radix-tree: fix preload vector size
We are not preallocating a sufficient number of nodes.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 86516f5..d7c878c 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -73,11 +73,24 @@
static struct kmem_cache *radix_tree_node_cachep;
/*
+ * The radix tree is variable-height, so an insert operation not only has
+ * to build the branch to its corresponding item, it also has to build the
+ * branch to existing items if the size has to be increased (by
+ * radix_tree_extend).
+ *
+ * The worst case is a zero height tree with just a single item at index 0,
+ * and then inserting an item at index ULONG_MAX. This requires 2 new branches
+ * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
+ * Hence:
+ */
+#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
+
+/*
* Per-cpu pool of preloaded nodes
*/
struct radix_tree_preload {
int nr;
- struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
+ struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE];
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };