Received: by 10.192.165.148 with SMTP id m20csp648539imm; Fri, 20 Apr 2018 12:55:11 -0700 (PDT) X-Google-Smtp-Source: AIpwx4+7LSo/HdAwamTIQHJGSkTHsfHYFihsDNbIF8xVi8BqwVaBP7k1U7iy6lFvdlMppb1T5UCY X-Received: by 2002:a17:902:8501:: with SMTP id bj1-v6mr11200810plb.239.1524254111084; Fri, 20 Apr 2018 12:55:11 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1524254111; cv=none; d=google.com; s=arc-20160816; b=v2mo6l7Pip0yUxRw2Q9dN117qaVCgE3fzLslZvxiIMNKRiMyy4um5mJIXVy2fhB7Ty ncWMsT85Szg3onhEOKgjN5OGCyx6k3Epv6Jcud6TKydArC0URetI53+zZP3oAiJAmvws y4ckDIxbXmp4gS/tv6KE3/ehUI+E75lGDu1quAeepF3nG9EV+Lx0Ju2OpAZuGb42ubzX 9YoBhgiTFyQOPQJsGyqeUYIDp39jQ4K9+jB6vhFu/Qq4AVUsr2Tx/C3unqhfWPTJYMdN +12nJxFg2ehbhDj8xzU3H31o/sZbTi4ICMvOuBQcCMyI2m06osCle990zHJZd1/1NOoq DbLQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:spamdiagnosticmetadata :spamdiagnosticoutput:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject:dkim-signature:arc-authentication-results; bh=HR8OTkjmFFBKdHV0+VpI0S4oxCE+Bsgj4KPqnODyyn4=; b=z2zC0PtL1GEfh6DV37qft261MDOvq2wesY72KJojMck244yszcdMlcZ09hzVxYgH8y JmgaC/TUC2VMGsAX8ItZL5AH1GxhE8Pt7VPdgwnWFlo+v9LaGlSMXVMEtaoDrOsGOBlP Uppaj/jqnVoea1GnqY5ujop6W5dzoDYY5K5Orn9s5428SNgKQ6V03HKNwDlZ1sgUm9N/ f3gjw78qNdn/qbYTXkD6uSyyn6IQsJly7/S3wtTXaj1PtEvBPYEvarqwjam+v4k3uxsi hksNSrDuWLCu5VCUXDOQKGkgDYce0WqzM7G25V9JfDlbwza1mg6Fo3gmTkCrWEU+dZDl GnqA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@virtuozzo.com header.s=selector1 header.b=RnPr/qZn; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=virtuozzo.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id e98-v6si6300608plb.273.2018.04.20.12.54.32; Fri, 20 Apr 2018 12:55:11 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@virtuozzo.com header.s=selector1 header.b=RnPr/qZn; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=virtuozzo.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752096AbeDTTvU (ORCPT + 99 others); Fri, 20 Apr 2018 15:51:20 -0400 Received: from mail-ve1eur01on0101.outbound.protection.outlook.com ([104.47.1.101]:53792 "EHLO EUR01-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751159AbeDTTvS (ORCPT ); Fri, 20 Apr 2018 15:51:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=virtuozzo.