RBAC and memory usage

[Undine]

I found that RBAC-enabled kernel reserves much more memory (on my system with 2G ram it is about 150-170M according to dmesg). On non-RBAC and vanilla kernels this value is small, giving to applications almost all RAM available on the machine (about 2007M). Now I have only 1885M for daily usage. This is normal if RBAC enabled? Thanks.
P.S. This is not a bug report and not any attempt to fix this. I only want to know it is normal or I misconfigured my kernel.