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Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are online

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On Thu, 2015-10-15 at 21:00 +0200, Laurent Vivier wrote:
> On kexec, all secondary offline CPUs are onlined before
> starting the new kernel, this is not done in the case of kdump.
> 
> If kdump is configured and a kernel crash occurs whereas
> some secondaries CPUs are offline (SMT=off),
> the new kernel is not able to start them and displays some
> "Processor X is stuck.".

Do we know why they are stuck?

I really don't like this fix. The reason we're doing a kdump is because the
first kernel has panicked, possibly with locks held or data structures
corrupted. Calling cpu_up() then goes and tries to run a bunch of code in the
crashed kernel, which increases the chance of us just wedging completely.

cheers


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[PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are online Laurent Vivier <lvivier@redhat.com> - 2015-10-15 21:10 +0200
  Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online kbuild test robot <lkp@intel.com> - 2015-10-16 02:40 +0200
  Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online Michael Ellerman <mpe@ellerman.id.au> - 2015-10-16 04:20 +0200
    Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online Laurent Vivier <lvivier@redhat.com> - 2015-10-16 09:50 +0200
      Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-17 04:10 +0200
  Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online David Gibson <dgibson@redhat.com> - 2015-10-16 04:30 +0200
    Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online Laurent Vivier <lvivier@redhat.com> - 2015-10-16 10:00 +0200
      Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are  online Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-17 04:10 +0200

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