diff options
| -rw-r--r-- | mm/mremap.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index dda09e957a5d..5917feafe8cc 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -140,6 +140,7 @@ static int move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, { struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; + pmd_t dummy_pmdval; spinlock_t *old_ptl, *new_ptl; bool force_flush = false; unsigned long len = old_end - old_addr; @@ -175,7 +176,15 @@ static int move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, err = -EAGAIN; goto out; } - new_pte = pte_offset_map_nolock(mm, new_pmd, new_addr, &new_ptl); + /* + * Now new_pte is none, so hpage_collapse_scan_file() path can not find + * this by traversing file->f_mapping, so there is no concurrency with + * retract_page_tables(). In addition, we already hold the exclusive + * mmap_lock, so this new_pte page is stable, so there is no need to get + * pmdval and do pmd_same() check. + */ + new_pte = pte_offset_map_rw_nolock(mm, new_pmd, new_addr, &dummy_pmdval, + &new_ptl); if (!new_pte) { pte_unmap_unlock(old_pte, old_ptl); err = -EAGAIN; |