From: Michal Hocko <mhocko@kernel.org>
To: Luigi Semenzato <semenzato@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
rafael@kernel.org, akpm@linux-foundation.org, gpike@google.com
Subject: Re: [PATCH 1/2] Documentation: clarify limitations of hibernation
Date: Mon, 6 Jan 2020 13:53:52 +0100 [thread overview]
Message-ID: <20200106125352.GB9198@dhcp22.suse.cz> (raw)
In-Reply-To: <20191226220205.128664-2-semenzato@google.com>
On Thu 26-12-19 14:02:04, Luigi Semenzato wrote:
[...]
> +Limitations of Hibernation
> +==========================
> +
> +When entering hibernation, the kernel tries to allocate a chunk of memory large
> +enough to contain a copy of all pages in use, to use it for the system
> +snapshot. If the allocation fails, the system cannot hibernate and the
> +operation fails with ENOMEM. This will happen, for instance, when the total
> +amount of anonymous pages (process data) exceeds 1/2 of total RAM.
> +
> +One possible workaround (besides terminating enough processes) is to force
> +excess anonymous pages out to swap before hibernating. This can be achieved
> +with memcgroups, by lowering memory usage limits with ``echo <new limit> >
> +/dev/cgroup/memory/<group>/memory.mem.usage_in_bytes``. However, the latter
> +operation is not guaranteed to succeed.
I am not familiar with the hibernation process much. But what prevents
those allocations to reclaim memory and push out the anonymous memory to
the swap on demand during the hibernation's allocations?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-01-06 12:53 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-26 22:02 [PATCH 0/2] clarify limitations of hibernation Luigi Semenzato
2019-12-26 22:02 ` [PATCH 1/2] Documentation: " Luigi Semenzato
2020-01-06 12:53 ` Michal Hocko [this message]
2020-01-06 19:08 ` Luigi Semenzato
2020-01-08 11:49 ` Michal Hocko
2020-01-24 16:37 ` Luigi Semenzato
2020-01-27 14:16 ` Michal Hocko
2020-01-27 16:13 ` Luigi Semenzato
2020-01-27 16:28 ` Rafael J. Wysocki
2020-01-27 17:21 ` Luigi Semenzato
2020-01-30 20:50 ` Rafael J. Wysocki
2020-01-30 21:10 ` Luigi Semenzato
2020-01-30 21:29 ` Rafael J. Wysocki
2020-01-30 21:36 ` Luigi Semenzato
2020-01-27 16:14 ` Rafael J. Wysocki
2020-01-07 10:04 ` Rafael J. Wysocki
2019-12-26 22:02 ` [PATCH 2/2] pm: add more logging on hibernation failure Luigi Semenzato
2019-12-27 21:34 [PATCH 0/2] clarify limitations of hibernation Luigi Semenzato
2019-12-27 21:34 ` [PATCH 1/2] Documentation: " Luigi Semenzato
2019-12-28 0:23 ` Chris Down
2019-12-28 0:25 ` Chris Down
2020-01-02 19:29 ` Luigi Semenzato
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