Messages in this thread | | | Subject | Re: md_raid: mdX_raid6 looping after sync_action "check" to "idle" transition | From | Yu Kuai <> | Date | Thu, 24 Aug 2023 09:18:58 +0800 |
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Hi,
在 2023/08/23 23:33, Dragan Stancevic 写道: > Hi Kuai- > > On 8/22/23 20:22, Yu Kuai wrote: >> Hi, >> >> 在 2023/08/23 5:16, Dragan Stancevic 写道: >>> On Tue, 3/28/23 17:01 Song Liu wrote: >>>> On Thu, Mar 16, 2023 at 8:25=E2=80=AFAM Marc Smith >>>> <msmith626@gmail.com> >>>> wr= >>>> ote: >>>> > >>>> > On Tue, Mar 14, 2023 at 10:45=E2=80=AFAM Marc Smith >>>> <msmith626@gmail.com>= >>>> wrote: >>>> > > >>>> > > On Tue, Mar 14, 2023 at 9:55=E2=80=AFAM Guoqing Jiang >>>> <guoqing.jiang@li= >>>> nux.dev> wrote: >>>> > > > >>>> > > > >>>> > > > >>>> > > > On 3/14/23 21:25, Marc Smith wrote: >>>> > > > > On Mon, Feb 8, 2021 at 7:49=E2=80=AFPM 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, >>>> would= >>>> n'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, >>>> othe= >>>> rwise >>>> > > > >>>> 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, 12= >>>> 65, >>>> > > > >>> 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 >>>> sta= >>>> ble >>>> > > > > 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 f= >>>> or >>>> > > > > 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 >>>> kern= >>>> el >>>> > > > > (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 >>>> rea= >>>> p >>>> > > > 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=3Dmd-tmp >>>> >>>> >>>> This contains a different version of the fix by Yu Kuai. >>>> >>>> Thanks, >>>> Song >>>> >>> >>> Hi Song, I can easily reproduce this issue on 5.10.133 and 5.10.53. >>> The change >>> "9dfbdafda3b3 "md: unlock mddev before reap" does not fix the issue >>> for me. >>> >>> But I did pull the changes from the md-tmp branch you are refering: >>> https://git.kernel.org/pub/scm/linux/kernel/git/song/md.git/log/?h=3Dmd-tmp >>> >>> >>> I was not totally clear on which change exactly to pull, but I pulled >>> the following changes: >>> 2023-03-28 md: enhance checking in md_check_recovery()md-tmp Yu >>> Kuai 1 -7/+15 >>> 2023-03-28 md: wake up 'resync_wait' at last in >>> md_reap_sync_thread() Yu Kuai 1 -1/+1 >>> 2023-03-28 md: refactor idle/frozen_sync_thread() Yu Kuai 2 -4/+22 >>> 2023-03-28 md: add a mutex to synchronize idle and frozen in >>> action_store() Yu Kuai 2 -0/+8 >>> 2023-03-28 md: refactor action_store() for 'idle' and 'frozen' Yu >>> Kuai 1 -16/+45 >>> >>> I used to be able to reproduce the lockup within minutes, but with those >>> changes the test system has been running for more than 120 hours. >>> >>> When you said a "different fix", can you confirm that I grabbed the >>> right >>> changes and that I need all 5 of them. >> >> Yes, you grabbed the right changes, and these patches is merged to >> linux-next as well. >>> >>> And second question was, has this fix been submitted upstream yet? >>> If so which kernel version? >> >> This fix is currently in linux-next, and will be applied to v6.6-rc1 >> soon. > > Thank you, that is great news. I'd like to see this change backported to > 5.10 and 6.1, do you have any plans of backporting to any of the > previous kernels? > > If not, I would like to try to get your changes into 5.10 and 6.1 if > Greg will accept them. >
I don't have plans yet, so feel free to do this, I guess these patches won't be picked automatically due to the conflict. Feel free to ask if you meet any problems.
Thanks, Kuai
> > Four out of five of your changes were a straight cherry-pick into 5.10, > one needed a minor conflict resolution. But I can definitely confirm > that your changes fix the lockup issue on 5.10 > > I am now switching to 6.1 and will test the changes there too. > > > Thanks > > > -- > Peace can only come as a natural consequence > of universal enlightenment -Dr. Nikola Tesla > > > . >
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