Re: [PATCH 2/2] Revert "topology: add support for node_to_mem_node() to determine the fallback node"

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

* Vlastimil Babka <vbabka@suse.cz> [2020-03-20 12:55:33]:

> This reverts commit ad2c8144418c6a81cefe65379fd47bbe8344cef2.
> 
> The function node_to_mem_node() was introduced by that commit for use in SLUB
> on systems with memoryless nodes, but it turned out to be unreliable on some
> architectures/configurations and a simpler solution exists than fixing it up.
> 
> Thus the previous commit "mm, slub: prevent kmalloc_node crashes and memory
> leaks" removed the only user of node_to_mem_node() and we can revert the commit
> that introduced it.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
>  include/linux/topology.h | 17 -----------------
>  mm/page_alloc.c          |  1 -
>  2 files changed, 18 deletions(-)
> 
> diff --git a/include/linux/topology.h b/include/linux/topology.h
> index eb2fe6edd73c..608fa4aadf0e 100644
> --- a/include/linux/topology.h
> +++ b/include/linux/topology.h
> @@ -130,20 +130,11 @@ static inline int numa_node_id(void)
>   * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem().
>   */
>  DECLARE_PER_CPU(int, _numa_mem_);
> -extern int _node_numa_mem_[MAX_NUMNODES];
> 
>  #ifndef set_numa_mem
>  static inline void set_numa_mem(int node)
>  {
>  	this_cpu_write(_numa_mem_, node);
> -	_node_numa_mem_[numa_node_id()] = node;
> -}
> -#endif
> -
> -#ifndef node_to_mem_node
> -static inline int node_to_mem_node(int node)
> -{
> -	return _node_numa_mem_[node];
>  }
>  #endif
> 
> @@ -166,7 +157,6 @@ static inline int cpu_to_mem(int cpu)
>  static inline void set_cpu_numa_mem(int cpu, int node)
>  {
>  	per_cpu(_numa_mem_, cpu) = node;
> -	_node_numa_mem_[cpu_to_node(cpu)] = node;
>  }
>  #endif
> 
> @@ -180,13 +170,6 @@ static inline int numa_mem_id(void)
>  }
>  #endif
> 
> -#ifndef node_to_mem_node
> -static inline int node_to_mem_node(int node)
> -{
> -	return node;
> -}
> -#endif
> -
>  #ifndef cpu_to_mem
>  static inline int cpu_to_mem(int cpu)
>  {
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3c4eb750a199..6e7e9c1d6caa 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -95,7 +95,6 @@ DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
>   */
>  DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
>  EXPORT_PER_CPU_SYMBOL(_numa_mem_);
> -int _node_numa_mem_[MAX_NUMNODES];
>  #endif
> 
>  /* work_structs for global per-cpu drains */
> -- 
> 2.25.1
> 

-- 
Thanks and Regards
Srikar Dronamraju