linux-kernel - [PATCH] virtio-balloon: move release_pages_balloon() outside of mutex_unlock(&vb->balloon

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Date:   Fri, 26 Mar 2021 17:53:26 +0800
From:   Liu Xiang <liu.xiang@...ngsmart.com>
To:     mst@...hat.com
Cc:     david@...hat.com, jasowang@...hat.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, liuxiang_1999@....com,
        liuxiang1999@...il.com, Liu Xiang <liu.xiang@...ngsmart.com>
Subject: [PATCH] virtio-balloon: move release_pages_balloon() outside of mutex_unlock(&vb->balloon_lock)

Since pages have been deflated to a local list,
there is no race between fill and leak.

Signed-off-by: Liu Xiang <liu.xiang@...ngsmart.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 8985fc2ce..7da25b87f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -303,8 +303,8 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
 	 */
 	if (vb->num_pfns != 0)
 		tell_host(vb, vb->deflate_vq);
-	release_pages_balloon(vb, &pages);
 	mutex_unlock(&vb->balloon_lock);
+	release_pages_balloon(vb, &pages);
 	return num_freed_pages;
 }
 
-- 
2.17.1