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 A9C7EC433F5 for ; Tue, 12 Apr 2022 03:07:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343671AbiDLDJw (ORCPT ); Mon, 11 Apr 2022 23:09:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229488AbiDLDJs (ORCPT ); Mon, 11 Apr 2022 23:09:48 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78A5A1E3F8 for ; Mon, 11 Apr 2022 20:07:31 -0700 (PDT) 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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))) { > > > . >