On Sat 16-12-17 08:44:22, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
>
> Instead of putting the ifdef in the middle of the definition of struct
> page, pull it forward to the rest of the ifdeffery around the SLUB
> cmpxchg_double optimisation.
>
> Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
The definition of struct page looks better now. I think that slub.c
needs some love as well. I haven't checked too deeply but it seems that
it assumes counters to be unsigned long in some places. Maybe I've
missed some ifdef-ery but using the native type would be much better
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> include/linux/mm_types.h | 21 ++++++++-------------
> 1 file changed, 8 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 8c3b8cea22ee..5521c9799c50 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -41,9 +41,15 @@ struct hmm;
> */
> #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
> #define _struct_page_alignment __aligned(2 * sizeof(unsigned long))
> +#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)
> +#define _slub_counter_t unsigned long
> #else
> -#define _struct_page_alignment
> +#define _slub_counter_t unsigned int
> #endif
> +#else /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
> +#define _struct_page_alignment
> +#define _slub_counter_t unsigned int
> +#endif /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
>
> struct page {
> /* First double word block */
> @@ -66,18 +72,7 @@ struct page {
> };
>
> union {
> -#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
> - defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
> - /* Used for cmpxchg_double in slub */
> - unsigned long counters;
> -#else
> - /*
> - * Keep _refcount separate from slub cmpxchg_double data.
> - * As the rest of the double word is protected by slab_lock
> - * but _refcount is not.
> - */
> - unsigned counters;
> -#endif
> + _slub_counter_t counters;
> unsigned int active; /* SLAB */
> struct { /* SLUB */
> unsigned inuse:16;
> --
> 2.15.1
>
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--
Michal Hocko
SUSE Labs
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