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From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Mel Gorman <mgorman@suse.de>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH] THP: Use explicit memory barrier
Date: Mon, 01 Apr 2013 10:01:49 +0900	[thread overview]
Message-ID: <5158DC7D.2040607@jp.fujitsu.com> (raw)
In-Reply-To: <1364773535-26264-1-git-send-email-minchan@kernel.org>

(2013/04/01 8:45), 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.
> 

Hmm...how about do_anonymous_page() ? there are no comments/locks/barriers.
Users can see non-zero value after page fault in theory ?

Thanks,
-Kame

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  reply	other threads:[~2013-04-01  1:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-31 23:45 [PATCH] THP: Use explicit memory barrier Minchan Kim
2013-04-01  1:01 ` Kamezawa Hiroyuki [this message]
2013-04-01  4:45   ` Minchan Kim
2013-04-01 23:35 ` David Rientjes
2013-04-02  0:37   ` Minchan Kim
2013-04-02 19:20     ` David Rientjes
2013-04-02 19:30     ` Hugh Dickins
2013-04-03  0:14       ` Minchan Kim
2013-04-04 13:45         ` Andrea Arcangeli
2013-04-04  2:45 ` Simon Jeons

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