Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752806AbaDCPkr (ORCPT ); Thu, 3 Apr 2014 11:40:47 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40141 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752769AbaDCPkn (ORCPT ); Thu, 3 Apr 2014 11:40:43 -0400 From: Vlastimil Babka To: Andrew Morton , Joonsoo Kim , Bartlomiej Zolnierkiewicz Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman , Yong-Taek Lee , Vlastimil Babka , Minchan Kim , KOSAKI Motohiro , Marek Szyprowski , Hugh Dickins , Rik van Riel , Michal Nazarewicz Subject: [PATCH 2/2] mm/page_alloc: DEBUG_VM checks for free_list placement of CMA and RESERVE pages Date: Thu, 3 Apr 2014 17:40:18 +0200 Message-Id: <1396539618-31362-2-git-send-email-vbabka@suse.cz> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1396539618-31362-1-git-send-email-vbabka@suse.cz> References: <533D8015.1000106@suse.cz> <1396539618-31362-1-git-send-email-vbabka@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For the MIGRATE_RESERVE pages, it is important they do not get misplaced on free_list of other migratetype, otherwise the whole MIGRATE_RESERVE pageblock might be changed to other migratetype in try_to_steal_freepages(). For MIGRATE_CMA, the pages also must not go to a different free_list, otherwise they could get allocated as unmovable and result in CMA failure. This is ensured by setting the freepage_migratetype appropriately when placing pages on pcp lists, and using the information when releasing them back to free_list. It is also assumed that CMA and RESERVE pageblocks are created only in the init phase. This patch adds DEBUG_VM checks to catch any regressions introduced for this invariant. Cc: Yong-Taek Lee Cc: Bartlomiej Zolnierkiewicz Cc: Joonsoo Kim Cc: Mel Gorman Cc: Minchan Kim Cc: KOSAKI Motohiro Cc: Marek Szyprowski Cc: Hugh Dickins Cc: Rik van Riel Cc: Michal Nazarewicz Signed-off-by: Vlastimil Babka --- include/linux/mm.h | 19 +++++++++++++++++++ mm/page_alloc.c | 3 +++ 2 files changed, 22 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index c1b7414..27a74ba 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -280,6 +280,25 @@ static inline int get_freepage_migratetype(struct page *page) } /* + * Check that a freepage cannot end up on a wrong free_list for "sensitive" + * migratetypes. Return false if it could. Useful for VM_BUG_ON checks. + */ +static inline bool check_freepage_migratetype(struct page *page) +{ + int pageblock_mt = get_pageblock_migratetype(page); + int freepage_mt = get_freepage_migratetype(page); + + /* + * For RESERVE and CMA pageblocks, the freepage_migratetype must + * match their migratetype. For other pageblocks, we don't care. + */ + if (pageblock_mt != MIGRATE_RESERVE && !is_migrate_cma(pageblock_mt)) + return true; + + return (freepage_mt == pageblock_mt); +} + +/* * FIXME: take this include out, include page-flags.h in * files which need it (119 of them) */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2dbaba1..0ee9f8c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -697,6 +697,8 @@ static void free_pcppages_bulk(struct zone *zone, int count, page = list_entry(list->prev, struct page, lru); /* must delete as __free_one_page list manipulates */ list_del(&page->lru); + + VM_BUG_ON(!check_freepage_migratetype(page)); mt = get_freepage_migratetype(page); /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */ __free_one_page(page, zone, 0, mt); @@ -1190,6 +1192,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, struct page *page = __rmqueue(zone, order, migratetype); if (unlikely(page == NULL)) break; + VM_BUG_ON(!check_freepage_migratetype(page)); /* * Split buddy pages returned by expand() are received here -- 1.8.4.5 -- 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/