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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E7D1CA0EE0 for ; Fri, 15 Aug 2025 05:23:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 860CC8E01D2; Fri, 15 Aug 2025 01:23:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 837768E0002; Fri, 15 Aug 2025 01:23:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6D86F8E01D2; Fri, 15 Aug 2025 01:23:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 5B1CD8E0002 for ; Fri, 15 Aug 2025 01:23:48 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B20C3138A5D for ; Fri, 15 Aug 2025 05:23:47 +0000 (UTC) X-FDA: 83777849694.17.BCFD1BD Received: from NAM11-BN8-obe.outbound.protection.outlook.com (mail-bn8nam11on2079.outbound.protection.outlook.com [40.107.236.79]) by imf17.hostedemail.com (Postfix) with ESMTP id F331240006 for ; Fri, 15 Aug 2025 05:23:44 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=fail ("body hash did not verify") header.d=Nvidia.com header.s=selector2 header.b=gXn7m9DU; spf=pass (imf17.hostedemail.com: domain of apopple@nvidia.com designates 40.107.236.79 as permitted sender) smtp.mailfrom=apopple@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755235425; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=PvYha/sZ+yX7IibyWsB4tyaF6YuUV1QfkLirpmkP+98=; b=LoPfvhzmcdcun92FzFUFvNOj7q3BRICCi9IVMIjb2fM2z39eAltNEyOyOKcIwjrasK5LW9 1L3sCfiCaRsB3PU6Ba2A04j3l/ZNxIPxok5ALg28wFcfuWMCg5CO5HTAgBAtj6DK6pl+Mc 8xnFoNE8vf41fjiCjUvw17NLJ88xBaM= ARC-Authentication-Results: i=2; imf17.hostedemail.com; dkim=fail ("body hash did not verify") header.d=Nvidia.com header.s=selector2 header.b=gXn7m9DU; spf=pass (imf17.hostedemail.com: domain of apopple@nvidia.com designates 40.107.236.79 as permitted sender) smtp.mailfrom=apopple@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1755235425; a=rsa-sha256; cv=fail; b=gIUdVc/92zR6X6541Klr7TpMVUH4uH5J8ZFcgMCWhuRxQCHxCZKdBoaDjAZOg+3fIQSL1k vAzlkFtg44tRGJYIac9m3Sh8Fvz+iFebVl+x8wuZpfu0/MjFK7ltPy/wNeBaokeZHH6cO6 Jn7BqmB52SCvoTjUbOfkeRGsk6zAYPY= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=wDLhm+ilpTRcp244+bAKEc+rqIhPV74XxY/ZDSOSGowt+Y7BGG4yZK9jYJUYb0uQqv8ZpWQ+uUCbAiCzCwIeT12+RkUB65t6izxgeOprI9n6IFmkuqa0V6E57a8zelZUDdRII4Wb7wqy8NXlvEvfy0ZdiZgw1/VQoIjdnrCpfKjdz7VPWyeCM97KdQqkrX8ubZIVPxyFmoc2FhdPXKNU9IA7RnQJvv15B3LSH2v70pcnBvMqGH25xansEeMvPY8+3ECp+2845Ttk0jMWpGL0xzYXoUJUd2z+M0Q5xnCXVBWnqPpFZlIE5O7ylSJRCfoYFaoOLiogvoUUGOisOz1lhg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=P2wsOVgLFUFFYMg79wl57kKK5Pp+T93Vp1LeZZs5UWk=; b=wsW9Q6130HYxoCp+ig/LublMdrOtiMM9txNKtA8qbDWQPdxq+PAiBXSbztfhV+OeCBqHcFH1txrKsl+e+LPEq3y9GqinI5QKAJlGg9ECY/puv9I7+n55YXktV5gSggIULjQaeigPYvNwezt+x74qPbt3nLzYbI7wSJFJBrMPqZxJewUiqAAPE5K30dVIdLGqp7sUotL/8d453kZOUHkRJmFnNrntlzradicZ707q3StmlvwTB608KRCe/FWSl7/SbyZiD+llOIfytlXEpIlUohCBEm/MHWAinnPVKIz0LpPp/xsEymui0nV5M85ofDKzQJyS2aSDH7M7Fc0lfyqalA== 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=P2wsOVgLFUFFYMg79wl57kKK5Pp+T93Vp1LeZZs5UWk=; b=gXn7m9DUyIYgz7OgK42rOUvY8QcaIVUrlBhnPbmLW89dyLitQ5lXAdzlxLzjuuxjBzeohFwqlSF9N0WfHDusCmfGB1Zo8DFzdHM+5GHuzEfz7oXtWUZydVVM5xT02acNKNWxgMiTdPKLsqN7WR/VNj5zL+j7RCw3w0EMLb0fssFDd7Y/XkdLXADjqZgPjfCfMUzmFhzctt+5/Kflqw7W8HW3YpdmSrABndZ0It+2jkQCsRcHUmD6rXRVQZG3PM6rP4JVZbnHYf8nYK5Fz6W4Kf647+0nZmrTFhQCF6+VTuxVo1yAWv+1dkeoKdywrht1mqbGluaCuWq9uv/pvO399w== Received: from CY8PR12MB7705.namprd12.prod.outlook.com (2603:10b6:930:84::9) by LV2PR12MB5871.namprd12.prod.outlook.com (2603:10b6:408:174::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9031.15; Fri, 15 Aug 2025 05:23:41 +0000 Received: from CY8PR12MB7705.namprd12.prod.outlook.com ([fe80::4b06:5351:3db4:95f6]) by CY8PR12MB7705.namprd12.prod.outlook.com ([fe80::4b06:5351:3db4:95f6%7]) with mapi id 15.20.9009.017; Fri, 15 Aug 2025 05:23:41 +0000 Date: Fri, 15 Aug 2025 15:23:35 +1000 From: Alistair Popple To: Mika =?utf-8?B?UGVudHRpbMOk?= Cc: Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Leon Romanovsky , Balbir Singh Subject: Re: [RFC PATCH 1/4] mm: use current as mmu notifier's owner Message-ID: References: <20250814072045.3637192-1-mpenttil@redhat.com> <20250814072045.3637192-3-mpenttil@redhat.com> <20250814124041.GD699432@nvidia.com> <2da9464b-3b3d-46bd-a68f-bfef1226bbf6@redhat.com> <20250814130403.GF699432@nvidia.com> <67b6e041-4bea-485d-a881-cc674d719685@redhat.com> <20250814141136.GG802098@nvidia.com> <20250814172018.GJ802098@nvidia.com> <2982b6f1-7c14-46ef-afb0-7951f7cdc2aa@redhat.com> Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2982b6f1-7c14-46ef-afb0-7951f7cdc2aa@redhat.com> X-ClientProxiedBy: MEWPR01CA0147.ausprd01.prod.outlook.com (2603:10c6:220:1d2::10) To CY8PR12MB7705.namprd12.prod.outlook.com (2603:10b6:930:84::9) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY8PR12MB7705:EE_|LV2PR12MB5871:EE_ X-MS-Office365-Filtering-Correlation-Id: 77db1422-78b5-4acd-2a11-08dddbbbe590 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014; X-Microsoft-Antispam-Message-Info: =?iso-8859-1?Q?170wRzoKiV59Ya/2F05ciaiYs66O3Zp3DNURSldI//TsEGMeF+IKTnPkAp?= =?iso-8859-1?Q?yGhd9tr+tnDlDHYtT768P4tALuMI3btiVqUnhODx5elgAHrnGWa7e8XqM4?= =?iso-8859-1?Q?j1Hpk2eUEukvM2UPob1kDSIrKlpLyNmdDRxqmpTJgBxfDU3gnf6kGL7o5s?= =?iso-8859-1?Q?BZ//swZf0uX0WHRt9eJymnZLZDUQEkRf1Vt2NakyNOqd48X3mmgcLAAqJC?= =?iso-8859-1?Q?jeGqkpLTbcPGy/j6gPShii8Z7Cg/raJr+XyI0Lesd/E1eGfhcR9R8AmCLi?= =?iso-8859-1?Q?WVH7sq7gDy5RMO/IRLr3w9uorjnstMrDcTNL1yS93Ap+cgqQrRt8mZTQwJ?