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Re: 4.5.0+ panic when setup loop device

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On Fri, Mar 18, 2016 at 05:11:54AM +0100, Mike Galbraith wrote:
> On Thu, 2016-03-17 at 10:52 +0100, Peter Zijlstra wrote:
> 
> > Andreas; Borislav said to Cc you since you wrote all this.
> > The issue is that Linux assumes:
> > 
> > 	> nr_logical_cpus = nr_cores * nr_siblings
> 
> It also seems to now assume that if SMT is possible, it's enabled.
> 
> Below is my 8 socket DL980 G7, which has SMT turned off for RT testing,
> booting NOPREEMPT master tuned for maximum bloat ala distro and getting
> confused by me telling it (as always) nr_cpus=64.  Bad juju ensues.

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)?

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 :/

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Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-16 16:30 +0100
  Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-17 11:00 +0100
  Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-17 11:00 +0100
    Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 11:30 +0100
      Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-17 11:30 +0100
        Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 12:50 +0100
          Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-17 13:00 +0100
            Re: 4.5.0+ panic when setup loop device Borislav Petkov <bp@alien8.de> - 2016-03-17 13:00 +0100
            Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 13:10 +0100
              Re: 4.5.0+ panic when setup loop device Jens Axboe <axboe@kernel.dk> - 2016-03-17 17:50 +0100
                Re: 4.5.0+ panic when setup loop device Jens Axboe <axboe@kernel.dk> - 2016-03-17 19:30 +0100
                Re: 4.5.0+ panic when setup loop device Jens Axboe <axboe@kernel.dk> - 2016-03-17 21:30 +0100
                Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 21:40 +0100
                Re: 4.5.0+ panic when setup loop device Jens Axboe <axboe@kernel.dk> - 2016-03-17 21:50 +0100
                Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 21:30 +0100
          Re: 4.5.0+ panic when setup loop device Xiong Zhou <jencce.kernel@gmail.com> - 2016-03-18 03:40 +0100
    Re: 4.5.0+ panic when setup loop device Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-03-18 05:20 +0100
      Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-18 09:00 +0100
      Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-18 11:20 +0100
        Re: 4.5.0+ panic when setup loop device Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-03-18 13:40 +0100
          Re: 4.5.0+ panic when setup loop device Peter Zijlstra <peterz@infradead.org> - 2016-03-18 14:40 +0100
            Re: 4.5.0+ panic when setup loop device Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-03-18 15:10 +0100
      Re: 4.5.0+ panic when setup loop device Thomas Gleixner <tglx@linutronix.de> - 2016-03-18 13:00 +0100
        Re: 4.5.0+ panic when setup loop device Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-03-18 13:50 +0100
        [tip:x86/urgent] x86/topology: Use total_cpus not nr_cpu_ids for  logical packages tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-03-19 10:40 +0100
    [tip:x86/urgent] x86/topology: Fix AMD core count tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2016-03-29 10:50 +0200

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