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

[Wei Yang]

On Tue, Feb 11, 2025 at 10:23:26AM -0500, Liam R. Howlett wrote:
>* Wei Yang <richard.weiyang at gmail.com> [250211 02:49]:
>> On Mon, Feb 10, 2025 at 09:19:46AM -0500, Liam R. Howlett wrote:
>> >* Wei Yang <richard.weiyang at 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 at gmail.com>
>> >> CC: Liam R. Howlett <Liam.Howlett at Oracle.com>
>> >> Cc: <stable at 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