blob: 0409a4ad6ea1363611d49269ecbb5ef88afe5c87 [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 */
Vlastimil Babka698b1b32016-03-17 14:18:08 -070010#include <linux/cpu.h>
Mel Gorman748446b2010-05-24 14:32:27 -070011#include <linux/swap.h>
12#include <linux/migrate.h>
13#include <linux/compaction.h>
14#include <linux/mm_inline.h>
15#include <linux/backing-dev.h>
Mel Gorman76ab0f52010-05-24 14:32:28 -070016#include <linux/sysctl.h>
Mel Gormaned4a6d72010-05-24 14:32:29 -070017#include <linux/sysfs.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>
Vlastimil Babka698b1b32016-03-17 14:18:08 -070020#include <linux/kthread.h>
21#include <linux/freezer.h>
Joonsoo Kim83358ec2016-07-26 15:23:43 -070022#include <linux/page_owner.h>
Mel Gorman748446b2010-05-24 14:32:27 -070023#include "internal.h"
24
Minchan Kim010fc292012-12-20 15:05:06 -080025#ifdef CONFIG_COMPACTION
26static inline void count_compact_event(enum vm_event_item item)
27{
28 count_vm_event(item);
29}
30
31static inline void count_compact_events(enum vm_event_item item, long delta)
32{
33 count_vm_events(item, delta);
34}
35#else
36#define count_compact_event(item) do { } while (0)
37#define count_compact_events(item, delta) do { } while (0)
38#endif
39
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010040#if defined CONFIG_COMPACTION || defined CONFIG_CMA
41
Mel Gormanb7aba692011-01-13 15:45:54 -080042#define CREATE_TRACE_POINTS
43#include <trace/events/compaction.h>
44
Vlastimil Babka06b66402016-05-19 17:11:48 -070045#define block_start_pfn(pfn, order) round_down(pfn, 1UL << (order))
46#define block_end_pfn(pfn, order) ALIGN((pfn) + 1, 1UL << (order))
47#define pageblock_start_pfn(pfn) block_start_pfn(pfn, pageblock_order)
48#define pageblock_end_pfn(pfn) block_end_pfn(pfn, pageblock_order)
49
Mel Gorman748446b2010-05-24 14:32:27 -070050static unsigned long release_freepages(struct list_head *freelist)
51{
52 struct page *page, *next;
Vlastimil Babka6bace092014-12-10 15:43:31 -080053 unsigned long high_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070054
55 list_for_each_entry_safe(page, next, freelist, lru) {
Vlastimil Babka6bace092014-12-10 15:43:31 -080056 unsigned long pfn = page_to_pfn(page);
Mel Gorman748446b2010-05-24 14:32:27 -070057 list_del(&page->lru);
58 __free_page(page);
Vlastimil Babka6bace092014-12-10 15:43:31 -080059 if (pfn > high_pfn)
60 high_pfn = pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070061 }
62
Vlastimil Babka6bace092014-12-10 15:43:31 -080063 return high_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070064}
65
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010066static void map_pages(struct list_head *list)
67{
Joonsoo Kim66c64222016-07-26 15:23:40 -070068 unsigned int i, order, nr_pages;
69 struct page *page, *next;
70 LIST_HEAD(tmp_list);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010071
Joonsoo Kim66c64222016-07-26 15:23:40 -070072 list_for_each_entry_safe(page, next, list, lru) {
73 list_del(&page->lru);
74
75 order = page_private(page);
76 nr_pages = 1 << order;
Joonsoo Kim66c64222016-07-26 15:23:40 -070077
Joonsoo Kim46f24fd2016-07-26 15:23:58 -070078 post_alloc_hook(page, order, __GFP_MOVABLE);
Joonsoo Kim66c64222016-07-26 15:23:40 -070079 if (order)
80 split_page(page, order);
81
82 for (i = 0; i < nr_pages; i++) {
83 list_add(&page->lru, &tmp_list);
84 page++;
85 }
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010086 }
Joonsoo Kim66c64222016-07-26 15:23:40 -070087
88 list_splice(&tmp_list, list);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010089}
90
Michal Nazarewicz47118af2011-12-29 13:09:50 +010091static inline bool migrate_async_suitable(int migratetype)
92{
93 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
94}
95
Mel Gormanbb13ffe2012-10-08 16:32:41 -070096#ifdef CONFIG_COMPACTION
Joonsoo Kim24e27162015-02-11 15:27:09 -080097
Minchan Kimbda807d2016-07-26 15:23:05 -070098int PageMovable(struct page *page)
99{
100 struct address_space *mapping;
101
102 VM_BUG_ON_PAGE(!PageLocked(page), page);
103 if (!__PageMovable(page))
104 return 0;
105
106 mapping = page_mapping(page);
107 if (mapping && mapping->a_ops && mapping->a_ops->isolate_page)
108 return 1;
109
110 return 0;
111}
112EXPORT_SYMBOL(PageMovable);
113
114void __SetPageMovable(struct page *page, struct address_space *mapping)
115{
116 VM_BUG_ON_PAGE(!PageLocked(page), page);
117 VM_BUG_ON_PAGE((unsigned long)mapping & PAGE_MAPPING_MOVABLE, page);
118 page->mapping = (void *)((unsigned long)mapping | PAGE_MAPPING_MOVABLE);
119}
120EXPORT_SYMBOL(__SetPageMovable);
121
122void __ClearPageMovable(struct page *page)
123{
124 VM_BUG_ON_PAGE(!PageLocked(page), page);
125 VM_BUG_ON_PAGE(!PageMovable(page), page);
126 /*
127 * Clear registered address_space val with keeping PAGE_MAPPING_MOVABLE
128 * flag so that VM can catch up released page by driver after isolation.
129 * With it, VM migration doesn't try to put it back.
130 */
131 page->mapping = (void *)((unsigned long)page->mapping &
132 PAGE_MAPPING_MOVABLE);
133}
134EXPORT_SYMBOL(__ClearPageMovable);
135
Joonsoo Kim24e27162015-02-11 15:27:09 -0800136/* Do not skip compaction more than 64 times */
137#define COMPACT_MAX_DEFER_SHIFT 6
138
139/*
140 * Compaction is deferred when compaction fails to result in a page
141 * allocation success. 1 << compact_defer_limit compactions are skipped up
142 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
143 */
144void defer_compaction(struct zone *zone, int order)
145{
146 zone->compact_considered = 0;
147 zone->compact_defer_shift++;
148
149 if (order < zone->compact_order_failed)
150 zone->compact_order_failed = order;
151
152 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
153 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
154
155 trace_mm_compaction_defer_compaction(zone, order);
156}
157
158/* Returns true if compaction should be skipped this time */
159bool compaction_deferred(struct zone *zone, int order)
160{
161 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
162
163 if (order < zone->compact_order_failed)
164 return false;
165
166 /* Avoid possible overflow */
167 if (++zone->compact_considered > defer_limit)
168 zone->compact_considered = defer_limit;
169
170 if (zone->compact_considered >= defer_limit)
171 return false;
172
173 trace_mm_compaction_deferred(zone, order);
174
175 return true;
176}
177
178/*
179 * Update defer tracking counters after successful compaction of given order,
180 * which means an allocation either succeeded (alloc_success == true) or is
181 * expected to succeed.
182 */
183void compaction_defer_reset(struct zone *zone, int order,
184 bool alloc_success)
185{
186 if (alloc_success) {
187 zone->compact_considered = 0;
188 zone->compact_defer_shift = 0;
189 }
190 if (order >= zone->compact_order_failed)
191 zone->compact_order_failed = order + 1;
192
193 trace_mm_compaction_defer_reset(zone, order);
194}
195
196/* Returns true if restarting compaction after many failures */
197bool compaction_restarting(struct zone *zone, int order)
198{
199 if (order < zone->compact_order_failed)
200 return false;
201
202 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
203 zone->compact_considered >= 1UL << zone->compact_defer_shift;
204}
205
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700206/* Returns true if the pageblock should be scanned for pages to isolate. */
207static inline bool isolation_suitable(struct compact_control *cc,
208 struct page *page)
209{
210 if (cc->ignore_skip_hint)
211 return true;
212
213 return !get_pageblock_skip(page);
214}
215
Vlastimil Babka023336412015-09-08 15:02:42 -0700216static void reset_cached_positions(struct zone *zone)
217{
218 zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
219 zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
Joonsoo Kim623446e2016-03-15 14:57:45 -0700220 zone->compact_cached_free_pfn =
Vlastimil Babka06b66402016-05-19 17:11:48 -0700221 pageblock_start_pfn(zone_end_pfn(zone) - 1);
Vlastimil Babka023336412015-09-08 15:02:42 -0700222}
223
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700224/*
225 * This function is called to clear all cached information on pageblocks that
226 * should be skipped for page isolation when the migrate and free page scanner
227 * meet.
228 */
Mel Gorman62997022012-10-08 16:32:47 -0700229static void __reset_isolation_suitable(struct zone *zone)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700230{
231 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -0800232 unsigned long end_pfn = zone_end_pfn(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700233 unsigned long pfn;
234
Mel Gorman62997022012-10-08 16:32:47 -0700235 zone->compact_blockskip_flush = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700236
237 /* Walk the zone and mark every pageblock as suitable for isolation */
238 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
239 struct page *page;
240
241 cond_resched();
242
243 if (!pfn_valid(pfn))
244 continue;
245
246 page = pfn_to_page(pfn);
247 if (zone != page_zone(page))
248 continue;
249
250 clear_pageblock_skip(page);
251 }
Vlastimil Babka023336412015-09-08 15:02:42 -0700252
253 reset_cached_positions(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700254}
255
Mel Gorman62997022012-10-08 16:32:47 -0700256void reset_isolation_suitable(pg_data_t *pgdat)
257{
258 int zoneid;
259
260 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
261 struct zone *zone = &pgdat->node_zones[zoneid];
262 if (!populated_zone(zone))
263 continue;
264
265 /* Only flush if a full compaction finished recently */
266 if (zone->compact_blockskip_flush)
267 __reset_isolation_suitable(zone);
268 }
269}
270
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700271/*
272 * If no pages were isolated then mark this pageblock to be skipped in the
Mel Gorman62997022012-10-08 16:32:47 -0700273 * future. The information is later cleared by __reset_isolation_suitable().
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700274 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700275static void update_pageblock_skip(struct compact_control *cc,
276 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700277 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700278{
Mel Gormanc89511a2012-10-08 16:32:45 -0700279 struct zone *zone = cc->zone;
David Rientjes35979ef2014-06-04 16:08:27 -0700280 unsigned long pfn;
Joonsoo Kim6815bf32013-12-18 17:08:52 -0800281
282 if (cc->ignore_skip_hint)
283 return;
284
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700285 if (!page)
286 return;
287
David Rientjes35979ef2014-06-04 16:08:27 -0700288 if (nr_isolated)
289 return;
290
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700291 set_pageblock_skip(page);
Mel Gormanc89511a2012-10-08 16:32:45 -0700292
David Rientjes35979ef2014-06-04 16:08:27 -0700293 pfn = page_to_pfn(page);
294
295 /* Update where async and sync compaction should restart */
296 if (migrate_scanner) {
David Rientjes35979ef2014-06-04 16:08:27 -0700297 if (pfn > zone->compact_cached_migrate_pfn[0])
298 zone->compact_cached_migrate_pfn[0] = pfn;
David Rientjese0b9dae2014-06-04 16:08:28 -0700299 if (cc->mode != MIGRATE_ASYNC &&
300 pfn > zone->compact_cached_migrate_pfn[1])
David Rientjes35979ef2014-06-04 16:08:27 -0700301 zone->compact_cached_migrate_pfn[1] = pfn;
302 } else {
David Rientjes35979ef2014-06-04 16:08:27 -0700303 if (pfn < zone->compact_cached_free_pfn)
304 zone->compact_cached_free_pfn = pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700305 }
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700306}
307#else
308static inline bool isolation_suitable(struct compact_control *cc,
309 struct page *page)
310{
311 return true;
312}
313
Mel Gormanc89511a2012-10-08 16:32:45 -0700314static void update_pageblock_skip(struct compact_control *cc,
315 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700316 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700317{
318}
319#endif /* CONFIG_COMPACTION */
320
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700321/*
322 * Compaction requires the taking of some coarse locks that are potentially
323 * very heavily contended. For async compaction, back out if the lock cannot
324 * be taken immediately. For sync compaction, spin on the lock if needed.
