[$] Backports and long-term stable kernels

One of the longest running debates in the kernel community has to do withthe backporting of patches from newer kernels to older ones. Substantialeffort goes into these backports, with the resulting kernels appearing ineverything from enterprise distributions to mobile devices. A recentresurgence of this debate on the KernelSummit discussion list led to no new conclusions, but it does show howthe debate has shifted over time.