[PATCH V5 0/9] nvme: pci: fix & improve timeout handling

[keith.busch@linux.intel.com (Keith Busch)]

Hi Ming,

On Sat, May 12, 2018@08:21:22AM +0800, Ming Lei wrote:
> > [  760.679960] nvme nvme1: controller is down; will reset: CSTS=0xffffffff, PCI_STATUS=0xffff
> > [  760.701468] nvme nvme1: EH 0: after shutdown, top eh: 1
> > [  760.727099] pci_raw_set_power_state: 62 callbacks suppressed
> > [  760.727103] nvme 0000:86:00.0: Refused to change power state, currently in D3
> 
> EH may not cover this kind of failure, so it fails in the 1st try.

Indeed, the test is simulating a permanently broken link, so recovery is
not expected. A success in this case is just completing driver
unbinding.
 
> > [  760.727483] nvme nvme1: EH 0: state 4, eh_done -19, top eh 1
> > [  760.727485] nvme nvme1: EH 0: after recovery -19
> > [  760.727488] nvme nvme1: EH: fail controller
> 
> The above issue(hang in nvme_remove()) is still an old issue, which
> is because queues are kept as quiesce during remove, so could you
> please test the following change?
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 1dec353388be..c78e5a0cde06 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3254,6 +3254,11 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
>          */
>         if (ctrl->state == NVME_CTRL_DEAD)
>                 nvme_kill_queues(ctrl);
> +       else {
> +               if (ctrl->admin_q)
> +                       blk_mq_unquiesce_queue(ctrl->admin_q);
> +               nvme_start_queues(ctrl);
> +       }
> 
>         down_write(&ctrl->namespaces_rwsem);
>         list_splice_init(&ctrl->namespaces, &ns_list);

The above won't actually do anything here since the broken link puts the
controller in the DEAD state, so we've killed the queues which also
unquiesces them.

> BTW, in my environment, it is hard to trigger this failure, so not see
> this issue, but I did verify the nested EH which can recover from error
> in reset.

It's actually pretty easy to trigger this one. I just modify block/019 to
remove the check for a hotplug slot then run it on a block device that's
not hot-pluggable.