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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?jd+VmTLOcBIWl/CDdRYKsWQAPZk5vx7sYGyrK7r5f8hhHurmp9Q/k7EL/B3b?= =?us-ascii?Q?LTYsqz0ooYexQkGkTeh/I2DWlek9VscB/PZhQ+JyuBRZ25kvFK8j8C54QN4k?= =?us-ascii?Q?amNjMda9J6MVxuIq5Ym/zd7XY4Eua+wZs8PDlYlC9Lw6zJ2CKqTImvDejaui?= =?us-ascii?Q?qpvfO2ftI5KTFhCgRDVQIJRQbmTFiJtvv3k6ncgwUyCcd1O8tzn3aiuu+xS6?= =?us-ascii?Q?jq04ocTsT0tb0boKyoJNoippsXNPLxCrM5i29nTVcmP7sKJHC9z0gKz4Ztpv?= =?us-ascii?Q?n2h+T5TvCokqJ9dA51AiXD83wGp3Nid6i+xY7XZJhR/yjjD3UVgtt+/70awb?= =?us-ascii?Q?u/mwe1DKoAIIAHiQZX1wrfgITA6TwmDb8ZuU6EB/1XsSgakTKiMZrkuNzxoq?= =?us-ascii?Q?Vjwp0Il+1mUeRwueDVnAI7BxokKeMi9b0NW8KactzP2hrcawsftGhKiW6M8f?= =?us-ascii?Q?XTwsuJNksIr8nAQTznWFRby533uGz0uwsZmuVi1R2e1nGbGcGKPxoWo0MC71?= =?us-ascii?Q?w8jCh+MnmZkNiqAGP/0cQd360oHjhHSt0/VzdIaZZxA5ZGNmL2XwULtlCH1m?= =?us-ascii?Q?MRk78WetZgZdzHq6hcuzOQ1dBDD4dh7cIzNiNiUnnyAUbzbxkAjttWBmFXCK?= =?us-ascii?Q?zegAX2mtwAf0dM/N2I5ecpXwVgntoHeC/CGEWti46Nco9DzEc4IOwRwVp85c?= =?us-ascii?Q?xVb665qqtXEBDqwcQ6Yf6bBORJUaIeYgBnMj5R4O9LO3RTBDgK2bAYv7uqaT?= =?us-ascii?Q?cVJQNn6BA5EnjKZrTGMloofybjcT1cle6JS4IKb6919KWNVRo2U3mfubKI49?= =?us-ascii?Q?JehGUDezhmtIurbSFftWmuH0Fm7qcDbOhRJ9WI8Qo0S61G6d2bLoYvdj8P+q?= =?us-ascii?Q?KZk0y7+r3k6hGjP6z6b/FGy71d2PlTjWgD+KDiSBMoi4wXq0zWS9hwDrRcxV?= =?us-ascii?Q?dgZe0vfDvXHMx00UEcWwwYtfbIVlmW7m+ljIjdRHOPw1OJetjPuaROMa9dsl?= =?us-ascii?Q?e87uV4J7M4ir1nLMqnCfeYpX7auL0KDlr2XOi4zyFyu8qSwjnvnosAZtcT8V?= =?us-ascii?Q?ccGRJ0Gj+7hdl7xbnTn9Y+1YyBqjGCavLRLaqGUOtPNyVaaT6keRsbUdHgC8?= =?us-ascii?Q?3HjOEr8KoClPiwNtGl01tuts9OuxZ/l05xPUPl/u6nc4PIREK0sxAAJ0Es31?= =?us-ascii?Q?ht2CM23QWN30sPSA3F42N0mDVfrGKwMdB8R3vp1ZsEbDAJ4WORsLJqhRhFBO?= =?us-ascii?Q?7H6t/No/yIoW3+LPZDDy96+xlYxJCUXPAdMyqVNUlVxY4NurKMB4/xtFBW7E?= =?us-ascii?Q?5njuriSOz9doesmMvM9CiyXv1cF6uV7FF5aoD5SpYYeYK6AFTn2P5qb4+fyz?= =?us-ascii?Q?ho6jTxqdbPhstRY/5SnlubHhS+j9KPMuDbMG9boN30nBv4whQK8NC7NoCvuf?= =?us-ascii?Q?ARTMyijLfaoVRq/BOVVgPn8dIkORQY5qlfunf7uMuXEINNs0l6tFFMjxHsKf?= =?us-ascii?Q?7Xo1v9wVnUligV83NB7iP+07LlB7BRI8eHOZFGrQpdm3K6KcZSusR8lq2vrD?= =?us-ascii?Q?O06RWJVtl1bBIx2x3Uc3xxtNQk6armuJFMIkz5cWmn5MC6Q3ra3mp3KpCdVw?= =?us-ascii?Q?1/Ze/TEy+jDOHb8yG3TdYL2IX7r+/vaUOB20ThOudNhYXOXieoNybhaNAtyf?= =?us-ascii?Q?h47SLNL6/DbvmaMAecDcBeI2IdYhE/ctDBC1axGhvIgmrM9TqJIPhz7mwt/v?