mm: remove misleading alignment claims

 * a page, though if it is a pagecache page, rmap structures can tell us

 * who is mapping it.

 *

 * The objects in struct page are organized in double word blocks in

 * order to allows us to use atomic double word operations on portions

 * of struct page. That is currently only used by slub but the arrangement

 * allows the use of atomic double word operations on the flags/mapping

 * and lru list pointers also.

 * SLUB uses cmpxchg_double() to atomically update its freelist and

 * counters.  That requires that freelist & counters be adjacent and

 * double-word aligned.  We align all struct pages to double-word

 * boundaries, and ensure that 'freelist' is aligned within the

 * struct.

 */

#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE

#define _struct_page_alignment	__aligned(2 * sizeof(unsigned long))

	};

	/*

	 * Third double word block

	 *

	 * WARNING: bit 0 of the first word encode PageTail(). That means

	 * the rest users of the storage space MUST NOT use the bit to

	 * avoid collision and false-positive PageTail().

#endif

	};

	/* Remainder is not double word aligned */

	union {

		unsigned long private;		/* Mapping-private opaque data:

					 	 * usually used for buffer_heads