From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754008AbYI3QOd (ORCPT ); Tue, 30 Sep 2008 12:14:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753079AbYI3QOY (ORCPT ); Tue, 30 Sep 2008 12:14:24 -0400 Received: from relay1.sgi.com ([192.48.171.29]:33639 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753080AbYI3QOX (ORCPT ); Tue, 30 Sep 2008 12:14:23 -0400 Message-ID: <48E2506C.7000406@sgi.com> Date: Tue, 30 Sep 2008 09:14:36 -0700 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ingo Molnar CC: Rusty Russell , Linus Torvalds , Yinghai Lu , David Miller , Alan.Brunelle@hp.com, tglx@linutronix.de, rjw@sisk.pl, Linux Kernel Mailing List , kernel-testers@vger.kernel.org, Andrew Morton , arjan@linux.intel.com, Jack Steiner Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected References: <200809251150.26760.rusty@rustcorp.com.au> <200809261525.30258.rusty@rustcorp.com.au> <48DC78F2.8060400@sgi.com> <20080927191653.GB18619@elte.hu> <48E0E73A.40803@sgi.com> <20080930110459.GB12529@elte.hu> In-Reply-To: <20080930110459.GB12529@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Mike Travis wrote: > >>> could you please send whatever .c changes you have already, so that >>> we can have a look at how the end result will look like? Doesnt have >>> to build, i'm just curious about how it looks like in practice, >>> semantically. >> >> I will, and the full "allyesconfig" does compile. And it's basically >> a benign change in that the functionality is still the same. I'm >> currently reordering it a bit to clean it up. > > btw., are the resulting instructions also expected to be the same? If > yes then you might want to verify it all by making sure the md5's of the > .o's do not change. > > (If that's not possible (gcc decides to compile it a bit differently) > then no big deal, just wanted to mention the possibility.) > > Ingo Well, not exactly... ;-) It does institute the new API change that specifies only pointers to cpumask's can be passed to functions and returned from functions. I really wanted the default cpumask_t to be a constant so those instances where the passed in cpumask is used as a read/write temp variable would be caught. But it started getting messy. One pain is: typedef struct __cpumask_s *cpumask_t; const cpumask_t xxx; is not the same as: typedef const struct __cpumask_s *const_cpumask_t; const_cpumask_t xxx; and I'm not exactly sure why. It came up when I tried to declare functions that returned a constant cpumask_t pointer (node_to_cpumask, cpumask_of_cpu, etc.) The other major change I'm contemplating is to remove "cpumask_t" completely (maybe cpumask_ptr_t?). This would force every instance of cpumask_t to be examined. (I found quite a few I had missed in my original edits when I added the task struct temp cpumask's.) Oh yeah, one question ... is "current" always valid? Thanks, Mike