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 D078FC43334 for ; Fri, 22 Jul 2022 14:47:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235213AbiGVOrg (ORCPT ); Fri, 22 Jul 2022 10:47:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbiGVOre (ORCPT ); Fri, 22 Jul 2022 10:47:34 -0400 Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2080.outbound.protection.outlook.com [40.107.94.80]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A26F43CBE7 for ; Fri, 22 Jul 2022 07:47:33 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=J8P8CqukQS+Fo/V0P8epMFOieT9AKtvzwVfhuyaTnvCZoQ/nwdHPvUJWQL6oB6depBe/7Yc+lT0tbXBe4OdXmUM+xPm6x7UCtuzMEhgZsch1E5hWByKtoMvRLsycr2LsFyA913Djsp3yXwWLqFsx/LAEA8V25brbqnkAkc1mklH1i0CKS7CKQD3a02z7mePDgMD7XooHLZmZ6twe8kQhQvWRUvZGdCl7oF1Lk0BbepY6UabiOYGgu9B95xnWTfWlqupmPGO2C6WpfU+Oq7Tqv+V0Zb7zXLvogRFN1aicRhZOzq8WLxHEwDq24blsWu1ZylT7E9e8XvpzeHZLuc53Rw== 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=d+K29ARDCfRWJTeRnA7afImG5Cb4K3f85c6//5ZPgsk=; b=NNzo37OP2fASq56k/d+SZwW04wFVD0LkPJ7rPeshcJV6Fdw1oSJNYepFBfP4yMMjbyTW0Eu3MGC0h2djAyWM5MAoro8ilKY5Dtn0Vz4mp8qXD+NMcua8l6MnaOujJ/vEuGrZ+Qh4w5iHX7J5a7HGfPa0Lr+2Q61hxmz+fWLd86i9RcplTJ7kQ/BP0nLkh7+rc/JDYoBhc9QaC5TWVP6MtT/ZS/AwRuSa/ROTz3z4c014TqNz0ZatWjAn1Z0LGVx+f/5rCxB3h9QklhThxA9IUDxq/AIkLU1KDFHPa3o6loyyIegK9PekWaOHJnBR/muhT8UBVWU1Lu41neNunqD01w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=d+K29ARDCfRWJTeRnA7afImG5Cb4K3f85c6//5ZPgsk=; b=k0ezUcr4WsRuppXfzH286iyshTYHV3CgcgFVYW9SGjISPpnbOEw4gRADECswBslNgHXGc3FtLzza4c8A+Bl6sl0fjZ9GFefKXwu0KPtV2HLh32eKzmbsLgabWL7lDJaq1T0urEmt5pBnsRi0uii7YoGn49MXEaFC27yv/jSuzCA= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from PH7PR12MB6588.namprd12.prod.outlook.com (2603:10b6:510:210::10) by MN2PR12MB3856.namprd12.prod.outlook.com (2603:10b6:208:168::29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5458.18; Fri, 22 Jul 2022 14:47:31 +0000 Received: from PH7PR12MB6588.namprd12.prod.outlook.com ([fe80::1c48:55fc:da99:87c9]) by PH7PR12MB6588.namprd12.prod.outlook.com ([fe80::1c48:55fc:da99:87c9%3]) with mapi id 15.20.5458.019; Fri, 22 Jul 2022 14:47:31 +0000 Message-ID: <78aff052-64f1-a044-6ed3-e5f48325476f@amd.com> Date: Fri, 22 Jul 2022 20:17:25 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Content-Language: en-US To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Mark Rutland , Jiri Olsa , Namhyung Kim , Linux Kernel Mailing List From: Ravi Bangoria Subject: Question on perf event context swap at process switch Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BMXP287CA0020.INDP287.PROD.OUTLOOK.COM (2603:1096:b00:2c::28) To PH7PR12MB6588.namprd12.prod.outlook.com (2603:10b6:510:210::10) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: a97c78eb-f665-4889-53cc-08da6bf11ad6 X-MS-TrafficTypeDiagnostic: MN2PR12MB3856: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:PH7PR12MB6588.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(39860400002)(376002)(346002)(136003)(396003)(366004)(8936002)(38100700002)(6506007)(6666004)(6486002)(5660300002)(2616005)(4744005)(41300700001)(478600001)(6512007)(316002)(54906003)(66556008)(4326008)(26005)(8676002)(66946007)(186003)(44832011)(31696002)(66476007)(31686004)(2906002)(86362001)(36756003)(6916009)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?elF0UzB3ZUZhdHFpN1hjSHc2d3pHaG5EN3lZKzVQaWFpUHc2TWM5NEpuSk04?