diff mbox

[v7,12/14] arm64/numa: remove the limitation that cpu0 must bind to node0

Message ID 1472024693-12912-13-git-send-email-thunder.leizhen@huawei.com (mailing list archive)
State New, archived
Headers show

Commit Message

Leizhen (ThunderTown) Aug. 24, 2016, 7:44 a.m. UTC 
1. Currently only cpu0 set on cpu_possible_mask and percpu areas have not
   been initialized.
2. No reason to limit cpu0 must belongs to node0.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 arch/arm64/mm/numa.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

--
2.5.0

Comments

Will Deacon Aug. 26, 2016, 3:49 p.m. UTC | #1 
On Wed, Aug 24, 2016 at 03:44:51PM +0800, Zhen Lei wrote:
> 1. Currently only cpu0 set on cpu_possible_mask and percpu areas have not
>    been initialized.
> 2. No reason to limit cpu0 must belongs to node0.

Whilst I suspect you're using enumerated lists in order to try to make
things clearer, I'm having a really hard time understanding the commit
messages you have in this series. It's actually much better if you
structure them as concise paragraphs explaining:

  - What is the problem that you're fixing?

  - How does that problem manifest?

  - How does the patch fix it?

As far as I can see, this patch just removes a bunch of code with no
explanation as to why it's not required or any problems caused by
keeping it around.

Will

> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
>  arch/arm64/mm/numa.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index 114180f..07a1978 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -94,7 +94,6 @@ void numa_clear_node(unsigned int cpu)
>   */
>  static void __init setup_node_to_cpumask_map(void)
>  {
> -	unsigned int cpu;
>  	int node;
> 
>  	/* setup nr_node_ids if not done yet */
> @@ -107,9 +106,6 @@ static void __init setup_node_to_cpumask_map(void)
>  		cpumask_clear(node_to_cpumask_map[node]);
>  	}
> 
> -	for_each_possible_cpu(cpu)
> -		set_cpu_numa_node(cpu, NUMA_NO_NODE);
> -
>  	/* cpumask_of_node() will now work */
>  	pr_debug("Node to cpumask map for %d nodes\n", nr_node_ids);
>  }
> @@ -119,13 +115,13 @@ static void __init setup_node_to_cpumask_map(void)
>   */
>  void numa_store_cpu_info(unsigned int cpu)
>  {
> -	map_cpu_to_node(cpu, numa_off ? 0 : cpu_to_node_map[cpu]);
> +	map_cpu_to_node(cpu, cpu_to_node_map[cpu]);
>  }
> 
>  void __init early_map_cpu_to_node(unsigned int cpu, int nid)
>  {
>  	/* fallback to node 0 */
> -	if (nid < 0 || nid >= MAX_NUMNODES)
> +	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
>  		nid = 0;
> 
>  	cpu_to_node_map[cpu] = nid;
> @@ -375,10 +371,6 @@ static int __init numa_init(int (*init_func)(void))
> 
>  	setup_node_to_cpumask_map();
> 
> -	/* init boot processor */
> -	cpu_to_node_map[0] = 0;
> -	map_cpu_to_node(0, 0);
> -
>  	return 0;
>  }
> 
> --
> 2.5.0
> 
>
Leizhen (ThunderTown) Aug. 29, 2016, 6:55 a.m. UTC | #2 
On 2016/8/26 23:49, Will Deacon wrote:
> On Wed, Aug 24, 2016 at 03:44:51PM +0800, Zhen Lei wrote:
>> 1. Currently only cpu0 set on cpu_possible_mask and percpu areas have not
>>    been initialized.
This description refer to below:
-	for_each_possible_cpu(cpu)
-		set_cpu_numa_node(cpu, NUMA_NO_NODE);

1. When the above code is executed, only the bit of cpu0 was set on cpu_possible_mask.
   So that, only set_cpu_numa_node(0, NUMA_NO_NODE); will be executed.
2. set_cpu_numa_node will access percpu variable numa_node, but setup_per_cpu_areas is
   called after current time. Without the first problem, it will lead kernel crash.

I changed the title of this patch in v7, the original is "remove some useless code".
I think I should separate this into a new patch.



