mm/sparse-vmemmap: introduce CONFIG_VMEMMAP_OPTIMIZATION

The section-based vmemmap optimization infrastructure is guarded by
CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP, but it can also be used by
ZONE_DEVICE users that set dev_pagemap::vmemmap_shift.  Introduce
CONFIG_VMEMMAP_OPTIMIZATION as a common config for the shared
infrastructure.

Select the new option from HUGETLB_PAGE_OPTIMIZE_VMEMMAP and from
ZONE_DEVICE when the architecture opts in to DAX vmemmap optimization, and
use it to guard the generic sparse-vmemmap state and helpers.

Link: https://lore.kernel.org/20260930140627.57431-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Lance Yang <lance.yang@linux.dev>

0 files changed, 0 insertions, 0 deletions