Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-we0-f178.google.com ([74.125.82.178]:61734 "EHLO mail-we0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756442AbaDWKYj (ORCPT ); Wed, 23 Apr 2014 06:24:39 -0400 Received: by mail-we0-f178.google.com with SMTP id u56so632796wes.23 for ; Wed, 23 Apr 2014 03:24:38 -0700 (PDT) Message-ID: <535794E3.1020201@dev.mellanox.co.il> Date: Wed, 23 Apr 2014 13:24:35 +0300 From: Sagi Grimberg MIME-Version: 1.0 To: Christoph Hellwig , Chuck Lever CC: linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH V2 10/17] xprtrdma: Add CONFIG setting that can disable ALLPHYSICAL References: <20140421214442.12569.8950.stgit@manet.1015granger.net> <20140421220214.12569.23157.stgit@manet.1015granger.net> <20140422062338.GA23311@infradead.org> In-Reply-To: <20140422062338.GA23311@infradead.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 4/22/2014 9:23 AM, Christoph Hellwig wrote: > On Mon, Apr 21, 2014 at 06:02:14PM -0400, Chuck Lever wrote: >> ALLPHYSICAL is not a safe memory registration mode because it >> permits NFS servers to write anywhere in a client's memory. NFS >> server bugs could result in client memory being overwritten. >> >> This can be useful for embedded systems which do not support more >> surgical RDMA memory registration and protection methods, or for >> bring-up of new HCA hardware. >> >> However, enterprise Linux distributions have expressed a desire to >> disable it in production environments. > It's just as unsafe in embedded devices. I think it should go For small IOs pattern, ALLPHYSICAL should outperform any registration method in terms of IOP rate (simply because it doesn't do it). Generally speaking, deployments that may prefer higher IOP rate in the cost of a security do exist out there... Sagi.