Messages in this thread | | | Date | Thu, 23 Jun 2022 11:31:51 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH v2] panic, kexec: Make __crash_kexec() NMI safe |
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On 2022-06-20 12:15:20 [+0100], Valentin Schneider wrote: > Attempting to get a crash dump out of a debug PREEMPT_RT kernel via an NMI > panic() doesn't work. The cause of that lies in the PREEMPT_RT definition > of mutex_trylock(): > …
> Fixes: 6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softirq context") > Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> --- > v1 -> v2 > ++++++++ > > o Changed from Peterson-like synchronization to simpler atomic_cmpxchg > (Petr) > o Slightly reworded changelog > o Added Fixes: tag. Technically should be up to since kexec can happen > in an NMI, but that isn't such a clear target
RT-wise it would be needed for each release. There is also a mutex_unlock() in case an image is missing. This can go via the scheduler if there is a waiter which does not look good with the NMI in the picture.
Sebastian
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