Re: [linux-next:master 7003/7050] include/linux/virtio_config.h:113: undefined reference to `page_reporting_unregister'

[David Hildenbrand <david@redhat.com>]

On 10.03.20 16:08, Alexander Duyck wrote:
> On Tue, Mar 10, 2020 at 5:13 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> On 10.03.20 13:02, Anup Patel wrote:
>>> On Tue, Mar 10, 2020 at 3:56 PM David Hildenbrand <david@redhat.com> wrote:
>>>>
>>>> On 10.03.20 11:22, David Hildenbrand wrote:
>>>>> On 10.03.20 03:19, Alexander Duyck wrote:
>>>>>> On Sun, Mar 8, 2020 at 7:54 PM kbuild test robot <lkp@intel.com> wrote:
>>>>>>>
>>>>>>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
>>>>>>> head:   b86a6a241b7c60ca7a6ca4fb3c0d2aedbbf2c1b6
>>>>>>> commit: 120359931943d2b801ce51a1a045dcc0a5d1a55b [7003/7050] Merge branch 'akpm-current/current'
>>>>>>> config: riscv-randconfig-a001-20200308 (attached as .config)
>>>>>>> compiler: riscv64-linux-gcc (GCC) 7.5.0
>>>>>>> reproduce:
>>>>>>>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>>>>>>         chmod +x ~/bin/make.cross
>>>>>>>         git checkout 120359931943d2b801ce51a1a045dcc0a5d1a55b
>>>>>>>         # save the attached .config to linux build tree
>>>>>>>         GCC_VERSION=7.5.0 make.cross ARCH=riscv
>>>>>>>
>>>>>>> If you fix the issue, kindly add following tag
>>>>>>> Reported-by: kbuild test robot <lkp@intel.com>
>>>>>>>
>>>>>>> All errors (new ones prefixed by >>):
>>>>>>>
>>>>>>>    drivers/virtio/virtio_balloon.o: In function `leak_balloon':
>>>>>>>    drivers/virtio/virtio_balloon.c:281: undefined reference to `balloon_page_dequeue'
>>>>>>>    drivers/virtio/virtio_balloon.o: In function `__virtio_test_bit':
>>>>>>>>> include/linux/virtio_config.h:113: undefined reference to `page_reporting_unregister'
>>>>>>>    drivers/virtio/virtio_balloon.o: In function `virtio_cread32':
>>>>>>>    include/linux/virtio_config.h:423: undefined reference to `balloon_page_alloc'
>>>>>>>    drivers/virtio/virtio_balloon.o: In function `fill_balloon':
>>>>>>>>> drivers/virtio/virtio_balloon.c:233: undefined reference to `balloon_page_enqueue'
>>>>>>>    drivers/virtio/virtio_balloon.o: In function `__virtio_test_bit':
>>>>>>>>> include/linux/virtio_config.h:113: undefined reference to `page_reporting_register'
>>>>>>>    drivers/gpu/drm/virtio/virtgpu_drv.o: In function `virtio_gpu_remove':
>>>>>>>    drivers/gpu/drm/virtio/virtgpu_drv.c:139: undefined reference to `drm_dev_unplug'
>>>>>>>    drivers/gpu/drm/virtio/virtgpu_drv.c:140: undefined reference to `drm_atomic_helper_shutdown'
>>>>>>>    drivers/gpu/drm/virtio/virtgpu_drv.c:141: undefined reference to `drm_dev_put'
>>>>>>>    drivers/gpu/drm/virtio/virtgpu_drv.o: In function `virtio_gpu_probe':
>>>>>>
>>>>>> It looks like somehow the config has CONFIG_VIRTIO_BALLOON enabled,
>>>>>> but didn't select CONFIG_MEMORY_BALLOON nor CONFIG_PAGE_REPORTING That
>>>>>> shouldn't be possible since in drivers/virtio/Kconfig we have the
>>>>>> following:
>>>>>> config VIRTIO_BALLOON
>>>>>>         tristate "Virtio balloon driver"
>>>>>>         depends on VIRTIO
>>>>>>         select MEMORY_BALLOON
>>>>>>         select PAGE_REPORTING
>>>>>
>>>>> IMHO that's perfectly valid. You might want to have ballooning without
>>>>> page compaction (MEMORY_BALLOON). Same with PAGE_REPORTING.
>>>>>
>>>>> AFAIK, "select" will still allow you to disable these things - which
>>>>> used to work fine with MEMORY_BALLOON (did that myself when debugging a
>>>>> compaction issue).
>>>>>
>>>>
>>>> Correction: I disabled BALLOON_COMPACTION back then ... so ignore my
>>>> comment regarding that :)
>>>>
>>>> But we should be able to build VIRTIO_BALLOON without PAGE_REPORTING
>>>> somehow IMHO.
>>>
>>> I have moved all VIRTIO driver selection to defconfigs for RISC-V which was
>>> the case before.
>>>
>>> Here's the patch:
>>> https://patchwork.kernel.org/patch/11429217/
>>
>> Make perfect sense. Still I think we might want to have the option to
>> build without page reporting in the future, similar to building without
>> balloon compaction (which is another discussion).
> 
> As far as page reporting it would be pretty simple to make it so that
> we can build without having it enabled. It would just depend on how we
> want to go about it.
> 
> My past experience has been that you end up having to create a third
> Kconfig option that depends on VIRTIO_BALLOON and selects the other
> config item. Then it is just a matter of figuring out if we want to

Yes, came to the same conclusion.

> use the new define as a wrapper in the virtio balloon driver, or if we
> want to create stubbed-out versions of page reporting and balloon
> compaction.

At least balloon compaction has stubs but still requires special
handling in the balloon drivers (e.g., skip balloon mount etc.)

Nothing urgent.

-- 
Thanks,

David / dhildenb