(resending, I messed up the message header, sorry) Hello, On Fri, Jul 15, 2022 at 01:59:38PM +0200, Michal Koutný wrote: > The css->rstat_css_node should not be modified if there are possible RCU > readers elsewhere. > One way to fix this would be to insert synchronize_rcu() after > list_del_rcu() and before list_add_rcu(). > (A further alternative (I've heard about) would be to utilize 'nulls' > RCU lists [1] to make the move between lists detectable.) > > But as I'm looking at it from distance, it may be simpler and sufficient > to just take cgroup_rstat_lock around the list migration (the nesting > under cgroup_mutex that's held with rebind_subsystems() is fine). synchronize_rcu() prolly is the better fit here given how that list_node's usage, but yeah, great find. Thanks. -- tejun
