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 981FAC433F5 for ; Wed, 9 Mar 2022 08:29:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231358AbiCIIaK (ORCPT ); Wed, 9 Mar 2022 03:30:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230413AbiCIIaI (ORCPT ); Wed, 9 Mar 2022 03:30:08 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44EE5BB0AD for ; Wed, 9 Mar 2022 00:29:10 -0800 (PST) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KD50K2S0rzBrSj; Wed, 9 Mar 2022 16:27:13 +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; Wed, 9 Mar 2022 16:29:07 +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> <85acb60f-76a6-2cbc-0896-a593531dfc27@huawei.com> <8735jsgctq.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Miaohe Lin Message-ID: <8ff5c0d7-bc5b-6991-6daa-d4c62d019dbb@huawei.com> Date: Wed, 9 Mar 2022 16:29:06 +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: <8735jsgctq.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: dggems703-chm.china.huawei.com (10.3.19.180) 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 2022/3/9 9:00, Huang, Ying wrote: > Miaohe Lin writes: > >> 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? > > I found the prototype of isolate_lru_page() is as follows, > > int isolate_lru_page(struct page *page) > > And it will return errno directly. I think we should follow same > convention here? > I see. Sounds reasonable to me. Will try to do it. Thanks. > Best Regards, > Huang, Ying > . >