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Date: Tue, 1 Dec 2015 23:44:37 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
 Peter Zijlstra <peterz@infradead.org>,
 Steven Rostedt <rostedt@goodmis.org>,
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 Petr Mladek <pmladek@suse.cz>
Subject: Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI
 context
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On Fri, Nov 27, 2015 at 12:09:30PM +0100, Petr Mladek wrote:
> What we can do, though, is to zap all printk locks. We already do this
> when a printk recursion is detected. This should be safe because
> the system is crashing and there shouldn't be any printk caller
> that would cause the deadlock.

What about serial consoles which may call out to subsystems like the
clk subsystem to enable a clock, which would want to take their own
spinlocks in addition to the serial console driver?

I don't see bust_spinlocks() dealing with any of these locks, so IMHO
trying to make this work in NMI context strikes me as making the
existing solution more unreliable on ARM systems.

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