Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261303AbVEKWxC (ORCPT ); Wed, 11 May 2005 18:53:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261635AbVEKWxC (ORCPT ); Wed, 11 May 2005 18:53:02 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:5647 "EHLO g5.random") by vger.kernel.org with ESMTP id S261303AbVEKWwu (ORCPT ); Wed, 11 May 2005 18:52:50 -0400 Date: Thu, 12 May 2005 00:52:43 +0200 From: Andrea Arcangeli To: Hugh Dickins Cc: William Jordan , Timur Tabi , Andrew Morton , linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation Message-ID: <20050511225243.GM6313@g5.random> References: <20050412180447.E6958@topspin.com> <20050425203110.A9729@topspin.com> <4279142A.8050501@ammasso.com> <427A6A7E.8000604@ammasso.com> <427BF8E1.2080006@ammasso.com> <427CD49E.6080300@ammasso.com> <78d18e2050511131246075b37@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1102 Lines: 20 On Wed, May 11, 2005 at 09:42:24PM +0100, Hugh Dickins wrote: > proposed patches) there is no such migration of pages; that we'd prefer > to implement migration in such a way that mlock does not inhibit it > (though there might prove to be strong arguments defeating that); > and that get_user_pages _must_ prevent migration (and if there > were already such migration, I'd be saying it _does_ prevent it). Indeed, mlock is a virtual pin and as such it won't be guaranteed to always prevent migration. While get_user_pages is a physical pin on the physical page so it has to prevent migration. I think for him the physical pin is better since I guess IB would break (at least unless you've some method to call to stop IB, adjust the IB dma tracking, and restart IB, that hotplug can call). For the short term using only get_user_pages sounds simpler IMHO. - 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/