From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161783AbcIZRjZ (ORCPT ); Mon, 26 Sep 2016 13:39:25 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:48230 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161042AbcIZRjX (ORCPT ); Mon, 26 Sep 2016 13:39:23 -0400 Date: Mon, 26 Sep 2016 13:36:47 -0400 (EDT) From: Thomas Gleixner To: Mike Galbraith cc: Ingo Molnar , LKML , Borislav Petkov , Dou Liyang Subject: Re: [x86-tip] strange nr_cpus= boot regression In-Reply-To: <1474892945.9232.23.camel@gmail.com> Message-ID: References: <1474892945.9232.23.camel@gmail.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org CC'ed: Dou Liyang On Mon, 26 Sep 2016, Mike Galbraith wrote: > I've encountered a strange regression in tip, symptom is that if you > boot with nr_cpus=nr_you_have, what actually boots is nr_you_have/2. > Do not pass nr_cpus=, and all is well. What's the number of possible cpus in your system? > Bisection repeatedly goes as below, pointing to the nodeid merge, > despite both timers/core and x86/apic (nodeid) being fine. Take tip > HEAD, extract all of the commits from nodeid (plus the fix), and revert > them in a quilt tree, the tree remains busted. So you remove all the nodeid commits from tip/master and it's still broken? > Checkout the timers/core merge commit, and merge nodeid with that, it is > indeed bad. > Bisecting takes you right the merge commit, with no commit > being 'bad', see logs. That's more than strange. An empty merge commit being the culprit. Thanks, tglx