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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D4A95D637D2 for ; Tue, 16 Dec 2025 21:40:18 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8EBBA10E998; Tue, 16 Dec 2025 21:40:18 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="eRy/MTDD"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) by gabe.freedesktop.org (Postfix) with ESMTPS id 28BBC10E98D; Tue, 16 Dec 2025 21:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1765921217; x=1797457217; h=date:from:to:cc:subject:message-id:references: content-transfer-encoding:in-reply-to:mime-version; bh=kq3wDnUk07Wx3FrPqVZNhqYl8nS0ErGgrhM0zKxSKHw=; b=eRy/MTDDrXCOvFa1lMlQemqN7C4UnNBI7IIit5G/iOqjzeKmp4N7Hm63 oPsxDCBpNUGQOTMIRMzl/Oh0rWFVb9wQ5jrhIacd209xJfNYwZ4ucA9N1 MpJ5AC1sdB59UJlxno3FG2mMJlCbf0YtEwxU8ZQkBMHn7TsEJWNKZ2ow2 vsQ0ZriQEfASRyP33pmjUGcIzR4Fgec62hGxgGGQvNXqQkcih0RI1+CR5 4SnNNZoh6SJpBPXAE6j5SD0ew1XyJJ/b7YhxQx9PeLil6fCFOURlGTYHu GtrffOIiKrTkEf4sCc78p+9zzpLRLFCdtpXIKbZ/MsbsOnBZwe6PRfU51 g==; X-CSE-ConnectionGUID: CzRD8V/jTPCZ+RiWFbwOww== X-CSE-MsgGUID: RzBSDt3HQEKvXsKceflCKQ== X-IronPort-AV: E=McAfee;i="6800,10657,11644"; a="67734639" X-IronPort-AV: E=Sophos;i="6.21,154,1763452800"; d="scan'208";a="67734639" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Dec 2025 13:40:16 -0800 X-CSE-ConnectionGUID: s2G5/pYFS0aiJjLhpBXNVg== X-CSE-MsgGUID: gRMphmTVRP2cmuNTcHkgvQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,154,1763452800"; d="scan'208";a="197419593" Received: from fmsmsx903.amr.corp.intel.com ([10.18.126.92]) by orviesa010.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Dec 2025 13:40:16 -0800 Received: from FMSMSX901.amr.corp.intel.com (10.18.126.90) by fmsmsx903.amr.corp.intel.com (10.18.126.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Tue, 16 Dec 2025 13:40:15 -0800 Received: from fmsedg903.ED.cps.intel.com (10.1.192.145) by FMSMSX901.amr.corp.intel.com (10.18.126.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29 via Frontend Transport; Tue, 16 Dec 2025 13:40:15 -0800 Received: from BL0PR03CU003.outbound.protection.outlook.com (52.101.53.19) by edgegateway.intel.com (192.55.55.