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 B1292C04FFE for ; Wed, 8 May 2024 16:35:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 48B6D6B0085; Wed, 8 May 2024 12:35:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 43B256B0089; Wed, 8 May 2024 12:35:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B4756B0092; Wed, 8 May 2024 12:35:35 -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 0F4386B0085 for ; Wed, 8 May 2024 12:35:35 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id BC655161132 for ; Wed, 8 May 2024 16:35:34 +0000 (UTC) X-FDA: 82095779388.17.9035518 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (mail-dm6nam11on2071.outbound.protection.outlook.com [40.107.223.71]) by imf10.hostedemail.com (Postfix) with ESMTP id 0B366C0019 for ; Wed, 8 May 2024 16:35:31 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=edUvFpIN; spf=pass (imf10.hostedemail.com: domain of jgg@nvidia.com designates 40.107.223.71 as permitted sender) smtp.mailfrom=jgg@nvidia.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1715186132; 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=iIOAqdn5/eCZjR/YyjURHb1YnHHaGuqdkU26A2nLwik=; b=Hf0dBdIL1vcEQlk53XlO03rksYRewC+P0RpPSOFr9xH2cUNxkPmzbl/v0uQWlY0g4x3IQp FwbfFvmBi8v9SRprhl9RfLNkJQzCqpwh2HRQ6nYmehb4zWpA77Qgf1vxw89QrX8LFgHuVa XZWNtu7KfBwAstnu2qqhz9I3f/LvWEY= ARC-Authentication-Results: i=2; imf10.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=edUvFpIN; spf=pass (imf10.hostedemail.com: domain of jgg@nvidia.com designates 40.107.223.71 as permitted sender) smtp.mailfrom=jgg@nvidia.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1715186132; a=rsa-sha256; cv=pass; b=KVCvztvVnGzXxVDHN3ioNk8agU2jtKb4TkloHBysorRaYDCvR7POdppGPErMl8yaJdtkbi L2uyXwIDJcHWcEZf+hwpQXiQ/oUK39tO5DIcVfs3m4hKCeDD2e6cAetR8Y+aOIrulpAWr9 jVNhJMFrtJSJFQo0Ul0nWiUmSfSpgQ0= ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=lRp6L3HNqT0GBl1nmMOsNt6Uux+Y3vK+0crjzx+4BMVAESDSLidXuCX6qJl6vsPkGwSh0BSC6lcQoFBJMLI05U9gGQf8m1vPMCzsUkUlEWALb59NwKTuEYb9+z1TmfKhcxG8NUaWVczy0MH1j+0S+r473KiYwtx4/3jCNS+mxEhYPUjvOfi7ZxWk+OWgiCUtwFhV8CO0oLPKmtMrAHk8nQk79AtqbFHZVbeANno0cNfh7rggMZBlKb1qi3N6cTwwY18GWiJudRg16PUYYJuMJQOvwJW22pLn5JtCvhd+mFBGob2LjjHTIyood+gHbzAMJAkg6a4zGZCJGAqHtcRCKg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=iIOAqdn5/eCZjR/YyjURHb1YnHHaGuqdkU26A2nLwik=; b=JUDa7jQ2vppEUKVWY6qSeSWeGs0ZYV6CcQbpbEB7oaQFVAaBap/kVVN+W4+iR7iXN+IB1Ze8T1CvN0KFi2/1afyTr2Umq0GC8IPZ4hZ3ovsZ3qfz/8KgOAH3JLJJ+0iKo7MVJNSZKiLH2S279mlDaAopN/OiLjakIQEiwO8mqUaLLgJdm1UyNFPVtzUGm455eGOb4bDYSm+/nKfEv+J9fFELQuEif/v4GSVpkgYvUYTKp4mISeGaiNe2Pt1kknK497PhFbh7kVko0+ZTNFaAO3BHxAUvUdsSulboLFEE0/8x60gPuvV9ESj+iUs1chko0UofBzN6lvUDMWJsWf9/HQ== 