Date: Mon, 18 Dec 2017 15:53:51 -0600
From: Bruno Wolff III <bruno@wolff.to>
To: weiping zhang <zwp10758@gmail.com>
Cc: Laura Abbott <labbott@redhat.com>, Jan Kara <jack@suse.cz>,
        Jens Axboe <axboe@kernel.dk>, linux-mm@kvack.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        regressions@leemhuis.info, linux-block@vger.kernel.org
Subject: Re: Regression with a0747a859ef6 ("bdi: add error handle for
 bdi_debug_register")
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On Sun, Dec 17, 2017 at 21:43:50 +0800,
  weiping zhang <zwp10758@gmail.com> wrote:
>Hi, thanks for testing, I think you first reproduce this issue(got WARNING
>at device_add_disk) by your own build, then add my debug patch.

I'm going to try testing warnings with a kernel I've built, to try to 
determine if warnings are working at all for the ones I'm building. However 
it might be that the WARN_ONs are not being reached for the kernels I've 
built. If that turns out to be the case, I may not be able to get you both 
the output from the WARN_ONs and the output from your debugging patch at 
the same time.
My next kernel build isn't going to finish in time to test today.