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 BCA44D60074 for ; Tue, 19 Nov 2024 07:49:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 18A476B007B; Tue, 19 Nov 2024 02:49:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 139F56B0082; Tue, 19 Nov 2024 02:49:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ECE7B6B0083; Tue, 19 Nov 2024 02:49:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CC51F6B007B for ; Tue, 19 Nov 2024 02:49:17 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 42DCA16020C for ; Tue, 19 Nov 2024 07:49:17 +0000 (UTC) X-FDA: 82802067222.25.042C7FB Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf22.hostedemail.com (Postfix) with ESMTP id B27B6C000B for ; Tue, 19 Nov 2024 07:48:11 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2023-11-20 header.b=oHAdNjBO; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=FxbAfmAM; spf=pass (imf22.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=oracle.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1732002373; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CaqqWmdVxKg7WtDfynfVPRVp+ko55te/B0usUUNc7LI=; b=q7vUkWyEI+EpLsi0e3D7cB/YKmVYjCU8AziWIdLOEm867nvgFStNG8cPN4DKxDBSFe0E/8 K6/MsOY/0QSzEdO1pFLzPpH9bAODIQTE5USDn1Y79udzSPANpiiKBulTgKkyOGD9RR1Jje FjikY7oVml2zpRTw4j2NTr1RZwXLfOU= ARC-Authentication-Results: i=2; imf22.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2023-11-20 header.b=oHAdNjBO; dkim=pass header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=FxbAfmAM; spf=pass (imf22.hostedemail.com: domain of lorenzo.stoakes@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=lorenzo.stoakes@oracle.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=oracle.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1732002373; a=rsa-sha256; cv=pass; b=h39D8rLmlRgk2mfasZJiDssfX2oSCNkuk4mABLnUX4T7fN8Hv7DLSdwir7nVbVu3+KmQtL C3UnlyVCEzz/EzVWmkkIfIG7OuO956DmDdvwjYm1vHWCoHnnxoqZ8sFcJVts4kcUhHC1gK Rx+H1wjDy4YxrooR/MMRXbk2O1KQXFg= Received: from pps.filterd (m0246631.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 4AJ7fvgo028589; Tue, 19 Nov 2024 07:48:52 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=corp-2023-11-20; bh=CaqqWmdVxKg7WtDfyn fVPRVp+ko55te/B0usUUNc7LI=; b=oHAdNjBOMX6Podjrg28T7U0xIkCjPFFhfI s2TCWLKhSi01qA1ntSDqS//Xej3SEYnyHCLUY+FMO1g93wJjsVxUkA0NRim+eOvl Qj2MPJW5NuLLCFPWN5k2RRtAsgBwaRzzgulpnN90QKi2hY6YxiCOFR4I2qdV3wkl ycPuOLUV8Uoma2csodaip5vC3i060QHpwlm/JAeoERiOWc9preWqMkQT63QRG8bS W1RJt7NNW4hbFEaRSm1p03idEbjHSUN0hJQLc6n6ruKx46Bh0osnnzqUMxL72XDH