linux-kernel - Re: [PATCH] THP: Use explicit memory barrier

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Message-ID: <20130402003746.GA30444@blaptop>
Date:	Tue, 2 Apr 2013 09:37:46 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Mel Gorman <mgorman@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH] THP: Use explicit memory barrier

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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