--- arch/um/sys-x86_64/Makefile

+++ arch/um/sys-x86_64/Makefile

@@ -8,7 +8,8 @@ obj-y = bug.o bugs.o delay.o fault.o ldt

setjmp.o signal.o stub.o stub_segv.o syscalls.o syscall_table.o \

sysrq.o ksyms.o tls.o

-subarch-obj-y = lib/csum-partial_64.o lib/memcpy_64.o lib/thunk_64.o

+subarch-obj-y = lib/csum-partial_64.o lib/memcpy_64.o lib/thunk_64.o \

+ lib/rwsem_64.o

subarch-obj-$(CONFIG_MODULES) += kernel/module.o

ldt-y = ../sys-i386/ldt.o