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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 7BCF9C11F69 for ; Mon, 12 Jul 2021 11:18:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6774B61003 for ; Mon, 12 Jul 2021 11:18:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236625AbhGLLVZ (ORCPT ); Mon, 12 Jul 2021 07:21:25 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:11263 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237966AbhGLLTi (ORCPT ); Mon, 12 Jul 2021 07:19:38 -0400 Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4GNh0J6FPSz1CJ2k; Mon, 12 Jul 2021 19:11:12 +0800 (CST) Received: from [10.174.178.125] (10.174.178.125) by dggeme703-chm.china.huawei.com (10.1.199.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Mon, 12 Jul 2021 19:16:47 +0800 Subject: Re: [PATCH 5/5] mm/vmscan: fix misleading comment in isolate_lru_pages() To: Michal Hocko CC: , , , , , , , , , , , , , References: <20210710100329.49174-1-linmiaohe@huawei.com> <20210710100329.49174-6-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Mon, 12 Jul 2021 19:16:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.125] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/7/12 15:28, Michal Hocko wrote: > On Sat 10-07-21 18:03:29, Miaohe Lin wrote: >> We couldn't know whether the page is being freed elsewhere until we failed >> to increase the page count. > > This is moving a hard to understand comment from one place to another. If get_page_unless_zero failed, the page could have been freed elsewhere. I think this looks straightforward but doesn't help a lot. Are you preferring to just remove this comment ? Thank you. > If anything this would benefit from what that elsewhere might be > typically or simply drop the comment altogether. > >> >> Signed-off-by: Miaohe Lin >> --- >> mm/vmscan.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index a74760c48bd8..6e26b3c93242 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1891,7 +1891,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, >> */ >> scan += nr_pages; >> if (!__isolate_lru_page_prepare(page, mode)) { >> - /* It is being freed elsewhere */ >> list_move(&page->lru, src); >> continue; >> } >> @@ -1901,6 +1900,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, >> * page release code relies on it. >> */ >> if (unlikely(!get_page_unless_zero(page))) { >> + /* It is being freed elsewhere. */ >> list_move(&page->lru, src); >> continue; >> } >> -- >> 2.23.0 >