diff options
| -rw-r--r-- | mm/khugepaged.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 79be13133322..935aa8b71d1c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1642,7 +1642,7 @@ static int retract_page_tables(struct address_space *mapping, pgoff_t pgoff, * has higher cost too. It would also probably require locking * the anon_vma. */ - if (vma->anon_vma) { + if (READ_ONCE(vma->anon_vma)) { result = SCAN_PAGE_ANON; goto next; } @@ -1671,6 +1671,18 @@ static int retract_page_tables(struct address_space *mapping, pgoff_t pgoff, if ((cc->is_khugepaged || is_target) && mmap_write_trylock(mm)) { /* + * Re-check whether we have an ->anon_vma, because + * collapse_and_free_pmd() requires that either no + * ->anon_vma exists or the anon_vma is locked. + * We already checked ->anon_vma above, but that check + * is racy because ->anon_vma can be populated under the + * mmap lock in read mode. + */ + if (vma->anon_vma) { + result = SCAN_PAGE_ANON; + goto unlock_next; + } + /* * When a vma is registered with uffd-wp, we can't * recycle the pmd pgtable because there can be pte * markers installed. Skip it only, so the rest mm/vma |