From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753304Ab1KWQU5 (ORCPT ); Wed, 23 Nov 2011 11:20:57 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:54999 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752385Ab1KWQUz (ORCPT ); Wed, 23 Nov 2011 11:20:55 -0500 From: Pedro Alves Organization: CodeSourcery To: Tejun Heo Subject: Re: [RFC][PATCH 0/3] fork: Add the ability to create tasks with given pids Date: Wed, 23 Nov 2011 16:20:44 +0000 User-Agent: KMail/1.13.6 (Linux/2.6.38-12-generic; KDE/4.7.2; x86_64; ; ) Cc: Pavel Emelyanov , Oleg Nesterov , Linus Torvalds , Andrew Morton , Alan Cox , Roland McGrath , Linux Kernel Mailing List , Cyrill Gorcunov , James Bottomley References: <4EC4F2FB.408@parallels.com> <201111221204.39235.pedro@codesourcery.com> <20111122153326.GD322@google.com> In-Reply-To: <20111122153326.GD322@google.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201111231620.45440.pedro@codesourcery.com> X-OriginalArrivalTime: 23 Nov 2011 16:20:47.0918 (UTC) FILETIME=[DBF6ECE0:01CCA9FB] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Tejun, On Tuesday 22 November 2011 15:33:26, Tejun Heo wrote: > Hello, > > On Tue, Nov 22, 2011 at 12:04:38PM +0000, Pedro Alves wrote: > > This whole userspace C/R stuff and being able to set the child's pid has potential > > of being very useful for GDB too, allowing a much better reimplementation of its > > old checkpointing feature [*], and allowing for a faster reverse debugging > > implementation, by being able to do faster rewinding -- restore snapshot and replay > > instructions up to N (by single stepping or running to breakpoint), rather than > > manually undoing the effects of each instruction, one by one. > > > > IOW, root only would be a shame from GDB's perspective. > > Would CAP_CHECKPOINT be a shame too? I think CAP_CHECKPOINT (or something through some LSM) would be definitely better. > I'm reluctant about priviledge > through fd inheritance mostly because of its unusualness. I don't > think priv management is a good problem space for small creative > solutions. We're much better off with mundane mechanisms which people > are already familiar with and is easy to account for. fd inheritance wouldn't work for gdb; a user spawned gdb wouldn't inherit an open fd to kernel.ns_last_pid from anywhere. -- Pedro Alves