blob: 018f08da99a2ece0aa25475c5f8f54bcc436f0eb [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>
Minchan Kim194159f2013-02-22 16:33:58 -080018#include <linux/page-isolation.h>
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080019#include <linux/kasan.h>
Mel Gorman748446b2010-05-24 14:32:27 -070020#include "internal.h"
21
Minchan Kim010fc292012-12-20 15:05:06 -080022#ifdef CONFIG_COMPACTION
23static inline void count_compact_event(enum vm_event_item item)
24{
25 count_vm_event(item);
26}
27
28static inline void count_compact_events(enum vm_event_item item, long delta)
29{
30 count_vm_events(item, delta);
31}
32#else
33#define count_compact_event(item) do { } while (0)
34#define count_compact_events(item, delta) do { } while (0)
35#endif
36
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010037#if defined CONFIG_COMPACTION || defined CONFIG_CMA
Joonsoo Kim16c4a092015-02-11 15:27:01 -080038#ifdef CONFIG_TRACEPOINTS
39static const char *const compaction_status_string[] = {
40 "deferred",
41 "skipped",
42 "continue",
43 "partial",
44 "complete",
Joonsoo Kim837d0262015-02-11 15:27:06 -080045 "no_suitable_page",
46 "not_suitable_zone",
Joonsoo Kim16c4a092015-02-11 15:27:01 -080047};
48#endif
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010049
Mel Gormanb7aba692011-01-13 15:45:54 -080050#define CREATE_TRACE_POINTS
51#include <trace/events/compaction.h>
52
Mel Gorman748446b2010-05-24 14:32:27 -070053static unsigned long release_freepages(struct list_head *freelist)
54{
55 struct page *page, *next;
Vlastimil Babka6bace092014-12-10 15:43:31 -080056 unsigned long high_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070057
58 list_for_each_entry_safe(page, next, freelist, lru) {
Vlastimil Babka6bace092014-12-10 15:43:31 -080059 unsigned long pfn = page_to_pfn(page);
Mel Gorman748446b2010-05-24 14:32:27 -070060 list_del(&page->lru);
61 __free_page(page);
Vlastimil Babka6bace092014-12-10 15:43:31 -080062 if (pfn > high_pfn)
63 high_pfn = pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070064 }
65
Vlastimil Babka6bace092014-12-10 15:43:31 -080066 return high_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070067}
68
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010069static void map_pages(struct list_head *list)
70{
71 struct page *page;
72
73 list_for_each_entry(page, list, lru) {
74 arch_alloc_page(page, 0);
75 kernel_map_pages(page, 1, 1);
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080076 kasan_alloc_pages(page, 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010077 }
78}
79
Michal Nazarewicz47118af2011-12-29 13:09:50 +010080static inline bool migrate_async_suitable(int migratetype)
81{
82 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
83}
84
Vlastimil Babka7d49d882014-10-09 15:27:11 -070085/*
86 * Check that the whole (or subset of) a pageblock given by the interval of
87 * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
88 * with the migration of free compaction scanner. The scanners then need to
89 * use only pfn_valid_within() check for arches that allow holes within
90 * pageblocks.
91 *
92 * Return struct page pointer of start_pfn, or NULL if checks were not passed.
93 *
94 * It's possible on some configurations to have a setup like node0 node1 node0
95 * i.e. it's possible that all pages within a zones range of pages do not
96 * belong to a single zone. We assume that a border between node0 and node1
97 * can occur within a single pageblock, but not a node0 node1 node0
98 * interleaving within a single pageblock. It is therefore sufficient to check
99 * the first and last page of a pageblock and avoid checking each individual
100 * page in a pageblock.
101 */
102static struct page *pageblock_pfn_to_page(unsigned long start_pfn,
103 unsigned long end_pfn, struct zone *zone)
104{
105 struct page *start_page;
106 struct page *end_page;
107
108 /* end_pfn is one past the range we are checking */
109 end_pfn--;
110
111 if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
112 return NULL;
113
114 start_page = pfn_to_page(start_pfn);
115
116 if (page_zone(start_page) != zone)
117 return NULL;
118
119 end_page = pfn_to_page(end_pfn);
120
121 /* This gives a shorter code than deriving page_zone(end_page) */
122 if (page_zone_id(start_page) != page_zone_id(end_page))
123 return NULL;
124
125 return start_page;
126}
127
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700128#ifdef CONFIG_COMPACTION
Joonsoo Kim24e27162015-02-11 15:27:09 -0800129
130/* Do not skip compaction more than 64 times */
131#define COMPACT_MAX_DEFER_SHIFT 6
132
133/*
134 * Compaction is deferred when compaction fails to result in a page
135 * allocation success. 1 << compact_defer_limit compactions are skipped up
136 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
137 */
138void defer_compaction(struct zone *zone, int order)
139{
140 zone->compact_considered = 0;
141 zone->compact_defer_shift++;
142
143 if (order < zone->compact_order_failed)
144 zone->compact_order_failed = order;
145
146 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
147 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
148
149 trace_mm_compaction_defer_compaction(zone, order);
150}
151
152/* Returns true if compaction should be skipped this time */
153bool compaction_deferred(struct zone *zone, int order)
154{
155 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
156
157 if (order < zone->compact_order_failed)
158 return false;
159
160 /* Avoid possible overflow */
161 if (++zone->compact_considered > defer_limit)
162 zone->compact_considered = defer_limit;
163
164 if (zone->compact_considered >= defer_limit)
165 return false;
166
167 trace_mm_compaction_deferred(zone, order);
168
169 return true;
170}
171
172/*
173 * Update defer tracking counters after successful compaction of given order,
174 * which means an allocation either succeeded (alloc_success == true) or is
175 * expected to succeed.
176 */
177void compaction_defer_reset(struct zone *zone, int order,
178 bool alloc_success)
179{
180 if (alloc_success) {
181 zone->compact_considered = 0;
182 zone->compact_defer_shift = 0;
183 }
184 if (order >= zone->compact_order_failed)
185 zone->compact_order_failed = order + 1;
186
187 trace_mm_compaction_defer_reset(zone, order);
188}
189
190/* Returns true if restarting compaction after many failures */
191bool compaction_restarting(struct zone *zone, int order)
192{
193 if (order < zone->compact_order_failed)
194 return false;
195
196 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
197 zone->compact_considered >= 1UL << zone->compact_defer_shift;
198}
199
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700200/* Returns true if the pageblock should be scanned for pages to isolate. */
201static inline bool isolation_suitable(struct compact_control *cc,
202 struct page *page)
203{
204 if (cc->ignore_skip_hint)
205 return true;
206
207 return !get_pageblock_skip(page);
208}
209
210/*
211 * This function is called to clear all cached information on pageblocks that
212 * should be skipped for page isolation when the migrate and free page scanner
213 * meet.
214 */
Mel Gorman62997022012-10-08 16:32:47 -0700215static void __reset_isolation_suitable(struct zone *zone)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700216{
217 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -0800218 unsigned long end_pfn = zone_end_pfn(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700219 unsigned long pfn;
220
David Rientjes35979ef2014-06-04 16:08:27 -0700221 zone->compact_cached_migrate_pfn[0] = start_pfn;
222 zone->compact_cached_migrate_pfn[1] = start_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700223 zone->compact_cached_free_pfn = end_pfn;
Mel Gorman62997022012-10-08 16:32:47 -0700224 zone->compact_blockskip_flush = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700225
226 /* Walk the zone and mark every pageblock as suitable for isolation */
227 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
228 struct page *page;
229
230 cond_resched();
231
232 if (!pfn_valid(pfn))
233 continue;
234
235 page = pfn_to_page(pfn);
236 if (zone != page_zone(page))
237 continue;
238
239 clear_pageblock_skip(page);
240 }
241}
242
Mel Gorman62997022012-10-08 16:32:47 -0700243void reset_isolation_suitable(pg_data_t *pgdat)
244{
245 int zoneid;
246
247 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
248 struct zone *zone = &pgdat->node_zones[zoneid];
249 if (!populated_zone(zone))
250 continue;
251
252 /* Only flush if a full compaction finished recently */
253 if (zone->compact_blockskip_flush)
254 __reset_isolation_suitable(zone);
255 }
256}
257
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700258/*
259 * If no pages were isolated then mark this pageblock to be skipped in the
Mel Gorman62997022012-10-08 16:32:47 -0700260 * future. The information is later cleared by __reset_isolation_suitable().
