From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753352AbYI1VAZ (ORCPT ); Sun, 28 Sep 2008 17:00:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751734AbYI1VAN (ORCPT ); Sun, 28 Sep 2008 17:00:13 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:38986 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751107AbYI1VAM (ORCPT ); Sun, 28 Sep 2008 17:00:12 -0400 Date: Sun, 28 Sep 2008 13:59:33 -0700 (PDT) From: Linus Torvalds To: Hugh Dickins cc: Al Viro , Alexey Dobriyan , ebiederm@xmission.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: 2.6.27-rc7-sha1: EIP at proc_sys_compare+0x36/0x50 In-Reply-To: Message-ID: References: <20080926152031.GA30831@x200.localdomain> <20080928141856.GG28946@ZenIV.linux.org.uk> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 28 Sep 2008, Linus Torvalds wrote: > > NOTE! Totally untested patch! It looks sane and really obvious, but maybe > it has some insane and non-obvious bug. Oh. I think I see at least a _potential_ insane and non-obvious bug: if somebody actually is going to do a __d_drop() _inside_ their d_compare(), this would fail horribly because we now assume that the dentry is still fine, since we held d_lock. Of course, I think that would be very very buggy of a filesystem to do (we don't even pass in the dentry as an argument - you have to figure it out from the qstr, and a filesystem really should not do that!), but /proc _does_ look up the dentry in question, maybe some other insane filesystem does too and then does the __d_drop. I'm not seeing it, though. So I still think the patch is sane and good, but somebody really needs to double- or triple-check me on it. Linus