reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/intel-lab-lkp/linux/commit/f2b3f56fe3597cb1fb3344f47d61760dc370d7ab
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Charles-Han/kernel-sysctl-test-Fix-potential-null-dereference-in-sysctl-test/20250110-181004
        git checkout f2b3f56fe3597cb1fb3344f47d61760dc370d7ab
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 SHELL=/bin/bash kernel/