Xen users - Mar 2012 - Live Migration failes with Failed to pin batch of xxx page tables (22 = Invalid argument): Internal error

Hi folks,

I have setup Xen 4.1.2 on CentOS 6. It is running fine so far, but live 
migration does not work.

While the source host works on the "xm migrate -l ..." command, I can 
see the VM on the target host in paused state in "xm list", but after
a
while it vanishes while the xm command on the source machine returns 
with return code 130.
Both machines have identical hardware (Xeon E5310, Chipset, etc.).

In the logs of the target machine I find entries like
> INFO (XendCheckpoint:423) xc: error: Failed to pin batch of 392 page 
> tables (22 = Invalid argument): Internal error
and then:
> [2012-03-13 20:38:23 1696] ERROR (XendDomainInfo:3085) 
> XendDomainInfo.destroy: domain destruction failed.
> Traceback (most recent call last):
>   File 
> "/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py",
line
> 3078, in destroy
>     xc.domain_pause(self.domid)
> Error: (3, ''No such process'')
I have searched the net and this list and found a few posts mentioning 
this error, but no solution, not even a hint on the source of the 
probelm. And most of the posts seem concerned with Remus, not with 
"plain" live migration.

What can I do to troubleshoot this issue?

Any hint or help is appreciated.

Dirk