Re: [PATCH kvm-next V11 0/7] Add NUMA mempolicy support for KVM guest-memfd

Sean Christopherson
2025-10-20T15:52:07Z

On Wed, Oct 15, 2025, Sean Christopherson wrote:
> On Wed, 27 Aug 2025 17:52:41 +0000, Shivank Garg wrote:
> > This series introduces NUMA-aware memory placement support for KVM guests
> > with guest_memfd memory backends. It builds upon Fuad Tabba's work (V17)
> > that enabled host-mapping for guest_memfd memory [1] and can be applied
> > directly applied on KVM tree [2] (branch kvm-next, base commit: a6ad5413,
> > Merge branch 'guest-memfd-mmap' into HEAD)
> >
> > == Background ==
> > KVM's guest-memfd memory backend currently lacks support for NUMA policy
> > enforcement, causing guest memory allocations to be distributed across host
> > nodes according to kernel's default behavior, irrespective of any policy
> > specified by the VMM. This limitation arises because conventional userspace
> > NUMA control mechanisms like mbind(2) don't work since the memory isn't
> > directly mapped to userspace when allocations occur.
> > Fuad's work [1] provides the necessary mmap capability, and this series
> > leverages it to enable mbind(2).
> >
> > [...]
>
> Applied the non-KVM change to kvm-x86 gmem. We're still tweaking and iterating
> on the KVM changes, but I fully expect them to land in 6.19.
>
> Holler if you object to taking these through the kvm tree.
>
> [1/7] mm/filemap: Add NUMA mempolicy support to filemap_alloc_folio()
> https://github.com/kvm-x86/linux/commit/601aa29f762f
> [2/7] mm/filemap: Extend __filemap_get_folio() to support NUMA memory policies
> https://github.com/kvm-x86/linux/commit/2bb25703e5bd
> [3/7] mm/mempolicy: Export memory policy symbols
> https://github.com/kvm-x86/linux/commit/e1b4cf7d6be3

FYI, I rebased these onto 6.18-rc2 to avoid a silly merge. New hashes:

[1/3] mm/filemap: Add NUMA mempolicy support to filemap_alloc_folio()
https://github.com/kvm-x86/linux/commit/7f3779a3ac3e
[2/3] mm/filemap: Extend __filemap_get_folio() to support NUMA memory policies
https://github.com/kvm-x86/linux/commit/16a542e22339
[3/3] mm/mempolicy: Export memory policy symbols