Re: 2.6.13-mm1

Zwane Mwaikambo
2005-09-02T14:40:47Z

On Fri, 2 Sep 2005, Alexander Nyberg wrote:

> On Thu, Sep 01, 2005 at 03:55:42AM -0700 Andrew Morton wrote:
>
> >
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.13/2.6.13-mm1/
> >
>
> i386-boottime-for_each_cpu-broken.patch
> i386-boottime-for_each_cpu-broken-fix.patch
>
> The SMP version of __alloc_percpu checks the cpu_possible_map
> before allocating memory for a certain cpu. With the above patches
> the BSP cpuid is never set in cpu_possible_map which breaks CONFIG_SMP
> on uniprocessor machines (as soon as someone tries to dereference
> something allocated via __alloc_percpu, which in fact is never allocated
> since the cpu is not set in cpu_possible_map).

Yes indeed, if there is no mptable or madt we would have missed setting
it.

> The below fixes this, I'm not entirely sure about the voyager
> part, should the cpu_possible_map really be CPU_MASK_ALL to begin
> with there, Zwane?

I wanted to avoid breaking it wholesale and since i don't entirely
understand the voyager SMP boot sequence, i opted for the safe method.
cpu_possible_map is fine because it's supposed to cover all possible
processors, upto NR_CPUS.

> Signed-off-by: Alexander Nyberg <alexn@telia.com>

Thanks Alex,

Acked-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>

> Index: mm/arch/i386/kernel/smpboot.c
> ===================================================================
> --- mm.orig/arch/i386/kernel/smpboot.c 2005-09-02 15:28:20.000000000 +0200
> +++ mm/arch/i386/kernel/smpboot.c 2005-09-02 16:16:46.000000000 +0200
> @@ -1265,6 +1265,7 @@
> cpu_set(smp_processor_id(), cpu_online_map);
> cpu_set(smp_processor_id(), cpu_callout_map);
> cpu_set(smp_processor_id(), cpu_present_map);
> + cpu_set(smp_processor_id(), cpu_possible_map);
> per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
> }
>
> Index: mm/arch/i386/mach-voyager/voyager_smp.c
> ===================================================================
> --- mm.orig/arch/i386/mach-voyager/voyager_smp.c 2005-09-02 15:28:20.000000000 +0200
> +++ mm/arch/i386/mach-voyager/voyager_smp.c 2005-09-02 16:17:29.000000000 +0200
> @@ -1910,6 +1910,7 @@
> {
> cpu_set(smp_processor_id(), cpu_online_map);
> cpu_set(smp_processor_id(), cpu_callout_map);
> + cpu_set(smp_processor_id(), cpu_possible_map);
> }
>
> int __devinit
> -
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