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=iIOAqdn5/eCZjR/YyjURHb1YnHHaGuqdkU26A2nLwik=; b=edUvFpINF7CYXSVH7tjqQZTkzsJ3Se1aWjOT6xYACi+79egXsmTSLWm90TC59cilaT5gfLHjHKEbAaWWsk7anvT3Yq1zz+lkNr7br+0AS30lYAH3853SyTeNT1FYzlUQAp0d5cUM7WA6Jw16ig4Wc6hWxtAInEUf0KnxSiPeuWk5i/RM4Lw+ZPPhvLpu6WbnkKjYmx6f/LmobOhzI2p+afB5NPI9um1VAkp+7pZHqgVYLFdT1+TTs+P92ErTAXbyyHzCckGN1Cgpjbyqh9wUN7REXwiC5dZGyL9Z39ixAKOzPDt9Dws9LDE1Ar90ocy7Jhn+IIQI2tMqQgQIkfdDdA== Received: from DM6PR12MB3849.namprd12.prod.outlook.com (2603:10b6:5:1c7::26) by MN0PR12MB6368.namprd12.prod.outlook.com (2603:10b6:208:3d2::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7544.38; Wed, 8 May 2024 16:35:28 +0000 Received: from DM6PR12MB3849.namprd12.prod.outlook.com ([fe80::c296:774b:a5fc:965e]) by DM6PR12MB3849.namprd12.prod.outlook.com ([fe80::c296:774b:a5fc:965e%3]) with mapi id 15.20.7544.045; Wed, 8 May 2024 16:35:28 +0000 Date: Wed, 8 May 2024 13:35:26 -0300 From: Jason Gunthorpe To: Zi Yan Cc: Lance Yang , Alistair Popple , akpm@linux-foundation.org, willy@infradead.org, sj@kernel.org, maskray@google.com, ryan.roberts@arm.com, david@redhat.com, 21cnbao@gmail.com, mhocko@suse.com, fengwei.yin@intel.com, zokeefe@google.com, shy828301@gmail.com, xiehuan09@gmail.com, libang.li@antgroup.com, wangkefeng.wang@huawei.com, songmuchun@bytedance.com, peterx@redhat.com, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Baolin Wang Subject: Re: [PATCH v4 2/3] mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop Message-ID: <20240508163526.GM4650@nvidia.com> References: <20240501042700.83974-1-ioworker0@gmail.com> <20240501042700.83974-3-ioworker0@gmail.com> <0077A412-0AF1-4022-8F49-EE77AE601ECB@nvidia.com> <10BA9EED-A2BB-44C2-B80A-26527CDFFA50@nvidia.com> <1B2017A4-A252-4C1F-9608-D43ECEAD53B1@nvidia.com> <20240508155253.GK4650@nvidia.com> <30469615-2DDC-467E-A810-5EE8E1CFCB43@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <30469615-2DDC-467E-A810-5EE8E1CFCB43@nvidia.com> X-ClientProxiedBy: BL1P222CA0028.NAMP222.PROD.OUTLOOK.COM (2603:10b6:208:2c7::33) To DM6PR12MB3849.namprd12.prod.outlook.com (2603:10b6:5:1c7::26) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6PR12MB3849:EE_|MN0PR12MB6368:EE_ X-MS-Office365-Filtering-Correlation-Id: 0355b6ab-4452-4a1a-4af7-08dc6f7cde70 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230031|376005|366007|1800799015|7416005; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?mle/dKkbRKf9gbHl9veG9MiYi0hK/35lha/h28qkrULD/WX/0tbLfpexZriq?