Re: [PATCH net 1/2] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()

From: Michael S. Tsirkin
Date: Wed Jan 24 2018 - 16:46:25 EST


On Wed, Jan 24, 2018 at 04:38:30PM -0500, David Miller wrote:
> From: Jason Wang <jasowang@xxxxxxxxxx>
> Date: Tue, 23 Jan 2018 17:27:25 +0800
>
> > 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> Michael, I see you ACK'd this, meaning that you're OK with these two
> fixes going via my net tree?
>
> Thanks.

Yes - this seems to be what Jason wanted (judging by the net
tag in the subject) and I'm fine with it.
Thanks a lot.

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MST