Re: [PATCH] Bugfix for system with 32 cpus

[Robin Holt <holt@sgi.com>]

Acked-by: Robin Holt <holt@sgi.com>

Sorry for the bug,
Robin

On Fri, Jun 27, 2008 at 03:30:20PM -0700, Luck, Tony wrote:
> commit 180f2319663d6aece02fc0284a02944ad2cc7c98
> Author: Tony Luck <tony.luck@intel.com>
> Date:   Fri Jun 27 14:04:21 2008 -0700
> 
>     [IA64] Bugfix for system with 32 cpus
> 
>     On a system where there are no hot pluggable cpus "additional_cpus"
>     is still set to -1 at the point where we call per_cpu_scan_finalize().
>     If we didn't find an SRAT table and so pick the default "32" for the
>     number of cpus, when we get to:
>         high_cpu = min(high_cpu + reserve_cpus, NR_CPUS);
>     we will end up initializing for just 31 cpus ... and so we will
>     die horribly when bringing up cpu#32.
> 
>     Problem introduced by: 2c6e6db41f01b6b4eb98809350827c9678996698
>     "Minimize per_cpu reservations."
> 
>     Signed-off-by: Tony Luck <tony.luck@intel.com>
> 
> diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
> index 4ae15c8..632cda8 100644
> --- a/arch/ia64/kernel/setup.c
> +++ b/arch/ia64/kernel/setup.c
> @@ -547,7 +547,8 @@ setup_arch (char **cmdline_p)
>  # ifdef CONFIG_ACPI_NUMA
>         acpi_numa_init();
>         per_cpu_scan_finalize((cpus_weight(early_cpu_possible_map) = 0 ?
> -               32 : cpus_weight(early_cpu_possible_map)), additional_cpus);
> +               32 : cpus_weight(early_cpu_possible_map)),
> +               additional_cpus > 0 ? additional_cpus : 0);
>  # endif
>  #else
>  # ifdef CONFIG_SMP
> 
> 
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