Merge branch 'sched/urgent' into sched/core

Merge reason: Add fixes before applying dependent patches.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 22 insertions, 10 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 17497d0cd8b9..6771ea70bfe7 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