Date: Thu, 4 Apr 2013 21:44:59 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Nathan Zimmer <nzimmer@sgi.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        David Woodhouse <dwmw2@infradead.org>, stable@vger.kernel.org
Subject: Re: [PATCH resend] fs/proc: Move kfree outside pde_unload_lock
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On Thu, Apr 04, 2013 at 12:12:05PM -0500, Nathan Zimmer wrote:

> Ok I am cloning the tree now.
> It does look like the patches would conflict.
> I'll run some tests and take a deeper look.

FWIW, I've just pushed there a tentative patch that switches to hopefully
saner locking (head should be at cb673c115c1f99d3480471ca5d8cb3f89a1e3bee).
Is that more or less what you want wrt spinlock contention?

One note: for any given pde_opener, close_pdeo() can be called at most
by two threads - final fput() and remove_proc_entry() resp.  I think
the use of completion + flag is safe there; pde->pde_unload_lock
should serialize the critical areas.
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