From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261264AbVFTOki (ORCPT ); Mon, 20 Jun 2005 10:40:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261267AbVFTOkg (ORCPT ); Mon, 20 Jun 2005 10:40:36 -0400 Received: from silver.veritas.com ([143.127.12.111]:53622 "EHLO silver.veritas.com") by vger.kernel.org with ESMTP id S261264AbVFTOk3 (ORCPT ); Mon, 20 Jun 2005 10:40:29 -0400 Date: Mon, 20 Jun 2005 15:41:46 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: "Richard B. Johnson" cc: Linux kernel Subject: Re: Linux-2.6.12 In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 20 Jun 2005 14:40:29.0164 (UTC) FILETIME=[00FEB2C0:01C575A6] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 20 Jun 2005, Richard B. Johnson wrote: > On Mon, 20 Jun 2005, Hugh Dickins wrote: > > > > It's the BUG_ON(!pte_none(*pte)) in remap_pte_range. Maybe your page > > table is corrupt, maybe your driver is trying to remap_pfn_range on > > top of something already mapped. > > But of course it is. There is some memory that is mapped into the > driver's address space, used for DMA. It was obtained using > ioremap_nocache(). This memory is then mapped into user-space > when the user executes mmap(). This is how we DMA directly to > user-space. Is this no longer allowed? Of course that is allowed. But mapping it into userspace on top of an existing populated mapping in userspace is not and has never been allowed (well, in 2.4.0 it just generated a printk, from 2.4.10 onwards it's been a BUG). Hugh