linux-kernel - Re: Getting rid of freezer for suspend [was Re: [fuse-devel] [PATCH] fuse: make fuse daemon frozen along with kernel threads]

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Message-ID: <CAJfpeguV5X1pwb-E7vzVtK4n0Q6Mu6A4XKnS5-tWn4Q7MtzgZg@mail.gmail.com>
Date:	Thu, 14 Feb 2013 14:09:50 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Pavel Machek <pavel@....cz>,
	Goswin von Brederlow <goswin-v-b@....de>,
	Li Fei <fei.li@...el.com>, len.brown@...el.com,
	mingo@...hat.com, peterz@...radead.org, biao.wang@...el.com,
	linux-pm@...r.kernel.org, fuse-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, chuansheng.liu@...el.com
Subject: Re: Getting rid of freezer for suspend [was Re: [fuse-devel] [PATCH]
 fuse: make fuse daemon frozen along with kernel threads]

On Thu, Feb 14, 2013 at 1:11 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Thursday, February 14, 2013 11:41:16 AM Miklos Szeredi wrote:

>>
>> It is essentially the same mechanism that is used to delay the
>> freezing of kernel threads after userspace tasks have been frozen.
>> Except it's a lot more difficult to determine which userspace tasks
>> need to be suspended late and which aren't.
>
> Well, I suppose that information is available to user space.
>
> Do we need an interface for a process to mark itself as PF_FREEZE_LATE or
> do we need an interface for one process to mark another process as
> PF_FREEZE_LATE, or both?

As a first step marking self with PF_FREEZE_LATE and inheriting this
flag across fork/clone would work for most cases, I think.

Marking an unrelated process would have all sorts of issues: Who has
permission to do this?  Won't it be misused to "fix" random freezer
issues.

Thanks,
Miklos
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