Re: [PATCH v7] numa: make node_to_cpumask_map() NUMA_NO_NODE aware

[Michal Hocko]

On Wed 30-10-19 17:34:28, Yunsheng Lin wrote:
> 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.
> 
> 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://lkml.org/lkml/2019/9/11/66

Please do not use lkml.org links. They tend to break quite often.
Use http://lkml.kernel.org/r/$msg_id or lore.kernel.org

> Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
> Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> Acked-by: Paul Burton <paul.burton@xxxxxxxx> # MIPS bits
> ---
> V7: replace -1 with NUMA_NO_NODE for mips ip27 as suggested by Paul.
> V6: Drop the cpu_all_mask -> cpu_online_mask change for it seems a
>     little controversial, may need deeper investigation, and rebased
>     on the latest linux-next.
> 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/arm64/include/asm/numa.h                    | 3 +++
>  arch/arm64/mm/numa.c                             | 3 +++
>  arch/mips/include/asm/mach-ip27/topology.h       | 2 +-
>  arch/mips/include/asm/mach-loongson64/topology.h | 4 +++-
>  arch/s390/include/asm/topology.h                 | 3 +++
>  arch/x86/include/asm/topology.h                  | 3 +++
>  arch/x86/mm/numa.c                               | 3 +++
>  7 files changed, 19 insertions(+), 2 deletions(-)
> 
> 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 4decf16..5ae7eea 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..db293cf 100644
> --- a/arch/mips/include/asm/mach-ip27/topology.h
> +++ b/arch/mips/include/asm/mach-ip27/topology.h
> @@ -15,7 +15,7 @@ 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 ?				\
> +#define cpumask_of_node(node)	((node) == NUMA_NO_NODE ?		\
>  				 cpu_all_mask :				\
>  				 &hub_data(node)->h_cpus)
>  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/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/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 4123100e..9859acb 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 ((unsigned)node >= nr_node_ids) {
>  		printk(KERN_WARNING
>  			"cpumask_of_node(%d): (unsigned)node >= nr_node_ids(%u)\n",
> -- 
> 2.8.1

-- 
Michal Hocko
SUSE Labs