[v5] numa: make node_to_cpumask_map() NUMA_NO_NODE aware
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Message ID 1568640481-133352-1-git-send-email-linyunsheng@huawei.com
State New
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  • [v5] numa: make node_to_cpumask_map() NUMA_NO_NODE aware
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Commit Message

Yunsheng Lin Sept. 16, 2019, 1:28 p.m. UTC
When passing the return value of dev_to_node() to cpumask_of_node()
without checking if the device's node id is NUMA_NO_NODE, there is
global-out-of-bounds detected by KASAN.

From the discussion [1], NUMA_NO_NODE really means no node affinity,
which also means all cpus should be usable. So the cpumask_of_node()
should always return all cpus online when user passes the node id as
NUMA_NO_NODE, just like similar semantic that page allocator handles
NUMA_NO_NODE.

But we cannot really copy the page allocator logic. Simply because the
page allocator doesn't enforce the near node affinity. It just picks it
up as a preferred node but then it is free to fallback to any other numa
node. This is not the case here and node_to_cpumask_map will only restrict
to the particular node's cpus which would have really non deterministic
behavior depending on where the code is executed. So in fact we really
want to return cpu_online_mask for NUMA_NO_NODE.

Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
which should be identical with cpu_online_mask when those arches do not
support cpu hotplug, this patch also changes them to return cpu_online_mask
in order to be consistent and use NUMA_NO_NODE instead of "-1".

Also there is a debugging version of node_to_cpumask_map() for x86 and
arm64, which is only used when CONFIG_DEBUG_PER_CPU_MAPS is defined, this
patch changes it to handle NUMA_NO_NODE as normal node_to_cpumask_map().

[1] https://lore.kernel.org/patchwork/patch/1125789/
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
---
V5: Drop unsigned "fix" change for x86/arm64, and change comment log
    according to Michal's comment.
V4: Have all these changes in a single patch.
V3: Change to only handle NUMA_NO_NODE, and return cpu_online_mask
    for NUMA_NO_NODE case, and change the commit log to better justify
    the change.
V2: make the node id checking change to other arches too.
---
 arch/alpha/include/asm/topology.h                | 2 +-
 arch/arm64/include/asm/numa.h                    | 3 +++
 arch/arm64/mm/numa.c                             | 3 +++
 arch/mips/include/asm/mach-ip27/topology.h       | 4 ++--
 arch/mips/include/asm/mach-loongson64/topology.h | 4 +++-
 arch/powerpc/include/asm/topology.h              | 6 +++---
 arch/s390/include/asm/topology.h                 | 3 +++
 arch/sparc/include/asm/topology_64.h             | 6 +++---
 arch/x86/include/asm/topology.h                  | 3 +++
 arch/x86/mm/numa.c                               | 3 +++
 10 files changed, 27 insertions(+), 10 deletions(-)

Comments

Michael Ellerman Sept. 17, 2019, 5:28 a.m. UTC | #1
Yunsheng Lin <linyunsheng@huawei.com> writes:
> When passing the return value of dev_to_node() to cpumask_of_node()
> without checking if the device's node id is NUMA_NO_NODE, there is
> global-out-of-bounds detected by KASAN.
>
> From the discussion [1], NUMA_NO_NODE really means no node affinity,
> which also means all cpus should be usable. So the cpumask_of_node()
> should always return all cpus online when user passes the node id as
> NUMA_NO_NODE, just like similar semantic that page allocator handles
> NUMA_NO_NODE.
>
> But we cannot really copy the page allocator logic. Simply because the
> page allocator doesn't enforce the near node affinity. It just picks it
> up as a preferred node but then it is free to fallback to any other numa
> node. This is not the case here and node_to_cpumask_map will only restrict
> to the particular node's cpus which would have really non deterministic
> behavior depending on where the code is executed. So in fact we really
> want to return cpu_online_mask for NUMA_NO_NODE.
>
> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
> which should be identical with cpu_online_mask when those arches do not
> support cpu hotplug, this patch also changes them to return cpu_online_mask
> in order to be consistent and use NUMA_NO_NODE instead of "-1".

Except some of those arches *do* support CPU hotplug, powerpc and sparc
at least. So switching from cpu_all_mask to cpu_online_mask is a
meaningful change.

That doesn't mean it's wrong, but you need to explain why it's the right
change.


> Also there is a debugging version of node_to_cpumask_map() for x86 and
> arm64, which is only used when CONFIG_DEBUG_PER_CPU_MAPS is defined, this
> patch changes it to handle NUMA_NO_NODE as normal node_to_cpumask_map().
>
> [1] https://lore.kernel.org/patchwork/patch/1125789/
> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> Suggested-by: Michal Hocko <mhocko@kernel.org>
> Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> V5: Drop unsigned "fix" change for x86/arm64, and change comment log
>     according to Michal's comment.
> V4: Have all these changes in a single patch.

