From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751273AbaEUBfe (ORCPT ); Tue, 20 May 2014 21:35:34 -0400 Received: from mail-pb0-f54.google.com ([209.85.160.54]:40173 "EHLO mail-pb0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbaEUBfd (ORCPT ); Tue, 20 May 2014 21:35:33 -0400 Message-ID: <1400636036.14703.21.camel@debian> Subject: Re: [PATCH v2] x86/mce: Distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU From: Chen Yucong To: Borislav Petkov Cc: tony.luck@intel.com, ak@linux.intel.com, ying.huang@intel.com, seto.hidetoshi@jp.fujitsu.com, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org Date: Wed, 21 May 2014 09:33:56 +0800 In-Reply-To: <20140520173308.GE16428@pd.tnic> References: <1400551885-13828-1-git-send-email-slaoub@gmail.com> <20140520173308.GE16428@pd.tnic> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-05-20 at 19:33 +0200, Borislav Petkov wrote: > On Tue, May 20, 2014 at 10:11:25AM +0800, Chen Yucong wrote: > > mces_seen is a Per-CPU variable which should only be accessed by > > Per-CPU as possible. So the clear operation of mces_seen should also > > be lcoal to Per-CPU rather than monarch CPU. > > > > Meanwhile, there is also a potential risk that mces_seen will not > > be be cleared if a timeout occors in mce_end for monarch CPU. As a > > reuslt, the stale value of mces_seen will reappear on the next mce. > > I don't know how many times I have to tell you this already: if we reach > the timeout, we have a much bigger friggin' problem! > > What you could do instead is make the machine panic in the tolerant==1, > i.e., the default case, in mce_timed_out(). > > Basically, in the case any core is stuck and we reach a timeout, we want > to panic the whole box immediately. There's a very little chance we can > recover so panic is the only sane thing left to do. > > Ok? Do you have any strong reasons to claim that a timeout is raised by any core which is stuck? In other word, what is the probability that an timeout is caused by stuck cores? thx! cyc