From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 27 Jun 2001 05:42:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 27 Jun 2001 05:42:22 -0400 Received: from penguin.e-mind.com ([195.223.140.120]:23584 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Wed, 27 Jun 2001 05:42:13 -0400 Date: Wed, 27 Jun 2001 11:41:55 +0200 From: Andrea Arcangeli To: Jens Axboe Cc: Linux Kernel , linux-mm@kvack.org, "ZINKEVICIUS,MATT (HP-Loveland,ex1)" Subject: Re: patch: highmem zero-bounce Message-ID: <20010627114155.A31910@athlon.random> In-Reply-To: <20010626182215.C14460@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010626182215.C14460@suse.de>; from axboe@suse.de on Tue, Jun 26, 2001 at 06:22:15PM +0200 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 26, 2001 at 06:22:15PM +0200, Jens Axboe wrote: > Hi, > > I updated the patches to 2.4.6-pre5, and removed the zone-dma32 > addition. This means that machines with > 4GB of RAM will need to go all good, we can relax the ZONE_NORMAL later, that's a separate problem with skipping the bounces. I can see one mm corruption race condition in the patch, you missed nested irq in the for kmap_irq_bh (PIO). You must _always_ __cli/__save_flags before accessing the KMAP_IRQ_BH slot, in case the remapping is required (so _only_ when the page is in the highmem zone). Otherwise memory corruption will happen when the race triggers (for example two ide disks in PIO mode doing I/O at the same time connected to different irq sources). Andrea