Using the `geometry` package with luatex

As with graphics and color it is usually best not to specify a driver at all and let the system detect what you are using. Unfortunately however geometry has not been updated to luatex 0.85 and later so you need to use

\RequirePackage{luatex85}

as the first line of the document to offer a compatibility layer, geometry will then work using the pdftex driver files.

luatex85 is no longer required with geometry 2018/03/24 v5.7

Adding to David Carlisle's answer, I found that I can get geometry to work with the latest LuaTeX (1.0.4) as long as I also use one of graphicx or color / xcolor.

Perhaps these packages detect the luatex driver so that geometry doesn't have to? I'm not expert enough to say, but that's my guess.