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 1C43C8C07 for ; Sat, 21 Sep 2024 08:05:39 +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=1726905943; cv=none; b=Gl0G5YOlrkaEYA5xA928JP4tTqVrFlRKEyNnooy+3VZOvLzK0qs8Cz+1e0rtYZ4+P+3ypPQxu323Gk8FAR3+oimOPAOp8KSzlsDIot7EJO53XIwGlI98GkwZohy6nh5awkHMVyU4gYvBfUR78HlFgQZlDVKgoI1RGcaSgxXdNVE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726905943; c=relaxed/simple; bh=AtLz/usv0W73PVsD4gOVRs7NTWRnSxRNnoRRwVOzlaQ=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=BmslOLqR7OF2RcN1PKrhdxP6svKOAHHjkYHGtJPBT+TRgrippFcFOnoOsBjkn2olFEgMY+wWLuOkPqp2z3d2Li/B2VWOH6VSDqLhRWF9LyCqOYRQOsceHeeZZlq4Vii6LVv3jOepoXhOTxVRbL5kK1DnqsCsA81ZFtDTAeV5LFU= 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 11761 invoked from network); 21 Sep 2024 07:58:56 -0000 Received: from unknown (HELO mailhost.afaics.de) (postmaster@xqrsonfo.mail.selfhost.de@87.160.249.214) by mailout.selfhost.de with ESMTPA; 21 Sep 2024 07:58:56 -0000 Received: from cecil.afaics.de (p200300e31f1da20268fdfffffe6f0e76.dip0.t-ipconnect.de [2003:e3:1f1d:a202:68fd:ffff:fe6f:e76]) by marvin.afaics.de (OpenSMTPD) with ESMTP id 0de61920; Sat, 21 Sep 2024 09:58:55 +0200 (CEST) Subject: Re: [syzbot] [nfs?] INFO: task hung in nfsd_umount To: NeilBrown , syzbot Cc: Jeff Layton , Dai.Ngo@oracle.com, chuck.lever@oracle.com, kolga@netapp.com, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, syzkaller-bugs@googlegroups.com, tom@talpey.com References: <000000000000f8ed54061ca0d9a5@google.com> <9825cc5ff85d4a2a4ce1c955f49681bef8d03442.camel@kernel.org> <172039726840.11489.12386749198888516742@noble.neil.brown.name> From: Harald Dunkel Message-ID: <42600ff8-512f-bea1-848c-2cc1c823cb76@afaics.de> Date: Sat, 21 Sep 2024 09:58:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 SeaMonkey/2.53.18.2 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <172039726840.11489.12386749198888516742@noble.neil.brown.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit NeilBrown wrote: > > We can guess though. It isn't waiting for a lock - that would show in > the above list - so it might be waiting for a wakeup, or might be > spinning. > The only wake-up I can imagine is in one of the memory-allocation calls, > but if the system were running out of memory we would probably see > messages about that. > I have seen something like this. I am running NFS inside a container, using legacy cgroup. When it got stuck it claimed I cannot login into the container due to out of memory. When it happens again, I can send you the exact error message. The next hung nfsd is overdue, anyway. > I wonder if it could be looping in svc_xprt_destroy_all(), and sitting > in the msleep() when the hang is detected so there are no locks to > report. I can't see while it would block there. > > It would really help to get a full task list. > There is a sysctl for that: /proc/sys/kernel/hung_task_all_cpu_backtrace > > Could that be enabled? > I have enabled it on my NFS server (echo 1 >/proc/.../hung_task_all_cpu_backtrace). Regards Harri