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Date:   Fri, 30 Dec 2022 14:21:32 +0100
From:   Frederic Weisbecker <frederic@kernel.org>
To:     Marcelo Tosatti <mtosatti@redhat.com>
Cc:     atomlin@atomlin.com, cl@linux.com, tglx@linutronix.de,
        mingo@kernel.org, peterz@infradead.org, pauld@redhat.com,
        neelx@redhat.com, oleksandr@natalenko.name,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v12 2/6] mm/vmstat: Use vmstat_dirty to track
 CPU-specific vmstat discrepancies
Message-ID: <20221230132132.GA186035@lothringen>
References: <20221227121137.102497574@redhat.com>
 <20221227121341.981235373@redhat.com>
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On Tue, Dec 27, 2022 at 09:11:39AM -0300, Marcelo Tosatti wrote:
> @@ -606,6 +608,7 @@ static inline void mod_zone_state(struct
>  
>  	if (z)
>  		zone_page_state_add(z, zone, item);
> +	vmstat_mark_dirty();
>  }
>  
>  void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
> @@ -674,6 +677,7 @@ static inline void mod_node_state(struct
>  
>  	if (z)
>  		node_page_state_add(z, pgdat, item);
> +	vmstat_mark_dirty();

Looking at this further, about the two above chunks, there is a risk to
mark the wrong CPU dirty because those functions are preemptible and rely
on this_cpu_cmpxchg() to deal with preemption.

Thanks.