>> 2. No reason to limit cpu0 must belongs to node0.
> 
> Whilst I suspect you're using enumerated lists in order to try to make
> things clearer, I'm having a really hard time understanding the commit
> messages you have in this series. It's actually much better if you
> structure them as concise paragraphs explaining:
> 
>   - What is the problem that you're fixing?
> 
>   - How does that problem manifest?
> 
>   - How does the patch fix it?
> 
> As far as I can see, this patch just removes a bunch of code with no
> explanation as to why it's not required or any problems caused by
> keeping it around.
> 
> Will
> 
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>>  arch/arm64/mm/numa.c | 12 ++----------
>>  1 file changed, 2 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>> index 114180f..07a1978 100644
>> --- a/arch/arm64/mm/numa.c
>> +++ b/arch/arm64/mm/numa.c
>> @@ -94,7 +94,6 @@ void numa_clear_node(unsigned int cpu)
>>   */
>>  static void __init setup_node_to_cpumask_map(void)
>>  {
>> -	unsigned int cpu;
>>  	int node;
>>
>>  	/* setup nr_node_ids if not done yet */
>> @@ -107,9 +106,6 @@ static void __init setup_node_to_cpumask_map(void)
>>  		cpumask_clear(node_to_cpumask_map[node]);
>>  	}
>>
>> -	for_each_possible_cpu(cpu)
>> -		set_cpu_numa_node(cpu, NUMA_NO_NODE);
>> -
>>  	/* cpumask_of_node() will now work */
>>  	pr_debug("Node to cpumask map for %d nodes\n", nr_node_ids);
>>  }
>> @@ -119,13 +115,13 @@ static void __init setup_node_to_cpumask_map(void)
>>   */
>>  void numa_store_cpu_info(unsigned int cpu)
>>  {
>> -	map_cpu_to_node(cpu, numa_off ? 0 : cpu_to_node_map[cpu]);
>> +	map_cpu_to_node(cpu, cpu_to_node_map[cpu]);
>>  }
>>
>>  void __init early_map_cpu_to_node(unsigned int cpu, int nid)
>>  {
>>  	/* fallback to node 0 */
>> -	if (nid < 0 || nid >= MAX_NUMNODES)
>> +	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
>>  		nid = 0;
After the below code have been removed, we should make the corresponding adjustment.
otherwise, kernel will be crashed if "numa=off" was set in bootargs.

>>
>>  	cpu_to_node_map[cpu] = nid;
>> @@ -375,10 +371,6 @@ static int __init numa_init(int (*init_func)(void))
>>
>>  	setup_node_to_cpumask_map();
>>
>> -	/* init boot processor */
>> -	cpu_to_node_map[0] = 0;
>> -	map_cpu_to_node(0, 0);
These code limit cpu0 must belong to node0, but our current implementation deesn't
have this limitation.

>> -
>>  	return 0;
>>  }
>>
>> --
>> 2.5.0
>>
>>
> 
> .
>
diff mbox

Patch

diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 114180f..07a1978 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -94,7 +94,6 @@  void numa_clear_node(unsigned int cpu)
  */
 static void __init setup_node_to_cpumask_map(void)
 {
-	unsigned int cpu;
 	int node;

 	/* setup nr_node_ids if not done yet */
@@ -107,9 +106,6 @@  static void __init setup_node_to_cpumask_map(void)
 		cpumask_clear(node_to_cpumask_map[node]);
 	}

-	for_each_possible_cpu(cpu)
-		set_cpu_numa_node(cpu, NUMA_NO_NODE);
-
 	/* cpumask_of_node() will now work */
 	pr_debug("Node to cpumask map for %d nodes\n", nr_node_ids);
 }
@@ -119,13 +115,13 @@  static void __init setup_node_to_cpumask_map(void)
  */
 void numa_store_cpu_info(unsigned int cpu)
 {
-	map_cpu_to_node(cpu, numa_off ? 0 : cpu_to_node_map[cpu]);
+	map_cpu_to_node(cpu, cpu_to_node_map[cpu]);
 }

 void __init early_map_cpu_to_node(unsigned int cpu, int nid)
 {
 	/* fallback to node 0 */
-	if (nid < 0 || nid >= MAX_NUMNODES)
+	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
 		nid = 0;

 	cpu_to_node_map[cpu] = nid;
@@ -375,10 +371,6 @@  static int __init numa_init(int (*init_func)(void))

 	setup_node_to_cpumask_map();

-	/* init boot processor */
-	cpu_to_node_map[0] = 0;
-	map_cpu_to_node(0, 0);
-
 	return 0;
 }