[$] Two topics in user-space access

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