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authorNick Piggin <npiggin@kernel.dk>2012-05-29 15:07:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-29 16:22:33 -0700
commit5536805292e64393f57054de66578f17eb1ea994 (patch)
treed7c283b123fd1fa0a944b500aba31f01207a98fd /lib
parentfd0a37355c4d39affa39d5cd75168fb94b292318 (diff)
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>
Diffstat (limited to 'lib')
-rw-r--r--lib/radix-tree.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 86516f5588e..d7c878cc006 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -73,11 +73,24 @@ static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
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, };