diff options
| author | Andrei Vagin <avagin@openvz.org> | 2017-01-04 19:28:14 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-19 20:18:03 +0100 |
| commit | 52fd0ab07676b295abc54eeb1cef7a06d49c9847 (patch) | |
| tree | 736f3cffb43a9b0f663f38bc54fef8cbb9debaab /kernel/pid_namespace.c | |
| parent | 57bfd5a3710bff25e35974de6db8816103d44973 (diff) | |
pid: fix lockdep deadlock warning due to ucount_lock
commit add7c65ca426b7a37184dd3d2172394e23d585d6 upstream.
=========================================================
[ INFO: possible irq lock inversion dependency detected ]
4.10.0-rc2-00024-g4aecec9-dirty #118 Tainted: G W
---------------------------------------------------------
swapper/1/0 just changed the state of lock:
(&(&sighand->siglock)->rlock){-.....}, at: [<ffffffffbd0a1bc6>] __lock_task_sighand+0xb6/0x2c0
but this lock took another, HARDIRQ-unsafe lock in the past:
(ucounts_lock){+.+...}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Chain exists of: &(&sighand->siglock)->rlock --> &(&tty->ctrl_lock)->rlock --> ucounts_lock
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(ucounts_lock);
local_irq_disable();
lock(&(&sighand->siglock)->rlock);
lock(&(&tty->ctrl_lock)->rlock);
<Interrupt>
lock(&(&sighand->siglock)->rlock);
*** DEADLOCK ***
This patch removes a dependency between rlock and ucount_lock.
Fixes: f333c700c610 ("pidns: Add a limit on the number of pid namespaces")
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/pid_namespace.c')
| -rw-r--r-- | kernel/pid_namespace.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index df9e8e9e0be7..eef2ce968636 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -151,8 +151,12 @@ out: static void delayed_free_pidns(struct rcu_head *p) { - kmem_cache_free(pid_ns_cachep, - container_of(p, struct pid_namespace, rcu)); + struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu); + + dec_pid_namespaces(ns->ucounts); + put_user_ns(ns->user_ns); + + kmem_cache_free(pid_ns_cachep, ns); } static void destroy_pid_namespace(struct pid_namespace *ns) @@ -162,8 +166,6 @@ static void destroy_pid_namespace(struct pid_namespace *ns) ns_free_inum(&ns->ns); for (i = 0; i < PIDMAP_ENTRIES; i++) kfree(ns->pidmap[i].page); - dec_pid_namespaces(ns->ucounts); - put_user_ns(ns->user_ns); call_rcu(&ns->rcu, delayed_free_pidns); } |