Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937854AbWLGAqJ (ORCPT ); Wed, 6 Dec 2006 19:46:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S937859AbWLGAqI (ORCPT ); Wed, 6 Dec 2006 19:46:08 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:58352 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S937854AbWLGAqF (ORCPT ); Wed, 6 Dec 2006 19:46:05 -0500 Date: Wed, 06 Dec 2006 16:46:16 -0800 (PST) Message-Id: <20061206.164616.74731030.davem@davemloft.net> To: mattjreimer@gmail.com Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: D-cache aliasing issue in cow_user_page From: David Miller In-Reply-To: References: <20061205.165948.98864221.davem@davemloft.net> X-Mailer: Mew version 4.2 on Emacs 21.4 / Mule 5.0 (SAKAKI) 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 Content-Length: 1242 Lines: 33 From: "Matt Reimer" Date: Wed, 6 Dec 2006 13:19:41 -0800 > On 12/5/06, David Miller wrote: > > From: "Matt Reimer" > > Date: Tue, 5 Dec 2006 16:57:12 -0800 > > > > > Right, but isn't he declaring that each architecture needs to take > > > care of this? So, say, on ARM we'd need to make kunmap() not a NOP and > > > call flush_dcache_page() ? > > > > No. He is only solving a problem that occurs on HIGHMEM > > configurations on systems which can have D-cache aliasing > > issues. > > Are you sure? James specifically mentions "non-highmem architectures," > and "all architectures with coherence issues," which would seem to > include ARM (which is my concern). > > For your convenience I quote the whole commit message below. Ok, I see. He's providing it an alternative way to solve the coherency issues. You can still solve it the traditional way via cache flushing in flush_dcache_page() and {copy,clear}_user_page(). - 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/