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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 B6790C433E7 for ; Fri, 16 Oct 2020 15:05:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69D0A20866 for ; Fri, 16 Oct 2020 15:05:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409782AbgJPPFy (ORCPT ); Fri, 16 Oct 2020 11:05:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:55946 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409774AbgJPPFx (ORCPT ); Fri, 16 Oct 2020 11:05:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E21BBADA2; Fri, 16 Oct 2020 15:05:52 +0000 (UTC) Subject: Re: [PATCH] mm/compaction: Remove some useless code in compact_zone() To: David Hildenbrand , yanfei.xu@windriver.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20201014072349.34494-1-yanfei.xu@windriver.com> From: Vlastimil Babka Message-ID: Date: Fri, 16 Oct 2020 17:05:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/14/20 2:28 PM, David Hildenbrand wrote: > On 14.10.20 09:23, yanfei.xu@windriver.com wrote: >> From: Yanfei Xu >> >> start_pfn has been declared at the begin of compact_zone(), it's >> no need to declare it again. And remove an useless semicolon. >> >> Signed-off-by: Yanfei Xu >> --- >> mm/compaction.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 176dcded298e..5e69c1f94d96 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -2272,7 +2272,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) >> >> while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) { >> int err; >> - unsigned long start_pfn = cc->migrate_pfn; >> + start_pfn = cc->migrate_pfn; > > There is a user in > > trace_mm_compaction_end(start_pfn, cc->migrate_pfn, cc->free_pfn, > end_pfn, sync, ret); > > we would now trace a different value, no? Agreed. We should rather rename the while-local one to avoid confusion. Something like "iteration_start_pfn" ? >> >> /* >> * Avoid multiple rescans which can happen if a page cannot be >> @@ -2309,7 +2309,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) >> case ISOLATE_SUCCESS: >> update_cached = false; >> last_migrated_pfn = start_pfn; >> - ; > > Huh, how does something like that happen :) Looks like "case ISOLATE_SUCCESS:" used to be an empty implementation, then statements got added, but semicolon not removed.