Re: [PATCHv6 11/17] mm/hugetlb: Remove fake head pages

[Usama Arif <usamaarif642@gmail.com>]

> +
>  int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
>  				       int node, unsigned long headsize)
>  {
> +	unsigned long maddr, len, tail_pfn;
> +	unsigned int order;
>  	pte_t *pte;
> -	unsigned long maddr;
> +
> +	len = end - addr;
> +	order = ilog2(len * sizeof(struct page) / PAGE_SIZE);


This doesnt work for ARM. For len = 32 (2MB contiguous-PTE hugetlb on arm64):
ilog2(32 * 64 / 65536) = ilog2(2048 / 65536) = ilog2(0) which is undefined.

Is order = ilog2(len / sizeof(struct page)) better?



> +	tail_pfn = vmemmap_get_tail(order, node);
> +	if (!tail_pfn)
> +		return -ENOMEM;
>  
>  	for (maddr = addr; maddr < addr + headsize; maddr += PAGE_SIZE) {
>  		pte = vmemmap_populate_address(maddr, node, NULL, -1, 0);
> @@ -398,8 +426,7 @@ int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
>  	/*
>  	 * Reuse the last page struct page mapped above for the rest.
>  	 */
> -	return vmemmap_populate_range(maddr, end, node, NULL,
> -					pte_pfn(ptep_get(pte)), 0);
> +	return vmemmap_populate_range(maddr, end, node, NULL, tail_pfn, 0);
>  }
>  
>  void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,