Re: [PATCH] mm/page_vma_mapped: guard check_pmd() with CONFIG_TRANSPARENT_HUGEPAGE

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 24 Jun 2026 08:23:59 +0000 Wei Yang <richard.weiyang@gmail.com> wrote:

> The kernel test robot reported a build failure on the parisc architecture
> when expanding HPAGE_PMD_NR in check_pmd().
> 
>    mm/page_vma_mapped.c:142:13: note: in expansion of macro 'HPAGE_PMD_NR'
>      if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)
>                 ^~~~~~~~~~~~
> 
> The config [1] in report link shows neither TRANSPARENT_HUGEPAGE nor
> HUGETLB_PAGE is defined. Then trigger the BUILD_BUG.
> 
> Fix it by define check_pmd() under CONFIG_TRANSPARENT_HUGEPAGE.

hm,

#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
#define HPAGE_PMD_SHIFT PMD_SHIFT
#define HPAGE_PUD_SHIFT PUD_SHIFT
#else
#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
#define HPAGE_PUD_SHIFT ({ BUILD_BUG(); 0; })
#endif

> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  /* Returns true if the two ranges overlap.  Careful to not overflow. */
>  static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw)
>  {
> @@ -145,6 +146,12 @@ static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw)
>  		return false;
>  	return true;
>  }
> +#else
> +static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw)
> +{
> +	return false;
> +}
> +#endif

I'll leave it to others to decide if this is the most appropriate fix.

Sashiko had an off-topic complaint about the surrounding code:
	https://lore.kernel.org/oe-kbuild-all/202606240042.ffPsEXVc-lkp@intel.com/