Description of problem:
When the daemon of xend stops ,the cron task who is /etc/cron.hourly/mcelog.cron can't read /sys/hypervisor/uuid.It leads to D status of "cat /sys/hypervisor/uuid " which results in high load average 

Version-Release number of selected component (if applicable):
In RHEL5.4 for 64 bits x86_64 xen kernel.

How reproducible:
In xen kernel,make the daemon of xend stop.

Steps to Reproduce:
1.#service xend stop
2.#top  (see the load average by hours) 
3.#ps aux |grep "^D" (there are lots of "D" status process)
     
Actual results:
See the result of 'ps' ,we will find there are a lot of "D" state process.Theses process are waiting for cat /sys/hypervisor/uuid.And the load average become more and more high.
Expected results:
When the daemon of xend stops, the process can read /sys/hypervisor/uuid.The load average is not high by hours. 

Additional info:
In RHEL 5.4 before,we find the bug for Reading /sys/hypervisor/uuid in Dom0 hangs if XenStoreD isn't running.The bugzilla website is https://bugzilla.redhat.com/show_bug.cgi?id=225203