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authorDave Chinner <dchinner@redhat.com>2010-08-23 10:33:19 +1000
committerDave Chinner <david@fromorbit.com>2010-08-23 10:33:19 +1000
commitb6dd08652e2b70e73661c4975ae46398066c06f8 (patch)
treefa70f295a5074627a6b6dba11a8c8cf90d4e4b95 /lib/radix-tree.c
parentda5cabf80e2433131bf0ed8993abc0f7ea618c73 (diff)
downloadlinux-b6dd08652e2b70e73661c4975ae46398066c06f8.tar.gz
radix-tree: clear all tags in radix_tree_node_rcu_free
Commit f446daaea9d4a420d16c606f755f3689dcb2d0ce ("mm: implement writeback livelock avoidance using page tagging") introduced a new radix tree tag, increasing the number of tags in each node from 2 to 3. It did not, however, fix up the code in radix_tree_node_rcu_free() that cleans up after radix_tree_shrink() and hence could leave stray tags set in the new tag array. The result is that the livelock avoidance code added in the the above commit would hit stale tags when doing tag based lookups, resulting in livelocks when trying to traverse the tree. Fix this problem in radix_tree_node_rcu_free() so it doesn't happen again in the future by using a loop to walk all the tags up to RADIX_TREE_MAX_TAGS to clear the stray tags radix_tree_shrink() leaves behind. Signed-off-by: Dave Chinner <dchinner@redhat.com> Acked-by: Nick Piggin <npiggin@kernel.dk> Acked-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'lib/radix-tree.c')
-rw-r--r--lib/radix-tree.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index e907858498a..1014171dd1c 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -174,14 +174,16 @@ static void radix_tree_node_rcu_free(struct rcu_head *head)
{
struct radix_tree_node *node =
container_of(head, struct radix_tree_node, rcu_head);
+ int i;
/*
* must only free zeroed nodes into the slab. radix_tree_shrink
* can leave us with a non-NULL entry in the first slot, so clear
* that here to make sure.
*/
- tag_clear(node, 0, 0);
- tag_clear(node, 1, 0);
+ for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
+ tag_clear(node, i, 0);
+
node->slots[0] = NULL;
node->count = 0;