Hi Michal, url: https://github.com/0day-ci/linux/commits/Michal-Rostecki/Add-roundrobin-r... base: 92bf22614b21a2706f4993b278017e437f7785b3 config: i386-randconfig-m021-20210209 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; Reported-by: Dan Carpenter <dan.carpenter(a)oracle.com&gt; New smatch warnings: fs/btrfs/volumes.c:635 btrfs_check_mixed() error: uninitialized symbol 'prev_device'. Old smatch warnings: fs/btrfs/volumes.c:1264 open_fs_devices() error: we previously assumed 'latest_dev' could be null (see line 1252) vim +/prev_device +635 fs/btrfs/volumes.c bd7608b9a9bbf6 Michal Rostecki 2021-02-09 629 static bool btrfs_check_mixed(struct btrfs_fs_devices *fs_devices, bd7608b9a9bbf6 Michal Rostecki 2021-02-09 630 bool new_device_rotating) bd7608b9a9bbf6 Michal Rostecki 2021-02-09 631 { bd7608b9a9bbf6 Michal Rostecki 2021-02-09 632 struct btrfs_device *device, *prev_device; bd7608b9a9bbf6 Michal Rostecki 2021-02-09 633 bd7608b9a9bbf6 Michal Rostecki 2021-02-09 634 list_for_each_entry(device, &fs_devices->devices, dev_list) { bd7608b9a9bbf6 Michal Rostecki 2021-02-09 @635 if (prev_device == NULL && ^^^^^^^^^^^^^^^^^^^ Uninitialized. bd7608b9a9bbf6 Michal Rostecki 2021-02-09 636 device->rotating != new_device_rotating) bd7608b9a9bbf6 Michal Rostecki 2021-02-09 637 return true; bd7608b9a9bbf6 Michal Rostecki 2021-02-09 638 if (prev_device != NULL && bd7608b9a9bbf6 Michal Rostecki 2021-02-09 639 (device->rotating != prev_device->rotating || bd7608b9a9bbf6 Michal Rostecki 2021-02-09 640 device->rotating != new_device_rotating)) bd7608b9a9bbf6 Michal Rostecki 2021-02-09 641 return true; bd7608b9a9bbf6 Michal Rostecki 2021-02-09 642 bd7608b9a9bbf6 Michal Rostecki 2021-02-09 643 prev_device = device; bd7608b9a9bbf6 Michal Rostecki 2021-02-09 644 } bd7608b9a9bbf6 Michal Rostecki 2021-02-09 645 bd7608b9a9bbf6 Michal Rostecki 2021-02-09 646 return false; bd7608b9a9bbf6 Michal Rostecki 2021-02-09 647 } --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org