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author | Tang Chen <tangchen@cn.fujitsu.com> | 2013-02-22 16:33:18 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-23 17:50:13 -0800 |
commit | a1e565aa3cfc7c6252cabc93de8391d12b9216aa (patch) | |
tree | f02974503acc8b61a7d8857c36dfb8b6cf7897ab | |
parent | d822b86a99e8d2b7ebbe3aba099288354287a885 (diff) | |
download | op-kernel-dev-a1e565aa3cfc7c6252cabc93de8391d12b9216aa.zip op-kernel-dev-a1e565aa3cfc7c6252cabc93de8391d12b9216aa.tar.gz |
memory-hotplug: do not allocate pgdat if it was not freed when offline.
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>
-rw-r--r-- | mm/memory_hotplug.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 3409134..e189b1f 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -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 start_pfn = start >> PAGE_SHIFT; - pgdat = arch_alloc_nodedata(nid); - if (!pgdat) - return NULL; + pgdat = NODE_DATA(nid); + if (!pgdat) { + 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 */ @@ -1074,7 +1077,8 @@ out: int __ref add_memory(int nid, u64 start, u64 size) { pg_data_t *pgdat = NULL; - int new_pgdat = 0; + bool new_pgdat; + bool new_node; struct resource *res; int ret; @@ -1085,12 +1089,16 @@ int __ref add_memory(int nid, u64 start, u64 size) if (!res) 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); ret = -ENOMEM; if (!pgdat) goto error; - new_pgdat = 1; } /* 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. */ node_set_online(nid); - if (new_pgdat) { + if (new_node) { ret = register_one_node(nid); /* * If sysfs file of new node can't create, cpu on the node |