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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8093BCA0FE7 for ; Mon, 25 Aug 2025 16:03:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ADD058E0049; Mon, 25 Aug 2025 12:03:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A8DE38E0038; Mon, 25 Aug 2025 12:03:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 907F78E0049; Mon, 25 Aug 2025 12:03:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E000C8E0038 for ; Mon, 25 Aug 2025 12:03:14 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id A6DBF14043C for ; Mon, 25 Aug 2025 16:03:14 +0000 (UTC) X-FDA: 83815749108.01.B57C23A Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by imf13.hostedemail.com (Postfix) with ESMTP id 336412000A for ; Mon, 25 Aug 2025 16:03:11 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b="onb/x+8o"; dkim=fail ("body hash did not verify") header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=pQ6ucEVO; spf=pass (imf13.hostedemail.com: domain of harry.yoo@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=harry.yoo@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1756137791; 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=yvL6M5j4mPen5RcKYMs+Q3Sw0xLty6CObCpwStUhw50=; b=sMEznPcEuPG73IkG0lbL8jbIoFaP6c1hB1IXV74ADHgE7QlQaxouEHSyUOU5i23YrWAUFR /z5fa3KjIn3c/QEJgIn/P9JnBgPDc8FcSsLMq9XXzWOKUNarWyfgh764ZxBo4GpK+3eqRG pkEv2ts1DaaZd53IbE7YAXdQKVTZr5A= ARC-Authentication-Results: i=2; imf13.hostedemail.com; dkim=pass header.d=oracle.com header.s=corp-2025-04-25 header.b="onb/x+8o"; dkim=fail ("body hash did not verify") header.d=oracle.onmicrosoft.com header.s=selector2-oracle-onmicrosoft-com header.b=pQ6ucEVO; spf=pass (imf13.hostedemail.com: domain of harry.yoo@oracle.com designates 205.220.177.32 as permitted sender) smtp.mailfrom=harry.yoo@oracle.com; dmarc=pass (policy=reject) header.from=oracle.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1756137791; a=rsa-sha256; cv=fail; b=Bp85S9gfYGaPkkuX4xeuSqGAAmKNu2WXs/kg5ukAYrMVFC2jjP+aKW9Eirx2vhQXd11/Fh hCjh8qRSaRvWdSxYapcVguHHZvw3oJxUsJP9aIB2bq9ZUUM4NqzMG3L/3uoM/bF2vpNsoo GzF8joJq4aeOGstJjLXEaiVECUICnpY= 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 57PFfv3p012690; Mon, 25 Aug 2025 16:02:41 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s= corp-2025-04-25; bh=yvL6M5j4mPen5RcKYMs+Q3Sw0xLty6CObCpwStUhw50=; b= onb/x+8oISGenpJKYECkyvmqQIXhhN4CyFvXx3yMQWe9bmEoLLRa4fx1UBMqusMV bSVcWxxCZal3DPYN0+G0BYArbW6j6CeyLecIX/noYhYtky/8QMSBFZq99zIu80g1 GOscaCSo6oOD7E0EqTf2VudVQVxpOH0ngGTOPmGah8IUURtYpM23YOnuxE3Gndzk D+3kFCKTw0z0bz42yQOaYzewete1ZydsPsVvjHsYFS4ixM/LukO6IaSVjzGvoc6s 58cVUX29BVyvTX7LYwBBKuK9+Ny4CHYL2aI0L7qAynKJRFpoumPIGh5hxj4oExL3 2aj5aD9dYPkuZ2N+SOthSQ== Received: from iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta01.appoci.oracle.com [130.35.100.223]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 48q4e22n84-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 25 Aug 2025 16:02:41 +0000 (GMT) Received: from pps.filterd (iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 57PFBSan005028; Mon, 25 Aug 2025 16:02:40 GMT Received: from nam10-bn7-obe.outbound.protection.outlook.com (mail-bn7nam10on2067.outbound.protection.outlook.com [40.107.92.67]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 48qj88ne74-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 25 Aug 2025 16:02:40 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=BXpPP23nfrz50NxWbGGPPbSjVAIXbyaR+S4pRCd9gUMJ7asbFYZ6BUlqZNk0fF7Zj3IjcxS5F9xyrjswUCXvykakaC8LU2hnvoweNsIb6ox9ewk1J2l3dCs0P9gQCjia1BipBnRNutbZLBEDRJqM5vnTxKJl0PBho/9cXNMCeKrm7GOdjykdZJybF5kRSG6x5SSDkkP3HH0eUNBhfTEz5e4aSW8IJW8aQlKdEWLbET0G685bslbQlX5IZRj8X3dJFdzCx5eOy3TMD9b7bDjF4AlZmhb6RA8+C139BuoNVHZgA9WhL4RdlvT0Da13uM01LyN9s/Mhx+APbTLy4sf5zg== 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=5rM7zJBqy7JZfT5ozsR6vQZpIBSGhID3PDQQw+swsaw=; b=RJxD77NtcPDXBAlLjqSGAa8/cCq9D6tqKG8HKXiKYaAcI/kijIwxIXiE6VGzhcZGFZMrLLhompYeHhpyLbj8EAp6NrdqNqGGkeucZX/Pg5XkAxBTg8yqw7jMV2StiqI+KCFrf5Cm4BhLLNKlVR9L5rh0IvrisanCXRM2cIFNgdb1bQCZZKLwSJBtpcdQmWhHqPqjgCMIluywraEGRWaQS9cKZBwgMUpuzrZTWE2C5f2WB1pCC+v+k+ODP80wHFRV53dQAmQpGg20EOJwnek/b4VRQs4sTbxcZ92rWV76WhVD5H4STM+MSxdAKtK8spFCLQ0SyCM7d1d1/XnbOm2RBg== 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=5rM7zJBqy7JZfT5ozsR6vQZpIBSGhID3PDQQw+swsaw=; b=pQ6ucEVOPoYqljp+q2cOVP5UdhWwzEgrbF25vKjSRM3WPQieU9hZmhDv/s7IVMXtFcyZRpVDdZF11a7H8//tEaxmPL1H/Xlud2Ic3gQQyDfewXjvnOGO9VbvZCMiOzwfVjrQBwszqS7D7ndszujcaYpunRvvUXQU/l+cHuHtKYM= Received: from CH3PR10MB7329.namprd10.prod.outlook.com (2603:10b6:610:12c::16) by SJ0PR10MB4607.namprd10.prod.outlook.com (2603:10b6:a03:2dc::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9052.21; Mon, 25 Aug 2025 16:02:37 +0000 Received: from CH3PR10MB7329.namprd10.prod.outlook.com ([fe80::f238:6143:104c:da23]) by CH3PR10MB7329.namprd10.prod.outlook.com ([fe80::f238:6143:104c:da23%7]) with mapi id 15.20.9052.019; Mon, 25 Aug 2025 16:02:36 +0000 Date: Tue, 26 Aug 2025 01:02:18 +0900 From: Harry Yoo To: Christophe Leroy Cc: Dennis Zhou , Andrew Morton , Andrey Ryabinin , x86@kernel.org, Borislav Petkov , Peter Zijlstra , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Tejun Heo , Uladzislau Rezki , Dave Hansen , Christoph Lameter , David Hildenbrand , Andrey Konovalov , Vincenzo Frascino , "H. Peter Anvin" , kasan-dev@googlegroups.com, Mike Rapoport , Ard Biesheuvel , linux-kernel@vger.kernel.org, Dmitry Vyukov , Alexander Potapenko , Vlastimil Babka , Suren Baghdasaryan , Thomas Huth , John Hubbard , Lorenzo Stoakes , Michal Hocko , "Liam R. Howlett" , linux-mm@kvack.org, "Kirill