Messages in this thread | | | Date | Wed, 5 Jun 2013 19:08:44 -0400 | From | Luiz Capitulino <> | Subject | Re: [PATCH] virtio_balloon: leak_balloon(): only tell host if we got pages deflated |
| |
On Wed, 5 Jun 2013 18:24:49 -0300 Rafael Aquini <aquini@redhat.com> wrote:
> On Wed, Jun 05, 2013 at 05:10:31PM -0400, Luiz Capitulino wrote: > > The balloon_page_dequeue() function can return NULL. If it does for > > the first page being freed, then leak_balloon() will create a > > scatter list with len=0. Which in turn seems to generate an invalid > > virtio request. > > > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > --- > > > > PS: I didn't get this in practice. I found it by code review. On the other > > hand, automatic-ballooning was able to put such invalid requests in > > the virtqueue and QEMU would explode... > > > > Nice catch! The patch looks sane and replicates the check done at > fill_balloon(). I think we also could use this P.S. as a commentary > to let others aware of this scenario. Thanks Luiz!
Want me to respin?
> Acked-by: Rafael Aquini <aquini@redhat.com>
Thanks for your review!
> > > > PPS: Very lightly tested > > > > drivers/virtio/virtio_balloon.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > > index bd3ae32..71af7b5 100644 > > --- a/drivers/virtio/virtio_balloon.c > > +++ b/drivers/virtio/virtio_balloon.c > > @@ -191,7 +191,8 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) > > * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); > > * is true, we *have* to do it in this order > > */ > > - tell_host(vb, vb->deflate_vq); > > + if (vb->num_pfns != 0) > > + tell_host(vb, vb->deflate_vq); > > mutex_unlock(&vb->balloon_lock); > > release_pages_by_pfn(vb->pfns, vb->num_pfns); > > } > > -- > > 1.8.1.4 > > >
| |