On Wed, Mar 19, 2025 at 04:23:45PM +0530, Nilay Shroff wrote:
> The ioc_qos_write method acquires q->elevator_lock to protect
> updates to blk-wbt parameters. Once these updates are complete,
> the lock should be released before returning from ioc_qos_write.
>
> However, in one code path, the release of q->elevator_lock was
> mistakenly omitted, potentially leading to a lock leak. This commit
> fixes the issue by ensuring that q->elevator_lock is properly
> released in all return paths of ioc_qos_write.
>
> Fixes: 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock")
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-lkp/202503171650.cc082b66-lkp@xxxxxxxxx
> Signed-off-by: Nilay Shroff <nilay@xxxxxxxxxxxxx>
> ---
> block/blk-iocost.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/block/blk-iocost.c b/block/blk-iocost.c
> index 38e7bf3c3b4f..56e6fb51316d 100644
> --- a/block/blk-iocost.c
> +++ b/block/blk-iocost.c
> @@ -3348,6 +3348,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
> wbt_enable_default(disk);
>
> blk_mq_unquiesce_queue(disk->queue);
> + mutex_unlock(&disk->queue->elevator_lock);
> blk_mq_unfreeze_queue(disk->queue, memflags);
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Thanks,
Ming
