[$] 4.20/5.0 Merge window part 1

Linus Torvalds has returned as the keeper of the mainline kernel
repository, and the merge window for the next release which, depending on
his mood, could be
called either 4.20 or 5.0, is well underway. As of this writing, 5,735
non-merge changesets have been pulled for this release; experience suggests
that we are thus at roughly the halfway point.