= =?us-ascii?Q?yobxK3ONyG5wTQmGeNVrUNiruDVhMCPGvtwXooKd+0oLBDFXhK8GbbgQMkLV?= =?us-ascii?Q?/qd0v2UK1fzC+C8EWt7jvkFNaraUy3wYBQN1U1onQzK2deUXTIKV6TqT6onl?= =?us-ascii?Q?O6eRkJmAzrH4pJa4WefZ54oAn/A4iZZjTPywCeCl76MXSmkcwj2JEz9u1pC4?= =?us-ascii?Q?qftsZ3iLdeYvhd5OjyNE66L3VK4tTeLJw4KWk07npM6FQV4lxQzjKT6s33HB?= =?us-ascii?Q?pFNj07IFyMHk0KmHSe4ftBMLdgroapR50KbNNPkiYvAiMjrHB62aiCSRkp1I?= =?us-ascii?Q?/Yax+4V3hvJNu5Sknc/U4430wkMzES1QSUybgKDKQfYzHoluc1ta63FkU5SQ?= =?us-ascii?Q?cCeCFFH5kMK5BpUHoR9LR0u4/nG/1e/zIHD8H/Cn7rWGs74WXyXs21gPJOlv?= =?us-ascii?Q?c0Q6Hg6UKODD1wlsSXIal9gJRuuq9fs6sYjKCrxhh11qh+88l+FEF6fuh4Zx?= =?us-ascii?Q?TpZMMO4ofKsIkshakoOYPOnHuIpmJTMHCf7LAhFbm7Oa4JaF1APLDElB54x7?= =?us-ascii?Q?SWI7KA5sP6UE9HYbBCDB7gxLzJcAY9UBCv5kJUN7sys2M0DgRZ+qwncIhPgA?= =?us-ascii?Q?rAxCe1vNY/Bp1nWMz6zGbx6lmOxlAQX61PDCwivitRrcKU1Sal1PryKA1p6y?= =?us-ascii?Q?sbcLv0cNPf+TP344a8S4E53t6h7FkeG0cZNPuhIsxc+fYOj4XfC0mAIodwWv?= =?us-ascii?Q?S3okueoP+jXUrnCe72Ysi6sqGkgpF5/+BrnlM/flGvE4rKgvjuu5CH7n1JPp?= =?us-ascii?Q?WoHWvW1gozBs1oyymIQu3CfcmEYQTrD8k7iTmWH2BQ1v34kD+g4flvIZ84jn?= =?us-ascii?Q?usCgyuN29hISkzAFCC04YG2flXe5JhQ2hI644XCux7Lm3thzlRNoz+k6aOTP?= =?us-ascii?Q?iHlF5MEnbOZ9Bp0aLu3imVqHqgEJZqOnfNy7EQv7PinVykKZnvCH+dXsD6h7?= =?us-ascii?Q?SIVST7+2ewQOzZ5UZSeZpsbLO2OapHqYsluxTnqk5j6O5DQG51cLYJB9Hh1H?= =?us-ascii?Q?wr2nEXko+70ZlCgfV9AnoW69ZkDzqoDVMRJPVn2BhbczsKnjfU+LR5hPjiIs?= =?us-ascii?Q?4VRPQBOrk07nlUmcD9VBy4Jy5m+yog9hlQqecip/L+GXNnEB/f6tcYjIznmq?= =?us-ascii?Q?tkVl4TlPFfOJ+Sq7GlQizWjyPxlQO7PKzMK5Cn3iPMkmKw7MkeDh+Voy2E5t?= =?us-ascii?Q?vUUpvKu1lUt+52erc1BploH3n5p6Z3ZjMdQT+SshHw=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM6PR12MB3849.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(376005)(366007)(1800799015)(7416005);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?p76T6yqTsQOHnQpcWmThksxrKFYXd/AkW4bqSmwYUz8bz2Hdfg/Ao2VShGvW?= =?us-ascii?Q?BRm4jgx3Vwtu7Az2gTjRJA7lKAOj4HbbkIiutNl0rGAcCe7Zgk+ZIZpDFkr8?= =?us-ascii?Q?6/5oTnoDUTfvz9mx1da7QnXn1kxptHFn2R2nJULgaK6dlLd1v+C5/590vvd1?= =?us-ascii?Q?KpsSZzhOo1VX7jAvTifWmmCKBSWiSBjEeTPcE3abyqAxTyBhlgH5Txyc1LOk?= =?us-ascii?Q?XBazbfZLKv7LUVqjSDZgQF0qlq9ZIfhaGd0xvj3t+rjCRSwOeICdQWRqyV+O?