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Message-ID: <b89a9828-d4e-9874-d482-dbb6cbe46@gentwo.de>
Date: Tue, 10 Jan 2023 13:06:37 +0100 (CET)
From: Christoph Lameter <cl@...two.de>
To: Marcelo Tosatti <mtosatti@...hat.com>
cc: atomlin@...mlin.com, frederic@...nel.org, tglx@...utronix.de,
mingo@...nel.org, peterz@...radead.org, pauld@...hat.com,
neelx@...hat.com, oleksandr@...alenko.name,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v13 2/6] mm/vmstat: Use vmstat_dirty to track CPU-specific
vmstat discrepancies
On Thu, 5 Jan 2023, Marcelo Tosatti wrote:
> --- linux-2.6.orig/mm/vmstat.c
> +++ linux-2.6/mm/vmstat.c
> @@ -381,6 +381,7 @@ void __mod_zone_page_state(struct zone *
> x = 0;
> }
> __this_cpu_write(*p, x);
> + vmstat_mark_dirty();
__vmstat_mark_dirty()? See earlier patch
>
> preempt_enable_nested();
> }
> @@ -417,6 +418,7 @@ void __mod_node_page_state(struct pglist
> x = 0;
> }
> __this_cpu_write(*p, x);
> + vmstat_mark_dirty();
Ditto.
>
> preempt_enable_nested();
> }
> @@ -577,6 +579,9 @@ static inline void mod_zone_state(struct
> s8 __percpu *p = pcp->vm_stat_diff + item;
> long o, n, t, z;
>
> + /* cmpxchg and vmstat_mark_dirty should happen on the same CPU */
> + preempt_disable();
If you are disabling preemption then why do we still need cmpxchg?
Same again below.
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