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Date:   Wed, 4 Jan 2023 13:34:59 +0000
From:   Aaron Tomlin <atomlin@atomlin.com>
To:     Frederic Weisbecker <frederic@kernel.org>
Cc:     Marcelo Tosatti <mtosatti@redhat.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: <20230104133459.5yaflf3yicpmhbbh@ava.usersys.com>
References: <20221227121137.102497574@redhat.com>
 <20221227121341.981235373@redhat.com>
 <20221230132132.GA186035@lothringen>
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On Fri 2022-12-30 14:21 +0100, Frederic Weisbecker wrote:
> 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.

Hi Frederic,

Agreed.


Kind regards,

-- 
Aaron Tomlin