Received: by 2002:a05:6a10:1287:0:0:0:0 with SMTP id d7csp3978725pxv; Mon, 19 Jul 2021 13:28:20 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzYst7G+4m4BnKaG8zXvT1XlG7+GIodp2hhmNsb5C56EUe/Cr2rJ5EHRpMQyY7KauNbPYCr X-Received: by 2002:a92:cd8a:: with SMTP id r10mr17181216ilb.287.1626726500189; Mon, 19 Jul 2021 13:28:20 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1626726500; cv=none; d=google.com; s=arc-20160816; b=l/lKatGjZX0QdUaCpAu8httK8X1WYkJQA6L5Qh7SK71DhS4h2T8J2xakAf4hf+OHR2 +o3ZMtedJZfY400WPtBS7L5lw6yMh5ET3sZ98F+zhuin5lZ0G7onanopo2rEOjDVDnor YetXqytJHilHaiHEnjLIeuNQ+u7kiyQWWvhrCYY73BgsqkF1eqyPWDdnKvAtcyHnZ9in j6Q0QQEbEref8/Zw8euChrjrUmwqFXT+l66x1LIVc1F+kqdoVPQSqd9bSiylbOP/klTR Qgctm/OPT5iVTXEh7fGCXfVNDygcv7sOm19UoJJWxvHuBZmQ8XMvDI1TlaXRT9M3TYu1 m+MA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:autocrypt:from :references:cc:to:subject; bh=WWSPaWVD6r5X/JuoY7qzj8Pt+f4vTJaWOCvQZk3xrNU=; b=AYO9yPQ/Cf/N86dOG8FdRhxyLZGvXsccCpZjIY7H8HoOqGa6sZOtkdNMFZhKp7usMp ExuB7w09Ap6Qxuo1RM0yjMp1+FUuj/iS8Rj5FU4LW8kMFqOz4Mxs3sdLsX2EU4JV3EPn jl4cFJoIhYgGKg7dqkBYnEsyt85e/qxGQ/OZ9gUFRar3lUYYJRWix+KkNOzxNFkf/KM3 XPC2JD6XrwIXneCKsOyrljbQmF7nu7t7bXbqdYvjH/+DCSBe54NQ1IpH4B8qOqONw62r 0s8WLkr2ElKI+TgIyvfy3mrxcK8dKheTRs7mq3XJo4TnsYpWuxJF8XQVXg8rMsm63b38 vAnQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id 10si21001628ilq.145.2021.07.19.13.28.06; Mon, 19 Jul 2021 13:28:20 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1385675AbhGSTHA (ORCPT + 99 others); Mon, 19 Jul 2021 15:07:00 -0400 Received: from mga18.intel.com ([134.134.136.126]:19106 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1384906AbhGSSjv (ORCPT ); Mon, 19 Jul 2021 14:39:51 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10050"; a="198389184" X-IronPort-AV: E=Sophos;i="5.84,252,1620716400"; d="scan'208";a="198389184" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2021 12:20:27 -0700 X-IronPort-AV: E=Sophos;i="5.84,252,1620716400"; d="scan'208";a="657011128" Received: from mwlibby-mobl1.amr.corp.intel.com (HELO [10.209.98.141]) ([10.209.98.141]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2021 12:20:26 -0700 Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time To: Rik van Riel , linux-kernel@vger.kernel.org Cc: Dave Hansen , Andy Lutomirski , kernel-team@fb.com, Peter Zijlstra , Ingo Molnar , Borislav Petkov , x86@kernel.org References: <20210719150041.3c719c94@imladris.surriel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: Date: Mon, 19 Jul 2021 12:20:24 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210719150041.3c719c94@imladris.surriel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/19/21 12:00 PM, Rik van Riel wrote: > In a large enough fleet of computers, it is common to have a few bad > CPUs. Those can often be identified by seeing that some commonly run > kernel code (that runs fine everywhere else) keeps crashing on the > same CPU core on a particular bad system. I've encountered a few of these kinds of things over the years. This is *definitely* useful. What you've proposed here is surely the simplest thing we could print and probably also offers the best bang for our buck. The only other thing I thought of is that it might be nice to print out the core id instead of the CPU id. If there are hardware issues with a CPU, they're likely to affect both threads. Seeing to different "CPUs" in an SMT environment might tempt some folks to think it's not a core-level hardware issue. If it's as trivial as: printk(KERN_CONT " on cpu/core %d/%d", raw_smp_processor_id(), topology_core_id(raw_smp_processor_id())); it would be handy. But, it's also not hard to look at 10 segfaults, see that they happened only on 2 CPUs and realize that hyperthreading is enabled. Either way, this patch moves things in the right direction, so: Acked-by: Dave Hansen