From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C19FFC4727E for ; Thu, 1 Oct 2020 16:58:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E36E20897 for ; Thu, 1 Oct 2020 16:58:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="ll5h6dD5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732107AbgJAQ6W (ORCPT ); Thu, 1 Oct 2020 12:58:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732096AbgJAQ6V (ORCPT ); Thu, 1 Oct 2020 12:58:21 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B21E6C0613D0 for ; Thu, 1 Oct 2020 09:58:21 -0700 (PDT) Received: from zn.tnic (p200300ec2f089d001daab592cfa658ec.dip0.t-ipconnect.de [IPv6:2003:ec:2f08:9d00:1daa:b592:cfa6:58ec]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9EB5B1EC04B9; Thu, 1 Oct 2020 18:58:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1601571499; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=x+4wfkyKykDT7OmC2ro5Fq7KR9OqEfx1a1SOSUD37TA=; b=ll5h6dD5a5siocy2jE8WxL1appOI8KFgsREbcIOV5cL9PBaXbpxkdaOtkt/SZcYTxcL6PG K/zi0pYSUMcr65Lv9jTaVENoz0t8YdckZ82vKqYHljdLjeqHeE0NQsF/rdgwByS07e5NDC k7KeRIlN+g5rrbIjM7K2rVWxeRD4tmM= Date: Thu, 1 Oct 2020 18:58:10 +0200 From: Borislav Petkov To: "Luck, Tony" Cc: Corey Minyard , Andy Lutomirski , "linux-edac@vger.kernel.org" , Corey Minyard , "hidehiro.kawai.ez@hitachi.com" , "linfeilong@huawei.com" , "liuzhiqiang26@huawei.com" Subject: Re: [PATCH v2] x86: Fix MCE error handing when kdump is enabled Message-ID: <20201001165810.GF17683@zn.tnic> References: <20200929211644.31632-1-minyard@acm.org> <20200930175633.GM6810@zn.tnic> <20200930184906.GZ3674@minyard.net> <20201001113318.GC17683@zn.tnic> <20201001134449.GB3674@minyard.net> <20201001161645.GD17683@zn.tnic> <6c6238c0088747a994a2bdce38ad0242@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <6c6238c0088747a994a2bdce38ad0242@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org On Thu, Oct 01, 2020 at 04:29:49PM +0000, Luck, Tony wrote: > >> I was thinking about this some yesterday. It seems to me that enabling > >> IRQS in an MCE handler is just a bad idea, but it's really a bad idea > >> for kdump. > > > > I don't think this code ever thought about kdump. > > How useful is kdump after a machine check induced crash anyway? > > kdump is useful for debugging software problems. There are very > few ways that a software bug can result in a machine check. There > are many ways that a hardware problem can trigger a machine check > and crash. > > So it would seem (statistically) that the analysis of almost every kdump > after a machine check just says "h/w issue". You certainly have a point. The only use case I can think of is being able to read out the MCE signature from the first kernel's buffer - *if* it has landed there - to at least know what it is that caused the explosion. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette