Hi Geert, This is the build error I get, on Eric's userns tree. tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git userns-always-map-user-v45 head: 38a0b1b84f5f613ff4e01fffda27f87d4cb2b649 commit: 5ea9fc30545b658380d4794340227fe821b83701 [80/99] vfs: Add setns support for the mount namespace config: m68k-m5475evb_defconfig (attached as .config) All related error/warning messages: fs/namespace.c:2290:1: error: unknown type name 'atomic64_t' fs/namespace.c:2290:1: error: implicit declaration of function 'ATOMIC64_INIT' [-Werror=implicit-function-declaration] fs/namespace.c:2290:1: error: initializer element is not constant fs/namespace.c: In function 'alloc_mnt_ns': fs/namespace.c:2299:2: error: implicit declaration of function 'atomic64_add_return' [-Werror=implicit-function-declaration] cc1: some warnings being treated as errors vim +2290 fs/namespace.c 2287 * number incrementing at 10Ghz will take 12,427 years to wrap which 2288 * is effectively never, so we can ignore the possibility. 2289 */ > 2290 static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); 2291 2292 static struct mnt_namespace *alloc_mnt_ns(void) 2293 { --- 0-DAY kernel build testing backend Open Source Technology Centre Fengguang Wu Intel Corporation