[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>

2 files changed, 7 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cc6483047567..f7ea020c23ea 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -633,7 +633,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 #ifdef CONFIG_NUMA
 /*
  * Called from the slab reaper to drain pagesets on a particular node that
- * belong to the currently executing processor.
+ * belongs to the currently executing processor.
  * Note that this function must be called with the thread pinned to
  * a single processor.
  */
@@ -647,6 +647,9 @@ void drain_node_pages(int nodeid)
                 struct zone *zone = NODE_DATA(nodeid)->node_zones + z;
                 struct per_cpu_pageset *pset;
 
+                if (!populated_zone(zone))
+                        continue;
+
                 pset = zone_pcp(zone, smp_processor_id());
                 for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
                         struct per_cpu_pages *pcp;
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++)