[PATCH v6 4/7] mm/memory_hotplug: Support memmap_on_memory when memmap is not aligned to pageblocks

Michal Hocko mhocko at suse.com
Thu Jul 27 19:23:47 AEST 2023

On Thu 27-07-23 13:32:29, Aneesh Kumar K.V wrote:
> +	if (mode == MEMMAP_ON_MEMORY_FORCE) {
> +		unsigned long memmap_pages = memory_block_memmap_on_memory_pages();
> +
> +		pr_info_once("Memory hotplug will reserve %ld pages in each memory block\n",
> +			     memmap_pages - PFN_UP(memory_block_memmap_size()));
> +	}
> +	return 0;
> +}

Why should we print this only for the forced case? Isn't that
interesting for any on memory memmap? Also is this the above sufficient
on its own? the size depends on the block size and that can vary.
I think it would make more sense to print the block size and the vmemmap
reservation and for the force case also any wasted amount on top (if

Michal Hocko

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