Re: [PATCH] THP: Use explicit memory barrier

From: Minchan Kim
Date: Mon Apr 01 2013 - 20:38:08 EST


On Mon, Apr 01, 2013 at 04:35:38PM -0700, David Rientjes wrote:
> On Mon, 1 Apr 2013, Minchan Kim wrote:
>
> > __do_huge_pmd_anonymous_page depends on page_add_new_anon_rmap's
> > spinlock for making sure that clear_huge_page write become visible
> > after set set_pmd_at() write.
> >
> > But lru_cache_add_lru uses pagevec so it could miss spinlock
> > easily so above rule was broken so user may see inconsistent data.
> >
> > This patch fixes it with using explict barrier rather than depending
> > on lru spinlock.
> >
>
> Is this the same issue that Andrea responded to in the "thp and memory
> barrier assumptions" thread at http://marc.info/?t=134333512700004 ?

Yes and Peter pointed out further step.
Thanks for pointing out.
Not that I know that Andrea alreay noticed it, I don't care about this
patch.

Remaining question is Kame's one.
Isn't there anyone could answer it?

>
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--
Kind regards,
Minchan Kim
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