From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758148Ab0KRUu7 (ORCPT ); Thu, 18 Nov 2010 15:50:59 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:51494 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443Ab0KRUu6 (ORCPT ); Thu, 18 Nov 2010 15:50:58 -0500 Date: Thu, 18 Nov 2010 12:51:23 -0800 (PST) Message-Id: <20101118.125123.241932424.davem@davemloft.net> To: npiggin@kernel.dk Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 01/28] fs: d_validate fixes From: David Miller In-Reply-To: <20101116142028.254946611@kernel.dk> References: <20101116140900.039761100@kernel.dk> <20101116142028.254946611@kernel.dk> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nick Piggin Date: Wed, 17 Nov 2010 01:09:01 +1100 > d_validate has been broken for a long time. > > kmem_ptr_validate does not guarantee that a pointer can be dereferenced > if it can go away at any time. Even rcu_read_lock doesn't help, because > the pointer might be queued in RCU callbacks but not executed yet. > > So the parent cannot be checked, nor the name hashed. The dentry pointer > can not be touched until it can be verified under lock. Hashing simply > cannot be used. > > Instead, verify the parent/child relationship by traversing parent's > d_child list. It's slow, but only ncpfs and the destaged smbfs care > about it, at this point. > > Signed-off-by: Nick Piggin This won't apply because is conflicts with Christoph Hellwig's RCU conversion of d_validate(). Which is a change that went in more than a month ago. Thus I'd really appreciate if you mentioned what tree your patches are against in your "0/N" posting, always. Thanks.