[ovirt-users] VM get stuck randomly

[Kevin Wolf]

Hi Christophe,

Am 30.03.2016 um 13:45 hat Christophe TREFOIS geschrieben:
> Another host went down, so I have to prepare info for this one.
> 
> I could not SSH to it anymore.
> Console would show login screen, but no keystrokes were registered.
> 
> I could “suspend” the VM and “run” it, but still can’t SSH to it.
> Before suspension, all QEMU threads were around 0%, after resuming, 3 of them hover at 100%.
> 
> Attached you could find the gdb, core dump, and other logs.
> 
> Logs: https://dl.dropboxusercontent.com/u/63261/ubuntu2-logs.tar.gz
> 
> Core Dump: https://dl.dropboxusercontent.com/u/63261/core-ubuntu2.tar.gz
> 
> Is there anything else we could provide?

This sounds much like it's not qemu that hangs (because then stopping
and resuming wouldn't work any more), but just the guest OS that is
running inside the VM.

We've had cases before where qemu was reported to hang with 100% CPU
usage and in the end it turned out that the guest kernel had panicked.
Can you check whether a guest kernel crash could be the cause? If this
is reproducible, maybe the easiest way would be to attach a serial
console to the VM and let the kernel print its messages there.

Kevin