It looks it’s a temporary bug: https://twitter.com/mpapis/status/447926386314186752.
The disable-binary option worked for me:
rvm reinstall 2.1.1 --disable-binary
EDIT – better solution
I see that some people still have this problem. Today much better solution is to update RVM like this:
rvm get stable
The problem was caused by RVM – it had some paths hard-coded into ruby binary versions. But this issue was already fixed and currently there’s no need in compiling ruby locally. All you need is to get most recent RVM version.