From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754913Ab2LMWZh (ORCPT ); Thu, 13 Dec 2012 17:25:37 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36906 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028Ab2LMWZg (ORCPT ); Thu, 13 Dec 2012 17:25:36 -0500 Date: Thu, 13 Dec 2012 14:25:34 -0800 From: Andrew Morton To: Neil Horman Cc: Serge Hallyn , linux-kernel@vger.kernel.org, Daniel Berrange , Alexander Viro , containers@lists.linux-foundation.org Subject: Re: [PATCH] core_pattern: set core helpers root and namespace to crashing process Message-Id: <20121213142534.ea07a3c8.akpm@linux-foundation.org> In-Reply-To: <20121213181220.GB14796@hmsreliant.think-freely.org> References: <1355255996-25953-1-git-send-email-nhorman@tuxdriver.com> <20121213122048.GF5246@sergelap> <20121213181220.GB14796@hmsreliant.think-freely.org> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 Dec 2012 13:12:20 -0500 Neil Horman wrote: > On Thu, Dec 13, 2012 at 06:20:48AM -0600, Serge Hallyn wrote: > > Quoting Neil Horman (nhorman@tuxdriver.com): > > > Theres one problem I currently see with it, and that is that I'm not sure we can > > > change the current behavior of how the root fs is set for the pipe reader, lest > > > we break some user space expectations. As such, I've added a sysctl in this > > > patch to allow administrators to globally select if a core reader specified via > > > /proc/sys/kernel/core_pattern should use the global rootfs, or the (possibly) > > > chrooted fs of the crashing process. > > > > Practical question: How is the admin to make an educated decision on > > how to set the sysctl? By reading the documentation which Neil didn't include? > My thought was that the admin typically wouldn't touch this at all. I really > added it as a backwards compatibility option only. Setting the user space > helper task to the root of the crashing parent has the possibility of breaking > existing installs because the core_pattern helper might be expecting global file > system access. Moving forward, my expectation would be that core_pattern > helpers would be written with the default setting in mind, and we could > eventually deprecate the control entirely. > > If you have a better mechanism in mind however (or if you think that removing > the control is a resaonable approach), I'm certainly open to that. Yeah, this is a tiresome patch but I can't think of a better way. Except, perhaps, adding a new token to the core_pattern which says "switch namespaces"? Is there any propect that the core_pattern itself will later become a per-namespace containerised thing? I guess that if the per-container core_pattern has been configured, we can implicitly do the namespace switch as well.