From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758833AbXGZCHS (ORCPT ); Wed, 25 Jul 2007 22:07:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754872AbXGZCHH (ORCPT ); Wed, 25 Jul 2007 22:07:07 -0400 Received: from ns.suse.de ([195.135.220.2]:46208 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751033AbXGZCHG (ORCPT ); Wed, 25 Jul 2007 22:07:06 -0400 Date: Thu, 26 Jul 2007 04:07:04 +0200 From: Nick Piggin To: Dave Airlie Cc: Benjamin Herrenschmidt , Linux Kernel Mailing List , magnade@gmail.com, davej@codemonkey.org.uk Subject: Re: [patch] agp: don't lock pages Message-ID: <20070726020704.GC20727@wotan.suse.de> References: <20070725111922.GF29011@wotan.suse.de> <1185398813.5439.342.camel@localhost.localdomain> <20070726004114.GA17294@wotan.suse.de> <21d7e9970707251844p5c0243d6q7366ab8fa3738f62@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <21d7e9970707251844p5c0243d6q7366ab8fa3738f62@mail.gmail.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 26, 2007 at 11:44:22AM +1000, Dave Airlie wrote: > > > >Yeah I had a bit of a look around, and it seems OK (but would > >appreciate an ack from someone who knows the code). > > > >These pages will never get seen by page reclaim, so we're OK > >there. There is a get_page before the SetPageLocked and a put_page > >right before the unlock_page, so refcounting should not be broken > >if it wasn't already: note that the lock_page doesn't pin a > >reference on a page in general -- we can use it as such for pagecache > >(although it isn't very clean), because the lock pins the page in > >pagecache and the pagecache holds a ref. > > > >Anyway, if Dave or David can take a look, that would be appreciated. > >We'll need this for 2.6.23. > > I talked with Ben earlier and I can't see anything inherently wrong > with removing the lock_page, I assume it was put there to stop things > getting swapped but if the get/put does that then I'd be happy to > remove it. Well it is prevented from being swapped out because it never gets put on swapout lists, but the get/put certainly doesn't hurt :) > I'm just a bit confused how this didn't get picked up in -mm at all. Beats me. It was in there for nearly 5 months. Mustn't have been tested or reported.