ptep = pte_offset_map(pmd, addr);
- if (!is_swap_pte(*ptep)) {
- pte_unmap(ptep);
- goto out;
- }
+ /*
+ * Peek to check is_swap_pte() before taking ptlock? No, we
+ * can race mremap's move_ptes(), which skips anon_vma lock.
+ */
ptl = pte_lockptr(mm, pmd);
}