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_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 823ADC433DF for ; Mon, 29 Jun 2020 21:23:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B511208DB for ; Mon, 29 Jun 2020 21:23:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388483AbgF2VXd (ORCPT ); Mon, 29 Jun 2020 17:23:33 -0400 Received: from mga03.intel.com ([134.134.136.65]:63958 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729383AbgF2SvV (ORCPT ); Mon, 29 Jun 2020 14:51:21 -0400 IronPort-SDR: uBUsazwOnmNYLPGQng0mmYqeiDr+H3IEsq7fDUMEBm+6npRfF3QqmMXMIDWcu0EOKFVNFuDZqy VeGmPmjIIZbQ== X-IronPort-AV: E=McAfee;i="6000,8403,9666"; a="145971622" X-IronPort-AV: E=Sophos;i="5.75,294,1589266800"; d="scan'208";a="145971622" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2020 07:36:17 -0700 IronPort-SDR: 7MwTDCGr5NjvvVT2xsNX3KfYnWnWvuUzoUCN0hhPSWxf0G/GgQJFCv3SqhoBI+4o7oVrkruyVH Ot/elOcYiaIw== X-IronPort-AV: E=Sophos;i="5.75,294,1589266800"; d="scan'208";a="454214032" Received: from tclumbax-mobl2.gar.corp.intel.com (HELO [10.255.1.194]) ([10.255.1.194]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2020 07:36:16 -0700 From: Dave Hansen Subject: Re: [PATCH] mm/vmscan: restore zone_reclaim_mode ABI To: Daniel Wagner Cc: Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, ben.widawsky@intel.com, alex.shi@linux.alibaba.com, tobin@kernel.org, cl@linux.com, akpm@linux-foundation.org, stable@kernel.org References: <20200626003459.D8E015CA@viggo.jf.intel.com> <20200626075918.dj6ioaon5iuhtg6k@beryllium.lan> <83731eeb-1f64-50b7-41e9-5b7114678533@intel.com> <20200629071338.m4veigbp4tu45gbz@beryllium.lan> Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200629071338.m4veigbp4tu45gbz@beryllium.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/29/20 12:13 AM, Daniel Wagner wrote: > On Fri, Jun 26, 2020 at 06:53:33AM -0700, Dave Hansen wrote: >> Was there something else specifically in the documentation which you >> think I've neglected? > > The first paragraph explains how you ended up modifying the code. While > I understand that you want to document the process, it wont help > a reader in future. It doesn't add any intersting information at all. > Just state what you're doing as first thing and explain why you are > doing it after it. I went back and looked at it to see what interesting information I think the first paragraph conveys: > I went to go add a new RECLAIM_* mode for the zone_reclaim_mode > sysctl. This conveys my motivation. It relays that my discovery of the issue was in the process of modifying the code, in contrast to it having being found through observed pathological kernel behavior. > Like a good kernel developer, I also went to go update the > documentation. This takes the opportunity to throw a tiny bit of shade in the direction of the other folks who modified the #define without updating the documentation. It also helps build the justification for the new comment on top of the #defines. I guess you can argue that this should be struck from the changelog. But, heck, it gave me a little chuckle when read it just now. > I noticed that the bits in the documentation didn't > match the bits in the #defines. This is the crux of the problem statement. Can't get rid of this. So, I guess I could pare the above down to simply: When modifying the zone_reclaim_mode sysctl documentation, I found through inspection that the bits in the documentation did not match the bits in the #defines. That's certainly chuckle-free, and it would make my editor happy because it's shorter and now he can sell another ad on the page. Would you prefer that form? >>> I think the documentation update should not be part of this patch. >>> This makes the back porting to stable more difficult. >> >> Really? If a backporter doesn't care about documentation, I'd just >> expect them to see the reject, ignore it, and move on with their life. >> If they do, they'd want the code fix and the Documentation/ update in >> the same patch so that they don't get disconnected. > > I understood you are fixing a regression ingroduced by a previous change. In > this case I would only fix the regression. Updating/improving the > documentation is good, I just don't think it's necessary to back port it to > stables trees along side the bug fix. That's a question for the person doing the backport. Attaching the two things makes it the most likely that they will be given the best, most complete information. I've done my share of backports and I if it were me, I think I'd rather have it this way.