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=HR8OTkjmFFBKdHV0+VpI0S4oxCE+Bsgj4KPqnODyyn4=; b=RnPr/qZnKpQDX7sb9kWki8VqbIC3YppN70plYnpVc5TYIyC/kBUDsYf+5jkSkOQFgXjEYaLm3BL5QrbEZA+gxiNeYRCj3wKZ70AOOdYSnN2W85uTHg82cwfE6sIR85WB7o8a9jP/o7mnWkZ6jQm14j6XkAatpHJ5GFcUyQ5WZzM= Authentication-Results: 01.org; dkim=none (message not signed) header.d=none;01.org; dmarc=none action=none header.from=virtuozzo.com; Received: from [172.16.25.12] (195.214.232.6) by AM6PR08MB3255.eurprd08.prod.outlook.com (2603:10a6:209:47::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 15.20.696.13; Fri, 20 Apr 2018 19:51:14 +0000 Subject: Re: [kcov] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] To: Yury Norov Cc: Fengguang Wu , Dmitry Vyukov , Kefeng Wang , linux-kernel@vger.kernel.org, lkp@01.org References: <20180419030135.nn454aqxlqdwe7ah@wfg-t540p.sh.intel.com> <20180420164523.zrjykc4jhx73cfjo@yury-thinkpad> From: Andrey Ryabinin Message-ID: <2c5e3996-d50b-416c-92aa-a554085cd656@virtuozzo.com> Date: Fri, 20 Apr 2018 22:52:07 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180420164523.zrjykc4jhx73cfjo@yury-thinkpad> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [195.214.232.6] X-ClientProxiedBy: HE1PR0301CA0020.eurprd03.prod.outlook.com (2603:10a6:3:76::30) To AM6PR08MB3255.eurprd08.prod.outlook.com (2603:10a6:209:47::20) X-MS-PublicTrafficType: Email X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(7168020)(4627221)(201703031133081)(201702281549075)(5600026)(2017052603328)(7153060)(7193020);SRVR:AM6PR08MB3255; X-Microsoft-Exchange-Diagnostics: 1;AM6PR08MB3255;3:B+vzqrSwGMIlk44uirQiZClM+2fkSTwDHREgvlf3bAjvbgrgo2ef8uXFREWlaJPVGhPYdrHyibrg7sw0enTCkhlyWqRVruqiDN2mvSbHqRjj/ch7RM/g8KNsF9CngsIGJ+vu6I9q2EOWSQZFOvyRpBPTgVydRs9lEjSvUlzW4xrZNhSoI3zVD7sfxFIaYIRwuM3lVIt9xH2V2eDXHgsANH4ImhYUooKOVouRrOTZvhucWPNaM+Nsgm1diC3E69zH;25:rjx2z6XAhSvtTlDapzIR+stKklzLoleZKKZAPtOaMXK+h5bKudDNunnasPRePBdi5xpKShpVXw4BbOcMRxELlEQxP6ZhtUojirDTTC9ZecXo4TN5sJWlLQsOIPkcM3heQiX6DHxa5RAX+qBKG7rFpA3NQICNDSG45hAF08n/G3zOGUMHBZEDL6Sc0iXnm7vm7k0RLgrarTjl+PENIOC7aE69ak9QTGEuLtX7iY8LhWpv3Ebuuzr37IQ/D8jRpQI/v/swqcX0ZtauHozrKJ+Krdh0Pp32dXfmfvGZOuo8oeGrIHfpBwtYZMTMOq1S53q6vnl60lU3Yf1xPJDaictokQ==;31:s4hBa76ALp05Z2EOrNDI6+blIk4aJ7toFBSLHW++fQBzqubf0qGMqRT+KKZHW6EaekzLH+lFQvXcS94NxjzzmZXxKQqLZFfqLnG99Iok9wPX7bIG6acGW6R3VFQZ6T08j1Gxa/o/0MghPF9qBhk3ME5MnEW18Izb3T57MryqVqrGeCHPOmzpE83xbD8SOdraqr5OtxpN/Ck8khsfAGMGLoK2A2rdafW8lMkJTaDhQ70= X-MS-TrafficTypeDiagnostic: AM6PR08MB3255: X-Microsoft-Exchange-Diagnostics: 