Unfinished: Big Kernel Lock removal

The BKL is a holdover from 2.0
Controlled access to the kernel
Made early SMP support possible

The BKL is little-used now
Fine-grained threading is the rule
Lockless algorithms used when possible

It lives on, however:
ioctl() methods (and others)
Much of /proc
RPC daemon
Core dumps
File locking
Various drivers

In 2.7, the BKL could finally die
...maybe