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 604D1C433EF for ; Thu, 31 Mar 2022 07:44:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 889E48D0001; Thu, 31 Mar 2022 03:44:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 839F76B0073; Thu, 31 Mar 2022 03:44:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 702A28D0001; Thu, 31 Mar 2022 03:44:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 600136B0072 for ; Thu, 31 Mar 2022 03:44:10 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 12317F98 for ; Thu, 31 Mar 2022 07:44:10 +0000 (UTC) X-FDA: 79303893060.15.53DAE60 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf01.hostedemail.com (Postfix) with ESMTP id F2AAF4000C for ; Thu, 31 Mar 2022 07:44:08 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KTb0208TjzdZQw; Thu, 31 Mar 2022 15:43:46 +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 15.1.2308.21; Thu, 31 Mar 2022 15:44:04 +0800 Subject: Re: [PATCH 1/8] mm/vmscan: remove redundant folio_test_swapbacked check when folio is file lru To: "Huang, Ying" CC: Andrew Morton , Linux Memory Management List , LKML , Muchun Song References: <20220329132619.18689-1-linmiaohe@huawei.com> <20220329132619.18689-2-linmiaohe@huawei.com> <87lewqbpad.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <7c8d06f6-ac41-d3d7-f6b6-20a06e56dc61@huawei.com> Date: Thu, 31 Mar 2022 15:44:03 +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: <87lewqbpad.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit 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: F2AAF4000C X-Stat-Signature: c6ips67u9azmqobhxe7wcnz3ae4j16iy Authentication-Results: imf01.hostedemail.com; dkim=none; spf=pass (imf01.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-HE-Tag: 1648712648-188547 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 2022/3/31 14:37, Huang, Ying wrote: > Muchun Song writes: > >> On Tue, Mar 29, 2022 at 9:26 PM Miaohe Lin wrote: >>> >>> When folio is file lru, folio_test_swapbacked is guaranteed to be true. So >>> it's unnecessary to check it here again. No functional change intended. >>> >>> Signed-off-by: Miaohe Lin >>> --- >>> mm/vmscan.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/mm/vmscan.c b/mm/vmscan.c >>> index 1678802e03e7..7c1a9713bfc9 100644 >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -1434,8 +1434,7 @@ 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 >>> */ >>> - if (!folio_is_file_lru(folio) || >>> - (folio_test_anon(folio) && !folio_test_swapbacked(folio))) { >>> + if (!folio_is_file_lru(folio) || folio_test_anon(folio)) { >> >> At least your login is no problem since folio_is_file_lru() is equal to >> !folio_test_swapbacked(). But the new code is not clear to me. >> The old code is easy to understand, e.g. folio_test_anon(folio) && >> !folio_test_swapbacked(folio) tells us that the anon pages which >> do not need to be swapped should be skipped. > > That is for MADV_FREE pages. The code is introduced in commit > 802a3a92ad7a ("mm: reclaim MADV_FREE pages"). > > So I think the original code is better. It's an implementation detail > that folio_is_file_lru() equals !folio_test_swapbacked(). It may be > better to add some comments here for MADV_FREE pages. > Do you tend to drop this patch or adding a comment with the change in this patch or something else? Thanks. >> So I'm neutral on the patch. > > Best Regards, > Huang, Ying > . >