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From:   John Ogness <john.ogness@linutronix.de>
To:     Vlastimil Babka <vbabka@suse.cz>,
        Pierre Gondois <pierre.gondois@arm.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        linux-rt-users@vger.kernel.org,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [ANNOUNCE] v6.3-rc2-rt3
In-Reply-To: <73b5657a-4c47-980a-e709-cd6a880c067c@suse.cz>
References: <20230314170502.OHw1_FK3@linutronix.de>
 <20230314171231.jwtham4a@linutronix.de>
 <9ee941ae-ae22-f14b-4e69-f81b29bbba4b@arm.com>
 <87ttxiefpd.fsf@jogness.linutronix.de>
 <73b5657a-4c47-980a-e709-cd6a880c067c@suse.cz>
Date:   Fri, 14 Apr 2023 17:07:25 +0206
Message-ID: <87pm86ece2.fsf@jogness.linutronix.de>
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On 2023-04-14, Vlastimil Babka <vbabka@suse.cz> wrote:
> Is it perhaps a similar situation to this thread?
>
> https://lore.kernel.org/all/20230412124735.GE628377@hirez.programming.kicks-ass.net/

We are dealing with a spin_lock() inside a raw_spin_lock() section. The
legacy console drivers do this. The fix is the new atomic/threaded
consoles. For CONFIG_PREEMPT_RT a workaround is implemented so that the
legacy consoles avoid this. For !CONFIG_PREEMPT_RT you can expect
CONFIG_PROVE_RAW_LOCK_NESTING to cause a splat on that printk().

Or perhaps that particular printk() in cblist_init_generic() should be
changed to printk_deferred() as a temporary whack-a-mole
workaround.

John Ogness