Re: assert/crash in __rmqueue() when enabling CONFIG_NUMA

["Martin J. Bligh" <mbligh@mbligh.org>]

>>>>Bollocks. It works fine,
>>>
>>>On what kind of box? Some summit system, right?
>>
>>Summit and NUMA-Q, ie everything we originally created it for.
>
> Andi:
>
> That's my point - it usually crashes everywhere else.

Ingo Molnar wrote:
>
> i only booted it on a non-NUMA PC. Most likely the instability is
> caused by some sort of zone mis-sizing. (See more details in this
> same thread.)

Ooooh, on ordinary PCs. that makes more sense.

> The problem is that it's not regression tested and quite complex and 
> tends to break often and stay broken.

OK, well the regression testing issue is easily fixed, but whether it's
worth it or not is a different issue. It was originally done for the
distros really, so they could have a single kernel that supported
everything.

> If you don't want to mark it CONFIG_BROKEN then i would suggest a panic
> early when the system isn't SUMMIT (I think NUMAQ does this already)
>
> Something like the appended patch

apw: this was your baby ... what do you want to do with it? Add it
to the automated regression testing, or kill it?

> -Andi
>
> i386: Panic the system early when a NUMA kernel doesn't run on IBM NUMA
>
> It has been broken forever anywhere else and is not too useful
> anyways so best to disable it.
>
> Signed-off-by: Andi Kleen <ak@suse.de>
>
> Index: linux/arch/i386/kernel/srat.c
> ===================================================================
> --- linux.orig/arch/i386/kernel/srat.c
> +++ linux/arch/i386/kernel/srat.c
> @@ -327,6 +327,14 @@ int __init get_memcfg_from_srat(void)
>  	int tables = 0;
>  	int i = 0;
>  
> +	extern int use_cyclone;
> +	if (use_cyclone == 0) {
> +		/* Make sure user sees something */
> +		static const char s[] __initdata = "Not an IBM x440/NUMAQ. Don't use i386 CONFIG_NUMA anywhere else."
> +		early_printk(s);
> +		panic(s); 
> +	}
> +
>  	if (ACPI_FAILURE(acpi_find_root_pointer(ACPI_PHYSICAL_ADDRESSING,
>  						rsdp_address))) {
>  		printk("%s: System description tables not found\n",
> Index: linux/arch/i386/Kconfig
> ===================================================================
> --- linux.orig/arch/i386/Kconfig
> +++ linux/arch/i386/Kconfig
> @@ -517,6 +517,9 @@ config NUMA
>  	depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
>  	default n if X86_PC
>  	default y if (X86_NUMAQ || X86_SUMMIT)
> +	help
> +		NUMA support. Note this only works on IBM x440 or IBM NUMAQ.
> +		Don't try to use it anywhere else.
>  
>  comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
>  	depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
-
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