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 F0B93C43334 for ; Mon, 25 Jul 2022 17:56:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229806AbiGYR41 (ORCPT ); Mon, 25 Jul 2022 13:56:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229805AbiGYR4Z (ORCPT ); Mon, 25 Jul 2022 13:56:25 -0400 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2077.outbound.protection.outlook.com [40.107.243.77]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B4D6BCBB for ; Mon, 25 Jul 2022 10:56:23 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=gzbnnmfImif5eJCvC7Y0DYdJNYKt03XIbYReDmC9FikHMqdpZ6YlIZM0un8aDQvalnTPHT8LkuQR8g3YV7zuyB71Ma6vtmIrjRGS9Khp2NAe/zdJYvXi7rN9XEraa1bWzDKNTCkUohmMgJW53k9j+x7FejlcvVVp+Ainvv3cOEgCd5+E0Z1Mk2yyuReapl8iGJ3ExYlQfCET7IJAxI5EAygzi0aBDF7lP7GR+e+uLkAGA5X5UjukdKlE4W00JRQYE3o4xHbHi7hdWIdBjIABqPfTzJHLfB91C8hoZMk3T52eZDi5d1hIkEbLYXGfIuA3XMlh99UyJQDKGOjUatHoig== 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=7+US225JqQmvhx4x5VO1ypLXrZVd27/VTbjJ8yU+xO8=; b=ZJ/mF+hoj7lHcGvSW9+X07zNKPCXFK5bc7GoNmXaZPPa0XaCy4P6NSDp6wICx9I5zL4EttR8ZWffUi2ETC9iF/60u22cWoA6yypNd/97tPKFSje0oK1+XnHSET+KZ93f3mvBowsVU2LqIphsV/ELDBKCdEoGHXWK57vjehx7XRrPvYVsLZuTZnbTcgNuJsvgeSETTHQbP9mtwbAXAtzA9/pJpSmE/HZlQZ1xkCaO/ezfCBXf3cNTVqf/o+20psEM6GlkQKd9sQQMkEUacs5E8K2a/RQwh6tcSW6C4wJ8QXIHNrdxUD4CIFQsmQCXN3RCgHLwY9j4I+vF6Tq2W06cPA== 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=7+US225JqQmvhx4x5VO1ypLXrZVd27/VTbjJ8yU+xO8=; b=mJ8NYbE+b5iFOnEXmEsn840/9EauIs+EqcBlcIWPXZTh8WGrITkgkqQPPf4iOzKHYxFNIFQTQ05Qw9hR2qs6Jz6Yi+t2/dfmKqTgVsCT9CfGY9p/2lkn7q6XbMhI1iVUIOL4uEsHUB/VTSONMtHG1muvRiSMYqMUmEvvBFES+zxQjard9wewRPdxaO1r1K8Y5lp1X1MwIsFHnGFIDXqMxpz9qgoVUF0NYLtWcumUmxcf9U2cQ2KK2SHkwvOXxUWAxNdwq8x/23vb/ofDYrrTKF64BKUAWGdF+SimDc+yQNubXa7oUJ7ivxPIOI89GkeZXG8bMjcHWW+YJgw4BXPqZA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from MN0PR12MB6150.namprd12.prod.outlook.com (2603:10b6:208:3c6::11) by MWHPR1201MB0207.namprd12.prod.outlook.com (2603:10b6:301:4d::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5458.19; Mon, 25 Jul 2022 17:56:21 +0000 Received: from MN0PR12MB6150.namprd12.prod.outlook.com ([fe80::30b4:54b4:c046:2e14]) by MN0PR12MB6150.namprd12.prod.outlook.com ([fe80::30b4:54b4:c046:2e14%3]) with mapi id 15.20.5458.024; Mon, 25 Jul 2022 17:56:21 +0000 Message-ID: Date: Mon, 25 Jul 2022 10:56:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] mm/hmm: fault non-owner device private entries Content-Language: en-US To: Alistair Popple Cc: linux-mm@kvack.org, Felix Kuehling , Philip Yang , Jason