From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750773AbXDDUa1 (ORCPT ); Wed, 4 Apr 2007 16:30:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750797AbXDDUa1 (ORCPT ); Wed, 4 Apr 2007 16:30:27 -0400 Received: from smtp.osdl.org ([65.172.181.24]:55498 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773AbXDDUaZ (ORCPT ); Wed, 4 Apr 2007 16:30:25 -0400 Date: Wed, 4 Apr 2007 13:29:49 -0700 From: Andrew Morton To: Dave Dillow Cc: Ingo Molnar , Gene Heskett , linux-kernel@vger.kernel.org, ray-gmail@madrabbit.org, amanda-hackers@amanda.org, amanda-users@amanda.org Subject: Re: plain 2.6.21-rc5 (1) vs amanda (0) Message-Id: <20070404132949.f6fbca9f.akpm@linux-foundation.org> In-Reply-To: <1175710634.27756.40.camel@dillow.idleaire.net> References: <200704010100.19016.gene.heskett@verizon.net> <2c0942db0704010033r61f967c3y7d05e3ec0a9f6931@mail.gmail.com> <200704011141.53105.gene.heskett@verizon.net> <200704020021.02393.gene.heskett@gmail.com> <1175488272.3161.28.camel@obelisk.thedillows.org> <1175661256.31439.23.camel@obelisk.thedillows.org> <20070404084530.GB1556@elte.hu> <20070404104219.40e25b6a.akpm@linux-foundation.org> <1175710634.27756.40.camel@dillow.idleaire.net> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-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 X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 04 Apr 2007 14:17:13 -0400 Dave Dillow wrote: > On Wed, 2007-04-04 at 10:42 -0700, Andrew Morton wrote: > > On Wed, 4 Apr 2007 10:45:30 +0200 Ingo Molnar wrote: > > > > > > > > * Dave Dillow wrote: > > > > > > > > Then it is a matter of figuring out why the device number changed -- > > > > > I'm thinking it is device-mapper, but will look closer tomorrow. > > > > > > > > This commit is the one that changed it: > > > > > > > > commit fdf892be32d84a1745fa0aee5fc60517421b8038 > > > > Author: Andrew Morton > > > > Date: Mon Feb 12 00:51:44 2007 -0800 > > > > > > > > [PATCH] register_blkdev(): don't hand out the LOCAL/EXPERIMENTAL majors > > > > > > > > As pointed out in http://bugzilla.kernel.org/show_bug.cgi?id=7922, > > > > dynamic blockdev major allocation can hand out majors which LANANA > > > > has defined as being for local/experimental use. > > > > > > i dont think we should break backwards compatibility with a system that > > > has not changed any hardware. Andrew, should we revert this? > > > > Well that's an odd thing for a backup program to be doing - there are any > > number of things which could cause a dynamically-allocated major to change. > > > > ho hum, yes, I guess it needs to go. > > The thing is, it's been broken for a long time -- this change just > highlighted it. This isn't the first time that device-mapper has moved > -- the introduction of mdp (before git, so haven't tracked down > timeframe) also moved it around. The dynamic major is not stable, so > should we be concerned if it moves for 2.6.21? > > I don't like the effect it has on the backups, but I don't think we > should hand out LOCAL/EXP majors to dynamic devices, either. There is a > module option to make the device-mapper and mdp majors stable, so > perhaps a compromise is possible? Revert for 2.6.21, and schedule the > patch for later addition, which gives distros time to use the DM major > option? hm, good points. Overall, the patch helps kernel developers and hurts the userbase. I tend to prefer to hurt kernel developers than our users ;) I don't think the protect-lanana-numbers thing is very important, really. If some kernel developer or someone who is maintaining an unofficial out-of-tree driver hits the problem, they are presumably able to handle it. Preferably by switching to a dynamically-assigned major.