From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751560AbdB1At5 (ORCPT ); Mon, 27 Feb 2017 19:49:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52332 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbdB1Atz (ORCPT ); Mon, 27 Feb 2017 19:49:55 -0500 Date: Mon, 27 Feb 2017 18:43:11 -0600 From: Josh Poimboeuf To: Guenter Roeck Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: Crash in -next due to 'objtool: Improve detection of BUG() and other dead ends' Message-ID: <20170228004311.pioqmzt76cssrjwr@treble> References: <20170227205923.GA6466@roeck-us.net> <20170227222114.p6vdugfmfjfprt47@treble> <20170227232328.GA1604@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170227232328.GA1604@roeck-us.net> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 28 Feb 2017 00:43:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 27, 2017 at 03:23:28PM -0800, Guenter Roeck wrote: > Hi Josh, > > On Mon, Feb 27, 2017 at 04:21:14PM -0600, Josh Poimboeuf wrote: > > On Mon, Feb 27, 2017 at 12:59:23PM -0800, Guenter Roeck wrote: > > > Hi, > > > > > > my qemu tests for mips64 in -next fail as follows. > > > > > > ... > > > VFS: Mounted root (ext3 filesystem) on device 8:0. > > > Freeing unused kernel memory: 304K > > > This architecture does not have kernel memory protection. > > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000a > > > > > > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000a > > > > > > There is no symbol traceback, and I don't see any other (obvious) error > > > message. bisect points to commit 'objtool: Improve detection of BUG() > > > and other dead ends'; reverting that patch fixes the problem. > > > Bisect log is attached below. > > > > > > The script used to run the test as well as the root file system is available > > > at https://github.com/groeck/linux-build-test/tree/master/rootfs/mips64 > > > > > > A complete log is available at > > > http://kerneltests.org/builders/qemu-mips64-next/builds/592/steps/qemubuildcommand/logs/stdio > > > > Hi Guenter, > > > > This failure doesn't make much sense. Objtool (and the reported bad > > patch) are x86-only and should have nothing to do with mips64. Would it > > be possible for you to double check the error? > > > I already did; after all, bisect points to the patch, and reverting it fixes > the problem. After looking into the patch, I concluded that the following > might help. > > -#define unreachable() annotate_unreachable(); __builtin_unreachable() > +#define unreachable() do { annotate_unreachable(); __builtin_unreachable(); } while (0) > > and it does ... > Doh, of course. Thanks for pointing it out, I'll fix it. -- Josh