On Fri, Dec 15, 2017 at 6:48 PM, Al Viro <v...@zeniv.linux.org.uk> wrote: > > Treating protection key bits as "escalate to page fault and let that > deal with the checks" should be fine
Well, it's *semantically* fine and I think it's the right model from that standpoint. However, since the main use case of protection keys is probably databases (Dave?) and since those also might be performance-sensitive about direct-IO doing page table lookups, it might not be great in practice. Linus