On Mon, Feb 12, 2007 at 11:46:20AM -0800, Paul Menage wrote: > On further reflection, this probably would be safe after all. Since we > don't call put_container_group() in attach_task() until after > synchronize_rcu() completes, that implies that a container_group_get() > from the RCU section would have already completed. So we should be > fine. Right. Which make me wonder why we need task_lock() at all ..I can understand the need for a lock like that if we are reading/updating multiple words in task_struct under the lock. In this case, it is used to read/write just one pointer, isnt it? I think it can be eliminated all-together with the use of RCU. -- Regards, vatsa