mem-hotplug: reset node present pages when hot-adding a new 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(). Otherwise, /proc/zoneinfo will corrupt: When the memory of node2 is offline: # cat /proc/zoneinfo ...... Node 2, zone Movable ...... spanned 8388608 present 8388608 managed 0 When we online memory on node2: # cat /proc/zoneinfo ...... Node 2, zone Movable ...... spanned 8388608 present 16777216 managed 8388608 Signed-off-by: Tang Chen <[email protected]> Reviewed-by: Yasuaki Ishimatsu <[email protected]> Cc: <[email protected]> [3.16+] Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ashr · Nov 14, 2014 · 0bd8542 · 0bd8542
1 parent f784a3f
commit 0bd8542
Showing 1 changed file with 17 additions and 0 deletions.
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
@@ -1067,6 +1067,16 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 }
 #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;
+
+	pgdat->node_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 +1115,13 @@ 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;
 }