FAILED: patch "[PATCH] virtio_balloon: fix shrinker count" failed to apply to 4.19-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxxx>.

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@xxxxxxxxx>
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@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>

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;
 }