linux-kernel - Suspend to RAM

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Message-ID: <50F96746.1080304@mrkva.eu>
Date:	Fri, 18 Jan 2013 16:16:22 +0100
From:	Radek Pilar <mrkva@...va.eu>
To:	linux-kernel@...r.kernel.org
Subject: Suspend to RAM - freeze & sync

Hello,
I'm trying to implement feature that removes cryptsetup keys from RAM on
suspend to RAM: mounts ramfs, unpacks initramfs to ramfs, moves /proc
/dev and /sys to ramfs, chroots, calls luksSuspend, suspends system
using /sys/power/state, after resume calls luksResume and cleans up.
However, there is a small issue I wasn't able to solve: after calling
luksSuspend, all attempts to access suspended device blocks - so most
likely some processes won't be able to freeze. The same issue will be
with sync just before suspend - if there are some data to be written,
sync() blocks. If I comment out freeze and sync from the suspend code,
it suspends (and wakes up) just fine - however, that patch will never be
accepted.
Is there any *correct* way to do this? (Skip freeze/sync on demand)?
Thanks
Radek Pilar

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