On Thu, Feb 17, 2022 at 1:48 AM Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > > During the integration of PREEMPT_RT support, the code flow around > memcg_check_events() resulted in `twisted code'. Moving the code around > and avoiding then would then lead to an additional local-irq-save > section within memcg_check_events(). While looking better, it adds a > local-irq-save section to code flow which is usually within an > local-irq-off block on non-PREEMPT_RT configurations. > > The threshold event handler is a deprecated memcg v1 feature. Instead of > trying to get it to work under PREEMPT_RT just disable it. There should > be no users on PREEMPT_RT. From that perspective it makes even less > sense to get it to work under PREEMPT_RT while having zero users. > > Make memory.soft_limit_in_bytes and cgroup.event_control return > -EOPNOTSUPP on PREEMPT_RT. Make an empty memcg_check_events() and > memcg_write_event_control() which return only -EOPNOTSUPP on PREEMPT_RT. > Document that the two knobs are disabled on PREEMPT_RT. > > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> > Suggested-by: Michal Koutný <mkoutny@xxxxxxxx> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Acked-by: Roman Gushchin <guro@xxxxxx> > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
