Funny reply from Linus,
A note on this: this is a project by various mad Russians to perform c/r mainly from userspace, with various oddball helper code added into the kernel where the need is demonstrated... However I'm less confident than the developers that it will all eventually work! So what I'm asking them to do is to wrap each piece of new code inside CONFIG_CHECKPOINT_RESTORE. So if it all eventually comes to tears and the project as a whole fails, it should be a simple matter to go through and delete all trace of it.