From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1764174AbXFCGaF@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1764174AbXFCGaF (ORCPT <rfc822;w@1wt.eu>);
	Sun, 3 Jun 2007 02:30:05 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755173AbXFCG3z
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Sun, 3 Jun 2007 02:29:55 -0400
Received: from ug-out-1314.google.com ([66.249.92.175]:26420 "EHLO
	ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1755169AbXFCG3y (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 3 Jun 2007 02:29:54 -0400
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=beta;
        h=received:date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:in-reply-to:user-agent;
        b=pOLp0/jIY2lRXlW1lHNLbcnb6Zx0aFfkqOrRLWkM0vQu8g0Gq2hoxGBLAEuHajWdYbK9UGg8ONWvcdcitCLzKsF/OMeEa61u4oVIcNPtKGiTsGRyGBQiFzaTv89jy2jhiEg25Ved6tiEBsjvsMOEMl+oJclbxCWrIaN7WNHueoE=
Date: Sun, 3 Jun 2007 10:28:40 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>, Eric Sandeen <sandeen@sandeen.net>,
       Jan Kara <jack@suse.cz>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] Fix possible leakage of blocks in UDF
Message-ID: <20070603062840.GA8396@cvg>
References: <20070602063403.GA8387@cvg> <20070601235422.fdc1f750.akpm@linux-foundation.org> <20070602065923.GB8387@cvg> <20070602000645.508ddf93.akpm@linux-foundation.org> <20070602140619.GA10303@cvg> <20070602103203.e39d25ed.akpm@linux-foundation.org> <20070602185707.GA8518@cvg> <20070602121616.37ffce9e.akpm@linux-foundation.org> <20070602200146.GC8518@cvg> <20070602154942.cc4f9818.akpm@linux-foundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20070602154942.cc4f9818.akpm@linux-foundation.org>
User-Agent: Mutt/1.5.13 (2006-08-11)
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

[Andrew Morton - Sat, Jun 02, 2007 at 03:49:42PM -0700]
| On Sun, 3 Jun 2007 00:01:46 +0400 Cyrill Gorcunov <gorcunov@gmail.com> wrote:
| 
| > [Andrew Morton - Sat, Jun 02, 2007 at 12:16:16PM -0700]
| > [...snip...]
| > | 
| > | No, the problem is that the patch caused the kernel to take inode_lock
| > | within the newly-added drop_inode(), btu drop_inode() is already called
| > | under inode_lock.
| > | 
| > | It has nothing to do with lock_kernel() and it has nothing to do with
| > | sleeping.
| > | 
| > 
| > Andrew, the only call that could leading to subseq. inode_lock lock
| > is mark_inode_dirty() I guess (and that is snown by Eric's dump)
| > but as I shown you in my dbg print without SMP it's OK. So
| > is it SMP who lead to lock? How it depends on it? (I understand
| > that is a stupid question for you but if you have time explain
| > me this please ;)
| > 
| 
| When CONFIG_SMP=n, spin_lock() is a no-op.  (Except with CONFIG_PREEMPT=y,
| in which case spin_lock() will disable kernel preemption on SMP and non-SMP
| kernels)
| 
| When CONFIG_SMP=y, spin_lock() really does take a lock.  But if this thread
| already holds this lock, we'll deadlock.
| 

Thanks, Andrew. So the reason that raises lock problem is the calling of
mark_inode_dirty() inside drop_inode() (by indirection). And I see two way
of solution:

- or check for inode->i_count at each mark_inode_dirty that being called
  after drop_inode

		if (inode->i_count > 0)
				mark_inode_dirty()

- or wrap mark_inode_dirty as

	udf_mark_inode_dirty()
	{
		if (inode->i_count > 0)
			mark_inode_dirty();
	}

	and replace all mark_inode_dirty -> udf_mark_inode_dirty

Your thoughts?

		Cyrill