diff --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c
index 1cf466d..45113d5 100644
--- a/arch/i386/kernel/cpu/mtrr/main.c
+++ b/arch/i386/kernel/cpu/mtrr/main.c
@@ -631,6 +631,70 @@ static struct sysdev_driver mtrr_sysdev_driver = {
 	.resume		= mtrr_restore,
 };
 
+/**
+ * mtrr_page_wb - check if a given page is marked WB in an MTRR range
+ * @page: page to check
+ *
+ * See if @page is marked as WB in an MTRR, assuming the default non-MTRR
+ * covered memory is marked uncached.
+ *
+ * RETURNS
+ *
+ * True if page is marked WB, false otherwise.
+ */
+static bool __init mtrr_page_wb(struct page *page)
+{
+	struct mtrr_value mtrr;
+	int i, wb = 0;
+
+	/* FIXME: check fixed ranges too? */
+	for (i = 0; i < num_var_ranges; i++) {
+		mtrr_if->get(i, &mtrr.lbase, &mtrr.lsize, &mtrr.ltype);
+
+		/* Is the page in the current MTRR range? */
+		if (page_to_phys(page) + PAGE_SIZE <= mtrr.lbase + mtrr.lsize &&
+		    page_to_phys(page) >= mtrr.lbase) {
+			/* Ok, now check the memory type... */
+			if (mtrr.ltype == MTRR_TYPE_WRBACK)
+				wb = 1;
+			else
+				return false;
+		}
+	}
+
+	/* Assume if we didn't find a matching MTRR, it must be uncached */
+	return wb;
+}
+
+/**
+ * verify_mtrr_ranges - check MTRRs against memory map
+ *
+ * Make sure MTRR WB ranges match our memory map.  If they don't, disable
+ * any memory marked uncached that should be WB and warn the user.
+ */
+static void __init verify_mtrr_ranges(void)
+{
+	pg_data_t *pgdat;
+	int i, pages_disabled = 0;
+
+	printk(KERN_ERR "Verifying MTRR ranges against memory map\n");
+
+	for_each_online_pgdat(pgdat)
+		for (i = 0; i < pgdat->node_present_pages; i++) {
+			struct page *page = pgdat_page_nr(pgdat, i);
+			if (!mtrr_page_wb(page)) {
+				pages_disabled++;
+				SetPageReserved(page);
+			}
+		}
+
+	if (pages_disabled) {
+		printk(KERN_WARNING "MTRRs don't cover all of RAM, removing "
+		       "%dk from available memory\n",
+		       pages_disabled << PAGE_SHIFT);
+		msleep(100000);
+	}
+}
 
 /**
  * mtrr_bp_init - initialize mtrrs on the boot CPU
@@ -705,6 +769,7 @@ void mtrr_bp_init(void)
 		init_table();
 		if (use_intel())
 			get_mtrr_state();
+		verify_mtrr_ranges();
 	}
 }