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Subject: Re: [PATCH v6 2/8] debugfs: prevent access to removed files' private
 data
To: Nicolai Stange <nicstange@gmail.com>
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Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Julia Lawall <Julia.Lawall@lip6.fr>,
        Gilles Muller <Gilles.Muller@lip6.fr>,
        Nicolas Palix <nicolas.palix@imag.fr>, Michal Marek <mmarek@suse.com>,
        linux-kernel@vger.kernel.org, cocci@systeme.lip6.fr
From: Sasha Levin <sasha.levin@oracle.com>
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Date: Wed, 18 May 2016 11:18:16 -0400
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On 05/18/2016 11:01 AM, Nicolai Stange wrote:
> Thanks a million for reporting!
> 
> 1.) Do you have lockdep enabled?

Yup, nothing there.

> 2.) Does this happen before or after userspace init has been spawned,
>     i.e. does the lockup happen at debugfs file creation time or
>     possibly at usage time?

So I looked closer, and it seems to happen after starting syzkaller, which
as far as I know tries to open many different debugfs files.

Is there debug code I can add it that'll help us figure out what's up?


Thanks,
Sasha