diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7747ec9de5889f3ee61ebac9386c11bbfc7ba70a..8331e76677c0428e9ad8218ec35de5be2a6bad55 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -855,18 +855,6 @@ static inline int local_memory_node(int node_id) { return node_id; };
  */
 #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 c4cdd39548041f979859b0bdd50a7674bebd18cd..2c74367a8ebae8fdd19f7c211c8b5b5b84d68548 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5926,7 +5926,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	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;
 
 	/*