A. Shutemov" , Oscar Salvador , Jane Chu , Gwan-gyeong Mun , "Aneesh Kumar K . V" , Joerg Roedel , Alistair Popple , Joao Martins , linux-arch@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH V4 mm-hotfixes 2/3] mm: introduce and use {pgd,p4d}_populate_kernel() Message-ID: References: <20250811053420.10721-1-harry.yoo@oracle.com> <20250811053420.10721-3-harry.yoo@oracle.com> <26796993-5a17-487e-a32e-d9f7577216c3@csgroup.eu> Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <26796993-5a17-487e-a32e-d9f7577216c3@csgroup.eu> X-ClientProxiedBy: SEWP216CA0016.KORP216.PROD.OUTLOOK.COM (2603:1096:101:2b6::10) To CH3PR10MB7329.namprd10.prod.outlook.com (2603:10b6:610:12c::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR10MB7329:EE_|SJ0PR10MB4607:EE_ X-MS-Office365-Filtering-Correlation-Id: 9a9c0387-7e1c-4aa0-c4a8-08dde3f0ceaa X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?iso-8859-1?Q?4slTHjk9SvjaYPkCsX5PB90gVyOaa33YVza7tQlUKi6i2tnLDHgauaNbUU?= =?iso-8859-1?Q?cS2bMrt+gO16IYP5r9IqkV7M4KYiF2escMItoMldUrVEKFU2EEnTpVgwrk?= =?iso-8859-1?Q?tUpZ9WH9v2OGp471gM33aLEHWsKyYZAvhfb6zDPbLvnqgRX5tU0Zj6MLKK?= =?iso-8859-1?Q?I59ROElCNt4pIbZSWq+z5af8Y/PvFxwFU9EDHqzTK3qtZP5jMxTAHw+lLo?= =?iso-8859-1?Q?HYtoZYPIVdYlLrcM7ysktbz65FgKk11JqmLDqLXVnu8ljnZLMfQ0T3gRMt?= =?iso-8859-1?Q?mVqOVYJyKxAN2dsWZCC6iCy3jhYZ6zXEc5dhuygNoDVEnrdHpFh1oh9Mt9?= =?iso-8859-1?Q?hvrc0FNZrkIeTzNberwXEjS7YTfXDtHroLHetGPecOE3FZd5dO+CmNDG7Y?= =?iso-8859-1?Q?PmKVaXHxDSDQX33Vgq65SJz3DV6vUJpewni0ZJG7Zy235qvaEu+W+RTc1Y?= =?iso-8859-1?Q?1NI39HoyNEe150xrzmm7WBXwhpKEqyt3Jh1fidLwNrpy3LmCSmxrGfyP8W?= =?iso-8859-1?Q?8U9VLZTnAm3NG5lzFGLe6KqcDqpGuwiRFMNyroYa7MACIuJ81Yckkq00bm?= =?iso-8859-1?Q?vwKELpgewk3oqYORKKO74RTt4xJAQSjPqGwBIiV7Gz/3eeRrv/cfCaW4om?= =?iso-8859-1?Q?R10J1zGajGnQw771Uh3GaJxxC1sLoxNK9FdDCt5J0Y+/smBn8eH7GWSNRj?= =?iso-8859-1?Q?eU3r5JtfEjqev0/hYYYVGIeJIobxeANoaMFxVvD8Rxl4plCWSZ3GeY/xF/?= =?iso-8859-1?Q?LNGhD5jvdnhdyV3YieNB1mBu3lFce85vR2OqKeCvd5bgcwBvBEWU3uojzO?= =?iso-8859-1?Q?ZnrGaGXLKcF6be6Ed6xaacN2JEro2ag2p4wp3kjxAlBnOjr75cgu5IXcGO?= =?iso-8859-1?Q?u95tEgN7i2LxgP43AghYxnbqfc8FUH0wXqK07crhUQYRB5n5OVf6hC2stu?= =?iso-8859-1?Q?60tuPoSUomEwpOBNkO5J1iAJFwMNshli2fwngDeEb39RyXPC7idAObofFh?= =?iso-8859-1?Q?7GgeumpHRi8G9t5X0cCocEf6XLgxH6bfBGTGUkVFMUjsPDZOLSWZkntJMs?= =?iso-8859-1?Q?komXwc+ggGEdjy6V/2xefobarIpeT+N1QyARsKCh0j4F0c/cMIprnYqDX6?= =?iso-8859-1?Q?zcNRqttURz9YiXi6CExmSp/YJU6C2kn4AQ6YWRiyfXdeH0d9wGkS/ei3F2?= =?iso-8859-1?Q?IEn+m+xwf/CGIbENXk9N4uiL2rtpbtyC5whiK+D/lRJc/jMNu2OA7cNjCB?= =?iso-8859-1?Q?T1frHBOrok4NFOU8yapmkjqRwWFNZ2RZdwjh1YGRr7srwIDcXAyIDuoLho?= =?iso-8859-1?Q?NWWlKz4SG0ZNi9qIdBxDymSXv3jXXFOCl91o7ViM9Z2OMLlz15QmEhpf1i?= =?iso-8859-1?Q?/WsswW0DRRARWErjXbu1VAkDiZusQOnnSAqfuaitYaGWxXAAeiw/ewCPS/?= =?iso-8859-1?Q?cG9M+S8fKrhCyd80beWtJrEusZPJRkS6ABFMbQ=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR10MB7329.