From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: Re: powerpc/watchdog: remove arch_trigger_cpumask_backtrace
Date: Mon, 22 Jan 2018 14:34:30 +1100 (AEDT) [thread overview]
Message-ID: <3zPxr81Gk4z9t39@ozlabs.org> (raw)
In-Reply-To: <20180117124722.31063-1-npiggin@gmail.com>
On Wed, 2018-01-17 at 12:47:22 UTC, Nicholas Piggin wrote:
> 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 watchdog")
> Signed-of-by: Nicholas Piggin <npiggin@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/47712a921bb781caf69fca9eae43be
cheers
prev parent reply other threads:[~2018-01-22 3:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 12:47 [PATCH] powerpc/watchdog: remove arch_trigger_cpumask_backtrace Nicholas Piggin
2018-01-22 3:34 ` Michael Ellerman [this message]
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