Commit 532a6086 authored Aug 18, 2008 by Anthony Liguori Committed by Rusty Russell Aug 26, 2008

virtio_balloon: fix towards_target when deflating balloon

Both v and vb->num_pages are u32 and unsigned int respectively. If v is less
than vb->num_pages (and it is, when deflating the balloon), the result is a
very large 32-bit number. Since we're returning a s64, instead of getting the
same negative number we desire, we get a very large positive number.

This handles the case where v < vb->num_pages and ensures we get a small,
negative, s64 as the result.

Rusty: please push this for 2.6.27-rc4. It's probably appropriate for the
stable tree too as it will cause an unexpected OOM when ballooning.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (simplified)

parent 83097aca

drivers/virtio/virtio_balloon.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -158,7 +158,7 @@ static inline s64 towards_target(struct virtio_balloon *vb)
	vb->vdev->config->get(vb->vdev,		vb->vdev->config->get(vb->vdev,
	offsetof(struct virtio_balloon_config, num_pages),		offsetof(struct virtio_balloon_config, num_pages),
	&v, sizeof(v));		&v, sizeof(v));
	return v - vb->num_pages;		return (s64)v - vb->num_pages;
	}		}

	static void update_balloon_size(struct virtio_balloon *vb)		static void update_balloon_size(struct virtio_balloon *vb)