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

Liam R. Howlett
2025-02-11T15:24:26Z

* Wei Yang <richard.weiyang@gmail.com> [250211 02:49]:
> On Mon, Feb 10, 2025 at 09:19:46AM -0500, Liam R. Howlett wrote:
> >* 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().
>
> You prefer a change like this?

Yes.

>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index e64ffa5b9970..79f8632c61a3 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5288,6 +5288,7 @@ static void mt_destroy_walk(struct maple_enode *enode, struct maple_tree *mt,
> struct maple_enode *start;
>
> if (mte_is_leaf(enode)) {
> + mte_set_node_dead(enode);
> node->type = mte_node_type(enode);
> goto free_leaf;
> }
> >
> >> if (mt_in_rcu(mt)) {
> >> mt_destroy_walk(enode, mt, false);
> >> call_rcu(&node->rcu, mt_free_walk);
> >> --
> >> 2.34.1
> >>
>
> --
> Wei Yang
> Help you, Help me