Messages in this thread | | | Date | Wed, 6 Jan 2021 16:44:21 +0100 | From | Peter Zijlstra <> | Subject | Re: lockdep splat in v5.11-rc1 involving console_sem and rq locks |
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On Wed, Jan 06, 2021 at 06:46:21AM -0800, Paul E. McKenney wrote: > Huh. The WARN does not always generate the lockdep complaint. But > fair enough.
Any printk()/WARN/BUG with rq lock held ought to generate that splat, sometimes we die before we splat. The printk rewrite should eventually fix that.
> > https://lkml.kernel.org/r/20201226025117.2770-1-jiangshanlai@gmail.com > > Thomas pointed me at this one a couple of weeks ago. Here is an > additional fix for rcutorture: f67e04bb0695 ("torture: Break affinity > of kthreads last running on outgoing CPU"). I am still getting WARNs > and lockdep splats with both applied.
That patch looks racy, what avoids the task being shuffled right back before the CPU goes offline?
> What would break if I made the code dump out a few entries in the > runqueue if the warning triggered?
There was a patch around that did that, Valentin might remember where that was.
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