From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011068.outbound.protection.outlook.com [40.93.194.68]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6F981917D0 for ; Tue, 16 Sep 2025 03:28:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.194.68 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757993287; cv=fail; b=HktxymHoa9HDpa5Iktf8GgUZtyS2ecOL/TLOpPsLZyAmHLAiP2wrbs87KLGNhgaHDol9KzYRBFhAfCa6yj3i+Ms0qKYP6GOWnv7+XnyZL5HG/0wrlEAs1Tz8EbPEu3ptYFqJwVhUntCq5dLMii81vMFWYRh7xn8vd6Yq1JuM1Yg= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757993287; c=relaxed/simple; bh=cx3yASvPuYb8V5q63ksLEcLIIALV6YQiqYKmIOaAkOE=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=TGpNI71eKMeg6j8mz001N32XZl+G+rZr9NcPaoPK2YP7/RA5J991ndjGTnsckRc+wMQ2vETeQPl5DNeFzIAYBt6hrIST6Y4c2tGu+86wG6u9IA9hn+tlCJ8OjdsPFYpf3tGHU1yk/ZXf41kd7KT/vkZgu9tnAEeFA8NtIwG5ido= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=F0z43rKn; arc=fail smtp.client-ip=40.93.194.68 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="F0z43rKn" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=KdS/gnPG1biWB6/8ZaOBCz6gEpQ+IkMNDS02FtYnmJMlC7YTzW/xkOH6Zzp24E/dy731SlcMM8h6pKzPJgZsiiBKwA9Yj7ohBYhXHQaUm0R+QiQtlgBzSP7VTGJugGQPpay8IW+AgHUUbOF8ZgnHZYNpytGQ17ojot9+t/VLlQox8rthsR9NhteyWe29yRPcQiZrVzgwog2FWcU6c7i4RGB04V0R6W9frO3vEWN0BjqPPAnUEohAjWNDb53APRG60F2EiVUX78euGXc5YudTItJVHXeglMD1UxGhCiKfXZvNYnmKYh7jXRPRDfn/aNNvqTz7xIuPPWB6WZyX4JOSag== 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=Al5M5VeE0PAyYl9c38zXqXAIw2Fm0hrGybMBZbWTtIc=; b=KpzVxWyk4uAWuLDTqKy/IfCkTsCWkA91mRHwWVJbC4knyOT/jG7Z4qtlMen0UUmsaaKKfQBvoG0orOrfVeSkiH1WvESjwZURkU7lznEvr8gwRLhGVa207XXxt/MHMAWRMPcgkr58UvcuHPtRi5hr2TPDcT11g9xfchaarv12EyWCT2AE6W/147ujDq14zTU7H4wQX0Q/tCGZ2n/s+TeV+Hkb96pyoc9T6CF7DL4KVGTYXgQIQcnyka6kW6waM14IVM4fW60cS+DFjXvUaYnkc3Fgbos3Ycltf2oikxMyAXf6Iadp2GZsaewXcA2z/DglfSTbzf5TUtzdCpl/cMelGQ== 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=Al5M5VeE0PAyYl9c38zXqXAIw2Fm0hrGybMBZbWTtIc=; b=F0z43rKn/52Eva25Ax0OtLpLxRqAuYEigj8X/OU4TIcnprOKj9FGaaFyUeT6biztajBzGjq4iPWM2zElZV8CJQOErglnojpMFmEqb6q7P7GXd9WBZ3Hk/MTziK0Xk6+8Iy6K+aZoS0a1S5scyxe2r2b8wEjrSBz/PpWKnD9anec5MJQ7fLk+VrFVLA2moV1SX6oSqul7paUrjeFGP6ytCwlIts3zPVZZCSJmKvoHML5ul47Cw3+9C6/RNGOuZMeE3v751HBHZnjk5VYoyZTt432pHGEfahiwBPsdneZuuXCHEPmUGNHa0LE6ydW61DHSSG9DXVGobFPcF23fWj4biw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from