Re: [PATCH v2 13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step

[James Houghton <jthoughton@google.com>]

On Sat, Feb 18, 2023 at 10:08 AM kernel test robot <lkp@intel.com> wrote:
>
> Hi James,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on next-20230217]
> [cannot apply to kvm/queue shuah-kselftest/next shuah-kselftest/fixes arnd-asm-generic/master linus/master kvm/linux-next v6.2-rc8 v6.2-rc7 v6.2-rc6 v6.2-rc8]
> [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#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230218-083216
> patch link:    https://lore.kernel.org/r/20230218002819.1486479-14-jthoughton%40google.com
> patch subject: [PATCH v2 13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step
> config: arm64-randconfig-r005-20230217 (https://download.01.org/0day-ci/archive/20230219/202302190101.aoXrbN26-lkp@intel.com/config)
> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project db89896bbbd2251fff457699635acbbedeead27f)
> 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
>         # install arm64 cross compiling tool for clang build
>         # apt-get install binutils-aarch64-linux-gnu
>         # https://github.com/intel-lab-lkp/linux/commit/7e55fe945a1b5f042746277050390bdeba9e22d2
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230218-083216
>         git checkout 7e55fe945a1b5f042746277050390bdeba9e22d2
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202302190101.aoXrbN26-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
> >> ld.lld: error: undefined symbol: hugetlb_walk_step
>    >>> referenced by hugetlb.c
>    >>>               mm/hugetlb.o:(__hugetlb_hgm_walk) in archive vmlinux.a
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests
>

This is fixed by providing a trivial definition of __hugetlb_hgm_walk
when !CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING. Will be done for v3.
hugetlb_walk_step() is only defined by architectures that support HGM.