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Subject: Re: [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with
 ACCESS_ONCE"
To: Mel Gorman <mgorman@techsingularity.net>
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 <20160330103839.GA4773@techsingularity.net>
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From: Hekuang <hekuang@huawei.com>
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Date: Wed, 30 Mar 2016 18:51:12 +0800
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hi

在 2016/3/30 18:38, Mel Gorman 写道:
> On Wed, Mar 30, 2016 at 10:22:07AM +0000, He Kuang wrote:
>> This reverts commit 998d39cb236fe464af86a3492a24d2f67ee1efc2.
>>
>> When local irq is disabled, a percpu variable does not change, so we can
>> remove the access macros and let the compiler optimize the code safely.
>>
> batch can be changed from other contexts. Why is this safe?
>
I've mistakenly thought that per_cpu variable can only be accessed by 
that cpu.
Thanks.