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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Corentin Labbe <clabbe.montjoie@gmail.com>,
        qemu-discuss@nongnu.org, mingo@redhat.com, bp@alien8.de,
        hpa@zytor.com, x86@kernel.org
Cc:     linux-kernel@vger.kernel.org
Subject: Re: qemu-x86: kernel panic when host is loaded
In-Reply-To: <20200402093132.GA15839@Red>
References: <20200402093132.GA15839@Red>
Date:   Thu, 02 Apr 2020 11:57:52 +0200
Message-ID: <87eet6nra7.fsf@nanos.tec.linutronix.de>
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Sender: linux-kernel-owner@vger.kernel.org
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Corentin,

Corentin Labbe <clabbe.montjoie@gmail.com> writes:
> On our kernelci lab, each qemu worker pass an healtcheck job each day and after each job failure, so it is heavily used.
> The healtcheck job is a Linux boot with a stable release.
>
> Since we upgraded our worker to buster, the qemu x86_64 healthcheck randomly panic with:
> <0>[    0.009000] Kernel panic - not syncing: IO-APIC + timer doesn't work!  Boot with apic=debug and send a report.  Then try booting with the 'noapic' option.
>
> After some test I found the source of this kernel panic, the host is
> loaded and qemu run "slower".  Simply renicing all qemu removed this
> behavour.
>
> So now what can I do ?
> Appart renicing qemu process, does something could be done ?

As the qemu timer/ioapic routing is actually sane, you might try to add
"no_timer_check" to the kernel command line.

Thanks,

        tglx