2 files changed, 7 insertions, 3 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index a0d0ef1f1a48..9d17541ebafa 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -869,7 +869,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
                 /* don't do anything if the namespace is dead - all the
                  * vfsmounts from it are going away anyway */
                 namespace = mnt->mnt_namespace;
-                if (!namespace || atomic_read(&namespace->count) <= 0)
+                if (!namespace || !namespace->root)
                         continue;
                 get_namespace(namespace);
 
@@ -1450,9 +1450,12 @@ void __init mnt_init(unsigned long mempages)
 
 void __put_namespace(struct namespace *namespace)
 {
+        struct vfsmount *root = namespace->root;
+        namespace->root = NULL;
+        spin_unlock(&vfsmount_lock);
         down_write(&namespace->sem);
         spin_lock(&vfsmount_lock);
-        umount_tree(namespace->root);
+        umount_tree(root);
         spin_unlock(&vfsmount_lock);
         up_write(&namespace->sem);
         kfree(namespace);
diff --git a/include/linux/namespace.h b/include/linux/namespace.h
index 697991b69f9b..0e5a86f13b2f 100644
--- a/include/linux/namespace.h
+++ b/include/linux/namespace.h
@@ -17,7 +17,8 @@ extern void __put_namespace(struct namespace *namespace);
 
 static inline void put_namespace(struct namespace *namespace)
 {
-        if (atomic_dec_and_test(&namespace->count))
+        if (atomic_dec_and_lock(&namespace->count, &vfsmount_lock))
+                /* releases vfsmount_lock */
                 __put_namespace(namespace);
 }