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 3E890C369AB for ; Fri, 18 Apr 2025 13:26:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 10520280156; Fri, 18 Apr 2025 09:26:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0B988280150; Fri, 18 Apr 2025 09:26:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DF92B280156; Fri, 18 Apr 2025 09:26:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C08A1280150 for ; Fri, 18 Apr 2025 09:26:07 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id C8D88B8F4E for ; Fri, 18 Apr 2025 13:26:07 +0000 (UTC) X-FDA: 83347237974.08.A9695F0 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2060.outbound.protection.outlook.com [40.107.243.60]) by imf28.hostedemail.com (Postfix) with ESMTP id 358A9C000B for ; Fri, 18 Apr 2025 13:26:03 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=SOPjvhe3; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf28.hostedemail.com: domain of ziy@nvidia.com designates 40.107.243.60 as permitted sender) smtp.mailfrom=ziy@nvidia.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1744982765; a=rsa-sha256; cv=pass; b=gxx5g1WjSMxI7nU2jZPa5Sz4uOvjEL0uZP+Uvbp5gTfUDXcWFToPnbDRB3D3eGvwprWCou pi5OzKKB4rSrszzNR2FSws6FxyXPIzUthIsj0meCmpiDHEfFrYVO327hkLCDtdjnJvHx62 TvTwJyWhiKvcjpsqbgjzU7Room6sjjY= ARC-Authentication-Results: i=2; imf28.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=SOPjvhe3; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf28.hostedemail.com: domain of ziy@nvidia.com designates 40.107.243.60 as permitted sender) smtp.mailfrom=ziy@nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744982765; 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=t3CimwwkIJeU2tZQ+SVZ433RhInvaW1T4xtHGftFMjs=; b=5R33O6VK+7SvRtMF18evhARKeZEbu2QlCKOVOobzQYAPwbXj5nDcyOMH2xaDCuhPL48rWt MSCqx58o5RoBdSXKOtY0cWSN1bAy/nUBrkLVGGwcGyiky4mgrKPGqPwxTfEzwiE6SzrPyt tdL6gmzgbNA53lCP2xj5ivwS32acWfc= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=nC8U+wcGEgqjpv9ptnbeyTXqXIdVGEEtMcX/e6kENLhekCX2aPDZahkxeHRPzvmhfblYCsAItBxXUxRGDxGoRXhI+si7q7wm2+yrxEQ+ROlNuF/Yfxcdc5WVwVeWYsGuvmqfyqUGRWvQ1fnjcH5p+b5ZOWUHyBbjlBzjiZDW/S99nnav5VK890Auo2aqlXpoXZ21NgYOgO1NkuSl4ia/qaactc/lQ7U2nKChDnxTHfbNDxexqRrwwLxxqP/veOEqTle3+2nmL98uaDp+0Tysi3JIHggWSU7eQQ/AT/JGb9O+QguZ+zhzAWILyNDZY/sMA2UyNW5MV5FrZ3fa1CSh5w== 