kernel hard lockups wit 5.9-rc{2,3}

kernel hard lockups wit 5.9-rc{2,3}

[Norbert Preining]

Dear all,

(please Cc)

I am seeing hard lockups with 5.9-rc2 and -rc3, while 5.8.N (1,2,3,4,5)
work without any problems.

THe lockups are hard to debug, since not even Sysrq works anymore. The
screen freezes completely, no reaction. Ports are also dead, ssh into
the machine is not possible.

Hangs are repeatable, but not triggerable (at least I didn't find a
way). Last time I left the screen locked and went shopping to find it
locked up coming back. In total I got about 10 lock ups.

This is an Intel CPU with AMD 5700xt GPU, running Debian/unstable.

My feeling is somehow GPU related, but that might be a wide grasp.

Any suggestions how to debug this? The kernel logs after reboot are
empty.

Best

Norbert

--
PREINING Norbert                              https://www.preining.info
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RE: kernel hard lockups wit 5.9-rc{2,3}

[David Laight]

From: Norbert Preining
> I am seeing hard lockups with 5.9-rc2 and -rc3, while 5.8.N (1,2,3,4,5)
> work without any problems.
> 
> THe lockups are hard to debug, since not even Sysrq works anymore. The
> screen freezes completely, no reaction. Ports are also dead, ssh into
> the machine is not possible.
> 
> Hangs are repeatable, but not triggerable (at least I didn't find a
> way). Last time I left the screen locked and went shopping to find it
> locked up coming back. In total I got about 10 lock ups.

I've had a random lockup on a pre-rc1 kernel.
But that might be one of our own drivers - OTOH they 'normally'
generate OOPS tracebacks.

Have you tried setting up a serial console?
It might contain some useful messages.

Sysrq is more likely to work with a PS2 keyboard (not USB).
IIRC the 'caps lock' light only needs PS2 keyboard interrupts
to be working - a useful check on how dead a system it.

	David

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