Messages in this thread | | | Date | Tue, 20 Apr 2010 20:14:10 -0700 | From | "Paul E. McKenney" <> | Subject | Re: INFO: suspicious rcu_dereference_check() usage - include/linux/cgroup.h:492 invoked rcu_dereference_check() without protection! |
| |
On Wed, Apr 21, 2010 at 09:05:50AM +0800, Li Zefan wrote: > > commit 2836f18139267ea918ed2cf39023fb0eb38c4361 > > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Date: Mon Apr 19 15:59:50 2010 -0700 > > > > rcu: fix RCU lockdep splat on freezer_fork path > > > > Add an RCU read-side critical section to suppress this false positive. > > > > Located-by: Eric Paris <eparis@parisplace.org> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > > diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c > > index da5e139..e5c0244 100644 > > --- a/kernel/cgroup_freezer.c > > +++ b/kernel/cgroup_freezer.c > > @@ -205,9 +205,12 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task) > > * No lock is needed, since the task isn't on tasklist yet, > > * so it can't be moved to another cgroup, which means the > > * freezer won't be removed and will be valid during this > > - * function call. > > + * function call. Nevertheless, apply RCU read-side critical > > + * section to suppress RCU lockdep false positives. > > */ > > It was me that added the original comment. > > > + rcu_read_lock(); > > freezer = task_freezer(task); > > + rcu_read_unlock(); > > > > /* > > * The root cgroup is non-freezable, so we can skip the > > Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Thank you, Li! I have added your Acked-by.
Thanx, Paul
| |