Re: [Qemu-devel] [PATCH v3] balloon: Fix failure of updating guest memory status

[Ladi Prosek]

On Mon, Aug 15, 2016 at 2:50 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Mon, Aug 15, 2016 at 1:35 PM, Ladi Prosek <address@hidden> wrote:
>> On Mon, Aug 15, 2016 at 2:09 PM, Stefan Hajnoczi <address@hidden> wrote:
>>> On Fri, Aug 05, 2016 at 01:36:32PM +0200, Ladi Prosek wrote:
>>>> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
>>>> index 5af429a..65457e9 100644
>>>> --- a/hw/virtio/virtio-balloon.c
>>>> +++ b/hw/virtio/virtio-balloon.c
>>>> @@ -423,6 +423,26 @@ static int virtio_balloon_load_device(VirtIODevice 
>>>> *vdev, QEMUFile *f,
>>>>      return 0;
>>>>  }
>>>>
>>>> +static void virtio_balloon_vmstate_cb(void *opaque, int running,
>>>> +                                      RunState state)
>>>> +{
>>>> +    VirtIOBalloon *s = opaque;
>>>> +
>>>> +    if (!running) {
>>>> +        /* put the stats element back if the VM is not running */
>>>> +        if (s->stats_vq_elem != NULL) {
>>>> +            virtqueue_discard(s->svq, s->stats_vq_elem, 
>>>> s->stats_vq_offset);
>>>
>>> The third argument should be 0 because we did not write anything into
>>> in_sg[].
>>
>> Thanks! Then it looks like the regular virtqueue_push in
>> balloon_stats_poll_cb should also be called with 0 and the
>> stats_vq_offset field can be deleted altogether. We never write to
>> in_sg.
>
> Yes.

I'll send a follow-up patch fixing this later if that's ok. Liang is
already testing this patch and passing non-0 does no harm, in_sg is
empty anyway so it doesn't make a difference really.

Thanks,
Ladi