On Thu, Apr 22, 2010 at 02:27:55PM +0200, Peter Zijlstra wrote: > On Thu, 2010-04-22 at 17:31 +0800, Li Zefan wrote: > > with CONFIG_PROVE_RCU, a warning can be triggered when we > > resume from suspend: > > > > ... > > include/linux/cgroup.h:533 invoked rcu_dereference_check() without protection! > > ... > > > > task_freezer() calls task_subsys_state(), which needs to be > > protected by rcu_read_lock or cgroup_mutex. > > > > Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx> > > --- > > kernel/cgroup_freezer.c | 2 ++ > > 1 files changed, 2 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c > > index 5038f4c..ac76983 100644 > > --- a/kernel/cgroup_freezer.c > > +++ b/kernel/cgroup_freezer.c > > @@ -53,6 +53,7 @@ int cgroup_freezing_or_frozen(struct task_struct *task) > > struct freezer *freezer; > > enum freezer_state state; > > > > + rcu_read_lock(); > > task_lock(task); > > freezer = task_freezer(task); > > if (!freezer->css.cgroup->parent) > > @@ -60,6 +61,7 @@ int cgroup_freezing_or_frozen(struct task_struct *task) > > else > > state = freezer->state; > > task_unlock(task); > > + rcu_read_unlock(); > > > > return (state == CGROUP_FREEZING) || (state == CGROUP_FROZEN); > > } > > Hmm cgroup_attach_task() does hold task_lock() over setting > tsk->cgroups, so doesn't that also pin the task to the cgroup and thus > the cgroup itself? So you are advocating for the rcu_dereference check including the task lock, correct? Thanx, Paul _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
