[PATCH] radix-tree: Fix private list warnings

Matthew Wilcox
2017-01-12T23:42:16Z

From: Matthew Wilcox <mawilcox@microsoft.com>

The newly introduced warning in radix_tree_free_nodes() was testing the
wrong variable; it should have been 'old' instead of 'node'. Rather
than replace that one instance, I noticed that we can simply put the
WARN_ON_ONCE in radix_tree_node_free() and it will be just as effective.

Fixes: ea07b862ac8e ("mm: workingset: fix use-after-free in shadow node shrinker")
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
lib/radix-tree.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 4a4ed3ee4222..3c4577cabc57 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -449,6 +449,7 @@ static void radix_tree_node_rcu_free(struct rcu_head *head)
static inline void
radix_tree_node_free(struct radix_tree_node *node)
{
+ WARN_ON_ONCE(!list_empty(&node->private_list));
call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
}

@@ -734,7 +735,6 @@ static inline void radix_tree_shrink(struct radix_tree_root *root,
update_node(node, private);
}

- WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node);
}
}
@@ -766,7 +766,6 @@ static void delete_node(struct radix_tree_root *root,
root->rnode = NULL;
}

- WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(node);

node = parent;
@@ -868,7 +867,6 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
struct radix_tree_node *old = child;
offset = child->offset + 1;
child = child->parent;
- WARN_ON_ONCE(!list_empty(&node->private_list));
radix_tree_node_free(old);
if (old == entry_to_node(node))
return;
--
2.11.0.296.g5800ad326.dirty