It sounds like there may be a generic bug with "ret" instructions. These
are handled specially. It would be best if you could construct a test
(e.g. write a test module that inserts kprobes on test code you provide in
that same module) where you can figure out exactly what happens when the
probe should be executing the return. That is, where you know exactly
where you should have gone after that (perhaps you can do this by having
another probe at the proper return location), and ideally figure out where
you actually went instead (or if the problem is different from that
e.g. the stack contents being wrong).