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From: "Wang, Yalin" <Yalin.Wang@sonymobile.com>
To: "'Hillf Danton'" <hillf.zj@alibaba-inc.com>,
	"'linux-kernel'" <linux-kernel@vger.kernel.org>,
	"'linux-mm@kvack.org'" <linux-mm@kvack.org>,
	"'linux-arm-kernel@lists.infradead.org'" 
	<linux-arm-kernel@lists.infradead.org>,
	"'Andrew Morton'" <akpm@linux-foundation.org>
Subject: [PATCH V3] mm:add VM_BUG_ON_PAGE() for page_mapcount()
Date: Mon, 8 Dec 2014 17:59:46 +0800
Message-ID: <35FD53F367049845BC99AC72306C23D103E688B313FA@CNBJMBX05.corpusers.net> (raw)
In-Reply-To: <35FD53F367049845BC99AC72306C23D103E688B313F9@CNBJMBX05.corpusers.net>


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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>
---
 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
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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   ` Wang, Yalin [this message]
2014-12-08 11:54     ` [PATCH V3] mm:add VM_BUG_ON_PAGE() " Kirill A. Shutemov
2014-12-09  3:18     ` Hillf Danton
2015-06-09 16:14     ` Vlastimil Babka

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