Re: [PATCH v3 1/2] mm: migration: fix migration of huge PMD shared pages

[Michal Hocko]

On Tue 21-08-18 18:10:42, Mike Kravetz wrote:
[...]

OK, after burning myself when trying to be clever here it seems like
your proposed solution is indeed simpler.

> +bool huge_pmd_sharing_possible(struct vm_area_struct *vma,
> +				unsigned long *start, unsigned long *end)
> +{
> +	unsigned long check_addr = *start;
> +	bool ret = false;
> +
> +	if (!(vma->vm_flags & VM_MAYSHARE))
> +		return ret;
> +
> +	for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) {
> +		unsigned long a_start = check_addr & PUD_MASK;
> +		unsigned long a_end = a_start + PUD_SIZE;

I guess this should be rather in HPAGE_SIZE * PTRS_PER_PTE units as
huge_pmd_unshare does.
-- 
Michal Hocko
SUSE Labs