_memory
889 */
890 if (order == -1)
891 return COMPACT_CONTINUE;
892
893 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800894 * Watermarks for order-0 must be met for compaction. Note the 2UL.
895 * This is because during migration, copies of pages need to be
896 * allocated and for a short time, the footprint is higher
897 */
898 watermark = low_wmark_pages(zone) + (2UL << order);
899 if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
900 return COMPACT_SKIPPED;
901
902 /*
903 * fragmentation index determines if allocation failures are due to
904 * low memory or external fragmentation
905 *
Shaohua Lia582a732011-06-15 15:08:49 -0700906 * index of -1000 implies allocations might succeed depending on
907 * watermarks
Mel Gorman3e7d3442011-01-13 15:45:56 -0800908 * index towards 0 implies failure is due to lack of memory
909 * index towards 1000 implies failure is due to fragmentation
910 *
911 * Only compact if a failure would be due to fragmentation.
912 */
913 fragindex = fragmentation_index(zone, order);
914 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
915 return COMPACT_SKIPPED;
916
Shaohua Lia582a732011-06-15 15:08:49 -0700917 if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
918 0, 0))
Mel Gorman3e7d3442011-01-13 15:45:56 -0800919 return COMPACT_PARTIAL;
920
921 return COMPACT_CONTINUE;
922}
923
Thierry Redingc8bf2d82012-12-12 13:51:17 -0800924static void compact_capture_page(struct compact_control *cc)
925{
926 unsigned long flags;
927 int mtype, mtype_low, mtype_high;
928
929 if (!cc->page || *cc->page)
930 return;
931
932 /*
933 * For MIGRATE_MOVABLE allocations we capture a suitable page ASAP
934 * regardless of the migratetype of the freelist is is captured from.
935 * This is fine because the order for a high-order MIGRATE_MOVABLE
936 * allocation is typically at least a pageblock size and overall
937 * fragmentation is not impaired. Other allocation types must
938 * capture pages from their own migratelist because otherwise they
939 * could pollute other pageblocks like MIGRATE_MOVABLE with
940 * difficult to move pages and making fragmentation worse overall.
941 */
942 if (cc->migratetype == MIGRATE_MOVABLE) {
943 mtype_low = 0;
944 mtype_high = MIGRATE_PCPTYPES;
945 } else {
946 mtype_low = cc->migratetype;
947 mtype_high = cc->migratetype + 1;
948 }
949
950 /* Speculatively examine the free lists without zone lock */
951 for (mtype = mtype_low; mtype < mtype_high; mtype++) {
952 int order;
953 for (order = cc->order; order < MAX_ORDER; order++) {
954 struct page *page;
955 struct free_area *area;
956 area = &(cc->zone->free_area[order]);
957 if (list_empty(&area->free_list[mtype]))
958 continue;
959
960 /* Take the lock and attempt capture of the page */
961 if (!compact_trylock_irqsave(&cc->zone->lock, &flags, cc))
962 return;
963 if (!list_empty(&area->free_list[mtype])) {
964 page = list_entry(area->free_list[mtype].next,
965 struct page, lru);
966 if (capture_free_page(page, cc->order, mtype)) {
967 spin_unlock_irqrestore(&cc->zone->lock,
968 flags);
969 *cc->page = page;
970 return;
971 }
972 }
973 spin_unlock_irqrestore(&cc->zone->lock, flags);
974 }
975 }
976}
977
Mel Gorman748446b2010-05-24 14:32:27 -0700978static int compact_zone(struct zone *zone, struct compact_control *cc)
979{
980 int ret;
Mel Gormanc89511a2012-10-08 16:32:45 -0700981 unsigned long start_pfn = zone->zone_start_pfn;
982 unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
Mel Gorman748446b2010-05-24 14:32:27 -0700983
Mel Gorman3e7d3442011-01-13 15:45:56 -0800984 ret = compaction_suitable(zone, cc->order);
985 switch (ret) {
986 case COMPACT_PARTIAL:
987 case COMPACT_SKIPPED:
988 /* Compaction is likely to fail */
989 return ret;
990 case COMPACT_CONTINUE:
991 /* Fall through to compaction */
992 ;
993 }
994
Mel Gormanc89511a2012-10-08 16:32:45 -0700995 /*
996 * Setup to move all movable pages to the end of the zone. Used cached
997 * information on where the scanners should start but check that it
998 * is initialised by ensuring the values are within zone boundaries.
