diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ad38648..ebe1811 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -671,12 +671,13 @@
 	unsigned long last_map_addr = 0;
 	unsigned long page_size_mask = 0;
 	unsigned long start_pfn, end_pfn;
+	unsigned long pos;
 
 	struct map_range mr[NR_RANGE_MR];
 	int nr_range, i;
 	int use_pse, use_gbpages;
 
-	printk(KERN_INFO "init_memory_mapping\n");
+	printk(KERN_INFO "init_memory_mapping: %016lx-%016lx\n", start, end);
 
 	/*
 	 * Find space for the kernel direct mapping tables.
@@ -710,35 +711,50 @@
 
 	/* head if not big page alignment ?*/
 	start_pfn = start >> PAGE_SHIFT;
-	end_pfn = ((start + (PMD_SIZE - 1)) >> PMD_SHIFT)
+	pos = start_pfn << PAGE_SHIFT;
+	end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
 			<< (PMD_SHIFT - PAGE_SHIFT);
-	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
+	if (start_pfn < end_pfn) {
+		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
+		pos = end_pfn << PAGE_SHIFT;
+	}
 
 	/* big page (2M) range*/
-	start_pfn = ((start + (PMD_SIZE - 1))>>PMD_SHIFT)
+	start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
 			 << (PMD_SHIFT - PAGE_SHIFT);
-	end_pfn = ((start + (PUD_SIZE - 1))>>PUD_SHIFT)
+	end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
 			 << (PUD_SHIFT - PAGE_SHIFT);
-	if (end_pfn > ((end>>PUD_SHIFT)<<(PUD_SHIFT - PAGE_SHIFT)))
-		end_pfn = ((end>>PUD_SHIFT)<<(PUD_SHIFT - PAGE_SHIFT));
-	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
-			page_size_mask & (1<<PG_LEVEL_2M));
+	if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
+		end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
+	if (start_pfn < end_pfn) {
+		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
+				page_size_mask & (1<<PG_LEVEL_2M));
+		pos = end_pfn << PAGE_SHIFT;
+	}
 
 	/* big page (1G) range */
-	start_pfn = end_pfn;
-	end_pfn = (end>>PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
-	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
+	start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
+			 << (PUD_SHIFT - PAGE_SHIFT);
+	end_pfn = (end >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
+	if (start_pfn < end_pfn) {
+		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 				page_size_mask &
 				 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
+		pos = end_pfn << PAGE_SHIFT;
+	}
 
 	/* tail is not big page (1G) alignment */
-	start_pfn = end_pfn;
-	end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
-	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
-			page_size_mask & (1<<PG_LEVEL_2M));
+	start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
+			 << (PMD_SHIFT - PAGE_SHIFT);
+	end_pfn = (end >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
+	if (start_pfn < end_pfn) {
+		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
+				page_size_mask & (1<<PG_LEVEL_2M));
+		pos = end_pfn << PAGE_SHIFT;
+	}
 
 	/* tail is not big page (2M) alignment */
-	start_pfn = end_pfn;
+	start_pfn = pos>>PAGE_SHIFT;
 	end_pfn = end>>PAGE_SHIFT;
 	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);