[rcu:dev.2021.04.02a 73/73] ia64-linux-ld: undefined reference to `rcu_spawn_one_boost_kthread'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2021.04.02a
head:   4bc4fd6b7e87ff0bdb1aa2493af85be2784717c0
commit: 4bc4fd6b7e87ff0bdb1aa2493af85be2784717c0 [73/73] rcu: Fix RCU priority boosting and add more debug output
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
        # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=4bc4fd6b7e87ff0bdb1aa2493af85be2784717c0
        git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu dev.2021.04.02a
        git checkout 4bc4fd6b7e87ff0bdb1aa2493af85be2784717c0
        # 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 >>):

   ia64-linux-ld: kernel/rcu/tree.o: in function `rcutree_online_cpu':
   (.text+0xf922): undefined reference to `rcu_spawn_one_boost_kthread'
>> ia64-linux-ld: (.text+0xf9a2): undefined reference to `rcu_spawn_one_boost_kthread'
   ia64-linux-ld: (.text+0xfa32): undefined reference to `rcu_spawn_one_boost_kthread'

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

Attachment: .config.gz
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