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700261 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700262static void update_pageblock_skip(struct compact_control *cc,
263 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700264 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700265{
Mel Gormanc89511a2012-10-08 16:32:45 -0700266 struct zone *zone = cc->zone;
David Rientjes35979ef2014-06-04 16:08:27 -0700267 unsigned long pfn;
Joonsoo Kim6815bf32013-12-18 17:08:52 -0800268
269 if (cc->ignore_skip_hint)
270 return;
271
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700272 if (!page)
273 return;
274
David Rientjes35979ef2014-06-04 16:08:27 -0700275 if (nr_isolated)
276 return;
277
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700278 set_pageblock_skip(page);
Mel Gormanc89511a2012-10-08 16:32:45 -0700279
David Rientjes35979ef2014-06-04 16:08:27 -0700280 pfn = page_to_pfn(page);
281
282 /* Update where async and sync compaction should restart */
283 if (migrate_scanner) {
David Rientjes35979ef2014-06-04 16:08:27 -0700284 if (pfn > zone->compact_cached_migrate_pfn[0])
285 zone->compact_cached_migrate_pfn[0] = pfn;
David Rientjese0b9dae2014-06-04 16:08:28 -0700286 if (cc->mode != MIGRATE_ASYNC &&
287 pfn > zone->compact_cached_migrate_pfn[1])
David Rientjes35979ef2014-06-04 16:08:27 -0700288 zone->compact_cached_migrate_pfn[1] = pfn;
289 } else {
David Rientjes35979ef2014-06-04 16:08:27 -0700290 if (pfn < zone->compact_cached_free_pfn)
291 zone->compact_cached_free_pfn = pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700292 }
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700293}
294#else
295static inline bool isolation_suitable(struct compact_control *cc,
296 struct page *page)
297{
298 return true;
299}
300
Mel Gormanc89511a2012-10-08 16:32:45 -0700301static void update_pageblock_skip(struct compact_control *cc,
302 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700303 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700304{
305}
306#endif /* CONFIG_COMPACTION */
307
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700308/*
309 * Compaction requires the taking of some coarse locks that are potentially
310 * very heavily contended. For async compaction, back out if the lock cannot
311 * be taken immediately. For sync compaction, spin on the lock if needed.
312 *
313 * Returns true if the lock is held
314 * Returns false if the lock is not held and compaction should abort
315 */
316static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
317 struct compact_control *cc)
Mel Gorman2a1402a2012-10-08 16:32:33 -0700318{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700319 if (cc->mode == MIGRATE_ASYNC) {
320 if (!spin_trylock_irqsave(lock, *flags)) {
321 cc->contended = COMPACT_CONTENDED_LOCK;
322 return false;
323 }
324 } else {
325 spin_lock_irqsave(lock, *flags);
326 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700327
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700328 return true;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700329}
330
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100331/*
Mel Gormanc67fe372012-08-21 16:16:17 -0700332 * Compaction requires the taking of some coarse locks that are potentially
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700333 * very heavily contended. The lock should be periodically unlocked to avoid
334 * having disabled IRQs for a long time, even when there is nobody waiting on
335 * the lock. It might also be that allowing the IRQs will result in
336 * need_resched() becoming true. If scheduling is needed, async compaction
337 * aborts. Sync compaction schedules.
338 * Either compaction type will also abort if a fatal signal is pending.
339 * In either case if the lock was locked, it is dropped and not regained.
Mel Gormanc67fe372012-08-21 16:16:17 -0700340 *
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700341 * Returns true if compaction should abort due to fatal signal pending, or
342 * async compaction due to need_resched()
343 * Returns false when compaction can continue (sync compaction might have
344 * scheduled)
Mel Gormanc67fe372012-08-21 16:16:17 -0700345 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700346static bool compact_unlock_should_abort(spinlock_t *lock,
347 unsigned long flags, bool *locked, struct compact_control *cc)
Mel Gormanc67fe372012-08-21 16:16:17 -0700348{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700349 if (*locked) {
350 spin_unlock_irqrestore(lock, flags);
351 *locked = false;
352 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700353
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700354 if (fatal_signal_pending(current)) {
355 cc->contended = COMPACT_CONTENDED_SCHED;
356 return true;
357 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700358
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700359 if (need_resched()) {
David Rientjese0b9dae2014-06-04 16:08:28 -0700360 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700361 cc->contended = COMPACT_CONTENDED_SCHED;
362 return true;
Mel Gormanc67fe372012-08-21 16:16:17 -0700363 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700364 cond_resched();
Mel Gormanc67fe372012-08-21 16:16:17 -0700365 }
366
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700367 return false;
Mel Gormanc67fe372012-08-21 16:16:17 -0700368}
369
Vlastimil Babkabe976572014-06-04 16:10:41 -0700370/*
371 * Aside from avoiding lock contention, compaction also periodically checks
372 * need_resched() and either schedules in sync compaction or aborts async
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700373 * compaction. This is similar to what compact_unlock_should_abort() does, but
Vlastimil Babkabe976572014-06-04 16:10:41 -0700374 * is used where no lock is concerned.
375 *
376 * Returns false when no scheduling was needed, or sync compaction scheduled.
377 * Returns true when async compaction should abort.
378 */
379static inline bool compact_should_abort(struct compact_control *cc)
380{
381 /* async compaction aborts if contended */
382 if (need_resched()) {
383 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700384 cc->contended = COMPACT_CONTENDED_SCHED;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700385 return true;
386 }
387
388 cond_resched();
389 }
390
391 return false;
392}
393
Mel Gormanc67fe372012-08-21 16:16:17 -0700394/*
Jerome Marchand9e4be472013-11-12 15:07:12 -0800395 * Isolate free pages onto a private freelist. If @strict is true, will abort
396 * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
397 * (even though it may still end up isolating some pages).
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100398 */
Mel Gormanf40d1e42012-10-08 16:32:36 -0700399static unsigned long isolate_freepages_block(struct compact_control *cc,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700400 unsigned long *start_pfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100401 unsigned long end_pfn,
402 struct list_head *freelist,
403 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -0700404{
Mel Gormanb7aba692011-01-13 15:45:54 -0800405 int nr_scanned = 0, total_isolated = 0;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700406 struct page *cursor, *valid_page = NULL;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700407 unsigned long flags = 0;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700408 bool locked = false;
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700409 unsigned long blockpfn = *start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700410
Mel Gorman748446b2010-05-24 14:32:27 -0700411 cursor = pfn_to_page(blockpfn);
412
Mel Gormanf40d1e42012-10-08 16:32:36 -0700413 /* Isolate free pages. */
Mel Gorman748446b2010-05-24 14:32:27 -0700414 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
415 int isolated, i;
416 struct page *page = cursor;
417
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700418 /*
419 * Periodically drop the lock (if held) regardless of its
420 * contention, to give chance to IRQs. Abort if fatal signal
421 * pending or async compaction detects need_resched()
422 */
423 if (!(blockpfn % SWAP_CLUSTER_MAX)
424 && compact_unlock_should_abort(&cc->zone->lock, flags,
425 &locked, cc))
426 break;
427
Mel Gormanb7aba692011-01-13 15:45:54 -0800428 nr_scanned++;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700429 if (!pfn_valid_within(blockpfn))
Laura Abbott2af120b2014-03-10 15:49:44 -0700430 goto isolate_fail;
431
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700432 if (!valid_page)
433 valid_page = page;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700434 if (!PageBuddy(page))
Laura Abbott2af120b2014-03-10 15:49:44 -0700435 goto isolate_fail;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700436
437 /*
Vlastimil Babka69b71892014-10-09 15:27:18 -0700438 * If we already hold the lock, we can skip some rechecking.
439 * Note that if we hold the lock now, checked_pageblock was
440 * already set in some previous iteration (or strict is true),
441 * so it is correct to skip the suitable migration target
442 * recheck as well.
Mel Gormanf40d1e42012-10-08 16:32:36 -0700443 */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700444 if (!locked) {
445 /*
446 * The zone lock must be held to isolate freepages.
447 * Unfortunately this is a very coarse lock and can be
448 * heavily contended if there are parallel allocations
449 * or parallel compactions. For async compaction do not
450 * spin on the lock and we acquire the lock as late as
451 * possible.
