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From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "'Wang, Yalin'" <Yalin.Wang@sonymobile.com>,
	"'linux-kernel'" <linux-kernel@vger.kernel.org>,
	<linux-mm@kvack.org>, <linux-arm-kernel@lists.infradead.org>,
	"'Andrew Morton'" <akpm@linux-foundation.org>
Subject: Re: [PATCH V3] mm:add VM_BUG_ON_PAGE() for page_mapcount()
Date: Tue, 09 Dec 2014 11:18:32 +0800
Message-ID: <015701d0135e$d1980980$74c81c80$@alibaba-inc.com> (raw)
In-Reply-To: <35FD53F367049845BC99AC72306C23D103E688B313FA@CNBJMBX05.corpusers.net>

> 
> This patch add VM_BUG_ON_PAGE() for slab page,
> because _mapcount is an union with slab struct in struct page,
> avoid access _mapcount if this page is a slab page.
> Also remove the unneeded bracket.
> 
> Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

>  include/linux/mm.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index b464611..a117527 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -449,7 +449,8 @@ static inline void page_mapcount_reset(struct page *page)
> 
>  static inline int page_mapcount(struct page *page)
>  {
> -	return atomic_read(&(page)->_mapcount) + 1;
> +	VM_BUG_ON_PAGE(PageSlab(page), page);
> +	return atomic_read(&page->_mapcount) + 1;
>  }
> 
>  static inline int page_count(struct page *page)
> --
> 2.1.3


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-08  9:33 [PATCH] mm:add VM_BUG_ON() " Hillf Danton
2014-12-08  9:51 ` Wang, Yalin
2014-12-08  9:58 ` [PATCH V2] " Wang, Yalin
2014-12-08  9:59   ` [PATCH V3] mm:add VM_BUG_ON_PAGE() " Wang, Yalin
2014-12-08 11:54     ` Kirill A. Shutemov
2014-12-09  3:18     ` Hillf Danton [this message]
2015-06-09 16:14     ` Vlastimil Babka

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