linux-kernel - [PATCH 4/6] mm: add set_pageblock_migratetype

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Date:	Fri, 28 Feb 2014 15:15:02 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 4/6] mm: add set_pageblock_migratetype_nolock() for calls outside zone->lock

To prevent races, set_pageblock_migratetype() should be called with zone->lock
held. This patch adds a debugging assertion and introduces a _nolock variant
for zone init functions.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/page_alloc.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index de5b419..fd6a64c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -232,7 +232,7 @@ EXPORT_SYMBOL(nr_online_nodes);
 
 int page_group_by_mobility_disabled __read_mostly;
 
-void set_pageblock_migratetype(struct page *page, int migratetype)
+static void set_pageblock_migratetype_nolock(struct page *page, int migratetype)
 {
 	if (unlikely(page_group_by_mobility_disabled &&
 		     migratetype < MIGRATE_PCPTYPES))
@@ -242,6 +242,13 @@ void set_pageblock_migratetype(struct page *page, int migratetype)
 					PB_migrate, PB_migrate_end);
 }
 
+void set_pageblock_migratetype(struct page *page, int migratetype)
+{
+	VM_BUG_ON(!spin_is_locked(&page_zone(page)->lock));
+
+	set_pageblock_migratetype_nolock(page, migratetype);
+}
+
 bool oom_killer_disabled __read_mostly;
 
 #ifdef CONFIG_DEBUG_VM
@@ -803,7 +810,7 @@ void __init init_cma_reserved_pageblock(struct page *page)
 	} while (++p, --i);
 
 	set_page_refcounted(page);
-	set_pageblock_migratetype(page, MIGRATE_CMA);
+	set_pageblock_migratetype_nolock(page, MIGRATE_CMA);
 	__free_pages(page, pageblock_order);
 	adjust_managed_page_count(page, pageblock_nr_pages);
 }
@@ -4100,7 +4107,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		if ((z->zone_start_pfn <= pfn)
 		    && (pfn < zone_end_pfn(z))
 		    && !(pfn & (pageblock_nr_pages - 1)))
-			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+			set_pageblock_migratetype_nolock(page, MIGRATE_MOVABLE);
 
 		INIT_LIST_HEAD(&page->lru);
 #ifdef WANT_PAGE_VIRTUAL
-- 
1.8.4.5

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