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 193D9C433EF for ; Mon, 7 Mar 2022 12:11:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 91B8B8D0002; Mon, 7 Mar 2022 07:11:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8CC448D0001; Mon, 7 Mar 2022 07:11:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7E2228D0002; Mon, 7 Mar 2022 07:11:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 6E5F08D0001 for ; Mon, 7 Mar 2022 07:11:51 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id 391271206BE for ; Mon, 7 Mar 2022 12:11:51 +0000 (UTC) X-FDA: 79217476422.09.340373C Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf13.hostedemail.com (Postfix) with ESMTP id 1A89F2000E for ; Mon, 7 Mar 2022 12:11:49 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KBy2p53RtzdZlC; Mon, 7 Mar 2022 20:10:26 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 7 Mar 2022 20:11:46 +0800 Subject: Re: [PATCH 12/16] mm/migration: fix potential page refcounts leak in migrate_pages To: "Huang, Ying" CC: , , , , , , , , , , , , , , , , , References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-13-linmiaohe@huawei.com> <87r17e5pat.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <3a93cba2-c877-73c6-e355-0b73fcb02cc6@huawei.com> Date: Mon, 7 Mar 2022 20:11:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <87r17e5pat.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1A89F2000E X-Stat-Signature: b6kkpkk8hk58bps9t1jjw7minw19xpn6 Authentication-Results: imf13.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf13.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-HE-Tag: 1646655109-738468 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 2022/3/7 13:01, Huang, Ying wrote: > Miaohe Lin writes: > >> 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; > > It appears that we don't need to change nr_failed, because we don't use > it for this situation. Otherwise looks good to me. > You're right. nr_failed is not used for this case. > Reviewed-by: "Huang, Ying" Many thanks for your review. > > Best Regards, > Huang, Ying > >> + nr_thp_failed += thp_retry; >> goto out; >> case -EAGAIN: >> if (is_thp) > . >