This makes it much harder to get the patch merged, you basically have to
get Andrew Morton to merge it now. Sending individual patches for each
arch means each arch maintainer can merge them separately.

cheers

> V3: Change to only handle NUMA_NO_NODE, and return cpu_online_mask
>     for NUMA_NO_NODE case, and change the commit log to better justify
>     the change.
> V2: make the node id checking change to other arches too.
> ---
>  arch/alpha/include/asm/topology.h                | 2 +-
>  arch/arm64/include/asm/numa.h                    | 3 +++
>  arch/arm64/mm/numa.c                             | 3 +++
>  arch/mips/include/asm/mach-ip27/topology.h       | 4 ++--
>  arch/mips/include/asm/mach-loongson64/topology.h | 4 +++-
>  arch/powerpc/include/asm/topology.h              | 6 +++---
>  arch/s390/include/asm/topology.h                 | 3 +++
>  arch/sparc/include/asm/topology_64.h             | 6 +++---
>  arch/x86/include/asm/topology.h                  | 3 +++
>  arch/x86/mm/numa.c                               | 3 +++
>  10 files changed, 27 insertions(+), 10 deletions(-)
>
> diff --git a/arch/alpha/include/asm/topology.h b/arch/alpha/include/asm/topology.h
> index 5a77a40..836c9e2 100644
> --- a/arch/alpha/include/asm/topology.h
> +++ b/arch/alpha/include/asm/topology.h
> @@ -31,7 +31,7 @@ static const struct cpumask *cpumask_of_node(int node)
>  	int cpu;
>  
>  	if (node == NUMA_NO_NODE)
> -		return cpu_all_mask;
> +		return cpu_online_mask;
>  
>  	cpumask_clear(&node_to_cpumask_map[node]);
>  
> diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h
> index 626ad01..c8a4b31 100644
> --- a/arch/arm64/include/asm/numa.h
> +++ b/arch/arm64/include/asm/numa.h
> @@ -25,6 +25,9 @@ const struct cpumask *cpumask_of_node(int node);
>  /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
>  static inline const struct cpumask *cpumask_of_node(int node)
>  {
> +	if (node == NUMA_NO_NODE)
> +		return cpu_online_mask;
> +
>  	return node_to_cpumask_map[node];
>  }
>  #endif
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index 4f241cc..f57202d 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -46,6 +46,9 @@ EXPORT_SYMBOL(node_to_cpumask_map);
>   */
>  const struct cpumask *cpumask_of_node(int node)
>  {
> +	if (node == NUMA_NO_NODE)
> +		return cpu_online_mask;
> +
>  	if (WARN_ON(node >= nr_node_ids))
>  		return cpu_none_mask;
>  
> diff --git a/arch/mips/include/asm/mach-ip27/topology.h b/arch/mips/include/asm/mach-ip27/topology.h
> index 965f079..04505e6 100644
> --- a/arch/mips/include/asm/mach-ip27/topology.h
> +++ b/arch/mips/include/asm/mach-ip27/topology.h
> @@ -15,8 +15,8 @@ struct cpuinfo_ip27 {
>  extern struct cpuinfo_ip27 sn_cpu_info[NR_CPUS];
>  
>  #define cpu_to_node(cpu)	(sn_cpu_info[(cpu)].p_nodeid)
> -#define cpumask_of_node(node)	((node) == -1 ?				\
> -				 cpu_all_mask :				\
> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
> +				 cpu_online_mask :			\
>  				 &hub_data(node)->h_cpus)
>  struct pci_bus;
>  extern int pcibus_to_node(struct pci_bus *);
> diff --git a/arch/mips/include/asm/mach-loongson64/topology.h b/arch/mips/include/asm/mach-loongson64/topology.h
> index 7ff819a..e78daa6 100644
> --- a/arch/mips/include/asm/mach-loongson64/topology.h
> +++ b/arch/mips/include/asm/mach-loongson64/topology.h
> @@ -5,7 +5,9 @@
>  #ifdef CONFIG_NUMA
>  
>  #define cpu_to_node(cpu)	(cpu_logical_map(cpu) >> 2)
> -#define cpumask_of_node(node)	(&__node_data[(node)]->cpumask)
> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
> +				 cpu_online_mask :			\
> +				 &__node_data[(node)]->cpumask)
>  
>  struct pci_bus;
>  extern int pcibus_to_node(struct pci_bus *);
> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
> index 2f7e1ea..309f847 100644
> --- a/arch/powerpc/include/asm/topology.h
> +++ b/arch/powerpc/include/asm/topology.h
> @@ -17,9 +17,9 @@ struct device_node;
