On Mon, Dec 13, 2021 at 12:09:07PM +0800, Laibin Qiu wrote:
> Submit_bio
> scsi_remove_device
> sd_remove
> del_gendisk
> blk_unregister_queue
> elv_unregister_queue
> wbt_enable_default
> <= Set rwb->enable_state (ON)
> q_qos_track
> <= rwb->enable_state (ON)
> ^^^^^^ this request will mark WBT_TRACKED without inflight add and will
> lead to drop rqw->inflight to -1 in wbt_done() which will trigger IO hung.
>
> Fix this by judge whether QUEUE_FLAG_REGISTERED is marked to distinguish
> scsi remove scene.
> Fixes: 76a8040817b4b ("blk-wbt: make sure throttle is enabled properly")
> Signed-off-by: Laibin Qiu <qiulaibin@xxxxxxxxxx>
> ---
> block/blk-wbt.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-wbt.c b/block/blk-wbt.c
> index 3ed71b8da887..537f77bb1365 100644
> --- a/block/blk-wbt.c
> +++ b/block/blk-wbt.c
> @@ -637,6 +637,10 @@ void wbt_enable_default(struct request_queue *q)
> {
> struct rq_qos *rqos = wbt_rq_qos(q);
>
> + /* Queue not registered? Maybe shutting down... */
> + if (!blk_queue_registered(q))
> + return;
Wouldn't it make more sense to simply not call wbt_enable_default from
elv_unregister_queue?
