Reference counting is the low-end of automatic memory management and garbage collection.

And about GC in kernel, of course you can. The issue is that most efficient GC needs giant locking and giant locking in kernel is something that you don't want.

In fact you can really live without GC. The burden of integrating it in kernel space out-range the benefit of using it.

Funny, because Windows uses reference counting on the Kernel.

http://technet.microsoft.com/en-us/sysinternals/bb963901