ERROR: modpost: "rcu_idle_enter" undefined!

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   325d0eab4f31c6240b59d5b2b8042c88f59405b5
commit: 1fecfdbb7acc6624655450a609221c89b5197a06 ACPI: processor: Take over RCU-idle for C3-BM idle
date:   4 days ago
config: ia64-defconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 1fecfdbb7acc6624655450a609221c89b5197a06
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "rcu_idle_enter" [drivers/acpi/processor.ko] undefined!
>> ERROR: modpost: "rcu_idle_exit" [drivers/acpi/processor.ko] undefined!

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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip