Unexpected issues with 2 NVME initiators using the same target

[Sagi Grimberg]

Hey Joseph,

> Hey folks.  Apologies if this message comes through twice, but when I originally sent it the list flagged it as too large due to the dmesg log attachments, and then a coworker just told me they never saw it, so I don't think it made it through on the first attempt.
>
> Please see last note above and dmesg example attached - after more extensive testing with Max's patch we are still able to produce cqe dump errors (at a much lower frequency) as well as a new failure mode involving a crash dump.
>

This is a different issue AFAICT,

Looks like nvmet_sq_destroy() is stuck waiting for
the final reference to drop (which seems to never happen).

I'm trying to look for a code path where this may happen.
Can jyou tell if the backend block device completed all of
its I/O when this happens (can check for active tags in debugfs).