Re: [PATCH v8 02/10] powerpc/8xx: add pte_set_huge()

[Barry Song]

On Thu, Sep 17, 2026 at 1:30 PM Wen Jiang <jiangwenxiaomi@xxxxxxxxx> wrote:
>
> From: Wen Jiang <jiangwen6@xxxxxxxxxx>
>
> vmap installs PTE-level block mappings (SZ_16K/SZ_512K on powerpc/8xx)
> by reusing set_huge_pte_at(), a HugeTLB helper gated by
> CONFIG_HUGETLB_PAGE. This makes the feature silently unavailable on
> CONFIG_HUGETLB_PAGE=n kernels and couples mm/vmalloc.c to HugeTLB
> internals it does not otherwise need.
>
> Add pte_set_huge() to powerpc/8xx, next to the existing
> pmd_clear_huge()/pud_clear_huge() in mm/nohash/8xx.c. It builds the huge
> PTE and writes it into the backing cells directly, without going through
> set_huge_pte_at(), so it does not depend on CONFIG_HUGETLB_PAGE.
>
> No pte_clear_huge() is needed: 8xx does not implement
> arch_vmap_pte_range_unmap_size(), so the vmap unmap path never takes the
> block-mapping branch.

I assume you mean the block-unmapping (or PTE-clearing) branch.
Please make this clear in the changelog.

>
> In practice PPC_8xx selects HUGETLBFS unconditionally, so
> CONFIG_HUGETLB_PAGE=n does not occur there today; this is a decoupling
> cleanup rather than a new configuration.
>
> There is no caller yet: mm/vmalloc.c is converted later in this series,
> once the generic fallbacks are in place.
>
> Signed-off-by: Wen Jiang <jiangwen6@xxxxxxxxxx>
> ---

BTW, this patch applies cleanly to the mm-new branch.

Best Regards
Barry