linux-kernel - Re: [PATCH 02/17] mm: stub out all of swapops.h for !CONFIG

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Date:   Tue, 11 Jun 2019 11:15:44 +0100
From:   Vladimir Murzin <vladimir.murzin@....com>
To:     Christoph Hellwig <hch@....de>, Palmer Dabbelt <palmer@...ive.com>
Cc:     Damien Le Moal <damien.lemoal@....com>,
        linux-riscv@...ts.infradead.org, uclinux-dev@...inux.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/17] mm: stub out all of swapops.h for !CONFIG_MMU

On 6/10/19 11:16 PM, Christoph Hellwig wrote:
> The whole header file deals with swap entries and PTEs, none of which
> can exist for nommu builds.

Although I agree with the patch, I'm wondering how you get into it?

Cheers
Vladimir

> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  include/linux/swapops.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/swapops.h b/include/linux/swapops.h
> index 4d961668e5fc..b02922556846 100644
> --- a/include/linux/swapops.h
> +++ b/include/linux/swapops.h
> @@ -6,6 +6,8 @@
>  #include <linux/bug.h>
>  #include <linux/mm_types.h>
>  
> +#ifdef CONFIG_MMU
> +
>  /*
>   * swapcache pages are stored in the swapper_space radix tree.  We want to
>   * get good packing density in that tree, so the index should be dense in
> @@ -50,13 +52,11 @@ static inline pgoff_t swp_offset(swp_entry_t entry)
>  	return entry.val & SWP_OFFSET_MASK;
>  }
>  
> -#ifdef CONFIG_MMU
>  /* check whether a pte points to a swap entry */
>  static inline int is_swap_pte(pte_t pte)
>  {
>  	return !pte_none(pte) && !pte_present(pte);
>  }
> -#endif
>  
>  /*
>   * Convert the arch-dependent pte representation of a swp_entry_t into an
> @@ -375,4 +375,5 @@ static inline int non_swap_entry(swp_entry_t entry)
>  }
>  #endif
>  
> +#endif /* CONFIG_MMU */
>  #endif /* _LINUX_SWAPOPS_H */
>