On Sun, Jul 14, 2019 at 3:04 PM Wenwen Wang <wang6495@xxxxxxx> wrote:
>
> From: Wenwen Wang <wenwen@xxxxxxxxxx>
>
> In blk_mq_init_allocated_queue(), a kernel buffer is allocated through
> kcalloc_node() to hold hardware dispatch queues in the request queue 'q',
> i.e., 'q->queue_hw_ctx'. Later on, if the blk-mq device has no scheduler
> set, a scheduler will be initialized through elevator_init_mq(). If this
> initialization fails, blk_mq_init_allocated_queue() needs to be terminated
> with an error code returned to indicate this failure. However, the
> allocated buffer is not freed on this execution path, leading to a memory
> leak bug. Moreover, the required cleanup work is also missed on this path.
>
> To fix the above issues, free the allocated buffer and invoke the cleanup
> functions.
>
> Signed-off-by: Wenwen Wang <wenwen@xxxxxxxxxx>
> ---
> block/blk-mq.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index e5ef40c..04fe077 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2845,6 +2845,8 @@ static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
> struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
> struct request_queue *q)
> {
> + int ret = -ENOMEM;
> +
The above isn't necessary because the function always returns
ERR_PTR(-ENOMEM) in case of failure.
> /* mark the queue as mq asap */
> q->mq_ops = set->ops;
>
> @@ -2906,11 +2908,9 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
> blk_mq_map_swqueue(q);
>
> if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
> - int ret;
> -
> ret = elevator_init_mq(q);
> if (ret)
> - return ERR_PTR(ret);
> + goto err_hctxs;
The above change itself is fine.
However, elevator_init_mq() shouldn't return failure since none should
work any time.
That said 'none' should be fallback to in case that default
mq-deadline can't be initialized.
thanks,
Ming Lei
