From: Luigi Semenzato <semenzato@google.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Geoff Pike <gpike@google.com>
Subject: Re: [PATCH 1/2] Documentation: clarify limitations of hibernation
Date: Mon, 27 Jan 2020 09:21:25 -0800 [thread overview]
Message-ID: <CAA25o9RHKerPJNW6h5d6W48q1qA3wYJAmhOBU3XiBHwMcEChhA@mail.gmail.com> (raw)
In-Reply-To: <CAJZ5v0iDtk+WWHV8F2C+9EdeMSx_JKYDEiarProoE55kiBOjkg@mail.gmail.com>
On Mon, Jan 27, 2020 at 8:28 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Mon, Jan 27, 2020 at 5:13 PM Luigi Semenzato <semenzato@google.com> wrote:
> >
> > On Mon, Jan 27, 2020 at 6:16 AM Michal Hocko <mhocko@kernel.org> wrote:
> > >
> > > On Fri 24-01-20 08:37:12, Luigi Semenzato wrote:
> > > [...]
> > > > The purpose of my documentation patch was to make it clearer that
> > > > hibernation may fail in situations in which suspend-to-RAM works; for
> > > > instance, when there is no swap, and anonymous pages are over 50% of
> > > > total RAM. I will send a new version of the patch which hopefully
> > > > makes this clearer.
> > >
> > > I was under impression that s2disk is pretty much impossible without any
> > > swap.
> >
> > I am not sure what you mean by "swap" here. S2disk needs a swap
> > partition for storing the image, but that partition is not used for
> > regular swap.
>
> That's not correct.
>
> The swap partition (or file) used by s2disk needs to be made active
> before it can use it and the mm subsystem is also able to use it for
> regular swap then.
OK---I had this wrong, thanks.
> > If there is no swap, but more than 50% of RAM is free
> > or reclaimable, s2disk works fine. If anonymous is more than 50%,
> > hibernation can still work, but swap needs to be set up (in addition
> > to the space for the hibernation image). The setup is not obvious and
> > I don't think that the documentation is clear on this.
>
> Well, the entire contents of RAM must be preserved, this way or
> another, during hibernation. That should be totally obvious to anyone
> using it really.
Yes, that's obvious.
> Some of the RAM contents is copies of data already there in the
> filesystems on persistent storage and that does not need to be saved
> again. Everything else must be saved and s2disk (and Linux
> hibernation in general) uses active swap space to save these things.
> This implies that in order to hibernate the system, you generally need
> the amount of swap space equal to the size of RAM minus the size of
> files mapped into memory.
>
> So, to be on the safe side, the total amount of swap space to be used
> for hibernation needs to match the size of RAM (even though
> realistically it may be smaller than that in the majority of cases).
This all makes sense, but we do this:
-- add resume=/dev/sdc to the command line
-- attach a disk (/dev/sdc) with size equal to RAM
-- mkswap /dev/sdc
-- swapon /dev/sdc
-- echo disk > /sys/power/state
and the last operation fails with ENOMEM. Are we doing something
wrong? Are we hitting some other mm bug?
Thanks!
next prev parent reply other threads:[~2020-01-27 17:21 UTC|newest]
Thread overview: 17+ 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAA25o9RHKerPJNW6h5d6W48q1qA3wYJAmhOBU3XiBHwMcEChhA@mail.gmail.com \
--to=semenzato@google.com \
--cc=akpm@linux-foundation.org \
--cc=gpike@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=rafael@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).