From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161010AbWHAOqH (ORCPT ); Tue, 1 Aug 2006 10:46:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161024AbWHAOqG (ORCPT ); Tue, 1 Aug 2006 10:46:06 -0400 Received: from smtp.osdl.org ([65.172.181.4]:64216 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1161010AbWHAOqE (ORCPT ); Tue, 1 Aug 2006 10:46:04 -0400 Date: Tue, 1 Aug 2006 07:45:56 -0700 From: Andrew Morton To: Herbert Xu Cc: linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net Subject: Re: [BLOCK] bh: Ensure bh fits within a page Message-Id: <20060801074556.b9e772bc.akpm@osdl.org> In-Reply-To: <20060801110658.GA5388@gondor.apana.org.au> References: <20060801030443.GA2221@gondor.apana.org.au> <20060731210418.084f9f5d.akpm@osdl.org> <20060801050259.GA3126@gondor.apana.org.au> <20060731225454.19981a5f.akpm@osdl.org> <20060801110658.GA5388@gondor.apana.org.au> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.17; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 1 Aug 2006 21:06:58 +1000 Herbert Xu wrote: > On Mon, Jul 31, 2006 at 10:54:54PM -0700, Andrew Morton wrote: > > > > Crap, that's hard to fix. Am I allowed to blame submit_bh()? ;) > > Sure you're allowed to do anything :) > > > uhm, we don't want to lose kmalloc redzoning, so I guess we need to create > > on-demand ext3-private slab caches for 1024, 2048, and 4096 bytes. With > > the appropriate slab flags to defeat the redzoning. > > Either that or we should fix redzoning so that it actually preserves > alignment, rather than turning off debugging whenever we want alignment. > Basically it means that we need to use twice the amount of memory for > each object (so 2K for each 1K object). Is this acceptable for debugging? It doesn't sound like a good idea. At present CONFIG_DEBUG_SLAB is acceptable for production use (although it makes kernel profiles look pretty sad). Doubling the size of the slabs would rather alter that.