Re: [PATCH -next] mm/hotplug: silence a lockdep splat with printk()

[Qian Cai]

> On Jan 14, 2020, at 4:02 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> 
> Yeah, that was a long discussion with a lot of lockdep false positives.
> I believe I have made it clear that the console code shouldn't depend on
> memory allocation because that is just too fragile. If that is not
> possible for some reason then it has to be mentioned in the changelog.
> I really do not want us to add kludges to the MM code just because of
> printk deficiencies unless that is absolutely inevitable.

I donât know how to convince you, but both random number generator and printk() maintainers agreed to get ride of printk() with zone->lock held as you can see in the approved commit mentioned in this patch description because it is a whac-a-mole to fix other places. In other word, the patch alone fixes quite a few false positives and potential real deadlocks. Maybe Andrew please has a look at this directly?