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usertap kernel read faults - can I ignore them somehow?
- From: Matthew Ward <matthew dot ward at fubra dot com>
- To: systemtap at sources dot redhat dot com
- Date: Tue, 29 Nov 2011 14:20:12 +0000
- Subject: usertap kernel read faults - can I ignore them somehow?
I'm having an issue with our usertap tapset
(https://github.com/fubralimited/usertap) on a high-load server where
trying to find an IP address for a particular socket is causing
systemtap to crash out on a kernel read fault. This tapset always builds
and runs on a low-traffic server, but after testing on one of our
high-traffic nodes it sometimes builds and runs without a problem, and
sometimes refuses to build at all.
There's a gist of the error we're getting here:
https://gist.github.com/1404868. The relevant line we're getting is:
ERROR: kernel read fault at 0x0000000100000264 (addr) near identifier
'@cast' at /usr/share/systemtap/tapset/ip.stp:45:11
I presume that that file is called/included by the usertap tapset as
it's asking for the IP address associated with a socket, but this seems
to be causing an error in certain situations (presumably where it's
requesting an IP address for something that doesn't have one). Is there
any way I can tell our systemtap script to silence or ignore the call
for the IP address if that lookup fails, so that it will start anyway
like it does normally?
System info:
systemtap-runtime-1.4-6.el6_1.2.x86_64
kernel-2.6.32-131.17.1.el6.x86_64
Source code for usertap:
https://github.com/fubralimited/usertap/blob/master/src/usertap.stp
---
Matthew Ward
e: matthew.ward@fubra.com