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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A392C433EF for ; Tue, 12 Apr 2022 03:07:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C6BA36B0071; Mon, 11 Apr 2022 23:07:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C1AC96B0073; Mon, 11 Apr 2022 23:07:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE2016B0074; Mon, 11 Apr 2022 23:07:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.28]) by kanga.kvack.org (Postfix) with ESMTP id 9C1E16B0071 for ; Mon, 11 Apr 2022 23:07:33 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id 656F3120E43 for ; Tue, 12 Apr 2022 03:07:33 +0000 (UTC) X-FDA: 79346741586.04.76515D9 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf22.hostedemail.com (Postfix) with ESMTP id 90450C0002 for ; Tue, 12 Apr 2022 03:07:32 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KcrBn0K8nzBsBk; Tue, 12 Apr 2022 11:03:13 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 12 Apr 2022 11:07:29 +0800 Subject: Re: [PATCH v2 1/9] mm/vmscan: add a comment about MADV_FREE pages check in folio_check_dirty_writeback To: "ying.huang@intel.com" CC: , , , , , Andrew Morton References: <20220409093500.10329-1-linmiaohe@huawei.com> <20220409093500.10329-2-linmiaohe@huawei.com> <4b7923585e07b0238545ebb997af92eeadcdaf78.camel@intel.com> From: Miaohe Lin Message-ID: <2a97ce77-42c8-15ea-50c4-fc18fd7fe693@huawei.com> Date: Tue, 12 Apr 2022 11:07:29 +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: <4b7923585e07b0238545ebb997af92eeadcdaf78.camel@intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 90450C0002 X-Stat-Signature: 7ap4soeoizzc6wzwfny4b9njcr3no17b Authentication-Results: imf22.hostedemail.com; dkim=none; spf=pass (imf22.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-HE-Tag: 1649732852-232571 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/4/11 19:50, ying.huang@intel.com wrote: > On Sat, 2022-04-09 at 17:34 +0800, Miaohe Lin wrote: >> The MADV_FREE pages check in folio_check_dirty_writeback is a bit hard to >> follow. Add a comment to make the code clear. >> >> Suggested-by: Huang, Ying >> Signed-off-by: Miaohe Lin >> --- >>  mm/vmscan.c | 3 +++ >>  1 file changed, 3 insertions(+) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index c77d5052f230..4a76be47bed1 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1436,6 +1436,9 @@ static void folio_check_dirty_writeback(struct folio >> *folio, >>         /* >>          * Anonymous pages are not handled by flushers and must be written >>          * from reclaim context. Do not stall reclaim based on them >> +        * MADV_FREE anonymous pages are put into inactive file list too. >> +        * They could be mistakenly treated as file lru. So further anon >> +        * test is needed. >>          */ > > How about something as follows, > > /* > * Anonymous pages (including MADV_FREE ones) are not handled > by * flushers and must be written from reclaim context. Do not stall > * reclaim based on them > */. > This comment looks good but it seems it doesn't explain the MADV_FREE check logic. Is this already enough? If so, will change to use this. Thanks! > Best Regards, > Huang, Ying > >>         if (!folio_is_file_lru(folio) || >>             (folio_test_anon(folio) && !folio_test_swapbacked(folio))) { > > > . >