mm/vmstat: make node_page_state() handles all zones by itself

node_page_state() manually adds statistics per each zone and returns
total value for all zones.  Whenever we add a new zone, we need to
consider this function and it's really troublesome.  Make it handle all
zones by itself.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmstat.c

@@ -600,19 +600,13 @@ void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 unsigned long node_page_state(int node, enum zone_stat_item item)
 {
 	struct zone *zones = NODE_DATA(node)->node_zones;
+	int i;
+	unsigned long count = 0;
 
-	return
-#ifdef CONFIG_ZONE_DMA
-		zone_page_state(&zones[ZONE_DMA], item) +
-#endif
-#ifdef CONFIG_ZONE_DMA32
-		zone_page_state(&zones[ZONE_DMA32], item) +
-#endif
-#ifdef CONFIG_HIGHMEM
-		zone_page_state(&zones[ZONE_HIGHMEM], item) +
-#endif
-		zone_page_state(&zones[ZONE_NORMAL], item) +
-		zone_page_state(&zones[ZONE_MOVABLE], item);
+	for (i = 0; i < MAX_NR_ZONES; i++)
+		count += zone_page_state(zones + i, item);
+
+	return count;
 }
 
 #endif