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 EC554C4332F for ; Thu, 31 Mar 2022 08:02:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232494AbiCaIET (ORCPT ); Thu, 31 Mar 2022 04:04:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232414AbiCaIER (ORCPT ); Thu, 31 Mar 2022 04:04:17 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52B03DAFCB for ; Thu, 31 Mar 2022 01:02:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1648713748; x=1680249748; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=eBg9UJ10yPGgoudu4x1qv1vFubx6B7Wlrl2Xo90m9tQ=; b=POuEHMnf9nANeHNdiGo483aVSZBsoZr9zgkTLQSsuKQP74J4APOfZl6u espyahYu5sI4N+I5Nd4N1C5ceWfYEpq9+jQ4dF3zA6WkcA5R3aRj4rslU qEzvKMXpf6WQ8nEYoKUOI7UCdOphhxweHXRfM1Qn/MqlwLamfwTTn5VYT 7Z/crVdGFj5nG8OGXzaziMobkgenSxaCgpPG9lL1fZelr1bkLjic7kz8n WUdxBo4XyvBOOAv6OsEEyS9kilv8WdFO8cbZ/4WDW31/eIn+6HLTr5sOU L8JC2W9FnsCAOJRQjzk71FqfbJPh6+FjnIc/8hvI0AxKnch5lQ0HBcXqY w==; X-IronPort-AV: E=McAfee;i="6200,9189,10302"; a="259726383" X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="259726383" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Mar 2022 01:02:27 -0700 X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="547211378" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.13.94]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Mar 2022 01:02:26 -0700 From: "Huang, Ying" To: Miaohe Lin Cc: Andrew Morton , Linux Memory Management List , LKML , Muchun Song Subject: Re: [PATCH 1/8] mm/vmscan: remove redundant folio_test_swapbacked check when folio is file lru References: <20220329132619.18689-1-linmiaohe@huawei.com> <20220329132619.18689-2-linmiaohe@huawei.com> <87lewqbpad.fsf@yhuang6-desk2.ccr.corp.intel.com> <7c8d06f6-ac41-d3d7-f6b6-20a06e56dc61@huawei.com> Date: Thu, 31 Mar 2022 16:02:24 +0800 In-Reply-To: <7c8d06f6-ac41-d3d7-f6b6-20a06e56dc61@huawei.com> (Miaohe Lin's message of "Thu, 31 Mar 2022 15:44:03 +0800") Message-ID: <87czi2bldb.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Miaohe Lin writes: > 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? I suggest to drop the code change and add a comment about MADV_FREE. Best Regards, Huang, Ying > Thanks. > >>> So I'm neutral on the patch. >> >> Best Regards, >> Huang, Ying >> . >>