PH8PR12MB7277.namprd12.prod.outlook.com (2603:10b6:510:223::13) by MN0PR12MB6293.namprd12.prod.outlook.com (2603:10b6:208:3c2::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9052.30; Tue, 16 Sep 2025 03:27:59 +0000 Received: from PH8PR12MB7277.namprd12.prod.outlook.com ([fe80::3a4:70ea:ff05:1251]) by PH8PR12MB7277.namprd12.prod.outlook.com ([fe80::3a4:70ea:ff05:1251%7]) with mapi id 15.20.9115.018; Tue, 16 Sep 2025 03:27:59 +0000 Message-ID: <8a2c4803-d613-4592-9114-d68b97bf3fb0@nvidia.com> Date: Tue, 16 Sep 2025 13:27:51 +1000 User-Agent: Mozilla Thunderbird Subject: Re: [v5 02/15] mm/huge_memory: add device-private THP support to PMD operations To: David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: damon@lists.linux.dev, dri-devel@lists.freedesktop.org, Andrew Morton , Zi Yan , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Oscar Salvador , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Ralph Campbell , =?UTF-8?Q?Mika_Penttil=C3=A4?= , Matthew Brost , Francois Dugast References: <20250908000448.180088-1-balbirs@nvidia.com> <20250908000448.180088-3-balbirs@nvidia.com> <17e3c19e-0719-4643-8db8-cf8c5b5aa022@redhat.com> <49776f0a-d891-40be-bce3-c2b1f16bd825@nvidia.com> <4de00290-7c29-42f5-b8aa-58a77b17c1d5@redhat.com> Content-Language: en-US From: Balbir Singh In-Reply-To: <4de00290-7c29-42f5-b8aa-58a77b17c1d5@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: BYAPR02CA0043.namprd02.prod.outlook.com (2603:10b6:a03:54::20) To PH8PR12MB7277.namprd12.prod.outlook.com (2603:10b6:510:223::13) Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR12MB7277:EE_|MN0PR12MB6293:EE_ X-MS-Office365-Filtering-Correlation-Id: 35cdd70e-1b82-4682-6ed8-08ddf4d10905 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|10070799003|376014|7416014|1800799024|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?ZnpDVmx2T09Pb3R5eFA4OWlhTHpibHFwZzdMeU5CMWFXWGJPZjl6TGhBdjA1?= =?utf-8?B?bTZSczM0QmpLNTFYTVMvYlZVQitmQXZlMWYwVm16dDJhOUtoYzlxSG9kSlZR?= =?utf-8?B?TEVUdkxtQnRTTkZSUGNCQU0rcXlQbFhjMldTZER5Ym8rOG43cnF0TWpBdXVR?= =?utf-8?B?bXFMU0U1ZWs5M3dCZkM4MEs2dWFUcndOUldRSzQ1cjJrWkxjdmRvUzlMcElI?= =?utf-8?B?QTM0RGJBLzJBMWQxM3hxNWc2NHUrVHNHRGFLWHN1d1ZZcmphb0lwRHp5ZUZx?= =?utf-8?B?dTNwa0k5aTdMTDFqRHdHUGlrZmhkRmV5c2diVWFDZzBmSzNjOWp4RG5JeHZh?