nvme-tcp poll queue crash

[Sagi Grimberg]

>>>> nvme-tcp: kernel NULL pointer dereference, address: 0000000000000034
>>>
>>> Thanks, I couldn't remember this discussion.
>>
>> It just happened late last week, so no worries.
>>
>> I believe we can get rid of bio and bdev dependency, and I am working on
>> detangling how to get the cookie through without these.
> 
> Keith,
> 
> I think we shouldn't have an issue *today* because the only non fs
> I/O that can be polled is the fabrics connect, which has a payload
> and hence has a bio. The minimal change to fix the regression afaict
> is protecting against a polled request submission of a user command
> that doesn't have a payload (just fail it), which again, shouldn't
> happen afaict.

On top of the fix you already suggested of course...