CC      kernel/power/poweroff.o
  LD      kernel/power/built-in.o
  CC      kernel/sched/bfs.o
In file included from kernel/sched/bfs.c:73:0:
include/linux/urwlock.h: In function ‘__urw_write_lock’:
include/linux/urwlock.h:42:2: error: implicit declaration of function ‘arch_write_lock’ [-Werror=implicit-function-declaration]
include/linux/urwlock.h: In function ‘__urw_write_unlock’:
include/linux/urwlock.h:48:2: error: implicit declaration of function ‘arch_write_unlock’ [-Werror=implicit-function-declaration]
include/linux/urwlock.h: In function ‘__urw_read_lock’:
include/linux/urwlock.h:54:2: error: implicit declaration of function ‘arch_read_lock’ [-Werror=implicit-function-declaration]
include/linux/urwlock.h: In function ‘__urw_read_unlock’:
include/linux/urwlock.h:60:2: error: implicit declaration of function ‘arch_read_unlock’ [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[2]: *** [kernel/sched/bfs.o] Error 1
make[1]: *** [kernel/sched] Error 2
make: *** [kernel] Error 2
==> ERROR: A failure occurred in build().
    Aborting...