Messages in this thread | | | Date | Mon, 24 Oct 2016 14:29:42 +0200 | From | Oleg Nesterov <> | Subject | Re: hit a KASan bug related to Perf during stress test |
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On 10/24, Peter Zijlstra wrote: > > On Mon, Oct 24, 2016 at 02:10:31PM +0200, Oleg Nesterov wrote: > > --- x/kernel/pid.c > > +++ x/kernel/pid.c > > @@ -526,8 +526,11 @@ pid_t __task_pid_nr_ns(struct task_struc > > if (!ns) > > ns = task_active_pid_ns(current); > > if (likely(pid_alive(task))) { > > - if (type != PIDTYPE_PID) > > + if (type != PIDTYPE_PID) { > > + if (type == PIDTYPE_TGID) > > + type = PIDTYPE_PID; > > task = task->group_leader; > > + } > > Aah, that makes much more sense ;-) > > > nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns); > > } > > rcu_read_unlock(); > > > Still, I wonder if returning 0 is the right thing. 0 is a 'valid' PID > for the init/idle task.
Yes, now I think that -1 would make more sense. Unfortunately we can't just change __task_pid_nr_ns(), it already has the users which assume it returns zero... attach_to_pi_state() for example.
> And we still have the re-use issue for the TID, because when we get here > TID is already unhashed too afaict,
Yes, so perf_event_tid() will report zero.
Oleg.
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