>  
>  #include <asm/mmzone.h>
>  
> -#define cpumask_of_node(node) ((node) == -1 ?				\
> -			       cpu_all_mask :				\
> -			       node_to_cpumask_map[node])
> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
> +				 cpu_online_mask :			\
> +				 node_to_cpumask_map[node])
>  
>  struct pci_bus;
>  #ifdef CONFIG_PCI
> diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
> index cca406f..1bd2e73 100644
> --- a/arch/s390/include/asm/topology.h
> +++ b/arch/s390/include/asm/topology.h
> @@ -78,6 +78,9 @@ static inline int cpu_to_node(int cpu)
>  #define cpumask_of_node cpumask_of_node
>  static inline const struct cpumask *cpumask_of_node(int node)
>  {
> +	if (node == NUMA_NO_NODE)
> +		return cpu_online_mask;
> +
>  	return &node_to_cpumask_map[node];
>  }
>  
> diff --git a/arch/sparc/include/asm/topology_64.h b/arch/sparc/include/asm/topology_64.h
> index 34c628a..8c29357 100644
> --- a/arch/sparc/include/asm/topology_64.h
> +++ b/arch/sparc/include/asm/topology_64.h
> @@ -11,9 +11,9 @@ static inline int cpu_to_node(int cpu)
>  	return numa_cpu_lookup_table[cpu];
>  }
>  
> -#define cpumask_of_node(node) ((node) == -1 ?				\
> -			       cpu_all_mask :				\
> -			       &numa_cpumask_lookup_table[node])
> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
> +				 cpu_online_mask :			\
> +				 &numa_cpumask_lookup_table[node])
>  
>  struct pci_bus;
>  #ifdef CONFIG_PCI
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index 4b14d23..7fa82e1 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -69,6 +69,9 @@ extern const struct cpumask *cpumask_of_node(int node);
>  /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
>  static inline const struct cpumask *cpumask_of_node(int node)
>  {
> +	if (node == NUMA_NO_NODE)
> +		return cpu_online_mask;
> +
>  	return node_to_cpumask_map[node];
>  }
>  #endif
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index e6dad60..84b28ef 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -861,6 +861,9 @@ void numa_remove_cpu(int cpu)
>   */
>  const struct cpumask *cpumask_of_node(int node)
>  {
> +	if (node == NUMA_NO_NODE)
> +		return cpu_online_mask;
> +
>  	if (node >= nr_node_ids) {
>  		printk(KERN_WARNING
>  			"cpumask_of_node(%d): node > nr_node_ids(%u)\n",
> -- 
> 2.8.1
Yunsheng Lin Sept. 17, 2019, 6:20 a.m. UTC | #2
On 2019/9/17 13:28, Michael Ellerman wrote:
> Yunsheng Lin <linyunsheng@huawei.com> writes:
>> When passing the return value of dev_to_node() to cpumask_of_node()
>> without checking if the device's node id is NUMA_NO_NODE, there is
>> global-out-of-bounds detected by KASAN.
>>
>> From the discussion [1], NUMA_NO_NODE really means no node affinity,
>> which also means all cpus should be usable. So the cpumask_of_node()
>> should always return all cpus online when user passes the node id as
>> NUMA_NO_NODE, just like similar semantic that page allocator handles
>> NUMA_NO_NODE.
>>
>> But we cannot really copy the page allocator logic. Simply because the
>> page allocator doesn't enforce the near node affinity. It just picks it
>> up as a preferred node but then it is free to fallback to any other numa
>> node. This is not the case here and node_to_cpumask_map will only restrict
>> to the particular node's cpus which would have really non deterministic
>> behavior depending on where the code is executed. So in fact we really
>> want to return cpu_online_mask for NUMA_NO_NODE.
>>
>> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
>> which should be identical with cpu_online_mask when those arches do not
>> support cpu hotplug, this patch also changes them to return cpu_online_mask
>> in order to be consistent and use NUMA_NO_NODE instead of "-1".
> 
> Except some of those arches *do* support CPU hotplug, powerpc and sparc
> at least. So switching from cpu_all_mask to cpu_online_mask is a
> meaningful change.

