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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?N9ySjxUpYcNGcOlNKGD7HxdVS1D3Io8xIdlYcui5xRmqRyYyYcjQ57Uo6byv?= =?us-ascii?Q?Y7QfLaV3Gs6PcUzASYJ0aQvnVQDoL5G+z4+UJ0t1dM4Li3/1UWe6talHyAfP?= =?us-ascii?Q?x1uQ90hvzHP+wDEJ/x8JLVOy0l9zPaPe0AeeSwTn5Dr+B/1L4DLPCCRIMrDt?= =?us-ascii?Q?dXvM6wdiE64nfgoYN0hD4A3mw+Q57geuobg/OkCzaVgtka6v1fFyirWYsYHW?= =?us-ascii?Q?7s9UMjmYWWYpRTrJLv50rKto1lDbGGBTx0yhUSvmRoxwIhhEogmmJqasZLaM?= =?us-ascii?Q?qlVgBY9+VX3K/acc8UWpG2GTBMo6qi75huRtDRMpDdDzQxQeUzIZacUlipna?= =?us-ascii?Q?GG/EY/6yb+noZUmE7/hCwrU8mvChJZkSj855+feSVRAiNTBQk/M6zTJeMDnv?= =?us-ascii?Q?nsbyPA64FLWYA14E66UcEiEn+7WUvt4J7QKRvZm9wGx2tiy2i7oHUfg816p/?= =?us-ascii?Q?rLhLgVh+mNnVIi1BcI2DFaSQkfx8JMV2YEyMt9j+stanzboZt/c2Y+VTqzv4?= =?us-ascii?Q?x1wW4eAiHKbSJPt4+o58GHM5knPhMyqsjcfkTPINpCMd+vSf+x1UtWvUtXzV?= =?us-ascii?Q?JsTNvGlibxacsdRA7FYTdPTC35TEj9wZMiUS6EnFzdqUWp/qDS88UAvinL/N?= =?us-ascii?Q?jHOOqbUI4c65QMId3dMz8LGe/lUtvTLIwIQE8VrN+ekJrXjTWchLiJCW6aZT?= =?us-ascii?Q?7H2bD1E8PVcfFXpBts+fgMvRmDsu0K/lbwSJ0gYUPQNM7DJPw4RRFM4LtvE0?= =?us-ascii?Q?hu0bEfFYKAOq+56Zf0b9NNcUOqhaFmbhQOYZTf8bykMqTluUsfyWw7t2pAei?= =?us-ascii?Q?BR5XDGrpqQD1L3lgc8M5L0yXOH3Dn2FysxskMMZylZlGhh0czljYAamlcXOh?= =?us-ascii?Q?kClTrw8BHPPcvIfxI1s/Kx58uG2jJkAKJvYsczklqkquM1PAqqHyX7i1AzE1?= =?us-ascii?Q?24ZRz5ItqAdID6sunfj5EqoZZOolpde5tlRUsES26f1X+OGMfmT4jvXddOwd?= =?us-ascii?Q?50jpZSdl0bAmXCbkeJE98tYt//Ucar5m8befB6qAENDOB4QO/Ih8iKEPmQMR?= =?us-ascii?Q?N6QbMq8CmfOCHxtDl7flW0QyQorqL2gn0RTlsPd5driy2PyyUWZ9G6pHAMNu?= =?us-ascii?Q?dqj9pDvz+2ghyBjq3TdwnvtXYvexdMU50NkXslR6QccoqIZ3t+e1TuArxtD/?= =?us-ascii?Q?t0iBvZq8WZuy+FjIYcYqrsludsnERrZgeu7hz+G1LvYlifxnbrWzRBgQEdWI?= =?us-ascii?Q?2AkCy4aVyvPriW/wBx2IExMNghsvGUntaBbYXVsmmd60wtpL6ysnS21/8mOV?= =?us-ascii?Q?ZIHps0ErvL3+T0YcMgwwpk4nuCi1Dcuw01sofL96TWFbQibmOQ+oGi2xoqvC?= =?us-ascii?Q?PRybnq+9Sq0UH22JvUYeCYhuLQiQX1R2xE/TiNRCzxc7zDHTQ/yeoa2UR1UR?= =?us-ascii?Q?Hlj0vbGnHcKnj/mwgnTX0ErnCyaZriA6Vu0MG8wIPbOvK7QqzGKgCtoDscia?= =?us-ascii?Q?Oe4zfIGbVskrxvHgpX0PjGZ3an000znq7P0BQYZ/QM06Ah87TKRI0aaxALx+?= =?us-ascii?Q?mGYmEJ7Lgs1Rb312yXRO8kfvsScN4G6fDaAac6vJhPVRk4S9gkK4Ndr1ZxAl?= =?us-ascii?Q?QZ6RAcb+XmmAISqtprFbk1rhtLIstKwsNqRYIeY9eTAzWZSGPZzEhIPKc3Lz?= =?us-ascii?Q?D/nL3v2MbtNjdLrytlLc8Y0+brMN+iuFAn+/WAK+P4FGrCbKMwqXNG3B38Zw?= =?us-ascii?Q?L0YYNST8lQ=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: dc212f96-000e-4999-6a27-08de7e7149ae X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Mar 2026 06:50:16.7482 (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: P4ReD/Xg+AQHHh5mXf1sfkBag8q5GXVzkWeJ9XBdX87RmyjABeknQBr7BPKRH2DbY1GRYLN5BtZNc8zOdelc5w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB8007 On Mon, Mar 09, 2026 at 03:16:48PM -1000, Tejun Heo wrote: > Hello, > > Cheng-Yang reported a lockdep circular dependency between scx_sched_lock and > rq->__lock. scx_bypass() and sysrq_handle_sched_ext_dump() take > scx_sched_lock -> rq lock, while scx_claim_exit() (reachable from many paths > with rq lock held) takes rq -> scx_sched_lock. In addition, scx_disable() > directly calling kthread_queue_work() under scx_sched_lock creates another > chain through worker->lock -> pi_lock -> rq->__lock. > > This patchset fixes these issues: > > 1. Fix wrong sub_detach op check. > 2. Add scx_dump_lock and dump_disabled to decouple dump from scx_sched_lock. > 3. Always bounce scx_disable() through irq_work to avoid lock nesting. > 4. Flip scx_bypass() lock order and drop scx_sched_lock from sysrq dump. > 5. Reject sub-sched attachment to a disabled parent. > > Tested on three machines (16-CPU QEMU, 192-CPU dual-socket EPYC, AMD Ryzen) > with lockdep trigger tests and an 11-test stress suite covering > attach/detach, nesting, reverse teardown, rapid cycling, error injection, > SysRq-D/S dump/exit, and combined stress. Lockdep triggered on baseline, > clean after patches. With the comment from Cheng-Yang about fixing the link in patch 4/5. Reviewed-by: Andrea Righi Thanks, -Andrea