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From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: David Hildenbrand <dhildenb@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Roman Gushchin <guro@fb.com>,
	Bharata B Rao <bharata@linux.ibm.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Kernel Team <Kernel-team@fb.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	stable <stable@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Sasha Levin <sashal@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v2 00/28] The new cgroup slab memory controller
Date: Wed, 2 Sep 2020 08:42:13 -0400	[thread overview]
Message-ID: <CA+CK2bAebg4PALh3_-49MXGJ-FNP3hE98wHZd5uEC-q7wG6Vmg@mail.gmail.com> (raw)
In-Reply-To: <A8A8D5FE-86C3-40B4-919C-5FF2A134F366@redhat.com>

> > Am 02.09.2020 um 11:53 schrieb Vlastimil Babka <vbabka@suse.cz>:
> >
> > On 8/28/20 6:47 PM, Pavel Tatashin wrote:
> >> There appears to be another problem that is related to the
> >> cgroup_mutex -> mem_hotplug_lock deadlock described above.
> >>
> >> In the original deadlock that I described, the workaround is to
> >> replace crash dump from piping to Linux traditional save to files
> >> method. However, after trying this workaround, I still observed
> >> hardware watchdog resets during machine  shutdown.
> >>
> >> The new problem occurs for the following reason: upon shutdown systemd
> >> calls a service that hot-removes memory, and if hot-removing fails for
> >
> > Why is that hotremove even needed if we're shutting down? Are there any
> > (virtualization?) platforms where it makes some difference over plain
> > shutdown/restart?
>
> If all it‘s doing is offlining random memory that sounds unnecessary and dangerous. Any pointers to this service so we can figure out what it‘s doing and why? (Arch? Hypervisor?)

Hi David,

This is how we are using it at Microsoft: there is  a very large
number of small memory machines (8G each) with low downtime
requirements (reboot must be under a second). There is also a large
state ~2G of memory that we need to transfer during reboot, otherwise
it is very expensive to recreate the state. We have 2G of system
memory memory reserved as a pmem in the device tree, and use it to
pass information across reboots. Once the information is not needed we
hot-add that memory and use it during runtime, before shutdown we
hot-remove the 2G, save the program state on it, and do the reboot.

Pasha

  reply	other threads:[~2020-09-02 12:43 UTC|newest]

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 17:34 [PATCH v2 00/28] The new cgroup slab memory controller Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 01/28] mm: kmem: cleanup (__)memcg_kmem_charge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 02/28] mm: kmem: cleanup memcg_kmem_uncharge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 03/28] mm: kmem: rename memcg_kmem_(un)charge() into memcg_kmem_(un)charge_page() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 04/28] mm: kmem: switch to nr_pages in (__)memcg_kmem_charge_memcg() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 05/28] mm: memcg/slab: cache page number in memcg_(un)charge_slab() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 06/28] mm: kmem: rename (__)memcg_kmem_(un)charge_memcg() to __memcg_kmem_(un)charge() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 07/28] mm: memcg/slab: introduce mem_cgroup_from_obj() Roman Gushchin
2020-02-03 16:05   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 08/28] mm: fork: fix kernel_stack memcg stats for various stack implementations Roman Gushchin
2020-02-03 16:12   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 09/28] mm: memcg/slab: rename __mod_lruvec_slab_state() into __mod_lruvec_obj_state() Roman Gushchin
2020-02-03 16:13   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 10/28] mm: memcg: introduce mod_lruvec_memcg_state() Roman Gushchin
2020-02-03 17:39   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 11/28] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-02-03 17:44   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 12/28] mm: vmstat: use s32 for vm_node_stat_diff in struct per_cpu_nodestat Roman Gushchin
2020-02-03 17:58   ` Johannes Weiner
2020-02-03 18:25     ` Roman Gushchin
2020-02-03 20:34       ` Johannes Weiner
2020-02-03 22:28         ` Roman Gushchin
2020-02-03 22:39           ` Johannes Weiner
2020-02-04  1:44             ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 13/28] mm: vmstat: convert slab vmstat counter to bytes Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 14/28] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 15/28] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-02-03 19:31   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 16/28] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-02-03 18:27   ` Johannes Weiner
2020-02-03 18:34     ` Roman Gushchin
2020-02-03 20:46       ` Johannes Weiner
2020-02-03 21:19         ` Roman Gushchin
2020-02-03 22:29           ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 17/28] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-02-03 19:53   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 18/28] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 19/28] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 20/28] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 21/28] mm: memcg/slab: use a single set of kmem_caches for all memory cgroups Roman Gushchin
2020-02-03 19:50   ` Johannes Weiner
2020-02-03 20:58     ` Roman Gushchin
2020-02-03 22:17       ` Johannes Weiner
2020-02-03 22:38         ` Roman Gushchin
2020-02-04  1:15         ` Roman Gushchin
2020-02-04  2:47           ` Johannes Weiner
2020-02-04  4:35             ` Roman Gushchin
2020-02-04 18:41               ` Johannes Weiner
2020-02-05 15:58                 ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 22/28] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 23/28] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 24/28] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 25/28] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 26/28] tools/cgroup: add slabinfo.py tool Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 27/28] tools/cgroup: make slabinfo.py compatible with new slab controller Roman Gushchin
2020-01-30  2:17   ` Bharata B Rao
2020-01-30  2:44     ` Roman Gushchin
2020-01-31 22:24     ` Roman Gushchin
2020-02-12  5:21       ` Bharata B Rao
2020-02-12 20:42         ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 28/28] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-01-30  2:06 ` [PATCH v2 00/28] The new cgroup slab memory controller Bharata B Rao
2020-01-30  2:41   ` Roman Gushchin
2020-08-12 23:16     ` Pavel Tatashin
2020-08-12 23:16       ` Pavel Tatashin
2020-08-12 23:18       ` Pavel Tatashin
2020-08-12 23:18         ` Pavel Tatashin
2020-08-13  0:04       ` Roman Gushchin
2020-08-13  0:31         ` Pavel Tatashin
2020-08-13  0:31           ` Pavel Tatashin
2020-08-28 16:47           ` Pavel Tatashin
2020-08-28 16:47             ` Pavel Tatashin
2020-09-01  5:28             ` Bharata B Rao
2020-09-01 12:52               ` Pavel Tatashin
2020-09-01 12:52                 ` Pavel Tatashin
2020-09-02  6:23                 ` Bharata B Rao
2020-09-02 12:34                   ` Pavel Tatashin
2020-09-02 12:34                     ` Pavel Tatashin
2020-09-02  9:53             ` Vlastimil Babka
2020-09-02 10:39               ` David Hildenbrand
2020-09-02 12:42                 ` Pavel Tatashin [this message]
2020-09-02 12:42                   ` Pavel Tatashin
2020-09-02 13:50                   ` Michal Hocko
2020-09-02 14:20                     ` Pavel Tatashin
2020-09-02 14:20                       ` Pavel Tatashin
2020-09-03 18:09                       ` David Hildenbrand
2020-09-02 11:26               ` Michal Hocko
2020-09-02 12:51                 ` Pavel Tatashin
2020-09-02 12:51                   ` Pavel Tatashin
2020-09-02 13:51                   ` Michal Hocko
2020-09-02 11:32               ` Michal Hocko
2020-09-02 12:53                 ` Pavel Tatashin
2020-09-02 12:53                   ` Pavel Tatashin
2020-09-02 13:52                   ` Michal Hocko

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