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That way we know that the problem is real and not a > > false-positive from some tool. You can reproduce it by adding enough > > delay in inetdev_destroy(): > > I guess delay was added between ip_mc_destroy_dev() and > RCU_INIT_POINTER(dev->ip_ptr, NULL) ? Yes, to increase the race window. > I feel like we should clear it first and destroy everything > as done in IPv6 addrconf_ifdown(). I agree, but let's do it as a separate change in net-next. The current one line fix is correct and fixes the root cause. Clearing the pointer happens to fix the problem because it relies on mc_hash only being accessible via dev->in_dev (vs reaching in_dev via a different path).