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From: Baoquan He <bhe@redhat.com>
To: mhocko@suse.com, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Memory hotplug failed to offline on bare metal system of multiple nodes
Date: Thu, 1 Nov 2018 17:10:55 +0800
Message-ID: <20181101091055.GA15166@MiWiFi-R3L-srv> (raw)

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

             reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-01  9:10 Baoquan He [this message]
2018-11-01  9:22 ` Michal Hocko
2018-11-01  9:42   ` Baoquan He
2018-11-01  9:58     ` Michal Hocko
2018-11-02 15:55 ` [PATCH] mm, memory_hotplug: teach has_unmovable_pages about of LRU migrateable pages Michal Hocko
2018-11-05  0:20   ` Baoquan He
2018-11-05  9:14     ` Michal Hocko
2018-11-05  9:26       ` Baoquan He
2018-11-05  9:35         ` Michal Hocko
2018-11-05  9:28       ` Michal Hocko
2018-11-05  9:45         ` Baoquan He
2018-11-05 10:25         ` Baoquan He
2018-11-05 12:38           ` Michal Hocko
2018-11-05 14:23             ` Baoquan He
2018-11-05 17:10               ` Michal Hocko
2018-11-06  0:22                 ` Baoquan He
2018-11-06  8:28                   ` Michal Hocko
2018-11-06  9:16                     ` Baoquan He
2018-11-06  9:36                       ` Baoquan He
2018-11-06  9:51                       ` Michal Hocko
2018-11-06 10:00                         ` Baoquan He

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