stap blocked (at stapio)

[Peter Teoh]

stapio:send_unwind_data:64 module sd_mod
stapio:get_module_unwind_data:52 module sd_mod returns 3896
stapio:send_unwind_data:64 module sg
stapio:get_module_unwind_data:52 module sg returns 3288
stapio:send_unwind_data:64 module sky2
stapio:get_module_unwind_data:52 module sky2 returns 4416

When running many of the stap scripts, it blocked here as above.  What
are the possible reason?   This is git-updated up to latest.
(8a49d1d23c77033bf98fc7b139b37f83e3e0eb49).

This blocked:

probe kernel.function("schedule")
{
printf("Called %s\n", probefunc());
print_backtrace();
}

But not this:

probe begin
{
  print ("hello world\n")
  exit ()
}

and the latter executed fine.

-- 
Regards,
Peter Teoh