From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.selfhost.de (mordac.selfhost.de [82.98.82.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 501791E4B0 for ; Sun, 29 Sep 2024 08:23:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.98.82.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727598226; cv=none; b=B5auEiigJPyD34Q63grJ5VWZCNMziboMdjro3HdJ2tKAfyf9LiPS4/y7TwcMLFBfncjXvZszzKxOHOn+AXnir8Zn4EZAGhpAeU6RiQwd1AZyqxqlSJ+HHrgN3OJ7blyRMu/TUrR2K+TAXVwgX5JWXQzeFEIaD+cuye92Xq1c35o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727598226; c=relaxed/simple; bh=QGiLX1N25i5QiptM390ojj7ex5Xay1s9G4LoYtTTuwE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F4bEQrqyi+uxTpnQvMxoWfToT7juuIuPGsXvGXjtzXUkC49S+QbbJnC5JT41B0irPByXAeumEqcJXLYkUmOTUu+5/EErSxPhrqfvnME8QgblxjxY/hKI4DUeZrGJJcQ6ZdkljQ6q+LHCHZ+RP8IiN1gsXi+jArBXQbxr1s52Aqs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=afaics.de; spf=none smtp.mailfrom=afaics.de; arc=none smtp.client-ip=82.98.82.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=afaics.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=afaics.de Received: (qmail 2526 invoked from network); 29 Sep 2024 08:23:35 -0000 Received: from unknown (HELO mailhost.afaics.de) (postmaster@xqrsonfo.mail.selfhost.de@87.160.249.214) by mailout.selfhost.de with ESMTPA; 29 Sep 2024 08:23:35 -0000 Received: from [IPV6:2003:e3:1f1d:a202:68fd:ffff:fe6f:e76] (p200300e31f1da20268fdfffffe6f0e76.dip0.t-ipconnect.de [2003:e3:1f1d:a202:68fd:ffff:fe6f:e76]) by marvin.afaics.de (OpenSMTPD) with ESMTP id 912a126f; Sun, 29 Sep 2024 10:23:34 +0200 (CEST) Message-ID: <90750d21-61fa-4243-8c6b-dbf6fa185ae4@afaics.de> Date: Sun, 29 Sep 2024 10:23:34 +0200 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Betterbird (Linux) Subject: Re: [syzbot] [nfs?] INFO: task hung in nfsd_umount To: NeilBrown Cc: syzbot , Jeff Layton , Dai.Ngo@oracle.com, chuck.lever@oracle.com, kolga@netapp.com, linux-nfs@vger.kernel.org, syzkaller-bugs@googlegroups.com, tom@talpey.com References: <> <172756219838.470955.2955513122187106920@noble.neil.brown.name> From: Harald Dunkel Content-Language: en-US In-Reply-To: <172756219838.470955.2955513122187106920@noble.neil.brown.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Neil, On 2024-09-29 00:23:18, NeilBrown wrote: > > Thanks for the logs. The point to flush_workqueue() being a problem, > presumably from nfsd4_probe_callback_sync(), though I'm not 100% sure of > that. Maybe some deadlock in the callback code. I'm not very familiar > with that code and nothing immediately jumps out. > > I had thought that hung_task_all_cpu_backtrace would show a backtrace of > *all* tasks - I missed the "cpu" in there. > If if it happens again and if you can > echo t > /proc/sysrq-trigger > to get stack traces of everything, that might help. Maybe it won't be > necessary if I or someone else can spot a deadlock with > flush_workqueue(). > I just learned that kernel.hung_task_panic = 1 should have been set, too. Sorry for that. Currently I have kernel.hung_task_panic = 1 kernel.hung_task_all_cpu_backtrace = 1 Please confirm. I have set a watchdog to run the sysrq trigger on the NFS server if df on an NFS client doesn't respond. Regards Harri