Re: [PATCH][RT] x86: Fix an RT MCE crash

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 07/06/2016 03:32 PM, Steven Rostedt wrote:
> On Wed, 6 Jul 2016 07:03:43 -0500
> Corey Minyard <cminyard@mvista.com> wrote:
> 
>>> ---
>>> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
>>> index aaf4b9b94f38..cc70d98a30f6 100644
>>> --- a/arch/x86/kernel/cpu/mcheck/mce.c
>>> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
>>> @@ -1391,7 +1391,8 @@ static int mce_notify_work_init(void)
>>>   
>>>   static void mce_notify_work(void)
>>>   {
>>> -	wake_up_process(mce_notify_helper);
>>> +	if (mce_notify_helper)
>>> +		wake_up_process(mce_notify_helper);
>>>   }
> 
> Actually, this appears to be the fix in 4.6-rt.

This is in there since it was switched to swork instead of using its
own thread and is also in v4.1:

https://git.kernel.org/cgit/linux/kernel/git/rt/linux-rt-devel.git/tree/arch/x86/kernel/cpu/mcheck/mce.c?h=linux-4.1.y-rt#n1387

as part of x86-mce-use-swait-queue-for-mce-wakeups.patch. And this
patch was first part of v3.18.9-rt4 as a new patch dropping x86-mce-
Defer-mce-wakeups-to-threads-for-PREEMPT_RT.patch.

> -- Steve

Sebastian