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> list_del_init(&event->child_list); > + /* > + * Cannot set to NULL, as that would confuse the situation vs > + * not being a child event. See for example unaccount_event(). > + */ > + event->parent = EVENT_TOMBSTONE; This will cause issues where we do `event = event->parent`. No? For ex: perf_pmu_unregister() ... perf_event_exit_event() perf_event_wakeup() ring_buffer_wakeup() if (event->parent) event = event->parent; Thanks, Ravi