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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E09FC433F5 for ; Mon, 7 Mar 2022 02:13:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ADD368D0002; Sun, 6 Mar 2022 21:13:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A8D108D0001; Sun, 6 Mar 2022 21:13:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 954848D0002; Sun, 6 Mar 2022 21:13:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0056.hostedemail.com [216.40.44.56]) by kanga.kvack.org (Postfix) with ESMTP id 835778D0001 for ; Sun, 6 Mar 2022 21:13:41 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3FEFB9F877 for ; Mon, 7 Mar 2022 02:13:41 +0000 (UTC) X-FDA: 79215969042.29.DDB66F5 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by imf27.hostedemail.com (Postfix) with ESMTP id 7086840006 for ; Mon, 7 Mar 2022 02:13:39 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=20;SR=0;TI=SMTPD_---0V6OapQN_1646619214; Received: from 30.97.48.83(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0V6OapQN_1646619214) by smtp.aliyun-inc.com(127.0.0.1); Mon, 07 Mar 2022 10:13:35 +0800 Message-ID: Date: Mon, 7 Mar 2022 10:14:37 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [PATCH 13/16] mm/migration: return errno when isolate_huge_page failed To: Miaohe Lin , akpm@linux-foundation.org Cc: mike.kravetz@oracle.com, shy828301@gmail.com, willy@infradead.org, ying.huang@intel.com, ziy@nvidia.com, minchan@kernel.org, apopple@nvidia.com, ave.hansen@linux.intel.com, o451686892@gmail.com, almasrymina@google.com, jhubbard@nvidia.com, rcampbell@nvidia.com, peterx@redhat.com, naoya.horiguchi@nec.com, mhocko@suse.com, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-14-linmiaohe@huawei.com> From: Baolin Wang In-Reply-To: <20220304093409.25829-14-linmiaohe@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: n1i69t9f49xqf15swh6fkrucxxmn66ya Authentication-Results: imf27.hostedemail.com; dkim=none; spf=pass (imf27.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.133 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-Rspamd-Queue-Id: 7086840006 X-HE-Tag: 1646619219-980855 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: Hi Miaohe, On 3/4/2022 5:34 PM, Miaohe Lin wrote: > We should return errno (-EBUSY here) when failed to isolate the huge page > rather than always return 1 which could confuse the user. > > Signed-off-by: Miaohe Lin > --- > mm/migrate.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 6c2dfed2ddb8..279940c0c064 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1618,10 +1618,8 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, > goto out_putpage; > > if (PageHuge(page)) { > - if (PageHead(page)) { > - isolate_huge_page(page, pagelist); > - err = 1; > - } > + if (PageHead(page)) > + err = isolate_huge_page(page, pagelist) ? 1 : -EBUSY; Could you elaborate on which case the huge page isolation can be failed in this case? Or you met a real problem? Cause now we've got this head huge page refcnt, I can not see why we'll fail to isolate this huge page.