On (10/19/18 19:35), Tetsuo Handa wrote: > > > > OK, that's a fair point. There was a patch from FB, which would allow us > > to set a log_level on per-console basis. So the noise goes to heav^W net > > console; only critical stuff goes to the serial console (if I recall it > > correctly). I'm not sure what happened to that patch, it was a while ago. > > I'll try to find that out. > > Per a console loglevel setting would help for several environments. > But syzbot environment cannot count on netconsole. We can't expect that > unlimited printk() will become safe. This target is moving too fast :) RCU stall -> user interaction -> syzbot I talked to Calvin Owens (who's working on the per-console loglevel patch set; CC-ed) and Calvin said that "It's in-progress". So we probably will have this functionality one day. That's all we can do from printk side wrt user-interaction problem. > > The problem you are talking about is not MM specific. You can have a > > faulty SCSI device, corrupted FS, and so and on. > > "a faulty SCSI device, corrupted FS, and so and on" are reporting problems > which will complete a request. They can use (and are using) ratelimit, > aren't they? Looking at scsi_request_fn(), the answer is probably "sure they can; but no, they aren't". In majority of cases the reason we replace printk with printk_ratelimit is because someone reports a stall or a lockup. Otherwise, people use printk(), which is absolutely fine. -ss
