task_cs() calls cgroup_subsys_state(). we must use rcu_read_lock() to protect cgroup_subsys_state(). it's correct that top_cpuset is never freed, but cgroup_subsys_state() accesses css_set, this css_set maybe freed when task_cs() called. we use use rcu_read_lock() to protect it. Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> --- diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 3e00526..e0e087e 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -363,14 +363,9 @@ void cpuset_update_task_memory_state(void) struct task_struct *tsk = current; struct cpuset *cs; - if (task_cs(tsk) == &top_cpuset) { - /* Don't need rcu for top_cpuset. It's never freed. */ - my_cpusets_mem_gen = top_cpuset.mems_generation; - } else { - rcu_read_lock(); - my_cpusets_mem_gen = task_cs(tsk)->mems_generation; - rcu_read_unlock(); - } + rcu_read_lock(); + my_cpusets_mem_gen = task_cs(tsk)->mems_generation; + rcu_read_unlock(); if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) { mutex_lock(&callback_mutex); _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers