The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c9a6820fc0da2603be3054ee7590eb9f350508a7 Mon Sep 17 00:00:00 2001

From: Wei Wang wei.w.wang@intel.com Date: Tue, 19 Nov 2019 05:02:33 -0500 Subject: [PATCH] virtio_balloon: fix shrinker count

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@vger.kernel.org Fixes: 71994620bb25 ("virtio_balloon: replace oom notifier with shrinker") Signed-off-by: Wei Wang wei.w.wang@intel.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Reviewed-by: David Hildenbrand david@redhat.com

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 51134f9a3ee7..e05679c478e2 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -826,7 +826,7 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, 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; }