Re: drm/mtrr: possible deadlock

[Dmitry Vyukov]

On Tue, Aug 15, 2017 at 11:20 AM, Dou Liyang <douly.fnst@xxxxxxxxxxxxxx> wrote:
> Hi Dmitry,
>
> At 08/15/2017 03:18 PM, Dmitry Vyukov wrote:
>>
>> Hello,
>>
>> I am getting the following deadlock report while booting linux-next on
>> 91dfed74eabcdae9378131546c446442c29bf769 in qemu. Config is attached.
>>
>>
>> WARNING: possible recursive locking detected
>> 4.13.0-rc4-next-20170811 #2 Not tainted
>> --------------------------------------------
>> swapper/0/1 is trying to acquire lock:
>>  (cpu_hotplug_lock.rw_sem){++++}, at: [<ffffffff816a19fc>]
>> stop_machine+0x1c/0x40 kernel/stop_machine.c:596
>>
>> but task is already holding lock:
>>  (cpu_hotplug_lock.rw_sem){++++}, at: [<ffffffff812aad6d>]
>> get_online_cpus include/linux/cpu.h:126 [inline]
>>  (cpu_hotplug_lock.rw_sem){++++}, at: [<ffffffff812aad6d>]
>> mtrr_add_page+0x1bd/0xe80 arch/x86/kernel/cpu/mtrr/main.c:328
>>
>
> I guess you may want this.
>
> https://lkml.org/lkml/2017/8/14/7
>
> and the solution by Thomas
>
> https://lkml.org/lkml/2017/8/14/64


Will try that. Thanks!