linux-kernel - Re: [patch V2 22/29] lockup_detector: Make watchdog_nmi

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Date:   Tue, 3 Oct 2017 15:20:21 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Michael Ellerman <mpe@...erman.id.au>
cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Nicholas Piggin <npiggin@...il.com>,
        Don Zickus <dzickus@...hat.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Ulrich Obergfell <uobergfe@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [patch V2 22/29] lockup_detector: Make watchdog_nmi_reconfigure()
 two stage

On Tue, 3 Oct 2017, Thomas Gleixner wrote:
> On Tue, 3 Oct 2017, Michael Ellerman wrote:
> > Hmm, I tried that patch, it makes the warning go away. But then I
> > triggered a deliberate hard lockup and got nothing.
> > 
> > Then I went back to the existing code (in linux-next), and I still get
> > no warning from a deliberate hard lockup.
> > 
> > So seems there may be some more gremlins. Will test more in the morning.
> 
> Hrm. That's weird. I'll have a look and send a proper patch series on top
> of next.

The major difference is that the reworked code utilizes
watchdog_nmi_reconfigure() for both init and the sysctl updates, but I
can't for my life figure out why that doesn't work.

Thanks,

	tglx