]> git.baikalelectronics.ru Git - kernel.git/commit
powerpc/watchdog: remove arch_trigger_cpumask_backtrace
authorNicholas Piggin <npiggin@gmail.com>
Wed, 17 Jan 2018 12:47:22 +0000 (22:47 +1000)
committerMichael Ellerman <mpe@ellerman.id.au>
Thu, 18 Jan 2018 04:43:43 +0000 (15:43 +1100)
commitdd287fde5f30c03ffa5bf9b890ddae36ce96c561
tree823db9b05645ce56f677a8c5a7276c7d58ca5f3a
parent03bb5f8a1732c5d9507a4199937ac42cac473a45
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: f5a97cad7542 ("powerpc/64s: implement arch-specific hardlockup watchdog")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/include/asm/nmi.h
arch/powerpc/kernel/watchdog.c