The article suggest reading code, which I agree is a good way to improve programming skills. But I'm a bit unsure what to do with the advice to read the linux source code. Where would you start? I find the only way to actually get to reading code, is if you have a need to understand some part of it (e.g. to fix a bug or add a feature).

So perhaps a more actionable proposal is to try to fix a bug, preferably one you care about, in some open source project.