From: Wei Wang <wei.w.wang@xxxxxxxxx> commit c9a6820fc0da2603be3054ee7590eb9f350508a7 upstream. Instead of multiplying by page order, virtio balloon divided by page order. The result is that it can return 0 if there are a bit less than MAX_ORDER - 1 pages in use, and then shrinker scan won't be called. Cc: stable@xxxxxxxxxxxxxxx Fixes: 71994620bb25 ("virtio_balloon: replace oom notifier with shrinker") Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/virtio/virtio_balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -820,7 +820,7 @@ static unsigned long virtio_balloon_shri unsigned long count; count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE; - count += vb->num_free_page_blocks >> VIRTIO_BALLOON_FREE_PAGE_ORDER; + count += vb->num_free_page_blocks << VIRTIO_BALLOON_FREE_PAGE_ORDER; return count; }