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Tue, 16 Dec 2025 13:40:15 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=nB4k0FDE4nyOW9hXOdyH+kIOy9Q8+Bd0pSDOqvSefJRwWciDa9bTapGuV4XIpU2bQSYlDP8A0KB4bFtX323hqga7NA8U7z5zGjYAYJavezm2mRtmLNRsjWdqF5feD3rPDtQv3NNpYCXzrI4ZjqJSbROSaRhnIV2w4+lPdtd8HiZT7mJ3bu/5LGYyi9CKamL6y52a/DiFqtcUvkeTesWxTEmIYG6oUlRzlBmcd/tOemSsVcyjoKaF2drjRRdS35TagnblkYPTvQjtXa+G0sLLkjCcOsNv8a2L1N75uvNG38xC3CW8ao+fTzHdTaOLKI7Bh/10IsIxlem7AGIC9IgUvA== 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=z6MtlBLkYlwQUag/wE2fkthopf7Jkr5F0SSfn2t8YhA=; b=MEa1bADsnULDLutVMfeWd5VVVjiYf3gBsvDcneKurlv2vp33JuOt333F7dgC63H9wVVSLtjKxGJtEbeW4Psa7UyK4Z1bm/fDE6FaEmAIcUQp+SAW9BfRFWZd7SJdU0W6RVUpOEKbRphWGNlXn4b8y3K8wcXdOMFjX+/N/4AwiGFeGUyzKdz281WIOqUSrotgFSAt3p+qlmyT97nI7VSPFFFkL+P8X9WEhVbxfgjC+LED1C5wdLOzKsrWhbuVz3xJ7TWaaBFI/F0Ge+2pEUjQmEC5r/sbfJ71Zba3ZUqpn5L95n5eAJ159j7S7X0do7CNDzLSXS8EZ2xI1tqhDmf+XQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from PH7PR11MB6522.namprd11.prod.outlook.com (2603:10b6:510:212::12) by LV8PR11MB8512.namprd11.prod.outlook.com (2603:10b6:408:1e7::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9412.13; Tue, 16 Dec 2025 21:40:08 +0000 Received: from PH7PR11MB6522.namprd11.prod.outlook.com ([fe80::9e94:e21f:e11a:332]) by PH7PR11MB6522.namprd11.prod.outlook.com ([fe80::9e94:e21f:e11a:332%7]) with mapi id 15.20.9434.001; Tue, 16 Dec 2025 21:40:08 +0000 Date: Tue, 16 Dec 2025 13:39:50 -0800 From: Matthew Brost To: Matthew Wilcox CC: Francois Dugast , , , "Andrew Morton" , Balbir Singh , Subject: Re: [PATCH 1/4] mm/migrate: Add migrate_device_split_page Message-ID: References: <20251216201206.1660899-1-francois.dugast@intel.com> <20251216201206.1660899-2-francois.dugast@intel.com> Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: MW4PR04CA0335.namprd04.prod.outlook.com (2603:10b6:303:8a::10) To PH7PR11MB6522.namprd11.prod.outlook.com (2603:10b6:510:212::12) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR11MB6522:EE_|LV8PR11MB8512:EE_ X-MS-Office365-Filtering-Correlation-Id: 80f57c5a-34bd-4abc-9fc8-08de3cebaec2 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: =?utf-8?B?cUdXMEFYWFVFL1NJQTk1QmgvYzNZOGlMU3l3VVEzeWxJQXVIdUdUYmJhdzQy?= =?utf-8?B?SnhkZDFBd3VqVVRRa0lWZ2ZkZldXMElRSGhCZUFVRzBUdVIvcFdmWjd0SXBX?