ERROR: "min_low_pfn" undefined!

[kernel test robot]

Hi Arnd,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   b51594df17d0ce80b9f9f35394a1f42d7ac94472
commit: 710ec38b0f633ab3e2581f07a73442d809e28ab0 mm: add dummy can_do_mlock() helper
date:   11 months ago
config: microblaze-randconfig-r031-20200831 (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
        git checkout 710ec38b0f633ab3e2581f07a73442d809e28ab0
        # 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@xxxxxxxxx>

All errors (new ones prefixed by >>):

>> ERROR: "min_low_pfn" [drivers/rpmsg/virtio_rpmsg_bus.ko] undefined!
   ERROR: "min_low_pfn" [drivers/block/aoe/aoe.ko] undefined!

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

Attachment: .config.gz
Description: application/gzip