The Bionic request has been sent.  However, because Artful is a stable
release, it requires testing before submitting a SRU request.

I built an Artful test kernel with commit 
47712a921bb781caf69fca9eae43be19968816cb.  The test kernel can be downloaded 

Can you test this kernel and see if it resolves this bug?

Note, to test this kernel, you need to install both the linux-image and
linux-image-extra .deb packages.

Thanks in advance!

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  [OPAL] Assert fail:

Status in The Ubuntu-power-systems project:
  In Progress
Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Artful:
  In Progress
Status in linux source package in Bionic:
  In Progress

Bug description:
  == Comment: #0 - Application Cdeadmin <> -
  2018-04-03 05:20:56 ==

  == Comment: #1 - Application Cdeadmin <> - 2018-04-05 01:30:56 ==
  ------- Comment From pridhiviraj 2018-04-05 01:30:25 EDT -------
  The disto needs 47712a921bb781caf69fca9eae43be19968816cb this level of 
commits need to be backported as suggested by Nick piggin.

  == Comment: #2 - PAWAN K. SINGH <> - 2018-04-06 03:35:49 ==
  which is ----

  From 47712a921bb781caf69fca9eae43be19968816cb Mon Sep 17 00:00:00 2001
  From: Nicholas Piggin <>
  Date: Wed, 17 Jan 2018 22:47:22 +1000
  Subject: [PATCH] powerpc/watchdog: remove arch_trigger_cpumask_backtrace

  The powerpc NMI IPIs may not be recoverable if they are taken in
  some sections of code, and also there have been and still are issues
  with taking NMIs (in KVM guest code, in firmware, etc) which makes them
  a bit dangerous to use.

  Generic code like softlockup detector and rcu stall detectors really
  hammer on trigger_*_backtrace, which has lead to further problems
  because we've implemented it with the NMI.

  So stop providing NMI backtraces for now. Importantly, the powerpc code
  uses NMI IPIs in crash/debug, and the SMP hardlockup watchdog. So if the
  softlockup and rcu hang detection traces are not being printed because
  the CPU is stuck with interrupts off, then the hard lockup watchdog
  should get it with the NMI IPI.

  Fixes: 2104180a5369 ("powerpc/64s: implement arch-specific hardlockup 
  Signed-off-by: Nicholas Piggin <>
  Signed-off-by: Michael Ellerman <>
   arch/powerpc/include/asm/nmi.h |  4 ----
   arch/powerpc/kernel/watchdog.c | 22 ----------------------
   2 files changed, 26 deletions(-)

  diff --git a/arch/powerpc/include/asm/nmi.h b/arch/powerpc/include/asm/nmi.h
  index e97f586..9c80939 100644
  --- a/arch/powerpc/include/asm/nmi.h
  +++ b/arch/powerpc/include/asm/nmi.h
  @@ -4,10 +4,6 @@
   extern void arch_touch_nmi_watchdog(void);
  -extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
  -                                        bool exclude_self);
  -#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
   static inline void arch_touch_nmi_watchdog(void) {}
  diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
  index 87da80c..3963baa 100644
  --- a/arch/powerpc/kernel/watchdog.c
  +++ b/arch/powerpc/kernel/watchdog.c
  @@ -393,25 +393,3 @@ int __init watchdog_nmi_probe(void)
        return 0;
  -static void handle_backtrace_ipi(struct pt_regs *regs)
  -     nmi_cpu_backtrace(regs);
  -static void raise_backtrace_ipi(cpumask_t *mask)
  -     unsigned int cpu;
  -     for_each_cpu(cpu, mask) {
  -             if (cpu == smp_processor_id())
  -                     handle_backtrace_ipi(NULL);
  -             else
  -                     smp_send_nmi_ipi(cpu, handle_backtrace_ipi, 1000000);
  -     }
  -void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
  -     nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);


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