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(366016)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?hsymHHMkUVI/W6MC/qQj3I4JXW7qEH5IXncZSkZaB2E+LKPGG4Tf7RohNH?= =?iso-8859-1?Q?8hF22qjxQp5P6tsVWssvuXqhE30O45DsBu3SRA7n2ewlnz2Gb0Yec6ZPUJ?= =?iso-8859-1?Q?f9rrA3riLpGF8u0PGR+E5HfTav0ZHZvG9chbo8YP1GkuZFZumNfRotFOXn?= =?iso-8859-1?Q?JgPFCrXBRQNPL5cZikKuVurvUwBwIAxDQaxq9EMBzJuG5xj9vEK+80XV8Q?= =?iso-8859-1?Q?GjjDzemSIJ4TBNoOtcrH7GHAoQ6xTj/3n8qm3DHbU7te76cRSJHUtutMSV?= =?iso-8859-1?Q?UvTqLXZe6pAnhoH5sFPGZnFU0HuDuEwPvRced9U0urW1T+lE7bryS6SdJk?= =?iso-8859-1?Q?lzQX2U0njUkve6V7Zlj1YdBY+KiPMSKVPlJPEeDsY5i5X19E5uA7/fhQ8S?= =?iso-8859-1?Q?5O2USadx+4+8+ZWvoW1MX7dhb4ySaE/Fc2v+MOZwJm59+IDUhlQ8felaNi?= =?iso-8859-1?Q?a4lDSBfp8g7KzCJnvJBMbuISs5FBFsFOQbvgwwImWvNi9vu4Y0Bm6qx6LH?= =?iso-8859-1?Q?Imd2zDsM22+AxkgvedfpncHrTDDtDGKrhQRIICsp3uWnPWgTERY+3qM53p?= =?iso-8859-1?Q?AMZMLRAQwgZHyjOAvTEIfrwUIPvRKfSLpa6qC2QMZcHHByYFg0wVZq9gGU?= =?iso-8859-1?Q?3oZSLF76uP/GSMQGDf24EtDdMuorNQ+4Vi6FVKVe0xTNzuv2IO5O7xUmVC?= =?iso-8859-1?Q?unqrzydsrJTrxmNodcHFFoNWgNkwtHvbkm7mk8Zl+CYgWMum7rLh5xMett?= =?iso-8859-1?Q?psD0dujPHO6GXs3mk7BoPtv80X9C/evYeV1MaDbfIZ2n+cQI01WZYBKyhO?= =?iso-8859-1?Q?1sjHBQ4FH6XRJr6VZ3uFWjjqy4+0RvTfmw/ukCQbYLByiapYsCUnHJg6u2?= =?iso-8859-1?Q?2O6lehCCH96WBeTy+ygoNBVeLeszXfvP1/ro6dhgDIYrSd1qZIb9nux80y?= =?iso-8859-1?Q?6qDGY+d2cdbi7yVE/vFae/gAmTYdXy85lN2mQyDxw5EWYYaqXto6MxMn29?= =?iso-8859-1?Q?i8RorrKPFYXww/tB6CmJpKFcq8NfgVP5B09jK4P5GUlJ8S0+ouBSyXMXUN?= =?iso-8859-1?Q?vYnuZGGDEH1JWqBfdmuH+8/wUaChIB2H+sQR7l630oT9vbptSZ3Rj18kqB?= =?iso-8859-1?Q?iOxlhcvik2obtCCZr0F8leZk6KJHryjoTTBh6255sUs4kGRw0Vo+lIBJBb?= =?iso-8859-1?Q?1gQM6zJTikEFAhmP69jPOOsYyajwlYi0rSQ2eo1jsVzia1w7mankryCYPQ?= =?iso-8859-1?Q?+qjVuPEOBNJxkzG7RsVWycKlpb8XGoenOkfeJ5NV0eInptmPffS1cL/Sog?= =?iso-8859-1?Q?HPovCWMyoI5E2jff3bY9PKBPWTIDKRg/vZKIiglgCtNwsKBbazC17vkdF2?= =?iso-8859-1?Q?cUI1Y6bSnmZG1NCAOiPZ0v9Vm+LQGCIq4OuAZrF5lPd4w+5pQnVBJyHBdF?= =?iso-8859-1?Q?O0t+JB7d4U+cbvok6CF3XOPjL+fyiMUW9A67TmT5n90+2nrqt2qkHNJLVy?= =?iso-8859-1?Q?fZqPiQFG1lrWzG/OvmylsS1AmMh8ju3uzF54cV1Tbgp8haAOz67FA95rWq?= =?iso-8859-1?Q?uIIiNfxhUJykOkWYIAHCo87LxWwfNpjx/bjURLp3AhaNQRbNJF0AVYtoOU?= =?iso-8859-1?Q?/P++0vkCY0WHAS1BoNx5Dre3Ju5dyfqe6T?= 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: 9a9c0387-7e1c-4aa0-c4a8-08dde3f0ceaa X-MS-Exchange-CrossTenant-AuthSource: CH3PR10MB7329.