[PATCH] mm: add populated_zone() helper

There are numerous places we check whether a zone is populated or not.

Provide a helper function to check for populated zones and convert all
checks for zone->present_pages.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 13 insertions, 8 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 8d6caa414c4c..c34f4a2c62f8 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -388,6 +388,11 @@ static inline struct zone *next_zone(struct zone *zone)
 #define for_each_zone(zone) \
         for (zone = pgdat_list->node_zones; zone; zone = next_zone(zone))
 
+static inline int populated_zone(struct zone *zone)
+{
+        return (!!zone->present_pages);
+}
+
 static inline int is_highmem_idx(int idx)
 {
         return (idx == ZONE_HIGHMEM);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b9fd2c238f13..8f3de5af92dd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1358,7 +1358,7 @@ void show_free_areas(void)
                 show_node(zone);
                 printk("%s per-cpu:", zone->name);
 
-                if (!zone->present_pages) {
+                if (!populated_zone(zone)) {
                         printk(" empty\n");
                         continue;
                 } else
@@ -1435,7 +1435,7 @@ void show_free_areas(void)
 
                 show_node(zone);
                 printk("%s: ", zone->name);
-                if (!zone->present_pages) {
+                if (!populated_zone(zone)) {
                         printk("empty\n");
                         continue;
                 }
@@ -2134,7 +2134,7 @@ static int frag_show(struct seq_file *m, void *arg)
         int order;
 
         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
-                if (!zone->present_pages)
+                if (!populated_zone(zone))
                         continue;
 
                 spin_lock_irqsave(&zone->lock, flags);
@@ -2167,7 +2167,7 @@ static int zoneinfo_show(struct seq_file *m, void *arg)
         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
                 int i;
 
-                if (!zone->present_pages)
+                if (!populated_zone(zone))
                         continue;
 
                 spin_lock_irqsave(&zone->lock, flags);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5c8a412b43f4..7681d8ee04fe 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -897,7 +897,7 @@ shrink_caches(struct zone **zones, struct scan_control *sc)
         for (i = 0; zones[i] != NULL; i++) {
                 struct zone *zone = zones[i];
 
-                if (zone->present_pages == 0)
+                if (!populated_zone(zone))
                         continue;
 
                 if (!cpuset_zone_allowed(zone, __GFP_HARDWALL))
@@ -1069,7 +1069,7 @@ loop_again:
                         for (i = pgdat->nr_zones - 1; i >= 0; i--) {
                                 struct zone *zone = pgdat->node_zones + i;
 
-                                if (zone->present_pages == 0)
+                                if (!populated_zone(zone))
                                         continue;
 
                                 if (zone->all_unreclaimable &&
@@ -1106,7 +1106,7 @@ scan:
                         struct zone *zone = pgdat->node_zones + i;
                         int nr_slab;
 
-                        if (zone->present_pages == 0)
+                        if (!populated_zone(zone))
                                 continue;
 
                         if (zone->all_unreclaimable && priority != DEF_PRIORITY)
@@ -1258,7 +1258,7 @@ void wakeup_kswapd(struct zone *zone, int order)
 {
         pg_data_t *pgdat;
 
-        if (zone->present_pages == 0)
+        if (!populated_zone(zone))
                 return;
 
         pgdat = zone->zone_pgdat;