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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 EA514C3DA4A for ; Mon, 19 Aug 2024 12:22:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To: Content-Type:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=PJfxMW0zjDw3au9LEf+PHQM/rUd+5+X4kZyP+vyKgqQ=; b=jAhijSzZITVAR2DZgS6ve1IXCv ZaNvEdpFwGt8cgiTsQqZ3t5JVbOb5CNOeZFycKffaLu+zvppr/pZJ6HWuq5/xiwaxL3b+f5jONi3O KI7A79R5EL70fo+4/VB7R8H0i4s3cLT1ARqX7vzowbP3NmM9xfObQGuHP401eArnVNuEQBNHJgoda ryvryliYWPLR6OW3vu0YnxN4oTGXG1dCcRuzP8NueCQAazLgtA0cGzBRiZGBPG4gE/7sIuzHYIs5L RdQRSd0TRg6g/Eoa5EnwnaGR2012DDDiofCgkpRGjY0x/xUmzuMiIOVskAi2SYwP5pPbwSi6YHafD R0T5tH5w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg1Ou-00000001PWi-0FUB; Mon, 19 Aug 2024 12:22:20 +0000 Received: from mail-dm6nam11on20607.outbound.protection.outlook.com ([2a01:111:f403:2415::607] helo=NAM11-DM6-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg1MF-00000001P61-05We for linux-arm-kernel@lists.infradead.org; Mon, 19 Aug 2024 12:19:36 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=S31CeETiwj0wVwbgp86kNeH0l/p/Bd+ru3vOM7BjtvNGvm/TlMH/uUEsLlt+te0AMNX/LMpAyRUotaKCHgG4vCOIEozUfgTdNSHgzUD6VfceK0xwwQg65EJWBYKld2MkV/7dYzJT6W868t2pqqzQx52wtChxAPXLZhSnozWSx+gw4lOaAE+DNJskqQqGVpXQ2kH0m+DrUg0yK/bqTkrI46uYT3yzFPRVCfMKrRWCzAt+c3MetkTKCdib5W3f0V1skoabo4kxLtAiEkdwe3D00tWpbMD1ddlMXDT3sOac0N+gUA77j8Whywz5jt9V2y+woPi1CsTW1xF1onhxvEDUPw== 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=PJfxMW0zjDw3au9LEf+PHQM/rUd+5+X4kZyP+vyKgqQ=; b=QbpGB9wUP+zRYiFOl3uMbt632O2K+gBvEMoscmjJdLjp2WEPDyniEik4foY1Dak1M/15Wk69cXQfmoSTfFf6w40ny48OHuW5D8ozLY7ddhMEVhL8nnyftc9mN9cTe3lE5WNahtH4qnlBrO5qlpjvTTdriBDkBSeGN6nEKgFpIpY9FQt5UlMehuhBAh5QQvMmJDcPE0vyHNY31/924FCSux3+/Ah4HbvWuAXYrhKIemFRO+9YCb9BTvwOCkrI1TUCKuzyeP30m2kHwAZgT7CoSThZRwVci5HMkqb78FViCZjXr5ym2vxV8+oLODd1k2Ui0LR8EquSm9ssrU1lWXFIsw== 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=PJfxMW0zjDw3au9LEf+PHQM/rUd+5+X4kZyP+vyKgqQ=; b=syzflwpOazbiZCAiGiRTVfnHgQ1NH/16OxWZC1uRy7aHfxXBGb4HmvjmapA9YnovfUVXGjf0v+SpNXV5u1JwigCOsbzgQoMb8jXJaVOG7ALoiy1L87/Kv20wEyClNT8BxNKG/xJbnVpcSaZCb8sLx+R0Id70vmKq0nVKwAUT9DjnyKYVNn1QnNy1N729L761XKiLVqG1zAlLx9qmpFHr4Ux93Zb+0WUKN9zQ+RSHqiWlMcqMJaheSOxr10Zax74t+84Yy337GaPsGOsuaYdTrem0/RBQrMLU5hz8aV6VWPoCGL931iqAhFAjwFXRq+6n5SEpvMbNA8zGL6RHGzSWbQ== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH3PR12MB7763.namprd12.prod.outlook.com (2603:10b6:610:145::10) by DM4PR12MB6566.namprd12.prod.outlook.com (2603:10b6:8:8d::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7875.21; Mon, 19 Aug 2024 12:19:27 +0000 Received: from CH3PR12MB7763.namprd12.prod.outlook.com ([fe80::8b63:dd80:c182:4ce8]) by CH3PR12MB7763.namprd12.prod.outlook.com ([fe80::8b63:dd80:c182:4ce8%3]) with mapi id 15.20.7875.019; Mon, 19 Aug 2024 12:19:27 +0000 Date: Mon, 19 Aug 2024 09:19:26 -0300 From: Jason Gunthorpe To: David Hildenbrand Cc: Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sean Christopherson , Oscar Salvador , Axel Rasmussen , linux-arm-kernel@lists.infradead.org, x86@kernel.org, Will Deacon , Gavin Shan , Paolo Bonzini , Zi Yan , Andrew Morton , Catalin Marinas , Ingo Molnar , Alistair Popple , Borislav Petkov , Thomas Gleixner , kvm@vger.kernel.org, Dave Hansen , Alex Williamson , Yan Zhao Subject: Re: [PATCH 06/19] mm/pagewalk: Check pfnmap early for folio_walk_start() Message-ID: <20240819121926.GG2032816@nvidia.com> References: <20240809160909.1023470-1-peterx@redhat.com> <20240809160909.1023470-7-peterx@redhat.com> <20240814130525.GH2032816@nvidia.com> <81080764-7c94-463f-80d3-e3b2968ddf5f@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: MN2PR15CA0038.namprd15.prod.outlook.com (2603:10b6:208:237::7) To CH3PR12MB7763.namprd12.prod.outlook.com (2603:10b6:610:145::10) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB7763:EE_|DM4PR12MB6566:EE_ X-MS-Office365-Filtering-Correlation-Id: f1ab3cf5-d2f7-41be-dea6-08dcc0492b47 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|7416014|366016; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?G48h6Hf2OSb0TMFFS9MgzsGYm0SnxxdGd0jR6bptKBq5QfQS3IYpAIhMKCKX?= =?us-ascii?Q?4VcPkqb8yaoTjmWaw5oEL11QCFmuCSEM2ZmdwDCOsZhKb80dUVdu2RNYj1Cr?= =?us-ascii?Q?F1+THopT3ak/CmEf+4qWytjmOibjnynpimmaUoNR7mUlvPA/YQbnHLDwrVYP?= =?us-ascii?Q?O12qRjEcIbBuck2ZZ8TwWH9DQmrSqHuayJxBSMau3riA2V5M5nXGYDLbKtH8?= =?us-ascii?Q?gROXuw5ZV4gDSVmYS/QJHBZZDAnJJSNcFrVgJtafVJTPPLGN65EdBgoH9A2P?= =?us-ascii?Q?CxFy/JPNjS+dX35O8mm5y0fbX7d1gGcQ1bjk8PlziINd1es9h0fzuPxuFDze?= =?us-ascii?Q?RHoHv6/7+zA0BrpbfRWx2bhcJr6eIuPhmCnNFS+a7jEszlDZdlazObMvyw9D?= =?us-ascii?Q?J6GSwy9UsrI+HvEgCE0fZPd4zGEiwYEBhut43tHPmCShyNqh0zCxW2/GHyhO?