Warnings that occur during pass 5 (execution) can have a variety of causes.
- probe insertion errors
With any of the systemtap runtimes, it may be possible that the backends are unable to insert probe points requested by the systemtap script. For example, you may see errors such as
WARNING: probe [...] registration error (rc -524)
(524 is a kernel error code for ENOTSUPP). These situations are out of systemtap's control, and result in some probes not receiving any hits. This may be caused by temporary resource constraints or permanent problems. One common permanent problem is such a probe point being placed at instructions that the runtime (kernel kprobes, uprobes or dyninst) cannot decode or intercept. A possible workaround is to move the probe points slightly in the script, so as to target a nearby statement, or a caller, or a callee. See also error::dwarf(7stap).
Gathering More Information
Increasing the verbosity of pass-5 with an option such as --vp 00001 can help pinpoint the problem.
stap(1), http://sourceware.org/systemtap/wiki/TipExhaustedResourceErrors, error::pass5(7stap), error::reporting(7stap) error::dwarf(7stap)