On Mon, Oct 24, 2016 at 02:21:23PM +0200, Oleg Nesterov wrote: > > Should we do the same for perf_event_tid() and report -1 as the pid/tid > > in the !alive case? -1 should be an obvious invalid pid since we limit > > the pid-space to less than 32 bits. > > task_pid_nr_ns() is always safe, it calls __task_pid_nr_ns(). But yes, > it can return zero if called after exit_notify() and/or release_task(). > > And while zero is not a valid pid too, I guess it can be confused with > the idle thread's "pid" ?
Right, 0 is the idle thread.
