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Re: 4.2.2: NR_CPUS effectively being 1 bug

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On Fri, 2 Oct 2015 23:46:59 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:

> FYI, I've upgraded from 4.1.7 to 4.2.1 (and retested with 4.2.2) and
> everything is scheduled on 1 CPU out of 4 (i5 760).
> 
> 	$ sudo cat /proc/1/status | grep cpu -i
> 	Cpus_allowed:   1
> 	Cpus_allowed_list:      0
> 
> Every process inherits this tiny cpumask.

Sell the other CPUs on ebay?

I haven't seen such a report before - maybe it rings a bell with Peter
& Ingo?

It should be pretty easy to debug.  I'd guess that the problem is in
the area of x86 SMP bringup and there might even be a nasty message in
the dmesg explaining what went wrong?

> #
> # Automatically generated file; DO NOT EDIT.
> # Linux/x86 4.2.2 Kernel Configuration
> #
> CONFIG_64BIT=y
> ...
>
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Re: 4.2.2: NR_CPUS effectively being 1 bug Andrew Morton <akpm@linux-foundation.org> - 2015-10-02 23:10 +0200
  Re: 4.2.2: NR_CPUS effectively being 1 bug Peter Zijlstra <peterz@infradead.org> - 2015-10-03 09:00 +0200
    Re: 4.2.2: NR_CPUS effectively being 1 bug Ingo Molnar <mingo@kernel.org> - 2015-10-03 09:40 +0200
      Re: 4.2.2: NR_CPUS effectively being 1 bug Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-10-03 10:20 +0200
        Re: 4.2.2: NR_CPUS effectively being 1 bug Ingo Molnar <mingo@kernel.org> - 2015-10-03 10:20 +0200
          Re: 4.2.2: NR_CPUS effectively being 1 bug Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-10-03 10:30 +0200
            Re: 4.2.2: NR_CPUS effectively being 1 bug Ingo Molnar <mingo@kernel.org> - 2015-10-03 11:00 +0200
              Re: 4.2.2: NR_CPUS effectively being 1 bug Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-10-03 14:10 +0200
                Re: 4.2.2: NR_CPUS effectively being 1 bug Frederic Weisbecker <fweisbec@gmail.com> - 2015-10-03 14:40 +0200
                Re: 4.2.2: NR_CPUS effectively being 1 bug Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-10-03 14:50 +0200
        Re: 4.2.2: NR_CPUS effectively being 1 bug Alexey Dobriyan <adobriyan@gmail.com> - 2015-10-03 14:20 +0200
          Re: 4.2.2: NR_CPUS effectively being 1 bug Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-10-03 14:30 +0200

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