tree:   https://github.com/0day-ci/linux/commits/UPDATE-20210829-092430/Tetsuo-Handa/loop-replace-loop_ctl_mutex-with-loop_idr_spinlock/20210827-000519
head:   d1d1d6b0374667ffe7418416765eedda70f0b6a5
commit: d1d1d6b0374667ffe7418416765eedda70f0b6a5 loop: reduce the loop_ctl_mutex scope
date:   8 hours ago
config: arm-imx_v6_v7_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0
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
        # https://github.com/0day-ci/linux/commit/d1d1d6b0374667ffe7418416765eedda70f0b6a5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review UPDATE-20210829-092430/Tetsuo-Handa/loop-replace-loop_ctl_mutex-with-loop_idr_spinlock/20210827-000519
        git checkout d1d1d6b0374667ffe7418416765eedda70f0b6a5
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash

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 >>):

   arm-linux-gnueabi-ld: drivers/block/loop.o: in function `loop_control_ioctl':
>> loop.c:(.text+0xdcc): undefined reference to `__bad_cmpxchg'

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