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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Omid Ehtemam-Haghighi , linux-kernel@vger.kernel.org Subject: Re: [PATCH net 1/2] ipv6: fix possible infinite loop in rt6_fill_node() Message-ID: <20260528084502.GA592092@shredder> References: <20260527053133.180695-1-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260527053133.180695-1-jiayuan.chen@linux.dev> X-ClientProxiedBy: FR2P281CA0154.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:98::9) To SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA3PR12MB7901:EE_|IA1PR12MB8311:EE_ X-MS-Office365-Filtering-Correlation-Id: 29c23e36-9e09-4b65-23ba-08debc956e7b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014|11063799006|56012099006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?00uTlB47Wy/AvOaVZiwjmStC2hPQySBZHJ9KWIm+qR2hHs0DjKVijIWf54Me?= =?us-ascii?Q?Ay1PzJHXmi3V5jiKCgoB2UswzkRMO4wSv3xardA+AIxrvLogmcqYdEouSoxm?= =?us-ascii?Q?jg0UIDErSYzv6evRRg8z3Ybxkk0D4WRpOMnE68yS0oMSLQzgkty6RndWUQqX?= =?us-ascii?Q?IkVkKYkWfQ/xGYwylR/qZGqWiDHAj1SUWg0lOqsfcmxur3wm9aXFoOY1gzS5?= =?us-ascii?Q?B0VPTpON/PrWOfdXSy82n8pRKqWo+I426KWYsJc6ksiRArEV2P4HWaYhR0yZ?= =?us-ascii?Q?/qk890/ICKtrVIgyXdQmbp68CyVQ6eQhPvZ5KsoIS4NGHpMnlJNwY8WSH7B5?= =?us-ascii?Q?9vngoxIifxh+0nc2JpmRVYEhMEKTynMTkOeECI81TcRdacbkWCo+mpsZL3ba?= =?us-ascii?Q?/0GMzpqUCbUKxeMQgWLC+qvLwp2xY/fTsRix8I5f1m5965pm8nVFs/ZkQvxC?= =?us-ascii?Q?nyHdodKx2UqYHDlTmgQHL29XDqjflaRVUFdcWQITwd9nGwh07DkR5WkMVTSh?= =?us-ascii?Q?q0FsJhHMMUqkKAF1PIdJc9NPGN2GXusA62/SbCFTBdMC8Q2octzdD8Y1mkoY?= =?us-ascii?Q?3vSlMvhwO+aoAK7AkaYCONccdLJ+RebFily80//jqHW3LG1J5lWfODp969mB?= =?us-ascii?Q?a3wgHWz367xXhxT5jtnF5aztvHFybWzaLHn+x6xo9eOhMfwQeCyOZdB4S8Qg?= =?us-ascii?Q?ssQorxU0P8+I3LIRelnxmrji7d36aq6lD29LfW0Djws9uNDJs/97AfSwCqrC?= =?us-ascii?Q?PkZDl/tensVRiyTdmUohQV971pQv3RXzANfv3QTwTSJ4klukbktbTZL+O0Ls?= =?us-ascii?Q?BXPqxnByiGvJbsqrCjPfCNKA0ayCop5+p7yaDVqKWJLGpx4bsjUjbipAYLDj?= =?us-ascii?Q?H/QheBMEckb8hEhiePCbhloCT5hudEdWH7aXALWA60lKEsPad6+HBu4gJTvJ?= =?us-ascii?Q?g5XIPx2/OSvviaZ6YHRHJ9jtP7RnmX74hqAElrB99i1c01fDrG5bB0o5LwJa?= =?us-ascii?Q?u/pvGttLfziAQ1MZs/AjX7jdvb4cxhB9flmBItGMTE6w01JwG0Xya4XkaWpQ?= =?us-ascii?Q?2IPTiyUDk5JshIN+zU/FB6Hf3/yCzq6hVvQP9icifSzeYXQmC596PupT4MNO?= =?us-ascii?Q?gHkYLNWV5aOA5Yb2Fxbrl8A4NwHlVVI/BwwRRqgXT/24WkXqNk2Ujg9PDhR+?= =?us-ascii?Q?1b5eGB5l/4xrMlz8z5f5lOaRDpW3+wmU/GpbkHQSH8AY3G4ywGviC4bl18S1?= =?us-ascii?Q?ywNc8y9YhN9SnZYSqvg+//MACOxrEeXUHfNVpJBD5yyDCvOxKuwyzaofDgSa?= =?us-ascii?Q?QJ/QXmBI9X+pv7uRYpHLQbkewXI28ACyNGDUTinLhw0d49jI5zJgxA94IKKY?= =?us-ascii?Q?30vEXbm6fUHho511wD5e+84vOzQSemTu1SeVhHtjVDA5QR4D6KSW1QmcK2mn?= =?us-ascii?Q?b6U+1/ZN53dfWQ4COQNOTdrSzrgZtHvpFy/pq0b86oe5jZ51C9o0GmNb8XVT?= =?us-ascii?Q?FrmMf6RUiwYKRXqAz93A4SJaHMn4F+tN11oPGci+YikSypR8lw0uzxE0LEe6?= =?us-ascii?Q?N71vqsVjXo4I8iK2+F1JGs4UHiFayPvwd3XAwfIqpkUT63CGfpvo8TjISoHH?= =?us-ascii?Q?NGGi0Y6NmKlyDkY0n+fto5wVZXov/o9oEm3YjlnHMUjrYsv/T3xWrWqTFxuW?= =?us-ascii?Q?Pd/iU0MimhLibuBiXaqAHN2jNupmNe3EDOKNToKcaBTHXJMUW/WaU+cLJCPl?= =?us-ascii?Q?vG8c3VUAMg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 29c23e36-9e09-4b65-23ba-08debc956e7b X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 May 2026 08:45:12.4350 (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: AJL03osrzYITPvOhrgZNg6sPb+MAxGx+1UmqC6yCe5mG80nPHUPVrz18fjcRz/qlFWcZ+KyntwfM2lI4OAd50w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB8311 On Wed, May 27, 2026 at 01:31:30PM +0800, Jiayuan Chen wrote: > Sashiko reported this issue [1]. Apply the same fix as > commit f8d8ce1b515a ("ipv6: fix possible infinite loop in fib6_info_uses_dev()"). > > Writers holding tb6_lock can list_del_rcu(&rt->fib6_siblings) > without waiting for RCU readers; rt->fib6_siblings.next then still > points into the old ring and this softirq-side walker never reaches > &rt->fib6_siblings, causing a CPU stall. fib6_purge_rt() always s/fib6_purge_rt/fib6_del_route/ ? > WRITE_ONCE()s rt->fib6_nsiblings to 0 before list_del_rcu(), so an > inside-loop check is a reliable detach signal. > > [1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev > > Fixes: d9ccb18f83ea ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn") > Signed-off-by: Jiayuan Chen Reviewed-by: Ido Schimmel Sashiko points out two pre-existing issues: 1. Same issue in nft_fib6_info_nh_uses_dev(). Fixed by: https://lore.kernel.org/all/20260526020227.4857-1-jiayuan.chen@linux.dev/ 2. Missing nlmsg_{end, cancel}() following ip6mr_get_route(). Seems valid, but completely unrelated.