From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757078Ab2IGAtg (ORCPT ); Thu, 6 Sep 2012 20:49:36 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:32869 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752914Ab2IGAtf (ORCPT ); Thu, 6 Sep 2012 20:49:35 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.8.4 Message-ID: <50494473.8030008@jp.fujitsu.com> Date: Fri, 07 Sep 2012 09:48:51 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:14.0) Gecko/20120713 Thunderbird/14.0 MIME-Version: 1.0 To: Minchan Kim CC: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Yasuaki Ishimatsu , Xishi Qiu , Wen Congyang Subject: Re: [PATCH v3 4/4] memory-hotplug: fix pages missed by race rather than failng References: <1346978372-17903-1-git-send-email-minchan@kernel.org> <1346978372-17903-5-git-send-email-minchan@kernel.org> In-Reply-To: <1346978372-17903-5-git-send-email-minchan@kernel.org> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2012/09/07 9:39), Minchan Kim wrote: > If race between allocation and isolation in memory-hotplug offline > happens, some pages could be in MIGRATE_MOVABLE of free_list although > the pageblock's migratetype of the page is MIGRATE_ISOLATE. > > The race could be detected by get_freepage_migratetype > in __test_page_isolated_in_pageblock. If it is detected, now EBUSY > gets bubbled all the way up and the hotplug operations fails. > > But better idea is instead of returning and failing memory-hotremove, > move the free page to the correct list at the time it is detected. > It could enhance memory-hotremove operation success ratio although > the race is really rare. > > Suggested-by: Mel Gorman > Signed-off-by: Minchan Kim Sounds reasonable. Thank you very much ! Acked-by: KAMEZAWA Hiroyuki