From: Masashi Honma <masashi.honma(a)gmail.com>
Date: Wed, 6 Jul 2016 09:28:29 +0900
Though currently such a use case was not found, to solve potential
issue we will add an allocation flag to netlink_unicast().
We don't solve potential issues, we solve real issues.
There is no reason to add the GFP parameter until it is actually
needed.