= =?iso-8859-1?Q?nOPlgvn4W1BFblL+u2z7mqPwl18/4nMrIkx7VHdVUrnX1zWjMYwjTqiD4w?= =?iso-8859-1?Q?eWRbd/YtocQsVciKZhRIh9vA5bFzKtYsCO1Cv1X2aOuio0G0dJWRjzKntO?= =?iso-8859-1?Q?suKTDxH+ycFE+4EbjrVwcE3iQY0JKU/yY39VNW/fc6t953J3APqvqDJIeg?= =?iso-8859-1?Q?yguNfTYoL1IYEAEgZIYh3kiy/v8LFr8xobbUuiScRAAhsAhkr0kpEi6QJv?= =?iso-8859-1?Q?kM6zJLm1QzRAGPLSAJNiQhL4RPYZlxUpFkzRT5Ht456b+TEUDZ1yXgqyon?= =?iso-8859-1?Q?3SYpTpKP4JgrImSkIIlFRgt+v0uYuk6fK7/j8ciygWZMEx/pjr4ocPc0wN?= =?iso-8859-1?Q?O+Et4as19IrUJOR/Xc3dgcoZMcGnPjhWb9sZGLZUjguIzAldnIxj2xsY1f?= =?iso-8859-1?Q?OMc9LJO0jD3/92nwyrBZustbOUuUVEQ7jo7+a48Eoad5vTtd35EKzzBjwk?= =?iso-8859-1?Q?icgg5MDSYFpZ+4Zib8XnHzAL6bua3ivH6j/yCsoyKo3ZM5NjMnBP6njPVD?= =?iso-8859-1?Q?mexzwgjMWQNa0ABZpE9LnxFXr2NmpiUdBqybGJQL73BZt95BO6iJxqFmqF?= =?iso-8859-1?Q?g0gV6s4COaSR/p/PgXLRcER6oWsjn73tvi7Y8tLWfdt/s0PJvsJK0NuWl6?= =?iso-8859-1?Q?Q8AQSev/gFA7Inx2kVEK0gRmAhQmyMzosQbwSSgW2V4Lfqu6xuBae8PWwO?= =?iso-8859-1?Q?WUhnbb1UU9X1ik0SydC/eIPMwTySyNbeONfG05AO315ouBkFxvysgfGpNr?= =?iso-8859-1?Q?KT05wkFmmSFVUNf2q+168cy11IDFjL/HYExrBTc6pP52Ip9O/u6Q89+d6Z?= =?iso-8859-1?Q?qsQ+Uk5LviPoSj5y1HnEeABz4yCzIe30EsHo2w8UcT7xqg7eeHyRA3Fe7U?= =?iso-8859-1?Q?obYRixAlQIBnpZn5X9VxnO6qhH7NOODPAq2qsb+dAp0kbnrjBfXWZO7a6K?= =?iso-8859-1?Q?C5C3fPJnEmkOfH/3mvxWGnhENerTr53gG7znL/mHHMJLJGMNWwi1tDC4wN?= =?iso-8859-1?Q?ibvYZxEkCA53vVh5AdTYbvNhAJMon6s9ce6a5TWTVXOto+jVRGs3x0JIFB?= =?iso-8859-1?Q?ty/v6N5+UidtNzLviOmwwdXBgrvlae8pO9OD0DbeP83eK3veSgfkpLk0kM?= =?iso-8859-1?Q?Y=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CY8PR12MB7705.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?IBi2EXgOF++/cny81vtlrgh5xEiyVXi0mrkMUvUkwTQf9hd4SXy9PXKB9a?= =?iso-8859-1?Q?Mxcc1N64xzPVSdT6XVHXKhvuqJqKV7bvraj3282VkC/1Ldepf5V+TiRhef?= =?iso-8859-1?Q?KLMnW9Rf0pQTBGoh/0Hic84NSdYXJBL3sHIPZdmyoAohCbygqI65cJnxzx?= =?iso-8859-1?Q?azIz7flINLDhErJ4i1n85+1avJ8HCSms9wrhGygYOP2PKhYmAbin3X6J8x?= =?iso-8859-1?Q?Stb5ix88OaQV1SjxRpxhnYlBJ0aRn6xyauwmo+NHBH6rCz62B6QDuWO0A8?= =?iso-8859-1?Q?7bWW/OOe0mtdZzeuoMdimiKjSciEVsUtC4yuH4QU/KDLqSRrunoJXowmp3?= =?iso-8859-1?Q?Tj/92r8JNmKr1iJW2NvfTnxhfYjffdC4YnDRhYeF2Aavsk7AZfnZO0USbS?= =?iso-8859-1?Q?21WpgW1npIwUbIh33GDrhGBT6x9E2p0SyyutkDBhscE9nX5HWWVjwjUihA?= =?iso-8859-1?Q?hMWm1n3QaVbQ2WSp9EZ2TPZ7iHFN7jEf/W0sBNVPMM5EET9IAxacjHSxqe?= =?iso-8859-1?Q?Q3bbc+IEvvsCHVgQVuVMfCVzSc4fWbxNPrp/e0WbwXeBgq0g5UyqprFsbl?= =?iso-8859-1?Q?bs6uLghVWNgRcXhKftd7z3orb44CdvSFCL9dAtyR7pXscaN5gc6rQ5V47z?= =?iso-8859-1?Q?2Tc6kw1zZeLRjC56FqjecLOPcE9GhaN+f3P9zcMmebBOOQK4Mza6xyGSIN?= =?iso-8859-1?Q?GXxTygilGZ85phQEfvB5h2LEL6FRMyhnUg9Np6EhqzyBjVc+S9PMaqiCDe?= =?iso-8859-1?Q?+QTNLm3k/ci4Y4FS+h5Sg3+tlrCRlJnUMj+H0FaNT6x5fqorIpnTbr7J6/?