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Subject: kthread, signals and PF_FREEZE (suspend)
From: Christophe Saout <christophe@saout.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
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Date: Mon, 16 Feb 2004 01:18:52 +0100
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Hi,

I was wondering, has kthread been tested with the suspend code?

When trying to freeze the processes the suspend code sets PF_FREEZE on a
process and calls signal_wake_up(p, 0);

That means that signal_pending() will return true for that process which
will make kthread stop the thread.

The workqueues have PF_IOTHREAD set and I'm only seeing those on my
machine that's why it doesn't fail.

But the migration threads for example call signal_pending() directly
after schedule() before checking PF_FREEZE and calling refrigerator()
(which BTW flushes all signals).