From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Serge E. Hallyn" Subject: Re: nsgroup autoremoving Date: Fri, 16 Jan 2009 10:52:17 -0600 Message-ID: <20090116165217.GA8477@us.ibm.com> References: <49706006.80002@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <49706006.80002-GANU6spQydw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Daniel Lezcano Cc: Linux Containers List-Id: containers.vger.kernel.org Quoting Daniel Lezcano (daniel.lezcano-GANU6spQydw@public.gmane.org): > Hi, > > While trying to unshare a namespace with the clone syscall with an > inifinite loop, I got an EEXIST. > That looks weird to have such syscall returning EEXIST ... :) > > After investigating, it appears the ns_cgroup creates automatically a > control group named with the pid number when we call the clone syscall > with a namespace parameter and when the namespace exits, the control > group is not automatically removed. So when the pid numbers are recycled > we conflict with a previous ns_cgroup name and the clone fails. > > IMHO, if the nsgroup is automatically created, it should automatically > destroyed, otherwise what will happen to application using the > namespaces (eg. mount namespace) wrote before nsgroup appeared ? but you can have it automatically destroyed. I.e. I did the following: mount -t cgroup -o freezer,ns freezer /cgroup cat > /bin/release_cgroup.sh << EOF #!/bin/sh echo "Removing dead cgroup .$*." >> /var/log/cgroup rmdir /cgroup/$* >> /var/log/cgroup 2>&1 echo "return value was $?" >> /var/log/cgroup EOF echo /bin/release_cgroup.sh > /cgroup/release_agent echo 1 > /cgroup/notify_on_release chmod ugo+x /bin/release_cgroup.sh ns_exec -m /bin/sh ls /cgroup` 3581 notify_on_release release_agent tasks exit ls /cgroup notify_on_release release_agent tasks -serge