dbm+OmUHMIGOlIIT+qpzOsIBHxAg/CvuZIbDZjJ3UvJhRj+Zr/1w== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 42ynyr2tck-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 19 Nov 2024 07:48:52 +0000 (GMT) Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 4AJ6sCA2008655; Tue, 19 Nov 2024 07:48:52 GMT Received: from nam11-dm6-obe.outbound.protection.outlook.com (mail-dm6nam11lp2172.outbound.protection.outlook.com [104.47.57.172]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 42xhu85t2y-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 19 Nov 2024 07:48:51 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=xWtgU+m/6yu0pq03ztzMe7WvukASBSlOP+40bzimHPVOi+mOsjme97KSpa3BEY/WBdWAlPsC1sjWi8k7cKzKYyUt1GxP1iZR/8sHv+uFirF3/9/jt+xcsmlICbweM9gjo+P8tbSk18dXEB9aozKhmvHCTXM1LZPrAtUd45IaTOx6hX1TA35io8Lq332xaAmlN9WAkcAnivsCAPKnOKIriLUzQGWrfdV8xSEQMmqFi/gKgVGtg1ZCmBqwoTPyvfyQ3Zy0IjDegszTx8ExXAFFSJTtM4hYePyO5uJQzU/J6k5OlffkcS4eBnU7jIj3fWNIRh90c45CTayKe9PTML+fOQ== 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=CaqqWmdVxKg7WtDfynfVPRVp+ko55te/B0usUUNc7LI=; b=CS3v6p0Js/x6up4ekdl4BbP0yg/Za9eWdunOhjCJpKiB50dzwUy4OcMgbkmKQZ34wVOyIL/pSauW0Isr8u0lf+NG3snSXlIJjnkApSfm5k36EWElhSjvo7sqGCN4sQrVJOhf3VO6qn29u5i98kMuY7puoyHwhYc1jGtpEa9zEZwrl2/Jc0sOiK+YYT4RZ2CkbkJs6BQxJTKNlLM39ETbOJuijUcFQ4g9ng48oN/ChurMTj+YYrmcUN5IpjLF2GsXsy4UTlab+JtGxvVlKu7G5PlL9wUhelFhJKG/TVKB1BiRidZKI2wr0TojixVl0BFN8TVUH3rzrjpwYiSKzD9+bw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=CaqqWmdVxKg7WtDfynfVPRVp+ko55te/B0usUUNc7LI=; b=FxbAfmAMkTOnfCHewaZP83GAZKSUgA/OxiLc5VJACcZ0GpG6ddxrZT/kMXr9HKc0RcwdXCqstYhfbXRfmKwlHwmL1WNl3nyMg/8mdS+ERPpWRnZI8uinN/63hfUDzVcZbiqcGSBdupVV69D1Q+zF36HIWB0+ItSa4X5hLDw4Y+8= Received: from BYAPR10MB3366.namprd10.prod.outlook.com (2603:10b6:a03:14f::25) by DS0PR10MB8030.namprd10.prod.outlook.com (2603:10b6:8:1f7::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8158.22; Tue, 19 Nov 2024 07:48:49 +0000 Received: from BYAPR10MB3366.namprd10.prod.outlook.com ([fe80::baf2:dff1:d471:1c9]) by BYAPR10MB3366.namprd10.prod.outlook.com ([fe80::baf2:dff1:d471:1c9%7]) with mapi id 15.20.8158.023; Tue, 19 Nov 2024 07:48:49 +0000 Date: Tue, 19 Nov 2024 07:48:42 +0000 From: Lorenzo Stoakes To: Qi Zheng Cc: Jann Horn , Andrew Morton , Jonathan Corbet , "Liam R . Howlett" , Vlastimil Babka , Alice Ryhl , Boqun Feng , Matthew Wilcox , Mike Rapoport , Suren Baghdasaryan , Hillf Danton , SeongJae Park , Bagas Sanjaya , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Matteo Rizzo Subject: Re: [PATCH v2] docs/mm: add more warnings around page table access Message-ID: References: <20241118-vma-docs-addition1-onv3-v2-1-c9d5395b72ee@google.com> <21195425-53d9-4007-a020-8106f94158dc@bytedance.