Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758095AbcLAMrx (ORCPT ); Thu, 1 Dec 2016 07:47:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39888 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255AbcLAMrw (ORCPT ); Thu, 1 Dec 2016 07:47:52 -0500 Message-ID: <58401BF6.4040405@redhat.com> Date: Thu, 01 Dec 2016 07:47:50 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Nicolas Pitre , Linus Torvalds CC: Jarod Wilson , Linux Kernel Mailing List , Tony Luck , zarniwhoop73@googlemail.com, Linux Kbuild mailing list Subject: Re: Odd build breakage in 4.9-rc7 References: <20161130172435.GG8563@redhat.com> <583F1A5A.7040708@redhat.com> <583F1F6A.5010307@redhat.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Thu, 01 Dec 2016 12:47:52 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1205 Lines: 38 On 11/30/2016 05:41 PM, Nicolas Pitre wrote: > On Wed, 30 Nov 2016, Linus Torvalds wrote: > >> On Wed, Nov 30, 2016 at 10:50 AM, Prarit Bhargava wrote: >>> >>> It comes back. The steps to reproduce this are: >>> >>> 1. checkout latest linux.git >>> 2. make -j112 >>> >>> (IOW, it occurs 100% of the time for me on a clean tree.) > > I don't have access to such hardware where -j112 could ever make sense. :-) :) I could push the builds onto the -j256 but I'm doing other stuff over there. :) > In other words, I can't reproduce regardless of the -j value I try. > >> I suspect it's not new, it's just that you are able to hit the timing >> just right (and the new include presumable makes that just be much >> easier). > > Here's the best fix I can think of. I can't convince myself any other > location would be 100% safe. Obviously I can't confirm if this actually > fixes anything. > > ----- >8 > Subject: kbuild: make sure autoksyms.h exists early > I'm building with this patch on top of latest now. I will put it in a tight loop and clear the drop_caches between builds to see if I can make it fail. Thanks Nicolas -- your help is very much appreciated. P.