Messages in this thread Patch in this message | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for tearing down vmbus state | Date | Mon, 20 Apr 2015 12:28:41 +0200 |
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Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> "K. Y. Srinivasan" <kys@microsoft.com> writes: > >> Implement the protocol for tearing down the monitor state established with >> the host. >> >> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> > > Unfortunatelly this patch leads to the following crash: > > pre-udev:/# modprobe hv_vmbus > modprobe hv_vmbus > [ 14.832334] hv_vmbus: Hyper-V Host Build:9600-6.3-17-0.17039; Vmbus version:3.0 > [ 14.834179] hv_vmbus: CPU offlining is not supported by hypervisor > pre-udev:/# modprobe -r hv_vmbus > modprobe -r hv_vmbus > [ 20.640893] BUG: unable to handle kernel NULL pointer dereference at (null) > [ 20.641104] IP: [< (null)>] (null) > > I'll try to investigate. >
The problem is that we call vmbus_disconnect() too late in vmbus_exit(). We need to call it: 1) Before hv_cleanup() call as we free hypercall page there (that's what you see in my crash) 2) Before hv_remove_vmbus_irq() as we're waiting for the hypervisor to reply.
This simple patch fixes the issue: diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 7870a90..2b56260 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1106,6 +1106,7 @@ static void __exit vmbus_exit(void) vmbus_connection.conn_state = DISCONNECTED; hv_synic_clockevents_cleanup(); + vmbus_disconnect(); hv_remove_vmbus_irq(); vmbus_free_channels(); if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) { @@ -1118,7 +1119,6 @@ static void __exit vmbus_exit(void) smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1); acpi_bus_unregister_driver(&vmbus_acpi_driver); hv_cpu_hotplug_quirk(false); - vmbus_disconnect(); }
I suggest we incorporate it into your PATCH 5/5. -- Vitaly
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