From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: [cgroup or VFS ?] WARNING: at fs/namespace.c:636 mntput_no_expire+0xac/0xf2() Date: Thu, 12 Feb 2009 14:10:37 +0800 Message-ID: <4993BD5D.2020707@cn.fujitsu.com> References: <49617D35.4040805@cn.fujitsu.com> <20090209004046.3ce1dde0.akpm@linux-foundation.org> <20090209093414.GU28946@ZenIV.linux.org.uk> <499013CC.2060808@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <499013CC.2060808@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org To: Al Viro Cc: containers@lists.osdl.org, Paul Menage , Andrew Morton , LKML , Arjan van de Ven List-Id: containers.vger.kernel.org Li Zefan wrote: > Al Viro wrote: >> On Mon, Feb 09, 2009 at 12:40:46AM -0800, Andrew Morton wrote: >>>> Thread 1: >>>> for ((; ;)) >>>> { >>>> mount -t cgroup -o cpuset xxx /mnt > /dev/null 2>&1 >>>> mkdir /mnt/0 > /dev/null 2>&1 >>>> rmdir /mnt/0 > /dev/null 2>&1 >>>> umount /mnt > /dev/null 2>&1 >>>> } >>>> >>>> Thread 2: >>>> { >>>> mount -t cpuset xxx /mnt > /dev/null 2>&1 >>>> umount /mnt > /dev/null 2>&1 >>>> } >> How cute... Same mountpoint in both, so these mount(2) will sometimes >> fail (cgroup picks the same sb on the same options, AFAICS) and fail >> silently due to these redirects... >> >> That's a lovely way to stress-test a large part of ro-bind stuff *and* >> umount()-related code. Could you do C equivalent of the above (just >> the same syscalls in loop, nothing fancier) and do time-stamped strace? >> > > Sure, I'll write a C version and try to reproduce the warning. > Unfortunately, the C equivalent can't reproduce the warning, I've run the test for the whole night. :( While using the script, often I can trigger the warning in several mins.