Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758002AbZCTKK2 (ORCPT ); Fri, 20 Mar 2009 06:10:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756035AbZCTKCw (ORCPT ); Fri, 20 Mar 2009 06:02:52 -0400 Received: from gir.skynet.ie ([193.1.99.77]:55097 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757329AbZCTKCq (ORCPT ); Fri, 20 Mar 2009 06:02:46 -0400 From: Mel Gorman To: Mel Gorman , Linux Memory Management List Cc: KOSAKI Motohiro , Christoph Lameter , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra , Andrew Morton Subject: [PATCH 20/25] Do not check for compound pages during the page allocator sanity checks Date: Fri, 20 Mar 2009 10:03:07 +0000 Message-Id: <1237543392-11797-21-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.5.6.5 In-Reply-To: <1237543392-11797-1-git-send-email-mel@csn.ul.ie> References: <1237543392-11797-1-git-send-email-mel@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2048 Lines: 57 A number of sanity checks are made on each page allocation and free including that the page count is zero. page_count() checks for compound pages and checks the count of the head page if true. However, in these paths, we do not care if the page is compound or not as the count of each tail page should also be zero. This patch makes two changes to the use of page_count() in the free path. It converts one check of page_count() to a VM_BUG_ON() as the count should have been unconditionally checked earlier in the free path. It also avoids checking for compound pages. [mel@csn.ul.ie: Wrote changelog] Signed-off-by: Nick Piggin Reviewed-by: Christoph Lameter --- mm/page_alloc.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 01cd489..fb5c4da 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -424,7 +424,7 @@ static inline int page_is_buddy(struct page *page, struct page *buddy, return 0; if (PageBuddy(buddy) && page_order(buddy) == order) { - BUG_ON(page_count(buddy) != 0); + VM_BUG_ON(page_count(buddy) != 0); return 1; } return 0; @@ -500,7 +500,7 @@ static inline int free_pages_check(struct page *page) { if (unlikely(page_mapcount(page) | (page->mapping != NULL) | - (page_count(page) != 0) | + (atomic_read(&page->_count) != 0) | (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) { bad_page(page); return 1; @@ -645,7 +645,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) { if (unlikely(page_mapcount(page) | (page->mapping != NULL) | - (page_count(page) != 0) | + (atomic_read(&page->_count) != 0) | (page->flags & PAGE_FLAGS_CHECK_AT_PREP))) { bad_page(page); return 1; -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/