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Date:   Mon, 3 Dec 2018 15:49:06 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Roman Gushchin <guroan@gmail.com>
Cc:     Tejun Heo <tj@kernel.org>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-team@fb.com,
        Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v4 4/7] cgroup: cgroup v2 freezer
Message-ID: <20181203144906.GE31795@redhat.com>
References: <20181130234745.6756-1-guro@fb.com>
 <20181130234745.6756-5-guro@fb.com>
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On 11/30, Roman Gushchin wrote:
>
> +void cgroup_enter_frozen(void)
> +{
> +	if (!current->frozen) {
> +		struct cgroup *cgrp;
> +
> +		spin_lock_irq(&css_set_lock);
> +		current->frozen = true;
> +		cgrp = task_dfl_cgroup(current);
> +		cgrp->freezer.nr_frozen_tasks++;
> +		WARN_ON_ONCE(cgrp->freezer.nr_frozen_tasks >
> +			     cgrp->freezer.nr_tasks_to_freeze);
> +		cgroup_update_frozen(cgrp, true);
> +		spin_unlock_irq(&css_set_lock);
> +	}
> +
> +	__set_current_state(TASK_INTERRUPTIBLE);
> +	schedule();
> +	__set_current_state(TASK_RUNNING);

forgot to mention, schedule() always returns in TASK_RUNNING, so the 2nd
__set_current_state() is pointless.

Oleg.