From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Schillstrom Subject: Race condition when creating multiple namespaces? Date: Mon, 11 Apr 2011 23:01:46 +0200 Message-ID: <201104112301.46776.hans@schillstrom.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org, Daniel Lezcano , "Eric W. Biederman" Return-path: Received: from smtp-gw21.han.skanova.net ([81.236.55.21]:48221 "EHLO smtp-gw21.han.skanova.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754239Ab1DKVCI (ORCPT ); Mon, 11 Apr 2011 17:02:08 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Hello I'v been strugling with this for some time now When creating multiple namespaces using lxc-start, un-initialized network namespace parts will be called by the new process in the namespace. ex. when using conntrack or ipvsadm to quickly, (a sleep 2 "solves" the problem). (From what I can see syscall clone() is used in lx-start i.e. do_fork will be called later on.) Actually I was debugging ip_vs when closing multiple ns when I fell into this one. I have a loop that create 33 containers whith lxc-start ... -- test.sh the first thing the new conatiner does in test.sh is #!/bin/bash iptables -t mangle -A PREROUTING -m conntrack --ctstate RELATED,ESTABLISHED -j CONNMARK --restore-mark nc -l -p1234 This results in NULL ptr in ip_conntrack_net_init(struct *net) and in anoither test test.sh looks like this #!/bin/bash ipvsadm --start-daemon=master --mcast-interface=lo nc -l -p1234 And this results in an uniitialized spinlock in ip_vs_sync I put a printk in nsproxy: copy_namespaces() and could see a dozens of them before anything appears from ipvs or conntrack. My feeling is that when you start up user processes in a new name space, all kernel related init should have been done (you should not need to add a sleep to get it working) All test made by using todays net-next-2.6 (2.6.39-rc1) Note: That neither conntrack or ip_vs modules where loaded, if modules where loaded before creating new namespaces it all works... Finally the question, Should it really work to load modules within a namespace , that is a part of netns ? -- Mvh Hasse Schillstrom 070-699 7150