| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 001/145] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs() | Date | Fri, 23 Feb 2018 19:25:07 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jason Wang <jasowang@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+dbb7c1161485e61b0241@syzkaller.appspotmail.com Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -849,7 +849,7 @@ 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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