On Fri, May 06, 2016 at 05:03:59PM +0200, Andrea Arcangeli wrote:
> compound_mapcount() is only called after PageCompound() has already
> been checked by the caller, so there's no point to check it again. Gcc
> may optimize it away too because it's inline but this will remove the
> runtime check for sure and add it'll add an assert instead.
>
> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> include/linux/mm.h | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 263f229..726ba80 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -471,8 +471,7 @@ static inline atomic_t *compound_mapcount_ptr(struct page *page)
>
> static inline int compound_mapcount(struct page *page)
> {
> - if (!PageCompound(page))
> - return 0;
> + VM_BUG_ON_PAGE(!PageCompound(page), page);
> page = compound_head(page);
> return atomic_read(compound_mapcount_ptr(page)) + 1;
> }
--
Kirill A. Shutemov
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