From: Song Liu <song@kernel.org>
To: Marc Smith <msmith626@gmail.com>, Yu Kuai <yukuai1@huaweicloud.com>
Cc: Guoqing Jiang <guoqing.jiang@linux.dev>,
Donald Buczek <buczek@molgen.mpg.de>,
linux-raid@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
it+raid@molgen.mpg.de
Subject: Re: md_raid: mdX_raid6 looping after sync_action "check" to "idle" transition
Date: Tue, 28 Mar 2023 17:01:09 -0700 [thread overview]
Message-ID: <CAPhsuW6R11y6vETeZ4vmFGmV6DRrj2gwhp1-Nm+csvtHb2nQYg@mail.gmail.com> (raw)
In-Reply-To: <CAH6h+hcWfXNpC1Mro3zfzQc8tK142vuaOMELLJL7mg_G+o0fXw@mail.gmail.com>
On Thu, Mar 16, 2023 at 8:25 AM Marc Smith <msmith626@gmail.com> wrote:
>
> On Tue, Mar 14, 2023 at 10:45 AM Marc Smith <msmith626@gmail.com> wrote:
> >
> > On Tue, Mar 14, 2023 at 9:55 AM Guoqing Jiang <guoqing.jiang@linux.dev> wrote:
> > >
> > >
> > >
> > > On 3/14/23 21:25, Marc Smith wrote:
> > > > On Mon, Feb 8, 2021 at 7:49 PM Guoqing Jiang
> > > > <guoqing.jiang@cloud.ionos.com> wrote:
> > > >> Hi Donald,
> > > >>
> > > >> On 2/8/21 19:41, Donald Buczek wrote:
> > > >>> Dear Guoqing,
> > > >>>
> > > >>> On 08.02.21 15:53, Guoqing Jiang wrote:
> > > >>>>
> > > >>>> On 2/8/21 12:38, Donald Buczek wrote:
> > > >>>>>> 5. maybe don't hold reconfig_mutex when try to unregister
> > > >>>>>> sync_thread, like this.
> > > >>>>>>
> > > >>>>>> /* resync has finished, collect result */
> > > >>>>>> mddev_unlock(mddev);
> > > >>>>>> md_unregister_thread(&mddev->sync_thread);
> > > >>>>>> mddev_lock(mddev);
> > > >>>>> As above: While we wait for the sync thread to terminate, wouldn't it
> > > >>>>> be a problem, if another user space operation takes the mutex?
> > > >>>> I don't think other places can be blocked while hold mutex, otherwise
> > > >>>> these places can cause potential deadlock. Please try above two lines
> > > >>>> change. And perhaps others have better idea.
> > > >>> Yes, this works. No deadlock after >11000 seconds,
> > > >>>
> > > >>> (Time till deadlock from previous runs/seconds: 1723, 37, 434, 1265,
> > > >>> 3500, 1136, 109, 1892, 1060, 664, 84, 315, 12, 820 )
> > > >> Great. I will send a formal patch with your reported-by and tested-by.
> > > >>
> > > >> Thanks,
> > > >> Guoqing
> > > > I'm still hitting this issue with Linux 5.4.229 -- it looks like 1/2
> > > > of the patches that supposedly resolve this were applied to the stable
> > > > kernels, however, one was omitted due to a regression:
> > > > md: don't unregister sync_thread with reconfig_mutex held (upstream
> > > > commit 8b48ec23cc51a4e7c8dbaef5f34ebe67e1a80934)
> > > >
> > > > I don't see any follow-up on the thread from June 8th 2022 asking for
> > > > this patch to be dropped from all stable kernels since it caused a
> > > > regression.
> > > >
> > > > The patch doesn't appear to be present in the current mainline kernel
> > > > (6.3-rc2) either. So I assume this issue is still present there, or it
> > > > was resolved differently and I just can't find the commit/patch.
> > >
> > > It should be fixed by commit 9dfbdafda3b3"md: unlock mddev before reap
> > > sync_thread in action_store".
> >
> > Okay, let me try applying that patch... it does not appear to be
> > present in my 5.4.229 kernel source. Thanks.
>
> Yes, applying this '9dfbdafda3b3 "md: unlock mddev before reap
> sync_thread in action_store"' patch on top of vanilla 5.4.229 source
> appears to fix the problem for me -- I can't reproduce the issue with
> the script, and it's been running for >24 hours now. (Previously I was
> able to induce the issue within a matter of minutes.)
Hi Marc,
Could you please run your reproducer on the md-tmp branch?
https://git.kernel.org/pub/scm/linux/kernel/git/song/md.git/log/?h=md-tmp
This contains a different version of the fix by Yu Kuai.
Thanks,
Song
next prev parent reply other threads:[~2023-03-29 0:01 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-28 12:25 md_raid: mdX_raid6 looping after sync_action "check" to "idle" transition Donald Buczek
2020-11-30 2:06 ` Guoqing Jiang
2020-12-01 9:29 ` Donald Buczek
2020-12-02 17:28 ` Donald Buczek
2020-12-03 1:55 ` Guoqing Jiang
2020-12-03 11:42 ` Donald Buczek
2020-12-21 12:33 ` Donald Buczek
2021-01-19 11:30 ` Donald Buczek
2021-01-20 16:33 ` Guoqing Jiang
2021-01-23 13:04 ` Donald Buczek
2021-01-25 8:54 ` Donald Buczek
2021-01-25 21:32 ` Donald Buczek
2021-01-26 0:44 ` Guoqing Jiang
2021-01-26 9:50 ` Donald Buczek
2021-01-26 11:14 ` Guoqing Jiang
2021-01-26 12:58 ` Donald Buczek
2021-01-26 14:06 ` Guoqing Jiang
2021-01-26 16:05 ` Donald Buczek
2021-02-02 15:42 ` Guoqing Jiang
2021-02-08 11:38 ` Donald Buczek
2021-02-08 14:53 ` Guoqing Jiang
2021-02-08 18:41 ` Donald Buczek
2021-02-09 0:46 ` Guoqing Jiang
2021-02-09 9:24 ` Donald Buczek
2023-03-14 13:25 ` Marc Smith
2023-03-14 13:55 ` Guoqing Jiang
2023-03-14 14:45 ` Marc Smith
2023-03-16 15:25 ` Marc Smith
2023-03-29 0:01 ` Song Liu [this message]
2023-08-22 21:16 ` Dragan Stancevic
2023-08-23 1:22 ` Yu Kuai
2023-08-23 15:33 ` Dragan Stancevic
2023-08-24 1:18 ` Yu Kuai
2023-08-28 20:32 ` Dragan Stancevic
2023-08-30 1:36 ` Yu Kuai
2023-09-05 3:50 ` Yu Kuai
2023-09-05 13:54 ` Dragan Stancevic
2023-09-13 9:08 ` Donald Buczek
2023-09-13 14:16 ` Dragan Stancevic
2023-09-14 6:03 ` Donald Buczek
2023-09-17 8:55 ` Donald Buczek
2023-09-24 14:35 ` Donald Buczek
2023-09-25 1:11 ` Yu Kuai
2023-09-25 9:11 ` Donald Buczek
2023-09-25 9:32 ` Yu Kuai
2023-03-15 3:02 ` Yu Kuai
2023-03-15 9:30 ` Guoqing Jiang
2023-03-15 9:53 ` Yu Kuai
2023-03-15 7:52 ` Donald Buczek
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