[rcu:rcu/next 33/36] ERROR: modpost: "rcu_read_unlock_longwait" undefined!

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
head:   9035ae87fcb36d2a7c8872e1cc0a46c0c5b619a8
commit: bd6ae31d1b1f22ab7ff8376b416f09d93d9ef75d [33/36] rcutorture: Add the ability to torture RCU longsleep
config: x86_64-randconfig-r015-20210316 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=bd6ae31d1b1f22ab7ff8376b416f09d93d9ef75d
        git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu rcu/next
        git checkout bd6ae31d1b1f22ab7ff8376b416f09d93d9ef75d
        # 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@xxxxxxxxx>

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

>> ERROR: modpost: "rcu_read_unlock_longwait" [kernel/rcu/rcutorture.ko] undefined!
>> ERROR: modpost: "rcu_read_lock_longwait" [kernel/rcu/rcutorture.ko] undefined!
>> ERROR: modpost: "rcu_read_lock_longwait_held" [kernel/rcu/rcutorture.ko] undefined!

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Attachment: .config.gz
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