325 *
326 * Returns true if the lock is held
327 * Returns false if the lock is not held and compaction should abort
328 */
329static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
330 struct compact_control *cc)
Mel Gorman2a1402a2012-10-08 16:32:33 -0700331{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700332 if (cc->mode == MIGRATE_ASYNC) {
333 if (!spin_trylock_irqsave(lock, *flags)) {
Vlastimil Babkac3486f52016-07-28 15:49:30 -0700334 cc->contended = true;
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700335 return false;
336 }
337 } else {
338 spin_lock_irqsave(lock, *flags);
339 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700340
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700341 return true;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700342}
343
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100344/*
Mel Gormanc67fe372012-08-21 16:16:17 -0700345 * Compaction requires the taking of some coarse locks that are potentially
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700346 * very heavily contended. The lock should be periodically unlocked to avoid
347 * having disabled IRQs for a long time, even when there is nobody waiting on
348 * the lock. It might also be that allowing the IRQs will result in
349 * need_resched() becoming true. If scheduling is needed, async compaction
350 * aborts. Sync compaction schedules.
351 * Either compaction type will also abort if a fatal signal is pending.
352 * In either case if the lock was locked, it is dropped and not regained.
Mel Gormanc67fe372012-08-21 16:16:17 -0700353 *
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700354 * Returns true if compaction should abort due to fatal signal pending, or
355 * async compaction due to need_resched()
356 * Returns false when compaction can continue (sync compaction might have
357 * scheduled)
Mel Gormanc67fe372012-08-21 16:16:17 -0700358 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700359static bool compact_unlock_should_abort(spinlock_t *lock,
360 unsigned long flags, bool *locked, struct compact_control *cc)
Mel Gormanc67fe372012-08-21 16:16:17 -0700361{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700362 if (*locked) {
363 spin_unlock_irqrestore(lock, flags);
364 *locked = false;
365 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700366
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700367 if (fatal_signal_pending(current)) {
Vlastimil Babkac3486f52016-07-28 15:49:30 -0700368 cc->contended = true;
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700369 return true;
370 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700371
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700372 if (need_resched()) {
David Rientjese0b9dae2014-06-04 16:08:28 -0700373 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babkac3486f52016-07-28 15:49:30 -0700374 cc->contended = true;
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700375 return true;
Mel Gormanc67fe372012-08-21 16:16:17 -0700376 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700377 cond_resched();
Mel Gormanc67fe372012-08-21 16:16:17 -0700378 }
379
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700380 return false;
Mel Gormanc67fe372012-08-21 16:16:17 -0700381}
382
Vlastimil Babkabe976572014-06-04 16:10:41 -0700383/*
384 * Aside from avoiding lock contention, compaction also periodically checks
385 * need_resched() and either schedules in sync compaction or aborts async
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700386 * compaction. This is similar to what compact_unlock_should_abort() does, but
Vlastimil Babkabe976572014-06-04 16:10:41 -0700387 * is used where no lock is concerned.
388 *
389 * Returns false when no scheduling was needed, or sync compaction scheduled.
390 * Returns true when async compaction should abort.
391 */
392static inline bool compact_should_abort(struct compact_control *cc)
393{
394 /* async compaction aborts if contended */
395 if (need_resched()) {
396 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babkac3486f52016-07-28 15:49:30 -0700397 cc->contended = true;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700398 return true;
399 }
400
401 cond_resched();
402 }
403
404 return false;
405}
406
Mel Gormanc67fe372012-08-21 16:16:17 -0700407/*
Jerome Marchand9e4be472013-11-12 15:07:12 -0800408 * Isolate free pages onto a private freelist. If @strict is true, will abort
409 * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
410 * (even though it may still end up isolating some pages).
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100411 */
Mel Gormanf40d1e42012-10-08 16:32:36 -0700412static unsigned long isolate_freepages_block(struct compact_control *cc,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700413 unsigned long *start_pfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100414 unsigned long end_pfn,
415 struct list_head *freelist,
416 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -0700417{
Mel Gormanb7aba692011-01-13 15:45:54 -0800418 int nr_scanned = 0, total_isolated = 0;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700419 struct page *cursor, *valid_page = NULL;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700420 unsigned long flags = 0;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700421 bool locked = false;
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700422 unsigned long blockpfn = *start_pfn;
Joonsoo Kim66c64222016-07-26 15:23:40 -0700423 unsigned int order;
Mel Gorman748446b2010-05-24 14:32:27 -0700424
Mel Gorman748446b2010-05-24 14:32:27 -0700425 cursor = pfn_to_page(blockpfn);
426
Mel Gormanf40d1e42012-10-08 16:32:36 -0700427 /* Isolate free pages. */
Mel Gorman748446b2010-05-24 14:32:27 -0700428 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
Joonsoo Kim66c64222016-07-26 15:23:40 -0700429 int isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700430 struct page *page = cursor;
431
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700432 /*
433 * Periodically drop the lock (if held) regardless of its
434 * contention, to give chance to IRQs. Abort if fatal signal
435 * pending or async compaction detects need_resched()
436 */
437 if (!(blockpfn % SWAP_CLUSTER_MAX)
438 && compact_unlock_should_abort(&cc->zone->lock, flags,
439 &locked, cc))
440 break;
441
Mel Gormanb7aba692011-01-13 15:45:54 -0800442 nr_scanned++;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700443 if (!pfn_valid_within(blockpfn))
Laura Abbott2af120b2014-03-10 15:49:44 -0700444 goto isolate_fail;
445
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700446 if (!valid_page)
447 valid_page = page;
Vlastimil Babka9fcd6d22015-09-08 15:02:49 -0700448
449 /*
450 * For compound pages such as THP and hugetlbfs, we can save
451 * potentially a lot of iterations if we skip them at once.
452 * The check is racy, but we can consider only valid values
453 * and the only danger is skipping too much.
454 */
455 if (PageCompound(page)) {
456 unsigned int comp_order = compound_order(page);
457
458 if (likely(comp_order < MAX_ORDER)) {
459 blockpfn += (1UL << comp_order) - 1;
460 cursor += (1UL << comp_order) - 1;
461 }
462
463 goto isolate_fail;
464 }
465
Mel Gormanf40d1e42012-10-08 16:32:36 -0700466 if (!PageBuddy(page))
Laura Abbott2af120b2014-03-10 15:49:44 -0700467 goto isolate_fail;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700468
469 /*
Vlastimil Babka69b71892014-10-09 15:27:18 -0700470 * If we already hold the lock, we can skip some rechecking.
471 * Note that if we hold the lock now, checked_pageblock was
472 * already set in some previous iteration (or strict is true),
473 * so it is correct to skip the suitable migration target
474 * recheck as well.
Mel Gormanf40d1e42012-10-08 16:32:36 -0700475 */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700476 if (!locked) {
477 /*
478 * The zone lock must be held to isolate freepages.
479 * Unfortunately this is a very coarse lock and can be
480 * heavily contended if there are parallel allocations
481 * or parallel compactions. For async compaction do not
482 * spin on the lock and we acquire the lock as late as
483 * possible.
484 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700485 locked = compact_trylock_irqsave(&cc->zone->lock,
486 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700487 if (!locked)
488 break;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700489
Vlastimil Babka69b71892014-10-09 15:27:18 -0700490 /* Recheck this is a buddy page under lock */
491 if (!PageBuddy(page))
492 goto isolate_fail;
493 }
Mel Gorman748446b2010-05-24 14:32:27 -0700494
Joonsoo Kim66c64222016-07-26 15:23:40 -0700495 /* Found a free page, will break it into order-0 pages */
496 order = page_order(page);
497 isolated = __isolate_free_page(page, order);
David Rientjesa4f04f22016-06-24 14:50:10 -0700498 if (!isolated)
499 break;
Joonsoo Kim66c64222016-07-26 15:23:40 -0700500 set_page_private(page, order);
David Rientjesa4f04f22016-06-24 14:50:10 -0700501
Mel Gorman748446b2010-05-24 14:32:27 -0700502 total_isolated += isolated;
David Rientjesa4f04f22016-06-24 14:50:10 -0700503 cc->nr_freepages += isolated;
Joonsoo Kim66c64222016-07-26 15:23:40 -0700504 list_add_tail(&page->lru, freelist);
505
David Rientjesa4f04f22016-06-24 14:50:10 -0700506 if (!strict && cc->nr_migratepages <= cc->nr_freepages) {
507 blockpfn += isolated;
508 break;
Mel Gorman748446b2010-05-24 14:32:27 -0700509 }
David Rientjesa4f04f22016-06-24 14:50:10 -0700510 /* Advance to the end of split page */
511 blockpfn += isolated - 1;
512 cursor += isolated - 1;
513 continue;
Laura Abbott2af120b2014-03-10 15:49:44 -0700514
515isolate_fail:
516 if (strict)
517 break;
518 else
519 continue;
520
Mel Gorman748446b2010-05-24 14:32:27 -0700521 }
522
David Rientjesa4f04f22016-06-24 14:50:10 -0700523 if (locked)
524 spin_unlock_irqrestore(&cc->zone->lock, flags);
525
Vlastimil Babka9fcd6d22015-09-08 15:02:49 -0700526 /*
527 * There is a tiny chance that we have read bogus compound_order(),
528 * so be careful to not go outside of the pageblock.
529 */
530 if (unlikely(blockpfn > end_pfn))
531 blockpfn = end_pfn;
532
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800533 trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
534 nr_scanned, total_isolated);
535
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700536 /* Record how far we have got within the block */
537 *start_pfn = blockpfn;
538
Mel Gormanf40d1e42012-10-08 16:32:36 -0700539 /*
540 * If strict isolation is requested by CMA then check that all the
541 * pages requested were isolated. If there were any failures, 0 is
542 * returned and CMA will fail.
543 */
Laura Abbott2af120b2014-03-10 15:49:44 -0700544 if (strict && blockpfn < end_pfn)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700545 total_isolated = 0;
546
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700547 /* Update the pageblock-skip if the whole pageblock was scanned */
548 if (blockpfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700549 update_pageblock_skip(cc, valid_page, total_isolated, false);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700550
Minchan Kim010fc292012-12-20 15:05:06 -0800551 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100552 if (total_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800553 count_compact_events(COMPACTISOLATED, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700554 return total_isolated;
555}
556
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100557/**
558 * isolate_freepages_range() - isolate free pages.
559 * @start_pfn: The first PFN to start isolating.
560 * @end_pfn: The one-past-last PFN.
