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mm: __count_immobile_pages(): make sure the node is online

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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>
This commit is contained in:
Michal Hocko 2012-01-20 14:33:58 -08:00 committed by Linus Torvalds
parent 687875fb7d
commit 656a070629
1 changed files with 10 additions and 3 deletions
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13
mm/page_alloc.c
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@ -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;