Red Hat Bugzilla – Bug 444236
snmpwalk spikes cpu if IPv6 disabled on X86_64 RHEL 5.2Beta
Last modified: 2008-04-28 11:35:23 EDT
Description of problem:
If you have disabled ipv6 on RHEL 5 x86_64 via the modprobe.conf, running
snmpwalk -v2c -c community 127.0.0.1 will spike a single CPU.
Version-Release number of selected component (if applicable):
This is applicable to every release of net-snmp since 5.1 ISOs were released.
The lastest version I have tried is is in the RHEL 5.2 Beta channel.
Steps to Reproduce:
1. Run RHEL 5.1 or newer x86_64
2. Disable IPv6 via the modprobe.conf
4. service snmpd start
5. snmpwalk -v2c -c community 127.0.0.1
6. Look at top output, watch a CPU sit at 100%
I have included attachments for the commands.
Not having 100% spike while snmpd is running.
It appears to be happening on at least these MIBS
I have included the following:
I also tried to rebuild the SRPM disabling Ipv6, but the build fails. I am not
sure if that is considered a bug though.
It appears that this bug isn't new. Google told me it's been happing in Centos
4, and 5 also.
Here's a link with some information from the CentOS crew.
Created attachment 303824 [details]
This is a slightly sanitized version of our snmpd.conf
Created attachment 303825 [details]
The output of snmpwalk (not straced anything)
Created attachment 303826 [details]
The output from top showing a cpu is 100% used
Created attachment 303827 [details]
strace running with snmpwalk
Created attachment 303828 [details]
And a bit of /var/log/messages
I see the same bug. Additionally, snmpd must be restarted after a snmpwalk of
the server to get snmpget's or walks working again.
Some people have reported this is a xen kernel issue, but this happens for us on
It should be already fixed in RHEL 5.2. It has nothing to do with xen and it
happens only with RHEL 5.1 (I've added a buggy patch there).
*** This bug has been marked as a duplicate of 431977 ***
This is not fixed in the currently released net-snmp inthe RHEL 5.2 beta channel.
I have the latest net-snmp installed that is available in RHN.
If there is a fix, could you direct me to the link? The other bug says proposed
for RHEL 5.3. I would like a fix before 2009.
it was fixed after beta, in net-snmp-5.3.1-23 to be precise. And the bug has
been evaluated as important enough to fix it in 5.2.
You can find test build at http://people.redhat.com/jsafrane/bugs/444236/
Thank you very much for a prompt response. Everything working just fine.