[RFC 5/5] xen: balloon: update the NR_BALLOON_PAGES state

[Nico Pache <npache@redhat.com>]

Update the NR_BALLOON_PAGES counter when pages are added to or
removed from the Xen balloon.

Signed-off-by: Nico Pache <npache@redhat.com>
---
 drivers/xen/balloon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 163f7f1d70f1..65d4e7fa1eb8 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -157,6 +157,8 @@ static void balloon_append(struct page *page)
 		list_add(&page->lru, &ballooned_pages);
 		balloon_stats.balloon_low++;
 	}
+	inc_node_page_state(page, NR_BALLOON_PAGES);
+
 	wake_up(&balloon_wq);
 }
 
@@ -179,6 +181,8 @@ static struct page *balloon_retrieve(bool require_lowmem)
 		balloon_stats.balloon_low--;
 
 	__ClearPageOffline(page);
+	dec_node_page_state(page, NR_BALLOON_PAGES);
+
 	return page;
 }
 
-- 
2.48.1