On Thu, Mar 07, 2019 at 03:00:30PM -0800, Roman Gushchin wrote: > Similar to the memcg's vmstats_percpu, per-memcg per-node stats > consists of percpu- and atomic counterparts, and we do expect > that both coexist during the whole life-cycle of the memcg. > > To prepare for a premature release of percpu per-node data, > let's pretend that lruvec_stat_cpu is a rcu-protected pointer, > which can be NULL. This patch adds corresponding checks whenever > required. > > Signed-off-by: Roman Gushchin <[email protected]>
Acked-by: Johannes Weiner <[email protected]> > @@ -4430,7 +4436,8 @@ static int alloc_mem_cgroup_per_node_info(struct > mem_cgroup *memcg, int node) > if (!pn) > return 1; > > - pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat); > + rcu_assign_pointer(pn->lruvec_stat_cpu, > + alloc_percpu(struct lruvec_stat)); > if (!pn->lruvec_stat_cpu) { Nitpick: wouldn't this have to use rcu_dereference()? Might be cleaner to use an intermediate variable and only assign after the NULL check.
