From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753528Ab0EKW4Y (ORCPT ); Tue, 11 May 2010 18:56:24 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54767 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752391Ab0EKW4W (ORCPT ); Tue, 11 May 2010 18:56:22 -0400 Date: Tue, 11 May 2010 15:56:00 -0700 From: Andrew Morton To: Dave Airlie Cc: Chris Wilson , Jaswinder Singh Rajput , dri-devel@lists.freedesktop.org, Dave Airlie , Linux Kernel Mailing List , Keith Packard , Eric Anholt , Ingo Molnar Subject: Re: DRM Error on Acer Aspire One Message-Id: <20100511155600.5c416992.akpm@linux-foundation.org> In-Reply-To: References: <89kc63$grtht6@fmsmga002.fm.intel.com> <20100511104818.8382a7de.akpm@linux-foundation.org> <89khjo$fd26d3@orsmga002.jf.intel.com> <20100511113555.a78c9c8e.akpm@linux-foundation.org> <89kc63$grv1m8@fmsmga002.fm.intel.com> <20100511121001.0731a9c2.akpm@linux-foundation.org> <89k77n$noi3t4@fmsmga001.fm.intel.com> <20100511153217.5c7661d7.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 May 2010 08:51:05 +1000 Dave Airlie wrote: > On Wed, May 12, 2010 at 8:32 AM, Andrew Morton > wrote: > > On Wed, 12 May 2010 08:22:49 +1000 > > Dave Airlie wrote: > > > >> On Wed, May 12, 2010 at 5:57 AM, Chris Wilson wrote: > >> > On Tue, 11 May 2010 12:10:01 -0700, Andrew Morton wrote: > >> >> On Tue, 11 May 2010 19:52:31 +0100 > >> >> Chris Wilson wrote: > >> >> > >> >> > On Tue, 11 May 2010 11:35:55 -0400, Andrew Morton wrote: > >> >> > > No, io_mapping_map_atomic_wc() cannot be used from [soft]irq context: > >> >> > > it hardwires use of KM_USER0. __I suggest that io_mapping_create_wc(), > >> >> > > io_mapping_map_atomic_wc() etc be changed so that the caller passes in the > >> >> > > KM_foo kmap slot index. > >> >> > > >> >> > Argh, sorry for the noise, read the mail in the wrong order. Thanks for > >> >> > the review. It would be sensible to go with your simpler patch whilst > >> >> > io_mapping_map_atomic_wc() is improved. > >> >> > >> >> OK. __I'll be sending a bunch of fixes Linuswards in an hour or two. > >> >> Should I include this? > >> > > >> > Yes. > >> > > >> > Acked-by: Chris Wilson > >> > > >> > >> I'm not sure pushing this in at this point is a good idea, if I'm > >> reading it correctly we've no idea what KM_IRQ is being used for, > > > > It's used for taking kmaps from IRQ contexts. > > > >> and > >> this codepath is called from non-irq contexts just as much as irq > >> contexts. > > > > That's fine. __As long as we do a local_irq_disable(), KM_IRQ0 can be > > used from both irq- and non-irq contexts. __All we need to do is to > > ensure that some interrupt cannot come along on this CPU and corrupt > > the slot. > > I don't think we do that in a lot of places, and I'd rather not add > that in to fix this problem at this point in the release cycle, as > we've no idea what it might break/regress. What is "that"? The switch to irq-protected KM_IRQ0? That won't break anything. > Its easier to just disable the hangcheck copy and try again for 2.6.35 > with a workqueue or slow work.