diff --git a/[refs] b/[refs]
index fa9057290b29..5faacb8a2709 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 48ddb154cf55fb1e292af49c270b950ef2c6ef32
+refs/heads/master: f2633105cd92b793dd6a6f623b4140287d46160a
diff --git a/trunk/arch/x86/mm/init_64.c b/trunk/arch/x86/mm/init_64.c
index 6c3f6eb1f790..05f12c527b02 100644
--- a/trunk/arch/x86/mm/init_64.c
+++ b/trunk/arch/x86/mm/init_64.c
@@ -497,6 +497,14 @@ void __init mem_init(void)
 
 	/* clear_bss() already clear the empty_zero_page */
 
+	/* temporary debugging - double check it's true: */
+	{
+		int i;
+
+		for (i = 0; i < 1024; i++)
+			WARN_ON_ONCE(empty_zero_page[i]);
+	}
+
 	reservedpages = 0;
 
 	/* this will put all low memory onto the freelists */