= =?iso-8859-1?Q?WFe2nLbTqBbg22jQRG3QbgraX4n+5SCDYJxXze3lJf3m45Gbc7mKyCO0J+?= =?iso-8859-1?Q?LnPnJt4cheVUVEuY0sXTy1ZrO3em/KMkstd5QDeIOvOKIqX9CevVrkNrD+?= =?iso-8859-1?Q?qFcifZlCYQBoDNFeXsTL1Xn/mvvAaT0KM1wRJiFwi8Sj8xyV0qsrlWK8c+?= =?iso-8859-1?Q?xL2LWqbOTXAkNN8SYlXffoDC21FHoOVoz+DwJ9IxXA+ZVq5KJQKirvM98F?= =?iso-8859-1?Q?8VDcBdYNXx+OjaNlbRk75Fi/N3R6Q/Q+C8gmi7ipO3q88/IwCEWsL4vbUc?= =?iso-8859-1?Q?SoYUxZwXSaqsYpW0UJFuNaI/Pm/C2wBHj/Onf4OjD9R4tgMqOp/zqKr2fv?= =?iso-8859-1?Q?sdBlLmKIF9MrMvX0LnzRt+rNZuBM5qn7NAYCnPuFXVhU0alx/EbSoCFOGd?= =?iso-8859-1?Q?4GOovXF09aW32BAOrILRIsAYBQMwR7WZDucsKhtyjr48NTzGa9kbXAcozD?= =?iso-8859-1?Q?3WVQmL+IJLkrWynpTKG1p8bBhHUFmbATTKp8eUIkyulmJJ5nMrS3s0L9Md?= =?iso-8859-1?Q?dlu5Jqj7YDGqn8p6EK5+9eOJgbcl/8/D4sQRDX4RDp5O0Uz+ieSxWWJ1ss?= =?iso-8859-1?Q?CDqZY1n+o0vc1P0bTcWRBXGttP3Kc3UVTNSV6+dmdJuOooUBWsbLrXYPam?= =?iso-8859-1?Q?XpCkALRGCsUBpqh5D+RSSFcr6p72SKYzKTwP1dHd6ueuKGnEpA2UlPbOAE?= =?iso-8859-1?Q?UQXsyyS9kXoza/HjTnFfjZyA45j2bH/W327D1KHFQNplbjx5LDYs5tx+t6?= =?iso-8859-1?Q?Yh1C+3hxha47iihBhrgmQO9BSP89hTt0Bf?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 77db1422-78b5-4acd-2a11-08dddbbbe590 X-MS-Exchange-CrossTenant-AuthSource: CY8PR12MB7705.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Aug 2025 05:23:41.6499 (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: qQ+Fj4q1EefSUNKZtFV3TPcxwqwQt2cq+FvPFvCjsdDXfU9B0TylCUWXgBGGtKy7MtPPmWV9dgbNgD7fPzwkyA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV2PR12MB5871 X-Rspamd-Queue-Id: F331240006 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: agf1mx51w4rxkgngg1zq8un76hdom6ww X-HE-Tag: 1755235424-231968 X-HE-Meta: U2FsdGVkX1/MU4z/8Pc3CKMZ2G1IXvzma09Bh3ZzzqDxZ4wuLOpcHPmP+Ix/5e1GsNe8zIaWL9kiy4GcHqmfaCh+FMIZQFyinMm2MA47nnQyj3lDQaqdI/JI4K600E2V6DutZVFGTqVQk9CEPRxblXHSggFAaZxElZWme2btR+zNDkMBkuV4jmMRCDcZfGCHNL+VZqQF/hJRrrygyf1wtRx7qqAT0KWtHP1491Rdj4yDxUgi8ROCCJFcQF4KHFcD6cl0SpMVJCA306UbwZSpOtaJqg6iWx4SgbyBF0hOH/B0rr8ehgbBjakyGO3M8xjXtCg7biXwEWYCzvZf1ItHM+q5LnNOQcsyBJ4XxkyEVyXfu7XVzQeppsa0mYQdpqCfM6EkzxX+NGHWaG0lDG3bGkcu4MByCqRmkPf5EnP87dBktgaOJzDDVoZfZ1khsIALoeGNX/0Yaeer3Pv0qlFrprK4m90969RRRGm1bS/r1S5EHHNKmTXSNIBdZ/cFpR4qPTESEPRcjKjsz1dP2YiPcA2pG8cBpRvd2cUxjUOWcNmwHMeBJwaODDmxOkkzsYxYO0f6+y/gukcZDnZeZQcDCxCcC8AdZElyBFxmtep4b/J2bCXF+ZQ6IVjno3W1lclhKO0Jak7IRz64/LyI3H3tAkET582t/F/RFHal+xsrBngCdlIFUjxzHXcby1EU5iamug4kBOGBRyRX05v8LRf2ijYiG6UnzXrET+RkJa3eWExdfE7XM8LYweWoNcUcyL8Pb3XrGWBFS9mgAc7VpE/CTiZ+Iyd0/tftJ6H/j1A/ZCfsXqJDLsLS8UoVtkzLshBSAhUtfgFQt4rA76q+v9Ogv6KavThNRK7Sv2TL7NVTNBtirpsSFm3KD12Sho/zhc5Tq2OxdlqfrSzbicWW9vY63I1M8H8W+3H9J4wYROTApElKRpQyKfB2hkcukstRJrEVSph9qHM8yTwM7LasK5d hBoZzsO/ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 14, 2025 at 08:45:43PM +0300, Mika Penttilä