From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263902AbTEZDGj (ORCPT ); Sun, 25 May 2003 23:06:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263911AbTEZDGj (ORCPT ); Sun, 25 May 2003 23:06:39 -0400 Received: from rth.ninka.net ([216.101.162.244]:43395 "EHLO rth.ninka.net") by vger.kernel.org with ESMTP id S263902AbTEZDGi (ORCPT ); Sun, 25 May 2003 23:06:38 -0400 Subject: Re: [patch] cache flush bug in mm/filemap.c (all kernels >= 2.5.30(at least)) From: "David S. Miller" To: Russell King Cc: Andrew Morton , Hugh Dickins , LW@KARO-electronics.de, linux-kernel@vger.kernel.org In-Reply-To: <20030523193458.B4584@flint.arm.linux.org.uk> References: <20030523175413.A4584@flint.arm.linux.org.uk> <20030523112926.7c864263.akpm@digeo.com> <20030523193458.B4584@flint.arm.linux.org.uk> Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: Message-Id: <1053919171.14018.2.camel@rth.ninka.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 25 May 2003 20:19:32 -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2003-05-23 at 11:34, Russell King wrote: > So no, I don't think it is a device driver issue at all. > > DaveM? Oh yes, this part is. If you don't ensure this, everything breaks. At the end of an I/O operation, say to a page cache page, that data ought to be visible equally to a userspace vs. a kernel space mapping to that page. For example, this is why we use language about "cpu visibility" in the DMA api documentation and not "kernel cpu visibility" :-) And because PIO transfers are basically pseudo-DMA they need to make the same exact guarentees. If you've been living in a world where you didn't think this is necessary, I certainly feel bad for you :-) -- David S. Miller