Re: [PATCH v5 5/7] null_blk: allow non power of 2 zoned devices

[Nathan Chancellor <nathan@kernel.org>]

On Tue, May 24, 2022 at 09:30:41AM +0200, Pankaj Raghav wrote:
> On 5/24/22 04:40, kernel test robot wrote:
> > Hi Pankaj,
> > 
> > Thank you for the patch! Yet something to improve:
> > 
> > [auto build test ERROR on axboe-block/for-next]
> > [also build test ERROR on device-mapper-dm/for-next linus/master hch-configfs/for-next v5.18 next-20220523]
> > [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://protect2.fireeye.com/v1/url?k=8acc50e6-d557681b-8acddba9-000babff317b-0ca211d60a57a8c6&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fgithub.com%2Fintel-lab-lkp%2Flinux%2Fcommits%2FPankaj-Raghav%2Fblock-make-blkdev_nr_zones-and-blk_queue_zone_no-generic-for-npo2-zsze%2F20220524-011616
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
> > config: hexagon-randconfig-r045-20220523 (https://protect2.fireeye.com/v1/url?k=0dc32741-52581fbc-0dc2ac0e-000babff317b-fb6f258f0c80ebb9&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fdownload.01.org%2F0day-ci%2Farchive%2F20220524%2F202205241034.izkLMTcH-lkp%40intel.com%2Fconfig)
> > compiler: clang version 15.0.0 (https://protect2.fireeye.com/v1/url?k=afbb4f4f-f02077b2-afbac400-000babff317b-a4413fa4cefe1877&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fgithub.com%2Fllvm%2Fllvm-project 10c9ecce9f6096e18222a331c5e7d085bd813f75)
> > reproduce (this is a W=1 build):
> >         wget https://protect2.fireeye.com/v1/url?k=718573dc-2e1e4b21-7184f893-000babff317b-b6c06a1c569b0d77&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fraw.githubusercontent.com%2Fintel%2Flkp-tests%2Fmaster%2Fsbin%2Fmake.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # https://protect2.fireeye.com/v1/url?k=247d070f-7be63ff2-247c8c40-000babff317b-6fd7f2f6a5a5bc60&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fgithub.com%2Fintel-lab-lkp%2Flinux%2Fcommit%2F3d3c81da0adbd40eb0d2125327b7e227582b2a37
> >         git remote add linux-review https://protect2.fireeye.com/v1/url?k=081be8db-5780d026-081a6394-000babff317b-d12fdca0fccd0493&q=1&e=5ef82219-ef70-445f-a7d0-0ae0a30be69f&u=https%3A%2F%2Fgithub.com%2Fintel-lab-lkp%2Flinux
> >         git fetch --no-tags linux-review Pankaj-Raghav/block-make-blkdev_nr_zones-and-blk_queue_zone_no-generic-for-npo2-zsze/20220524-011616
> >         git checkout 3d3c81da0adbd40eb0d2125327b7e227582b2a37
> >         # save the config file
> >         mkdir build_dir && cp config build_dir/.config
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash
> > 
> > If you fix the issue, kindly add following tag where applicable
> > Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All errors (new ones prefixed by >>, old ones prefixed by <<):
> > 
> >>> ERROR: modpost: "__hexagon_umoddi3" [drivers/block/null_blk/null_blk.ko] undefined!
> 
> I am able to apply my patches cleanly against next-20220523, build it
> without any errors with GCC and boot into it in my x86_64 machine. Not
> sure why this error is popping up.

Do a 32-bit build and you'll see it. With GCC 12.1.0, ARCH=i386
defconfig + CONFIG_BLK_DEV_NULL_BLK=y + CONFIG_BLK_DEV_ZONED=y
reproduces it for me:

$ make -skj"$(nproc)" ARCH=i386 defconfig menuconfig all
ld: drivers/block/null_blk/zoned.o: in function `null_init_zoned_dev':
zoned.c:(.text+0x112e): undefined reference to `__umoddi3'
...

roundup() does a plain division with a 64-bit dividend, which will cause
issues with 32-bit architectures. I suspect that you should really be
using DIV_ROUND_UP_SECTOR_T() for the nr_zones calculation or maybe one
of the other rounding macros in include/linux/math.h but I am not sure.

Cheers,
Nathan