[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 01:34:38PM -0600, Jonathan Derrick wrote:
> 
> 
> On 4/4/2022 11:02 AM, Keith Busch wrote:
> > On Mon, Apr 04, 2022 at 04:39:06PM +0000, Alan Adamson wrote:
> > > 
> > > [   97.083215] nvme0: Admin Cmd(0x6), I/O Error (sct 0x0 / sc 0x2) MORE DNR
> > > 
> > > An error from the device (status=2/Invalid Field) when an Identify (0x6) command was issued. Prior to the patch,
> > > the nvme driver didn’t display the error.
> > And it's harmless. The driver is querying an optional identification and it's
> > okay if the device doesn't support it, but the driver doesn't know if the
> > device supports until it tries it.
> I've had to field bug reports like this before, where it says error in dmesg
> but is actually harmless.

Even before the kernel message was added, some implementations trigger error
log events, which alerts smartd. :(
 
> Maybe we could suppress the error and add a harmless print?
> Eg, nvme0: blah blah command set not supported

The new print in the completion handler is pretty generic. I don't think it can
readily tell the difference from a harmless error. Maybe pr_err is too high?

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.