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=t3CimwwkIJeU2tZQ+SVZ433RhInvaW1T4xtHGftFMjs=; b=pGJtIa+AB1vW0S6o+uTO56S1sROParFAh0lM8cZaH6HdxCP0jnQZLcN8PkWW/F8bHfM5vNMiOncXpQApB3geItqbRTCgGv1KQMdm9HcRfuSqp619XxQAhp5ctKOS5GNhuQstd2f9oWO966keTkpNWCFP7IZ5YTDoF0DkKiF0NP4yJHC4AJ9nMed7WGWorzI4t0hbyNhreyVp5m3vK2AsJo+Ur4/rg45ayxM38Z//I+XiDkzxN4/sVbFEadi59oSURxB6gJsdBXkI6JPGGUUWv2EPqtKRi7p3yXEDLYx424Wn+nBnVV24mI3PWoDpIDT4sDoIDdXIyAf8IGGwp7cBxA== 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=t3CimwwkIJeU2tZQ+SVZ433RhInvaW1T4xtHGftFMjs=; b=SOPjvhe3u4eugQ1pBemIcvn3eSM0b2rR10Y8KbWnvbsks9jdsLE/vSHbT1sqO80RXdDGVBlG3Asi/0F9vLa/jdTorHpF+x+GfgmKqFNdtn6aFH3FF1fdf9uk0MWBrrm5h4ZgrOSQYLOE8LsCnthJfG60dvmb922Py39zO2L88P8/H6IFM+MlevTIWQClj+T6gITFDCvXJmDzAorCPcPAHD8IAwg8Bkf+qBGzuZOsNvludi2YTEtbbhcxX+tuErql7WYk07h2bGnka4Wce6umn3uDSZsvxVzaBXNe2jy/PNzJuitHng6LK8FeEgAs7LZ65Fj55iYWflGF5fbxvdm3qg== Received: from DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) by PH7PR12MB7260.namprd12.prod.outlook.com (2603:10b6:510:208::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8632.30; Fri, 18 Apr 2025 13:26:00 +0000 Received: from DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a]) by DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a%5]) with mapi id 15.20.8632.040; Fri, 18 Apr 2025 13:25:59 +0000 From: Zi Yan To: Hugh Dickins Cc: Gavin Guo , linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, linmiaohe@huawei.com, revest@google.com, david@redhat.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, Naoya Horiguchi Subject: Re: [PATCH] mm/huge_memory: fix dereferencing invalid pmd migration entry Date: Fri, 18 Apr 2025 09:25:57 -0400 X-Mailer: MailMate (2.0r6245) Message-ID: <537D4547-383D-4AAF-9F9F-8A37B0BCB7BD@nvidia.com> In-Reply-To: <95e543dd-6b93-9507-d383-1ae91e2e6640@google.com> References: <20250414072737.1698513-1-gavinguo@igalia.com> <83629774-981b-44cb-a106-d549f1a43db9@igalia.com> <95e543dd-6b93-9507-d383-1ae91e2e6640@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: BL1PR13CA0121.namprd13.prod.outlook.com (2603:10b6:208:2bb::6) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|PH7PR12MB7260:EE_ X-MS-Office365-Filtering-Correlation-Id: d0c0a3bd-c6a2-486f-e0c6-08dd7e7c8f17 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?OGtwYVNoY1pWeHNkTmZGRWlGM2MybE1oeG1DTUpJS1ppRER0OHlXREE3blhs?= =?utf-8?B?b1VuLzMrc1N6cTRaUFd2U3g3MmVRejNZOVZ0b28rVWFDRzk2SG1lUDlXMjll?= =?utf-8?B?QWtOR0JnamZDMVo4dWtNUEZ1WWJDdGE2dFZ5RmNnZnJ1ZHRrNjVZRXJmSGcz?