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Date:   Tue, 21 Nov 2023 18:21:39 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Chengming Zhou <chengming.zhou@linux.dev>
Cc:     vbabka@suse.cz, cl@linux.com, penberg@kernel.org,
        rientjes@google.com, iamjoonsoo.kim@lge.com,
        akpm@linux-foundation.org, roman.gushchin@linux.dev,
        42.hyeyoo@gmail.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Chengming Zhou <zhouchengming@bytedance.com>
Subject: Re: [PATCH v5 6/9] slub: Delay freezing of partial slabs
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On Tue, Nov 21, 2023 at 11:47:26PM +0800, Chengming Zhou wrote:

> Ah yes, there is no NMI on ARM, so CPU 3 maybe running somewhere with
> interrupts disabled. I searched the full log, but still haven't a clue.
> And there is no any WARNING or BUG related to SLUB in the log.

Yeah, nor anything else particularly.  I tried turning on some debug
options:

CONFIG_SOFTLOCKUP_DETECTOR=y
CONFIG_DETECT_HUNG_TASK=y
CONFIG_WQ_WATCHDOG=y
CONFIG_DEBUG_PREEMPT=y
CONFIG_DEBUG_LOCKING=y
CONFIG_DEBUG_ATOMIC_SLEEP=y

https://validation.linaro.org/scheduler/job/4017828

which has some additional warnings related to clock changes but AFAICT
those come from today's -next rather than the debug stuff:

https://validation.linaro.org/scheduler/job/4017823

so that's not super helpful.

> I wonder how to reproduce it locally with a Qemu VM since I don't have
> the ARM machine.

There's sample qemu jobs available from for example KernelCI:

   https://storage.kernelci.org/next/master/next-20231120/arm/multi_v7_defconfig/gcc-10/lab-baylibre/baseline-qemu_arm-virt-gicv3.html

(includes the command line, though it's not using Debian testing like my
test was).  Note that I'm testing a bunch of platforms with the same
kernel/rootfs combination and it was only the Raspberry Pi 3 which blew
up.  It is a bit tight for memory which might have some influence?

I'm really suspecting this may have made some underlying platform bug
more obvious :/

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