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Miller" , Andreas Larsson , Arnd Bergmann , Greg Kroah-Hartman , Dan Williams , Vishal Verma , Dave Jiang , Nicolas Pitre , Muchun Song , Oscar Salvador , David Hildenbrand , Konstantin Komarov , Baoquan He , Vivek Goyal , Dave Young , Tony Luck , Reinette Chatre , Dave Martin , James Morse , Alexander Viro , Christian Brauner , Jan Kara , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , Uladzislau Rezki , Dmitry Vyukov , Andrey Konovalov , Jann Horn , Pedro Falcato , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-csky@vger.kernel.org, linux-mips@vger.kernel.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-mm@kvack.org, ntfs3@lists.linux.dev, kexec@lists.infradead.org, kasan-dev@googlegroups.com Subject: Re: [PATCH 12/16] mm: update resctl to use mmap_prepare, mmap_complete, mmap_abort Message-ID: <20250908132447.GB616306@nvidia.com> References: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: YT3PR01CA0051.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:82::22) To PH7PR12MB5757.namprd12.prod.outlook.com (2603:10b6:510:1d0::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR12MB5757:EE_|PH7PR12MB6882:EE_ X-MS-Office365-Filtering-Correlation-Id: fce15a36-c8f7-47ad-070f-08ddeedb15fe X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; 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Therefore, establish the mutex in mmap_prepare(), release it in > mmap_complete() and release it in mmap_abort() should the operation fail. The mutex can't do anything relative to remap_pfn, no reason to hold it. > @@ -1053,15 +1087,11 @@ static int pseudo_lock_dev_mmap(struct file *filp, struct vm_area_struct *vma) > return -ENOSPC; > } > > - memset(plr->kmem + off, 0, vsize); > + /* No CoW allowed so don't need to specify pfn. */ > + remap_pfn_range_prepare(desc, 0); This would be a good place to make a more generic helper.. ret = remap_pfn_no_cow(desc, phys); And it can consistently check for !shared internally. Store phys in the desc and use common code to trigger the PTE population during complete. Jason