linux-kernel - Re: [RFC][PATCH -mm] Freezer: Handle uninterruptible tasks

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Message-Id: <200707070100.17413.rjw@sisk.pl>
Date:	Sat, 7 Jul 2007 01:00:16 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Oleg Nesterov <oleg@...sign.ru>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH -mm] Freezer: Handle uninterruptible tasks

On Saturday, 7 July 2007 00:38, Oliver Neukum wrote:
> Am Freitag, 6. Juli 2007 schrieb Oleg Nesterov:
> > Rafael J. Wysocki wrote:
> > >
> > > This patch makes the freezer skip uninterruptible user space tasks (ie. such
> > > that have an mm of their own) when counting the tasks to be frozen.  As a
> > > result, these tasks have the TIF_FREEZE and TIF_SIGPENDING flags set, but the
> > > freezer doesn't wait for them to enter the refrigerator.  Nevertheless, they
> > > will enter the refrigerator as soon as they change their state.
> > 
> > A small correction: they will enter the refrigerator on return to user-space.
> 
> That is too late. We would need them to go to sleep as soon as they are
> woken up. This does not matter if they are in uninterruptible sleep due to
> fuse deadlocking, as they won't be woken up, but it kills the other cases.

I'm sorry I can't write anything more about that right now, I'll write more
tomorrow.

For now, I can only say that I have reasons to believe that the other cases
are not likely to "leak" through the freezer.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth
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