Re: [PATCH v2 1/8] mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT

On Tue, Aug 01, 2023 at 02:48:37PM +0200, David Hildenbrand wrote:

@@ -2240,6 +2244,12 @@ static bool is_valid_gup_args(struct page **pages, int *locked, gup_flags |= FOLL_UNLOCKABLE; }

• /*

• * For now, always trigger NUMA hinting faults. Some GUP users like
  

• * KVM really require it to benefit from autonuma.
  

• */
  

• gup_flags |= FOLL_HONOR_NUMA_FAULT;

Since at it, do we want to not set it for FOLL_REMOTE, which still sounds like a good thing to have?

Other than that, looks good here.

Side note: when I was looking at the flags again just to check the interactions over numa balancing, I found FOLL_NOFAULT and I highly suspect that's not needed, instead it just wants to use follow_page[_mask]() with some proper gup flags passed over.. but that's off topic.

Thanks,