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 36CEFC433EF for ; Tue, 19 Apr 2022 14:07:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 581198D0075; Tue, 19 Apr 2022 10:07:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 530428D0047; Tue, 19 Apr 2022 10:07:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3D7368D0075; Tue, 19 Apr 2022 10:07:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 2EFE68D0047 for ; Tue, 19 Apr 2022 10:07:58 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 08A6A81470 for ; Tue, 19 Apr 2022 14:07:58 +0000 (UTC) X-FDA: 79373807436.18.FA58FA6 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf16.hostedemail.com (Postfix) with ESMTP id 438E3180013 for ; Tue, 19 Apr 2022 14:07:56 +0000 (UTC) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KjQcG1MX8zhXXP; Tue, 19 Apr 2022 22:07:42 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 19 Apr 2022 22:07:47 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 19 Apr 2022 22:07:46 +0800 Message-ID: <4734132d-bae3-d3ab-33b3-a4c3282ad5cd@huawei.com> Date: Tue, 19 Apr 2022 22:07:46 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH v4] hugetlb: Fix wrong use of nr_online_nodes Content-Language: en-US To: Andrew Morton , Peng Liu CC: , , , , , , , , References: <20220413032915.251254-2-liupeng256@huawei.com> <20220416103526.3287348-1-liupeng256@huawei.com> <20220418210352.1d1d90aeba477d598bd6f0be@linux-foundation.org> From: Kefeng Wang In-Reply-To: <20220418210352.1d1d90aeba477d598bd6f0be@linux-foundation.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 438E3180013 X-Stat-Signature: xipmfyresedgcx45cc9ouw9jcx4iwa6n Authentication-Results: imf16.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf16.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com X-HE-Tag: 1650377276-930036 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 2022/4/19 12:03, Andrew Morton wrote: > On Sat, 16 Apr 2022 10:35:26 +0000 Peng Liu wrote: > >> Certain systems are designed to have sparse/discontiguous nodes. In >> this case, nr_online_nodes can not be used to walk through numa node. >> Also, a valid node may be greater than nr_online_nodes. >> >> However, in hugetlb, it is assumed that nodes are contiguous. Recheck >> all the places that use nr_online_nodes, and repair them one by one. > oops. > > What are the user-visible runtime effects of this flaw? For example, there are four node=0,1,2,3, and nid = 1 is offline node，nr_online_nodes = 3 1) per-node alloc (hugepages=1:2) fails, 2) per-node alloc (hugepages=3:2) fails, but it could succeed. I assume that there is no user-visible runtime effects. > .