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 1425DC433EF for ; Mon, 9 May 2022 08:03:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4E6D16B0071; Mon, 9 May 2022 04:03:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 496DB6B0073; Mon, 9 May 2022 04:03:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3AF006B0074; Mon, 9 May 2022 04:03:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 2D5826B0071 for ; Mon, 9 May 2022 04:03:09 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id F032180D10 for ; Mon, 9 May 2022 08:03:08 +0000 (UTC) X-FDA: 79445464056.24.C895220 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf16.hostedemail.com (Postfix) with ESMTP id 8F49818009B for ; Mon, 9 May 2022 08:02:59 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KxYW61wz5zGpcf; Mon, 9 May 2022 16:00:18 +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 15.1.2375.24; Mon, 9 May 2022 16:03:04 +0800 Subject: Re: [PATCH v2 3/4] mm/migration: return errno when isolate_huge_page failed To: David Hildenbrand CC: , , , , , , , , References: <20220425132723.34824-1-linmiaohe@huawei.com> <20220425132723.34824-4-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Mon, 9 May 2022 16:03:04 +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: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Stat-Signature: r4ps31ered7cz5pjdd6jo7ntm1cdohdj Authentication-Results: imf16.hostedemail.com; dkim=none; spf=pass (imf16.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 8F49818009B X-HE-Tag: 1652083379-935581 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 2022/4/29 18:08, David Hildenbrand wrote: > On 25.04.22 15:27, Miaohe Lin wrote: >> We might fail to isolate huge page due to e.g. the page is under migration >> which cleared HPageMigratable. So we should return -EBUSY in this case >> rather than always return 1 which could confuse the user. Also we make >> the prototype of isolate_huge_page consistent with isolate_lru_page to >> improve the readability. >> >> Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration") > > If this is a fix, what's the runtime effect of it? > > You state "could confuse", which doesn't indicate an actual BUG to me. The hugetlb page might not be migrated due to error while it's not reported in the __user *status. So the caller might think all of the memory is migrated and thus does not retry to migrate the hugetlb page in the next round. Is this too trival to bother adding a Fixes tag? Thanks! > >