1;AM6PR08MB3255;20: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;4:/RLal9MrR61jDxtNg1UVHHe3gc1nImhgXKorzRKUoCbtZdy3ErfLJI1o6K4l8WuqQBJQ+C/6GSAHlF1p93waquXqdnE1Me0J8hrJ1qDQBYuQ1r5oB8HxsE/slbLK/Q5mJ7EY8zEkxQnCsnfPgqZQNLYVni7BxOps/vG9X1anNxZnDoXiWYnjsXp+u+56EIT7qy8O4RqTUCkK0mkqD8Ge/pkd61zuJ1DfLfwM6IMH9qHqPYqfk0EaKtxk4Dc+anbu5K8C5AMAhwm9tEAkv5toWw== X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(6040522)(2401047)(8121501046)(5005006)(10201501046)(3231232)(944501397)(52105095)(3002001)(93006095)(93001095)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123558120)(20161123560045)(20161123564045)(20161123562045)(6072148)(201708071742011);SRVR:AM6PR08MB3255;BCL:0;PCL:0;RULEID:;SRVR:AM6PR08MB3255; X-Forefront-PRVS: 0648FCFFA8 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(39850400004)(39380400002)(366004)(346002)(376002)(396003)(69234005)(81166006)(76176011)(305945005)(66066001)(47776003)(4326008)(2616005)(77096007)(956004)(26005)(53936002)(11346002)(52116002)(230700001)(2486003)(8676002)(6916009)(65826007)(52146003)(186003)(23676004)(6666003)(446003)(6246003)(16526019)(25786009)(6486002)(7736002)(2906002)(8936002)(50466002)(54906003)(3846002)(6116002)(316002)(36756003)(478600001)(229853002)(5660300001)(16576012)(31696002)(31686004)(55236004)(53546011)(386003)(476003)(86362001);DIR:OUT;SFP:1102;SCL:1;SRVR:AM6PR08MB3255;H:[172.16.25.12];FPR:;SPF:None;LANG:en;MLV:sfv; X-Microsoft-Exchange-Diagnostics: =?utf-8?B?MTtBTTZQUjA4TUIzMjU1OzIzOmlFeDUwQ0V1YnkyNEVqVTVqMzNmOWJKWjhj?= =?utf-8?B?clYyeGtoUEhwVFovakhJVUJnTDVFTkpYNDQwaGl3amFzcnZIaDB0dGpyVjMy?= =?utf-8?B?M3B2V0luVVpTQUJjN0Q5eFNlanlmWnFQbnZOWGZqUm1tRUJyNlQ3SmdLZnc5?= =?utf-8?B?MURNT0FUVFA5M3VWblQweCt5azVqVjhYaGplMTFGWmV5QjdRbXovb2VyZ0FX?= =?utf-8?B?YU1BQjJMK21oVzFxYmpFbExNanV5RkVFcElmOGFVQjZQcFJHZzRjZTl1ZTEx?= =?utf-8?B?SW1Gc0ZQQ1JOTFF0SEVUUHA0T3laQUVLTEJQOXg3MmpWZ29GSkNrLzN5Z2FF?= =?utf-8?B?NWJCNEsyaUNwYmlpOXpzeVBmcXhObEV3b0NJWUV2U0RGbUk5MEd4cXFZZ2F4?= =?utf-8?B?SmFtZ3R2NVkveVRHNXBvQ3B3dXYyUjZGVFJxbFpLWEw5aXR1emQ5L3REaG9w?= =?utf-8?B?S2llb1hIaTQ5d3grWS96TkpUOW1DY3QxWmo2cm9TRlJpdjdaWCtKN0V1cFE5?= =?utf-8?B?M0NOUUFTNlJsQmhqSzA4RXJFMTZnYVNDOEdXRDlMVXFYajhiN1hTZ1pRdW5L?= =?utf-8?B?Q3dUN3FKSTZHRFNrYUc5MGZab1BWQk1TckxMS2dqUlBiQTl0cTR5OXlXZFh2?= =?utf-8?B?YUJFR0MrQXRPd3ZKRjE0bis0Lzh5WXJZT2hzRmsvcndUSlRGV2tWRmNuZnNS?= =?utf-8?B?bHNSZFJWYmJOWHpoTFpPczI1c2RHYmVSRFc2eTByWmFod1VteVV4c2FwREJI?= =?utf-8?B?ditveHdVR2ROTjUweUw0dHZDNDRMOHFoc0ZYL2FWT2tkaEh4UmhITXZmcnBI?= =?utf-8?B?VE05UnU5MUtuOCtycWV3WElWVkJubjVpQ0FLdkFpcUx2R0NFcWZGZVF1YURO?= =?utf-8?B?WklTaVlkMFRsLzRWMFlBcGQ2azlUQ0VSY1NoSUh1RnRvVVZFbFh6UTF1Z2RO?= =?utf-8?B?eFdob2pUMUlUbHMzSGx6czc1dTZja3VkWndjYUtDM2hsS2pOSWpNdmtZTDJu?= =?utf-8?B?V3dRSkd5Qi9Ed09jV1dnNmdkN29XQTZEbjMvelUxb2M2MUM1NVYvd3hCRGYr?