Hi "Christian,

I love your patch! Yet something to improve:

[auto build test ERROR on drm-intel/for-linux-next]
[also build test ERROR on staging/staging-testing linux/master linus/master v5.9-rc8 next-20201008]
[cannot apply to mmotm/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Christian-K-nig/mm-introduce-vma_set_file-function-v2/20201008-192433
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
config: arm-randconfig-r021-20201008 (attached as .config)
compiler: arm-linux-gnueabi-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://github.com/0day-ci/linux/commit/839555b050d42ba052565bb71a11223e3d649c7a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Christian-K-nig/mm-introduce-vma_set_file-function-v2/20201008-192433
        git checkout 839555b050d42ba052565bb71a11223e3d649c7a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 

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

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: drivers/dma-buf/dma-buf.o: in function `dma_buf_mmap':
   drivers/dma-buf/dma-buf.c:1166: undefined reference to `vma_set_file'
>> arm-linux-gnueabi-ld: drivers/dma-buf/dma-buf.c:1172: undefined reference to `vma_set_file'

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