From: David Rientjes <rientjes@google.com>
Date: Wed, 4 Jun 2014 23:08:31 +0000 (-0700)
Subject: mm, compaction: terminate async compaction when rescheduling
X-Git-Tag: v4.9.8~6270^2~16^2~135
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=aeef4b83806f49a0c454b7d4578671b71045bee2;p=platform%2Fkernel%2Flinux-rpi3.git

mm, compaction: terminate async compaction when rescheduling

Async compaction terminates prematurely when need_resched(), see
compact_checklock_irqsave().  This can never trigger, however, if the
cond_resched() in isolate_migratepages_range() always takes care of the
scheduling.

If the cond_resched() actually triggers, then terminate this pageblock
scan for async compaction as well.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/compaction.c b/mm/compaction.c
index 217a6ad..56331f5 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -494,8 +494,13 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
 			return 0;
 	}
 
+	if (cond_resched()) {
+		/* Async terminates prematurely on need_resched() */
+		if (cc->mode == MIGRATE_ASYNC)
+			return 0;
+	}
+
 	/* Time to isolate some pages for migration */
-	cond_resched();
 	for (; low_pfn < end_pfn; low_pfn++) {
 		/* give a chance to irqs before checking need_resched() */
 		if (locked && !(low_pfn % SWAP_CLUSTER_MAX)) {