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Howlett" , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Jann Horn , Suren Baghdasaryan , Alex Gaynor , Boqun Feng , " =?UTF-8?B?QmrDtnJu?= Roy Baron" , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v14 4/8] mm: rust: add lock_vma_under_rcu Message-ID: <20250225162848.730a420e@eugeo> In-Reply-To: <20250213-vma-v14-4-b29c47ab21f5@google.com> References: <20250213-vma-v14-0-b29c47ab21f5@google.com> <20250213-vma-v14-4-b29c47ab21f5@google.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-pc-linux-gnu) Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-ClientProxiedBy: LO4P123CA0331.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:18c::12) To LO2P265MB5183.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:253::10) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LO2P265MB5183:EE_|CWXP265MB2805:EE_ X-MS-Office365-Filtering-Correlation-Id: 56c5f514-dd6a-4c56-7c1d-08dd55b97ccb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|10070799003|7416014|1800799024|376014|7053199007; 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Because the mmap lock is global to the process, this can > involve significant contention. However, the kernel has a feature called > per-vma locks, which can significantly reduce contention. For example, > you can take a vma lock in parallel with an mmap write lock. This is > important because contention on the mmap lock has been a long-term > recurring challenge for the Binder driver. > > This patch introduces support for using `lock_vma_under_rcu` from Rust. > The Rust Binder driver will be able to use this to reduce contention on > the mmap lock. > > Acked-by: Lorenzo Stoakes > Reviewed-by: Jann Horn > Reviewed-by: Andreas Hindborg > Signed-off-by: Alice Ryhl Reviewed-by: Gary Guo > --- > rust/helpers/mm.c | 5 +++++ > rust/kernel/mm.rs | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++