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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C64ADC433EF for ; Tue, 8 Mar 2022 12:12:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346717AbiCHMNh (ORCPT ); Tue, 8 Mar 2022 07:13:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236809AbiCHMN3 (ORCPT ); Tue, 8 Mar 2022 07:13:29 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4026062E6 for ; Tue, 8 Mar 2022 04:12:32 -0800 (PST) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KCYxB56Xdzbc92; Tue, 8 Mar 2022 20:07:42 +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; Tue, 8 Mar 2022 20:12:29 +0800 Subject: Re: [PATCH 13/16] mm/migration: return errno when isolate_huge_page failed To: "Huang, Ying" CC: , , , , , , , , , , , , , , , , , References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-14-linmiaohe@huawei.com> <87ilsq5p0x.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <85acb60f-76a6-2cbc-0896-a593531dfc27@huawei.com> Date: Tue, 8 Mar 2022 20:12:28 +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: <87ilsq5p0x.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: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/3/7 13:07, Huang, Ying wrote: > Miaohe Lin writes: > >> 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; > > IMHO, it's better to determine the proper errno inside > isolate_huge_page() instead of in the caller. If you think it's > necessary to get errno here. How about change isolate_huge_page() > instead? IMO, -EBUSY should be enough for the user (as they could not do much) and this errno keeps consistent with the non-hugetlb page case. What do you think? Thanks. > > Best Regards, > Huang, Ying > >> } else { >> struct page *head; > . >