diff --git a/arch/x86/mm/memtest.c b/arch/x86/mm/memtest.c
new file mode 100644
index 0000000..672e17f
--- /dev/null
+++ b/arch/x86/mm/memtest.c
@@ -0,0 +1,123 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/pfn.h>
+
+#include <asm/e820.h>
+
+static void __init memtest(unsigned long start_phys, unsigned long size,
+				 unsigned pattern)
+{
+	unsigned long i;
+	unsigned long *start;
+	unsigned long start_bad;
+	unsigned long last_bad;
+	unsigned long val;
+	unsigned long start_phys_aligned;
+	unsigned long count;
+	unsigned long incr;
+
+	switch (pattern) {
+	case 0:
+		val = 0UL;
+		break;
+	case 1:
+		val = -1UL;
+		break;
+	case 2:
+#ifdef CONFIG_X86_64
+		val = 0x5555555555555555UL;
+#else
+		val = 0x55555555UL;
+#endif
+		break;
+	case 3:
+#ifdef CONFIG_X86_64
+		val = 0xaaaaaaaaaaaaaaaaUL;
+#else
+		val = 0xaaaaaaaaUL;
+#endif
+		break;
+	default:
+		return;
+	}
+
+	incr = sizeof(unsigned long);
+	start_phys_aligned = ALIGN(start_phys, incr);
+	count = (size - (start_phys_aligned - start_phys))/incr;
+	start = __va(start_phys_aligned);
+	start_bad = 0;
+	last_bad = 0;
+
+	for (i = 0; i < count; i++)
+		start[i] = val;
+	for (i = 0; i < count; i++, start++, start_phys_aligned += incr) {
+		if (*start != val) {
+			if (start_phys_aligned == last_bad + incr) {
+				last_bad += incr;
+			} else {
+				if (start_bad) {
+					printk(KERN_CONT "\n  %010lx bad mem addr %010lx - %010lx reserved",
+						val, start_bad, last_bad + incr);
+					reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+				}
+				start_bad = last_bad = start_phys_aligned;
+			}
+		}
+	}
+	if (start_bad) {
+		printk(KERN_CONT "\n  %016lx bad mem addr %010lx - %010lx reserved",
+			val, start_bad, last_bad + incr);
+		reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+	}
+
+}
+
+/* default is disabled */
+static int memtest_pattern __initdata;
+
+static int __init parse_memtest(char *arg)
+{
+	if (arg)
+		memtest_pattern = simple_strtoul(arg, NULL, 0);
+	return 0;
+}
+
+early_param("memtest", parse_memtest);
+
+void __init early_memtest(unsigned long start, unsigned long end)
+{
+	u64 t_start, t_size;
+	unsigned pattern;
+
+	if (!memtest_pattern)
+		return;
+
+	printk(KERN_INFO "early_memtest: pattern num %d", memtest_pattern);
+	for (pattern = 0; pattern < memtest_pattern; pattern++) {
+		t_start = start;
+		t_size = 0;
+		while (t_start < end) {
+			t_start = find_e820_area_size(t_start, &t_size, 1);
+
+			/* done ? */
+			if (t_start >= end)
+				break;
+			if (t_start + t_size > end)
+				t_size = end - t_start;
+
+			printk(KERN_CONT "\n  %010llx - %010llx pattern %d",
+				(unsigned long long)t_start,
+				(unsigned long long)t_start + t_size, pattern);
+
+			memtest(t_start, t_size, pattern);
+
+			t_start += t_size;
+		}
+	}
+	printk(KERN_CONT "\n");
+}