4 files changed, 9 insertions, 5 deletions

diff --git a/include/linux/idr.h b/include/linux/idr.h
index 7d6a6313f0ab..913c335054f0 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -29,7 +29,8 @@ 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_BASE(base) {                                           \
         .idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER),                       \
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index fc55ff31eca7..6c4e2e716dac 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -104,9 +104,10 @@ 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 8e00138d593f..da9e10c827df 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -146,7 +146,7 @@ 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,
@@ -2285,6 +2285,7 @@ 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 e3201ccf54c3..32159c08a52e 100644
--- a/tools/testing/radix-tree/linux/gfp.h
+++ b/tools/testing/radix-tree/linux/gfp.h
@@ -19,6 +19,7 @@
 
 #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)