path: root/kernel/user_namespace.c
diff options
authorDavid Howells <dhowells@redhat.com>2009-02-27 14:03:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-27 16:26:21 -0800
commit5170836679185357dc1b7660bad13287b39e1e33 (patch)
tree0b470820e11df7c7eef7e3161657aefe90c7c35e /kernel/user_namespace.c
parent8ca2f156b06bdcbfd1ab543355279246d05e2499 (diff)
Fix recursive lock in free_uid()/free_user_ns()
free_uid() and free_user_ns() are corecursive when CONFIG_USER_SCHED=n, but free_user_ns() is called from free_uid() by way of uid_hash_remove(), which requires uidhash_lock to be held. free_user_ns() then calls free_uid() to complete the destruction. Fix this by deferring the destruction of the user_namespace. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/user_namespace.c')
1 files changed, 17 insertions, 4 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 79084311ee5..076c7c8215b 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -60,12 +60,25 @@ int create_user_ns(struct cred *new)
return 0;
-void free_user_ns(struct kref *kref)
+ * Deferred destructor for a user namespace. This is required because
+ * free_user_ns() may be called with uidhash_lock held, but we need to call
+ * back to free_uid() which will want to take the lock again.
+ */
+static void free_user_ns_work(struct work_struct *work)
- struct user_namespace *ns;
- ns = container_of(kref, struct user_namespace, kref);
+ struct user_namespace *ns =
+ container_of(work, struct user_namespace, destroyer);
+void free_user_ns(struct kref *kref)
+ struct user_namespace *ns =
+ container_of(kref, struct user_namespace, kref);
+ INIT_WORK(&ns->destroyer, free_user_ns_work);
+ schedule_work(&ns->destroyer);