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emacs 29.1 From: Alistair Popple To: Bjorn Helgaas Cc: dan.j.williams@intel.com, linux-mm@kvack.org, vishal.l.verma@intel.com, dave.jiang@intel.com, logang@deltatee.com, bhelgaas@google.com, jack@suse.cz, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, dave.hansen@linux.intel.com, ira.weiny@intel.com, willy@infradead.org, djwong@kernel.org, tytso@mit.edu, linmiaohe@huawei.com, david@redhat.com, peterx@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com Subject: Re: [PATCH 02/12] pci/p2pdma: Don't initialise page refcount to one Date: Wed, 11 Sep 2024 11:07:51 +1000 In-reply-to: <20240910134745.GA577955@bhelgaas> Message-ID: <87r09rgfjj.fsf@nvdebian.thelocal> Content-Type: text/plain X-ClientProxiedBy: SY5P282CA0057.AUSP282.PROD.OUTLOOK.COM (2603:10c6:10:20a::9) To DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB7726:EE_|PH7PR12MB5734:EE_ X-MS-Office365-Filtering-Correlation-Id: 4ac3c709-a737-40e2-d939-08dcd1feb700 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016; 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As we have >> + * just allocated the page no one else should be using it. >> + */ >> + set_page_count(virt_to_page(kaddr), 1); > > No doubt the subject line is true in some overall context, but it does > seem to say the opposite of what happens here. Fair. It made sense to me from the mm context I was coming from (it was being initialised to 1 there) but not overall. Something like "move page refcount initialisation to p2pdma driver" would make more sense? - Alistair > Bjorn