Hello, On Tue, Mar 01, 2022 at 01:21:42PM +0100, Sebastian Andrzej Siewior wrote: > All callers of cgroup_rstat_flush_locked() acquire cgroup_rstat_lock > either with spin_lock_irq() or spin_lock_irqsave(). > cgroup_rstat_flush_locked() itself acquires cgroup_rstat_cpu_lock which > is a raw_spin_lock. This lock is also acquired in cgroup_rstat_updated() > in IRQ context and therefore requires _irqsave() locking suffix in > cgroup_rstat_flush_locked(). > Since there is no difference between spin_lock_t and raw_spin_lock_t > on !RT lockdep does not complain here. On RT lockdep complains because > the interrupts were not disabled here and a deadlock is possible. > > Acquire the raw_spin_lock_t with disabled interrupts. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Can you please add a comment explaining why irqsave is being used? As it stands, it just looks spurious. Thanks. -- tejun
