staprun exited with status: 1

[gzcaimufu]

@agentzh hello, very glad to see your project openresty-systemtap-toolkit. Recently I use sample-bt-off-cpu to analyze the off-CPU time. sample-bt-off-cpu returns normally if no benchmark. However, sample-bt-off-cpu returns "/usr/local/bin/staprun exited with status: 1" and failed if I do benchmark with ab. Such as:

./sample-bt-off-cpu -t 20 -p ps aux|grep gas-|grep -v grep|awk '{print $2}' -u > cache.stap

WARNING: Tracing 33201 (/home/fee/dm0/gas-issue#26552-v3.10.2.6177-nolog)...
WARNING: Missing unwind data for a module, rerun with 'stap -d (unknown; retry with -DDEBUG_UNWIND)'
WARNING: too many pending (warning) messages
WARNING: Missing unwind data for a module, rerun with 'stap -d kernel'
ERROR: too many pending (error) messages
WARNING: Number of errors: 0, skipped probes: 101
WARNING: /usr/local/bin/staprun exited with status: 1
Pass 5: run failed. [man error::pass5]

Can you help me to find the reason? Thanks!!