= =?utf-8?B?Z0hDbkcvR3pxZzhOdnEwd3pIYW9Dc2xwRG93R0NqUGpJdXhhZlY4WnhwMGd1?= =?utf-8?B?ZlhMR21TWjBrd0drTmRmWVpMM2h3ZUMwUmU3Y2RhUURxbGNPT0E3ZFQyNXNT?= =?utf-8?B?VS9xYk11Y3orOUI4dmhFTWxRcnR0dHdUMmsxVmdwcWVLWFZndnFYVXVFMWtK?= =?utf-8?B?YUZSSy9ySmptdVo1LzM4K0FVRmZqdDZRRHM5aEw1MndIalA0M05DRnNOQk9N?= =?utf-8?B?VW1rNDltSmRNRkdBZndYQ0ZSRmhCZzZWZWhRM1liZzFKenBmSFgzSmc5OVQ3?= =?utf-8?B?ZndPdFR0aVhsNUY3SFpGVzJGTC9xUXVmcm1TRXF1VEtLci9kYXJlam5uQ0xn?= =?utf-8?B?STJibG11SG5sWUFkWk81T2xQZ1RVYjcrdmtDTTM0NHlQKzErcWJKZm92anBC?= =?utf-8?B?Z3NLQjlpK3Ird0YyUldXWGU1Ri9nSllhTXBqUk1nSi9ENTcxbC92a28vRlRD?= =?utf-8?B?ZGYwTmhLMlMvQ1lNNTRxZ1V6TDhmc2RVdGs4d3gzdGZQTDBNdzJyOFI4ZVBm?= =?utf-8?B?a0JjbGoxNDJhREVRbFRnRmliSmNYZU0vVkR6VVNtdWlOUmg2U3c1NlBrSG1V?= =?utf-8?B?NmFCTUd6SmZUVWRvdmR2TzdBMnJoUzFscmxIQzBOVmtoVnIzMFQwakxhM25k?= =?utf-8?B?Q25WVnhDaU9BWnhOSkc4TG5nY0NpR21MSHNrcy90MFhkbzBkN2w2QVZieC8y?= =?utf-8?B?VEZYOXAwV3o1bGZKMjRkY0RMZlRZSEx5VFQ4aXRrUXFvK0V5S2EvVEVPcWVP?= =?utf-8?B?a0l3Skg5ZVJBOFNhTXVhU2J3dWJqR05sUitUS0JtTEtXZS83VzVmUFJKR3VT?= =?utf-8?B?MER4UnNqbzM5NlhoREdoOExRUEdIamNKWEVZWXNRY0dFS01mZ1l3ekIveHdy?= =?utf-8?B?aG1ZbEpFVnRhbzd3VUQvSzI4dURMUCswVmpyZ3RhTW5tdVFlc1ovVENaR3RL?= =?utf-8?B?ZmVhWURYL3NCcEhsVkk1OFhtc2l0cUp0aEZPbnJXRk5vUVBCQlgrV1pZQ3N6?= =?utf-8?B?dW9uMmNJRW5vYWtKMUtpNXN0SWZRUVRjTTVVbGhsK2thMllTNE9tZ1BiVlND?= =?utf-8?B?U1kzaTNmYXFsaWhCbVg0TXRHOVU2cVZJTWMwc3RzbmZ6cnpKQmNCUUdpRFE3?= =?utf-8?B?ZDgzRFExbGpkU1o4aGNPVGtUV2N4VDUvdnpQSVg1UW1rNW03T3JlNDRjYnpq?= =?utf-8?B?WUo5U2hoVE05K0lmMWpnTXI3cXR0ZTNNNDloWW1Ka0dOSmdDNGpxb1YrYWVB?= =?utf-8?B?NCt2cE4vQ2tIS3RpVFNqQ3dLTUFEcko5TUF6eDFPZjExd3FDZTc1ZmdjNFpj?= =?utf-8?B?d29wK21yWmMvNGNnWWVhdDREZXgya2poUW96Q0V6WjFnTWpmRlM4dDArKzFN?= =?utf-8?B?bmRUQlpXemJSMnVySTM2QVRyWitVNmVRdk5KdzFuQzlFRWdUaTA4WklvVXdz?= =?utf-8?B?ckVraUFqRk1zS21TVUI0TmcrUGdMOUMvNzF4Q2wxdFVuMWdIa1hjbEFINWlM?= =?utf-8?B?aHdHck1Td0NvbVFYWWI1SFZkU1B2ZGZ6dUhrblkzMUJmbnFNUTlRenRHUEtT?= =?utf-8?B?dk9QM0FPMDZsMk1neGV2S0RVQjhmSEY5UmEvZDQ3SDhxczFIMEg0SU9GTXlY?= =?utf-8?B?NENmSUxiZDVmOTFnb1pWY2V6dGFPNTZzcE9wVnorYkV0Zzd1U2dRZGNMZWFH?= =?utf-8?B?TndpWDdONGRNMFZiZmNJZWcyc3F6YlduSlFVdWJHUnNtbG1XYlFGRFhNMXg3?= =?utf-8?Q?lZy94ib7SP8=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR12MB9473.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(1800799024)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?NkNxazVtUDRaVkNBS1RmaDNDQjk4ZDJXSVdKdWduTm9IYm9RSmRoWHQyeVQy?