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

Huang, Kai
2017-02-27T07:42:06Z

On 2/25/2017 2:44 PM, Herongguang (Stephen) wrote:
>
>
> On 2017/2/24 23:14, Paolo Bonzini wrote:
>>
>>
>> On 24/02/2017 16:10, Chris Friesen wrote:
>>> On 02/23/2017 08:23 PM, Herongguang (Stephen) wrote:
>>>
>>>> On 2017/2/22 22:43, Paolo Bonzini wrote:
>>>
>>>>> Hopefully Gaohuai and Rongguang can help with this too.
>>>>>
>>>>> Paolo
>>>>
>>>> Yes, we are looking into and testing this.
>>>>
>>>> I think this can result in any memory corruption, if VM1 writes its
>>>> PML buffer into VM2’s VMCS (since sched_in/sched_out notifier of VM1
>>>> is not registered yet), then VM1 is destroyed (hence its PML buffer
>>>> is freed back to kernel), after that, VM2 starts migration, so CPU
>>>> logs VM2’s dirty GFNS into a freed memory, results in any memory
>>>> corruption.
>>>>
>>>> As its severity, this commit
>>>> (http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4e59516a12a6ef6dcb660cb3a3f70c64bd60cfec)
>>>>
>>>>
>>>> is eligible to back port to kernel stable.
>>>
>>> Are we expecting that fix to resolve the original issue, or is it a
>>> separate issue that needs fixing in stable?
>>
>> It should be the original issue.
>>
>> Paolo
>>
>> .
>>
> Yes, I agree, though we are still testing.
>
>
Hi Stephen,

Sorry for late reply. I was taking the whole week off last week. How's
the test going?

Thanks,
-Kai