Re: [Qemu-devel] kvm bug in __rmap_clear_dirty during live migration

[Paolo Bonzini]

On 22/02/2017 04:08, Chris Friesen wrote:
> On 02/19/2017 10:38 PM, Han, Huaitong wrote:
>> Hi, Gaohuai
>>
>> I tried to debug the problem, and I found the indirect cause may be that
>> the rmap value is not cleared when KVM mmu page is freed. I have read
>> code without the root cause. Can you stable reproduce the the issue?
>> Many guesses need to be verified.
> 
> In both cases it seems to have been triggered by repeatedly
> live-migrating a KVM virtual machine between two hypervisors with
> Broadwell CPUs running the latest CentOS 7.
> 
> It's a race of some sort, it doesn't happen every time.

Can you reproduce it with kernel 4.8+?  I'm suspecting commmit
4e59516a12a6 ("kvm: vmx: ensure VMCS is current while enabling PML",
2016-07-14) to be the fix.

Paolo