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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 E74BAC33C9E for ; Wed, 29 Jan 2020 00:46:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9B5182073A for ; Wed, 29 Jan 2020 00:46:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B5182073A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3884A6B0006; Tue, 28 Jan 2020 19:46:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3385E6B0008; Tue, 28 Jan 2020 19:46:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 24EE46B000A; Tue, 28 Jan 2020 19:46:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0187.hostedemail.com [216.40.44.187]) by kanga.kvack.org (Postfix) with ESMTP id 0D72D6B0006 for ; Tue, 28 Jan 2020 19:46:29 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D0B2C45B3 for ; Wed, 29 Jan 2020 00:46:28 +0000 (UTC) X-FDA: 76428830856.19.fact73_72b4f432c3a0f X-HE-Tag: fact73_72b4f432c3a0f X-Filterd-Recvd-Size: 3247 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Jan 2020 00:46:28 +0000 (UTC) X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Jan 2020 16:46:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,376,1574150400"; d="scan'208";a="222916704" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga007.fm.intel.com with ESMTP; 28 Jan 2020 16:46:25 -0800 Date: Wed, 29 Jan 2020 08:46:37 +0800 From: Wei Yang To: David Hildenbrand Cc: Wei Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@suse.com, yang.shi@linux.alibaba.com, rientjes@google.com Subject: Re: [Patch v2 3/4] mm/migrate.c: check pagelist in move_pages_and_store_status() Message-ID: <20200129004637.GD12835@richard> Reply-To: Wei Yang References: <20200122011647.13636-1-richardw.yang@linux.intel.com> <20200122011647.13636-4-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) 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 Tue, Jan 28, 2020 at 11:21:13AM +0100, David Hildenbrand wrote: >On 22.01.20 02:16, Wei Yang wrote: >> When pagelist is empty, it is not necessary to do the move and store. >> Also it consolidate the empty list check in one place. >> >> Signed-off-by: Wei Yang >> Acked-by: Michal Hocko >> --- >> mm/migrate.c | 9 +++------ >> 1 file changed, 3 insertions(+), 6 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index a4d3bd6475e1..80d2bba57265 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm, >> { >> int err; >> >> - if (list_empty(pagelist)) >> - return 0; >> - >> err = migrate_pages(pagelist, alloc_new_node_page, NULL, node, >> MIGRATE_SYNC, MR_SYSCALL); >> if (err) >> @@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node, >> { >> int err; >> >> + if (list_empty(pagelist)) >> + return 0; >> + >> err = do_move_pages_to_node(mm, pagelist, node); >> if (err) >> return err; >> @@ -1676,9 +1676,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, >> current_node = NUMA_NO_NODE; >> } >> out_flush: >> - if (list_empty(&pagelist)) >> - return err; > > >Am I wrong or are you discarding an error here? (err could be !0) > This is not obvious in this code snippet. If you look into the source code, it might help you get the whole picture. The following comment says: Make sure we do not overwrite the existing error So we didn't eat error here. > >-- >Thanks, > >David / dhildenb -- Wei Yang Help you, Help me