Re: hit a KASan bug related to Perf during stress test

[Peter Zijlstra]

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.