From: Peter Zijlstra <peterz@infradead.org>
To: Chen Ridong <chenridong@huaweicloud.com>
Cc: timvp@google.com, Michal Koutn?? <mkoutny@suse.com>,
rafael@kernel.org, pavel@kernel.org, tj@kernel.org,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
lujialin4@huawei.com, chenridong@huawei.com
Subject: Re: [PATCH next] sched,freezer: prevent tasks from escaping being frozen
Date: Tue, 8 Jul 2025 09:28:52 +0200 [thread overview]
Message-ID: <20250708072852.GD1613376@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <c63a1698-2d93-4105-8641-ecec69b48523@huaweicloud.com>
On Mon, Jul 07, 2025 at 07:32:59PM +0800, Chen Ridong wrote:
> Below is the race condition scenario:
>
> get_signal read freezer.state
> try_to_freeze
> __refrigerator freezer_read
> update_if_frozen
> WRITE_ONCE(current->__state, TASK_FROZEN);
> // The task is set to frozen(now, frozen(task) == ture).
> // we suppose other tasks are all frozen.
> // set cgroup frozen when all tasks are frozen
> freezer->state |= CGROUP_FROZEN;
Ooh, yes, now I see. Somehow I kept missing update_if_frozen().
Sometimes reading is hard :-) Thanks!
> // freezing(current) will return false,
> // since cgroup is frozen(not freezing)
> break out
> __set_current_state(TASK_RUNNING);
> //bug: the task is set to running, but it should be frozen.
next prev parent reply other threads:[~2025-07-08 7:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-03 13:34 [PATCH next] sched,freezer: prevent tasks from escaping being frozen Chen Ridong
2025-07-03 17:01 ` Michal Koutný
2025-07-04 3:02 ` Chen Ridong
2025-07-04 3:11 ` Chen Ridong
2025-07-04 7:57 ` Peter Zijlstra
2025-07-04 10:25 ` Chen Ridong
2025-07-07 4:02 ` Chen Ridong
2025-07-07 10:10 ` Peter Zijlstra
2025-07-07 11:32 ` Chen Ridong
2025-07-08 7:28 ` Peter Zijlstra [this message]
2025-07-08 15:35 ` Tim Van Patten
2025-07-10 15:44 ` Michal Koutný
2025-07-11 0:51 ` Chen Ridong
2025-07-07 16:38 ` Michal Koutný
2025-07-08 1:38 ` Chen Ridong
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