wrote: > > On 8/14/25 20:20, Jason Gunthorpe wrote: > > > On Thu, Aug 14, 2025 at 08:00:01PM +0300, Mika Penttilä wrote: > >> as well as hmm test module with : > >> > >> * Ignore invalidation callbacks for device private pages since > >> * the invalidation is handled as part of the migration process. > >> */ > >> if (range->event == MMU_NOTIFY_MIGRATE && > >> range->owner == dmirror->mdevice) > >> return true; > > If I recall this was about a very specific case where migration does a > > number of invalidations and some of the earlier ones are known to be > > redundant in this specific case. Redundant means it can be ignored > > without causing an inconsistency. > > > > Alistair would know, but I assumed this works OK because the above > > invalidation doesn't actually go on to free any pages but keeps them > > around until a later invalidation? Right, the pages don't actually get freed because a reference is taken on them during migrate_vma_setup(). However other device MMU's still need invalidating because the driver will go on to copy the page after this step. It's just assumed that the driver is able to be consistent with itself (ie. it will unmap/ invalidate it's own MMU prior to initiating the copy). In practice I suspect what Mika is running into is that the page table synchronisation for migration works slightly differently for migrate_vma_*(). Instead of using mmu_interval_notifier's which have a sequence number drivers typically use normal mmu_notifier's and take a device specific lock to block page table downgrades (eg. RW -> RO). This ensures it's safe to update the device page tables with the PFNs/permissions collected in migrate_vma_setup() (or the new PFN) by blocking other threads from updating the page table. The ususal problem with this approach is that when migrate_vma_setup() calls the mmu_notifier it deadlocks on the device specific lock in the notifier callback because it already holds the lock, which it can't drop before calling migrate_vma_setup(). I think one of the main benefits of a series which consolidates these two page-table mirroring techniques into common code would also be to make the mirroring/invalidation logic the same for migration as hmm_range_fault(). Ie. to move to mmu_interval notifers with sequence numbers for migration, perhaps with filtering if required/safe and retries. - Alistair > > This is nothing like what your case is talking about. > > This one is actually pretty similar, MMU_NOTIFY_CLEAR is also fired in migration process > (split case) and invalidation handled part of the migration process. > > But I have already a working version without any of that. > > > > > Jason > > > --Mika > >