Hi Andrew,
On 2013/8/7 5:03, Andrew Morton wrote:
> On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu <wujianguo@xxxxxxxxxx> wrote:
>
>> If node == NUMA_NO_NODE, pol is NULL, we should return NULL instead of
>> do "if (!pol->mode)" check.
>>
>> Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx>
>> ---
>> mm/mempolicy.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
>> index 4baf12e..e0e3398 100644
>> --- a/mm/mempolicy.c
>> +++ b/mm/mempolicy.c
>> @@ -129,6 +129,8 @@ static struct mempolicy *get_task_policy(struct task_struct *p)
>> node = numa_node_id();
>> if (node != NUMA_NO_NODE)
>> pol = &preferred_node_policy[node];
>> + else
>> + return NULL;
>>
>> /* preferred_node_policy is not initialised early in boot */
>> if (!pol->mode)
>
> Well yes, it'll dereference a null pointer
>
> This is neater, I think:
>
Yes, this is more readable, Thanks.
> --- a/mm/mempolicy.c~mm-mempolicy-return-null-if-node-is-numa_no_node-in-get_task_policy
> +++ a/mm/mempolicy.c
> @@ -123,16 +123,19 @@ static struct mempolicy preferred_node_p
> static struct mempolicy *get_task_policy(struct task_struct *p)
> {
> struct mempolicy *pol = p->mempolicy;
> - int node;
>
> if (!pol) {
> - node = numa_node_id();
> - if (node != NUMA_NO_NODE)
> - pol = &preferred_node_policy[node];
> + int node = numa_node_id();
>
> - /* preferred_node_policy is not initialised early in boot */
> - if (!pol->mode)
> - pol = NULL;
> + if (node != NUMA_NO_NODE) {
> + pol = &preferred_node_policy[node];
> + /*
> + * preferred_node_policy is not initialised early in
> + * boot
> + */
> + if (!pol->mode)
> + pol = NULL;
> + }
> }
>
> return pol;
> _
>
>
> .
>
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