x86: enable memory tester support on 32-bit

only supports memory below max_low_pfn.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/init_32.c

@@ -844,6 +844,9 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
 		reserve_early(table_start << PAGE_SHIFT,
 				 table_end << PAGE_SHIFT, "PGTABLE");
 
+	if (!after_init_bootmem)
+		early_memtest(start, end);
+
 	return end >> PAGE_SHIFT;
 }