nvme-fabrics: crash at nvme connect-all

[swise@opengridcomputing.com (Steve Wise)]

> -----Original Message-----
> From: Ming Lin [mailto:mlin at kernel.org]
> Sent: Thursday, June 9, 2016 5:26 PM
> To: Steve Wise <swise at opengridcomputing.com>
> Cc: keith busch <keith.busch at intel.com>; ming l <ming.l at ssi.samsung.com>;
> Sagi Grimberg <sagi at grimberg.me>; Marta Rybczynska
> <mrybczyn at kalray.eu>; Jens Axboe <axboe at fb.com>; linux-
> nvme at lists.infradead.org; Christoph Hellwig <hch at infradead.org>; james p
> freyensee <james.p.freyensee at intel.com>; armenx baloyan
> <armenx.baloyan at intel.com>
> Subject: Re: nvme-fabrics: crash at nvme connect-all
> 
> On Thu, Jun 9, 2016 at 2:06 PM, Steve Wise
> <swise@opengridcomputing.com> wrote:
> 
> > Yes, I get the same crash after reproducing it twice.  At least the RIP is
> exactly the same:
> >
> > get_next_timer_interrupt+0x183/0x210
> >
> > The rest of the stack looked a little different but still had tick_nohz stuff in
> it.
> >
> > Does this look correct ("freeing queue 17" twice)?
> >
> > nvmet: creating controller 1 for NQN nqn.2014-
> 08.org.nvmexpress:NVMf:uuid:6e01fbc9-49fb-4998-9522-df85a95f9ff7.
> > nvme nvme1: new ctrl: NQN "nqn.2014-08.org.nvmexpress.discovery",
> addr 10.0.1.14:4420
> > nvmet_rdma: freeing queue 17
> > nvmet: creating controller 1 for NQN nqn.2014-
> 08.org.nvmexpress:NVMf:uuid:6e01fbc9-49fb-4998-9522-df85a95f9ff7.
> > nvme nvme1: creating 16 I/O queues.
> > rdma_rw_init_mrs: failed to allocated 128 MRs
> > failed to init MR pool ret= -12
> > nvmet_rdma: failed to create_qp ret= -12
> > nvmet_rdma: nvmet_rdma_alloc_queue: creating RDMA queue failed (-12).
> > nvme nvme1: Connect rejected, no private data.
> > nvme nvme1: rdma_resolve_addr wait failed (-104).
> > nvme nvme1: failed to initialize i/o queue: -104
> > nvmet_rdma: freeing queue 17
> > general protection fault: 0000 [#1] SMP
> 
> I'll get a Chelsio card to try.
> 
> What's the step to reproduce?

Add the hack into iw_cxgb4 to force alloc_mr failures after 200 allocations (or whatever value you need to make it happen).  Then on the same machine, export a target device, load nvme-rdma and discover/connect to that target device with nvme.  It will crash.

Unfortunately, with the 4.7-rc2 base I'm using, I get no vmcore dump.  I'm not sure why...