Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031549AbWLEVYK (ORCPT ); Tue, 5 Dec 2006 16:24:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031567AbWLEVYK (ORCPT ); Tue, 5 Dec 2006 16:24:10 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:56211 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1031549AbWLEVYI (ORCPT ); Tue, 5 Dec 2006 16:24:08 -0500 Date: Tue, 05 Dec 2006 13:24:12 -0800 (PST) Message-Id: <20061205.132412.116353924.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: 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: 838 Lines: 19 From: "Matt Reimer" Date: Mon, 4 Dec 2006 23:38:13 -0800 > In light of James Bottomsley's commit[1] declaring that kmap() and > friends now have to take care of coherency issues, is the patch "mm: > D-cache aliasing issue in cow_user_page"[2] correct, or could it > potentially cause a slowdown by calling flush_dcache_page() a second > time (i.e. once in an architecture-specific kmap() implementation, and > once in cow_user_page())? kmap() is a NOP unless HIGHMEM is configured. Therefore, it cannot possibly take care of D-cache aliasing issues across the board. - 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/