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From:   Thomas Gleixner <tglx@linutronix.de>
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To:     Marcelo Tosatti <mtosatti@redhat.com>, linux-kernel@vger.kernel.org
Cc:     Nitesh Lal <nilal@redhat.com>,
        Nicolas Saenz Julienne <nsaenzju@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alex Belits <abelits@belits.com>, Peter Xu <peterx@redhat.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Oscar Shiang <oscar0225@livemail.tw>,
        Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [patch v12 07/13] task isolation: sync vmstats conditional on
 changes
In-Reply-To: <20220315153314.042469218@fedora.localdomain>
References: <20220315153132.717153751@fedora.localdomain>
 <20220315153314.042469218@fedora.localdomain>
Date:   Wed, 27 Apr 2022 10:03:58 +0200
Message-ID: <87tuafx89d.ffs@tglx>
MIME-Version: 1.0
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List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Mar 15 2022 at 12:31, Marcelo Tosatti wrote:
>  
> +#ifdef CONFIG_TASK_ISOLATION
> +struct static_key vmstat_sync_enabled;

jump_label.h:

"The use of 'struct static_key' directly, is now DEPRECATED."

> +DEFINE_PER_CPU_ALIGNED(bool, vmstat_dirty);
> +
> +static inline void mark_vmstat_dirty(void)
> +{
> +	if (!static_key_false(&vmstat_sync_enabled))
> +		return;
> +
> +	raw_cpu_write(vmstat_dirty, true);

What's the justification for raw_cpu_write()?

>  
> @@ -1512,6 +1543,7 @@ static void pagetypeinfo_showfree_print(
>  		}
>  		seq_putc(m, '\n');
>  	}
> +	mark_vmstat_dirty();

Why does a function which just dumps information via /proc/pagetypeinfo
make vmstats dirty?

Thanks,

        tglx