diff --git a/[refs] b/[refs]
index abae22ff2502..f7e6215db585 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9a007b3791cdba3601d835ea10e68c14115b9afb
+refs/heads/master: 2992e545ea006992ec9dc91c4fa996ce1e15f921
diff --git a/trunk/arch/x86/pci/i386.c b/trunk/arch/x86/pci/i386.c
index a70a85de5e84..52e656f17781 100644
--- a/trunk/arch/x86/pci/i386.c
+++ b/trunk/arch/x86/pci/i386.c
@@ -280,6 +280,15 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 		return -EINVAL;
 
 	prot = pgprot_val(vma->vm_page_prot);
+
+	/*
+ 	 * Return error if pat is not enabled and write_combine is requested.
+ 	 * Caller can followup with UC MINUS request and add a WC mtrr if there
+ 	 * is a free mtrr slot.
+ 	 */
+	if (!pat_enabled && write_combine)
+		return -EINVAL;
+
 	if (pat_enabled && write_combine)
 		prot |= _PAGE_CACHE_WC;
 	else if (pat_enabled || boot_cpu_data.x86 > 3)