999 */
1000 cc->migrate_pfn = zone->compact_cached_migrate_pfn;
1001 cc->free_pfn = zone->compact_cached_free_pfn;
1002 if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
1003 cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
1004 zone->compact_cached_free_pfn = cc->free_pfn;
1005 }
1006 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) {
1007 cc->migrate_pfn = start_pfn;
1008 zone->compact_cached_migrate_pfn = cc->migrate_pfn;
1009 }
Mel Gorman748446b2010-05-24 14:32:27 -07001010
Mel Gorman62997022012-10-08 16:32:47 -07001011 /*
1012 * Clear pageblock skip if there were failures recently and compaction
1013 * is about to be retried after being deferred. kswapd does not do
1014 * this reset as it'll reset the cached information when going to sleep.
1015 */
1016 if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
1017 __reset_isolation_suitable(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001018
Mel Gorman748446b2010-05-24 14:32:27 -07001019 migrate_prep_local();
1020
1021 while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
1022 unsigned long nr_migrate, nr_remaining;
Minchan Kim9d502c12011-03-22 16:30:39 -07001023 int err;
Mel Gorman748446b2010-05-24 14:32:27 -07001024
Mel Gormanf9e35b32011-06-15 15:08:52 -07001025 switch (isolate_migratepages(zone, cc)) {
1026 case ISOLATE_ABORT:
1027 ret = COMPACT_PARTIAL;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001028 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001029 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001030 goto out;
1031 case ISOLATE_NONE:
Mel Gorman748446b2010-05-24 14:32:27 -07001032 continue;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001033 case ISOLATE_SUCCESS:
1034 ;
1035 }
Mel Gorman748446b2010-05-24 14:32:27 -07001036
1037 nr_migrate = cc->nr_migratepages;
Minchan Kim9d502c12011-03-22 16:30:39 -07001038 err = migrate_pages(&cc->migratepages, compaction_alloc,
Linus Torvalds68e3e922012-06-03 20:05:57 -07001039 (unsigned long)cc, false,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001040 cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC,
1041 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001042 update_nr_listpages(cc);
1043 nr_remaining = cc->nr_migratepages;
1044
Mel Gormanb7aba692011-01-13 15:45:54 -08001045 trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
1046 nr_remaining);
Mel Gorman748446b2010-05-24 14:32:27 -07001047
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001048 /* Release isolated pages not migrated */
Minchan Kim9d502c12011-03-22 16:30:39 -07001049 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001050 putback_movable_pages(&cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001051 cc->nr_migratepages = 0;
David Rientjes4bf2bba2012-07-11 14:02:13 -07001052 if (err == -ENOMEM) {
1053 ret = COMPACT_PARTIAL;
1054 goto out;
1055 }
Mel Gorman748446b2010-05-24 14:32:27 -07001056 }
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001057
1058 /* Capture a page now if it is a suitable size */
1059 compact_capture_page(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001060 }
1061
Mel Gormanf9e35b32011-06-15 15:08:52 -07001062out:
Mel Gorman748446b2010-05-24 14:32:27 -07001063 /* Release free pages and check accounting */
1064 cc->nr_freepages -= release_freepages(&cc->freepages);
1065 VM_BUG_ON(cc->nr_freepages != 0);
1066
1067 return ret;
1068}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001069
Kyungmin Parkd43a87e2011-10-31 17:09:08 -07001070static unsigned long compact_zone_order(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001071 int order, gfp_t gfp_mask,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001072 bool sync, bool *contended,
1073 struct page **page)
Mel Gorman56de7262010-05-24 14:32:30 -07001074{
Shaohua Lie64c5232012-10-08 16:32:27 -07001075 unsigned long ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001076 struct compact_control cc = {
1077 .nr_freepages = 0,
1078 .nr_migratepages = 0,
1079 .order = order,
1080 .migratetype = allocflags_to_migratetype(gfp_mask),
1081 .zone = zone,
Linus Torvalds68e3e922012-06-03 20:05:57 -07001082 .sync = sync,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001083 .page = page,
Mel Gorman56de7262010-05-24 14:32:30 -07001084 };
1085 INIT_LIST_HEAD(&cc.freepages);
1086 INIT_LIST_HEAD(&cc.migratepages);
1087
Shaohua Lie64c5232012-10-08 16:32:27 -07001088 ret = compact_zone(zone, &cc);
1089
1090 VM_BUG_ON(!list_empty(&cc.freepages));
1091 VM_BUG_ON(!list_empty(&cc.migratepages));
1092
1093 *contended = cc.contended;
1094 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001095}
1096
Mel Gorman5e771902010-05-24 14:32:31 -07001097int sysctl_extfrag_threshold = 500;
1098
Mel Gorman56de7262010-05-24 14:32:30 -07001099/**
1100 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
1101 * @zonelist: The zonelist used for the current allocation
1102 * @order: The order of the current allocation
1103 * @gfp_mask: The GFP mask of the current allocation
1104 * @nodemask: The allowed nodes to allocate from
Mel Gorman77f1fe62011-01-13 15:45:57 -08001105 * @sync: Whether migration is synchronous or not
Mel Gorman661c4cb2012-10-08 16:32:31 -07001106 * @contended: Return value that is true if compaction was aborted due to lock contention
1107 * @page: Optionally capture a free page of the requested order during compaction
Mel Gorman56de7262010-05-24 14:32:30 -07001108 *
1109 * This is the main entry point for direct page compaction.
