From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757463AbZBJW6T (ORCPT ); Tue, 10 Feb 2009 17:58:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755548AbZBJW6I (ORCPT ); Tue, 10 Feb 2009 17:58:08 -0500 Received: from outbound-mail-156.bluehost.com ([67.222.39.36]:47163 "HELO outbound-mail-156.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754527AbZBJW6H convert rfc822-to-8bit (ORCPT ); Tue, 10 Feb 2009 17:58:07 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=default; d=virtuousgeek.org; h=Received:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-Disposition:Message-Id:X-Identified-User; b=bCtt12pdCNWSR6cRtY4RthhxnXQHLesBKDWR9aW/wowWeUl4eWOZ0WbiP6KPciRqyHSoOX2viH1lEdPBb3jbrbSlg0pDxxgpMhmtOHxhNql+4Yp4gVbiVZOBDJJ1Kt9o; From: Jesse Barnes To: Eric Anholt Subject: Re: Gem GTT mmaps.. Date: Tue, 10 Feb 2009 14:58:00 -0800 User-Agent: KMail/1.9.10 Cc: Thomas =?iso-8859-15?q?Hellstr=F6m?= , DRI , Linux Kernel References: <498A1760.7010108@shipmail.org> <200902061424.02906.jbarnes@virtuousgeek.org> <1234303201.32506.8.camel@gaiman> In-Reply-To: <1234303201.32506.8.camel@gaiman> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200902101458.01157.jbarnes@virtuousgeek.org> X-Identified-User: {642:box128.bluehost.com:virtuous:virtuousgeek.org} {sentby:smtp auth 75.111.27.49 authed with jbarnes@virtuousgeek.org} Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, February 10, 2009 2:00 pm Eric Anholt wrote: > On Fri, 2009-02-06 at 14:24 -0800, Jesse Barnes wrote: > > On Friday, February 6, 2009 1:35 pm Thomas Hellström wrote: > > > Jesse Barnes wrote: > > > > On Thursday, February 5, 2009 10:37 am Jesse Barnes wrote: > > > >> So if we leave the lookup reference around from the GTT mapping > > > >> ioctl, that would take care of new mappings. And if we > > > >> added/removed references at VM open/close time, we should be covered > > > >> for fork. But is it ok to add a new unref in the finish ioctl for > > > >> GTT mapped objects? I don't think so, because we don't know for > > > >> sure if the caller was the one that created the new fake offset > > > >> (which would be one way of detecting whether it was GTT mapped). > > > >> Seems like we need a new unmap ioctl? Or we could put the mapping > > > >> ref/unref in libdrm, where it would be tracked on a per-process > > > >> basis... > > > > > > > > Ah but maybe we should just tear down the fake offset at unmap time; > > > > then we'd be able to use it as an existence test for the mapping and > > > > get the refcounting right. The last thing I thought of was whether > > > > we'd be ok in a map_gtt -> crash case. I *think* the vm_close code > > > > will deal with that, if we do a deref there? > > > > > > Yes, an mmap() is always paired with a vm_close(), and the vm_close() > > > also happens in a crash situation. > > > > This one should cover the cases you found. > > - ref at map time will keep the object around so fault shouldn't fail > > - additional threads will take their refs in vm_open/close > > - unmap will unref and remove mmap_offset allowing object to be freed > > sw_finish doesn't mean unmap (note that it doesn't actually unmap). > > If you want to actually unmap, that should be done with munmap. Yeah, but it does get called at dri_bo_unmap time... I haven't traced the munmap code to see if it would do what we want... if it ends up in vm_close too then it would be fine (ref at gtt ioctl time, unref at vm_close time, as long as there's not a stray vm_open in there). Jesse -- Jesse Barnes, Intel Open Source Technology Center