Was J.R.R. Tolkien a racist?

Or just a huge fan of Norse Mythology? I mean, I don't think he ever describes the Dwarf's skin pigmentation, but all his Men, Elves and Hobbits are very fair. And in "Return of the King" Mordor is aided by "Dark men from the south". And there's a lot of talk about the "True West". So was it just an effect of being a British Catholic humanities professor, or was he really a racist?