Systemtap hangs target task?

[rmhartman]

I _think_ systemtap is locking up the target task.
I am probing both .call and .return on a target user task e.g.

probe process("mytaskname").function("*").call

I am keeping count of how frequently various functions are being called.

I have a timer every 2 seconds generating a report, and an end function generating a final report when I ctrl-c out

But ... sometimes the target task appears to get hung up. Hung so badly that a kill -9 won't even kill it. And it appears that a probe task is stuck as well:
# ps -aef | grep stap

root 25435 1 0 Dec21 ? 00:00:24 /usr/libexec/systemtap/stapio -u/tmp/stapbqH2rI/uprobes/uprobes.ko -R stap_f31ebf1dac687ed521b27e27b05f7a6a_1_25435 -F3

So ... is it possible that the ctrl-c is sometimes not being handled properly, and stap leaves the probe stuck in as it were, hanging the target process so badly that it can't even respond to a kill -9 ?

Has anybody run across a similar problem with systemtap before