Merge tag 'v2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-linus

1 files changed, 22 insertions, 10 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 17497d0..6771ea7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1841,16 +1841,28 @@ static inline bool should_continue_reclaim(struct zone *zone,
 	if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
 		return false;
 
-	/*
-	 * If we failed to reclaim and have scanned the full list, stop.
-	 * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far
-	 *       faster but obviously would be less likely to succeed
-	 *       allocation. If this is desirable, use GFP_REPEAT to decide
-	 *       if both reclaimed and scanned should be checked or just
-	 *       reclaimed
-	 */
-	if (!nr_reclaimed && !nr_scanned)
-		return false;
+	/* Consider stopping depending on scan and reclaim activity */
+	if (sc->gfp_mask & __GFP_REPEAT) {
+		/*
+		 * For __GFP_REPEAT allocations, stop reclaiming if the
+		 * full LRU list has been scanned and we are still failing
+		 * to reclaim pages. This full LRU scan is potentially
+		 * expensive but a __GFP_REPEAT caller really wants to succeed
+		 */
+		if (!nr_reclaimed && !nr_scanned)
+			return false;
+	} else {
+		/*
+		 * For non-__GFP_REPEAT allocations which can presumably
+		 * fail without consequence, stop if we failed to reclaim
+		 * any pages from the last SWAP_CLUSTER_MAX number of
+		 * pages that were scanned. This will return to the
+		 * caller faster at the risk reclaim/compaction and
+		 * the resulting allocation attempt fails
+		 */
+		if (!nr_reclaimed)
+			return false;
+	}
 
 	/*
 	 * If we have not reclaimed enough pages for compaction and the