page_alloc: break early in check_for_regular_memory()

If there is a zone below ZONE_NORMAL has present_pages, we can set node
state to N_NORMAL_MEMORY, no need to loop to end.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4642,8 +4642,10 @@ static void check_for_regular_memory(pg_data_t *pgdat)
 
 	for (zone_type = 0; zone_type <= ZONE_NORMAL; zone_type++) {
 		struct zone *zone = &pgdat->node_zones[zone_type];
-		if (zone->present_pages)
+		if (zone->present_pages) {
 			node_set_state(zone_to_nid(zone), N_NORMAL_MEMORY);
+			break;
+		}
 	}
 #endif
 }