On 2020/07/01 6:57, Alexei Starovoitov wrote: >>>>> They were all should never happen cases. Which is why my patches do: >>>>> if (WARN_ON_ONCE(...)) >>>> >>>> No. Fuzz testing (which uses panic_on_warn=1) will trivially hit them. >>> >>> I don't believe that's true. >>> Please show fuzzing stack trace to prove your point. >>> >> >> Please find links containing "WARNING" from https://syzkaller.appspot.com/upstream . ;-) > > Is it a joke? Do you understand how syzbot works? > If so, please explain how it can invoke umd_* interface. > Currently syzkaller can't invoke umd_* interface because this interface is used by only bpfilter_umh module. But I can imagine that someone starts using this interface in a way syzkaller can somehow invoke. Thus, how can it be a joke? I don't understand your question.