452 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700453 locked = compact_trylock_irqsave(&cc->zone->lock,
454 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700455 if (!locked)
456 break;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700457
Vlastimil Babka69b71892014-10-09 15:27:18 -0700458 /* Recheck this is a buddy page under lock */
459 if (!PageBuddy(page))
460 goto isolate_fail;
461 }
Mel Gorman748446b2010-05-24 14:32:27 -0700462
463 /* Found a free page, break it into order-0 pages */
464 isolated = split_free_page(page);
465 total_isolated += isolated;
466 for (i = 0; i < isolated; i++) {
467 list_add(&page->lru, freelist);
468 page++;
469 }
470
471 /* If a page was split, advance to the end of it */
472 if (isolated) {
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800473 cc->nr_freepages += isolated;
474 if (!strict &&
475 cc->nr_migratepages <= cc->nr_freepages) {
476 blockpfn += isolated;
477 break;
478 }
479
Mel Gorman748446b2010-05-24 14:32:27 -0700480 blockpfn += isolated - 1;
481 cursor += isolated - 1;
Laura Abbott2af120b2014-03-10 15:49:44 -0700482 continue;
Mel Gorman748446b2010-05-24 14:32:27 -0700483 }
Laura Abbott2af120b2014-03-10 15:49:44 -0700484
485isolate_fail:
486 if (strict)
487 break;
488 else
489 continue;
490
Mel Gorman748446b2010-05-24 14:32:27 -0700491 }
492
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800493 trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
494 nr_scanned, total_isolated);
495
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700496 /* Record how far we have got within the block */
497 *start_pfn = blockpfn;
498
Mel Gormanf40d1e42012-10-08 16:32:36 -0700499 /*
500 * If strict isolation is requested by CMA then check that all the
501 * pages requested were isolated. If there were any failures, 0 is
502 * returned and CMA will fail.
503 */
Laura Abbott2af120b2014-03-10 15:49:44 -0700504 if (strict && blockpfn < end_pfn)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700505 total_isolated = 0;
506
507 if (locked)
508 spin_unlock_irqrestore(&cc->zone->lock, flags);
509
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700510 /* Update the pageblock-skip if the whole pageblock was scanned */
511 if (blockpfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700512 update_pageblock_skip(cc, valid_page, total_isolated, false);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700513
Minchan Kim010fc292012-12-20 15:05:06 -0800514 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100515 if (total_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800516 count_compact_events(COMPACTISOLATED, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700517 return total_isolated;
518}
519
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100520/**
521 * isolate_freepages_range() - isolate free pages.
522 * @start_pfn: The first PFN to start isolating.
523 * @end_pfn: The one-past-last PFN.
524 *
525 * Non-free pages, invalid PFNs, or zone boundaries within the
526 * [start_pfn, end_pfn) range are considered errors, cause function to
527 * undo its actions and return zero.
528 *
529 * Otherwise, function returns one-past-the-last PFN of isolated page
530 * (which may be greater then end_pfn if end fell in a middle of
531 * a free page).
532 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100533unsigned long
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700534isolate_freepages_range(struct compact_control *cc,
535 unsigned long start_pfn, unsigned long end_pfn)
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100536{
Mel Gormanf40d1e42012-10-08 16:32:36 -0700537 unsigned long isolated, pfn, block_end_pfn;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100538 LIST_HEAD(freelist);
539
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700540 pfn = start_pfn;
541 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100542
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700543 for (; pfn < end_pfn; pfn += isolated,
544 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700545 /* Protect pfn from changing by isolate_freepages_block */
546 unsigned long isolate_start_pfn = pfn;
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700547
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100548 block_end_pfn = min(block_end_pfn, end_pfn);
549
Joonsoo Kim58420012014-11-13 15:19:07 -0800550 /*
551 * pfn could pass the block_end_pfn if isolated freepage
552 * is more than pageblock order. In this case, we adjust
553 * scanning range to right one.
554 */
555 if (pfn >= block_end_pfn) {
556 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
557 block_end_pfn = min(block_end_pfn, end_pfn);
558 }
559
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700560 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
561 break;
562
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700563 isolated = isolate_freepages_block(cc, &isolate_start_pfn,
564 block_end_pfn, &freelist, true);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100565
566 /*
567 * In strict mode, isolate_freepages_block() returns 0 if
568 * there are any holes in the block (ie. invalid PFNs or
569 * non-free pages).
570 */
571 if (!isolated)
572 break;
573
574 /*
575 * If we managed to isolate pages, it is always (1 << n) *
576 * pageblock_nr_pages for some non-negative n. (Max order
577 * page may span two pageblocks).
578 */
579 }
580
581 /* split_free_page does not map the pages */
582 map_pages(&freelist);
583
584 if (pfn < end_pfn) {
585 /* Loop terminated early, cleanup. */
586 release_freepages(&freelist);
587 return 0;
588 }
589
590 /* We don't use freelists for anything. */
591 return pfn;
592}
593
Mel Gorman748446b2010-05-24 14:32:27 -0700594/* Update the number of anon and file isolated pages in the zone */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700595static void acct_isolated(struct zone *zone, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700596{
597 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700598 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700599
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700600 if (list_empty(&cc->migratepages))
601 return;
602
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700603 list_for_each_entry(page, &cc->migratepages, lru)
604 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700605
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700606 mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
607 mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
Mel Gorman748446b2010-05-24 14:32:27 -0700608}
609
610/* Similar to reclaim, but different enough that they don't share logic */
611static bool too_many_isolated(struct zone *zone)
612{
Minchan Kimbc693042010-09-09 16:38:00 -0700613 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700614
615 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
616 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700617 active = zone_page_state(zone, NR_ACTIVE_FILE) +
618 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700619 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
620 zone_page_state(zone, NR_ISOLATED_ANON);
621
Minchan Kimbc693042010-09-09 16:38:00 -0700622 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700623}
624
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100625/**
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700626 * isolate_migratepages_block() - isolate all migrate-able pages within
627 * a single pageblock
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100628 * @cc: Compaction control structure.
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700629 * @low_pfn: The first PFN to isolate
630 * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock
631 * @isolate_mode: Isolation mode to be used.
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100632 *
633 * Isolate all pages that can be migrated from the range specified by
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700634 * [low_pfn, end_pfn). The range is expected to be within same pageblock.
635 * Returns zero if there is a fatal signal pending, otherwise PFN of the
636 * first page that was not scanned (which may be both less, equal to or more
637 * than end_pfn).
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100638 *
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700639 * The pages are isolated on cc->migratepages list (not required to be empty),
640 * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
641 * is neither read nor updated.
Mel Gorman748446b2010-05-24 14:32:27 -0700642 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700643static unsigned long
644isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
645 unsigned long end_pfn, isolate_mode_t isolate_mode)
Mel Gorman748446b2010-05-24 14:32:27 -0700646{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700647 struct zone *zone = cc->zone;
Mel Gormanb7aba692011-01-13 15:45:54 -0800648 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700649 struct list_head *migratelist = &cc->migratepages;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700650 struct lruvec *lruvec;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700651 unsigned long flags = 0;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700652 bool locked = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700653 struct page *page = NULL, *valid_page = NULL;
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800654 unsigned long start_pfn = low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700655
Mel Gorman748446b2010-05-24 14:32:27 -0700656 /*
657 * Ensure that there are not too many pages isolated from the LRU
658 * list by either parallel reclaimers or compaction. If there are,
659 * delay for some time until fewer pages are isolated
660 */
661 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700662 /* async migration should just abort */
David Rientjese0b9dae2014-06-04 16:08:28 -0700663 if (cc->mode == MIGRATE_ASYNC)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100664 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700665
Mel Gorman748446b2010-05-24 14:32:27 -0700666 congestion_wait(BLK_RW_ASYNC, HZ/10);
667
668 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100669 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700670 }
671
Vlastimil Babkabe976572014-06-04 16:10:41 -0700672 if (compact_should_abort(cc))
673 return 0;
David Rientjesaeef4b82014-06-04 16:08:31 -0700674
Mel Gorman748446b2010-05-24 14:32:27 -0700675 /* Time to isolate some pages for migration */
Mel Gorman748446b2010-05-24 14:32:27 -0700676 for (; low_pfn < end_pfn; low_pfn++) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700677 /*
678 * Periodically drop the lock (if held) regardless of its
679 * contention, to give chance to IRQs. Abort async compaction
680 * if contended.
681 */
682 if (!(low_pfn % SWAP_CLUSTER_MAX)
683 && compact_unlock_should_abort(&zone->lru_lock, flags,
684 &locked, cc))
685 break;
Mel Gormanc67fe372012-08-21 16:16:17 -0700686
Mel Gorman748446b2010-05-24 14:32:27 -0700687 if (!pfn_valid_within(low_pfn))
688 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800689 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700690
Mel Gorman748446b2010-05-24 14:32:27 -0700691 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800692
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700693 if (!valid_page)
694 valid_page = page;
695
Mel Gorman6c144662014-01-23 15:53:38 -0800696 /*
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700697 * Skip if free. We read page order here without zone lock
698 * which is generally unsafe, but the race window is small and
699 * the worst thing that can happen is that we skip some
700 * potential isolation targets.
