diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index bd791e4..67ab5fe 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -490,6 +490,12 @@
 	unsigned long		managed_pages;
 
 	/*
+	 * Number of MIGRATE_RESEVE page block. To maintain for just
+	 * optimization. Protected by zone->lock.
+	 */
+	int			nr_migrate_reserve_block;
+
+	/*
 	 * rarely used fields:
 	 */
 	const char		*name;