+ spin_lock(&walk->mm->page_table_lock);
+ if (pmd_trans_huge(*pmd)) {
+ if (pmd_trans_splitting(*pmd)) {
+ spin_unlock(&walk->mm->page_table_lock);
+ wait_split_huge_page(vma->anon_vma, pmd);
+ } else {
+ for (; addr != end; addr += PAGE_SIZE) {
+ unsigned long offset;
+
+ offset = (addr & ~PAGEMAP_WALK_MASK) >>
+ PAGE_SHIFT;
+ pfn = thp_pmd_to_pagemap_entry(*pmd, offset);
+ err = add_to_pagemap(addr, pfn, pm);
+ if (err)
+ break;
+ }
+ spin_unlock(&walk->mm->page_table_lock);
+ return err;
+ }
+ } else {
+ spin_unlock(&walk->mm->page_table_lock);
+ }
+