[PATCH v2 1/2] vdso: move offset_in_page() from linux/mm.h to vdso/page.h

[Thorsten Blum <thorsten.blum@linux.dev>]

Move offset_in_page() out of linux/mm.h so users that only need page
offset calculations can include the lightweight vdso/page.h header
instead of pulling in the large linux/mm.h.

Include vdso/page.h from linux/mm.h so existing users of
offset_in_page() continue to build.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 include/linux/mm.h  | 2 +-
 include/vdso/page.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9cedc5e75aa9..d5c7f1ca80ef 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -37,6 +37,7 @@
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <linux/iommu-debug-pagealloc.h>
+#include <vdso/page.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -3023,7 +3024,6 @@ static inline void clear_page_pfmemalloc(struct page *page)
  */
 extern void pagefault_out_of_memory(void);
 
-#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
 #define offset_in_folio(folio, p) ((unsigned long)(p) & (folio_size(folio) - 1))
 
 /*
diff --git a/include/vdso/page.h b/include/vdso/page.h
index bc47186c07fc..948b13091084 100644
--- a/include/vdso/page.h
+++ b/include/vdso/page.h
@@ -28,4 +28,6 @@
 #define PAGE_MASK	(~(PAGE_SIZE - 1))
 #endif
 
+#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
+
 #endif	/* __VDSO_PAGE_H */