Re: [PATCH] arch_numa: remove redundant nodemask clears in numa_init()

[Andrew Morton]

On Thu, 18 Jun 2026 01:39:19 +0900 Sang-Heon Jeon <ekffu200098@xxxxxxxxx> wrote:

> numa_init() clears numa_nodes_parsed, node_possible_map and
> node_online_map, then calls numa_memblks_init(), which clears the same
> nodemasks. Nothing uses them in between.
> 
> These clears have been redundant since commit 767507654c22 ("arch_numa:
> switch over to numa_memblks") made numa_init() use numa_memblks_init().
> 
> No functional change.
> 
> ...
>
> --- a/drivers/base/arch_numa.c
> +++ b/drivers/base/arch_numa.c
> @@ -231,10 +231,6 @@ static int __init numa_init(int (*init_func)(void))
>  {
>  	int ret;
>  
> -	nodes_clear(numa_nodes_parsed);
> -	nodes_clear(node_possible_map);
> -	nodes_clear(node_online_map);
> -
>  	ret = numa_memblks_init(init_func, /* memblock_force_top_down */ false);
>  	if (ret < 0)
>  		goto out_free_distance;

hm, OK, thanks.


A couple of driveby questions:

Are the other nodes_clear() calls are needed - aren't these things
zeroed when the kernel is loaded?


Also, 

#define node_possible_map 	node_states[N_POSSIBLE]

...

nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
	[N_POSSIBLE] = NODE_MASK_ALL,

why do we carefully initialize node_possible_map at compile-time then
zero it within __init code?