+ mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch added to -mm tree

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Subject: + mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch added to -mm tree
To: vbabka@xxxxxxx,b.zolnierkie@xxxxxxxxxxx,hughd@xxxxxxxxxx,iamjoonsoo.kim@xxxxxxx,kosaki.motohiro@xxxxxxxxxxxxxx,m.szyprowski@xxxxxxxxxxx,mgorman@xxxxxxx,mina86@xxxxxxxxxx,minchan@xxxxxxxxxx,riel@xxxxxxxxxx,ytk.lee@xxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 18 Apr 2014 15:10:51 -0700


The patch titled
     Subject: mm/page_alloc: DEBUG_VM checks for free_list placement of CMA and RESERVE pages
has been added to the -mm tree.  Its filename is
     mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch

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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm/page_alloc: DEBUG_VM checks for free_list placement of CMA and RESERVE pages

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.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yong-Taek Lee <ytk.lee@xxxxxxxxxxx>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/mm.h |   19 +++++++++++++++++++
 mm/page_alloc.c    |    3 +++
 2 files changed, 22 insertions(+)

diff -puN include/linux/mm.h~mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages include/linux/mm.h
--- a/include/linux/mm.h~mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages
+++ a/include/linux/mm.h
@@ -288,6 +288,25 @@ static inline int get_freepage_migratety
 }
 
 /*
+ * 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 -puN mm/page_alloc.c~mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages
+++ a/mm/page_alloc.c
@@ -698,6 +698,8 @@ static void free_pcppages_bulk(struct zo
 			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);
@@ -1191,6 +1193,7 @@ static int rmqueue_bulk(struct zone *zon
 		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
_

Patches currently in -mm which might be from vbabka@xxxxxxx are

thp-close-race-between-split-and-zap-huge-pages.patch
mm-compactionc-isolate_freepages_block-small-tuneup.patch
mm-page_alloc-prevent-migrate_reserve-pages-from-being-misplaced.patch
mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch

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