From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751291AbWHAFzB (ORCPT ); Tue, 1 Aug 2006 01:55:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751574AbWHAFzB (ORCPT ); Tue, 1 Aug 2006 01:55:01 -0400 Received: from smtp.osdl.org ([65.172.181.4]:8598 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751291AbWHAFzA (ORCPT ); Tue, 1 Aug 2006 01:55:00 -0400 Date: Mon, 31 Jul 2006 22:54:54 -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: <20060731225454.19981a5f.akpm@osdl.org> In-Reply-To: <20060801050259.GA3126@gondor.apana.org.au> References: <20060801030443.GA2221@gondor.apana.org.au> <20060731210418.084f9f5d.akpm@osdl.org> <20060801050259.GA3126@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 15:02:59 +1000 Herbert Xu wrote: > On Mon, Jul 31, 2006 at 09:04:18PM -0700, Andrew Morton wrote: > > > > Could we have a more detailed description? > > Sure, this particular instance is in journal_write_metadata_buffer > where the bh may be constructed from kmalloc memory (search for the > call to jbd_rep_kmalloc). Because the memory returned by kmalloc > may straddle a page (when slab debugging is enabled that is), this > causes a broken bh to be injected into submit_bh. > Crap, that's hard to fix. Am I allowed to blame submit_bh()? ;) 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.