= =?us-ascii?Q?WFuxlHoMLSyl6SMYfWREmOpImpZsif0RO5wiVzSltDoWAU6QQklcIeJFtrjv?= =?us-ascii?Q?tpAwKnhXbUvAqZmS/4p3OY3SjEjKcYx2HPgPgqKhdaW4pT9EnSRTgd10SdYL?= =?us-ascii?Q?11h6ZLJCWJ79LykY/Y355Hi6qgjoFMl4YB1Q9HGDnikge2uVaaUIyvvhYLg4?= =?us-ascii?Q?sNLySAReSye9a9eIK6NmwV4NZlavtln3Mmyr3226aMhOsvEdRS9kxdm2PKwB?= =?us-ascii?Q?kk5HpILO5+9qfAwsRz+il3w7E2ub3p/fMBRMHW8ywhXJid/ifEaZyQViDqWg?= =?us-ascii?Q?s58jCezl8MO46nIiddbf8QIHIK9pWE+xfhjTKO6nJrAZoGiA8PRQ5ybPA6ZG?= =?us-ascii?Q?spCPlm2uiM7vUEtP00KIiAsa8jGDPCo3jRv+p2OKktawI3Kpwlsk3HKz3d5O?= =?us-ascii?Q?/y6qGOVWbn3n45Mm2RZp6q6MGygb6KpMl1msh5hjt3UGq8IgCoARuwKynZ1L?= =?us-ascii?Q?X6d3vjM6engAGKIBhgtEbX941vDeUDwBb0/3q5gY7LFaeAr8BzQ3zsxXHcOJ?= =?us-ascii?Q?GFew3chmOm16AIaLIifxXMzjmpzcOEH9wKEF4Rh6RVABPcH8dXKcmiMswNqW?= =?us-ascii?Q?CJntw6LFE8x9+94/Zkr1jqGgej6po7/pgNGK2eDlOqrLie8BWHFBoxWxUfXd?= =?us-ascii?Q?aO9cmjMDZuiIZYqs9mZDo1m73MtycpA9w83pEhJWKlhUAKjYr9GDw069WsAZ?= =?us-ascii?Q?vg532/UbjiJOkh26WyU0DUFm5D0vMSzXBO5uIR58M1XRny4LQNDkGQi5UuSc?= =?us-ascii?Q?w0wEhHT8o0oVmMC1VwVPB4IYyFNf71fhwkWaOqYbl/Bui3fv4FJt0lozg4vb?= =?us-ascii?Q?U+hqdj3mz7jqUmU8U4Y5GtuJntvJkvCGLig/RQfeRKXegw=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR12MB7763.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(1800799024)(7416014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?BmVlZECIuBqiuKQOuuznqWiEkr31P3LYCiKLfgvu+krV3z3UlfcoHnDRhPiQ?= =?us-ascii?Q?bgpbXUr6CZnNV6UeuSrQCRFx00vgZy3sZL2h0u9ScApFZyjplu/NYh8VfbSP?= =?us-ascii?Q?ts0u/iU7xEMkuLWNMUMDk/dP7Z6fq9D6nTDMgYH9+1KgzDC72x0Nh4w2lzar?= =?us-ascii?Q?2XlI8VrrHMnOfvmJ9Dyssr11zkbu7QhpFEQC6/TJpbbf5peFGN/gPn8tBw12?= =?us-ascii?Q?qeR5adAs6lh/8TL1je9cFx1UW4PGYEi7xbj25JhLje+JFCu3+sY7TKyRfhGb?= =?us-ascii?Q?+5pIe7G+0yZ9rXMWwlME8ok3Bn0vqQbPJP8ukzVjz+imG2SVSEZ8nEINE+ME?= =?us-ascii?Q?QG6NZFK0ANnQRCtEnGuGSlES6wpB65G23zcXlwmbOx+AudM1Rzt8kRYgvc20?= =?us-ascii?Q?JJpD8dhBzQKDeq81YiC/Omu1+IbbJ8tSKyFyIaeMmaqdLfPIPkqtCp/HRtjV?= =?us-ascii?Q?pRcTGLwIvxo+2vZMDOltxgvMdaiMYdCPCuCDiYUHO6Lv8PdoGYdqQAbIraF7?= =?us-ascii?Q?TK5pKyG0XJZ0yVKEWS6baZTzTKPJFwidxBVQviCHIjb8Ic5o+Riz0d6yefhW?= =?us-ascii?Q?/pHgDPlsp3Bg008YcQadA56pdN8wfOx6iNMVO8LI6HTJOkeVlJRXmzrNPFL/?= =?us-ascii?Q?5+dz2LnUdZlqLPfYAK5kqxqPjONF1Hhp8qfjCEwZ4pd89QDZ/5T0m/lIa0bK?= =?us-ascii?Q?MYrWs3q+a53bFwTmsZnqgt+2/Z5grtf8cCrez9AR4EH1GBbF/21zf2MxAj6f?