mm, memcg: protect mem_cgroup_read_events for cpu hotplug

[karo-tx-linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1c52ddbc839ba1f8f42e940c51bc321ba6b2abfe..5335b2b6be779a2c3ee014c68465b9ad653cc3de 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -866,6 +866,7 @@ static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
        unsigned long val = 0;
        int cpu;
 
+       get_online_cpus();
        for_each_online_cpu(cpu)
                val += per_cpu(memcg->stat->events[idx], cpu);
 #ifdef CONFIG_HOTPLUG_CPU
@@ -873,6 +874,7 @@ static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
        val += memcg->nocpu_base.events[idx];
        spin_unlock(&memcg->pcp_counter_lock);
 #endif
+       put_online_cpus();
        return val;
 }