From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755082AbaLHJ75 (ORCPT ); Mon, 8 Dec 2014 04:59:57 -0500 Received: from cnbjrel02.sonyericsson.com ([219.141.167.166]:4123 "EHLO cnbjrel02.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755063AbaLHJ7z (ORCPT ); Mon, 8 Dec 2014 04:59:55 -0500 From: "Wang, Yalin" To: "'Hillf Danton'" , "'linux-kernel'" , "'linux-mm@kvack.org'" , "'linux-arm-kernel@lists.infradead.org'" , "'Andrew Morton'" Date: Mon, 8 Dec 2014 17:59:46 +0800 Subject: [PATCH V3] mm:add VM_BUG_ON_PAGE() for page_mapcount() Thread-Topic: [PATCH V3] mm:add VM_BUG_ON_PAGE() for page_mapcount() Thread-Index: AdASyaRYNK5Lt1HlQ1KFwSk6V3BFwAAA8BmwAAAOZuA= Message-ID: <35FD53F367049845BC99AC72306C23D103E688B313FA@CNBJMBX05.corpusers.net> References: <010b01d012ca$05244060$0f6cc120$@alibaba-inc.com> <35FD53F367049845BC99AC72306C23D103E688B313F9@CNBJMBX05.corpusers.net> In-Reply-To: <35FD53F367049845BC99AC72306C23D103E688B313F9@CNBJMBX05.corpusers.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id sB8A08eN024266 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 --- 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 {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I