tree: https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git idmapped_mounts head: c31a7b55b2be330464b2a79a13b30f84ebd48b0f commit: f0b285928ebdeb56d8b9895a17c77512e5e02a53 [5/34] fs: introduce MOUNT_ATTR_IDMAP config: x86_64-randconfig-c002-20201029 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/... git remote add brauner https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git git fetch --no-tags brauner idmapped_mounts git checkout f0b285928ebdeb56d8b9895a17c77512e5e02a53 # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from <command-line>:32: ./usr/include/linux/mount.h:126:2: error: unknown type name '__u64' 126 | __u64 attr_set; | ^~~~~ ./usr/include/linux/mount.h:127:2: error: unknown type name '__u64' 127 | __u64 attr_clr; | ^~~~~ ./usr/include/linux/mount.h:128:2: error: unknown type name '__u64' 128 | __u64 propagation; | ^~~~~ 129 | __u32 userns; | ^~~~~ ./usr/include/linux/mount.h:130:2: error: unknown type name '__u32' 130 | __u32 reserved[0]; | ^~~~~ --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org