Re: [PATCH 1/3] maple_tree: may miss to set node dead on destroy

Liam R. Howlett
2025-02-10T14:19:58Z

* Wei Yang <richard.weiyang@gmail.com> [250207 20:26]:
> On destroy, we should set each node dead. But current code miss this
> when the maple tree has only the root node.
>
> The reason is mt_destroy_walk() leverage mte_destroy_descend() to set
> node dead, but this is skipped since the only root node is a leaf.
>
> This patch fixes this by setting the root dead before mt_destroy_walk().
>
> Fixes: 54a611b60590 ("Maple Tree: add new data structure")
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> CC: Liam R. Howlett <Liam.Howlett@Oracle.com>
> Cc: <stable@vger.kernel.org>
> ---
> lib/maple_tree.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 198c14dd3377..d31f0a2858f7 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5347,6 +5347,8 @@ static inline void mte_destroy_walk(struct maple_enode *enode,
> {
> struct maple_node *node = mte_to_node(enode);
>
> + mte_set_node_dead(enode);
> +

This belongs in mt_destroy_walk().

> if (mt_in_rcu(mt)) {
> mt_destroy_walk(enode, mt, false);
> call_rcu(&node->rcu, mt_free_walk);
> --
> 2.34.1
>