Re: [linux-next:master 7315/10599] ld.lld: error: undefined symbol: _copy_from_user

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Nov 20, 2025 at 08:52:07PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   88cbd8ac379cf5ce68b7efcfd4d1484a6871ee0b
> commit: d99dc586ca7c7729450af2ed39ca1483c0eb7b5c [7315/10599] uaccess: decouple INLINE_COPY_FROM_USER and CONFIG_RUST
> config: loongarch-randconfig-6002-20251120 (https://download.01.org/0day-ci/archive/20251120/202511202005.7GzetV3D-lkp@intel.com/config)
> compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
> rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251120/202511202005.7GzetV3D-lkp@intel.com/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@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202511202005.7GzetV3D-lkp@intel.com/
> 
> Note: the linux-next/master HEAD 88cbd8ac379cf5ce68b7efcfd4d1484a6871ee0b builds fine.
>       It may have been fixed somewhere.
> 
> All errors (new ones prefixed by >>):
> 
> >> ld.lld: error: undefined symbol: _copy_from_user
>    >>> referenced by uaccess.rs:306 (rust/kernel/uaccess.rs:306)
>    >>>               samples/rust/rust_misc_device.o:(<kernel::uaccess::UserSliceReader>::read::<i32>) in archive vmlinux.a
>    >>> referenced by uaccess.rs:306 (rust/kernel/uaccess.rs:306)
>    >>>               drivers/android/binder/rust_binder_main.o:(<kernel::uaccess::UserSliceReader>::read::<rust_binder_main::defs::BinderWriteRead>) in archive vmlinux.a
>    >>> referenced by uaccess.rs:306 (rust/kernel/uaccess.rs:306)
>    >>>               drivers/android/binder/rust_binder_main.o:(<kernel::uaccess::UserSliceReader>::read::<rust_binder_main::defs::BinderFreezeInfo>) in archive vmlinux.a
>    >>> referenced 24 more times
> --
> >> ld.lld: error: undefined symbol: _copy_to_user
>    >>> referenced by uaccess.rs:458 (rust/kernel/uaccess.rs:458)
>    >>>               samples/rust/rust_misc_device.o:(<kernel::uaccess::UserSliceWriter>::write::<i32>) in archive vmlinux.a
>    >>> referenced by uaccess.rs:458 (rust/kernel/uaccess.rs:458)
>    >>>               samples/rust/rust_misc_device.o:(<rust_misc_device::RustMiscDevice as kernel::miscdevice::MiscDevice>::ioctl) in archive vmlinux.a
>    >>> referenced by uaccess.rs:458 (rust/kernel/uaccess.rs:458)
>    >>>               drivers/android/binder/rust_binder_main.o:(<kernel::uaccess::UserSliceWriter>::write::<rust_binder_main::defs::BinderVersion>) in archive vmlinux.a
>    >>> referenced 15 more times
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

This is a known issue:
https://lore.kernel.org/all/20251118173250.2821388-1-aliceryhl@google.com/