Hi Wei,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.12 next-20170712]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Wei-Wang/Virtio-balloon-Enhancement/20170713-074956
config: powerpc-defconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

>> ERROR: ".xb_set_bit" [drivers/virtio/virtio_balloon.ko] undefined!
>> ERROR: ".xb_zero" [drivers/virtio/virtio_balloon.ko] undefined!
>> ERROR: ".xb_find_next_bit" [drivers/virtio/virtio_balloon.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation