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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82E0AC19F2C for ; Tue, 16 Aug 2022 05:33:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230310AbiHPFdx (ORCPT ); Tue, 16 Aug 2022 01:33:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229566AbiHPFdh (ORCPT ); Tue, 16 Aug 2022 01:33:37 -0400 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (mail-co1nam11on2048.outbound.protection.outlook.com [40.107.220.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3A17118DE7; Mon, 15 Aug 2022 15:12:24 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=NbNNwUtJs3Eu2qK0+LV4RI1IPvE3AMiH9UkCRVBWrt8JcwQb9bZ73glOFpfggq4dn4maryfkbzBWu3WTpt2LJmK9HEXSYRVovpiFbI2vh7UBuZkJLgQTrIINBKDaACtHl9/sd6XTQF12tSCLQRKttbWpNo/Ph9++81EVrLSzUMNA4lMNwapWL/UiytaNdGqD5I9wppN7Zwf1Lt2JYPGMMszooT8TsmpAXPUO0rpMLxk6NxnjlgDXRHOo0xJRFm8NK/0IQp0RrlCmCAoIfQtLO/hEEuk2iTaxdSIWNanHiIa9woBAQo5zJUKDhmc/jM5XMLcQ/CCNJVphFun353RwIQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=ck+VCzPdVu3/y3LimiewTjanc97eXGBhENYeTvKUq50=; b=Qkpyrfi6qBqgsyrCVtayfrgRReKeirPjX/W9zagbEMJphITe3Yr5cCVKU1J5S+A3adP8PE4k+uickVBxLByHCMUtIlznYrJKkKD48fRbxkGjJXwx1ItTCb4M/OLaPgPsm44Omk+VqjSnwzeKVYFa5YcOxy4eRrI1VcATaajYHUkunojsaGgzoJkmYFRA2SwYtbSDz4tf3kEteu6B04f7ywOTNznv73Y/VbMWUaIPTCMjYbDqwcvdS/nYXY8Lr4vpzPhkO3HW3fpY3c6Gkx/O5tv6YXvf4hNXsIjCHqKtIvfLsWH76ekbE/D/xdvr5lH4SGe7c1Oeggk1dt4kMs3v1w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=ck+VCzPdVu3/y3LimiewTjanc97eXGBhENYeTvKUq50=; b=rAiuBuJsa4mDJovTyTYi3dAILOZ3yM0p+xRYMY5u8mqd0gT28Zq+hxF90n0b7JOY928Gqz9HzXQIyyPqDiIosMJjIFFsXnKnvdm4jhdERBXNlzLNLgNvi9IYqfaQxO7doutSL2ynHTTJhRKMLintyvdAm2Ntw3J5r2KyR/nVRNr4WXeNp0olmPB5cakdA7IXWt1gepoMQ+y8ocW7FS32RAc1yEHp4kvesqxw14r4woOx8ptzDITOt99E1WjWx1K4NuwQEduX9r59fh+KNGVW1gDC2eAIcBVnFkQHZx5hHRy7QDjhyXYzSekPImASUVq0MPkMSiV7zLHUlirIaofDWg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from BY5PR12MB4130.namprd12.prod.outlook.com (2603:10b6:a03:20b::16) by BL1PR12MB5946.namprd12.prod.outlook.com (2603:10b6:208:399::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5525.11; Mon, 15 Aug 2022 22:12:22 +0000 Received: from BY5PR12MB4130.namprd12.prod.outlook.com ([fe80::508d:221c:9c9e:e1a5]) by BY5PR12MB4130.namprd12.prod.outlook.com ([fe80::508d:221c:9c9e:e1a5%9]) with mapi id 15.20.5525.011; Mon, 15 Aug 2022 22:12:22 +0000 Message-ID: Date: Mon, 15 Aug 2022 15:12:19 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [PATCH v2] sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() Content-Language: en-US To: Mel Gorman , Ingo Molnar