From: Michal Hocko <mhocko@kernel.org>
To: Baoquan He <bhe@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, aarcange@redhat.com, david@redhat.com,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: Memory hotplug softlock issue
Date: Wed, 14 Nov 2018 11:00:58 +0100 [thread overview]
Message-ID: <20181114100058.GK23419@dhcp22.suse.cz> (raw)
In-Reply-To: <20181114070909.GB2653@MiWiFi-R3L-srv>
[Cc Vladimir]
On Wed 14-11-18 15:09:09, Baoquan He wrote:
> Hi,
>
> Tested memory hotplug on a bare metal system, hot removing always
> trigger a lock. Usually need hot plug/unplug several times, then the hot
> removing will hang there at the last block. Surely with memory pressure
> added by executing "stress -m 200".
>
> Will attach the log partly. Any idea or suggestion, appreciated.
>
[...]
> [ +0.007169] Not tainted 4.20.0-rc2+ #4
> [ +0.004630] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ +0.008001] kworker/181:1 D 0 1187 2 0x80000000
> [ +0.005711] Workqueue: memcg_kmem_cache memcg_kmem_cache_create_func
> [ +0.006467] Call Trace:
> [ +0.002591] ? __schedule+0x24e/0x880
> [ +0.004995] schedule+0x28/0x80
> [ +0.003380] rwsem_down_read_failed+0x103/0x190
> [ +0.006528] call_rwsem_down_read_failed+0x14/0x30
> [ +0.004937] __percpu_down_read+0x4f/0x80
> [ +0.004204] get_online_mems+0x2d/0x30
> [ +0.003871] memcg_create_kmem_cache+0x1b/0x120
> [ +0.004740] memcg_kmem_cache_create_func+0x1b/0x60
> [ +0.004986] process_one_work+0x1a1/0x3a0
> [ +0.004255] worker_thread+0x30/0x380
> [ +0.003764] ? drain_workqueue+0x120/0x120
> [ +0.004238] kthread+0x112/0x130
> [ +0.003320] ? kthread_park+0x80/0x80
> [ +0.003796] ret_from_fork+0x35/0x40
For a quick context. We do hold the exclusive mem hotplug lock
throughout the whole offlining and that can take quite some time.
So I am wondering whether we absolutely have to take the shared lock
in this path (introduced by 03afc0e25f7f ("slab: get_online_mems for
kmem_cache_{create,destroy,shrink}")). Is there any way to relax this
requirement? E.g. nodes stay around even when they are completely
offline. Does that help?
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2018-11-14 10:01 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 7:09 Memory hotplug softlock issue Baoquan He
2018-11-14 7:16 ` Baoquan He
2018-11-14 8:18 ` David Hildenbrand
2018-11-14 9:00 ` Baoquan He
2018-11-14 9:25 ` David Hildenbrand
2018-11-14 9:41 ` Michal Hocko
2018-11-14 9:48 ` David Hildenbrand
2018-11-14 10:04 ` Michal Hocko
2018-11-14 9:01 ` Michal Hocko
2018-11-14 9:22 ` David Hildenbrand
2018-11-14 9:37 ` Michal Hocko
2018-11-14 9:39 ` David Hildenbrand
2018-11-14 14:52 ` Baoquan He
2018-11-14 15:00 ` Michal Hocko
2018-11-15 5:10 ` Baoquan He
2018-11-15 7:30 ` Michal Hocko
2018-11-15 7:53 ` Baoquan He
2018-11-15 8:30 ` Michal Hocko
2018-11-15 9:42 ` David Hildenbrand
2018-11-15 9:52 ` Baoquan He
2018-11-15 9:53 ` David Hildenbrand
2018-11-15 13:12 ` Baoquan He
2018-11-15 13:19 ` Michal Hocko
2018-11-15 13:23 ` Baoquan He
2018-11-15 14:25 ` Michal Hocko
2018-11-15 13:38 ` Baoquan He
2018-11-15 14:32 ` Michal Hocko
2018-11-15 14:34 ` Baoquan He
2018-11-16 1:24 ` Baoquan He
2018-11-16 9:14 ` Michal Hocko
2018-11-17 4:22 ` Baoquan He
[not found] ` <20181119105202.GE18471@MiWiFi-R3L-srv>
2018-11-19 12:40 ` Michal Hocko
2018-11-19 12:51 ` Michal Hocko
2018-11-19 14:10 ` Michal Hocko
2018-11-19 16:36 ` Vlastimil Babka
2018-11-19 16:46 ` Michal Hocko
2018-11-19 16:46 ` Vlastimil Babka
2018-11-19 16:48 ` Vlastimil Babka
2018-11-19 17:01 ` Michal Hocko
2018-11-19 17:33 ` Michal Hocko
2018-11-19 20:34 ` Hugh Dickins
2018-11-19 20:59 ` Michal Hocko
2018-11-20 1:56 ` Baoquan He
2018-11-20 5:44 ` Hugh Dickins
2018-11-20 13:38 ` Vlastimil Babka
2018-11-20 13:58 ` Baoquan He
2018-11-20 14:05 ` Michal Hocko
2018-11-20 14:12 ` Baoquan He
2018-11-21 1:21 ` Hugh Dickins
2018-11-21 1:08 ` Hugh Dickins
2018-11-21 3:20 ` Hugh Dickins
2018-11-21 17:31 ` Michal Hocko
2018-11-22 1:53 ` Hugh Dickins
2018-11-14 10:00 ` Michal Hocko [this message]
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