Hi Nicholas,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on arm64/for-next/core linus/master v5.10-rc5]
[cannot apply to hnaz-linux-mm/master next-20201127]
[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/Nicholas-Piggin/huge-vmalloc-mappings/20201128-232946
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: microblaze-randconfig-r035-20201128 (attached as .config)
compiler: microblaze-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://github.com/0day-ci/linux/commit/95e5da88c21d305af971ed4f00112f0576c2b94f
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Nicholas-Piggin/huge-vmalloc-mappings/20201128-232946
        git checkout 95e5da88c21d305af971ed4f00112f0576c2b94f
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=microblaze 

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 >>):

   microblaze-linux-ld: mm/page_alloc.o: in function `alloc_large_system_hash':
>> (.init.text+0x4144): undefined reference to `find_vm_area'

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