Shakeel Butt <shakeel.butt@xxxxxxxxx> writes: > Generally memcg charging is allowed from all the contexts including NMI > where even spinning on spinlock can cause locking issues. However one > call chain was missed during the addition of memcg charging from any > context support. That is try_charge_memcg() -> memcg_memory_event() -> > cgroup_file_notify(). > > The possible function call tree under cgroup_file_notify() can acquire > many different spin locks in spinning mode. Some of them are > cgroup_file_kn_lock, kernfs_notify_lock, pool_workqeue's lock. So, let's > just skip cgroup_file_notify() from memcg charging if the context does > not allow spinning. Hmm, what about OOM events? Losing something like MEMCG_LOW doesn't look like a bit deal, but OOM events can be way more important. Should we instead preserve the event (e.g. as a pending_event_mask) and raise it on the next occasion / from a different context? Thanks