= =?utf-8?B?M09Wd2k3YjQwRlkrR0Ywamd5NEg1YS9nV05ybEhIdnNDOUl3ZEJaODhtcUVQ?= =?utf-8?B?MFVXeWRwdjljblViRm5HVW5vRFJsTWROaStKbFNLUTVjUm1LUU93cmFTU0Zw?= =?utf-8?B?NUthaEtSdXJCVHF5MnRRa3IrcWNBYlZ0cEJva1ZDSkgvUjFFMisveUhoTlV6?= =?utf-8?B?bStMRXh5RjJrdXVRVEcrQXlIOUNxbnNKdndRT29ZUUFPejVjMkdqL1JoL2Ri?= =?utf-8?B?dGprRmQrbld2U0JoRy81cmNVdE5zUkZ0VzhJSFFhY0R2RjNKcUdGcStWVjZD?= =?utf-8?B?a1NOZDNXUkhHZGRXWkw0a0hBWEx4V0ZXZVBzRDF5ZVZsckExTHRNdnRlOTBZ?= =?utf-8?B?NXNmbnRsOStqZ2s1aVZzT1VZVmdyeHZEOTQ3T1FKbWlxR1ZwZFF2Mno2VUtC?= =?utf-8?B?c2d5cSt2elpIcU5XZmthajhpUzhDTk5FUWk3UGl0YkFvZWtsR0ZPdzNneXBY?= =?utf-8?B?SVp2QkkweS9XcmxiTnl3cGphNmV6aVR6K21zaS9TVUZKdWR4WW93M3U3dVA5?= =?utf-8?Q?WvTWVxCKFcW7tLTskBW+?= X-Microsoft-Antispam-Message-Info: vXd/pNcJJnXnN8XV0PeEqBDLoObxw4qlIw640evxmyrV4Q1VXA+smq5uiixpI5amOucKUbOY7kVEfjdxtCjLvKj1qhDtZgabBNAfCP8ensBTyA0s5MVL/9PyqxUn+CdMQ5nNvagYnRC6TYzEmm3AAcvnAt0CU6Yqk+QJhG7rXCSq2gMcbfiXCJeRquhCPlSW X-Microsoft-Exchange-Diagnostics: 1;AM6PR08MB3255;6:IMjfwV/ysUUU4TfW7XzxyzVJoKV+sU336P+EetoOiIfC/SuB3ZCRGmsKueVmFElpWaNxb9veTIOCKnM2NvcE7AIgnBg5+Xc07lSDCIIc7uystr9SK/TE3IQxkk43YQya2QJ9KGdPuuqW0ZHjsHPiS6RkK8u231hsuHHNfvmjqcIaITxuj0QdRHqsuGYKQOwXq2WJaErjLB+WKlVwXvZopRra7sTk5hQkkYZxlEzXsBg22BjJsTkWco4vOYBXrIEtmBCK0gu/B988kClEsK1RDn3A0XOf06jiAj7WTnlwW36CXrzpYwOEMktLr/tHkaR+rhKjnJYkUU9RHGQDukDWZ6Fr1WDU985HftwTlRDC+WCAFJkQHl9GRaf6kD8JXYdpmn+eCzX9duZ6+uJBEfNI7jN3HMyJ38ByctvGE1uigKzaZq3xnidmrGsgPwAi3juA0PMpcvna/1UYGCfcMMls5g==;5:L2hwLt8XZ/zKv+Zq0PtjwOb2LkBOvXAsniAb+an9SSA3X+cO0w4dK+XYsn9tCmuz2CJJJhwNFIfgG/YxRCKVkGoXSrM8uBGEIitLQH0udm3G6QSmvk7rfkPuHLZbfby8IiNEre1p2fEPzmkmM3ay+fLWiamr6VXlKKqJDlRtFoo=;24:9U6oYePSgnaJSH4p1fUwVltqrgvZUvF7uk1S+3q2xmt2Keyk8Qb7kONrKQJ1/G15w2OEyZhXQW9uLYyNP5293LoOemoEBjV+q+yDVx//R/U= SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;AM6PR08MB3255;7:la0vZFrRayH+uycMxTgQiIEUsPR9Ni9mLv+BizJ4GBIfc2BrHEwBLyU3puFXlG1jvCPhdIAuBQyfohAJXT7k8MA0YUEN5aCiVl2mIhimPjtEZA4kt7jJ3YIrF9RKH4+YzpXBsF2Df0v/9345e+bGVQGdr3A0H88O2y+DNt/KoAm8ra5Nx034Jn/0uam7jPbhpKA/TzVSWvmYvCmsXJ2gr5T8S/Ub/At+TggvSn9ysFoUkkXeVlREIlopgMLR208r;20:zXJo4ivQauF19l/fjFLhxYnArIIk2t8zaMDWsArLijs8FNBBgyCOSHgwm3xzqYId+L7V/PjyLFSKSvkV+xwpA/7fvvAl74kXI0S89f06nUeeKz5zs1KXp+3OA8Eh1QIOUE2c5S2EUW5K2V2V+zk8c0jkCNmFNq5M0IAsO3iZSCk= X-MS-Office365-Filtering-Correlation-Id: 904a3372-8382-4035-b288-08d5a6f813c2 X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Apr 2018 19:51:14.9232 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 904a3372-8382-4035-b288-08d5a6f813c2 