Re: [PATCH v6 2/8] debugfs: prevent access to removed files' private data

[Greg Kroah-Hartman]

On Wed, May 18, 2016 at 11:18:16AM -0400, Sasha Levin wrote:
> 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?

Trying to figure out _which_ debugfs file is causing this would be
great, if at all possible.  strace?