Re: [PATCH v2] openvswitch: allocate nr_node_ids flow_stats instead of num_possible_nodes

[Nishanth Aravamudan <nacc-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On 21.07.2015 [12:36:33 -0500], Chris J Arges wrote:
> Some architectures like POWER can have a NUMA node_possible_map that
> contains sparse entries. This causes memory corruption with openvswitch
> since it allocates flow_cache with a multiple of num_possible_nodes() and
> assumes the node variable returned by for_each_node will index into
> flow->stats[node].
> 
> Use nr_node_ids to allocate a maximal sparse array instead of
> num_possible_nodes().
> 
> The crash was noticed after 3af229f2 was applied as it changed the
> node_possible_map to match node_online_map on boot.
> Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
> 
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> ---
>  net/openvswitch/flow_table.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 4613df8..6552394 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -752,7 +752,7 @@ int ovs_flow_init(void)
>  	BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
> 
>  	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
> -				       + (num_possible_nodes()
> +				       + (nr_node_ids
>  					  * sizeof(struct flow_stats *)),
>  				       0, 0, NULL);
>  	if (flow_cache == NULL)
> -- 
> 1.9.1
> 

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