561 *
562 * Non-free pages, invalid PFNs, or zone boundaries within the
563 * [start_pfn, end_pfn) range are considered errors, cause function to
564 * undo its actions and return zero.
565 *
566 * Otherwise, function returns one-past-the-last PFN of isolated page
567 * (which may be greater then end_pfn if end fell in a middle of
568 * a free page).
569 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100570unsigned long
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700571isolate_freepages_range(struct compact_control *cc,
572 unsigned long start_pfn, unsigned long end_pfn)
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100573{
Joonsoo Kime1409c32016-03-15 14:57:48 -0700574 unsigned long isolated, pfn, block_start_pfn, block_end_pfn;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100575 LIST_HEAD(freelist);
576
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700577 pfn = start_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -0700578 block_start_pfn = pageblock_start_pfn(pfn);
Joonsoo Kime1409c32016-03-15 14:57:48 -0700579 if (block_start_pfn < cc->zone->zone_start_pfn)
580 block_start_pfn = cc->zone->zone_start_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -0700581 block_end_pfn = pageblock_end_pfn(pfn);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100582
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700583 for (; pfn < end_pfn; pfn += isolated,
Joonsoo Kime1409c32016-03-15 14:57:48 -0700584 block_start_pfn = block_end_pfn,
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700585 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700586 /* Protect pfn from changing by isolate_freepages_block */
587 unsigned long isolate_start_pfn = pfn;
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700588
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100589 block_end_pfn = min(block_end_pfn, end_pfn);
590
Joonsoo Kim58420012014-11-13 15:19:07 -0800591 /*
592 * pfn could pass the block_end_pfn if isolated freepage
593 * is more than pageblock order. In this case, we adjust
594 * scanning range to right one.
595 */
596 if (pfn >= block_end_pfn) {
Vlastimil Babka06b66402016-05-19 17:11:48 -0700597 block_start_pfn = pageblock_start_pfn(pfn);
598 block_end_pfn = pageblock_end_pfn(pfn);
Joonsoo Kim58420012014-11-13 15:19:07 -0800599 block_end_pfn = min(block_end_pfn, end_pfn);
600 }
601
Joonsoo Kime1409c32016-03-15 14:57:48 -0700602 if (!pageblock_pfn_to_page(block_start_pfn,
603 block_end_pfn, cc->zone))
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700604 break;
605
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700606 isolated = isolate_freepages_block(cc, &isolate_start_pfn,
607 block_end_pfn, &freelist, true);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100608
609 /*
610 * In strict mode, isolate_freepages_block() returns 0 if
611 * there are any holes in the block (ie. invalid PFNs or
612 * non-free pages).
613 */
614 if (!isolated)
615 break;
616
617 /*
618 * If we managed to isolate pages, it is always (1 << n) *
619 * pageblock_nr_pages for some non-negative n. (Max order
620 * page may span two pageblocks).
621 */
622 }
623
Joonsoo Kim66c64222016-07-26 15:23:40 -0700624 /* __isolate_free_page() does not map the pages */
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100625 map_pages(&freelist);
626
627 if (pfn < end_pfn) {
628 /* Loop terminated early, cleanup. */
629 release_freepages(&freelist);
630 return 0;
631 }
632
633 /* We don't use freelists for anything. */
634 return pfn;
635}
636
Mel Gorman748446b2010-05-24 14:32:27 -0700637/* Update the number of anon and file isolated pages in the zone */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700638static void acct_isolated(struct zone *zone, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700639{
640 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700641 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700642
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700643 if (list_empty(&cc->migratepages))
644 return;
645
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700646 list_for_each_entry(page, &cc->migratepages, lru)
647 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700648
Mel Gorman599d0c92016-07-28 15:45:31 -0700649 mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON, count[0]);
650 mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, count[1]);
Mel Gorman748446b2010-05-24 14:32:27 -0700651}
652
653/* Similar to reclaim, but different enough that they don't share logic */
654static bool too_many_isolated(struct zone *zone)
655{
Minchan Kimbc693042010-09-09 16:38:00 -0700656 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700657
Mel Gorman599d0c92016-07-28 15:45:31 -0700658 inactive = node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE) +
659 node_page_state(zone->zone_pgdat, NR_INACTIVE_ANON);
660 active = node_page_state(zone->zone_pgdat, NR_ACTIVE_FILE) +
661 node_page_state(zone->zone_pgdat, NR_ACTIVE_ANON);
662 isolated = node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE) +
663 node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700664
Minchan Kimbc693042010-09-09 16:38:00 -0700665 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700666}
667
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100668/**
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700669 * isolate_migratepages_block() - isolate all migrate-able pages within
670 * a single pageblock
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100671 * @cc: Compaction control structure.
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700672 * @low_pfn: The first PFN to isolate
673 * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock
674 * @isolate_mode: Isolation mode to be used.
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100675 *
676 * Isolate all pages that can be migrated from the range specified by
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700677 * [low_pfn, end_pfn). The range is expected to be within same pageblock.
678 * Returns zero if there is a fatal signal pending, otherwise PFN of the
679 * first page that was not scanned (which may be both less, equal to or more
680 * than end_pfn).
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100681 *
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700682 * The pages are isolated on cc->migratepages list (not required to be empty),
683 * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
684 * is neither read nor updated.
Mel Gorman748446b2010-05-24 14:32:27 -0700685 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700686static unsigned long
687isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
688 unsigned long end_pfn, isolate_mode_t isolate_mode)
Mel Gorman748446b2010-05-24 14:32:27 -0700689{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700690 struct zone *zone = cc->zone;
Mel Gormanb7aba692011-01-13 15:45:54 -0800691 unsigned long nr_scanned = 0, nr_isolated = 0;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700692 struct lruvec *lruvec;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700693 unsigned long flags = 0;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700694 bool locked = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700695 struct page *page = NULL, *valid_page = NULL;
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800696 unsigned long start_pfn = low_pfn;
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700697 bool skip_on_failure = false;
698 unsigned long next_skip_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700699
Mel Gorman748446b2010-05-24 14:32:27 -0700700 /*
701 * Ensure that there are not too many pages isolated from the LRU
702 * list by either parallel reclaimers or compaction. If there are,
703 * delay for some time until fewer pages are isolated
704 */
705 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700706 /* async migration should just abort */
David Rientjese0b9dae2014-06-04 16:08:28 -0700707 if (cc->mode == MIGRATE_ASYNC)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100708 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700709
Mel Gorman748446b2010-05-24 14:32:27 -0700710 congestion_wait(BLK_RW_ASYNC, HZ/10);
711
712 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100713 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700714 }
715
Vlastimil Babkabe976572014-06-04 16:10:41 -0700716 if (compact_should_abort(cc))
717 return 0;
David Rientjesaeef4b82014-06-04 16:08:31 -0700718
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700719 if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC)) {
720 skip_on_failure = true;
721 next_skip_pfn = block_end_pfn(low_pfn, cc->order);
722 }
723
Mel Gorman748446b2010-05-24 14:32:27 -0700724 /* Time to isolate some pages for migration */
Mel Gorman748446b2010-05-24 14:32:27 -0700725 for (; low_pfn < end_pfn; low_pfn++) {
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700726
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700727 if (skip_on_failure && low_pfn >= next_skip_pfn) {
728 /*
729 * We have isolated all migration candidates in the
730 * previous order-aligned block, and did not skip it due
731 * to failure. We should migrate the pages now and
732 * hopefully succeed compaction.
733 */
734 if (nr_isolated)
735 break;
736
737 /*
738 * We failed to isolate in the previous order-aligned
739 * block. Set the new boundary to the end of the
740 * current block. Note we can't simply increase
741 * next_skip_pfn by 1 << order, as low_pfn might have
742 * been incremented by a higher number due to skipping
743 * a compound or a high-order buddy page in the
744 * previous loop iteration.
745 */
746 next_skip_pfn = block_end_pfn(low_pfn, cc->order);
747 }
748
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700749 /*
750 * Periodically drop the lock (if held) regardless of its
751 * contention, to give chance to IRQs. Abort async compaction
752 * if contended.
753 */
754 if (!(low_pfn % SWAP_CLUSTER_MAX)
Mel Gormana52633d2016-07-28 15:45:28 -0700755 && compact_unlock_should_abort(zone_lru_lock(zone), flags,
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700756 &locked, cc))
757 break;
Mel Gormanc67fe372012-08-21 16:16:17 -0700758
Mel Gorman748446b2010-05-24 14:32:27 -0700759 if (!pfn_valid_within(low_pfn))
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700760 goto isolate_fail;
Mel Gormanb7aba692011-01-13 15:45:54 -0800761 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700762
Mel Gorman748446b2010-05-24 14:32:27 -0700763 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800764
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700765 if (!valid_page)
766 valid_page = page;
767
Mel Gorman6c144662014-01-23 15:53:38 -0800768 /*
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700769 * Skip if free. We read page order here without zone lock
770 * which is generally unsafe, but the race window is small and
771 * the worst thing that can happen is that we skip some
772 * potential isolation targets.
Mel Gorman6c144662014-01-23 15:53:38 -0800773 */
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700774 if (PageBuddy(page)) {
775 unsigned long freepage_order = page_order_unsafe(page);
776
777 /*
778 * Without lock, we cannot be sure that what we got is
779 * a valid page order. Consider only values in the
780 * valid order range to prevent low_pfn overflow.
781 */
782 if (freepage_order > 0 && freepage_order < MAX_ORDER)
783 low_pfn += (1UL << freepage_order) - 1;
Mel Gorman748446b2010-05-24 14:32:27 -0700784 continue;
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700785 }
Mel Gorman748446b2010-05-24 14:32:27 -0700786
Mel Gorman9927af742011-01-13 15:45:59 -0800787 /*
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700788 * Regardless of being on LRU, compound pages such as THP and
789 * hugetlbfs are not to be compacted. We can potentially save
790 * a lot of iterations if we skip them at once. The check is
791 * racy, but we can consider only valid values and the only
792 * danger is skipping too much.
Andrea Arcangelibc835012011-01-13 15:47:08 -0800793 */
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700794 if (PageCompound(page)) {
795 unsigned int comp_order = compound_order(page);
796
797 if (likely(comp_order < MAX_ORDER))
798 low_pfn += (1UL << comp_order) - 1;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700799
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700800 goto isolate_fail;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700801 }
802
Minchan Kimbda807d2016-07-26 15:23:05 -0700803 /*
804 * Check may be lockless but that's ok as we recheck later.
805 * It's possible to migrate LRU and non-lru movable pages.
806 * Skip any other type of page
807 */
808 if (!PageLRU(page)) {
Minchan Kimbda807d2016-07-26 15:23:05 -0700809 /*
810 * __PageMovable can return false positive so we need
811 * to verify it under page_lock.
812 */
813 if (unlikely(__PageMovable(page)) &&
814 !PageIsolated(page)) {
815 if (locked) {
Mel Gormana52633d2016-07-28 15:45:28 -0700816 spin_unlock_irqrestore(zone_lru_lock(zone),
Minchan Kimbda807d2016-07-26 15:23:05 -0700817 flags);
818 locked = false;
819 }
820
821 if (isolate_movable_page(page, isolate_mode))
822 goto isolate_success;
823 }
824
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700825 goto isolate_fail;
Minchan Kimbda807d2016-07-26 15:23:05 -0700826 }
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700827
David Rientjes119d6d52014-04-03 14:48:00 -0700828 /*
829 * Migration will fail if an anonymous page is pinned in memory,
830 * so avoid taking lru_lock and isolating it unnecessarily in an
831 * admittedly racy check.
