From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Thery Subject: [PROCFS] [NETNS] issue with /proc/net entries Date: Thu, 10 Jan 2008 18:24:49 +0100 Message-ID: <478654E1.5050501@bull.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: ebiederm@xmission.com Return-path: Received: from ecfrec.frec.bull.fr ([129.183.4.8]:42209 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755254AbYAJRYw (ORCPT ); Thu, 10 Jan 2008 12:24:52 -0500 Sender: netdev-owner@vger.kernel.org List-ID: Hi Eric, While testing the current network namespace stuff merged in net-2.6.25, I bumped into the following problem with the /proc/net/ entries. It doesn't always display the actual data of the current namespace, but sometime displays data from other namespaces. I bisected the problem to the commit: "proc: remove/Fix proc generic d_revalidate" 3790ee4bd86396558eedd86faac1052cb782e4e1 The problem: If a process in a particular network namespace changes current directory to /proc/net, then processes in other network namespaces trying to look at /proc/net entries will see data from the first namespace (the one with CWD /proc/net). (See test case below). As you comments in the commit suggest, you seem to be aware of some issues when CONFIG_NET_NS=y. Is it one of these corner cases you identified? Any idea on how we can fix it? Thanks. Benjamin Test case: ---------- (1) Shell 1, in init namespace: $ cat /proc/net/dev lo ... eth0 ... (2) Shell 2, in another network namespace $ cat /proc/net/dev lo ... (3) Shell 1 $ cd /proc/net $ cat dev lo ... eth0 ... (4) Shell 2 $ cat /proc/net/dev lo ... eth0 ... Argh, lo + eth0 in child namespace.... the device list of init netns is displayed in /proc/net/dev of child namespace :-( (5) Shell 1 $ cd / (6) Shell 2 $ cat /proc/net/dev lo ... Back to normality. -- B e n j a m i n T h e r y - BULL/DT/Open Software R&D http://www.bull.com