Systemtap will error when attempting to attach to a resumed process. This happens with "fake" utrace (seen on RHEL7 and f20).
 
====
# stap -v -e 'probe syscall.getpid { printf("%s\n", probefunc()) }'
<snip>
Pass 5: starting run.
sys_getpid
<snip>
ERROR: utrace_set_events returned error -114 on pid 1903
WARNING: /usr/bin/staprun exited with status: 1
Pass 5: run completed in 0usr/70sys/8196real ms.
Pass 5: run failed.  [man error::pass5]
====

Here's how to reproduce this one:

1. Compile the following C code to 'a.out'.
====
#include <unistd.h>
#include <signal.h>
 
void main()
{
    kill(getpid(), SIGSTOP);
    getpid();
}
====
 
2. Run 'a.out' in the background.

# ./a.out &
[1] <pid>
 
3. Execute stap command in another console.
# stap -v -e 'probe syscall.getpid { printf("%s\n", probefunc()) }'
 
4. Resume the stopped process
# kill -cont <pid>

Sometimes the stopped process can get stuck in the 't' state till
kill -9'd.