= =?us-ascii?Q?c9jBlK6ijg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9e9e155f-0549-46ca-80e7-08de971c977e X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Apr 2026 16:16:59.2168 (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: A6G+kjpca120+DdgLmFzZMXsI97SxpPzg4KAMIBjYnRME3ULQ0QLh0PXcyPWORd99yrFxIXc4DAhdl//emal1g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV9PR12MB9760 On Thu, Apr 09, 2026 at 08:30:40PM -1000, Tejun Heo wrote: > sched_move_task() invokes ops.cgroup_move() inside task_rq_lock(tsk), so > @p's rq lock is held. The SCX_CALL_OP_TASK invocation mislabels this: > > - kf_mask = SCX_KF_UNLOCKED (== 0), claiming no lock is held. > - rq = NULL, so update_locked_rq() doesn't run and scx_locked_rq() > returns NULL. > > Switch to SCX_KF_REST and pass task_rq(p), matching ops.set_cpumask() > from set_cpus_allowed_scx(). > > Three effects: > > - scx_bpf_task_cgroup() becomes callable (was rejected by > scx_kf_allowed(__SCX_KF_RQ_LOCKED)). Safe; rq lock is held. > > - scx_bpf_dsq_move() is now rejected (was allowed via the unlocked > branch). Calling it while holding an unrelated task's rq lock is > risky; rejection is correct. > > - scx_bpf_select_cpu_*() previously took the unlocked branch in > select_cpu_from_kfunc() and called task_rq_lock(p, &rf), which > would deadlock against the already-held pi_lock. Now it takes the > locked-rq branch and is rejected with -EPERM via the existing > kf_allowed(SCX_KF_SELECT_CPU | SCX_KF_ENQUEUE) check. Latent > deadlock fix. > > No in-tree scheduler is known to call any of these from ops.cgroup_move(). Similarly to the ops.set_cpumask() fix maybe add: Fixes: 18853ba782be ("sched_ext: Track currently locked rq") With that: Reviewed-by: Andrea Righi Thanks, -Andrea > > Signed-off-by: Tejun Heo > --- > kernel/sched/ext.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c > index 6ca0085903e0..f7db8822a544 100644 > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -4397,7 +4397,7 @@ void scx_cgroup_move_task(struct task_struct *p) > */ > if (SCX_HAS_OP(sch, cgroup_move) && > !WARN_ON_ONCE(!p->scx.cgrp_moving_from)) > - SCX_CALL_OP_TASK(sch, SCX_KF_UNLOCKED, cgroup_move, NULL, > + SCX_CALL_OP_TASK(sch, SCX_KF_REST, cgroup_move, task_rq(p), > p, p->scx.cgrp_moving_from, > tg_cgrp(task_group(p))); > p->scx.cgrp_moving_from = NULL; > -- > 2.53.0 >