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 72907ECAAA1 for ; Tue, 6 Sep 2022 15:33:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B2B418029D; Tue, 6 Sep 2022 11:33:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AD99780224; Tue, 6 Sep 2022 11:33:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 953758029D; Tue, 6 Sep 2022 11:33:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 81A8180224 for ; Tue, 6 Sep 2022 11:33:26 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 4B810C0779 for ; Tue, 6 Sep 2022 15:33:26 +0000 (UTC) X-FDA: 79882054812.30.47B26BA Received: from NAM10-BN7-obe.outbound.protection.outlook.com (mail-bn7nam10on2080.outbound.protection.outlook.com [40.107.92.80]) by imf08.hostedemail.com (Postfix) with ESMTP id EBBEA160084 for ; Tue, 6 Sep 2022 15:33:24 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=XHLjvTitugnNz59y7odCy57GPzbh7xW7XlfXXs+2g0DHsmuF9PBYoUSaOCE6o8e7zTaVjxufmPO1MZsxzUpZnrLxQgyylWAWP8lU00kdwDbGBr4vxkBFlPxzXl11BqoYbE42KsLbOo4TPBvjlvZsmMObtOO38T0WK47fFxFbJA8K8SWLDAUyGdyqKIluKimMsgl4/Vp6tOCuzxPX3jhy0eroE4HoIR8LLn5ihPjstPdzGRz8li2eZaxI2JQjAY8RvbfpjOwPdTf7NW50S/XuKA4KZ7FKlhhTZJhSaO0AfcdTijE7odqaTschBCjd0amcKVYxWPuRkCI15OL3WLYZrg== 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=85zNFP4iOcjSRuEklV+/IZ4dHqEv1vmNtNiho4vIu8U=; b=kWjeNz35qsXYkky2VQJPVhyS9U6sXHY9L3Yx8LKYvhRmbiSN2tFjCh8XYKoAca6SFS0WwcTovG3gjAi2TCGD5bKS5yi3EGXUY6ys2g7gp74p6vZHylvBf4xrhPz2TJ4RQr/uD8mN/pvR3LYggwtL/Yf1+cyviJE+pSbX/3miBsgyIJgTtkRJta4NdYKVLbNT+vNbayax6pqkFN/oxdtGADVgNY5mq2XoIqQQKCjPYOMiADeFoBWikelYTMM6iNc9jq8pOTA8Bf2lO64CW5xE1/8b8CLhE3US2kJR1Po63P12Lm/7+HjYjsz2F+j5TqkhCFK4NLmyJaMbBsucSs8Bww== 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=85zNFP4iOcjSRuEklV+/IZ4dHqEv1vmNtNiho4vIu8U=; b=BpePv8xGT6pleJKvFWrAgrGGjFZyLh2hMKb8AAtMc7Lb5F3uECQ3yb4CqSMc5WOvK+j1H/1PRzK7Sxz6xui0Qd6lfedFylDn8Hf1UOHQlXRErx9vK3SvjrjutvWiasxfjuKy5nPShFKOUqxhaeb0ankXQuVyiEYYNm5BFtLFD+h7H7BeL5tc10zS+ZgO/DjJmQVR4tJyQ1/TYvutWUduVOeVS++apuWaCD4VftibPtYjO9Q5d0o+o9UTmz1TMrGZGslzrL4wQmPjBkqQWQ4eEr6wAkcdfl5bp9xyXu6BZ3RzQ91uUrBsYT8tGu14l/LsDM8Nv26BcFeRl2UTcPhzGQ== Received: from MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) by CH0PR12MB5026.namprd12.prod.outlook.com (2603:10b6:610:e1::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5612.12; Tue, 6 Sep 2022 15:33:22 +0000 Received: from MN2PR12MB4192.namprd12.prod.outlook.com ([fe80::462:7fe:f04f:d0d5]) by MN2PR12MB4192.namprd12.prod.outlook.com ([fe80::462:7fe:f04f:d0d5%7]) with mapi id 15.20.5588.018; Tue, 6 Sep 2022 15:33:22 +0000 Date: Tue, 6 Sep 2022 12:33:21 -0300 From: