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Date:   Mon, 27 Apr 2020 15:06:26 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
        Tom Zanussi <zanussi@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-rt-users <linux-rt-users@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Carsten Emde <C.Emde@osadl.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        John Kacur <jkacur@redhat.com>,
        Julia Cartwright <julia@ni.com>,
        Daniel Wagner <wagi@monom.org>,
        Julien Grall <julien.grall@arm.com>
Subject: Re: [PATCH RT 10/30] hrtimer: Prevent using
 hrtimer_grab_expiry_lock() on migration_base
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On Mon, 27 Apr 2020 15:10:00 +0200
Rasmus Villemoes <rasmus.villemoes@prevas.dk> wrote:

> However, building with their rescue initrd and booting that, the board
> would consistently hang during reboot. Sometimes I would get lines like
> 
> [   72.956630] sched: RT throttling activated
> [   72.973769] lanx: port 1(lan1) entered disabled state
> [   73.000401] lanx: port 2(lan2) entered disabled state
> [   73.974951] lanx: port 3(lan3) entered disabled state
> [   73.997473] lanx: port 4(lan4) entered disabled state
> [   74.968006] lanx: port 5(lan5) entered disabled state
> 
> other times there would be no output, but the board was still hanging.
> Reverting
> 
> b1a471ec4df1 - hrtimer: Prevent using hrtimer_grab_expiry_lock() on
> migration_base
> 40aae5708e7a - hrtimer: Add a missing bracket and hide `migration_base'
> on !SMP
> 
> on top of v4.19.94-rt39 makes that problem go away, i.e. the board
> reboots as expected.
> 
> The board is a 32 bit powerpc (mpc8309) !SMP. Any ideas what I can do to
> debug this further?

Thanks Rasmus for looking into this. Tom now maintains 4.19-rt.

Tom, care to pull in these patches on top of 4.19-rt?

-- Steve