From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: BUG: enabling psacct breaks fsfreeze Date: Wed, 31 Oct 2012 13:15:17 +0100 Message-ID: <20121031121517.GD18424@quack.suse.cz> References: <20121023094351.GC27919@pcnci.linuxbox.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Nikola Ciprich Return-path: Content-Disposition: inline In-Reply-To: <20121023094351.GC27919@pcnci.linuxbox.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hello, On Tue 23-10-12 11:43:51, Nikola Ciprich wrote: > while trying to create consistent backups of KVM guest, I've discovered > that fsfreeze always hangs.. deeper investigation revealed psacct to be the culprit. > When psacct is disabled, fsfreeze works fine, when enabled, the command never returns. > I suppose that the problem is /var is not on separate partition (ie it's same volume > as /) and psacct isn't able to dump process exit information about fsfreeze command > thus creating deadlock.. > problem is 100% reproducible on both latest 3.0.x kernel and 3.7-r1c. > > Should more debugging information be needed, I'll be glad to provide whatever I can.. Thanks for report. Hum, I'm not sure how the deadlock can happen because AFAIU audit sends a message via netlink to userspace and whatever audit daemon does with it is its private thing. Can you please run: echo w >/proc/sysrq-trigger after the machine deadlocks and then take dmesg and attach it here? You'll have to have the shell prepared and use serial console / netconsole to gather dmesg or try your luck with copying via ssh / netcat. Honza -- Jan Kara SUSE Labs, CR