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Subject: Re: [PATCH 5/6] mm: Constify get_pfnblock_flags_mask and
 get_pfnblock_migratetype
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org
References: <20210416231531.2521383-1-willy@infradead.org>
 <20210416231531.2521383-6-willy@infradead.org>
From:   Vlastimil Babka <vbabka@suse.cz>
Message-ID: <5cb13e53-cd3f-a969-23c8-0e8a0788f242@suse.cz>
Date:   Fri, 23 Apr 2021 16:59:57 +0200
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On 4/17/21 1:15 AM, Matthew Wilcox (Oracle) wrote:
> The struct page is not modified by these routines, so it can be marked
> const.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  include/linux/pageblock-flags.h |  2 +-
>  mm/page_alloc.c                 | 13 +++++++------
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
> index fff52ad370c1..973fd731a520 100644
> --- a/include/linux/pageblock-flags.h
> +++ b/include/linux/pageblock-flags.h
> @@ -54,7 +54,7 @@ extern unsigned int pageblock_order;
>  /* Forward declaration */
>  struct page;
>  
> -unsigned long get_pfnblock_flags_mask(struct page *page,
> +unsigned long get_pfnblock_flags_mask(const struct page *page,
>  				unsigned long pfn,
>  				unsigned long mask);
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0152670c6f04..4be2179eedd5 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -474,7 +474,7 @@ static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
>  #endif
>  
>  /* Return a pointer to the bitmap storing bits affecting a block of pages */
> -static inline unsigned long *get_pageblock_bitmap(struct page *page,
> +static inline unsigned long *get_pageblock_bitmap(const struct page *page,
>  							unsigned long pfn)
>  {
>  #ifdef CONFIG_SPARSEMEM
> @@ -484,7 +484,7 @@ static inline unsigned long *get_pageblock_bitmap(struct page *page,
>  #endif /* CONFIG_SPARSEMEM */
>  }
>  
> -static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
> +static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
>  {
>  #ifdef CONFIG_SPARSEMEM
>  	pfn &= (PAGES_PER_SECTION-1);
> @@ -495,7 +495,7 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
>  }
>  
>  static __always_inline
> -unsigned long __get_pfnblock_flags_mask(struct page *page,
> +unsigned long __get_pfnblock_flags_mask(const struct page *page,
>  					unsigned long pfn,
>  					unsigned long mask)
>  {
> @@ -520,13 +520,14 @@ unsigned long __get_pfnblock_flags_mask(struct page *page,
>   *
>   * Return: pageblock_bits flags
>   */
> -unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
> -					unsigned long mask)
> +unsigned long get_pfnblock_flags_mask(const struct page *page,
> +					unsigned long pfn, unsigned long mask)
>  {
>  	return __get_pfnblock_flags_mask(page, pfn, mask);
>  }
>  
> -static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
> +static __always_inline int get_pfnblock_migratetype(const struct page *page,
> +					unsigned long pfn)
>  {
>  	return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
>  }
>