Merge tag 'v4.4.89' into linux-linaro-lsk-v4.4lsk-v4.4-17.09

 This is the 4.4.89 stable release

1 files changed, 18 insertions, 6 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index badac96cb969..233a2c348a24 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1741,13 +1741,25 @@ static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
 						struct page, lru);
 
 			/*
-			 * It should never happen but changes to locking could
-			 * inadvertently allow a per-cpu drain to add pages
-			 * to MIGRATE_HIGHATOMIC while unreserving so be safe
-			 * and watch for underflows.
+			 * In page freeing path, migratetype change is racy so
+			 * we can counter several free pages in a pageblock
+			 * in this loop althoug we changed the pageblock type
+			 * from highatomic to ac->migratetype. So we should
+			 * adjust the count once.
 			 */
-			zone->nr_reserved_highatomic -= min(pageblock_nr_pages,
-				zone->nr_reserved_highatomic);
+			if (get_pageblock_migratetype(page) ==
+							MIGRATE_HIGHATOMIC) {
+				/*
+				 * It should never happen but changes to
+				 * locking could inadvertently allow a per-cpu
+				 * drain to add pages to MIGRATE_HIGHATOMIC
+				 * while unreserving so be safe and watch for
+				 * underflows.
+				 */
+				zone->nr_reserved_highatomic -= min(
+						pageblock_nr_pages,
+						zone->nr_reserved_highatomic);
+			}
 
 			/*
 			 * Convert to ac->migratetype and avoid the normal