diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7747ec9..8331e76 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -855,18 +855,6 @@
  */
 #define zone_idx(zone)		((zone) - (zone)->zone_pgdat->node_zones)
 
-#ifdef CONFIG_ZONE_DEVICE
-static inline bool is_dev_zone(const struct zone *zone)
-{
-	return zone_idx(zone) == ZONE_DEVICE;
-}
-#else
-static inline bool is_dev_zone(const struct zone *zone)
-{
-	return false;
-}
-#endif
-
 /*
  * Returns true if a zone has pages managed by the buddy allocator.
  * All the reclaim decisions have to use this function rather than
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c4cdd39..2c74367 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5926,7 +5926,7 @@
 	unsigned long start = jiffies;
 	int nid = pgdat->node_id;
 
-	if (WARN_ON_ONCE(!pgmap || !is_dev_zone(zone)))
+	if (WARN_ON_ONCE(!pgmap || zone_idx(zone) != ZONE_DEVICE))
 		return;
 
 	/*