Re: [kvm-devel] WARNING: at /usr/src/modules/kvm/mmu.c:390 account_shadowed()

Avi Kivity
2008-05-19T14:30:54Z

Thomas Cataldo wrote:
> On Sat, Apr 26, 2008 at 10:08 AM, Avi Kivity <avi@qumranet.com> wrote:
>
>> That strikes me as unlikely (though a valid scenario).
>>
>> An alternative explanation is that we're seeing a nonpae guest, so each page
>> can be shadowed in two different roles (two quadrants for a pte page) or
>> even four (for a pgd page).
>>
>> Thomas, are you running a 32-bit nonpae guest?
>>
>>
>
> We reproduiced this on a production machine, running with :
>
>
[...]

> kvm is version 66.
>
> The offending guest was a 32bit winXp (don't know if this uses pae or
> not) with 384mo of ram. we use tap networking and vnc access. The vms
> on this server are qcow2 files stored lvm (this might be relevant as
> lots of vfs calls are in the traces) :
> /dev/mapper/volGroupe-VMs on /mnt/machines_virtuelles type ext3 (rw)
> /dev/mapper/volGroupe-VMs_snapshots on /mnt/VMs_snapshots type ext3 (rw)
>
> The command line used to start the vms looks like this :
> /usr/bin/kvm -m 256 -hda /home/tom/kvm/root/root_vm.qcow2 -no-acpi
> -net nic,model=e1000,macaddr=52:54:10:00:00:02 -net
> tap,script=/etc/qemu-kvm.ifup,downscript=/etc/qemu-kvm.ifdown
> -daemonize -monitor telnet:localhost:9002,server,nowait -vnc :2 -k fr
>
> I attached our dmesg output with all the warnings we grabbed.
>

From the trace it looks like a nonpae guest (paging32_...). Anyway
this was fixed in kvm-68.

--
error compiling committee.c: too many arguments to function