832 */
833 if (!page_mapping(page) &&
834 page_count(page) > page_mapcount(page))
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700835 goto isolate_fail;
David Rientjes119d6d52014-04-03 14:48:00 -0700836
Vlastimil Babka69b71892014-10-09 15:27:18 -0700837 /* If we already hold the lock, we can skip some rechecking */
838 if (!locked) {
Mel Gormana52633d2016-07-28 15:45:28 -0700839 locked = compact_trylock_irqsave(zone_lru_lock(zone),
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700840 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700841 if (!locked)
842 break;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700843
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700844 /* Recheck PageLRU and PageCompound under lock */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700845 if (!PageLRU(page))
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700846 goto isolate_fail;
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700847
848 /*
849 * Page become compound since the non-locked check,
850 * and it's on LRU. It can only be a THP so the order
851 * is safe to read and it's 0 for tail pages.
852 */
853 if (unlikely(PageCompound(page))) {
854 low_pfn += (1UL << compound_order(page)) - 1;
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700855 goto isolate_fail;
Vlastimil Babka69b71892014-10-09 15:27:18 -0700856 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800857 }
858
Mel Gorman599d0c92016-07-28 15:45:31 -0700859 lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700860
Mel Gorman748446b2010-05-24 14:32:27 -0700861 /* Try isolate the page */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700862 if (__isolate_lru_page(page, isolate_mode) != 0)
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700863 goto isolate_fail;
Mel Gorman748446b2010-05-24 14:32:27 -0700864
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700865 VM_BUG_ON_PAGE(PageCompound(page), page);
Andrea Arcangelibc835012011-01-13 15:47:08 -0800866
Mel Gorman748446b2010-05-24 14:32:27 -0700867 /* Successfully isolated */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700868 del_page_from_lru_list(page, lruvec, page_lru(page));
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700869
870isolate_success:
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700871 list_add(&page->lru, &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -0700872 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800873 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700874
Vlastimil Babkaa34753d2016-05-19 17:11:51 -0700875 /*
876 * Record where we could have freed pages by migration and not
877 * yet flushed them to buddy allocator.
878 * - this is the lowest page that was isolated and likely be
879 * then freed by migration.
880 */
881 if (!cc->last_migrated_pfn)
882 cc->last_migrated_pfn = low_pfn;
883
Mel Gorman748446b2010-05-24 14:32:27 -0700884 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800885 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
886 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700887 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800888 }
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700889
890 continue;
891isolate_fail:
892 if (!skip_on_failure)
893 continue;
894
895 /*
896 * We have isolated some pages, but then failed. Release them
897 * instead of migrating, as we cannot form the cc->order buddy
898 * page anyway.
899 */
900 if (nr_isolated) {
901 if (locked) {
Mel Gormana52633d2016-07-28 15:45:28 -0700902 spin_unlock_irqrestore(zone_lru_lock(zone), flags);
Vlastimil Babkafdd048e2016-05-19 17:11:55 -0700903 locked = false;
904 }
905 acct_isolated(zone, cc);
906 putback_movable_pages(&cc->migratepages);
907 cc->nr_migratepages = 0;
908 cc->last_migrated_pfn = 0;
909 nr_isolated = 0;
910 }
911
912 if (low_pfn < next_skip_pfn) {
913 low_pfn = next_skip_pfn - 1;
914 /*
915 * The check near the loop beginning would have updated
916 * next_skip_pfn too, but this is a bit simpler.
917 */
918 next_skip_pfn += 1UL << cc->order;
919 }
Mel Gorman748446b2010-05-24 14:32:27 -0700920 }
921
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700922 /*
923 * The PageBuddy() check could have potentially brought us outside
924 * the range to be scanned.
925 */
926 if (unlikely(low_pfn > end_pfn))
927 low_pfn = end_pfn;
928
Mel Gormanc67fe372012-08-21 16:16:17 -0700929 if (locked)
Mel Gormana52633d2016-07-28 15:45:28 -0700930 spin_unlock_irqrestore(zone_lru_lock(zone), flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700931
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800932 /*
933 * Update the pageblock-skip information and cached scanner pfn,
934 * if the whole pageblock was scanned without isolating any page.
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800935 */
David Rientjes35979ef2014-06-04 16:08:27 -0700936 if (low_pfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700937 update_pageblock_skip(cc, valid_page, nr_isolated, true);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700938
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800939 trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
940 nr_scanned, nr_isolated);
Mel Gormanb7aba692011-01-13 15:45:54 -0800941
Minchan Kim010fc292012-12-20 15:05:06 -0800942 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100943 if (nr_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800944 count_compact_events(COMPACTISOLATED, nr_isolated);
Mel Gorman397487d2012-10-19 12:00:10 +0100945
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100946 return low_pfn;
947}
948
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700949/**
950 * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
951 * @cc: Compaction control structure.
952 * @start_pfn: The first PFN to start isolating.
953 * @end_pfn: The one-past-last PFN.
954 *
955 * Returns zero if isolation fails fatally due to e.g. pending signal.
956 * Otherwise, function returns one-past-the-last PFN of isolated page
957 * (which may be greater than end_pfn if end fell in a middle of a THP page).
958 */
959unsigned long
960isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
961 unsigned long end_pfn)
962{
Joonsoo Kime1409c32016-03-15 14:57:48 -0700963 unsigned long pfn, block_start_pfn, block_end_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700964
965 /* Scan block by block. First and last block may be incomplete */
966 pfn = start_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -0700967 block_start_pfn = pageblock_start_pfn(pfn);
Joonsoo Kime1409c32016-03-15 14:57:48 -0700968 if (block_start_pfn < cc->zone->zone_start_pfn)
969 block_start_pfn = cc->zone->zone_start_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -0700970 block_end_pfn = pageblock_end_pfn(pfn);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700971
972 for (; pfn < end_pfn; pfn = block_end_pfn,
Joonsoo Kime1409c32016-03-15 14:57:48 -0700973 block_start_pfn = block_end_pfn,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700974 block_end_pfn += pageblock_nr_pages) {
975
976 block_end_pfn = min(block_end_pfn, end_pfn);
977
Joonsoo Kime1409c32016-03-15 14:57:48 -0700978 if (!pageblock_pfn_to_page(block_start_pfn,
979 block_end_pfn, cc->zone))
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700980 continue;
981
982 pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
983 ISOLATE_UNEVICTABLE);
984
Hugh Dickins14af4a52016-05-05 16:22:15 -0700985 if (!pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700986 break;
Joonsoo Kim6ea41c02014-10-29 14:50:20 -0700987
988 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
989 break;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700990 }
991 acct_isolated(cc->zone, cc);
992
993 return pfn;
994}
995
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100996#endif /* CONFIG_COMPACTION || CONFIG_CMA */
997#ifdef CONFIG_COMPACTION
Andrew Morton018e9a42015-04-15 16:15:20 -0700998
999/* Returns true if the page is within a block suitable for migration to */
Vlastimil Babka9f7e3382016-10-07 17:00:37 -07001000static bool suitable_migration_target(struct compact_control *cc,
1001 struct page *page)
Andrew Morton018e9a42015-04-15 16:15:20 -07001002{
Vlastimil Babka9f7e3382016-10-07 17:00:37 -07001003 if (cc->ignore_block_suitable)
1004 return true;
1005
Andrew Morton018e9a42015-04-15 16:15:20 -07001006 /* If the page is a large free page, then disallow migration */
1007 if (PageBuddy(page)) {
1008 /*
1009 * We are checking page_order without zone->lock taken. But
1010 * the only small danger is that we skip a potentially suitable
1011 * pageblock, so it's not worth to check order for valid range.
1012 */
1013 if (page_order_unsafe(page) >= pageblock_order)
1014 return false;
1015 }
1016
1017 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
1018 if (migrate_async_suitable(get_pageblock_migratetype(page)))
1019 return true;
1020
1021 /* Otherwise skip the block */
1022 return false;
1023}
1024
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001025/*
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001026 * Test whether the free scanner has reached the same or lower pageblock than
1027 * the migration scanner, and compaction should thus terminate.
1028 */
1029static inline bool compact_scanners_met(struct compact_control *cc)
1030{
1031 return (cc->free_pfn >> pageblock_order)
1032 <= (cc->migrate_pfn >> pageblock_order);
1033}
1034
1035/*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001036 * Based on information in the current compact_control, find blocks
1037 * suitable for isolating free pages from and then isolate them.
1038 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001039static void isolate_freepages(struct compact_control *cc)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001040{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001041 struct zone *zone = cc->zone;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001042 struct page *page;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -07001043 unsigned long block_start_pfn; /* start of current pageblock */
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001044 unsigned long isolate_start_pfn; /* exact pfn we start at */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -07001045 unsigned long block_end_pfn; /* end of current pageblock */
1046 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001047 struct list_head *freelist = &cc->freepages;
1048
1049 /*
1050 * Initialise the free scanner. The starting point is where we last
Vlastimil Babka49e068f2014-05-06 12:50:03 -07001051 * successfully isolated from, zone-cached value, or the end of the
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001052 * zone when isolating for the first time. For looping we also need
1053 * this pfn aligned down to the pageblock boundary, because we do
Vlastimil Babkac96b9e52014-06-04 16:07:26 -07001054 * block_start_pfn -= pageblock_nr_pages in the for loop.
1055 * For ending point, take care when isolating in last pageblock of a
1056 * a zone which ends in the middle of a pageblock.
Vlastimil Babka49e068f2014-05-06 12:50:03 -07001057 * The low boundary is the end of the pageblock the migration scanner
1058 * is using.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001059 */
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001060 isolate_start_pfn = cc->free_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -07001061 block_start_pfn = pageblock_start_pfn(cc->free_pfn);
Vlastimil Babkac96b9e52014-06-04 16:07:26 -07001062 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
1063 zone_end_pfn(zone));
Vlastimil Babka06b66402016-05-19 17:11:48 -07001064 low_pfn = pageblock_end_pfn(cc->migrate_pfn);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001065
1066 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001067 * Isolate free pages until enough are available to migrate the
1068 * pages on cc->migratepages. We stop searching if the migrate
1069 * and free page scanners meet or enough free pages are isolated.
1070 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001071 for (; block_start_pfn >= low_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -07001072 block_end_pfn = block_start_pfn,
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001073 block_start_pfn -= pageblock_nr_pages,
1074 isolate_start_pfn = block_start_pfn) {
David Rientjesf6ea3ad2013-09-30 13:45:03 -07001075 /*
1076 * This can iterate a massively long zone without finding any
1077 * suitable migration targets, so periodically check if we need
Vlastimil Babkabe976572014-06-04 16:10:41 -07001078 * to schedule, or even abort async compaction.
David Rientjesf6ea3ad2013-09-30 13:45:03 -07001079 */
Vlastimil Babkabe976572014-06-04 16:10:41 -07001080 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1081 && compact_should_abort(cc))
1082 break;
David Rientjesf6ea3ad2013-09-30 13:45:03 -07001083
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001084 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
1085 zone);
1086 if (!page)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001087 continue;
1088
1089 /* Check the block is suitable for migration */
Vlastimil Babka9f7e3382016-10-07 17:00:37 -07001090 if (!suitable_migration_target(cc, page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001091 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -07001092
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001093 /* If isolation recently failed, do not retry */
1094 if (!isolation_suitable(cc, page))
1095 continue;
1096
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001097 /* Found a block suitable for isolating free pages from. */
David Rientjesa46cbf32016-07-14 12:06:50 -07001098 isolate_freepages_block(cc, &isolate_start_pfn, block_end_pfn,
1099 freelist, false);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001100
1101 /*
David Rientjesa46cbf32016-07-14 12:06:50 -07001102 * If we isolated enough freepages, or aborted due to lock
1103 * contention, terminate.
