From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by kanga.kvack.org (Postfix) with ESMTP id 350606B0005 for ; Thu, 1 Nov 2018 05:11:01 -0400 (EDT) Received: by mail-qt1-f197.google.com with SMTP id x8-v6so19918318qtc.15 for ; Thu, 01 Nov 2018 02:11:01 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id u79si2443113qki.223.2018.11.01.02.10.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Nov 2018 02:11:00 -0700 (PDT) Date: Thu, 1 Nov 2018 17:10:55 +0800 From: Baoquan He Subject: Memory hotplug failed to offline on bare metal system of multiple nodes Message-ID: <20181101091055.GA15166@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@suse.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi, A hot removal failure was met on one bare metal system with 8 nodes, and node1~7 are all hotpluggable and 'movable_node' is set. When try to check value of /sys/devices/system/node/node1/memory*/removable, found some of them are 0, namely un-removable. And a back trace will always be seen. After bisecting, it points at criminal commit: 15c30bc09085 ("mm, memory_hotplug: make has_unmovable_pages more robust") Reverting it fix the failure, and node1~7 can be hot removed and hot added again. From the log of commit 15c30bc09085, it's to fix a movable_core setting issue which we allocated node_data firstly in initmem_init(), then try to mark it as movable in mm_init(). We may need think about it further to fix it, meanwhile not breaking bare metal system. I haven't figured out why the above commit caused those memmory block in MOVABL zone being not removable. Still checking. Attach the tested reverting patch in this mail. Thanks Baoquan