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR08MB3255 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/20/2018 07:45 PM, Yury Norov wrote: > On Fri, Apr 20, 2018 at 05:08:23PM +0300, Andrey Ryabinin wrote: >> >> >> On 04/19/2018 06:01 AM, Fengguang Wu wrote: >>> Hello, >>> >>> FYI this happens in mainline kernel 4.17.0-rc1. >>> It at least dates back to v4.8 . >>> >>> [ 25.697463] >>> [ 25.697463] Start testing find_bit() with random-filled bitmap >>> [ 25.736615] find_next_bit: 30203201 ns, 163965 iterations >>> [ 25.783266] find_next_zero_bit: 45554622 ns, 163716 iterations >>> [ 25.832480] find_last_bit: 48003878 ns, 163965 iterations >>> [ 52.050031] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] >>> [ 52.050031] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.17.0-rc1 #210 >>> [ 52.050031] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 >>> [ 52.050031] RIP: 0010:__sanitizer_cov_trace_pc+0x65/0x66: >>> __sanitizer_cov_trace_pc at kernel/kcov.c:111 >>> [ 52.050031] RSP: 0000:ffff88000fd43e40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 >>> [ 52.050031] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000017 >>> [ 52.050031] RDX: 0000000000000000 RSI: ffff88000fd3e000 RDI: 0000000000000002 >>> [ 52.050031] RBP: 0000000000050000 R08: 0000000000000008 R09: 0000000000000000 >>> [ 52.050031] R10: ffff88000fd3e000 R11: 00000000222e2c32 R12: ffffffff85565d90 >>> [ 52.050031] R13: 0000000000030f80 R14: 0000000000030f80 R15: 0000000000000000 >>> [ 52.050031] FS: 0000000000000000(0000) GS:ffff88001f600000(0000) knlGS:0000000000000000 >>> [ 52.050031] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [ 52.050031] CR2: 0000000000000000 CR3: 0000000003c6a000 CR4: 00000000000006b0 >>> [ 52.050031] Call Trace: >>> [ 52.050031] find_first_bit+0x66/0x7c: >>> find_first_bit at lib/find_bit.c:106 (discriminator 1) >>> [ 52.050031] test_find_first_bit+0x3a/0x93 >> >> >> I suppose test_find_first_bit() needs a little more than zero cond_resched() calls. > > Or just decrease length of bitmap in this test. find_first_bit() takes > lion's share of time of the test. > Yeah, that would be better. > Start testing find_bit() with random-filled bitmap > find_next_bit: 240043 cycles, 164062 iterations > find_next_zero_bit: 312848 cycles, 163619 iterations > find_last_bit: 193748 cycles, 164062 iterations > find_first_bit: 177720874 cycles, 164062 iterations > > I'll test the patch and send it soon if you OK with it. > > Yury >