Cc: Linus Torvalds , David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Andrew Morton , Greg Kroah-Hartman , Axel Rasmussen , Peter Xu , Hugh Dickins , Andrea Arcangeli , Matthew Wilcox , Vlastimil Babka , Jason Gunthorpe , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt References: <20220808073232.8808-1-david@redhat.com> <1a48d71d-41ee-bf39-80d2-0102f4fe9ccb@redhat.com> <20220815144143.zjsiamw5y22bvgki@suse.de> From: John Hubbard In-Reply-To: <20220815144143.zjsiamw5y22bvgki@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR01CA0018.prod.exchangelabs.com (2603:10b6:a02:80::31) To BY5PR12MB4130.namprd12.prod.outlook.com (2603:10b6:a03:20b::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: dea507ef-8667-40b9-ddaf-08da7f0b39bc X-MS-TrafficTypeDiagnostic: BL1PR12MB5946:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY5PR12MB4130.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(366004)(136003)(396003)(376002)(346002)(39860400002)(38100700002)(31696002)(316002)(86362001)(66556008)(36756003)(8676002)(66476007)(66946007)(4326008)(83380400001)(6666004)(8936002)(6506007)(6486002)(53546011)(478600001)(5660300002)(7416002)(2616005)(6512007)(186003)(26005)(54906003)(110136005)(4744005)(41300700001)(2906002)(31686004)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZVM5cmgza29qSS9GYzFNZ2dpMmVOSkYxWlZvTE45ZjVvNnlYYUZyMFBhSG0x?= =?utf-8?B?ZXA2RWx2YzJIdEk1S3lwQ3JwR1B1Q1liOVVlUUhNMDUrb0J0OE04K3A0Umxm?= =?utf-8?B?bDNJU2J2VloxaEo1YzB1dEJhTUF6enlkOWU4bjFpMW1MUzRUbjVWRk0yNDVJ?= =?utf-8?B?WlhXY3M0OGxYSHVxN1dBZmxxQWVXVlFWdVZXQzNzaFFzUkh1YTFyVkNXN0Fv?= =?utf-8?B?VzB2ZTdmU2JaUFlXREhSNHUxNlA1QytadXJ3ZUlJaUdZWkNHSG9sNnNIUFh6?= =?utf-8?B?T05WeUJiZzhROWF3RUV6RzZsOE1tUXpsRjRXVHI0MXpRNUUwbUxiVnM3eHJT?= =?utf-8?B?ZG1LUldlRExFdnJzNWNIMVlWWVNOTUlOWGduSkFVVUZjc3NKdnVMOXVZZG9n?= =?utf-8?B?RmsydmNSZ0l2amQvUkFES2dGaTJmY3pQY01KSWYxb0hyeVJHS1Z1UUZONDdZ?= =?utf-8?B?MnFZTzhlSFBFZHBmQnljK1VWRGdKZDhReVBGeklCU1VuTWdxdWpLeURrZkZw?= =?utf-8?B?dkN0aVVwYmxrSWgxZ0pkeE1TWk5YVTh4U1QxZTcxRCtXUW9NMkRUMHBNaFlr?= =?utf-8?B?eGVaSVdNWDRLMXpsNFhDT28vOGIxaFRGZFFyZy9KU2tvcTY0NlVjczc0aHVT?= =?utf-8?B?bmNKMGFVTVlSbWJPRlJTSm94QjFFTWN3TlA5NitGU3RCbVRyQWtIVHlpMGJw?= =?utf-8?B?ak00NWZDRlBxdXZ5V0RpUUYzM0RLbFNIN2VRdkptVDJxNC9INU85YmpjRzZG?= =?utf-8?B?ZjdyUG8vQWUvdU8xSGk5YTVjcGtSd2x2cUNmSVZxeEVhOXJtL2w2OTJyWjdk?= =?utf-8?B?TTNEYmdqZ0tXTjVEbG1Hb1E3LytkR1JqVzcydUw5Njl1WHFkQW1RUDRkcmVQ?= =?utf-8?B?bi8yVXZMdEFic2NpSUI0NXdacHNqdk5xT2lxZzNzTTUwcDBVcFh1QkM1OUt6?= =?utf-8?B?VEVwTklYc2Y0N0RhaS9CZHRUdXpaYXJsSWpJdEcyeWhkeUhRaFc3SjIzSHEv?