diff --git a/[refs] b/[refs]
index 0a74292858dd..7e82ebcee37e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e1b4d1143651fb3838be1117785b6e0386fa151f
+refs/heads/master: ef5fa0ab24b87646c7bc98645acbb4b51fc2acd4
diff --git a/trunk/arch/x86/mm/iomap_32.c b/trunk/arch/x86/mm/iomap_32.c
index d0151d8ce452..ca53224fc56c 100644
--- a/trunk/arch/x86/mm/iomap_32.c
+++ b/trunk/arch/x86/mm/iomap_32.c
@@ -17,6 +17,7 @@
  */
 
 #include <asm/iomap.h>
+#include <asm/pat.h>
 #include <linux/module.h>
 
 /* Map 'pfn' using fixed map 'type' and protections 'prot'
@@ -29,6 +30,15 @@ iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
 
 	pagefault_disable();
 
+	/*
+	 * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
+	 * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
+	 * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
+	 * user, which is "WC if the MTRR is WC, UC if you can't do that."
+	 */
+	if (!pat_enabled && pgprot_val(prot) == pgprot_val(PAGE_KERNEL_WC))
+		prot = PAGE_KERNEL_UC_MINUS;
+
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 	set_pte(kmap_pte-idx, pfn_pte(pfn, prot));