Jason Gunthorpe To: David Hildenbrand Cc: John Hubbard , Yang Shi , peterx@redhat.com, kirill.shutemov@linux.intel.com, hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: gup: fix the fast GUP race against THP collapse Message-ID: References: <20220901222707.477402-1-shy828301@gmail.com> <4516a349-49cb-fd7b-176a-f1a9479906d9@redhat.com> <40486dbb-9f19-6fa6-d46d-99d2b033883d@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40486dbb-9f19-6fa6-d46d-99d2b033883d@redhat.com> X-ClientProxiedBy: BL1PR13CA0200.namprd13.prod.outlook.com (2603:10b6:208:2be::25) To MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 31ecc236-6791-4176-32f6-08da901d2202 X-MS-TrafficTypeDiagnostic: CH0PR12MB5026:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN2PR12MB4192.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(346002)(136003)(366004)(376002)(39860400002)(396003)(316002)(38100700002)(41300700001)(36756003)(6916009)(54906003)(4326008)(66946007)(66556008)(6506007)(478600001)(8676002)(83380400001)(6486002)(66476007)(86362001)(8936002)(558084003)(186003)(2616005)(26005)(2906002)(5660300002)(6512007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ZbF7FP8mYqYoJHcO5yBGRUTbv12lkchZ3sNFPRJIoKlmXMTutFqR0Dz/oOpK?= =?us-ascii?Q?adPDYDhvl7aOLqhWJIEgNFvvoIdp7w+Ot3mT8GpBlBCDNmdO7dS9hV9sf/Bv?= =?us-ascii?Q?zjA7UQj7nncb6gEFhjRVcv3b8x5OgZsQafRNWDVwponsj5IulgTSEKM7PpMT?= =?us-ascii?Q?NWnjBtFN5Z3Zxgpr0K0mein3GSN26mubyFdu0Q7tR3V3xV7+kcFQCzQ2o2A+?= =?us-ascii?Q?7oRsmZG0+fKqAfGoWZCzETEoDhdBwcgUQ1Dg56QEjXuR0rutRl9ntAhoyoXh?= =?us-ascii?Q?KJBIXG5kIFHGCsFrbOrUwuGZHVw4ckeIEeowU+TmsgppQGQbkWaytE8DSLw0?= =?us-ascii?Q?iGJdeCNvvKIz0Kfza94UbwwMQgKqVwPNOJ1ojmJ4l9ltFiCDXw8c9OU3P3Kz?= =?us-ascii?Q?Lf2vk5nPBqto2tVxIN3MX4W02IUgRobLPVMEInucemvsC2bg5+kuKFBzUpPy?= =?us-ascii?Q?dBIwWsmIqzdsoPGAUXgfT7T82yHcbCBFG6bvCGbpPHvwSAUxqh+E6LPFOVaN?= =?us-ascii?Q?n/ICRvyXVOTRVZphFmqVGm2mkJ3PFn+uz2qYGCz23Milno1kpFOThtc9fswg?= =?us-ascii?Q?wC69sWK3OQMXoML3tUptZ94KeD3hF2EfR9h5fJj243FUV8bgI2udgnvtNjbb?= =?us-ascii?Q?aXJsknFhYYQxHe7LudpeO8titnEKMxCZhTO71VtEOVIysXU0mRpRI3FwLUO/?= =?us-ascii?Q?/n9MF1CsLHOuOh+zmebJ2ep9nB3YQLfjAOrJpweYhDF8ozhvIMd1tRinasff?= =?us-ascii?Q?YnctdXvgPxYGo/F+Sylhr0r1Hd/0ysfQIiuK80PwPXWc+c+nwMNZCLk4YiF1?= =?us-ascii?Q?42IrspYP71ZV60vL0PX2GB1WraZB4IHktFP0P7lxEq+Y2PrMY/AKY5+4wWIX?= =?us-ascii?Q?wu46Go3AYufJQowlSpeBFbjnfYAcq0qEsyBelnUt3iNMZN8vHFYvZcU7ilgW?= =?us-ascii?Q?dIsMJSvbBIpGQNglLiSF894WG/RTCJ5jje4lx7beTrinS9xYOcUonTUxIu+4?= =?us-ascii?Q?EuJWf6JktrJ2+mMcBTGBqd8zTAJB9q3xpAt4kgOKSB9O7r9E00cKimzwBXKL?= =?us-ascii?Q?lDeXDzmJztKrzrLI5KsXXkpddWauzRRsaF+QzdGYfk/f5MkeJNazIzRR/qvU?