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Date:   Mon, 4 Jun 2018 13:17:48 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Dou Liyang <douly.fnst@cn.fujitsu.com>
cc:     Song Liu <songliubraving@fb.com>,
        Song Liu <liu.song.a23@gmail.com>,
        Tariq Toukan <tariqt@mellanox.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        Maor Gottlieb <maorg@mellanox.com>,
        Kernel Team <Kernel-team@fb.com>
Subject: Re: WARNING and PANIC in irq_matrix_free
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On Mon, 4 Jun 2018, Dou Liyang wrote:
> Here, why didn't we avoid this cleanup by
> 
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index a75de0792942..0cc59646755f 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -821,6 +821,9 @@ static void free_moved_vector(struct apic_chip_data
> *apicd)
>          */
>         WARN_ON_ONCE(managed);
> 
> +       if (!vector)
> +               return;
> +
>         trace_vector_free_moved(apicd->irq, cpu, vector, managed);
>         irq_matrix_free(vector_matrix, cpu, vector, managed);
>         per_cpu(vector_irq, cpu)[vector] = VECTOR_UNUSED;
> 
> Is there something I didn't consider with? ;-)

Well, that just prevents the warning, but the hlist is already
corrupted. So you'd just cure the symptom ...

I'm about to send a patch series which addresses that. Just need to finish
writing changelogs.

Thanks,

	tglx