Fix verified in lvm2-cluster-2.02.56-7.el5_5.1.
I ran 6 instances of the stress script (in comment #0 of bug 561226) for 15 min, on each of the three nodes in the cluster and never saw it hang.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2010-0432.html