Gunthorpe , Andrew Morton , stable@vger.kernel.org References: <20220722225632.4101276-1-rcampbell@nvidia.com> <878rohbkeg.fsf@nvdebian.thelocal> From: Ralph Campbell In-Reply-To: <878rohbkeg.fsf@nvdebian.thelocal> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY3PR03CA0001.namprd03.prod.outlook.com (2603:10b6:a03:39a::6) To MN0PR12MB6150.namprd12.prod.outlook.com (2603:10b6:208:3c6::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: e078f347-e2cd-4444-070b-08da6e66fb65 X-MS-TrafficTypeDiagnostic: MWHPR1201MB0207: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:MN0PR12MB6150.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(366004)(39860400002)(136003)(376002)(396003)(346002)(38100700002)(86362001)(8936002)(186003)(6862004)(4744005)(5660300002)(31696002)(66556008)(66476007)(2616005)(478600001)(41300700001)(66946007)(6512007)(6486002)(2906002)(8676002)(4326008)(54906003)(37006003)(316002)(6506007)(6666004)(53546011)(36756003)(31686004)(6636002)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?YTFTYUdWVitIRE1Bb2NSU3ZiVnd0S1NVOTFaNXJ6NFErSXZTdS9Wa3hicEE2?= =?utf-8?B?QjBiZUFsRVN5aENBcjNGVTMrVG9zNllIQ0w5Z2lDcmRscHlvY3V0SU5RK2J6?= =?utf-8?B?eXEyUC9Jbkc2UHcvMHZmaUIvSThwU1JwaFlxK0x3STYrSXlRVVpCa0NReU9N?= =?utf-8?B?OXpqVnVDclNpalArR3FkY29RWTM2KzlWR3J0bzdlZXRKbEZ6SXJFcGI2YURM?= =?utf-8?B?a0k0Y1AyQkZPUjB3Q1BhVHdFZzRnTnRIWG9LejYvcjBxQnc5aTJxdUZ6QnBN?= =?utf-8?B?dFY1L1crUHNadlJTYXBwVGNjY08xWHJtVkZINU52Zm1xVFFKbW1nRGpSQ2R0?= =?utf-8?B?TmF0ZTk1dVNtNVlOM1pKZlZkZjZVVUlkdk53QUtLelBZWDZXdVBHZU9YYk5i?= =?utf-8?B?MCt4VEltQnFYSWRub3h6VVJVeGMrUGNOL1VCK0pUQzlGanJscEFRWlJmb1ph?= =?utf-8?B?YXg5V2dMUE5KRlNUZmsrSERrVS93VDAwamZEU0tKZmpmcXBZRGczNTFETUtE?= =?utf-8?B?U2Y1YWcxemNvOWZWa1l0VFFKUjdrSVJTNGhDVllnS01rV0tOUGliYWRMZUhW?= =?utf-8?B?eEcxMUxKSXhrRzg5MmQwRnR4VXZ1eldlUjErdmNTcEpwK0NBY1dQNlMvZDQx?= =?utf-8?B?L0hFNHU4M3ppRytGSUNkOWJsY1QrNkZxbUh3cWN4NUQrRGFzT0N2Q1g3ZEti?= =?utf-8?B?MWtXWjZpZFRrYm5FdURJeW5NWngvbC92OFhYMFFwT0xiNzhXWTFsSUhBZm5w?= =?utf-8?B?UlhqTjMvQnRoM0pwVy96Z3BabWFMbWpSTjFjR0VkME81QUhtaGpYaXFlVy82?= =?utf-8?B?bDhmVkY5ODluQldZQVN2YVkvc1RzZkZCYnV6VUVnK1Y3emkrMkwyaFBHUDRx?= =?utf-8?B?ZHhZQW44bmlQZStxRlNId21HNjdxbjZGWVdKSkEwbUM2QmUyK2toeEgzMytF?= =?utf-8?B?dERmQ0dLYzQ5a2FnWTRmZC9RL1JqRVUwWU9yNTVkZmRqUi9ocDIwVlRML3BL?= =?utf-8?B?b0JnNUJ0bHVyc3NoVTJ5c09JQzhtdHhzYjI0WURtclVUcVhMb256emhEUXRn?= =?utf-8?B?bFgyZ0tLUmw0MmZROTltSnQ2dUJEZVcxc2EzNVNWeXJGVHdVSk1TR05YRDYz?= =?utf-8?B?b3ZidjlQNFJYQ1MxRU52bnc0OUxkK1JiTG5QQUErbTA0VGdBVW50aTZXdmZS?= =?utf-8?B?STR4a0svbE9NR04rUmkyN1JWMCtqdURxZEJQV0dRZEl0dGw1aUlJMTVIdjNw?