| From | Kamal Mostafa <> | Subject | [PATCH 3.13.y-ckt 066/136] virtio_balloon: fix race by fill and leak | Date | Tue, 2 Feb 2016 10:14:21 -0800 |
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3.13.11-ckt34 -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> Signed-off-by: Kamal Mostafa <kamal@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 5f8af50..38eaeae 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -194,8 +194,8 @@ 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, -- 1.9.1
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