1 files changed, 17 insertions, 4 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 0eee4020a7be..519d3f00ef9e 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -60,9 +60,14 @@ struct radix_tree_path {
 };
 
 #define RADIX_TREE_INDEX_BITS  (8 /* CHAR_BIT */ * sizeof(unsigned long))
-#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
+                                          RADIX_TREE_MAP_SHIFT))
 
-static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
+/*
+ * The height_to_maxindex array needs to be one deeper than the maximum
+ * path as height 0 holds only 1 entry.
+ */
+static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
 
 /*
  * Radix tree node cache.
@@ -492,7 +497,11 @@ EXPORT_SYMBOL(radix_tree_tag_set);
 void *radix_tree_tag_clear(struct radix_tree_root *root,
                         unsigned long index, unsigned int tag)
 {
-        struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+        /*
+         * The radix tree path needs to be one longer than the maximum path
+         * since the "list" is null terminated.
+         */
+        struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
         struct radix_tree_node *slot = NULL;
         unsigned int height, shift;
 
@@ -934,7 +943,11 @@ static inline void radix_tree_shrink(struct radix_tree_root *root)
  */
 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
 {
-        struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+        /*
+         * The radix tree path needs to be one longer than the maximum path
+         * since the "list" is null terminated.
+         */
+        struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
         struct radix_tree_node *slot = NULL;
         struct radix_tree_node *to_free;
         unsigned int height, shift;