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Subject: Re: unable to handle kernel paging request
To: Mark Gavalda <markgavalda@kinsta.com>, <linux-btrfs@vger.kernel.org>
References: <CAAwVk4ny29d5qEAEvv=ydGN9DudUpWDQxzusmW1FpdBpLeVDYA@mail.gmail.com>
From: Chris Mason <clm@fb.com>
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Date: Thu, 15 Sep 2016 12:05:16 -0400
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On 09/15/2016 10:08 AM, Mark Gavalda wrote:
> Hi,
>
> Bumped into the following one today; kernel 4.4.0-36-generic Ubuntu
> 16.4.1; CPU went to 100% and only a hard restart solved the issue.
> Since then everything's back to normal.
>
> Please let me know how can I help get to the bottom of this?

I saw similar traces when tracking down this bug:

https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/commit/?h=for-linus-4.8&id=cbd60aa7cd17d81a434234268c55192862147439

It's flagged for stable, so you'll get it with the next stable update, 
or you can apply it by hand and rebuild.

-chris