On Tue, 3/28/23 17:01 Song Liu wrote: > On Thu, Mar 16, 2023 at 8:25=E2=80=AFAM Marc Smith <msmith626@xxxxxxxxx> > wr= > ote: > > > > On Tue, Mar 14, 2023 at 10:45=E2=80=AFAM Marc Smith > <msmith626@xxxxxxxxx>= > 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@xxxxxxxxxxxxxxx> 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. And second question was, has this fix been submitted upstream yet? If so which kernel version? Thank you
