Re: [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE"

[Hekuang]

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.