Hi Dan, I love your patch! Yet something to improve: [auto build test ERROR on dm/for-next] [also build test ERROR on linus/master v5.9-rc5 next-20200917] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Dan-Williams/dm-Call-proper-help... base: https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next config: mips-allyesconfig (attached as .config) compiler: mips-linux-gcc (GCC) 9.3.0 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 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): drivers/dax/super.c:69:6: warning: no previous prototype for '__generic_fsdax_supported' [-Wmissing-prototypes] 69 | bool __generic_fsdax_supported(struct dax_device *dax_dev, | ^~~~~~~~~~~~~~~~~~~~~~~~~ drivers/dax/super.c:167:6: warning: no previous prototype for '__bdev_dax_supported' [-Wmissing-prototypes] 167 | bool __bdev_dax_supported(struct block_device *bdev, int blocksize) | ^~~~~~~~~~~~~~~~~~~~ 325 | bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev, | ^~~~~~~~~~~~~ In file included from drivers/dax/super.c:16: include/linux/dax.h:162:20: note: previous definition of 'dax_supported' was here 162 | static inline bool dax_supported(struct dax_device *dax_dev, | ^~~~~~~~~~~~~ drivers/dax/super.c:451:6: warning: no previous prototype for 'run_dax' [-Wmissing-prototypes] 451 | void run_dax(struct dax_device *dax_dev) | ^~~~~~~ # https://github.com/0day-ci/linux/commit/36000760ad7496d92b34294192ae5dd7d... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Dan-Williams/dm-Call-proper-helper-to-determine-dax-support/20200918-135024 git checkout 36000760ad7496d92b34294192ae5dd7da0eeb27 vim +/dax_supported +325 drivers/dax/super.c b0686260fecaa92 Dan Williams 2017-01-26 324 7bf7eac8d648057 Dan Williams 2019-05-16 @325 bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev, 7bf7eac8d648057 Dan Williams 2019-05-16 326 int blocksize, sector_t start, sector_t len) 7bf7eac8d648057 Dan Williams 2019-05-16 327 { 36000760ad7496d Jan Kara 2020-09-17 328 if (!dax_dev) 36000760ad7496d Jan Kara 2020-09-17 329 return false; 36000760ad7496d Jan Kara 2020-09-17 330 7bf7eac8d648057 Dan Williams 2019-05-16 331 if (!dax_alive(dax_dev)) 7bf7eac8d648057 Dan Williams 2019-05-16 332 return false; 7bf7eac8d648057 Dan Williams 2019-05-16 333 7bf7eac8d648057 Dan Williams 2019-05-16 334 return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len); 7bf7eac8d648057 Dan Williams 2019-05-16 335 } 36000760ad7496d Jan Kara 2020-09-17 336 EXPORT_SYMBOL_GPL(dax_supported); 7bf7eac8d648057 Dan Williams 2019-05-16 337 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org