kmem_cache_free(anon_vma_cachep, anon_vma);
}
-static inline struct anon_vma_chain *anon_vma_chain_alloc(void)
+static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
{
- return kmem_cache_alloc(anon_vma_chain_cachep, GFP_KERNEL);
+ return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
}
static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
struct mm_struct *mm = vma->vm_mm;
struct anon_vma *allocated;
- avc = anon_vma_chain_alloc();
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
if (!avc)
goto out_enomem;
list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
struct anon_vma *anon_vma;
- avc = anon_vma_chain_alloc();
- if (!avc)
- goto enomem_failure;
+ avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
+ if (unlikely(!avc)) {
+ unlock_anon_vma_root(root);
+ root = NULL;
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
+ if (!avc)
+ goto enomem_failure;
+ }
anon_vma = pavc->anon_vma;
root = lock_anon_vma_root(root, anon_vma);
anon_vma_chain_link(dst, avc, anon_vma);
return 0;
enomem_failure:
- unlock_anon_vma_root(root);
unlink_anon_vmas(dst);
return -ENOMEM;
}
anon_vma = anon_vma_alloc();
if (!anon_vma)
goto out_error;
- avc = anon_vma_chain_alloc();
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
if (!avc)
goto out_error_free_anon_vma;
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);
}