Jan 062016
 

The kernel development community is organized as a hierarchy, with
developers submitting patches to maintainers who will, in turn, commit
those patches
to a repository and push them upstream to higher-level maintainers. This
hierarchy logically looks a lot like the directory hierarchy of the kernel
source itself; most maintainers look after one or more subtrees of the
kernel source tree. But does that model really describe how patches make
it into the mainline? The kernel’s git repository, with the aid of some
scripting, holds an answer to that question.
[$] How 4.4's patches got to the mainline
Source: LWN.Net