4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
commit 9c57b5808c625f4fc93da330b932647eaff321f7 upstream.
With CONFIG_BALLOON_COMPACTION=y the kernel will mount balloon_mnt for
balloon page migration when we probe a virtio_balloon device. However
we do not unmount it when removing the device. Fix this.
Fixes: b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature")
Link: http://lkml.kernel.org/r/1486531318-35189-1-git-send-email-xieyisheng1@xxxxxxxxxx
Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rafael Aquini <aquini@xxxxxxxxxx>
Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Cc: Gioh Kim <gi-oh.kim@xxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Hanjun Guo <guohanjun@xxxxxxxxxx>
Cc: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -615,8 +615,12 @@ static void virtballoon_remove(struct vi
cancel_work_sync(&vb->update_balloon_stats_work);
remove_common(vb);
+#ifdef CONFIG_BALLOON_COMPACTION
if (vb->vb_dev_info.inode)
iput(vb->vb_dev_info.inode);
+
+ kern_unmount(balloon_mnt);
+#endif
kfree(vb);
}