KASAN_TAG_MASK
tag = (page->flags.f >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
{KASAN_TAG_WIDTH, KASAN_TAG_PGSHIFT, KASAN_TAG_MASK,
{KASAN_TAG_WIDTH, KASAN_TAG_PGSHIFT, KASAN_TAG_MASK,