diff --git a/include/linux/idr.h b/include/linux/idr.h
index 7c3a365f7e12..6972588690a2 100755
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -28,7 +28,8 @@ struct idr {
 #define IDR_FREE	0
 
 /* Set the IDR flag and the IDR_FREE tag */
-#define IDR_RT_MARKER		((__force gfp_t)(3 << __GFP_BITS_SHIFT))
+#define IDR_RT_MARKER	(ROOT_IS_IDR | (__force gfp_t)			\
+					(1 << (ROOT_TAG_SHIFT + IDR_FREE)))
 
 #define IDR_INIT							\
 {									\
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index bd6c60e5230b..3339f07bc863 100755
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -107,9 +107,10 @@ struct radix_tree_node {
 	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
 };
 
-/* The top bits of gfp_mask are used to store the root tags and the IDR flag */
-#define ROOT_IS_IDR	((__force gfp_t)(1 << __GFP_BITS_SHIFT))
-#define ROOT_TAG_SHIFT	(__GFP_BITS_SHIFT + 1)
+/* The IDR tag is stored in the low bits of the GFP flags */
+#define ROOT_IS_IDR	((__force gfp_t)4)
+/* The top bits of gfp_mask are used to store the root tags */
+#define ROOT_TAG_SHIFT	(__GFP_BITS_SHIFT)
 
 struct radix_tree_root {
 	gfp_t			gfp_mask;
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 6f77b53aa93f..a8e546bd1255 100755
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -150,7 +150,7 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
 
 static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
 {
-	return root->gfp_mask & __GFP_BITS_MASK;
+	return root->gfp_mask & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
 }
 
 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
@@ -2336,6 +2336,7 @@ void __init radix_tree_init(void)
 	int ret;
 
 	BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
+	BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
 	radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
 			sizeof(struct radix_tree_node), 0,
 			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
diff --git a/tools/testing/radix-tree/linux/gfp.h b/tools/testing/radix-tree/linux/gfp.h
index e9fff59dfd8a..a72007d9818b 100755
--- a/tools/testing/radix-tree/linux/gfp.h
+++ b/tools/testing/radix-tree/linux/gfp.h
@@ -18,6 +18,7 @@
 
 #define __GFP_RECLAIM	(__GFP_DIRECT_RECLAIM|__GFP_KSWAPD_RECLAIM)
 
+#define GFP_ZONEMASK	0x0fu
 #define GFP_ATOMIC	(__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
 #define GFP_KERNEL	(__GFP_RECLAIM | __GFP_IO | __GFP_FS)
 #define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM)