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Subject[PATCH v2 2/2] mem-hotplug: Reset node present pages when hot-adding a new pgdat.
Date
When onlining memory on node2, node2 zoneinfo and node3 meminfo corrupted:

# for ((i = 2048; i < 2064; i++)); do echo online_movable > /sys/devices/system/node/node2/memory$i/state; done
# cat /sys/devices/system/node/node2/meminfo
Node 2 MemTotal: 33554432 kB
Node 2 MemFree: 33549092 kB
Node 2 MemUsed: 5340 kB
......
# cat /sys/devices/system/node/node3/meminfo
Node 3 MemTotal: 0 kB
Node 3 MemFree: 248 kB /* corrupted, should be 0 */
Node 3 MemUsed: 0 kB
......

# cat /proc/zoneinfo
......
Node 2, zone Movable
......
spanned 8388608
present 16777216 /* corrupted, should be 8388608 */
managed 8388608


When memory is hot-added, all the memory is in offline state. So
clear all zone->present_pages because they will be updated in
online_pages() and offline_pages().

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
mm/memory_hotplug.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8aba12b..26eac61 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1067,6 +1067,14 @@ out:
}
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */

+static void reset_node_present_pages(pg_data_t *pgdat)
+{
+ struct zone *z;
+
+ for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+ z->present_pages = 0;
+}
+
/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
{
@@ -1105,6 +1113,13 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
*/
reset_node_managed_pages(pgdat);

+ /*
+ * When memory is hot-added, all the memory is in offline state. So
+ * clear all zones' present_pages because they will be updated in
+ * online_pages() and offline_pages().
+ */
+ reset_node_present_pages(pgdat);
+
return pgdat;
}

--
1.8.3.1


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