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 9BC92C7618E for ; Mon, 24 Apr 2023 10:46:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231278AbjDXKqs (ORCPT ); Mon, 24 Apr 2023 06:46:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230255AbjDXKqq (ORCPT ); Mon, 24 Apr 2023 06:46:46 -0400 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CCD91FE0 for ; Mon, 24 Apr 2023 03:46:44 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0VgtI39q_1682333200; Received: from 30.97.48.59(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VgtI39q_1682333200) by smtp.aliyun-inc.com; Mon, 24 Apr 2023 18:46:41 +0800 Message-ID: <7525a9f6-b431-4404-2878-898e52905d4a@linux.alibaba.com> Date: Mon, 24 Apr 2023 18:46:40 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v2 1/2] mm/page_alloc: drop the unnecessary pfn_valid() for start pfn To: Michal Hocko Cc: akpm@linux-foundation.org, rppt@kernel.org, ying.huang@intel.com, mgorman@techsingularity.net, vbabka@suse.cz, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <9fc85cce8908938f4fd75ff50bc981c073779aa5.1682229876.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/24/2023 5:50 PM, Michal Hocko wrote: > On Sun 23-04-23 18:59:10, Baolin Wang wrote: >> We've already used pfn_to_online_page() for start pfn to make sure > > Who is we? I do not see any note explicitly requiring that start_pfn has > to be valid for __pageblock_pfn_to_page. Sorry for confusing, what I mean is the __pageblock_pfn_to_page() function, which has used pfn_to_online_page() for start pfn. So the pfn_valid() in __pageblock_pfn_to_page() for start pfn is unnecessary. I will update the commit log to make it clear. >> it is online and valid, so the pfn_valid() for the start pfn is >> unnecessary, drop it. >> >> Signed-off-by: Baolin Wang >> Reviewed-by: David Hildenbrand >> Reviewed-by: "Huang, Ying" >> --- >> Changes from v1: >> - Collect reviewed tags. Thanks David and Ying. >> --- >> mm/page_alloc.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 9de2a18519a1..6457b64fe562 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1512,7 +1512,7 @@ struct page *__pageblock_pfn_to_page(unsigned long start_pfn, >> /* end_pfn is one past the range we are checking */ >> end_pfn--; >> >> - if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) >> + if (!pfn_valid(end_pfn)) >> return NULL; >> >> start_page = pfn_to_online_page(start_pfn); >> -- >> 2.27.0 >