From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f175.google.com (mail-ie0-f175.google.com [209.85.223.175]) by kanga.kvack.org (Postfix) with ESMTP id 2558E6B0036 for ; Sat, 28 Dec 2013 20:45:23 -0500 (EST) Received: by mail-ie0-f175.google.com with SMTP id x13so10897704ief.20 for ; Sat, 28 Dec 2013 17:45:22 -0800 (PST) Received: from userp1040.oracle.com (userp1040.oracle.com. [156.151.31.81]) by mx.google.com with ESMTPS id nh2si48018356icc.78.2013.12.28.17.45.21 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Sat, 28 Dec 2013 17:45:22 -0800 (PST) From: 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> In-Reply-To: <1388281504-11453-1-git-send-email-sasha.levin@oracle.com> References: <1388281504-11453-1-git-send-email-sasha.levin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kirill@shutemov.name, Sasha Levin 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org