= =?utf-8?B?M2hWR09Wa1RkK0JDRU1PWG8zdVJGV1hJMEU2WmdsYkpiNGpibkR1Q3M1dy8v?= =?utf-8?B?OVhOU0l1K1FiLzdlbmlwSVByUVR4emgxVUl3T3VqcXlRTVBZZDYxL0VJeHJQ?= =?utf-8?B?dTZJVlhiSDFPZGNuN2crLzA0Sk9Jc0lBWlZNNmQ3M2JnL3N4eXZPMDQrNmgw?= =?utf-8?B?dzdyamVYYTNpZ1RXMlhlSVNmcWlrMlcwQ1lEOGZoTno3NHJ6aHZwemh6cmNG?= =?utf-8?B?MHJHbGpEOE1kZ2t1Yk9ybWJRVEpLZ0FjQ3UrcHJYZ2lVSEVhcjJ0S2MrMUQ2?= =?utf-8?B?UmlOcGhxQ2hmUVRlTE12SVdMaGtDL3hOc2hUYSt2QVl5ckwxOFllN1JleS9a?= =?utf-8?B?VmhtcEhhV2NwN3pXenFUM283VW4wcC9LUGliZEFucWhYcWluc012eHhJa25V?= =?utf-8?B?WGF5RjJEcXNWcnd6ZUlhNkJldE1Jamp6aHRPSEF2K2RkNEhhZkhkMXJkVmxy?= =?utf-8?B?ekc1L0RyN2JKUXhES1l1OFVGQ0JZRXNEVWozVmtkNkcrcGVER1pqWUdUNFZu?= =?utf-8?B?YlI5WFh4azJTNkdSSm1Ib2t5Z2drKzUybGp4Ui9sY3dDQzNxdHVDQk9GQUpq?= =?utf-8?B?djlaYi92eEVyQjhCVEZ4bG1IQzRJQVltd0RFa3N3NVRxSDl1RWk1MzRtRnBU?= =?utf-8?B?RnNDWENRQlVhWHVUZG9nK3JlU0RwSEFwSGhxNENtU2MyaTA1WmpqYU5ZTFlB?= =?utf-8?B?cTR5L2w0TzRKdDJ0V21WT3lNUUZCbW1BRmhxREFkajVGQWpYbXFJRHZmWFJm?= =?utf-8?B?VnNkVkZkWmI3QmU1a3B5UFFyRjRNaDdVTi9yRmhIZ3lOblg0OGhSalBYekJn?= =?utf-8?B?VWxDMElpbGU3cEpiRXFwbFlKNDBMQngvSGRJZXVyTGRpcGpBSm1sTGJ2MnM3?= =?utf-8?B?ejVVWnEwNHA4WFFaOHJoaWp1QXYzT2xEcS9vZFNTQTdhUWtXS1hsd2FpdW11?= =?utf-8?B?YW5QcU5sRU04Q3FjR0E4RDE0ME1oWEZ6STRoLzZhcUROekxkT0k1QWtWN0Jk?= =?utf-8?B?ejFoMFZad3d5b2tUMFQ0U25kWkpCTGJBSmpuZ1NvUTBEZnB6WDhzaWFOY0JX?= =?utf-8?B?RkR0QnhoRmpqRTZCekVLV0h2VEV1eTViUFpzc3pTVW9vZDd1Y0MvbGg4TVND?= =?utf-8?B?VWtTMngyNk5yTXpMQ1NFMEJIck1yenhOV1RlNnkySE9sTTJMYzVlRmlIcGJP?= =?utf-8?B?UkI5dFQ2ZzBxVEpTR1I1RXJmQ1p1Rm9aRURDL2IyeHl3eUhjKzFZUG5TTnJM?= =?utf-8?B?aFFBbElOMVYrRlJjdk5FMG1FRUtjS3pTSCtNZVBwREs2a1RYMDZURldvTGFa?= =?utf-8?B?NjhWeGpZaXFZQVhaa2VXS1BUZXA1WTBDSWNtMldlSWNuTGg0TXhZbFZwS2pj?= =?utf-8?B?TnFzcWt5dGM0YlFRSUtXYkhJSDlCVVd2SVE5a2QvRjZNanBwUkF5cnc5Nmhk?= =?utf-8?B?TzBWU1QxZGVmdTdmSWNBdUZXTTJZM3JMMjZsUXYxajNxSlBOTGNsVkFQV25J?= =?utf-8?B?SkMvUFpoekg1VVR0SmpZTU5CZk9SQ2t2R3czT0hacm56cXBrM1owemlHNTQ3?= =?utf-8?B?dTJETXBrNGc4S0hCMFdMT0UwVkJjeE03dGxBQytHYTEvcmlYOW1OUjF1cUdu?= =?utf-8?B?M0JCM2p6dDZJN0N3YksvTlVQQkJBcDRzMzZQWGpzUHhLL0lIemF4R0wwRHhR?= =?utf-8?B?MzNTQ2hpVjZpTGhYOEhtUjNHZU5wQUQydDFpdkhjc3pVRmppZWFjRjJIOXNM?= =?utf-8?B?WWxMRWdGNGxlQm5kRXhEQXpmMUdwcEg0cElZOFdIRXozTlVGR1RzWk9MdlZp?= =?utf-8?Q?xS8T1rls9/EDJRozPrJMkM2YANbXJK1r?