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60f21a2649
a72f73c4dd("cgroup: Don't expose dead tasks in cgroup") made css_task_iter_advance() skip exiting tasks so cgroup.procs stays consistent with waitpid() visibility. Unfortunately, this broke scx_task_iter. scx_task_iter walks either scx_tasks (global) or a cgroup subtree via css_task_iter() and the two modes are expected to cover the same set of tasks. After the above change the cgroup-scoped mode silently skips tasks past exit_signals() that are still on scx_tasks. scx_sub_enable_workfn()'s abort path is one of the symptoms: an exiting SCX_TASK_SUB_INIT task can race past the cgroup iter leaking __scx_init_task() state. Other iterations share the same gap. Add CSS_TASK_ITER_WITH_DEAD to opt out of the skip and use it from scx_task_iter(). Fixes:b0e4c2f8a0("sched_ext: Implement cgroup subtree iteration for scx_task_iter") Reported-by: Cheng-Yang Chou <yphbchou0911@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>