This bug has been copied from bug #771592 and has been proposed to be backported to 5.6 z-stream (EUS).
in kernel-2.6.18-238.35.1.el5 linux-2.6-block-disable-sg_io-ioctls-on-virtio-blk-devices.patch
According to comment7,set this issue as verified.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2012-0358.html