= =?us-ascii?Q?gN28/rBMDm2DskUMZboKOL7e14Rg3NqzvPXIGwXNbe5SLirsutO3tRroK/VV?= =?us-ascii?Q?dH8g23SkSzZznnmOcCmKuR9EcjzoMrdklg5yPeG9k5f0hPvzInvavLueGAet?= =?us-ascii?Q?gHDKb93RqDPYL0qz3FQNxygJZNReHDuFDI7myvBuKvTixWwjkTAFGSJagapQ?= =?us-ascii?Q?l1NYJKOJvi7WSttcXa5tXDsIfw2LgeWaBQjMe3XE+9a2Mw8M5cDadfURFui5?= =?us-ascii?Q?bqHpyFsjREgRmbcD2CGluL4wNo39Pz+3aczhRQsj4epy9kyfB2TVGccmN6En?= =?us-ascii?Q?jr0GYTq3gOZh9npJtOh6PXEAw/gWUTyD+Yw2IwyLCwmpO28yytjvrt8dF0p2?= =?us-ascii?Q?S4v1seL2AzSTzXLDqX3BCy5OFFyx/zAHpmL88omwhnLQWoCJzHkyMsSXnROD?= =?us-ascii?Q?nV1AO2KL3bCWentCp99PVk+en88sQZ6tSTNBU24N?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 31ecc236-6791-4176-32f6-08da901d2202 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Sep 2022 15:33:22.7241 (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: sAYWzqMobjPYE13FZTYr9n+x0o1vhuYAnjNh2oYb5eIxk6/7gufaCLpEIOBpUD8U X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR12MB5026 ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1662478405; a=rsa-sha256; cv=pass; b=rYCu+qREEy9SkyWTRKTAv0v0N9nfhbvcmueOrw4nizuaW5zY8/NP5p0E+uHRAeJ/ubS7OQ sUOPgN+Wz4Qn1+vXPklmPywjYMmq87drnKyDe0jCf2uv3UTIEDdVatXqq3cot4cwc0IJJH Es/Y27hm6fj2KT6WeOl/EoVmDI8Qtnc= ARC-Authentication-Results: i=2; imf08.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=BpePv8xG; spf=pass (imf08.hostedemail.com: domain of jgg@nvidia.com designates 40.107.92.80 as permitted sender) smtp.mailfrom=jgg@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector9901:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662478405; 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=85zNFP4iOcjSRuEklV+/IZ4dHqEv1vmNtNiho4vIu8U=; b=gj7Zo+DmAMnxkmrtFp/3y97eZGiqaywGsdosNHBheH4uYVnlSRT6bp8LQmJwlvDW5kG/mY N0SbW3RCnFo/xaRHYCS68ngWpt5zNkQTOHicSw1EXB81+hoyZ38FW+edpEZmDumLxV/uny UuxMFdiw22erwaOj4BJ2QEhRNIQMaOI= X-Rspamd-Queue-Id: EBBEA160084 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=BpePv8xG; spf=pass (imf08.hostedemail.com: domain of jgg@nvidia.com designates 40.107.92.80 as permitted sender) smtp.mailfrom=jgg@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com; arc=pass ("microsoft.com:s=arcselector9901:i=1") X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: 8wytb35janpkjkardyt19qbtw3e5xtjr X-HE-Tag: 1662478404-231912 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 06, 2022 at 04:44:20PM +0200, David Hildenbrand wrote: > ... I do wonder if we want to reuse ptep_get_lockless() instead of the > READ_ONCE(). CONFIG_GUP_GET_PTE_LOW_HIGH is confusing. Yes, that is a whole other topic, and you may be quite right on that. Jason