On Wed, Jan 16, 2019 at 05:00:25PM +1200, Linus Torvalds wrote:

And if you're not the owner of the file, do you have another
suggestion for that "Yes, I have the right to see what's in-core for
this file". Because the problem is literally that if it's some random
read-only system file, the kernel shouldn't leak access patterns to
it..

This probably isn't a good heuristic, but thought I'd mention it
anyway ...  if the file is executable and you're not the owner, mincore
always/never says its pages are resident.  That'd fix all library leaks,
but then there's probably a smart way of figuring out something from
access patterns to a data file of some kind (/etc/passwd?)