Yes, thanks for pointing out.

> 
> That doesn't mean it's wrong, but you need to explain why it's the right
> change.

How about adding the below to the commit log:
Even if some of the arches do support CPU hotplug, it does not make sense
to return the cpu that has been hotplugged.

Any suggestion?

> 
> 
>> Also there is a debugging version of node_to_cpumask_map() for x86 and
>> arm64, which is only used when CONFIG_DEBUG_PER_CPU_MAPS is defined, this
>> patch changes it to handle NUMA_NO_NODE as normal node_to_cpumask_map().
>>
>> [1] https://lore.kernel.org/patchwork/patch/1125789/
>> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
>> Suggested-by: Michal Hocko <mhocko@kernel.org>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> ---
>> V5: Drop unsigned "fix" change for x86/arm64, and change comment log
>>     according to Michal's comment.
>> V4: Have all these changes in a single patch.
> 
> This makes it much harder to get the patch merged, you basically have to
> get Andrew Morton to merge it now. Sending individual patches for each
> arch means each arch maintainer can merge them separately.

I am new to the arch change here, and not sure which is the best way to get
the multi-arches change merged.

Do you think it is better to resend this as individual patches for each arch
after megre window?

thanks for reviewing.

> 
> cheers
> 
>> V3: Change to only handle NUMA_NO_NODE, and return cpu_online_mask
>>     for NUMA_NO_NODE case, and change the commit log to better justify
>>     the change.
>> V2: make the node id checking change to other arches too.
>> ---
>>  arch/alpha/include/asm/topology.h                | 2 +-
>>  arch/arm64/include/asm/numa.h                    | 3 +++
>>  arch/arm64/mm/numa.c                             | 3 +++
>>  arch/mips/include/asm/mach-ip27/topology.h       | 4 ++--
>>  arch/mips/include/asm/mach-loongson64/topology.h | 4 +++-
>>  arch/powerpc/include/asm/topology.h              | 6 +++---
>>  arch/s390/include/asm/topology.h                 | 3 +++
>>  arch/sparc/include/asm/topology_64.h             | 6 +++---
>>  arch/x86/include/asm/topology.h                  | 3 +++
>>  arch/x86/mm/numa.c                               | 3 +++
>>  10 files changed, 27 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/alpha/include/asm/topology.h b/arch/alpha/include/asm/topology.h
>> index 5a77a40..836c9e2 100644
>> --- a/arch/alpha/include/asm/topology.h
>> +++ b/arch/alpha/include/asm/topology.h
>> @@ -31,7 +31,7 @@ static const struct cpumask *cpumask_of_node(int node)
>>  	int cpu;
>>  
>>  	if (node == NUMA_NO_NODE)
>> -		return cpu_all_mask;
>> +		return cpu_online_mask;
>>  
>>  	cpumask_clear(&node_to_cpumask_map[node]);
>>  
>> diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h
>> index 626ad01..c8a4b31 100644
>> --- a/arch/arm64/include/asm/numa.h
>> +++ b/arch/arm64/include/asm/numa.h
>> @@ -25,6 +25,9 @@ const struct cpumask *cpumask_of_node(int node);
>>  /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
>>  static inline const struct cpumask *cpumask_of_node(int node)
>>  {
>> +	if (node == NUMA_NO_NODE)
>> +		return cpu_online_mask;
>> +
>>  	return node_to_cpumask_map[node];
>>  }
>>  #endif
>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>> index 4f241cc..f57202d 100644
>> --- a/arch/arm64/mm/numa.c
>> +++ b/arch/arm64/mm/numa.c
>> @@ -46,6 +46,9 @@ EXPORT_SYMBOL(node_to_cpumask_map);
>>   */
>>  const struct cpumask *cpumask_of_node(int node)
>>  {
>> +	if (node == NUMA_NO_NODE)
>> +		return cpu_online_mask;
>> +
>>  	if (WARN_ON(node >= nr_node_ids))
>>  		return cpu_none_mask;
>>  
>> diff --git a/arch/mips/include/asm/mach-ip27/topology.h b/arch/mips/include/asm/mach-ip27/topology.h
>> index 965f079..04505e6 100644
>> --- a/arch/mips/include/asm/mach-ip27/topology.h
>> +++ b/arch/mips/include/asm/mach-ip27/topology.h
>> @@ -15,8 +15,8 @@ struct cpuinfo_ip27 {
>>  extern struct cpuinfo_ip27 sn_cpu_info[NR_CPUS];
>>  
>>  #define cpu_to_node(cpu)	(sn_cpu_info[(cpu)].p_nodeid)
>> -#define cpumask_of_node(node)	((node) == -1 ?				\
>> -				 cpu_all_mask :				\
>> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
>> +				 cpu_online_mask :			\
>>  				 &hub_data(node)->h_cpus)
>>  struct pci_bus;
>>  extern int pcibus_to_node(struct pci_bus *);
>> diff --git a/arch/mips/include/asm/mach-loongson64/topology.h b/arch/mips/include/asm/mach-loongson64/topology.h
>> index 7ff819a..e78daa6 100644
>> --- a/arch/mips/include/asm/mach-loongson64/topology.h
>> +++ b/arch/mips/include/asm/mach-loongson64/topology.h
