From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759416AbZCPJvq (ORCPT ); Mon, 16 Mar 2009 05:51:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754947AbZCPJog (ORCPT ); Mon, 16 Mar 2009 05:44:36 -0400 Received: from gir.skynet.ie ([193.1.99.77]:49696 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752295AbZCPJob (ORCPT ); Mon, 16 Mar 2009 05:44:31 -0400 From: Mel Gorman To: Mel Gorman , Linux Memory Management List Cc: Pekka Enberg , Rik van Riel , KOSAKI Motohiro , Christoph Lameter , Johannes Weiner , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra Subject: [PATCH 21/35] Do not check for compound pages during the page allocator sanity checks Date: Mon, 16 Mar 2009 09:46:16 +0000 Message-Id: <1237196790-7268-22-git-send-email-mel@csn.ul.ie> X-Mailer: git-send-email 1.5.6.5 In-Reply-To: <1237196790-7268-1-git-send-email-mel@csn.ul.ie> References: <1237196790-7268-1-git-send-email-mel@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 d297780..2704092 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -425,7 +425,7 @@ 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; @@ -501,7 +501,7 @@ 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; @@ -646,7 +646,7 @@ 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id D2C336B0087 for ; Mon, 16 Mar 2009 05:44:32 -0400 (EDT) From: Mel Gorman Subject: [PATCH 21/35] Do not check for compound pages during the page allocator sanity checks Date: Mon, 16 Mar 2009 09:46:16 +0000 Message-Id: <1237196790-7268-22-git-send-email-mel@csn.ul.ie> In-Reply-To: <1237196790-7268-1-git-send-email-mel@csn.ul.ie> References: <1237196790-7268-1-git-send-email-mel@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman , Linux Memory Management List Cc: Pekka Enberg , Rik van Riel , KOSAKI Motohiro , Christoph Lameter , Johannes Weiner , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra List-ID: 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 --- 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 d297780..2704092 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -425,7 +425,7 @@ 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; @@ -501,7 +501,7 @@ 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; @@ -646,7 +646,7 @@ 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, 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