Re: FAILED: patch "[PATCH] x86/Hyper-V: Unload vmbus channel in hv panic callback" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Tue, Apr 21, 2020 at 07:11:27PM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.19-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 74347a99e73ae00b8385f1209aaea193c670f901 Mon Sep 17 00:00:00 2001
>From: Tianyu Lan <Tianyu.Lan@microsoft.com>
>Date: Mon, 6 Apr 2020 08:53:26 -0700
>Subject: [PATCH] x86/Hyper-V: Unload vmbus channel in hv panic callback
>
>When kdump is not configured, a Hyper-V VM might still respond to
>network traffic after a kernel panic when kernel parameter panic=0.
>The panic CPU goes into an infinite loop with interrupts enabled,
>and the VMbus driver interrupt handler still works because the
>VMbus connection is unloaded only in the kdump path.  The network
>responses make the other end of the connection think the VM is
>still functional even though it has panic'ed, which could affect any
>failover actions that should be taken.
>
>Fix this by unloading the VMbus connection during the panic process.
>vmbus_initiate_unload() could then be called twice (e.g., by
>hyperv_panic_event() and hv_crash_handler(), so reset the connection
>state in vmbus_initiate_unload() to ensure the unload is done only
>once.
>
>Fixes: 81b18bce48af ("Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic")
>Reviewed-by: Michael Kelley <mikelley@microsoft.com>
>Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
>Link: https://lore.kernel.org/r/20200406155331.2105-2-Tianyu.Lan@microsoft.com
>Signed-off-by: Wei Liu <wei.liu@kernel.org>

I've dropped the suspend/resume bits as there's no support for that in
4.19.

-- 
Thanks,
Sasha