Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751825AbXBFJAO (ORCPT ); Tue, 6 Feb 2007 04:00:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751723AbXBFJAO (ORCPT ); Tue, 6 Feb 2007 04:00:14 -0500 Received: from hp3.statik.TU-Cottbus.De ([141.43.120.68]:35900 "EHLO hp3.statik.tu-cottbus.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825AbXBFJAL (ORCPT ); Tue, 6 Feb 2007 04:00:11 -0500 Message-ID: <45C84399.70407@s5r6.in-berlin.de> Date: Tue, 06 Feb 2007 10:00:09 +0100 From: Stefan Richter User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.0.8) Gecko/20061030 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Andi Kleen CC: Andrew Morton , David Moore , linux-kernel , discuss@x86-64.org, linux1394-devel , Jan Beulich Subject: Re: [PATCH] Missing critical phys_to_virt in lib/swiotlb.c References: <1170614380.26464.52.camel@PISCES.MIT.EDU> <20070205133556.9b290d0a.akpm@linux-foundation.org> <200702060856.45473.ak@suse.de> In-Reply-To: <200702060856.45473.ak@suse.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2321 Lines: 55 On 2/6/2007 8:56 AM, Andi Kleen wrote: >> > From: David Moore ... >> > It fixes real crashes: >> > http://lists.opensuse.org/opensuse-bugs/2006-12/msg02943.html >> > http://qa.mandriva.com/show_bug.cgi?id=28224 >> > http://www.pchdtv.com/forum/viewtopic.php?t=2063&sid=a959a14a4c2db0eebaab7b0df56103ce >> > >> > --- linux-2.6.19.x86_64/lib/swiotlb.c.orig 2007-02-04 13:18:41.000000000 -0500 >> > +++ linux-2.6.19.x86_64/lib/swiotlb.c 2007-02-04 13:19:43.000000000 -0500 >> > @@ -750,7 +750,7 @@ swiotlb_sync_sg(struct device *hwdev, st >> > >> > for (i = 0; i < nelems; i++, sg++) >> > if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg)) >> > - sync_single(hwdev, (void *) sg->dma_address, >> > + sync_single(hwdev, phys_to_virt(sg->dma_address), >> > sg->dma_length, dir, target); >> > } ... > Sounds weird. If this really didn't work much more should be broken > (e.g. no cdroms/sound on Intel x86-64 boxes with >4GB) Yes, it's weird; e.g. it seems that reports of that on linux1394-user and -devel came in only recently. But I may have missed something. (OTOH, this bug was partially hidden for FireWire users because one of the relevant FireWire drivers was lacking respective _sync_sg calls.) > I'm a little sceptical. Perhaps the TV driver is doing something bogus > here? sync_single() definitely wants a virtual address there. sg->dma_address is a physical address. The bug and the fix are obvious. Unfortunately an author of lib/swiotlb.c chose to call many variables holding *virtual* addresses "dma_addr". Note how that file at the same time contains variables like "dma_addr_t dma_handle". A recipe for disaster. > Also I haven't heard of this problem before at all and I'm sure I would > have if sounds/cdroms were broken. > > Shouldn't be applied without further analysis. Maybe some recent changes elsewhere cause more frequent use of swiotlb-driven bounce buffers? That should be verified. Or maybe people are deploying affected hardware more often now? -- Stefan Richter -=====-=-=== --=- --==- http://arcgraph.de/sr/ - 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/