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <21195425-53d9-4007-a020-8106f94158dc@bytedance.com> X-ClientProxiedBy: LO4P265CA0286.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:38f::13) To BYAPR10MB3366.namprd10.prod.outlook.com (2603:10b6:a03:14f::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BYAPR10MB3366:EE_|DS0PR10MB8030:EE_ X-MS-Office365-Filtering-Correlation-Id: f1614707-5b51-4407-40cb-08dd086e9ab5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?K4IiB8IxONxB0fHvxrUqKYXPnyD/awT4B74k5SH4yboQgC7sqZ6gRL8ioc4R?= =?us-ascii?Q?oZGzbNuBJVRaorEz6fZgD1c0KaI5NAzsQt83cSeJk7rjIOrD4rFoYzR6A9he?= =?us-ascii?Q?9jEJbzs1LpCaz5F0wvSOxabrVdpyM3N4vPsHVb4l45IOA71YwTfS0YrjboMg?= =?us-ascii?Q?OP1POOhiUaUIyuOhhulyMzyCsifaySIvdMCjQCOgCHD8bme4PRhg6nukOYw8?= =?us-ascii?Q?CAEdOh2pa6X8OBt+ntInfmWp/mdvKstGZmlAg+9PVgZbSo8jb7ANY2pfXSv9?= =?us-ascii?Q?5yesxpynWL2mQCaTD4cBOmBXesvwYDrMTexOjlm86XJmuxuD/H/22aozFU44?= =?us-ascii?Q?vpnWIazT7m2d0QrnQymCZpvveCM+QSlSy9upa5UMfs5VWIxd6KzxJJT8Gyq7?= =?us-ascii?Q?HYZERlAdME9TTHkvOxzDxpIcqZLubmY3ok//4Fv7fb/hFj/1+TZfsV3+yQ7X?= =?us-ascii?Q?14wL9QjL0nV9jox2FUhg7orFzmmvXZYMKHOn1SK31jC39PXYCCtfawPPiAXS?= =?us-ascii?Q?dR9q7GLowBnwRVGzqxluEFXeQvD08UvlnfyBGgdy5HxOQPc6TnwvVGinVJqF?= =?us-ascii?Q?QTomUgGNkO3D2GH03cUMdnA/a1wrViPpLrbmRJqOs4DeOI2mmYhvNTP300oo?= =?us-ascii?Q?onvWhfb3qT8Cy/oHU44Il33TXofv4mLl9boKj8GqxhWsJN6qLrHQGke3nsBt?= =?us-ascii?Q?SJpjcyH8s8RFOKJX9dYtxMcEcVoJa8AyfSpnw4vq2YjvdjUUdz08wS7OmYBy?= =?us-ascii?Q?sOWWe8SlnvlC5ymxFh3smCTPqDH2Tqki9ZICeYa+02xtyiglrBiYY9EaqB05?= =?us-ascii?Q?YQ8vBZRBVaZMCW/r0arIcm0spqZvWJm1+NDZY2wI8FQgzzCD+5n5XR5NzMBN?= =?us-ascii?Q?1Qfmxs9EnPbGiwvKNwgvgNEGrgW4ESZy42a2KZd14uSq0Od+fCVaOG4w9t3H?= =?us-ascii?Q?Y3m3KbUGtm/5JTrAdzdVdKQveaodGyCpprO+CkJYjMwC3wPku6CmdeEqmwo1?= =?us-ascii?Q?V2s+sUjDuyt9kbB7428DAJzObc7zaLmLt4jMhL9eblVoBS5afUySSSqnJez/?= =?us-ascii?Q?QxC/v9OHuWCGIX/R/N87nsTN9rdluYASg65y+GPiWwY7KO4hXJJVXDqa3vUi?= =?us-ascii?Q?9OZGM8qimrncOQQZD0C5qst8a9NO9v7so3SxH/TsaWMfJL7xYE+DCPtyVwCk?= =?us-ascii?Q?B2DHsnRyh1z47BVvCqeEncIxefbAg5uFiknbPd1/Q7Gxllt8WKp6sfkVIZa3?= =?us-ascii?Q?pTjYDorlyA/iomKDXqfRytWVojPJGMG/O41B824y+zegNxnDm/bjTsEpdw75?= =?us-ascii?Q?lMW4LKkYGfKbNx3w8CJ/55z+?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR10MB3366.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(7416014)(376014)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?nwqx0ebAKdsf2hdFO1ql4SgIVTdk5MrOBfHLLlWCe2MC6mB0LgfFI5VupP3N?