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

On 03/03, Eric W. Biederman wrote:

Oleg Nesterov [off-list ref] writes:

quoted

quoted

@@ -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.