[External] : Re: way to unbind a bad nvme device/controller without powering off system

[Keith Busch]

On Mon, Oct 24, 2022 at 08:26:54PM -0600, Keith Busch wrote:
> On Mon, Oct 24, 2022 at 08:02:33PM -0400, James Puthukattukaran wrote:
> > On 10/24/22 18:36, Keith Busch wrote:
> > 
> > > 
> > > Generally, the default timeout is really long. If you have a broken
> > > controller, it could take several minutes before the driver unblocks
> > > forward progress to unbind.
> > One concern is that the reset controller flow attempts to reinitialze the controller and this will cause problems if the controller is bad. Would it make sense to have a sysfs "remove_controller" interface that simply goes through and does a nvme_dev_disable() with the assumption that the controller is dead? Will the nvme_kill_queues() in nvme_dev_disadble() unwedge any potential nvme reset thread that is blocked and thus allow the nvme_remove() flow to complete?
> > thanks
> 
> In your log snippet, there's this line:
> 
>   kernel:warning: [10416608.580157] nvme nvme3: I/O 209 QID 1 timeout, disable controller
> 
> The next action the driver takes after logging that is to drain any
> outstanding IO through a forced reset, and all subsequent tasks *should*
> be unblocked after that completes to allow the unbinding, so I don't
> think adding any new sysfs knobs is going to help if it's not already
> succeeding.
> 
> The only other thing that looks odd is that one of your stuck tasks is a
> user passthrough command, but that should have also been cleared out by
> the reset. Do you know what command that process is sending? I'll need
> to double check your kernel version to see if there's anything missing
> in that driver to ensure the unbinding succeeds. 

I think there could be a mismatched queue quiesce state happening, but
there's some fixes for this in later kernels. Could you possibly try
something newer, like 6.0-stable, as an experiment?