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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?9Fi2UREew4xSi2ui/8fN6qo/RoVrPV+EBO1Vi/tox9fDZMQJOBUY9ELUW2gl?= =?us-ascii?Q?R2Zf6fIZr1xntBxZjrYh6vWorL++KmjbuNMElM8xnXmkXNrCUSFmcbCyBvCF?= =?us-ascii?Q?mtzieGIYSK7FCf9PKsKunkOdXE86bOvMfb4G+EENOMe+MIiiBWt+W3GLHVB1?= =?us-ascii?Q?XZt9wLTRdaDloEsObXmrjv4nBIQqtBPWudvbs2w00HaEi83iksRAI2pO3c/H?= =?us-ascii?Q?X2V5nUKEEPwo/MaPE7TBwc911Xye2VBMCxRJ4wmWPSfQ0PvbYCs6gHJRab1n?= =?us-ascii?Q?xwTIQsiZx2ppRT18RD8MtUSYeq7sro0YcXLnXo7bs0D0eKwSZ8NlREY8ANZy?= =?us-ascii?Q?tJURK7rVw4JEEtPnRPB+I65MnPtvghj5SY7aFR447dGh4ZUinjIA7il7jZvK?= =?us-ascii?Q?Ke8zVPdV04jKb58Ixwspr+sei3ln2XjMn+OCvdSJC4icaAFCskpzD+tr+Z5v?= =?us-ascii?Q?EZsw8hWeXNG7XQ4f36CHZ+ffoqhFcA1CWsyoWy16QUn3LIjvZJ8kRgUeP8UL?= =?us-ascii?Q?5Z6lK88jLp+fQ4VV2DBmFnSPSmMrbPcJte6Na1b5pY6Dftu4iFTQHY4TFfq0?= =?us-ascii?Q?3cgrnydFW09CX/uhcg24OJ1lrRznJImYi+UDbPcGzAGuXNfBqlUtM7BuXMML?= =?us-ascii?Q?SNksWyfv1CkOAj1RkrKkk9sEyLKy5y2aiiexn49RW5y1D7qXzsX5DyaPjKbS?= =?us-ascii?Q?EIqNdIXAUWdS8dVNS2EZ+TwvdzOb6HB8zYUNwsVF14gWqNsZtIE1w20quPbr?= =?us-ascii?Q?oQ3ejjFzkRIkZFm3IkRlSLOdMPgdnmBuCCAl8bRrEz06pfyzKE7zfGV4F4DU?= =?us-ascii?Q?g4+Hgp4IIKhDG6ynYLYfcJ0iIhc2KSF4vnpZDfkKnggXWG+M5rT4TQr2YGD5?= =?us-ascii?Q?7FXqHyKHM4V/U7qWG5hNm6xQJIHzlP4LJn6Cft3w3Xi/8cAHuIFqXX/A70nE?= =?us-ascii?Q?4stEopWTSf+uyIskqggnPYE6mBeke/2eWz9MDcM7DvmQzmFydIbaQqNh7x8h?= =?us-ascii?Q?rba34Btf7GdU+EzmYl5j/Jro3a/j/ux7UF6zH4dl3SRkBBmKF2uQ5M2wBg29?= =?us-ascii?Q?ZbKrAyVodUuWtkeRQABhX3EyYpEQp/GmRkC7TiiDqBlx5Dq4GT6ozsl45x/p?= =?us-ascii?Q?TW9xhLnT7dN8f6QofndfuscAi65Iw4DXFMv7Z9MBZcSUfNwFi7n4XdwgqlI4?= =?us-ascii?Q?QM4THEhoG6PSaJpx85PEEGsR0K1s1qh7LcALzsHcTbSS5aAtf1ak3TSKE+DK?= =?us-ascii?Q?g4plM71qC28i5wb/5HwTdB1SuP/tum1xKoqRnCr8NtrBdBg68CHIk4AysqNu?= =?us-ascii?Q?8rZG4ZSIK7i9e8g/GGc/0Go0RZBypj8AM3Lnh4iHYR+GBoDNmGYWQqtuMUnt?= =?us-ascii?Q?BW4lxWsJYrORWMbkD0XdGMSyh99XYywyc2vSXXtsnG/yFlz0w/UJf97/xiDr?= =?us-ascii?Q?mzZ1io/bdoiutghdkgoXe6BZCZIejIwzfIBHoqqNiDuuRXbFv23uLW48+D0I?= =?us-ascii?Q?VxW1vM81V918J/g3US4GoFJAKt79Iixuf93zVEAdPx0Z5hyNlM0PD/jggljT?= =?us-ascii?Q?KXmriARUCbgta9V4/mzcVYmuQqkukIismUUj21vb?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ecb33732-c1a0-4d15-c15f-08ddeb2b35a8 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Sep 2025 20:48:17.4614 (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: UrnCLvf2yAMp/Zz+WFb63PSNE6Y/vQkTYTDKO2Je7qaAA0V9MJ91zZDoYbL/pDFaTTa5E6WVxtsoKET7TItWwQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8978 On Wed, Sep 03, 2025 at 06:39:46AM -1000, Tejun Heo wrote: > Hello, > > On Wed, Sep 03, 2025 at 02:44:58PM +0200, Andrea Righi wrote: > > > static void scx_cgroup_lock(void) > > > { > > > - percpu_down_write(&scx_cgroup_rwsem); > > > + percpu_down_write(&scx_cgroup_ops_rwsem); > > > + cgroup_lock(); > > > } > > > > Shouldn't we acquire cgroup_lock() before scx_cgroup_ops_rwsem to avoid > > a potential AB-BA deadlock? > > There's no existing ordering between the two locks, so any order should be > safe. The reason why I put it in this particular order is because any > cgroup_lock() holder has no reason to grab ops_rwsem now or in the future > while the opposite direction is still unlikely but theoretically more > possible. Isn't scx_group_set_weight() called with cgroup_mutex held? In this case the order is cgroup_lock() -> scx_cgroup_ops_rwsem, or am I missing something? Thanks, -Andrea