Re: [PATCH] mm: add mmap_prepare() compatibility layer for nested file systems

[Lorenzo Stoakes]

On Tue, Jun 10, 2025 at 12:13:08AM +0800, kernel test robot wrote:
> Hi Lorenzo,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on akpm-mm/mm-everything]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Lorenzo-Stoakes/mm-add-mmap_prepare-compatibility-layer-for-nested-file-systems/20250609-172628
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20250609092413.45435-1-lorenzo.stoakes%40oracle.com
> patch subject: [PATCH] mm: add mmap_prepare() compatibility layer for nested file systems
> config: arm-randconfig-002-20250609 (https://download.01.org/0day-ci/archive/20250610/202506100000.34KZcoZ5-lkp@xxxxxxxxx/config)
> compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250610/202506100000.34KZcoZ5-lkp@xxxxxxxxx/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202506100000.34KZcoZ5-lkp@xxxxxxxxx/
>
> All errors (new ones prefixed by >>):
>
> >> ld.lld: error: undefined symbol: compat_vma_mmap_prepare
>    >>> referenced by shm.c
>    >>>               ipc/shm.o:(shm_mmap) in archive vmlinux.a
>    >>> referenced by backing-file.c
>    >>>               fs/backing-file.o:(backing_file_mmap) in archive vmlinux.a
>    >>> referenced by nommu.c
>    >>>               mm/nommu.o:(do_mmap) in archive vmlinux.a
>    >>> referenced 2 more times

Yeah of course yet again it's nommu doing what it always does - causing
maintenance pain for little to no apparent benefit.

I'll send a fix-patch.

>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki