linux-kernel - Re: [patch -mm] mm, compaction: persistently skip hugetlbfs pageblocks fix

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Date:   Mon, 21 Aug 2017 08:37:41 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [patch -mm] mm, compaction: persistently skip hugetlbfs
 pageblocks fix

On Sun 20-08-17 17:36:41, David Rientjes wrote:
> Fix build:
> 
> mm/compaction.c: In function ‘isolate_freepages_block’:
> mm/compaction.c:469:4: error: implicit declaration of function ‘pageblock_skip_persistent’ [-Werror=implicit-function-declaration]
>     if (pageblock_skip_persistent(page, order)) {
>     ^
> mm/compaction.c:470:5: error: implicit declaration of function ‘set_pageblock_skip’ [-Werror=implicit-function-declaration]
>      set_pageblock_skip(page);
>      ^
> 
> CMA doesn't guarantee pageblock skip will get reset when migration and 
> freeing scanners meet, and pageblock skip is a CONFIG_COMPACTION only 
> feature, so disable it when CONFIG_COMPACTION=n.
> 
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Yes, this passes the compilation test for me.

> ---
>  include/linux/pageblock-flags.h | 11 +++++++++++
>  mm/compaction.c                 |  8 +++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
> --- a/include/linux/pageblock-flags.h
> +++ b/include/linux/pageblock-flags.h
> @@ -96,6 +96,17 @@ void set_pfnblock_flags_mask(struct page *page,
>  #define set_pageblock_skip(page) \
>  			set_pageblock_flags_group(page, 1, PB_migrate_skip,  \
>  							PB_migrate_skip)
> +#else
> +static inline bool get_pageblock_skip(struct page *page)
> +{
> +	return false;
> +}
> +static inline void clear_pageblock_skip(struct page *page)
> +{
> +}
> +static inline void set_pageblock_skip(struct page *page)
> +{
> +}
>  #endif /* CONFIG_COMPACTION */
>  
>  #endif	/* PAGEBLOCK_FLAGS_H */
> diff --git a/mm/compaction.c b/mm/compaction.c
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -322,7 +322,13 @@ static inline bool isolation_suitable(struct compact_control *cc,
>  	return true;
>  }
>  
> -static void update_pageblock_skip(struct compact_control *cc,
> +static inline bool pageblock_skip_persistent(struct page *page,
> +					     unsigned int order)
> +{
> +	return false;
> +}
> +
> +static inline void update_pageblock_skip(struct compact_control *cc,
>  			struct page *page, unsigned long nr_isolated,
>  			bool migrate_scanner)
>  {


-- 
Michal Hocko
SUSE Labs