On Fri, Jul 28, 2023 at 09:40:54PM +0200, David Hildenbrand wrote: > Hmm. So three alternatives I see: > > 1) Use FOLL_FORCE in follow_page() to unconditionally disable protnone > checks. Alternatively, have an internal FOLL_NO_PROTNONE flag if we > don't like that. > > 2) Revert the commit and reintroduce unconditional FOLL_NUMA without > FOLL_FORCE. > > 3) Have a FOLL_NUMA that callers like KVM can pass. I'm afraid 3) means changing numa balancing to opt-in, probably no-go for any non-kvm gup users as that could start to break there, even if making smaps/follow_page happy again. I keep worrying 1) on FOLL_FORCE abuse. So I keep my vote on 2). Thanks, -- Peter Xu
