From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CH1PR05CU001.outbound.protection.outlook.com (mail-northcentralusazon11010060.outbound.protection.outlook.com [52.101.193.60]) (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 6964331B812 for ; Wed, 7 Jan 2026 20:54:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.193.60 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767819254; cv=fail; b=a2Ep+PsRp8OG1LtXn5pXn9Eg4GH7AEZTbFgJeX3cVKI1DYJnkpVF3ZIYhPyoYtCX8I0RnED2steXMDgHuF4uZ9/2reoNqKvtPDnAKYnIwLsHzsCWvYDvQ10hvdJuKBYZ2YsWhCBHzEkJqBJqTcQy9nqlEfl6GJDxTDrs/3aXfbA= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767819254; c=relaxed/simple; bh=Hc/vx75SWqfZ17r7Ei3C/qDWhOgR6Dy9HUbWNm+PuQ8=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=MrttSUMOPTcNAgAFYSzFe5cwSICMH2P1IVmRiL8bxPb932sw7SZ5Vjo2Q8LyT+sqmflK/dlsZG+1bbBFxMtw05vof1uQQAJz3ndeNaLthXizytOUSCM2HLRSF6V5tSmhOSlwmc+gTu+h4MBZJUkgKT2KlOxWh0n6lozDCU3Ja18= 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=uYn6Zpxp; arc=fail smtp.client-ip=52.101.193.60 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="uYn6Zpxp" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=oBRP/ZBAJYnGJMDYQXpy/FypIkrjtEa0wlSPmJ7NQI7Sft21ETmvVCRwm9FnN4g8gD/bVik4mvMxK3RmYcGIMZx6eE/r3adBT6JCGS5MV95j1ZYcBuejmS4FooD9090aC98NF4IgGnPk9igsMC5nlprzw2qPXOJZv7zfysJHKFX3VzblmUvffYji5RfuGSuAjrKnM95ITFBOt+yB3bHz70np4+uuDfMWv59wW/OxfcZLIvsyyolwNz692qNMbYdFTXX8NY2p+72NN4XPxtYPqLFxKwwCXNVJwYjJMZwLdFMlYdGMdSUxo6Hm1yuEDzjeXDTotNcWyYFIbFc4xlJvBw== 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=bg/+TeXfpGaelqWXlfi2WyIE54OghyTP7ekZYKuGuvY=; b=TkqGSsyv8Sq9VOY/FGLYqXcO7AebmBK5hXV0tJ+CCkziuUa1HXc/vSxk5Ntic/B2duNOKvVKNsCcmfKOcZwDApxRBiiNcqgU2f+V3Tn7ZywQ4HK5kW0dLsuF8+zCzeM/4bkQbBSePCIU6d1wqCNfAqR0VcJ/9ajLfWBQr/Z0pkFRDvQ9/1Us0n8/55eDAWUMtDXO1UPzfWPTPsK0p0YOJyWJ/6UzR/7RTpnlSIKHNsGEOGpU1U5EL6Owv7YeVNDKN4IzqK+gqXdRCCSyNnbT7wjmSIJ37LPNfu2LZby8revJVLQ2YcdpVz8ScQDEjnMfJdPVMlNj/QR/Ga4PvVW/kQ== 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=bg/+TeXfpGaelqWXlfi2WyIE54OghyTP7ekZYKuGuvY=; b=uYn6ZpxpoQKQAhE1YvSYwKljqRQjhtPvO+X7Vun1OiqPFQgGAJ+dNOajGq3Y1vj513hw86s88jk+Zdnn15g509fk0HWB12imZYhwKq0XSGtcHtLZC08I04O2wKtzwGwurCvSpQmCfW0UK7AvckAy3Fo/2ipBc2kCrtX6xc8zPPoUEv3nRF8RCQpljpihxSPuZ78/pCBb7ynfvnV6Ow4RfDIPCFYHE1+ri5uczquLjgp184cr2Ahwg0YODXmKDEySmJWI/IzpjbGxQ0rJKLmt+5HzDUI6gZnpqluQlEd66gfW1uk7kvWVmZy2iuFumZzyXoBQQTSMfV5h9WUJzf3Qkw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) by