1110 */
1111unsigned long try_to_compact_pages(struct zonelist *zonelist,
Mel Gorman77f1fe62011-01-13 15:45:57 -08001112 int order, gfp_t gfp_mask, nodemask_t *nodemask,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001113 bool sync, bool *contended, struct page **page)
Mel Gorman56de7262010-05-24 14:32:30 -07001114{
1115 enum zone_type high_zoneidx = gfp_zone(gfp_mask);
1116 int may_enter_fs = gfp_mask & __GFP_FS;
1117 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001118 struct zoneref *z;
1119 struct zone *zone;
1120 int rc = COMPACT_SKIPPED;
Bartlomiej Zolnierkiewiczd95ea5d2012-10-08 16:32:05 -07001121 int alloc_flags = 0;
Mel Gorman56de7262010-05-24 14:32:30 -07001122
Mel Gorman4ffb6332012-10-08 16:29:09 -07001123 /* Check if the GFP flags allow compaction */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -08001124 if (!order || !may_enter_fs || !may_perform_io)
Mel Gorman56de7262010-05-24 14:32:30 -07001125 return rc;
1126
Minchan Kim010fc292012-12-20 15:05:06 -08001127 count_compact_event(COMPACTSTALL);
Mel Gorman56de7262010-05-24 14:32:30 -07001128
Bartlomiej Zolnierkiewiczd95ea5d2012-10-08 16:32:05 -07001129#ifdef CONFIG_CMA
1130 if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
1131 alloc_flags |= ALLOC_CMA;
1132#endif
Mel Gorman56de7262010-05-24 14:32:30 -07001133 /* Compact each zone in the list */
1134 for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
1135 nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -07001136 int status;
1137
Mel Gormanc67fe372012-08-21 16:16:17 -07001138 status = compact_zone_order(zone, order, gfp_mask, sync,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001139 contended, page);
Mel Gorman56de7262010-05-24 14:32:30 -07001140 rc = max(status, rc);
1141
Mel Gorman3e7d3442011-01-13 15:45:56 -08001142 /* If a normal allocation would succeed, stop compacting */
Bartlomiej Zolnierkiewiczd95ea5d2012-10-08 16:32:05 -07001143 if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0,
1144 alloc_flags))
Mel Gorman56de7262010-05-24 14:32:30 -07001145 break;
1146 }
1147
1148 return rc;
1149}
1150
1151
Mel Gorman76ab0f52010-05-24 14:32:28 -07001152/* Compact all zones within a node */
Rik van Riel7be62de2012-03-21 16:33:52 -07001153static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001154{
1155 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -07001156 struct zone *zone;
1157
Mel Gorman76ab0f52010-05-24 14:32:28 -07001158 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -07001159
1160 zone = &pgdat->node_zones[zoneid];
1161 if (!populated_zone(zone))
1162 continue;
1163
Rik van Riel7be62de2012-03-21 16:33:52 -07001164 cc->nr_freepages = 0;
1165 cc->nr_migratepages = 0;
1166 cc->zone = zone;
1167 INIT_LIST_HEAD(&cc->freepages);
1168 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001169
Dan Carpenteraad6ec32012-03-21 16:33:54 -07001170 if (cc->order == -1 || !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -07001171 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001172
Rik van Rielaff62242012-03-21 16:33:52 -07001173 if (cc->order > 0) {
1174 int ok = zone_watermark_ok(zone, cc->order,
1175 low_wmark_pages(zone), 0, 0);
Minchan Kimc81758f2012-08-21 16:16:03 -07001176 if (ok && cc->order >= zone->compact_order_failed)
Rik van Rielaff62242012-03-21 16:33:52 -07001177 zone->compact_order_failed = cc->order + 1;
1178 /* Currently async compaction is never deferred. */
Linus Torvalds68e3e922012-06-03 20:05:57 -07001179 else if (!ok && cc->sync)