= =?utf-8?B?OTJXRm5scDRjSFhpaURBN2FBWXlnaEpkNmFEWUJTR2crc0psMjNBS2d2Wkxt?= =?utf-8?B?NDZ1RVpYSHdjd2tCRWE3dXdDNUlFems2OFZLd2JXMjBRMnZUOHpxZDdmTlJ0?= =?utf-8?B?aXlWcEhtc0RTeUtZYXJFT3hET0cvdy9KNzV6MzNQdmxYQ0ZTUGtiUE9adEtk?= =?utf-8?B?ZzdRYmx6Uk42QXdMNjZVUkhpekFwc2FTeVVaY1Rpc2NXUnU5bzF5cktqM1da?= =?utf-8?B?V3p5SitQeVlnL3ZxUFJzT3pOU2JzbTlVY0J0dTB4eVFiZVgrMDZSMlY4OGYw?= =?utf-8?B?ZGxhbFoxR0NQYjVneHNha1N3M3NwNncxU3JVK05UZlBmTGREZnhUYTd5SWlI?= =?utf-8?B?TkRzb0JMNGhIdUhITHdQUFNOMm9tdlVvUGsyL0pRbkZod21tZG1aNnR3Rk5q?= =?utf-8?B?eklQNVdRSFArcnR0UGk3WXZ5OXZuQ0ptSE81WEdEc1JmRUh1ZXJVbmllMzR4?= =?utf-8?B?OEJSbkJOZnJoTUhlam11aCtSU3ovS2lNR3FqNDhTM1FIa2VhaERXbXN3blBM?= =?utf-8?B?YlIyYTZDTHZ1RE5oYkhBWWxwYXFQdnFMcXoxWG82Y0taTTFyNU9HQkFkR1h4?= =?utf-8?B?aFYva2Q3cGplcmdlT29laTQvT3lDSzRDUnhnZVduNmFRcXU3dFc2UEgxa0ZH?= =?utf-8?B?R3JmdVE4QVRKbTZ2VXdVOTJ5SC80MS8rNU9xcnZDMmlISEQxVHJybGplOUpt?= =?utf-8?B?RzcraCtDOGZ6VjBmaFA0b2RrLzFRYWpxT0VSdFc5Q2wxYlRWcUtiVGsza2ZR?= =?utf-8?B?TVE4bnQ0c0JzcXY3WlhldFFsbUhORXBDc2dUZ3JuWDI2cm5QM1dXY2ZwNU1a?= =?utf-8?B?SWJRUldiaVNUR1B0bW94SmZzUXpZWHNiaWZ0ZnVkQkhtVXQwUkUrNUlNNVZn?= =?utf-8?B?R0IrUWhVVENFcUZOUW1xTUVwcFFmRXVHODBCVW1tWHVhR25xb1ZEWmk5VVdX?= =?utf-8?B?M1JaTUxNYXZyRDhMN242RUNNNFdwcGE5Q21lK25CZGVzNkZvR0xMRi9ZRkx6?= =?utf-8?B?WUw1dmZ2WGFzbkZ3M1hjRC9qTjAxYlhtbHB4eGpNUjlNY2J5VmxFcThVMlJq?= =?utf-8?B?ejlTNnVMdWdpMDNuejhucmJ1N0hVb2x6cnBLUWQvWUpobERnZkowM1RSa05B?= =?utf-8?B?eGhMR2VOcTZYNW9uUDBpK0RDK085d2l4ckphclc3cnpySnpBRDJkbUd4V3dB?= =?utf-8?B?Znoyd25ESnlHTkErdzMzQ3ZDY1QwamF0cllydkVBdG5pWEc4MnhYSGlqLzZ2?= =?utf-8?B?YkgzMGM5dTJrbWN1aGJKbTlJRTZZMThUSTFMMXdhazNSN2t2ZE5oOEI5bUN6?= =?utf-8?B?cExPZjdEZ3NVeStRWklnN3Qzc3laTFdaaEZwcHR6QUllMHR3TFJnT2VkYVVy?= =?utf-8?B?RXVaa2dnQVQxSHNxdTJWSHdoU2xUTFZlRTU4eE5FVTZ6N1FoUEtUem9JNXBB?= =?utf-8?B?MXFMci8wYnNSSXJnNm1aMjRCdkZiSEVtbEZJdkI5T01heXV4akN0bXJZdzFD?= =?utf-8?B?Z2ZERER4WVFKb3g4d2Z0WEJ4YVVYOGYza2ZxUW9MZUxRQXo0NFZwRHN3WHpN?= =?utf-8?Q?s+ZP/F8brHA=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH8PR12MB7277.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(10070799003)(376014)(7416014)(1800799024)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cnoyeDlOdlpLM01wbWQ1SWlWQWtXZHc4Nkd2bllYSHlRKzZ1SFk4clg1cVFX?= =?utf-8?B?WXBzWnlRZkhabHJnc3NpeFVJU2hTSThiVzgvRmN4NHRSS2dKMlNSRGE5WDFX?= =?utf-8?B?ajNUY21TdUI4NTFOamx4NzEyVk40VUUwalVmd085YVhnOEdDb2NQRDIzZlEw?