From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759123Ab2IGG0P (ORCPT ); Fri, 7 Sep 2012 02:26:15 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:53823 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752979Ab2IGG0O (ORCPT ); Fri, 7 Sep 2012 02:26:14 -0400 MIME-Version: 1.0 In-Reply-To: <1346829962-31989-4-git-send-email-minchan@kernel.org> References: <1346829962-31989-1-git-send-email-minchan@kernel.org> <1346829962-31989-4-git-send-email-minchan@kernel.org> Date: Fri, 7 Sep 2012 14:26:13 +0800 Message-ID: Subject: Re: [PATCH 3/3] memory-hotplug: bug fix race between isolation and allocation From: jencce zhou To: Minchan Kim Cc: Andrew Morton , Kamezawa Hiroyuki , Yasuaki Ishimatsu , Xishi Qiu , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2012/9/5 Minchan Kim : > Like below, memory-hotplug makes race between page-isolation > and page-allocation so it can hit BUG_ON in __offline_isolated_pages. > > CPU A CPU B > > start_isolate_page_range > set_migratetype_isolate > spin_lock_irqsave(zone->lock) > > free_hot_cold_page(Page A) > /* without zone->lock */ > migratetype = get_pageblock_migratetype(Page A); > /* > * Page could be moved into MIGRATE_MOVABLE > * of per_cpu_pages > */ > list_add_tail(&page->lru, &pcp->lists[migratetype]); > > set_pageblock_isolate here > move_freepages_block > drain_all_pages > > /* Page A could be in MIGRATE_MOVABLE of free_list. */ why ? should it has been moved to MIGRATE_ISOLATE list ? > > check_pages_isolated > __test_page_isolated_in_pageblock > /* > * We can't catch freed page which > * is free_list[MIGRATE_MOVABLE] > */ > if (PageBuddy(page A)) > pfn += 1 << page_order(page A); > > /* So, Page A could be allocated */ > > __offline_isolated_pages > /* > * BUG_ON hit or offline page > * which is used by someone > */ > BUG_ON(!PageBuddy(page A)); > > Signed-off-by: Minchan Kim > --- > mm/page_isolation.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index acf65a7..4699d1f 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -196,8 +196,11 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn) > continue; > } > page = pfn_to_page(pfn); > - if (PageBuddy(page)) > + if (PageBuddy(page)) { > + if (get_page_migratetype(page) != MIGRATE_ISOLATE) > + break; > pfn += 1 << page_order(page); > + } > else if (page_count(page) == 0 && > get_page_migratetype(page) == MIGRATE_ISOLATE) > pfn += 1; > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/