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Tejun Heo
d3e73a0808
scx_fail_parent() leaves cgroup tasks at (state=NONE, sched=parent, sched_class=ext) until the parent itself is torn down by the scx_error() it raised. When the later root_disable iterates them, two paths trip on NONE. scx_disable_and_exit_task() re-enters the wrapper at NONE: the inner switch returns early but the trailing scx_set_task_sched(p, NULL) clobbers the parent sched left by scx_fail_parent(), and scx_set_task_state(p, NONE) wastes a write on an already-NONE task. switched_from_scx() then calls scx_disable_task(), which WARNs on non-ENABLED state and writes state=READY, producing a NONE -> READY transition the validation matrix rejects. Treat NONE as "nothing to do" in both paths. Add a NONE early-return at the top of scx_disable_and_exit_task() and a parallel NONE check in switched_from_scx() next to task_dead_and_done(). Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Andrea Righi <arighi@nvidia.com>