Hi Michal,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   3e08a95294a4fb3702bb3d35ed08028433c37fe6
commit: 2602276d3d3811b1a48c48113042cd75fcbfc27d microblaze: Wire CMA allocator
date:   5 months ago
config: microblaze-randconfig-r031-20200624 (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 2602276d3d3811b1a48c48113042cd75fcbfc27d
        # 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_contig_range':
>> (.text+0x14c08): undefined reference to `start_isolate_page_range'
>> microblaze-linux-ld: (.text+0x14cec): undefined reference to `undo_isolate_page_range'
>> microblaze-linux-ld: (.text+0x14e54): undefined reference to `test_pages_isolated'
   microblaze-linux-ld: (.text+0x14ee8): undefined reference to `undo_isolate_page_range'
   microblaze-linux-ld: (.text+0x14f4c): undefined reference to `undo_isolate_page_range'

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