Re: [PATCH v2 1/1] mm/hmm: Move pmd_to_hmm_pfn_flags() to the respective #ifdeffery

[Alistair Popple <apopple@nvidia.com>]

Shouldn't the Fixes tag be for the commit that introduced the #ifdeffery in the
first place? Ie: 992de9a8b751 ("mm/hmm: allow to mirror vma of a file on a DAX
backed filesystem")

As far as I can tell that is what would have introduced the warning. Other than
that it looks good though so feel free to add:

Reviewed-by: Alistair Popple <apopple@nvidia.com>

On Thu, Jul 10, 2025 at 11:23:53AM +0300, Andy Shevchenko wrote:
> When pmd_to_hmm_pfn_flags() is unused, it prevents kernel builds with clang,
> `make W=1` and CONFIG_TRANSPARENT_HUGEPAGE=n:
> 
>   mm/hmm.c:186:29: warning: unused function 'pmd_to_hmm_pfn_flags' [-Wunused-function]
> 
> Fix this by moving the function to the respective existing ifdeffery
> for its the only user.
> 
> See also:
> 
>   6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 build")
> 
> Fixes: 9d3973d60f0a ("mm/hmm: cleanup the hmm_vma_handle_pmd stub")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> 
> v2: fixed Subject prefix
> 
>  mm/hmm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/hmm.c b/mm/hmm.c
> index e8b26aa838b9..015ab243f081 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -183,6 +183,7 @@ static inline unsigned long hmm_pfn_flags_order(unsigned long order)
>  	return order << HMM_PFN_ORDER_SHIFT;
>  }
>  
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
>  						 pmd_t pmd)
>  {
> @@ -193,7 +194,6 @@ static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
>  	       hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT);
>  }
>  
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
>  			      unsigned long end, unsigned long hmm_pfns[],
>  			      pmd_t pmd)
> -- 
> 2.47.2
> 
>