Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757460Ab2HNUad (ORCPT ); Tue, 14 Aug 2012 16:30:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1568 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757398Ab2HNUac (ORCPT ); Tue, 14 Aug 2012 16:30:32 -0400 Date: Tue, 14 Aug 2012 23:31:23 +0300 From: "Michael S. Tsirkin" To: Rafael Aquini Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell , Rik van Riel , Mel Gorman , Andi Kleen , Andrew Morton , Konrad Rzeszutek Wilk , Minchan Kim Subject: Re: [PATCH v7 2/4] virtio_balloon: introduce migration primitives to balloon pages Message-ID: <20120814203123.GC28990@redhat.com> References: <20120813084123.GF14081@redhat.com> <20120814182244.GB13338@t510.redhat.com> <20120814195139.GA28870@redhat.com> <20120814201113.GE22133@t510.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120814201113.GE22133@t510.redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 839 Lines: 22 On Tue, Aug 14, 2012 at 05:11:13PM -0300, Rafael Aquini wrote: > On Tue, Aug 14, 2012 at 10:51:39PM +0300, Michael S. Tsirkin wrote: > > What I think you should do is use rcu for access. > > And here sync rcu before freeing. > > Maybe an overkill but at least a documented synchronization > > primitive, and it is very light weight. > > > > I liked your suggestion on barriers, as well. > > Rik, Mel ? Further instead of simple assignment I would add an api in mm to set/clear the balloon mapping, with proper locking. This could fail if already set, and thus fix crash with many ballons. -- 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/