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dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.117.161 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.117.161; helo=mail.nvidia.com; pr=C Received: from mail.nvidia.com (216.228.117.161) by CO1PEPF000044F9.mail.protection.outlook.com (10.167.241.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6652.5 via Frontend Transport; Fri, 28 Jul 2023 21:32:23 +0000 Received: from rnnvmail201.nvidia.com (10.129.68.8) by mail.nvidia.com (10.129.200.67) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.5; Fri, 28 Jul 2023 14:32:14 -0700 Received: from [10.110.48.28] (10.126.230.35) by rnnvmail201.nvidia.com (10.129.68.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.37; Fri, 28 Jul 2023 14:32:13 -0700 Message-ID: Date: Fri, 28 Jul 2023 14:32:12 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout Content-Language: en-US To: Peter Xu , David Hildenbrand CC: Linus Torvalds , , , , Andrew Morton , liubo , Matthew Wilcox , "Hugh Dickins" , Jason Gunthorpe References: <20230727212845.135673-1-david@redhat.com> <69a5f457-63b6-2d4f-e5c0-4b3de1e6c9f1@redhat.com> From: John Hubbard In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.126.230.35] X-ClientProxiedBy: rnnvmail203.nvidia.com (10.129.68.9) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PEPF000044F9:EE_|DS7PR12MB6189:EE_ X-MS-Office365-Filtering-Correlation-Id: 56e791ca-62cd-4e04-515e-08db8fb221c2 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:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230028)(4636009)(346002)(396003)(39860400002)(136003)(376002)(82310400008)(451199021)(36840700001)(40470700004)(46966006)(86362001)(7636003)(356005)(31696002)(36756003)(66899021)(31686004)(40460700003)(2906002)(40480700001)(478600001)(110136005)(54906003)(82740400003)(336012)(36860700001)(26005)(186003)(53546011)(2616005)(426003)(47076005)(16526019)(41300700001)(8676002)(316002)(70206006)(16576012)(70586007)(4326008)(83380400001)(7416002)(5660300002)(8936002)(43740500002);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jul 2023 21:32:23.4828 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 56e791ca-62cd-4e04-515e-08db8fb221c2 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000044F9.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6189 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 7/28/23 14:20, Peter Xu wrote: > On Fri, Jul 28, 2023 at 11:02:46PM +0200, David Hildenbrand wrote: >> Can we get a simple revert in first (without that FOLL_FORCE special casing >> and ideally with a better name) to handle stable backports, and I'll >> follow-up with more documentation and letting GUP callers pass in that flag >> instead? >> >> That would help a lot. Then we also have more time to let that "move it to >> GUP callers" mature a bit in -next, to see if we find any surprises? > > As I raised my concern over the other thread, I still worry numa users can > be affected by this change. After all, numa isn't so uncommon to me, at > least fedora / rhel as CONFIG_NUMA_BALANCING_DEFAULT_ENABLED=y. I highly > suspect that's also true to major distros. Meanwhile all kernel modules > use gup.. > > I'd say we can go ahead and try if we want, but I really don't know why > that helps in any form to move it to the callers.. with the risk of > breaking someone. It's worth the trouble, in order to clear up this historical mess. It's helping *future* callers of the API, and future maintenance efforts. Yes there is some risk, but it seems very manageable. The story of how FOLL_NUMA and FOLL_FORCE became entangled was enlightening, by the way, and now that I've read it I don't want to go back. :) thanks, -- John Hubbard NVIDIA