Re: [PATCH 0/3] Drivers: hv: vmbus: fix crashes on hv_vmbus load/unload path

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Vitaly Kuznetsov <vkuznets@redhat.com> writes:

> It is possible (since 93e5bd06a953: "Drivers: hv: Make the vmbus driver
> unloadable") to unload hv_vmbus driver if no other devices are connected.
> 1aec169673d7: "x86: Hyperv: Cleanup the irq mess" fixed doulble interrupt
> gate setup. However, if we try to unload hv_vmbus and then load it back
> crashes in different places of vmbus driver occur on both unload and second
> load paths. Address those I saw in my testing.

It seems that newly introduced clockevent device (Drivers: hv: vmbus:
Implement a clockevent device) makes it impossible to unload hv_vmbus
module:

# rmmod hv_vmbus
rmmod hv_vmbus
rmmod: ERROR: Module hv_vmbus is in use

I'll try investigating before sending v2 without PATCH 2/3.

>
> Not everything is fixed though. MCE was hit once on Generation2 instance and
> I neither understand what caused it nor do I know the way to reproduce it.
> Anyway, here is the log:
>
> [  204.846255] mce: [Hardware Error]: CPU 0: Machine Check Exception: 4 Bank 0: b2000000c0020001
> [  204.846675] mce: [Hardware Error]: TSC 6b5cd64bc8 
> [  204.846675] mce: [Hardware Error]: PROCESSOR 0:306e4 TIME 1421944123 SOCKET 0 APIC 0 microcode ffffffff
> [  204.846675] mce: [Hardware Error]: Run the above through 'mcelog --ascii'
> [  204.846675] mce: [Hardware Error]: Machine check: Processor context corrupt
> [  204.846675] Kernel panic - not syncing: Fatal Machine check
> [  204.846675] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)
> [  204.846675] Rebooting in 30 seconds..
> [  204.846675] ACPI MEMORY or I/O RESET_REG.
>
> Vitaly Kuznetsov (3):
>   Drivers: hv: vmbus: avoid double kfree for device_obj
>   Drivers: hv: vmbus: introduce vmbus_acpi_remove
>   Drivers: hv: vmbus: teardown hv_vmbus_con workqueue and
>     vmbus_connection pages on shutdown
>
>  drivers/hv/channel_mgmt.c |  1 -
>  drivers/hv/connection.c   | 17 ++++++++++++-----
>  drivers/hv/hyperv_vmbus.h |  1 +
>  drivers/hv/vmbus_drv.c    | 16 ++++++++++++++++
>  4 files changed, 29 insertions(+), 6 deletions(-)

-- 
  Vitaly