mm: introduce for_each_populated_zone() macro

Impact: cleanup

In almost cases, for_each_zone() is used with populated_zone().  It's
because almost function doesn't need memoryless node information.
Therefore, for_each_populated_zone() can help to make code simplify.

This patch has no functional change.

[akpm@linux-foundation.org: small cleanup]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 9 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 8cd81ea1ddc1..9826766f1274 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -135,11 +135,7 @@ static void refresh_zone_stat_thresholds(void)
         int cpu;
         int threshold;
 
-        for_each_zone(zone) {
-
-                if (!zone->present_pages)
-                        continue;
-
+        for_each_populated_zone(zone) {
                 threshold = calculate_threshold(zone);
 
                 for_each_online_cpu(cpu)
@@ -301,12 +297,9 @@ void refresh_cpu_vm_stats(int cpu)
         int i;
         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 
-        for_each_zone(zone) {
+        for_each_populated_zone(zone) {
                 struct per_cpu_pageset *p;
 
-                if (!populated_zone(zone))
-                        continue;
-
                 p = zone_pcp(zone, cpu);
 
                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)