On Fri, Jan 22, 2021 at 4:42 PM Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote: > > Hello, BPF developers. > > Alexey Kardashevskiy is reporting that system_wq gets stuck due to flooding of > unbounded bpf_map_free_deferred work. Use of WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND > workqueue did not solve this problem. Is it possible that a refcount leak somewhere > preventing bpf_map_free_deferred from completing? Please see > https://lkml.kernel.org/r/CACT4Y+Z+kwPM=WUzJ-e359PWeLLqmF0w4Yxp1spzZ=+J0ekrag@xxxxxxxxxxxxxx . > Which map does the reproducer create? And where exactly do those work block on? Different map->ops->map_free() waits for different reasons, for example, htab_map_free() waits for flying htab_elem_free_rcu(). I can't immediately see how they could wait for each other, if this is what you meant above. Thanks.