>> @@ -5,7 +5,9 @@
>>  #ifdef CONFIG_NUMA
>>  
>>  #define cpu_to_node(cpu)	(cpu_logical_map(cpu) >> 2)
>> -#define cpumask_of_node(node)	(&__node_data[(node)]->cpumask)
>> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
>> +				 cpu_online_mask :			\
>> +				 &__node_data[(node)]->cpumask)
>>  
>>  struct pci_bus;
>>  extern int pcibus_to_node(struct pci_bus *);
>> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
>> index 2f7e1ea..309f847 100644
>> --- a/arch/powerpc/include/asm/topology.h
>> +++ b/arch/powerpc/include/asm/topology.h
>> @@ -17,9 +17,9 @@ struct device_node;
>>  
>>  #include <asm/mmzone.h>
>>  
>> -#define cpumask_of_node(node) ((node) == -1 ?				\
>> -			       cpu_all_mask :				\
>> -			       node_to_cpumask_map[node])
>> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
>> +				 cpu_online_mask :			\
>> +				 node_to_cpumask_map[node])
>>  
>>  struct pci_bus;
>>  #ifdef CONFIG_PCI
>> diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
>> index cca406f..1bd2e73 100644
>> --- a/arch/s390/include/asm/topology.h
>> +++ b/arch/s390/include/asm/topology.h
>> @@ -78,6 +78,9 @@ static inline int cpu_to_node(int cpu)
>>  #define cpumask_of_node cpumask_of_node
>>  static inline const struct cpumask *cpumask_of_node(int node)
>>  {
>> +	if (node == NUMA_NO_NODE)
>> +		return cpu_online_mask;
>> +
>>  	return &node_to_cpumask_map[node];
>>  }
>>  
>> diff --git a/arch/sparc/include/asm/topology_64.h b/arch/sparc/include/asm/topology_64.h
>> index 34c628a..8c29357 100644
>> --- a/arch/sparc/include/asm/topology_64.h
>> +++ b/arch/sparc/include/asm/topology_64.h
>> @@ -11,9 +11,9 @@ static inline int cpu_to_node(int cpu)
>>  	return numa_cpu_lookup_table[cpu];
>>  }
>>  
>> -#define cpumask_of_node(node) ((node) == -1 ?				\
>> -			       cpu_all_mask :				\
>> -			       &numa_cpumask_lookup_table[node])
>> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
>> +				 cpu_online_mask :			\
>> +				 &numa_cpumask_lookup_table[node])
>>  
>>  struct pci_bus;
>>  #ifdef CONFIG_PCI
>> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
>> index 4b14d23..7fa82e1 100644
>> --- a/arch/x86/include/asm/topology.h
>> +++ b/arch/x86/include/asm/topology.h
>> @@ -69,6 +69,9 @@ extern const struct cpumask *cpumask_of_node(int node);
>>  /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
>>  static inline const struct cpumask *cpumask_of_node(int node)
>>  {
>> +	if (node == NUMA_NO_NODE)
>> +		return cpu_online_mask;
>> +
>>  	return node_to_cpumask_map[node];
>>  }
>>  #endif
>> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
>> index e6dad60..84b28ef 100644
>> --- a/arch/x86/mm/numa.c
>> +++ b/arch/x86/mm/numa.c
>> @@ -861,6 +861,9 @@ void numa_remove_cpu(int cpu)
>>   */
>>  const struct cpumask *cpumask_of_node(int node)
>>  {
>> +	if (node == NUMA_NO_NODE)
>> +		return cpu_online_mask;
>> +
>>  	if (node >= nr_node_ids) {
>>  		printk(KERN_WARNING
>>  			"cpumask_of_node(%d): node > nr_node_ids(%u)\n",
>> -- 
>> 2.8.1
> 
> .
>
Michal Hocko Sept. 17, 2019, 9:36 a.m. UTC | #3
On Tue 17-09-19 14:20:11, Yunsheng Lin wrote:
> On 2019/9/17 13:28, Michael Ellerman wrote:
> > Yunsheng Lin <linyunsheng@huawei.com> writes:
[...]
> >> But we cannot really copy the page allocator logic. Simply because the
> >> page allocator doesn't enforce the near node affinity. It just picks it
> >> up as a preferred node but then it is free to fallback to any other numa
> >> node. This is not the case here and node_to_cpumask_map will only restrict
> >> to the particular node's cpus which would have really non deterministic
> >> behavior depending on where the code is executed. So in fact we really
> >> want to return cpu_online_mask for NUMA_NO_NODE.
> >>
> >> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
> >> which should be identical with cpu_online_mask when those arches do not
> >> support cpu hotplug, this patch also changes them to return cpu_online_mask
> >> in order to be consistent and use NUMA_NO_NODE instead of "-1".
> > 
> > Except some of those arches *do* support CPU hotplug, powerpc and sparc
> > at least. So switching from cpu_all_mask to cpu_online_mask is a
> > meaningful change.
> 
> Yes, thanks for pointing out.
> 
> > 
> > That doesn't mean it's wrong, but you need to explain why it's the right
> > change.
> 
> How about adding the below to the commit log:
> Even if some of the arches do support CPU hotplug, it does not make sense
> to return the cpu that has been hotplugged.
>
> Any suggestion?