= =?us-ascii?Q?XV/JRMDJxdGWwXQ8yQ5KcJo3df8zw34X4TT0vMWBl9hLAENJk83pttDC7wWa?= =?us-ascii?Q?D+KD3RT6VfmR9X/xD4CxZAxvHgaZqj3eLSgY3O2hN3AzjvyIAjGsQXWfFUwD?= =?us-ascii?Q?4rZ4IKQ9nSxTKulFlwu0H/KEcrdqk7c4aKAe+LEKWm/PBmISBfDtNe4T2alH?= =?us-ascii?Q?GrRIwZQKdt8S43pwZpLHBH4JypLYD9CogFbgGVgJYzGVi75wy9qAUpVA70fm?= =?us-ascii?Q?sd47XLjFDLalvIjCAPnPamRGi1QGGyb6idM1rO5OD/r3EIQ/PXc2tZ6XYg7G?= =?us-ascii?Q?WZKTWhFS7/z6r0CxciVn8j+yCiLGBfdW0kpmjJBVgvg1AMhNbGfJUJSCy7sa?= =?us-ascii?Q?dgir/LZPysYiBGefYiZwlSaiuDQ38S+7CsOqGvs6vRUxRuOVl7wWMScebkkz?= =?us-ascii?Q?1aL2aUQ4ouH/s7+AfzVE3Yp2PUz40bfaZJRkHV2O9miULwH9C47JiUa7bbxN?= =?us-ascii?Q?u6/PmFnAa0HDCK2eMHAfTS1qsd8c3o3w174FKbRdyxLiT4HCrG/AJCKHiPtR?= =?us-ascii?Q?6UENhFdYzrXxjdIpsDSwdje8h5pbFgwuYRWATuY4JNjizD5YKQERTXpfmk0r?= =?us-ascii?Q?zbS0wN7whbw85Yyg4mHGgiUPCOZEV1xlGjHu+hqZSrHRemYRGHhZTxZwmpgS?= =?us-ascii?Q?G0R+8zZy1OtKWhesPmBDFpnPHQeQ7+S5yQMaBdWCVefDYtZF2/t1HiDy+k3V?= =?us-ascii?Q?jkDEEIru9HQgTx6cuI3Z377FMKDM26vB59tu8ladGxDRzytcC+MbpcqG0gFq?= =?us-ascii?Q?Z72gBHzRBGMPzcA/CosGk1t6zy2sVBtAPwTEuvC75GcHVEvmv0zGfdQ4z3MP?= =?us-ascii?Q?3gcRzmxTJoWV2b2vbxtH3LwBfOQ5vjBI9+Op/MtpZUQ3GZqesK9IHyxWI8yI?= =?us-ascii?Q?gfDUwEFr43km5uUoY+XojK535nLxYd15GfVeY/rz+ZQ7FzaON1penByQpZSg?= =?us-ascii?Q?3V0v3f67iWGowsreeOu96imzFy7mmcLl09VGs9VaRlC7O41fSaJt8hIRm9U/?= =?us-ascii?Q?yapsYM2Rl+o+ec0v3C9eGFIaCN2/q5mdlgIXCEVPRmr2yKmZt5VHOzC7E7XN?= =?us-ascii?Q?H7RilTJV4wBErjHMx80NeoFAntk27/SYp0fq9N4IqBC58AaBwfRJG+UhxIFa?= =?us-ascii?Q?8+frIHpPLeLXFSAzQjx47ntcQDwySiAvfI+JShPbIcdcaCKZya7NgNoVn0uO?= =?us-ascii?Q?GzfNrU0TNbaDitfiwek5Hn0FKqLT7LtRKhWaVPsnGPnrCZYWQtOUHNNcn61L?= =?us-ascii?Q?TSfrqRyJV7CSDXXErhHnqpp8OMaPrDgOxl3bI2S1?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0355b6ab-4452-4a1a-4af7-08dc6f7cde70 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB3849.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 May 2024 16:35:27.9658 (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: xPyMdqyK3WysIKrMlcxTEXfhGBXQ7JcEM0uR5J5NhAwaewpodyhxx3wdVeb3GBz6 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6368 X-Rspam-User: X-Rspamd-Queue-Id: 0B366C0019 X-Rspamd-Server: rspam06 X-Stat-Signature: bcf6ka36rzb883uppeqnbzkoz5ygpbk7 X-HE-Tag: 1715186131-975885 X-HE-Meta: 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 KwwUs9j5 ylyMYyescwfgmqqUOH6KhkY3DG/s6jOHxQzFqUQXDzRAvlMvqGwK24BL4b8D5knRdKGQ2vGuMhXpjikmudecM2P8t+nZ5X4FWfjAIXG0iOD+HcOxjow9fWNxUaQggR2ZywEaUTwA0ed7Fk75ntokPd+WoC66hOzHIVeRhNcXmbaeY+DbNnOrrIkaIx7wLdCl/D+Vr4RW5Wt8KVzJG/JGcwqwASw== 