= =?us-ascii?Q?1NonJsiIp6DOtmXqfXQPNEYCBCkXAktsG6bnXjPh384HjeMJYjWj3rdqyoAc?= =?us-ascii?Q?N5f5lk5TqENT+OH9VONOIhfZwo7/jfoHB+Suw5u+l5vPLM3G8QRWIWWaasXY?= =?us-ascii?Q?aM8iL4+v8tSCBSdGd+1aP5taymF2OlxhAT3hPlc9T0XB88BGwbcL4ui2fFHw?= =?us-ascii?Q?X2iP6vEGc+GeXExcmpHxAh9oX6HDi9a0ru7XFvtDjzBu/cRcEBO9e7ErTeIU?= =?us-ascii?Q?xeIKovHh9ofP/McRsMuQI18NnO3biRYTJbcaw7MDd4f3uAGhoX6+oBCwhsIN?= =?us-ascii?Q?mh2n1w9z1+1TZ9JgFU7KYRro4bl4PUiEQ+iAud0n9JfJptFeruIpyVYGzQI6?= =?us-ascii?Q?9iEqYoLHwHfmRKOvXfyfVnVTWweijc66ka1sKbayzkGOmAZuK1qOvdRX42gy?= =?us-ascii?Q?p6+nZ+/enOhKu5ROPJISFi8dVec36ZiP37rJxCLKTGYky3S543ytoXSq7zcd?= =?us-ascii?Q?2u/mzb8/Bqmoqmq47BcUAVYMp7shU69GeN86ZxgR0Z3BiYqaJnETCosggudN?= =?us-ascii?Q?wvoexzd635RIeU5sQfgd0BvhOnXw3O8VXeuZqd5pbJlFAZIdH5Ozp+1Yq3F/?= =?us-ascii?Q?9584eQ4pyCIplsTnwh0zcIgjLCA9mqQ+Z8aBq16IaioH7kVOzTxOwP1v4ucX?= =?us-ascii?Q?yKqAN8MZEnERJG1SRQOIRqzB9zeq+WIzpQ2STJt2E263o96NUoob2Navsp9g?= =?us-ascii?Q?ypUmy9kQg7oGfsFi9xKV2OlZKxhVm88epRJO8Hgqz7PGR203WZI2cPhg4zPh?= =?us-ascii?Q?sFS2lFLnadVKxAiXlcV1y0eZoGpN2fDI46oFU97SomhNx+GnQXSeWtNSIVSM?= =?us-ascii?Q?obYL3Tx2fYtlUPlpqKuyAf3Djy/BI6rlHYCc0WsZxu4Q6xW4gekcFTl2Fokk?= =?us-ascii?Q?5Wkjtx7A9QbDDhXH6zMaAAkRlZX1xqK/ayZr+au9AqholjPv6aFYgayndN9C?= =?us-ascii?Q?OuZ2W/c2U35zYnLwlkk+xRgqJhJeFXj80cT9wx47d+zUaYpdLoTP6KdpAJte?= =?us-ascii?Q?TTen05tyJvPOqyVZlDUpzE50yF4jmcpLChh4yOw7KUqzoDbWNU5kSMp0t3Gd?= =?us-ascii?Q?9QlrLlVi5Cu4Du8AiD+yrlOub1t1Tw0SbtYkZB+rwLY9ouWq5qS6kynU6Hep?= =?us-ascii?Q?fRsIpbY1A72QF2pKIJchuofRpwNxzbcDyOsbG4219a4RHBPBnnMEEkEHhnjs?= =?us-ascii?Q?Gl2V3L7cOSr4BJq799CQaAjgq8mFrdFIS/BCaZrk1M0MJiOn+MdBN0t00IHi?= =?us-ascii?Q?xmP2Mqk/Kyj/pgidLeySojLLadg4mbxvtqB6mfMn+BKYvT0rdih0CcxeUeU9?= =?us-ascii?Q?HjQmcS4yvrnOi5w8E8TMdhYrfc8NnOxSghiJ5rcKyIO2Efbk1NvUaHJjAgpe?= =?us-ascii?Q?crRBk/ZN8v4uukRAzP6GMoBA3CmLm/zprRZJ1MT9pKWvqkFwvDyPyMdRr8Dc?= =?us-ascii?Q?19gZkt6pZL0ax/5JcN25XBKwmzb2fuhX59XNqfFPRMO4UHSzD2qIU0W4thT0?= =?us-ascii?Q?vUivicV0gf0ym7O1A6poUyA9Wh8IJkO+ihAO2dxl/EQkS/YX2OKR8N7mhlYG?= =?us-ascii?Q?xw=3D=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: f1614707-5b51-4407-40cb-08dd086e9ab5 X-MS-Exchange-CrossTenant-AuthSource: BYAPR10MB3366.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Nov 2024 07:48:49.2564 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: KFcdo/If0CVuVjMAPwIafa/nOVaxvRDDiN6qL8C4p2XnD1+i4c1mmJgEey22txeBJtUI3DxHR7HZ4JF+3j4tYwGnnRwOIjNvNNvvMUIjmr8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR10MB8030 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-11-18_17,2024-11-18_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 