nvme: subsystem handle not released on hot removal under raid1 configuration and multipath enabled

[Keith Busch]

On Mon, Nov 16, 2020 at 04:06:54PM -0800, Rajashekar, Revanth wrote:
> I guess this is because the md-raid1 driver is still holding a reference to the nvme driver (kref count is 2 in the nvme removal path).
> Is this a bug in nvme multipath? Because it works fine with multipath off.
> Please let me know if more information is required :)

Correct, the md raid is holding a reference. It's not really a bug, but
others have commented that this behavior isn't necessarily desirable.

I posted an RFC about this issue here:

  http://lists.infradead.org/pipermail/linux-nvme/2020-September/019873.html

The discussion evolved a bit since then, but hasn't had much activity
recently. I'm hoping to get back on that conversation soon.