Again, for the third time, I believe. Make it a separate patch please.
There is absolutely no reason to conflate those two things.
Yunsheng Lin Sept. 17, 2019, 9:53 a.m. UTC | #4
On 2019/9/17 17:36, Michal Hocko wrote:
> On Tue 17-09-19 14:20:11, Yunsheng Lin wrote:
>> On 2019/9/17 13:28, Michael Ellerman wrote:
>>> Yunsheng Lin <linyunsheng@huawei.com> writes:
> [...]
>>>> But we cannot really copy the page allocator logic. Simply because the
>>>> page allocator doesn't enforce the near node affinity. It just picks it
>>>> up as a preferred node but then it is free to fallback to any other numa
>>>> node. This is not the case here and node_to_cpumask_map will only restrict
>>>> to the particular node's cpus which would have really non deterministic
>>>> behavior depending on where the code is executed. So in fact we really
>>>> want to return cpu_online_mask for NUMA_NO_NODE.
>>>>
>>>> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
>>>> which should be identical with cpu_online_mask when those arches do not
>>>> support cpu hotplug, this patch also changes them to return cpu_online_mask
>>>> in order to be consistent and use NUMA_NO_NODE instead of "-1".
>>>
>>> Except some of those arches *do* support CPU hotplug, powerpc and sparc
>>> at least. So switching from cpu_all_mask to cpu_online_mask is a
>>> meaningful change.
>>
>> Yes, thanks for pointing out.
>>
>>>
>>> That doesn't mean it's wrong, but you need to explain why it's the right
>>> change.
>>
>> How about adding the below to the commit log:
>> Even if some of the arches do support CPU hotplug, it does not make sense
>> to return the cpu that has been hotplugged.
>>
>> Any suggestion?
> 
> Again, for the third time, I believe. Make it a separate patch please.
> There is absolutely no reason to conflate those two things.

Ok, thanks.
Will make the cpu_all_mask -> cpu_online_mask change a separate patch.

Also, do you think it is better to resend this as individual patches for each arch
or have all these changes in a single patch? I am not sure which is the common
practice for a multi-arches changes like this.

>
Michal Hocko Sept. 17, 2019, 10:08 a.m. UTC | #5
On Tue 17-09-19 17:53:57, Yunsheng Lin wrote:
> On 2019/9/17 17:36, Michal Hocko wrote:
> > On Tue 17-09-19 14:20:11, Yunsheng Lin wrote:
> >> On 2019/9/17 13:28, Michael Ellerman wrote:
> >>> Yunsheng Lin <linyunsheng@huawei.com> writes:
> > [...]
> >>>> But we cannot really copy the page allocator logic. Simply because the
> >>>> page allocator doesn't enforce the near node affinity. It just picks it
> >>>> up as a preferred node but then it is free to fallback to any other numa
> >>>> node. This is not the case here and node_to_cpumask_map will only restrict
> >>>> to the particular node's cpus which would have really non deterministic
> >>>> behavior depending on where the code is executed. So in fact we really
> >>>> want to return cpu_online_mask for NUMA_NO_NODE.
> >>>>
> >>>> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
> >>>> which should be identical with cpu_online_mask when those arches do not
> >>>> support cpu hotplug, this patch also changes them to return cpu_online_mask
> >>>> in order to be consistent and use NUMA_NO_NODE instead of "-1".
> >>>
> >>> Except some of those arches *do* support CPU hotplug, powerpc and sparc
> >>> at least. So switching from cpu_all_mask to cpu_online_mask is a
> >>> meaningful change.
> >>
> >> Yes, thanks for pointing out.
> >>
> >>>
> >>> That doesn't mean it's wrong, but you need to explain why it's the right
> >>> change.
> >>
> >> How about adding the below to the commit log:
> >> Even if some of the arches do support CPU hotplug, it does not make sense
> >> to return the cpu that has been hotplugged.
> >>
> >> Any suggestion?
> > 
> > Again, for the third time, I believe. Make it a separate patch please.
> > There is absolutely no reason to conflate those two things.
> 
> Ok, thanks.
> Will make the cpu_all_mask -> cpu_online_mask change a separate patch.

