linux-kernel - Re: [PATCH V6] perf: Reset the dirty counter to prevent the leak for an RDPMC task

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Date:   Wed, 12 May 2021 09:35:55 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Rob Herring <robh@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andy Lutomirski <luto@...capital.net>,
        Stephane Eranian <eranian@...gle.com>,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH V6] perf: Reset the dirty counter to prevent the leak for
 an RDPMC task

On Tue, May 11, 2021 at 05:42:54PM -0400, Liang, Kan wrote:
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 1574b70..8216acc 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -3851,7 +3851,7 @@ static void perf_event_context_sched_in(struct
> perf_event_context *ctx,
>  		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
>  	perf_event_sched_in(cpuctx, ctx, task);
> 
> -	if (cpuctx->sched_cb_usage && pmu->sched_task)
> +	if (pmu->sched_task && (cpuctx->sched_cb_usage ||
> atomic_read(&pmu->sched_cb_usages)))
>  		pmu->sched_task(cpuctx->task_ctx, true);

Aside from the obvious whitespace issues; I think this should work.