Re: [patch 1/2] mm, hotplug: fix error handling in mem_online_node()

KOSAKI Motohiro
2011-06-23T01:31:25Z

(2011/06/23 10:13), David Rientjes wrote:
> The error handling in mem_online_node() is incorrect: hotadd_new_pgdat()
> returns NULL if the new pgdat could not have been allocated and a pointer
> to it otherwise.
>
> mem_online_node() should fail if hotadd_new_pgdat() fails, not the
> inverse. This fixes an issue when memoryless nodes are not onlined and
> their sysfs interface is not registered when their first cpu is brought
> up.
>
> Signed-off-by: David Rientjes <rientjes@google.com>

Nice catch.

The fault was introduced by commit cf23422b9d76(cpu/mem hotplug: enable CPUs
online before local memory online) iow v2.6.35.

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

> ---
> mm/memory_hotplug.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -521,7 +521,7 @@ int mem_online_node(int nid)
>
> lock_memory_hotplug();
> pgdat = hotadd_new_pgdat(nid, 0);
> - if (pgdat) {
> + if (!pgdat) {
> ret = -ENOMEM;
> goto out;
> }
>
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