From mboxrd@z Thu Jan  1 00:00:00 1970
From: swise@opengridcomputing.com (Steve Wise)
Date: Thu, 1 Sep 2016 09:10:56 -0500
Subject: crash when connecting to targets using nr_io_queues < num cpus
In-Reply-To: <6082d700-a45c-b00a-3f09-ba6196cc3e5e@grimberg.me>
References: <011401d203c4$0cdd78c0$26986a40$@opengridcomputing.com>
 <6082d700-a45c-b00a-3f09-ba6196cc3e5e@grimberg.me>
Message-ID: <00ae01d2045a$a8516500$f8f42f00$@opengridcomputing.com>

> 
> > 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...

This?

http://lists.infradead.org/pipermail/linux-nvme/2016-June/004884.html