linux-kernel - Re: [PATCH] nvme-rdma: complete requests from ->timeout

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Date:   Tue, 11 Dec 2018 15:16:30 -0800
From:   Jaesoo Lee <jalee@...estorage.com>
To:     nitzanc@...lanox.com
Cc:     sagi@...mberg.me, keith.busch@...el.com, axboe@...com, hch@....de,
        Roland Dreier <roland@...estorage.com>,
        Prabhath Sajeepa <psajeepa@...estorage.com>,
        Ashish Karkare <ashishk@...estorage.com>,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org
Subject: Re: [PATCH] nvme-rdma: complete requests from ->timeout

I cannot reproduce the bug with the patch; in my failure scenarios, it
seems that completing the request on errors in nvme_rdma_send_done
makes __nvme_submit_sync_cmd to be unblocked. Also, I think this is
safe from the double completions.

However, it seems that nvme_rdma_timeout code is still not free from
the double completion problem. So, it looks promising to me if you
could separate out the nvme_rdma_wr_error handling code as a new
patch.
On Tue, Dec 11, 2018 at 1:14 AM Nitzan Carmi <nitzanc@...lanox.com> wrote:
>
> I was just in the middle of sending this to upstream when I saw your
> mail, and thought too that it addresses the same bug, although I see a
> little different call trace than yours.
>
> I would be happy if you can verify that this patch works for you too,
> and we can push it to upstream.
>
> On 11/12/2018 01:40, Jaesoo Lee wrote:
> > It seems that your patch is addressing the same bug. I will see if
> > that works for our failure scenarios.
> >
> > Why don't you make it upstream?
> >
> > On Sun, Dec 9, 2018 at 6:22 AM Nitzan Carmi <nitzanc@...lanox.com> wrote:
> >>
> >> Hi,
> >> We encountered similar issue.
> >> I think that the problem is that error_recovery might not even be
> >> queued, in case we're in DELETING state (or CONNECTING state, for that
> >> matter), because we cannot move from those states to RESETTING.
> >>
> >> We prepared some patches which handle completions in case such scenario
> >> happens (which, in fact, might happen in numerous error flows).
> >>
> >> Does it solve your problem?
> >> Nitzan.
> >>
> >>
> >> On 30/11/2018 03:30, Sagi Grimberg 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?
> >>>
> >>> _______________________________________________
> >>> Linux-nvme mailing list
> >>> Linux-nvme@...ts.infradead.org
> >>> http://lists.infradead.org/mailman/listinfo/linux-nvme

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