diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index b086dc957b0c..15a55304aa3b 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -542,6 +542,7 @@ struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, struct anon_vma *root_anon_vma; unsigned long anon_mapping; +retry: rcu_read_lock(); anon_mapping = (unsigned long)READ_ONCE(folio->mapping); if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) @@ -553,6 +554,17 @@ struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, root_anon_vma = READ_ONCE(anon_vma->root); if (down_read_trylock(&root_anon_vma->rwsem)) { /* + * folio_move_anon_rmap() might have changed the anon_vma as we + * might not hold the folio lock here. + */ + if (unlikely((unsigned long)READ_ONCE(folio->mapping) != + anon_mapping)) { + up_read(&root_anon_vma->rwsem); + rcu_read_unlock(); + goto retry; + } + + /* * If the folio is still mapped, then this anon_vma is still * its anon_vma, and holding the mutex ensures that it will * not go away, see anon_vma_free(). @@ -586,6 +598,18 @@ struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, rcu_read_unlock(); anon_vma_lock_read(anon_vma); + /* + * folio_move_anon_rmap() might have changed the anon_vma as we might + * not hold the folio lock here. + */ + if (unlikely((unsigned long)READ_ONCE(folio->mapping) != + anon_mapping)) { + anon_vma_unlock_read(anon_vma); + put_anon_vma(anon_vma); + anon_vma = NULL; + goto retry; + } + if (atomic_dec_and_test(&anon_vma->refcount)) { /* * Oops, we held the last refcount, release the lock |