[PATCH v2 0/6] mm: Fix vmemmap optimization accounting and initialization

[Muchun Song <songmuchun@bytedance.com>]

This patch series fixes a number of issues related to vmemmap optimization
for compound pages (e.g., DAX), including incorrect page accounting and
missing architecture-specific initialization steps.

The series addresses these issues through the following steps:
- Patch 1: Fixes a vmemmap accounting underflow in error paths.
- Patch 2-3: Fixes DAX vmemmap accounting by plumbing the pgmap
  argument through memory deactivation paths.
- Patch 4-5: Fixes missing architecture-specific page table syncs by
  plumbing the pgmap argument through vmemmap_populate APIs.
- Patch 6: Fixes pageblock migratetype initialization for large
  compound ZONE_DEVICE pages.

Changelog:
v1 -> v2:
- Moved vmemmap accounting to populate_section_memmap() /
  depopulate_section_memmap() to fix accounting underflow,
  suggested by Mike.
- Replaced VM_BUG_ON with VM_WARN_ON_ONCE as requested by David.
- Reduced frequency of calling cond_resched() in pageblock_migratetype_init_range()
  based on feedback from David and Mike.
- Extracted all bugfix patches from a larger patchset
  (https://lore.kernel.org/linux-mm/20260405125240.2558577-1-songmuchun@bytedance.com/)
  into this separate patchset, suggested by David.

Muchun Song (6):
  mm/sparse-vmemmap: Fix vmemmap accounting underflow
  mm/sparse-vmemmap: Pass @pgmap argument to memory deactivation paths
  mm/sparse-vmemmap: Fix DAX vmemmap accounting with optimization
  mm/sparse-vmemmap: Pass @pgmap argument to arch vmemmap_populate()
  mm/sparse-vmemmap: Fix missing architecture-specific page table sync
  mm/mm_init: Fix pageblock migratetype for ZONE_DEVICE compound pages

 arch/arm64/mm/mmu.c                        | 11 +--
 arch/loongarch/mm/init.c                   | 12 +--
 arch/powerpc/include/asm/book3s/64/radix.h |  9 +--
 arch/powerpc/mm/book3s64/radix_pgtable.c   | 18 +++--
 arch/powerpc/mm/init_64.c                  |  4 +-
 arch/powerpc/mm/mem.c                      |  5 +-
 arch/riscv/mm/init.c                       |  9 ++-
 arch/s390/mm/init.c                        |  5 +-
 arch/s390/mm/vmem.c                        |  2 +-
 arch/sparc/mm/init_64.c                    |  5 +-
 arch/x86/mm/init_64.c                      | 13 +--
 include/linux/memory_hotplug.h             |  8 +-
 include/linux/mm.h                         |  8 +-
 mm/hugetlb_vmemmap.c                       |  4 +-
 mm/memory_hotplug.c                        | 12 +--
 mm/memremap.c                              |  4 +-
 mm/mm_init.c                               | 42 ++++++----
 mm/sparse-vmemmap.c                        | 93 ++++++++++++++--------
 18 files changed, 160 insertions(+), 104 deletions(-)

-- 
2.20.1