Re: 4.5.0+ panic when setup loop device

[Mike Galbraith <umgwanakikbuti@gmail.com>]

On Fri, 2016-03-18 at 14:32 +0100, Peter Zijlstra wrote:
> On Fri, Mar 18, 2016 at 01:39:16PM +0100, Mike Galbraith wrote:
> > On Fri, 2016-03-18 at 11:15 +0100, Peter Zijlstra wrote:
> 
> > > Ah, did you actually disable HT in the BIOS, or just skip the HT
> > > enumeration by saying nr_cpus=64 (knowing that all the siblings are
> > > last)?
> > 
> > It's disabled in BIOS.
> 
> OK, so I disabled HT in the BIOS too, on my IVB-EX
> 
> > > In any case, Thomas has a clue and I'm going to test, but 4 socket
> > > machine takes forever to boot, so might be a few minutes :/
> > 
> > His one-liner made my DL980 all better.
> 
> My machine is profoundly unhappy though; and since I have no nr_cpus=
> nr_cpu_ids == total_cpus and his patch wouldn't do anything anyway.
> 
> [    0.286838] max_cores: 15, cpu_ids: 60, num_siblings: 2, coreid_bits: 5
> [    0.293463] smpboot: Max logical packages: 2
> [    0.297733] smpboot: APIC(0) Converting physical 0 to logical package 0
> [    0.304346] smpboot: APIC(20) Converting physical 1 to logical package 1
> [    0.311047] smpboot: APIC(40) Package 2 exceeds logical package map
> [    0.317309] smpboot: CPU 30 APICId 40 disabled
> [    0.321757] smpboot: APIC(60) Package 3 exceeds logical package map
> [    0.328022] smpboot: CPU 45 APICId 60 disabled
> 
> This machine does exactly what I suspected yours did.

Yup, that looks very familiar.  I just booted without nr_cpus=64 to
make sure it's a happy camper both w/wo, and it says all is peachy.

	-Mike