Re: [patch 2/2] mm, hotplug: protect zonelist building with zonelists_mutex

KOSAKI Motohiro
2011-06-23T01:35:07Z

(2011/06/23 10:13), David Rientjes wrote:
> 959ecc48fc75 ("mm/memory_hotplug.c: fix building of node hotplug
> zonelist") does not protect the build_all_zonelists() call with
> zonelists_mutex as needed. This can lead to races in constructing
> zonelist ordering if a concurrent build is underway. Protecting this with
> lock_memory_hotplug() is insufficient since zonelists can be rebuild
> though sysfs as well.
>
> Signed-off-by: David Rientjes <rientjes@google.com>

Indeed.

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

> ---
> mm/memory_hotplug.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -498,7 +498,9 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
> * The node we allocated has no zone fallback lists. For avoiding
> * to access not-initialized zonelist, build here.
> */
> + mutex_lock(&zonelists_mutex);
> build_all_zonelists(NULL);
> + mutex_unlock(&zonelists_mutex);
>
> return pgdat;
> }
>
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