Comment 55 for bug 1608236

It looks like commit 14de6c44d is in the Ubuntu 4.4 based kernel(It was added to resolve bug 1542939). However, the commit was never applied to upstream 4.4. That would explain why the bug does not exist in upstream 4.4, but it does in 4.4 based Xenial.

Can you see if this bug also exists in the 4.8 based Yakkety kernel? If it does, we may just have to revert 14de6c44d in Xenial.

The Yakkety kernel is available from:
https://launchpad.net/~canonical-kernel-security-team/+archive/ubuntu/ppa/+build/11288461

If the bug does exist in Yakkety, we could also see if this bug still exists in current mainline:
 http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc8