My un-authoritative answer: I've been tracking this bug (or several with the same symptoms) for going on a couple years. It's ridiculously common, apparently well known to the Xen/Xensource guys judging by the number of reports/bugs posted, but I haven't seen mention of it actually being addressed and resolved. Unfortunately I see the same issue with it cropping up after VM moves, though it occurs /every/ time there is a VM migration, once per processor in the VM; doesn't matter if there is any IO on the Dom0 or DomU. Occasionally VM's die during a migration and have to be manually destroyed/restarted. I do see evidence of significant instability (not implying it is related to the above softlockup issues) however, in either VM moves migrating from a Xeon (5345) to Opteron Dom0, and in high-utilization DomU's which are just plain flaky and reboot/die semi-frequently even when never altered from their start Dom0. For me, it currently means running only low-priority non-production services in a VM, and not shelling out for RHEL5 support for the project (contrary to what I planned) since it's not being addressed. I'd be curious if this is being addressed in the Xen 3.2 release for RHEL5*... Cheers, /eli Brett Worth wrote: > Hello All. > > I've just started looking into Xen and have a test environment in > place. I'm seeing an > annoying problem that I thought worthy of a post. > > Config: > > I have 2 x HP DL585 servers each with 4 Dual core Opterons (non-vmx) and > 16GB RAM > configured as Xen servers. These run CentOS 5.1 with the latest updates > applied. These > system both attach to an iSCSI target which is an HP DL385 running ietd > and serving SAN > based storage. > > I have a test VM running CentOS 5.1 also updated. > > Problem: > > If I run the VM on a single server everything is OK. If I do a migrate > of the VM to the > other server I start getting random "BUG: soft lockup detected on CPU#?" > messages on the > VM console. The messages seem to happen with IO but not every time. A > reboot of the VM > on the new server will stop these messages. > > I've also left the VM running overnight a couple of times and when I do > I find that any > external sessions (ssh) are hung in the morning but the console session > is not. New ssh > sessions can be started and seem to work. > > After much googling it looks like the kernel messages can occur if dom0 > is very busy but > mine is not. > > Any suggestions? > > Regards > > Brett Worth > > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt >