linux-kernel - Re: [RFC PATCH] PM, freezer: Don't thaw when it's intended frozen processes

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Date:	Mon, 11 May 2015 16:47:14 +0900
From:	Kyungmin Park <kmpark@...radead.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"\\Rafael J. Wysocki\\" <rjw@...ysocki.net>,
	David Rientjes <rientjes@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Cong Wang <xiyou.wangcong@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [RFC PATCH] PM, freezer: Don't thaw when it's intended frozen processes

On Mon, May 11, 2015 at 1:28 PM, Kyungmin Park <kmpark@...radead.org> wrote:
> On Sat, May 9, 2015 at 12:25 AM, Tejun Heo <tj@...nel.org> wrote:
>> Hello, Kyungmin.
>>
>> On Fri, May 08, 2015 at 09:04:26AM +0900, Kyungmin Park wrote:
>>> > I need to think more about it but as an *optimization* we can add
>>> > freezing() test before actually waking tasks up during resume, but can
>>> > you please clarify what you're seeing?
>>>
>>> The mobile application has life cycle and one of them is 'suspend'
>>> state. it's different from 'pause' or 'background'.
>>> if there are some application and enter go 'suspend' state. all
>>> behaviors are stopped and can't do anything. right it's suspended. but
>>> after system suspend & resume, these application is thawed and
>>> running. even though system know it's suspended.
>>>
>>> We made some test application, print out some message within infinite
>>> loop. when it goes 'suspend' state. nothing is print out. but after
>>> system suspend & resume, it prints out again. that's not desired
>>> behavior. and want to address it.
>>>
>>> frozen user processes should be remained as frozen while system
>>> suspend & resume.
>>
>> Yes, they should and I'm not sure why what you're saying is happening
>> because freezing() test done from the frozen tasks themselves should
>> keep them in the freezer.  Which kernel version did you test?  Can you
>> please verify it against a recent kernel?
>
> The kernel 3.10 is not working as expected, but right the latest
> kernel is working correctly.

Please ignore it. test is wrong and it's not working, see Krzysztof Mail.

>
> I see I'll check what's different and which are modified.
>
> Thank you,
> Kyungmin Park
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