= X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:PH7PR11MB6522.namprd11.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: =?utf-8?B?L2pIeFlxV0VFRHozdEE1dWxsb3lPWlpiekw2L3hJM0dtZ1JFdDRWNVkwZXR1?= =?utf-8?B?RGpRY2xWQm5JRXNWRGd3SU9RK1Nra0FSTUliUW96OWFpZTZ3aVZKMUYzU3Fu?= =?utf-8?B?T0JIVm9pSFZ3eWNVbW5hYXNBWDRKbTQrTEVpdmdJb0FlWWxoZlZOTjZFMXNE?= =?utf-8?B?TWYyaUV6aHVpbnJQNmJLay92K3hKSlJoR2s3K1N3TFN1RWR0dXNzaTNKbWg4?= =?utf-8?B?M1dSVks4MVQ4RkI3YTg2aTNCMFRhbllkMU4xNzRSOUcvMkRMdVdsMUdqcVFJ?= =?utf-8?B?UVppaFFwL3JreVk5ZzczUW9Ob3gxMXhEK2VFZmxMU1gxc2VjN01URUoyTmRM?= =?utf-8?B?bStGczRXeDNVa2NUQ0ovUFp2YkNreHhrU1FVU3g0WlZxeENEN0kzenI0RHhF?= =?utf-8?B?K3N6eUozWFl0dE5UNW9yT21SbHdrMFY5VCsrbDFkYUVsVGt4VjliZWFvRWVa?= =?utf-8?B?RVNIUHlzcU1BTmx5MklCbTVia09ENytqd25kemEwWmFwdWRKVW8xZjRQRDhQ?= =?utf-8?B?K2pBMFZnVFd1Y0RSemkwNE9VR2VGRWNQdFNtUFhJbXBoR0VBb01SQmpmZ0Zp?= =?utf-8?B?ektxZFdiOHUrVk9ycDJncmdyN2ZMNGIyZW92bVhndnpFdnNtZ3dRNkNHSW9v?= =?utf-8?B?c1pQUkJKMk9rc1ZUTjZKMWZ3Sys4Q1hBQnFmQldVY00vbCtXUklNc2VWMy9q?= =?utf-8?B?empIVzdkK0RNNUhNNjR5QTNBSHpxNmxSQjZxSndqaEF1b3ZaNnI0T2ZNbWs1?= =?utf-8?B?SDdYU2JCL1o3OVdwcEtaM2VGMldJVDBuS1l1a3R4K2k1YThOTnlETFpBOGlh?= =?utf-8?B?NGZwYU5ZaXdjMkFUNnpoV2x1OElOT25hTlUrTnRQazZOUENYbzd2SnZFalN4?= =?utf-8?B?WEVYMWNFcmFvV1hyMFBrdlRtaEcwMng4a0xTQndCK01NcEEwZGxhK0xQa3dU?= =?utf-8?B?WnBEOU9rbG9ldzZuRFFNdnFDNmNvZVNxOW5oMkRZc3Y2Q1ppUlNCaG5wcEh6?= =?utf-8?B?OGhMb2Fkb1lNKzlyWDlQWmJQNGhMNWliQXp6cCtrQmovTW5UYUx3U3pta29T?= =?utf-8?B?MGsvVDA5OGZRb1FpSGdjQXoxbXp5QjFvRXcrUFBYS3FwZ1ZNV0gwMVB0OHAz?= =?utf-8?B?VGZ6S1N2M1dKMlBlVjVrdUQ5M0hRRUlaUzdLdTBjYTlTWERCL2RvY1RQZ3k5?= =?utf-8?B?ajRla253SnAxOExKNFJSVm5wWE1UYU9oNEo5clVFVmt1YWdoRlJ1TXlpTVZJ?= =?utf-8?B?cDlVc0RlT1I0bUo5Wk94cHA2T3czSXF3RTFyTk04L1hwdVpEck5FZXhpVGMw?= =?utf-8?B?OW9JTGNkakFwbGFDMnc1OXBVZjJTdlZoSXhvTS9PelRwS1YzNzlnWGI5eGFY?= =?utf-8?B?QlovOVR1QUVhRFJZdGszZzFYTmV0WTJnWGpvencyNmZjQWJiUDVYQmsxMVV5?= =?utf-8?B?eTZyeHRYa0pUWkhKQ2lRTmo3RXQzRDZMN0JJMWFReXlVclprMVVBY0k4SEJO?= =?utf-8?B?VDJWRVJ4ZFJDQ2c3UWMrMWJjenNRSVNmUExMaldoTnduRXNzMFpqTFFkUTFs?= =?utf-8?B?K2V4ZTRVakVrSTQ4SU5mRHFTUndLUkIrQ29EUmNRcUhoTVZFbWVteEk4ZFFB?= =?utf-8?B?OHArSldma2xnZWhUV1NjS1pFQStsSXVBZ0E2cDBRa25iNlJ6ZUI4YVdGVEJP?= =?utf-8?B?M0liRnppK2xCSWNqSXBnYWQwL2I0RjBkYzRlTEQwa1BSbm1jT2NlVXh6UGZi?