Re: [PATCH v6 00/17] mm: Introduce section-based vmemmap optimization for HugeTLB

[Andrew Morton]

On Thu, 10 Sep 2026 14:32:39 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:

> This series is split out from the earlier, larger series "mm: Generalize
> HVO for HugeTLB and device DAX" [1]. While the parent series generalizes
> vmemmap optimization across HugeTLB and device DAX, this subset addresses
> a single, self-contained step: making the generic sparse-vmemmap code
> section-based optimization aware and switching HugeTLB bootmem pages to
> this path.
> 
> HugeTLB vmemmap optimization currently has its own early boot setup
> path. It pre-populates optimized vmemmap mappings before the normal
> sparse-vmemmap population code runs, and sparsemem carries
> SPARSEMEM_VMEMMAP_PREINIT only to support that special case.
> 
> That makes the HugeTLB vmemmap optimization path harder to share with
> other users of sparse-vmemmap optimization and leaves a fair amount of
> HugeTLB-specific boot-time state in the generic memory initialization
> flow.
> 
> This series introduces section-based vmemmap optimization support in
> the sparse-vmemmap code and switches HugeTLB bootmem pages over to it.
> Instead of having HugeTLB pre-populate optimized vmemmap mappings
> itself, HugeTLB now records the compound page order in the corresponding
> memory sections. The generic sparse-vmemmap population path can then
> allocate or reuse shared tail vmemmap pages based on section metadata.

Thanks, I updated mm-unstable with this series.