Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756318AbYA3Nh5 (ORCPT ); Wed, 30 Jan 2008 08:37:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753724AbYA3Nhj (ORCPT ); Wed, 30 Jan 2008 08:37:39 -0500 Received: from host36-195-149-62.serverdedicati.aruba.it ([62.149.195.36]:50442 "EHLO mx.cpushare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841AbYA3Nhd (ORCPT ); Wed, 30 Jan 2008 08:37:33 -0500 Date: Wed, 30 Jan 2008 14:37:20 +0100 From: Andrea Arcangeli To: Jack Steiner Cc: Christoph Lameter , Robin Holt , Avi Kivity , Izik Eidus , Nick Piggin , kvm-devel@lists.sourceforge.net, Benjamin Herrenschmidt , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Hugh Dickins Subject: Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges Message-ID: <20080130133720.GM7233@v2.random> References: <20080128202923.849058104@sgi.com> <20080129162004.GL7233@v2.random> <20080129211759.GV7233@v2.random> <20080129220212.GX7233@v2.random> <20080130000039.GA7233@v2.random> <20080130002804.GA13840@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080130002804.GA13840@sgi.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1465 Lines: 30 On Tue, Jan 29, 2008 at 06:28:05PM -0600, Jack Steiner wrote: > On Tue, Jan 29, 2008 at 04:20:50PM -0800, Christoph Lameter wrote: > > On Wed, 30 Jan 2008, Andrea Arcangeli wrote: > > > > > > invalidate_range after populate allows access to memory for which ptes > > > > were zapped and the refcount was released. > > > > > > The last refcount is released by the invalidate_range itself. > > > > That is true for your implementation and to address Robin's issues. Jack: > > Is that true for the GRU? > > I'm not sure I understand the question. The GRU never (currently) takes > a reference on a page. It has no mechanism for tracking pages that > were exported to the external TLBs. If you don't have a pin, then things like invalidate_range in remap_file_pages can't be safe as writes through the external TLBs can keep going on pages in the freelist. For you to be safe w/o a page-pin, you need to return in the direction of invalidate_page inside ptep_clear_flush (or anyway before page_cache_release/__free_page/put_page...). You're generally not safe with any invalidate_range that may run after the page pointed by the pte has been freed (or can be freed by the VM anytime because of being unpinned cache). -- 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/