[CentOS-virt] Updated kvm kernael and now some guests are hung

James B. Byrne

byrnejb at harte-lyne.ca
Wed Feb 1 03:02:34 UTC 2012

Earlier this evening I updated our CentOS-6.2 kvm virtual
host to kernel 2.6.32-220.4.1.el6.  After rebooting three
guests are hung.  I cannot establish connections via the
network (no route to host) and the virtual console is
unresponsive.  On two of them I was able to initiate the
login process but after the password prompt the system no
longer responded.  On the other the system hung when I
tried to run the vi editor.

The console display on each of the affected guests shows a
long list of hung tasks:

task jbd2/dm-0-0:384 blocked for more than 120 seconds
.  . .
task jbd2/dm-3-8:838 blocked for more than 120 seconfs

task master:1226 blocked for more than .  .  .

task miniserv.pl:1248 blocked

task pickup:29136 blocked

The lists on each guest vary somewhat but share most of
the same processes being blocked. One has a postmaster
task that does not display on any of the others.

I can recover from this but I want to get these guests
restarted if I possibly can.  Is there a way to do this? 
What would cause the problem?

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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
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Hamilton, Ontario             fax: +1 905 561 0757
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