Re: systemhang

[Mark Wielaard <mjw at redhat dot com>]

Hi Hans-Peter,

On Mon, 2009-03-30 at 13:42 +0200, Sloot, Hans-Peter wrote:
> I have created a small script to see what functions as certain process
> calls.
> 
> probe kernel.function("*") {
>        if (pid() == target()) {
>                 printf("function name : %s ", pp())
>        }
> }
> 
> Whenever I start stap with the script below  as follows 
>  stap -v -x <pid>  function.stp
> 
> The system starts to hang.
> 
> Any clues what is wrong?
> My script ? 
> A systemtap bug?

stap should never hang your system, so it is a bug in systemtap (or a
bad interaction with you specific kernel). kernel.function("*") matches
very many things (all function calls, whether inlined or not). You might
want to start with something more more constrained to see if the basics
work. On my system it seems it doesn't even want to register all those
probes, since I get a registration error. Try something like:
stap -v -x <pid> -e 'probe syscall.* {printf("syscall: %s\n", name)}'
Should already give you lots of output to start with.

You could help us narrow it down by providing some of the information
discussed at http://sourceware.org/systemtap/wiki/HowToReportBugs
Systemtap comes with a stap-report program that provides most of that
info.

Thanks,

Mark