On (23/07/13 13:20), Hyeonggon Yoo wrote:
> /*
> @@ -264,6 +247,52 @@ struct mapping_area {
> enum zs_mapmode vm_mm; /* mapping mode */
> };
>
struct zspage already has a zsdesc member at this point, so I'd prefer
to move struct zsdesc definition before struct zspage.
> +/*
> + * struct zsdesc - memory descriptor for zsmalloc memory
> + *
> + * This struct overlays struct page for now. Do not modify without a
> + * good understanding of the issues.
> + *
> + * Usage of struct page flags on zsdesc:
> + * PG_private: identifies the first component zsdesc
> + */
> +struct zsdesc {
> + unsigned long flags;
> +
> + /*
> + * Although not used by zsmalloc, this field is used by non-LRU page migration
> + * code. Leave it unused.
> + */
> + struct list_head lru;
> +
> + /* Always points to zsmalloc_mops with PAGE_MAPPING_MOVABLE set */
> + struct movable_operations *mops;
> +
> + union {
> + /* linked list of all zsdescs in a zspage */
> + struct zsdesc *next;
> + /* for huge zspages */
> + unsigned long handle;
> + };
> + struct zspage *zspage;
> + unsigned int first_obj_offset;
> + unsigned int _refcount;
> +};
> +
> +#define ZSDESC_MATCH(pg, zs) \
> + static_assert(offsetof(struct page, pg) == offsetof(struct zsdesc, zs))
> +
> +ZSDESC_MATCH(flags, flags);
> +ZSDESC_MATCH(lru, lru);
> +ZSDESC_MATCH(mapping, mops);
> +ZSDESC_MATCH(index, next);
> +ZSDESC_MATCH(index, handle);
> +ZSDESC_MATCH(private, zspage);
> +ZSDESC_MATCH(page_type, first_obj_offset);
> +ZSDESC_MATCH(_refcount, _refcount);
> +#undef ZSDESC_MATCH
> +static_assert(sizeof(struct zsdesc) <= sizeof(struct page));
> +
> /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
> static void SetZsHugePage(struct zspage *zspage)
> {
> --
> 2.41.0
>
