[PATCH 3/3] fixup! mm/arch: provide pud_pfn() fallback

[peterx]

From: Peter Xu <peterx@xxxxxxxxxx>

Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
 include/linux/pgtable.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index fa8f92f6e2d7..0f4b2faa1d71 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1882,9 +1882,13 @@ typedef unsigned int pgtbl_mod_mask;
  * code.  Now it happens too for pud_pfn (and can happen for larger
  * mappings too in the future; we're not there yet).  Instead of defining
  * it for all archs (like pmd_pfn), provide a fallback.
+ *
+ * Note that returning 0 here means any arch that didn't define this can
+ * get severely wrong when it hits a real pud leaf.  It's arch's
+ * responsibility to properly define it when a huge pud is possible.
  */
 #ifndef pud_pfn
-#define pud_pfn(x) ({ BUILD_BUG(); 0; })
+#define pud_pfn(x) 0
 #endif
 
 /*
-- 
2.44.0