From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754790AbbCBQvO (ORCPT ); Mon, 2 Mar 2015 11:51:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34673 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754349AbbCBQvN (ORCPT ); Mon, 2 Mar 2015 11:51:13 -0500 Message-ID: <54F494E9.4020307@redhat.com> Date: Mon, 02 Mar 2015 11:50:49 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131028 Thunderbird/17.0.10 MIME-Version: 1.0 To: Borislav Petkov CC: Naoya Horiguchi , Naoya Horiguchi , "Luck, Tony" , Vivek Goyal , "linux-kernel@vger.kernel.org" , Junichi Nomura , Kiyoshi Ueda Subject: Re: [PATCH v2 1/2] x86: mce: kexec: turn off MCE in kexec References: <1425013116-23581-1-git-send-email-n-horiguchi@ah.jp.nec.com> <54F05080.9090605@redhat.com> <20150227120648.GA3337@pd.tnic> <3908561D78D1C84285E8C5FCA982C28F329F18A7@ORSMSX114.amr.corp.intel.com> <20150302023118.GB25064@hori1.linux.bs1.fc.nec.co.jp> <20150302121701.GA17521@pd.tnic> <54F474BD.1010802@gmail.com> <20150302163216.GF17521@pd.tnic> In-Reply-To: <20150302163216.GF17521@pd.tnic> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/02/2015 11:32 AM, Borislav Petkov wrote: > On Mon, Mar 02, 2015 at 11:33:33PM +0900, Naoya Horiguchi wrote: >> Yes, CPU offlining is one option to keep other CPUs quiet. I'm not sure why >> current kexec implementation doesn't offline the other CPUs but just doing >> cpu_relax() loop, but my guess is that in some kernel panic situation (like >> soft lockup) we want to keep CPUs' status undisturbed to make sure the bug's >> info is captured in kdump. > > Well either offlining or keeping them in the idle loop is fine - they're > not executing anything else and thus the probability of them causing an > MCE becomes disappearingly small. Unless entering a deep C state kicks an MCE ... which we've seen with flaky hardware. P. >