Messages in this thread | | | Date | Fri, 21 Nov 2008 11:05:18 -0800 | Subject | Re: [PATCH] cpuset: rcu_read_lock() to protect task_cs() even we don't dereference to task_cs()'s return value | From | Paul Menage <> |
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On Fri, Nov 21, 2008 at 12:49 AM, Lai Jiangshan <laijs@cn.fujitsu.com> wrote: > > task_cs() calls cgroup_subsys_state().
You man "calls task_subsys_state()"
> > we must use rcu_read_lock() to protect cgroup_subsys_state(). > > in current_cpuset_is_being_rebound(), we don't dereference to task_cs()'s > return value, but task_cs() accesses css_set, this css_set maybe freed > when task_cs() called.
Wouldn't this be fixed by your patch that adds an rcu_read_lock() to task_subsys_state() ?
Paul
> > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > index 3e00526..e0e087e 100644 > --- a/kernel/cpuset.c > +++ b/kernel/cpuset.c > @@ -1141,7 +1136,11 @@ done: > > int current_cpuset_is_being_rebound(void) > { > - return task_cs(current) == cpuset_being_rebound; > + struct cpuset *cs; > + rcu_read_lock(); > + cs = task_cs(current); > + rcu_read_unlock(); > + return cs == cpuset_being_rebound; > } > > static int update_relax_domain_level(struct cpuset *cs, s64 val) > >
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