From: Theodore Ts'o Subject: Re: Difference in jbd2 behavior between CentOS and Ubuntu while unmounting Date: Wed, 18 May 2016 10:12:40 -0400 Message-ID: <20160518141240.GB1710@thunk.org> References: <32a9cbf4-4e2d-335c-0603-9639b30e2863@redhat.com> <782fe069-c14f-4bae-609e-bbad554cb657@redhat.com> <20160518061834.GA4502@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , Kamran Khan , linux-ext4@vger.kernel.org To: "Darrick J. Wong" Return-path: Received: from imap.thunk.org ([74.207.234.97]:37972 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932237AbcEROMu (ORCPT ); Wed, 18 May 2016 10:12:50 -0400 Content-Disposition: inline In-Reply-To: <20160518061834.GA4502@birch.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, May 17, 2016 at 11:18:34PM -0700, Darrick J. Wong wrote: > Just to throw some gasoline on this fire, I hit the same set of symptoms > a couple of weeks ago while trying to umount /home on 4.5.0 + Ubuntu 16.04. > Ted mused that it could be some process running in a funny mount namespace. > Or systemd dragons. Or something. Try the following to see if someone process is playing namespace games find /proc -name mounts | xargs grep /dev/sda3 (replace /dev/sda3 with the device that you think is unmounted). When you find the process, kill it. (Or try doing a service XXX restart assuming that the device has been unmounted in the "normal" mount namespace.) Another simple thing to try doing is to go into single user mode, which will kill off all/most of your userspace processes, which may also have the desired effect. Much more of a blunt hammer, though. - Ted