= =?utf-8?B?VWtRQVY2bGdZMkhUTUMrNzAzeVVrTnRBZlh4aSt2bWVMV055c2ZkS2FzcnMv?= =?utf-8?B?MFdWR2E0Y1liZnF5KzNnRDVlUzlhaVFsc3N1aHdnY2d6ZmhYeDk4UUZoNGRv?= =?utf-8?B?a0RyeG5CRkE3b0lBd1p4cUVsNHJmYllIMkt4QWNTVDhqcXByOTZHTmNQTjVi?= =?utf-8?B?b3E4dGRrWVRJUmM0Zlg2NDVVU3VDcmh1SGIzb0NYSkZzVWtrdjdGUXkyc08z?= =?utf-8?B?UnJ4ZmpzWkdpellWdFR3TWU1VEZ0U2JNa0llQzUwaFVhQlFNbmRMd0FIQ015?= =?utf-8?B?cXZkYWNuREVQRXQ0YWFlN0h6elQwN1BRZHZGSXlSYVU3cjE1UkxHTEE0d0FD?= =?utf-8?B?cmp2c3BWTk1lU2JNTHlZUWdiSjZGZDdvYWM4cEJsM3J5dWJFcUZ4OUh1ZzVP?= =?utf-8?B?RkZ2b29aQm5CT2pnVjROVGYzR055Nk95VXMyL2RCWkdKczg2TURiUW9qZjdL?= =?utf-8?B?ek1YSERyQzVZVG1zT3d3WHdCRkFPMm52NGpXajFUS3hmTDM2dFJ2TFZmTGUz?= =?utf-8?B?ZUtwVEhMTnd2WG9ibGI2emZXSXZ1S2ROcW5vWGFNU0JCcmlSTWFyVUNPbkJ3?= =?utf-8?B?dFFHVWdKTG5BNzhuUU1tYjVONDBwTEJzanFCQ05nTzVzaTA3NDhhN0thNFJH?= =?utf-8?B?QkdUV3VPUS9ZdTBpMUxTYjd1ZlFaRGllSWtPK2N4RndkZTgzUFNPcmUrcDd4?= =?utf-8?B?eHBYTnRmRjJadnF3RzV1b0dyOHFoWDIydk9DUmFub3MxTmU0bFFiWXdJelNv?= =?utf-8?B?dThlS0Z6bE1DTjhta0NLVXdvdGxsZjVBV0x5NWxDb09lbm83SjVYRlRSN3po?= =?utf-8?B?U1pyZjF2MjJERjArYVBoeEdyTW5wYmFGMmladGZMdUpXUUIyUmZXc3dTQWF1?= =?utf-8?Q?rV9K51Jf9zPGVgOO1KHe9gs=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: e078f347-e2cd-4444-070b-08da6e66fb65 X-MS-Exchange-CrossTenant-AuthSource: MN0PR12MB6150.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2022 17:56:21.1955 (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: jXiV9+S2cJIDTrnzaEbOGMmmyUca2+tdDKio7hbj0DEbckSPI/KOC5T0/FIfRKvg8ATwKW5jMdO5h9D4V3bmMA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1201MB0207 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 7/25/22 02:32, Alistair Popple wrote: > Ralph Campbell writes: > >> If hmm_range_fault() is called with the HMM_PFN_REQ_FAULT flag and a >> device private PTE is found, the hmm_range::dev_private_owner page is >> used to determine if the device private page should not be faulted in. >> However, if the device private page is not owned by the caller, >> hmm_range_fault() returns an error instead of calling migrate_to_ram() >> to fault in the page. > /* > * Never fault in device private pages, but just report > * the PFN even if not present. > */ > > This comment needs updating because it will be possible to fault in > device private pages now. > > It also looks a bit strange to be checking for device private entries > twice - I think it would be clearer if hmm_is_device_private_entry() is > removed and the ownership check done directly in hmm_vma_handle_pte(). > > - Alistair I'll fix this in v2. Thanks for the review.