[PATCH v6 0/7] 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 three patches handle follow-up initialization and cleanup
issues. Patches 5 and 6 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. The last patch factors out the altmap free
and verification logic into a helper.

Changelog:
v5 -> v6:
- Add Cc: stable at vger.kernel.org to bugfix patches.
- mm/sparse-vmemmap: Relax the alignment warning in
  section_nr_vmemmap_pages() for sub-section callers.
- mm/memory_hotplug: Factor out altmap free/check handling into a final
  standalone patch suggested-by from David Hildenbrand.
- Collect Acked-by tags from David.

Muchun Song (7):
  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
  mm/memory_hotplug: Factor out altmap freeing checks

 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            | 29 ++++++++++--------
 mm/memremap.c                  |  4 +--
 mm/mm_init.c                   | 47 ++++++++++++++++++-----------
 mm/sparse-vmemmap.c            | 55 +++++++++++++++++++++++++---------
 11 files changed, 111 insertions(+), 62 deletions(-)

-- 
2.20.1