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Date: Tue, 27 Jan 2015 00:37:42 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 00/16 v3] tracing: Add new file system tracefs
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On Mon, Jan 26, 2015 at 06:43:14PM -0500, Steven Rostedt wrote:

> I originally had this, but the issue isn't with i_mutex only. The
> instance_mkdir and instance_rmdir need to grab trace_types_lock. This
> is also held when calling into tracefs.
> 
> That is, we can not hold i_mutex and take trace_types_lock.
> 
> trace_types_lock needs to be held with the creation or destruction of
> events, which is what mkdir an rmdir do.

Yecchhh...

Looks like something that fell out of BKL removal - AFAICS, you are using
it to protect all kinds of things ;-/