Return-Path: Received: from fieldses.org ([173.255.197.46]:33351 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755118AbbHLNxq (ORCPT ); Wed, 12 Aug 2015 09:53:46 -0400 Date: Wed, 12 Aug 2015 09:53:45 -0400 From: "J. Bruce Fields" To: Chuck Lever Cc: Linux NFS Mailing List Subject: Re: [PATCH] svcrdma: Change maximum server payload back to RPCSVC_MAXPAYLOAD Message-ID: <20150812135345.GA26656@fieldses.org> References: <20150807205325.1887.53743.stgit@klimt.1015granger.net> <20150810210557.GC10455@fieldses.org> <4E4E8EA4-AF06-4BB6-ABAB-5D9B5BF6FEB6@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4E4E8EA4-AF06-4BB6-ABAB-5D9B5BF6FEB6@oracle.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Aug 10, 2015 at 05:27:18PM -0400, Chuck Lever wrote: > > On Aug 10, 2015, at 5:05 PM, J. Bruce Fields wrote: > > > On Fri, Aug 07, 2015 at 04:55:46PM -0400, Chuck Lever wrote: > >> Both commit 0380a3f375 ("svcrdma: Add a separate "max data segs" > >> macro for svcrdma") and commit 7e5be28827bf ("svcrdma: advertise > >> the correct max payload") are incorrect. This commit reverts both > >> changes, restoring the server's maximum payload size to 1MB. > >> > >> Commit 7e5be28827bf based the server's maximum payload on the > >> _client's_ RPCRDMA_MAX_DATA_SEGS value. That was wrong. > >> > >> Commit 0380a3f375 tried to fix this so that the client maximum > >> payload size could be raised without affecting the server, but > >> managed to confuse matters more on the server side. > >> > >> More importantly, limiting the advertised maximum payload size was > >> meant to be a workaround, not the actual fix. We need to revisit > >> > >> https://bugzilla.linux-nfs.org/show_bug.cgi?id=270 > >> > >> A Linux client on a platform with 64KB pages can overrun and crash > >> an x86_64 NFS/RDMA server when the r/wsize is 1MB. An x86/64 Linux > >> client seems to work fine using 1MB reads and writes when the Linux > >> server's maximum payload size is restored to 1MB. > >> > >> BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=270 > >> Fixes: 0380a3f375 ("svcrdma: Add a separate "max data segs" macro") > >> Signed-off-by: Chuck Lever > >> --- > >> > >> Hi Bruce- > >> > >> I notice you still have "svcrdma: Boost NFS READ/WRITE payload > >> size maximum" in both your nfsd-next and for-4.3 branches. Can > >> you please replace that patch with this one? This patch uses > >> the approach we agreed on several weeks ago. > >> > >> Thanks! > > > > Gah, I don't like rebasing those for-XXX branches, but OK, done. In the > > future I'd prefer incremental patches against those branches if at all > > possible. > > Thanks for taking the update! > > I thought you were going to wait for v2 of that series. > > http://marc.info/?l=linux-nfs&m=143680563000597&w=2 Yeah, that was probably my screwup. --b.