With over 10 Million Lines of Code and additions plus changes everyday, it would be a little tough for any one person to really grasp it. Even Microsoft contributed 20,000 lines of code to the kernel after they got caught hijacking the Hyper-V network drivers. There is a map here: http://en.wikipedia.org/wiki/File:Linux_kernel_map.png

"Robert Love's "Linux Kernel Development"

yes. its a good one

Some part understanding kernel or a code walk of kernel is also possible with any good professional IDE application.

So if you think using a open-source IDE, you can try using Bluefish, I use it to develop my open-source kernel project. Before that, I used to manage via Vi or via Gedit applications, but now the best IDE, is paying off really well both interms of understand (code walk), and even kernel software development.

And regarding suggested books, certainly you can read kernel specific books, but beyond that kindly read the intro sections of Linux Device Drivers (LDD) Book. It is too useful for you to understand simple kernel APIs, code, modules specific to each subsystem i.e networking, filesystem, memory, etc.

http://www.youtube.com/watch?v=n9QgKo5ogg4

I made this video on using Bluefish IDE to understand my TrafficSqueezer code. Actually it is a part of Linux Kernel.
It is for my students to understand Linux Kernel code + my code/modules in it.
Hence you can use such IDE or Netbeans IDE, or any such IDE to go through the Kernel sources.

Sometimes please note each folder you see in Kernel can be a
module or sub-modules,
subsystems - such as filesystem, networking, etc,
device drivers, and so on.

Hence use a good IDE, and preferrably O'Relly series books also mainly LDD book.

I hope my video helps you too.