Mel Gorman6c144662014-01-23 15:53:38 -0800701 */
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700702 if (PageBuddy(page)) {
703 unsigned long freepage_order = page_order_unsafe(page);
704
705 /*
706 * Without lock, we cannot be sure that what we got is
707 * a valid page order. Consider only values in the
708 * valid order range to prevent low_pfn overflow.
709 */
710 if (freepage_order > 0 && freepage_order < MAX_ORDER)
711 low_pfn += (1UL << freepage_order) - 1;
Mel Gorman748446b2010-05-24 14:32:27 -0700712 continue;
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700713 }
Mel Gorman748446b2010-05-24 14:32:27 -0700714
Mel Gorman9927af742011-01-13 15:45:59 -0800715 /*
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800716 * Check may be lockless but that's ok as we recheck later.
717 * It's possible to migrate LRU pages and balloon pages
718 * Skip any other type of page
719 */
720 if (!PageLRU(page)) {
721 if (unlikely(balloon_page_movable(page))) {
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700722 if (balloon_page_isolate(page)) {
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800723 /* Successfully isolated */
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700724 goto isolate_success;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800725 }
726 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800727 continue;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800728 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800729
730 /*
Mel Gorman2a1402a2012-10-08 16:32:33 -0700731 * PageLRU is set. lru_lock normally excludes isolation
732 * splitting and collapsing (collapsing has already happened
733 * if PageLRU is set) but the lock is not necessarily taken
734 * here and it is wasteful to take it just to check transhuge.
735 * Check TransHuge without lock and skip the whole pageblock if
736 * it's either a transhuge or hugetlbfs page, as calling
737 * compound_order() without preventing THP from splitting the
738 * page underneath us may return surprising results.
Andrea Arcangelibc835012011-01-13 15:47:08 -0800739 */
740 if (PageTransHuge(page)) {
Mel Gorman2a1402a2012-10-08 16:32:33 -0700741 if (!locked)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700742 low_pfn = ALIGN(low_pfn + 1,
743 pageblock_nr_pages) - 1;
744 else
745 low_pfn += (1 << compound_order(page)) - 1;
746
Mel Gorman2a1402a2012-10-08 16:32:33 -0700747 continue;
748 }
749
David Rientjes119d6d52014-04-03 14:48:00 -0700750 /*
751 * Migration will fail if an anonymous page is pinned in memory,
752 * so avoid taking lru_lock and isolating it unnecessarily in an
753 * admittedly racy check.
754 */
755 if (!page_mapping(page) &&
756 page_count(page) > page_mapcount(page))
757 continue;
758
Vlastimil Babka69b71892014-10-09 15:27:18 -0700759 /* If we already hold the lock, we can skip some rechecking */
760 if (!locked) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700761 locked = compact_trylock_irqsave(&zone->lru_lock,
762 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700763 if (!locked)
764 break;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700765
Vlastimil Babka69b71892014-10-09 15:27:18 -0700766 /* Recheck PageLRU and PageTransHuge under lock */
767 if (!PageLRU(page))
768 continue;
769 if (PageTransHuge(page)) {
770 low_pfn += (1 << compound_order(page)) - 1;
771 continue;
772 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800773 }
774
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700775 lruvec = mem_cgroup_page_lruvec(page, zone);
776
Mel Gorman748446b2010-05-24 14:32:27 -0700777 /* Try isolate the page */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700778 if (__isolate_lru_page(page, isolate_mode) != 0)
Mel Gorman748446b2010-05-24 14:32:27 -0700779 continue;
780
Sasha Levin309381fea2014-01-23 15:52:54 -0800781 VM_BUG_ON_PAGE(PageTransCompound(page), page);
Andrea Arcangelibc835012011-01-13 15:47:08 -0800782
Mel Gorman748446b2010-05-24 14:32:27 -0700783 /* Successfully isolated */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700784 del_page_from_lru_list(page, lruvec, page_lru(page));
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700785
786isolate_success:
Mel Gorman748446b2010-05-24 14:32:27 -0700787 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700788 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800789 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700790
791 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800792 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
793 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700794 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800795 }
Mel Gorman748446b2010-05-24 14:32:27 -0700796 }
797
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700798 /*
799 * The PageBuddy() check could have potentially brought us outside
800 * the range to be scanned.
801 */
802 if (unlikely(low_pfn > end_pfn))
803 low_pfn = end_pfn;
804
Mel Gormanc67fe372012-08-21 16:16:17 -0700805 if (locked)
806 spin_unlock_irqrestore(&zone->lru_lock, flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700807
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800808 /*
809 * Update the pageblock-skip information and cached scanner pfn,
810 * if the whole pageblock was scanned without isolating any page.
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800811 */
David Rientjes35979ef2014-06-04 16:08:27 -0700812 if (low_pfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700813 update_pageblock_skip(cc, valid_page, nr_isolated, true);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700814
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800815 trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
816 nr_scanned, nr_isolated);
Mel Gormanb7aba692011-01-13 15:45:54 -0800817
Minchan Kim010fc292012-12-20 15:05:06 -0800818 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100819 if (nr_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800820 count_compact_events(COMPACTISOLATED, nr_isolated);
Mel Gorman397487d2012-10-19 12:00:10 +0100821
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100822 return low_pfn;
823}
824
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700825/**
826 * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
827 * @cc: Compaction control structure.
828 * @start_pfn: The first PFN to start isolating.
829 * @end_pfn: The one-past-last PFN.
830 *
831 * Returns zero if isolation fails fatally due to e.g. pending signal.
832 * Otherwise, function returns one-past-the-last PFN of isolated page
833 * (which may be greater than end_pfn if end fell in a middle of a THP page).
834 */
835unsigned long
836isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
837 unsigned long end_pfn)
838{
839 unsigned long pfn, block_end_pfn;
840
841 /* Scan block by block. First and last block may be incomplete */
842 pfn = start_pfn;
843 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
844
845 for (; pfn < end_pfn; pfn = block_end_pfn,
846 block_end_pfn += pageblock_nr_pages) {
847
848 block_end_pfn = min(block_end_pfn, end_pfn);
849
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700850 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700851 continue;
852
853 pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
854 ISOLATE_UNEVICTABLE);
855
856 /*
857 * In case of fatal failure, release everything that might
858 * have been isolated in the previous iteration, and signal
859 * the failure back to caller.
860 */
861 if (!pfn) {
862 putback_movable_pages(&cc->migratepages);
863 cc->nr_migratepages = 0;
864 break;
865 }
Joonsoo Kim6ea41c02014-10-29 14:50:20 -0700866
867 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
868 break;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700869 }
870 acct_isolated(cc->zone, cc);
871
872 return pfn;
873}
874
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100875#endif /* CONFIG_COMPACTION || CONFIG_CMA */
876#ifdef CONFIG_COMPACTION
Andrew Morton018e9a42015-04-15 16:15:20 -0700877
878/* Returns true if the page is within a block suitable for migration to */
879static bool suitable_migration_target(struct page *page)
880{
881 /* If the page is a large free page, then disallow migration */
882 if (PageBuddy(page)) {
883 /*
884 * We are checking page_order without zone->lock taken. But
885 * the only small danger is that we skip a potentially suitable
886 * pageblock, so it's not worth to check order for valid range.
887 */
888 if (page_order_unsafe(page) >= pageblock_order)
889 return false;
890 }
891
892 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
893 if (migrate_async_suitable(get_pageblock_migratetype(page)))
894 return true;
895
896 /* Otherwise skip the block */
897 return false;
898}
899
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100900/*
901 * Based on information in the current compact_control, find blocks
902 * suitable for isolating free pages from and then isolate them.
903 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700904static void isolate_freepages(struct compact_control *cc)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100905{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700906 struct zone *zone = cc->zone;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100907 struct page *page;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700908 unsigned long block_start_pfn; /* start of current pageblock */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700909 unsigned long isolate_start_pfn; /* exact pfn we start at */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700910 unsigned long block_end_pfn; /* end of current pageblock */
911 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100912 struct list_head *freelist = &cc->freepages;
913
914 /*
915 * Initialise the free scanner. The starting point is where we last
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700916 * successfully isolated from, zone-cached value, or the end of the
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700917 * zone when isolating for the first time. For looping we also need
918 * this pfn aligned down to the pageblock boundary, because we do
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700919 * block_start_pfn -= pageblock_nr_pages in the for loop.
