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Date:   Tue, 10 May 2022 14:29:27 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Evan Green <evgreen@chromium.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Matthew Garrett <mgarrett@aurora.tech>,
        Daniil Lunev <dlunev@google.com>, zohar@linux.ibm.com,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        linux-integrity@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        rjw@rjwysocki.net, Gwendal Grignou <gwendal@chromium.org>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Len Brown <len.brown@intel.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH 08/10] PM: hibernate: Mix user key in encrypted hibernate
Message-ID: <20220510122927.GA19328@amd>
References: <20220504232102.469959-1-evgreen@chromium.org>
 <20220504161439.8.I87952411cf83f2199ff7a4cc8c828d357b8c8ce3@changeid>
 <20220506160820.GB1060@bug>
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Hi!

> > > One annoyance of the "preloading" scheme is that hibernate image memo=
ry
> > > is effectively double-allocated: first by the usermode process pulling
> > > encrypted contents off of disk and holding it, and second by the kern=
el
> > > in its giant allocation in prepare_image(). An interesting future
> > > optimization would be to allow the kernel to accept and store encrypt=
ed
> > > page data before the user key is available. This would remove the
> > > double allocation problem, as usermode could push the encrypted pages
> > > loaded from disk immediately without storing them. The kernel could d=
efer
> > > decryption of the data until the user key is available, while still
> > > knowing the correct page locations to store the encrypted data in.
> >
> > Um. Dunno. Won't you run out of memory? Hibernation images can be quite=
 big...
> >
>=20
> As you know, with the way the snapshot mechanism works, a hibernation
> image can be at most 50% of RAM. If the system was using more than

There used to be 50% of RAM limit, but it was removed.

Best regards,
								Pavel
							=09
--=20
People of Russia, stop Putin before his war on Ukraine escalates.

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