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* [V6 PATCH 0/6] Fix race issues among panic, NMI and crash_kexec
@ 2015-12-10  1:46 Hidehiro Kawai
  2015-12-10  1:46 ` [V6 PATCH 1/6] panic/x86: Fix re-entrance problem due to panic on NMI Hidehiro Kawai
                   ` (6 more replies)
  0 siblings, 7 replies; 20+ messages in thread
From: Hidehiro Kawai @ 2015-12-10  1:46 UTC (permalink / raw)
  To: Jonathan Corbet, Peter Zijlstra, Ingo Molnar, Eric W. Biederman,
	H. Peter Anvin, Andrew Morton, Thomas Gleixner, Vivek Goyal
  Cc: Baoquan He, linux-doc, x86, kexec, linux-kernel, Steven Rostedt,
	Michal Hocko, Borislav Petkov, Masami Hiramatsu

When an HA clustering software or administrator detects unresponsiveness
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.

Also, crash_kexec() called from oops context and panic() can
cause race conditions.

To solve these issues, this patch set does following things:

- Don't call panic() on NMI if the kernel has already panicked
- Extend exclusion control currently done by panic_lock to crash_kexec
- Introduce "apic_extnmi=none" boot option which masks external NMI
  NMI at the boot time

Additionally, "apic_extnmi=all" is provieded.  This option unmasks
external NMI for all CPUs.  This would help cause kernel panic even if
CPU 0 can't handle an external NMI due to hang-up in NMI context
or being handled by other NMI handlers.

This patch set can be applied to current -tip tree.

V6:
- Update comments and patch descriptions all over the patch series
- Add documentation for kernel.panic_on_io_nmi sysctl (PATCH 6/6)
- Separate PATCH 5/6 from PATCH 2/6 because the portion is actually
  needed for "apic_extnmi=all" case introduced by PATCH 4/6
- ...and various fixes (please see the change logs in each patch
  description for details)

V5: https://lkml.org/lkml/2015/11/20/228
- Use WRITE_ONCE() for crash_ipi_done to keep the instruction order
  (PATCH 2/4)
- Address concurrent unknown/external NMI case, too (PATCH 2/4)
- Fix build errors (PATCH 3/4)
- Rename "noextnmi" boot option to "apic_extnmi" and expand its
  feature (PATCH 4/4)

V4: https://lkml.org/lkml/2015/9/25/193
- Improve comments and descriptions (PATCH 1/4 to 3/4)
- Use new __crash_kexec(), no exclusion check version of crash_kexec(),
  instead of checking if panic_cpu is the current cpu or not
  (PATCH 3/4)

V3: https://lkml.org/lkml/2015/8/6/39
- Introduce nmi_panic() macro to reduce code duplication
- In the case of panic on NMI, don't return from NMI handlers
  if another cpu already panicked

V2: https://lkml.org/lkml/2015/7/27/31
- 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()

V1: https://lkml.org/lkml/2015/7/22/81

---

Hidehiro Kawai (6):
      panic/x86: Fix re-entrance problem due to panic on NMI
      panic/x86: Allow CPUs to save registers even if they are looping in NMI context
      kexec: Fix race between panic() and crash_kexec() called directly
      x86/apic: Introduce apic_extnmi boot option
      x86/nmi: Fix to save registers for crash dump on external NMI broadcast
      Documentation: Add documentation for kernel.panic_on_io_nmi sysctl


 Documentation/kernel-parameters.txt |    9 +++++++++
 Documentation/sysctl/kernel.txt     |   15 +++++++++++++++
 arch/x86/include/asm/apic.h         |    5 +++++
 arch/x86/include/asm/reboot.h       |    1 +
 arch/x86/kernel/apic/apic.c         |   35 +++++++++++++++++++++++++++++++++--
 arch/x86/kernel/nmi.c               |   27 ++++++++++++++++++++++-----
 arch/x86/kernel/reboot.c            |   28 ++++++++++++++++++++++++++++
 include/linux/kernel.h              |   29 +++++++++++++++++++++++++++++
 include/linux/kexec.h               |    2 ++
 kernel/kexec_core.c                 |   30 +++++++++++++++++++++++++++++-
 kernel/panic.c                      |   29 ++++++++++++++++++++++++-----
 kernel/watchdog.c                   |    2 +-
 12 files changed, 198 insertions(+), 14 deletions(-)


-- 
Hidehiro Kawai
Hitachi, Ltd. Research & Development Group



^ permalink raw reply	[flat|nested] 20+ messages in thread

end of thread, other threads:[~2015-12-19 10:15 UTC | newest]

Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-12-10  1:46 [V6 PATCH 0/6] Fix race issues among panic, NMI and crash_kexec Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 1/6] panic/x86: Fix re-entrance problem due to panic on NMI Hidehiro Kawai
2015-12-10 15:41   ` Borislav Petkov
2015-12-11  0:23     ` 河合英宏 / KAWAI,HIDEHIRO
2015-12-19 10:12   ` [tip:x86/apic] panic, x86: " tip-bot for Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 2/6] panic/x86: Allow CPUs to save registers even if they are looping in NMI context Hidehiro Kawai
2015-12-19 10:13   ` [tip:x86/apic] panic, x86: Allow CPUs to save registers even if " tip-bot for Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 3/6] kexec: Fix race between panic() and crash_kexec() called directly Hidehiro Kawai
2015-12-19 10:13   ` [tip:x86/apic] kexec: Fix race between panic() and crash_kexec() tip-bot for Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 4/6] x86/apic: Introduce apic_extnmi boot option Hidehiro Kawai
2015-12-19 10:13   ` [tip:x86/apic] x86/apic: Introduce apic_extnmi command line parameter tip-bot for Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 5/6] x86/nmi: Fix to save registers for crash dump on external NMI broadcast Hidehiro Kawai
2015-12-10  3:57   ` kbuild test robot
2015-12-10  6:36     ` 河合英宏 / KAWAI,HIDEHIRO
2015-12-10  6:52       ` [V6.1 " Hidehiro Kawai
2015-12-11 18:04         ` Borislav Petkov
2015-12-19 10:14         ` [tip:x86/apic] x86/nmi: Save regs in crash dump on external NMI tip-bot for Hidehiro Kawai
2015-12-10  1:46 ` [V6 PATCH 6/6] Documentation: Add documentation for kernel.panic_on_io_nmi sysctl Hidehiro Kawai
2015-12-19 10:14   ` [tip:x86/apic] Documentation: Document " tip-bot for Hidehiro Kawai
2015-12-12 11:17 ` [V6 PATCH 0/6] Fix race issues among panic, NMI and crash_kexec Borislav Petkov

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