From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20189C71153 for ; Mon, 28 Aug 2023 20:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233364AbjH1UnG (ORCPT ); Mon, 28 Aug 2023 16:43:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231469AbjH1Umq (ORCPT ); Mon, 28 Aug 2023 16:42:46 -0400 Received: from crane.ash.relay.mailchannels.net (crane.ash.relay.mailchannels.net [23.83.222.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF3A4C9; Mon, 28 Aug 2023 13:42:39 -0700 (PDT) X-Sender-Id: dreamhost|x-authsender|dragan@stancevic.com Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 6BE9D80861; Mon, 28 Aug 2023 20:32:38 +0000 (UTC) Received: from pdx1-sub0-mail-a249.dreamhost.com (unknown [127.0.0.6]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id DBCA9807EA; Mon, 28 Aug 2023 20:32:37 +0000 (UTC) ARC-Seal: i=1; s=arc-2022; d=mailchannels.net; t=1693254758; a=rsa-sha256; cv=none; b=hfMwAbAC16ILpo2xtd3eYe3h/uhwDR7QeRw3kw//n8mfbdxgSfObSMBczGg2oTWG1QaoPs 2P//rglYeQ6n2gre/JRJ/Evz+xxzuS5g/7KBuuv46tI72z4sdLuP0YL36z5ErcdUk/nhr5 gyAYw3Mp/FicIVAJLexpmA/r23gFYldNizf2m8iEwAoQY1ZpKxiGvnfLKFSOktFBQPT22I FAetrhvPPwg0yZz6tWlSLhHppvN6bcPdBGM/8x1Fa+2WHljLo1g4pqBzV020IVKtFUuTin 471VFtsodiEiJoMWeIcQPj4AMDY1QZzgoAVZLiG9UDBPZ+5U72DNiHrBE/PBQA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=mailchannels.net; s=arc-2022; t=1693254757; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xZyZDKbyF1/fKxJYNgyAYTd8dlWkrTHJesnwa/TM0kQ=; b=OuccNz2hW0TNIO5wSPc2a+jYTW9Pc45fMMsyXD/z8dmqDlzOeb3WAbLz0jS623vLVY6Ezt 9sZWqQZNNvX4ebgMJZC6SCvotTTL7ReOOeXe23+3lxwSbLfoJtJgDj+3cwXYMOBWlZRAMy 5R7j6ySlSSCiO/lVTEfxBa2Zxm2e78ghloyXmvRaOBZYC1s1jbiQ2BXwPivuI78eLZeMbm ucNYZJtZ5/tiahVWGjUUiaXxZkIzzQ6gitwPdwlrWh2fylzVuMIj/S0WE3YOT18mnpNvFu bv3nzoAdb4NW0Ajlep3e6GrmMBVoau+F5Fszucay95M3tcwedS+Qs6RGd2HiKw== ARC-Authentication-Results: i=1; rspamd-6fd95854bb-vllw7; auth=pass smtp.auth=dreamhost smtp.mailfrom=dragan@stancevic.com X-Sender-Id: dreamhost|x-authsender|dragan@stancevic.com X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|dragan@stancevic.com X-MailChannels-Auth-Id: dreamhost X-Arithmetic-Fearful: 6004c0411d7f7aa3_1693254758230_2183733472 X-MC-Loop-Signature: 1693254758230:2968947667 X-MC-Ingress-Time: 1693254758230 Received: from pdx1-sub0-mail-a249.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.104.240.44 (trex/6.9.1); Mon, 28 Aug 2023 20:32:38 +0000 Received: from [192.168.1.36] (99-160-136-52.lightspeed.nsvltn.sbcglobal.net [99.160.136.52]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dragan@stancevic.com) by pdx1-sub0-mail-a249.dreamhost.com (Postfix) with ESMTPSA id 4RZMgS6Hlmz2Z; Mon, 28 Aug 2023 13:32:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=stancevic.com; s=dreamhost; t=1693254757; bh=xZyZDKbyF1/fKxJYNgyAYTd8dlWkrTHJesnwa/TM0kQ=; h=Date:Subject:To:Cc:From:Content-Type:Content-Transfer-Encoding; b=ZrDh3m6WN+mIo2x5E88CdIwNQwHP286r/0+VkGolpyPn4gtElYngtJC0cTkRP1C2i 7nEF30EOs0kHADXPQgPwD4n07NNVnl9cusXyuB1Sas2BW2/dWYuplUy3JRQ1k+XLSi 3pBIaS977daPkuQtmElacy60BT62azxM3gLxehdCOo0ocdEWoQTYa9zZPaoYN/5Bps 0f47jdXejV1JnC0P624804ycQ3FFzXwrelDJyoN336XOSbKrrWUkEau6zsrt9QxV41 fzjbieOvN4hBsmSAVlaqel7ox1WlwtNGzITar7r3nb4qjH2MuqPCZDWRI/A08UJ2/x fRnp/OMqV36jw== Message-ID: Date: Mon, 28 Aug 2023 15:32:35 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: md_raid: mdX_raid6 looping after sync_action "check" to "idle" transition Content-Language: en-US To: Yu Kuai , song@kernel.org Cc: buczek@molgen.mpg.de, guoqing.jiang@linux.dev, it+raid@molgen.mpg.de, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, msmith626@gmail.com, "yangerkun@huawei.com" , "yukuai (C)" References: <20230822211627.1389410-1-dragan@stancevic.com> <2061b123-6332-1456-e7c3-b713752527fb@stancevic.com> <07d5c7c2-c444-8747-ed6d-ca24231decd8@huaweicloud.com> From: Dragan Stancevic In-Reply-To: <07d5c7c2-c444-8747-ed6d-ca24231decd8@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kuai, On 8/23/23 20:18, Yu Kuai wrote: > 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 >>>>> >>>>> wr= >>>>> ote: >>>>>   > >>>>>   > On Tue, Mar 14, 2023 at 10:45=E2=80=AFAM Marc Smith >>>>> = >>>>>    wrote: >>>>>   > > >>>>>   > > On Tue, Mar 14, 2023 at 9:55=E2=80=AFAM Guoqing Jiang >>>>> >>>> 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 >>>>>   > > > > 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. Just a followup on 6.1 testing. I tried reproducing this problem for 5 days with 6.1.42 kernel without your patches and I was not able to reproduce it. It seems that 6.1 has some other code that prevents this from happening. On 5.10 I can reproduce it within minutes to an hour. > > 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 >> >> >> . >> > -- Peace can only come as a natural consequence of universal enlightenment -Dr. Nikola Tesla