Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762396AbYBTOmO (ORCPT ); Wed, 20 Feb 2008 09:42:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751558AbYBTOl7 (ORCPT ); Wed, 20 Feb 2008 09:41:59 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:52824 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751244AbYBTOl7 (ORCPT ); Wed, 20 Feb 2008 09:41:59 -0500 Date: Wed, 20 Feb 2008 08:41:55 -0600 From: Robin Holt To: Andrea Arcangeli Cc: Nick Piggin , akpm@linux-foundation.org, Robin Holt , Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Christoph Lameter Subject: Re: [PATCH] mmu notifiers #v6 Message-ID: <20080220144155.GI11391@sgi.com> References: <20080219084357.GA22249@wotan.suse.de> <20080219135851.GI7128@v2.random> <20080219231157.GC18912@wotan.suse.de> <20080220010941.GR7128@v2.random> <20080220103942.GU7128@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080220103942.GU7128@v2.random> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 814 Lines: 17 On Wed, Feb 20, 2008 at 11:39:42AM +0100, Andrea Arcangeli wrote: > XPMEM simply can't use RCU for the registration locking if it wants to > schedule inside the mmu notifier calls. So I guess it's better to add Whoa there. In Christoph's patch, we did not use rcu for the list. It was a simple hlist_head. The list manipulations were done under down_write(¤t->mm->mmap_sem) and would therefore not be racy. All the callout locations are already acquiring the mmap_sem at least readably, so we should be safe. Maybe I missed a race somewhere. Thanks, Robin -- 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/