From: Jaesoo Lee <jalee@purestorage.com>
To: sagi@grimberg.me
Cc: keith.busch@intel.com, axboe@fb.com, hch@lst.de,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Prabhath Sajeepa <psajeepa@purestorage.com>,
Roland Dreier <roland@purestorage.com>,
Ashish Karkare <ashishk@purestorage.com>
Subject: Re: [PATCH] nvme-rdma: complete requests from ->timeout
Date: Thu, 6 Dec 2018 16:18:28 -0800 [thread overview]
Message-ID: <CAJX3CthC6KxH7ZtpSzEGGQTVUgKO6UVkjiMMBV6=OG__UVF43Q@mail.gmail.com> (raw)
In-Reply-To: <CAJX3CtiBs6YOjkP5xGb5yPShvOdmhuD7kx-kBAVL7+YsyEGMyw@mail.gmail.com>
Could you please take a look at this bug and code review?
We are seeing more instances of this bug and found that reconnect_work
could hang as well, as can be seen from below stacktrace.
Workqueue: nvme-wq nvme_rdma_reconnect_ctrl_work [nvme_rdma]
Call Trace:
__schedule+0x2ab/0x880
schedule+0x36/0x80
schedule_timeout+0x161/0x300
? __next_timer_interrupt+0xe0/0xe0
io_schedule_timeout+0x1e/0x50
wait_for_completion_io_timeout+0x130/0x1a0
? wake_up_q+0x80/0x80
blk_execute_rq+0x6e/0xa0
__nvme_submit_sync_cmd+0x6e/0xe0
nvmf_connect_admin_queue+0x128/0x190 [nvme_fabrics]
? wait_for_completion_interruptible_timeout+0x157/0x1b0
nvme_rdma_start_queue+0x5e/0x90 [nvme_rdma]
nvme_rdma_setup_ctrl+0x1b4/0x730 [nvme_rdma]
nvme_rdma_reconnect_ctrl_work+0x27/0x70 [nvme_rdma]
process_one_work+0x179/0x390
worker_thread+0x4f/0x3e0
kthread+0x105/0x140
? max_active_store+0x80/0x80
? kthread_bind+0x20/0x20
This bug is produced by setting MTU of RoCE interface to '568' for
test while running I/O traffics.
Thanks,
Jaesoo Lee.
On Thu, Nov 29, 2018 at 5:54 PM Jaesoo Lee <jalee@purestorage.com> wrote:
>
> Not the queue, but the RDMA connections.
>
> Let me describe the scenario.
>
> 1. connected nvme-rdma target with 500 namespaces
> : this will make the nvme_remove_namespaces() took a long time to
> complete and open the window vulnerable to this bug
> 2. host will take below code path for nvme_delete_ctrl_work and send
> normal shutdown in nvme_shutdown_ctrl()
> - nvme_stop_ctrl
> - nvme_stop_keep_alive --> stopped keep alive
> - nvme_remove_namespaces --> took too long time, over 10~15s
> - nvme_rdma_shutdown_ctrl
> - nvme_rdma_teardown_io_queues
> - nvme_shutdown_ctrl
> - nvmf_reg_write32
> -__nvme_submit_sync_cmd --> nvme_delete_ctrl_work blocked here
> - nvme_rdma_teardown_admin_queue
> - nvme_uninit_ctrl
> - nvme_put_ctrl
> 3. the rdma connection is disconnected by the nvme-rdma target
> : in our case, this is triggered by the target side timeout mechanism
> : I did not try, but I think this could happen if we lost the RoCE link, too.
> 4. the shutdown notification command timed out and the work stuck
> while leaving the controller in NVME_CTRL_DELETING state
>
> Thanks,
>
> Jaesoo Lee.
>
>
> On Thu, Nov 29, 2018 at 5:30 PM Sagi Grimberg <sagi@grimberg.me> wrote:
> >
> >
> > > This does not hold at least for NVMe RDMA host driver. An example scenario
> > > is when the RDMA connection is gone while the controller is being deleted.
> > > In this case, the nvmf_reg_write32() for sending shutdown admin command by
> > > the delete_work could be hung forever if the command is not completed by
> > > the timeout handler.
> >
> > If the queue is gone, this means that the queue has already flushed and
> > any commands that were inflight has completed with a flush error
> > completion...
> >
> > Can you describe the scenario that caused this hang? When has the
> > queue became "gone" and when did the shutdown command execute?
next prev parent reply other threads:[~2018-12-07 0:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 23:59 [PATCH] nvme-rdma: complete requests from ->timeout Jaesoo Lee
2018-11-30 1:30 ` Sagi Grimberg
2018-11-30 1:54 ` Jaesoo Lee
2018-12-07 0:18 ` Jaesoo Lee [this message]
2018-12-07 20:05 ` Sagi Grimberg
2018-12-08 2:02 ` Keith Busch
2018-12-08 6:28 ` Jaesoo Lee
2018-12-09 14:22 ` Nitzan Carmi
2018-12-10 23:40 ` Jaesoo Lee
2018-12-11 9:14 ` Nitzan Carmi
2018-12-11 23:16 ` Jaesoo Lee
2018-12-11 23:38 ` Sagi Grimberg
2018-12-12 1:31 ` Jaesoo Lee
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