Hello, I'd like to ask what are the locking rules when using mem_cgroup_from_task(current)? Currently I'm doing this under rcu_read_lock which I believe is sufficient. However, I've seen patches where reference is obtained via mem_cgroup_from_task and then css_tryget_online is used on the resulting cgroup? Looking at the context of css_tryget_online it seems it will only succeed if the cgroup isn't being terminated (cgroup_destroy_locked isn't being invoked). Judging from this then if a css_tryget_online succeeds this means the caller can be sure they are working with a live cgroup, however, what happens if the process of acuiqring a reference on css is skipped AND the caller is under RCU read lock? They are guaranteed to succeed, but after the rcu read lock is released the cgroup might go away ? Essentially my use case is to obtain a reference to a memcg for the current process and query some counter values IOW - just reading from the memcg. Do I need to acquire a CSS reference in this case? Regards, Nikolay -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
