[vfio-users] "BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8"

[Nick Sarnie]

On Fri, Feb 23, 2018 at 6:04 PM, Will Marler <will at wmarler.com> wrote:
> I'm running Arch and updating recently has caused my VM to stop booting.
>
> Watching journalctl I see this when I try to start the VM:
>
> "Feb 23 15:04:07 haze kernel: BUG: unable to handle kernel NULL pointer
> dereference at 00000000000000a8
> Feb 23 15:04:07 haze kernel: IP: down_write+0x12/0x30
>
> and some more. Full pastebin is here: https://pastebin.com/8u70XLWJ
>
> This happens when I try to start my domain (called "Win10Full"). When it
> occurs, virsh locks up -- if I'm in virsh and do "list" it sits
> indefinitely. If I ctrl-C at this point, "End of file while reading data:
> Input/output error" gets written to the log, and my host cannot be rebooted
> without a physical power cycle.
>
> There is nothing that gets written to /var/log/libvirt/qemu/Win10Full.log.
>
> I'm not sure how to proceed; I figured this mailing list would be the first
> place to start. Any suggestions?
>
> Thanks in advance,
>
> Will
>
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Hi,

This is a bug in 4.15. You can either revert to 4.14, or revert this
patch and recompile the kernel:

https://patchwork.kernel.org/patch/10103043/raw/

Sarnex