[$] Two approaches to tightening restrictions on loadable modules

The kernel's loadable-module facility allows code to be loaded into (and
sometimes removed from) a running kernel. Among other things, loadable
modules make it possible to run a kernel with only the subsystems needed
for the system's hardware and workload. Loadable modules can also make it
easy for out-of-tree code to access parts of the kernel that developers
would prefer to keep private; this has led to many discussions in the
past. The topic has returned to the kernel's mailing lists with two
different patch sets aimed at further tightening the restrictions applied
to loadable modules.