From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 1E10B6B0005 for ; Wed, 18 Apr 2018 07:29:21 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id 88-v6so293123wrc.21 for ; Wed, 18 Apr 2018 04:29:21 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id i5si1144721edc.176.2018.04.18.04.29.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 18 Apr 2018 04:29:19 -0700 (PDT) Date: Wed, 18 Apr 2018 13:29:16 +0200 From: Michal Hocko Subject: Re: [RFC PATCH] mm: correct status code which move_pages() returns for zero page Message-ID: <20180418112916.GX17484@dhcp22.suse.cz> References: <20180417110615.16043-1-liwang@redhat.com> <20180417130300.GF17484@dhcp22.suse.cz> <20180417141442.GG17484@dhcp22.suse.cz> <20180417190044.GK17484@dhcp22.suse.cz> <7674C632-FE3E-42D2-B19D-32F531617043@cs.rutgers.edu> <20180418090722.GV17484@dhcp22.suse.cz> <20180418091943.GW17484@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Li Wang Cc: Zi Yan , linux-mm@kvack.org, ltp@lists.linux.it, "Kirill A . Shutemov" On Wed 18-04-18 18:39:19, Li Wang wrote: > On Wed, Apr 18, 2018 at 5:19 PM, Michal Hocko wrote: > > > On Wed 18-04-18 11:07:22, Michal Hocko wrote: > > > On Tue 17-04-18 16:09:33, Zi Yan wrote: > > [...] > > > > diff --git a/mm/migrate.c b/mm/migrate.c > > > > index f65dd69e1fd1..32afa4723e7f 100644 > > > > --- a/mm/migrate.c > > > > +++ b/mm/migrate.c > > > > @@ -1619,6 +1619,8 @@ static int do_pages_move(struct mm_struct *mm, > > nodemask_t task_nodes, > > > > if (err) > > > > goto out; > > > > } > > > > + /* Move to next page (i+1), after we have saved page > > status (until i) */ > > > > + start = i + 1; > > > > current_node = NUMA_NO_NODE; > > > > } > > > > out_flush: > > > > > > > > Feel free to check it by yourselves. > > > > > > Yes, you are right. I never update start if the last page in the range > > > fails and so we overwrite the whole [start, i] range. I wish the code > > > wasn't that ugly and subtle but considering how we can fail in different > > > ways and that we want to batch as much as possible I do not see an easy > > > way. > > > > > > Care to send the patch? I would just drop the comment. > > > > Hmm, thinking about it some more. An alternative would be to check for > > list_empty on the page list. It is a bit larger diff but maybe that > > would be tiny bit cleaner because there is simply no point to call > > do_move_pages_to_node on an empty list in the first place. > > > > a??Hi Michal, Zi > > I tried your patch separately, both of them works fine to me. Thanks for retesting! Do you plan to post a patch with the changelog or should I do it? -- Michal Hocko SUSE Labs