[$] Two topics in user-space access

Kernel code must often access data that is stored in user space. Most of
the time, this access is uneventful, but it is not without its dangers and
cannot be done without exercising due care. A couple of recent discussions
have made it clear that this care is not always being taken, and that not
all kernel developers fully understand how user-space access should be
performed. The good news is that kernel developers are currently working
on a set of changes to make user-space access safer in the future.