x86: memtest: WARN if bad RAM found

Since this is not a particularly thorough test, if we find any bad
bits of RAM then there is a fair chance that there are other bad bits
we fail to detect.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

mm/memtest.c

@@ -31,6 +31,10 @@ static u64 patterns[] __initdata = {
 
 static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
 {
+#ifdef CONFIG_X86
+	WARN_ONCE(1, "Bad RAM detected. Use memtest86+ to perform a thorough test\n"
+		  "and the memmap= parameter to reserve the bad areas.");
+#endif
 	pr_info("  %016llx bad mem addr %pa - %pa reserved\n",
 		cpu_to_be64(pattern), &start_bad, &end_bad);
 	memblock_reserve(start_bad, end_bad - start_bad);