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Aug 2025 16:02:35.9474 (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: psWQrwHhFkvmYmZ6scIsUGr+sxALQ4w2Vg2pD3amgYPEyDtoX+q2zFS6+/svAHIoUcRckvCILgTvh1htPJpIAA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR10MB4607 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-25_07,2025-08-20_03,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 suspectscore=0 spamscore=0 phishscore=0 bulkscore=0 mlxscore=0 mlxlogscore=999 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2508110000 definitions=main-2508250144 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAxNyBTYWx0ZWRfX6pR0U+2O/SOQ mQY9tgh14sjBKCqmzGUzXLOXW0p0LJFK45dbtAMTFHZvmq8NFl0bwXEvX3bu4TeELXCazYvu5Qj epVbf/5t3WAbYvjANQrGKx8qSjb1LzRbeu7P+j9tYu1BPqA3eGlYaAKKTGmQ7dhxHuA/XpBj1Hj iqhECk6QQfpMUqxcckUXtf4tGBDdi4MPXDfhsV5aujEQjZznekyUThWxgd162HbIZXjZUu35aJe MmDy8jxPt9qCy5IUthhDVpEgf4KGCR4ADe0WHK2/atJ4SpCKUJ1xOraYOn1g0cUUzp4yBkoylrH 2sOyvyR2PGCDPzaJQpbnGU6Tl+xf71G1i69d8wFuSpj1O1VGeem23g1Egb9YBsQ9I952dbFmeTG BwH+eg/xq89shu55EkDXNm/NbpZuhg== X-Proofpoint-ORIG-GUID: dm-hYueEENp1RGfnegDKRoGjRSpae4Nu X-Proofpoint-GUID: dm-hYueEENp1RGfnegDKRoGjRSpae4Nu X-Authority-Analysis: v=2.4 cv=IauHWXqa c=1 sm=1 tr=0 ts=68ac8921 b=1 cx=c_pps a=zPCbziy225d3KhSqZt3L1A==:117 a=zPCbziy225d3KhSqZt3L1A==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=8nJEP1OIZ-IA:10 a=2OwXVqhp2XgA:10 a=GoEa3M9JfhUA:10 a=VwQbUJbxAAAA:8 a=cI9SBmEsuJOggFUlpjAA:9 a=3ZKOabzyN94A:10 a=wPNLvfGTeEIA:10 cc=ntf awl=host:12069 X-Rspamd-Queue-Id: 336412000A X-Rspam-User: X-Stat-Signature: a7wbqhq4s7spftsjw83chk8dkwqi356t X-Rspamd-Server: rspam09 X-HE-Tag: 1756137791-439264 X-HE-Meta: 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 Bn2Jxf6k 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 Ljtwkbyw RvU+XVM4bHIoeLacwu+Wk743cMYEfCA40rwzCTjV9n2iJnIRXxKpZRRbRbaN5e0fEf4S76cnNl7AIBvZIBtlnmm6cQHokDmh 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 Mon, Aug 25, 2025 at 01:27:20PM +0200, Christophe Leroy wrote: > > > Le 11/08/2025 à 07:34, Harry Yoo a écrit : > > Introduce and use {pgd,p4d}_populate_kernel() in core MM code when > > populating PGD and P4D entries for the kernel address space. > > These helpers ensure proper synchronization of page tables when > > updating the kernel portion of top-level page tables. > > > > Until now, the kernel has relied on each architecture to handle > > synchronization of top-level page tables in an ad-hoc manner. > > For example, see commit 9b861528a801 ("x86-64, mem: Update all PGDs for > > direct mapping and vmemmap mapping changes"). > > > > However, this approach has proven fragile for following reasons: > > > > 1) It is easy to forget to perform the necessary page table > > synchronization when introducing new changes. > > For instance, commit 4917f55b4ef9 ("mm/sparse-vmemmap: improve memory > > savings for compound devmaps") overlooked the need to synchronize > > page tables for the vmemmap area. > > > > 2) It is also easy to overlook that the vmemmap and direct mapping areas > > must not be accessed before explicit page table synchronization. > > For example, commit 8d400913c231 ("x86/vmemmap: handle unpopulated > > sub-pmd