Re: [PATCH] mm/mapping_dirty_helpers: Guard hugepage pud's usage

[Thomas Hellström (Intel)]

On 4/8/21 9:15 PM, Zack Rusin wrote:
> Lets make sure we don't use pud hugepage helpers on architectures
> which do not support it. This fixes the code on arm64.
nits:

Perhaps be a little more specific about what it fixes? I figure it's a 
compilation failure?
Also please use imperative form: "Fix the code arm64" rather than "This 
fixes the code on arm64"

Other than that LGTM.

Reviewed-by: Thomas Hellström (Intel) <thomas_os@xxxxxxxxxxxx>


> Signed-off-by: Zack Rusin <zackr@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Thomas Hellström (Intel) <thomas_os@xxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>   mm/mapping_dirty_helpers.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/mm/mapping_dirty_helpers.c b/mm/mapping_dirty_helpers.c
> index b59054ef2e10..b890854ec761 100644
> --- a/mm/mapping_dirty_helpers.c
> +++ b/mm/mapping_dirty_helpers.c
> @@ -165,10 +165,12 @@ static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
>   		return 0;
>   	}
>   
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
>   	/* Huge pud */
>   	walk->action = ACTION_CONTINUE;
>   	if (pud_trans_huge(pudval) || pud_devmap(pudval))
>   		WARN_ON(pud_write(pudval) || pud_dirty(pudval));
> +#endif
>   
>   	return 0;
>   }