Vlastimil Babkae14c7202014-10-09 15:27:20 -07001104 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001105 if ((cc->nr_freepages >= cc->nr_migratepages)
1106 || cc->contended) {
David Rientjesa46cbf32016-07-14 12:06:50 -07001107 if (isolate_start_pfn >= block_end_pfn) {
1108 /*
1109 * Restart at previous pageblock if more
1110 * freepages can be isolated next time.
1111 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001112 isolate_start_pfn =
1113 block_start_pfn - pageblock_nr_pages;
David Rientjesa46cbf32016-07-14 12:06:50 -07001114 }
Vlastimil Babkabe976572014-06-04 16:10:41 -07001115 break;
David Rientjesa46cbf32016-07-14 12:06:50 -07001116 } else if (isolate_start_pfn < block_end_pfn) {
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001117 /*
David Rientjesa46cbf32016-07-14 12:06:50 -07001118 * If isolation failed early, do not continue
1119 * needlessly.
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001120 */
David Rientjesa46cbf32016-07-14 12:06:50 -07001121 break;
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001122 }
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +01001123 }
1124
Joonsoo Kim66c64222016-07-26 15:23:40 -07001125 /* __isolate_free_page() does not map the pages */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001126 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +01001127
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001128 /*
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001129 * Record where the free scanner will restart next time. Either we
1130 * broke from the loop and set isolate_start_pfn based on the last
1131 * call to isolate_freepages_block(), or we met the migration scanner
1132 * and the loop terminated due to isolate_start_pfn < low_pfn
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001133 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001134 cc->free_pfn = isolate_start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -07001135}
1136
1137/*
1138 * This is a migrate-callback that "allocates" freepages by taking pages
1139 * from the isolated freelists in the block we are migrating to.
1140 */
1141static struct page *compaction_alloc(struct page *migratepage,
1142 unsigned long data,
1143 int **result)
1144{
1145 struct compact_control *cc = (struct compact_control *)data;
1146 struct page *freepage;
1147
Vlastimil Babkabe976572014-06-04 16:10:41 -07001148 /*
1149 * Isolate free pages if necessary, and if we are not aborting due to
1150 * contention.
1151 */
Mel Gorman748446b2010-05-24 14:32:27 -07001152 if (list_empty(&cc->freepages)) {
Vlastimil Babkabe976572014-06-04 16:10:41 -07001153 if (!cc->contended)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001154 isolate_freepages(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001155
1156 if (list_empty(&cc->freepages))
1157 return NULL;
1158 }
1159
1160 freepage = list_entry(cc->freepages.next, struct page, lru);
1161 list_del(&freepage->lru);
1162 cc->nr_freepages--;
1163
1164 return freepage;
1165}
1166
1167/*
David Rientjesd53aea32014-06-04 16:08:26 -07001168 * This is a migrate-callback that "frees" freepages back to the isolated
1169 * freelist. All pages on the freelist are from the same zone, so there is no
1170 * special handling needed for NUMA.
1171 */
1172static void compaction_free(struct page *page, unsigned long data)
1173{
1174 struct compact_control *cc = (struct compact_control *)data;
1175
1176 list_add(&page->lru, &cc->freepages);
1177 cc->nr_freepages++;
1178}
1179
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001180/* possible outcome of isolate_migratepages */
1181typedef enum {
1182 ISOLATE_ABORT, /* Abort compaction now */
1183 ISOLATE_NONE, /* No pages isolated, continue scanning */
1184 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1185} isolate_migrate_t;
1186
1187/*
Eric B Munson5bbe3542015-04-15 16:13:20 -07001188 * Allow userspace to control policy on scanning the unevictable LRU for
1189 * compactable pages.
1190 */
1191int sysctl_compact_unevictable_allowed __read_mostly = 1;
1192
1193/*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001194 * Isolate all pages that can be migrated from the first suitable block,
1195 * starting at the block pointed to by the migrate scanner pfn within
1196 * compact_control.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001197 */
1198static isolate_migrate_t isolate_migratepages(struct zone *zone,
1199 struct compact_control *cc)
1200{
Joonsoo Kime1409c32016-03-15 14:57:48 -07001201 unsigned long block_start_pfn;
1202 unsigned long block_end_pfn;
1203 unsigned long low_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001204 struct page *page;
1205 const isolate_mode_t isolate_mode =
Eric B Munson5bbe3542015-04-15 16:13:20 -07001206 (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
Hugh Dickins1d2047f2016-07-28 15:48:41 -07001207 (cc->mode != MIGRATE_SYNC ? ISOLATE_ASYNC_MIGRATE : 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001208
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001209 /*
1210 * Start at where we last stopped, or beginning of the zone as
1211 * initialized by compact_zone()
1212 */
1213 low_pfn = cc->migrate_pfn;
Vlastimil Babka06b66402016-05-19 17:11:48 -07001214 block_start_pfn = pageblock_start_pfn(low_pfn);
Joonsoo Kime1409c32016-03-15 14:57:48 -07001215 if (block_start_pfn < zone->zone_start_pfn)
1216 block_start_pfn = zone->zone_start_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001217
1218 /* Only scan within a pageblock boundary */
Vlastimil Babka06b66402016-05-19 17:11:48 -07001219 block_end_pfn = pageblock_end_pfn(low_pfn);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001220
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001221 /*
1222 * Iterate over whole pageblocks until we find the first suitable.
1223 * Do not cross the free scanner.
1224 */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001225 for (; block_end_pfn <= cc->free_pfn;
1226 low_pfn = block_end_pfn,
1227 block_start_pfn = block_end_pfn,
1228 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001229
1230 /*
1231 * This can potentially iterate a massively long zone with
1232 * many pageblocks unsuitable, so periodically check if we
1233 * need to schedule, or even abort async compaction.
1234 */
1235 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1236 && compact_should_abort(cc))
1237 break;
1238
Joonsoo Kime1409c32016-03-15 14:57:48 -07001239 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
1240 zone);
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001241 if (!page)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001242 continue;
1243
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001244 /* If isolation recently failed, do not retry */
1245 if (!isolation_suitable(cc, page))
1246 continue;
1247
1248 /*
1249 * For async compaction, also only scan in MOVABLE blocks.
1250 * Async compaction is optimistic to see if the minimum amount
1251 * of work satisfies the allocation.
1252 */
1253 if (cc->mode == MIGRATE_ASYNC &&
1254 !migrate_async_suitable(get_pageblock_migratetype(page)))
1255 continue;
1256
1257 /* Perform the isolation */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001258 low_pfn = isolate_migratepages_block(cc, low_pfn,
1259 block_end_pfn, isolate_mode);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001260
Hugh Dickinsff599092015-02-12 15:00:28 -08001261 if (!low_pfn || cc->contended) {
1262 acct_isolated(zone, cc);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001263 return ISOLATE_ABORT;
Hugh Dickinsff599092015-02-12 15:00:28 -08001264 }
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001265
1266 /*
1267 * Either we isolated something and proceed with migration. Or
1268 * we failed and compact_zone should decide if we should
1269 * continue or not.
1270 */
1271 break;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001272 }
1273
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001274 acct_isolated(zone, cc);
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001275 /* Record where migration scanner will be restarted. */
1276 cc->migrate_pfn = low_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001277
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001278 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001279}
1280
Yaowei Bai21c527a2015-11-05 18:47:20 -08001281/*
1282 * order == -1 is expected when compacting via
1283 * /proc/sys/vm/compact_memory
1284 */
1285static inline bool is_via_compact_memory(int order)
1286{
1287 return order == -1;
1288}
1289
Michal Hockoea7ab982016-05-20 16:56:38 -07001290static enum compact_result __compact_finished(struct zone *zone, struct compact_control *cc,
David Rientjes6d7ce552014-10-09 15:27:27 -07001291 const int migratetype)
Mel Gorman748446b2010-05-24 14:32:27 -07001292{
Mel Gorman8fb74b92013-01-11 14:32:16 -08001293 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001294 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -07001295
Vlastimil Babkabe976572014-06-04 16:10:41 -07001296 if (cc->contended || fatal_signal_pending(current))
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001297 return COMPACT_CONTENDED;
Mel Gorman748446b2010-05-24 14:32:27 -07001298
Mel Gorman753341a2012-10-08 16:32:40 -07001299 /* Compaction run completes if the migrate and free scanner meet */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001300 if (compact_scanners_met(cc)) {
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001301 /* Let the next compaction start anew. */
Vlastimil Babka023336412015-09-08 15:02:42 -07001302 reset_cached_positions(zone);
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001303
Mel Gorman62997022012-10-08 16:32:47 -07001304 /*
1305 * Mark that the PG_migrate_skip information should be cleared
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001306 * by kswapd when it goes to sleep. kcompactd does not set the
Mel Gorman62997022012-10-08 16:32:47 -07001307 * flag itself as the decision to be clear should be directly
1308 * based on an allocation request.
1309 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001310 if (cc->direct_compaction)
Mel Gorman62997022012-10-08 16:32:47 -07001311 zone->compact_blockskip_flush = true;
1312
Michal Hockoc8f7de02016-05-20 16:56:47 -07001313 if (cc->whole_zone)
1314 return COMPACT_COMPLETE;
1315 else
1316 return COMPACT_PARTIAL_SKIPPED;
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001317 }
Mel Gorman748446b2010-05-24 14:32:27 -07001318
Yaowei Bai21c527a2015-11-05 18:47:20 -08001319 if (is_via_compact_memory(cc->order))
Mel Gorman56de7262010-05-24 14:32:30 -07001320 return COMPACT_CONTINUE;
1321
Michal Hocko3957c772011-06-15 15:08:25 -07001322 /* Compaction run is not finished if the watermark is not met */
Vlastimil Babkaf2b82282016-10-07 16:57:50 -07001323 watermark = zone->watermark[cc->alloc_flags & ALLOC_WMARK_MASK];
Michal Hocko3957c772011-06-15 15:08:25 -07001324
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001325 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1326 cc->alloc_flags))
Michal Hocko3957c772011-06-15 15:08:25 -07001327 return COMPACT_CONTINUE;
1328
Mel Gorman56de7262010-05-24 14:32:30 -07001329 /* Direct compactor: Is a suitable page free? */
Mel Gorman8fb74b92013-01-11 14:32:16 -08001330 for (order = cc->order; order < MAX_ORDER; order++) {
1331 struct free_area *area = &zone->free_area[order];
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001332 bool can_steal;
Mel Gorman56de7262010-05-24 14:32:30 -07001333
Mel Gorman8fb74b92013-01-11 14:32:16 -08001334 /* Job done if page is free of the right migratetype */
David Rientjes6d7ce552014-10-09 15:27:27 -07001335 if (!list_empty(&area->free_list[migratetype]))
Vlastimil Babkacf378312016-10-07 16:57:41 -07001336 return COMPACT_SUCCESS;
Mel Gorman8fb74b92013-01-11 14:32:16 -08001337
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001338#ifdef CONFIG_CMA
1339 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1340 if (migratetype == MIGRATE_MOVABLE &&
1341 !list_empty(&area->free_list[MIGRATE_CMA]))
Vlastimil Babkacf378312016-10-07 16:57:41 -07001342 return COMPACT_SUCCESS;
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001343#endif
1344 /*
1345 * Job done if allocation would steal freepages from
1346 * other migratetype buddy lists.