= =?utf-8?B?bkdlWFlxSEdHVmN6UWRDeTh3VjJVUmZzS0UwOVhVMUJ5RTlaVVRQWUh2b1B0?= =?utf-8?B?YlNBb1lHQytmamNZSTJoTnJWZ2x1M0lRR1dlbWRoTDhxTGs5Z2diaStHbVB6?= =?utf-8?B?K25mWEJPZzFMQTlnNDNUM3pQN3hOa1hEZGJSZzF4czQzdk5DNU1nbGZwY1hp?= =?utf-8?B?NFVjTVpWSzBQRldPMU1QUmg1MFAvUlRXM1Qra3dNRkpWN2xYWEtxTEYxZnAr?= =?utf-8?B?VXQxYzk4eXQ1eURWU3ZxM0ZmM0tyc0lPNHMwTkI2NzNVUVRiRmE5YzMvZGZ2?= =?utf-8?B?VjFvaWg4bUo3eWdTTWkvNGhSL2xaTXdEaFNENzFuQnc2L1ZUVGVhOGcxOVh1?= =?utf-8?B?Y0l6dEtTRWxjbUJ4VWo4RllDRDFHaVM2OUlpejNidjRtdXg4YTBQNTlHdlZv?= =?utf-8?B?d2NWV09HTkVzV3N3a3dHRDhuTEZuR1plNmRNY3Q1SFRuMzhhdlY4RGtuQ2dD?= =?utf-8?B?bDBxV1lwNTJkc21WNE1mOUxaYVVSR1dNMll2c0tveGlqUDg2Zk14TVNMQWJy?= =?utf-8?B?TkNBc1N0K2ZFb3BBYk40ZDNVS2taOTlyUzgvaS9KZTVuNFVuTmltN2JHUEhN?= =?utf-8?B?RWVrMVZVNXExRlh0NVlLUXhTMm54YzhiZm1lT3hoYk10bTBVZ1FqTWJOenhE?= =?utf-8?B?YzNZZEpkVk40VGt6WFZNSVkxRUpEQXdnYTVlakpqRlRBSWx6OFppQVkvZDR1?= =?utf-8?B?U1pVam1qLzlSMFVuSkZPV1c5dlRjcEpWaC9GWndmRWtLelQ4eFp5N1FWVHdz?= =?utf-8?B?SEd1NkhBbkxSOE5uSm5HVW5ueXhkeVoxSmp3c0pjNUx5TDd5V0lRQmMyL1JH?= =?utf-8?B?VjYzbDZnTExLU2xiQnJiZm5CbVVocyt0b1hEaEtKVE5COUJNTElRdVRsWnR1?= =?utf-8?B?MzMxMGJOQVJOWllGb1dqVGhwdXBsSmEvcWY0TUpkSm1XZDR6bEZRd1ludTU1?= =?utf-8?B?OTRGemFabjdEU29CdVBhSVJ1RjQzZUhQMmtpN2ZqKzdKYU5nV1p5aHE1ZDky?= =?utf-8?B?cEM5WWRJNjdqeGJ0WGlQY0RLU2tLMDY2K3RVTS9NNkdpNUczTExGQzNlTnI0?= =?utf-8?B?OTM4TUN6SndzenhydjRCU0dRRmhwN1Z6U0NCTElBZ1NBeFZqRXg4c0NaS2pS?= =?utf-8?B?b1N1WVRjTldIQjNKY1RhMEZ4M3hlL3FpemwxanIxVW5hM3VYYnBobHg1bTQv?= =?utf-8?B?MG83VDZ0M0xVdUFWT1kycFZUTmJ4MEFBMUpET1Y1V3VHTXFYdzhKNC92ZkJC?= =?utf-8?B?T3B0RjZmYVU5UktET3BNcXhuNnRNRFcwZjBTV2o0MFpSbXVvZDdlTkNUSjBS?= =?utf-8?B?dmNxdk8xVzFkSXQ0bE53QWtwcXVJM1Y1YndkK3hleDY1aGlWcDBsdlZoTFkx?= =?utf-8?B?cTFkNGg4dzhoODc2aThWRTRKSHVnbFdPNWhiSDYzMVB0RktKMDRxdGVKOHpa?= =?utf-8?B?WUlOa0tmSFdsbWFEVVpJbVlCUWlyd0RRcC8vZzBTaVlGZUE3cHp3eitCbWFZ?= =?utf-8?B?SGxxUVJOTHVyY1VtMU5WSW91QnQ5Z3dNMHJCNEl0UnhmMXYrTlRMZ2pjaTZ4?= =?utf-8?B?aWczNTBCZG12Qk5tU2hsSVp6b0UrMGJaU2dQRHI2S0UyTWRsT3RudEI2dGRD?= =?utf-8?B?N2FzUzM1NmZnSHhDc2pSckFsMjZDR0htMms1bjVhRUNtbVFDUnFEajNzYkdH?= =?utf-8?B?REpwTXZFSGtYVlFhbjBVTEJxYUhOTkZKSjUwdjl0VkJWRXRlWUFnRWpSWlZB?= =?utf-8?B?UFZadk9RUEdoWGNxQ3RYcmJVSjJua1Awc3huMHJ5VXJVTDlrV3lidzRxdDVw?= =?utf-8?B?bFJ3NWUwQ2VYSzFWWTVIQUxiZmhQbU9ib1hncXlGQllydGUrUVRvWTBKR0dP?