diff options
| -rw-r--r-- | mm/rmap.c | 49 |
1 files changed, 28 insertions, 21 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index f286697c61dc..68756a77ef87 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -324,36 +324,43 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) return -ENOMEM; } -static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain) -{ - struct anon_vma *anon_vma = anon_vma_chain->anon_vma; - int empty; - - /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */ - if (!anon_vma) - return; - - anon_vma_lock(anon_vma); - list_del(&anon_vma_chain->same_anon_vma); - - /* We must garbage collect the anon_vma if it's empty */ - empty = list_empty(&anon_vma->head); - anon_vma_unlock(anon_vma); - - if (empty) - put_anon_vma(anon_vma); -} - void unlink_anon_vmas(struct vm_area_struct *vma) { struct anon_vma_chain *avc, *next; + struct anon_vma *root = NULL; /* * Unlink each anon_vma chained to the VMA. This list is ordered * from newest to oldest, ensuring the root anon_vma gets freed last. */ list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { - anon_vma_unlink(avc); + struct anon_vma *anon_vma = avc->anon_vma; + + root = lock_anon_vma_root(root, anon_vma); + list_del(&avc->same_anon_vma); + + /* + * Leave empty anon_vmas on the list - we'll need + * to free them outside the lock. + */ + if (list_empty(&anon_vma->head)) + continue; + + list_del(&avc->same_vma); + anon_vma_chain_free(avc); + } + unlock_anon_vma_root(root); + + /* + * Iterate the list once more, it now only contains empty and unlinked + * anon_vmas, destroy them. Could not do before due to __put_anon_vma() + * needing to acquire the anon_vma->root->mutex. + */ + list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { + struct anon_vma *anon_vma = avc->anon_vma; + + put_anon_vma(anon_vma); + list_del(&avc->same_vma); anon_vma_chain_free(avc); } |