linux-kernel - Re: [PATCH] mm: don't expose page to fast gup before it's ready

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Message-Id: <20190514142527.356cb071155cd1077536f3da@linux-foundation.org>
Date:   Tue, 14 May 2019 14:25:27 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Yu Zhao <yuzhao@...gle.com>
Cc:     Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: don't expose page to fast gup before it's ready

On Tue, 9 Jan 2018 02:10:50 -0800 Yu Zhao <yuzhao@...gle.com> wrote:

> > Also what prevents reordering here? There do not seem to be any barriers
> > to prevent __SetPageSwapBacked leak after set_pte_at with your patch.
> 
> I assumed mem_cgroup_commit_charge() acted as full barrier. Since you
> explicitly asked the question, I realized my assumption doesn't hold
> when memcg is disabled. So we do need something to prevent reordering
> in my patch. And it brings up the question whether we want to add more
> barrier to other places that call page_add_new_anon_rmap() and
> set_pte_at().

Is a new version of this patch planned?