4.14-stable review patch.  If anyone has any objections, please let me know.


From: Jason Wang <jasow...@redhat.com>

commit e9cb4239134c860e5f92c75bf5321bd377bb505b upstream.

We used to call mutex_lock() in vhost_dev_lock_vqs() which tries to
hold mutexes of all virtqueues. This may confuse lockdep to report a
possible deadlock because of trying to hold locks belong to same
class. Switch to use mutex_lock_nested() to avoid false positive.

Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Reported-by: syzbot+dbb7c1161485e61b0...@syzkaller.appspotmail.com
Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

 drivers/vhost/vhost.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -904,7 +904,7 @@ static void vhost_dev_lock_vqs(struct vh
        int i = 0;
        for (i = 0; i < d->nvqs; ++i)
-               mutex_lock(&d->vqs[i]->mutex);
+               mutex_lock_nested(&d->vqs[i]->mutex, i);
 static void vhost_dev_unlock_vqs(struct vhost_dev *d)

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