[bug report]nvme0: Admin Cmd(0x6), I/O Error (sct 0x0 / sc 0x2) MORE DNR observed during blktests

[Keith Busch]

On Mon, Apr 04, 2022 at 06:43:01PM -0600, Jonathan Derrick wrote:
> > Or maybe since enough people have been concerned about *this* specific
> > identify, maybe it should be restricted to 2.0 devices where it's mandatory. I
> > was reluctant to do that at first since the initial device I tested was 1.4,
> > but it was a prototype and we should be fine without the non-mdts limits
> > anyway.
> Well I'm not sure about that. I'm not honestly sure what this specific
> identify is, but (I know you know) NVMe being forward compatible allows eg,
> 1.4 compliant devices/targets to support 2.0 features.

The command triggering the error is the NVM CSI Identify Controller (CNS=6),
which provides the recommended limits for commands that don't transfer block
data (write zeroes, verify, dsm, etc..). The driver sets it up in
nvme_init_non_mdts_limits().

Here are two other user reports of this triggering smartd warnings:

 http://lists.infradead.org/pipermail/linux-nvme/2021-July/028009.html
 https://bugzilla.kernel.org/show_bug.cgi?id=215763

The identification only provides recommended limits, so it's not all that bad
if we skip checking it for <2.0 versions that don't require it.