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 9D008C433F5 for ; Mon, 7 Mar 2022 01:56:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 01B248D0002; Sun, 6 Mar 2022 20:56:36 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE4458D0001; Sun, 6 Mar 2022 20:56:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D5DCB8D0002; Sun, 6 Mar 2022 20:56:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id C0B918D0001 for ; Sun, 6 Mar 2022 20:56:35 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7719F18211CD3 for ; Mon, 7 Mar 2022 01:56:35 +0000 (UTC) X-FDA: 79215925950.20.F132328 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by imf02.hostedemail.com (Postfix) with ESMTP id D951280006 for ; Mon, 7 Mar 2022 01:56:33 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R741e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=20;SR=0;TI=SMTPD_---0V6OHp72_1646618187; Received: from 30.97.48.83(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0V6OHp72_1646618187) by smtp.aliyun-inc.com(127.0.0.1); Mon, 07 Mar 2022 09:56:29 +0800 Message-ID: <20f47ec9-3b5b-5326-b1c3-4b1a0c38ef46@linux.alibaba.com> Date: Mon, 7 Mar 2022 09:57:30 +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 12/16] mm/migration: fix potential page refcounts leak in migrate_pages 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> <20220304093409.25829-13-linmiaohe@huawei.com> From: Baolin Wang In-Reply-To: <20220304093409.25829-13-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: gycrggq3t4z6orie4idj9bkqoiyy8mdz Authentication-Results: imf02.hostedemail.com; dkim=none; spf=pass (imf02.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: D951280006 X-HE-Tag: 1646618193-287812 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: > In -ENOMEM case, there might be some subpages of fail-to-migrate THPs > left in thp_split_pages list. We should move them back to migration > list so that they could be put back to the right list by the caller > otherwise the page refcnt will be leaked here. Also adjust nr_failed > and nr_thp_failed accordingly to make vm events account more accurate. > > Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()") > Signed-off-by: Miaohe Lin > --- > mm/migrate.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/migrate.c b/mm/migrate.c > index e0db06927f02..6c2dfed2ddb8 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1422,6 +1422,15 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > } > > nr_failed_pages += nr_subpages; > + /* > + * There might be some subpages of fail-to-migrate THPs > + * left in thp_split_pages list. Move them back to migration > + * list so that they could be put back to the right list by > + * the caller otherwise the page refcnt will be leaked. > + */ > + list_splice_init(&thp_split_pages, from); > + nr_failed += retry; > + nr_thp_failed += thp_retry; Yes, I think we missed this case before, and your patch looks right. But we should also update the 'rc' to return the correct number of pages that were not migrated, right?