Messages in this thread | | | Date | Tue, 14 Dec 2021 20:36:57 -0800 | From | Davidlohr Bueso <> | Subject | Re: [PATCH-next v3] mm/memcg: Properly handle memcg_stock access for PREEMPT_RT |
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On Tue, 14 Dec 2021, Waiman Long wrote:
>@@ -2189,7 +2194,7 @@ static void drain_local_stock(struct work_struct *dummy) > * drain_stock races is that we always operate on local CPU stock > * here with IRQ disabled > */ >- local_irq_save(flags); >+ local_lock_irqsave(&memcg_stock.lock, flags); > > stock = this_cpu_ptr(&memcg_stock); > drain_obj_stock(&stock->irq_obj);
So here there is still the problem that you can end up taking sleeping locks with irqs disabled via obj_cgroup_put() >> obj_cgroup_release() - ie: the percpu_ref_switch_lock and css_set_lock. It had occurred to me to promote the former to a raw spinlock, but doubt we can get away with the latter.
Thanks, Davidlohr
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