want_pmd_share
if (want_pmd_share(vma, addr) && pud_none(READ_ONCE(*pudp)))
if (want_pmd_share(vma, addr) && pud_none(pudp_get(pud)))
bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr);
if (want_pmd_share(vma, addr) && pud_none(*pud))