= =?utf-8?B?ejdjNG9VY3lRY2tIK24wMmdGSU10Zk5JSGNyR2RpNVZLZXJvZVVuckc2Y2Nn?= =?utf-8?B?LzNCT1ZydmZnWHNFSTUvTjFxWm41WXgxRzJJbE16b1ZBdkxINDd2U2lzOHNU?= =?utf-8?B?ajJIWWw2SVlMTHNHZFVPTXN5c2J2L3ViZ3RNZFZZWWhERjh3YjZUTUZkVlgr?= =?utf-8?B?bTJkWUF2NmUxMlQ4N0JJUGlla000U3hDYmNIbFUwUy9Ib3EzS0crM0dnZWtO?= =?utf-8?B?UnlHblFLWnYxdG5YNXQ2cXJJbWlsajB2WXhIVFhkQmxkV216RXR6RUZkZ012?= =?utf-8?B?Tm5vMlNHbFF4dExISVZkOUlDVUMxU2tST2pnOE85Z1o4dk5HYytRVmNvekRj?= =?utf-8?B?TVM5bU9zOGZhRUZyV2dZZEVBZFFTNW9iUVYzMWJRdmRVSWVoSnhHVVdLUDJs?= =?utf-8?B?Q2pMVngxNi9GQlJ3YTh0TklERERHYjhTYWlYVitoWTQ4b1M0OTdGWGVVSkJP?= =?utf-8?B?YU1xREIzdzdsT3Y3K2JlbzYvMVArMVMzM0ZBdFdGVFRpbzBwKzJXVFJVZkhz?= =?utf-8?B?bTU2WnBrZVdQWjZvb0lyeHVvMXVhTHAzN01qRTIxNGlBSjE0UU0zbHJhNmVC?= =?utf-8?B?c2EyNEN2dWRDcXlXanRmWGZzY3g3S3RtK0d0QzFvTVZ2eW1UT2YzcERkMEN4?= =?utf-8?B?RDd1WERNOFBYOHU1Z1plT2tubFp1WWsvR1ZBa0l1MEJDTG9OSk5zTm9PMU0r?= =?utf-8?B?K2o3Szd4eXFYcnhDZGlJOXQ4YzJ5N0Z2cGdjZXhyazM2N3ZRdSt1a0NmdTJr?= =?utf-8?B?VVVkYzNKWnB0Q05vaEJ2eW1WYkVkaFRWNTVtSmE0ZkpEdEhsc0pqYUthTHZw?= =?utf-8?B?NThURjlvRG9SN0dEak1jbyt1aFBuOXlRUTVYK2srMzFZY2E2U3ZTTGU4YmFp?= =?utf-8?B?ZFJSdEhMTXc1WThCNU1Oc3BYOHZvTTdYMTJ2QWJNd2RBcFJMdXJISThrSXd3?= =?utf-8?B?bTdqN2EzcXhCaG9sQSs5T0ludkVpUTJtak9kNXJUdzlVYjZCYXV1eVJMY24x?= =?utf-8?B?TUtraGdjemp1bEpkWStLWHFSbnVQeWxzdmVIK2ZQbGF3ck5mdVFUc2tZcjZh?= =?utf-8?B?SjIyUFRKYlVxR2lxMzFxVzl4M1FGTEd4VFlvTUU1R0hHOVVhSUQzbnpxNmdE?= =?utf-8?B?Rk9RQTBjUUl0YkQvQ1d2TWlIOHVzdEpxc2xrSWhYejJiVFZ4azBHeUVVRlBE?= =?utf-8?B?WlZKTkVnN0lDYWttb3ZHMzFMdzJLSk9oUFBlcWhPNnA5UlVjVlpLaWJOTjgr?= =?utf-8?B?SDNrdzIyK3grVWFSMWhQMHpKZVk1L0htNmJpclRDeDJudVpRUk1zTGNKb2dp?= =?utf-8?B?THN2Y0kwczJKcGQwRmlQeEh4czFpdWhJMy8rV0grNERFNUxlM1FWbGR3eTYx?= =?utf-8?B?YTFqdzRNN25VY3hPUFFyemp1WlNKZW9TYjZqdUh0MmY3Z2lBT1VUMllOQnFn?= =?utf-8?B?WFZzUkxCSHM0WnFyejlrVGNiYXh5dEpaQlhUbnpPQ3NqeThFSysycWlBcGM2?= =?utf-8?B?MGhrN2x5b1l3dFdod1orTVRuNnJ6Vy9SVGtBYUFqbEFzMmJ3d0ZkeTBOaWFk?= =?utf-8?B?N2tFK2ZFTmNwWmhIakRaWGMwdmpBWElSZHREVnZMMWpHZ01JLytxYWdPZFNq?= =?utf-8?B?VWVXRDhZZWtlWG5zKzlrVzJ1YnZiT1U5b0puV0pUbUtuUzRQR3BnK3NLb2RR?= =?utf-8?B?YU9rL2RBRVd1SndpNmcrV0JmZ1hEOTBWS2NaZ3BaSjdnSUxsN0g0aUxvN1VF?= =?utf-8?B?ZWk3c0FvM0gzQ2RGaWtlMndHdlFUOVJ0blIrMEhNWVh0d2YwcXRmeG52UURz?= =?utf-8?B?aTlJek1CSk8rU1B6UnNpcWQ4czVaUkNrd25LNGdWOGg5RFdYYnkxc1A4UzJS?= =?utf-8?B?dUtWS09mMUtTUnZHQzhQL2JDcy9VK0dVN2dsdUpUU3lzbzh3NXpHN01xRDJZ?= =?utf-8?B?SG9Gc0cxa3hYUUg5TW1SNmM1RlhyL3U5R0hxOFVlbEQvZ2tUSTNOcE42ZCsz?