diff --git a/[refs] b/[refs]
index 76d005124853..2ba6cc7ee09e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 17cf44064ae744f081309108fa67f0e942b10167
+refs/heads/master: 6626c5d53bc45c59798628677ba5606f02e371f3
diff --git a/trunk/mm/page_alloc.c b/trunk/mm/page_alloc.c
index bdff85899638..ed91684cb1f5 100644
--- a/trunk/mm/page_alloc.c
+++ b/trunk/mm/page_alloc.c
@@ -217,6 +217,11 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
 	int i;
 
 	BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
+	/*
+	 * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
+	 * and __GFP_HIGHMEM from hard or soft interrupt context.
+	 */
+	BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
 	for (i = 0; i < (1 << order); i++)
 		clear_highpage(page + i);
 }