= =?utf-8?B?WjR3ZU5TNWs2TTdLbHBKTTRnV2FMQkcwMXo0ZjRwWHR5b1NDVWE4TncwOUVz?= =?utf-8?B?cGJFUGZUdXNZWE1uVENIZmoyTVB2NzZmVGNhNFNtQnllWjA5NW1uNmkwdkRT?= =?utf-8?B?Z2RNTVdpQWdPdU4ySTNGTnJBZVUyb1lkb2dzTGhoY0JoT3B5OTIrQmVEK1Vm?= =?utf-8?B?RDZYNGlPeEEvTUowUG9RMzVJaTFOeUxhUlJqb05mTWNnc2NIYm1GU2N4c2dO?= =?utf-8?B?VGFXdkJ4Vk1PUTlFN2xZTm5CUUpJa1ZBYlVGOUkrQnRWckg3UHBEcFJkdC9r?= =?utf-8?B?KzEyMlR0ZmtCNTRueWl5Q3hPQmNXSnp6ZHgvemJQZmdLYm1DdjRBWXNpOHRp?= =?utf-8?B?eHcxL3l3TUVJK3V0NFgxVjBDWGhRb0F5VDA4dldLcWJHZlJUcmNTeGVvMDJZ?= =?utf-8?B?VWxiUExNZnhWTWlrcTZXN2ZjY0hpQWtLNzlFZGx2NDlkbVhXdHdXeWdLVVE0?= =?utf-8?B?WUxVVVNuQVNrODNWZ1VnZzlselFPZTkwczhqbW4vSkZTeXd5ejR6RFJ0Lyto?= =?utf-8?B?djNOb0h2WU1hTWVoN2JDSnZERmdTTkZ4VE5Pc3FFdjAyZDBQYU5oenZGeEVF?= =?utf-8?B?UDBrMXBUaklnRSsyeWFFNmZ2K1YzemdCNFlWdlJBV3hNRlhaZ2dUVSs4QzV2?= =?utf-8?B?eGxuRm92YWxrbzlBclZiTm9weURybThOb2p5eVdtam5EWU1pV1RWOUNHa0V2?= =?utf-8?B?SW0zNnUyREhoVXVwbGZaTnpub2VXZE1wYUdhNGdhN1NveG1YdGdreHFXOUk3?= =?utf-8?B?K0M4a0FLaUxPK1BFbnJBYTVGUTNpRDRwQWNDWUtkM3MrU2hnRFc0ODI3Mndq?= =?utf-8?B?dmxCVmhlUGEzcFgvZlV1anhXMThoZExIdXFIaHZEanRsSkljb01nWHJTME5r?= =?utf-8?B?MlAreE1BWlVBeCtkSjJsL0RESkVpSGt2aTZUQStkT20yeDhISVJKY1huR3Rj?= =?utf-8?B?Tk80ZzNJenBPbEJxa3NSamNCNyt0ejhoeXFPQWt2WVBhblB1NEZBbEFaS0k4?= =?utf-8?B?ZFkvaHFsRWJ3SU9xanJNNTNZSU9vOHBBaWNxbFZITVpwaTZxcXhDdm8xM291?= =?utf-8?Q?37FX3r+wS/yBqfqFvMjA+s8Jh?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: dea507ef-8667-40b9-ddaf-08da7f0b39bc X-MS-Exchange-CrossTenant-AuthSource: BY5PR12MB4130.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Aug 2022 22:12:21.8423 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: QCvRClMINjg+cLuaIzEBseX+6WWkOJZti7gqbbY1GM2F9n2q1Rq9xedO/nyjI8oamL2h5/SpUovV/jNwW1fu7w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5946 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/15/22 07:41, Mel Gorman wrote: > For the rest, I didn't see obvious recovery paths that would allow the > system to run predictably. Any of them firing will have unpredictable > consequences (e.g. move_queued_task firing would be fun if it was a per-cpu > kthread). Depending on which warning triggers, the remaining life of the > system may be very short but maybe long enough to be logged even if system > locks up shortly afterwards. Hi Mel, Are you basically saying, "WARN_ON*() seems acceptable in mm/, because we can at least get the problem logged before it locks up, probably"? Or are you implying that we should instead introduce and use some new PANIC_ON() or VM_PANIC_ON() set of macros that would allow proper "log then reboot" behavior? thanks, -- John Hubbard NVIDIA