[PATCH] mm: page->mapping folio->mapping should have the same offset

[Wei Yang <richard.weiyang@gmail.com>]

In commit 7b230db3b8d3 ("mm: Introduce struct folio"), folio is
introduced. This is a folio of page, so we need to make sure those
members of folio should be at the same offset in page.

The offset of mapping is not checked. This patch just add it.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

---
BYW, I am not sure why we compare ->compound_head and ->lru?
---
 include/linux/mm_types.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index c3a6e6209600..0a2de709fe40 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -288,6 +288,7 @@ static_assert(sizeof(struct page) == sizeof(struct folio));
 	static_assert(offsetof(struct page, pg) == offsetof(struct folio, fl))
 FOLIO_MATCH(flags, flags);
 FOLIO_MATCH(lru, lru);
+FOLIO_MATCH(mapping, mapping);
 FOLIO_MATCH(compound_head, lru);
 FOLIO_MATCH(index, index);
 FOLIO_MATCH(private, private);
-- 
2.33.1