[$] 4.20/5.0 Merge window part 1

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