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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 0631AC32771 for ; Tue, 21 Jan 2020 01:44:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C8AB822522 for ; Tue, 21 Jan 2020 01:44:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8AB822522 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 5395F6B0003; Mon, 20 Jan 2020 20:44:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4EB226B0005; Mon, 20 Jan 2020 20:44:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 427696B0006; Mon, 20 Jan 2020 20:44:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 2B3E66B0003 for ; Mon, 20 Jan 2020 20:44:11 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id C17D7180AD801 for ; Tue, 21 Jan 2020 01:44:10 +0000 (UTC) X-FDA: 76399945860.14.rate63_74dcd124f808 X-HE-Tag: rate63_74dcd124f808 X-Filterd-Recvd-Size: 3555 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Tue, 21 Jan 2020 01:44:09 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Jan 2020 17:44:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,344,1574150400"; d="scan'208";a="307056935" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga001.jf.intel.com with ESMTP; 20 Jan 2020 17:44:05 -0800 Date: Tue, 21 Jan 2020 09:44:16 +0800 From: Wei Yang To: Michal Hocko Cc: Yang Shi , richardw.yang@linux.intel.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm: move_pages: fix the return value if there are not-migrated pages Message-ID: <20200121014416.GC1567@richard> Reply-To: Wei Yang References: <1579325203-16405-1-git-send-email-yang.shi@linux.alibaba.com> <20200120130624.GD18451@dhcp22.suse.cz> <20200120131744.GE18451@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200120131744.GE18451@dhcp22.suse.cz> 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 Mon, Jan 20, 2020 at 02:17:44PM +0100, Michal Hocko wrote: >On Mon 20-01-20 14:06:26, Michal Hocko wrote: >> On Sat 18-01-20 13:26:43, Yang Shi wrote: >> > The do_move_pages_to_node() might return > 0 value, the number of pages >> > that are not migrated, then the value will be returned to userspace >> > directly. But, move_pages() syscall would just return 0 or errno. So, >> > we need reset the return value to 0 for such case as what pre-v4.17 did. >> >> The patch is wrong. migrate_pages returns the number of pages it >> _hasn't_ migrated or -errno. Yeah that semantic sucks but... >> So err != 0 is always an error. Except err > 0 doesn't really provide >> any useful information to the userspace. I cannot really remember what >> was the actual behavior before my rework because there were some gotchas >> hidden there. > >OK, so I've double checked. do_move_page_to_node_array would carry the >error code over to do_pages_move and it would store the status stored >in the pm array. It contains page_to_nid(page) so the resulting code >indeed behaves properly before my change and this is a regression. I Thanks, I see the change. >have a very vague recollection that this has been brought up already. ><...looks in notes...> >Found it! The report is >http://lkml.kernel.org/r/0329efa0984b9b0252ef166abb4498c0795fab36.1535113317.git.jstancek@redhat.com >and my proposed workaround was http://lkml.kernel.org/r/20180829145537.GZ10223@dhcp22.suse.cz Well, the above two links return 404. > >> If you want to fix this properly then you have to query node status of >> each page unmigrated when migrate_pages fails with > 0. This would be >> easier if the fix is done on the latest cleanup posted to the list which >> consolidates all do_move_pages_to_node and store_status calls to a >> single function. > >Sorry forgot to put a reference to the patch: http://lkml.kernel.org/r/20200119030636.11899-5-richardw.yang@linux.intel.com > >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me