= =?us-ascii?Q?rf0gJ2YFYFuGOArtuVXWeHxdQV2ftV2upeC6CF8f62J3iQiWXFjOZqvqrP9f?= =?us-ascii?Q?FM7xzJO65gbTw5U4HrFuY29QJLX8QjquGVU5lE076KEL/xgxdMc16Jzs03PH?= =?us-ascii?Q?V+v+UuoAAZ5HnZkN7F4AEwd5oiQXmPI5aDlMuEbQ0Ln8YKAgn/sYFHLm6Ar1?= =?us-ascii?Q?dpXruYQ3/DfhjOEfVSdgtzQn/jiwIom2TqPfj7abDJ2NeIicw33JHSSPjOAD?= =?us-ascii?Q?mmkDMbYg6AbS4otJHWyftflmE3pltfoNCQthUkO9KnL86b+bEf78tvVvRT1k?= =?us-ascii?Q?gYMo2Psxq03VNmPX/4HKATpzDhh3Isrc7vYQABkR09soxNsMS+fUkYfKhdLW?= =?us-ascii?Q?V90lcMms9jyAcdM/468MOgAaN/RVYbSyv2/Kn1FTyzkJa0jDQ6OhtrAz6rAm?= =?us-ascii?Q?Y+kN+7lmWBk8nqIsUwaWKflrHmYI8eDpUbIQutXXLTaO2/RLdKuQcFRso1H/?= =?us-ascii?Q?hYtL7uAsPyML6N+BGhV46yxAraovSvYvPt9/Vmas7t/u1BMZsv/pWkUHjcrG?= =?us-ascii?Q?7KdraoAaT+jajbYaNmebadw1Wmu0TEc4ABVJvmOkgrz69ihF/WtDr3tAK+S9?= =?us-ascii?Q?TZGO+DrtBvM3FOBQCoNt+RXiJI15lzzQlSovPQzFYKvkc4yTthsBuj5pGsX6?= =?us-ascii?Q?PvtscUUKTceuGge7y4/fz5hK6rGhBfAgMz6OONIfPQHmlG3Ke34eawCxk/la?= =?us-ascii?Q?3fHNTT6MFLe1rNT03gzpJfw6vKq3jIdrff9MnDkPE0RMqKgDvXDxLg2JK17G?= =?us-ascii?Q?qLO0y5kTpUoe5BFJbZ/17uSDZAyU1BYM/fjrp87y?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f1ab3cf5-d2f7-41be-dea6-08dcc0492b47 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB7763.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Aug 2024 12:19:27.2687 (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: KcTMWaponkF7OcqKeyMdei5uhfE/K2+Bi9OxFJtjDU51YIBDQLbm12ek/QOQoTw4 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6566 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240819_051935_106820_848CA477 X-CRM114-Status: GOOD ( 11.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 16, 2024 at 07:56:30PM +0200, David Hildenbrand wrote: > I think KVM does something nasty: if it something with a "struct page", and > it's not PageReserved, it would take a reference (if I get > kvm_pfn_to_refcounted_page()) independent if it's a "normal" or "not normal" > page -- it essentially ignores the vm_normal_page() information in the page > tables ... Oh that's nasty. Nothing should be upgrading the output of the follow functions to refcounted. That's what GUP is for. And PFNMAP pages, even if they have struct pages for some reason, should *NEVER* be refcounted because they are in a PFNMAP VMA. That is completely against the whole point :\ If they could be safely refcounted then it would be a MIXEDMAP. Jason