cpu_to_ul
bitmap_ulong mask_to_set = cpu_to_ul(BITMAP_FIRST_WORD_MASK(start));
mask_to_set = cpu_to_ul(~0UL);
mask_to_set &= cpu_to_ul(BITMAP_LAST_WORD_MASK(size));
bitmap_ulong mask_to_clear = cpu_to_ul(BITMAP_FIRST_WORD_MASK(start));
mask_to_clear = cpu_to_ul(~0UL);
mask_to_clear &= cpu_to_ul(BITMAP_LAST_WORD_MASK(size));