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-rw-r--r--mm/vmscan.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5daf606e0a35..b07c48b09a93 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1867,6 +1867,23 @@ out:
try_to_freeze();
+ /*
+ * Fragmentation may mean that the system cannot be
+ * rebalanced for high-order allocations in all zones.
+ * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
+ * it means the zones have been fully scanned and are still
+ * not balanced. For high-order allocations, there is
+ * little point trying all over again as kswapd may
+ * infinite loop.
+ *
+ * Instead, recheck all watermarks at order-0 as they
+ * are the most important. If watermarks are ok, kswapd will go
+ * back to sleep. High-order users can still perform direct
+ * reclaim if they wish.
+ */
+ if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
+ order = sc.order = 0;
+
goto loop_again;
}