From: Minchan Kim Date: Sun, 27 Dec 2015 23:35:12 +0000 (+0900) Subject: virtio_balloon: fix race by fill and leak X-Git-Tag: v3.16.35~597 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9f0f48350a29b198a3d8c530ce8376c3346f5151;p=thirdparty%2Fkernel%2Fstable.git virtio_balloon: fix race by fill and leak commit f68b992bbb474641881932c61c92dcfa6f5b3689 upstream. 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. Signed-off-by: Minchan Kim Signed-off-by: Michael S. Tsirkin [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 25ebe8eecdb73..eb35e3fa984ad 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -193,8 +193,8 @@ static void 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_by_pfn(vb->pfns, vb->num_pfns); + mutex_unlock(&vb->balloon_lock); } static inline void update_stat(struct virtio_balloon *vb, int idx,