memory-hotplug: free node_data when a node is offlined

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

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Wu Jianguo <wujianguo@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index aea6374..3409134 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1700,9 +1700,12 @@ 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)
 {
-       unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
-       unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+       pg_data_t *pgdat = NODE_DATA(nid);
+       unsigned long start_pfn = pgdat->node_start_pfn;
+       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);
@@ -1720,7 +1723,7 @@ static void try_offline_node(int nid)
                return;
        }
 
-       if (stop_machine(check_cpu_on_node, NODE_DATA(nid), NULL))
+       if (stop_machine(check_cpu_on_node, pgdat, NULL))
                return;
 
        /*
@@ -1729,6 +1732,27 @@ 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);
+       }
+
+       /*
+        * Since there is no way to guarentee the address of pgdat/zone is not
+        * on stack of any kernel threads or used by other kernel objects
+        * without reference counting or other symchronizing method, do not
+        * reset node_data and free pgdat here. Just reset it to 0 and reuse
+        * the memory when the node is online again.
+        */
+       memset(pgdat, 0, sizeof(*pgdat));
 }
 
 int __ref remove_memory(int nid, u64 start, u64 size)