Re: [PATCH 2/2] mm: Fixup abandoned PG_buddy for private in structpage

From: Johannes Weiner
Date: Fri Sep 28 2012 - 12:34:25 EST


On Thu, Sep 06, 2012 at 05:11:18PM +0800, Li Haifeng wrote:
> PG_buddy, an abandoned flag, indicates page(s) is/are free
> and in buddy allocator. And when page(s) in buddy allocator,
> the _mapcount will equal PAGE_BUDDY_MAPCOUNT_VALUE. So,
> here, "_mapcount equals PAGE_BUDDY_MAPCOUNT_VALUE" instead
> of "PG_buddy is set".
>
> Signed-off-by: Haifeng Li <omycle@xxxxxxxxx>
> ---
> include/linux/mm_types.h | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 704a626..49d9247 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -126,7 +126,8 @@ struct page {
> * if PagePrivate set; used for
> * swp_entry_t if PageSwapCache;
> * indicates order in the buddy
> - * system if PG_buddy is set.
> + * system if _mapcount equals
> + * PAGE_BUDDY_MAPCOUNT_VALUE.

How about simply "if PageBuddy", just like the previous sentence about
swap cache does? No reason to expose the implementation of PageBuddy
at this point, I guess...
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