I've seen on various Xen/amd64 setups of mine hangs like those reported in the
They seem to occur especially when dom0 is under heavy load (typically when
running climateprediction.net, if you try a dist-upgrade or an install of any
package that touches mandb, the install will hang).
It can affect pretty much any process (I've experienced it with ssh, or bash...)
I'm afraid it gets really nasty when, as in the attached output, it affects key
kernel processes such as kjournald...