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Tue, 10 Sep 2024 04:15:03 +0000 Received: from DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::953f:2f80:90c5:67fe]) by DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::953f:2f80:90c5:67fe%3]) with mapi id 15.20.7918.024; Tue, 10 Sep 2024 04:15:03 +0000 From: Alistair Popple To: dan.j.williams@intel.com, linux-mm@kvack.org Cc: Alistair Popple , 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: [PATCH 02/12] pci/p2pdma: Don't initialise page refcount to one Date: Tue, 10 Sep 2024 14:14:27 +1000 Message-ID: <4f8326d9d9e81f1cb893c2bd6f17878b138cf93d.1725941415.git-series.apopple@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: X-ClientProxiedBy: SY5P282CA0191.AUSP282.PROD.OUTLOOK.COM (2603:10c6:10:249::14) To DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB7726:EE_|BY5PR12MB4148:EE_ X-MS-Office365-Filtering-Correlation-Id: 17208fe1-2f79-4791-0afc-08dcd14f24d7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024; 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This is currently the case for MEMORY_DEVICE_PRIVATE and MEMORY_DEVICE_COHERENT pages but not MEMORY_DEVICE_PCI_P2PDMA pages so fix that up. Signed-off-by: Alistair Popple Reviewed-by: Dan Williams --- drivers/pci/p2pdma.c | 6 ++++++ mm/memremap.c | 17 +++++++++++++---- mm/mm_init.c | 22 ++++++++++++++++++---- 3 files changed, 37 insertions(+), 8 deletions(-) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 4f47a13..210b9f4 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -129,6 +129,12 @@ static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj, } /* + * Initialise the refcount for the freshly allocated page. As we have + * just allocated the page no one else should be using it. + */ + set_page_count(virt_to_page(kaddr), 1); + + /* * vm_insert_page() can sleep, so a reference is taken to mapping * such that rcu_read_unlock() can be done before inserting the * pages diff --git a/mm/memremap.c b/mm/memremap.c index 40d4547..07bbe0e 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -488,15 +488,24 @@ void free_zone_device_folio(struct folio *folio) folio->mapping = NULL; folio->page.pgmap->ops->page_free(folio_page(folio, 0)); - if (folio->page.pgmap->type != MEMORY_DEVICE_PRIVATE && - folio->page.pgmap->type != MEMORY_DEVICE_COHERENT) + switch (folio->page.pgmap->type) { + case MEMORY_DEVICE_PRIVATE: + case MEMORY_DEVICE_COHERENT: + put_dev_pagemap(folio->page.pgmap); + break; + + case MEMORY_DEVICE_FS_DAX: + case MEMORY_DEVICE_GENERIC: /* * Reset the refcount to 1 to prepare for handing out the page * again. */ folio_set_count(folio, 1); - else - put_dev_pagemap(folio->page.pgmap); + break; + + case MEMORY_DEVICE_PCI_P2PDMA: + break; + } } void zone_device_page_init(struct page *page) diff --git a/mm/mm_init.c b/mm/mm_init.c index 4ba5607..0489820 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1015,12 +1015,26 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, } /* - * ZONE_DEVICE pages are released directly to the driver page allocator - * which will set the page count to 1 when allocating the page. + * ZONE_DEVICE pages other than MEMORY_TYPE_GENERIC and + * MEMORY_TYPE_FS_DAX pages are released directly to the driver page + * allocator which will set the page count to 1 when allocating the + * page. + * + * MEMORY_TYPE_GENERIC and MEMORY_TYPE_FS_DAX pages automatically have + * their refcount reset to one whenever they are freed (ie. after + * their refcount drops to 0). */ - if (pgmap->type == MEMORY_DEVICE_PRIVATE || - pgmap->type == MEMORY_DEVICE_COHERENT) + switch (pgmap->type) { + case MEMORY_DEVICE_PRIVATE: + case MEMORY_DEVICE_COHERENT: + case MEMORY_DEVICE_PCI_P2PDMA: set_page_count(page, 0); + break; + + case MEMORY_DEVICE_FS_DAX: + case MEMORY_DEVICE_GENERIC: + break; + } } /*