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Date:   Thu, 4 Feb 2021 15:01:34 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc:     Nishanth Aravamudan <naravamudan@digitalocean.com>,
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Subject: Re: [PATCH v10 2/5] sched: CGroup tagging interface for core
 scheduling
Message-ID: <YBv+Ps8F2eho77qh@hirez.programming.kicks-ass.net>
References: <20210123011704.1901835-1-joel@joelfernandes.org>
 <20210123011704.1901835-3-joel@joelfernandes.org>
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On Fri, Jan 22, 2021 at 08:17:01PM -0500, Joel Fernandes (Google) wrote:

> +#ifdef CONFIG_SCHED_DEBUG
> +	/* Read the group cookie. */
> +	{
> +		.name = "core_group_cookie",
> +		.flags = CFTYPE_NOT_ON_ROOT,
> +		.read_u64 = cpu_core_group_cookie_read_u64,
> +	},
> +#endif

> +#ifdef CONFIG_SCHED_DEBUG
> +	/* Read the group cookie. */
> +	{
> +		.name = "core_group_cookie",
> +		.flags = CFTYPE_NOT_ON_ROOT,
> +		.read_u64 = cpu_core_group_cookie_read_u64,
> +	},
> +#endif

AFAICT this leaks kernel pointers. IIRC that was a bad thing.