linux-kernel - Re: Bug 218665 - nohz_full=0 prevents kernel from booting

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Date: Mon, 22 Apr 2024 16:23:15 -0500
From: Bjorn Andersson <andersson@...nel.org>
To: Tejun Heo <tj@...nel.org>
Cc: Linux regressions mailing list <regressions@...ts.linux.dev>, 
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Bug 218665 - nohz_full=0 prevents kernel from booting

On Wed, Apr 17, 2024 at 04:07:26PM -1000, Tejun Heo wrote:
> Hello, Thorsten.
> 
> On Wed, Apr 17, 2024 at 07:48:33AM +0200, Linux regression tracking (Thorsten Leemhuis) wrote:
> > > Can you elaborate why Bjorn's case is different?
> > 
> > Well "not booting at all when using 'nohz_full=0'"[as reported two
> > times] and "I start neovim, send SIGSTOP (i.e. ^Z) to it, start another
> > neovim instance and upon sending SIGSTOP to that instance all of
> > userspace locks up - 100% reproducible."[while no 'nohz_full=0' in use]
> > at least on the first sight to and outsider sound a lot like different
> > problems to me -- but of course that impression might be wrong and you
> > know better about these things.
> 
> You are right. That is very different.
> 
> > > I was assuming it was the
> > > same problem and that Oleg's fixes would address the issue.
> > 
> > Bjorn, could you give it a try?
> 
> Yeah, I'm curious whether it's just a different symptom of the same problem.
> 

Sorry for the late reply, had to step back to v6.8 on my work machine
and didn't retry this in a timely manner.

I've now confirmed that my problem with Neovim was resolved in v6.9-rc3,
through the introduction of:
73eaa2b58349 ("io_uring: use private workqueue for exit work")

Regards,
Bjorn