Re: [PATCH 3/3] mm: use vmem_altmap code without CONFIG_ZONE_DEVICE

[David Hildenbrand <david@redhat.com>]

On 20.11.23 08:23, Sumanth Korikkar wrote:
> vmem_altmap_free() and vmem_altmap_offset() could be utlized without
> CONFIG_ZONE_DEVICE enabled. For example,
> mm/memory_hotplug.c:__add_pages() relies on that.  The altmap is no
> longer restricted to ZONE_DEVICE handling, but instead depends on
> CONFIG_SPARSEMEM_VMEMMAP.
> 
> When CONFIG_SPARSEMEM_VMEMMAP is disabled, these functions are defined
> as inline stubs, ensuring compatibility with configurations that do not
> use sparsemem vmemmap. Without it, lkp reported the following:
> 
> ld: arch/x86/mm/init_64.o: in function `remove_pagetable':
> init_64.c:(.meminit.text+0xfc7): undefined reference to
> `vmem_altmap_free'
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202311180545.VeyRXEDq-lkp@intel.com/
> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
> ---


[...]

>   
> +unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
> +{
> +	/* number of pfns from base where pfn_to_page() is valid */
> +	if (altmap)
> +		return altmap->reserve + altmap->free;
> +	return 0;
> +}
> +
> +void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
> +{
> +	altmap->alloc -= nr_pfns;
> +}

What speaks against just moving them to the header instead? They surely 
are tiny ...

-- 
Cheers,

David / dhildenb