Re: [PATCH 0/2] fix the traced mt-exec deadlock

[Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 03/03, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> writes:
>
> >> @@ -699,8 +701,6 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
> >>  	}
> >>
> >>  	tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
> >> -	if (tsk->exit_state == EXIT_DEAD)
> >> -		list_add(&tsk->ptrace_entry, &dead);
> >>
> >>  	/* mt-exec, de_thread() is waiting for group leader */
> >>  	if (unlikely(tsk->signal->notify_count < 0))
> >> @@ -711,6 +711,8 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
> >>  		list_del_init(&p->ptrace_entry);
> >>  		release_task(p);
> >>  	}
> >> +	if (autoreap)
> >> +		release_task(tsk);
> >
> > These 2 changes are not needed. release_task(tsk) will be called by
> > list_for_each_entry_safe() above if autoreap == T.
>
> Except for the practical case that for threads that are ptraced
> tsk->ptrace_entry is already in use.  Which means we can't use
> list_add(&tsk->ptrace_entry, &dead).

Yes, I was wrong here, thanks for correcting me.

Oleg.