Re: sched: serial port lockdep warning when offlining CPUs

[Peter Zijlstra]

On Thu, Sep 28, 2017 at 02:05:32PM +0200, Peter Zijlstra wrote:
> (please linewrap normal text at 72 chars)
> 
> On Thu, Sep 28, 2017 at 11:45:30AM +0000, Levin, Alexander (Sasha Levin) wrote:
> > Okay, that seems to have delt with the callbacks supressed issue.
> > 
> > I also seem to be hitting it as a result of the scheduler triggering a
> > WARN, where print_stack_trace(), for example, just uses printk().
> > 
> > Now I'm not sure what's your approach here, do we keep converting
> > printk to printk_deferred one by one until we whacked every mole?
> 
> Nah.. WARN's _should_ not trigger. If they do we fix that.
> 
> Getting a lockdep splat after a WARN is something I can live with.
> 
> And you really don't want that deferred nonsense for WARNs, because that
> means you'll risk not over getting the output.

Note that I'm not likely to care too much either way, because I'm simply
not using any of that printk() nonsense ;-)


I'll repost my patches now; otherwise I'll forget again anyway.