920 * For ending point, take care when isolating in last pageblock of a
921 * a zone which ends in the middle of a pageblock.
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700922 * The low boundary is the end of the pageblock the migration scanner
923 * is using.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100924 */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700925 isolate_start_pfn = cc->free_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700926 block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
927 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
928 zone_end_pfn(zone));
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800929 low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100930
931 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100932 * Isolate free pages until enough are available to migrate the
933 * pages on cc->migratepages. We stop searching if the migrate
934 * and free page scanners meet or enough free pages are isolated.
935 */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800936 for (; block_start_pfn >= low_pfn &&
937 cc->nr_migratepages > cc->nr_freepages;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700938 block_end_pfn = block_start_pfn,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700939 block_start_pfn -= pageblock_nr_pages,
940 isolate_start_pfn = block_start_pfn) {
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100941
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700942 /*
943 * This can iterate a massively long zone without finding any
944 * suitable migration targets, so periodically check if we need
Vlastimil Babkabe976572014-06-04 16:10:41 -0700945 * to schedule, or even abort async compaction.
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700946 */
Vlastimil Babkabe976572014-06-04 16:10:41 -0700947 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
948 && compact_should_abort(cc))
949 break;
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700950
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700951 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
952 zone);
953 if (!page)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100954 continue;
955
956 /* Check the block is suitable for migration */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700957 if (!suitable_migration_target(page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100958 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -0700959
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700960 /* If isolation recently failed, do not retry */
961 if (!isolation_suitable(cc, page))
962 continue;
963
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700964 /* Found a block suitable for isolating free pages from. */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800965 isolate_freepages_block(cc, &isolate_start_pfn,
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700966 block_end_pfn, freelist, false);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100967
968 /*
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700969 * Remember where the free scanner should restart next time,
970 * which is where isolate_freepages_block() left off.
971 * But if it scanned the whole pageblock, isolate_start_pfn
972 * now points at block_end_pfn, which is the start of the next
973 * pageblock.
974 * In that case we will however want to restart at the start
975 * of the previous pageblock.
976 */
977 cc->free_pfn = (isolate_start_pfn < block_end_pfn) ?
978 isolate_start_pfn :
979 block_start_pfn - pageblock_nr_pages;
980
981 /*
Vlastimil Babkabe976572014-06-04 16:10:41 -0700982 * isolate_freepages_block() might have aborted due to async
983 * compaction being contended
984 */
985 if (cc->contended)
986 break;
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100987 }
988
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100989 /* split_free_page does not map the pages */
990 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100991
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800992 /*
993 * If we crossed the migrate scanner, we want to keep it that way
994 * so that compact_finished() may detect this
995 */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700996 if (block_start_pfn < low_pfn)
Vlastimil Babkae9ade562014-06-04 16:08:34 -0700997 cc->free_pfn = cc->migrate_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700998}
999
1000/*
1001 * This is a migrate-callback that "allocates" freepages by taking pages
1002 * from the isolated freelists in the block we are migrating to.
1003 */
1004static struct page *compaction_alloc(struct page *migratepage,
1005 unsigned long data,
1006 int **result)
1007{
1008 struct compact_control *cc = (struct compact_control *)data;
1009 struct page *freepage;
1010
Vlastimil Babkabe976572014-06-04 16:10:41 -07001011 /*
1012 * Isolate free pages if necessary, and if we are not aborting due to
1013 * contention.
1014 */
Mel Gorman748446b2010-05-24 14:32:27 -07001015 if (list_empty(&cc->freepages)) {
Vlastimil Babkabe976572014-06-04 16:10:41 -07001016 if (!cc->contended)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001017 isolate_freepages(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001018
1019 if (list_empty(&cc->freepages))
1020 return NULL;
1021 }
1022
1023 freepage = list_entry(cc->freepages.next, struct page, lru);
1024 list_del(&freepage->lru);
1025 cc->nr_freepages--;
1026
1027 return freepage;
1028}
1029
1030/*
David Rientjesd53aea32014-06-04 16:08:26 -07001031 * This is a migrate-callback that "frees" freepages back to the isolated
1032 * freelist. All pages on the freelist are from the same zone, so there is no
1033 * special handling needed for NUMA.
1034 */
1035static void compaction_free(struct page *page, unsigned long data)
1036{
1037 struct compact_control *cc = (struct compact_control *)data;
1038
1039 list_add(&page->lru, &cc->freepages);
1040 cc->nr_freepages++;
1041}
1042
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001043/* possible outcome of isolate_migratepages */
1044typedef enum {
1045 ISOLATE_ABORT, /* Abort compaction now */
1046 ISOLATE_NONE, /* No pages isolated, continue scanning */
1047 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1048} isolate_migrate_t;
1049
1050/*
Eric B Munson5bbe3542015-04-15 16:13:20 -07001051 * Allow userspace to control policy on scanning the unevictable LRU for
1052 * compactable pages.
1053 */
1054int sysctl_compact_unevictable_allowed __read_mostly = 1;
1055
1056/*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001057 * Isolate all pages that can be migrated from the first suitable block,
1058 * starting at the block pointed to by the migrate scanner pfn within
1059 * compact_control.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001060 */
1061static isolate_migrate_t isolate_migratepages(struct zone *zone,
1062 struct compact_control *cc)
1063{
1064 unsigned long low_pfn, end_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001065 struct page *page;
1066 const isolate_mode_t isolate_mode =
Eric B Munson5bbe3542015-04-15 16:13:20 -07001067 (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001068 (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001069
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001070 /*
1071 * Start at where we last stopped, or beginning of the zone as
1072 * initialized by compact_zone()
1073 */
1074 low_pfn = cc->migrate_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001075
1076 /* Only scan within a pageblock boundary */
Mel Gormana9aacbc2013-02-22 16:32:25 -08001077 end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001078
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001079 /*
1080 * Iterate over whole pageblocks until we find the first suitable.
1081 * Do not cross the free scanner.
1082 */
1083 for (; end_pfn <= cc->free_pfn;
1084 low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {
1085
1086 /*
1087 * This can potentially iterate a massively long zone with
1088 * many pageblocks unsuitable, so periodically check if we
1089 * need to schedule, or even abort async compaction.
1090 */
1091 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1092 && compact_should_abort(cc))
1093 break;
1094
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001095 page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);
1096 if (!page)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001097 continue;
1098
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001099 /* If isolation recently failed, do not retry */
1100 if (!isolation_suitable(cc, page))
1101 continue;
1102
1103 /*
1104 * For async compaction, also only scan in MOVABLE blocks.
1105 * Async compaction is optimistic to see if the minimum amount
1106 * of work satisfies the allocation.
1107 */
1108 if (cc->mode == MIGRATE_ASYNC &&
1109 !migrate_async_suitable(get_pageblock_migratetype(page)))
1110 continue;
1111
1112 /* Perform the isolation */
1113 low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
1114 isolate_mode);
1115
Hugh Dickinsff599092015-02-12 15:00:28 -08001116 if (!low_pfn || cc->contended) {
1117 acct_isolated(zone, cc);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001118 return ISOLATE_ABORT;
Hugh Dickinsff599092015-02-12 15:00:28 -08001119 }
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001120
1121 /*
1122 * Either we isolated something and proceed with migration. Or
1123 * we failed and compact_zone should decide if we should
1124 * continue or not.
1125 */
1126 break;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001127 }
1128
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001129 acct_isolated(zone, cc);
Vlastimil Babka1d5bfe12014-11-13 15:19:30 -08001130 /*
1131 * Record where migration scanner will be restarted. If we end up in
1132 * the same pageblock as the free scanner, make the scanners fully
1133 * meet so that compact_finished() terminates compaction.
