Please note that you'll need the followup patch for the Xen kernel as well. That was just posted, and should be integrated into the 5.5 kernel soon.
Chris Lalancette
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/RHSA-2010-0380.html