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Date: Fri, 18 Sep 2009 09:35:31 -0700
From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Yinghai Lu <yinghai@kernel.org>
Cc: David Rientjes <rientjes@google.com>,
       Suresh Jayaram <sureshjayaram@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>, mm-commits@vger.kernel.org,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Jesse Brandeburg <jesse.brandeburg@gmail.com>
Subject: Re: mmotm 2009-09-09-22-56 uploaded
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On Fri, 18 Sep 2009 09:27:33 -0700
Yinghai Lu <yinghai@kernel.org> wrote:

> David Rientjes wrote:
> > On Fri, 18 Sep 2009, David Rientjes wrote:
> > 
> >> This seems to be related to 2547089 "x86/PCI: initialize PCI bus
> >> node numbers early" since cpumask_of_pcibus() on x86 doesn't check
> >> for -1 pcibus_to_node() like most other architectures.  It'll
> >> simply index into cpumask_of_node for whatever the pci_sysdata's
> >> node is, and in this case that's -1.
> >>
> > 
> > Suresh, could you give this patch a try?  It turns out that the 
> > mp_bus_to_node map simply leaves all busses that don't have memory 
> > affinity to -1, so cpu_online_mask is actually the appropriate
> > cpumask to return and x86 doesn't catch this.
> > 
> > 
> > x86: default pcibus cpumask to all cpus if it lacks affinity
> > 
> > The early initialization of the pci bus to node mapping leaves all
> > busses with a node id of -1 if it lacks memory affinity.  Thus,
> > cpumask_of_pcibus must return all online cpus for such busses.
> > 
> > Signed-off-by: David Rientjes <rientjes@google.com>
> > ---
> >  arch/x86/include/asm/pci.h |    6 +++++-
> >  1 files changed, 5 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
> > --- a/arch/x86/include/asm/pci.h
> > +++ b/arch/x86/include/asm/pci.h
> > @@ -143,7 +143,11 @@ static inline int __pcibus_to_node(const
> > struct pci_bus *bus) static inline const struct cpumask *
> >  cpumask_of_pcibus(const struct pci_bus *bus)
> >  {
> > -	return cpumask_of_node(__pcibus_to_node(bus));
> > +	int node;
> > +
> > +	node = __pcibus_to_node(bus);
> > +	return (node == -1) ? cpu_online_mask :
> > +			      cpumask_of_node(node);
> >  }
> >  #endif
> >  
> 
> looks right, but we should use nearby_node or local cpu node instead
> of cpu_online_mask...

There is no nearby node.  That's why node is -1.

-- 
Jesse Barnes, Intel Open Source Technology Center
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