Re: [RFC PATCH v3 1/3] powerpc: Fix warning reported by verify_cpu_node_mapping()

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2014-10-02 at 14:13 -0700, Nishanth Aravamudan wrote:
> Ben & Michael,
> 
> What's the status of these patches?

Waiting for somebody to review them ? :-)

Cheers,
Ben.

> Thanks,
> Nish
> 
> On 27.08.2014 [17:33:59 +0800], Li Zhong wrote:
> > With commit 2fabf084b6ad ("powerpc: reorder per-cpu NUMA information's
> > initialization"), during boottime, cpu_numa_callback() is called
> > earlier(before their online) for each cpu, and verify_cpu_node_mapping()
> > uses cpu_to_node() to check whether siblings are in the same node.
> > 
> > It skips the checking for siblings that are not online yet. So the only
> > check done here is for the bootcpu, which is online at that time. But
> > the per-cpu numa_node cpu_to_node() uses hasn't been set up yet (which
> > will be set up in smp_prepare_cpus()).
> > 
> > So I saw something like following reported:
> > [    0.000000] CPU thread siblings 1/2/3 and 0 don't belong to the same
> > node!
> > 
> > As we don't actually do the checking during this early stage, so maybe
> > we could directly call numa_setup_cpu() in do_init_bootmem().
> > 
> > Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> > Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > ---
> >  arch/powerpc/mm/numa.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index d7737a5..9918c02 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -1128,8 +1128,7 @@ void __init do_init_bootmem(void)
> >  	 * early in boot, cf. smp_prepare_cpus().
> >  	 */
> >  	for_each_possible_cpu(cpu) {
> > -		cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
> > -				  (void *)(unsigned long)cpu);
> > +		numa_setup_cpu((unsigned long)cpu);
> >  	}
> >  }
> > 
> > -- 
> > 1.9.1
> >