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=unavailable 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 5659CC33CB7 for ; Wed, 29 Jan 2020 22:07:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 232EC20702 for ; Wed, 29 Jan 2020 22:07:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 232EC20702 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 AED306B02A5; Wed, 29 Jan 2020 17:07:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A9D196B02A6; Wed, 29 Jan 2020 17:07:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9B19E6B02A7; Wed, 29 Jan 2020 17:07:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id 75BAC6B02A5 for ; Wed, 29 Jan 2020 17:07:15 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 14EB340D6 for ; Wed, 29 Jan 2020 22:07:15 +0000 (UTC) X-FDA: 76432058430.02.talk09_5c54ef360f729 X-HE-Tag: talk09_5c54ef360f729 X-Filterd-Recvd-Size: 4801 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Jan 2020 22:07:14 +0000 (UTC) X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jan 2020 14:07:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,379,1574150400"; d="scan'208";a="218082796" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga007.jf.intel.com with ESMTP; 29 Jan 2020 14:07:10 -0800 Date: Thu, 30 Jan 2020 06:07:23 +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 4/4] mm/migrate.c: handle same node and add failure in the same way Message-ID: <20200129220723.GC20736@richard> Reply-To: Wei Yang References: <20200122011647.13636-1-richardw.yang@linux.intel.com> <20200122011647.13636-5-richardw.yang@linux.intel.com> <17796dbb-b9b6-9481-5048-addfa5eec51e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17796dbb-b9b6-9481-5048-addfa5eec51e@redhat.com> 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 Wed, Jan 29, 2020 at 11:13:23AM +0100, David Hildenbrand wrote: >On 22.01.20 02:16, Wei Yang wrote: >> When page is not queued for migration, there are two possible cases: >> >> * page already on the target node >> * failed to add to migration queue >> >> Current code handle them differently, this leads to a behavior >> inconsistency. >> >> Usually for each page's status, we just do store for once. While for the >> page already on the target node, we might store the node information for >> twice: >> >> * once when we found the page is on the target node >> * second when moving the pages to target node successfully after above >> action >> >> The reason is even we don't add the page to pagelist, but store_status() >> does store in a range which still contains the page. >> >> This patch handles these two cases in the same way to reduce this >> inconsistency and also make the code a little easier to read. >> > >I'd rephrase to > >"mm/migrate.c: unify "not queued for migration" handling in do_pages_move() > >It can currently happen that we store the status of a page twice: >* Once we detect that it is already on the target node >* Once we moved a bunch of pages, and a page that's already on the > target node is contained in the current interval. > >Let's simplify the code and always call do_move_pages_to_node() in >case we did not queue a page for migration. Note that pages that are >already on the target node are not added to the pagelist and are, >therefore, ignored by do_move_pages_to_node() - there is no functional >change. > >The status of such a page is now only stored once. >" > >> Signed-off-by: Wei Yang >> Acked-by: Michal Hocko >> --- >> mm/migrate.c | 16 ++++++++-------- >> 1 file changed, 8 insertions(+), 8 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 80d2bba57265..591f2e5caed6 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1654,18 +1654,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, >> err = add_page_for_migration(mm, addr, current_node, >> &pagelist, flags & MPOL_MF_MOVE_ALL); >> >> - if (!err) { >> - /* The page is already on the target node */ >> - err = store_status(status, i, current_node, 1); >> - if (err) >> - goto out_flush; >> - continue; >> - } else if (err > 0) { >> + if (err > 0) { >> /* The page is successfully queued for migration */ >> continue; >> } >> >> - err = store_status(status, i, err, 1); >> + /* >> + * Two possible cases for err here: >> + * == 0: page is already on the target node, then store >> + * current_node to status >> + * < 0: failed to add page to list, then store err to status >> + */ > >I'd shorten that to > >/* > * If the page is already on the target node (!err), store the node, > * otherwise, store the err. >*/ > >> + err = store_status(status, i, err ? : current_node, 1); >> if (err) >> goto out_flush; >> >> > >Thanks! > >Reviewed-by: David Hildenbrand > Yep, thanks. I would take this :-) >-- >Thanks, > >David / dhildenb -- Wei Yang Help you, Help me