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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0FC5C25B0E for ; Fri, 19 Aug 2022 02:12:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242263AbiHSCMn (ORCPT ); Thu, 18 Aug 2022 22:12:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236204AbiHSCMj (ORCPT ); Thu, 18 Aug 2022 22:12:39 -0400 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22D24DD777 for ; Thu, 18 Aug 2022 19:12:37 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R211e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0VMdxGnC_1660875154; Received: from 30.240.99.21(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0VMdxGnC_1660875154) by smtp.aliyun-inc.com; Fri, 19 Aug 2022 10:12:35 +0800 Message-ID: <5c1c4b01-5ada-5c25-7181-a6f6c2c1f6ed@linux.alibaba.com> Date: Fri, 19 Aug 2022 10:12:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.1.0 Subject: Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func To: SeongJae Park Cc: akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220818171145.51607-1-sj@kernel.org> From: haoxin In-Reply-To: <20220818171145.51607-1-sj@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/8/19 上午1:11, SeongJae Park 写道: > Hi Xin, > > > On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao wrote: > >> In damon_lru_sort_apply_parameters(), if "monitor_region_start" >> and "monitor_region_end" is not a valid physical address range, >> There no need to run the remainder codes in it. > The function, 'damon_lru_sort_apply_parameters()', checks validity of > parameters and construct the DAMON context one by one. For example, > 'damon_set_attrs()' returns an error if the parameters are invalid. So the > intended flow is, > > 1. check DAMON attributes parameters, > 2. apply DAMON attributes parameters, > 3. check scheme parameters, > 4. apply scheme parameters, > 5. check target region parameters, and > 6. apply target region parameters. > > Therefore what this patch does is making the target regions validity check to > be done earlier than validity checks of other parameters. There is no special > reason to check the region earlier than others. Also, this change makes the > flow of the function a little bit weird in my humble opinion, as the flow will > be > > 1. check target region parameters, > 2. check DAMON attributes parameters, > 3. apply DAMON attributes parameters, > 4. check scheme parameters, > 5. apply scheme parameters, and > 6. apply target region parameters. Ok, understand what you mean,   my fix looks ugly,  buy any apply above are not not necessary if one of them checks failed, why not check all fisrt and then apply them, like this: 1. check target region parameters, 2. check DAMON attributes parameters, 3. check scheme parameters, > > So I'd argue this patch seems not really needed, sorry. > > > Thanks, > SJ > > [...]