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-rw-r--r--mm/compaction.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 018f08da99a2..7077b81a4893 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -898,6 +898,16 @@ static bool suitable_migration_target(struct page *page)
 }
 
 /*
+ * Test whether the free scanner has reached the same or lower pageblock than
+ * the migration scanner, and compaction should thus terminate.
+ */
+static inline bool compact_scanners_met(struct compact_control *cc)
+{
+	return (cc->free_pfn >> pageblock_order)
+		<= (cc->migrate_pfn >> pageblock_order);
+}
+
+/*
  * Based on information in the current compact_control, find blocks
  * suitable for isolating free pages from and then isolate them.
  */
@@ -1127,12 +1137,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
 	}
 
 	acct_isolated(zone, cc);
-	/*
-	 * Record where migration scanner will be restarted. If we end up in
-	 * the same pageblock as the free scanner, make the scanners fully
-	 * meet so that compact_finished() terminates compaction.
-	 */
-	cc->migrate_pfn = (end_pfn <= cc->free_pfn) ? low_pfn : cc->free_pfn;
+	/* Record where migration scanner will be restarted. */
+	cc->migrate_pfn = low_pfn;
 
 	return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
 }
@@ -1147,7 +1153,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc,
 		return COMPACT_PARTIAL;
 
 	/* Compaction run completes if the migrate and free scanner meet */
-	if (cc->free_pfn <= cc->migrate_pfn) {
+	if (compact_scanners_met(cc)) {
 		/* Let the next compaction start anew. */
 		zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
 		zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
@@ -1376,7 +1382,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 			 * migrate_pages() may return -ENOMEM when scanners meet
 			 * and we want compact_finished() to detect it
 			 */
-			if (err == -ENOMEM && cc->free_pfn > cc->migrate_pfn) {
+			if (err == -ENOMEM && !compact_scanners_met(cc)) {
 				ret = COMPACT_PARTIAL;
 				goto out;
 			}