= =?utf-8?B?ZDlpclhmUHhXWHdFWGRYMUJNYW9KZTdMS25KeHFnWXRHZFdwM2E1MEt5TThi?= =?utf-8?Q?aF8Q/HUwyPRFyZAsz6e9eDXj5?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d0c0a3bd-c6a2-486f-e0c6-08dd7e7c8f17 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Apr 2025 13:25:59.9201 (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: ZKln49V3Blld6rM7yhgCzfA6qEs3J7M1RFo2ZfrLvYIxmi43fHWVyuSLCpgcJxXy X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7260 X-Rspamd-Queue-Id: 358A9C000B X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: zemsyoromrqm34yfmkukht7zbbiiu9g7 X-HE-Tag: 1744982763-188805 X-HE-Meta: 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 bmuAYuKE H1mmDSRp9e+mZqiDJbZm/FYF8i0cQiqzKecZdcI2Dv94iHnfiHuVgJwqZ0mkq6pVu5mLbBFUK82E//wd8MDCdDX8Bw7ItzAK7x494mbV8pvjU5hGyFbDjJypqlet/mndjRGtSgm2v0kw0eI9mP1eJLKvFI0EYkr1S0y5aIYxXK7dQJo6deJQW/hgLJIJm1R7gepCZvIKR/5o4Nl+xyqM8OPlMHRQgftvb1NfzEK7gfm4I6ovq6vCl0v4s2AGLiV2r+herTykf8To4DstDCASk0UHdD1uv/VecvYTZ33tMyWZG/FW+bRClDvl6Yo274Kd9+Mny49WD/QdEK8m1SOWACuBV7JHhxiJYgfUXUeTQKKCV5YG+0j0VbDWfxm1tbF2zwCSshyEGsL80kVwXpaTxJVjV6O+tR1EX9tMhInxNR4MO0oNMN+8OXmY3mBq4gi9lELPT 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 17 Apr 2025, at 1:29, Hugh Dickins wrote: > On Tue, 15 Apr 2025, Zi Yan wrote: >> >> Anyway, we need to figure out why both THP migration and deferred_split_scan() >> hold the THP lock first, which sounds impossible to me. Or some other execution >> interleaving is happening. > > I think perhaps you're missing that an anon_vma lookup points to a > location which may contain the folio of interest, but might instead > contain another folio: and weeding out those other folios is precisely > what the "folio != pmd_folio((*pmd)" check (and the "risk of replacing > the wrong folio" comment a few lines above it) is for. Yes, from Gavin’s commit log, I thought both migration and deferred split are working on the same folio. But after reread it along with your explanation, now I understand that both are working on the same pmd migration entry. Thank you for the explanation. > > The "BUG: unable to handle page fault" comes about because that other > folio might actually be being migrated at this time, so we encounter > a PMD migration entry instead of a valid PMD entry. But if it's the > folio we're looking for, our folio lock excludes a racing migration, > so it would never be a PMD migration entry for our folio. > > Hugh Best Regards, Yan, Zi