Without CONFIG_DAX_DRIVER, drivers/md/dm-stripe.c fails to compile:
drivers/md/dm-stripe.c:515:27: error: 'stripe_dax_memcpy_toiovecend' undeclared here (not in a function)
.dax_memcpy_toiovecend = stripe_dax_memcpy_toiovecend,
^
CONFIG_DAX_DRIVER will be automaticallly selected by NVDIMM support,
which needs PHYS_ADDR_T_64BIT setup.
diff -up ./drivers/md/dm-stripe.c.dax ./drivers/md/dm-stripe.c
--- ./drivers/md/dm-stripe.c.dax 2018-10-05 05:18:19.000000000 +0900
+++ ./drivers/md/dm-stripe.c 2018-11-01 12:53:35.000000000 +0900
@@ -370,6 +370,7 @@ static int stripe_dax_memcpy_toiovecend(
#define stripe_dax_direct_access NULL
#define stripe_dax_memcpy_fromiovecend NULL
#define stripe_dax_memcpy_fromiovecend NULL
+#define stripe_dax_memcpy_toiovecend NULL
#endif
/*