From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422784AbXCBFJw (ORCPT ); Fri, 2 Mar 2007 00:09:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422801AbXCBFJw (ORCPT ); Fri, 2 Mar 2007 00:09:52 -0500 Received: from smtp.osdl.org ([65.172.181.24]:42529 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422784AbXCBFJv (ORCPT ); Fri, 2 Mar 2007 00:09:51 -0500 Date: Thu, 1 Mar 2007 21:09:42 -0800 From: Andrew Morton To: Christoph Hellwig Cc: support@coraid.com, "Ed L. Cashin" , linux-kernel@vger.kernel.org, Greg KH Subject: Re: PATCH 2.6.21-rc1 aoe: handle zero _count pages in bios Message-Id: <20070301210942.ebf40993.akpm@linux-foundation.org> In-Reply-To: <20070302050351.GA24705@infradead.org> References: <20070301231510.GC8524@coraid.com> <20070301174204.a550dd3a.akpm@linux-foundation.org> <20070302022919.GA26285@infradead.org> <20070301192245.bf034385.akpm@linux-foundation.org> <20070302043039.GA18651@infradead.org> <20070301204806.61225e2b.akpm@linux-foundation.org> <20070302044910.GA22209@infradead.org> <20070301210044.d95bcd70.akpm@linux-foundation.org> <20070302050351.GA24705@infradead.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-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 Fri, 2 Mar 2007 05:03:51 +0000 Christoph Hellwig wrote: > On Thu, Mar 01, 2007 at 09:00:44PM -0800, Andrew Morton wrote: > > I that case we're talking about different things. > > > > I thought the proposal was to continue to use slab pages, but to take a ref > > on them as they're added to the bio, drop that ref in bi_end_io()? > > That would give you silent memory corruption in case the networking code > hold a reference after the memory gets returned to slab and reused. Well, given that bi_end_io() is called after the "io" has completed, I'm assuming that networking has completely finished with the memory by the time bi_end_io() gets called. I guess one can envisage situations where that might not happen, but they'd be terribly buggy ones, surely. > We need to either stop allowing to pass slab memory to the block layer, > or document that drivers need to handle it specially and give them a > way to find out about them. (Or do the horrible slab refcounting hack > I wrote up above) OK. So you're proposing that XFS and ext3 simply stop sing slab for this memory?