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Howlett" , Suren Baghdasaryan , Arnd Bergmann , Shakeel Butt , linux-api@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim Subject: [PATCH 0/2] unrestrict process_madvise() for current process Date: Mon, 23 Sep 2024 17:03:55 +0100 Message-ID: X-Mailer: git-send-email 2.46.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: LO4P123CA0381.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:18f::8) To SJ0PR10MB5613.namprd10.prod.outlook.com (2603:10b6:a03:3d0::5) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ0PR10MB5613:EE_|DM4PR10MB6744:EE_ X-MS-Office365-Filtering-Correlation-Id: 3656529c-1f68-44d2-ed57-08dcdbe9585f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|10070799003|1800799024|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Zs7rsEV0G+k73oFAOTJD5pdwI+sOqcaLdg+Ca86VYgb6S/FlJwcxXXHlwO7O?= =?us-ascii?Q?/mjC6iL8iB82+TRPANe7M+ZX/vI4kKmDHLMYcNCr1pVbVS1bfIYXz2SrLHhl?= =?us-ascii?Q?ttehmd/idoIrq32VGaFgbOfB7qgMgyjrVanqmOZ63NPhwnKsy+qsEzcQNnAI?= =?us-ascii?Q?Eo2uRq0gp8XbQNgbD/QQzwSzToi5kixk9bS+BSdHvfoJ2xAsF1rBHheOB88l?= =?us-ascii?Q?Bk7mefFRkTZut4nH7YinS83mtjt9jVObpve4n34PANw7z/Mo/XWp6dOI5XPb?= =?us-ascii?Q?sKUfU6e/9GkgbC2rqPogiSMcXM7b4RDYcgsq9YxHBwQT3OnLB4zdasY+X3MV?= =?us-ascii?Q?MUAWCq9fosSKVC/hG8JdsuFqCG9nW+LUR4vpp3zHzN3CKF2k3SWW/+yr96NV?= =?us-ascii?Q?PMvvELwHS3XH5ZNHYu3/pb8ujzulgq0I8WG1H7adGuTddwNYcSM71Wv91bVp?= =?us-ascii?Q?cmOWwO+mY1sjxV695uHwcutDRG1Nd0Z7RteGuNqxgDUKzFm6XpoOGrqY7Uoz?= =?us-ascii?Q?pkuhMwEzXHPL1QZz+glWnV1oxBA0GT40HMz0nauJpFDRTs4RMBk0fCumDCXI?= =?us-ascii?Q?oIEjY+5iXulnJ3ZTyaiugSpGzIRgmcKt7OHChLzKJK+3X5kpBgEnR6DkC0RQ?= =?us-ascii?Q?iKtN0BcdtWm/tQivX7HBfCSvTNfeXNL9eoGmlaZG9osvhXE0OpTi9iBaUvH0?= =?us-ascii?Q?BiqC5sV7YiXW8vobU5ychipFfGCWCwrNJs2A3AN1ekMRIct8SUK0L1B8p8Nd?= =?us-ascii?Q?SXg/jrolvNi848KYEftyrR3CsR6GlwgEgW5aYX/V3RgBiUT4+GJ32G0ncIY6?= =?us-ascii?Q?eL+wYMg/dsEffMlYVGgUFiUVIwasY+F+qreXuNe8KGTCj1Ikwgmwz2P7zU3h?= =?us-ascii?Q?RNGQynAaq91UtBL34CV9LXyvTcmSs1O7PtYnRXgF9qItkRAqTUviIFZKjhNx?= =?us-ascii?Q?ItiTiaItj8RzDTgtNA57soLo7nYaRibKmYVq9haD506Yn1hFLea1Y480ZZI1?= =?us-ascii?Q?7hmw0M79bKuO6qMQYfCpfsH3AaspX4dpfjnxQ6gskzBl+qS5AZv07FwaMDiA?= =?us-ascii?Q?Hc9NFBjsINeEnf9Tj33ARoY2Pgm8xFVgl9pC2+RHy1S5V9tFWIu9ZWP7LJm3?= =?us-ascii?Q?HsXbe4L1FALI7HX99ZyXJZSW1pobYrAwukfbIdE4TZFkhKcxNplXYL1Mzt09?= =?us-ascii?Q?9PWHV0tally6V0cIQzoOvCgRNR8lcAhoorVySVq7FZYVZXxwj9g3fNkyti9m?= =?us-ascii?Q?iGt7VbyGmxZuGHWc/98Ja8sxftVxVXpm80vWJ2T5C5ZW5ZGjfkfwMFe15LeR?= =?us-ascii?Q?2qnP0dQ+D6PVkLEBHO22FXayy5bmRZmb+yKY0Rx1CcdfGg=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SJ0PR10MB5613.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(10070799003)(1800799024)(376014);DIR:OUT;SFP:1101; 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However, as it provides the means by which to perform multiple madvise() operations in a batch via an iovec, it is useful to utilise the same interface for performing operations on the current process rather than a remote one. Using this interface targeting the current process is cumbersome - a pidfd needs to be setup for the current pid, and we are limited to only a subset of madvise() operations, a limitation sensible for manipulating remote processes but not meaningful when manipulating the current one. Commit 22af8caff7d1 ("mm/madvise: process_madvise() drop capability check if same mm") removed the need for a caller invoking process_madvise() on its own pidfd to possess the CAP_SYS_NICE capability, however this leaves the restrictions on operation in place and the cumbersome need for a 'self pidfd'. This patch series eliminates both limitations: 1. The restriction on permitted operations is removed when operating on the current process. 2. A new flag is introduced - PR_MADV_SELF - which eliminates the need for a pidfd - if this flag is set, the pidfd argument is ignored and the operation is simply applied to the current process. Therefore a user can simply invoke: process_madvise(0, iovec, n, MADV_..., PR_MADV_SELF); And perform any madvise() operation they like on the n ranges specified by the iovec parameter. This series also introduces a series of self-tests for this feature asserting that the flag functions as expected. Lorenzo Stoakes (2): mm/madvise: introduce PR_MADV_SELF flag to process_madvise() selftests/mm: add test for process_madvise PR_MADV_SELF flag use include/uapi/asm-generic/mman-common.h | 2 + mm/madvise.c | 58 +++++++--- tools/testing/selftests/mm/.gitignore | 1 + tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/process_madvise.c | 115 +++++++++++++++++++ 5 files changed, 161 insertions(+), 16 deletions(-) create mode 100644 tools/testing/selftests/mm/process_madvise.c -- 2.46.0