On 07/20, Jiri Slaby wrote: > > You tackled it, we cherry-picked dbfb089d360 to our kernels. Ccing more > people.
Thanks... so with this patch __schedule() does prev_state = prev->state; ... if (!preempt && prev_state && prev_state == prev->state) { if (signal_pending_state(prev_state, prev)) { prev->state = TASK_RUNNING; } else { and ptrace_freeze_traced() can change ->state in between. This means that this task can return from __schedule() with ->state != RUNNING, this can explain BUG_ON(task_is_stopped_or_traced) in do_notify_parent() you reported. Oleg.