this article explains the SMAP feature - Jonathan Corbet really knows how to explain things.<p><a href="https://lwn.net/Articles/517475/" rel="nofollow">https://lwn.net/Articles/517475/</a>
For those who were slightly confused as to why this post talks about 4.3 when 4.8 is a few days away from release - if you miss it at the end, Kees is just catching up and will do more posts covering 4.4 to 4.8 :)