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Subject[RFC 05/16] mm/vmstat: watch out zone range overlap
In the following patches, new zone, ZONE_CMA, will be introduced and
it would be overlapped with other zones. Currently, many places
iterating pfn range doesn't consider possibility of zone overlap and
this would cause a problem such as printing wrong statistics information.
To prevent this situation, this patch add some code to consider zone
overlapping before adding ZONE_CMA.

pagetypeinfo_showblockcount_print() prints zone's statistics so should
consider zone overlap.

Signed-off-by: Joonsoo Kim <>
mm/vmstat.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 1b12d39..7a4ac8e 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -984,6 +984,8 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,

page = pfn_to_page(pfn);
+ if (page_zone(page) != zone)
+ continue;

/* Watch for unexpected holes punched in the memmap */
if (!memmap_valid_within(pfn, page, zone))

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