Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760785AbZFKP2h (ORCPT ); Thu, 11 Jun 2009 11:28:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759687AbZFKP2G (ORCPT ); Thu, 11 Jun 2009 11:28:06 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:41691 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758242AbZFKP2F (ORCPT ); Thu, 11 Jun 2009 11:28:05 -0400 Subject: Re: [PATCH 2/2] SLUB: Disable debugging if it increases the minimum page order From: Pekka Enberg To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, mel@csn.ul.ie, Larry.Finger@lwfinger.net In-Reply-To: References: <1244728824.17483.51.camel@penberg-laptop> <1244733119.17483.56.camel@penberg-laptop> Date: Thu, 11 Jun 2009 18:28:06 +0300 Message-Id: <1244734086.17483.59.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.24.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1313 Lines: 30 Hi Christoph, On Thu, 11 Jun 2009, Pekka Enberg wrote: > > I think my patch is the simplest solution here: it turns off debugging > > for those caches where the metadata bumps up the minimum allocation > > order and I suspect that we disable cache only for 4096 in practice. On Thu, 2009-06-11 at 11:20 -0400, Christoph Lameter wrote: > There could be other slab caches that would randomly be affected by this. > I ran a couple of times into situations where I had to hack slab to do > debugging of exempted slabs. Yes, I do understand that and I have hit that too in the past. But surely a printk() telling the user we disabled debugging can cure that? My main point is that a lot of _testers_ will probably enable all SLUB debugging by default because we encourage them to and it's pretty bad that we end up causing order 1 allocations and oom conditions. So I still think we need to fix _at minimum_ the kmalloc-4096 case (assuming Larry won't hit the same problem still). I see you're not happy with my patch so any suggestions how to handle that? Pekka -- 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/