On Mon, Dec 28, 2015 at 08:35:12AM +0900, Minchan Kim wrote: > During my compaction-related stuff, I encountered a bug > with ballooning. > > With repeated inflating and deflating cycle, guest memory( > ie, cat /proc/meminfo | grep MemTotal) is decreased and > couldn't be recovered. > > The reason is balloon_lock doesn't cover release_pages_balloon > so struct virtio_balloon fields could be overwritten by race > of fill_balloon(e,g, vb->*pfns could be critical). > > This patch fixes it in my test. > > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > drivers/virtio/virtio_balloon.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 7efc32945810..7d3e5d0e9aa4 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -209,8 +209,8 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > */ > if (vb->num_pfns != 0) > tell_host(vb, vb->deflate_vq); > - mutex_unlock(&vb->balloon_lock); > release_pages_balloon(vb); > + mutex_unlock(&vb->balloon_lock); > return num_freed_pages; > } > > -- > 1.9.1 > Acked-by: Rafael Aquini <aquini@xxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>