virtio_balloon: fix race by fill and leak
During my compaction-related stuff, I encountered a bug
with ballooning.
With repeated inflating and deflating cycle, guest memory(
ie, cat /proc/meminfo | grep MemTotal) is decreased and
couldn't be recovered.
The reason is balloon_lock doesn't cover release_pages_balloon
so struct virtio_balloon fields could be overwritten by race
of fill_balloon(e,g, vb->*pfns could be critical).
This patch fixes it in my test.
Cc: <stable@vger.kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 7efc329..7d3e5d0 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -209,8 +209,8 @@
*/
if (vb->num_pfns != 0)
tell_host(vb, vb->deflate_vq);
- mutex_unlock(&vb->balloon_lock);
release_pages_balloon(vb);
+ mutex_unlock(&vb->balloon_lock);
return num_freed_pages;
}
