From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B80BC282C4 for ; Thu, 7 Feb 2019 16:58:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E258721872 for ; Thu, 7 Feb 2019 16:58:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726860AbfBGQ57 (ORCPT ); Thu, 7 Feb 2019 11:57:59 -0500 Received: from mga06.intel.com ([134.134.136.31]:58682 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbfBGQ56 (ORCPT ); Thu, 7 Feb 2019 11:57:58 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Feb 2019 08:57:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,344,1544515200"; d="scan'208";a="318468274" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by fmsmga005.fm.intel.com with ESMTP; 07 Feb 2019 08:57:57 -0800 Date: Thu, 7 Feb 2019 08:57:41 -0800 From: Ira Weiny To: Tom Talpey Cc: Chuck Lever , Jason Gunthorpe , Dave Chinner , Doug Ledford , Christopher Lameter , Matthew Wilcox , Jan Kara , lsf-pc@lists.linux-foundation.org, linux-rdma , linux-mm@kvack.org, Linux Kernel Mailing List , John Hubbard , Jerome Glisse , Dan Williams , Michal Hocko Subject: Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA Message-ID: <20190207165740.GB29531@iweiny-DESK2.sc.intel.com> References: <20190206175233.GN21860@bombadil.infradead.org> <47820c4d696aee41225854071ec73373a273fd4a.camel@redhat.com> <01000168c43d594c-7979fcf8-b9c1-4bda-b29a-500efe001d66-000000@email.amazonses.com> <20190206210356.GZ6173@dastard> <20190206220828.GJ12227@ziepe.ca> <0c868bc615a60c44d618fb0183fcbe0c418c7c83.camel@redhat.com> <20190207035258.GD6173@dastard> <20190207052310.GA22726@ziepe.ca> <6b260348-966a-bc95-162b-44ae8265cf03@talpey.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b260348-966a-bc95-162b-44ae8265cf03@talpey.com> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 07, 2019 at 10:28:05AM -0500, Tom Talpey wrote: > On 2/7/2019 10:04 AM, Chuck Lever wrote: > > > > > > > On Feb 7, 2019, at 12:23 AM, Jason Gunthorpe wrote: > > > > > > On Thu, Feb 07, 2019 at 02:52:58PM +1100, Dave Chinner wrote: > > > > > > > Requiring ODP capable hardware and applications that control RDMA > > > > access to use file leases and be able to cancel/recall client side > > > > delegations (like NFS is already able to do!) seems like a pretty > > > > > > So, what happens on NFS if the revoke takes too long? > > > > NFS distinguishes between "recall" and "revoke". Dave used "recall" > > here, it means that the server recalls the client's delegation. If > > the client doesn't respond, the server revokes the delegation > > unilaterally and other users are allowed to proceed. > > The SMB3 protocol has a similar "lease break" mechanism, btw. > > SMB3 "push mode" has long-expected to allow DAX mapping of files > only when an exclusive lease is held by the requesting client. > The server may recall the lease if the DAX mapping needs to change. > > Once local (MMU) and remote (RDMA) mappings are dropped, the > client may re-request that the server reestablish them. No > connection or process is terminated, and no data is silently lost. How long does one wait for these remote mappings to be dropped? Ira