From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754477AbbHMXS3 (ORCPT ); Thu, 13 Aug 2015 19:18:29 -0400 Received: from mail-ig0-f182.google.com ([209.85.213.182]:34810 "EHLO mail-ig0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754153AbbHMXSS (ORCPT ); Thu, 13 Aug 2015 19:18:18 -0400 MIME-Version: 1.0 In-Reply-To: References: <55CA90B4.2010205@list.ru> <55CCD921.4040301@list.ru> <20150813200823.GS2059@uranus> <55CD0F29.4070604@gmail.com> <55CD13A0.8060403@gmail.com> Date: Thu, 13 Aug 2015 16:18:17 -0700 X-Google-Sender-Auth: WmLYLhwUqyCC6q4p5-6xo3EyP7E Message-ID: Subject: Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu From: Linus Torvalds To: Raymond Jennings Cc: Cyrill Gorcunov , Andy Lutomirski , Pavel Emelyanov , Stas Sergeev , Linux kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 13, 2015 at 4:05 PM, Linus Torvalds wrote: > > The _only_ thing that matters is that something broke. To clarify: things like test programs etc don't matter. Real applications, used by real users. That's what regressions cover. If you have a workflow that isn't just some random kernel test thing, and you depend on it, and we break it, the kernel is supposed to fix it. There are some (very few) exceptions. If it's a security issue, we may not be able to "fix" it, because other concerns can obviously take precedence. Also, sometimes the reports come in way too late - if you were running some stable distro kernel for several years, and updated, and notice a change that happened four years ago and modern applications now rely on the _new_ behavior, we may not be able to fix the regression any more. But no, "it was an unintentional kernel bug and clearly just stupid crap code, and we fixed it and now the kernel is much better and cleaner" is not a valid reason for regressions. We'll go back to the stupid and crap code if necessary, however much that may annoy us. For an example of the kind of things we may have to do, see commits 64f371bc3107 autofs: make the autofsv5 packet file descriptor use a packetized pipe 9883035ae7ed pipes: add a "packetized pipe" mode for writing and just wonder at the insanity. That's the kinds of things that happen when one application had actively worked around a bug in compatibility handling, and then trying to "fix" that bug just caused another application to break instead. Linus