Re: [RFC][PATCH 1/4] memcg: fix formem_cgroup_get_reclaim_stat_from_page

[KAMEZAWA Hiroyuki]

On Fri, 09 Jan 2009 08:57:59 +0800
Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:

> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index e2996b8..62e69d8 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -559,6 +559,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
> >  		return NULL;
> >  
> >  	pc = lookup_page_cgroup(page);
> > +	smp_rmb();
> 
> It is better to add a comment to explain this smp_rmb. I think it's recommended
> that every memory barrier has a comment.
> 
Ah, yes. good point.

Maybe text like this
/*
 * Used bit is set without atomic ops but after smp_wmb().
 * For making pc->mem_cgroup visible, insert smp_rmb() here.
 */

?
-Kame

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