cgroups: fix lockdep subclasses overflow
I enabled all cgroup subsystems when compiling kernel, and then:
# mount -t cgroup -o net_cls xxx /mnt
# mkdir /mnt/0
This showed up immediately:
BUG: MAX_LOCKDEP_SUBCLASSES too low!
turning off the locking correctness validator.
It's caused by the cgroup hierarchy lock:
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (ss->root == root)
mutex_lock_nested(&ss->hierarchy_mutex, i);
}
Now we have 9 cgroup subsystems, and the above 'i' for net_cls is 8, but
MAX_LOCKDEP_SUBCLASSES is 8.
This patch uses different lockdep keys for different subsystems.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5a54ff4..e14db9c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2351,7 +2351,7 @@
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (ss->root == root)
- mutex_lock_nested(&ss->hierarchy_mutex, i);
+ mutex_lock(&ss->hierarchy_mutex);
}
}
@@ -2637,6 +2637,7 @@
BUG_ON(!list_empty(&init_task.tasks));
mutex_init(&ss->hierarchy_mutex);
+ lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
ss->active = 1;
}
