linux-kernel - Re: [PATCH] x86: Move per cpu cpu_llc_shared_map to a field in struct cpuinfo

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Message-ID: <20120212112306.GA14593@x1.osrc.amd.com>
Date:	Sun, 12 Feb 2012 12:23:06 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Kevin Winchester <kjwinchester@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Randy Dunlap <rdunlap@...otime.net>,
	Nick Bowler <nbowler@...iptictech.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Move per cpu cpu_llc_shared_map to a field in
 struct cpuinfo_x86

On Sat, Feb 11, 2012 at 10:18:53PM -0400, Kevin Winchester wrote:
> > @@ -225,7 +225,6 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
> >        for_each_possible_cpu(i) {
> >                zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
> >                zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
> > -               zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
> >        }
> >        set_cpu_sibling_map(0);
> >
> 
> I just realized that I took out a couple of allocations here for
> cpu_llc_shared_map, without replacing them.  Am I leaving
> cpuinfo_x86.llc_shared_map unallocated then, and just writing to
> whatever address that field happened to get?

AFAICT, yes, you need to alloc the cpumask too, i.e. something like

	zalloc_cpumask_var(cpu_info(i).llc_shared_map, GFP_KERNEL);

assuming this happens before the cpumask gets initted in
set_cpu_sibling_map() et al. Just give the whole init path a hard
staring, and try to figure out the proper init sequence.

HTH.

P.S.: I'm currently travelling but will give your patch a run when I get
back, thanks.

-- 
Regards/Gruss,
Boris.
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