From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id F04766B0032 for ; Tue, 9 Dec 2014 02:51:49 -0500 (EST) Received: by mail-pa0-f45.google.com with SMTP id lj1so59313pab.18 for ; Mon, 08 Dec 2014 23:51:49 -0800 (PST) Received: from mailout1.samsung.com (mailout1.samsung.com. [203.254.224.24]) by mx.google.com with ESMTPS id d5si569432pdd.145.2014.12.08.23.51.47 for (version=TLSv1 cipher=RC4-MD5 bits=128/128); Mon, 08 Dec 2014 23:51:48 -0800 (PST) Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NGB00HTD1UA1SB0@mailout1.samsung.com> for linux-mm@kvack.org; Tue, 09 Dec 2014 16:51:46 +0900 (KST) From: Weijie Yang Subject: [PATCH 1/3] mm: page_isolation: remove redundant moving for isolated buddy pages Date: Tue, 09 Dec 2014 15:50:35 +0800 Message-id: <000101d01384$fac61240$f05236c0$%yang@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-transfer-encoding: 7bit Content-language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: iamjoonsoo.kim@lge.com Cc: 'Andrew Morton' , mgorman@suse.de, 'Rik van Riel' , vbabka@suse.cz, 'Johannes Weiner' , 'Minchan Kim' , 'Weijie Yang' , linux-kernel@vger.kernel.org, linux-mm@kvack.org The commit ad53f92e(fix incorrect isolation behavior by rechecking migratetype) patch series describe the race between page isolation and alloc/free path, and fix the race. Now, after the pageblock has been isolated, free buddy pages are already in the free_list[MIGRATE_ISOLATE] and will not be allocated for usage. So the current freepage_migratetype check is unnecessary and it will cause redundant page move. That is to say, even if the buddy page's migratetype is not MIGRATE_ISOLATE, the page is in free_list[MIGRATE_ISOLATE], we just move it from free_list[MIGRATE_ISOLATE] to free_list[MIGRATE_ISOLATE]. This patch removes the unnecessary freepage_migratetype check and the redundant page moving. Signed-off-by: Weijie Yang --- mm/page_isolation.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index c8778f7..6e5174d 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -221,23 +221,8 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, continue; } page = pfn_to_page(pfn); - if (PageBuddy(page)) { - /* - * If race between isolatation and allocation happens, - * some free pages could be in MIGRATE_MOVABLE list - * although pageblock's migratation type of the page - * is MIGRATE_ISOLATE. Catch it and move the page into - * MIGRATE_ISOLATE list. - */ - if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { - struct page *end_page; - - end_page = page + (1 << page_order(page)) - 1; - move_freepages(page_zone(page), page, end_page, - MIGRATE_ISOLATE); - } + if (PageBuddy(page)) pfn += 1 << page_order(page); - } else if (page_count(page) == 0 && get_freepage_migratetype(page) == MIGRATE_ISOLATE) pfn += 1; -- 1.7.10.4 -- 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