echo 0 > events/enable
echo > kprobe_events
-echo 'r:testprobe2 do_fork $retval' > kprobe_events
+echo 'r:testprobe2 _do_fork $retval' > kprobe_events
grep testprobe2 kprobe_events
test -d events/kprobes/testprobe2
echo 1 > events/kprobes/testprobe2/enable