virtio-balloon: Fix memory leak when unloading while hinting is in progress
When unloading the driver while hinting is in progress, we will not
release the free page blocks back to MM, resulting in a memory leak.
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Liang Li <liang.z.li@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200205163402.42627-2-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 2457c54..6d063ee 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -970,6 +970,10 @@ static void remove_common(struct virtio_balloon *vb)
leak_balloon(vb, vb->num_pages);
update_balloon_size(vb);
+ /* There might be free pages that are being reported: release them. */
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+ return_free_pages_to_mm(vb, ULONG_MAX);
+
/* Now we reset the device so we can clean up the queues. */
vb->vdev->config->reset(vb->vdev);
