Date: Wed, 2 Mar 2016 21:37:48 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Gilad Ben Yossef <giladb@ezchip.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andy Lutomirski <luto@amacapital.net>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v10 07/12] task_isolation: add debug boot flag
Message-ID: <20160302203748.GH6356@twins.programming.kicks-ass.net>
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On Wed, Mar 02, 2016 at 03:09:31PM -0500, Chris Metcalf wrote:
> +void task_isolation_debug(int cpu)
> +{
> +	struct task_struct *p;
> +
> +	if (!task_isolation_possible(cpu))
> +		return;
> +
> +	rcu_read_lock();
> +	p = cpu_curr(cpu);
> +	get_task_struct(p);

As I think Oleg keeps reminding me, this is not actually a safe thing to
do.

> +	rcu_read_unlock();
> +	task_isolation_debug_task(cpu, p);
> +	put_task_struct(p);
> +}