From 9a2d72365eca6123f780dd4f566d28ed8c1dccc6 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 4 Feb 2008 16:48:07 +0100
Subject: [PATCH] --- yaml --- r: 82895 b: refs/heads/master c:
 9a14aefc1d28c6037122965ee8c10d92a970ade0 h: refs/heads/master i:   82893:
 e8743e3ad648569d4eaf8d94f7ec15603946a072   82891:
 772fcf6f495a7c9e19ac991ce237674c8b534d01   82887:
 fab600b8de57d52ea509aff133809b9f04b05c8c   82879:
 357b8ba76ebcdb45735786bcaad8282cd20b5c79 v: v3

---
 [refs]                       |  2 +-
 trunk/arch/x86/mm/pageattr.c | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 1a057db1a0a1..4ddaf8f3f3c4 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 34508f66b69ff1708192654f631eb8f1d4c52005
+refs/heads/master: 9a14aefc1d28c6037122965ee8c10d92a970ade0
diff --git a/trunk/arch/x86/mm/pageattr.c b/trunk/arch/x86/mm/pageattr.c
index 3810f7a83b1d..7d21cd658ed3 100644
--- a/trunk/arch/x86/mm/pageattr.c
+++ b/trunk/arch/x86/mm/pageattr.c
@@ -188,6 +188,14 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
 	return prot;
 }
 
+/*
+ * Lookup the page table entry for a virtual address. Return a pointer
+ * to the entry and the level of the mapping.
+ *
+ * Note: We return pud and pmd either when the entry is marked large
+ * or when the present bit is not set. Otherwise we would return a
+ * pointer to a nonexisting mapping.
+ */
 pte_t *lookup_address(unsigned long address, int *level)
 {
 	pgd_t *pgd = pgd_offset_k(address);
@@ -206,7 +214,7 @@ pte_t *lookup_address(unsigned long address, int *level)
 		return NULL;
 
 	*level = PG_LEVEL_2M;
-	if (pmd_large(*pmd))
+	if (pmd_large(*pmd) || !pmd_present(*pmd))
 		return (pte_t *)pmd;
 
 	*level = PG_LEVEL_4K;