Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756150AbXFTXCy (ORCPT ); Wed, 20 Jun 2007 19:02:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751352AbXFTXCn (ORCPT ); Wed, 20 Jun 2007 19:02:43 -0400 Received: from wa-out-1112.google.com ([209.85.146.177]:22737 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751121AbXFTXCm (ORCPT ); Wed, 20 Jun 2007 19:02:42 -0400 Message-ID: <5640c7e00706201602g5c983a34qf7644b19d6295d42@mail.gmail.com> Date: Thu, 21 Jun 2007 11:02:42 +1200 From: "Ian McDonald" To: "Linus Torvalds" Subject: Re: [1/2] 2.6.22-rc5: known regressions with patches Cc: "Andrew Morton" , LKML , "Miklos Szeredi" , "Ingo Molnar" , "Darrick J. Wong" , "Andi Kleen" , "Bj?rn Steinbrink" , "William Cohen" , "S. P. Prasanna" , "Antonino Daplas" , "Olaf Hering" , "Ville Syrj?l?" , "Jean Delvare" , "Rudolf Marek" , "Soeren Sonnenburg" , "Michal Piotrowski" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <467543FA.60905@googlemail.com> <5640c7e00706201508g3c1fc40eq82a1db05c9156b5d@mail.gmail.com> <5640c7e00706201541g3ecaf8c5i524d8b464d8fcc2d@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1433 Lines: 40 On 6/21/07, Linus Torvalds wrote: > And yes, sometimes debugging *does* change what it debugs. In timing, if > nothing else, but also in the kinds of things you can do. Totally agree. > For example, we > don't allow slab redzoning on data structures that have alignment > restrictions not compatible with the redzoning, and I'd argue that this is > more of the same: we just should not do DEBUG_RODATA if you expect to > change read-only data. > Well the description for DEBUG_RODATA is: Mark the kernel read-only data as write-protected in the pagetables, in order to catch accidental (and incorrect) writes to such const data. What we are doing with kprobes is neither accidental, nor incorrect. > There's just no *point*. > > Linus > I understand your philosophical viewpoint here. Anyway it's no biggie as can keep the patch out of tree if I want it... Another option is to be able to enable and disable protecting read only data via a sysctl but that seems even uglier. Anyway I'll stop wasting your time now. Ian -- Web: http://wand.net.nz/~iam4/ Blog: http://iansblog.jandi.co.nz WAND Network Research Group - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/