1347 */
1348 if (find_suitable_fallback(area, order, migratetype,
1349 true, &can_steal) != -1)
Vlastimil Babkacf378312016-10-07 16:57:41 -07001350 return COMPACT_SUCCESS;
Mel Gorman56de7262010-05-24 14:32:30 -07001351 }
1352
Joonsoo Kim837d0262015-02-11 15:27:06 -08001353 return COMPACT_NO_SUITABLE_PAGE;
1354}
1355
Michal Hockoea7ab982016-05-20 16:56:38 -07001356static enum compact_result compact_finished(struct zone *zone,
1357 struct compact_control *cc,
1358 const int migratetype)
Joonsoo Kim837d0262015-02-11 15:27:06 -08001359{
1360 int ret;
1361
1362 ret = __compact_finished(zone, cc, migratetype);
1363 trace_mm_compaction_finished(zone, cc->order, ret);
1364 if (ret == COMPACT_NO_SUITABLE_PAGE)
1365 ret = COMPACT_CONTINUE;
1366
1367 return ret;
Mel Gorman748446b2010-05-24 14:32:27 -07001368}
1369
Mel Gorman3e7d3442011-01-13 15:45:56 -08001370/*
1371 * compaction_suitable: Is this suitable to run compaction on this zone now?
1372 * Returns
1373 * COMPACT_SKIPPED - If there are too few free pages for compaction
Vlastimil Babkacf378312016-10-07 16:57:41 -07001374 * COMPACT_SUCCESS - If the allocation would succeed without compaction
Mel Gorman3e7d3442011-01-13 15:45:56 -08001375 * COMPACT_CONTINUE - If compaction should run now
1376 */
Michal Hockoea7ab982016-05-20 16:56:38 -07001377static enum compact_result __compaction_suitable(struct zone *zone, int order,
Mel Gormanc6038442016-05-19 17:13:38 -07001378 unsigned int alloc_flags,
Michal Hocko86a294a2016-05-20 16:57:12 -07001379 int classzone_idx,
1380 unsigned long wmark_target)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001381{
Mel Gorman3e7d3442011-01-13 15:45:56 -08001382 unsigned long watermark;
1383
Yaowei Bai21c527a2015-11-05 18:47:20 -08001384 if (is_via_compact_memory(order))
Michal Hocko3957c772011-06-15 15:08:25 -07001385 return COMPACT_CONTINUE;
1386
Vlastimil Babkaf2b82282016-10-07 16:57:50 -07001387 watermark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001388 /*
1389 * If watermarks for high-order allocation are already met, there
1390 * should be no need for compaction at all.
1391 */
1392 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1393 alloc_flags))
Vlastimil Babkacf378312016-10-07 16:57:41 -07001394 return COMPACT_SUCCESS;
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001395
Michal Hocko3957c772011-06-15 15:08:25 -07001396 /*
Vlastimil Babka9861a622016-10-07 16:57:53 -07001397 * Watermarks for order-0 must be met for compaction to be able to
Vlastimil Babka984fdba2016-10-07 16:57:57 -07001398 * isolate free pages for migration targets. This means that the
1399 * watermark and alloc_flags have to match, or be more pessimistic than
1400 * the check in __isolate_free_page(). We don't use the direct
1401 * compactor's alloc_flags, as they are not relevant for freepage
1402 * isolation. We however do use the direct compactor's classzone_idx to
1403 * skip over zones where lowmem reserves would prevent allocation even
1404 * if compaction succeeds.
Vlastimil Babka8348faf2016-10-07 16:58:00 -07001405 * For costly orders, we require low watermark instead of min for
1406 * compaction to proceed to increase its chances.
Vlastimil Babka984fdba2016-10-07 16:57:57 -07001407 * ALLOC_CMA is used, as pages in CMA pageblocks are considered
1408 * suitable migration targets
Mel Gorman3e7d3442011-01-13 15:45:56 -08001409 */
Vlastimil Babka8348faf2016-10-07 16:58:00 -07001410 watermark = (order > PAGE_ALLOC_COSTLY_ORDER) ?
1411 low_wmark_pages(zone) : min_wmark_pages(zone);
1412 watermark += compact_gap(order);
Michal Hocko86a294a2016-05-20 16:57:12 -07001413 if (!__zone_watermark_ok(zone, 0, watermark, classzone_idx,
Vlastimil Babka984fdba2016-10-07 16:57:57 -07001414 ALLOC_CMA, wmark_target))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001415 return COMPACT_SKIPPED;
1416
Vlastimil Babkacc5c9f02016-10-07 17:00:43 -07001417 return COMPACT_CONTINUE;
1418}
1419
1420enum compact_result compaction_suitable(struct zone *zone, int order,
1421 unsigned int alloc_flags,
1422 int classzone_idx)
1423{
1424 enum compact_result ret;
1425 int fragindex;
1426
1427 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx,
1428 zone_page_state(zone, NR_FREE_PAGES));
Mel Gorman3e7d3442011-01-13 15:45:56 -08001429 /*
1430 * fragmentation index determines if allocation failures are due to
1431 * low memory or external fragmentation
1432 *
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001433 * index of -1000 would imply allocations might succeed depending on
1434 * watermarks, but we already failed the high-order watermark check
Mel Gorman3e7d3442011-01-13 15:45:56 -08001435 * index towards 0 implies failure is due to lack of memory
1436 * index towards 1000 implies failure is due to fragmentation
1437 *
Vlastimil Babka20311422016-10-07 17:00:46 -07001438 * Only compact if a failure would be due to fragmentation. Also
1439 * ignore fragindex for non-costly orders where the alternative to
1440 * a successful reclaim/compaction is OOM. Fragindex and the
1441 * vm.extfrag_threshold sysctl is meant as a heuristic to prevent
1442 * excessive compaction for costly orders, but it should not be at the
1443 * expense of system stability.
Mel Gorman3e7d3442011-01-13 15:45:56 -08001444 */
Vlastimil Babka20311422016-10-07 17:00:46 -07001445 if (ret == COMPACT_CONTINUE && (order > PAGE_ALLOC_COSTLY_ORDER)) {
Vlastimil Babkacc5c9f02016-10-07 17:00:43 -07001446 fragindex = fragmentation_index(zone, order);
1447 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
1448 ret = COMPACT_NOT_SUITABLE_ZONE;
1449 }
Mel Gorman3e7d3442011-01-13 15:45:56 -08001450
Joonsoo Kim837d0262015-02-11 15:27:06 -08001451 trace_mm_compaction_suitable(zone, order, ret);
1452 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1453 ret = COMPACT_SKIPPED;
1454
1455 return ret;
1456}
1457
Michal Hocko86a294a2016-05-20 16:57:12 -07001458bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
1459 int alloc_flags)
1460{
1461 struct zone *zone;
1462 struct zoneref *z;
1463
1464 /*
1465 * Make sure at least one zone would pass __compaction_suitable if we continue
1466 * retrying the reclaim.
1467 */
1468 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1469 ac->nodemask) {
1470 unsigned long available;
1471 enum compact_result compact_result;
1472
1473 /*
1474 * Do not consider all the reclaimable memory because we do not
1475 * want to trash just for a single high order allocation which
1476 * is even not guaranteed to appear even if __compaction_suitable
1477 * is happy about the watermark check.
1478 */
Mel Gorman5a1c84b2016-07-28 15:47:31 -07001479 available = zone_reclaimable_pages(zone) / order;
Michal Hocko86a294a2016-05-20 16:57:12 -07001480 available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
1481 compact_result = __compaction_suitable(zone, order, alloc_flags,
1482 ac_classzone_idx(ac), available);
Vlastimil Babkacc5c9f02016-10-07 17:00:43 -07001483 if (compact_result != COMPACT_SKIPPED)
Michal Hocko86a294a2016-05-20 16:57:12 -07001484 return true;
1485 }
1486
1487 return false;
1488}
1489
Michal Hockoea7ab982016-05-20 16:56:38 -07001490static enum compact_result compact_zone(struct zone *zone, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -07001491{
Michal Hockoea7ab982016-05-20 16:56:38 -07001492 enum compact_result ret;
Mel Gormanc89511a2012-10-08 16:32:45 -07001493 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -08001494 unsigned long end_pfn = zone_end_pfn(zone);
David Rientjes6d7ce552014-10-09 15:27:27 -07001495 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
David Rientjese0b9dae2014-06-04 16:08:28 -07001496 const bool sync = cc->mode != MIGRATE_ASYNC;
Mel Gorman748446b2010-05-24 14:32:27 -07001497
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001498 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1499 cc->classzone_idx);
Michal Hockoc46649d2016-05-20 16:56:41 -07001500 /* Compaction is likely to fail */
Vlastimil Babkacf378312016-10-07 16:57:41 -07001501 if (ret == COMPACT_SUCCESS || ret == COMPACT_SKIPPED)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001502 return ret;
Michal Hockoc46649d2016-05-20 16:56:41 -07001503
1504 /* huh, compaction_suitable is returning something unexpected */
1505 VM_BUG_ON(ret != COMPACT_CONTINUE);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001506
Mel Gormanc89511a2012-10-08 16:32:45 -07001507 /*
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001508 * Clear pageblock skip if there were failures recently and compaction
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001509 * is about to be retried after being deferred.
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001510 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001511 if (compaction_restarting(zone, cc->order))
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001512 __reset_isolation_suitable(zone);
1513
1514 /*
Mel Gormanc89511a2012-10-08 16:32:45 -07001515 * Setup to move all movable pages to the end of the zone. Used cached
Vlastimil Babka06ed2992016-10-07 16:57:35 -07001516 * information on where the scanners should start (unless we explicitly
1517 * want to compact the whole zone), but check that it is initialised
1518 * by ensuring the values are within zone boundaries.
Mel Gormanc89511a2012-10-08 16:32:45 -07001519 */
Vlastimil Babka06ed2992016-10-07 16:57:35 -07001520 if (cc->whole_zone) {
Mel Gormanc89511a2012-10-08 16:32:45 -07001521 cc->migrate_pfn = start_pfn;
Vlastimil Babka06ed2992016-10-07 16:57:35 -07001522 cc->free_pfn = pageblock_start_pfn(end_pfn - 1);
1523 } else {
1524 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
1525 cc->free_pfn = zone->compact_cached_free_pfn;
1526 if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) {
1527 cc->free_pfn = pageblock_start_pfn(end_pfn - 1);
1528 zone->compact_cached_free_pfn = cc->free_pfn;
1529 }
1530 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) {
1531 cc->migrate_pfn = start_pfn;
1532 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1533 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
1534 }
Michal Hockoc8f7de02016-05-20 16:56:47 -07001535
Vlastimil Babka06ed2992016-10-07 16:57:35 -07001536 if (cc->migrate_pfn == start_pfn)
1537 cc->whole_zone = true;
1538 }
Michal Hockoc8f7de02016-05-20 16:56:47 -07001539
Joonsoo Kim1a167182015-09-08 15:03:59 -07001540 cc->last_migrated_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -07001541
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001542 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1543 cc->free_pfn, end_pfn, sync);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001544
Mel Gorman748446b2010-05-24 14:32:27 -07001545 migrate_prep_local();
1546
David Rientjes6d7ce552014-10-09 15:27:27 -07001547 while ((ret = compact_finished(zone, cc, migratetype)) ==
1548 COMPACT_CONTINUE) {
Minchan Kim9d502c12011-03-22 16:30:39 -07001549 int err;
Mel Gorman748446b2010-05-24 14:32:27 -07001550
Mel Gormanf9e35b32011-06-15 15:08:52 -07001551 switch (isolate_migratepages(zone, cc)) {
1552 case ISOLATE_ABORT:
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001553 ret = COMPACT_CONTENDED;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001554 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001555 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001556 goto out;
1557 case ISOLATE_NONE:
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001558 /*
1559 * We haven't isolated and migrated anything, but
1560 * there might still be unflushed migrations from
1561 * previous cc->order aligned block.
