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=-5.8 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 2F2A6C433E0 for ; Wed, 20 Jan 2021 12:53:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCB9023355 for ; Wed, 20 Jan 2021 12:53:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726396AbhATMuo (ORCPT ); Wed, 20 Jan 2021 07:50:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389672AbhATMTE (ORCPT ); Wed, 20 Jan 2021 07:19:04 -0500 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1536C0613C1; Wed, 20 Jan 2021 04:18:20 -0800 (PST) Received: from zn.tnic (p200300ec2f0bb0007fac97ee58c503f0.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:b000:7fac:97ee:58c5:3f0]) (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 1B40A1EC02FE; Wed, 20 Jan 2021 13:18:19 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1611145099; 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=1XfKvTlUd9M2I3j5DZ6ix3W+3HI+vf6zvmLqPMZR2eE=; b=HXNQWzSWiBIqaFIUkL5enVXRU801d3U+sN0n5ZOaG0O8ii7YtMc62jYpy3DQLo6OKZxCtD W98w3yO72RcqY66K04zMxBxY22EfiWLALoxd9sFXJfyH4prxRLRDI4r58t+MzZPI0HcFSb 7NCjTCF82FAgOEhE54yIxGv8j5s3jgc= Date: Wed, 20 Jan 2021 13:18:12 +0100 From: Borislav Petkov To: "Luck, Tony" Cc: x86@kernel.org, Andrew Morton , Peter Zijlstra , Darren Hart , Andy Lutomirski , linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4] x86/mce: Avoid infinite loop for copy from user recovery Message-ID: <20210120121812.GF825@zn.tnic> References: <20210111214452.1826-1-tony.luck@intel.com> <20210115003817.23657-1-tony.luck@intel.com> <20210115152754.GC9138@zn.tnic> <20210115193435.GA4663@agluck-desk2.amr.corp.intel.com> <20210115205103.GA5920@agluck-desk2.amr.corp.intel.com> <20210115232346.GA7967@agluck-desk2.amr.corp.intel.com> <20210119105632.GF27433@zn.tnic> <20210119235759.GA9970@agluck-desk2.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210119235759.GA9970@agluck-desk2.amr.corp.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org On Tue, Jan 19, 2021 at 03:57:59PM -0800, Luck, Tony wrote: > But the real validation folks took my patch and found that it has > destabilized cases 1 & 2 (and case 3 also chokes if you repeat a few > more times). System either hangs or panics. Generally before 100 > injection/conumption cycles. Hmm, that mce_count increment and check stuff might turn out to be fragile in the face of a race condition. But I don't see it... > So if you see anything obviously broken, let me know. Otherwise I'll > be poking around at the patch to figure out what is wrong. Yah, some printk sprinkling might be a good start. But debugging in that atomic context is always nasty. ;-\ -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette