Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757276AbXKBPfV (ORCPT ); Fri, 2 Nov 2007 11:35:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754220AbXKBPfJ (ORCPT ); Fri, 2 Nov 2007 11:35:09 -0400 Received: from mx1.redhat.com ([66.187.233.31]:57074 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754068AbXKBPfH (ORCPT ); Fri, 2 Nov 2007 11:35:07 -0400 Message-ID: <472B4378.80809@redhat.com> Date: Fri, 02 Nov 2007 08:34:16 -0700 From: Ulrich Drepper Organization: Red Hat, Inc. User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Pavel Emelyanov CC: Andrew Morton , Ingo Molnar , Linus Torvalds , linux-kernel@vger.kernel.org, Sukadev Bhattiprolu , Serge Hallyn Subject: Re: [patch] PID namespace design bug, workaround References: <20071101144307.GA29566@elte.hu> <4729E7E4.8070208@openvz.org> <4729E936.4040400@redhat.com> <4729EB3C.9050102@openvz.org> <472A6D91.1020300@redhat.com> <472AD7D6.80900@openvz.org> <20071102010419.23f3db5c.akpm@linux-foundation.org> <472ADC78.6070706@openvz.org> <472B2EBD.7070007@redhat.com> <472B327E.2060006@openvz.org> In-Reply-To: <472B327E.2060006@openvz.org> X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1542 Lines: 39 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Pavel Emelyanov wrote: > So is "everything else", you mentioned, covered with the problems > above? No, it's not. If you'd read the mail carefully you'd notice that the use of PIDs especially in robust futexes is part of the API and that it simply isn't acceptable to say "don't do that". A robust mutex can be stored in any file and as long as two processes have access to the same file (or they can pass each other shared memory) the underlying futex functionality simply must work. This whole approach to allow switching on and off each of the namespaces is just wrong. Do it all or nothing, at least for the problematic ones like NEWPID. Having access to the same filesystem but using separate PID namespaces is simply not going to work. You also brush completely over the SysV IPC issue. And I doubt that I spent enough time thinking about all this to arrive at the more subtle problems. I don't think especially the PID namespace is ready at all at this time. - -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) iD4DBQFHK0N42ijCOnn/RHQRAkPyAJiDR9ZEPUbCdEa2xk+Te80B7avDAJ4mgy7v jgtZG129yBUGBrpQ8fbn7w== =ho0Z -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/