ranges")) caused crashes by accessing the vmemmap area > > before calling sync_global_pgds(). > > > > To address this, as suggested by Dave Hansen, introduce _kernel() variants > > of the page table population helpers, which invoke architecture-specific > > hooks to properly synchronize page tables. These are introduced in a new > > header file, include/linux/pgalloc.h, so they can be called from common code. > > > > They reuse existing infrastructure for vmalloc and ioremap. > > Synchronization requirements are determined by ARCH_PAGE_TABLE_SYNC_MASK, > > and the actual synchronization is performed by arch_sync_kernel_mappings(). > > > > This change currently targets only x86_64, so only PGD and P4D level > > helpers are introduced. In theory, PUD and PMD level helpers can be added > > later if needed by other architectures. > > AFAIK pmd_populate_kernel() already exist on all architectures, and I'm not > sure it does what you expect. Or am I missing something ? It does not do what I expect. Yes, if someone is going to introduce a PMD level helper, existing pmd_populate_kernel() should be renamed or removed. To be honest I'm not really sure why we need both pmd_populate() and pmd_populate_kernel(). It is introduced by historical commit 3a0b82c08a0e8668 ("adds simple support for atomically-mapped PTEs. On highmem systems this enables the allocation of the pagetables in highmem.") [1], but as there's no explanation or comment so I can only speculate. Key differences I recognize is 1) the type of the last parameter is pgtable_t (which can be either struct page * or pte_t * depending on architecture) in pmd_populate() and pte_t * in pmd_populate_kernel(), and 2) some architectures treat user and kernel page tables differently. Regarding 1), I think a reasonable experience is that pmd_populate() should take struct page * in some architectures because with CONFIG_HIGHPTE=y pte_t * might not be accessible, but kernel page tables are not allocated from highmem even with CONFIG_HIGHPTE=y so pmd_populate_kernel() can take pte_t *, and that can save a few instructions. And some architectures (that does not support HIGHPTE?) define pgtable_t as pte_t * to support sub-page page tables (Commit 2f569afd9ced ("CONFIG_HIGHPTE vs. sub-page page tables.")). Maybe things to clean up in the future: 1) Once CONFIG_HIGHPTE is completely dropped (is that ever going to happen?), pte_t * can be used instead of struct page *. 2) Convert users of pmd_populate_kernel() to use pmd_populate(). But some architectures treat user and kernel page tables differently and that will be handled in pmd_populate() (depending on (mm == &init_mm)) [1] https://web.git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=3a0b82c08a0e86683783c30d7fec9d1b06c2fe20 -- Cheers, Harry / Hyeonggon