Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756978Ab3CUJOE (ORCPT ); Thu, 21 Mar 2013 05:14:04 -0400 Received: from na3sys010aog111.obsmtp.com ([74.125.245.90]:34157 "HELO na3sys010aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756702Ab3CUJOA (ORCPT ); Thu, 21 Mar 2013 05:14:00 -0400 MIME-Version: 1.0 In-Reply-To: <20130321085107.GE28328@redhat.com> References: <20130321061838.GA28319@redhat.com> <20130321070357.GD28328@redhat.com> <20130321085107.GE28328@redhat.com> From: Roland Dreier Date: Thu, 21 Mar 2013 02:13:38 -0700 X-Google-Sender-Auth: 4ZRHNxO1nkdCdcKromBee6KgSmM Message-ID: Subject: Re: [PATCH] rdma: don't make pages writeable if not requiested To: "Michael S. Tsirkin" Cc: "Michael R. Hines" , Sean Hefty , Hal Rosenstock , Yishai Hadas , Christoph Lameter , "linux-rdma@vger.kernel.org" , LKML , qemu-devel@nongnu.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 956 Lines: 23 On Thu, Mar 21, 2013 at 1:51 AM, Michael S. Tsirkin wrote: >> In that case, no, I don't see any reason for LOCAL_WRITE, since the >> only RDMA operations that will access this memory are remote reads. > > What is the meaning of LOCAL_WRITE then? There are no local > RDMA writes as far as I can see. Umm, it means you're giving the local adapter permission to write to that memory. So you can use it as a receive buffer or as the target for remote data from an RDMA read operation. > OK then what we need is a new flag saying "I really do not > intend to write into this memory please do not break > COW or do anything else just in case I do". Isn't that a shared read-only mapping? - R. -- 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/