Re: sched: serial port lockdep warning when offlining CPUs
From: Peter Zijlstra
Date: Thu Sep 28 2017 - 08:05:49 EST
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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.