Merge tag 'powerpc-4.9-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...

[cascardo/linux.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index b918bdb..0409a4a 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1435,9 +1435,14 @@ enum compact_result compaction_suitable(struct zone *zone, int order,
         * index towards 0 implies failure is due to lack of memory
         * index towards 1000 implies failure is due to fragmentation
         *
-        * Only compact if a failure would be due to fragmentation.
+        * Only compact if a failure would be due to fragmentation. Also
+        * ignore fragindex for non-costly orders where the alternative to
+        * a successful reclaim/compaction is OOM. Fragindex and the
+        * vm.extfrag_threshold sysctl is meant as a heuristic to prevent
+        * excessive compaction for costly orders, but it should not be at the
+        * expense of system stability.
         */
-       if (ret == COMPACT_CONTINUE) {
+       if (ret == COMPACT_CONTINUE && (order > PAGE_ALLOC_COSTLY_ORDER)) {
                fragindex = fragmentation_index(zone, order);
                if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
                        ret = COMPACT_NOT_SUITABLE_ZONE;