Merge branch 'vhost-fixes'

Jason Wang says:

====================
Fix various issue of vhost

This series tries to fix various issues of vhost:

- Patch 1 adds a missing write barrier between used idx updating and
  logging.
- Patch 2-3 brings back the protection of device IOTLB through vq
  mutex, this fixes possible use after free in device IOTLB entries.

Please consider them for -stable.

Changes from V2:
- drop dirty page fix and make it for net-next
Changes from V1:
- silent compiler warning for 32bit.
- use mutex_trylock() on slowpath instead of mutex_lock() even on fast
  path.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>