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authorMichal Hocko <mhocko@suse.cz>2012-01-20 14:33:58 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-23 08:38:47 -0800
commit656a070629adfe23c12768e35ddf91feab469ff7 (patch)
tree42c001d079ec926186873b91d7d84bf66c54bcad
parent687875fb7de4a95223af20ee024282fa9099f860 (diff)
downloadlinux-656a070629adfe23c12768e35ddf91feab469ff7.tar.gz
mm: __count_immobile_pages(): make sure the node is online
page_zone() requires an online node otherwise we are accessing NULL NODE_DATA. This is not an issue at the moment because node_zones are located at the structure beginning but this might change in the future so better be careful about that. Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 21c272d517b..d2186ecb36f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5413,15 +5413,22 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
bool is_pageblock_removable_nolock(struct page *page)
{
- struct zone *zone = page_zone(page);
- unsigned long pfn = page_to_pfn(page);
+ struct zone *zone;
+ unsigned long pfn;
/*
* We have to be careful here because we are iterating over memory
* sections which are not zone aware so we might end up outside of
* the zone but still within the section.
+ * We have to take care about the node as well. If the node is offline
+ * its NODE_DATA will be NULL - see page_zone.
*/
- if (!zone || zone->zone_start_pfn > pfn ||
+ if (!node_online(page_to_nid(page)))
+ return false;
+
+ zone = page_zone(page);
+ pfn = page_to_pfn(page);
+ if (zone->zone_start_pfn > pfn ||
zone->zone_start_pfn + zone->spanned_pages <= pfn)
return false;