From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762419AbZDIVmV (ORCPT ); Thu, 9 Apr 2009 17:42:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758526AbZDIVmJ (ORCPT ); Thu, 9 Apr 2009 17:42:09 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41059 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757286AbZDIVmI (ORCPT ); Thu, 9 Apr 2009 17:42:08 -0400 Date: Thu, 9 Apr 2009 14:37:55 -0700 From: Andrew Morton To: Linus Torvalds Cc: bugzilla-daemon@bugzilla.kernel.org, linux-kernel@vger.kernel.org, "Barry K. Nathan" , stable@kernel.org Subject: Re: [Bugme-new] [Bug 13012] New: 2.6.28.9 causes init to segfault on Debian etch; 2.6.28.8 OK Message-Id: <20090409143755.96e0c62c.akpm@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). -fwrapv killed Barry's gcc-4.1.2-compiled kernel in 2.6.27.x, 2.6.28.x and presumably 2.6.29, 2.6.30. On Sun, 5 Apr 2009 13:04:02 GMT bugzilla-daemon@bugzilla.kernel.org wrote: > http://bugzilla.kernel.org/show_bug.cgi?id=13012 > > Summary: 2.6.28.9 causes init to segfault on Debian etch; > 2.6.28.8 OK > Product: Other > Version: 2.5 > Kernel Version: 2.6.28.9 > Platform: All > OS/Version: Linux > Tree: Mainline > Status: NEW > Severity: high > Priority: P1 > Component: Other > AssignedTo: other_other@kernel-bugs.osdl.org > ReportedBy: barryn@pobox.com > Regression: Yes > > > (I haven't had a chance to collect all that data that I wanted to collect > before reporting this bug, but this might be the best I can do for the next few > days, so I think it's best for me to submit what I have so far instead of > sitting on it.) > > The system in question is a Debian etch system which has a static /dev (no > udev) and does not use an initrd or initramfs. With 2.6.28.8, it works fine. > With 2.6.28.9, init segfaults during boot, so the system fails to finish > booting. (Same problem happens on 2.6.27.21 and does not happen on 2.6.27.20, > but I have not had time to investigate that version in depth.) > > git bisect says "92db6956ecd01ceb7934be0252b3b184a82ebb64 is first bad commit". > That's "Add '-fwrapv' to gcc CFLAGS". If I take 2.6.28.9 and I revert "Move > cc-option to below arch-specific setup" and "Add '-fwrapv' to gcc CFLAGS" then > the resulting kernel works again. > > I also noticed that the problem only happens with some gcc's: > > Problem occurs: > gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21) > gcc-4.1 (GCC) 4.1.3 20080704 (prerelease) (Debian 4.1.2-25) > > Problem does not occur (i.e. 2.6.28.9 works and I don't have to revert > anything): > gcc-4.2 (GCC) 4.2.4 (Debian 4.2.4-6) > gcc (Debian 4.3.2-1.1) 4.3.2 > > (BTW, on 2.6.29, I'm having a problem where if I'm running 2.6.29 then make > instantly blows up in a strange way, and the same pattern of working/failing > compilers is showing up there too.) > > I have not yet had a chance to try vanilla gcc 4.1.2. That's what I intend to > try next. > > I'll attach my .config within the next 24 hours, and I'll try to post serial > console captures by sometime Tuesday or so. If there's any other information > which would help, feel free to ask... > > > My gut feeling is that this is truly a gcc bug rather than a kernel bug, but > it's still disconcerting to see this kind of breakage suddenly pop up in a > -stable series, so IMO it may be worth considering reverting the -fwrapv > changes for 2.6.2[78].y. >