crash when connecting to targets using nr_io_queues < num cpus

[Sagi Grimberg]

> Hey all,
>
> I'm testing smaller ioq sets with nvmf/rdma, and I see some issue.  If I connect
> with 2, 4, 6, 8, 10, 16, or 32  for nr_io_queues, everything is happy.  It
> seems, though, if I connect with a value of 12, or 28, or some other non power
> of two, I get intermittent crashes in __blk_mq_get_reserved_tag() at line 337
> when setting up a controller's IO queues.   I'm not sure exactly if this is
> always non power of two, or something else, but it seems to never crash with
> power of two values (could be a coincidence I guess).

I think Ming sent a patch for this some time ago... Not sure what
happened with it though...