Rik van Rielaff62242012-03-21 16:33:52 -07001180 defer_compaction(zone, cc->order);
1181 }
1182
Rik van Riel7be62de2012-03-21 16:33:52 -07001183 VM_BUG_ON(!list_empty(&cc->freepages));
1184 VM_BUG_ON(!list_empty(&cc->migratepages));
Mel Gorman76ab0f52010-05-24 14:32:28 -07001185 }
1186
1187 return 0;
1188}
1189
Rik van Riel7be62de2012-03-21 16:33:52 -07001190int compact_pgdat(pg_data_t *pgdat, int order)
1191{
1192 struct compact_control cc = {
1193 .order = order,
Linus Torvalds68e3e922012-06-03 20:05:57 -07001194 .sync = false,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001195 .page = NULL,
Rik van Riel7be62de2012-03-21 16:33:52 -07001196 };
1197
1198 return __compact_pgdat(pgdat, &cc);
1199}
1200
1201static int compact_node(int nid)
1202{
Rik van Riel7be62de2012-03-21 16:33:52 -07001203 struct compact_control cc = {
1204 .order = -1,
Linus Torvalds68e3e922012-06-03 20:05:57 -07001205 .sync = true,
Mel Gorman1fb3f8c2012-10-08 16:29:12 -07001206 .page = NULL,
Rik van Riel7be62de2012-03-21 16:33:52 -07001207 };
1208
Hugh Dickins8575ec22012-03-21 16:33:53 -07001209 return __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001210}
1211
Mel Gorman76ab0f52010-05-24 14:32:28 -07001212/* Compact all nodes in the system */
1213static int compact_nodes(void)
1214{
1215 int nid;
1216
Hugh Dickins8575ec22012-03-21 16:33:53 -07001217 /* Flush pending updates to the LRU lists */
1218 lru_add_drain_all();
1219
Mel Gorman76ab0f52010-05-24 14:32:28 -07001220 for_each_online_node(nid)
1221 compact_node(nid);
1222
1223 return COMPACT_COMPLETE;
1224}
1225
1226/* The written value is actually unused, all memory is compacted */
1227int sysctl_compact_memory;
1228
1229/* This is the entry point for compacting all nodes via /proc/sys/vm */
1230int sysctl_compaction_handler(struct ctl_table *table, int write,
1231 void __user *buffer, size_t *length, loff_t *ppos)
1232{
1233 if (write)
1234 return compact_nodes();
1235
1236 return 0;
1237}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001238
Mel Gorman5e771902010-05-24 14:32:31 -07001239int sysctl_extfrag_handler(struct ctl_table *table, int write,
1240 void __user *buffer, size_t *length, loff_t *ppos)
1241{
1242 proc_dointvec_minmax(table, write, buffer, length, ppos);
1243
1244 return 0;
1245}
1246
Mel Gormaned4a6d72010-05-24 14:32:29 -07001247#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Kay Sievers10fbcf42011-12-21 14:48:43 -08001248ssize_t sysfs_compact_node(struct device *dev,
1249 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001250 const char *buf, size_t count)
1251{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001252 int nid = dev->id;
1253
1254 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1255 /* Flush pending updates to the LRU lists */
1256 lru_add_drain_all();
1257
1258 compact_node(nid);
1259 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001260
1261 return count;
1262}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001263static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001264
1265int compaction_register_node(struct node *node)
1266{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001267 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001268}
1269
1270void compaction_unregister_node(struct node *node)
1271{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001272 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001273}
1274#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001275
1276#endif /* CONFIG_COMPACTION */