Re: [PATCH] mm/mempolicy: fix memory leak in weighted_interleave_auto_store()

[Donet Tom <donettom@linux.ibm.com>]

Hi Jackie

On 3/31/26 3:37 PM, Jackie Liu wrote:
> From: Jackie Liu <liuyun01@kylinos.cn>
>
> Add the missing kfree(new_wi_state) when the auto mode is already set
> to the requested value. When a user writes "false" to the auto sysfs
> interface and the current mode is already manual (mode_auto == false),
> the function returns early without freeing new_wi_state allocated at
> the beginning of the function. This can be triggered repeatedly from
> userspace, leaking memory on each write.
>
> Fixes: e341f9c3c841 ("mm/mempolicy: Weighted Interleave Auto-tuning")
> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
> ---
>   mm/mempolicy.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index cf92bd6a8226..9ac74178075b 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -3713,6 +3713,7 @@ static ssize_t weighted_interleave_auto_store(struct kobject *kobj,
>   			goto update_wi_state;
>   		if (input == old_wi_state->mode_auto) {
>   			mutex_unlock(&wi_state_lock);
> +			kfree(new_wi_state);

Good catch—this looks good to me

Reviewed by: Donet Tom <donettom@linux.ibm.com>

>   			return count;
>   		}
>