From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 226836B00BA for ; Wed, 22 Apr 2009 09:53:09 -0400 (EDT) From: Mel Gorman Subject: [PATCH 17/22] Do not check for compound pages during the page allocator sanity checks Date: Wed, 22 Apr 2009 14:53:22 +0100 Message-Id: <1240408407-21848-18-git-send-email-mel@csn.ul.ie> In-Reply-To: <1240408407-21848-1-git-send-email-mel@csn.ul.ie> References: <1240408407-21848-1-git-send-email-mel@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman , Linux Memory Management List Cc: KOSAKI Motohiro , Christoph Lameter , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra , Pekka Enberg , Andrew Morton 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 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 e59bb80..b174f2c 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