Re: [PATCH RFC 00/12] mm/gup: Unify hugetlb, part 2

Jason Gunthorpe
2023-11-22T14:51:59Z

On Wed, Nov 15, 2023 at 08:28:56PM -0500, Peter Xu wrote:
> This patchset is in RFC stage. It's mostly because it is only yet tested on
> x86_64 in a VM. Not even compile tested on PPC or any other archs, it
> means at least the hugepd patch (patch 11) is mostly untested, or even not
> compile tested. Before doing that, I'd like to collect any information
> from high level.
>
> If anyone would like to provide any testing either over hugepd or CONT_PMD
> / CONT_PTE on ARM (before I reach there..), or RISCV over 64K Svnapot,
> that'll be very much appreciated. I'm copying PPC, ARM, RISCV list for
> that. It can be as simple as "./run_vmtests.sh -t gup_test -a" for now,
> making sure hugetlb pages can be allocated along the way; the non-hugetlb
> gup tests will guaranteed to be covered more or less, I suppose.
>
> In summary, this is a continuous work for previous series:
>
> https://lore.kernel.org/all/20230628215310.73782-1-peterx@redhat.com
>
> And this more or less is my current take to move one more small step
> towards merging hugetlb code into generic mm code, as much as we can.
>
> That part-1 series dropped follow_hugetlb_page(). The plan of this one is
> to further drops hugetlb_follow_page_mask(). The hugetlb GUP will use the
> same code path for generic mm after whole set applied.
>
> It means the generic code will need to at least understand hugepd, and
> that's already done like so in fast-gup. Fortunately it seems that's the
> only major thing I need to teach GUP to share the common path for now
> besides normal huge PxD entries. Non-gup can be more challenging, but
> that's a question for later.

This is great, I looked through quickly and didn't have any profound remarks

Thanks,
Jason