It looks like your libdrm, mesa and the radeon driver do not match. Most likely, your libdrm is too old.
Are you using the default drivers that come with Ubuntu, or did you install newer ones from one of the external repositories? This might be a good idea to do anyway, due to the rate of improvement of the drivers.
There are relatively easy ways to do this for your specific distribution (Ubuntu), but since I don't use it, somebody else will likely have better advice.
There is a "standard" way to install experimental software from source, but you should stick with the standard services provided by your distribution for the time being, and save yourself some headaches.