Pkg xen devel - Nov 2016 - Bug#820862: Xen VM on Jessie freezes often with INFO: task jbd2/xvda2-8:111 blocked for more than 120 seconds

Control: severity -1 normal
Control: tags -1 + moreinfo

Thanks for your report.  I'm afraid I don't really know for sure what
might be causing this.  I suspect that the root cause is probably a
kernel bug, or perhaps simply the kernel's IO scheduler being poor.

Can you please provide your Xen domain config file(s) ?  I would like
to see your storage arrangements.

What is the NFS server ?  What exact command do you run ?

Thanks,
Ian.