Re: [PATCH RFC 02/12] mm: add config option and per-NUMA node VMS support

["Christoph Lameter (Ampere)" <cl@xxxxxxxxxx>]

On Thu, 28 Dec 2023, artem.kuzin@xxxxxxxxxx wrote:

> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -626,7 +628,14 @@ struct mm_struct {
> 		unsigned long mmap_compat_legacy_base;
> #endif
> 		unsigned long task_size;	/* size of task vm space */
> -		pgd_t * pgd;
> +#ifndef CONFIG_KERNEL_REPLICATION
> +		pgd_t *pgd;
> +#else
> +		union {
> +			pgd_t *pgd;
> +			pgd_t *pgd_numa[MAX_NUMNODES];
> +		};
> +#endif


Hmmm... This is adding the pgd pointers for all mm_structs. But we 
only need the numa pgs pointers for the init_mm. Can this be a separate 
variable? There are some architecures with larger number of nodes.