On Tue, Oct 25, 2016 at 04:41:26PM +0200, Oleg Nesterov wrote: > > > > So what serialization would close that race? __task_pid_nr_ns() only > > seems to use RCU nothing more. > > I do not see how can we close this race, we obviously do not want to use > any locking. > > That is why I tried to suggest > > nr = __task_pid_nr_ns(p, type, event->ns); > if (!nr && !is_idle_task(p)) > nr = -1; > return nr; > > but this will report -1 if p runs in another namespace, so perhaps we > can do > > nr = __task_pid_nr_ns(p, type, event->ns); > if (!nr && p->exit_state) > // it has already called exit_notify > nr = -1; > return nr;
I think I'm asking how __task_pid_nr_ns() isn't susceptible to this race ;-)
