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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Randy Dunlap , netdev@vger.kernel.org, Arun Ajith S , Roopa Prabhu , Jaehee Park , Jonathan Corbet , Shuah Khan , Shuah Khan , linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v3 1/2] ipv6: update NUD_FAILED neighbors from NA messages Message-ID: <20260920080909.GA1826239@shredder> References: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: FR0P281CA0199.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:ad::7) To PH0PR12MB7957.namprd12.prod.outlook.com (2603:10b6:510:281::22) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR12MB7957:EE_|CH4PR12MB231692:EE_ X-MS-Office365-Filtering-Correlation-Id: 50cefa86-ef10-4493-10c2-08df16ee7880 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016|23010399003|3023799007|10067099003|11063799006|4143699003|56012099006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Xcv4jpKbNxfOMZ7umHJs3elh/L9u1A3S89bpK7FjVC2ZlHAFcWxEkvLaJoel?= =?us-ascii?Q?bSockJW0hzoyTc6YxXuCkOnJA4YKoDMpIKn7YIjxloemLraPjc4Zqcges80a?= =?us-ascii?Q?I2WArN0WiQwcg+HiGSf4Eavfy9+J8AN2lWuc3/RklDEyaeenC+OMnMrbCflk?= =?us-ascii?Q?ePXXuuOOslfgKBgQvoUFHkARITUqiPxOjhWVXwdS42vjI0DctXUCx0qBHjnh?= =?us-ascii?Q?pNCKiPx0YY/PkCZpB6/n0QYvH9eFNHpO7gnyqmo/x+9f1cRO8+baacB5Ue78?= =?us-ascii?Q?LbiDrTIzahB/3ITgs1dfFqHtJ5o4IIYwC7Dyu71sOF+ODthFygNWaP4gGyE5?= =?us-ascii?Q?IkLrFkkUQth/bFnpfw6RFbo6RT/DffyeGmotjA5ZViBho4HsRSHzxU2PCWMH?= =?us-ascii?Q?XQj5uMKjbru4wxVTAxGGWYKfAoauJJm5rfKhyKDG1Gc3nO3N8asDniPytOXA?= =?us-ascii?Q?R83vOxNenTQ/MYRxn5DsKozpX7c3le6JXUQX1CjuKJ0yEz5FIKg65Y81Awz9?= =?us-ascii?Q?Ph8XsgOMp8IaTe4DJx7NhyiLAcDU7fYsQp1LHehlWrWz7X9eo7BwJ5yZuIjt?= =?us-ascii?Q?+9gN6dNWyTq3pxQ3P4VfCZ+hr9/qGoasdE7HlOeci1Ytpsv7Ab1s5FPgryvD?= =?us-ascii?Q?cTWgIjFdwe0X7YE/T0J0ZMbZqBfUWjmNBpBXpS0pQgyVs21g2y8Tp4jaFcHk?= =?us-ascii?Q?DpPrANUCO/6dgFHzmYoI9fgpazA/t2yFk98SqySy5xHpvH7goS1TDUxRLYRZ?= =?us-ascii?Q?eYMtgrkSU6LZX5YMxhksE9WemGLI5TPN0I4G/mYsZ3zBwhAKVzKlL3QfFiau?= =?us-ascii?Q?C36TFYCqwwQtHQK05oUIYGIfNLKflBgnKi6AbUcrgr6oxSb1SwEd0RScUqsw?= =?us-ascii?Q?IuPl4rM78PCaJbpQY0cCBexgjt3HJmznARjVfDiVDscgorsJJRfvE8ioBmgo?= =?us-ascii?Q?CLbWGCYR1UBJ9+AtOLpo4EGlkwo6+Dx/6QHfOOb5z3U0iFqwfwI45Ui54TpV?= =?us-ascii?Q?BMGDqirpnlft09gcHtNIOPcZUrnbGSbzVV125wGjrtHPE5UgQp0mhuxObeq5?= =?us-ascii?Q?3BPGnJ4JKRKkI+5pizZZfC8s/IOx+VwqRfCqjWm31kGVPX6GyrS22pRIaTAO?= =?us-ascii?Q?Kp/VDhA8AXGnDRR949XLUAhE2pRS6ciM17lIXkaD7sKs6EdPVfjH+EohftQ5?= =?us-ascii?Q?1vnCZkmBfU7cNcEsMytn/D+CMMyP/L9I29ndpf7GW/k0NP4ap7PZ2/clVJyH?= =?us-ascii?Q?VKanWsr2iCjUAO6rpjZitdYqTBGzSu4Je1SQkrqD2US3AImwqNKGLLoiBFm2?= =?us-ascii?Q?QVObDYdyErQpRbAdRjUL3aqvIStlYqvAUVf20nzbvonp8exFGobll+XRox2q?= =?us-ascii?Q?Ifh2Nuc2+5uEwfL/dxUMT82DReMGv6/go8WUcr6yZSxBNSS5IoGkDh/yyv2z?= =?us-ascii?Q?9hacapOsRhuojJrjIXgCKFlbfrih/dwa9yrEEEgsE+JeC4S0UjE/wM/DdX8/?= =?us-ascii?Q?M/+zZOD7EUp93H3xbD00YQcGSfRx7U3KJrIAESE3YNWHn6ko83vRVeFuAyl6?= =?us-ascii?Q?9MsBYRSKtp/0swEaV9FIGYwbWFe6jhogVvEAOl13DmrPceT8rqQvwgCz1HwI?= =?us-ascii?Q?lVT76V+aTxOc6qDFlR+5x2hrg/9FGBh9iorvNVWlMKkmoG0w/esrdn7VeA9I?= =?us-ascii?Q?gupy5BVK03lWKd1QcmLHU/Fwz3qhiQqpmHDcePXQ8Bj5BK+MVjePUDY7H3Bk?= =?us-ascii?Q?UVHchR+I9g=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 50cefa86-ef10-4493-10c2-08df16ee7880 X-MS-Exchange-CrossTenant-AuthSource: PH0PR12MB7957.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Sep 2026 08:09:19.1772 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ieOVhBnsq7eSyu1auDVYrp+z1IXKXsSLp37e2j3rnZ2S7X5ioB9P+krBs3zfwna6fonNcpit2/jiJbq0ZeFiMw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH4PR12MB231692 On Fri, Sep 18, 2026 at 10:13:23PM +0000, Lawrence Lee wrote: > Transition a FAILED neighbor entry to STALE upon receipt of an NA > message on routers when accept_untracked_na is enabled. This extends the > RFC 9131 accept_untracked_na behavior so that FAILED entries are treated > the same as non-existent entries. > > RFC 4861 section 7.3.3 says that an entry should be deleted when address > resolution fails. Linux instead retains the entry in NUD_FAILED, so > treating it as untracked is consistent with the protocol model. > > Trying to resolve FAILED neighbors via periodic probing (e.g. using > NTF_EXT_MANAGED) is more work compared to this approach which uses > information in NAs that the kernel may already be receiving. Note that > because this behavior in IPv6 is dependent on the accept_untracked_na > sysctl setting, this approach is more conservative than IPv4 which > transitions FAILED neighbors to STALE by default upon receiving GARPs. > > Link: https://lore.kernel.org/r/20260813233344.445265-1-lfqlee314@gmail.com > Assisted-by: LLM Sashiko sparse > Signed-off-by: Lawrence Lee Reviewed-by: Ido Schimmel