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Fri, 11 Feb 2022 16:45:38 +0000 Date: Fri, 11 Feb 2022 12:45:37 -0400 From: Jason Gunthorpe To: David Hildenbrand Cc: Alex Sierra , akpm@linux-foundation.org, Felix.Kuehling@amd.com, linux-mm@kvack.org, rcampbell@nvidia.com, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, hch@lst.de, jglisse@redhat.com, apopple@nvidia.com, willy@infradead.org Subject: Re: [PATCH v6 01/10] mm: add zone device coherent type memory support Message-ID: <20220211164537.GO4160@nvidia.com> References: <20220201154901.7921-1-alex.sierra@amd.com> <20220201154901.7921-2-alex.sierra@amd.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: MN2PR14CA0018.namprd14.prod.outlook.com (2603:10b6:208:23e::23) 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: b3b67288-2ce4-4852-4782-08d9ed7def00 X-MS-TrafficTypeDiagnostic: CH2PR12MB4875:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:6790; 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I'm pretty sure we cannot FOLL_PIN DEVICE_PRIVATE pages Currently the only way to get a DEVICE_PRIVATE page out of the page tables is via hmm_range_fault() and that doesn't manipulate any ref counts. Jason