linux-kernel - Re: [PATCH 1/1] Drivers: hv: vmbus: Only notify Hyper-V for die events that are oops

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Message-ID: <87o8nmome0.fsf@vitty.brq.redhat.com>
Date:   Fri, 07 Aug 2020 11:06:47 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     mikelley@...rosoft.com, linux-kernel@...r.kernel.org,
        kys@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        linux-hyperv@...r.kernel.org
Subject: Re: [PATCH 1/1] Drivers: hv: vmbus: Only notify Hyper-V for die events that are oops

Michael Kelley <mikelley@...rosoft.com> writes:

> Hyper-V currently may be notified of a panic for any die event. But
> this results in false panic notifications for various user space traps
> that are die events. Fix this by ignoring die events that aren't oops.
>
> Fixes: 510f7aef65bb ("Drivers: hv: vmbus: prefer 'die' notification chain to 'panic'")
> Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
> ---
>  drivers/hv/vmbus_drv.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index b50081c..910b6e9 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -86,6 +86,10 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
>  	struct die_args *die = (struct die_args *)args;
>  	struct pt_regs *regs = die->regs;
>  
> +	/* Don't notify Hyper-V if the die event is other than oops */
> +	if (val != DIE_OOPS)
> +		return NOTIFY_DONE;
> +

Looking at die_val enum, DIE_PANIC also sounds like something we would
want to report but it doesn't get emitted anywhere and honestly I don't
quite understand how is was supposed to be different from DIE_OOPS.

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

>  	/*
>  	 * Hyper-V should be notified only once about a panic.  If we will be
>  	 * doing hyperv_report_panic_msg() later with kmsg data, don't do

-- 
Vitaly