Re: [PATCH v3 6/7] mm/memblock: Use KSTATE instead of kho to preserve preserved_mem_table

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Sep 09, 2025 at 10:14:41PM +0200, Andrey Ryabinin wrote:
> +static int kstate_preserve_phys(struct kstate_stream *stream, void *obj,
> +				const struct kstate_field *field)
> +{
> +	struct reserve_mem_table *map = obj;
> +
> +	return kho_preserve_phys(map->start, map->size);
> +}
> +
> +struct kstate_description kstate_reserve_mem = {
> +	.name = "reserved_mem",
> +	.id = KSTATE_RESERVED_MEM_ID,
> +	.fields = (const struct kstate_field[]) {
> +		KSTATE_BASE_TYPE(name, struct reserve_mem_table,
> +				char[RESERVE_MEM_NAME_SIZE]),
> +		KSTATE_BASE_TYPE(start, struct reserve_mem_table, phys_addr_t),
> +		KSTATE_BASE_TYPE(size, struct reserve_mem_table, phys_addr_t),
> +		{
> +			.name = "phys_range",
> +			.flags = KS_CUSTOM,
> +			.save = kstate_preserve_phys,
> +		},
> +		KSTATE_END_OF_LIST(),
> +	},
> +};
>  
>  static int __init reserve_mem_init(void)
>  {
>  	int err;
> +	int i;
>  
>  	if (!kho_is_enabled() || !reserved_mem_count)
>  		return 0;
>  
> +	for (i = 0; i < reserved_mem_count; i++) {
> +		struct reserve_mem_table *map = &reserved_mem_table[i];
>  
> +		err = kstate_register(&kstate_reserve_mem,
> +				map, crc32(~0, map->name, RESERVE_MEM_NAME_SIZE));
> +		if (err)
> +			goto out;
>  	}

As I've said to the other proposals, this doesn't seem to be bringing
that much value compared to just using a normal struct:

	for (i = 0; i < reserved_mem_count; i++) {
		struct reserve_mem_table *map = &reserved_mem_table[i];
		struct khoser_reserve_mem_table abi_map = {.name = map->name. .start = map->start, .size = map->size};

		err = kho_preserve_phys(map->start, map->size);
		if (err)
		    return err; // Should unwind the other preservations!
		
		luo_preserve_key(luo_obj, map->name, &abi_map, sizeof(abi_map), VERSION_0);
 	}

Jason