From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762362AbZFKK0R (ORCPT ); Thu, 11 Jun 2009 06:26:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758083AbZFKK0G (ORCPT ); Thu, 11 Jun 2009 06:26:06 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:57549 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751581AbZFKK0E (ORCPT ); Thu, 11 Jun 2009 06:26:04 -0400 From: KOSAKI Motohiro To: linux-mm , LKML Subject: [PATCH for mmotm 1/5] cleanp page_remove_rmap() Cc: kosaki.motohiro@jp.fujitsu.com, Mel Gorman , Wu Fengguang , Andrew Morton In-Reply-To: <20090611192114.6D4A.A69D9226@jp.fujitsu.com> References: <20090611192114.6D4A.A69D9226@jp.fujitsu.com> Message-Id: <20090611192514.6D4D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Thu, 11 Jun 2009 19:26:04 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Subject: [PATCH] cleanp page_remove_rmap() page_remove_rmap() has multiple PageAnon() test and it has a bit deeply nesting. cleanup here. note: this patch doesn't have behavior change. Signed-off-by: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Cc: Wu Fengguang --- mm/rmap.c | 59 ++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 32 insertions(+), 27 deletions(-) Index: b/mm/rmap.c =================================================================== --- a/mm/rmap.c +++ b/mm/rmap.c @@ -862,34 +862,39 @@ void page_dup_rmap(struct page *page, st */ void page_remove_rmap(struct page *page) { - if (atomic_add_negative(-1, &page->_mapcount)) { - /* - * Now that the last pte has gone, s390 must transfer dirty - * flag from storage key to struct page. We can usually skip - * this if the page is anon, so about to be freed; but perhaps - * not if it's in swapcache - there might be another pte slot - * containing the swap entry, but page not yet written to swap. - */ - if ((!PageAnon(page) || PageSwapCache(page)) && - page_test_dirty(page)) { - page_clear_dirty(page); - set_page_dirty(page); - } - if (PageAnon(page)) - mem_cgroup_uncharge_page(page); - __dec_zone_page_state(page, - PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); - mem_cgroup_update_mapped_file_stat(page, -1); - /* - * It would be tidy to reset the PageAnon mapping here, - * but that might overwrite a racing page_add_anon_rmap - * which increments mapcount after us but sets mapping - * before us: so leave the reset to free_hot_cold_page, - * and remember that it's only reliable while mapped. - * Leaving it set also helps swapoff to reinstate ptes - * faster for those pages still in swapcache. - */ + if (!atomic_add_negative(-1, &page->_mapcount)) { + /* the page is still mapped another one */ + return; } + + /* + * Now that the last pte has gone, s390 must transfer dirty + * flag from storage key to struct page. We can usually skip + * this if the page is anon, so about to be freed; but perhaps + * not if it's in swapcache - there might be another pte slot + * containing the swap entry, but page not yet written to swap. + */ + if ((!PageAnon(page) || PageSwapCache(page)) && + page_test_dirty(page)) { + page_clear_dirty(page); + set_page_dirty(page); + } + if (PageAnon(page)) { + mem_cgroup_uncharge_page(page); + __dec_zone_page_state(page, NR_ANON_PAGES); + } else { + __dec_zone_page_state(page, NR_FILE_MAPPED); + } + mem_cgroup_update_mapped_file_stat(page, -1); + /* + * It would be tidy to reset the PageAnon mapping here, + * but that might overwrite a racing page_add_anon_rmap + * which increments mapcount after us but sets mapping + * before us: so leave the reset to free_hot_cold_page, + * and remember that it's only reliable while mapped. + * Leaving it set also helps swapoff to reinstate ptes + * faster for those pages still in swapcache. + */ } /*