[PATCH] oom: use unreclaimable info

__alloc_pages currently starts shooting if page reclaim has failed to free up
swap_cluster_max pages in one run through the priorities.  This is not always
a good indicator on its own, so make use of the all_unreclaimable logic as
well: don't consider going OOM until all zones we're interested in are
unreclaimable.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 16180587fd7..ba18d0c36b8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -62,6 +62,8 @@ struct scan_control {
         int swap_cluster_max;
 
         int swappiness;
+
+        int all_unreclaimable;
 };
 
 /*
@@ -925,6 +927,7 @@ static unsigned long shrink_zones(int priority, struct zone **zones,
         unsigned long nr_reclaimed = 0;
         int i;
 
+        sc->all_unreclaimable = 1;
         for (i = 0; zones[i] != NULL; i++) {
                 struct zone *zone = zones[i];
 
@@ -941,6 +944,8 @@ static unsigned long shrink_zones(int priority, struct zone **zones,
                 if (zone->all_unreclaimable && priority != DEF_PRIORITY)
                         continue;       /* Let kswapd poll it */
 
+                sc->all_unreclaimable = 0;
+
                 nr_reclaimed += shrink_zone(priority, zone, sc);
         }
         return nr_reclaimed;
@@ -1021,6 +1026,9 @@ unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
                 if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
                         blk_congestion_wait(WRITE, HZ/10);
         }
+        /* top priority shrink_caches still had more to do? don't OOM, then */
+        if (!sc.all_unreclaimable)
+                ret = 1;
 out:
         for (i = 0; zones[i] != 0; i++) {
                 struct zone *zone = zones[i];