= =?utf-8?B?d0hZbkxBOWNvRFpPcUtldDFES29wck00OGVSWVUybEw4UDBib1c3T3pQaXRD?= =?utf-8?B?RmNkdEs0Q1pnVXZFUld4ZUV2Sy92MnhpM3Avb0NTSnhvTFFncW1tWm5mMWx1?= =?utf-8?B?NXM2YytLNEthVElDMVhBSDlFTGUrTEUzRmRkaWkxcUc0aS9najlJZlNzUjdt?= =?utf-8?B?enZ2ZXIrdEdzRTdQNzY5Ukxrem5PTUdFZWFpbU5pZHREMmV6a3JXeU1Ha2JO?= =?utf-8?B?SmdFVHd4cEw1RVJaQTVjcUJOVzcrY09nREprcWhUZXBuNG5uY1dnbEZkcWdq?= =?utf-8?B?cUV3UzQ3YlZoaU9idGJpU2djTUlDYWlVYlZYWUFqWExUYmZCK29Oa25iUDdo?= =?utf-8?B?bzU0Mm92aGd5TVFjYWdPTHFNY3JKcFRhYjRrcHh0blQxNk83c3oyTWNjNDZF?= =?utf-8?B?NUE9PQ==?= X-MS-Exchange-CrossTenant-Network-Message-Id: 80f57c5a-34bd-4abc-9fc8-08de3cebaec2 X-MS-Exchange-CrossTenant-AuthSource: PH7PR11MB6522.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Dec 2025 21:40:08.1348 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: QiG20vjrfr1efiWfqHBztCr89PoOmfsjBTwhvdSqTpnyg+pdCptpTbzHaH26ZwE/+vVY8roioSxfUFqPtFaqGw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR11MB8512 X-OriginatorOrg: intel.com X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Tue, Dec 16, 2025 at 08:34:46PM +0000, Matthew Wilcox wrote: > On Tue, Dec 16, 2025 at 09:10:11PM +0100, Francois Dugast wrote: > > + ret = __split_unmapped_folio(folio, 0, page, NULL, NULL, SPLIT_TYPE_UNIFORM); > > We're trying to get rid of uniform splits. Why do you need this to be > uniform? It’s very possible we’re doing this incorrectly due to a lack of core MM experience. I believe Zi Yan suggested this approach (use __split_unmapped_folio) a while back. Let me start by explaining what we’re trying to do and see if there’s a better suggestion for how to accomplish it. Would SPLIT_TYPE_NON_UNIFORM split work here? Or do you have another suggestion on how to split the folio aside from __split_unmapped_folio? This covers the case where a GPU device page was allocated as a THP (e.g., we call zone_device_folio_init with an order of 9). Later, this page is freed/unmapped and then reallocated for a CPU VMA that is smaller than a THP (e.g., we’d allocate either 4KB or 64KB based on CPU VMA size alignment). At this point, we need to split the device folio so we can migrate data into 4KB device pages. Would SPLIT_TYPE_NON_UNIFORM work here? Or do you have another suggestion for splitting the folio aside from __split_unmapped_folio? Matt