[PATCH] mm: do not check unpopulated zones for draining and counter updates

If a zone is unpopulated then we do not need to check for pages that are to
be drained and also not for vm counters that may need to be updated.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 04a9093f649e..968c0072e19a 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -321,6 +321,9 @@ void refresh_cpu_vm_stats(int cpu)
         for_each_zone(zone) {
                 struct per_cpu_pageset *pcp;
 
+                if (!populated_zone(zone))
+                        continue;
+
                 pcp = zone_pcp(zone, cpu);
 
                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)