As of commit 
dce44566192e ("mm/memtest: add ARCH_USE_MEMTEST"),
architectures must select ARCH_USE_MEMTESET to enable CONFIG_MEMTEST.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Fixes: f6e5aedf470b ("riscv: Add support for memtest")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
 
        select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
        select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
        select ARCH_SUPPORTS_HUGETLBFS if MMU
+       select ARCH_USE_MEMTEST
        select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
        select ARCH_WANT_FRAME_POINTERS
        select ARCH_WANT_HUGE_PMD_SHARE if 64BIT