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.
Also, crash_kexec() called from oops context and panic() can cause race conditions. To solve these issue, this patch set does following things: - Don't panic on NMI if the kernel has already panicked - Extend exclusion control currently done by panic_lock to crash_kexec - Introduce "noextnmi" boot option which masks external NMI at the boot time (supported only for x86) V3: - 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: - 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 (4): 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 noextnmi boot option Documentation/kernel-parameters.txt | 4 ++++ arch/x86/kernel/apic/apic.c | 17 ++++++++++++++++- arch/x86/kernel/nmi.c | 15 +++++++++++---- arch/x86/kernel/reboot.c | 11 +++++++++++ include/linux/kernel.h | 21 +++++++++++++++++++++ kernel/kexec.c | 20 ++++++++++++++++++++ kernel/panic.c | 23 ++++++++++++++++++++--- kernel/watchdog.c | 5 +++-- 8 files changed, 106 insertions(+), 10 deletions(-) -- Hidehiro Kawai Hitachi, Ltd. Research & Development Group -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/