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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150512144032.GN11388@htj.duckdns.org>
Date:	Tue, 12 May 2015 10:40:32 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Kyungmin Park <kmpark@...radead.org>,
	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 03:33:10PM +0900, Krzysztof Kozlowski wrote:
> > 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?
> 
> I tested it on v4.1-rc3 and next-20150508.
> 
> Task was moved to frozen cgroup:
> -----
> root@...alhost:/sys/fs/cgroup/freezer/frozen# grep . *
> cgroup.clone_children:0
> cgroup.procs:2750
> freezer.parent_freezing:0
> freezer.self_freezing:1
> freezer.state:FROZEN
> notify_on_release:0
> tasks:2750
> tasks:2773
> -----
> 
> Unfortunately during system resume the process was woken up. The "if
> (frozen(p))" check was true. Is it expected behaviour?

It isn't optimal but doesn't break anything either.  Whether a task
stays in the freezer or not is solely decided by freezing() test by
the task itself.  Being woken up spuriously doesn't break anything.

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/