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authorMinchan Kim <minchan@kernel.org>2015-12-28 02:35:12 +0300
committerMichael S. Tsirkin <mst@redhat.com>2016-01-12 21:47:05 +0300
commitf68b992bbb474641881932c61c92dcfa6f5b3689 (patch)
tree56685b8b2bb7e93b7c8c96785076cf14baab50dd
parent779a6a36961b50cd154da5705d9e6508f819cc4e (diff)
downloadlinux-f68b992bbb474641881932c61c92dcfa6f5b3689.tar.xz
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>
-rw-r--r--drivers/virtio/virtio_balloon.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 7efc32945810..7d3e5d0e9aa4 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -209,8 +209,8 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
*/
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;
}