Hi Masahiro, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 7af08140979a6e7e12b78c93b8625c8d25b084e2 commit: ea29b20a828511de3348334e529a3d046a180416 init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM date: 5 weeks ago config: s390-randconfig-s032-20210420 (attached as .config) compiler: s390-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 # apt-get install sparse # sparse version: v0.6.3-341-g8af24329-dirty # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout ea29b20a828511de3348334e529a3d046a180416 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) drivers/watchdog/at91rm9200_wdt.c:219:27: sparse: expected long ( *write )( ... ) drivers/watchdog/at91rm9200_wdt.c:219:27: sparse: got long ( * )( ... ) vim +219 drivers/watchdog/at91rm9200_wdt.c 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 211 62322d2554d2f9 drivers/char/watchdog/at91_wdt.c Arjan van de Ven 2006-07-03 212 static const struct file_operations at91wdt_fops = { 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 213 .owner = THIS_MODULE, 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 214 .llseek = no_llseek, 2760600da2a13d drivers/watchdog/at91rm9200_wdt.c Alan Cox 2008-05-19 215 .unlocked_ioctl = at91_wdt_ioctl, b6dfb2477fb0bf drivers/watchdog/at91rm9200_wdt.c Arnd Bergmann 2019-06-03 216 .compat_ioctl = compat_ptr_ioctl, 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 217 .open = at91_wdt_open, 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 218 .release = at91_wdt_close, 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 @219 .write = at91_wdt_write, 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 220 }; 853807fb500a94 drivers/char/watchdog/at91_wdt.c Andrew Victor 2006-03-14 221 :::::: The code at line 219 was first introduced by commit :::::: 853807fb500a9442d88646b7be92bfa51334f8e8 [WATCHDOG] at91_wdt.c - Atmel AT91RM9200 watchdog driver :::::: TO: Andrew Victor <andrew(a)sanpeople.com&gt; :::::: CC: Wim Van Sebroeck <wim(a)iguana.be&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org