1 files changed, 34 insertions, 16 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index f94cbc0b99a..d8187f9cabb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -66,24 +66,15 @@ static inline bool isolation_suitable(struct compact_control *cc,
  * should be skipped for page isolation when the migrate and free page scanner
  * meet.
  */
-static void reset_isolation_suitable(struct zone *zone)
+static void __reset_isolation_suitable(struct zone *zone)
 {
 	unsigned long start_pfn = zone->zone_start_pfn;
 	unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
 	unsigned long pfn;
 
-	/*
-	 * Do not reset more than once every five seconds. If allocations are
-	 * failing sufficiently quickly to allow this to happen then continually
-	 * scanning for compaction is not going to help. The choice of five
-	 * seconds is arbitrary but will mitigate excessive scanning.
-	 */
-	if (time_before(jiffies, zone->compact_blockskip_expire))
-		return;
-
 	zone->compact_cached_migrate_pfn = start_pfn;
 	zone->compact_cached_free_pfn = end_pfn;
-	zone->compact_blockskip_expire = jiffies + (HZ * 5);
+	zone->compact_blockskip_flush = false;
 
 	/* Walk the zone and mark every pageblock as suitable for isolation */
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
@@ -102,9 +93,24 @@ static void reset_isolation_suitable(struct zone *zone)
 	}
 }
 
+void reset_isolation_suitable(pg_data_t *pgdat)
+{
+	int zoneid;
+
+	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+		struct zone *zone = &pgdat->node_zones[zoneid];
+		if (!populated_zone(zone))
+			continue;
+
+		/* Only flush if a full compaction finished recently */
+		if (zone->compact_blockskip_flush)
+			__reset_isolation_suitable(zone);
+	}
+}
+
 /*
  * If no pages were isolated then mark this pageblock to be skipped in the
- * future. The information is later cleared by reset_isolation_suitable().
+ * future. The information is later cleared by __reset_isolation_suitable().
  */
 static void update_pageblock_skip(struct compact_control *cc,
 			struct page *page, unsigned long nr_isolated,
@@ -820,7 +826,15 @@ static int compact_finished(struct zone *zone,
 
 	/* Compaction run completes if the migrate and free scanner meet */
 	if (cc->free_pfn <= cc->migrate_pfn) {
-		reset_isolation_suitable(cc->zone);
+		/*
+		 * Mark that the PG_migrate_skip information should be cleared
+		 * by kswapd when it goes to sleep. kswapd does not set the
+		 * flag itself as the decision to be clear should be directly
+		 * based on an allocation request.
+		 */
+		if (!current_is_kswapd())
+			zone->compact_blockskip_flush = true;
+
 		return COMPACT_COMPLETE;
 	}
 
@@ -943,9 +957,13 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 		zone->compact_cached_migrate_pfn = cc->migrate_pfn;
 	}
 
-	/* Clear pageblock skip if there are numerous alloc failures */
-	if (zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT)
-		reset_isolation_suitable(zone);
+	/*
+	 * Clear pageblock skip if there were failures recently and compaction
+	 * is about to be retried after being deferred. kswapd does not do
+	 * this reset as it'll reset the cached information when going to sleep.
+	 */
+	if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
+		__reset_isolation_suitable(zone);
 
 	migrate_prep_local();