Re: [PATCH] THP: Use explicit memory barrier

[Kamezawa Hiroyuki]

(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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