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Date: Tue, 09 Sep 2014 22:48:29 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Tejun Heo <tj@...nel.org>
Cc: Michal Hocko <mhocko@...e.cz>,
Cong Wang <xiyou.wangcong@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
David Rientjes <rientjes@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [Patch v4 1/2] freezer: check OOM kill while being frozen
On Wednesday, September 10, 2014 12:23:36 AM Tejun Heo wrote:
> On Tue, Sep 09, 2014 at 05:16:55PM +0200, Michal Hocko wrote:
> > But OOM killer doesn't kill kernel threads as they do not own any
> > memory. So the check should be safe, no?
>
> Even for userland tasks, try_to_freeze() can currently be anywhere in
> the kernel. The frequently used ones are few but there are some odd
> ones out, and, again, there's nothing enforcing any structure on
> try_to_freeze() usage. The other thing is that we may do quite a bit
> during exiting including allocating memory. Are those safe for system
> PM? Rafael, what exactly are the rules for PM? What shouldn't
> change?
We can't make any assumptions regarding the availability of any devices.
That is, whatever can end up in device access may potentially fail.
Rafael
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