It's been merged to v4.13 upstream kernel - https://github.com/torvalds/linux/commit/35cf2845563c1aaa01d27bd34d64795c4ae72700#diff-4f541554c5f8f378effc907c8f0c9115 and is not in current 4.4.0 Ubuntu Xenial.
It's been merged to v4.13 upstream kernel - https:/ /github. com/torvalds/ linux/commit/ 35cf2845563c1aa a01d27bd34d6479 5c4ae72700# diff-4f541554c5 f8f378effc907c8 f0c9115 and is not in current 4.4.0 Ubuntu Xenial.