Ask HN: Best book to understand modern Linux from top to bottom?

Tannenbaum's book is one of best authors on OS design, but he tells nothing about modern Linux. But you may find interesting a dialogue between Tannenbaum and Tolvalds as a read about kernel internals.

Networking is a different world for OS learner, nothing in common.

Filesystems usually have a documentation, just read it for every FS you need.