DM3PR12MB9414.namprd12.prod.outlook.com (2603:10b6:0:47::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9499.2; Wed, 7 Jan 2026 20:54:05 +0000 Received: from LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::1b59:c8a2:4c00:8a2c]) by LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::1b59:c8a2:4c00:8a2c%3]) with mapi id 15.20.9499.002; Wed, 7 Jan 2026 20:54:05 +0000 Date: Wed, 7 Jan 2026 16:54:04 -0400 From: Jason Gunthorpe To: Andrew Morton Cc: Jordan Niethe , linux-mm@kvack.org, balbirs@nvidia.com, matthew.brost@intel.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, david@redhat.com, ziy@nvidia.com, apopple@nvidia.com, lorenzo.stoakes@oracle.com, lyude@redhat.com, dakr@kernel.org, airlied@gmail.com, simona@ffwll.ch, rcampbell@nvidia.com, mpenttil@redhat.com, willy@infradead.org, linuxppc-dev@lists.ozlabs.org, intel-xe@lists.freedesktop.org, Felix.Kuehling@amd.com Subject: Re: [PATCH v2 00/11] Remove device private pages from physical address space Message-ID: <20260107205404.GI293394@nvidia.com> References: <20260107091823.68974-1-jniethe@nvidia.com> <20260107120608.5ccd2cc7e4227d2e80028bd9@linux-foundation.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260107120608.5ccd2cc7e4227d2e80028bd9@linux-foundation.org> X-ClientProxiedBy: BLAPR03CA0092.namprd03.prod.outlook.com (2603:10b6:208:32a::7) To LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV8PR12MB9620:EE_|DM3PR12MB9414:EE_ X-MS-Office365-Filtering-Correlation-Id: 1e9ffa15-abb3-4d2c-6de6-08de4e2ee509 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|366016|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?6o9KcxXnCK3SikQTHuHdPKNboUWlMyd+jjbPumtmLKQDMsnfzQu+1Hw4nE4k?= =?us-ascii?Q?XN0/+LW5RkIkfbUy+Tesz9hmBqdO5fFO4lmWgT9pdlLpvy1+qvKIROMWf2n7?= =?us-ascii?Q?tLTa/1N3AzgYjftqkFwwcg0IlBD52W6a0apg1hxxU3ZCe6MQtg+CnHa9U05+?= =?us-ascii?Q?Hh7bAl1ezQkczcoBzjgYXLSaI3FnmsI8e0Cr/1bEjfZQK9QAKDX1sgD3hXJ9?= =?us-ascii?Q?DCjtLaymD5yZhtk6xz8u2YjxRbxfPcsXn/1vFDte+XYjSo5hVJMSsWOlh+wQ?= =?us-ascii?Q?RiBQc2AiEmZWgtCd8ZuiKb/aYgeM3Z9Pzz52Q0zfldWk1zYH7i0Qh9SJKNgF?= =?us-ascii?Q?BXhR7sBqH+Yj4hRn2tql7XsrIo2IJK9VnQSECBSjJ8R5DS+dqUW5E2kZXVfy?= =?us-ascii?Q?TtTA3TJ5u5ohIM/7BcDQLFnXgBq61wHvMuIsIhHpi+qnZxsmP1LFR/qRBas3?= =?us-ascii?Q?FCVj+kNZEJYgVhWWk8dqCKGyJmMza9p/+Pft13FPiRNLCJ+wn9IP5eg/MNEA?