Hello all
continue to study the scheduler is O(1) there was one difficulty with the string 2 on 3, in that these blocking occurs after lines?
a reference to the code that study - http://lxr.free-electrons.com/source/kernel/sched.c?v=2.6.36
what I learn on line 4682 to 4695.

1  rcu_read_lock();
2   pcred = __task_cred(p);
3   match = (cred->euid == pcred->euid ||
                     cred->euid == pcread->uid);
4   rcu_read_unlock();

I ask because in the comments there is not described.
Thank.