Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI context

From	Russell King - ARM Linux <linux@arm.linux.org.uk>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI context
Date	2015-12-02 00:50 +0100
Message-ID	<qB2Qj-7Sl-27@gated-at.bofh.it> (permalink)
References	<qzp4E-243-71@gated-at.bofh.it> <qzpei-27s-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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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Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI  context Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-02 00:50 +0100
  Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI  context Petr Mladek <pmladek@suse.com> - 2015-12-04 16:30 +0100
    Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI  context Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-12-04 18:20 +0100
      RE: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in  NMI context David Laight <David.Laight@ACULAB.COM> - 2015-12-07 17:00 +0100
        Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI  context Petr Mladek <pmladek@suse.com> - 2015-12-08 15:50 +0100
      Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI  context Petr Mladek <pmladek@suse.com> - 2015-12-08 12:30 +0100

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