Re: [PATCH v4 00/19] mm: Refactor bootmem gigantic hugepage allocation

[Muchun Song <muchun.song@linux.dev>]

> On Jun 12, 2026, at 11:58, Muchun Song <songmuchun@bytedance.com> wrote:
> 
> This series is split out from the earlier larger series "mm: Generalize
> HVO for HugeTLB and device DAX" [1]. It collects the first 19 patches of
> that series as a standalone set of fixes and preparatory cleanups around
> bootmem HugeTLB handling, sparse initialization ordering, and related
> vmemmap setup.
> 
> The first patches fix a few bugs found while reviewing the existing
> code, including incorrect bootmem HVO handling, wrong vmemmap
> registration arguments, a powerpc compound-vmemmap tracking bug, and
> too-late initialization of gigantic bootmem HugeTLB struct pages.
> 
> The rest of the series reorders early memory initialization so the
> relevant zone state is available before sparse and HugeTLB boot-time
> setup runs, then simplifies the remaining bootmem gigantic hugepage
> allocation path and removes code made obsolete by that rework.
> 
> At a high level:
>  - patches [1-4] fix boot-time and arch-specific bugs
>  - patches [5-12] reorder and simplify sparse/mm/hugetlb early init
>  - patches [13-19] refactor bootmem gigantic hugepage allocation and
>    remove obsolete helpers and state
> 
> Changes since v3:
>  - patches 2-4: add Cc: stable@vger.kernel.org to the applicable fixes
>  - patch 3: collect Reviewed-by from Ritesh Harjani
>  - patch 15: move pfn_to_zone() before hugetlb_vmemmap_init_early()
>    instead of using a forward declaration
>  - patches 15-17: collect Acked-by from Mike Rapoport where applicable
>  - patch 15: collect Acked-by from Usama Arif
>  - patch 18: clarify that the changelog also covers the early CMA
>    bootmem allocation fallback refactoring
>  - patch 19: initialize pgdat at declaration in
>    __init_deferred_page() and collect Reviewed-by from Mike Rapoport
> 
> [1] https://lore.kernel.org/linux-mm/20260513130542.35604-1-songmuchun@bytedance.com/

Hi Andrew,

Would you mind picking these up for the mm-unstable branch? Almost all
patches have received a Reviewed-by or Acked-by.

Regarding the Sashiko review comments, it reported 5 issues in total, and
I've verified all of them:

- Patches 7 & 11: These are pre-existing issues and not introduced by this
  series.
- Patch 14: This is a false positive.
- Patches 8 & 9: These are valid observations but not a practical issue. The
  report mentioned:

	"moving these reservations after free_area_init() artificially inflate
	 nr_kernel_pages and nr_all_pages, potentially causing an early boot OOM"

However, this aligns the 1GB HugeTLB allocation behavior with the existing
2MB HugeTLB allocation, which already behaves this way. So it won't introduce
new risks.

Thanks for your time!

Best regards,
Muchun

> 
> Muchun Song (19):
>  mm/hugetlb: Fix boot panic with CONFIG_DEBUG_VM and HVO bootmem pages
>  mm/hugetlb_vmemmap: Fix __hugetlb_vmemmap_optimize_folios()
>  powerpc/mm: Fix wrong addr_pfn tracking in compound vmemmap population
>  mm/hugetlb: Initialize gigantic bootmem hugepage struct pages earlier
>  mm/mm_init: Simplify deferred_free_pages() migratetype init
>  mm/sparse: Panic on memmap and usemap allocation failure
>  mm/sparse: Move subsection_map_init() into sparse_init()
>  mm/mm_init: Defer sparse_init() until after zone initialization
>  mm/mm_init: Defer hugetlb reservation until after zone initialization
>  mm/mm_init: Remove set_pageblock_order() call from sparse_init()
>  mm/sparse: Move sparse_vmemmap_init_nid_late() into sparse_init_nid()
>  mm/hugetlb_cma: Validate hugetlb CMA range by zone at reserve time
>  mm/hugetlb: Refactor early boot gigantic hugepage allocation
>  mm/hugetlb: Free cross-zone bootmem gigantic pages after allocation
>  mm/hugetlb_vmemmap: Move bootmem HVO setup to early init
>  mm/hugetlb: Remove obsolete bootmem cross-zone checks
>  mm/sparse-vmemmap: Remove sparse_vmemmap_init_nid_late()
>  mm/hugetlb: Remove unused bootmem cma field
>  mm/mm_init: Fold __init_page_from_nid() into __init_deferred_page()
> 
> arch/powerpc/mm/book3s64/radix_pgtable.c |   7 +-
> arch/powerpc/mm/hugetlbpage.c            |  13 +-
> include/linux/hugetlb.h                  |  24 +--
> include/linux/mmzone.h                   |   7 -
> mm/cma.c                                 |   3 +-
> mm/hugetlb.c                             | 259 +++++++++++------------
> mm/hugetlb_cma.c                         |  44 ++--
> mm/hugetlb_cma.h                         |   8 +-
> mm/hugetlb_vmemmap.c                     | 120 +++--------
> mm/hugetlb_vmemmap.h                     |   5 -
> mm/internal.h                            |  14 +-
> mm/mm_init.c                             |  86 +++-----
> mm/sparse-vmemmap.c                      |  26 ++-
> mm/sparse.c                              |  48 +----
> 14 files changed, 251 insertions(+), 413 deletions(-)
> 
> 
> base-commit: ec039126b7fac4e3af35ebccaa7c6f9b6875ba81
> -- 
> 2.54.0