1134 */
1135 cc->migrate_pfn = (end_pfn <= cc->free_pfn) ? low_pfn : cc->free_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001136
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001137 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001138}
1139
Joonsoo Kim837d0262015-02-11 15:27:06 -08001140static int __compact_finished(struct zone *zone, struct compact_control *cc,
David Rientjes6d7ce552014-10-09 15:27:27 -07001141 const int migratetype)
Mel Gorman748446b2010-05-24 14:32:27 -07001142{
Mel Gorman8fb74b92013-01-11 14:32:16 -08001143 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001144 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -07001145
Vlastimil Babkabe976572014-06-04 16:10:41 -07001146 if (cc->contended || fatal_signal_pending(current))
Mel Gorman748446b2010-05-24 14:32:27 -07001147 return COMPACT_PARTIAL;
1148
Mel Gorman753341a2012-10-08 16:32:40 -07001149 /* Compaction run completes if the migrate and free scanner meet */
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001150 if (cc->free_pfn <= cc->migrate_pfn) {
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001151 /* Let the next compaction start anew. */
David Rientjes35979ef2014-06-04 16:08:27 -07001152 zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
1153 zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001154 zone->compact_cached_free_pfn = zone_end_pfn(zone);
1155
Mel Gorman62997022012-10-08 16:32:47 -07001156 /*
1157 * Mark that the PG_migrate_skip information should be cleared
1158 * by kswapd when it goes to sleep. kswapd does not set the
1159 * flag itself as the decision to be clear should be directly
1160 * based on an allocation request.
1161 */
1162 if (!current_is_kswapd())
1163 zone->compact_blockskip_flush = true;
1164
Mel Gorman748446b2010-05-24 14:32:27 -07001165 return COMPACT_COMPLETE;
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001166 }
Mel Gorman748446b2010-05-24 14:32:27 -07001167
Johannes Weiner82478fb2011-01-20 14:44:21 -08001168 /*
1169 * order == -1 is expected when compacting via
1170 * /proc/sys/vm/compact_memory
1171 */
Mel Gorman56de7262010-05-24 14:32:30 -07001172 if (cc->order == -1)
1173 return COMPACT_CONTINUE;
1174
Michal Hocko3957c772011-06-15 15:08:25 -07001175 /* Compaction run is not finished if the watermark is not met */
1176 watermark = low_wmark_pages(zone);
Michal Hocko3957c772011-06-15 15:08:25 -07001177
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001178 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1179 cc->alloc_flags))
Michal Hocko3957c772011-06-15 15:08:25 -07001180 return COMPACT_CONTINUE;
1181
Mel Gorman56de7262010-05-24 14:32:30 -07001182 /* Direct compactor: Is a suitable page free? */
Mel Gorman8fb74b92013-01-11 14:32:16 -08001183 for (order = cc->order; order < MAX_ORDER; order++) {
1184 struct free_area *area = &zone->free_area[order];
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001185 bool can_steal;
Mel Gorman56de7262010-05-24 14:32:30 -07001186
Mel Gorman8fb74b92013-01-11 14:32:16 -08001187 /* Job done if page is free of the right migratetype */
David Rientjes6d7ce552014-10-09 15:27:27 -07001188 if (!list_empty(&area->free_list[migratetype]))
Mel Gorman8fb74b92013-01-11 14:32:16 -08001189 return COMPACT_PARTIAL;
1190
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001191#ifdef CONFIG_CMA
1192 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1193 if (migratetype == MIGRATE_MOVABLE &&
1194 !list_empty(&area->free_list[MIGRATE_CMA]))
1195 return COMPACT_PARTIAL;
1196#endif
1197 /*
1198 * Job done if allocation would steal freepages from
1199 * other migratetype buddy lists.
1200 */
1201 if (find_suitable_fallback(area, order, migratetype,
1202 true, &can_steal) != -1)
Mel Gorman8fb74b92013-01-11 14:32:16 -08001203 return COMPACT_PARTIAL;
Mel Gorman56de7262010-05-24 14:32:30 -07001204 }
1205
Joonsoo Kim837d0262015-02-11 15:27:06 -08001206 return COMPACT_NO_SUITABLE_PAGE;
1207}
1208
1209static int compact_finished(struct zone *zone, struct compact_control *cc,
1210 const int migratetype)
1211{
1212 int ret;
1213
1214 ret = __compact_finished(zone, cc, migratetype);
1215 trace_mm_compaction_finished(zone, cc->order, ret);
1216 if (ret == COMPACT_NO_SUITABLE_PAGE)
1217 ret = COMPACT_CONTINUE;
1218
1219 return ret;
Mel Gorman748446b2010-05-24 14:32:27 -07001220}
1221
Mel Gorman3e7d3442011-01-13 15:45:56 -08001222/*
1223 * compaction_suitable: Is this suitable to run compaction on this zone now?
1224 * Returns
1225 * COMPACT_SKIPPED - If there are too few free pages for compaction
1226 * COMPACT_PARTIAL - If the allocation would succeed without compaction
1227 * COMPACT_CONTINUE - If compaction should run now
1228 */
Joonsoo Kim837d0262015-02-11 15:27:06 -08001229static unsigned long __compaction_suitable(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001230 int alloc_flags, int classzone_idx)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001231{
1232 int fragindex;
1233 unsigned long watermark;
1234
1235 /*
Michal Hocko3957c772011-06-15 15:08:25 -07001236 * order == -1 is expected when compacting via
1237 * /proc/sys/vm/compact_memory
1238 */
1239 if (order == -1)
1240 return COMPACT_CONTINUE;
1241
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001242 watermark = low_wmark_pages(zone);
1243 /*
1244 * If watermarks for high-order allocation are already met, there
1245 * should be no need for compaction at all.
1246 */
1247 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1248 alloc_flags))
1249 return COMPACT_PARTIAL;
1250
Michal Hocko3957c772011-06-15 15:08:25 -07001251 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001252 * Watermarks for order-0 must be met for compaction. Note the 2UL.
1253 * This is because during migration, copies of pages need to be
1254 * allocated and for a short time, the footprint is higher
1255 */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001256 watermark += (2UL << order);
1257 if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001258 return COMPACT_SKIPPED;
1259
1260 /*
1261 * fragmentation index determines if allocation failures are due to
1262 * low memory or external fragmentation
1263 *
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001264 * index of -1000 would imply allocations might succeed depending on
1265 * watermarks, but we already failed the high-order watermark check
Mel Gorman3e7d3442011-01-13 15:45:56 -08001266 * index towards 0 implies failure is due to lack of memory
1267 * index towards 1000 implies failure is due to fragmentation
1268 *
1269 * Only compact if a failure would be due to fragmentation.
1270 */
1271 fragindex = fragmentation_index(zone, order);
1272 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
Joonsoo Kim837d0262015-02-11 15:27:06 -08001273 return COMPACT_NOT_SUITABLE_ZONE;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001274
Mel Gorman3e7d3442011-01-13 15:45:56 -08001275 return COMPACT_CONTINUE;
1276}
1277
Joonsoo Kim837d0262015-02-11 15:27:06 -08001278unsigned long compaction_suitable(struct zone *zone, int order,
1279 int alloc_flags, int classzone_idx)
1280{
1281 unsigned long ret;
1282
1283 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
1284 trace_mm_compaction_suitable(zone, order, ret);
1285 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1286 ret = COMPACT_SKIPPED;
1287
1288 return ret;
1289}
1290
Mel Gorman748446b2010-05-24 14:32:27 -07001291static int compact_zone(struct zone *zone, struct compact_control *cc)
1292{
1293 int ret;
Mel Gormanc89511a2012-10-08 16:32:45 -07001294 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -08001295 unsigned long end_pfn = zone_end_pfn(zone);
David Rientjes6d7ce552014-10-09 15:27:27 -07001296 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
David Rientjese0b9dae2014-06-04 16:08:28 -07001297 const bool sync = cc->mode != MIGRATE_ASYNC;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001298 unsigned long last_migrated_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -07001299
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001300 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1301 cc->classzone_idx);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001302 switch (ret) {
1303 case COMPACT_PARTIAL:
1304 case COMPACT_SKIPPED:
1305 /* Compaction is likely to fail */
1306 return ret;
1307 case COMPACT_CONTINUE:
1308 /* Fall through to compaction */
1309 ;
1310 }
1311
Mel Gormanc89511a2012-10-08 16:32:45 -07001312 /*
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001313 * Clear pageblock skip if there were failures recently and compaction
1314 * is about to be retried after being deferred. kswapd does not do
1315 * this reset as it'll reset the cached information when going to sleep.
1316 */
1317 if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
1318 __reset_isolation_suitable(zone);
1319
1320 /*
Mel Gormanc89511a2012-10-08 16:32:45 -07001321 * Setup to move all movable pages to the end of the zone. Used cached
1322 * information on where the scanners should start but check that it
1323 * is initialised by ensuring the values are within zone boundaries.