1562 */
1563 goto check_drain;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001564 case ISOLATE_SUCCESS:
1565 ;
1566 }
Mel Gorman748446b2010-05-24 14:32:27 -07001567
David Rientjesd53aea32014-06-04 16:08:26 -07001568 err = migrate_pages(&cc->migratepages, compaction_alloc,
David Rientjese0b9dae2014-06-04 16:08:28 -07001569 compaction_free, (unsigned long)cc, cc->mode,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001570 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001571
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001572 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1573 &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001574
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001575 /* All pages were either migrated or will be released */
1576 cc->nr_migratepages = 0;
Minchan Kim9d502c12011-03-22 16:30:39 -07001577 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001578 putback_movable_pages(&cc->migratepages);
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001579 /*
1580 * migrate_pages() may return -ENOMEM when scanners meet
1581 * and we want compact_finished() to detect it
1582 */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001583 if (err == -ENOMEM && !compact_scanners_met(cc)) {
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001584 ret = COMPACT_CONTENDED;
David Rientjes4bf2bba2012-07-11 14:02:13 -07001585 goto out;
1586 }
Vlastimil Babkafdd048e2016-05-19 17:11:55 -07001587 /*
1588 * We failed to migrate at least one page in the current
1589 * order-aligned block, so skip the rest of it.
1590 */
1591 if (cc->direct_compaction &&
1592 (cc->mode == MIGRATE_ASYNC)) {
1593 cc->migrate_pfn = block_end_pfn(
1594 cc->migrate_pfn - 1, cc->order);
1595 /* Draining pcplists is useless in this case */
1596 cc->last_migrated_pfn = 0;
1597
1598 }
Mel Gorman748446b2010-05-24 14:32:27 -07001599 }
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001600
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001601check_drain:
1602 /*
1603 * Has the migration scanner moved away from the previous
1604 * cc->order aligned block where we migrated from? If yes,
1605 * flush the pages that were freed, so that they can merge and
1606 * compact_finished() can detect immediately if allocation
1607 * would succeed.
1608 */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001609 if (cc->order > 0 && cc->last_migrated_pfn) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001610 int cpu;
1611 unsigned long current_block_start =
Vlastimil Babka06b66402016-05-19 17:11:48 -07001612 block_start_pfn(cc->migrate_pfn, cc->order);
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001613
Joonsoo Kim1a167182015-09-08 15:03:59 -07001614 if (cc->last_migrated_pfn < current_block_start) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001615 cpu = get_cpu();
1616 lru_add_drain_cpu(cpu);
1617 drain_local_pages(zone);
1618 put_cpu();
1619 /* No more flushing until we migrate again */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001620 cc->last_migrated_pfn = 0;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001621 }
1622 }
1623
Mel Gorman748446b2010-05-24 14:32:27 -07001624 }
1625
Mel Gormanf9e35b32011-06-15 15:08:52 -07001626out:
Vlastimil Babka6bace092014-12-10 15:43:31 -08001627 /*
1628 * Release free pages and update where the free scanner should restart,
1629 * so we don't leave any returned pages behind in the next attempt.
1630 */
1631 if (cc->nr_freepages > 0) {
1632 unsigned long free_pfn = release_freepages(&cc->freepages);
1633
1634 cc->nr_freepages = 0;
1635 VM_BUG_ON(free_pfn == 0);
1636 /* The cached pfn is always the first in a pageblock */
Vlastimil Babka06b66402016-05-19 17:11:48 -07001637 free_pfn = pageblock_start_pfn(free_pfn);
Vlastimil Babka6bace092014-12-10 15:43:31 -08001638 /*
1639 * Only go back, not forward. The cached pfn might have been
1640 * already reset to zone end in compact_finished()
1641 */
1642 if (free_pfn > zone->compact_cached_free_pfn)
1643 zone->compact_cached_free_pfn = free_pfn;
1644 }
Mel Gorman748446b2010-05-24 14:32:27 -07001645
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001646 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1647 cc->free_pfn, end_pfn, sync, ret);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001648
Mel Gorman748446b2010-05-24 14:32:27 -07001649 return ret;
1650}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001651
Michal Hockoea7ab982016-05-20 16:56:38 -07001652static enum compact_result compact_zone_order(struct zone *zone, int order,
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001653 gfp_t gfp_mask, enum compact_priority prio,
Mel Gormanc6038442016-05-19 17:13:38 -07001654 unsigned int alloc_flags, int classzone_idx)
Mel Gorman56de7262010-05-24 14:32:30 -07001655{
Michal Hockoea7ab982016-05-20 16:56:38 -07001656 enum compact_result ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001657 struct compact_control cc = {
1658 .nr_freepages = 0,
1659 .nr_migratepages = 0,
1660 .order = order,
David Rientjes6d7ce552014-10-09 15:27:27 -07001661 .gfp_mask = gfp_mask,
Mel Gorman56de7262010-05-24 14:32:30 -07001662 .zone = zone,
Vlastimil Babkaa5508cd2016-07-28 15:49:28 -07001663 .mode = (prio == COMPACT_PRIO_ASYNC) ?
1664 MIGRATE_ASYNC : MIGRATE_SYNC_LIGHT,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001665 .alloc_flags = alloc_flags,
1666 .classzone_idx = classzone_idx,
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001667 .direct_compaction = true,
Vlastimil Babkaa8e025e2016-10-07 16:57:47 -07001668 .whole_zone = (prio == MIN_COMPACT_PRIORITY),
Vlastimil Babka9f7e3382016-10-07 17:00:37 -07001669 .ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY),
1670 .ignore_block_suitable = (prio == MIN_COMPACT_PRIORITY)
Mel Gorman56de7262010-05-24 14:32:30 -07001671 };
1672 INIT_LIST_HEAD(&cc.freepages);
1673 INIT_LIST_HEAD(&cc.migratepages);
1674
Shaohua Lie64c5232012-10-08 16:32:27 -07001675 ret = compact_zone(zone, &cc);
1676
1677 VM_BUG_ON(!list_empty(&cc.freepages));
1678 VM_BUG_ON(!list_empty(&cc.migratepages));
1679
Shaohua Lie64c5232012-10-08 16:32:27 -07001680 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001681}
1682
Mel Gorman5e771902010-05-24 14:32:31 -07001683int sysctl_extfrag_threshold = 500;
1684
Mel Gorman56de7262010-05-24 14:32:30 -07001685/**
1686 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
Mel Gorman56de7262010-05-24 14:32:30 -07001687 * @gfp_mask: The GFP mask of the current allocation
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001688 * @order: The order of the current allocation
1689 * @alloc_flags: The allocation flags of the current allocation
1690 * @ac: The context of current allocation
David Rientjese0b9dae2014-06-04 16:08:28 -07001691 * @mode: The migration mode for async, sync light, or sync migration
Mel Gorman56de7262010-05-24 14:32:30 -07001692 *
1693 * This is the main entry point for direct page compaction.
1694 */
Michal Hockoea7ab982016-05-20 16:56:38 -07001695enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
Mel Gormanc6038442016-05-19 17:13:38 -07001696 unsigned int alloc_flags, const struct alloc_context *ac,
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001697 enum compact_priority prio)
Mel Gorman56de7262010-05-24 14:32:30 -07001698{
Mel Gorman56de7262010-05-24 14:32:30 -07001699 int may_enter_fs = gfp_mask & __GFP_FS;
1700 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001701 struct zoneref *z;
1702 struct zone *zone;
Michal Hocko1d4746d2016-05-20 16:56:44 -07001703 enum compact_result rc = COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001704
Mel Gorman4ffb6332012-10-08 16:29:09 -07001705 /* Check if the GFP flags allow compaction */
Ganesh Mahendranb2b331f2016-07-28 15:45:13 -07001706 if (!may_enter_fs || !may_perform_io)
Vlastimil Babka53853e22014-10-09 15:27:02 -07001707 return COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001708
Vlastimil Babkaa5508cd2016-07-28 15:49:28 -07001709 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio);
Joonsoo Kim837d0262015-02-11 15:27:06 -08001710
Mel Gorman56de7262010-05-24 14:32:30 -07001711 /* Compact each zone in the list */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001712 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1713 ac->nodemask) {
Michal Hockoea7ab982016-05-20 16:56:38 -07001714 enum compact_result status;
Mel Gorman56de7262010-05-24 14:32:30 -07001715
Vlastimil Babkaa8e025e2016-10-07 16:57:47 -07001716 if (prio > MIN_COMPACT_PRIORITY
1717 && compaction_deferred(zone, order)) {
Michal Hocko1d4746d2016-05-20 16:56:44 -07001718 rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);
Vlastimil Babka53853e22014-10-09 15:27:02 -07001719 continue;
Michal Hocko1d4746d2016-05-20 16:56:44 -07001720 }
Vlastimil Babka53853e22014-10-09 15:27:02 -07001721
Vlastimil Babkaa5508cd2016-07-28 15:49:28 -07001722 status = compact_zone_order(zone, order, gfp_mask, prio,
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001723 alloc_flags, ac_classzone_idx(ac));
Mel Gorman56de7262010-05-24 14:32:30 -07001724 rc = max(status, rc);
1725
Vlastimil Babka7ceb0092016-10-07 16:57:44 -07001726 /* The allocation should succeed, stop compacting */
1727 if (status == COMPACT_SUCCESS) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001728 /*
1729 * We think the allocation will succeed in this zone,
1730 * but it is not certain, hence the false. The caller
1731 * will repeat this with true if allocation indeed
1732 * succeeds in this zone.
1733 */
1734 compaction_defer_reset(zone, order, false);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001735
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001736 break;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001737 }
1738
Vlastimil Babkaa5508cd2016-07-28 15:49:28 -07001739 if (prio != COMPACT_PRIO_ASYNC && (status == COMPACT_COMPLETE ||
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001740 status == COMPACT_PARTIAL_SKIPPED))
Vlastimil Babka53853e22014-10-09 15:27:02 -07001741 /*
1742 * We think that allocation won't succeed in this zone
1743 * so we defer compaction there. If it ends up
1744 * succeeding after all, it will be reset.
