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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81136C433EF for ; Wed, 20 Apr 2022 13:39:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D7D7D6B0071; Wed, 20 Apr 2022 09:39:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D2CC26B0072; Wed, 20 Apr 2022 09:39:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C1C0E6B0074; Wed, 20 Apr 2022 09:39:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id AEE156B0071 for ; Wed, 20 Apr 2022 09:39:07 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 7B4CA25903 for ; Wed, 20 Apr 2022 13:39:07 +0000 (UTC) X-FDA: 79377363534.14.28CCF78 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by imf24.hostedemail.com (Postfix) with ESMTP id E9278180025 for ; Wed, 20 Apr 2022 13:39:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650461946; x=1681997946; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=5rhMhH6TF5DbIecBIgZYcaxM4JlyAMgHd4dTkECw8NI=; b=RmQabUsltncJGkcWWfjb8+dznrOkjbfeDvwcLh+uIgeJ6bOGUkBhAbss u01EtwuH8bA5YFMsU7q0w+BGx6EHl8FlHBcFEY9rq86UcgDaJyGm38J23 Mz8w8/VMMzFqcbTii7/4ecNhWjZD+e+bPa8NRQckEZ2yPT7/fwQYwPgNe a5CwcnjDzSkTQy89xfJwU7LONTNlaSo3A4lrZ4Cv8fbrFyJrey1moaxt/ SO+QIHIR38kVQdr335xCZkOOAUEFlnWVxAGH6hM0hGFZ+/FTrD+nSY9Jf ySmp140XC/gJjSSHzSK5WidIf0RLVwhgwpVO8eaWUxJDb9xlUdd8fiJOa Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10322"; a="326925519" X-IronPort-AV: E=Sophos;i="5.90,275,1643702400"; d="scan'208";a="326925519" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2022 06:39:04 -0700 X-IronPort-AV: E=Sophos;i="5.90,275,1643702400"; d="scan'208";a="562109991" Received: from mileskin-mobl.amr.corp.intel.com (HELO [10.213.184.8]) ([10.213.184.8]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2022 06:39:03 -0700 Message-ID: <3720f7d9-a4f3-214c-1dea-f8ffc837c1da@intel.com> Date: Wed, 20 Apr 2022 06:39:02 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: Qiuxu Zhuo , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Tony Luck , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Naoya Horiguchi Cc: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , "open list:HWPOISON MEMORY FAILURE HANDLING" , "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" References: <20220420210009.65666-1-qiuxu.zhuo@intel.com> From: Dave Hansen Subject: Re: [PATCH 1/1] x86/mm: Forbid the zero page once it has uncorrectable errors In-Reply-To: <20220420210009.65666-1-qiuxu.zhuo@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: E9278180025 X-Rspam-User: Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=RmQabUsl; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf24.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 134.134.136.100) smtp.mailfrom=dave.hansen@intel.com X-Stat-Signature: 31gckc8yhb6dom3poc66ru1sdeo5cgop X-HE-Tag: 1650461944-705757 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/20/22 14:00, Qiuxu Zhuo wrote: > Accessing to the zero page with uncorrectable errors causes unexpected > machine checks. So forbid the zero page from being used by user-space > processes once it has uncorrectable errors. Processes that have already > mapped the zero page with uncorrectable errors will get killed once they > access to it. New processes will not use the zero page. There are lots of pages which are entirely fatal if they have uncorrectable errors. On my laptop, if there were an error, there is a 0.00000596% chance it will be in the zero page. Why is this worth special casing this one page?