1324 */
David Rientjese0b9dae2014-06-04 16:08:28 -07001325 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
Mel Gormanc89511a2012-10-08 16:32:45 -07001326 cc->free_pfn = zone->compact_cached_free_pfn;
1327 if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
1328 cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
1329 zone->compact_cached_free_pfn = cc->free_pfn;
1330 }
1331 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) {
1332 cc->migrate_pfn = start_pfn;
David Rientjes35979ef2014-06-04 16:08:27 -07001333 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1334 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -07001335 }
Mel Gorman748446b2010-05-24 14:32:27 -07001336
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001337 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1338 cc->free_pfn, end_pfn, sync);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001339
Mel Gorman748446b2010-05-24 14:32:27 -07001340 migrate_prep_local();
1341
David Rientjes6d7ce552014-10-09 15:27:27 -07001342 while ((ret = compact_finished(zone, cc, migratetype)) ==
1343 COMPACT_CONTINUE) {
Minchan Kim9d502c12011-03-22 16:30:39 -07001344 int err;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001345 unsigned long isolate_start_pfn = cc->migrate_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -07001346
Mel Gormanf9e35b32011-06-15 15:08:52 -07001347 switch (isolate_migratepages(zone, cc)) {
1348 case ISOLATE_ABORT:
1349 ret = COMPACT_PARTIAL;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001350 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001351 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001352 goto out;
1353 case ISOLATE_NONE:
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001354 /*
1355 * We haven't isolated and migrated anything, but
1356 * there might still be unflushed migrations from
1357 * previous cc->order aligned block.
1358 */
1359 goto check_drain;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001360 case ISOLATE_SUCCESS:
1361 ;
1362 }
Mel Gorman748446b2010-05-24 14:32:27 -07001363
David Rientjesd53aea32014-06-04 16:08:26 -07001364 err = migrate_pages(&cc->migratepages, compaction_alloc,
David Rientjese0b9dae2014-06-04 16:08:28 -07001365 compaction_free, (unsigned long)cc, cc->mode,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001366 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001367
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001368 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1369 &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001370
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001371 /* All pages were either migrated or will be released */
1372 cc->nr_migratepages = 0;
Minchan Kim9d502c12011-03-22 16:30:39 -07001373 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001374 putback_movable_pages(&cc->migratepages);
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001375 /*
1376 * migrate_pages() may return -ENOMEM when scanners meet
1377 * and we want compact_finished() to detect it
1378 */
1379 if (err == -ENOMEM && cc->free_pfn > cc->migrate_pfn) {
David Rientjes4bf2bba2012-07-11 14:02:13 -07001380 ret = COMPACT_PARTIAL;
1381 goto out;
1382 }
Mel Gorman748446b2010-05-24 14:32:27 -07001383 }
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001384
1385 /*
1386 * Record where we could have freed pages by migration and not
1387 * yet flushed them to buddy allocator. We use the pfn that
1388 * isolate_migratepages() started from in this loop iteration
1389 * - this is the lowest page that could have been isolated and
1390 * then freed by migration.
1391 */
1392 if (!last_migrated_pfn)
1393 last_migrated_pfn = isolate_start_pfn;
1394
1395check_drain:
1396 /*
1397 * Has the migration scanner moved away from the previous
1398 * cc->order aligned block where we migrated from? If yes,
1399 * flush the pages that were freed, so that they can merge and
1400 * compact_finished() can detect immediately if allocation
1401 * would succeed.
1402 */
1403 if (cc->order > 0 && last_migrated_pfn) {
1404 int cpu;
1405 unsigned long current_block_start =
1406 cc->migrate_pfn & ~((1UL << cc->order) - 1);
1407
1408 if (last_migrated_pfn < current_block_start) {
1409 cpu = get_cpu();
1410 lru_add_drain_cpu(cpu);
1411 drain_local_pages(zone);
1412 put_cpu();
1413 /* No more flushing until we migrate again */
1414 last_migrated_pfn = 0;
1415 }
1416 }
1417
Mel Gorman748446b2010-05-24 14:32:27 -07001418 }
1419
Mel Gormanf9e35b32011-06-15 15:08:52 -07001420out:
Vlastimil Babka6bace092014-12-10 15:43:31 -08001421 /*
1422 * Release free pages and update where the free scanner should restart,
1423 * so we don't leave any returned pages behind in the next attempt.
1424 */
1425 if (cc->nr_freepages > 0) {
1426 unsigned long free_pfn = release_freepages(&cc->freepages);
1427
1428 cc->nr_freepages = 0;
1429 VM_BUG_ON(free_pfn == 0);
1430 /* The cached pfn is always the first in a pageblock */
1431 free_pfn &= ~(pageblock_nr_pages-1);
1432 /*
1433 * Only go back, not forward. The cached pfn might have been
1434 * already reset to zone end in compact_finished()
1435 */
1436 if (free_pfn > zone->compact_cached_free_pfn)
1437 zone->compact_cached_free_pfn = free_pfn;
1438 }
Mel Gorman748446b2010-05-24 14:32:27 -07001439
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001440 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1441 cc->free_pfn, end_pfn, sync, ret);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001442
Mel Gorman748446b2010-05-24 14:32:27 -07001443 return ret;
1444}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001445
David Rientjese0b9dae2014-06-04 16:08:28 -07001446static unsigned long compact_zone_order(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001447 gfp_t gfp_mask, enum migrate_mode mode, int *contended,
1448 int alloc_flags, int classzone_idx)
Mel Gorman56de7262010-05-24 14:32:30 -07001449{
Shaohua Lie64c5232012-10-08 16:32:27 -07001450 unsigned long ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001451 struct compact_control cc = {
1452 .nr_freepages = 0,
1453 .nr_migratepages = 0,
1454 .order = order,
David Rientjes6d7ce552014-10-09 15:27:27 -07001455 .gfp_mask = gfp_mask,
Mel Gorman56de7262010-05-24 14:32:30 -07001456 .zone = zone,
David Rientjese0b9dae2014-06-04 16:08:28 -07001457 .mode = mode,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001458 .alloc_flags = alloc_flags,
1459 .classzone_idx = classzone_idx,
Mel Gorman56de7262010-05-24 14:32:30 -07001460 };
1461 INIT_LIST_HEAD(&cc.freepages);
1462 INIT_LIST_HEAD(&cc.migratepages);
1463
Shaohua Lie64c5232012-10-08 16:32:27 -07001464 ret = compact_zone(zone, &cc);
1465
1466 VM_BUG_ON(!list_empty(&cc.freepages));
1467 VM_BUG_ON(!list_empty(&cc.migratepages));
1468
1469 *contended = cc.contended;
1470 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001471}
1472
Mel Gorman5e771902010-05-24 14:32:31 -07001473int sysctl_extfrag_threshold = 500;
1474
Mel Gorman56de7262010-05-24 14:32:30 -07001475/**
1476 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
Mel Gorman56de7262010-05-24 14:32:30 -07001477 * @gfp_mask: The GFP mask of the current allocation
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001478 * @order: The order of the current allocation
1479 * @alloc_flags: The allocation flags of the current allocation
1480 * @ac: The context of current allocation
David Rientjese0b9dae2014-06-04 16:08:28 -07001481 * @mode: The migration mode for async, sync light, or sync migration
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001482 * @contended: Return value that determines if compaction was aborted due to
1483 * need_resched() or lock contention
Mel Gorman56de7262010-05-24 14:32:30 -07001484 *
1485 * This is the main entry point for direct page compaction.
1486 */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001487unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
1488 int alloc_flags, const struct alloc_context *ac,
1489 enum migrate_mode mode, int *contended)
Mel Gorman56de7262010-05-24 14:32:30 -07001490{
Mel Gorman56de7262010-05-24 14:32:30 -07001491 int may_enter_fs = gfp_mask & __GFP_FS;
1492 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001493 struct zoneref *z;
1494 struct zone *zone;
Vlastimil Babka53853e22014-10-09 15:27:02 -07001495 int rc = COMPACT_DEFERRED;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001496 int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
1497
1498 *contended = COMPACT_CONTENDED_NONE;
Mel Gorman56de7262010-05-24 14:32:30 -07001499
Mel Gorman4ffb6332012-10-08 16:29:09 -07001500 /* Check if the GFP flags allow compaction */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -08001501 if (!order || !may_enter_fs || !may_perform_io)
Vlastimil Babka53853e22014-10-09 15:27:02 -07001502 return COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001503
Joonsoo Kim837d0262015-02-11 15:27:06 -08001504 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
1505
Mel Gorman56de7262010-05-24 14:32:30 -07001506 /* Compact each zone in the list */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001507 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1508 ac->nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -07001509 int status;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001510 int zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001511
Vlastimil Babka53853e22014-10-09 15:27:02 -07001512 if (compaction_deferred(zone, order))
1513 continue;
1514
David Rientjese0b9dae2014-06-04 16:08:28 -07001515 status = compact_zone_order(zone, order, gfp_mask, mode,
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001516 &zone_contended, alloc_flags,
1517 ac->classzone_idx);
Mel Gorman56de7262010-05-24 14:32:30 -07001518 rc = max(status, rc);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001519 /*
1520 * It takes at least one zone that wasn't lock contended
1521 * to clear all_zones_contended.
1522 */
1523 all_zones_contended &= zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001524
Mel Gorman3e7d3442011-01-13 15:45:56 -08001525 /* If a normal allocation would succeed, stop compacting */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001526 if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001527 ac->classzone_idx, alloc_flags)) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001528 /*
1529 * We think the allocation will succeed in this zone,
1530 * but it is not certain, hence the false. The caller
1531 * will repeat this with true if allocation indeed
1532 * succeeds in this zone.
1533 */
1534 compaction_defer_reset(zone, order, false);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001535 /*
1536 * It is possible that async compaction aborted due to
1537 * need_resched() and the watermarks were ok thanks to
1538 * somebody else freeing memory. The allocation can
1539 * however still fail so we better signal the
1540 * need_resched() contention anyway (this will not
1541 * prevent the allocation attempt).
1542 */
1543 if (zone_contended == COMPACT_CONTENDED_SCHED)
1544 *contended = COMPACT_CONTENDED_SCHED;
1545
1546 goto break_loop;
1547 }
1548
Vlastimil Babkaf8669792014-12-10 15:43:28 -08001549 if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001550 /*
1551 * We think that allocation won't succeed in this zone
1552 * so we defer compaction there. If it ends up
1553 * succeeding after all, it will be reset.
1554 */
1555 defer_compaction(zone, order);
1556 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001557
1558 /*
1559 * We might have stopped compacting due to need_resched() in
1560 * async compaction, or due to a fatal signal detected. In that
1561 * case do not try further zones and signal need_resched()
1562 * contention.
1563 */
1564 if ((zone_contended == COMPACT_CONTENDED_SCHED)
1565 || fatal_signal_pending(current)) {
1566 *contended = COMPACT_CONTENDED_SCHED;
1567 goto break_loop;
1568 }
1569
1570 continue;
1571break_loop:
1572 /*
1573 * We might not have tried all the zones, so be conservative
1574 * and assume they are not all lock contended.
1575 */
1576 all_zones_contended = 0;
1577 break;
Mel Gorman56de7262010-05-24 14:32:30 -07001578 }
1579
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001580 /*
1581 * If at least one zone wasn't deferred or skipped, we report if all
1582 * zones that were tried were lock contended.
1583 */
1584 if (rc > COMPACT_SKIPPED && all_zones_contended)
1585 *contended = COMPACT_CONTENDED_LOCK;
1586
Mel Gorman56de7262010-05-24 14:32:30 -07001587 return rc;
1588}
1589
1590
Mel Gorman76ab0f52010-05-24 14:32:28 -07001591/* Compact all zones within a node */
Andrew Morton7103f162013-02-22 16:32:33 -08001592static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001593{
1594 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -07001595 struct zone *zone;
1596
Mel Gorman76ab0f52010-05-24 14:32:28 -07001597 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -07001598
1599 zone = &pgdat->node_zones[zoneid];
1600 if (!populated_zone(zone))
1601 continue;
1602
Rik van Riel7be62de2012-03-21 16:33:52 -07001603 cc->nr_freepages = 0;
1604 cc->nr_migratepages = 0;
1605 cc->zone = zone;
1606 INIT_LIST_HEAD(&cc->freepages);
1607 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001608
Gioh Kim195b0c62015-04-15 16:13:33 -07001609 /*
1610 * When called via /proc/sys/vm/compact_memory
1611 * this makes sure we compact the whole zone regardless of
1612 * cached scanner positions.
1613 */
1614 if (cc->order == -1)
1615 __reset_isolation_suitable(zone);
1616
Dan Carpenteraad6ec32012-03-21 16:33:54 -07001617 if (cc->order == -1 || !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -07001618 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001619
Rik van Rielaff62242012-03-21 16:33:52 -07001620 if (cc->order > 0) {
Vlastimil Babkade6c60a2014-01-21 15:51:07 -08001621 if (zone_watermark_ok(zone, cc->order,
1622 low_wmark_pages(zone), 0, 0))
1623 compaction_defer_reset(zone, cc->order, false);
Rik van Rielaff62242012-03-21 16:33:52 -07001624 }
1625
Rik van Riel7be62de2012-03-21 16:33:52 -07001626 VM_BUG_ON(!list_empty(&cc->freepages));
1627 VM_BUG_ON(!list_empty(&cc->migratepages));
Mel Gorman76ab0f52010-05-24 14:32:28 -07001628 }
Mel Gorman76ab0f52010-05-24 14:32:28 -07001629}
1630
Andrew Morton7103f162013-02-22 16:32:33 -08001631void compact_pgdat(pg_data_t *pgdat, int order)
Rik van Riel7be62de2012-03-21 16:33:52 -07001632{
1633 struct compact_control cc = {
1634 .order = order,
David Rientjese0b9dae2014-06-04 16:08:28 -07001635 .mode = MIGRATE_ASYNC,
Rik van Riel7be62de2012-03-21 16:33:52 -07001636 };
1637
Mel Gorman3a7200a2013-09-11 14:22:19 -07001638 if (!order)
1639 return;
1640
Andrew Morton7103f162013-02-22 16:32:33 -08001641 __compact_pgdat(pgdat, &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001642}
1643
Andrew Morton7103f162013-02-22 16:32:33 -08001644static void compact_node(int nid)
Rik van Riel7be62de2012-03-21 16:33:52 -07001645{
Rik van Riel7be62de2012-03-21 16:33:52 -07001646 struct compact_control cc = {
1647 .order = -1,
David Rientjese0b9dae2014-06-04 16:08:28 -07001648 .mode = MIGRATE_SYNC,
David Rientjes91ca9182014-04-03 14:47:23 -07001649 .ignore_skip_hint = true,
Rik van Riel7be62de2012-03-21 16:33:52 -07001650 };
1651
Andrew Morton7103f162013-02-22 16:32:33 -08001652 __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001653}
1654
Mel Gorman76ab0f52010-05-24 14:32:28 -07001655/* Compact all nodes in the system */
Jason Liu7964c062013-01-11 14:31:47 -08001656static void compact_nodes(void)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001657{
1658 int nid;
1659
Hugh Dickins8575ec22012-03-21 16:33:53 -07001660 /* Flush pending updates to the LRU lists */
1661 lru_add_drain_all();
1662
Mel Gorman76ab0f52010-05-24 14:32:28 -07001663 for_each_online_node(nid)
1664 compact_node(nid);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001665}
1666
1667/* The written value is actually unused, all memory is compacted */
1668int sysctl_compact_memory;
1669
1670/* This is the entry point for compacting all nodes via /proc/sys/vm */
1671int sysctl_compaction_handler(struct ctl_table *table, int write,
1672 void __user *buffer, size_t *length, loff_t *ppos)
1673{
1674 if (write)
Jason Liu7964c062013-01-11 14:31:47 -08001675 compact_nodes();
Mel Gorman76ab0f52010-05-24 14:32:28 -07001676
1677 return 0;
1678}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001679
Mel Gorman5e771902010-05-24 14:32:31 -07001680int sysctl_extfrag_handler(struct ctl_table *table, int write,
1681 void __user *buffer, size_t *length, loff_t *ppos)
1682{
1683 proc_dointvec_minmax(table, write, buffer, length, ppos);
1684
1685 return 0;
1686}
1687
Mel Gormaned4a6d72010-05-24 14:32:29 -07001688#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Rashika Kheria74e77fb2014-04-03 14:48:01 -07001689static ssize_t sysfs_compact_node(struct device *dev,
Kay Sievers10fbcf42011-12-21 14:48:43 -08001690 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001691 const char *buf, size_t count)
1692{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001693 int nid = dev->id;
1694
1695 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1696 /* Flush pending updates to the LRU lists */
1697 lru_add_drain_all();
1698
1699 compact_node(nid);
1700 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001701
1702 return count;
1703}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001704static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001705
1706int compaction_register_node(struct node *node)
1707{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001708 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001709}
1710
1711void compaction_unregister_node(struct node *node)
1712{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001713 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001714}
1715#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001716
1717#endif /* CONFIG_COMPACTION */