sendmail function probe registration error with systemtap

[Xiaokui Shu <subbyte at gmail dot com>]

Hello everyone,

I am using systemtap to trace function calls of a running process. It
works well with small programs, e.g., grep. However, I run into an
issue with "sendmail". When I start systemtap with a simple probe
(shown below), I get two warnings in Pass 5. While running systemtap,
I can send emails to the monitored host, but my mailbox on the host
does not receive them. Only after I shutdown systemtap, the emails are
coming to /var/mail/xxx. When running systemtap, after sending several
emails, sendmail seems to be blocked, and all TCP connections to 25
port is rejected. After I shutdown systemtap, sendmail works again,
and the port is open.

Can anyone help me to figure out what is the problem brought by the tracing?

Thank you very much!

######## systemtap running log ########
Pass 1: parsed user script and 102 library script(s) using
32296virt/18852res/2588shr/16968data kb, in 280usr/10sys/297real ms.
Pass 2: analyzed script: 947 probe(s), 12 function(s), 3 embed(s), 0
global(s) using 41316virt/27460res/4520shr/23536data kb, in
210usr/160sys/369real ms.
Pass 3: using cached
/root/.systemtap/cache/56/stap_560093aa0c2089c2c95856502772a700_258364.c
Pass 4: using cached
/root/.systemtap/cache/56/stap_560093aa0c2089c2c95856502772a700_258364.ko
Pass 5: starting run.
WARNING: probe process("/usr/sbin/sendmail.sendmail").function("mime_getchar_crlf.part.1")
inode-offset 0005e620 registration error (rc -524)
WARNING: probe process("/usr/sbin/sendmail.sendmail").function("frame_dummy")
inode-offset 0001cc80 registration error (rc -524)

######## trace.stp ########
probe process(@1).function("*")
{
    printf ("%s:0x%x\n", probefunc (), ustack (1))
}

Best,
Xiaokui