Sorry for the noise if this isn't the appropriate venue for this. I posted this last month to xen-devel:

http://lists.xensource.com/archives/html/xen-devel/2007-11/msg00777.html

I can reliably cause a paravirt_ops Xen guest to hang during intensive IO. My current recipe is an untar/tar loop, without compression, of a kernel tree. For example:

wget http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.tar.bz2 bzip2 -d linux-2.6.23.tar.bz2

while true; echo `date` tar xf linux-2.6.23.tar tar cf linux-2.6.23.tar linux-2.6.23 done

After a few loops, anything that touches the xvd device that hung will get stuck in D state.

This happens on both a 2.6.16 and 2.6.18 dom0 (3.1.2 tools). Paravirt guests I've tried that exhibit the problem: 2.6.23.8, 2.6.23.12, and 2.6.24-rc6. It does *not* occur using the Xensource 2.6.18 domU tree from 3.1.2. In all cases, the host continues to run fine, nothing out of the ordinary is logged on the dom0 side, xenstore reports the status of the devices is fine.

Can anyone reproduce this problem, or let me know what else I can provide to help track this down?

Thanks, -Chris