= =?utf-8?B?czU4MDI0TG1vU1VRVTEyM3pCZ2pJQW9hRFJwMHdDZnRUUklCc0RMc1ZZczhD?= =?utf-8?B?L05jTHFTTG1idnVZUy9xZEFESGI5c1ovRzk5Mjdwb2ZBajZuYk1nOVNXSEoy?= =?utf-8?Q?VQW0+NcnrHBwefNDU/3Kygu5jU81vZzb6S1KLRbMc7c0?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 35cdd70e-1b82-4682-6ed8-08ddf4d10905 X-MS-Exchange-CrossTenant-AuthSource: PH8PR12MB7277.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Sep 2025 03:27:59.4874 (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: ZD1xHn4QWDZcJhzT2Kfs6r7CGM8aRf5o1oJKpV/z26PcmIvcbuBmfA9kkUDFxt0iTYE7pKYrN0MOm01sT7v+6g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6293 On 9/15/25 18:10, David Hildenbrand wrote: >>>> + >>> >>> Wrong indentation. >> >> checkpatch.pl did not complain, what I see is >> >> +        VM_WARN_ON(!is_pmd_migration_entry(pmd) && >> +                !is_pmd_device_private_entry(pmd)); >> > > David complains :) > >> It looks different in your reply (is your email converting tabs to space? >> did you want me to align the conditions? > > Indeed, looks wrong, not sure why. Likely I messed it up. > Ack >> >> +        VM_WARN_ON(!is_pmd_migration_entry(pmd) && >> +               !is_pmd_device_private_entry(pmd)); >> >> > > Exactly. > >> >>> >>>> +        if (is_migration_entry(entry) && >>>> +            !is_readable_migration_entry(entry)) { >>> >>> Dito. >>> >> >> Same as above :) >> >> >>> Wonder if we want to be more explicit. >>> >>> if (is_readable_migration_entry(enrty) || >>>      is_readable_exclusive_migration_entry)) { >>> >> >> !is_readable_migration_entry => writable entry or read exclusive, did you mean is_writable_migration_entry() >> above? > > Yes, sorry, my brain was dizzy after all the review lately. > > if (is_writable_migration_entry(enrty) || >     is_readable_exclusive_migration_entry)) > > [...] > Ack >>> >>> Couldn't we do here >>> >>> if (!pmd_present(pmdval)) >>>      goto nomap; >>> >>> To replace the original pmd_none() .. check. >>> >>> A page table must always be present IIRC. >>> >> >> I am not sure about the pmd_none(), a page table may not be present, I've not audited >> the callers. But I think we can do > > IIRC page tables must always have the present bit set. So we can just simplify to the single pmd_present() check. > Not sure about that one, are you happy if we follow it up later with a separate fix Balbir