= =?us-ascii?Q?IdS0JQchjf0XtJywn49Grn7gbqFAUdYNsW7bd3rk9CeoGQiFjwiPJfeWlOMm?= =?us-ascii?Q?cLa+AXzR9ghR2XP2M+ME7jj/Eyci223GTY9ayen6hRqkSLm5Yn9H3/DJJhyP?= =?us-ascii?Q?AYfgHllI3g0sRTJtltQEXiZQZ6Ehvp3l8CiZ3qcob/FxGAX/xvL222/0KbZW?= =?us-ascii?Q?TyhZS8k66TSCeA10HHvoFOB1uTLxsqfo26+arplL9eRKxwgVIvD7VuBbkYpm?= =?us-ascii?Q?YWYNPV3yPDM0Bg/x7Do6QXQaFzzPXSVHaILRmW0NSSW4X7AKdtW/H9WE8bPY?= =?us-ascii?Q?7+ip98jaTO3Hs5PxPYwrtkoGHl7F+tHoDJLIs7MJ1iUnIe+uTobfvrjrJHBh?= =?us-ascii?Q?MckIDTvHzGflkQMhgSf+WxQgUkDqlO82dSAI/hMnDeit7i+55loNGdQrARhH?= =?us-ascii?Q?A7L6ahRTGQnw4QOLQmzADcBU1QHha6FNX86YMhKa7aWaECYeEyOxAwE8T1sl?= =?us-ascii?Q?EG6V6PoGNj7jv2NcAmGvzrw7zWfIM1FcbrINfcyhkpTNhFq2GkpBadFWI3eE?= =?us-ascii?Q?Z/4GPG5fRw0lekHSJaLTDgMDNyXsJaWPUKacwN+wEWy5EkWgj8CqCkyCexJK?= =?us-ascii?Q?hQjiWCM16BU/UI7DlfAHqQHpSbhnAM/abszEeHoCrhrHY8tSQUJ+jWR+66FC?= =?us-ascii?Q?RnT835RZE4GEye3vckKUy/YpELMgAkQ6gj+It67cFSkhV+BxJKgc0hOC6WxD?= =?us-ascii?Q?be+f9lpq2rpmIQWvvvGYgDqi9UOOf3pM8V6HTn/CzVq5CPGxOVsotfInDzhU?= =?us-ascii?Q?sLYNoXZXQUpa8QJ6moXoWWNYvxDQ1UbnjQdEVYJgpbCcGCJyfI6qfHibfkXj?= =?us-ascii?Q?AuITjOqhxauuvlTd4jhNq0jbkAUnWB2lqUmvDzz3pfAdQ3TycFaGhgr7bAw9?= =?us-ascii?Q?maFz5noza9M9KvsfUzPsztR1LpM7y8Cj?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LV8PR12MB9620.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(366016)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?eOPPs13Yk4l5ydwfFLssFlVkchbx1ESFVjpFTv4dLsI7XUafVLDBzKqmu25F?= =?us-ascii?Q?atl2rIpUZ9f/9vNX1pF8s0igrmiKQM89U8Imgck3CVE7rkhdEuEzmjR0Eqa4?= =?us-ascii?Q?awIXR3xW7fvDnptPk/Iof82OAzgPWSe5MFoxNWNRywFbAGIBFRc8kY9PaZ6D?= =?us-ascii?Q?lV88NOqrWOFUudRuow29UAxxg5owU2rebAi9aM01yznvFd7aWgIlJEJlUOvl?= =?us-ascii?Q?5sCSX4rMXH9uY/c8DK3NgOUm/bkczqT+RcxrJzRuu5lOQb/y93UrCV7+zIfJ?= =?us-ascii?Q?/U0fANE1lnRa5qFmfZzJanCLIc8HvSWN15cAd/bl/u4aV/iVhu3y2vd6GSwi?= =?us-ascii?Q?fgr92D7ZRuqS3JzutUHfV7tAxL5gPbV5lmvS4W4PONyHosRKU+kf6FgbvKXa?= =?us-ascii?Q?IyP/hUxYOJpvO7zmbK0kxuQniqEuyYC3FzcioJrZA+I2s9/63a2hXld6BJev?= =?us-ascii?Q?yi16ELdCS/6tsMLARjs9sObqcKiNQPcWsmGWrbe81uXpOpMviOKGpcxQvfRk?= =?us-ascii?Q?evIxrVFpqL1vAjXhac1zCn1JE39sLmW4FQg33Ck03/kAKUJ8G6bMNeYreXpR?= =?us-ascii?Q?TJFz2RWxU87zVAO5F3lqeX3Ynq87AYdlalmkHxF2ec6g58MftMzh+0lJ6lDB?= =?us-ascii?Q?FWZbbU/zHqPXteDq2CMLqbm42DXWN9pTFD/KzOXwSguDTyfx/W5s+XIltq79?= =?us-ascii?Q?09Brdf89ViQRj8Q9/DcF6qIptDmglVocEw3Y5OdJwe2SIMhW+/9+C4udIl0c?