There shouldn't be a way to interrupt an atomic operation, because then it won't be atomic.
An interruptable atomic is basically a transaction that can be rolled back. If it gets interrupted nothing is changed. Probably doesn't make sense to run it from anywhere but kill-thread and similar operations.
To restate my original point: reasonable semantics for atomic are that threads inside atomic can't be killed. How to kill long-running atomics is a separate issue, needing a lot more engineering.