mlxscore=0 adultscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2409260000 definitions=main-2411190055 X-Proofpoint-ORIG-GUID: -J1rLP5ULl2P32M3h9-xryn3E05XYjjW X-Proofpoint-GUID: -J1rLP5ULl2P32M3h9-xryn3E05XYjjW X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B27B6C000B X-Stat-Signature: ouo58xyemtyxambhkth73zjpjg5wd9js X-Rspam-User: X-HE-Tag: 1732002491-694924 X-HE-Meta: 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 MSZd8pYX 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 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 Tue, Nov 19, 2024 at 02:53:52PM +0800, Qi Zheng wrote: > > > On 2024/11/19 00:47, Jann Horn wrote: > > Make it clearer that holding the mmap lock in read mode is not enough > > to traverse page tables, and that just having a stable VMA is not enough > > to read PTEs. > > > > Suggested-by: Matteo Rizzo > > Suggested-by: Lorenzo Stoakes > > Signed-off-by: Jann Horn > > Acked-by: Qi Zheng > > > + > > +* On 32-bit architectures, they may be in high memory (meaning they need to be > > + mapped into kernel memory to be accessible). > > +* When empty, they can be unlinked and RCU-freed while holding an mmap lock or > > + rmap lock for reading in combination with the PTE and PMD page table locks. > > + In particular, this happens in :c:func:`!retract_page_tables` when handling > > + :c:macro:`!MADV_COLLAPSE`. > > + So accessing PTE-level page tables requires at least holding an RCU read lock; > > + but that only suffices for readers that can tolerate racing with concurrent > > + page table updates such that an empty PTE is observed (in a page table that > > + has actually already been detached and marked for RCU freeing) while another > > + new page table has been installed in the same location and filled with > > + entries. Writers normally need to take the PTE lock and revalidate that the > > + PMD entry still refers to the same PTE-level page table. > > + > > In practice, this also happens in the retract_page_tables(). Maybe can > add a note about this after my patch[1] is merged. ;) > > [1]. https://lore.kernel.org/lkml/e5b321ffc3ebfcc46e53830e917ad246f7d2825f.1731566457.git.zhengqi.arch@bytedance.com/ You could even queue the doc change up there? :>) I think one really nice thing with having docs in-tree like this is when we change things that alter the doc's accuracy we can queue them up with the patch so the doc always stays in sync. I feel you may have accidentally self-volunteered there ;) > > Thanks! > > >