Checkpoint/restart (mostly) in user space

The best way to implement checkpoint/restart seems to me to first write something that works in userspace using the current kernel, and have it use the additional kernel information exposed by submitted patches if available.

For example the tool could initially just read /proc/maps and hope there aren't any pathological issues, and then be enhanced to use /proc/mfd to be actually fully correct.

Then, just submit a ton of small patches that add new generally useful query/set (and atomicity) interfaces, which coincidentally happen to be those needed for more accurate checkpoint/restart.