Mention that linux/slab.h should be included to get kmalloc/kfree.
drwxr-xr-x - 000summary
drwxr-xr-x - 00rev
drwxr-xr-x - 01intro
drwxr-xr-x - 02hello
drwxr-xr-x - 03types
drwxr-xr-x - 04char