[$] 5.16 Merge window, part 1

As of this writing, Linus Torvalds has pulled exactly 6,800 non-merge
changesets into the mainline repository for the 5.16 kernel release. That
is probably a little over half of what will arrive during this merge
window, so this is a good time to catch up on what has been pulled so far.
There are many significant changes and some large-scale restructuring of
internal kernel code, but relatively few ground-breaking new
features.