[PATCH v7 0/6] mm: Fix vmemmap optimization accounting and initialization

[Muchun Song]

The series fixes several bugs in vmemmap optimization, mainly around
incorrect page accounting and memmap initialization in DAX and memory
hotplug paths. It also fixes pageblock migratetype initialization and
struct page initialization for ZONE_DEVICE compound pages.

The first four patches fix vmemmap accounting issues. The first patch
fixes an accounting underflow in the section activation failure path.
The second patch fixes incorrect altmap passing in the error path.
The third patch passes pgmap through memory deactivation paths so the
teardown side can determine whether vmemmap optimization was in effect.
The fourth patch uses that information to account the optimized DAX
vmemmap size correctly.

The last two patches fix initialization issues in mm/mm_init. One makes
sure all pageblocks in ZONE_DEVICE compound pages get their migratetype
initialized. The other fixes a case where DAX memory hotplug reuses an
unoptimized early-section memmap while compound_nr_pages() still assumes
vmemmap optimization, leaving tail struct pages uninitialized.

Changes in v7:
- Split the previous series into a fixes-only series and a follow-up cleanup
  patch per review feedback.
- Drop the altmap-freeing cleanup patch from this bugfix series.
- Make the alignment assertions in section_nr_vmemmap_pages() explicit for
  subsection, compound, and section granularity as suggested by David
  Hildenbrand.
- Collect Acked-by from Mike Rapoport on the ZONE_DEVICE initialization fix.

Muchun Song (6):
  mm/sparse-vmemmap: Fix vmemmap accounting underflow
  mm/memory_hotplug: Fix incorrect altmap passing in error path
  mm/sparse-vmemmap: Pass @pgmap argument to memory deactivation paths
  mm/sparse-vmemmap: Fix DAX vmemmap accounting with optimization
  mm/mm_init: Fix pageblock migratetype for ZONE_DEVICE compound pages
  mm/mm_init: Fix uninitialized struct pages for ZONE_DEVICE

 arch/arm64/mm/mmu.c            |  5 +--
 arch/loongarch/mm/init.c       |  5 +--
 arch/powerpc/mm/mem.c          |  5 +--
 arch/riscv/mm/init.c           |  5 +--
 arch/s390/mm/init.c            |  5 +--
 arch/x86/mm/init_64.c          |  5 +--
 include/linux/memory_hotplug.h |  8 +++--
 mm/memory_hotplug.c            | 13 ++++----
 mm/memremap.c                  |  4 +--
 mm/mm_init.c                   | 47 ++++++++++++++++-----------
 mm/sparse-vmemmap.c            | 58 ++++++++++++++++++++++++++--------
 11 files changed, 105 insertions(+), 55 deletions(-)


base-commit: 7080e32d3f09d8688c4a87d81bdcc71f7f606b16
-- 
2.20.1