This book is great, I'm really enjoying it. However I find that sometimes it takes too much pain to annotate the source code itself, rather than the ideas behind the code. This comes at the expense of being pedagogical and directing the reader's attention to the interesting bits where the mechanics happen.

For example, anyone who is reading this will understand that the kernel does lots of checks for null pointers and other errors here and there. Why not just skip over the mundane descriptions of IS_ERR() and PF_NPROC_EXCEEDED?

Brilliant; Helps you to write better quality code for your apps;