Re: [PATCH] nvme-pci: not invoke nvme_remove_dead_ctrl when change state fails

From: Keith Busch
Date: Tue Jun 19 2018 - 12:36:50 EST


On Tue, Jun 19, 2018 at 04:30:50PM +0800, Jianchao Wang wrote:
> There is race between nvme_remove and nvme_reset_work that can
> lead to io hang.
>
> nvme_remove nvme_reset_work
> -> change state to DELETING
> -> fail to change state to LIVE
> -> nvme_remove_dead_ctrl
> -> nvme_dev_disable
> -> quiesce request_queue
> -> queue remove_work
> -> cancel_work_sync reset_work
> -> nvme_remove_namespaces
> -> splice ctrl->namespaces
> nvme_remove_dead_ctrl_work
> -> nvme_kill_queues
> -> nvme_ns_remove do nothing
> -> blk_cleanup_queue
> -> blk_freeze_queue
> Finally, the request_queue is quiesced state when wait freeze,
> we will get io hang here.
>
> In fact, when fails to change state in nvme_reset_work, the only
> reason is someone has changed state to DELETING. So it is not
> necessary to invoke nvme_remove_dead_ctrl in that case.
>
> Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>

Good catch. I think the fix should either have the nvme_dev_disable set
shutdown to true to indicate the controller isn't coming back online, or
move the nvme_kill_queues inside nvme_remove_dead_ctrl.