Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933915Ab3GPU36 (ORCPT ); Tue, 16 Jul 2013 16:29:58 -0400 Received: from mail.lang.hm ([64.81.33.126]:53959 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933829Ab3GPU34 (ORCPT ); Tue, 16 Jul 2013 16:29:56 -0400 Date: Tue, 16 Jul 2013 13:29:27 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: "H. Peter Anvin" cc: Willy Tarreau , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, ksummit-2013-discuss@lists.linux-foundation.org, torvalds@linux-foundation.org Subject: Re: [Ksummit-2013-discuss] When to push bug fixes to mainline In-Reply-To: <51E593B6.1050607@zytor.com> Message-ID: References: <20130711214830.611455274@linuxfoundation.org> <20130712005023.GB31005@thunk.org> <20130712051451.GC25815@1wt.eu> <51E593B6.1050607@zytor.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1798 Lines: 41 On Tue, 16 Jul 2013, H. Peter Anvin wrote: > On 07/16/2013 12:19 AM, David Lang wrote: >> On Fri, 12 Jul 2013, Willy Tarreau wrote: >> >>> And maybe in the end, having 1/10 patch cause a regression is not *that* >>> dramatic, and probably less than not fixing the 9 other bugs. In one case >>> we rely on -stable to merge the 10 fixes, and on the other case we'd rely >>> on -stable to just revert one of them. >> >> Apologies for the late post, I'm catching up on things, but this jumped >> out at me. >> >> We went through a LOT of pain several years ago when people got into the >> mindset that a patch was acceptable if it fixed more people than it >> broke. eliminating that mindset did wonders for kernel stability. >> >> Regressions are a lot more of a negative than bugfixes are a positive, a >> 10:1 ratio of fixes to regressions is _not_ good enough. >> > > In my opinion, there is one exception, and that is when the problem > being fixed is much more severe than the fix. *In particular* two > cases: permanently damaging hardware and corrupting data. For example: > no boot, as severe as it is, is much better than either of these two > scenarios. True, but the key point of this subthread is that regressions are _really_ bad, and in practice it's impossible to do enough testing to guarantee that there aren't regressions. as a result, you should only risk regressions if the problem that is being fixed is really important. Just because someone found a bug doesn't make it important enough to risk regressions over. David Lang -- 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/