[V2 PATCH 0/3] x86: Fix panic vs. NMI issues

Hidehiro Kawai hidehiro.kawai.ez at hitachi.com
Sun Jul 26 18:58:50 PDT 2015

When an HA cluster software or administrator detects non-response
of a host, they issue an NMI to the host to completely stop current
works and take a crash dump.  If the kernel has already panicked
or is capturing a crash dump at that time, further NMI can cause
a crash dump failure.

To solve this issue, this patch set does two things:

- Don't panic on NMI if the kernel has already panicked
- Introduce "noextnmi" boot option which masks external NMI at the
  boot time (supported only for x86)

- Use atomic_cmpxchg() instead of current spin_trylock() to exclude
  concurrent accesses to panic() and crash_kexec()
- Don't introduce no-lock version of panic() and crash_kexec()


Hidehiro Kawai (3):
      x86/panic: Fix re-entrance problem due to panic on NMI
      kexec: Fix race between panic() and crash_kexec() called directly
      x86/apic: Introduce noextnmi boot option

 Documentation/kernel-parameters.txt |    4 ++++
 arch/x86/kernel/apic/apic.c         |   17 ++++++++++++++++-
 arch/x86/kernel/nmi.c               |   15 +++++++++++----
 include/linux/kernel.h              |    1 +
 kernel/kexec.c                      |   20 ++++++++++++++++++++
 kernel/panic.c                      |   13 ++++++++++---
 6 files changed, 62 insertions(+), 8 deletions(-)

Hidehiro Kawai
Hitachi, Ltd. Research & Development Group

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