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

Wei Yang
2025-02-12T00:26:45Z

On Tue, Feb 11, 2025 at 10:23:26AM -0500, Liam R. Howlett wrote:
>* 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.
>

Thanks, will adjust in v2.

>>
>> 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

--
Wei Yang
Help you, Help me