tree: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-5.8/block head: 870c153cf0e6df1b8b5226af41b19945e8e0d143 commit: e6249cdd46e43a7d3bdb8cce5fe24565d6c11e94 [60/79] block: add blk_io_schedule() for avoiding task hung in sync dio config: m68k-allnoconfig (attached as .config) compiler: m68k-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout e6249cdd46e43a7d3bdb8cce5fe24565d6c11e94 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=m68k If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; Note: the block/for-5.8/block HEAD 870c153cf0e6df1b8b5226af41b19945e8e0d143 builds fine. It only hurts bisectibility. All errors (new ones prefixed by >>, old ones prefixed by <<): In file included from include/linux/backing-dev.h:15, from fs/open.c:16: include/linux/blkdev.h: In function 'blk_io_schedule': 1834 | unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/blkdev.h:1834:26: note: each undeclared identifier is reported only once for each function it appears in vim +/sysctl_hung_task_timeout_secs +1834 include/linux/blkdev.h 1830 1831 static inline void blk_io_schedule(void) 1832 { 1833 /* Prevent hang_check timer from firing at us during very long I/O */ 1835 1836 if (timeout) 1837 io_schedule_timeout(timeout); 1838 else 1839 io_schedule(); 1840 } 1841 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org