= =?us-ascii?Q?KMxzZtD6QtATIJXboVyQI3mgGeQW5Vzx62sOaYayfztrRtyw04GmHaKYKAIm?= =?us-ascii?Q?yNkzTHXnLGFYJgP8k0W/sVwx56bCkA+lsLGGVuKhx+zLTE5ZSkrCja6ZkUEj?= =?us-ascii?Q?pwRMGKgrj3qiSRSy4pIWWmBBQ3lpj6OnL5c5e4rgQh8vB5eRslMzTF8eGqoY?= =?us-ascii?Q?aw90ZCn/FEmtpCJH4qTfbRUzf7Iz8Zyd64/KoWLGs08M/w7Fqiwbse3nn5mq?= =?us-ascii?Q?zfZgTPNWN/dzghHrOku/mpXe80db05x61mIQslcolnulMldeycV2Mi7iUsB3?= =?us-ascii?Q?1QxRC4avbb1rHHf/xYHX0Tge5XTnkJPBFkiKz0BuIG3qGgieb+IPrAbCo0iv?= =?us-ascii?Q?1wvvlfLUIPC2FdNwUZr1AHYGHVUtroqask/7fWjNmNlvbvmr2wLjymufTqga?= =?us-ascii?Q?wusEJjgdAhnVdXMem8UOrFTgWjHBDnTLnF5yzUhNPnpxcT/svF6QaNALejjJ?= =?us-ascii?Q?VICqkW9jdWFwcNlYVKzZjDoLiS0gZhmGpOHKHcXE4OupmLnwqF+OrKrEkdLl?= =?us-ascii?Q?awpuePS55pxRXc81yFVgGsMNOxlkiE64qcWrPvFse/pVQ9ZQQN3+fcqT4SX9?= =?us-ascii?Q?/YB+HCVFOK/D1Tio42UsEOUmzL4oIo+EpkZv7QWYNihgDWcb/BBs5H5iOn2P?= =?us-ascii?Q?tHwXXChAYH++rFlwFMm8X4wmat67QdIBSIbcCYHNWjbaZAIg/NI51dqA7ztb?= =?us-ascii?Q?uEqRGBPzf+1RLzLZVwUE9sV40CIXIz8x874XtAgX208XJ0JfoJKSFh8/WA+0?= =?us-ascii?Q?NS6y1vreQ8BmD4QbLyFhYeJb30DY7LPCXdtBXL6X7bCA18yBwC3ZsTsln7UL?= =?us-ascii?Q?9WI51vjxp9timizOoCjRNA8dhLNhxU5JCnSzPmKpd/8WcuJ6fsk6WKAqYzi/?= =?us-ascii?Q?vn4g89zXikutap4c1810thxTlxt5IuiMGpyc4bLE3iAf78Ks21da4+LBY2H9?= =?us-ascii?Q?VqklkMbFqg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1e9ffa15-abb3-4d2c-6de6-08de4e2ee509 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jan 2026 20:54:05.3701 (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: W4o0C8uj7Jy4xeNwzhu98tRrbtEq8eHjo4FmvJ+RJg0wuT9MKcnuGG8TQddIoloD X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM3PR12MB9414 On Wed, Jan 07, 2026 at 12:06:08PM -0800, Andrew Morton wrote: > > 2) Attempting to add the device private pages to the linear map at > > addresses beyond the actual physical memory causes issues on > > architectures like aarch64 - meaning the feature does not work there [0]. > > Can you better help us understand the seriousness of these problems? > How much are our users really hurting from this? We think it is pretty serious, in the future HW support sense, as it means real systems being built do not work :) Also Willy and others were cheering this work on at LPC. I think the possible followup to move DEVICE_PRIVATE from struct page and reduce the memory allocation would be well celebrated. The Intel Xe and AMD GPU teams are the two drivers most important to be testing this as they consume the feature. Jason