mm: kmsan: export kmsan_copy_page_meta()

Certain modules call copy_user_highpage(), which calls
kmsan_copy_page_meta() under KMSAN, so we need to export the latter.

Link: https://lkml.kernel.org/r/20221024212144.2852069-1-glider@google.com
Link: https://github.com/google/kmsan/issues/89
Fixes: b073d7f8 ("mm: kmsan: maintain KMSAN metadata for page operations")
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kmsan/shadow.c

@@ -167,6 +167,7 @@ void kmsan_copy_page_meta(struct page *dst, struct page *src)
 	__memcpy(origin_ptr_for(dst), origin_ptr_for(src), PAGE_SIZE);
 	kmsan_leave_runtime();
 }
+EXPORT_SYMBOL(kmsan_copy_page_meta);
 
 void kmsan_alloc_page(struct page *page, unsigned int order, gfp_t flags)
 {