[PATCH v3 12/12] memory-hotplug: free node_data when a node is offlined

[Wen Congyang]

We call hotadd_new_pgdat() to allocate memory to store node_data. So we
should free it when removing a node.

CC: David Rientjes <rientjes at google.com>
CC: Jiang Liu <liuj97 at gmail.com>
CC: Len Brown <len.brown at intel.com>
CC: Benjamin Herrenschmidt <benh at kernel.crashing.org>
CC: Paul Mackerras <paulus at samba.org>
CC: Christoph Lameter <cl at linux.com>
Cc: Minchan Kim <minchan.kim at gmail.com>
CC: Andrew Morton <akpm at linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki at jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency at cn.fujitsu.com>
---
 mm/memory_hotplug.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d965da3..e281c31 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1320,9 +1320,12 @@ static int check_cpu_on_node(void *data)
 /* offline the node if all memory sections of this node are removed */
 static void try_offline_node(int nid)
 {
+	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
-	unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+	unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
 	unsigned long pfn;
+	struct page *pgdat_page = virt_to_page(pgdat);
+	int i;
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		unsigned long section_nr = pfn_to_section_nr(pfn);
@@ -1349,6 +1352,21 @@ static void try_offline_node(int nid)
 	 */
 	node_set_offline(nid);
 	unregister_one_node(nid);
+
+	if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page))
+		/* node data is allocated from boot memory */
+		return;
+
+	/* free waittable in each zone */
+	for (i = 0; i < MAX_NR_ZONES; i++) {
+		struct zone *zone = pgdat->node_zones + i;
+
+		if (zone->wait_table)
+			vfree(zone->wait_table);
+	}
+
+	arch_refresh_nodedata(nid, NULL);
+	arch_free_nodedata(pgdat);
 }
 
 int __ref remove_memory(int nid, u64 start, u64 size)
-- 
1.8.0