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 Wed, May 08, 2024 at 12:22:08PM -0400, Zi Yan wrote: > On 8 May 2024, at 11:52, Jason Gunthorpe wrote: > > > On Wed, May 08, 2024 at 10:56:34AM -0400, Zi Yan wrote: > > > >> Lance is improving try_to_unmap_one() to support unmapping PMD THP as a whole, > >> so he moves split_huge_pmd_address() inside while (page_vma_mapped_walk(&pvmw)) > >> and after mmu_notifier_invalidate_range_start() as split_huge_pmd_locked() > >> and does not include the mmu notifier ops inside split_huge_pmd_address(). > >> I wonder if that could cause issues, since the mmu_notifier_invalidate_range_start() > >> before the while loop only has range of the original address and > >> split huge pmd can affect the entire PMD address range and these two ranges > >> might not be the same. > > > > That does not sound entirely good.. > > > > I suppose it depends on what split does, if the MM page table has the > > same translation before and after split then perhaps no invalidation > > is even necessary. > > Before split, it is a PMD mapping to a PMD THP (order-9). After split, > they are 512 PTEs mapping to the same THP. Unless the secondary TLB > does not support PMD mapping and use 512 PTEs instead, it seems to > be an issue from my understanding. I may not recall fully, but I don't think any secondaries are so sensitive to the PMD/PTE distinction.. At least the ones using hmm_range_fault() are not. When the PTE eventually comes up for invalidation then the secondary should wipe out any granual they may have captured. Though, perhaps KVM should be checked carefully. > In terms of two mmu_notifier ranges, first is in the split_huge_pmd_address()[1] > and second is in try_to_unmap_one()[2]. When try_to_unmap_one() is unmapping > a subpage in the middle of a PMD THP, the former notifies about the PMD range > change due to one PMD split into 512 PTEs and the latter only needs to notify > about the invalidation of the unmapped PTE. I do not think the latter can > replace the former, although a potential optimization can be that the latter > can be removed as it is included in the range of the former. I think we probably don't need both, either size might be fine, but the larger size is definately fine.. > Regarding Lance's current code change, is it OK to change mmu_notifier range > after mmu_notifier_invalidate_range_start()? No, it cannot be changed during a start/stop transaction. Jason