Re: [PATCH 1/2] mm/mempolicy: Fix incorrect freeing of wi_kobj

[Joshua Hahn]

On Mon,  2 Jun 2025 09:23:39 -0700 Joshua Hahn <joshua.hahnjy@xxxxxxxxx> wrote:

> We should not free wi_group->wi_kobj here. In the error path of
> add_weighted_interleave_group() where this snippet is called from,
> kobj_{del, put} is immediately called right after this section. Thus,
> it is not only unnecessary but also incorrect to free it here. 
> 
Fixes: e341f9c3c841 ("mm/mempolicy: Weighted Interleave Auto-tuning")
> Signed-off-by: Joshua Hahn <joshua.hahnjy@xxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202506011545.Fduxqxqj-lkp@xxxxxxxxx/
> ---
>  mm/mempolicy.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 72fd72e156b1..3b1dfd08338b 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -3708,15 +3708,13 @@ static void wi_state_free(void)
>  			lockdep_is_held(&wi_state_lock));
>  	if (!old_wi_state) {
>  		mutex_unlock(&wi_state_lock);
> -		goto out;
> +		return;
>  	}
>  
>  	rcu_assign_pointer(wi_state, NULL);
>  	mutex_unlock(&wi_state_lock);
>  	synchronize_rcu();
>  	kfree(old_wi_state);
> -out:
> -	kfree(&wi_group->wi_kobj);
>  }
>  
>  static struct kobj_attribute wi_auto_attr =
> -- 
> 2.47.1