linux-kernel - Re: [PATCH 08/10] PM: hibernate: Mix user key in encrypted hibernate

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Message-ID: <20220510122927.GA19328@amd>
Date:   Tue, 10 May 2022 14:29:27 +0200
From:   Pavel Machek <pavel@....cz>
To:     Evan Green <evgreen@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Matthew Garrett <mgarrett@...ora.tech>,
        Daniil Lunev <dlunev@...gle.com>, zohar@...ux.ibm.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        linux-integrity@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        rjw@...ysocki.net, Gwendal Grignou <gwendal@...omium.org>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Len Brown <len.brown@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH 08/10] PM: hibernate: Mix user key in encrypted hibernate

Hi!

> > > One annoyance of the "preloading" scheme is that hibernate image memory
> > > is effectively double-allocated: first by the usermode process pulling
> > > encrypted contents off of disk and holding it, and second by the kernel
> > > in its giant allocation in prepare_image(). An interesting future
> > > optimization would be to allow the kernel to accept and store encrypted
> > > 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 defer
> > > 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...
> >
> 
> 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
								
-- 
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