Thanks. This really needs per arch maintainer to check closely.

> Also, do you think it is better to resend this as individual patches for each arch
> or have all these changes in a single patch? I am not sure which is the common
> practice for a multi-arches changes like this.

It really depends on arch maintainers. Both approaches have some pros
and cons. A single patch is more compact and and parts are not going to
get lost in noise. They might generate some conflicts with parallel
changes. I suspect a conflict risk is quite low in this code considering
from a recent activity. A follow up arch specific patch would have to be
routed via Andrew as well.

If Andrew is ok routing it through his tree and none of the arch
maintainers is opposed then I would go with a single patch.
Yunsheng Lin Sept. 17, 2019, 11:36 a.m. UTC | #6
On 2019/9/17 18:08, Michal Hocko wrote:
> On Tue 17-09-19 17:53:57, Yunsheng Lin wrote:
>> On 2019/9/17 17:36, Michal Hocko wrote:
>>> On Tue 17-09-19 14:20:11, Yunsheng Lin wrote:
>>>> On 2019/9/17 13:28, Michael Ellerman wrote:
>>>>> Yunsheng Lin <linyunsheng@huawei.com> writes:
>>> [...]
>>>>>> But we cannot really copy the page allocator logic. Simply because the
>>>>>> page allocator doesn't enforce the near node affinity. It just picks it
>>>>>> up as a preferred node but then it is free to fallback to any other numa
>>>>>> node. This is not the case here and node_to_cpumask_map will only restrict
>>>>>> to the particular node's cpus which would have really non deterministic
>>>>>> behavior depending on where the code is executed. So in fact we really
>>>>>> want to return cpu_online_mask for NUMA_NO_NODE.
>>>>>>
>>>>>> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask,
>>>>>> which should be identical with cpu_online_mask when those arches do not
>>>>>> support cpu hotplug, this patch also changes them to return cpu_online_mask
>>>>>> in order to be consistent and use NUMA_NO_NODE instead of "-1".
>>>>>
>>>>> Except some of those arches *do* support CPU hotplug, powerpc and sparc
>>>>> at least. So switching from cpu_all_mask to cpu_online_mask is a
>>>>> meaningful change.
>>>>
>>>> Yes, thanks for pointing out.
>>>>
>>>>>
>>>>> That doesn't mean it's wrong, but you need to explain why it's the right
>>>>> change.
>>>>
>>>> How about adding the below to the commit log:
>>>> Even if some of the arches do support CPU hotplug, it does not make sense
>>>> to return the cpu that has been hotplugged.
>>>>
>>>> Any suggestion?
>>>
>>> Again, for the third time, I believe. Make it a separate patch please.
>>> There is absolutely no reason to conflate those two things.
>>
>> Ok, thanks.
>> Will make the cpu_all_mask -> cpu_online_mask change a separate patch.
> 
> Thanks. This really needs per arch maintainer to check closely.
> 
>> Also, do you think it is better to resend this as individual patches for each arch
>> or have all these changes in a single patch? I am not sure which is the common
>> practice for a multi-arches changes like this.
> 
> It really depends on arch maintainers. Both approaches have some pros
> and cons. A single patch is more compact and and parts are not going to
> get lost in noise. They might generate some conflicts with parallel
> changes. I suspect a conflict risk is quite low in this code considering
> from a recent activity. A follow up arch specific patch would have to be
> routed via Andrew as well.
> 
> If Andrew is ok routing it through his tree and none of the arch
> maintainers is opposed then I would go with a single patch.

Ok, I will try a single patch for NUMA_NO_NODE aware change first.
"cpu_all_mask -> cpu_online_mask" change seems a little controversial,
and may need deeper investigation.


>

Patch
diff mbox series

diff --git a/arch/alpha/include/asm/topology.h b/arch/alpha/include/asm/topology.h
index 5a77a40..836c9e2 100644
--- a/arch/alpha/include/asm/topology.h
+++ b/arch/alpha/include/asm/topology.h
@@ -31,7 +31,7 @@  static const struct cpumask *cpumask_of_node(int node)
 	int cpu;
 
 	if (node == NUMA_NO_NODE)
-		return cpu_all_mask;
+		return cpu_online_mask;
 
 	cpumask_clear(&node_to_cpumask_map[node]);
 
diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h
index 626ad01..c8a4b31 100644
--- a/arch/arm64/include/asm/numa.h
+++ b/arch/arm64/include/asm/numa.h
@@ -25,6 +25,9 @@  const struct cpumask *cpumask_of_node(int node);
 /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
 static inline const struct cpumask *cpumask_of_node(int node)
 {
+	if (node == NUMA_NO_NODE)
+		return cpu_online_mask;
+
 	return node_to_cpumask_map[node];
 }
 #endif
diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 4f241cc..f57202d 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -46,6 +46,9 @@  EXPORT_SYMBOL(node_to_cpumask_map);
  */
 const struct cpumask *cpumask_of_node(int node)
 {
+	if (node == NUMA_NO_NODE)
+		return cpu_online_mask;
+
 	if (WARN_ON(node >= nr_node_ids))
 		return cpu_none_mask;
 
diff --git a/arch/mips/include/asm/mach-ip27/topology.h b/arch/mips/include/asm/mach-ip27/topology.h
index 965f079..04505e6 100644
--- a/arch/mips/include/asm/mach-ip27/topology.h
+++ b/arch/mips/include/asm/mach-ip27/topology.h
@@ -15,8 +15,8 @@  struct cpuinfo_ip27 {
 extern struct cpuinfo_ip27 sn_cpu_info[NR_CPUS];
 
 #define cpu_to_node(cpu)	(sn_cpu_info[(cpu)].p_nodeid)
-#define cpumask_of_node(node)	((node) == -1 ?				\
-				 cpu_all_mask :				\
+#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
+				 cpu_online_mask :			\
 				 &hub_data(node)->h_cpus)
 struct pci_bus;
 extern int pcibus_to_node(struct pci_bus *);
diff --git a/arch/mips/include/asm/mach-loongson64/topology.h b/arch/mips/include/asm/mach-loongson64/topology.h
index 7ff819a..e78daa6 100644
--- a/arch/mips/include/asm/mach-loongson64/topology.h
+++ b/arch/mips/include/asm/mach-loongson64/topology.h
@@ -5,7 +5,9 @@ 
 #ifdef CONFIG_NUMA
 
 #define cpu_to_node(cpu)	(cpu_logical_map(cpu) >> 2)
-#define cpumask_of_node(node)	(&__node_data[(node)]->cpumask)
+#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
+				 cpu_online_mask :			\
+				 &__node_data[(node)]->cpumask)
 
 struct pci_bus;
 extern int pcibus_to_node(struct pci_bus *);
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index 2f7e1ea..309f847 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -17,9 +17,9 @@  struct device_node;
 
 #include <asm/mmzone.h>
 
-#define cpumask_of_node(node) ((node) == -1 ?				\
-			       cpu_all_mask :				\
-			       node_to_cpumask_map[node])
+#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
+				 cpu_online_mask :			\
+				 node_to_cpumask_map[node])
 
 struct pci_bus;
 #ifdef CONFIG_PCI
diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index cca406f..1bd2e73 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h
@@ -78,6 +78,9 @@  static inline int cpu_to_node(int cpu)
 #define cpumask_of_node cpumask_of_node
 static inline const struct cpumask *cpumask_of_node(int node)
 {
+	if (node == NUMA_NO_NODE)
+		return cpu_online_mask;
+
 	return &node_to_cpumask_map[node];
 }
 
diff --git a/arch/sparc/include/asm/topology_64.h b/arch/sparc/include/asm/topology_64.h
index 34c628a..8c29357 100644
--- a/arch/sparc/include/asm/topology_64.h
+++ b/arch/sparc/include/asm/topology_64.h
@@ -11,9 +11,9 @@  static inline int cpu_to_node(int cpu)
 	return numa_cpu_lookup_table[cpu];
 }
 
-#define cpumask_of_node(node) ((node) == -1 ?				\
-			       cpu_all_mask :				\
-			       &numa_cpumask_lookup_table[node])
+#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
+				 cpu_online_mask :			\
+				 &numa_cpumask_lookup_table[node])
 
 struct pci_bus;
 #ifdef CONFIG_PCI
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 4b14d23..7fa82e1 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -69,6 +69,9 @@  extern const struct cpumask *cpumask_of_node(int node);
 /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
 static inline const struct cpumask *cpumask_of_node(int node)
 {
+	if (node == NUMA_NO_NODE)
+		return cpu_online_mask;
+
 	return node_to_cpumask_map[node];
 }
 #endif
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index e6dad60..84b28ef 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -861,6 +861,9 @@  void numa_remove_cpu(int cpu)
  */
 const struct cpumask *cpumask_of_node(int node)
 {
+	if (node == NUMA_NO_NODE)
+		return cpu_online_mask;
+
 	if (node >= nr_node_ids) {
 		printk(KERN_WARNING
 			"cpumask_of_node(%d): node > nr_node_ids(%u)\n",