= =?utf-8?B?SU5GTUhtUkVMMzBzZlprZmJybEhHTWhod2VGZGpBaE9OY0phWk1oVmxPbTVO?= =?utf-8?B?UkZPYVRseGhxTks2alhnVndsMCtmVkZ5WmhjSVIyY2JvUFRndFRLV29Qbzg1?= =?utf-8?B?M2RhUDk3ajd3TXVpSFpPODI4SmthMnhQY05HeUFGdjhqUnhzNnV1QjVBVFlZ?= =?utf-8?B?U2RZd3hHTXJOa2hJUEkxVUdEVEdJTWw3dmRIOWYvTVg2VTBNUTJCaTRsYitN?= =?utf-8?B?bS8wUnl2RldsS2p2amNUcjJ1SkpuMEtYcU41U01tT0dvckZTKzIyUlNMRlMv?= =?utf-8?B?WFJSTnpwU3BxWDhva2tnVXdyUDFMTFlnOGJXaXlJc0MwWjhjTDdOWW9qTFhG?= =?utf-8?B?MWFHZmtXaFZMZU1mN0gwRzhCR0NUL3dpVXdFSE95OW5QcTR1ZHFOLzgyU2cx?= =?utf-8?B?TXFGRzdQT1p4V2xkeWJVb01pYjFMbEMvTlc1L2FrRERJRmpsOGc3a1dvOHY5?= =?utf-8?B?aFA4YzR1VE81RVVOOFZISDR2VUtCRjE1Q3VxaEZOaGtqWjRRRm9RemNwUDd4?= =?utf-8?B?VWM0N21Od2VRbkhZNVcrWHd0SmRYdEpKOEFOMDRsUTg0T0VwOVZ1VVlBeWk0?= =?utf-8?B?QlRLdGMwc1lHMHpnTUM1aE5zY2syS0srSWhuUUlDN0E1T2lGWjlTZW9wUG0v?= =?utf-8?B?bGFJRU04M3hPK0syQTQ1WjB5MVRDS3VSdmQxSTRkMTZQK2tnMVZBQUdnMUtP?= =?utf-8?B?RU1nWjZkMFZGcForOWhMYUo0N08zc2VyQ2JJdHlPNTl1Z3I5S0xMWE00akNs?= =?utf-8?B?alRlK2k5b3hVbE9PS1FaaEdPYmUwcFl5OGdTOUtXekJjQ010L3dlTHdzRXdG?= =?utf-8?B?aFVKMmFuMnRDdkU5dTBSd1dMbjBaN1dPTEhqd1NsTTg1V2FzWFVzM0RKNllI?= =?utf-8?B?djBrckgrT3RvbXFpZVEwR1Q5YVhCanJoMzlwdlBJUENid2lqQkNYNUpiMGlz?= =?utf-8?B?UlpQeWdYbDJsdE0zMFhqQmVKS2Y4bmo5YmtSZTI1VVFFVUgyN1p4cW9KUnVj?= =?utf-8?B?UlBlNTMwMmJMM1pzYjY1azMxR1I4c0pySWV1c0NCYi9HS2tsYXJLMnB4RXFw?= =?utf-8?B?TS9rTVE2cGlvNnRocHp3Mlg5UFRvbE5HcXcwK1hGbVdYQVdyQ21zL2owYWdp?= =?utf-8?B?UUtQVytSeTFWd3pjZEhhdTV4VW9aa2NZQ0ZEQWR3aDRBOGx2SDJJOVNhQjFm?= =?utf-8?B?bHVMUUtjcW1SZlk5NEdQZ3dsSDRHMTZUUE1KZlBFcFovRkFJMjRSY3RZVEVt?= =?utf-8?B?YzJpNWs0SUZlQS9ubGhLaHpPdFd3ektjNHJNODZvZXN4Mi80TS9oVTBVbnRp?= =?utf-8?B?NTl0a1dtRFRRWVhjRDlHbEE2aTdEZTFTUUw3YzFCbnBIaHdkZXVCVUYzSzBH?= =?utf-8?B?dVJ2aFhDTHZOYW9MNTNpUjZmaGVXVDYxcEhQV1RzZFJZTjFkR3Vma1Jqd1Nh?= =?utf-8?B?eDBnOVZ3eTh4Z1VvQkxkL3JXSExKZ3ZTZDJEVmVmQXBrQTA0MXY5VzhpYTB4?= =?utf-8?B?UzcxMkRFVTZBdndDT1ZLYzRZWVNYVzBBMGpjVzJoTWR3cGxPMWpxUW1Gc0h3?= =?utf-8?B?enpFWjdFeUw5UjZnaDJaOTNsUENVMVZ1M0NEN2ViZ00zOFpwMTRnZzlJakpm?= =?utf-8?B?clJxcXMxZ29lSFEzUWs2b21XSFNUeHc1QkJrbTJrakdQRTZ6TEZmalhjVkFP?= =?utf-8?B?RXBUNldKYXpFL09aMjdVRnFtbEpmWTl2dGZyVVZjZGZCYURXc1pvcTJ1TWdR?= =?utf-8?B?WlNjcUl6Rnh2WTBhS1RXRlNYUkszOHVkWkltd2dFQkNTZFZBQnJna0x3L3hG?= =?utf-8?B?SVNBelNBT01ndmpXdVkxNjlkdlBEQlUrNm1EY1R0UlZuSFBrdHNQV09jWnBD?= =?utf-8?B?aDFNdGhLbm15V0E3ajFodFhBLzViQ3VTUEExczhvK28yYzhXYzF5TnJMcFIv?= =?utf-8?B?T0Y4T1RTOW5DOElVYzVCK3o5L3BaSnN0dG85MDRuLzJoOGViaElBSGpKQzI0?= =?utf-8?B?YmNRYVY2TTk2NzBwZzlaY2puanRjbWVMVmFzcXdxYmJlR2dsSjZFN0hpYkVw?= =?utf-8?Q?XofVdHGfLjcOA5Ywp+w/Mv+/t?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: a97c78eb-f665-4889-53cc-08da6bf11ad6 X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB6588.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jul 2022 14:47:31.1796 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: D7xzWWFre6TekaaSiyIJvog7jvwSvi2JNS37QjeufG0qIDfD/7pWdqIz2KliTmA+0wjnWIBPL6muCcFWnOvgag== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB3856 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, Consider two processes having clone contexts (for example, two children of the same parent). While process switch between these two, the perf event context would get swapped but event->hw.target will point to other sibling's task_struct. If that process exit just after one context swap, _free_event() will call put_task_context() on sibling process' task_struct. Wouldn't it result into fatal error later? Thanks, Ravi