On Thu, Dec 14, 2017 at 18:09:27 +0800,
  weiping zhang <zhangweiping@didichuxing.com> wrote:
>
>It seems something wrong with bdi debugfs register, could you help
>test the forllowing debug patch, I add some debug log, no function
>change, thanks.

I applied your patch to d39a01eff9af1045f6e30ff9db40310517c4b45f and there 
were some new debug messages in the dmesg output. Hopefully this helps. I 
also added the patch and output to the Fedora bug for people following there.