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.