linux-kernel - Re: [PATCH 0/4] allow freezing of tasks with netfs calls in flight

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Message-ID: <20111011061819.GA1377@ucw.cz>
Date:	Tue, 11 Oct 2011 08:18:19 +0200
From:	Pavel Machek <pavel@....cz>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	trond.myklebust@...app.com, smfrench@...il.com, rjw@...k.pl,
	linux-pm@...ts.linux-foundation.org, linux-cifs@...r.kernel.org,
	linux-nfs@...r.kernel.org, john@...va.COM,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] allow freezing of tasks with netfs calls in flight

Hi!

> We've had a number of reports recently of people with NFS and CIFS
> mounts that were unable to suspend or hibernate their machines. Here
> are a couple of Fedora bugs that illustrate the problem:
> 
>     https://bugzilla.redhat.com/show_bug.cgi?id=712088
>     https://bugzilla.redhat.com/show_bug.cgi?id=717735
> 
> When it occurs the problem is pretty clear. We have a task that's
> sleeping in the kernel in TASK_KILLABLE sleep, generally waiting
> for a reply to come in. Often though, userspace has already taken
> down the interface so that reply will never come. The process then
> fails to freeze and the suspend fails.

Userspace should not take interface down for suspend (*). Why do that?


> This patch fixes this by allowing the TASK_KILLABLE sleeps in NFS and
> CIFS to be awoken by the freezer and then to try to freeze. If a freeze
> event does occur, then the code will treat it as if a schedule() has
> already occured.

Looks like good idea...

(*) unless absolutely neccessary. openvpn?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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