Hi Jeff, [FYI, it's a private test report for your RFC patch.] [auto build test WARNING on miklos-vfs/overlayfs-next] [also build test WARNING on linus/master v5.10-rc7 next-20201211] [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/Jeff-Layton/errseq-overlayfs-acc... base: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next config: x86_64-randconfig-a016-20201213 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project d38205144febf4dc42c9270c6aa3d978f1ef65e1) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # https://github.com/0day-ci/linux/commit/89bd90a6b2a9bc40a46e9b9de68356e99... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Jeff-Layton/errseq-overlayfs-accomodate-the-volatile-upper-layer-use-case/20201213-213109 git checkout 89bd90a6b2a9bc40a46e9b9de68356e99cde04e8 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): ret = errseq_check(&upper_sb->s_wb_err, ofs->err_mark); ^~~~~~~~ fs/overlayfs/super.c:264:30: note: initialize the variable 'upper_sb' to silence this warning struct super_block *upper_sb; ^ = NULL 1 warning generated. vim +/upper_sb +272 fs/overlayfs/super.c 259 260 /* Sync real dirty inodes in upper filesystem (if it exists) */ 261 static int ovl_sync_fs(struct super_block *sb, int wait) 262 { 263 struct ovl_fs *ofs = sb->s_fs_info; 264 struct super_block *upper_sb; 265 int ret; 266 267 if (!ovl_upper_mnt(ofs)) 268 return 0; 269 270 if (!ovl_should_sync(ofs)) { 271 /* Propagate errors from upper to overlayfs */ 273 errseq_set(&sb->s_wb_err, ret); 274 return ret; 275 } 276 277 /* 278 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). 279 * All the super blocks will be iterated, including upper_sb. 280 * 281 * If this is a syncfs(2) call, then we do need to call 282 * sync_filesystem() on upper_sb, but enough if we do it when being 283 * called with wait == 1. 284 */ 285 if (!wait) 286 return 0; 287 288 upper_sb = ovl_upper_mnt(ofs)->mnt_sb; 289 290 down_read(&upper_sb->s_umount); 291 ret = sync_filesystem(upper_sb); 292 up_read(&upper_sb->s_umount); 293 294 return ret; 295 } 296 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org