Re: [PATCH] mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy

[Jianguo Wu]

Hi Andrew,

On 2013/8/7 5:03, Andrew Morton wrote:

> On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu  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 
>> ---
>>  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 = _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 = _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 = _node_policy[node];
> + /*
> +  * preferred_node_policy is not initialised early in
> +  * boot
> +  */
> + if (!pol->mode)
> + pol = NULL;
> + }
>   }
>  
>   return pol;
> _
> 
> 
> .
> 



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Re: [PATCH] mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy

[Andrew Morton]

On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu  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 
> ---
>  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 = _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:

--- 
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 = _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 = _node_policy[node];
+   /*
+* preferred_node_policy is not initialised early in
+* boot
+*/
+   if (!pol->mode)
+   pol = NULL;
+   }
}
 
return pol;
_

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Re: [PATCH] mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy

[Andrew Morton]

On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu wujian...@huawei.com 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 wujian...@huawei.com
 ---
  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:

--- 
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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Re: [PATCH] mm/mempolicy: return NULL if node is NUMA_NO_NODE in get_task_policy

[Jianguo Wu]

Hi Andrew,

On 2013/8/7 5:03, Andrew Morton wrote:

 On Tue, 6 Aug 2013 12:06:56 +0800 Jianguo Wu wujian...@huawei.com 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 wujian...@huawei.com
 ---
  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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