nvme-tcp: kernel NULL pointer dereference, address: 0000000000000034

[Sagi Grimberg]

>> admin_tagset.nr_maps = 1 (only the default map, no read, no poll)
> 
> Indeed, that would be to easy.
> 
> I've just triggered a crash where we are passing in a non-null bio. Some
> more annotation. This time I am printing from blk_rq_is_poll() and
> we see that that is also the case where we have a valid bio but
> want to use the poll context:

That is not a crash, but a WARN stack dump. It is still unclear to me
how exactly you get to poll for a bio-less request.

See my other reply, While I removed the below warning, and allow
bio-less request polling, I was not able to observe any bio-less
requests actually being polled.