Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 093/180] virtio_balloon: fix race by fill and leak | Date | Wed, 3 Feb 2016 22:31:39 +0000 |
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3.16.7-ckt24 -stable review patch. If anyone has any objections, please let me know.
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From: Minchan Kim <minchan@kernel.org>
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 <minchan@kernel.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/virtio/virtio_balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 25ebe8eecdb7..eb35e3fa984a 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,
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