1745 */
1746 defer_compaction(zone, order);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001747
1748 /*
1749 * We might have stopped compacting due to need_resched() in
1750 * async compaction, or due to a fatal signal detected. In that
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001751 * case do not try further zones
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001752 */
Vlastimil Babkac3486f52016-07-28 15:49:30 -07001753 if ((prio == COMPACT_PRIO_ASYNC && need_resched())
1754 || fatal_signal_pending(current))
1755 break;
Mel Gorman56de7262010-05-24 14:32:30 -07001756 }
1757
1758 return rc;
1759}
1760
1761
Mel Gorman76ab0f52010-05-24 14:32:28 -07001762/* Compact all zones within a node */
Andrew Morton7103f162013-02-22 16:32:33 -08001763static void compact_node(int nid)
Rik van Riel7be62de2012-03-21 16:33:52 -07001764{
Vlastimil Babka791cae92016-10-07 16:57:38 -07001765 pg_data_t *pgdat = NODE_DATA(nid);
1766 int zoneid;
1767 struct zone *zone;
Rik van Riel7be62de2012-03-21 16:33:52 -07001768 struct compact_control cc = {
1769 .order = -1,
David Rientjese0b9dae2014-06-04 16:08:28 -07001770 .mode = MIGRATE_SYNC,
David Rientjes91ca9182014-04-03 14:47:23 -07001771 .ignore_skip_hint = true,
Vlastimil Babka06ed2992016-10-07 16:57:35 -07001772 .whole_zone = true,
Rik van Riel7be62de2012-03-21 16:33:52 -07001773 };
1774
Vlastimil Babka791cae92016-10-07 16:57:38 -07001775
1776 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
1777
1778 zone = &pgdat->node_zones[zoneid];
1779 if (!populated_zone(zone))
1780 continue;
1781
1782 cc.nr_freepages = 0;
1783 cc.nr_migratepages = 0;
1784 cc.zone = zone;
1785 INIT_LIST_HEAD(&cc.freepages);
1786 INIT_LIST_HEAD(&cc.migratepages);
1787
1788 compact_zone(zone, &cc);
1789
1790 VM_BUG_ON(!list_empty(&cc.freepages));
1791 VM_BUG_ON(!list_empty(&cc.migratepages));
1792 }
Rik van Riel7be62de2012-03-21 16:33:52 -07001793}
1794
Mel Gorman76ab0f52010-05-24 14:32:28 -07001795/* Compact all nodes in the system */
Jason Liu7964c062013-01-11 14:31:47 -08001796static void compact_nodes(void)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001797{
1798 int nid;
1799
Hugh Dickins8575ec22012-03-21 16:33:53 -07001800 /* Flush pending updates to the LRU lists */
1801 lru_add_drain_all();
1802
Mel Gorman76ab0f52010-05-24 14:32:28 -07001803 for_each_online_node(nid)
1804 compact_node(nid);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001805}
1806
1807/* The written value is actually unused, all memory is compacted */
1808int sysctl_compact_memory;
1809
Yaowei Baifec4eb22016-01-14 15:20:09 -08001810/*
1811 * This is the entry point for compacting all nodes via
1812 * /proc/sys/vm/compact_memory
1813 */
Mel Gorman76ab0f52010-05-24 14:32:28 -07001814int sysctl_compaction_handler(struct ctl_table *table, int write,
1815 void __user *buffer, size_t *length, loff_t *ppos)
1816{
1817 if (write)
Jason Liu7964c062013-01-11 14:31:47 -08001818 compact_nodes();
Mel Gorman76ab0f52010-05-24 14:32:28 -07001819
1820 return 0;
1821}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001822
Mel Gorman5e771902010-05-24 14:32:31 -07001823int sysctl_extfrag_handler(struct ctl_table *table, int write,
1824 void __user *buffer, size_t *length, loff_t *ppos)
1825{
1826 proc_dointvec_minmax(table, write, buffer, length, ppos);
1827
1828 return 0;
1829}
1830
Mel Gormaned4a6d72010-05-24 14:32:29 -07001831#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Rashika Kheria74e77fb2014-04-03 14:48:01 -07001832static ssize_t sysfs_compact_node(struct device *dev,
Kay Sievers10fbcf42011-12-21 14:48:43 -08001833 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001834 const char *buf, size_t count)
1835{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001836 int nid = dev->id;
1837
1838 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1839 /* Flush pending updates to the LRU lists */
1840 lru_add_drain_all();
1841
1842 compact_node(nid);
1843 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001844
1845 return count;
1846}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001847static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001848
1849int compaction_register_node(struct node *node)
1850{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001851 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001852}
1853
1854void compaction_unregister_node(struct node *node)
1855{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001856 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001857}
1858#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001859
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001860static inline bool kcompactd_work_requested(pg_data_t *pgdat)
1861{
Vlastimil Babka172400c2016-05-05 16:22:32 -07001862 return pgdat->kcompactd_max_order > 0 || kthread_should_stop();
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001863}
1864
1865static bool kcompactd_node_suitable(pg_data_t *pgdat)
1866{
1867 int zoneid;
1868 struct zone *zone;
1869 enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
1870
Chen Feng6cd9dc32016-05-20 16:59:02 -07001871 for (zoneid = 0; zoneid <= classzone_idx; zoneid++) {
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001872 zone = &pgdat->node_zones[zoneid];
1873
1874 if (!populated_zone(zone))
1875 continue;
1876
1877 if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0,
1878 classzone_idx) == COMPACT_CONTINUE)
1879 return true;
1880 }
1881
1882 return false;
1883}
1884
1885static void kcompactd_do_work(pg_data_t *pgdat)
1886{
1887 /*
1888 * With no special task, compact all zones so that a page of requested
1889 * order is allocatable.
1890 */
1891 int zoneid;
1892 struct zone *zone;
1893 struct compact_control cc = {
1894 .order = pgdat->kcompactd_max_order,
1895 .classzone_idx = pgdat->kcompactd_classzone_idx,
1896 .mode = MIGRATE_SYNC_LIGHT,
1897 .ignore_skip_hint = true,
1898
1899 };
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001900 trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
1901 cc.classzone_idx);
1902 count_vm_event(KCOMPACTD_WAKE);
1903
Chen Feng6cd9dc32016-05-20 16:59:02 -07001904 for (zoneid = 0; zoneid <= cc.classzone_idx; zoneid++) {
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001905 int status;
1906
1907 zone = &pgdat->node_zones[zoneid];
1908 if (!populated_zone(zone))
1909 continue;
1910
1911 if (compaction_deferred(zone, cc.order))
1912 continue;
1913
1914 if (compaction_suitable(zone, cc.order, 0, zoneid) !=
1915 COMPACT_CONTINUE)
1916 continue;
1917
1918 cc.nr_freepages = 0;
1919 cc.nr_migratepages = 0;
1920 cc.zone = zone;
1921 INIT_LIST_HEAD(&cc.freepages);
1922 INIT_LIST_HEAD(&cc.migratepages);
1923
Vlastimil Babka172400c2016-05-05 16:22:32 -07001924 if (kthread_should_stop())
1925 return;
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001926 status = compact_zone(zone, &cc);
1927
Vlastimil Babka7ceb0092016-10-07 16:57:44 -07001928 if (status == COMPACT_SUCCESS) {
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001929 compaction_defer_reset(zone, cc.order, false);
Michal Hockoc8f7de02016-05-20 16:56:47 -07001930 } else if (status == COMPACT_PARTIAL_SKIPPED || status == COMPACT_COMPLETE) {
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001931 /*
1932 * We use sync migration mode here, so we defer like
1933 * sync direct compaction does.
1934 */
1935 defer_compaction(zone, cc.order);
1936 }
1937
1938 VM_BUG_ON(!list_empty(&cc.freepages));
1939 VM_BUG_ON(!list_empty(&cc.migratepages));
1940 }
1941
1942 /*
1943 * Regardless of success, we are done until woken up next. But remember
1944 * the requested order/classzone_idx in case it was higher/tighter than
1945 * our current ones
1946 */
1947 if (pgdat->kcompactd_max_order <= cc.order)
1948 pgdat->kcompactd_max_order = 0;
1949 if (pgdat->kcompactd_classzone_idx >= cc.classzone_idx)
1950 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1951}
1952
1953void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
1954{
1955 if (!order)
1956 return;
1957
1958 if (pgdat->kcompactd_max_order < order)
1959 pgdat->kcompactd_max_order = order;
1960
1961 if (pgdat->kcompactd_classzone_idx > classzone_idx)
1962 pgdat->kcompactd_classzone_idx = classzone_idx;
1963
1964 if (!waitqueue_active(&pgdat->kcompactd_wait))
1965 return;
1966
1967 if (!kcompactd_node_suitable(pgdat))
1968 return;
1969
1970 trace_mm_compaction_wakeup_kcompactd(pgdat->node_id, order,
1971 classzone_idx);
1972 wake_up_interruptible(&pgdat->kcompactd_wait);
1973}
1974
1975/*
1976 * The background compaction daemon, started as a kernel thread
1977 * from the init process.
1978 */
1979static int kcompactd(void *p)
1980{
1981 pg_data_t *pgdat = (pg_data_t*)p;
1982 struct task_struct *tsk = current;
1983
1984 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
1985
1986 if (!cpumask_empty(cpumask))
1987 set_cpus_allowed_ptr(tsk, cpumask);
1988
1989 set_freezable();
1990
1991 pgdat->kcompactd_max_order = 0;
1992 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1993
1994 while (!kthread_should_stop()) {
1995 trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
1996 wait_event_freezable(pgdat->kcompactd_wait,
1997 kcompactd_work_requested(pgdat));
1998
1999 kcompactd_do_work(pgdat);
2000 }
2001
2002 return 0;
2003}
2004
2005/*
2006 * This kcompactd start function will be called by init and node-hot-add.
2007 * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added.
2008 */
2009int kcompactd_run(int nid)
2010{
2011 pg_data_t *pgdat = NODE_DATA(nid);
2012 int ret = 0;
2013
2014 if (pgdat->kcompactd)
2015 return 0;
2016
2017 pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
2018 if (IS_ERR(pgdat->kcompactd)) {
2019 pr_err("Failed to start kcompactd on node %d\n", nid);
2020 ret = PTR_ERR(pgdat->kcompactd);
2021 pgdat->kcompactd = NULL;
2022 }
2023 return ret;
2024}
2025
2026/*
2027 * Called by memory hotplug when all memory in a node is offlined. Caller must
2028 * hold mem_hotplug_begin/end().
2029 */
2030void kcompactd_stop(int nid)
2031{
2032 struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd;
2033
2034 if (kcompactd) {
2035 kthread_stop(kcompactd);
2036 NODE_DATA(nid)->kcompactd = NULL;
2037 }
2038}
2039
2040/*
2041 * It's optimal to keep kcompactd on the same CPUs as their memory, but
2042 * not required for correctness. So if the last cpu in a node goes
2043 * away, we get changed to run anywhere: as the first one comes back,
2044 * restore their cpu bindings.
2045 */
2046static int cpu_callback(struct notifier_block *nfb, unsigned long action,
2047 void *hcpu)
2048{
2049 int nid;
2050
2051 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
2052 for_each_node_state(nid, N_MEMORY) {
2053 pg_data_t *pgdat = NODE_DATA(nid);
2054 const struct cpumask *mask;
2055
2056 mask = cpumask_of_node(pgdat->node_id);
2057
2058 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
2059 /* One of our CPUs online: restore mask */
2060 set_cpus_allowed_ptr(pgdat->kcompactd, mask);
2061 }
2062 }
2063 return NOTIFY_OK;
2064}
2065
2066static int __init kcompactd_init(void)
2067{
2068 int nid;
2069
2070 for_each_node_state(nid, N_MEMORY)
2071 kcompactd_run(nid);
2072 hotcpu_notifier(cpu_callback, 0);
2073 return 0;
2074}
2075subsys_initcall(kcompactd_init)
2076
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01002077#endif /* CONFIG_COMPACTION */