There's what looks like a race condition discussed at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=698810 This doesn't do anything about the race condition, but tries to report more helpful information when it happens. If I knew how to test this properly, I'd probably know how to reproduce the race condition. The first page in the series is needed for some other things, so it's not as much overkill as it looks.