Re: [External] Re: panic at boot time with kernel >= 4.9.98 - uninitialized system_wq in early interrupt

[Greg KH <greg@kroah.com>]

On Thu, Jun 07, 2018 at 05:54:56PM +0000, Max Asbock wrote:
> 
> ________________________________________
> From: Greg KH [greg@kroah.com]
> Sent: Thursday, June 07, 2018 1:37 AM
> To: Max Asbock
> Cc: stable@vger.kernel.org; tytso@mit.edu; Chris McDermott
> Subject: [External]  Re: panic at boot time with kernel >= 4.9.98 - uninitialized system_wq in early interrupt
> 
> > Ick :(
> 
> > I'm guessing you also see these problems on 4.17?  Can you test there to
> > be sure of that?
> 
> We haven't had a chance to test 4.17 on the system where this happens. I am suspecting this won't be a problem on 4.17 as workqueue init has been split up and there is now a workqueue_init_early() in start_kernel():
>     /*
>      * Allow workqueue creation and work item queueing/cancelling
>      * early.  Work item execution depends on kthreads and starts after
>      * workqueue_init().
>      */
>     workqueue_init_early();
> 
> So far we have only seen this with 4.9.x. Also, this only happens when lots of memory is installed (10TB). i am guessing the large memory size changes the timing of the initialization steps and brings out the problem.
> When we get access to the system again we can attempt to boot the latest main-line kernel to verify that the work_init_early indeed fixes the issue there.

Ugh, I forgot about the workqueue rewrite.

How about 4.14, does that work for you?  If so, just use that, you
shouldn't be using the 4.9 kernel tree on x86-based hardware unless you
are somehow forced to due to horrible closed source kernel drivers.  You
want and need the fixes and speedups that are on 4.14.y, it's a
measurable difference.

thanks,

greg k-h