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

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.