You should DO it rather than just read it.
There is a great way to DO it first hand with fun.
Follow eudyptula challenge. Just got to eudyptula-challenge.org and do what they say. There are 20 tasks. After solving them you will not only know about kernel, but you would have done things with linux and kernel.
They says that they are using script to verify your drivers during challenge tasks, but I highly doubt it due to humorous and funny responses I get from them!