From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751819Ab3L2Bp0 (ORCPT ); Sat, 28 Dec 2013 20:45:26 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:39600 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751194Ab3L2BpY (ORCPT ); Sat, 28 Dec 2013 20:45:24 -0500 From: Sasha Levin To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kirill@shutemov.name, Sasha Levin Subject: [RFC 2/2] mm: additional checks to page flag set/clear Date: Sat, 28 Dec 2013 20:45:04 -0500 Message-Id: <1388281504-11453-2-git-send-email-sasha.levin@oracle.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1388281504-11453-1-git-send-email-sasha.levin@oracle.com> References: <1388281504-11453-1-git-send-email-sasha.levin@oracle.com> X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Check if the flag is already set before setting it, and vice versa for clearing. Obviously setting or clearing a flag twice isn't a problem on it's own, but it implies that there's an issue where some piece of code assumed an opposite state of the flag. Signed-off-by: Sasha Levin --- include/linux/page-flags.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d1fe1a7..36b0bef 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -130,6 +130,12 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H +#ifdef CONFIG_DEBUG_VM_PAGE_FLAGS +#define VM_ASSERT_FLAG(assert, page) VM_BUG_ON_PAGE(assert, page) +#else +#define VM_ASSERT_FLAG(assert, page) do { } while (0) +#endif + /* * Macros to create function definitions for page flags */ @@ -139,11 +145,13 @@ static inline int Page##uname(const struct page *page) \ #define SETPAGEFLAG(uname, lname) \ static inline void SetPage##uname(struct page *page) \ - { set_bit(PG_##lname, &page->flags); } + { VM_ASSERT_FLAG(Page##uname(page), page); \ + set_bit(PG_##lname, &page->flags); } #define CLEARPAGEFLAG(uname, lname) \ static inline void ClearPage##uname(struct page *page) \ - { clear_bit(PG_##lname, &page->flags); } + { VM_ASSERT_FLAG(!Page##uname(page), page); \ + clear_bit(PG_##lname, &page->flags); } #define __SETPAGEFLAG(uname, lname) \ static inline void __SetPage##uname(struct page *page) \ -- 1.8.3.2