On 2018/12/12 下午10:24, Michael S. Tsirkin wrote:

On Wed, Dec 12, 2018 at 06:08:18PM +0800, Jason Wang wrote:

quoted

This reverts commit 78139c94dc8c96a478e67dab3bee84dc6eccb5fd. We don't
protect device IOTLB with vq mutex, which will lead e.g use after free
for device IOTLB entries. And since we've switched to use
mutex_trylock() in previous patch, it's safe to revert it without
having deadlock.

Fixes: commit 78139c94dc8c ("net: vhost: lock the vqs one by one")
Cc: Tonghao Zhang<redacted>
Signed-off-by: Jason Wang<jasowang@redhat.com>

Acked-by: Michael S. Tsirkin<mst@redhat.com>

I'd try to put this in 4.20 if we can
and it's needed for -stable I think.

Also looks like we should allow iotlb entries per vq
to improve locking. What do you think?

Yes, we can do it for -next.

Thanks