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memory-hotplug: do not allocate pgdat if it was not freed when offline.

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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, we cannot reset
node_data and free pgdat when offlining a node.  Just reset pgdat to 0
and reuse the memory when the node is online again.

The problem is suggested by Kamezawa Hiroyuki.  The idea is from Wen
Congyang.

NOTE: If we don't reset pgdat to 0, the WARN_ON in free_area_init_node()
      will be triggered.

[akpm@linux-foundation.org: fix warning when CONFIG_NEED_MULTIPLE_NODES=n]
[akpm@linux-foundation.org: fix the warning again again]
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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>
This commit is contained in:
Tang Chen 2013-02-22 16:33:18 -08:00 committed by Linus Torvalds
parent d822b86a99
commit a1e565aa3c
1 changed files with 16 additions and 8 deletions
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24
mm/memory_hotplug.c
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@ -1017,11 +1017,14 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
unsigned long zholes_size[MAX_NR_ZONES] = {0}; unsigned long zholes_size[MAX_NR_ZONES] = {0};
unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long start_pfn = start >> PAGE_SHIFT;
pgdat = arch_alloc_nodedata(nid); pgdat = NODE_DATA(nid);
if (!pgdat) if (!pgdat) {
return NULL; pgdat = arch_alloc_nodedata(nid);
if (!pgdat)
return NULL;
arch_refresh_nodedata(nid, pgdat); arch_refresh_nodedata(nid, pgdat);
}
/* we can use NODE_DATA(nid) from here */ /* we can use NODE_DATA(nid) from here */
@ -1074,7 +1077,8 @@ int mem_online_node(int nid)
int __ref add_memory(int nid, u64 start, u64 size) int __ref add_memory(int nid, u64 start, u64 size)
{ {
pg_data_t *pgdat = NULL; pg_data_t *pgdat = NULL;
int new_pgdat = 0; bool new_pgdat;
bool new_node;
struct resource *res; struct resource *res;
int ret; int ret;
@ -1085,12 +1089,16 @@ int __ref add_memory(int nid, u64 start, u64 size)
if (!res) if (!res)
goto out; goto out;
if (!node_online(nid)) { { /* Stupid hack to suppress address-never-null warning */
void *p = NODE_DATA(nid);
new_pgdat = !p;
}
new_node = !node_online(nid);
if (new_node) {
pgdat = hotadd_new_pgdat(nid, start); pgdat = hotadd_new_pgdat(nid, start);
ret = -ENOMEM; ret = -ENOMEM;
if (!pgdat) if (!pgdat)
goto error; goto error;
new_pgdat = 1;
} }
/* call arch's memory hotadd */ /* call arch's memory hotadd */
@ -1102,7 +1110,7 @@ int __ref add_memory(int nid, u64 start, u64 size)
/* we online node here. we can't roll back from here. */ /* we online node here. we can't roll back from here. */
node_set_online(nid); node_set_online(nid);
if (new_pgdat) { if (new_node) {
ret = register_one_node(nid); ret = register_one_node(nid);
/* /*
* If sysfs file of new node can't create, cpu on the node * If sysfs file of new node can't create, cpu on the node